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Merge tag 'mm-hotfixes-stable-2025-07-11-16-16' of git://git.kernel.org/pub/scm/linux...
[linux-block.git] / net / ipv4 / ip_output.c
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1// SPDX-License-Identifier: GPL-2.0-only
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 * The Internet Protocol (IP) output module.
8 *
9 * Authors: Ross Biro
10 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
11 * Donald Becker, <becker@super.org>
12 * Alan Cox, <Alan.Cox@linux.org>
13 * Richard Underwood
14 * Stefan Becker, <stefanb@yello.ping.de>
15 * Jorge Cwik, <jorge@laser.satlink.net>
16 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
17 * Hirokazu Takahashi, <taka@valinux.co.jp>
18 *
19 * See ip_input.c for original log
20 *
21 * Fixes:
22 * Alan Cox : Missing nonblock feature in ip_build_xmit.
23 * Mike Kilburn : htons() missing in ip_build_xmit.
24 * Bradford Johnson: Fix faulty handling of some frames when
25 * no route is found.
26 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit
27 * (in case if packet not accepted by
28 * output firewall rules)
29 * Mike McLagan : Routing by source
30 * Alexey Kuznetsov: use new route cache
31 * Andi Kleen: Fix broken PMTU recovery and remove
32 * some redundant tests.
33 * Vitaly E. Lavrov : Transparent proxy revived after year coma.
34 * Andi Kleen : Replace ip_reply with ip_send_reply.
35 * Andi Kleen : Split fast and slow ip_build_xmit path
36 * for decreased register pressure on x86
37 * and more readability.
38 * Marc Boucher : When call_out_firewall returns FW_QUEUE,
39 * silently drop skb instead of failing with -EPERM.
40 * Detlev Wengorz : Copy protocol for fragments.
41 * Hirokazu Takahashi: HW checksumming for outgoing UDP
42 * datagrams.
43 * Hirokazu Takahashi: sendfile() on UDP works now.
44 */
45
46#include <linux/uaccess.h>
47#include <linux/module.h>
48#include <linux/types.h>
49#include <linux/kernel.h>
50#include <linux/mm.h>
51#include <linux/string.h>
52#include <linux/errno.h>
53#include <linux/highmem.h>
54#include <linux/slab.h>
55
56#include <linux/socket.h>
57#include <linux/sockios.h>
58#include <linux/in.h>
59#include <linux/inet.h>
60#include <linux/netdevice.h>
61#include <linux/etherdevice.h>
62#include <linux/proc_fs.h>
63#include <linux/stat.h>
64#include <linux/init.h>
65
66#include <net/snmp.h>
67#include <net/ip.h>
68#include <net/protocol.h>
69#include <net/route.h>
70#include <net/xfrm.h>
71#include <linux/skbuff.h>
72#include <net/sock.h>
73#include <net/arp.h>
74#include <net/icmp.h>
75#include <net/checksum.h>
76#include <net/gso.h>
77#include <net/inetpeer.h>
78#include <net/lwtunnel.h>
79#include <net/inet_dscp.h>
80#include <linux/bpf-cgroup.h>
81#include <linux/igmp.h>
82#include <linux/netfilter_ipv4.h>
83#include <linux/netfilter_bridge.h>
84#include <linux/netlink.h>
85#include <linux/tcp.h>
86
87static int
88ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
89 unsigned int mtu,
90 int (*output)(struct net *, struct sock *, struct sk_buff *));
91
92/* Generate a checksum for an outgoing IP datagram. */
93void ip_send_check(struct iphdr *iph)
94{
95 iph->check = 0;
96 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
97}
98EXPORT_SYMBOL(ip_send_check);
99
100int __ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
101{
102 struct iphdr *iph = ip_hdr(skb);
103
104 IP_INC_STATS(net, IPSTATS_MIB_OUTREQUESTS);
105
106 iph_set_totlen(iph, skb->len);
107 ip_send_check(iph);
108
109 /* if egress device is enslaved to an L3 master device pass the
110 * skb to its handler for processing
111 */
112 skb = l3mdev_ip_out(sk, skb);
113 if (unlikely(!skb))
114 return 0;
115
116 skb->protocol = htons(ETH_P_IP);
117
118 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT,
119 net, sk, skb, NULL, skb_dst(skb)->dev,
120 dst_output);
121}
122
123int ip_local_out(struct net *net, struct sock *sk, struct sk_buff *skb)
124{
125 int err;
126
127 err = __ip_local_out(net, sk, skb);
128 if (likely(err == 1))
129 err = dst_output(net, sk, skb);
130
131 return err;
132}
133EXPORT_SYMBOL_GPL(ip_local_out);
134
135static inline int ip_select_ttl(const struct inet_sock *inet,
136 const struct dst_entry *dst)
137{
138 int ttl = READ_ONCE(inet->uc_ttl);
139
140 if (ttl < 0)
141 ttl = ip4_dst_hoplimit(dst);
142 return ttl;
143}
144
145/*
146 * Add an ip header to a skbuff and send it out.
147 *
148 */
149int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
150 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt,
151 u8 tos)
152{
153 const struct inet_sock *inet = inet_sk(sk);
154 struct rtable *rt = skb_rtable(skb);
155 struct net *net = sock_net(sk);
156 struct iphdr *iph;
157
158 /* Build the IP header. */
159 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
160 skb_reset_network_header(skb);
161 iph = ip_hdr(skb);
162 iph->version = 4;
163 iph->ihl = 5;
164 iph->tos = tos;
165 iph->ttl = ip_select_ttl(inet, &rt->dst);
166 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
167 iph->saddr = saddr;
168 iph->protocol = sk->sk_protocol;
169 /* Do not bother generating IPID for small packets (eg SYNACK) */
170 if (skb->len <= IPV4_MIN_MTU || ip_dont_fragment(sk, &rt->dst)) {
171 iph->frag_off = htons(IP_DF);
172 iph->id = 0;
173 } else {
174 iph->frag_off = 0;
175 /* TCP packets here are SYNACK with fat IPv4/TCP options.
176 * Avoid using the hashed IP ident generator.
177 */
178 if (sk->sk_protocol == IPPROTO_TCP)
179 iph->id = (__force __be16)get_random_u16();
180 else
181 __ip_select_ident(net, iph, 1);
182 }
183
184 if (opt && opt->opt.optlen) {
185 iph->ihl += opt->opt.optlen>>2;
186 ip_options_build(skb, &opt->opt, daddr, rt);
187 }
188
189 skb->priority = READ_ONCE(sk->sk_priority);
190 if (!skb->mark)
191 skb->mark = READ_ONCE(sk->sk_mark);
192
193 /* Send it out. */
194 return ip_local_out(net, skb->sk, skb);
195}
196EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
197
198static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
199{
200 struct dst_entry *dst = skb_dst(skb);
201 struct rtable *rt = dst_rtable(dst);
202 struct net_device *dev = dst->dev;
203 unsigned int hh_len = LL_RESERVED_SPACE(dev);
204 struct neighbour *neigh;
205 bool is_v6gw = false;
206
207 if (rt->rt_type == RTN_MULTICAST) {
208 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
209 } else if (rt->rt_type == RTN_BROADCAST)
210 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTBCAST, skb->len);
211
212 /* OUTOCTETS should be counted after fragment */
213 IP_UPD_PO_STATS(net, IPSTATS_MIB_OUT, skb->len);
214
215 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
216 skb = skb_expand_head(skb, hh_len);
217 if (!skb)
218 return -ENOMEM;
219 }
220
221 if (lwtunnel_xmit_redirect(dst->lwtstate)) {
222 int res = lwtunnel_xmit(skb);
223
224 if (res != LWTUNNEL_XMIT_CONTINUE)
225 return res;
226 }
227
228 rcu_read_lock();
229 neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
230 if (!IS_ERR(neigh)) {
231 int res;
232
233 sock_confirm_neigh(skb, neigh);
234 /* if crossing protocols, can not use the cached header */
235 res = neigh_output(neigh, skb, is_v6gw);
236 rcu_read_unlock();
237 return res;
238 }
239 rcu_read_unlock();
240
241 net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
242 __func__);
243 kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
244 return PTR_ERR(neigh);
245}
246
247static int ip_finish_output_gso(struct net *net, struct sock *sk,
248 struct sk_buff *skb, unsigned int mtu)
249{
250 struct sk_buff *segs, *nskb;
251 netdev_features_t features;
252 int ret = 0;
253
254 /* common case: seglen is <= mtu
255 */
256 if (skb_gso_validate_network_len(skb, mtu))
257 return ip_finish_output2(net, sk, skb);
258
259 /* Slowpath - GSO segment length exceeds the egress MTU.
260 *
261 * This can happen in several cases:
262 * - Forwarding of a TCP GRO skb, when DF flag is not set.
263 * - Forwarding of an skb that arrived on a virtualization interface
264 * (virtio-net/vhost/tap) with TSO/GSO size set by other network
265 * stack.
266 * - Local GSO skb transmitted on an NETIF_F_TSO tunnel stacked over an
267 * interface with a smaller MTU.
268 * - Arriving GRO skb (or GSO skb in a virtualized environment) that is
269 * bridged to a NETIF_F_TSO tunnel stacked over an interface with an
270 * insufficient MTU.
271 */
272 features = netif_skb_features(skb);
273 BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
274 segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
275 if (IS_ERR_OR_NULL(segs)) {
276 kfree_skb(skb);
277 return -ENOMEM;
278 }
279
280 consume_skb(skb);
281
282 skb_list_walk_safe(segs, segs, nskb) {
283 int err;
284
285 skb_mark_not_on_list(segs);
286 err = ip_fragment(net, sk, segs, mtu, ip_finish_output2);
287
288 if (err && ret == 0)
289 ret = err;
290 }
291
292 return ret;
293}
294
295static int __ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
296{
297 unsigned int mtu;
298
299#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
300 /* Policy lookup after SNAT yielded a new policy */
301 if (skb_dst(skb)->xfrm) {
302 IPCB(skb)->flags |= IPSKB_REROUTED;
303 return dst_output(net, sk, skb);
304 }
305#endif
306 mtu = ip_skb_dst_mtu(sk, skb);
307 if (skb_is_gso(skb))
308 return ip_finish_output_gso(net, sk, skb, mtu);
309
310 if (skb->len > mtu || IPCB(skb)->frag_max_size)
311 return ip_fragment(net, sk, skb, mtu, ip_finish_output2);
312
313 return ip_finish_output2(net, sk, skb);
314}
315
316static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
317{
318 int ret;
319
320 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
321 switch (ret) {
322 case NET_XMIT_SUCCESS:
323 return __ip_finish_output(net, sk, skb);
324 case NET_XMIT_CN:
325 return __ip_finish_output(net, sk, skb) ? : ret;
326 default:
327 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
328 return ret;
329 }
330}
331
332static int ip_mc_finish_output(struct net *net, struct sock *sk,
333 struct sk_buff *skb)
334{
335 struct rtable *new_rt;
336 bool do_cn = false;
337 int ret, err;
338
339 ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
340 switch (ret) {
341 case NET_XMIT_CN:
342 do_cn = true;
343 fallthrough;
344 case NET_XMIT_SUCCESS:
345 break;
346 default:
347 kfree_skb_reason(skb, SKB_DROP_REASON_BPF_CGROUP_EGRESS);
348 return ret;
349 }
350
351 /* Reset rt_iif so that inet_iif() will return skb->skb_iif. Setting
352 * this to non-zero causes ipi_ifindex in in_pktinfo to be overwritten,
353 * see ipv4_pktinfo_prepare().
354 */
355 new_rt = rt_dst_clone(net->loopback_dev, skb_rtable(skb));
356 if (new_rt) {
357 new_rt->rt_iif = 0;
358 skb_dst_drop(skb);
359 skb_dst_set(skb, &new_rt->dst);
360 }
361
362 err = dev_loopback_xmit(net, sk, skb);
363 return (do_cn && err) ? ret : err;
364}
365
366int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb)
367{
368 struct rtable *rt = skb_rtable(skb);
369 struct net_device *dev = rt->dst.dev;
370
371 /*
372 * If the indicated interface is up and running, send the packet.
373 */
374 skb->dev = dev;
375 skb->protocol = htons(ETH_P_IP);
376
377 /*
378 * Multicasts are looped back for other local users
379 */
380
381 if (rt->rt_flags&RTCF_MULTICAST) {
382 if (sk_mc_loop(sk)
383#ifdef CONFIG_IP_MROUTE
384 /* Small optimization: do not loopback not local frames,
385 which returned after forwarding; they will be dropped
386 by ip_mr_input in any case.
387 Note, that local frames are looped back to be delivered
388 to local recipients.
389
390 This check is duplicated in ip_mr_input at the moment.
391 */
392 &&
393 ((rt->rt_flags & RTCF_LOCAL) ||
394 !(IPCB(skb)->flags & IPSKB_FORWARDED))
395#endif
396 ) {
397 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
398 if (newskb)
399 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
400 net, sk, newskb, NULL, newskb->dev,
401 ip_mc_finish_output);
402 }
403
404 /* Multicasts with ttl 0 must not go beyond the host */
405
406 if (ip_hdr(skb)->ttl == 0) {
407 kfree_skb(skb);
408 return 0;
409 }
410 }
411
412 if (rt->rt_flags&RTCF_BROADCAST) {
413 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
414 if (newskb)
415 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
416 net, sk, newskb, NULL, newskb->dev,
417 ip_mc_finish_output);
418 }
419
420 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
421 net, sk, skb, NULL, skb->dev,
422 ip_finish_output,
423 !(IPCB(skb)->flags & IPSKB_REROUTED));
424}
425
426int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb)
427{
428 struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev;
429
430 skb->dev = dev;
431 skb->protocol = htons(ETH_P_IP);
432
433 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
434 net, sk, skb, indev, dev,
435 ip_finish_output,
436 !(IPCB(skb)->flags & IPSKB_REROUTED));
437}
438EXPORT_SYMBOL(ip_output);
439
440/*
441 * copy saddr and daddr, possibly using 64bit load/stores
442 * Equivalent to :
443 * iph->saddr = fl4->saddr;
444 * iph->daddr = fl4->daddr;
445 */
446static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4)
447{
448 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) !=
449 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr));
450
451 iph->saddr = fl4->saddr;
452 iph->daddr = fl4->daddr;
453}
454
455/* Note: skb->sk can be different from sk, in case of tunnels */
456int __ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
457 __u8 tos)
458{
459 struct inet_sock *inet = inet_sk(sk);
460 struct net *net = sock_net(sk);
461 struct ip_options_rcu *inet_opt;
462 struct flowi4 *fl4;
463 struct rtable *rt;
464 struct iphdr *iph;
465 int res;
466
467 /* Skip all of this if the packet is already routed,
468 * f.e. by something like SCTP.
469 */
470 rcu_read_lock();
471 inet_opt = rcu_dereference(inet->inet_opt);
472 fl4 = &fl->u.ip4;
473 rt = skb_rtable(skb);
474 if (rt)
475 goto packet_routed;
476
477 /* Make sure we can route this packet. */
478 rt = dst_rtable(__sk_dst_check(sk, 0));
479 if (!rt) {
480 inet_sk_init_flowi4(inet, fl4);
481
482 /* sctp_v4_xmit() uses its own DSCP value */
483 fl4->flowi4_tos = tos & INET_DSCP_MASK;
484
485 /* If this fails, retransmit mechanism of transport layer will
486 * keep trying until route appears or the connection times
487 * itself out.
488 */
489 rt = ip_route_output_flow(net, fl4, sk);
490 if (IS_ERR(rt))
491 goto no_route;
492 sk_setup_caps(sk, &rt->dst);
493 }
494 skb_dst_set_noref(skb, &rt->dst);
495
496packet_routed:
497 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_uses_gateway)
498 goto no_route;
499
500 /* OK, we know where to send it, allocate and build IP header. */
501 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
502 skb_reset_network_header(skb);
503 iph = ip_hdr(skb);
504 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (tos & 0xff));
505 if (ip_dont_fragment(sk, &rt->dst) && !skb->ignore_df)
506 iph->frag_off = htons(IP_DF);
507 else
508 iph->frag_off = 0;
509 iph->ttl = ip_select_ttl(inet, &rt->dst);
510 iph->protocol = sk->sk_protocol;
511 ip_copy_addrs(iph, fl4);
512
513 /* Transport layer set skb->h.foo itself. */
514
515 if (inet_opt && inet_opt->opt.optlen) {
516 iph->ihl += inet_opt->opt.optlen >> 2;
517 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt);
518 }
519
520 ip_select_ident_segs(net, skb, sk,
521 skb_shinfo(skb)->gso_segs ?: 1);
522
523 /* TODO : should we use skb->sk here instead of sk ? */
524 skb->priority = READ_ONCE(sk->sk_priority);
525 skb->mark = READ_ONCE(sk->sk_mark);
526
527 res = ip_local_out(net, sk, skb);
528 rcu_read_unlock();
529 return res;
530
531no_route:
532 rcu_read_unlock();
533 IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
534 kfree_skb_reason(skb, SKB_DROP_REASON_IP_OUTNOROUTES);
535 return -EHOSTUNREACH;
536}
537EXPORT_SYMBOL(__ip_queue_xmit);
538
539int ip_queue_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl)
540{
541 return __ip_queue_xmit(sk, skb, fl, READ_ONCE(inet_sk(sk)->tos));
542}
543EXPORT_SYMBOL(ip_queue_xmit);
544
545static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
546{
547 to->pkt_type = from->pkt_type;
548 to->priority = from->priority;
549 to->protocol = from->protocol;
550 to->skb_iif = from->skb_iif;
551 skb_dst_drop(to);
552 skb_dst_copy(to, from);
553 to->dev = from->dev;
554 to->mark = from->mark;
555
556 skb_copy_hash(to, from);
557
558#ifdef CONFIG_NET_SCHED
559 to->tc_index = from->tc_index;
560#endif
561 nf_copy(to, from);
562 skb_ext_copy(to, from);
563#if IS_ENABLED(CONFIG_IP_VS)
564 to->ipvs_property = from->ipvs_property;
565#endif
566 skb_copy_secmark(to, from);
567}
568
569static int ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
570 unsigned int mtu,
571 int (*output)(struct net *, struct sock *, struct sk_buff *))
572{
573 struct iphdr *iph = ip_hdr(skb);
574
575 if ((iph->frag_off & htons(IP_DF)) == 0)
576 return ip_do_fragment(net, sk, skb, output);
577
578 if (unlikely(!skb->ignore_df ||
579 (IPCB(skb)->frag_max_size &&
580 IPCB(skb)->frag_max_size > mtu))) {
581 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
582 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
583 htonl(mtu));
584 kfree_skb(skb);
585 return -EMSGSIZE;
586 }
587
588 return ip_do_fragment(net, sk, skb, output);
589}
590
591void ip_fraglist_init(struct sk_buff *skb, struct iphdr *iph,
592 unsigned int hlen, struct ip_fraglist_iter *iter)
593{
594 unsigned int first_len = skb_pagelen(skb);
595
596 iter->frag = skb_shinfo(skb)->frag_list;
597 skb_frag_list_init(skb);
598
599 iter->offset = 0;
600 iter->iph = iph;
601 iter->hlen = hlen;
602
603 skb->data_len = first_len - skb_headlen(skb);
604 skb->len = first_len;
605 iph->tot_len = htons(first_len);
606 iph->frag_off = htons(IP_MF);
607 ip_send_check(iph);
608}
609EXPORT_SYMBOL(ip_fraglist_init);
610
611void ip_fraglist_prepare(struct sk_buff *skb, struct ip_fraglist_iter *iter)
612{
613 unsigned int hlen = iter->hlen;
614 struct iphdr *iph = iter->iph;
615 struct sk_buff *frag;
616
617 frag = iter->frag;
618 frag->ip_summed = CHECKSUM_NONE;
619 skb_reset_transport_header(frag);
620 __skb_push(frag, hlen);
621 skb_reset_network_header(frag);
622 memcpy(skb_network_header(frag), iph, hlen);
623 iter->iph = ip_hdr(frag);
624 iph = iter->iph;
625 iph->tot_len = htons(frag->len);
626 ip_copy_metadata(frag, skb);
627 iter->offset += skb->len - hlen;
628 iph->frag_off = htons(iter->offset >> 3);
629 if (frag->next)
630 iph->frag_off |= htons(IP_MF);
631 /* Ready, complete checksum */
632 ip_send_check(iph);
633}
634EXPORT_SYMBOL(ip_fraglist_prepare);
635
636void ip_frag_init(struct sk_buff *skb, unsigned int hlen,
637 unsigned int ll_rs, unsigned int mtu, bool DF,
638 struct ip_frag_state *state)
639{
640 struct iphdr *iph = ip_hdr(skb);
641
642 state->DF = DF;
643 state->hlen = hlen;
644 state->ll_rs = ll_rs;
645 state->mtu = mtu;
646
647 state->left = skb->len - hlen; /* Space per frame */
648 state->ptr = hlen; /* Where to start from */
649
650 state->offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
651 state->not_last_frag = iph->frag_off & htons(IP_MF);
652}
653EXPORT_SYMBOL(ip_frag_init);
654
655static void ip_frag_ipcb(struct sk_buff *from, struct sk_buff *to,
656 bool first_frag)
657{
658 /* Copy the flags to each fragment. */
659 IPCB(to)->flags = IPCB(from)->flags;
660
661 /* ANK: dirty, but effective trick. Upgrade options only if
662 * the segment to be fragmented was THE FIRST (otherwise,
663 * options are already fixed) and make it ONCE
664 * on the initial skb, so that all the following fragments
665 * will inherit fixed options.
666 */
667 if (first_frag)
668 ip_options_fragment(from);
669}
670
671struct sk_buff *ip_frag_next(struct sk_buff *skb, struct ip_frag_state *state)
672{
673 unsigned int len = state->left;
674 struct sk_buff *skb2;
675 struct iphdr *iph;
676
677 /* IF: it doesn't fit, use 'mtu' - the data space left */
678 if (len > state->mtu)
679 len = state->mtu;
680 /* IF: we are not sending up to and including the packet end
681 then align the next start on an eight byte boundary */
682 if (len < state->left) {
683 len &= ~7;
684 }
685
686 /* Allocate buffer */
687 skb2 = alloc_skb(len + state->hlen + state->ll_rs, GFP_ATOMIC);
688 if (!skb2)
689 return ERR_PTR(-ENOMEM);
690
691 /*
692 * Set up data on packet
693 */
694
695 ip_copy_metadata(skb2, skb);
696 skb_reserve(skb2, state->ll_rs);
697 skb_put(skb2, len + state->hlen);
698 skb_reset_network_header(skb2);
699 skb2->transport_header = skb2->network_header + state->hlen;
700
701 /*
702 * Charge the memory for the fragment to any owner
703 * it might possess
704 */
705
706 if (skb->sk)
707 skb_set_owner_w(skb2, skb->sk);
708
709 /*
710 * Copy the packet header into the new buffer.
711 */
712
713 skb_copy_from_linear_data(skb, skb_network_header(skb2), state->hlen);
714
715 /*
716 * Copy a block of the IP datagram.
717 */
718 if (skb_copy_bits(skb, state->ptr, skb_transport_header(skb2), len))
719 BUG();
720 state->left -= len;
721
722 /*
723 * Fill in the new header fields.
724 */
725 iph = ip_hdr(skb2);
726 iph->frag_off = htons((state->offset >> 3));
727 if (state->DF)
728 iph->frag_off |= htons(IP_DF);
729
730 /*
731 * Added AC : If we are fragmenting a fragment that's not the
732 * last fragment then keep MF on each bit
733 */
734 if (state->left > 0 || state->not_last_frag)
735 iph->frag_off |= htons(IP_MF);
736 state->ptr += len;
737 state->offset += len;
738
739 iph->tot_len = htons(len + state->hlen);
740
741 ip_send_check(iph);
742
743 return skb2;
744}
745EXPORT_SYMBOL(ip_frag_next);
746
747/*
748 * This IP datagram is too large to be sent in one piece. Break it up into
749 * smaller pieces (each of size equal to IP header plus
750 * a block of the data of the original IP data part) that will yet fit in a
751 * single device frame, and queue such a frame for sending.
752 */
753
754int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
755 int (*output)(struct net *, struct sock *, struct sk_buff *))
756{
757 struct iphdr *iph;
758 struct sk_buff *skb2;
759 u8 tstamp_type = skb->tstamp_type;
760 struct rtable *rt = skb_rtable(skb);
761 unsigned int mtu, hlen, ll_rs;
762 struct ip_fraglist_iter iter;
763 ktime_t tstamp = skb->tstamp;
764 struct ip_frag_state state;
765 int err = 0;
766
767 /* for offloaded checksums cleanup checksum before fragmentation */
768 if (skb->ip_summed == CHECKSUM_PARTIAL &&
769 (err = skb_checksum_help(skb)))
770 goto fail;
771
772 /*
773 * Point into the IP datagram header.
774 */
775
776 iph = ip_hdr(skb);
777
778 mtu = ip_skb_dst_mtu(sk, skb);
779 if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu)
780 mtu = IPCB(skb)->frag_max_size;
781
782 /*
783 * Setup starting values.
784 */
785
786 hlen = iph->ihl * 4;
787 mtu = mtu - hlen; /* Size of data space */
788 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
789 ll_rs = LL_RESERVED_SPACE(rt->dst.dev);
790
791 /* When frag_list is given, use it. First, check its validity:
792 * some transformers could create wrong frag_list or break existing
793 * one, it is not prohibited. In this case fall back to copying.
794 *
795 * LATER: this step can be merged to real generation of fragments,
796 * we can switch to copy when see the first bad fragment.
797 */
798 if (skb_has_frag_list(skb)) {
799 struct sk_buff *frag, *frag2;
800 unsigned int first_len = skb_pagelen(skb);
801
802 if (first_len - hlen > mtu ||
803 ((first_len - hlen) & 7) ||
804 ip_is_fragment(iph) ||
805 skb_cloned(skb) ||
806 skb_headroom(skb) < ll_rs)
807 goto slow_path;
808
809 skb_walk_frags(skb, frag) {
810 /* Correct geometry. */
811 if (frag->len > mtu ||
812 ((frag->len & 7) && frag->next) ||
813 skb_headroom(frag) < hlen + ll_rs)
814 goto slow_path_clean;
815
816 /* Partially cloned skb? */
817 if (skb_shared(frag))
818 goto slow_path_clean;
819
820 BUG_ON(frag->sk);
821 if (skb->sk) {
822 frag->sk = skb->sk;
823 frag->destructor = sock_wfree;
824 }
825 skb->truesize -= frag->truesize;
826 }
827
828 /* Everything is OK. Generate! */
829 ip_fraglist_init(skb, iph, hlen, &iter);
830
831 for (;;) {
832 /* Prepare header of the next frame,
833 * before previous one went down. */
834 if (iter.frag) {
835 bool first_frag = (iter.offset == 0);
836
837 IPCB(iter.frag)->flags = IPCB(skb)->flags;
838 ip_fraglist_prepare(skb, &iter);
839 if (first_frag && IPCB(skb)->opt.optlen) {
840 /* ipcb->opt is not populated for frags
841 * coming from __ip_make_skb(),
842 * ip_options_fragment() needs optlen
843 */
844 IPCB(iter.frag)->opt.optlen =
845 IPCB(skb)->opt.optlen;
846 ip_options_fragment(iter.frag);
847 ip_send_check(iter.iph);
848 }
849 }
850
851 skb_set_delivery_time(skb, tstamp, tstamp_type);
852 err = output(net, sk, skb);
853
854 if (!err)
855 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
856 if (err || !iter.frag)
857 break;
858
859 skb = ip_fraglist_next(&iter);
860 }
861
862 if (err == 0) {
863 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
864 return 0;
865 }
866
867 kfree_skb_list(iter.frag);
868
869 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
870 return err;
871
872slow_path_clean:
873 skb_walk_frags(skb, frag2) {
874 if (frag2 == frag)
875 break;
876 frag2->sk = NULL;
877 frag2->destructor = NULL;
878 skb->truesize += frag2->truesize;
879 }
880 }
881
882slow_path:
883 /*
884 * Fragment the datagram.
885 */
886
887 ip_frag_init(skb, hlen, ll_rs, mtu, IPCB(skb)->flags & IPSKB_FRAG_PMTU,
888 &state);
889
890 /*
891 * Keep copying data until we run out.
892 */
893
894 while (state.left > 0) {
895 bool first_frag = (state.offset == 0);
896
897 skb2 = ip_frag_next(skb, &state);
898 if (IS_ERR(skb2)) {
899 err = PTR_ERR(skb2);
900 goto fail;
901 }
902 ip_frag_ipcb(skb, skb2, first_frag);
903
904 /*
905 * Put this fragment into the sending queue.
906 */
907 skb_set_delivery_time(skb2, tstamp, tstamp_type);
908 err = output(net, sk, skb2);
909 if (err)
910 goto fail;
911
912 IP_INC_STATS(net, IPSTATS_MIB_FRAGCREATES);
913 }
914 consume_skb(skb);
915 IP_INC_STATS(net, IPSTATS_MIB_FRAGOKS);
916 return err;
917
918fail:
919 kfree_skb(skb);
920 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
921 return err;
922}
923EXPORT_SYMBOL(ip_do_fragment);
924
925int
926ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
927{
928 struct msghdr *msg = from;
929
930 if (skb->ip_summed == CHECKSUM_PARTIAL) {
931 if (!copy_from_iter_full(to, len, &msg->msg_iter))
932 return -EFAULT;
933 } else {
934 __wsum csum = 0;
935 if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter))
936 return -EFAULT;
937 skb->csum = csum_block_add(skb->csum, csum, odd);
938 }
939 return 0;
940}
941EXPORT_SYMBOL(ip_generic_getfrag);
942
943static int __ip_append_data(struct sock *sk,
944 struct flowi4 *fl4,
945 struct sk_buff_head *queue,
946 struct inet_cork *cork,
947 struct page_frag *pfrag,
948 int getfrag(void *from, char *to, int offset,
949 int len, int odd, struct sk_buff *skb),
950 void *from, int length, int transhdrlen,
951 unsigned int flags)
952{
953 struct inet_sock *inet = inet_sk(sk);
954 struct ubuf_info *uarg = NULL;
955 struct sk_buff *skb;
956 struct ip_options *opt = cork->opt;
957 int hh_len;
958 int exthdrlen;
959 int mtu;
960 int copy;
961 int err;
962 int offset = 0;
963 bool zc = false;
964 unsigned int maxfraglen, fragheaderlen, maxnonfragsize;
965 int csummode = CHECKSUM_NONE;
966 struct rtable *rt = dst_rtable(cork->dst);
967 bool paged, hold_tskey = false, extra_uref = false;
968 unsigned int wmem_alloc_delta = 0;
969 u32 tskey = 0;
970
971 skb = skb_peek_tail(queue);
972
973 exthdrlen = !skb ? rt->dst.header_len : 0;
974 mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize;
975 paged = !!cork->gso_size;
976
977 hh_len = LL_RESERVED_SPACE(rt->dst.dev);
978
979 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
980 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
981 maxnonfragsize = ip_sk_ignore_df(sk) ? IP_MAX_MTU : mtu;
982
983 if (cork->length + length > maxnonfragsize - fragheaderlen) {
984 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
985 mtu - (opt ? opt->optlen : 0));
986 return -EMSGSIZE;
987 }
988
989 /*
990 * transhdrlen > 0 means that this is the first fragment and we wish
991 * it won't be fragmented in the future.
992 */
993 if (transhdrlen &&
994 length + fragheaderlen <= mtu &&
995 rt->dst.dev->features & (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM) &&
996 (!(flags & MSG_MORE) || cork->gso_size) &&
997 (!exthdrlen || (rt->dst.dev->features & NETIF_F_HW_ESP_TX_CSUM)))
998 csummode = CHECKSUM_PARTIAL;
999
1000 if ((flags & MSG_ZEROCOPY) && length) {
1001 struct msghdr *msg = from;
1002
1003 if (getfrag == ip_generic_getfrag && msg->msg_ubuf) {
1004 if (skb_zcopy(skb) && msg->msg_ubuf != skb_zcopy(skb))
1005 return -EINVAL;
1006
1007 /* Leave uarg NULL if can't zerocopy, callers should
1008 * be able to handle it.
1009 */
1010 if ((rt->dst.dev->features & NETIF_F_SG) &&
1011 csummode == CHECKSUM_PARTIAL) {
1012 paged = true;
1013 zc = true;
1014 uarg = msg->msg_ubuf;
1015 }
1016 } else if (sock_flag(sk, SOCK_ZEROCOPY)) {
1017 uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
1018 false);
1019 if (!uarg)
1020 return -ENOBUFS;
1021 extra_uref = !skb_zcopy(skb); /* only ref on new uarg */
1022 if (rt->dst.dev->features & NETIF_F_SG &&
1023 csummode == CHECKSUM_PARTIAL) {
1024 paged = true;
1025 zc = true;
1026 } else {
1027 uarg_to_msgzc(uarg)->zerocopy = 0;
1028 skb_zcopy_set(skb, uarg, &extra_uref);
1029 }
1030 }
1031 } else if ((flags & MSG_SPLICE_PAGES) && length) {
1032 if (inet_test_bit(HDRINCL, sk))
1033 return -EPERM;
1034 if (rt->dst.dev->features & NETIF_F_SG &&
1035 getfrag == ip_generic_getfrag)
1036 /* We need an empty buffer to attach stuff to */
1037 paged = true;
1038 else
1039 flags &= ~MSG_SPLICE_PAGES;
1040 }
1041
1042 cork->length += length;
1043
1044 if (cork->tx_flags & SKBTX_ANY_TSTAMP &&
1045 READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) {
1046 if (cork->flags & IPCORK_TS_OPT_ID) {
1047 tskey = cork->ts_opt_id;
1048 } else {
1049 tskey = atomic_inc_return(&sk->sk_tskey) - 1;
1050 hold_tskey = true;
1051 }
1052 }
1053
1054 /* So, what's going on in the loop below?
1055 *
1056 * We use calculated fragment length to generate chained skb,
1057 * each of segments is IP fragment ready for sending to network after
1058 * adding appropriate IP header.
1059 */
1060
1061 if (!skb)
1062 goto alloc_new_skb;
1063
1064 while (length > 0) {
1065 /* Check if the remaining data fits into current packet. */
1066 copy = mtu - skb->len;
1067 if (copy < length)
1068 copy = maxfraglen - skb->len;
1069 if (copy <= 0) {
1070 char *data;
1071 unsigned int datalen;
1072 unsigned int fraglen;
1073 unsigned int fraggap;
1074 unsigned int alloclen, alloc_extra;
1075 unsigned int pagedlen;
1076 struct sk_buff *skb_prev;
1077alloc_new_skb:
1078 skb_prev = skb;
1079 if (skb_prev)
1080 fraggap = skb_prev->len - maxfraglen;
1081 else
1082 fraggap = 0;
1083
1084 /*
1085 * If remaining data exceeds the mtu,
1086 * we know we need more fragment(s).
1087 */
1088 datalen = length + fraggap;
1089 if (datalen > mtu - fragheaderlen)
1090 datalen = maxfraglen - fragheaderlen;
1091 fraglen = datalen + fragheaderlen;
1092 pagedlen = 0;
1093
1094 alloc_extra = hh_len + 15;
1095 alloc_extra += exthdrlen;
1096
1097 /* The last fragment gets additional space at tail.
1098 * Note, with MSG_MORE we overallocate on fragments,
1099 * because we have no idea what fragment will be
1100 * the last.
1101 */
1102 if (datalen == length + fraggap)
1103 alloc_extra += rt->dst.trailer_len;
1104
1105 if ((flags & MSG_MORE) &&
1106 !(rt->dst.dev->features&NETIF_F_SG))
1107 alloclen = mtu;
1108 else if (!paged &&
1109 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
1110 !(rt->dst.dev->features & NETIF_F_SG)))
1111 alloclen = fraglen;
1112 else {
1113 alloclen = fragheaderlen + transhdrlen;
1114 pagedlen = datalen - transhdrlen;
1115 }
1116
1117 alloclen += alloc_extra;
1118
1119 if (transhdrlen) {
1120 skb = sock_alloc_send_skb(sk, alloclen,
1121 (flags & MSG_DONTWAIT), &err);
1122 } else {
1123 skb = NULL;
1124 if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
1125 2 * sk->sk_sndbuf)
1126 skb = alloc_skb(alloclen,
1127 sk->sk_allocation);
1128 if (unlikely(!skb))
1129 err = -ENOBUFS;
1130 }
1131 if (!skb)
1132 goto error;
1133
1134 /*
1135 * Fill in the control structures
1136 */
1137 skb->ip_summed = csummode;
1138 skb->csum = 0;
1139 skb_reserve(skb, hh_len);
1140
1141 /*
1142 * Find where to start putting bytes.
1143 */
1144 data = skb_put(skb, fraglen + exthdrlen - pagedlen);
1145 skb_set_network_header(skb, exthdrlen);
1146 skb->transport_header = (skb->network_header +
1147 fragheaderlen);
1148 data += fragheaderlen + exthdrlen;
1149
1150 if (fraggap) {
1151 skb->csum = skb_copy_and_csum_bits(
1152 skb_prev, maxfraglen,
1153 data + transhdrlen, fraggap);
1154 skb_prev->csum = csum_sub(skb_prev->csum,
1155 skb->csum);
1156 data += fraggap;
1157 pskb_trim_unique(skb_prev, maxfraglen);
1158 }
1159
1160 copy = datalen - transhdrlen - fraggap - pagedlen;
1161 /* [!] NOTE: copy will be negative if pagedlen>0
1162 * because then the equation reduces to -fraggap.
1163 */
1164 if (copy > 0 &&
1165 INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
1166 from, data + transhdrlen, offset,
1167 copy, fraggap, skb) < 0) {
1168 err = -EFAULT;
1169 kfree_skb(skb);
1170 goto error;
1171 } else if (flags & MSG_SPLICE_PAGES) {
1172 copy = 0;
1173 }
1174
1175 offset += copy;
1176 length -= copy + transhdrlen;
1177 transhdrlen = 0;
1178 exthdrlen = 0;
1179 csummode = CHECKSUM_NONE;
1180
1181 /* only the initial fragment is time stamped */
1182 skb_shinfo(skb)->tx_flags = cork->tx_flags;
1183 cork->tx_flags = 0;
1184 skb_shinfo(skb)->tskey = tskey;
1185 tskey = 0;
1186 skb_zcopy_set(skb, uarg, &extra_uref);
1187
1188 if ((flags & MSG_CONFIRM) && !skb_prev)
1189 skb_set_dst_pending_confirm(skb, 1);
1190
1191 /*
1192 * Put the packet on the pending queue.
1193 */
1194 if (!skb->destructor) {
1195 skb->destructor = sock_wfree;
1196 skb->sk = sk;
1197 wmem_alloc_delta += skb->truesize;
1198 }
1199 __skb_queue_tail(queue, skb);
1200 continue;
1201 }
1202
1203 if (copy > length)
1204 copy = length;
1205
1206 if (!(rt->dst.dev->features&NETIF_F_SG) &&
1207 skb_tailroom(skb) >= copy) {
1208 unsigned int off;
1209
1210 off = skb->len;
1211 if (INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
1212 from, skb_put(skb, copy),
1213 offset, copy, off, skb) < 0) {
1214 __skb_trim(skb, off);
1215 err = -EFAULT;
1216 goto error;
1217 }
1218 } else if (flags & MSG_SPLICE_PAGES) {
1219 struct msghdr *msg = from;
1220
1221 err = -EIO;
1222 if (WARN_ON_ONCE(copy > msg->msg_iter.count))
1223 goto error;
1224
1225 err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
1226 sk->sk_allocation);
1227 if (err < 0)
1228 goto error;
1229 copy = err;
1230 wmem_alloc_delta += copy;
1231 } else if (!zc) {
1232 int i = skb_shinfo(skb)->nr_frags;
1233
1234 err = -ENOMEM;
1235 if (!sk_page_frag_refill(sk, pfrag))
1236 goto error;
1237
1238 skb_zcopy_downgrade_managed(skb);
1239 if (!skb_can_coalesce(skb, i, pfrag->page,
1240 pfrag->offset)) {
1241 err = -EMSGSIZE;
1242 if (i == MAX_SKB_FRAGS)
1243 goto error;
1244
1245 __skb_fill_page_desc(skb, i, pfrag->page,
1246 pfrag->offset, 0);
1247 skb_shinfo(skb)->nr_frags = ++i;
1248 get_page(pfrag->page);
1249 }
1250 copy = min_t(int, copy, pfrag->size - pfrag->offset);
1251 if (INDIRECT_CALL_1(getfrag, ip_generic_getfrag,
1252 from,
1253 page_address(pfrag->page) + pfrag->offset,
1254 offset, copy, skb->len, skb) < 0)
1255 goto error_efault;
1256
1257 pfrag->offset += copy;
1258 skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
1259 skb_len_add(skb, copy);
1260 wmem_alloc_delta += copy;
1261 } else {
1262 err = skb_zerocopy_iter_dgram(skb, from, copy);
1263 if (err < 0)
1264 goto error;
1265 }
1266 offset += copy;
1267 length -= copy;
1268 }
1269
1270 if (wmem_alloc_delta)
1271 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1272 return 0;
1273
1274error_efault:
1275 err = -EFAULT;
1276error:
1277 net_zcopy_put_abort(uarg, extra_uref);
1278 cork->length -= length;
1279 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1280 refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
1281 if (hold_tskey)
1282 atomic_dec(&sk->sk_tskey);
1283 return err;
1284}
1285
1286static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1287 struct ipcm_cookie *ipc, struct rtable **rtp)
1288{
1289 struct ip_options_rcu *opt;
1290 struct rtable *rt;
1291
1292 rt = *rtp;
1293 if (unlikely(!rt))
1294 return -EFAULT;
1295
1296 cork->fragsize = ip_sk_use_pmtu(sk) ?
1297 dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
1298
1299 if (!inetdev_valid_mtu(cork->fragsize))
1300 return -ENETUNREACH;
1301
1302 /*
1303 * setup for corking.
1304 */
1305 opt = ipc->opt;
1306 if (opt) {
1307 if (!cork->opt) {
1308 cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1309 sk->sk_allocation);
1310 if (unlikely(!cork->opt))
1311 return -ENOBUFS;
1312 }
1313 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1314 cork->flags |= IPCORK_OPT;
1315 cork->addr = ipc->addr;
1316 }
1317
1318 cork->gso_size = ipc->gso_size;
1319
1320 cork->dst = &rt->dst;
1321 /* We stole this route, caller should not release it. */
1322 *rtp = NULL;
1323
1324 cork->length = 0;
1325 cork->ttl = ipc->ttl;
1326 cork->tos = ipc->tos;
1327 cork->mark = ipc->sockc.mark;
1328 cork->priority = ipc->sockc.priority;
1329 cork->transmit_time = ipc->sockc.transmit_time;
1330 cork->tx_flags = 0;
1331 sock_tx_timestamp(sk, &ipc->sockc, &cork->tx_flags);
1332 if (ipc->sockc.tsflags & SOCKCM_FLAG_TS_OPT_ID) {
1333 cork->flags |= IPCORK_TS_OPT_ID;
1334 cork->ts_opt_id = ipc->sockc.ts_opt_id;
1335 }
1336
1337 return 0;
1338}
1339
1340/*
1341 * ip_append_data() can make one large IP datagram from many pieces of
1342 * data. Each piece will be held on the socket until
1343 * ip_push_pending_frames() is called. Each piece can be a page or
1344 * non-page data.
1345 *
1346 * Not only UDP, other transport protocols - e.g. raw sockets - can use
1347 * this interface potentially.
1348 *
1349 * LATER: length must be adjusted by pad at tail, when it is required.
1350 */
1351int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1352 int getfrag(void *from, char *to, int offset, int len,
1353 int odd, struct sk_buff *skb),
1354 void *from, int length, int transhdrlen,
1355 struct ipcm_cookie *ipc, struct rtable **rtp,
1356 unsigned int flags)
1357{
1358 struct inet_sock *inet = inet_sk(sk);
1359 int err;
1360
1361 if (flags&MSG_PROBE)
1362 return 0;
1363
1364 if (skb_queue_empty(&sk->sk_write_queue)) {
1365 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1366 if (err)
1367 return err;
1368 } else {
1369 transhdrlen = 0;
1370 }
1371
1372 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base,
1373 sk_page_frag(sk), getfrag,
1374 from, length, transhdrlen, flags);
1375}
1376
1377static void ip_cork_release(struct inet_cork *cork)
1378{
1379 cork->flags &= ~IPCORK_OPT;
1380 kfree(cork->opt);
1381 cork->opt = NULL;
1382 dst_release(cork->dst);
1383 cork->dst = NULL;
1384}
1385
1386/*
1387 * Combined all pending IP fragments on the socket as one IP datagram
1388 * and push them out.
1389 */
1390struct sk_buff *__ip_make_skb(struct sock *sk,
1391 struct flowi4 *fl4,
1392 struct sk_buff_head *queue,
1393 struct inet_cork *cork)
1394{
1395 struct sk_buff *skb, *tmp_skb;
1396 struct sk_buff **tail_skb;
1397 struct inet_sock *inet = inet_sk(sk);
1398 struct net *net = sock_net(sk);
1399 struct ip_options *opt = NULL;
1400 struct rtable *rt = dst_rtable(cork->dst);
1401 struct iphdr *iph;
1402 u8 pmtudisc, ttl;
1403 __be16 df = 0;
1404
1405 skb = __skb_dequeue(queue);
1406 if (!skb)
1407 goto out;
1408 tail_skb = &(skb_shinfo(skb)->frag_list);
1409
1410 /* move skb->data to ip header from ext header */
1411 if (skb->data < skb_network_header(skb))
1412 __skb_pull(skb, skb_network_offset(skb));
1413 while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1414 __skb_pull(tmp_skb, skb_network_header_len(skb));
1415 *tail_skb = tmp_skb;
1416 tail_skb = &(tmp_skb->next);
1417 skb->len += tmp_skb->len;
1418 skb->data_len += tmp_skb->len;
1419 skb->truesize += tmp_skb->truesize;
1420 tmp_skb->destructor = NULL;
1421 tmp_skb->sk = NULL;
1422 }
1423
1424 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1425 * to fragment the frame generated here. No matter, what transforms
1426 * how transforms change size of the packet, it will come out.
1427 */
1428 skb->ignore_df = ip_sk_ignore_df(sk);
1429
1430 /* DF bit is set when we want to see DF on outgoing frames.
1431 * If ignore_df is set too, we still allow to fragment this frame
1432 * locally. */
1433 pmtudisc = READ_ONCE(inet->pmtudisc);
1434 if (pmtudisc == IP_PMTUDISC_DO ||
1435 pmtudisc == IP_PMTUDISC_PROBE ||
1436 (skb->len <= dst_mtu(&rt->dst) &&
1437 ip_dont_fragment(sk, &rt->dst)))
1438 df = htons(IP_DF);
1439
1440 if (cork->flags & IPCORK_OPT)
1441 opt = cork->opt;
1442
1443 if (cork->ttl != 0)
1444 ttl = cork->ttl;
1445 else if (rt->rt_type == RTN_MULTICAST)
1446 ttl = READ_ONCE(inet->mc_ttl);
1447 else
1448 ttl = ip_select_ttl(inet, &rt->dst);
1449
1450 iph = ip_hdr(skb);
1451 iph->version = 4;
1452 iph->ihl = 5;
1453 iph->tos = (cork->tos != -1) ? cork->tos : READ_ONCE(inet->tos);
1454 iph->frag_off = df;
1455 iph->ttl = ttl;
1456 iph->protocol = sk->sk_protocol;
1457 ip_copy_addrs(iph, fl4);
1458 ip_select_ident(net, skb, sk);
1459
1460 if (opt) {
1461 iph->ihl += opt->optlen >> 2;
1462 ip_options_build(skb, opt, cork->addr, rt);
1463 }
1464
1465 skb->priority = cork->priority;
1466 skb->mark = cork->mark;
1467 if (sk_is_tcp(sk))
1468 skb_set_delivery_time(skb, cork->transmit_time, SKB_CLOCK_MONOTONIC);
1469 else
1470 skb_set_delivery_type_by_clockid(skb, cork->transmit_time, sk->sk_clockid);
1471 /*
1472 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1473 * on dst refcount
1474 */
1475 cork->dst = NULL;
1476 skb_dst_set(skb, &rt->dst);
1477
1478 if (iph->protocol == IPPROTO_ICMP) {
1479 u8 icmp_type;
1480
1481 /* For such sockets, transhdrlen is zero when do ip_append_data(),
1482 * so icmphdr does not in skb linear region and can not get icmp_type
1483 * by icmp_hdr(skb)->type.
1484 */
1485 if (sk->sk_type == SOCK_RAW &&
1486 !(fl4->flowi4_flags & FLOWI_FLAG_KNOWN_NH))
1487 icmp_type = fl4->fl4_icmp_type;
1488 else
1489 icmp_type = icmp_hdr(skb)->type;
1490 icmp_out_count(net, icmp_type);
1491 }
1492
1493 ip_cork_release(cork);
1494out:
1495 return skb;
1496}
1497
1498int ip_send_skb(struct net *net, struct sk_buff *skb)
1499{
1500 int err;
1501
1502 err = ip_local_out(net, skb->sk, skb);
1503 if (err) {
1504 if (err > 0)
1505 err = net_xmit_errno(err);
1506 if (err)
1507 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1508 }
1509
1510 return err;
1511}
1512
1513int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1514{
1515 struct sk_buff *skb;
1516
1517 skb = ip_finish_skb(sk, fl4);
1518 if (!skb)
1519 return 0;
1520
1521 /* Netfilter gets whole the not fragmented skb. */
1522 return ip_send_skb(sock_net(sk), skb);
1523}
1524
1525/*
1526 * Throw away all pending data on the socket.
1527 */
1528static void __ip_flush_pending_frames(struct sock *sk,
1529 struct sk_buff_head *queue,
1530 struct inet_cork *cork)
1531{
1532 struct sk_buff *skb;
1533
1534 while ((skb = __skb_dequeue_tail(queue)) != NULL)
1535 kfree_skb(skb);
1536
1537 ip_cork_release(cork);
1538}
1539
1540void ip_flush_pending_frames(struct sock *sk)
1541{
1542 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1543}
1544
1545struct sk_buff *ip_make_skb(struct sock *sk,
1546 struct flowi4 *fl4,
1547 int getfrag(void *from, char *to, int offset,
1548 int len, int odd, struct sk_buff *skb),
1549 void *from, int length, int transhdrlen,
1550 struct ipcm_cookie *ipc, struct rtable **rtp,
1551 struct inet_cork *cork, unsigned int flags)
1552{
1553 struct sk_buff_head queue;
1554 int err;
1555
1556 if (flags & MSG_PROBE)
1557 return NULL;
1558
1559 __skb_queue_head_init(&queue);
1560
1561 cork->flags = 0;
1562 cork->addr = 0;
1563 cork->opt = NULL;
1564 err = ip_setup_cork(sk, cork, ipc, rtp);
1565 if (err)
1566 return ERR_PTR(err);
1567
1568 err = __ip_append_data(sk, fl4, &queue, cork,
1569 &current->task_frag, getfrag,
1570 from, length, transhdrlen, flags);
1571 if (err) {
1572 __ip_flush_pending_frames(sk, &queue, cork);
1573 return ERR_PTR(err);
1574 }
1575
1576 return __ip_make_skb(sk, fl4, &queue, cork);
1577}
1578
1579/*
1580 * Fetch data from kernel space and fill in checksum if needed.
1581 */
1582static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1583 int len, int odd, struct sk_buff *skb)
1584{
1585 __wsum csum;
1586
1587 csum = csum_partial_copy_nocheck(dptr+offset, to, len);
1588 skb->csum = csum_block_add(skb->csum, csum, odd);
1589 return 0;
1590}
1591
1592/*
1593 * Generic function to send a packet as reply to another packet.
1594 * Used to send some TCP resets/acks so far.
1595 */
1596void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk,
1597 struct sk_buff *skb,
1598 const struct ip_options *sopt,
1599 __be32 daddr, __be32 saddr,
1600 const struct ip_reply_arg *arg,
1601 unsigned int len, u64 transmit_time, u32 txhash)
1602{
1603 struct ip_options_data replyopts;
1604 struct ipcm_cookie ipc;
1605 struct flowi4 fl4;
1606 struct rtable *rt = skb_rtable(skb);
1607 struct net *net = sock_net(sk);
1608 struct sk_buff *nskb;
1609 int err;
1610 int oif;
1611
1612 if (__ip_options_echo(net, &replyopts.opt.opt, skb, sopt))
1613 return;
1614
1615 ipcm_init(&ipc);
1616 ipc.addr = daddr;
1617 ipc.sockc.transmit_time = transmit_time;
1618
1619 if (replyopts.opt.opt.optlen) {
1620 ipc.opt = &replyopts.opt;
1621
1622 if (replyopts.opt.opt.srr)
1623 daddr = replyopts.opt.opt.faddr;
1624 }
1625
1626 oif = arg->bound_dev_if;
1627 if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
1628 oif = skb->skb_iif;
1629
1630 flowi4_init_output(&fl4, oif,
1631 IP4_REPLY_MARK(net, skb->mark) ?: sk->sk_mark,
1632 arg->tos & INET_DSCP_MASK,
1633 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol,
1634 ip_reply_arg_flowi_flags(arg),
1635 daddr, saddr,
1636 tcp_hdr(skb)->source, tcp_hdr(skb)->dest,
1637 arg->uid);
1638 security_skb_classify_flow(skb, flowi4_to_flowi_common(&fl4));
1639 rt = ip_route_output_flow(net, &fl4, sk);
1640 if (IS_ERR(rt))
1641 return;
1642
1643 inet_sk(sk)->tos = arg->tos;
1644
1645 sk->sk_protocol = ip_hdr(skb)->protocol;
1646 sk->sk_bound_dev_if = arg->bound_dev_if;
1647 sk->sk_sndbuf = READ_ONCE(sysctl_wmem_default);
1648 ipc.sockc.mark = fl4.flowi4_mark;
1649 err = ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base,
1650 len, 0, &ipc, &rt, MSG_DONTWAIT);
1651 if (unlikely(err)) {
1652 ip_flush_pending_frames(sk);
1653 goto out;
1654 }
1655
1656 nskb = skb_peek(&sk->sk_write_queue);
1657 if (nskb) {
1658 if (arg->csumoffset >= 0)
1659 *((__sum16 *)skb_transport_header(nskb) +
1660 arg->csumoffset) = csum_fold(csum_add(nskb->csum,
1661 arg->csum));
1662 nskb->ip_summed = CHECKSUM_NONE;
1663 if (orig_sk)
1664 skb_set_owner_edemux(nskb, (struct sock *)orig_sk);
1665 if (transmit_time)
1666 nskb->tstamp_type = SKB_CLOCK_MONOTONIC;
1667 if (txhash)
1668 skb_set_hash(nskb, txhash, PKT_HASH_TYPE_L4);
1669 ip_push_pending_frames(sk, &fl4);
1670 }
1671out:
1672 ip_rt_put(rt);
1673}
1674
1675void __init ip_init(void)
1676{
1677 ip_rt_init();
1678 inet_initpeers();
1679
1680#if defined(CONFIG_IP_MULTICAST)
1681 igmp_mc_init();
1682#endif
1683}
Linux 6.x block layer and io_uring tree(s)