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 *btf, 99 const struct btf_type *t, int off, 100 int size, enum bpf_access_type atype, 101 u32 *next_btf_id) 102 { 103 size_t end; 104 105 if (atype == BPF_READ) 106 return btf_struct_access(log, btf, t, off, size, atype, next_btf_id); 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 const struct bpf_func_proto * 166 bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, 167 const struct bpf_prog *prog) 168 { 169 switch (func_id) { 170 case BPF_FUNC_tcp_send_ack: 171 return &bpf_tcp_send_ack_proto; 172 case BPF_FUNC_sk_storage_get: 173 return &bpf_sk_storage_get_proto; 174 case BPF_FUNC_sk_storage_delete: 175 return &bpf_sk_storage_delete_proto; 176 default: 177 return bpf_base_func_proto(func_id); 178 } 179 } 180 181 static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 182 .get_func_proto = bpf_tcp_ca_get_func_proto, 183 .is_valid_access = bpf_tcp_ca_is_valid_access, 184 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 185 }; 186 187 static int bpf_tcp_ca_init_member(const struct btf_type *t, 188 const struct btf_member *member, 189 void *kdata, const void *udata) 190 { 191 const struct tcp_congestion_ops *utcp_ca; 192 struct tcp_congestion_ops *tcp_ca; 193 int prog_fd; 194 u32 moff; 195 196 utcp_ca = (const struct tcp_congestion_ops *)udata; 197 tcp_ca = (struct tcp_congestion_ops *)kdata; 198 199 moff = btf_member_bit_offset(t, member) / 8; 200 switch (moff) { 201 case offsetof(struct tcp_congestion_ops, flags): 202 if (utcp_ca->flags & ~TCP_CONG_MASK) 203 return -EINVAL; 204 tcp_ca->flags = utcp_ca->flags; 205 return 1; 206 case offsetof(struct tcp_congestion_ops, name): 207 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 208 sizeof(tcp_ca->name)) <= 0) 209 return -EINVAL; 210 if (tcp_ca_find(utcp_ca->name)) 211 return -EEXIST; 212 return 1; 213 } 214 215 if (!btf_type_resolve_func_ptr(btf_vmlinux, member->type, NULL)) 216 return 0; 217 218 /* Ensure bpf_prog is provided for compulsory func ptr */ 219 prog_fd = (int)(*(unsigned long *)(udata + moff)); 220 if (!prog_fd && !is_optional(moff) && !is_unsupported(moff)) 221 return -EINVAL; 222 223 return 0; 224 } 225 226 static int bpf_tcp_ca_check_member(const struct btf_type *t, 227 const struct btf_member *member) 228 { 229 if (is_unsupported(btf_member_bit_offset(t, member) / 8)) 230 return -ENOTSUPP; 231 return 0; 232 } 233 234 static int bpf_tcp_ca_reg(void *kdata) 235 { 236 return tcp_register_congestion_control(kdata); 237 } 238 239 static void bpf_tcp_ca_unreg(void *kdata) 240 { 241 tcp_unregister_congestion_control(kdata); 242 } 243 244 /* Avoid sparse warning. It is only used in bpf_struct_ops.c. */ 245 extern struct bpf_struct_ops bpf_tcp_congestion_ops; 246 247 struct bpf_struct_ops bpf_tcp_congestion_ops = { 248 .verifier_ops = &bpf_tcp_ca_verifier_ops, 249 .reg = bpf_tcp_ca_reg, 250 .unreg = bpf_tcp_ca_unreg, 251 .check_member = bpf_tcp_ca_check_member, 252 .init_member = bpf_tcp_ca_init_member, 253 .init = bpf_tcp_ca_init, 254 .name = "tcp_congestion_ops", 255 }; 256