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0baf26b0 MKL |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* Copyright (c) 2019 Facebook */ | |
3 | ||
b202d844 | 4 | #include <linux/init.h> |
0baf26b0 MKL |
5 | #include <linux/types.h> |
6 | #include <linux/bpf_verifier.h> | |
7 | #include <linux/bpf.h> | |
8 | #include <linux/btf.h> | |
e78aea8b | 9 | #include <linux/btf_ids.h> |
0baf26b0 MKL |
10 | #include <linux/filter.h> |
11 | #include <net/tcp.h> | |
ab14fd4e | 12 | #include <net/bpf_sk_storage.h> |
0baf26b0 | 13 | |
eb18b49e MKL |
14 | /* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */ |
15 | extern struct bpf_struct_ops bpf_tcp_congestion_ops; | |
16 | ||
0baf26b0 MKL |
17 | static u32 unsupported_ops[] = { |
18 | offsetof(struct tcp_congestion_ops, get_info), | |
19 | }; | |
20 | ||
21 | static const struct btf_type *tcp_sock_type; | |
22 | static u32 tcp_sock_id, sock_id; | |
23 | ||
24 | static int bpf_tcp_ca_init(struct btf *btf) | |
25 | { | |
26 | s32 type_id; | |
27 | ||
28 | type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); | |
29 | if (type_id < 0) | |
30 | return -EINVAL; | |
31 | sock_id = type_id; | |
32 | ||
33 | type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); | |
34 | if (type_id < 0) | |
35 | return -EINVAL; | |
36 | tcp_sock_id = type_id; | |
37 | tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); | |
38 | ||
39 | return 0; | |
40 | } | |
41 | ||
0baf26b0 MKL |
42 | static bool is_unsupported(u32 member_offset) |
43 | { | |
44 | unsigned int i; | |
45 | ||
46 | for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { | |
47 | if (member_offset == unsupported_ops[i]) | |
48 | return true; | |
49 | } | |
50 | ||
51 | return false; | |
52 | } | |
53 | ||
54 | extern struct btf *btf_vmlinux; | |
55 | ||
56 | static bool bpf_tcp_ca_is_valid_access(int off, int size, | |
57 | enum bpf_access_type type, | |
58 | const struct bpf_prog *prog, | |
59 | struct bpf_insn_access_aux *info) | |
60 | { | |
35346ab6 | 61 | if (!bpf_tracing_btf_ctx_access(off, size, type, prog, info)) |
0baf26b0 MKL |
62 | return false; |
63 | ||
64 | if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id) | |
65 | /* promote it to tcp_sock */ | |
66 | info->btf_id = tcp_sock_id; | |
67 | ||
68 | return true; | |
69 | } | |
70 | ||
71 | static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, | |
22dc4a0f | 72 | const struct btf *btf, |
0baf26b0 MKL |
73 | const struct btf_type *t, int off, |
74 | int size, enum bpf_access_type atype, | |
c6f1bfe8 YS |
75 | u32 *next_btf_id, |
76 | enum bpf_type_flag *flag) | |
0baf26b0 MKL |
77 | { |
78 | size_t end; | |
79 | ||
80 | if (atype == BPF_READ) | |
c6f1bfe8 YS |
81 | return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, |
82 | flag); | |
0baf26b0 MKL |
83 | |
84 | if (t != tcp_sock_type) { | |
85 | bpf_log(log, "only read is supported\n"); | |
86 | return -EACCES; | |
87 | } | |
88 | ||
89 | switch (off) { | |
41c95dd6 JTH |
90 | case offsetof(struct sock, sk_pacing_rate): |
91 | end = offsetofend(struct sock, sk_pacing_rate); | |
92 | break; | |
93 | case offsetof(struct sock, sk_pacing_status): | |
94 | end = offsetofend(struct sock, sk_pacing_status); | |
95 | break; | |
0baf26b0 MKL |
96 | case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): |
97 | end = offsetofend(struct inet_connection_sock, icsk_ca_priv); | |
98 | break; | |
99 | case offsetof(struct inet_connection_sock, icsk_ack.pending): | |
100 | end = offsetofend(struct inet_connection_sock, | |
101 | icsk_ack.pending); | |
102 | break; | |
103 | case offsetof(struct tcp_sock, snd_cwnd): | |
104 | end = offsetofend(struct tcp_sock, snd_cwnd); | |
105 | break; | |
106 | case offsetof(struct tcp_sock, snd_cwnd_cnt): | |
107 | end = offsetofend(struct tcp_sock, snd_cwnd_cnt); | |
108 | break; | |
109 | case offsetof(struct tcp_sock, snd_ssthresh): | |
110 | end = offsetofend(struct tcp_sock, snd_ssthresh); | |
111 | break; | |
112 | case offsetof(struct tcp_sock, ecn_flags): | |
113 | end = offsetofend(struct tcp_sock, ecn_flags); | |
114 | break; | |
115 | default: | |
116 | bpf_log(log, "no write support to tcp_sock at off %d\n", off); | |
117 | return -EACCES; | |
118 | } | |
119 | ||
120 | if (off + size > end) { | |
121 | bpf_log(log, | |
122 | "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", | |
123 | off, size, end); | |
124 | return -EACCES; | |
125 | } | |
126 | ||
127 | return NOT_INIT; | |
128 | } | |
129 | ||
206057fe MKL |
130 | BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) |
131 | { | |
132 | /* bpf_tcp_ca prog cannot have NULL tp */ | |
133 | __tcp_send_ack((struct sock *)tp, rcv_nxt); | |
134 | return 0; | |
135 | } | |
136 | ||
137 | static const struct bpf_func_proto bpf_tcp_send_ack_proto = { | |
138 | .func = bpf_tcp_send_ack, | |
139 | .gpl_only = false, | |
140 | /* In case we want to report error later */ | |
141 | .ret_type = RET_INTEGER, | |
142 | .arg1_type = ARG_PTR_TO_BTF_ID, | |
9436ef6e | 143 | .arg1_btf_id = &tcp_sock_id, |
206057fe | 144 | .arg2_type = ARG_ANYTHING, |
206057fe MKL |
145 | }; |
146 | ||
eb18b49e MKL |
147 | static u32 prog_ops_moff(const struct bpf_prog *prog) |
148 | { | |
149 | const struct btf_member *m; | |
150 | const struct btf_type *t; | |
151 | u32 midx; | |
152 | ||
153 | midx = prog->expected_attach_type; | |
154 | t = bpf_tcp_congestion_ops.type; | |
155 | m = &btf_type_member(t)[midx]; | |
156 | ||
8293eb99 | 157 | return __btf_member_bit_offset(t, m) / 8; |
eb18b49e MKL |
158 | } |
159 | ||
0baf26b0 MKL |
160 | static const struct bpf_func_proto * |
161 | bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, | |
162 | const struct bpf_prog *prog) | |
163 | { | |
206057fe MKL |
164 | switch (func_id) { |
165 | case BPF_FUNC_tcp_send_ack: | |
166 | return &bpf_tcp_send_ack_proto; | |
ab14fd4e | 167 | case BPF_FUNC_sk_storage_get: |
592a3498 | 168 | return &bpf_sk_storage_get_proto; |
ab14fd4e | 169 | case BPF_FUNC_sk_storage_delete: |
592a3498 | 170 | return &bpf_sk_storage_delete_proto; |
eb18b49e MKL |
171 | case BPF_FUNC_setsockopt: |
172 | /* Does not allow release() to call setsockopt. | |
173 | * release() is called when the current bpf-tcp-cc | |
174 | * is retiring. It is not allowed to call | |
175 | * setsockopt() to make further changes which | |
176 | * may potentially allocate new resources. | |
177 | */ | |
178 | if (prog_ops_moff(prog) != | |
179 | offsetof(struct tcp_congestion_ops, release)) | |
180 | return &bpf_sk_setsockopt_proto; | |
181 | return NULL; | |
182 | case BPF_FUNC_getsockopt: | |
183 | /* Since get/setsockopt is usually expected to | |
184 | * be available together, disable getsockopt for | |
185 | * release also to avoid usage surprise. | |
186 | * The bpf-tcp-cc already has a more powerful way | |
187 | * to read tcp_sock from the PTR_TO_BTF_ID. | |
188 | */ | |
189 | if (prog_ops_moff(prog) != | |
190 | offsetof(struct tcp_congestion_ops, release)) | |
191 | return &bpf_sk_getsockopt_proto; | |
192 | return NULL; | |
5e0bc308 DB |
193 | case BPF_FUNC_ktime_get_coarse_ns: |
194 | return &bpf_ktime_get_coarse_ns_proto; | |
206057fe MKL |
195 | default: |
196 | return bpf_base_func_proto(func_id); | |
197 | } | |
0baf26b0 MKL |
198 | } |
199 | ||
a4703e31 KKD |
200 | BTF_SET8_START(bpf_tcp_ca_check_kfunc_ids) |
201 | BTF_ID_FLAGS(func, tcp_reno_ssthresh) | |
202 | BTF_ID_FLAGS(func, tcp_reno_cong_avoid) | |
203 | BTF_ID_FLAGS(func, tcp_reno_undo_cwnd) | |
204 | BTF_ID_FLAGS(func, tcp_slow_start) | |
205 | BTF_ID_FLAGS(func, tcp_cong_avoid_ai) | |
206 | BTF_SET8_END(bpf_tcp_ca_check_kfunc_ids) | |
e78aea8b | 207 | |
b202d844 | 208 | static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = { |
a4703e31 KKD |
209 | .owner = THIS_MODULE, |
210 | .set = &bpf_tcp_ca_check_kfunc_ids, | |
b202d844 | 211 | }; |
e78aea8b | 212 | |
0baf26b0 MKL |
213 | static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { |
214 | .get_func_proto = bpf_tcp_ca_get_func_proto, | |
215 | .is_valid_access = bpf_tcp_ca_is_valid_access, | |
216 | .btf_struct_access = bpf_tcp_ca_btf_struct_access, | |
217 | }; | |
218 | ||
219 | static int bpf_tcp_ca_init_member(const struct btf_type *t, | |
220 | const struct btf_member *member, | |
221 | void *kdata, const void *udata) | |
222 | { | |
223 | const struct tcp_congestion_ops *utcp_ca; | |
224 | struct tcp_congestion_ops *tcp_ca; | |
0baf26b0 MKL |
225 | u32 moff; |
226 | ||
227 | utcp_ca = (const struct tcp_congestion_ops *)udata; | |
228 | tcp_ca = (struct tcp_congestion_ops *)kdata; | |
229 | ||
8293eb99 | 230 | moff = __btf_member_bit_offset(t, member) / 8; |
0baf26b0 MKL |
231 | switch (moff) { |
232 | case offsetof(struct tcp_congestion_ops, flags): | |
233 | if (utcp_ca->flags & ~TCP_CONG_MASK) | |
234 | return -EINVAL; | |
235 | tcp_ca->flags = utcp_ca->flags; | |
236 | return 1; | |
237 | case offsetof(struct tcp_congestion_ops, name): | |
8e7ae251 MKL |
238 | if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, |
239 | sizeof(tcp_ca->name)) <= 0) | |
0baf26b0 MKL |
240 | return -EINVAL; |
241 | if (tcp_ca_find(utcp_ca->name)) | |
242 | return -EEXIST; | |
0baf26b0 MKL |
243 | return 1; |
244 | } | |
245 | ||
0baf26b0 MKL |
246 | return 0; |
247 | } | |
248 | ||
249 | static int bpf_tcp_ca_check_member(const struct btf_type *t, | |
250 | const struct btf_member *member) | |
251 | { | |
8293eb99 | 252 | if (is_unsupported(__btf_member_bit_offset(t, member) / 8)) |
0baf26b0 MKL |
253 | return -ENOTSUPP; |
254 | return 0; | |
255 | } | |
256 | ||
257 | static int bpf_tcp_ca_reg(void *kdata) | |
258 | { | |
259 | return tcp_register_congestion_control(kdata); | |
260 | } | |
261 | ||
262 | static void bpf_tcp_ca_unreg(void *kdata) | |
263 | { | |
264 | tcp_unregister_congestion_control(kdata); | |
265 | } | |
266 | ||
0baf26b0 MKL |
267 | struct bpf_struct_ops bpf_tcp_congestion_ops = { |
268 | .verifier_ops = &bpf_tcp_ca_verifier_ops, | |
269 | .reg = bpf_tcp_ca_reg, | |
270 | .unreg = bpf_tcp_ca_unreg, | |
271 | .check_member = bpf_tcp_ca_check_member, | |
272 | .init_member = bpf_tcp_ca_init_member, | |
273 | .init = bpf_tcp_ca_init, | |
274 | .name = "tcp_congestion_ops", | |
275 | }; | |
b202d844 KKD |
276 | |
277 | static int __init bpf_tcp_ca_kfunc_init(void) | |
278 | { | |
279 | return register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set); | |
280 | } | |
281 | late_initcall(bpf_tcp_ca_kfunc_init); |