1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2019 Facebook */ 3 4 #include <linux/init.h> 5 #include <linux/types.h> 6 #include <linux/bpf_verifier.h> 7 #include <linux/bpf.h> 8 #include <linux/btf.h> 9 #include <linux/btf_ids.h> 10 #include <linux/filter.h> 11 #include <net/tcp.h> 12 #include <net/bpf_sk_storage.h> 13 14 /* "extern" is to avoid sparse warning. It is only used in bpf_struct_ops.c. */ 15 static struct bpf_struct_ops bpf_tcp_congestion_ops; 16 17 static const struct btf_type *tcp_sock_type; 18 static u32 tcp_sock_id, sock_id; 19 static const struct btf_type *tcp_congestion_ops_type; 20 21 static int bpf_tcp_ca_init(struct btf *btf) 22 { 23 s32 type_id; 24 25 type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); 26 if (type_id < 0) 27 return -EINVAL; 28 sock_id = type_id; 29 30 type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); 31 if (type_id < 0) 32 return -EINVAL; 33 tcp_sock_id = type_id; 34 tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); 35 36 type_id = btf_find_by_name_kind(btf, "tcp_congestion_ops", BTF_KIND_STRUCT); 37 if (type_id < 0) 38 return -EINVAL; 39 tcp_congestion_ops_type = btf_type_by_id(btf, type_id); 40 41 return 0; 42 } 43 44 static bool bpf_tcp_ca_is_valid_access(int off, int size, 45 enum bpf_access_type type, 46 const struct bpf_prog *prog, 47 struct bpf_insn_access_aux *info) 48 { 49 if (!bpf_tracing_btf_ctx_access(off, size, type, prog, info)) 50 return false; 51 52 if (base_type(info->reg_type) == PTR_TO_BTF_ID && 53 !bpf_type_has_unsafe_modifiers(info->reg_type) && 54 info->btf_id == sock_id) 55 /* promote it to tcp_sock */ 56 info->btf_id = tcp_sock_id; 57 58 return true; 59 } 60 61 static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, 62 const struct bpf_reg_state *reg, 63 int off, int size) 64 { 65 const struct btf_type *t; 66 size_t end; 67 68 t = btf_type_by_id(reg->btf, reg->btf_id); 69 if (t != tcp_sock_type) { 70 bpf_log(log, "only read is supported\n"); 71 return -EACCES; 72 } 73 74 switch (off) { 75 case offsetof(struct sock, sk_pacing_rate): 76 end = offsetofend(struct sock, sk_pacing_rate); 77 break; 78 case offsetof(struct sock, sk_pacing_status): 79 end = offsetofend(struct sock, sk_pacing_status); 80 break; 81 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): 82 end = offsetofend(struct inet_connection_sock, icsk_ca_priv); 83 break; 84 case offsetof(struct inet_connection_sock, icsk_ack.pending): 85 end = offsetofend(struct inet_connection_sock, 86 icsk_ack.pending); 87 break; 88 case offsetof(struct tcp_sock, snd_cwnd): 89 end = offsetofend(struct tcp_sock, snd_cwnd); 90 break; 91 case offsetof(struct tcp_sock, snd_cwnd_cnt): 92 end = offsetofend(struct tcp_sock, snd_cwnd_cnt); 93 break; 94 case offsetof(struct tcp_sock, snd_cwnd_stamp): 95 end = offsetofend(struct tcp_sock, snd_cwnd_stamp); 96 break; 97 case offsetof(struct tcp_sock, snd_ssthresh): 98 end = offsetofend(struct tcp_sock, snd_ssthresh); 99 break; 100 case offsetof(struct tcp_sock, ecn_flags): 101 end = offsetofend(struct tcp_sock, ecn_flags); 102 break; 103 case offsetof(struct tcp_sock, app_limited): 104 end = offsetofend(struct tcp_sock, app_limited); 105 break; 106 default: 107 bpf_log(log, "no write support to tcp_sock at off %d\n", off); 108 return -EACCES; 109 } 110 111 if (off + size > end) { 112 bpf_log(log, 113 "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", 114 off, size, end); 115 return -EACCES; 116 } 117 118 return 0; 119 } 120 121 BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) 122 { 123 /* bpf_tcp_ca prog cannot have NULL tp */ 124 __tcp_send_ack((struct sock *)tp, rcv_nxt); 125 return 0; 126 } 127 128 static const struct bpf_func_proto bpf_tcp_send_ack_proto = { 129 .func = bpf_tcp_send_ack, 130 .gpl_only = false, 131 /* In case we want to report error later */ 132 .ret_type = RET_INTEGER, 133 .arg1_type = ARG_PTR_TO_BTF_ID, 134 .arg1_btf_id = &tcp_sock_id, 135 .arg2_type = ARG_ANYTHING, 136 }; 137 138 static u32 prog_ops_moff(const struct bpf_prog *prog) 139 { 140 const struct btf_member *m; 141 const struct btf_type *t; 142 u32 midx; 143 144 midx = prog->expected_attach_type; 145 t = tcp_congestion_ops_type; 146 m = &btf_type_member(t)[midx]; 147 148 return __btf_member_bit_offset(t, m) / 8; 149 } 150 151 static const struct bpf_func_proto * 152 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, 153 const struct bpf_prog *prog) 154 { 155 switch (func_id) { 156 case BPF_FUNC_tcp_send_ack: 157 return &bpf_tcp_send_ack_proto; 158 case BPF_FUNC_sk_storage_get: 159 return &bpf_sk_storage_get_proto; 160 case BPF_FUNC_sk_storage_delete: 161 return &bpf_sk_storage_delete_proto; 162 case BPF_FUNC_setsockopt: 163 /* Does not allow release() to call setsockopt. 164 * release() is called when the current bpf-tcp-cc 165 * is retiring. It is not allowed to call 166 * setsockopt() to make further changes which 167 * may potentially allocate new resources. 168 */ 169 if (prog_ops_moff(prog) != 170 offsetof(struct tcp_congestion_ops, release)) 171 return &bpf_sk_setsockopt_proto; 172 return NULL; 173 case BPF_FUNC_getsockopt: 174 /* Since get/setsockopt is usually expected to 175 * be available together, disable getsockopt for 176 * release also to avoid usage surprise. 177 * The bpf-tcp-cc already has a more powerful way 178 * to read tcp_sock from the PTR_TO_BTF_ID. 179 */ 180 if (prog_ops_moff(prog) != 181 offsetof(struct tcp_congestion_ops, release)) 182 return &bpf_sk_getsockopt_proto; 183 return NULL; 184 case BPF_FUNC_ktime_get_coarse_ns: 185 return &bpf_ktime_get_coarse_ns_proto; 186 default: 187 return bpf_base_func_proto(func_id, prog); 188 } 189 } 190 191 BTF_KFUNCS_START(bpf_tcp_ca_check_kfunc_ids) 192 BTF_ID_FLAGS(func, tcp_reno_ssthresh) 193 BTF_ID_FLAGS(func, tcp_reno_cong_avoid) 194 BTF_ID_FLAGS(func, tcp_reno_undo_cwnd) 195 BTF_ID_FLAGS(func, tcp_slow_start) 196 BTF_ID_FLAGS(func, tcp_cong_avoid_ai) 197 BTF_KFUNCS_END(bpf_tcp_ca_check_kfunc_ids) 198 199 static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = { 200 .owner = THIS_MODULE, 201 .set = &bpf_tcp_ca_check_kfunc_ids, 202 }; 203 204 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 205 .get_func_proto = bpf_tcp_ca_get_func_proto, 206 .is_valid_access = bpf_tcp_ca_is_valid_access, 207 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 208 }; 209 210 static int bpf_tcp_ca_init_member(const struct btf_type *t, 211 const struct btf_member *member, 212 void *kdata, const void *udata) 213 { 214 const struct tcp_congestion_ops *utcp_ca; 215 struct tcp_congestion_ops *tcp_ca; 216 u32 moff; 217 218 utcp_ca = (const struct tcp_congestion_ops *)udata; 219 tcp_ca = (struct tcp_congestion_ops *)kdata; 220 221 moff = __btf_member_bit_offset(t, member) / 8; 222 switch (moff) { 223 case offsetof(struct tcp_congestion_ops, flags): 224 if (utcp_ca->flags & ~TCP_CONG_MASK) 225 return -EINVAL; 226 tcp_ca->flags = utcp_ca->flags; 227 return 1; 228 case offsetof(struct tcp_congestion_ops, name): 229 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 230 sizeof(tcp_ca->name)) <= 0) 231 return -EINVAL; 232 return 1; 233 } 234 235 return 0; 236 } 237 238 static int bpf_tcp_ca_reg(void *kdata, struct bpf_link *link) 239 { 240 return tcp_register_congestion_control(kdata); 241 } 242 243 static void bpf_tcp_ca_unreg(void *kdata, struct bpf_link *link) 244 { 245 tcp_unregister_congestion_control(kdata); 246 } 247 248 static int bpf_tcp_ca_update(void *kdata, void *old_kdata, struct bpf_link *link) 249 { 250 return tcp_update_congestion_control(kdata, old_kdata); 251 } 252 253 static int bpf_tcp_ca_validate(void *kdata) 254 { 255 return tcp_validate_congestion_control(kdata); 256 } 257 258 static u32 bpf_tcp_ca_ssthresh(struct sock *sk) 259 { 260 return 0; 261 } 262 263 static void bpf_tcp_ca_cong_avoid(struct sock *sk, u32 ack, u32 acked) 264 { 265 } 266 267 static void bpf_tcp_ca_set_state(struct sock *sk, u8 new_state) 268 { 269 } 270 271 static void bpf_tcp_ca_cwnd_event(struct sock *sk, enum tcp_ca_event ev) 272 { 273 } 274 275 static void bpf_tcp_ca_in_ack_event(struct sock *sk, u32 flags) 276 { 277 } 278 279 static void bpf_tcp_ca_pkts_acked(struct sock *sk, const struct ack_sample *sample) 280 { 281 } 282 283 static u32 bpf_tcp_ca_min_tso_segs(struct sock *sk) 284 { 285 return 0; 286 } 287 288 static void bpf_tcp_ca_cong_control(struct sock *sk, u32 ack, int flag, 289 const struct rate_sample *rs) 290 { 291 } 292 293 static u32 bpf_tcp_ca_undo_cwnd(struct sock *sk) 294 { 295 return 0; 296 } 297 298 static u32 bpf_tcp_ca_sndbuf_expand(struct sock *sk) 299 { 300 return 0; 301 } 302 303 static void __bpf_tcp_ca_init(struct sock *sk) 304 { 305 } 306 307 static void __bpf_tcp_ca_release(struct sock *sk) 308 { 309 } 310 311 static struct tcp_congestion_ops __bpf_ops_tcp_congestion_ops = { 312 .ssthresh = bpf_tcp_ca_ssthresh, 313 .cong_avoid = bpf_tcp_ca_cong_avoid, 314 .set_state = bpf_tcp_ca_set_state, 315 .cwnd_event = bpf_tcp_ca_cwnd_event, 316 .in_ack_event = bpf_tcp_ca_in_ack_event, 317 .pkts_acked = bpf_tcp_ca_pkts_acked, 318 .min_tso_segs = bpf_tcp_ca_min_tso_segs, 319 .cong_control = bpf_tcp_ca_cong_control, 320 .undo_cwnd = bpf_tcp_ca_undo_cwnd, 321 .sndbuf_expand = bpf_tcp_ca_sndbuf_expand, 322 323 .init = __bpf_tcp_ca_init, 324 .release = __bpf_tcp_ca_release, 325 }; 326 327 static struct bpf_struct_ops bpf_tcp_congestion_ops = { 328 .verifier_ops = &bpf_tcp_ca_verifier_ops, 329 .reg = bpf_tcp_ca_reg, 330 .unreg = bpf_tcp_ca_unreg, 331 .update = bpf_tcp_ca_update, 332 .init_member = bpf_tcp_ca_init_member, 333 .init = bpf_tcp_ca_init, 334 .validate = bpf_tcp_ca_validate, 335 .name = "tcp_congestion_ops", 336 .cfi_stubs = &__bpf_ops_tcp_congestion_ops, 337 .owner = THIS_MODULE, 338 }; 339 340 static int __init bpf_tcp_ca_kfunc_init(void) 341 { 342 int ret; 343 344 ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set); 345 ret = ret ?: register_bpf_struct_ops(&bpf_tcp_congestion_ops, tcp_congestion_ops); 346 347 return ret; 348 } 349 late_initcall(bpf_tcp_ca_kfunc_init); 350