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 static u32 optional_ops[] = { 14 offsetof(struct tcp_congestion_ops, init), 15 offsetof(struct tcp_congestion_ops, release), 16 offsetof(struct tcp_congestion_ops, set_state), 17 offsetof(struct tcp_congestion_ops, cwnd_event), 18 offsetof(struct tcp_congestion_ops, in_ack_event), 19 offsetof(struct tcp_congestion_ops, pkts_acked), 20 offsetof(struct tcp_congestion_ops, min_tso_segs), 21 offsetof(struct tcp_congestion_ops, sndbuf_expand), 22 offsetof(struct tcp_congestion_ops, cong_control), 23 }; 24 25 static u32 unsupported_ops[] = { 26 offsetof(struct tcp_congestion_ops, get_info), 27 }; 28 29 static const struct btf_type *tcp_sock_type; 30 static u32 tcp_sock_id, sock_id; 31 32 static int bpf_tcp_ca_init(struct btf *btf) 33 { 34 s32 type_id; 35 36 type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); 37 if (type_id < 0) 38 return -EINVAL; 39 sock_id = type_id; 40 41 type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); 42 if (type_id < 0) 43 return -EINVAL; 44 tcp_sock_id = type_id; 45 tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); 46 47 return 0; 48 } 49 50 static bool is_optional(u32 member_offset) 51 { 52 unsigned int i; 53 54 for (i = 0; i < ARRAY_SIZE(optional_ops); i++) { 55 if (member_offset == optional_ops[i]) 56 return true; 57 } 58 59 return false; 60 } 61 62 static bool is_unsupported(u32 member_offset) 63 { 64 unsigned int i; 65 66 for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { 67 if (member_offset == unsupported_ops[i]) 68 return true; 69 } 70 71 return false; 72 } 73 74 extern struct btf *btf_vmlinux; 75 76 static bool bpf_tcp_ca_is_valid_access(int off, int size, 77 enum bpf_access_type type, 78 const struct bpf_prog *prog, 79 struct bpf_insn_access_aux *info) 80 { 81 if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS) 82 return false; 83 if (type != BPF_READ) 84 return false; 85 if (off % size != 0) 86 return false; 87 88 if (!btf_ctx_access(off, size, type, prog, info)) 89 return false; 90 91 if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id) 92 /* promote it to tcp_sock */ 93 info->btf_id = tcp_sock_id; 94 95 return true; 96 } 97 98 static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, 99 const struct btf *btf, 100 const struct btf_type *t, int off, 101 int size, enum bpf_access_type atype, 102 u32 *next_btf_id) 103 { 104 size_t end; 105 106 if (atype == BPF_READ) 107 return btf_struct_access(log, btf, t, off, size, atype, next_btf_id); 108 109 if (t != tcp_sock_type) { 110 bpf_log(log, "only read is supported\n"); 111 return -EACCES; 112 } 113 114 switch (off) { 115 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): 116 end = offsetofend(struct inet_connection_sock, icsk_ca_priv); 117 break; 118 case offsetof(struct inet_connection_sock, icsk_ack.pending): 119 end = offsetofend(struct inet_connection_sock, 120 icsk_ack.pending); 121 break; 122 case offsetof(struct tcp_sock, snd_cwnd): 123 end = offsetofend(struct tcp_sock, snd_cwnd); 124 break; 125 case offsetof(struct tcp_sock, snd_cwnd_cnt): 126 end = offsetofend(struct tcp_sock, snd_cwnd_cnt); 127 break; 128 case offsetof(struct tcp_sock, snd_ssthresh): 129 end = offsetofend(struct tcp_sock, snd_ssthresh); 130 break; 131 case offsetof(struct tcp_sock, ecn_flags): 132 end = offsetofend(struct tcp_sock, ecn_flags); 133 break; 134 default: 135 bpf_log(log, "no write support to tcp_sock at off %d\n", off); 136 return -EACCES; 137 } 138 139 if (off + size > end) { 140 bpf_log(log, 141 "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", 142 off, size, end); 143 return -EACCES; 144 } 145 146 return NOT_INIT; 147 } 148 149 BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) 150 { 151 /* bpf_tcp_ca prog cannot have NULL tp */ 152 __tcp_send_ack((struct sock *)tp, rcv_nxt); 153 return 0; 154 } 155 156 static const struct bpf_func_proto bpf_tcp_send_ack_proto = { 157 .func = bpf_tcp_send_ack, 158 .gpl_only = false, 159 /* In case we want to report error later */ 160 .ret_type = RET_INTEGER, 161 .arg1_type = ARG_PTR_TO_BTF_ID, 162 .arg1_btf_id = &tcp_sock_id, 163 .arg2_type = ARG_ANYTHING, 164 }; 165 166 static const struct bpf_func_proto * 167 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, 168 const struct bpf_prog *prog) 169 { 170 switch (func_id) { 171 case BPF_FUNC_tcp_send_ack: 172 return &bpf_tcp_send_ack_proto; 173 case BPF_FUNC_sk_storage_get: 174 return &bpf_sk_storage_get_proto; 175 case BPF_FUNC_sk_storage_delete: 176 return &bpf_sk_storage_delete_proto; 177 default: 178 return bpf_base_func_proto(func_id); 179 } 180 } 181 182 BTF_SET_START(bpf_tcp_ca_kfunc_ids) 183 BTF_ID(func, tcp_reno_ssthresh) 184 BTF_ID(func, tcp_reno_cong_avoid) 185 BTF_ID(func, tcp_reno_undo_cwnd) 186 BTF_ID(func, tcp_slow_start) 187 BTF_ID(func, tcp_cong_avoid_ai) 188 #ifdef CONFIG_DYNAMIC_FTRACE 189 #if IS_BUILTIN(CONFIG_TCP_CONG_CUBIC) 190 BTF_ID(func, cubictcp_init) 191 BTF_ID(func, cubictcp_recalc_ssthresh) 192 BTF_ID(func, cubictcp_cong_avoid) 193 BTF_ID(func, cubictcp_state) 194 BTF_ID(func, cubictcp_cwnd_event) 195 BTF_ID(func, cubictcp_acked) 196 #endif 197 #if IS_BUILTIN(CONFIG_TCP_CONG_DCTCP) 198 BTF_ID(func, dctcp_init) 199 BTF_ID(func, dctcp_update_alpha) 200 BTF_ID(func, dctcp_cwnd_event) 201 BTF_ID(func, dctcp_ssthresh) 202 BTF_ID(func, dctcp_cwnd_undo) 203 BTF_ID(func, dctcp_state) 204 #endif 205 #if IS_BUILTIN(CONFIG_TCP_CONG_BBR) 206 BTF_ID(func, bbr_init) 207 BTF_ID(func, bbr_main) 208 BTF_ID(func, bbr_sndbuf_expand) 209 BTF_ID(func, bbr_undo_cwnd) 210 BTF_ID(func, bbr_cwnd_event) 211 BTF_ID(func, bbr_ssthresh) 212 BTF_ID(func, bbr_min_tso_segs) 213 BTF_ID(func, bbr_set_state) 214 #endif 215 #endif /* CONFIG_DYNAMIC_FTRACE */ 216 BTF_SET_END(bpf_tcp_ca_kfunc_ids) 217 218 static bool bpf_tcp_ca_check_kfunc_call(u32 kfunc_btf_id) 219 { 220 return btf_id_set_contains(&bpf_tcp_ca_kfunc_ids, kfunc_btf_id); 221 } 222 223 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 224 .get_func_proto = bpf_tcp_ca_get_func_proto, 225 .is_valid_access = bpf_tcp_ca_is_valid_access, 226 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 227 .check_kfunc_call = bpf_tcp_ca_check_kfunc_call, 228 }; 229 230 static int bpf_tcp_ca_init_member(const struct btf_type *t, 231 const struct btf_member *member, 232 void *kdata, const void *udata) 233 { 234 const struct tcp_congestion_ops *utcp_ca; 235 struct tcp_congestion_ops *tcp_ca; 236 int prog_fd; 237 u32 moff; 238 239 utcp_ca = (const struct tcp_congestion_ops *)udata; 240 tcp_ca = (struct tcp_congestion_ops *)kdata; 241 242 moff = btf_member_bit_offset(t, member) / 8; 243 switch (moff) { 244 case offsetof(struct tcp_congestion_ops, flags): 245 if (utcp_ca->flags & ~TCP_CONG_MASK) 246 return -EINVAL; 247 tcp_ca->flags = utcp_ca->flags; 248 return 1; 249 case offsetof(struct tcp_congestion_ops, name): 250 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 251 sizeof(tcp_ca->name)) <= 0) 252 return -EINVAL; 253 if (tcp_ca_find(utcp_ca->name)) 254 return -EEXIST; 255 return 1; 256 } 257 258 if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL)) 259 return 0; 260 261 /* Ensure bpf_prog is provided for compulsory func ptr */ 262 prog_fd = (int)(*(unsigned long *)(udata + moff)); 263 if (!prog_fd && !is_optional(moff) && !is_unsupported(moff)) 264 return -EINVAL; 265 266 return 0; 267 } 268 269 static int bpf_tcp_ca_check_member(const struct btf_type *t, 270 const struct btf_member *member) 271 { 272 if (is_unsupported(btf_member_bit_offset(t, member) / 8)) 273 return -ENOTSUPP; 274 return 0; 275 } 276 277 static int bpf_tcp_ca_reg(void *kdata) 278 { 279 return tcp_register_congestion_control(kdata); 280 } 281 282 static void bpf_tcp_ca_unreg(void *kdata) 283 { 284 tcp_unregister_congestion_control(kdata); 285 } 286 287 /* Avoid sparse warning. It is only used in bpf_struct_ops.c. */ 288 extern struct bpf_struct_ops bpf_tcp_congestion_ops; 289 290 struct bpf_struct_ops bpf_tcp_congestion_ops = { 291 .verifier_ops = &bpf_tcp_ca_verifier_ops, 292 .reg = bpf_tcp_ca_reg, 293 .unreg = bpf_tcp_ca_unreg, 294 .check_member = bpf_tcp_ca_check_member, 295 .init_member = bpf_tcp_ca_init_member, 296 .init = bpf_tcp_ca_init, 297 .name = "tcp_congestion_ops", 298 }; 299