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 (!bpf_tracing_btf_ctx_access(off, size, type, prog, info)) 85 return false; 86 87 if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id) 88 /* promote it to tcp_sock */ 89 info->btf_id = tcp_sock_id; 90 91 return true; 92 } 93 94 static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, 95 const struct btf *btf, 96 const struct btf_type *t, int off, 97 int size, enum bpf_access_type atype, 98 u32 *next_btf_id) 99 { 100 size_t end; 101 102 if (atype == BPF_READ) 103 return btf_struct_access(log, btf, t, off, size, atype, next_btf_id); 104 105 if (t != tcp_sock_type) { 106 bpf_log(log, "only read is supported\n"); 107 return -EACCES; 108 } 109 110 switch (off) { 111 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): 112 end = offsetofend(struct inet_connection_sock, icsk_ca_priv); 113 break; 114 case offsetof(struct inet_connection_sock, icsk_ack.pending): 115 end = offsetofend(struct inet_connection_sock, 116 icsk_ack.pending); 117 break; 118 case offsetof(struct tcp_sock, snd_cwnd): 119 end = offsetofend(struct tcp_sock, snd_cwnd); 120 break; 121 case offsetof(struct tcp_sock, snd_cwnd_cnt): 122 end = offsetofend(struct tcp_sock, snd_cwnd_cnt); 123 break; 124 case offsetof(struct tcp_sock, snd_ssthresh): 125 end = offsetofend(struct tcp_sock, snd_ssthresh); 126 break; 127 case offsetof(struct tcp_sock, ecn_flags): 128 end = offsetofend(struct tcp_sock, ecn_flags); 129 break; 130 default: 131 bpf_log(log, "no write support to tcp_sock at off %d\n", off); 132 return -EACCES; 133 } 134 135 if (off + size > end) { 136 bpf_log(log, 137 "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", 138 off, size, end); 139 return -EACCES; 140 } 141 142 return NOT_INIT; 143 } 144 145 BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) 146 { 147 /* bpf_tcp_ca prog cannot have NULL tp */ 148 __tcp_send_ack((struct sock *)tp, rcv_nxt); 149 return 0; 150 } 151 152 static const struct bpf_func_proto bpf_tcp_send_ack_proto = { 153 .func = bpf_tcp_send_ack, 154 .gpl_only = false, 155 /* In case we want to report error later */ 156 .ret_type = RET_INTEGER, 157 .arg1_type = ARG_PTR_TO_BTF_ID, 158 .arg1_btf_id = &tcp_sock_id, 159 .arg2_type = ARG_ANYTHING, 160 }; 161 162 static u32 prog_ops_moff(const struct bpf_prog *prog) 163 { 164 const struct btf_member *m; 165 const struct btf_type *t; 166 u32 midx; 167 168 midx = prog->expected_attach_type; 169 t = bpf_tcp_congestion_ops.type; 170 m = &btf_type_member(t)[midx]; 171 172 return btf_member_bit_offset(t, m) / 8; 173 } 174 175 static const struct bpf_func_proto * 176 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, 177 const struct bpf_prog *prog) 178 { 179 switch (func_id) { 180 case BPF_FUNC_tcp_send_ack: 181 return &bpf_tcp_send_ack_proto; 182 case BPF_FUNC_sk_storage_get: 183 return &bpf_sk_storage_get_proto; 184 case BPF_FUNC_sk_storage_delete: 185 return &bpf_sk_storage_delete_proto; 186 case BPF_FUNC_setsockopt: 187 /* Does not allow release() to call setsockopt. 188 * release() is called when the current bpf-tcp-cc 189 * is retiring. It is not allowed to call 190 * setsockopt() to make further changes which 191 * may potentially allocate new resources. 192 */ 193 if (prog_ops_moff(prog) != 194 offsetof(struct tcp_congestion_ops, release)) 195 return &bpf_sk_setsockopt_proto; 196 return NULL; 197 case BPF_FUNC_getsockopt: 198 /* Since get/setsockopt is usually expected to 199 * be available together, disable getsockopt for 200 * release also to avoid usage surprise. 201 * The bpf-tcp-cc already has a more powerful way 202 * to read tcp_sock from the PTR_TO_BTF_ID. 203 */ 204 if (prog_ops_moff(prog) != 205 offsetof(struct tcp_congestion_ops, release)) 206 return &bpf_sk_getsockopt_proto; 207 return NULL; 208 case BPF_FUNC_ktime_get_coarse_ns: 209 return &bpf_ktime_get_coarse_ns_proto; 210 default: 211 return bpf_base_func_proto(func_id); 212 } 213 } 214 215 BTF_SET_START(bpf_tcp_ca_kfunc_ids) 216 BTF_ID(func, tcp_reno_ssthresh) 217 BTF_ID(func, tcp_reno_cong_avoid) 218 BTF_ID(func, tcp_reno_undo_cwnd) 219 BTF_ID(func, tcp_slow_start) 220 BTF_ID(func, tcp_cong_avoid_ai) 221 BTF_SET_END(bpf_tcp_ca_kfunc_ids) 222 223 static bool bpf_tcp_ca_check_kfunc_call(u32 kfunc_btf_id, struct module *owner) 224 { 225 if (btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id)) 226 return true; 227 return bpf_check_mod_kfunc_call(&bpf_tcp_ca_kfunc_list, kfunc_btf_id, owner); 228 } 229 230 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 231 .get_func_proto = bpf_tcp_ca_get_func_proto, 232 .is_valid_access = bpf_tcp_ca_is_valid_access, 233 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 234 .check_kfunc_call = bpf_tcp_ca_check_kfunc_call, 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