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 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 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 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 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 } 100 101 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 } 151 152 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 }; 168 169 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 * 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 default: 216 return bpf_base_func_proto(func_id); 217 } 218 } 219 220 BTF_SET_START(bpf_tcp_ca_kfunc_ids) 221 BTF_ID(func, tcp_reno_ssthresh) 222 BTF_ID(func, tcp_reno_cong_avoid) 223 BTF_ID(func, tcp_reno_undo_cwnd) 224 BTF_ID(func, tcp_slow_start) 225 BTF_ID(func, tcp_cong_avoid_ai) 226 #ifdef CONFIG_X86 227 #ifdef CONFIG_DYNAMIC_FTRACE 228 #if IS_BUILTIN(CONFIG_TCP_CONG_CUBIC) 229 BTF_ID(func, cubictcp_init) 230 BTF_ID(func, cubictcp_recalc_ssthresh) 231 BTF_ID(func, cubictcp_cong_avoid) 232 BTF_ID(func, cubictcp_state) 233 BTF_ID(func, cubictcp_cwnd_event) 234 BTF_ID(func, cubictcp_acked) 235 #endif 236 #if IS_BUILTIN(CONFIG_TCP_CONG_DCTCP) 237 BTF_ID(func, dctcp_init) 238 BTF_ID(func, dctcp_update_alpha) 239 BTF_ID(func, dctcp_cwnd_event) 240 BTF_ID(func, dctcp_ssthresh) 241 BTF_ID(func, dctcp_cwnd_undo) 242 BTF_ID(func, dctcp_state) 243 #endif 244 #if IS_BUILTIN(CONFIG_TCP_CONG_BBR) 245 BTF_ID(func, bbr_init) 246 BTF_ID(func, bbr_main) 247 BTF_ID(func, bbr_sndbuf_expand) 248 BTF_ID(func, bbr_undo_cwnd) 249 BTF_ID(func, bbr_cwnd_event) 250 BTF_ID(func, bbr_ssthresh) 251 BTF_ID(func, bbr_min_tso_segs) 252 BTF_ID(func, bbr_set_state) 253 #endif 254 #endif /* CONFIG_DYNAMIC_FTRACE */ 255 #endif /* CONFIG_X86 */ 256 BTF_SET_END(bpf_tcp_ca_kfunc_ids) 257 258 static bool bpf_tcp_ca_check_kfunc_call(u32 kfunc_btf_id) 259 { 260 return btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id); 261 } 262 263 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 264 .get_func_proto = bpf_tcp_ca_get_func_proto, 265 .is_valid_access = bpf_tcp_ca_is_valid_access, 266 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 267 .check_kfunc_call = bpf_tcp_ca_check_kfunc_call, 268 }; 269 270 static int bpf_tcp_ca_init_member(const struct btf_type *t, 271 const struct btf_member *member, 272 void *kdata, const void *udata) 273 { 274 const struct tcp_congestion_ops *utcp_ca; 275 struct tcp_congestion_ops *tcp_ca; 276 int prog_fd; 277 u32 moff; 278 279 utcp_ca = (const struct tcp_congestion_ops *)udata; 280 tcp_ca = (struct tcp_congestion_ops *)kdata; 281 282 moff = btf_member_bit_offset(t, member) / 8; 283 switch (moff) { 284 case offsetof(struct tcp_congestion_ops, flags): 285 if (utcp_ca->flags & ~TCP_CONG_MASK) 286 return -EINVAL; 287 tcp_ca->flags = utcp_ca->flags; 288 return 1; 289 case offsetof(struct tcp_congestion_ops, name): 290 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 291 sizeof(tcp_ca->name)) <= 0) 292 return -EINVAL; 293 if (tcp_ca_find(utcp_ca->name)) 294 return -EEXIST; 295 return 1; 296 } 297 298 if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL)) 299 return 0; 300 301 /* Ensure bpf_prog is provided for compulsory func ptr */ 302 prog_fd = (int)(*(unsigned long *)(udata + moff)); 303 if (!prog_fd && !is_optional(moff) && !is_unsupported(moff)) 304 return -EINVAL; 305 306 return 0; 307 } 308 309 static int bpf_tcp_ca_check_member(const struct btf_type *t, 310 const struct btf_member *member) 311 { 312 if (is_unsupported(btf_member_bit_offset(t, member) / 8)) 313 return -ENOTSUPP; 314 return 0; 315 } 316 317 static int bpf_tcp_ca_reg(void *kdata) 318 { 319 return tcp_register_congestion_control(kdata); 320 } 321 322 static void bpf_tcp_ca_unreg(void *kdata) 323 { 324 tcp_unregister_congestion_control(kdata); 325 } 326 327 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 .check_member = bpf_tcp_ca_check_member, 332 .init_member = bpf_tcp_ca_init_member, 333 .init = bpf_tcp_ca_init, 334 .name = "tcp_congestion_ops", 335 }; 336