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/filter.h> 9 #include <net/tcp.h> 10 #include <net/bpf_sk_storage.h> 11 12 static u32 optional_ops[] = { 13 offsetof(struct tcp_congestion_ops, init), 14 offsetof(struct tcp_congestion_ops, release), 15 offsetof(struct tcp_congestion_ops, set_state), 16 offsetof(struct tcp_congestion_ops, cwnd_event), 17 offsetof(struct tcp_congestion_ops, in_ack_event), 18 offsetof(struct tcp_congestion_ops, pkts_acked), 19 offsetof(struct tcp_congestion_ops, min_tso_segs), 20 offsetof(struct tcp_congestion_ops, sndbuf_expand), 21 offsetof(struct tcp_congestion_ops, cong_control), 22 }; 23 24 static u32 unsupported_ops[] = { 25 offsetof(struct tcp_congestion_ops, get_info), 26 }; 27 28 static const struct btf_type *tcp_sock_type; 29 static u32 tcp_sock_id, sock_id; 30 31 static int bpf_tcp_ca_init(struct btf *btf) 32 { 33 s32 type_id; 34 35 type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); 36 if (type_id < 0) 37 return -EINVAL; 38 sock_id = type_id; 39 40 type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); 41 if (type_id < 0) 42 return -EINVAL; 43 tcp_sock_id = type_id; 44 tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); 45 46 return 0; 47 } 48 49 static bool is_optional(u32 member_offset) 50 { 51 unsigned int i; 52 53 for (i = 0; i < ARRAY_SIZE(optional_ops); i++) { 54 if (member_offset == optional_ops[i]) 55 return true; 56 } 57 58 return false; 59 } 60 61 static bool is_unsupported(u32 member_offset) 62 { 63 unsigned int i; 64 65 for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { 66 if (member_offset == unsupported_ops[i]) 67 return true; 68 } 69 70 return false; 71 } 72 73 extern struct btf *btf_vmlinux; 74 75 static bool bpf_tcp_ca_is_valid_access(int off, int size, 76 enum bpf_access_type type, 77 const struct bpf_prog *prog, 78 struct bpf_insn_access_aux *info) 79 { 80 if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS) 81 return false; 82 if (type != BPF_READ) 83 return false; 84 if (off % size != 0) 85 return false; 86 87 if (!btf_ctx_access(off, size, type, prog, info)) 88 return false; 89 90 if (info->reg_type == PTR_TO_BTF_ID && info->btf_id == sock_id) 91 /* promote it to tcp_sock */ 92 info->btf_id = tcp_sock_id; 93 94 return true; 95 } 96 97 static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, 98 const struct btf_type *t, int off, 99 int size, enum bpf_access_type atype, 100 u32 *next_btf_id) 101 { 102 size_t end; 103 104 if (atype == BPF_READ) 105 return btf_struct_access(log, t, off, size, atype, next_btf_id); 106 107 if (t != tcp_sock_type) { 108 bpf_log(log, "only read is supported\n"); 109 return -EACCES; 110 } 111 112 switch (off) { 113 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): 114 end = offsetofend(struct inet_connection_sock, icsk_ca_priv); 115 break; 116 case offsetof(struct inet_connection_sock, icsk_ack.pending): 117 end = offsetofend(struct inet_connection_sock, 118 icsk_ack.pending); 119 break; 120 case offsetof(struct tcp_sock, snd_cwnd): 121 end = offsetofend(struct tcp_sock, snd_cwnd); 122 break; 123 case offsetof(struct tcp_sock, snd_cwnd_cnt): 124 end = offsetofend(struct tcp_sock, snd_cwnd_cnt); 125 break; 126 case offsetof(struct tcp_sock, snd_ssthresh): 127 end = offsetofend(struct tcp_sock, snd_ssthresh); 128 break; 129 case offsetof(struct tcp_sock, ecn_flags): 130 end = offsetofend(struct tcp_sock, ecn_flags); 131 break; 132 default: 133 bpf_log(log, "no write support to tcp_sock at off %d\n", off); 134 return -EACCES; 135 } 136 137 if (off + size > end) { 138 bpf_log(log, 139 "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", 140 off, size, end); 141 return -EACCES; 142 } 143 144 return NOT_INIT; 145 } 146 147 BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) 148 { 149 /* bpf_tcp_ca prog cannot have NULL tp */ 150 __tcp_send_ack((struct sock *)tp, rcv_nxt); 151 return 0; 152 } 153 154 static const struct bpf_func_proto bpf_tcp_send_ack_proto = { 155 .func = bpf_tcp_send_ack, 156 .gpl_only = false, 157 /* In case we want to report error later */ 158 .ret_type = RET_INTEGER, 159 .arg1_type = ARG_PTR_TO_BTF_ID, 160 .arg1_btf_id = &tcp_sock_id, 161 .arg2_type = ARG_ANYTHING, 162 }; 163 164 static const struct bpf_func_proto * 165 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, 166 const struct bpf_prog *prog) 167 { 168 switch (func_id) { 169 case BPF_FUNC_tcp_send_ack: 170 return &bpf_tcp_send_ack_proto; 171 case BPF_FUNC_sk_storage_get: 172 return &bpf_sk_storage_get_proto; 173 case BPF_FUNC_sk_storage_delete: 174 return &bpf_sk_storage_delete_proto; 175 default: 176 return bpf_base_func_proto(func_id); 177 } 178 } 179 180 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 181 .get_func_proto = bpf_tcp_ca_get_func_proto, 182 .is_valid_access = bpf_tcp_ca_is_valid_access, 183 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 184 }; 185 186 static int bpf_tcp_ca_init_member(const struct btf_type *t, 187 const struct btf_member *member, 188 void *kdata, const void *udata) 189 { 190 const struct tcp_congestion_ops *utcp_ca; 191 struct tcp_congestion_ops *tcp_ca; 192 int prog_fd; 193 u32 moff; 194 195 utcp_ca = (const struct tcp_congestion_ops *)udata; 196 tcp_ca = (struct tcp_congestion_ops *)kdata; 197 198 moff = btf_member_bit_offset(t, member) / 8; 199 switch (moff) { 200 case offsetof(struct tcp_congestion_ops, flags): 201 if (utcp_ca->flags & ~TCP_CONG_MASK) 202 return -EINVAL; 203 tcp_ca->flags = utcp_ca->flags; 204 return 1; 205 case offsetof(struct tcp_congestion_ops, name): 206 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 207 sizeof(tcp_ca->name)) <= 0) 208 return -EINVAL; 209 if (tcp_ca_find(utcp_ca->name)) 210 return -EEXIST; 211 return 1; 212 } 213 214 if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL)) 215 return 0; 216 217 /* Ensure bpf_prog is provided for compulsory func ptr */ 218 prog_fd = (int)(*(unsigned long *)(udata + moff)); 219 if (!prog_fd && !is_optional(moff) && !is_unsupported(moff)) 220 return -EINVAL; 221 222 return 0; 223 } 224 225 static int bpf_tcp_ca_check_member(const struct btf_type *t, 226 const struct btf_member *member) 227 { 228 if (is_unsupported(btf_member_bit_offset(t, member) / 8)) 229 return -ENOTSUPP; 230 return 0; 231 } 232 233 static int bpf_tcp_ca_reg(void *kdata) 234 { 235 return tcp_register_congestion_control(kdata); 236 } 237 238 static void bpf_tcp_ca_unreg(void *kdata) 239 { 240 tcp_unregister_congestion_control(kdata); 241 } 242 243 /* Avoid sparse warning. It is only used in bpf_struct_ops.c. */ 244 extern struct bpf_struct_ops bpf_tcp_congestion_ops; 245 246 struct bpf_struct_ops bpf_tcp_congestion_ops = { 247 .verifier_ops = &bpf_tcp_ca_verifier_ops, 248 .reg = bpf_tcp_ca_reg, 249 .unreg = bpf_tcp_ca_unreg, 250 .check_member = bpf_tcp_ca_check_member, 251 .init_member = bpf_tcp_ca_init_member, 252 .init = bpf_tcp_ca_init, 253 .name = "tcp_congestion_ops", 254 }; 255