1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2019 Facebook */
3
4 #include <linux/types.h>
5 #include <linux/bpf_verifier.h>
6 #include <linux/bpf.h>
7 #include <linux/btf.h>
8 #include <linux/btf_ids.h>
9 #include <linux/filter.h>
10 #include <net/tcp.h>
11 #include <net/bpf_sk_storage.h>
12
13 /* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */
14 extern struct bpf_struct_ops bpf_tcp_congestion_ops;
15
16 static u32 optional_ops[] = {
17 offsetof(struct tcp_congestion_ops, init),
18 offsetof(struct tcp_congestion_ops, release),
19 offsetof(struct tcp_congestion_ops, set_state),
20 offsetof(struct tcp_congestion_ops, cwnd_event),
21 offsetof(struct tcp_congestion_ops, in_ack_event),
22 offsetof(struct tcp_congestion_ops, pkts_acked),
23 offsetof(struct tcp_congestion_ops, min_tso_segs),
24 offsetof(struct tcp_congestion_ops, sndbuf_expand),
25 offsetof(struct tcp_congestion_ops, cong_control),
26 };
27
28 static u32 unsupported_ops[] = {
29 offsetof(struct tcp_congestion_ops, get_info),
30 };
31
32 static const struct btf_type *tcp_sock_type;
33 static u32 tcp_sock_id, sock_id;
34
bpf_tcp_ca_init(struct btf * btf)35 static int bpf_tcp_ca_init(struct btf *btf)
36 {
37 s32 type_id;
38
39 type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT);
40 if (type_id < 0)
41 return -EINVAL;
42 sock_id = type_id;
43
44 type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT);
45 if (type_id < 0)
46 return -EINVAL;
47 tcp_sock_id = type_id;
48 tcp_sock_type = btf_type_by_id(btf, tcp_sock_id);
49
50 return 0;
51 }
52
is_optional(u32 member_offset)53 static bool is_optional(u32 member_offset)
54 {
55 unsigned int i;
56
57 for (i = 0; i < ARRAY_SIZE(optional_ops); i++) {
58 if (member_offset == optional_ops[i])
59 return true;
60 }
61
62 return false;
63 }
64
is_unsupported(u32 member_offset)65 static bool is_unsupported(u32 member_offset)
66 {
67 unsigned int i;
68
69 for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) {
70 if (member_offset == unsupported_ops[i])
71 return true;
72 }
73
74 return false;
75 }
76
77 extern struct btf *btf_vmlinux;
78
bpf_tcp_ca_is_valid_access(int off,int size,enum bpf_access_type type,const struct bpf_prog * prog,struct bpf_insn_access_aux * info)79 static bool bpf_tcp_ca_is_valid_access(int off, int size,
80 enum bpf_access_type type,
81 const struct bpf_prog *prog,
82 struct bpf_insn_access_aux *info)
83 {
84 if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS)
85 return false;
86 if (type != BPF_READ)
87 return false;
88 if (off % size != 0)
89 return false;
90
91 if (!btf_ctx_access(off, size, type, prog, info))
92 return false;
93
94 if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id)
95 /* promote it to tcp_sock */
96 info->btf_id = tcp_sock_id;
97
98 return true;
99 }
100
bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log * log,const struct btf * btf,const struct btf_type * t,int off,int size,enum bpf_access_type atype,u32 * next_btf_id)101 static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log,
102 const struct btf *btf,
103 const struct btf_type *t, int off,
104 int size, enum bpf_access_type atype,
105 u32 *next_btf_id)
106 {
107 size_t end;
108
109 if (atype == BPF_READ)
110 return btf_struct_access(log, btf, t, off, size, atype, next_btf_id);
111
112 if (t != tcp_sock_type) {
113 bpf_log(log, "only read is supported\n");
114 return -EACCES;
115 }
116
117 switch (off) {
118 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv):
119 end = offsetofend(struct inet_connection_sock, icsk_ca_priv);
120 break;
121 case offsetof(struct inet_connection_sock, icsk_ack.pending):
122 end = offsetofend(struct inet_connection_sock,
123 icsk_ack.pending);
124 break;
125 case offsetof(struct tcp_sock, snd_cwnd):
126 end = offsetofend(struct tcp_sock, snd_cwnd);
127 break;
128 case offsetof(struct tcp_sock, snd_cwnd_cnt):
129 end = offsetofend(struct tcp_sock, snd_cwnd_cnt);
130 break;
131 case offsetof(struct tcp_sock, snd_ssthresh):
132 end = offsetofend(struct tcp_sock, snd_ssthresh);
133 break;
134 case offsetof(struct tcp_sock, ecn_flags):
135 end = offsetofend(struct tcp_sock, ecn_flags);
136 break;
137 default:
138 bpf_log(log, "no write support to tcp_sock at off %d\n", off);
139 return -EACCES;
140 }
141
142 if (off + size > end) {
143 bpf_log(log,
144 "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n",
145 off, size, end);
146 return -EACCES;
147 }
148
149 return NOT_INIT;
150 }
151
BPF_CALL_2(bpf_tcp_send_ack,struct tcp_sock *,tp,u32,rcv_nxt)152 BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt)
153 {
154 /* bpf_tcp_ca prog cannot have NULL tp */
155 __tcp_send_ack((struct sock *)tp, rcv_nxt);
156 return 0;
157 }
158
159 static const struct bpf_func_proto bpf_tcp_send_ack_proto = {
160 .func = bpf_tcp_send_ack,
161 .gpl_only = false,
162 /* In case we want to report error later */
163 .ret_type = RET_INTEGER,
164 .arg1_type = ARG_PTR_TO_BTF_ID,
165 .arg1_btf_id = &tcp_sock_id,
166 .arg2_type = ARG_ANYTHING,
167 };
168
prog_ops_moff(const struct bpf_prog * prog)169 static u32 prog_ops_moff(const struct bpf_prog *prog)
170 {
171 const struct btf_member *m;
172 const struct btf_type *t;
173 u32 midx;
174
175 midx = prog->expected_attach_type;
176 t = bpf_tcp_congestion_ops.type;
177 m = &btf_type_member(t)[midx];
178
179 return btf_member_bit_offset(t, m) / 8;
180 }
181
182 static const struct bpf_func_proto *
bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,const struct bpf_prog * prog)183 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id,
184 const struct bpf_prog *prog)
185 {
186 switch (func_id) {
187 case BPF_FUNC_tcp_send_ack:
188 return &bpf_tcp_send_ack_proto;
189 case BPF_FUNC_sk_storage_get:
190 return &bpf_sk_storage_get_proto;
191 case BPF_FUNC_sk_storage_delete:
192 return &bpf_sk_storage_delete_proto;
193 case BPF_FUNC_setsockopt:
194 /* Does not allow release() to call setsockopt.
195 * release() is called when the current bpf-tcp-cc
196 * is retiring. It is not allowed to call
197 * setsockopt() to make further changes which
198 * may potentially allocate new resources.
199 */
200 if (prog_ops_moff(prog) !=
201 offsetof(struct tcp_congestion_ops, release))
202 return &bpf_sk_setsockopt_proto;
203 return NULL;
204 case BPF_FUNC_getsockopt:
205 /* Since get/setsockopt is usually expected to
206 * be available together, disable getsockopt for
207 * release also to avoid usage surprise.
208 * The bpf-tcp-cc already has a more powerful way
209 * to read tcp_sock from the PTR_TO_BTF_ID.
210 */
211 if (prog_ops_moff(prog) !=
212 offsetof(struct tcp_congestion_ops, release))
213 return &bpf_sk_getsockopt_proto;
214 return NULL;
215 case BPF_FUNC_ktime_get_coarse_ns:
216 return &bpf_ktime_get_coarse_ns_proto;
217 default:
218 return bpf_base_func_proto(func_id);
219 }
220 }
221
222 BTF_SET_START(bpf_tcp_ca_kfunc_ids)
BTF_ID(func,tcp_reno_ssthresh)223 BTF_ID(func, tcp_reno_ssthresh)
224 BTF_ID(func, tcp_reno_cong_avoid)
225 BTF_ID(func, tcp_reno_undo_cwnd)
226 BTF_ID(func, tcp_slow_start)
227 BTF_ID(func, tcp_cong_avoid_ai)
228 #ifdef CONFIG_X86
229 #ifdef CONFIG_DYNAMIC_FTRACE
230 #if IS_BUILTIN(CONFIG_TCP_CONG_CUBIC)
231 BTF_ID(func, cubictcp_init)
232 BTF_ID(func, cubictcp_recalc_ssthresh)
233 BTF_ID(func, cubictcp_cong_avoid)
234 BTF_ID(func, cubictcp_state)
235 BTF_ID(func, cubictcp_cwnd_event)
236 BTF_ID(func, cubictcp_acked)
237 #endif
238 #if IS_BUILTIN(CONFIG_TCP_CONG_DCTCP)
239 BTF_ID(func, dctcp_init)
240 BTF_ID(func, dctcp_update_alpha)
241 BTF_ID(func, dctcp_cwnd_event)
242 BTF_ID(func, dctcp_ssthresh)
243 BTF_ID(func, dctcp_cwnd_undo)
244 BTF_ID(func, dctcp_state)
245 #endif
246 #if IS_BUILTIN(CONFIG_TCP_CONG_BBR)
247 BTF_ID(func, bbr_init)
248 BTF_ID(func, bbr_main)
249 BTF_ID(func, bbr_sndbuf_expand)
250 BTF_ID(func, bbr_undo_cwnd)
251 BTF_ID(func, bbr_cwnd_event)
252 BTF_ID(func, bbr_ssthresh)
253 BTF_ID(func, bbr_min_tso_segs)
254 BTF_ID(func, bbr_set_state)
255 #endif
256 #endif /* CONFIG_DYNAMIC_FTRACE */
257 #endif /* CONFIG_X86 */
258 BTF_SET_END(bpf_tcp_ca_kfunc_ids)
259
260 static bool bpf_tcp_ca_check_kfunc_call(u32 kfunc_btf_id)
261 {
262 return btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id);
263 }
264
265 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = {
266 .get_func_proto = bpf_tcp_ca_get_func_proto,
267 .is_valid_access = bpf_tcp_ca_is_valid_access,
268 .btf_struct_access = bpf_tcp_ca_btf_struct_access,
269 .check_kfunc_call = bpf_tcp_ca_check_kfunc_call,
270 };
271
bpf_tcp_ca_init_member(const struct btf_type * t,const struct btf_member * member,void * kdata,const void * udata)272 static int bpf_tcp_ca_init_member(const struct btf_type *t,
273 const struct btf_member *member,
274 void *kdata, const void *udata)
275 {
276 const struct tcp_congestion_ops *utcp_ca;
277 struct tcp_congestion_ops *tcp_ca;
278 int prog_fd;
279 u32 moff;
280
281 utcp_ca = (const struct tcp_congestion_ops *)udata;
282 tcp_ca = (struct tcp_congestion_ops *)kdata;
283
284 moff = btf_member_bit_offset(t, member) / 8;
285 switch (moff) {
286 case offsetof(struct tcp_congestion_ops, flags):
287 if (utcp_ca->flags & ~TCP_CONG_MASK)
288 return -EINVAL;
289 tcp_ca->flags = utcp_ca->flags;
290 return 1;
291 case offsetof(struct tcp_congestion_ops, name):
292 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name,
293 sizeof(tcp_ca->name)) <= 0)
294 return -EINVAL;
295 if (tcp_ca_find(utcp_ca->name))
296 return -EEXIST;
297 return 1;
298 }
299
300 if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL))
301 return 0;
302
303 /* Ensure bpf_prog is provided for compulsory func ptr */
304 prog_fd = (int)(*(unsigned long *)(udata + moff));
305 if (!prog_fd && !is_optional(moff) && !is_unsupported(moff))
306 return -EINVAL;
307
308 return 0;
309 }
310
bpf_tcp_ca_check_member(const struct btf_type * t,const struct btf_member * member)311 static int bpf_tcp_ca_check_member(const struct btf_type *t,
312 const struct btf_member *member)
313 {
314 if (is_unsupported(btf_member_bit_offset(t, member) / 8))
315 return -ENOTSUPP;
316 return 0;
317 }
318
bpf_tcp_ca_reg(void * kdata)319 static int bpf_tcp_ca_reg(void *kdata)
320 {
321 return tcp_register_congestion_control(kdata);
322 }
323
bpf_tcp_ca_unreg(void * kdata)324 static void bpf_tcp_ca_unreg(void *kdata)
325 {
326 tcp_unregister_congestion_control(kdata);
327 }
328
329 struct bpf_struct_ops bpf_tcp_congestion_ops = {
330 .verifier_ops = &bpf_tcp_ca_verifier_ops,
331 .reg = bpf_tcp_ca_reg,
332 .unreg = bpf_tcp_ca_unreg,
333 .check_member = bpf_tcp_ca_check_member,
334 .init_member = bpf_tcp_ca_init_member,
335 .init = bpf_tcp_ca_init,
336 .name = "tcp_congestion_ops",
337 };
338