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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
4 | * operating system. INET is implemented using the BSD Socket | |
5 | * interface as the means of communication with the user level. | |
6 | * | |
7 | * Implementation of the Transmission Control Protocol(TCP). | |
8 | * | |
02c30a84 | 9 | * Authors: Ross Biro |
1da177e4 LT |
10 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
11 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
12 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
13 | * Florian La Roche, <flla@stud.uni-sb.de> | |
14 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
15 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
16 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
17 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
18 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
19 | * Jorge Cwik, <jorge@laser.satlink.net> | |
20 | */ | |
21 | ||
22 | /* | |
23 | * Changes: Pedro Roque : Retransmit queue handled by TCP. | |
24 | * : Fragmentation on mtu decrease | |
25 | * : Segment collapse on retransmit | |
26 | * : AF independence | |
27 | * | |
28 | * Linus Torvalds : send_delayed_ack | |
29 | * David S. Miller : Charge memory using the right skb | |
30 | * during syn/ack processing. | |
31 | * David S. Miller : Output engine completely rewritten. | |
32 | * Andrea Arcangeli: SYNACK carry ts_recent in tsecr. | |
33 | * Cacophonix Gaul : draft-minshall-nagle-01 | |
34 | * J Hadi Salim : ECN support | |
35 | * | |
36 | */ | |
37 | ||
91df42be JP |
38 | #define pr_fmt(fmt) "TCP: " fmt |
39 | ||
1da177e4 | 40 | #include <net/tcp.h> |
eda7acdd | 41 | #include <net/mptcp.h> |
1da177e4 LT |
42 | |
43 | #include <linux/compiler.h> | |
5a0e3ad6 | 44 | #include <linux/gfp.h> |
1da177e4 | 45 | #include <linux/module.h> |
60e2a778 | 46 | #include <linux/static_key.h> |
1da177e4 | 47 | |
e086101b | 48 | #include <trace/events/tcp.h> |
35089bb2 | 49 | |
9799ccb0 ED |
50 | /* Refresh clocks of a TCP socket, |
51 | * ensuring monotically increasing values. | |
52 | */ | |
53 | void tcp_mstamp_refresh(struct tcp_sock *tp) | |
54 | { | |
55 | u64 val = tcp_clock_ns(); | |
56 | ||
e6d14070 ED |
57 | tp->tcp_clock_cache = val; |
58 | tp->tcp_mstamp = div_u64(val, NSEC_PER_USEC); | |
9799ccb0 ED |
59 | } |
60 | ||
46d3ceab ED |
61 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
62 | int push_one, gfp_t gfp); | |
519855c5 | 63 | |
67edfef7 | 64 | /* Account for new data that has been sent to the network. */ |
75c119af | 65 | static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb) |
1da177e4 | 66 | { |
6ba8a3b1 | 67 | struct inet_connection_sock *icsk = inet_csk(sk); |
9e412ba7 | 68 | struct tcp_sock *tp = tcp_sk(sk); |
66f5fe62 | 69 | unsigned int prior_packets = tp->packets_out; |
9e412ba7 | 70 | |
e0d694d6 | 71 | WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(skb)->end_seq); |
8512430e | 72 | |
75c119af ED |
73 | __skb_unlink(skb, &sk->sk_write_queue); |
74 | tcp_rbtree_insert(&sk->tcp_rtx_queue, skb); | |
75 | ||
85369750 CZ |
76 | if (tp->highest_sack == NULL) |
77 | tp->highest_sack = skb; | |
78 | ||
66f5fe62 | 79 | tp->packets_out += tcp_skb_pcount(skb); |
bec41a11 | 80 | if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) |
750ea2ba | 81 | tcp_rearm_rto(sk); |
f19c29e3 | 82 | |
f7324acd DM |
83 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT, |
84 | tcp_skb_pcount(skb)); | |
4bfe744f | 85 | tcp_check_space(sk); |
1da177e4 LT |
86 | } |
87 | ||
a4ecb15a CC |
88 | /* SND.NXT, if window was not shrunk or the amount of shrunk was less than one |
89 | * window scaling factor due to loss of precision. | |
1da177e4 LT |
90 | * If window has been shrunk, what should we make? It is not clear at all. |
91 | * Using SND.UNA we will fail to open window, SND.NXT is out of window. :-( | |
92 | * Anything in between SND.UNA...SND.UNA+SND.WND also can be already | |
93 | * invalid. OK, let's make this for now: | |
94 | */ | |
cf533ea5 | 95 | static inline __u32 tcp_acceptable_seq(const struct sock *sk) |
1da177e4 | 96 | { |
cf533ea5 | 97 | const struct tcp_sock *tp = tcp_sk(sk); |
9e412ba7 | 98 | |
a4ecb15a CC |
99 | if (!before(tcp_wnd_end(tp), tp->snd_nxt) || |
100 | (tp->rx_opt.wscale_ok && | |
101 | ((tp->snd_nxt - tcp_wnd_end(tp)) < (1 << tp->rx_opt.rcv_wscale)))) | |
1da177e4 LT |
102 | return tp->snd_nxt; |
103 | else | |
90840def | 104 | return tcp_wnd_end(tp); |
1da177e4 LT |
105 | } |
106 | ||
107 | /* Calculate mss to advertise in SYN segment. | |
108 | * RFC1122, RFC1063, draft-ietf-tcpimpl-pmtud-01 state that: | |
109 | * | |
110 | * 1. It is independent of path mtu. | |
111 | * 2. Ideally, it is maximal possible segment size i.e. 65535-40. | |
112 | * 3. For IPv4 it is reasonable to calculate it from maximal MTU of | |
113 | * attached devices, because some buggy hosts are confused by | |
114 | * large MSS. | |
115 | * 4. We do not make 3, we advertise MSS, calculated from first | |
116 | * hop device mtu, but allow to raise it to ip_rt_min_advmss. | |
117 | * This may be overridden via information stored in routing table. | |
118 | * 5. Value 65535 for MSS is valid in IPv6 and means "as large as possible, | |
119 | * probably even Jumbo". | |
120 | */ | |
121 | static __u16 tcp_advertise_mss(struct sock *sk) | |
122 | { | |
123 | struct tcp_sock *tp = tcp_sk(sk); | |
cf533ea5 | 124 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
125 | int mss = tp->advmss; |
126 | ||
0dbaee3b DM |
127 | if (dst) { |
128 | unsigned int metric = dst_metric_advmss(dst); | |
129 | ||
130 | if (metric < mss) { | |
131 | mss = metric; | |
132 | tp->advmss = mss; | |
133 | } | |
1da177e4 LT |
134 | } |
135 | ||
136 | return (__u16)mss; | |
137 | } | |
138 | ||
139 | /* RFC2861. Reset CWND after idle period longer RTO to "restart window". | |
6f021c62 ED |
140 | * This is the first part of cwnd validation mechanism. |
141 | */ | |
142 | void tcp_cwnd_restart(struct sock *sk, s32 delta) | |
1da177e4 | 143 | { |
463c84b9 | 144 | struct tcp_sock *tp = tcp_sk(sk); |
6f021c62 | 145 | u32 restart_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk)); |
40570375 | 146 | u32 cwnd = tcp_snd_cwnd(tp); |
1da177e4 | 147 | |
6687e988 | 148 | tcp_ca_event(sk, CA_EVENT_CWND_RESTART); |
1da177e4 | 149 | |
6687e988 | 150 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
1da177e4 LT |
151 | restart_cwnd = min(restart_cwnd, cwnd); |
152 | ||
463c84b9 | 153 | while ((delta -= inet_csk(sk)->icsk_rto) > 0 && cwnd > restart_cwnd) |
1da177e4 | 154 | cwnd >>= 1; |
40570375 | 155 | tcp_snd_cwnd_set(tp, max(cwnd, restart_cwnd)); |
c2203cf7 | 156 | tp->snd_cwnd_stamp = tcp_jiffies32; |
1da177e4 LT |
157 | tp->snd_cwnd_used = 0; |
158 | } | |
159 | ||
67edfef7 | 160 | /* Congestion state accounting after a packet has been sent. */ |
40efc6fa | 161 | static void tcp_event_data_sent(struct tcp_sock *tp, |
cf533ea5 | 162 | struct sock *sk) |
1da177e4 | 163 | { |
463c84b9 | 164 | struct inet_connection_sock *icsk = inet_csk(sk); |
d635fbe2 | 165 | const u32 now = tcp_jiffies32; |
1da177e4 | 166 | |
05c5a46d NC |
167 | if (tcp_packets_in_flight(tp) == 0) |
168 | tcp_ca_event(sk, CA_EVENT_TX_START); | |
169 | ||
4a41f453 | 170 | tp->lsndtime = now; |
4d8f24ee WW |
171 | |
172 | /* If it is a reply for ato after last received | |
173 | * packet, enter pingpong mode. | |
174 | */ | |
175 | if ((u32)(now - icsk->icsk_ack.lrcvtime) < icsk->icsk_ack.ato) | |
176 | inet_csk_enter_pingpong_mode(sk); | |
1da177e4 LT |
177 | } |
178 | ||
67edfef7 | 179 | /* Account for an ACK we sent. */ |
27cde44a YC |
180 | static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts, |
181 | u32 rcv_nxt) | |
1da177e4 | 182 | { |
5d9f4262 ED |
183 | struct tcp_sock *tp = tcp_sk(sk); |
184 | ||
2b195850 | 185 | if (unlikely(tp->compressed_ack)) { |
200d95f4 | 186 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPACKCOMPRESSED, |
2b195850 ED |
187 | tp->compressed_ack); |
188 | tp->compressed_ack = 0; | |
5d9f4262 ED |
189 | if (hrtimer_try_to_cancel(&tp->compressed_ack_timer) == 1) |
190 | __sock_put(sk); | |
191 | } | |
27cde44a YC |
192 | |
193 | if (unlikely(rcv_nxt != tp->rcv_nxt)) | |
194 | return; /* Special ACK sent by DCTCP to reflect ECN */ | |
463c84b9 ACM |
195 | tcp_dec_quickack_mode(sk, pkts); |
196 | inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); | |
1da177e4 LT |
197 | } |
198 | ||
199 | /* Determine a window scaling and initial window to offer. | |
200 | * Based on the assumption that the given amount of space | |
201 | * will be offered. Store the results in the tp structure. | |
202 | * NOTE: for smooth operation initial space offering should | |
203 | * be a multiple of mss if possible. We assume here that mss >= 1. | |
204 | * This MUST be enforced by all callers. | |
205 | */ | |
ceef9ab6 | 206 | void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss, |
1da177e4 | 207 | __u32 *rcv_wnd, __u32 *window_clamp, |
31d12926 | 208 | int wscale_ok, __u8 *rcv_wscale, |
209 | __u32 init_rcv_wnd) | |
1da177e4 LT |
210 | { |
211 | unsigned int space = (__space < 0 ? 0 : __space); | |
212 | ||
213 | /* If no clamp set the clamp to the max possible scaled window */ | |
214 | if (*window_clamp == 0) | |
589c49cb | 215 | (*window_clamp) = (U16_MAX << TCP_MAX_WSCALE); |
1da177e4 LT |
216 | space = min(*window_clamp, space); |
217 | ||
218 | /* Quantize space offering to a multiple of mss if possible. */ | |
219 | if (space > mss) | |
589c49cb | 220 | space = rounddown(space, mss); |
1da177e4 LT |
221 | |
222 | /* NOTE: offering an initial window larger than 32767 | |
15d99e02 RJ |
223 | * will break some buggy TCP stacks. If the admin tells us |
224 | * it is likely we could be speaking with such a buggy stack | |
225 | * we will truncate our initial window offering to 32K-1 | |
226 | * unless the remote has sent us a window scaling option, | |
227 | * which we interpret as a sign the remote TCP is not | |
228 | * misinterpreting the window field as a signed quantity. | |
1da177e4 | 229 | */ |
0f1e4d06 | 230 | if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)) |
15d99e02 RJ |
231 | (*rcv_wnd) = min(space, MAX_TCP_WINDOW); |
232 | else | |
a337531b YC |
233 | (*rcv_wnd) = min_t(u32, space, U16_MAX); |
234 | ||
235 | if (init_rcv_wnd) | |
236 | *rcv_wnd = min(*rcv_wnd, init_rcv_wnd * mss); | |
15d99e02 | 237 | |
19bf6261 | 238 | *rcv_wscale = 0; |
1da177e4 | 239 | if (wscale_ok) { |
589c49cb | 240 | /* Set window scaling on max possible window */ |
02739545 | 241 | space = max_t(u32, space, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); |
1227c177 | 242 | space = max_t(u32, space, READ_ONCE(sysctl_rmem_max)); |
316c1592 | 243 | space = min_t(u32, space, *window_clamp); |
19bf6261 ED |
244 | *rcv_wscale = clamp_t(int, ilog2(space) - 15, |
245 | 0, TCP_MAX_WSCALE); | |
1da177e4 | 246 | } |
1da177e4 | 247 | /* Set the clamp no higher than max representable value */ |
589c49cb | 248 | (*window_clamp) = min_t(__u32, U16_MAX << (*rcv_wscale), *window_clamp); |
1da177e4 | 249 | } |
4bc2f18b | 250 | EXPORT_SYMBOL(tcp_select_initial_window); |
1da177e4 LT |
251 | |
252 | /* Chose a new window to advertise, update state in tcp_sock for the | |
253 | * socket, and return result with RFC1323 scaling applied. The return | |
254 | * value can be stuffed directly into th->window for an outgoing | |
255 | * frame. | |
256 | */ | |
40efc6fa | 257 | static u16 tcp_select_window(struct sock *sk) |
1da177e4 LT |
258 | { |
259 | struct tcp_sock *tp = tcp_sk(sk); | |
8e165e20 | 260 | u32 old_win = tp->rcv_wnd; |
1da177e4 LT |
261 | u32 cur_win = tcp_receive_window(tp); |
262 | u32 new_win = __tcp_select_window(sk); | |
263 | ||
264 | /* Never shrink the offered window */ | |
2de979bd | 265 | if (new_win < cur_win) { |
1da177e4 LT |
266 | /* Danger Will Robinson! |
267 | * Don't update rcv_wup/rcv_wnd here or else | |
268 | * we will not be able to advertise a zero | |
269 | * window in time. --DaveM | |
270 | * | |
271 | * Relax Will Robinson. | |
272 | */ | |
8e165e20 FW |
273 | if (new_win == 0) |
274 | NET_INC_STATS(sock_net(sk), | |
275 | LINUX_MIB_TCPWANTZEROWINDOWADV); | |
607bfbf2 | 276 | new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale); |
1da177e4 LT |
277 | } |
278 | tp->rcv_wnd = new_win; | |
279 | tp->rcv_wup = tp->rcv_nxt; | |
280 | ||
281 | /* Make sure we do not exceed the maximum possible | |
282 | * scaled window. | |
283 | */ | |
ceef9ab6 | 284 | if (!tp->rx_opt.rcv_wscale && |
0f1e4d06 | 285 | READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)) |
1da177e4 LT |
286 | new_win = min(new_win, MAX_TCP_WINDOW); |
287 | else | |
288 | new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale)); | |
289 | ||
290 | /* RFC1323 scaling applied */ | |
291 | new_win >>= tp->rx_opt.rcv_wscale; | |
292 | ||
31770e34 | 293 | /* If we advertise zero window, disable fast path. */ |
8e165e20 | 294 | if (new_win == 0) { |
31770e34 | 295 | tp->pred_flags = 0; |
8e165e20 FW |
296 | if (old_win) |
297 | NET_INC_STATS(sock_net(sk), | |
298 | LINUX_MIB_TCPTOZEROWINDOWADV); | |
299 | } else if (old_win == 0) { | |
300 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPFROMZEROWINDOWADV); | |
301 | } | |
1da177e4 LT |
302 | |
303 | return new_win; | |
304 | } | |
305 | ||
67edfef7 | 306 | /* Packet ECN state for a SYN-ACK */ |
735d3831 | 307 | static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d | 308 | { |
30e502a3 DB |
309 | const struct tcp_sock *tp = tcp_sk(sk); |
310 | ||
4de075e0 | 311 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; |
056834d9 | 312 | if (!(tp->ecn_flags & TCP_ECN_OK)) |
4de075e0 | 313 | TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; |
91b5b21c LB |
314 | else if (tcp_ca_needs_ecn(sk) || |
315 | tcp_bpf_ca_needs_ecn(sk)) | |
30e502a3 | 316 | INET_ECN_xmit(sk); |
bdf1ee5d IJ |
317 | } |
318 | ||
67edfef7 | 319 | /* Packet ECN state for a SYN. */ |
735d3831 | 320 | static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) |
bdf1ee5d IJ |
321 | { |
322 | struct tcp_sock *tp = tcp_sk(sk); | |
91b5b21c | 323 | bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); |
4785a667 | 324 | bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 || |
91b5b21c | 325 | tcp_ca_needs_ecn(sk) || bpf_needs_ecn; |
f7b3bec6 FW |
326 | |
327 | if (!use_ecn) { | |
328 | const struct dst_entry *dst = __sk_dst_get(sk); | |
329 | ||
330 | if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) | |
331 | use_ecn = true; | |
332 | } | |
bdf1ee5d IJ |
333 | |
334 | tp->ecn_flags = 0; | |
f7b3bec6 FW |
335 | |
336 | if (use_ecn) { | |
4de075e0 | 337 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; |
bdf1ee5d | 338 | tp->ecn_flags = TCP_ECN_OK; |
91b5b21c | 339 | if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) |
30e502a3 | 340 | INET_ECN_xmit(sk); |
bdf1ee5d IJ |
341 | } |
342 | } | |
343 | ||
49213555 DB |
344 | static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb) |
345 | { | |
12b8d9ca | 346 | if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)) |
49213555 DB |
347 | /* tp->ecn_flags are cleared at a later point in time when |
348 | * SYN ACK is ultimatively being received. | |
349 | */ | |
350 | TCP_SKB_CB(skb)->tcp_flags &= ~(TCPHDR_ECE | TCPHDR_CWR); | |
351 | } | |
352 | ||
735d3831 | 353 | static void |
6ac705b1 | 354 | tcp_ecn_make_synack(const struct request_sock *req, struct tcphdr *th) |
bdf1ee5d | 355 | { |
6ac705b1 | 356 | if (inet_rsk(req)->ecn_ok) |
bdf1ee5d IJ |
357 | th->ece = 1; |
358 | } | |
359 | ||
67edfef7 AK |
360 | /* Set up ECN state for a packet on a ESTABLISHED socket that is about to |
361 | * be sent. | |
362 | */ | |
735d3831 | 363 | static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, |
ea1627c2 | 364 | struct tcphdr *th, int tcp_header_len) |
bdf1ee5d IJ |
365 | { |
366 | struct tcp_sock *tp = tcp_sk(sk); | |
367 | ||
368 | if (tp->ecn_flags & TCP_ECN_OK) { | |
369 | /* Not-retransmitted data segment: set ECT and inject CWR. */ | |
370 | if (skb->len != tcp_header_len && | |
371 | !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { | |
372 | INET_ECN_xmit(sk); | |
056834d9 | 373 | if (tp->ecn_flags & TCP_ECN_QUEUE_CWR) { |
bdf1ee5d | 374 | tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; |
ea1627c2 | 375 | th->cwr = 1; |
bdf1ee5d IJ |
376 | skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; |
377 | } | |
30e502a3 | 378 | } else if (!tcp_ca_needs_ecn(sk)) { |
bdf1ee5d IJ |
379 | /* ACK or retransmitted segment: clear ECT|CE */ |
380 | INET_ECN_dontxmit(sk); | |
381 | } | |
382 | if (tp->ecn_flags & TCP_ECN_DEMAND_CWR) | |
ea1627c2 | 383 | th->ece = 1; |
bdf1ee5d IJ |
384 | } |
385 | } | |
386 | ||
e870a8ef IJ |
387 | /* Constructs common control bits of non-data skb. If SYN/FIN is present, |
388 | * auto increment end seqno. | |
389 | */ | |
390 | static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) | |
391 | { | |
2e8e18ef | 392 | skb->ip_summed = CHECKSUM_PARTIAL; |
e870a8ef | 393 | |
4de075e0 | 394 | TCP_SKB_CB(skb)->tcp_flags = flags; |
e870a8ef | 395 | |
cd7d8498 | 396 | tcp_skb_pcount_set(skb, 1); |
e870a8ef IJ |
397 | |
398 | TCP_SKB_CB(skb)->seq = seq; | |
a3433f35 | 399 | if (flags & (TCPHDR_SYN | TCPHDR_FIN)) |
e870a8ef IJ |
400 | seq++; |
401 | TCP_SKB_CB(skb)->end_seq = seq; | |
402 | } | |
403 | ||
a2a385d6 | 404 | static inline bool tcp_urg_mode(const struct tcp_sock *tp) |
33f5f57e IJ |
405 | { |
406 | return tp->snd_una != tp->snd_up; | |
407 | } | |
408 | ||
3b65abb8 LC |
409 | #define OPTION_SACK_ADVERTISE BIT(0) |
410 | #define OPTION_TS BIT(1) | |
411 | #define OPTION_MD5 BIT(2) | |
412 | #define OPTION_WSCALE BIT(3) | |
413 | #define OPTION_FAST_OPEN_COOKIE BIT(8) | |
414 | #define OPTION_SMC BIT(9) | |
415 | #define OPTION_MPTCP BIT(10) | |
60e2a778 UB |
416 | |
417 | static void smc_options_write(__be32 *ptr, u16 *options) | |
418 | { | |
419 | #if IS_ENABLED(CONFIG_SMC) | |
420 | if (static_branch_unlikely(&tcp_have_smc)) { | |
421 | if (unlikely(OPTION_SMC & *options)) { | |
422 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
423 | (TCPOPT_NOP << 16) | | |
424 | (TCPOPT_EXP << 8) | | |
425 | (TCPOLEN_EXP_SMC_BASE)); | |
426 | *ptr++ = htonl(TCPOPT_SMC_MAGIC); | |
427 | } | |
428 | } | |
429 | #endif | |
430 | } | |
33ad798c AL |
431 | |
432 | struct tcp_out_options { | |
2100c8d2 YC |
433 | u16 options; /* bit field of OPTION_* */ |
434 | u16 mss; /* 0 to disable */ | |
33ad798c AL |
435 | u8 ws; /* window scale, 0 to disable */ |
436 | u8 num_sack_blocks; /* number of SACK blocks to include */ | |
bd0388ae | 437 | u8 hash_size; /* bytes in hash_location */ |
331fca43 | 438 | u8 bpf_opt_len; /* length of BPF hdr option */ |
bd0388ae | 439 | __u8 *hash_location; /* temporary pointer, overloaded */ |
2100c8d2 YC |
440 | __u32 tsval, tsecr; /* need to include OPTION_TS */ |
441 | struct tcp_fastopen_cookie *fastopen_cookie; /* Fast open cookie */ | |
eda7acdd | 442 | struct mptcp_out_options mptcp; |
33ad798c AL |
443 | }; |
444 | ||
ea66758c PA |
445 | static void mptcp_options_write(struct tcphdr *th, __be32 *ptr, |
446 | struct tcp_sock *tp, | |
fa3fe2b1 | 447 | struct tcp_out_options *opts) |
eda7acdd PK |
448 | { |
449 | #if IS_ENABLED(CONFIG_MPTCP) | |
450 | if (unlikely(OPTION_MPTCP & opts->options)) | |
ea66758c | 451 | mptcp_write_options(th, ptr, tp, &opts->mptcp); |
eda7acdd PK |
452 | #endif |
453 | } | |
454 | ||
331fca43 | 455 | #ifdef CONFIG_CGROUP_BPF |
0813a841 MKL |
456 | static int bpf_skops_write_hdr_opt_arg0(struct sk_buff *skb, |
457 | enum tcp_synack_type synack_type) | |
458 | { | |
459 | if (unlikely(!skb)) | |
460 | return BPF_WRITE_HDR_TCP_CURRENT_MSS; | |
461 | ||
462 | if (unlikely(synack_type == TCP_SYNACK_COOKIE)) | |
463 | return BPF_WRITE_HDR_TCP_SYNACK_COOKIE; | |
464 | ||
465 | return 0; | |
466 | } | |
467 | ||
331fca43 MKL |
468 | /* req, syn_skb and synack_type are used when writing synack */ |
469 | static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, | |
470 | struct request_sock *req, | |
471 | struct sk_buff *syn_skb, | |
472 | enum tcp_synack_type synack_type, | |
473 | struct tcp_out_options *opts, | |
474 | unsigned int *remaining) | |
475 | { | |
0813a841 MKL |
476 | struct bpf_sock_ops_kern sock_ops; |
477 | int err; | |
478 | ||
331fca43 MKL |
479 | if (likely(!BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), |
480 | BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG)) || | |
481 | !*remaining) | |
482 | return; | |
483 | ||
0813a841 MKL |
484 | /* *remaining has already been aligned to 4 bytes, so *remaining >= 4 */ |
485 | ||
486 | /* init sock_ops */ | |
487 | memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); | |
488 | ||
489 | sock_ops.op = BPF_SOCK_OPS_HDR_OPT_LEN_CB; | |
490 | ||
491 | if (req) { | |
492 | /* The listen "sk" cannot be passed here because | |
493 | * it is not locked. It would not make too much | |
494 | * sense to do bpf_setsockopt(listen_sk) based | |
495 | * on individual connection request also. | |
496 | * | |
497 | * Thus, "req" is passed here and the cgroup-bpf-progs | |
498 | * of the listen "sk" will be run. | |
499 | * | |
500 | * "req" is also used here for fastopen even the "sk" here is | |
501 | * a fullsock "child" sk. It is to keep the behavior | |
502 | * consistent between fastopen and non-fastopen on | |
503 | * the bpf programming side. | |
504 | */ | |
505 | sock_ops.sk = (struct sock *)req; | |
506 | sock_ops.syn_skb = syn_skb; | |
507 | } else { | |
508 | sock_owned_by_me(sk); | |
509 | ||
510 | sock_ops.is_fullsock = 1; | |
511 | sock_ops.sk = sk; | |
512 | } | |
513 | ||
514 | sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); | |
515 | sock_ops.remaining_opt_len = *remaining; | |
516 | /* tcp_current_mss() does not pass a skb */ | |
517 | if (skb) | |
518 | bpf_skops_init_skb(&sock_ops, skb, 0); | |
519 | ||
520 | err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); | |
521 | ||
522 | if (err || sock_ops.remaining_opt_len == *remaining) | |
523 | return; | |
524 | ||
525 | opts->bpf_opt_len = *remaining - sock_ops.remaining_opt_len; | |
526 | /* round up to 4 bytes */ | |
527 | opts->bpf_opt_len = (opts->bpf_opt_len + 3) & ~3; | |
528 | ||
529 | *remaining -= opts->bpf_opt_len; | |
331fca43 MKL |
530 | } |
531 | ||
532 | static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, | |
533 | struct request_sock *req, | |
534 | struct sk_buff *syn_skb, | |
535 | enum tcp_synack_type synack_type, | |
536 | struct tcp_out_options *opts) | |
537 | { | |
0813a841 MKL |
538 | u8 first_opt_off, nr_written, max_opt_len = opts->bpf_opt_len; |
539 | struct bpf_sock_ops_kern sock_ops; | |
540 | int err; | |
541 | ||
542 | if (likely(!max_opt_len)) | |
331fca43 MKL |
543 | return; |
544 | ||
0813a841 MKL |
545 | memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); |
546 | ||
547 | sock_ops.op = BPF_SOCK_OPS_WRITE_HDR_OPT_CB; | |
548 | ||
549 | if (req) { | |
550 | sock_ops.sk = (struct sock *)req; | |
551 | sock_ops.syn_skb = syn_skb; | |
552 | } else { | |
553 | sock_owned_by_me(sk); | |
554 | ||
555 | sock_ops.is_fullsock = 1; | |
556 | sock_ops.sk = sk; | |
557 | } | |
558 | ||
559 | sock_ops.args[0] = bpf_skops_write_hdr_opt_arg0(skb, synack_type); | |
560 | sock_ops.remaining_opt_len = max_opt_len; | |
561 | first_opt_off = tcp_hdrlen(skb) - max_opt_len; | |
562 | bpf_skops_init_skb(&sock_ops, skb, first_opt_off); | |
563 | ||
564 | err = BPF_CGROUP_RUN_PROG_SOCK_OPS_SK(&sock_ops, sk); | |
565 | ||
566 | if (err) | |
567 | nr_written = 0; | |
568 | else | |
569 | nr_written = max_opt_len - sock_ops.remaining_opt_len; | |
570 | ||
571 | if (nr_written < max_opt_len) | |
572 | memset(skb->data + first_opt_off + nr_written, TCPOPT_NOP, | |
573 | max_opt_len - nr_written); | |
331fca43 MKL |
574 | } |
575 | #else | |
576 | static void bpf_skops_hdr_opt_len(struct sock *sk, struct sk_buff *skb, | |
577 | struct request_sock *req, | |
578 | struct sk_buff *syn_skb, | |
579 | enum tcp_synack_type synack_type, | |
580 | struct tcp_out_options *opts, | |
581 | unsigned int *remaining) | |
582 | { | |
583 | } | |
584 | ||
585 | static void bpf_skops_write_hdr_opt(struct sock *sk, struct sk_buff *skb, | |
586 | struct request_sock *req, | |
587 | struct sk_buff *syn_skb, | |
588 | enum tcp_synack_type synack_type, | |
589 | struct tcp_out_options *opts) | |
590 | { | |
591 | } | |
592 | #endif | |
593 | ||
67edfef7 AK |
594 | /* Write previously computed TCP options to the packet. |
595 | * | |
596 | * Beware: Something in the Internet is very sensitive to the ordering of | |
fd6149d3 IJ |
597 | * TCP options, we learned this through the hard way, so be careful here. |
598 | * Luckily we can at least blame others for their non-compliance but from | |
8e3bff96 | 599 | * inter-operability perspective it seems that we're somewhat stuck with |
fd6149d3 IJ |
600 | * the ordering which we have been using if we want to keep working with |
601 | * those broken things (not that it currently hurts anybody as there isn't | |
602 | * particular reason why the ordering would need to be changed). | |
603 | * | |
604 | * At least SACK_PERM as the first option is known to lead to a disaster | |
605 | * (but it may well be that other scenarios fail similarly). | |
606 | */ | |
ea66758c | 607 | static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp, |
bd0388ae WAS |
608 | struct tcp_out_options *opts) |
609 | { | |
ea66758c | 610 | __be32 *ptr = (__be32 *)(th + 1); |
2100c8d2 | 611 | u16 options = opts->options; /* mungable copy */ |
bd0388ae | 612 | |
bd0388ae | 613 | if (unlikely(OPTION_MD5 & options)) { |
1a2c6181 CP |
614 | *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) | |
615 | (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG); | |
bd0388ae WAS |
616 | /* overload cookie hash location */ |
617 | opts->hash_location = (__u8 *)ptr; | |
33ad798c | 618 | ptr += 4; |
40efc6fa | 619 | } |
33ad798c | 620 | |
fd6149d3 IJ |
621 | if (unlikely(opts->mss)) { |
622 | *ptr++ = htonl((TCPOPT_MSS << 24) | | |
623 | (TCPOLEN_MSS << 16) | | |
624 | opts->mss); | |
625 | } | |
626 | ||
bd0388ae WAS |
627 | if (likely(OPTION_TS & options)) { |
628 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { | |
33ad798c AL |
629 | *ptr++ = htonl((TCPOPT_SACK_PERM << 24) | |
630 | (TCPOLEN_SACK_PERM << 16) | | |
631 | (TCPOPT_TIMESTAMP << 8) | | |
632 | TCPOLEN_TIMESTAMP); | |
bd0388ae | 633 | options &= ~OPTION_SACK_ADVERTISE; |
33ad798c AL |
634 | } else { |
635 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
636 | (TCPOPT_NOP << 16) | | |
637 | (TCPOPT_TIMESTAMP << 8) | | |
638 | TCPOLEN_TIMESTAMP); | |
639 | } | |
640 | *ptr++ = htonl(opts->tsval); | |
641 | *ptr++ = htonl(opts->tsecr); | |
642 | } | |
643 | ||
bd0388ae | 644 | if (unlikely(OPTION_SACK_ADVERTISE & options)) { |
33ad798c AL |
645 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
646 | (TCPOPT_NOP << 16) | | |
647 | (TCPOPT_SACK_PERM << 8) | | |
648 | TCPOLEN_SACK_PERM); | |
649 | } | |
650 | ||
bd0388ae | 651 | if (unlikely(OPTION_WSCALE & options)) { |
33ad798c AL |
652 | *ptr++ = htonl((TCPOPT_NOP << 24) | |
653 | (TCPOPT_WINDOW << 16) | | |
654 | (TCPOLEN_WINDOW << 8) | | |
655 | opts->ws); | |
656 | } | |
657 | ||
658 | if (unlikely(opts->num_sack_blocks)) { | |
659 | struct tcp_sack_block *sp = tp->rx_opt.dsack ? | |
660 | tp->duplicate_sack : tp->selective_acks; | |
40efc6fa SH |
661 | int this_sack; |
662 | ||
663 | *ptr++ = htonl((TCPOPT_NOP << 24) | | |
664 | (TCPOPT_NOP << 16) | | |
665 | (TCPOPT_SACK << 8) | | |
33ad798c | 666 | (TCPOLEN_SACK_BASE + (opts->num_sack_blocks * |
40efc6fa | 667 | TCPOLEN_SACK_PERBLOCK))); |
2de979bd | 668 | |
33ad798c AL |
669 | for (this_sack = 0; this_sack < opts->num_sack_blocks; |
670 | ++this_sack) { | |
40efc6fa SH |
671 | *ptr++ = htonl(sp[this_sack].start_seq); |
672 | *ptr++ = htonl(sp[this_sack].end_seq); | |
673 | } | |
2de979bd | 674 | |
5861f8e5 | 675 | tp->rx_opt.dsack = 0; |
40efc6fa | 676 | } |
2100c8d2 YC |
677 | |
678 | if (unlikely(OPTION_FAST_OPEN_COOKIE & options)) { | |
679 | struct tcp_fastopen_cookie *foc = opts->fastopen_cookie; | |
7f9b838b DL |
680 | u8 *p = (u8 *)ptr; |
681 | u32 len; /* Fast Open option length */ | |
682 | ||
683 | if (foc->exp) { | |
684 | len = TCPOLEN_EXP_FASTOPEN_BASE + foc->len; | |
685 | *ptr = htonl((TCPOPT_EXP << 24) | (len << 16) | | |
686 | TCPOPT_FASTOPEN_MAGIC); | |
687 | p += TCPOLEN_EXP_FASTOPEN_BASE; | |
688 | } else { | |
689 | len = TCPOLEN_FASTOPEN_BASE + foc->len; | |
690 | *p++ = TCPOPT_FASTOPEN; | |
691 | *p++ = len; | |
692 | } | |
2100c8d2 | 693 | |
7f9b838b DL |
694 | memcpy(p, foc->val, foc->len); |
695 | if ((len & 3) == 2) { | |
696 | p[foc->len] = TCPOPT_NOP; | |
697 | p[foc->len + 1] = TCPOPT_NOP; | |
2100c8d2 | 698 | } |
7f9b838b | 699 | ptr += (len + 3) >> 2; |
2100c8d2 | 700 | } |
60e2a778 UB |
701 | |
702 | smc_options_write(ptr, &options); | |
eda7acdd | 703 | |
ea66758c | 704 | mptcp_options_write(th, ptr, tp, opts); |
60e2a778 UB |
705 | } |
706 | ||
707 | static void smc_set_option(const struct tcp_sock *tp, | |
708 | struct tcp_out_options *opts, | |
709 | unsigned int *remaining) | |
710 | { | |
711 | #if IS_ENABLED(CONFIG_SMC) | |
712 | if (static_branch_unlikely(&tcp_have_smc)) { | |
713 | if (tp->syn_smc) { | |
714 | if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { | |
715 | opts->options |= OPTION_SMC; | |
716 | *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; | |
717 | } | |
718 | } | |
719 | } | |
720 | #endif | |
721 | } | |
722 | ||
723 | static void smc_set_option_cond(const struct tcp_sock *tp, | |
724 | const struct inet_request_sock *ireq, | |
725 | struct tcp_out_options *opts, | |
726 | unsigned int *remaining) | |
727 | { | |
728 | #if IS_ENABLED(CONFIG_SMC) | |
729 | if (static_branch_unlikely(&tcp_have_smc)) { | |
730 | if (tp->syn_smc && ireq->smc_ok) { | |
731 | if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) { | |
732 | opts->options |= OPTION_SMC; | |
733 | *remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED; | |
734 | } | |
735 | } | |
736 | } | |
737 | #endif | |
33ad798c AL |
738 | } |
739 | ||
cec37a6e PK |
740 | static void mptcp_set_option_cond(const struct request_sock *req, |
741 | struct tcp_out_options *opts, | |
742 | unsigned int *remaining) | |
743 | { | |
744 | if (rsk_is_mptcp(req)) { | |
745 | unsigned int size; | |
746 | ||
747 | if (mptcp_synack_options(req, &size, &opts->mptcp)) { | |
748 | if (*remaining >= size) { | |
749 | opts->options |= OPTION_MPTCP; | |
750 | *remaining -= size; | |
751 | } | |
752 | } | |
753 | } | |
754 | } | |
755 | ||
67edfef7 AK |
756 | /* Compute TCP options for SYN packets. This is not the final |
757 | * network wire format yet. | |
758 | */ | |
95c96174 | 759 | static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 760 | struct tcp_out_options *opts, |
cf533ea5 ED |
761 | struct tcp_md5sig_key **md5) |
762 | { | |
33ad798c | 763 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 764 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
783237e8 | 765 | struct tcp_fastopen_request *fastopen = tp->fastopen_req; |
33ad798c | 766 | |
8c2320e8 | 767 | *md5 = NULL; |
cfb6eeb4 | 768 | #ifdef CONFIG_TCP_MD5SIG |
459837b5 | 769 | if (static_branch_unlikely(&tcp_md5_needed.key) && |
6015c71e | 770 | rcu_access_pointer(tp->md5sig_info)) { |
8c2320e8 ED |
771 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
772 | if (*md5) { | |
773 | opts->options |= OPTION_MD5; | |
774 | remaining -= TCPOLEN_MD5SIG_ALIGNED; | |
775 | } | |
cfb6eeb4 YH |
776 | } |
777 | #endif | |
33ad798c AL |
778 | |
779 | /* We always get an MSS option. The option bytes which will be seen in | |
780 | * normal data packets should timestamps be used, must be in the MSS | |
781 | * advertised. But we subtract them from tp->mss_cache so that | |
782 | * calculations in tcp_sendmsg are simpler etc. So account for this | |
783 | * fact here if necessary. If we don't do this correctly, as a | |
784 | * receiver we won't recognize data packets as being full sized when we | |
785 | * should, and thus we won't abide by the delayed ACK rules correctly. | |
786 | * SACKs don't matter, we never delay an ACK when we have any of those | |
787 | * going out. */ | |
788 | opts->mss = tcp_advertise_mss(sk); | |
bd0388ae | 789 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c | 790 | |
3666f666 | 791 | if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps) && !*md5)) { |
33ad798c | 792 | opts->options |= OPTION_TS; |
7faee5c0 | 793 | opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset; |
33ad798c | 794 | opts->tsecr = tp->rx_opt.ts_recent; |
bd0388ae | 795 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c | 796 | } |
3666f666 | 797 | if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling))) { |
33ad798c | 798 | opts->ws = tp->rx_opt.rcv_wscale; |
89e95a61 | 799 | opts->options |= OPTION_WSCALE; |
bd0388ae | 800 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 801 | } |
3666f666 | 802 | if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_sack))) { |
33ad798c | 803 | opts->options |= OPTION_SACK_ADVERTISE; |
b32d1310 | 804 | if (unlikely(!(OPTION_TS & opts->options))) |
bd0388ae | 805 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c AL |
806 | } |
807 | ||
783237e8 | 808 | if (fastopen && fastopen->cookie.len >= 0) { |
2646c831 DL |
809 | u32 need = fastopen->cookie.len; |
810 | ||
811 | need += fastopen->cookie.exp ? TCPOLEN_EXP_FASTOPEN_BASE : | |
812 | TCPOLEN_FASTOPEN_BASE; | |
783237e8 YC |
813 | need = (need + 3) & ~3U; /* Align to 32 bits */ |
814 | if (remaining >= need) { | |
815 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
816 | opts->fastopen_cookie = &fastopen->cookie; | |
817 | remaining -= need; | |
818 | tp->syn_fastopen = 1; | |
2646c831 | 819 | tp->syn_fastopen_exp = fastopen->cookie.exp ? 1 : 0; |
783237e8 YC |
820 | } |
821 | } | |
bd0388ae | 822 | |
60e2a778 UB |
823 | smc_set_option(tp, opts, &remaining); |
824 | ||
cec37a6e PK |
825 | if (sk_is_mptcp(sk)) { |
826 | unsigned int size; | |
827 | ||
cc7972ea | 828 | if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) { |
cec37a6e PK |
829 | opts->options |= OPTION_MPTCP; |
830 | remaining -= size; | |
831 | } | |
832 | } | |
833 | ||
331fca43 MKL |
834 | bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); |
835 | ||
bd0388ae | 836 | return MAX_TCP_OPTION_SPACE - remaining; |
40efc6fa SH |
837 | } |
838 | ||
67edfef7 | 839 | /* Set up TCP options for SYN-ACKs. */ |
60e2a778 UB |
840 | static unsigned int tcp_synack_options(const struct sock *sk, |
841 | struct request_sock *req, | |
37bfbdda ED |
842 | unsigned int mss, struct sk_buff *skb, |
843 | struct tcp_out_options *opts, | |
844 | const struct tcp_md5sig_key *md5, | |
e114e1e8 | 845 | struct tcp_fastopen_cookie *foc, |
331fca43 MKL |
846 | enum tcp_synack_type synack_type, |
847 | struct sk_buff *syn_skb) | |
4957faad | 848 | { |
33ad798c | 849 | struct inet_request_sock *ireq = inet_rsk(req); |
95c96174 | 850 | unsigned int remaining = MAX_TCP_OPTION_SPACE; |
33ad798c | 851 | |
cfb6eeb4 | 852 | #ifdef CONFIG_TCP_MD5SIG |
80f03e27 | 853 | if (md5) { |
33ad798c | 854 | opts->options |= OPTION_MD5; |
4957faad WAS |
855 | remaining -= TCPOLEN_MD5SIG_ALIGNED; |
856 | ||
857 | /* We can't fit any SACK blocks in a packet with MD5 + TS | |
858 | * options. There was discussion about disabling SACK | |
859 | * rather than TS in order to fit in better with old, | |
860 | * buggy kernels, but that was deemed to be unnecessary. | |
861 | */ | |
e114e1e8 ED |
862 | if (synack_type != TCP_SYNACK_COOKIE) |
863 | ireq->tstamp_ok &= !ireq->sack_ok; | |
cfb6eeb4 YH |
864 | } |
865 | #endif | |
33ad798c | 866 | |
4957faad | 867 | /* We always send an MSS option. */ |
33ad798c | 868 | opts->mss = mss; |
4957faad | 869 | remaining -= TCPOLEN_MSS_ALIGNED; |
33ad798c AL |
870 | |
871 | if (likely(ireq->wscale_ok)) { | |
872 | opts->ws = ireq->rcv_wscale; | |
89e95a61 | 873 | opts->options |= OPTION_WSCALE; |
4957faad | 874 | remaining -= TCPOLEN_WSCALE_ALIGNED; |
33ad798c | 875 | } |
de213e5e | 876 | if (likely(ireq->tstamp_ok)) { |
33ad798c | 877 | opts->options |= OPTION_TS; |
95a22cae | 878 | opts->tsval = tcp_skb_timestamp(skb) + tcp_rsk(req)->ts_off; |
33ad798c | 879 | opts->tsecr = req->ts_recent; |
4957faad | 880 | remaining -= TCPOLEN_TSTAMP_ALIGNED; |
33ad798c AL |
881 | } |
882 | if (likely(ireq->sack_ok)) { | |
883 | opts->options |= OPTION_SACK_ADVERTISE; | |
de213e5e | 884 | if (unlikely(!ireq->tstamp_ok)) |
4957faad | 885 | remaining -= TCPOLEN_SACKPERM_ALIGNED; |
33ad798c | 886 | } |
7f9b838b DL |
887 | if (foc != NULL && foc->len >= 0) { |
888 | u32 need = foc->len; | |
889 | ||
890 | need += foc->exp ? TCPOLEN_EXP_FASTOPEN_BASE : | |
891 | TCPOLEN_FASTOPEN_BASE; | |
8336886f JC |
892 | need = (need + 3) & ~3U; /* Align to 32 bits */ |
893 | if (remaining >= need) { | |
894 | opts->options |= OPTION_FAST_OPEN_COOKIE; | |
895 | opts->fastopen_cookie = foc; | |
896 | remaining -= need; | |
897 | } | |
898 | } | |
1a2c6181 | 899 | |
cec37a6e PK |
900 | mptcp_set_option_cond(req, opts, &remaining); |
901 | ||
60e2a778 UB |
902 | smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining); |
903 | ||
331fca43 MKL |
904 | bpf_skops_hdr_opt_len((struct sock *)sk, skb, req, syn_skb, |
905 | synack_type, opts, &remaining); | |
906 | ||
4957faad | 907 | return MAX_TCP_OPTION_SPACE - remaining; |
33ad798c AL |
908 | } |
909 | ||
67edfef7 AK |
910 | /* Compute TCP options for ESTABLISHED sockets. This is not the |
911 | * final wire format yet. | |
912 | */ | |
95c96174 | 913 | static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb, |
33ad798c | 914 | struct tcp_out_options *opts, |
cf533ea5 ED |
915 | struct tcp_md5sig_key **md5) |
916 | { | |
33ad798c | 917 | struct tcp_sock *tp = tcp_sk(sk); |
95c96174 | 918 | unsigned int size = 0; |
cabeccbd | 919 | unsigned int eff_sacks; |
33ad798c | 920 | |
5843ef42 AK |
921 | opts->options = 0; |
922 | ||
8c2320e8 | 923 | *md5 = NULL; |
33ad798c | 924 | #ifdef CONFIG_TCP_MD5SIG |
459837b5 | 925 | if (static_branch_unlikely(&tcp_md5_needed.key) && |
6015c71e | 926 | rcu_access_pointer(tp->md5sig_info)) { |
8c2320e8 ED |
927 | *md5 = tp->af_specific->md5_lookup(sk, sk); |
928 | if (*md5) { | |
929 | opts->options |= OPTION_MD5; | |
930 | size += TCPOLEN_MD5SIG_ALIGNED; | |
931 | } | |
33ad798c | 932 | } |
33ad798c AL |
933 | #endif |
934 | ||
935 | if (likely(tp->rx_opt.tstamp_ok)) { | |
936 | opts->options |= OPTION_TS; | |
7faee5c0 | 937 | opts->tsval = skb ? tcp_skb_timestamp(skb) + tp->tsoffset : 0; |
33ad798c AL |
938 | opts->tsecr = tp->rx_opt.ts_recent; |
939 | size += TCPOLEN_TSTAMP_ALIGNED; | |
940 | } | |
941 | ||
cec37a6e PK |
942 | /* MPTCP options have precedence over SACK for the limited TCP |
943 | * option space because a MPTCP connection would be forced to | |
944 | * fall back to regular TCP if a required multipath option is | |
945 | * missing. SACK still gets a chance to use whatever space is | |
946 | * left. | |
947 | */ | |
948 | if (sk_is_mptcp(sk)) { | |
949 | unsigned int remaining = MAX_TCP_OPTION_SPACE - size; | |
950 | unsigned int opt_size = 0; | |
951 | ||
952 | if (mptcp_established_options(sk, skb, &opt_size, remaining, | |
953 | &opts->mptcp)) { | |
954 | opts->options |= OPTION_MPTCP; | |
955 | size += opt_size; | |
956 | } | |
957 | } | |
958 | ||
cabeccbd IJ |
959 | eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack; |
960 | if (unlikely(eff_sacks)) { | |
95c96174 | 961 | const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; |
9cfcca23 MM |
962 | if (unlikely(remaining < TCPOLEN_SACK_BASE_ALIGNED + |
963 | TCPOLEN_SACK_PERBLOCK)) | |
964 | return size; | |
965 | ||
33ad798c | 966 | opts->num_sack_blocks = |
95c96174 | 967 | min_t(unsigned int, eff_sacks, |
33ad798c AL |
968 | (remaining - TCPOLEN_SACK_BASE_ALIGNED) / |
969 | TCPOLEN_SACK_PERBLOCK); | |
9cfcca23 MM |
970 | |
971 | size += TCPOLEN_SACK_BASE_ALIGNED + | |
972 | opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; | |
33ad798c AL |
973 | } |
974 | ||
331fca43 MKL |
975 | if (unlikely(BPF_SOCK_OPS_TEST_FLAG(tp, |
976 | BPF_SOCK_OPS_WRITE_HDR_OPT_CB_FLAG))) { | |
977 | unsigned int remaining = MAX_TCP_OPTION_SPACE - size; | |
978 | ||
979 | bpf_skops_hdr_opt_len(sk, skb, NULL, NULL, 0, opts, &remaining); | |
980 | ||
981 | size = MAX_TCP_OPTION_SPACE - remaining; | |
982 | } | |
983 | ||
33ad798c | 984 | return size; |
40efc6fa | 985 | } |
1da177e4 | 986 | |
46d3ceab ED |
987 | |
988 | /* TCP SMALL QUEUES (TSQ) | |
989 | * | |
990 | * TSQ goal is to keep small amount of skbs per tcp flow in tx queues (qdisc+dev) | |
991 | * to reduce RTT and bufferbloat. | |
992 | * We do this using a special skb destructor (tcp_wfree). | |
993 | * | |
994 | * Its important tcp_wfree() can be replaced by sock_wfree() in the event skb | |
995 | * needs to be reallocated in a driver. | |
8e3bff96 | 996 | * The invariant being skb->truesize subtracted from sk->sk_wmem_alloc |
46d3ceab ED |
997 | * |
998 | * Since transmit from skb destructor is forbidden, we use a tasklet | |
999 | * to process all sockets that eventually need to send more skbs. | |
1000 | * We use one tasklet per cpu, with its own queue of sockets. | |
1001 | */ | |
1002 | struct tsq_tasklet { | |
1003 | struct tasklet_struct tasklet; | |
1004 | struct list_head head; /* queue of tcp sockets */ | |
1005 | }; | |
1006 | static DEFINE_PER_CPU(struct tsq_tasklet, tsq_tasklet); | |
1007 | ||
73a6bab5 | 1008 | static void tcp_tsq_write(struct sock *sk) |
6f458dfb ED |
1009 | { |
1010 | if ((1 << sk->sk_state) & | |
1011 | (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING | | |
f9616c35 ED |
1012 | TCPF_CLOSE_WAIT | TCPF_LAST_ACK)) { |
1013 | struct tcp_sock *tp = tcp_sk(sk); | |
1014 | ||
1015 | if (tp->lost_out > tp->retrans_out && | |
40570375 | 1016 | tcp_snd_cwnd(tp) > tcp_packets_in_flight(tp)) { |
3a91d29f | 1017 | tcp_mstamp_refresh(tp); |
f9616c35 | 1018 | tcp_xmit_retransmit_queue(sk); |
3a91d29f | 1019 | } |
f9616c35 ED |
1020 | |
1021 | tcp_write_xmit(sk, tcp_current_mss(sk), tp->nonagle, | |
bf06200e | 1022 | 0, GFP_ATOMIC); |
f9616c35 | 1023 | } |
6f458dfb | 1024 | } |
73a6bab5 ED |
1025 | |
1026 | static void tcp_tsq_handler(struct sock *sk) | |
1027 | { | |
1028 | bh_lock_sock(sk); | |
1029 | if (!sock_owned_by_user(sk)) | |
1030 | tcp_tsq_write(sk); | |
1031 | else if (!test_and_set_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags)) | |
1032 | sock_hold(sk); | |
1033 | bh_unlock_sock(sk); | |
1034 | } | |
46d3ceab | 1035 | /* |
8e3bff96 | 1036 | * One tasklet per cpu tries to send more skbs. |
46d3ceab | 1037 | * We run in tasklet context but need to disable irqs when |
8e3bff96 | 1038 | * transferring tsq->head because tcp_wfree() might |
46d3ceab ED |
1039 | * interrupt us (non NAPI drivers) |
1040 | */ | |
c6533ca8 | 1041 | static void tcp_tasklet_func(struct tasklet_struct *t) |
46d3ceab | 1042 | { |
c6533ca8 | 1043 | struct tsq_tasklet *tsq = from_tasklet(tsq, t, tasklet); |
46d3ceab ED |
1044 | LIST_HEAD(list); |
1045 | unsigned long flags; | |
1046 | struct list_head *q, *n; | |
1047 | struct tcp_sock *tp; | |
1048 | struct sock *sk; | |
1049 | ||
1050 | local_irq_save(flags); | |
1051 | list_splice_init(&tsq->head, &list); | |
1052 | local_irq_restore(flags); | |
1053 | ||
1054 | list_for_each_safe(q, n, &list) { | |
1055 | tp = list_entry(q, struct tcp_sock, tsq_node); | |
1056 | list_del(&tp->tsq_node); | |
1057 | ||
1058 | sk = (struct sock *)tp; | |
0a9648f1 | 1059 | smp_mb__before_atomic(); |
7aa5470c ED |
1060 | clear_bit(TSQ_QUEUED, &sk->sk_tsq_flags); |
1061 | ||
73a6bab5 | 1062 | tcp_tsq_handler(sk); |
46d3ceab ED |
1063 | sk_free(sk); |
1064 | } | |
1065 | } | |
1066 | ||
40fc3423 ED |
1067 | #define TCP_DEFERRED_ALL (TCPF_TSQ_DEFERRED | \ |
1068 | TCPF_WRITE_TIMER_DEFERRED | \ | |
1069 | TCPF_DELACK_TIMER_DEFERRED | \ | |
1070 | TCPF_MTU_REDUCED_DEFERRED) | |
46d3ceab ED |
1071 | /** |
1072 | * tcp_release_cb - tcp release_sock() callback | |
1073 | * @sk: socket | |
1074 | * | |
1075 | * called from release_sock() to perform protocol dependent | |
1076 | * actions before socket release. | |
1077 | */ | |
1078 | void tcp_release_cb(struct sock *sk) | |
1079 | { | |
fac30731 ED |
1080 | unsigned long flags = smp_load_acquire(&sk->sk_tsq_flags); |
1081 | unsigned long nflags; | |
46d3ceab | 1082 | |
6f458dfb ED |
1083 | /* perform an atomic operation only if at least one flag is set */ |
1084 | do { | |
6f458dfb ED |
1085 | if (!(flags & TCP_DEFERRED_ALL)) |
1086 | return; | |
1087 | nflags = flags & ~TCP_DEFERRED_ALL; | |
fac30731 | 1088 | } while (!try_cmpxchg(&sk->sk_tsq_flags, &flags, nflags)); |
6f458dfb | 1089 | |
73a6bab5 ED |
1090 | if (flags & TCPF_TSQ_DEFERRED) { |
1091 | tcp_tsq_write(sk); | |
1092 | __sock_put(sk); | |
1093 | } | |
c3f9b018 ED |
1094 | /* Here begins the tricky part : |
1095 | * We are called from release_sock() with : | |
1096 | * 1) BH disabled | |
1097 | * 2) sk_lock.slock spinlock held | |
1098 | * 3) socket owned by us (sk->sk_lock.owned == 1) | |
1099 | * | |
1100 | * But following code is meant to be called from BH handlers, | |
1101 | * so we should keep BH disabled, but early release socket ownership | |
1102 | */ | |
1103 | sock_release_ownership(sk); | |
1104 | ||
40fc3423 | 1105 | if (flags & TCPF_WRITE_TIMER_DEFERRED) { |
6f458dfb | 1106 | tcp_write_timer_handler(sk); |
144d56e9 ED |
1107 | __sock_put(sk); |
1108 | } | |
40fc3423 | 1109 | if (flags & TCPF_DELACK_TIMER_DEFERRED) { |
6f458dfb | 1110 | tcp_delack_timer_handler(sk); |
144d56e9 ED |
1111 | __sock_put(sk); |
1112 | } | |
40fc3423 | 1113 | if (flags & TCPF_MTU_REDUCED_DEFERRED) { |
4fab9071 | 1114 | inet_csk(sk)->icsk_af_ops->mtu_reduced(sk); |
144d56e9 ED |
1115 | __sock_put(sk); |
1116 | } | |
46d3ceab ED |
1117 | } |
1118 | EXPORT_SYMBOL(tcp_release_cb); | |
1119 | ||
1120 | void __init tcp_tasklet_init(void) | |
1121 | { | |
1122 | int i; | |
1123 | ||
1124 | for_each_possible_cpu(i) { | |
1125 | struct tsq_tasklet *tsq = &per_cpu(tsq_tasklet, i); | |
1126 | ||
1127 | INIT_LIST_HEAD(&tsq->head); | |
c6533ca8 | 1128 | tasklet_setup(&tsq->tasklet, tcp_tasklet_func); |
46d3ceab ED |
1129 | } |
1130 | } | |
1131 | ||
1132 | /* | |
1133 | * Write buffer destructor automatically called from kfree_skb. | |
8e3bff96 | 1134 | * We can't xmit new skbs from this context, as we might already |
46d3ceab ED |
1135 | * hold qdisc lock. |
1136 | */ | |
d6a4a104 | 1137 | void tcp_wfree(struct sk_buff *skb) |
46d3ceab ED |
1138 | { |
1139 | struct sock *sk = skb->sk; | |
1140 | struct tcp_sock *tp = tcp_sk(sk); | |
408f0a6c | 1141 | unsigned long flags, nval, oval; |
b548b17a ED |
1142 | struct tsq_tasklet *tsq; |
1143 | bool empty; | |
9b462d02 ED |
1144 | |
1145 | /* Keep one reference on sk_wmem_alloc. | |
1146 | * Will be released by sk_free() from here or tcp_tasklet_func() | |
1147 | */ | |
14afee4b | 1148 | WARN_ON(refcount_sub_and_test(skb->truesize - 1, &sk->sk_wmem_alloc)); |
9b462d02 ED |
1149 | |
1150 | /* If this softirq is serviced by ksoftirqd, we are likely under stress. | |
1151 | * Wait until our queues (qdisc + devices) are drained. | |
1152 | * This gives : | |
1153 | * - less callbacks to tcp_write_xmit(), reducing stress (batches) | |
1154 | * - chance for incoming ACK (processed by another cpu maybe) | |
1155 | * to migrate this flow (skb->ooo_okay will be eventually set) | |
1156 | */ | |
14afee4b | 1157 | if (refcount_read(&sk->sk_wmem_alloc) >= SKB_TRUESIZE(1) && this_cpu_ksoftirqd() == current) |
9b462d02 | 1158 | goto out; |
46d3ceab | 1159 | |
b548b17a ED |
1160 | oval = smp_load_acquire(&sk->sk_tsq_flags); |
1161 | do { | |
408f0a6c ED |
1162 | if (!(oval & TSQF_THROTTLED) || (oval & TSQF_QUEUED)) |
1163 | goto out; | |
1164 | ||
73a6bab5 | 1165 | nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED; |
b548b17a ED |
1166 | } while (!try_cmpxchg(&sk->sk_tsq_flags, &oval, nval)); |
1167 | ||
1168 | /* queue this socket to tasklet queue */ | |
1169 | local_irq_save(flags); | |
1170 | tsq = this_cpu_ptr(&tsq_tasklet); | |
1171 | empty = list_empty(&tsq->head); | |
1172 | list_add(&tp->tsq_node, &tsq->head); | |
1173 | if (empty) | |
1174 | tasklet_schedule(&tsq->tasklet); | |
1175 | local_irq_restore(flags); | |
1176 | return; | |
9b462d02 ED |
1177 | out: |
1178 | sk_free(sk); | |
46d3ceab ED |
1179 | } |
1180 | ||
73a6bab5 ED |
1181 | /* Note: Called under soft irq. |
1182 | * We can call TCP stack right away, unless socket is owned by user. | |
218af599 ED |
1183 | */ |
1184 | enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) | |
1185 | { | |
1186 | struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); | |
1187 | struct sock *sk = (struct sock *)tp; | |
218af599 | 1188 | |
73a6bab5 ED |
1189 | tcp_tsq_handler(sk); |
1190 | sock_put(sk); | |
218af599 | 1191 | |
218af599 ED |
1192 | return HRTIMER_NORESTART; |
1193 | } | |
1194 | ||
a7a25630 ED |
1195 | static void tcp_update_skb_after_send(struct sock *sk, struct sk_buff *skb, |
1196 | u64 prior_wstamp) | |
e2080072 | 1197 | { |
ab408b6d ED |
1198 | struct tcp_sock *tp = tcp_sk(sk); |
1199 | ||
ab408b6d | 1200 | if (sk->sk_pacing_status != SK_PACING_NONE) { |
76a9ebe8 | 1201 | unsigned long rate = sk->sk_pacing_rate; |
ab408b6d ED |
1202 | |
1203 | /* Original sch_fq does not pace first 10 MSS | |
1204 | * Note that tp->data_segs_out overflows after 2^32 packets, | |
1205 | * this is a minor annoyance. | |
1206 | */ | |
76a9ebe8 | 1207 | if (rate != ~0UL && rate && tp->data_segs_out >= 10) { |
a7a25630 ED |
1208 | u64 len_ns = div64_ul((u64)skb->len * NSEC_PER_SEC, rate); |
1209 | u64 credit = tp->tcp_wstamp_ns - prior_wstamp; | |
1210 | ||
1211 | /* take into account OS jitter */ | |
1212 | len_ns -= min_t(u64, len_ns / 2, credit); | |
1213 | tp->tcp_wstamp_ns += len_ns; | |
ab408b6d ED |
1214 | } |
1215 | } | |
e2080072 ED |
1216 | list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
1217 | } | |
1218 | ||
05e22e83 ED |
1219 | INDIRECT_CALLABLE_DECLARE(int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); |
1220 | INDIRECT_CALLABLE_DECLARE(int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)); | |
dd2e0b86 | 1221 | INDIRECT_CALLABLE_DECLARE(void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb)); |
05e22e83 | 1222 | |
1da177e4 LT |
1223 | /* This routine actually transmits TCP packets queued in by |
1224 | * tcp_do_sendmsg(). This is used by both the initial | |
1225 | * transmission and possible later retransmissions. | |
1226 | * All SKB's seen here are completely headerless. It is our | |
1227 | * job to build the TCP header, and pass the packet down to | |
1228 | * IP so it can do the same plus pass the packet off to the | |
1229 | * device. | |
1230 | * | |
1231 | * We are working here with either a clone of the original | |
1232 | * SKB, or a fresh unique copy made by the retransmit engine. | |
1233 | */ | |
2987babb YC |
1234 | static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, |
1235 | int clone_it, gfp_t gfp_mask, u32 rcv_nxt) | |
1da177e4 | 1236 | { |
dfb4b9dc DM |
1237 | const struct inet_connection_sock *icsk = inet_csk(sk); |
1238 | struct inet_sock *inet; | |
1239 | struct tcp_sock *tp; | |
1240 | struct tcp_skb_cb *tcb; | |
33ad798c | 1241 | struct tcp_out_options opts; |
95c96174 | 1242 | unsigned int tcp_options_size, tcp_header_size; |
8c72c65b | 1243 | struct sk_buff *oskb = NULL; |
cfb6eeb4 | 1244 | struct tcp_md5sig_key *md5; |
dfb4b9dc | 1245 | struct tcphdr *th; |
a7a25630 | 1246 | u64 prior_wstamp; |
dfb4b9dc DM |
1247 | int err; |
1248 | ||
1249 | BUG_ON(!skb || !tcp_skb_pcount(skb)); | |
6f094b9e | 1250 | tp = tcp_sk(sk); |
7f12422c YC |
1251 | prior_wstamp = tp->tcp_wstamp_ns; |
1252 | tp->tcp_wstamp_ns = max(tp->tcp_wstamp_ns, tp->tcp_clock_cache); | |
a1ac9c8a | 1253 | skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); |
ccdbb6e9 | 1254 | if (clone_it) { |
8c72c65b | 1255 | oskb = skb; |
e2080072 ED |
1256 | |
1257 | tcp_skb_tsorted_save(oskb) { | |
1258 | if (unlikely(skb_cloned(oskb))) | |
1259 | skb = pskb_copy(oskb, gfp_mask); | |
1260 | else | |
1261 | skb = skb_clone(oskb, gfp_mask); | |
1262 | } tcp_skb_tsorted_restore(oskb); | |
1263 | ||
dfb4b9dc DM |
1264 | if (unlikely(!skb)) |
1265 | return -ENOBUFS; | |
b738a185 ED |
1266 | /* retransmit skbs might have a non zero value in skb->dev |
1267 | * because skb->dev is aliased with skb->rbnode.rb_left | |
1268 | */ | |
1269 | skb->dev = NULL; | |
dfb4b9dc | 1270 | } |
5f6188a8 | 1271 | |
dfb4b9dc | 1272 | inet = inet_sk(sk); |
dfb4b9dc | 1273 | tcb = TCP_SKB_CB(skb); |
33ad798c | 1274 | memset(&opts, 0, sizeof(opts)); |
1da177e4 | 1275 | |
051ba674 | 1276 | if (unlikely(tcb->tcp_flags & TCPHDR_SYN)) { |
33ad798c | 1277 | tcp_options_size = tcp_syn_options(sk, skb, &opts, &md5); |
051ba674 | 1278 | } else { |
33ad798c AL |
1279 | tcp_options_size = tcp_established_options(sk, skb, &opts, |
1280 | &md5); | |
051ba674 ED |
1281 | /* Force a PSH flag on all (GSO) packets to expedite GRO flush |
1282 | * at receiver : This slightly improve GRO performance. | |
1283 | * Note that we do not force the PSH flag for non GSO packets, | |
1284 | * because they might be sent under high congestion events, | |
1285 | * and in this case it is better to delay the delivery of 1-MSS | |
1286 | * packets and thus the corresponding ACK packet that would | |
1287 | * release the following packet. | |
1288 | */ | |
1289 | if (tcp_skb_pcount(skb) > 1) | |
1290 | tcb->tcp_flags |= TCPHDR_PSH; | |
1291 | } | |
33ad798c | 1292 | tcp_header_size = tcp_options_size + sizeof(struct tcphdr); |
e905a9ed | 1293 | |
547669d4 | 1294 | /* if no packet is in qdisc/device queue, then allow XPS to select |
b2532eb9 | 1295 | * another queue. We can be called from tcp_tsq_handler() |
73a6bab5 | 1296 | * which holds one reference to sk. |
b2532eb9 ED |
1297 | * |
1298 | * TODO: Ideally, in-flight pure ACK packets should not matter here. | |
1299 | * One way to get this would be to set skb->truesize = 2 on them. | |
547669d4 | 1300 | */ |
b2532eb9 | 1301 | skb->ooo_okay = sk_wmem_alloc_get(sk) < SKB_TRUESIZE(1); |
dfb4b9dc | 1302 | |
38ab52e8 ED |
1303 | /* If we had to use memory reserve to allocate this skb, |
1304 | * this might cause drops if packet is looped back : | |
1305 | * Other socket might not have SOCK_MEMALLOC. | |
1306 | * Packets not looped back do not care about pfmemalloc. | |
1307 | */ | |
1308 | skb->pfmemalloc = 0; | |
1309 | ||
aa8223c7 ACM |
1310 | skb_push(skb, tcp_header_size); |
1311 | skb_reset_transport_header(skb); | |
46d3ceab ED |
1312 | |
1313 | skb_orphan(skb); | |
1314 | skb->sk = sk; | |
1d2077ac | 1315 | skb->destructor = skb_is_tcp_pure_ack(skb) ? __sock_wfree : tcp_wfree; |
14afee4b | 1316 | refcount_add(skb->truesize, &sk->sk_wmem_alloc); |
dfb4b9dc | 1317 | |
c3a2e837 JA |
1318 | skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm); |
1319 | ||
dfb4b9dc | 1320 | /* Build TCP header and checksum it. */ |
ea1627c2 | 1321 | th = (struct tcphdr *)skb->data; |
c720c7e8 ED |
1322 | th->source = inet->inet_sport; |
1323 | th->dest = inet->inet_dport; | |
dfb4b9dc | 1324 | th->seq = htonl(tcb->seq); |
2987babb | 1325 | th->ack_seq = htonl(rcv_nxt); |
df7a3b07 | 1326 | *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | |
4de075e0 | 1327 | tcb->tcp_flags); |
dfb4b9dc | 1328 | |
dfb4b9dc DM |
1329 | th->check = 0; |
1330 | th->urg_ptr = 0; | |
1da177e4 | 1331 | |
33f5f57e | 1332 | /* The urg_mode check is necessary during a below snd_una win probe */ |
7691367d HX |
1333 | if (unlikely(tcp_urg_mode(tp) && before(tcb->seq, tp->snd_up))) { |
1334 | if (before(tp->snd_up, tcb->seq + 0x10000)) { | |
1335 | th->urg_ptr = htons(tp->snd_up - tcb->seq); | |
1336 | th->urg = 1; | |
1337 | } else if (after(tcb->seq + 0xFFFF, tp->snd_nxt)) { | |
0eae88f3 | 1338 | th->urg_ptr = htons(0xFFFF); |
7691367d HX |
1339 | th->urg = 1; |
1340 | } | |
dfb4b9dc | 1341 | } |
1da177e4 | 1342 | |
51466a75 | 1343 | skb_shinfo(skb)->gso_type = sk->sk_gso_type; |
ea1627c2 ED |
1344 | if (likely(!(tcb->tcp_flags & TCPHDR_SYN))) { |
1345 | th->window = htons(tcp_select_window(sk)); | |
1346 | tcp_ecn_send(sk, skb, th, tcp_header_size); | |
1347 | } else { | |
1348 | /* RFC1323: The window in SYN & SYN/ACK segments | |
1349 | * is never scaled. | |
1350 | */ | |
1351 | th->window = htons(min(tp->rcv_wnd, 65535U)); | |
1352 | } | |
fa3fe2b1 | 1353 | |
ea66758c | 1354 | tcp_options_write(th, tp, &opts); |
fa3fe2b1 | 1355 | |
cfb6eeb4 YH |
1356 | #ifdef CONFIG_TCP_MD5SIG |
1357 | /* Calculate the MD5 hash, as we have all we need now */ | |
1358 | if (md5) { | |
aba54656 | 1359 | sk_gso_disable(sk); |
bd0388ae | 1360 | tp->af_specific->calc_md5_hash(opts.hash_location, |
39f8e58e | 1361 | md5, sk, skb); |
cfb6eeb4 YH |
1362 | } |
1363 | #endif | |
1364 | ||
331fca43 MKL |
1365 | /* BPF prog is the last one writing header option */ |
1366 | bpf_skops_write_hdr_opt(sk, skb, NULL, NULL, 0, &opts); | |
1367 | ||
dd2e0b86 ED |
1368 | INDIRECT_CALL_INET(icsk->icsk_af_ops->send_check, |
1369 | tcp_v6_send_check, tcp_v4_send_check, | |
1370 | sk, skb); | |
1da177e4 | 1371 | |
4de075e0 | 1372 | if (likely(tcb->tcp_flags & TCPHDR_ACK)) |
27cde44a | 1373 | tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt); |
1da177e4 | 1374 | |
a44d6eac | 1375 | if (skb->len != tcp_header_size) { |
cf533ea5 | 1376 | tcp_event_data_sent(tp, sk); |
a44d6eac | 1377 | tp->data_segs_out += tcp_skb_pcount(skb); |
ba113c3a | 1378 | tp->bytes_sent += skb->len - tcp_header_size; |
a44d6eac | 1379 | } |
1da177e4 | 1380 | |
bd37a088 | 1381 | if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) |
aa2ea058 TH |
1382 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_OUTSEGS, |
1383 | tcp_skb_pcount(skb)); | |
1da177e4 | 1384 | |
2efd055c | 1385 | tp->segs_out += tcp_skb_pcount(skb); |
0ae5b43d | 1386 | skb_set_hash_from_sk(skb, sk); |
f69ad292 | 1387 | /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */ |
cd7d8498 | 1388 | skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb); |
f69ad292 | 1389 | skb_shinfo(skb)->gso_size = tcp_skb_mss(skb); |
cd7d8498 | 1390 | |
d3edd06e | 1391 | /* Leave earliest departure time in skb->tstamp (skb->skb_mstamp_ns) */ |
971f10ec ED |
1392 | |
1393 | /* Cleanup our debris for IP stacks */ | |
1394 | memset(skb->cb, 0, max(sizeof(struct inet_skb_parm), | |
1395 | sizeof(struct inet6_skb_parm))); | |
1396 | ||
a842fe14 ED |
1397 | tcp_add_tx_delay(skb, tp); |
1398 | ||
05e22e83 ED |
1399 | err = INDIRECT_CALL_INET(icsk->icsk_af_ops->queue_xmit, |
1400 | inet6_csk_xmit, ip_queue_xmit, | |
1401 | sk, skb, &inet->cork.fl); | |
7faee5c0 | 1402 | |
8c72c65b ED |
1403 | if (unlikely(err > 0)) { |
1404 | tcp_enter_cwr(sk); | |
1405 | err = net_xmit_eval(err); | |
1406 | } | |
fc225799 | 1407 | if (!err && oskb) { |
a7a25630 | 1408 | tcp_update_skb_after_send(sk, oskb, prior_wstamp); |
fc225799 ED |
1409 | tcp_rate_skb_sent(sk, oskb); |
1410 | } | |
8c72c65b | 1411 | return err; |
1da177e4 LT |
1412 | } |
1413 | ||
2987babb YC |
1414 | static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, |
1415 | gfp_t gfp_mask) | |
1416 | { | |
1417 | return __tcp_transmit_skb(sk, skb, clone_it, gfp_mask, | |
1418 | tcp_sk(sk)->rcv_nxt); | |
1419 | } | |
1420 | ||
67edfef7 | 1421 | /* This routine just queues the buffer for sending. |
1da177e4 LT |
1422 | * |
1423 | * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames, | |
1424 | * otherwise socket can stall. | |
1425 | */ | |
1426 | static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) | |
1427 | { | |
1428 | struct tcp_sock *tp = tcp_sk(sk); | |
1429 | ||
1430 | /* Advance write_seq and place onto the write_queue. */ | |
0f317464 | 1431 | WRITE_ONCE(tp->write_seq, TCP_SKB_CB(skb)->end_seq); |
f4a775d1 | 1432 | __skb_header_release(skb); |
fe067e8a | 1433 | tcp_add_write_queue_tail(sk, skb); |
ab4e846a | 1434 | sk_wmem_queued_add(sk, skb->truesize); |
3ab224be | 1435 | sk_mem_charge(sk, skb->truesize); |
1da177e4 LT |
1436 | } |
1437 | ||
67edfef7 | 1438 | /* Initialize TSO segments for a packet. */ |
5bbb432c | 1439 | static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
f6302d1d | 1440 | { |
4a64fd6c | 1441 | if (skb->len <= mss_now) { |
f6302d1d DM |
1442 | /* Avoid the costly divide in the normal |
1443 | * non-TSO case. | |
1444 | */ | |
cd7d8498 | 1445 | tcp_skb_pcount_set(skb, 1); |
f69ad292 | 1446 | TCP_SKB_CB(skb)->tcp_gso_size = 0; |
f6302d1d | 1447 | } else { |
cd7d8498 | 1448 | tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now)); |
f69ad292 | 1449 | TCP_SKB_CB(skb)->tcp_gso_size = mss_now; |
1da177e4 LT |
1450 | } |
1451 | } | |
1452 | ||
797108d1 IJ |
1453 | /* Pcount in the middle of the write queue got changed, we need to do various |
1454 | * tweaks to fix counters | |
1455 | */ | |
cf533ea5 | 1456 | static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr) |
797108d1 IJ |
1457 | { |
1458 | struct tcp_sock *tp = tcp_sk(sk); | |
1459 | ||
1460 | tp->packets_out -= decr; | |
1461 | ||
1462 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) | |
1463 | tp->sacked_out -= decr; | |
1464 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) | |
1465 | tp->retrans_out -= decr; | |
1466 | if (TCP_SKB_CB(skb)->sacked & TCPCB_LOST) | |
1467 | tp->lost_out -= decr; | |
1468 | ||
1469 | /* Reno case is special. Sigh... */ | |
1470 | if (tcp_is_reno(tp) && decr > 0) | |
1471 | tp->sacked_out -= min_t(u32, tp->sacked_out, decr); | |
1472 | ||
797108d1 IJ |
1473 | if (tp->lost_skb_hint && |
1474 | before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(tp->lost_skb_hint)->seq) && | |
713bafea | 1475 | (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) |
797108d1 IJ |
1476 | tp->lost_cnt_hint -= decr; |
1477 | ||
1478 | tcp_verify_left_out(tp); | |
1479 | } | |
1480 | ||
0a2cf20c SHY |
1481 | static bool tcp_has_tx_tstamp(const struct sk_buff *skb) |
1482 | { | |
1483 | return TCP_SKB_CB(skb)->txstamp_ack || | |
1484 | (skb_shinfo(skb)->tx_flags & SKBTX_ANY_TSTAMP); | |
1485 | } | |
1486 | ||
490cc7d0 WB |
1487 | static void tcp_fragment_tstamp(struct sk_buff *skb, struct sk_buff *skb2) |
1488 | { | |
1489 | struct skb_shared_info *shinfo = skb_shinfo(skb); | |
1490 | ||
0a2cf20c | 1491 | if (unlikely(tcp_has_tx_tstamp(skb)) && |
490cc7d0 WB |
1492 | !before(shinfo->tskey, TCP_SKB_CB(skb2)->seq)) { |
1493 | struct skb_shared_info *shinfo2 = skb_shinfo(skb2); | |
1494 | u8 tsflags = shinfo->tx_flags & SKBTX_ANY_TSTAMP; | |
1495 | ||
1496 | shinfo->tx_flags &= ~tsflags; | |
1497 | shinfo2->tx_flags |= tsflags; | |
1498 | swap(shinfo->tskey, shinfo2->tskey); | |
b51e13fa MKL |
1499 | TCP_SKB_CB(skb2)->txstamp_ack = TCP_SKB_CB(skb)->txstamp_ack; |
1500 | TCP_SKB_CB(skb)->txstamp_ack = 0; | |
490cc7d0 WB |
1501 | } |
1502 | } | |
1503 | ||
a166140e MKL |
1504 | static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2) |
1505 | { | |
1506 | TCP_SKB_CB(skb2)->eor = TCP_SKB_CB(skb)->eor; | |
1507 | TCP_SKB_CB(skb)->eor = 0; | |
1508 | } | |
1509 | ||
75c119af ED |
1510 | /* Insert buff after skb on the write or rtx queue of sk. */ |
1511 | static void tcp_insert_write_queue_after(struct sk_buff *skb, | |
1512 | struct sk_buff *buff, | |
1513 | struct sock *sk, | |
1514 | enum tcp_queue tcp_queue) | |
1515 | { | |
1516 | if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE) | |
1517 | __skb_queue_after(&sk->sk_write_queue, skb, buff); | |
1518 | else | |
1519 | tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); | |
1520 | } | |
1521 | ||
1da177e4 LT |
1522 | /* Function to create two new TCP segments. Shrinks the given segment |
1523 | * to the specified size and appends a new segment with the rest of the | |
e905a9ed | 1524 | * packet to the list. This won't be called frequently, I hope. |
1da177e4 LT |
1525 | * Remember, these are still headerless SKBs at this point. |
1526 | */ | |
75c119af ED |
1527 | int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, |
1528 | struct sk_buff *skb, u32 len, | |
6cc55e09 | 1529 | unsigned int mss_now, gfp_t gfp) |
1da177e4 LT |
1530 | { |
1531 | struct tcp_sock *tp = tcp_sk(sk); | |
1532 | struct sk_buff *buff; | |
6475be16 | 1533 | int nsize, old_factor; |
b617158d | 1534 | long limit; |
b60b49ea | 1535 | int nlen; |
9ce01461 | 1536 | u8 flags; |
1da177e4 | 1537 | |
2fceec13 IJ |
1538 | if (WARN_ON(len > skb->len)) |
1539 | return -EINVAL; | |
6a438bbe | 1540 | |
1da177e4 LT |
1541 | nsize = skb_headlen(skb) - len; |
1542 | if (nsize < 0) | |
1543 | nsize = 0; | |
1544 | ||
b617158d ED |
1545 | /* tcp_sendmsg() can overshoot sk_wmem_queued by one full size skb. |
1546 | * We need some allowance to not penalize applications setting small | |
1547 | * SO_SNDBUF values. | |
1548 | * Also allow first and last skb in retransmit queue to be split. | |
1549 | */ | |
7c4e983c | 1550 | limit = sk->sk_sndbuf + 2 * SKB_TRUESIZE(GSO_LEGACY_MAX_SIZE); |
b617158d ED |
1551 | if (unlikely((sk->sk_wmem_queued >> 1) > limit && |
1552 | tcp_queue != TCP_FRAG_IN_WRITE_QUEUE && | |
1553 | skb != tcp_rtx_queue_head(sk) && | |
1554 | skb != tcp_rtx_queue_tail(sk))) { | |
f070ef2a ED |
1555 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG); |
1556 | return -ENOMEM; | |
1557 | } | |
1558 | ||
c4777efa | 1559 | if (skb_unclone_keeptruesize(skb, gfp)) |
1da177e4 LT |
1560 | return -ENOMEM; |
1561 | ||
1562 | /* Get a new skb... force flag on. */ | |
f8dd3b8d | 1563 | buff = tcp_stream_alloc_skb(sk, nsize, gfp, true); |
51456b29 | 1564 | if (!buff) |
1da177e4 | 1565 | return -ENOMEM; /* We'll just try again later. */ |
41477662 | 1566 | skb_copy_decrypted(buff, skb); |
5a369ca6 | 1567 | mptcp_skb_ext_copy(buff, skb); |
ef5cb973 | 1568 | |
ab4e846a | 1569 | sk_wmem_queued_add(sk, buff->truesize); |
3ab224be | 1570 | sk_mem_charge(sk, buff->truesize); |
b60b49ea HX |
1571 | nlen = skb->len - len - nsize; |
1572 | buff->truesize += nlen; | |
1573 | skb->truesize -= nlen; | |
1da177e4 LT |
1574 | |
1575 | /* Correct the sequence numbers. */ | |
1576 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
1577 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
1578 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
1579 | ||
1580 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
1581 | flags = TCP_SKB_CB(skb)->tcp_flags; |
1582 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
1583 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
e14c3caf | 1584 | TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked; |
a166140e | 1585 | tcp_skb_fragment_eor(skb, buff); |
1da177e4 | 1586 | |
98be9b12 | 1587 | skb_split(skb, buff, len); |
1da177e4 | 1588 | |
a1ac9c8a | 1589 | skb_set_delivery_time(buff, skb->tstamp, true); |
490cc7d0 | 1590 | tcp_fragment_tstamp(skb, buff); |
1da177e4 | 1591 | |
6475be16 DM |
1592 | old_factor = tcp_skb_pcount(skb); |
1593 | ||
1da177e4 | 1594 | /* Fix up tso_factor for both original and new SKB. */ |
5bbb432c ED |
1595 | tcp_set_skb_tso_segs(skb, mss_now); |
1596 | tcp_set_skb_tso_segs(buff, mss_now); | |
1da177e4 | 1597 | |
b9f64820 YC |
1598 | /* Update delivered info for the new segment */ |
1599 | TCP_SKB_CB(buff)->tx = TCP_SKB_CB(skb)->tx; | |
1600 | ||
6475be16 DM |
1601 | /* If this packet has been sent out already, we must |
1602 | * adjust the various packet counters. | |
1603 | */ | |
cf0b450c | 1604 | if (!before(tp->snd_nxt, TCP_SKB_CB(buff)->end_seq)) { |
6475be16 DM |
1605 | int diff = old_factor - tcp_skb_pcount(skb) - |
1606 | tcp_skb_pcount(buff); | |
1da177e4 | 1607 | |
797108d1 IJ |
1608 | if (diff) |
1609 | tcp_adjust_pcount(sk, skb, diff); | |
1da177e4 LT |
1610 | } |
1611 | ||
1612 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 1613 | __skb_header_release(buff); |
75c119af | 1614 | tcp_insert_write_queue_after(skb, buff, sk, tcp_queue); |
f67971e6 ED |
1615 | if (tcp_queue == TCP_FRAG_IN_RTX_QUEUE) |
1616 | list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor); | |
1da177e4 LT |
1617 | |
1618 | return 0; | |
1619 | } | |
1620 | ||
f4d01666 ED |
1621 | /* This is similar to __pskb_pull_tail(). The difference is that pulled |
1622 | * data is not copied, but immediately discarded. | |
1da177e4 | 1623 | */ |
7162fb24 | 1624 | static int __pskb_trim_head(struct sk_buff *skb, int len) |
1da177e4 | 1625 | { |
7b7fc97a | 1626 | struct skb_shared_info *shinfo; |
1da177e4 LT |
1627 | int i, k, eat; |
1628 | ||
4fa48bf3 ED |
1629 | eat = min_t(int, len, skb_headlen(skb)); |
1630 | if (eat) { | |
1631 | __skb_pull(skb, eat); | |
1632 | len -= eat; | |
1633 | if (!len) | |
7162fb24 | 1634 | return 0; |
4fa48bf3 | 1635 | } |
1da177e4 LT |
1636 | eat = len; |
1637 | k = 0; | |
7b7fc97a ED |
1638 | shinfo = skb_shinfo(skb); |
1639 | for (i = 0; i < shinfo->nr_frags; i++) { | |
1640 | int size = skb_frag_size(&shinfo->frags[i]); | |
9e903e08 ED |
1641 | |
1642 | if (size <= eat) { | |
aff65da0 | 1643 | skb_frag_unref(skb, i); |
9e903e08 | 1644 | eat -= size; |
1da177e4 | 1645 | } else { |
7b7fc97a | 1646 | shinfo->frags[k] = shinfo->frags[i]; |
1da177e4 | 1647 | if (eat) { |
b54c9d5b | 1648 | skb_frag_off_add(&shinfo->frags[k], eat); |
7b7fc97a | 1649 | skb_frag_size_sub(&shinfo->frags[k], eat); |
1da177e4 LT |
1650 | eat = 0; |
1651 | } | |
1652 | k++; | |
1653 | } | |
1654 | } | |
7b7fc97a | 1655 | shinfo->nr_frags = k; |
1da177e4 | 1656 | |
1da177e4 LT |
1657 | skb->data_len -= len; |
1658 | skb->len = skb->data_len; | |
7162fb24 | 1659 | return len; |
1da177e4 LT |
1660 | } |
1661 | ||
67edfef7 | 1662 | /* Remove acked data from a packet in the transmit queue. */ |
1da177e4 LT |
1663 | int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len) |
1664 | { | |
7162fb24 ED |
1665 | u32 delta_truesize; |
1666 | ||
c4777efa | 1667 | if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) |
1da177e4 LT |
1668 | return -ENOMEM; |
1669 | ||
7162fb24 | 1670 | delta_truesize = __pskb_trim_head(skb, len); |
1da177e4 LT |
1671 | |
1672 | TCP_SKB_CB(skb)->seq += len; | |
1da177e4 | 1673 | |
7162fb24 ED |
1674 | if (delta_truesize) { |
1675 | skb->truesize -= delta_truesize; | |
ab4e846a | 1676 | sk_wmem_queued_add(sk, -delta_truesize); |
9b65b17d TA |
1677 | if (!skb_zcopy_pure(skb)) |
1678 | sk_mem_uncharge(sk, delta_truesize); | |
7162fb24 | 1679 | } |
1da177e4 | 1680 | |
5b35e1e6 | 1681 | /* Any change of skb->len requires recalculation of tso factor. */ |
1da177e4 | 1682 | if (tcp_skb_pcount(skb) > 1) |
5bbb432c | 1683 | tcp_set_skb_tso_segs(skb, tcp_skb_mss(skb)); |
1da177e4 LT |
1684 | |
1685 | return 0; | |
1686 | } | |
1687 | ||
1b63edd6 YC |
1688 | /* Calculate MSS not accounting any TCP options. */ |
1689 | static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
5d424d5a | 1690 | { |
cf533ea5 ED |
1691 | const struct tcp_sock *tp = tcp_sk(sk); |
1692 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1693 | int mss_now; |
1694 | ||
1695 | /* Calculate base mss without TCP options: | |
1696 | It is MMS_S - sizeof(tcphdr) of rfc1122 | |
1697 | */ | |
1698 | mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr); | |
1699 | ||
67469601 ED |
1700 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1701 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1702 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1703 | ||
1704 | if (dst && dst_allfrag(dst)) | |
1705 | mss_now -= icsk->icsk_af_ops->net_frag_header_len; | |
1706 | } | |
1707 | ||
5d424d5a JH |
1708 | /* Clamp it (mss_clamp does not include tcp options) */ |
1709 | if (mss_now > tp->rx_opt.mss_clamp) | |
1710 | mss_now = tp->rx_opt.mss_clamp; | |
1711 | ||
1712 | /* Now subtract optional transport overhead */ | |
1713 | mss_now -= icsk->icsk_ext_hdr_len; | |
1714 | ||
1715 | /* Then reserve room for full set of TCP options and 8 bytes of data */ | |
78eb166c KI |
1716 | mss_now = max(mss_now, |
1717 | READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss)); | |
5d424d5a JH |
1718 | return mss_now; |
1719 | } | |
1720 | ||
1b63edd6 YC |
1721 | /* Calculate MSS. Not accounting for SACKs here. */ |
1722 | int tcp_mtu_to_mss(struct sock *sk, int pmtu) | |
1723 | { | |
1724 | /* Subtract TCP options size, not including SACKs */ | |
1725 | return __tcp_mtu_to_mss(sk, pmtu) - | |
1726 | (tcp_sk(sk)->tcp_header_len - sizeof(struct tcphdr)); | |
1727 | } | |
c7bb4b89 | 1728 | EXPORT_SYMBOL(tcp_mtu_to_mss); |
1b63edd6 | 1729 | |
5d424d5a | 1730 | /* Inverse of above */ |
67469601 | 1731 | int tcp_mss_to_mtu(struct sock *sk, int mss) |
5d424d5a | 1732 | { |
cf533ea5 ED |
1733 | const struct tcp_sock *tp = tcp_sk(sk); |
1734 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
5d424d5a JH |
1735 | int mtu; |
1736 | ||
1737 | mtu = mss + | |
1738 | tp->tcp_header_len + | |
1739 | icsk->icsk_ext_hdr_len + | |
1740 | icsk->icsk_af_ops->net_header_len; | |
1741 | ||
67469601 ED |
1742 | /* IPv6 adds a frag_hdr in case RTAX_FEATURE_ALLFRAG is set */ |
1743 | if (icsk->icsk_af_ops->net_frag_header_len) { | |
1744 | const struct dst_entry *dst = __sk_dst_get(sk); | |
1745 | ||
1746 | if (dst && dst_allfrag(dst)) | |
1747 | mtu += icsk->icsk_af_ops->net_frag_header_len; | |
1748 | } | |
5d424d5a JH |
1749 | return mtu; |
1750 | } | |
556c6b46 | 1751 | EXPORT_SYMBOL(tcp_mss_to_mtu); |
5d424d5a | 1752 | |
67edfef7 | 1753 | /* MTU probing init per socket */ |
5d424d5a JH |
1754 | void tcp_mtup_init(struct sock *sk) |
1755 | { | |
1756 | struct tcp_sock *tp = tcp_sk(sk); | |
1757 | struct inet_connection_sock *icsk = inet_csk(sk); | |
b0f9ca53 | 1758 | struct net *net = sock_net(sk); |
5d424d5a | 1759 | |
f47d00e0 | 1760 | icsk->icsk_mtup.enabled = READ_ONCE(net->ipv4.sysctl_tcp_mtu_probing) > 1; |
5d424d5a | 1761 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) + |
e905a9ed | 1762 | icsk->icsk_af_ops->net_header_len; |
88d78bc0 | 1763 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, READ_ONCE(net->ipv4.sysctl_tcp_base_mss)); |
5d424d5a | 1764 | icsk->icsk_mtup.probe_size = 0; |
05cbc0db | 1765 | if (icsk->icsk_mtup.enabled) |
c74df29a | 1766 | icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
5d424d5a | 1767 | } |
4bc2f18b | 1768 | EXPORT_SYMBOL(tcp_mtup_init); |
5d424d5a | 1769 | |
1da177e4 LT |
1770 | /* This function synchronize snd mss to current pmtu/exthdr set. |
1771 | ||
1772 | tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts | |
1773 | for TCP options, but includes only bare TCP header. | |
1774 | ||
1775 | tp->rx_opt.mss_clamp is mss negotiated at connection setup. | |
caa20d9a | 1776 | It is minimum of user_mss and mss received with SYN. |
1da177e4 LT |
1777 | It also does not include TCP options. |
1778 | ||
d83d8461 | 1779 | inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function. |
1da177e4 LT |
1780 | |
1781 | tp->mss_cache is current effective sending mss, including | |
1782 | all tcp options except for SACKs. It is evaluated, | |
1783 | taking into account current pmtu, but never exceeds | |
1784 | tp->rx_opt.mss_clamp. | |
1785 | ||
1786 | NOTE1. rfc1122 clearly states that advertised MSS | |
1787 | DOES NOT include either tcp or ip options. | |
1788 | ||
d83d8461 ACM |
1789 | NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache |
1790 | are READ ONLY outside this function. --ANK (980731) | |
1da177e4 | 1791 | */ |
1da177e4 LT |
1792 | unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu) |
1793 | { | |
1794 | struct tcp_sock *tp = tcp_sk(sk); | |
d83d8461 | 1795 | struct inet_connection_sock *icsk = inet_csk(sk); |
5d424d5a | 1796 | int mss_now; |
1da177e4 | 1797 | |
5d424d5a JH |
1798 | if (icsk->icsk_mtup.search_high > pmtu) |
1799 | icsk->icsk_mtup.search_high = pmtu; | |
1da177e4 | 1800 | |
5d424d5a | 1801 | mss_now = tcp_mtu_to_mss(sk, pmtu); |
409d22b4 | 1802 | mss_now = tcp_bound_to_half_wnd(tp, mss_now); |
1da177e4 LT |
1803 | |
1804 | /* And store cached results */ | |
d83d8461 | 1805 | icsk->icsk_pmtu_cookie = pmtu; |
5d424d5a JH |
1806 | if (icsk->icsk_mtup.enabled) |
1807 | mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low)); | |
c1b4a7e6 | 1808 | tp->mss_cache = mss_now; |
1da177e4 LT |
1809 | |
1810 | return mss_now; | |
1811 | } | |
4bc2f18b | 1812 | EXPORT_SYMBOL(tcp_sync_mss); |
1da177e4 LT |
1813 | |
1814 | /* Compute the current effective MSS, taking SACKs and IP options, | |
1815 | * and even PMTU discovery events into account. | |
1da177e4 | 1816 | */ |
0c54b85f | 1817 | unsigned int tcp_current_mss(struct sock *sk) |
1da177e4 | 1818 | { |
cf533ea5 ED |
1819 | const struct tcp_sock *tp = tcp_sk(sk); |
1820 | const struct dst_entry *dst = __sk_dst_get(sk); | |
c1b4a7e6 | 1821 | u32 mss_now; |
95c96174 | 1822 | unsigned int header_len; |
33ad798c AL |
1823 | struct tcp_out_options opts; |
1824 | struct tcp_md5sig_key *md5; | |
c1b4a7e6 DM |
1825 | |
1826 | mss_now = tp->mss_cache; | |
1827 | ||
1da177e4 LT |
1828 | if (dst) { |
1829 | u32 mtu = dst_mtu(dst); | |
d83d8461 | 1830 | if (mtu != inet_csk(sk)->icsk_pmtu_cookie) |
1da177e4 LT |
1831 | mss_now = tcp_sync_mss(sk, mtu); |
1832 | } | |
1833 | ||
33ad798c AL |
1834 | header_len = tcp_established_options(sk, NULL, &opts, &md5) + |
1835 | sizeof(struct tcphdr); | |
1836 | /* The mss_cache is sized based on tp->tcp_header_len, which assumes | |
1837 | * some common options. If this is an odd packet (because we have SACK | |
1838 | * blocks etc) then our calculated header_len will be different, and | |
1839 | * we have to adjust mss_now correspondingly */ | |
1840 | if (header_len != tp->tcp_header_len) { | |
1841 | int delta = (int) header_len - tp->tcp_header_len; | |
1842 | mss_now -= delta; | |
1843 | } | |
cfb6eeb4 | 1844 | |
1da177e4 LT |
1845 | return mss_now; |
1846 | } | |
1847 | ||
86fd14ad WP |
1848 | /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto. |
1849 | * As additional protections, we do not touch cwnd in retransmission phases, | |
1850 | * and if application hit its sndbuf limit recently. | |
1851 | */ | |
1852 | static void tcp_cwnd_application_limited(struct sock *sk) | |
1853 | { | |
1854 | struct tcp_sock *tp = tcp_sk(sk); | |
1855 | ||
1856 | if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open && | |
1857 | sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) { | |
1858 | /* Limited by application or receiver window. */ | |
1859 | u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk)); | |
1860 | u32 win_used = max(tp->snd_cwnd_used, init_win); | |
40570375 | 1861 | if (win_used < tcp_snd_cwnd(tp)) { |
86fd14ad | 1862 | tp->snd_ssthresh = tcp_current_ssthresh(sk); |
40570375 | 1863 | tcp_snd_cwnd_set(tp, (tcp_snd_cwnd(tp) + win_used) >> 1); |
86fd14ad WP |
1864 | } |
1865 | tp->snd_cwnd_used = 0; | |
1866 | } | |
c2203cf7 | 1867 | tp->snd_cwnd_stamp = tcp_jiffies32; |
86fd14ad WP |
1868 | } |
1869 | ||
ca8a2263 | 1870 | static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) |
a762a980 | 1871 | { |
1b1fc3fd | 1872 | const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; |
9e412ba7 | 1873 | struct tcp_sock *tp = tcp_sk(sk); |
a762a980 | 1874 | |
f4ce91ce NC |
1875 | /* Track the strongest available signal of the degree to which the cwnd |
1876 | * is fully utilized. If cwnd-limited then remember that fact for the | |
1877 | * current window. If not cwnd-limited then track the maximum number of | |
1878 | * outstanding packets in the current window. (If cwnd-limited then we | |
1879 | * chose to not update tp->max_packets_out to avoid an extra else | |
1880 | * clause with no functional impact.) | |
ca8a2263 | 1881 | */ |
f4ce91ce NC |
1882 | if (!before(tp->snd_una, tp->cwnd_usage_seq) || |
1883 | is_cwnd_limited || | |
1884 | (!tp->is_cwnd_limited && | |
1885 | tp->packets_out > tp->max_packets_out)) { | |
ca8a2263 | 1886 | tp->is_cwnd_limited = is_cwnd_limited; |
f4ce91ce NC |
1887 | tp->max_packets_out = tp->packets_out; |
1888 | tp->cwnd_usage_seq = tp->snd_nxt; | |
ca8a2263 | 1889 | } |
e114a710 | 1890 | |
24901551 | 1891 | if (tcp_is_cwnd_limited(sk)) { |
a762a980 DM |
1892 | /* Network is feed fully. */ |
1893 | tp->snd_cwnd_used = 0; | |
c2203cf7 | 1894 | tp->snd_cwnd_stamp = tcp_jiffies32; |
a762a980 DM |
1895 | } else { |
1896 | /* Network starves. */ | |
1897 | if (tp->packets_out > tp->snd_cwnd_used) | |
1898 | tp->snd_cwnd_used = tp->packets_out; | |
1899 | ||
4845b571 | 1900 | if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) && |
c2203cf7 | 1901 | (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && |
1b1fc3fd | 1902 | !ca_ops->cong_control) |
a762a980 | 1903 | tcp_cwnd_application_limited(sk); |
b0f71bd3 FY |
1904 | |
1905 | /* The following conditions together indicate the starvation | |
1906 | * is caused by insufficient sender buffer: | |
1907 | * 1) just sent some data (see tcp_write_xmit) | |
1908 | * 2) not cwnd limited (this else condition) | |
75c119af | 1909 | * 3) no more data to send (tcp_write_queue_empty()) |
b0f71bd3 FY |
1910 | * 4) application is hitting buffer limit (SOCK_NOSPACE) |
1911 | */ | |
75c119af | 1912 | if (tcp_write_queue_empty(sk) && sk->sk_socket && |
b0f71bd3 FY |
1913 | test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) && |
1914 | (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) | |
1915 | tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED); | |
a762a980 DM |
1916 | } |
1917 | } | |
1918 | ||
d4589926 ED |
1919 | /* Minshall's variant of the Nagle send check. */ |
1920 | static bool tcp_minshall_check(const struct tcp_sock *tp) | |
1921 | { | |
1922 | return after(tp->snd_sml, tp->snd_una) && | |
1923 | !after(tp->snd_sml, tp->snd_nxt); | |
1924 | } | |
1925 | ||
1926 | /* Update snd_sml if this skb is under mss | |
1927 | * Note that a TSO packet might end with a sub-mss segment | |
1928 | * The test is really : | |
1929 | * if ((skb->len % mss) != 0) | |
1930 | * tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1931 | * But we can avoid doing the divide again given we already have | |
1932 | * skb_pcount = skb->len / mss_now | |
0e3a4803 | 1933 | */ |
d4589926 ED |
1934 | static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now, |
1935 | const struct sk_buff *skb) | |
1936 | { | |
1937 | if (skb->len < tcp_skb_pcount(skb) * mss_now) | |
1938 | tp->snd_sml = TCP_SKB_CB(skb)->end_seq; | |
1939 | } | |
1940 | ||
1941 | /* Return false, if packet can be sent now without violation Nagle's rules: | |
1942 | * 1. It is full sized. (provided by caller in %partial bool) | |
1943 | * 2. Or it contains FIN. (already checked by caller) | |
1944 | * 3. Or TCP_CORK is not set, and TCP_NODELAY is set. | |
1945 | * 4. Or TCP_CORK is not set, and all sent packets are ACKed. | |
1946 | * With Minshall's modification: all sent small packets are ACKed. | |
1947 | */ | |
1948 | static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp, | |
cc93fc51 | 1949 | int nonagle) |
d4589926 ED |
1950 | { |
1951 | return partial && | |
1952 | ((nonagle & TCP_NAGLE_CORK) || | |
1953 | (!nonagle && tp->packets_out && tcp_minshall_check(tp))); | |
1954 | } | |
605ad7f1 ED |
1955 | |
1956 | /* Return how many segs we'd like on a TSO packet, | |
65466904 ED |
1957 | * depending on current pacing rate, and how close the peer is. |
1958 | * | |
1959 | * Rationale is: | |
1960 | * - For close peers, we rather send bigger packets to reduce | |
1961 | * cpu costs, because occasional losses will be repaired fast. | |
1962 | * - For long distance/rtt flows, we would like to get ACK clocking | |
1963 | * with 1 ACK per ms. | |
1964 | * | |
1965 | * Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting | |
1966 | * in bigger TSO bursts. We we cut the RTT-based allowance in half | |
1967 | * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance | |
1968 | * is below 1500 bytes after 6 * ~500 usec = 3ms. | |
605ad7f1 | 1969 | */ |
dcb8c9b4 ED |
1970 | static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, |
1971 | int min_tso_segs) | |
605ad7f1 | 1972 | { |
65466904 ED |
1973 | unsigned long bytes; |
1974 | u32 r; | |
605ad7f1 | 1975 | |
65466904 | 1976 | bytes = sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift); |
605ad7f1 | 1977 | |
2455e61b | 1978 | r = tcp_min_rtt(tcp_sk(sk)) >> READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_rtt_log); |
65466904 ED |
1979 | if (r < BITS_PER_TYPE(sk->sk_gso_max_size)) |
1980 | bytes += sk->sk_gso_max_size >> r; | |
1981 | ||
1982 | bytes = min_t(unsigned long, bytes, sk->sk_gso_max_size); | |
605ad7f1 | 1983 | |
65466904 | 1984 | return max_t(u32, bytes / mss_now, min_tso_segs); |
605ad7f1 ED |
1985 | } |
1986 | ||
ed6e7268 NC |
1987 | /* Return the number of segments we want in the skb we are transmitting. |
1988 | * See if congestion control module wants to decide; otherwise, autosize. | |
1989 | */ | |
1990 | static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) | |
1991 | { | |
1992 | const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; | |
dcb8c9b4 | 1993 | u32 min_tso, tso_segs; |
ed6e7268 | 1994 | |
dcb8c9b4 ED |
1995 | min_tso = ca_ops->min_tso_segs ? |
1996 | ca_ops->min_tso_segs(sk) : | |
e0bb4ab9 | 1997 | READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); |
dcb8c9b4 ED |
1998 | |
1999 | tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); | |
350c9f48 | 2000 | return min_t(u32, tso_segs, sk->sk_gso_max_segs); |
ed6e7268 NC |
2001 | } |
2002 | ||
d4589926 ED |
2003 | /* Returns the portion of skb which can be sent right away */ |
2004 | static unsigned int tcp_mss_split_point(const struct sock *sk, | |
2005 | const struct sk_buff *skb, | |
2006 | unsigned int mss_now, | |
2007 | unsigned int max_segs, | |
2008 | int nonagle) | |
c1b4a7e6 | 2009 | { |
cf533ea5 | 2010 | const struct tcp_sock *tp = tcp_sk(sk); |
d4589926 | 2011 | u32 partial, needed, window, max_len; |
c1b4a7e6 | 2012 | |
90840def | 2013 | window = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
1485348d | 2014 | max_len = mss_now * max_segs; |
0e3a4803 | 2015 | |
1485348d BH |
2016 | if (likely(max_len <= window && skb != tcp_write_queue_tail(sk))) |
2017 | return max_len; | |
0e3a4803 | 2018 | |
5ea3a748 IJ |
2019 | needed = min(skb->len, window); |
2020 | ||
1485348d BH |
2021 | if (max_len <= needed) |
2022 | return max_len; | |
0e3a4803 | 2023 | |
d4589926 ED |
2024 | partial = needed % mss_now; |
2025 | /* If last segment is not a full MSS, check if Nagle rules allow us | |
2026 | * to include this last segment in this skb. | |
2027 | * Otherwise, we'll split the skb at last MSS boundary | |
2028 | */ | |
cc93fc51 | 2029 | if (tcp_nagle_check(partial != 0, tp, nonagle)) |
d4589926 ED |
2030 | return needed - partial; |
2031 | ||
2032 | return needed; | |
c1b4a7e6 DM |
2033 | } |
2034 | ||
2035 | /* Can at least one segment of SKB be sent right now, according to the | |
2036 | * congestion window rules? If so, return how many segments are allowed. | |
2037 | */ | |
cf533ea5 ED |
2038 | static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp, |
2039 | const struct sk_buff *skb) | |
c1b4a7e6 | 2040 | { |
d649a7a8 | 2041 | u32 in_flight, cwnd, halfcwnd; |
c1b4a7e6 DM |
2042 | |
2043 | /* Don't be strict about the congestion window for the final FIN. */ | |
4de075e0 ED |
2044 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) && |
2045 | tcp_skb_pcount(skb) == 1) | |
c1b4a7e6 DM |
2046 | return 1; |
2047 | ||
2048 | in_flight = tcp_packets_in_flight(tp); | |
40570375 | 2049 | cwnd = tcp_snd_cwnd(tp); |
d649a7a8 ED |
2050 | if (in_flight >= cwnd) |
2051 | return 0; | |
c1b4a7e6 | 2052 | |
d649a7a8 ED |
2053 | /* For better scheduling, ensure we have at least |
2054 | * 2 GSO packets in flight. | |
2055 | */ | |
2056 | halfcwnd = max(cwnd >> 1, 1U); | |
2057 | return min(halfcwnd, cwnd - in_flight); | |
c1b4a7e6 DM |
2058 | } |
2059 | ||
b595076a | 2060 | /* Initialize TSO state of a skb. |
67edfef7 | 2061 | * This must be invoked the first time we consider transmitting |
c1b4a7e6 DM |
2062 | * SKB onto the wire. |
2063 | */ | |
5bbb432c | 2064 | static int tcp_init_tso_segs(struct sk_buff *skb, unsigned int mss_now) |
c1b4a7e6 DM |
2065 | { |
2066 | int tso_segs = tcp_skb_pcount(skb); | |
2067 | ||
f8269a49 | 2068 | if (!tso_segs || (tso_segs > 1 && tcp_skb_mss(skb) != mss_now)) { |
5bbb432c | 2069 | tcp_set_skb_tso_segs(skb, mss_now); |
c1b4a7e6 DM |
2070 | tso_segs = tcp_skb_pcount(skb); |
2071 | } | |
2072 | return tso_segs; | |
2073 | } | |
2074 | ||
c1b4a7e6 | 2075 | |
a2a385d6 | 2076 | /* Return true if the Nagle test allows this packet to be |
c1b4a7e6 DM |
2077 | * sent now. |
2078 | */ | |
a2a385d6 ED |
2079 | static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb, |
2080 | unsigned int cur_mss, int nonagle) | |
c1b4a7e6 DM |
2081 | { |
2082 | /* Nagle rule does not apply to frames, which sit in the middle of the | |
2083 | * write_queue (they have no chances to get new data). | |
2084 | * | |
2085 | * This is implemented in the callers, where they modify the 'nonagle' | |
2086 | * argument based upon the location of SKB in the send queue. | |
2087 | */ | |
2088 | if (nonagle & TCP_NAGLE_PUSH) | |
a2a385d6 | 2089 | return true; |
c1b4a7e6 | 2090 | |
9b44190d YC |
2091 | /* Don't use the nagle rule for urgent data (or for the final FIN). */ |
2092 | if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) | |
a2a385d6 | 2093 | return true; |
c1b4a7e6 | 2094 | |
cc93fc51 | 2095 | if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle)) |
a2a385d6 | 2096 | return true; |
c1b4a7e6 | 2097 | |
a2a385d6 | 2098 | return false; |
c1b4a7e6 DM |
2099 | } |
2100 | ||
2101 | /* Does at least the first segment of SKB fit into the send window? */ | |
a2a385d6 ED |
2102 | static bool tcp_snd_wnd_test(const struct tcp_sock *tp, |
2103 | const struct sk_buff *skb, | |
2104 | unsigned int cur_mss) | |
c1b4a7e6 DM |
2105 | { |
2106 | u32 end_seq = TCP_SKB_CB(skb)->end_seq; | |
2107 | ||
2108 | if (skb->len > cur_mss) | |
2109 | end_seq = TCP_SKB_CB(skb)->seq + cur_mss; | |
2110 | ||
90840def | 2111 | return !after(end_seq, tcp_wnd_end(tp)); |
c1b4a7e6 DM |
2112 | } |
2113 | ||
c1b4a7e6 DM |
2114 | /* Trim TSO SKB to LEN bytes, put the remaining data into a new packet |
2115 | * which is put after SKB on the list. It is very much like | |
2116 | * tcp_fragment() except that it may make several kinds of assumptions | |
2117 | * in order to speed up the splitting operation. In particular, we | |
2118 | * know that all the data is in scatter-gather pages, and that the | |
2119 | * packet has never been sent out before (and thus is not cloned). | |
2120 | */ | |
56483341 | 2121 | static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, |
c4ead4c5 | 2122 | unsigned int mss_now, gfp_t gfp) |
c1b4a7e6 | 2123 | { |
c1b4a7e6 | 2124 | int nlen = skb->len - len; |
56483341 | 2125 | struct sk_buff *buff; |
9ce01461 | 2126 | u8 flags; |
c1b4a7e6 DM |
2127 | |
2128 | /* All of a TSO frame must be composed of paged data. */ | |
c8ac3774 | 2129 | if (skb->len != skb->data_len) |
56483341 ED |
2130 | return tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
2131 | skb, len, mss_now, gfp); | |
c1b4a7e6 | 2132 | |
f8dd3b8d | 2133 | buff = tcp_stream_alloc_skb(sk, 0, gfp, true); |
51456b29 | 2134 | if (unlikely(!buff)) |
c1b4a7e6 | 2135 | return -ENOMEM; |
41477662 | 2136 | skb_copy_decrypted(buff, skb); |
5a369ca6 | 2137 | mptcp_skb_ext_copy(buff, skb); |
c1b4a7e6 | 2138 | |
ab4e846a | 2139 | sk_wmem_queued_add(sk, buff->truesize); |
3ab224be | 2140 | sk_mem_charge(sk, buff->truesize); |
b60b49ea | 2141 | buff->truesize += nlen; |
c1b4a7e6 DM |
2142 | skb->truesize -= nlen; |
2143 | ||
2144 | /* Correct the sequence numbers. */ | |
2145 | TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len; | |
2146 | TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq; | |
2147 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq; | |
2148 | ||
2149 | /* PSH and FIN should only be set in the second packet. */ | |
4de075e0 ED |
2150 | flags = TCP_SKB_CB(skb)->tcp_flags; |
2151 | TCP_SKB_CB(skb)->tcp_flags = flags & ~(TCPHDR_FIN | TCPHDR_PSH); | |
2152 | TCP_SKB_CB(buff)->tcp_flags = flags; | |
c1b4a7e6 | 2153 | |
a166140e MKL |
2154 | tcp_skb_fragment_eor(skb, buff); |
2155 | ||
c1b4a7e6 | 2156 | skb_split(skb, buff, len); |
490cc7d0 | 2157 | tcp_fragment_tstamp(skb, buff); |
c1b4a7e6 DM |
2158 | |
2159 | /* Fix up tso_factor for both original and new SKB. */ | |
5bbb432c ED |
2160 | tcp_set_skb_tso_segs(skb, mss_now); |
2161 | tcp_set_skb_tso_segs(buff, mss_now); | |
c1b4a7e6 DM |
2162 | |
2163 | /* Link BUFF into the send queue. */ | |
f4a775d1 | 2164 | __skb_header_release(buff); |
56483341 | 2165 | tcp_insert_write_queue_after(skb, buff, sk, TCP_FRAG_IN_WRITE_QUEUE); |
c1b4a7e6 DM |
2166 | |
2167 | return 0; | |
2168 | } | |
2169 | ||
2170 | /* Try to defer sending, if possible, in order to minimize the amount | |
2171 | * of TSO splitting we do. View it as a kind of TSO Nagle test. | |
2172 | * | |
2173 | * This algorithm is from John Heffner. | |
2174 | */ | |
ca8a2263 | 2175 | static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, |
f9bfe4e6 ED |
2176 | bool *is_cwnd_limited, |
2177 | bool *is_rwnd_limited, | |
2178 | u32 max_segs) | |
c1b4a7e6 | 2179 | { |
6687e988 | 2180 | const struct inet_connection_sock *icsk = inet_csk(sk); |
f1c6ea38 | 2181 | u32 send_win, cong_win, limit, in_flight; |
50c8339e | 2182 | struct tcp_sock *tp = tcp_sk(sk); |
50c8339e | 2183 | struct sk_buff *head; |
ad9f4f50 | 2184 | int win_divisor; |
f1c6ea38 | 2185 | s64 delta; |
c1b4a7e6 | 2186 | |
99d7662a | 2187 | if (icsk->icsk_ca_state >= TCP_CA_Recovery) |
ae8064ac JH |
2188 | goto send_now; |
2189 | ||
5f852eb5 | 2190 | /* Avoid bursty behavior by allowing defer |
a682850a ED |
2191 | * only if the last write was recent (1 ms). |
2192 | * Note that tp->tcp_wstamp_ns can be in the future if we have | |
2193 | * packets waiting in a qdisc or device for EDT delivery. | |
5f852eb5 | 2194 | */ |
a682850a ED |
2195 | delta = tp->tcp_clock_cache - tp->tcp_wstamp_ns - NSEC_PER_MSEC; |
2196 | if (delta > 0) | |
ae8064ac | 2197 | goto send_now; |
908a75c1 | 2198 | |
c1b4a7e6 DM |
2199 | in_flight = tcp_packets_in_flight(tp); |
2200 | ||
c8c9aeb5 | 2201 | BUG_ON(tcp_skb_pcount(skb) <= 1); |
40570375 | 2202 | BUG_ON(tcp_snd_cwnd(tp) <= in_flight); |
c1b4a7e6 | 2203 | |
90840def | 2204 | send_win = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
c1b4a7e6 DM |
2205 | |
2206 | /* From in_flight test above, we know that cwnd > in_flight. */ | |
40570375 | 2207 | cong_win = (tcp_snd_cwnd(tp) - in_flight) * tp->mss_cache; |
c1b4a7e6 DM |
2208 | |
2209 | limit = min(send_win, cong_win); | |
2210 | ||
ba244fe9 | 2211 | /* If a full-sized TSO skb can be sent, do it. */ |
605ad7f1 | 2212 | if (limit >= max_segs * tp->mss_cache) |
ae8064ac | 2213 | goto send_now; |
ba244fe9 | 2214 | |
62ad2761 IJ |
2215 | /* Middle in queue won't get any more data, full sendable already? */ |
2216 | if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) | |
2217 | goto send_now; | |
2218 | ||
5bbcc0f5 | 2219 | win_divisor = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_tso_win_divisor); |
ad9f4f50 | 2220 | if (win_divisor) { |
40570375 | 2221 | u32 chunk = min(tp->snd_wnd, tcp_snd_cwnd(tp) * tp->mss_cache); |
c1b4a7e6 DM |
2222 | |
2223 | /* If at least some fraction of a window is available, | |
2224 | * just use it. | |
2225 | */ | |
ad9f4f50 | 2226 | chunk /= win_divisor; |
c1b4a7e6 | 2227 | if (limit >= chunk) |
ae8064ac | 2228 | goto send_now; |
c1b4a7e6 DM |
2229 | } else { |
2230 | /* Different approach, try not to defer past a single | |
2231 | * ACK. Receiver should ACK every other full sized | |
2232 | * frame, so if we have space for more than 3 frames | |
2233 | * then send now. | |
2234 | */ | |
6b5a5c0d | 2235 | if (limit > tcp_max_tso_deferred_mss(tp) * tp->mss_cache) |
ae8064ac | 2236 | goto send_now; |
c1b4a7e6 DM |
2237 | } |
2238 | ||
75c119af ED |
2239 | /* TODO : use tsorted_sent_queue ? */ |
2240 | head = tcp_rtx_queue_head(sk); | |
2241 | if (!head) | |
2242 | goto send_now; | |
f1c6ea38 | 2243 | delta = tp->tcp_clock_cache - head->tstamp; |
50c8339e | 2244 | /* If next ACK is likely to come too late (half srtt), do not defer */ |
f1c6ea38 | 2245 | if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0) |
50c8339e ED |
2246 | goto send_now; |
2247 | ||
f9bfe4e6 ED |
2248 | /* Ok, it looks like it is advisable to defer. |
2249 | * Three cases are tracked : | |
2250 | * 1) We are cwnd-limited | |
2251 | * 2) We are rwnd-limited | |
2252 | * 3) We are application limited. | |
2253 | */ | |
2254 | if (cong_win < send_win) { | |
2255 | if (cong_win <= skb->len) { | |
2256 | *is_cwnd_limited = true; | |
2257 | return true; | |
2258 | } | |
2259 | } else { | |
2260 | if (send_win <= skb->len) { | |
2261 | *is_rwnd_limited = true; | |
2262 | return true; | |
2263 | } | |
2264 | } | |
ae8064ac | 2265 | |
f9bfe4e6 | 2266 | /* If this packet won't get more data, do not wait. */ |
d8ed257f ED |
2267 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || |
2268 | TCP_SKB_CB(skb)->eor) | |
f9bfe4e6 | 2269 | goto send_now; |
ca8a2263 | 2270 | |
a2a385d6 | 2271 | return true; |
ae8064ac JH |
2272 | |
2273 | send_now: | |
a2a385d6 | 2274 | return false; |
c1b4a7e6 DM |
2275 | } |
2276 | ||
05cbc0db FD |
2277 | static inline void tcp_mtu_check_reprobe(struct sock *sk) |
2278 | { | |
2279 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2280 | struct tcp_sock *tp = tcp_sk(sk); | |
2281 | struct net *net = sock_net(sk); | |
2282 | u32 interval; | |
2283 | s32 delta; | |
2284 | ||
2a85388f | 2285 | interval = READ_ONCE(net->ipv4.sysctl_tcp_probe_interval); |
c74df29a | 2286 | delta = tcp_jiffies32 - icsk->icsk_mtup.probe_timestamp; |
05cbc0db FD |
2287 | if (unlikely(delta >= interval * HZ)) { |
2288 | int mss = tcp_current_mss(sk); | |
2289 | ||
2290 | /* Update current search range */ | |
2291 | icsk->icsk_mtup.probe_size = 0; | |
2292 | icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + | |
2293 | sizeof(struct tcphdr) + | |
2294 | icsk->icsk_af_ops->net_header_len; | |
2295 | icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); | |
2296 | ||
2297 | /* Update probe time stamp */ | |
c74df29a | 2298 | icsk->icsk_mtup.probe_timestamp = tcp_jiffies32; |
05cbc0db FD |
2299 | } |
2300 | } | |
2301 | ||
808cf9e3 IL |
2302 | static bool tcp_can_coalesce_send_queue_head(struct sock *sk, int len) |
2303 | { | |
2304 | struct sk_buff *skb, *next; | |
2305 | ||
2306 | skb = tcp_send_head(sk); | |
2307 | tcp_for_write_queue_from_safe(skb, next, sk) { | |
2308 | if (len <= skb->len) | |
2309 | break; | |
2310 | ||
9b65b17d TA |
2311 | if (unlikely(TCP_SKB_CB(skb)->eor) || |
2312 | tcp_has_tx_tstamp(skb) || | |
2313 | !skb_pure_zcopy_same(skb, next)) | |
808cf9e3 IL |
2314 | return false; |
2315 | ||
2316 | len -= skb->len; | |
2317 | } | |
2318 | ||
2319 | return true; | |
2320 | } | |
2321 | ||
5d424d5a | 2322 | /* Create a new MTU probe if we are ready. |
67edfef7 AK |
2323 | * MTU probe is regularly attempting to increase the path MTU by |
2324 | * deliberately sending larger packets. This discovers routing | |
2325 | * changes resulting in larger path MTUs. | |
2326 | * | |
5d424d5a JH |
2327 | * Returns 0 if we should wait to probe (no cwnd available), |
2328 | * 1 if a probe was sent, | |
056834d9 IJ |
2329 | * -1 otherwise |
2330 | */ | |
5d424d5a JH |
2331 | static int tcp_mtu_probe(struct sock *sk) |
2332 | { | |
5d424d5a | 2333 | struct inet_connection_sock *icsk = inet_csk(sk); |
12a59abc | 2334 | struct tcp_sock *tp = tcp_sk(sk); |
5d424d5a | 2335 | struct sk_buff *skb, *nskb, *next; |
6b58e0a5 | 2336 | struct net *net = sock_net(sk); |
5d424d5a | 2337 | int probe_size; |
91cc17c0 | 2338 | int size_needed; |
12a59abc | 2339 | int copy, len; |
5d424d5a | 2340 | int mss_now; |
6b58e0a5 | 2341 | int interval; |
5d424d5a JH |
2342 | |
2343 | /* Not currently probing/verifying, | |
2344 | * not in recovery, | |
2345 | * have enough cwnd, and | |
12a59abc ED |
2346 | * not SACKing (the variable headers throw things off) |
2347 | */ | |
2348 | if (likely(!icsk->icsk_mtup.enabled || | |
2349 | icsk->icsk_mtup.probe_size || | |
2350 | inet_csk(sk)->icsk_ca_state != TCP_CA_Open || | |
40570375 | 2351 | tcp_snd_cwnd(tp) < 11 || |
12a59abc | 2352 | tp->rx_opt.num_sacks || tp->rx_opt.dsack)) |
5d424d5a JH |
2353 | return -1; |
2354 | ||
6b58e0a5 FD |
2355 | /* Use binary search for probe_size between tcp_mss_base, |
2356 | * and current mss_clamp. if (search_high - search_low) | |
2357 | * smaller than a threshold, backoff from probing. | |
2358 | */ | |
0c54b85f | 2359 | mss_now = tcp_current_mss(sk); |
6b58e0a5 FD |
2360 | probe_size = tcp_mtu_to_mss(sk, (icsk->icsk_mtup.search_high + |
2361 | icsk->icsk_mtup.search_low) >> 1); | |
91cc17c0 | 2362 | size_needed = probe_size + (tp->reordering + 1) * tp->mss_cache; |
6b58e0a5 | 2363 | interval = icsk->icsk_mtup.search_high - icsk->icsk_mtup.search_low; |
05cbc0db FD |
2364 | /* When misfortune happens, we are reprobing actively, |
2365 | * and then reprobe timer has expired. We stick with current | |
2366 | * probing process by not resetting search range to its orignal. | |
2367 | */ | |
6b58e0a5 | 2368 | if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high) || |
92c0aa41 | 2369 | interval < READ_ONCE(net->ipv4.sysctl_tcp_probe_threshold)) { |
05cbc0db FD |
2370 | /* Check whether enough time has elaplased for |
2371 | * another round of probing. | |
2372 | */ | |
2373 | tcp_mtu_check_reprobe(sk); | |
5d424d5a JH |
2374 | return -1; |
2375 | } | |
2376 | ||
2377 | /* Have enough data in the send queue to probe? */ | |
7f9c33e5 | 2378 | if (tp->write_seq - tp->snd_nxt < size_needed) |
5d424d5a JH |
2379 | return -1; |
2380 | ||
91cc17c0 IJ |
2381 | if (tp->snd_wnd < size_needed) |
2382 | return -1; | |
90840def | 2383 | if (after(tp->snd_nxt + size_needed, tcp_wnd_end(tp))) |
91cc17c0 | 2384 | return 0; |
5d424d5a | 2385 | |
d67c58e9 | 2386 | /* Do we need to wait to drain cwnd? With none in flight, don't stall */ |
40570375 | 2387 | if (tcp_packets_in_flight(tp) + 2 > tcp_snd_cwnd(tp)) { |
d67c58e9 | 2388 | if (!tcp_packets_in_flight(tp)) |
5d424d5a JH |
2389 | return -1; |
2390 | else | |
2391 | return 0; | |
2392 | } | |
2393 | ||
808cf9e3 IL |
2394 | if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) |
2395 | return -1; | |
2396 | ||
5d424d5a | 2397 | /* We're allowed to probe. Build it now. */ |
f8dd3b8d | 2398 | nskb = tcp_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); |
51456b29 | 2399 | if (!nskb) |
5d424d5a | 2400 | return -1; |
ab4e846a | 2401 | sk_wmem_queued_add(sk, nskb->truesize); |
3ab224be | 2402 | sk_mem_charge(sk, nskb->truesize); |
5d424d5a | 2403 | |
fe067e8a | 2404 | skb = tcp_send_head(sk); |
41477662 | 2405 | skb_copy_decrypted(nskb, skb); |
5a369ca6 | 2406 | mptcp_skb_ext_copy(nskb, skb); |
5d424d5a JH |
2407 | |
2408 | TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq; | |
2409 | TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size; | |
4de075e0 | 2410 | TCP_SKB_CB(nskb)->tcp_flags = TCPHDR_ACK; |
5d424d5a | 2411 | |
50c4817e | 2412 | tcp_insert_write_queue_before(nskb, skb, sk); |
2b7cda9c | 2413 | tcp_highest_sack_replace(sk, skb, nskb); |
50c4817e | 2414 | |
5d424d5a | 2415 | len = 0; |
234b6860 | 2416 | tcp_for_write_queue_from_safe(skb, next, sk) { |
5d424d5a | 2417 | copy = min_t(int, skb->len, probe_size - len); |
98be9b12 | 2418 | skb_copy_bits(skb, 0, skb_put(nskb, copy), copy); |
5d424d5a JH |
2419 | |
2420 | if (skb->len <= copy) { | |
2421 | /* We've eaten all the data from this skb. | |
2422 | * Throw it away. */ | |
4de075e0 | 2423 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags; |
808cf9e3 IL |
2424 | /* If this is the last SKB we copy and eor is set |
2425 | * we need to propagate it to the new skb. | |
2426 | */ | |
2427 | TCP_SKB_CB(nskb)->eor = TCP_SKB_CB(skb)->eor; | |
888a5c53 | 2428 | tcp_skb_collapse_tstamp(nskb, skb); |
fe067e8a | 2429 | tcp_unlink_write_queue(skb, sk); |
03271f3a | 2430 | tcp_wmem_free_skb(sk, skb); |
5d424d5a | 2431 | } else { |
4de075e0 | 2432 | TCP_SKB_CB(nskb)->tcp_flags |= TCP_SKB_CB(skb)->tcp_flags & |
a3433f35 | 2433 | ~(TCPHDR_FIN|TCPHDR_PSH); |
5d424d5a JH |
2434 | if (!skb_shinfo(skb)->nr_frags) { |
2435 | skb_pull(skb, copy); | |
5d424d5a JH |
2436 | } else { |
2437 | __pskb_trim_head(skb, copy); | |
5bbb432c | 2438 | tcp_set_skb_tso_segs(skb, mss_now); |
5d424d5a JH |
2439 | } |
2440 | TCP_SKB_CB(skb)->seq += copy; | |
2441 | } | |
2442 | ||
2443 | len += copy; | |
234b6860 IJ |
2444 | |
2445 | if (len >= probe_size) | |
2446 | break; | |
5d424d5a | 2447 | } |
5bbb432c | 2448 | tcp_init_tso_segs(nskb, nskb->len); |
5d424d5a JH |
2449 | |
2450 | /* We're ready to send. If this fails, the probe will | |
7faee5c0 ED |
2451 | * be resegmented into mss-sized pieces by tcp_write_xmit(). |
2452 | */ | |
5d424d5a JH |
2453 | if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) { |
2454 | /* Decrement cwnd here because we are sending | |
056834d9 | 2455 | * effectively two packets. */ |
40570375 | 2456 | tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - 1); |
66f5fe62 | 2457 | tcp_event_new_data_sent(sk, nskb); |
5d424d5a JH |
2458 | |
2459 | icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len); | |
0e7b1368 JH |
2460 | tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq; |
2461 | tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq; | |
5d424d5a JH |
2462 | |
2463 | return 1; | |
2464 | } | |
2465 | ||
2466 | return -1; | |
2467 | } | |
2468 | ||
864e5c09 | 2469 | static bool tcp_pacing_check(struct sock *sk) |
218af599 | 2470 | { |
864e5c09 ED |
2471 | struct tcp_sock *tp = tcp_sk(sk); |
2472 | ||
2473 | if (!tcp_needs_internal_pacing(sk)) | |
2474 | return false; | |
2475 | ||
2476 | if (tp->tcp_wstamp_ns <= tp->tcp_clock_cache) | |
2477 | return false; | |
2478 | ||
2479 | if (!hrtimer_is_queued(&tp->pacing_timer)) { | |
2480 | hrtimer_start(&tp->pacing_timer, | |
2481 | ns_to_ktime(tp->tcp_wstamp_ns), | |
2482 | HRTIMER_MODE_ABS_PINNED_SOFT); | |
2483 | sock_hold(sk); | |
2484 | } | |
2485 | return true; | |
218af599 ED |
2486 | } |
2487 | ||
f9616c35 ED |
2488 | /* TCP Small Queues : |
2489 | * Control number of packets in qdisc/devices to two packets / or ~1 ms. | |
2490 | * (These limits are doubled for retransmits) | |
2491 | * This allows for : | |
2492 | * - better RTT estimation and ACK scheduling | |
2493 | * - faster recovery | |
2494 | * - high rates | |
2495 | * Alas, some drivers / subsystems require a fair amount | |
2496 | * of queued bytes to ensure line rate. | |
2497 | * One example is wifi aggregation (802.11 AMPDU) | |
2498 | */ | |
2499 | static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb, | |
2500 | unsigned int factor) | |
2501 | { | |
76a9ebe8 | 2502 | unsigned long limit; |
f9616c35 | 2503 | |
76a9ebe8 ED |
2504 | limit = max_t(unsigned long, |
2505 | 2 * skb->truesize, | |
7c68fa2b | 2506 | sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift)); |
c73e5807 ED |
2507 | if (sk->sk_pacing_status == SK_PACING_NONE) |
2508 | limit = min_t(unsigned long, limit, | |
9fb90193 | 2509 | READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes)); |
f9616c35 ED |
2510 | limit <<= factor; |
2511 | ||
a842fe14 ED |
2512 | if (static_branch_unlikely(&tcp_tx_delay_enabled) && |
2513 | tcp_sk(sk)->tcp_tx_delay) { | |
2514 | u64 extra_bytes = (u64)sk->sk_pacing_rate * tcp_sk(sk)->tcp_tx_delay; | |
2515 | ||
2516 | /* TSQ is based on skb truesize sum (sk_wmem_alloc), so we | |
2517 | * approximate our needs assuming an ~100% skb->truesize overhead. | |
2518 | * USEC_PER_SEC is approximated by 2^20. | |
2519 | * do_div(extra_bytes, USEC_PER_SEC/2) is replaced by a right shift. | |
2520 | */ | |
2521 | extra_bytes >>= (20 - 1); | |
2522 | limit += extra_bytes; | |
2523 | } | |
14afee4b | 2524 | if (refcount_read(&sk->sk_wmem_alloc) > limit) { |
75c119af | 2525 | /* Always send skb if rtx queue is empty. |
75eefc6c ED |
2526 | * No need to wait for TX completion to call us back, |
2527 | * after softirq/tasklet schedule. | |
2528 | * This helps when TX completions are delayed too much. | |
2529 | */ | |
75c119af | 2530 | if (tcp_rtx_queue_empty(sk)) |
75eefc6c ED |
2531 | return false; |
2532 | ||
7aa5470c | 2533 | set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); |
f9616c35 ED |
2534 | /* It is possible TX completion already happened |
2535 | * before we set TSQ_THROTTLED, so we must | |
2536 | * test again the condition. | |
2537 | */ | |
2538 | smp_mb__after_atomic(); | |
ce8299b6 | 2539 | if (refcount_read(&sk->sk_wmem_alloc) > limit) |
f9616c35 ED |
2540 | return true; |
2541 | } | |
2542 | return false; | |
2543 | } | |
2544 | ||
05b055e8 FY |
2545 | static void tcp_chrono_set(struct tcp_sock *tp, const enum tcp_chrono new) |
2546 | { | |
628174cc | 2547 | const u32 now = tcp_jiffies32; |
efe967cd | 2548 | enum tcp_chrono old = tp->chrono_type; |
05b055e8 | 2549 | |
efe967cd AB |
2550 | if (old > TCP_CHRONO_UNSPEC) |
2551 | tp->chrono_stat[old - 1] += now - tp->chrono_start; | |
05b055e8 FY |
2552 | tp->chrono_start = now; |
2553 | tp->chrono_type = new; | |
2554 | } | |
2555 | ||
2556 | void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type) | |
2557 | { | |
2558 | struct tcp_sock *tp = tcp_sk(sk); | |
2559 | ||
2560 | /* If there are multiple conditions worthy of tracking in a | |
0f87230d FY |
2561 | * chronograph then the highest priority enum takes precedence |
2562 | * over the other conditions. So that if something "more interesting" | |
05b055e8 FY |
2563 | * starts happening, stop the previous chrono and start a new one. |
2564 | */ | |
2565 | if (type > tp->chrono_type) | |
2566 | tcp_chrono_set(tp, type); | |
2567 | } | |
2568 | ||
2569 | void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type) | |
2570 | { | |
2571 | struct tcp_sock *tp = tcp_sk(sk); | |
2572 | ||
0f87230d FY |
2573 | |
2574 | /* There are multiple conditions worthy of tracking in a | |
2575 | * chronograph, so that the highest priority enum takes | |
2576 | * precedence over the other conditions (see tcp_chrono_start). | |
2577 | * If a condition stops, we only stop chrono tracking if | |
2578 | * it's the "most interesting" or current chrono we are | |
2579 | * tracking and starts busy chrono if we have pending data. | |
2580 | */ | |
75c119af | 2581 | if (tcp_rtx_and_write_queues_empty(sk)) |
0f87230d FY |
2582 | tcp_chrono_set(tp, TCP_CHRONO_UNSPEC); |
2583 | else if (type == tp->chrono_type) | |
2584 | tcp_chrono_set(tp, TCP_CHRONO_BUSY); | |
05b055e8 FY |
2585 | } |
2586 | ||
1da177e4 LT |
2587 | /* This routine writes packets to the network. It advances the |
2588 | * send_head. This happens as incoming acks open up the remote | |
2589 | * window for us. | |
2590 | * | |
f8269a49 IJ |
2591 | * LARGESEND note: !tcp_urg_mode is overkill, only frames between |
2592 | * snd_up-64k-mss .. snd_up cannot be large. However, taking into | |
2593 | * account rare use of URG, this is not a big flaw. | |
2594 | * | |
6ba8a3b1 ND |
2595 | * Send at most one packet when push_one > 0. Temporarily ignore |
2596 | * cwnd limit to force at most one packet out when push_one == 2. | |
2597 | ||
a2a385d6 ED |
2598 | * Returns true, if no segments are in flight and we have queued segments, |
2599 | * but cannot send anything now because of SWS or another problem. | |
1da177e4 | 2600 | */ |
a2a385d6 ED |
2601 | static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, |
2602 | int push_one, gfp_t gfp) | |
1da177e4 LT |
2603 | { |
2604 | struct tcp_sock *tp = tcp_sk(sk); | |
92df7b51 | 2605 | struct sk_buff *skb; |
c1b4a7e6 DM |
2606 | unsigned int tso_segs, sent_pkts; |
2607 | int cwnd_quota; | |
5d424d5a | 2608 | int result; |
5615f886 | 2609 | bool is_cwnd_limited = false, is_rwnd_limited = false; |
605ad7f1 | 2610 | u32 max_segs; |
1da177e4 | 2611 | |
92df7b51 | 2612 | sent_pkts = 0; |
5d424d5a | 2613 | |
ee1836ae | 2614 | tcp_mstamp_refresh(tp); |
d5dd9175 IJ |
2615 | if (!push_one) { |
2616 | /* Do MTU probing. */ | |
2617 | result = tcp_mtu_probe(sk); | |
2618 | if (!result) { | |
a2a385d6 | 2619 | return false; |
d5dd9175 IJ |
2620 | } else if (result > 0) { |
2621 | sent_pkts = 1; | |
2622 | } | |
5d424d5a JH |
2623 | } |
2624 | ||
ed6e7268 | 2625 | max_segs = tcp_tso_segs(sk, mss_now); |
fe067e8a | 2626 | while ((skb = tcp_send_head(sk))) { |
c8ac3774 HX |
2627 | unsigned int limit; |
2628 | ||
79861919 ED |
2629 | if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) { |
2630 | /* "skb_mstamp_ns" is used as a start point for the retransmit timer */ | |
a1ac9c8a MKL |
2631 | tp->tcp_wstamp_ns = tp->tcp_clock_cache; |
2632 | skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); | |
79861919 | 2633 | list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); |
bf50b606 | 2634 | tcp_init_tso_segs(skb, mss_now); |
79861919 ED |
2635 | goto repair; /* Skip network transmission */ |
2636 | } | |
2637 | ||
218af599 ED |
2638 | if (tcp_pacing_check(sk)) |
2639 | break; | |
2640 | ||
5bbb432c | 2641 | tso_segs = tcp_init_tso_segs(skb, mss_now); |
c1b4a7e6 | 2642 | BUG_ON(!tso_segs); |
aa93466b | 2643 | |
b68e9f85 | 2644 | cwnd_quota = tcp_cwnd_test(tp, skb); |
6ba8a3b1 ND |
2645 | if (!cwnd_quota) { |
2646 | if (push_one == 2) | |
2647 | /* Force out a loss probe pkt. */ | |
2648 | cwnd_quota = 1; | |
2649 | else | |
2650 | break; | |
2651 | } | |
b68e9f85 | 2652 | |
5615f886 FY |
2653 | if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now))) { |
2654 | is_rwnd_limited = true; | |
b68e9f85 | 2655 | break; |
5615f886 | 2656 | } |
b68e9f85 | 2657 | |
d6a4e26a | 2658 | if (tso_segs == 1) { |
c1b4a7e6 DM |
2659 | if (unlikely(!tcp_nagle_test(tp, skb, mss_now, |
2660 | (tcp_skb_is_last(sk, skb) ? | |
2661 | nonagle : TCP_NAGLE_PUSH)))) | |
2662 | break; | |
2663 | } else { | |
ca8a2263 | 2664 | if (!push_one && |
605ad7f1 | 2665 | tcp_tso_should_defer(sk, skb, &is_cwnd_limited, |
f9bfe4e6 | 2666 | &is_rwnd_limited, max_segs)) |
c1b4a7e6 DM |
2667 | break; |
2668 | } | |
aa93466b | 2669 | |
605ad7f1 | 2670 | limit = mss_now; |
d6a4e26a | 2671 | if (tso_segs > 1 && !tcp_urg_mode(tp)) |
605ad7f1 ED |
2672 | limit = tcp_mss_split_point(sk, skb, mss_now, |
2673 | min_t(unsigned int, | |
2674 | cwnd_quota, | |
2675 | max_segs), | |
2676 | nonagle); | |
2677 | ||
2678 | if (skb->len > limit && | |
56483341 | 2679 | unlikely(tso_fragment(sk, skb, limit, mss_now, gfp))) |
605ad7f1 ED |
2680 | break; |
2681 | ||
f9616c35 ED |
2682 | if (tcp_small_queue_check(sk, skb, 0)) |
2683 | break; | |
c9eeec26 | 2684 | |
1f85e626 ED |
2685 | /* Argh, we hit an empty skb(), presumably a thread |
2686 | * is sleeping in sendmsg()/sk_stream_wait_memory(). | |
2687 | * We do not want to send a pure-ack packet and have | |
2688 | * a strange looking rtx queue with empty packet(s). | |
2689 | */ | |
2690 | if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) | |
2691 | break; | |
2692 | ||
d5dd9175 | 2693 | if (unlikely(tcp_transmit_skb(sk, skb, 1, gfp))) |
92df7b51 | 2694 | break; |
1da177e4 | 2695 | |
ec342325 | 2696 | repair: |
92df7b51 DM |
2697 | /* Advance the send_head. This one is sent out. |
2698 | * This call will increment packets_out. | |
2699 | */ | |
66f5fe62 | 2700 | tcp_event_new_data_sent(sk, skb); |
1da177e4 | 2701 | |
92df7b51 | 2702 | tcp_minshall_update(tp, mss_now, skb); |
a262f0cd | 2703 | sent_pkts += tcp_skb_pcount(skb); |
d5dd9175 IJ |
2704 | |
2705 | if (push_one) | |
2706 | break; | |
92df7b51 | 2707 | } |
1da177e4 | 2708 | |
5615f886 FY |
2709 | if (is_rwnd_limited) |
2710 | tcp_chrono_start(sk, TCP_CHRONO_RWND_LIMITED); | |
2711 | else | |
2712 | tcp_chrono_stop(sk, TCP_CHRONO_RWND_LIMITED); | |
2713 | ||
40570375 | 2714 | is_cwnd_limited |= (tcp_packets_in_flight(tp) >= tcp_snd_cwnd(tp)); |
299bcb55 NC |
2715 | if (likely(sent_pkts || is_cwnd_limited)) |
2716 | tcp_cwnd_validate(sk, is_cwnd_limited); | |
2717 | ||
aa93466b | 2718 | if (likely(sent_pkts)) { |
684bad11 YC |
2719 | if (tcp_in_cwnd_reduction(sk)) |
2720 | tp->prr_out += sent_pkts; | |
6ba8a3b1 ND |
2721 | |
2722 | /* Send one loss probe per tail loss episode. */ | |
2723 | if (push_one != 2) | |
ed66dfaf | 2724 | tcp_schedule_loss_probe(sk, false); |
a2a385d6 | 2725 | return false; |
1da177e4 | 2726 | } |
75c119af | 2727 | return !tp->packets_out && !tcp_write_queue_empty(sk); |
6ba8a3b1 ND |
2728 | } |
2729 | ||
ed66dfaf | 2730 | bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto) |
6ba8a3b1 ND |
2731 | { |
2732 | struct inet_connection_sock *icsk = inet_csk(sk); | |
2733 | struct tcp_sock *tp = tcp_sk(sk); | |
a2815817 | 2734 | u32 timeout, rto_delta_us; |
2ae21cf5 | 2735 | int early_retrans; |
6ba8a3b1 | 2736 | |
6ba8a3b1 ND |
2737 | /* Don't do any loss probe on a Fast Open connection before 3WHS |
2738 | * finishes. | |
2739 | */ | |
d983ea6f | 2740 | if (rcu_access_pointer(tp->fastopen_rsk)) |
6ba8a3b1 ND |
2741 | return false; |
2742 | ||
52e65865 | 2743 | early_retrans = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_early_retrans); |
6ba8a3b1 | 2744 | /* Schedule a loss probe in 2*RTT for SACK capable connections |
b4f70c3d | 2745 | * not in loss recovery, that are either limited by cwnd or application. |
6ba8a3b1 | 2746 | */ |
2ae21cf5 | 2747 | if ((early_retrans != 3 && early_retrans != 4) || |
bec41a11 | 2748 | !tp->packets_out || !tcp_is_sack(tp) || |
b4f70c3d NC |
2749 | (icsk->icsk_ca_state != TCP_CA_Open && |
2750 | icsk->icsk_ca_state != TCP_CA_CWR)) | |
6ba8a3b1 ND |
2751 | return false; |
2752 | ||
bb4d991a | 2753 | /* Probe timeout is 2*rtt. Add minimum RTO to account |
f9b99582 YC |
2754 | * for delayed ack when there's one outstanding packet. If no RTT |
2755 | * sample is available then probe after TCP_TIMEOUT_INIT. | |
6ba8a3b1 | 2756 | */ |
bb4d991a YC |
2757 | if (tp->srtt_us) { |
2758 | timeout = usecs_to_jiffies(tp->srtt_us >> 2); | |
2759 | if (tp->packets_out == 1) | |
2760 | timeout += TCP_RTO_MIN; | |
2761 | else | |
2762 | timeout += TCP_TIMEOUT_MIN; | |
2763 | } else { | |
2764 | timeout = TCP_TIMEOUT_INIT; | |
2765 | } | |
6ba8a3b1 | 2766 | |
a2815817 | 2767 | /* If the RTO formula yields an earlier time, then use that time. */ |
ed66dfaf NC |
2768 | rto_delta_us = advancing_rto ? |
2769 | jiffies_to_usecs(inet_csk(sk)->icsk_rto) : | |
2770 | tcp_rto_delta_us(sk); /* How far in future is RTO? */ | |
a2815817 NC |
2771 | if (rto_delta_us > 0) |
2772 | timeout = min_t(u32, timeout, usecs_to_jiffies(rto_delta_us)); | |
6ba8a3b1 | 2773 | |
8dc242ad | 2774 | tcp_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout, TCP_RTO_MAX); |
6ba8a3b1 ND |
2775 | return true; |
2776 | } | |
2777 | ||
1f3279ae ED |
2778 | /* Thanks to skb fast clones, we can detect if a prior transmit of |
2779 | * a packet is still in a qdisc or driver queue. | |
2780 | * In this case, there is very little point doing a retransmit ! | |
1f3279ae | 2781 | */ |
f4dae54e | 2782 | static bool skb_still_in_host_queue(struct sock *sk, |
1f3279ae ED |
2783 | const struct sk_buff *skb) |
2784 | { | |
39bb5e62 | 2785 | if (unlikely(skb_fclone_busy(sk, skb))) { |
f4dae54e ED |
2786 | set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags); |
2787 | smp_mb__after_atomic(); | |
2788 | if (skb_fclone_busy(sk, skb)) { | |
2789 | NET_INC_STATS(sock_net(sk), | |
2790 | LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES); | |
2791 | return true; | |
2792 | } | |
1f3279ae ED |
2793 | } |
2794 | return false; | |
2795 | } | |
2796 | ||
b340b264 | 2797 | /* When probe timeout (PTO) fires, try send a new segment if possible, else |
6ba8a3b1 ND |
2798 | * retransmit the last segment. |
2799 | */ | |
2800 | void tcp_send_loss_probe(struct sock *sk) | |
2801 | { | |
9b717a8d | 2802 | struct tcp_sock *tp = tcp_sk(sk); |
6ba8a3b1 ND |
2803 | struct sk_buff *skb; |
2804 | int pcount; | |
2805 | int mss = tcp_current_mss(sk); | |
6ba8a3b1 | 2806 | |
76be93fc YC |
2807 | /* At most one outstanding TLP */ |
2808 | if (tp->tlp_high_seq) | |
2809 | goto rearm_timer; | |
2810 | ||
2811 | tp->tlp_retrans = 0; | |
b340b264 | 2812 | skb = tcp_send_head(sk); |
75c119af ED |
2813 | if (skb && tcp_snd_wnd_test(tp, skb, mss)) { |
2814 | pcount = tp->packets_out; | |
2815 | tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC); | |
2816 | if (tp->packets_out > pcount) | |
2817 | goto probe_sent; | |
2818 | goto rearm_timer; | |
6ba8a3b1 | 2819 | } |
75c119af | 2820 | skb = skb_rb_last(&sk->tcp_rtx_queue); |
b2b7af86 YC |
2821 | if (unlikely(!skb)) { |
2822 | WARN_ONCE(tp->packets_out, | |
2823 | "invalid inflight: %u state %u cwnd %u mss %d\n", | |
40570375 | 2824 | tp->packets_out, sk->sk_state, tcp_snd_cwnd(tp), mss); |
b2b7af86 YC |
2825 | inet_csk(sk)->icsk_pending = 0; |
2826 | return; | |
2827 | } | |
6ba8a3b1 | 2828 | |
1f3279ae ED |
2829 | if (skb_still_in_host_queue(sk, skb)) |
2830 | goto rearm_timer; | |
2831 | ||
6ba8a3b1 ND |
2832 | pcount = tcp_skb_pcount(skb); |
2833 | if (WARN_ON(!pcount)) | |
2834 | goto rearm_timer; | |
2835 | ||
2836 | if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) { | |
75c119af ED |
2837 | if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, |
2838 | (pcount - 1) * mss, mss, | |
6cc55e09 | 2839 | GFP_ATOMIC))) |
6ba8a3b1 | 2840 | goto rearm_timer; |
75c119af | 2841 | skb = skb_rb_next(skb); |
6ba8a3b1 ND |
2842 | } |
2843 | ||
2844 | if (WARN_ON(!skb || !tcp_skb_pcount(skb))) | |
2845 | goto rearm_timer; | |
2846 | ||
10d3be56 | 2847 | if (__tcp_retransmit_skb(sk, skb, 1)) |
b340b264 | 2848 | goto rearm_timer; |
6ba8a3b1 | 2849 | |
76be93fc YC |
2850 | tp->tlp_retrans = 1; |
2851 | ||
2852 | probe_sent: | |
9b717a8d | 2853 | /* Record snd_nxt for loss detection. */ |
b340b264 | 2854 | tp->tlp_high_seq = tp->snd_nxt; |
9b717a8d | 2855 | |
c10d9310 | 2856 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPLOSSPROBES); |
b340b264 YC |
2857 | /* Reset s.t. tcp_rearm_rto will restart timer from now */ |
2858 | inet_csk(sk)->icsk_pending = 0; | |
6ba8a3b1 | 2859 | rearm_timer: |
fcd16c0a | 2860 | tcp_rearm_rto(sk); |
1da177e4 LT |
2861 | } |
2862 | ||
a762a980 DM |
2863 | /* Push out any pending frames which were held back due to |
2864 | * TCP_CORK or attempt at coalescing tiny packets. | |
2865 | * The socket must be locked by the caller. | |
2866 | */ | |
9e412ba7 IJ |
2867 | void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, |
2868 | int nonagle) | |
a762a980 | 2869 | { |
726e07a8 IJ |
2870 | /* If we are closed, the bytes will have to remain here. |
2871 | * In time closedown will finish, we empty the write queue and | |
2872 | * all will be happy. | |
2873 | */ | |
2874 | if (unlikely(sk->sk_state == TCP_CLOSE)) | |
2875 | return; | |
2876 | ||
99a1dec7 | 2877 | if (tcp_write_xmit(sk, cur_mss, nonagle, 0, |
7450aaf6 | 2878 | sk_gfp_mask(sk, GFP_ATOMIC))) |
726e07a8 | 2879 | tcp_check_probe_timer(sk); |
a762a980 DM |
2880 | } |
2881 | ||
c1b4a7e6 DM |
2882 | /* Send _single_ skb sitting at the send head. This function requires |
2883 | * true push pending frames to setup probe timer etc. | |
2884 | */ | |
2885 | void tcp_push_one(struct sock *sk, unsigned int mss_now) | |
2886 | { | |
fe067e8a | 2887 | struct sk_buff *skb = tcp_send_head(sk); |
c1b4a7e6 DM |
2888 | |
2889 | BUG_ON(!skb || skb->len < mss_now); | |
2890 | ||
d5dd9175 | 2891 | tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation); |
c1b4a7e6 DM |
2892 | } |
2893 | ||
1da177e4 LT |
2894 | /* This function returns the amount that we can raise the |
2895 | * usable window based on the following constraints | |
e905a9ed | 2896 | * |
1da177e4 LT |
2897 | * 1. The window can never be shrunk once it is offered (RFC 793) |
2898 | * 2. We limit memory per socket | |
2899 | * | |
2900 | * RFC 1122: | |
2901 | * "the suggested [SWS] avoidance algorithm for the receiver is to keep | |
2902 | * RECV.NEXT + RCV.WIN fixed until: | |
2903 | * RCV.BUFF - RCV.USER - RCV.WINDOW >= min(1/2 RCV.BUFF, MSS)" | |
2904 | * | |
2905 | * i.e. don't raise the right edge of the window until you can raise | |
2906 | * it at least MSS bytes. | |
2907 | * | |
2908 | * Unfortunately, the recommended algorithm breaks header prediction, | |
2909 | * since header prediction assumes th->window stays fixed. | |
2910 | * | |
2911 | * Strictly speaking, keeping th->window fixed violates the receiver | |
2912 | * side SWS prevention criteria. The problem is that under this rule | |
2913 | * a stream of single byte packets will cause the right side of the | |
2914 | * window to always advance by a single byte. | |
e905a9ed | 2915 | * |
1da177e4 LT |
2916 | * Of course, if the sender implements sender side SWS prevention |
2917 | * then this will not be a problem. | |
e905a9ed | 2918 | * |
1da177e4 | 2919 | * BSD seems to make the following compromise: |
e905a9ed | 2920 | * |
1da177e4 LT |
2921 | * If the free space is less than the 1/4 of the maximum |
2922 | * space available and the free space is less than 1/2 mss, | |
2923 | * then set the window to 0. | |
2924 | * [ Actually, bsd uses MSS and 1/4 of maximal _window_ ] | |
2925 | * Otherwise, just prevent the window from shrinking | |
2926 | * and from being larger than the largest representable value. | |
2927 | * | |
2928 | * This prevents incremental opening of the window in the regime | |
2929 | * where TCP is limited by the speed of the reader side taking | |
2930 | * data out of the TCP receive queue. It does nothing about | |
2931 | * those cases where the window is constrained on the sender side | |
2932 | * because the pipeline is full. | |
2933 | * | |
2934 | * BSD also seems to "accidentally" limit itself to windows that are a | |
2935 | * multiple of MSS, at least until the free space gets quite small. | |
2936 | * This would appear to be a side effect of the mbuf implementation. | |
2937 | * Combining these two algorithms results in the observed behavior | |
2938 | * of having a fixed window size at almost all times. | |
2939 | * | |
2940 | * Below we obtain similar behavior by forcing the offered window to | |
2941 | * a multiple of the mss when it is feasible to do so. | |
2942 | * | |
2943 | * Note, we don't "adjust" for TIMESTAMP or SACK option bytes. | |
2944 | * Regular options like TIMESTAMP are taken into account. | |
2945 | */ | |
2946 | u32 __tcp_select_window(struct sock *sk) | |
2947 | { | |
463c84b9 | 2948 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 2949 | struct tcp_sock *tp = tcp_sk(sk); |
caa20d9a | 2950 | /* MSS for the peer's data. Previous versions used mss_clamp |
1da177e4 LT |
2951 | * here. I don't know if the value based on our guesses |
2952 | * of peer's MSS is better for the performance. It's more correct | |
2953 | * but may be worse for the performance because of rcv_mss | |
2954 | * fluctuations. --SAW 1998/11/1 | |
2955 | */ | |
463c84b9 | 2956 | int mss = icsk->icsk_ack.rcv_mss; |
1da177e4 | 2957 | int free_space = tcp_space(sk); |
86c1a045 | 2958 | int allowed_space = tcp_full_space(sk); |
071c8ed6 FW |
2959 | int full_space, window; |
2960 | ||
2961 | if (sk_is_mptcp(sk)) | |
2962 | mptcp_space(sk, &free_space, &allowed_space); | |
2963 | ||
2964 | full_space = min_t(int, tp->window_clamp, allowed_space); | |
1da177e4 | 2965 | |
06425c30 | 2966 | if (unlikely(mss > full_space)) { |
e905a9ed | 2967 | mss = full_space; |
06425c30 ED |
2968 | if (mss <= 0) |
2969 | return 0; | |
2970 | } | |
b92edbe0 | 2971 | if (free_space < (full_space >> 1)) { |
463c84b9 | 2972 | icsk->icsk_ack.quick = 0; |
1da177e4 | 2973 | |
b8da51eb | 2974 | if (tcp_under_memory_pressure(sk)) |
053f3684 | 2975 | tcp_adjust_rcv_ssthresh(sk); |
1da177e4 | 2976 | |
86c1a045 FW |
2977 | /* free_space might become our new window, make sure we don't |
2978 | * increase it due to wscale. | |
2979 | */ | |
2980 | free_space = round_down(free_space, 1 << tp->rx_opt.rcv_wscale); | |
2981 | ||
2982 | /* if free space is less than mss estimate, or is below 1/16th | |
2983 | * of the maximum allowed, try to move to zero-window, else | |
2984 | * tcp_clamp_window() will grow rcv buf up to tcp_rmem[2], and | |
2985 | * new incoming data is dropped due to memory limits. | |
2986 | * With large window, mss test triggers way too late in order | |
2987 | * to announce zero window in time before rmem limit kicks in. | |
2988 | */ | |
2989 | if (free_space < (allowed_space >> 4) || free_space < mss) | |
1da177e4 LT |
2990 | return 0; |
2991 | } | |
2992 | ||
2993 | if (free_space > tp->rcv_ssthresh) | |
2994 | free_space = tp->rcv_ssthresh; | |
2995 | ||
2996 | /* Don't do rounding if we are using window scaling, since the | |
2997 | * scaled window will not line up with the MSS boundary anyway. | |
2998 | */ | |
1da177e4 LT |
2999 | if (tp->rx_opt.rcv_wscale) { |
3000 | window = free_space; | |
3001 | ||
3002 | /* Advertise enough space so that it won't get scaled away. | |
3003 | * Import case: prevent zero window announcement if | |
3004 | * 1<<rcv_wscale > mss. | |
3005 | */ | |
1935299d | 3006 | window = ALIGN(window, (1 << tp->rx_opt.rcv_wscale)); |
1da177e4 | 3007 | } else { |
1935299d | 3008 | window = tp->rcv_wnd; |
1da177e4 LT |
3009 | /* Get the largest window that is a nice multiple of mss. |
3010 | * Window clamp already applied above. | |
3011 | * If our current window offering is within 1 mss of the | |
3012 | * free space we just keep it. This prevents the divide | |
3013 | * and multiply from happening most of the time. | |
3014 | * We also don't do any window rounding when the free space | |
3015 | * is too small. | |
3016 | */ | |
3017 | if (window <= free_space - mss || window > free_space) | |
1935299d | 3018 | window = rounddown(free_space, mss); |
84565070 | 3019 | else if (mss == full_space && |
b92edbe0 | 3020 | free_space > window + (full_space >> 1)) |
84565070 | 3021 | window = free_space; |
1da177e4 LT |
3022 | } |
3023 | ||
3024 | return window; | |
3025 | } | |
3026 | ||
cfea5a68 MKL |
3027 | void tcp_skb_collapse_tstamp(struct sk_buff *skb, |
3028 | const struct sk_buff *next_skb) | |
082ac2d5 | 3029 | { |
0a2cf20c SHY |
3030 | if (unlikely(tcp_has_tx_tstamp(next_skb))) { |
3031 | const struct skb_shared_info *next_shinfo = | |
3032 | skb_shinfo(next_skb); | |
082ac2d5 MKL |
3033 | struct skb_shared_info *shinfo = skb_shinfo(skb); |
3034 | ||
0a2cf20c | 3035 | shinfo->tx_flags |= next_shinfo->tx_flags & SKBTX_ANY_TSTAMP; |
082ac2d5 | 3036 | shinfo->tskey = next_shinfo->tskey; |
2de8023e MKL |
3037 | TCP_SKB_CB(skb)->txstamp_ack |= |
3038 | TCP_SKB_CB(next_skb)->txstamp_ack; | |
082ac2d5 MKL |
3039 | } |
3040 | } | |
3041 | ||
4a17fc3a | 3042 | /* Collapses two adjacent SKB's during retransmission. */ |
f8071cde | 3043 | static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb) |
1da177e4 LT |
3044 | { |
3045 | struct tcp_sock *tp = tcp_sk(sk); | |
75c119af | 3046 | struct sk_buff *next_skb = skb_rb_next(skb); |
13dde04f | 3047 | int next_skb_size; |
1da177e4 | 3048 | |
058dc334 | 3049 | next_skb_size = next_skb->len; |
1da177e4 | 3050 | |
058dc334 | 3051 | BUG_ON(tcp_skb_pcount(skb) != 1 || tcp_skb_pcount(next_skb) != 1); |
a6963a6b | 3052 | |
bd446314 ED |
3053 | if (next_skb_size && !tcp_skb_shift(skb, next_skb, 1, next_skb_size)) |
3054 | return false; | |
3055 | ||
2b7cda9c | 3056 | tcp_highest_sack_replace(sk, next_skb, skb); |
1da177e4 | 3057 | |
058dc334 IJ |
3058 | /* Update sequence range on original skb. */ |
3059 | TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(next_skb)->end_seq; | |
1da177e4 | 3060 | |
e6c7d085 | 3061 | /* Merge over control information. This moves PSH/FIN etc. over */ |
4de075e0 | 3062 | TCP_SKB_CB(skb)->tcp_flags |= TCP_SKB_CB(next_skb)->tcp_flags; |
058dc334 IJ |
3063 | |
3064 | /* All done, get rid of second SKB and account for it so | |
3065 | * packet counting does not break. | |
3066 | */ | |
3067 | TCP_SKB_CB(skb)->sacked |= TCP_SKB_CB(next_skb)->sacked & TCPCB_EVER_RETRANS; | |
a643b5d4 | 3068 | TCP_SKB_CB(skb)->eor = TCP_SKB_CB(next_skb)->eor; |
058dc334 IJ |
3069 | |
3070 | /* changed transmit queue under us so clear hints */ | |
ef9da47c IJ |
3071 | tcp_clear_retrans_hints_partial(tp); |
3072 | if (next_skb == tp->retransmit_skb_hint) | |
3073 | tp->retransmit_skb_hint = skb; | |
058dc334 | 3074 | |
797108d1 IJ |
3075 | tcp_adjust_pcount(sk, next_skb, tcp_skb_pcount(next_skb)); |
3076 | ||
082ac2d5 MKL |
3077 | tcp_skb_collapse_tstamp(skb, next_skb); |
3078 | ||
75c119af | 3079 | tcp_rtx_queue_unlink_and_free(next_skb, sk); |
f8071cde | 3080 | return true; |
1da177e4 LT |
3081 | } |
3082 | ||
67edfef7 | 3083 | /* Check if coalescing SKBs is legal. */ |
a2a385d6 | 3084 | static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb) |
4a17fc3a IJ |
3085 | { |
3086 | if (tcp_skb_pcount(skb) > 1) | |
a2a385d6 | 3087 | return false; |
4a17fc3a | 3088 | if (skb_cloned(skb)) |
a2a385d6 | 3089 | return false; |
2331ccc5 | 3090 | /* Some heuristics for collapsing over SACK'd could be invented */ |
4a17fc3a | 3091 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) |
a2a385d6 | 3092 | return false; |
4a17fc3a | 3093 | |
a2a385d6 | 3094 | return true; |
4a17fc3a IJ |
3095 | } |
3096 | ||
67edfef7 AK |
3097 | /* Collapse packets in the retransmit queue to make to create |
3098 | * less packets on the wire. This is only done on retransmission. | |
3099 | */ | |
4a17fc3a IJ |
3100 | static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, |
3101 | int space) | |
3102 | { | |
3103 | struct tcp_sock *tp = tcp_sk(sk); | |
3104 | struct sk_buff *skb = to, *tmp; | |
a2a385d6 | 3105 | bool first = true; |
4a17fc3a | 3106 | |
1a63cb91 | 3107 | if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse)) |
4a17fc3a | 3108 | return; |
4de075e0 | 3109 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) |
4a17fc3a IJ |
3110 | return; |
3111 | ||
75c119af | 3112 | skb_rbtree_walk_from_safe(skb, tmp) { |
4a17fc3a IJ |
3113 | if (!tcp_can_collapse(sk, skb)) |
3114 | break; | |
3115 | ||
85712484 | 3116 | if (!tcp_skb_can_collapse(to, skb)) |
a643b5d4 MKL |
3117 | break; |
3118 | ||
4a17fc3a IJ |
3119 | space -= skb->len; |
3120 | ||
3121 | if (first) { | |
a2a385d6 | 3122 | first = false; |
4a17fc3a IJ |
3123 | continue; |
3124 | } | |
3125 | ||
3126 | if (space < 0) | |
3127 | break; | |
4a17fc3a IJ |
3128 | |
3129 | if (after(TCP_SKB_CB(skb)->end_seq, tcp_wnd_end(tp))) | |
3130 | break; | |
3131 | ||
f8071cde ED |
3132 | if (!tcp_collapse_retrans(sk, to)) |
3133 | break; | |
4a17fc3a IJ |
3134 | } |
3135 | } | |
3136 | ||
1da177e4 LT |
3137 | /* This retransmits one SKB. Policy decisions and retransmit queue |
3138 | * state updates are done by the caller. Returns non-zero if an | |
3139 | * error occurred which prevented the send. | |
3140 | */ | |
10d3be56 | 3141 | int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) |
1da177e4 | 3142 | { |
5d424d5a | 3143 | struct inet_connection_sock *icsk = inet_csk(sk); |
10d3be56 | 3144 | struct tcp_sock *tp = tcp_sk(sk); |
7d227cd2 | 3145 | unsigned int cur_mss; |
10d3be56 | 3146 | int diff, len, err; |
536a6c8e | 3147 | int avail_wnd; |
1da177e4 | 3148 | |
10d3be56 ED |
3149 | /* Inconclusive MTU probe */ |
3150 | if (icsk->icsk_mtup.probe_size) | |
5d424d5a | 3151 | icsk->icsk_mtup.probe_size = 0; |
1da177e4 | 3152 | |
1f3279ae ED |
3153 | if (skb_still_in_host_queue(sk, skb)) |
3154 | return -EBUSY; | |
3155 | ||
1da177e4 | 3156 | if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) { |
7f582b24 ED |
3157 | if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) { |
3158 | WARN_ON_ONCE(1); | |
3159 | return -EINVAL; | |
3160 | } | |
1da177e4 LT |
3161 | if (tcp_trim_head(sk, skb, tp->snd_una - TCP_SKB_CB(skb)->seq)) |
3162 | return -ENOMEM; | |
3163 | } | |
3164 | ||
7d227cd2 SS |
3165 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) |
3166 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
3167 | ||
0c54b85f | 3168 | cur_mss = tcp_current_mss(sk); |
536a6c8e | 3169 | avail_wnd = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
7d227cd2 | 3170 | |
1da177e4 LT |
3171 | /* If receiver has shrunk his window, and skb is out of |
3172 | * new window, do not retransmit it. The exception is the | |
3173 | * case, when window is shrunk to zero. In this case | |
536a6c8e | 3174 | * our retransmit of one segment serves as a zero window probe. |
1da177e4 | 3175 | */ |
536a6c8e YL |
3176 | if (avail_wnd <= 0) { |
3177 | if (TCP_SKB_CB(skb)->seq != tp->snd_una) | |
3178 | return -EAGAIN; | |
3179 | avail_wnd = cur_mss; | |
3180 | } | |
1da177e4 | 3181 | |
10d3be56 | 3182 | len = cur_mss * segs; |
536a6c8e YL |
3183 | if (len > avail_wnd) { |
3184 | len = rounddown(avail_wnd, cur_mss); | |
3185 | if (!len) | |
3186 | len = avail_wnd; | |
3187 | } | |
10d3be56 | 3188 | if (skb->len > len) { |
75c119af ED |
3189 | if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len, |
3190 | cur_mss, GFP_ATOMIC)) | |
1da177e4 | 3191 | return -ENOMEM; /* We'll try again later. */ |
02276f3c | 3192 | } else { |
c4777efa | 3193 | if (skb_unclone_keeptruesize(skb, GFP_ATOMIC)) |
10d3be56 | 3194 | return -ENOMEM; |
9eb9362e | 3195 | |
10d3be56 ED |
3196 | diff = tcp_skb_pcount(skb); |
3197 | tcp_set_skb_tso_segs(skb, cur_mss); | |
3198 | diff -= tcp_skb_pcount(skb); | |
3199 | if (diff) | |
3200 | tcp_adjust_pcount(sk, skb, diff); | |
536a6c8e YL |
3201 | avail_wnd = min_t(int, avail_wnd, cur_mss); |
3202 | if (skb->len < avail_wnd) | |
3203 | tcp_retrans_try_collapse(sk, skb, avail_wnd); | |
1da177e4 LT |
3204 | } |
3205 | ||
49213555 DB |
3206 | /* RFC3168, section 6.1.1.1. ECN fallback */ |
3207 | if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN_ECN) == TCPHDR_SYN_ECN) | |
3208 | tcp_ecn_clear_syn(sk, skb); | |
3209 | ||
678550c6 YC |
3210 | /* Update global and local TCP statistics. */ |
3211 | segs = tcp_skb_pcount(skb); | |
3212 | TCP_ADD_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS, segs); | |
3213 | if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) | |
3214 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
3215 | tp->total_retrans += segs; | |
fb31c9b9 | 3216 | tp->bytes_retrans += skb->len; |
678550c6 | 3217 | |
50bceae9 TG |
3218 | /* make sure skb->data is aligned on arches that require it |
3219 | * and check if ack-trimming & collapsing extended the headroom | |
3220 | * beyond what csum_start can cover. | |
3221 | */ | |
3222 | if (unlikely((NET_IP_ALIGN && ((unsigned long)skb->data & 3)) || | |
3223 | skb_headroom(skb) >= 0xFFFF)) { | |
10a81980 ED |
3224 | struct sk_buff *nskb; |
3225 | ||
e2080072 ED |
3226 | tcp_skb_tsorted_save(skb) { |
3227 | nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC); | |
07f8e4d0 FW |
3228 | if (nskb) { |
3229 | nskb->dev = NULL; | |
3230 | err = tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC); | |
3231 | } else { | |
3232 | err = -ENOBUFS; | |
3233 | } | |
e2080072 ED |
3234 | } tcp_skb_tsorted_restore(skb); |
3235 | ||
5889e2c0 | 3236 | if (!err) { |
a7a25630 | 3237 | tcp_update_skb_after_send(sk, skb, tp->tcp_wstamp_ns); |
5889e2c0 YS |
3238 | tcp_rate_skb_sent(sk, skb); |
3239 | } | |
117632e6 | 3240 | } else { |
c84a5711 | 3241 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
117632e6 | 3242 | } |
c84a5711 | 3243 | |
7f12422c YC |
3244 | /* To avoid taking spuriously low RTT samples based on a timestamp |
3245 | * for a transmit that never happened, always mark EVER_RETRANS | |
3246 | */ | |
3247 | TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS; | |
3248 | ||
a31ad29e LB |
3249 | if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RETRANS_CB_FLAG)) |
3250 | tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RETRANS_CB, | |
3251 | TCP_SKB_CB(skb)->seq, segs, err); | |
3252 | ||
fc9f3501 | 3253 | if (likely(!err)) { |
e086101b | 3254 | trace_tcp_retransmit_skb(sk, skb); |
678550c6 | 3255 | } else if (err != -EBUSY) { |
ec641b39 | 3256 | NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs); |
fc9f3501 | 3257 | } |
c84a5711 | 3258 | return err; |
93b174ad YC |
3259 | } |
3260 | ||
10d3be56 | 3261 | int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs) |
93b174ad YC |
3262 | { |
3263 | struct tcp_sock *tp = tcp_sk(sk); | |
10d3be56 | 3264 | int err = __tcp_retransmit_skb(sk, skb, segs); |
1da177e4 LT |
3265 | |
3266 | if (err == 0) { | |
1da177e4 | 3267 | #if FASTRETRANS_DEBUG > 0 |
056834d9 | 3268 | if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) { |
e87cc472 | 3269 | net_dbg_ratelimited("retrans_out leaked\n"); |
1da177e4 LT |
3270 | } |
3271 | #endif | |
3272 | TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; | |
3273 | tp->retrans_out += tcp_skb_pcount(skb); | |
1da177e4 | 3274 | } |
6e08d5e3 | 3275 | |
7ae18975 YC |
3276 | /* Save stamp of the first (attempted) retransmit. */ |
3277 | if (!tp->retrans_stamp) | |
3278 | tp->retrans_stamp = tcp_skb_timestamp(skb); | |
3279 | ||
6e08d5e3 YC |
3280 | if (tp->undo_retrans < 0) |
3281 | tp->undo_retrans = 0; | |
3282 | tp->undo_retrans += tcp_skb_pcount(skb); | |
1da177e4 LT |
3283 | return err; |
3284 | } | |
3285 | ||
3286 | /* This gets called after a retransmit timeout, and the initially | |
3287 | * retransmitted data is acknowledged. It tries to continue | |
3288 | * resending the rest of the retransmit queue, until either | |
3289 | * we've sent it all or the congestion window limit is reached. | |
1da177e4 LT |
3290 | */ |
3291 | void tcp_xmit_retransmit_queue(struct sock *sk) | |
3292 | { | |
6687e988 | 3293 | const struct inet_connection_sock *icsk = inet_csk(sk); |
b9f1f1ce | 3294 | struct sk_buff *skb, *rtx_head, *hole = NULL; |
1da177e4 | 3295 | struct tcp_sock *tp = tcp_sk(sk); |
916e6d1a | 3296 | bool rearm_timer = false; |
840a3cbe | 3297 | u32 max_segs; |
61eb55f4 | 3298 | int mib_idx; |
6a438bbe | 3299 | |
45e77d31 IJ |
3300 | if (!tp->packets_out) |
3301 | return; | |
3302 | ||
b9f1f1ce ED |
3303 | rtx_head = tcp_rtx_queue_head(sk); |
3304 | skb = tp->retransmit_skb_hint ?: rtx_head; | |
ed6e7268 | 3305 | max_segs = tcp_tso_segs(sk, tcp_current_mss(sk)); |
75c119af | 3306 | skb_rbtree_walk_from(skb) { |
dca0aaf8 | 3307 | __u8 sacked; |
10d3be56 | 3308 | int segs; |
1da177e4 | 3309 | |
218af599 ED |
3310 | if (tcp_pacing_check(sk)) |
3311 | break; | |
3312 | ||
08ebd172 | 3313 | /* we could do better than to assign each time */ |
51456b29 | 3314 | if (!hole) |
0e1c54c2 | 3315 | tp->retransmit_skb_hint = skb; |
08ebd172 | 3316 | |
40570375 | 3317 | segs = tcp_snd_cwnd(tp) - tcp_packets_in_flight(tp); |
10d3be56 | 3318 | if (segs <= 0) |
916e6d1a | 3319 | break; |
dca0aaf8 | 3320 | sacked = TCP_SKB_CB(skb)->sacked; |
a3d2e9f8 ED |
3321 | /* In case tcp_shift_skb_data() have aggregated large skbs, |
3322 | * we need to make sure not sending too bigs TSO packets | |
3323 | */ | |
3324 | segs = min_t(int, segs, max_segs); | |
1da177e4 | 3325 | |
840a3cbe YC |
3326 | if (tp->retrans_out >= tp->lost_out) { |
3327 | break; | |
0e1c54c2 | 3328 | } else if (!(sacked & TCPCB_LOST)) { |
51456b29 | 3329 | if (!hole && !(sacked & (TCPCB_SACKED_RETRANS|TCPCB_SACKED_ACKED))) |
0e1c54c2 IJ |
3330 | hole = skb; |
3331 | continue; | |
1da177e4 | 3332 | |
0e1c54c2 IJ |
3333 | } else { |
3334 | if (icsk->icsk_ca_state != TCP_CA_Loss) | |
3335 | mib_idx = LINUX_MIB_TCPFASTRETRANS; | |
3336 | else | |
3337 | mib_idx = LINUX_MIB_TCPSLOWSTARTRETRANS; | |
3338 | } | |
1da177e4 | 3339 | |
0e1c54c2 | 3340 | if (sacked & (TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS)) |
1da177e4 LT |
3341 | continue; |
3342 | ||
f9616c35 | 3343 | if (tcp_small_queue_check(sk, skb, 1)) |
916e6d1a | 3344 | break; |
f9616c35 | 3345 | |
10d3be56 | 3346 | if (tcp_retransmit_skb(sk, skb, segs)) |
916e6d1a | 3347 | break; |
24ab6bec | 3348 | |
de1d6578 | 3349 | NET_ADD_STATS(sock_net(sk), mib_idx, tcp_skb_pcount(skb)); |
1da177e4 | 3350 | |
684bad11 | 3351 | if (tcp_in_cwnd_reduction(sk)) |
a262f0cd ND |
3352 | tp->prr_out += tcp_skb_pcount(skb); |
3353 | ||
75c119af | 3354 | if (skb == rtx_head && |
57dde7f7 | 3355 | icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT) |
916e6d1a ED |
3356 | rearm_timer = true; |
3357 | ||
1da177e4 | 3358 | } |
916e6d1a ED |
3359 | if (rearm_timer) |
3360 | tcp_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
3361 | inet_csk(sk)->icsk_rto, | |
3362 | TCP_RTO_MAX); | |
1da177e4 LT |
3363 | } |
3364 | ||
d83769a5 ED |
3365 | /* We allow to exceed memory limits for FIN packets to expedite |
3366 | * connection tear down and (memory) recovery. | |
845704a5 ED |
3367 | * Otherwise tcp_send_fin() could be tempted to either delay FIN |
3368 | * or even be forced to close flow without any FIN. | |
a6c5ea4c ED |
3369 | * In general, we want to allow one skb per socket to avoid hangs |
3370 | * with edge trigger epoll() | |
d83769a5 | 3371 | */ |
a6c5ea4c | 3372 | void sk_forced_mem_schedule(struct sock *sk, int size) |
d83769a5 | 3373 | { |
c4ee1185 | 3374 | int delta, amt; |
d83769a5 | 3375 | |
c4ee1185 ED |
3376 | delta = size - sk->sk_forward_alloc; |
3377 | if (delta <= 0) | |
d83769a5 | 3378 | return; |
c4ee1185 | 3379 | amt = sk_mem_pages(delta); |
100fdd1f | 3380 | sk->sk_forward_alloc += amt << PAGE_SHIFT; |
e805605c JW |
3381 | sk_memory_allocated_add(sk, amt); |
3382 | ||
baac50bb | 3383 | if (mem_cgroup_sockets_enabled && sk->sk_memcg) |
4b1327be WW |
3384 | mem_cgroup_charge_skmem(sk->sk_memcg, amt, |
3385 | gfp_memcg_charge() | __GFP_NOFAIL); | |
d83769a5 ED |
3386 | } |
3387 | ||
845704a5 ED |
3388 | /* Send a FIN. The caller locks the socket for us. |
3389 | * We should try to send a FIN packet really hard, but eventually give up. | |
1da177e4 LT |
3390 | */ |
3391 | void tcp_send_fin(struct sock *sk) | |
3392 | { | |
ee2aabd3 | 3393 | struct sk_buff *skb, *tskb, *tail = tcp_write_queue_tail(sk); |
e905a9ed | 3394 | struct tcp_sock *tp = tcp_sk(sk); |
e905a9ed | 3395 | |
845704a5 ED |
3396 | /* Optimization, tack on the FIN if we have one skb in write queue and |
3397 | * this skb was not yet sent, or we are under memory pressure. | |
3398 | * Note: in the latter case, FIN packet will be sent after a timeout, | |
3399 | * as TCP stack thinks it has already been transmitted. | |
1da177e4 | 3400 | */ |
ee2aabd3 | 3401 | tskb = tail; |
75c119af ED |
3402 | if (!tskb && tcp_under_memory_pressure(sk)) |
3403 | tskb = skb_rb_last(&sk->tcp_rtx_queue); | |
3404 | ||
3405 | if (tskb) { | |
845704a5 ED |
3406 | TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN; |
3407 | TCP_SKB_CB(tskb)->end_seq++; | |
1da177e4 | 3408 | tp->write_seq++; |
ee2aabd3 | 3409 | if (!tail) { |
845704a5 ED |
3410 | /* This means tskb was already sent. |
3411 | * Pretend we included the FIN on previous transmit. | |
3412 | * We need to set tp->snd_nxt to the value it would have | |
3413 | * if FIN had been sent. This is because retransmit path | |
3414 | * does not change tp->snd_nxt. | |
3415 | */ | |
e0d694d6 | 3416 | WRITE_ONCE(tp->snd_nxt, tp->snd_nxt + 1); |
845704a5 ED |
3417 | return; |
3418 | } | |
1da177e4 | 3419 | } else { |
845704a5 | 3420 | skb = alloc_skb_fclone(MAX_TCP_HEADER, sk->sk_allocation); |
d1edc085 | 3421 | if (unlikely(!skb)) |
845704a5 | 3422 | return; |
d1edc085 | 3423 | |
e2080072 | 3424 | INIT_LIST_HEAD(&skb->tcp_tsorted_anchor); |
d83769a5 | 3425 | skb_reserve(skb, MAX_TCP_HEADER); |
a6c5ea4c | 3426 | sk_forced_mem_schedule(sk, skb->truesize); |
1da177e4 | 3427 | /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */ |
e870a8ef | 3428 | tcp_init_nondata_skb(skb, tp->write_seq, |
a3433f35 | 3429 | TCPHDR_ACK | TCPHDR_FIN); |
1da177e4 LT |
3430 | tcp_queue_skb(sk, skb); |
3431 | } | |
845704a5 | 3432 | __tcp_push_pending_frames(sk, tcp_current_mss(sk), TCP_NAGLE_OFF); |
1da177e4 LT |
3433 | } |
3434 | ||
3435 | /* We get here when a process closes a file descriptor (either due to | |
3436 | * an explicit close() or as a byproduct of exit()'ing) and there | |
3437 | * was unread data in the receive queue. This behavior is recommended | |
65bb723c | 3438 | * by RFC 2525, section 2.17. -DaveM |
1da177e4 | 3439 | */ |
dd0fc66f | 3440 | void tcp_send_active_reset(struct sock *sk, gfp_t priority) |
1da177e4 | 3441 | { |
1da177e4 LT |
3442 | struct sk_buff *skb; |
3443 | ||
7cc2b043 GF |
3444 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTRSTS); |
3445 | ||
1da177e4 LT |
3446 | /* NOTE: No TCP options attached and we never retransmit this. */ |
3447 | skb = alloc_skb(MAX_TCP_HEADER, priority); | |
3448 | if (!skb) { | |
4e673444 | 3449 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
1da177e4 LT |
3450 | return; |
3451 | } | |
3452 | ||
3453 | /* Reserve space for headers and prepare control bits. */ | |
3454 | skb_reserve(skb, MAX_TCP_HEADER); | |
e870a8ef | 3455 | tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk), |
a3433f35 | 3456 | TCPHDR_ACK | TCPHDR_RST); |
9a568de4 | 3457 | tcp_mstamp_refresh(tcp_sk(sk)); |
1da177e4 | 3458 | /* Send it off. */ |
dfb4b9dc | 3459 | if (tcp_transmit_skb(sk, skb, 0, priority)) |
4e673444 | 3460 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED); |
c24b14c4 SL |
3461 | |
3462 | /* skb of trace_tcp_send_reset() keeps the skb that caused RST, | |
3463 | * skb here is different to the troublesome skb, so use NULL | |
3464 | */ | |
3465 | trace_tcp_send_reset(sk, NULL); | |
1da177e4 LT |
3466 | } |
3467 | ||
67edfef7 AK |
3468 | /* Send a crossed SYN-ACK during socket establishment. |
3469 | * WARNING: This routine must only be called when we have already sent | |
1da177e4 LT |
3470 | * a SYN packet that crossed the incoming SYN that caused this routine |
3471 | * to get called. If this assumption fails then the initial rcv_wnd | |
3472 | * and rcv_wscale values will not be correct. | |
3473 | */ | |
3474 | int tcp_send_synack(struct sock *sk) | |
3475 | { | |
056834d9 | 3476 | struct sk_buff *skb; |
1da177e4 | 3477 | |
75c119af | 3478 | skb = tcp_rtx_queue_head(sk); |
51456b29 | 3479 | if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { |
75c119af | 3480 | pr_err("%s: wrong queue state\n", __func__); |
1da177e4 LT |
3481 | return -EFAULT; |
3482 | } | |
4de075e0 | 3483 | if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) { |
1da177e4 | 3484 | if (skb_cloned(skb)) { |
e2080072 ED |
3485 | struct sk_buff *nskb; |
3486 | ||
3487 | tcp_skb_tsorted_save(skb) { | |
3488 | nskb = skb_copy(skb, GFP_ATOMIC); | |
3489 | } tcp_skb_tsorted_restore(skb); | |
51456b29 | 3490 | if (!nskb) |
1da177e4 | 3491 | return -ENOMEM; |
e2080072 | 3492 | INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor); |
2bec445f | 3493 | tcp_highest_sack_replace(sk, skb, nskb); |
75c119af | 3494 | tcp_rtx_queue_unlink_and_free(skb, sk); |
f4a775d1 | 3495 | __skb_header_release(nskb); |
75c119af | 3496 | tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb); |
ab4e846a | 3497 | sk_wmem_queued_add(sk, nskb->truesize); |
3ab224be | 3498 | sk_mem_charge(sk, nskb->truesize); |
1da177e4 LT |
3499 | skb = nskb; |
3500 | } | |
3501 | ||
4de075e0 | 3502 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK; |
735d3831 | 3503 | tcp_ecn_send_synack(sk, skb); |
1da177e4 | 3504 | } |
dfb4b9dc | 3505 | return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
1da177e4 LT |
3506 | } |
3507 | ||
4aea39c1 | 3508 | /** |
331fca43 MKL |
3509 | * tcp_make_synack - Allocate one skb and build a SYNACK packet. |
3510 | * @sk: listener socket | |
3511 | * @dst: dst entry attached to the SYNACK. It is consumed and caller | |
3512 | * should not use it again. | |
3513 | * @req: request_sock pointer | |
3514 | * @foc: cookie for tcp fast open | |
3515 | * @synack_type: Type of synack to prepare | |
3516 | * @syn_skb: SYN packet just received. It could be NULL for rtx case. | |
4aea39c1 | 3517 | */ |
5d062de7 | 3518 | struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, |
e6b4d113 | 3519 | struct request_sock *req, |
ca6fb065 | 3520 | struct tcp_fastopen_cookie *foc, |
331fca43 MKL |
3521 | enum tcp_synack_type synack_type, |
3522 | struct sk_buff *syn_skb) | |
1da177e4 | 3523 | { |
2e6599cb | 3524 | struct inet_request_sock *ireq = inet_rsk(req); |
5d062de7 | 3525 | const struct tcp_sock *tp = tcp_sk(sk); |
80f03e27 | 3526 | struct tcp_md5sig_key *md5 = NULL; |
5d062de7 ED |
3527 | struct tcp_out_options opts; |
3528 | struct sk_buff *skb; | |
bd0388ae | 3529 | int tcp_header_size; |
5d062de7 | 3530 | struct tcphdr *th; |
f5fff5dc | 3531 | int mss; |
a842fe14 | 3532 | u64 now; |
1da177e4 | 3533 | |
ca6fb065 | 3534 | skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC); |
4aea39c1 ED |
3535 | if (unlikely(!skb)) { |
3536 | dst_release(dst); | |
1da177e4 | 3537 | return NULL; |
4aea39c1 | 3538 | } |
1da177e4 LT |
3539 | /* Reserve space for headers. */ |
3540 | skb_reserve(skb, MAX_TCP_HEADER); | |
3541 | ||
b3d05147 ED |
3542 | switch (synack_type) { |
3543 | case TCP_SYNACK_NORMAL: | |
9e17f8a4 | 3544 | skb_set_owner_w(skb, req_to_sk(req)); |
b3d05147 ED |
3545 | break; |
3546 | case TCP_SYNACK_COOKIE: | |
3547 | /* Under synflood, we do not attach skb to a socket, | |
3548 | * to avoid false sharing. | |
3549 | */ | |
3550 | break; | |
3551 | case TCP_SYNACK_FASTOPEN: | |
ca6fb065 ED |
3552 | /* sk is a const pointer, because we want to express multiple |
3553 | * cpu might call us concurrently. | |
3554 | * sk->sk_wmem_alloc in an atomic, we can promote to rw. | |
3555 | */ | |
3556 | skb_set_owner_w(skb, (struct sock *)sk); | |
b3d05147 | 3557 | break; |
ca6fb065 | 3558 | } |
4aea39c1 | 3559 | skb_dst_set(skb, dst); |
1da177e4 | 3560 | |
3541f9e8 | 3561 | mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
f5fff5dc | 3562 | |
33ad798c | 3563 | memset(&opts, 0, sizeof(opts)); |
a842fe14 | 3564 | now = tcp_clock_ns(); |
8b5f12d0 | 3565 | #ifdef CONFIG_SYN_COOKIES |
f8ace8d9 | 3566 | if (unlikely(synack_type == TCP_SYNACK_COOKIE && ireq->tstamp_ok)) |
a1ac9c8a MKL |
3567 | skb_set_delivery_time(skb, cookie_init_timestamp(req, now), |
3568 | true); | |
8b5f12d0 FW |
3569 | else |
3570 | #endif | |
9e450c1e | 3571 | { |
a1ac9c8a | 3572 | skb_set_delivery_time(skb, now, true); |
9e450c1e YC |
3573 | if (!tcp_rsk(req)->snt_synack) /* Timestamp first SYNACK */ |
3574 | tcp_rsk(req)->snt_synack = tcp_skb_timestamp_us(skb); | |
3575 | } | |
80f03e27 ED |
3576 | |
3577 | #ifdef CONFIG_TCP_MD5SIG | |
3578 | rcu_read_lock(); | |
fd3a154a | 3579 | md5 = tcp_rsk(req)->af_specific->req_md5_lookup(sk, req_to_sk(req)); |
80f03e27 | 3580 | #endif |
58d607d3 | 3581 | skb_set_hash(skb, tcp_rsk(req)->txhash, PKT_HASH_TYPE_L4); |
331fca43 MKL |
3582 | /* bpf program will be interested in the tcp_flags */ |
3583 | TCP_SKB_CB(skb)->tcp_flags = TCPHDR_SYN | TCPHDR_ACK; | |
60e2a778 | 3584 | tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, md5, |
331fca43 MKL |
3585 | foc, synack_type, |
3586 | syn_skb) + sizeof(*th); | |
cfb6eeb4 | 3587 | |
aa8223c7 ACM |
3588 | skb_push(skb, tcp_header_size); |
3589 | skb_reset_transport_header(skb); | |
1da177e4 | 3590 | |
ea1627c2 | 3591 | th = (struct tcphdr *)skb->data; |
1da177e4 LT |
3592 | memset(th, 0, sizeof(struct tcphdr)); |
3593 | th->syn = 1; | |
3594 | th->ack = 1; | |
6ac705b1 | 3595 | tcp_ecn_make_synack(req, th); |
b44084c2 | 3596 | th->source = htons(ireq->ir_num); |
634fb979 | 3597 | th->dest = ireq->ir_rmt_port; |
e05a90ec | 3598 | skb->mark = ireq->ir_mark; |
3b117750 ED |
3599 | skb->ip_summed = CHECKSUM_PARTIAL; |
3600 | th->seq = htonl(tcp_rsk(req)->snt_isn); | |
8336886f JC |
3601 | /* XXX data is queued and acked as is. No buffer/window check */ |
3602 | th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt); | |
1da177e4 LT |
3603 | |
3604 | /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */ | |
ed53d0ab | 3605 | th->window = htons(min(req->rsk_rcv_wnd, 65535U)); |
ea66758c | 3606 | tcp_options_write(th, NULL, &opts); |
1da177e4 | 3607 | th->doff = (tcp_header_size >> 2); |
bced3f7d | 3608 | TCP_INC_STATS(sock_net(sk), TCP_MIB_OUTSEGS); |
cfb6eeb4 YH |
3609 | |
3610 | #ifdef CONFIG_TCP_MD5SIG | |
3611 | /* Okay, we have all we need - do the md5 hash if needed */ | |
80f03e27 | 3612 | if (md5) |
bd0388ae | 3613 | tcp_rsk(req)->af_specific->calc_md5_hash(opts.hash_location, |
39f8e58e | 3614 | md5, req_to_sk(req), skb); |
80f03e27 | 3615 | rcu_read_unlock(); |
cfb6eeb4 YH |
3616 | #endif |
3617 | ||
331fca43 MKL |
3618 | bpf_skops_write_hdr_opt((struct sock *)sk, skb, req, syn_skb, |
3619 | synack_type, &opts); | |
3620 | ||
a1ac9c8a | 3621 | skb_set_delivery_time(skb, now, true); |
a842fe14 ED |
3622 | tcp_add_tx_delay(skb, tp); |
3623 | ||
1da177e4 LT |
3624 | return skb; |
3625 | } | |
4bc2f18b | 3626 | EXPORT_SYMBOL(tcp_make_synack); |
1da177e4 | 3627 | |
81164413 DB |
3628 | static void tcp_ca_dst_init(struct sock *sk, const struct dst_entry *dst) |
3629 | { | |
3630 | struct inet_connection_sock *icsk = inet_csk(sk); | |
3631 | const struct tcp_congestion_ops *ca; | |
3632 | u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); | |
3633 | ||
3634 | if (ca_key == TCP_CA_UNSPEC) | |
3635 | return; | |
3636 | ||
3637 | rcu_read_lock(); | |
3638 | ca = tcp_ca_find_key(ca_key); | |
0baf26b0 MKL |
3639 | if (likely(ca && bpf_try_module_get(ca, ca->owner))) { |
3640 | bpf_module_put(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner); | |
81164413 DB |
3641 | icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); |
3642 | icsk->icsk_ca_ops = ca; | |
3643 | } | |
3644 | rcu_read_unlock(); | |
3645 | } | |
3646 | ||
67edfef7 | 3647 | /* Do all connect socket setups that can be done AF independent. */ |
f7e56a76 | 3648 | static void tcp_connect_init(struct sock *sk) |
1da177e4 | 3649 | { |
cf533ea5 | 3650 | const struct dst_entry *dst = __sk_dst_get(sk); |
1da177e4 LT |
3651 | struct tcp_sock *tp = tcp_sk(sk); |
3652 | __u8 rcv_wscale; | |
13d3b1eb | 3653 | u32 rcv_wnd; |
1da177e4 LT |
3654 | |
3655 | /* We'll fix this up when we get a response from the other end. | |
3656 | * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT. | |
3657 | */ | |
5d2ed052 | 3658 | tp->tcp_header_len = sizeof(struct tcphdr); |
3666f666 | 3659 | if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps)) |
5d2ed052 | 3660 | tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED; |
1da177e4 | 3661 | |
cfb6eeb4 | 3662 | #ifdef CONFIG_TCP_MD5SIG |
00db4124 | 3663 | if (tp->af_specific->md5_lookup(sk, sk)) |
cfb6eeb4 YH |
3664 | tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; |
3665 | #endif | |
3666 | ||
1da177e4 LT |
3667 | /* If user gave his TCP_MAXSEG, record it to clamp */ |
3668 | if (tp->rx_opt.user_mss) | |
3669 | tp->rx_opt.mss_clamp = tp->rx_opt.user_mss; | |
3670 | tp->max_window = 0; | |
5d424d5a | 3671 | tcp_mtup_init(sk); |
1da177e4 LT |
3672 | tcp_sync_mss(sk, dst_mtu(dst)); |
3673 | ||
81164413 DB |
3674 | tcp_ca_dst_init(sk, dst); |
3675 | ||
1da177e4 LT |
3676 | if (!tp->window_clamp) |
3677 | tp->window_clamp = dst_metric(dst, RTAX_WINDOW); | |
3541f9e8 | 3678 | tp->advmss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
f5fff5dc | 3679 | |
1da177e4 | 3680 | tcp_initialize_rcv_mss(sk); |
1da177e4 | 3681 | |
e88c64f0 HPP |
3682 | /* limit the window selection if the user enforce a smaller rx buffer */ |
3683 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
3684 | (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0)) | |
3685 | tp->window_clamp = tcp_full_space(sk); | |
3686 | ||
13d3b1eb LB |
3687 | rcv_wnd = tcp_rwnd_init_bpf(sk); |
3688 | if (rcv_wnd == 0) | |
3689 | rcv_wnd = dst_metric(dst, RTAX_INITRWND); | |
3690 | ||
ceef9ab6 | 3691 | tcp_select_initial_window(sk, tcp_full_space(sk), |
1da177e4 LT |
3692 | tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0), |
3693 | &tp->rcv_wnd, | |
3694 | &tp->window_clamp, | |
3666f666 | 3695 | READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling), |
31d12926 | 3696 | &rcv_wscale, |
13d3b1eb | 3697 | rcv_wnd); |
1da177e4 LT |
3698 | |
3699 | tp->rx_opt.rcv_wscale = rcv_wscale; | |
3700 | tp->rcv_ssthresh = tp->rcv_wnd; | |
3701 | ||
e13ec3da | 3702 | WRITE_ONCE(sk->sk_err, 0); |
1da177e4 LT |
3703 | sock_reset_flag(sk, SOCK_DONE); |
3704 | tp->snd_wnd = 0; | |
ee7537b6 | 3705 | tcp_init_wl(tp, 0); |
7f582b24 | 3706 | tcp_write_queue_purge(sk); |
1da177e4 LT |
3707 | tp->snd_una = tp->write_seq; |
3708 | tp->snd_sml = tp->write_seq; | |
33f5f57e | 3709 | tp->snd_up = tp->write_seq; |
e0d694d6 | 3710 | WRITE_ONCE(tp->snd_nxt, tp->write_seq); |
ee995283 PE |
3711 | |
3712 | if (likely(!tp->repair)) | |
3713 | tp->rcv_nxt = 0; | |
c7781a6e | 3714 | else |
70eabf0e | 3715 | tp->rcv_tstamp = tcp_jiffies32; |
ee995283 | 3716 | tp->rcv_wup = tp->rcv_nxt; |
7db48e98 | 3717 | WRITE_ONCE(tp->copied_seq, tp->rcv_nxt); |
1da177e4 | 3718 | |
8550f328 | 3719 | inet_csk(sk)->icsk_rto = tcp_timeout_init(sk); |
463c84b9 | 3720 | inet_csk(sk)->icsk_retransmits = 0; |
1da177e4 LT |
3721 | tcp_clear_retrans(tp); |
3722 | } | |
3723 | ||
783237e8 YC |
3724 | static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb) |
3725 | { | |
3726 | struct tcp_sock *tp = tcp_sk(sk); | |
3727 | struct tcp_skb_cb *tcb = TCP_SKB_CB(skb); | |
3728 | ||
3729 | tcb->end_seq += skb->len; | |
f4a775d1 | 3730 | __skb_header_release(skb); |
ab4e846a | 3731 | sk_wmem_queued_add(sk, skb->truesize); |
783237e8 | 3732 | sk_mem_charge(sk, skb->truesize); |
0f317464 | 3733 | WRITE_ONCE(tp->write_seq, tcb->end_seq); |
783237e8 YC |
3734 | tp->packets_out += tcp_skb_pcount(skb); |
3735 | } | |
3736 | ||
3737 | /* Build and send a SYN with data and (cached) Fast Open cookie. However, | |
3738 | * queue a data-only packet after the regular SYN, such that regular SYNs | |
3739 | * are retransmitted on timeouts. Also if the remote SYN-ACK acknowledges | |
3740 | * only the SYN sequence, the data are retransmitted in the first ACK. | |
3741 | * If cookie is not cached or other error occurs, falls back to send a | |
3742 | * regular SYN with Fast Open cookie request option. | |
3743 | */ | |
3744 | static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) | |
3745 | { | |
ed0c99dc | 3746 | struct inet_connection_sock *icsk = inet_csk(sk); |
783237e8 YC |
3747 | struct tcp_sock *tp = tcp_sk(sk); |
3748 | struct tcp_fastopen_request *fo = tp->fastopen_req; | |
065263f4 | 3749 | int space, err = 0; |
355a901e | 3750 | struct sk_buff *syn_data; |
aab48743 | 3751 | |
67da22d2 | 3752 | tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */ |
065263f4 | 3753 | if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie)) |
783237e8 YC |
3754 | goto fallback; |
3755 | ||
3756 | /* MSS for SYN-data is based on cached MSS and bounded by PMTU and | |
3757 | * user-MSS. Reserve maximum option space for middleboxes that add | |
3758 | * private TCP options. The cost is reduced data space in SYN :( | |
3759 | */ | |
3541f9e8 | 3760 | tp->rx_opt.mss_clamp = tcp_mss_clamp(tp, tp->rx_opt.mss_clamp); |
ed0c99dc JK |
3761 | /* Sync mss_cache after updating the mss_clamp */ |
3762 | tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); | |
3541f9e8 | 3763 | |
ed0c99dc | 3764 | space = __tcp_mtu_to_mss(sk, icsk->icsk_pmtu_cookie) - |
783237e8 YC |
3765 | MAX_TCP_OPTION_SPACE; |
3766 | ||
f5ddcbbb ED |
3767 | space = min_t(size_t, space, fo->size); |
3768 | ||
3769 | /* limit to order-0 allocations */ | |
3770 | space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER)); | |
3771 | ||
f8dd3b8d | 3772 | syn_data = tcp_stream_alloc_skb(sk, space, sk->sk_allocation, false); |
355a901e | 3773 | if (!syn_data) |
783237e8 | 3774 | goto fallback; |
355a901e | 3775 | memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); |
07e100f9 ED |
3776 | if (space) { |
3777 | int copied = copy_from_iter(skb_put(syn_data, space), space, | |
3778 | &fo->data->msg_iter); | |
3779 | if (unlikely(!copied)) { | |
ba233b34 | 3780 | tcp_skb_tsorted_anchor_cleanup(syn_data); |
07e100f9 ED |
3781 | kfree_skb(syn_data); |
3782 | goto fallback; | |
3783 | } | |
3784 | if (copied != space) { | |
3785 | skb_trim(syn_data, copied); | |
3786 | space = copied; | |
3787 | } | |
f859a448 | 3788 | skb_zcopy_set(syn_data, fo->uarg, NULL); |
57be5bda | 3789 | } |
355a901e ED |
3790 | /* No more data pending in inet_wait_for_connect() */ |
3791 | if (space == fo->size) | |
3792 | fo->data = NULL; | |
3793 | fo->copied = space; | |
783237e8 | 3794 | |
355a901e | 3795 | tcp_connect_queue_skb(sk, syn_data); |
0f87230d FY |
3796 | if (syn_data->len) |
3797 | tcp_chrono_start(sk, TCP_CHRONO_BUSY); | |
783237e8 | 3798 | |
355a901e | 3799 | err = tcp_transmit_skb(sk, syn_data, 1, sk->sk_allocation); |
783237e8 | 3800 | |
a1ac9c8a | 3801 | skb_set_delivery_time(syn, syn_data->skb_mstamp_ns, true); |
431a9124 | 3802 | |
355a901e ED |
3803 | /* Now full SYN+DATA was cloned and sent (or not), |
3804 | * remove the SYN from the original skb (syn_data) | |
3805 | * we keep in write queue in case of a retransmit, as we | |
3806 | * also have the SYN packet (with no data) in the same queue. | |
3807 | */ | |
3808 | TCP_SKB_CB(syn_data)->seq++; | |
3809 | TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH; | |
3810 | if (!err) { | |
67da22d2 | 3811 | tp->syn_data = (fo->copied > 0); |
75c119af | 3812 | tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data); |
f19c29e3 | 3813 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT); |
783237e8 YC |
3814 | goto done; |
3815 | } | |
783237e8 | 3816 | |
75c119af ED |
3817 | /* data was not sent, put it in write_queue */ |
3818 | __skb_queue_tail(&sk->sk_write_queue, syn_data); | |
b5b7db8d ED |
3819 | tp->packets_out -= tcp_skb_pcount(syn_data); |
3820 | ||
783237e8 YC |
3821 | fallback: |
3822 | /* Send a regular SYN with Fast Open cookie request option */ | |
3823 | if (fo->cookie.len > 0) | |
3824 | fo->cookie.len = 0; | |
3825 | err = tcp_transmit_skb(sk, syn, 1, sk->sk_allocation); | |
3826 | if (err) | |
3827 | tp->syn_fastopen = 0; | |
783237e8 YC |
3828 | done: |
3829 | fo->cookie.len = -1; /* Exclude Fast Open option for SYN retries */ | |
3830 | return err; | |
3831 | } | |
3832 | ||
67edfef7 | 3833 | /* Build a SYN and send it off. */ |
1da177e4 LT |
3834 | int tcp_connect(struct sock *sk) |
3835 | { | |
3836 | struct tcp_sock *tp = tcp_sk(sk); | |
3837 | struct sk_buff *buff; | |
ee586811 | 3838 | int err; |
1da177e4 | 3839 | |
de525be2 | 3840 | tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_CONNECT_CB, 0, NULL); |
8ba60924 ED |
3841 | |
3842 | if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk)) | |
3843 | return -EHOSTUNREACH; /* Routing failure or similar. */ | |
3844 | ||
1da177e4 LT |
3845 | tcp_connect_init(sk); |
3846 | ||
2b916477 AV |
3847 | if (unlikely(tp->repair)) { |
3848 | tcp_finish_connect(sk, NULL); | |
3849 | return 0; | |
3850 | } | |
3851 | ||
f8dd3b8d | 3852 | buff = tcp_stream_alloc_skb(sk, 0, sk->sk_allocation, true); |
355a901e | 3853 | if (unlikely(!buff)) |
1da177e4 LT |
3854 | return -ENOBUFS; |
3855 | ||
a3433f35 | 3856 | tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN); |
9a568de4 ED |
3857 | tcp_mstamp_refresh(tp); |
3858 | tp->retrans_stamp = tcp_time_stamp(tp); | |
783237e8 | 3859 | tcp_connect_queue_skb(sk, buff); |
735d3831 | 3860 | tcp_ecn_send_syn(sk, buff); |
75c119af | 3861 | tcp_rbtree_insert(&sk->tcp_rtx_queue, buff); |
1da177e4 | 3862 | |
783237e8 YC |
3863 | /* Send off SYN; include data in Fast Open. */ |
3864 | err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) : | |
3865 | tcp_transmit_skb(sk, buff, 1, sk->sk_allocation); | |
ee586811 EP |
3866 | if (err == -ECONNREFUSED) |
3867 | return err; | |
bd37a088 WY |
3868 | |
3869 | /* We change tp->snd_nxt after the tcp_transmit_skb() call | |
3870 | * in order to make this packet get counted in tcpOutSegs. | |
3871 | */ | |
e0d694d6 | 3872 | WRITE_ONCE(tp->snd_nxt, tp->write_seq); |
bd37a088 | 3873 | tp->pushed_seq = tp->write_seq; |
b5b7db8d ED |
3874 | buff = tcp_send_head(sk); |
3875 | if (unlikely(buff)) { | |
e0d694d6 | 3876 | WRITE_ONCE(tp->snd_nxt, TCP_SKB_CB(buff)->seq); |
b5b7db8d ED |
3877 | tp->pushed_seq = TCP_SKB_CB(buff)->seq; |
3878 | } | |
81cc8a75 | 3879 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ACTIVEOPENS); |
1da177e4 LT |
3880 | |
3881 | /* Timer for repeating the SYN until an answer. */ | |
3f421baa ACM |
3882 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, |
3883 | inet_csk(sk)->icsk_rto, TCP_RTO_MAX); | |
1da177e4 LT |
3884 | return 0; |
3885 | } | |
4bc2f18b | 3886 | EXPORT_SYMBOL(tcp_connect); |
1da177e4 LT |
3887 | |
3888 | /* Send out a delayed ack, the caller does the policy checking | |
3889 | * to see if we should even be here. See tcp_input.c:tcp_ack_snd_check() | |
3890 | * for details. | |
3891 | */ | |
3892 | void tcp_send_delayed_ack(struct sock *sk) | |
3893 | { | |
463c84b9 ACM |
3894 | struct inet_connection_sock *icsk = inet_csk(sk); |
3895 | int ato = icsk->icsk_ack.ato; | |
1da177e4 LT |
3896 | unsigned long timeout; |
3897 | ||
3898 | if (ato > TCP_DELACK_MIN) { | |
463c84b9 | 3899 | const struct tcp_sock *tp = tcp_sk(sk); |
056834d9 | 3900 | int max_ato = HZ / 2; |
1da177e4 | 3901 | |
31954cd8 | 3902 | if (inet_csk_in_pingpong_mode(sk) || |
056834d9 | 3903 | (icsk->icsk_ack.pending & ICSK_ACK_PUSHED)) |
1da177e4 LT |
3904 | max_ato = TCP_DELACK_MAX; |
3905 | ||
3906 | /* Slow path, intersegment interval is "high". */ | |
3907 | ||
3908 | /* If some rtt estimate is known, use it to bound delayed ack. | |
463c84b9 | 3909 | * Do not use inet_csk(sk)->icsk_rto here, use results of rtt measurements |
1da177e4 LT |
3910 | * directly. |
3911 | */ | |
740b0f18 ED |
3912 | if (tp->srtt_us) { |
3913 | int rtt = max_t(int, usecs_to_jiffies(tp->srtt_us >> 3), | |
3914 | TCP_DELACK_MIN); | |
1da177e4 LT |
3915 | |
3916 | if (rtt < max_ato) | |
3917 | max_ato = rtt; | |
3918 | } | |
3919 | ||
3920 | ato = min(ato, max_ato); | |
3921 | } | |
3922 | ||
2b8ee4f0 MKL |
3923 | ato = min_t(u32, ato, inet_csk(sk)->icsk_delack_max); |
3924 | ||
1da177e4 LT |
3925 | /* Stay within the limit we were given */ |
3926 | timeout = jiffies + ato; | |
3927 | ||
3928 | /* Use new timeout only if there wasn't a older one earlier. */ | |
463c84b9 | 3929 | if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { |
b6b6d653 ED |
3930 | /* If delack timer is about to expire, send ACK now. */ |
3931 | if (time_before_eq(icsk->icsk_ack.timeout, jiffies + (ato >> 2))) { | |
1da177e4 LT |
3932 | tcp_send_ack(sk); |
3933 | return; | |
3934 | } | |
3935 | ||
463c84b9 ACM |
3936 | if (!time_before(timeout, icsk->icsk_ack.timeout)) |
3937 | timeout = icsk->icsk_ack.timeout; | |
1da177e4 | 3938 | } |
463c84b9 ACM |
3939 | icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; |
3940 | icsk->icsk_ack.timeout = timeout; | |
3941 | sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); | |
1da177e4 LT |
3942 | } |
3943 | ||
3944 | /* This routine sends an ack and also updates the window. */ | |
2987babb | 3945 | void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) |
1da177e4 | 3946 | { |
058dc334 | 3947 | struct sk_buff *buff; |
1da177e4 | 3948 | |
058dc334 IJ |
3949 | /* If we have been reset, we may not send again. */ |
3950 | if (sk->sk_state == TCP_CLOSE) | |
3951 | return; | |
1da177e4 | 3952 | |
058dc334 IJ |
3953 | /* We are not putting this on the write queue, so |
3954 | * tcp_transmit_skb() will set the ownership to this | |
3955 | * sock. | |
3956 | */ | |
7450aaf6 ED |
3957 | buff = alloc_skb(MAX_TCP_HEADER, |
3958 | sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); | |
3959 | if (unlikely(!buff)) { | |
a37c2134 ED |
3960 | struct inet_connection_sock *icsk = inet_csk(sk); |
3961 | unsigned long delay; | |
3962 | ||
3963 | delay = TCP_DELACK_MAX << icsk->icsk_ack.retry; | |
3964 | if (delay < TCP_RTO_MAX) | |
3965 | icsk->icsk_ack.retry++; | |
058dc334 | 3966 | inet_csk_schedule_ack(sk); |
a37c2134 ED |
3967 | icsk->icsk_ack.ato = TCP_ATO_MIN; |
3968 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, delay, TCP_RTO_MAX); | |
058dc334 | 3969 | return; |
1da177e4 | 3970 | } |
058dc334 IJ |
3971 | |
3972 | /* Reserve space for headers and prepare control bits. */ | |
3973 | skb_reserve(buff, MAX_TCP_HEADER); | |
a3433f35 | 3974 | tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); |
058dc334 | 3975 | |
98781965 ED |
3976 | /* We do not want pure acks influencing TCP Small Queues or fq/pacing |
3977 | * too much. | |
3978 | * SKB_TRUESIZE(max(1 .. 66, MAX_TCP_HEADER)) is unfortunately ~784 | |
98781965 ED |
3979 | */ |
3980 | skb_set_tcp_pure_ack(buff); | |
3981 | ||
058dc334 | 3982 | /* Send it off, this clears delayed acks for us. */ |
2987babb YC |
3983 | __tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0, rcv_nxt); |
3984 | } | |
27cde44a | 3985 | EXPORT_SYMBOL_GPL(__tcp_send_ack); |
2987babb YC |
3986 | |
3987 | void tcp_send_ack(struct sock *sk) | |
3988 | { | |
3989 | __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); | |
1da177e4 LT |
3990 | } |
3991 | ||
3992 | /* This routine sends a packet with an out of date sequence | |
3993 | * number. It assumes the other end will try to ack it. | |
3994 | * | |
3995 | * Question: what should we make while urgent mode? | |
3996 | * 4.4BSD forces sending single byte of data. We cannot send | |
3997 | * out of window data, because we have SND.NXT==SND.MAX... | |
3998 | * | |
3999 | * Current solution: to send TWO zero-length segments in urgent mode: | |
4000 | * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is | |
4001 | * out-of-date with SND.UNA-1 to probe window. | |
4002 | */ | |
e520af48 | 4003 | static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib) |
1da177e4 LT |
4004 | { |
4005 | struct tcp_sock *tp = tcp_sk(sk); | |
4006 | struct sk_buff *skb; | |
4007 | ||
4008 | /* We don't queue it, tcp_transmit_skb() sets ownership. */ | |
7450aaf6 ED |
4009 | skb = alloc_skb(MAX_TCP_HEADER, |
4010 | sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN)); | |
51456b29 | 4011 | if (!skb) |
1da177e4 LT |
4012 | return -1; |
4013 | ||
4014 | /* Reserve space for headers and set control bits. */ | |
4015 | skb_reserve(skb, MAX_TCP_HEADER); | |
1da177e4 LT |
4016 | /* Use a previous sequence. This should cause the other |
4017 | * end to send an ack. Don't queue or clone SKB, just | |
4018 | * send it. | |
4019 | */ | |
a3433f35 | 4020 | tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK); |
e2e8009f | 4021 | NET_INC_STATS(sock_net(sk), mib); |
7450aaf6 | 4022 | return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0); |
1da177e4 LT |
4023 | } |
4024 | ||
385e2070 | 4025 | /* Called from setsockopt( ... TCP_REPAIR ) */ |
ee995283 PE |
4026 | void tcp_send_window_probe(struct sock *sk) |
4027 | { | |
4028 | if (sk->sk_state == TCP_ESTABLISHED) { | |
4029 | tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1; | |
9a568de4 | 4030 | tcp_mstamp_refresh(tcp_sk(sk)); |
e520af48 | 4031 | tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE); |
ee995283 PE |
4032 | } |
4033 | } | |
4034 | ||
67edfef7 | 4035 | /* Initiate keepalive or window probe from timer. */ |
e520af48 | 4036 | int tcp_write_wakeup(struct sock *sk, int mib) |
1da177e4 | 4037 | { |
058dc334 IJ |
4038 | struct tcp_sock *tp = tcp_sk(sk); |
4039 | struct sk_buff *skb; | |
1da177e4 | 4040 | |
058dc334 IJ |
4041 | if (sk->sk_state == TCP_CLOSE) |
4042 | return -1; | |
4043 | ||
00db4124 IM |
4044 | skb = tcp_send_head(sk); |
4045 | if (skb && before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(tp))) { | |
058dc334 | 4046 | int err; |
0c54b85f | 4047 | unsigned int mss = tcp_current_mss(sk); |
058dc334 IJ |
4048 | unsigned int seg_size = tcp_wnd_end(tp) - TCP_SKB_CB(skb)->seq; |
4049 | ||
4050 | if (before(tp->pushed_seq, TCP_SKB_CB(skb)->end_seq)) | |
4051 | tp->pushed_seq = TCP_SKB_CB(skb)->end_seq; | |
4052 | ||
4053 | /* We are probing the opening of a window | |
4054 | * but the window size is != 0 | |
4055 | * must have been a result SWS avoidance ( sender ) | |
4056 | */ | |
4057 | if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq || | |
4058 | skb->len > mss) { | |
4059 | seg_size = min(seg_size, mss); | |
4de075e0 | 4060 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
75c119af ED |
4061 | if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE, |
4062 | skb, seg_size, mss, GFP_ATOMIC)) | |
058dc334 IJ |
4063 | return -1; |
4064 | } else if (!tcp_skb_pcount(skb)) | |
5bbb432c | 4065 | tcp_set_skb_tso_segs(skb, mss); |
058dc334 | 4066 | |
4de075e0 | 4067 | TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH; |
058dc334 IJ |
4068 | err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC); |
4069 | if (!err) | |
4070 | tcp_event_new_data_sent(sk, skb); | |
4071 | return err; | |
4072 | } else { | |
33f5f57e | 4073 | if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF)) |
e520af48 ED |
4074 | tcp_xmit_probe_skb(sk, 1, mib); |
4075 | return tcp_xmit_probe_skb(sk, 0, mib); | |
1da177e4 | 4076 | } |
1da177e4 LT |
4077 | } |
4078 | ||
4079 | /* A window probe timeout has occurred. If window is not closed send | |
4080 | * a partial packet else a zero probe. | |
4081 | */ | |
4082 | void tcp_send_probe0(struct sock *sk) | |
4083 | { | |
463c84b9 | 4084 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 4085 | struct tcp_sock *tp = tcp_sk(sk); |
c6214a97 | 4086 | struct net *net = sock_net(sk); |
c1d5674f | 4087 | unsigned long timeout; |
1da177e4 LT |
4088 | int err; |
4089 | ||
e520af48 | 4090 | err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE); |
1da177e4 | 4091 | |
75c119af | 4092 | if (tp->packets_out || tcp_write_queue_empty(sk)) { |
1da177e4 | 4093 | /* Cancel probe timer, if it is not required. */ |
6687e988 | 4094 | icsk->icsk_probes_out = 0; |
463c84b9 | 4095 | icsk->icsk_backoff = 0; |
9d9b1ee0 | 4096 | icsk->icsk_probes_tstamp = 0; |
1da177e4 LT |
4097 | return; |
4098 | } | |
4099 | ||
c1d5674f | 4100 | icsk->icsk_probes_out++; |
1da177e4 | 4101 | if (err <= 0) { |
39e24435 | 4102 | if (icsk->icsk_backoff < READ_ONCE(net->ipv4.sysctl_tcp_retries2)) |
463c84b9 | 4103 | icsk->icsk_backoff++; |
c1d5674f | 4104 | timeout = tcp_probe0_when(sk, TCP_RTO_MAX); |
1da177e4 LT |
4105 | } else { |
4106 | /* If packet was not sent due to local congestion, | |
c1d5674f | 4107 | * Let senders fight for local resources conservatively. |
1da177e4 | 4108 | */ |
c1d5674f YC |
4109 | timeout = TCP_RESOURCE_PROBE_INTERVAL; |
4110 | } | |
344db93a EC |
4111 | |
4112 | timeout = tcp_clamp_probe0_to_user_timeout(sk, timeout); | |
8dc242ad | 4113 | tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, timeout, TCP_RTO_MAX); |
1da177e4 | 4114 | } |
5db92c99 | 4115 | |
ea3bea3a | 4116 | int tcp_rtx_synack(const struct sock *sk, struct request_sock *req) |
5db92c99 OP |
4117 | { |
4118 | const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific; | |
4119 | struct flowi fl; | |
4120 | int res; | |
4121 | ||
cb6cd2ce AK |
4122 | /* Paired with WRITE_ONCE() in sock_setsockopt() */ |
4123 | if (READ_ONCE(sk->sk_txrehash) == SOCK_TXREHASH_ENABLED) | |
4124 | tcp_rsk(req)->txhash = net_tx_rndhash(); | |
331fca43 MKL |
4125 | res = af_ops->send_synack(sk, NULL, &fl, req, NULL, TCP_SYNACK_NORMAL, |
4126 | NULL); | |
5db92c99 | 4127 | if (!res) { |
0a375c82 ED |
4128 | TCP_INC_STATS(sock_net(sk), TCP_MIB_RETRANSSEGS); |
4129 | NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNRETRANS); | |
e9d9da91 ED |
4130 | if (unlikely(tcp_passive_fastopen(sk))) { |
4131 | /* sk has const attribute because listeners are lockless. | |
4132 | * However in this case, we are dealing with a passive fastopen | |
4133 | * socket thus we can change total_retrans value. | |
4134 | */ | |
4135 | tcp_sk_rw(sk)->total_retrans++; | |
4136 | } | |
cf34ce3d | 4137 | trace_tcp_retransmit_synack(sk, req); |
5db92c99 OP |
4138 | } |
4139 | return res; | |
4140 | } | |
4141 | EXPORT_SYMBOL(tcp_rtx_synack); |