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