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 extern struct bpf_struct_ops bpf_tcp_congestion_ops; 16 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 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 { 61 if (!bpf_tracing_btf_ctx_access(off, size, type, prog, info)) 62 return false; 63 64 if (base_type(info->reg_type) == PTR_TO_BTF_ID && 65 !bpf_type_has_unsafe_modifiers(info->reg_type) && 66 info->btf_id == sock_id) 67 /* promote it to tcp_sock */ 68 info->btf_id = tcp_sock_id; 69 70 return true; 71 } 72 73 static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, 74 const struct bpf_reg_state *reg, 75 int off, int size) 76 { 77 const struct btf_type *t; 78 size_t end; 79 80 t = btf_type_by_id(reg->btf, reg->btf_id); 81 if (t != tcp_sock_type) { 82 bpf_log(log, "only read is supported\n"); 83 return -EACCES; 84 } 85 86 switch (off) { 87 case offsetof(struct sock, sk_pacing_rate): 88 end = offsetofend(struct sock, sk_pacing_rate); 89 break; 90 case offsetof(struct sock, sk_pacing_status): 91 end = offsetofend(struct sock, sk_pacing_status); 92 break; 93 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): 94 end = offsetofend(struct inet_connection_sock, icsk_ca_priv); 95 break; 96 case offsetof(struct inet_connection_sock, icsk_ack.pending): 97 end = offsetofend(struct inet_connection_sock, 98 icsk_ack.pending); 99 break; 100 case offsetof(struct tcp_sock, snd_cwnd): 101 end = offsetofend(struct tcp_sock, snd_cwnd); 102 break; 103 case offsetof(struct tcp_sock, snd_cwnd_cnt): 104 end = offsetofend(struct tcp_sock, snd_cwnd_cnt); 105 break; 106 case offsetof(struct tcp_sock, snd_ssthresh): 107 end = offsetofend(struct tcp_sock, snd_ssthresh); 108 break; 109 case offsetof(struct tcp_sock, ecn_flags): 110 end = offsetofend(struct tcp_sock, ecn_flags); 111 break; 112 case offsetof(struct tcp_sock, app_limited): 113 end = offsetofend(struct tcp_sock, app_limited); 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 0; 128 } 129 130 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, 143 .arg1_btf_id = &tcp_sock_id, 144 .arg2_type = ARG_ANYTHING, 145 }; 146 147 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]; 156 157 return __btf_member_bit_offset(t, m) / 8; 158 } 159 160 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 { 164 switch (func_id) { 165 case BPF_FUNC_tcp_send_ack: 166 return &bpf_tcp_send_ack_proto; 167 case BPF_FUNC_sk_storage_get: 168 return &bpf_sk_storage_get_proto; 169 case BPF_FUNC_sk_storage_delete: 170 return &bpf_sk_storage_delete_proto; 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; 193 case BPF_FUNC_ktime_get_coarse_ns: 194 return &bpf_ktime_get_coarse_ns_proto; 195 default: 196 return bpf_base_func_proto(func_id); 197 } 198 } 199 200 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) 207 208 static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = { 209 .owner = THIS_MODULE, 210 .set = &bpf_tcp_ca_check_kfunc_ids, 211 }; 212 213 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; 225 u32 moff; 226 227 utcp_ca = (const struct tcp_congestion_ops *)udata; 228 tcp_ca = (struct tcp_congestion_ops *)kdata; 229 230 moff = __btf_member_bit_offset(t, member) / 8; 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): 238 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 239 sizeof(tcp_ca->name)) <= 0) 240 return -EINVAL; 241 return 1; 242 } 243 244 return 0; 245 } 246 247 static int bpf_tcp_ca_check_member(const struct btf_type *t, 248 const struct btf_member *member, 249 const struct bpf_prog *prog) 250 { 251 if (is_unsupported(__btf_member_bit_offset(t, member) / 8)) 252 return -ENOTSUPP; 253 return 0; 254 } 255 256 static int bpf_tcp_ca_reg(void *kdata) 257 { 258 return tcp_register_congestion_control(kdata); 259 } 260 261 static void bpf_tcp_ca_unreg(void *kdata) 262 { 263 tcp_unregister_congestion_control(kdata); 264 } 265 266 static int bpf_tcp_ca_update(void *kdata, void *old_kdata) 267 { 268 return tcp_update_congestion_control(kdata, old_kdata); 269 } 270 271 static int bpf_tcp_ca_validate(void *kdata) 272 { 273 return tcp_validate_congestion_control(kdata); 274 } 275 276 struct bpf_struct_ops bpf_tcp_congestion_ops = { 277 .verifier_ops = &bpf_tcp_ca_verifier_ops, 278 .reg = bpf_tcp_ca_reg, 279 .unreg = bpf_tcp_ca_unreg, 280 .update = bpf_tcp_ca_update, 281 .check_member = bpf_tcp_ca_check_member, 282 .init_member = bpf_tcp_ca_init_member, 283 .init = bpf_tcp_ca_init, 284 .validate = bpf_tcp_ca_validate, 285 .name = "tcp_congestion_ops", 286 }; 287 288 static int __init bpf_tcp_ca_kfunc_init(void) 289 { 290 return register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set); 291 } 292 late_initcall(bpf_tcp_ca_kfunc_init); 293