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. */ 15extern struct bpf_struct_ops bpf_tcp_congestion_ops; 16 17static u32 unsupported_ops[] = { 18 offsetof(struct tcp_congestion_ops, get_info), 19}; 20 21static const struct btf_type *tcp_sock_type; 22static u32 tcp_sock_id, sock_id; 23 24static int bpf_tcp_ca_init(struct btf *btf) 25{ 26 s32 type_id; 27 28 type_id = btf_find_by_name_kind(btf, "sock", BTF_KIND_STRUCT); 29 if (type_id < 0) 30 return -EINVAL; 31 sock_id = type_id; 32 33 type_id = btf_find_by_name_kind(btf, "tcp_sock", BTF_KIND_STRUCT); 34 if (type_id < 0) 35 return -EINVAL; 36 tcp_sock_id = type_id; 37 tcp_sock_type = btf_type_by_id(btf, tcp_sock_id); 38 39 return 0; 40} 41 42static bool is_unsupported(u32 member_offset) 43{ 44 unsigned int i; 45 46 for (i = 0; i < ARRAY_SIZE(unsupported_ops); i++) { 47 if (member_offset == unsupported_ops[i]) 48 return true; 49 } 50 51 return false; 52} 53 54static bool bpf_tcp_ca_is_valid_access(int off, int size, 55 enum bpf_access_type type, 56 const struct bpf_prog *prog, 57 struct bpf_insn_access_aux *info) 58{ 59 if (!bpf_tracing_btf_ctx_access(off, size, type, prog, info)) 60 return false; 61 62 if (base_type(info->reg_type) == PTR_TO_BTF_ID && 63 !bpf_type_has_unsafe_modifiers(info->reg_type) && 64 info->btf_id == sock_id) 65 /* promote it to tcp_sock */ 66 info->btf_id = tcp_sock_id; 67 68 return true; 69} 70 71static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, 72 const struct bpf_reg_state *reg, 73 int off, int size) 74{ 75 const struct btf_type *t; 76 size_t end; 77 78 t = btf_type_by_id(reg->btf, reg->btf_id); 79 if (t != tcp_sock_type) { 80 bpf_log(log, "only read is supported\n"); 81 return -EACCES; 82 } 83 84 switch (off) { 85 case offsetof(struct sock, sk_pacing_rate): 86 end = offsetofend(struct sock, sk_pacing_rate); 87 break; 88 case offsetof(struct sock, sk_pacing_status): 89 end = offsetofend(struct sock, sk_pacing_status); 90 break; 91 case bpf_ctx_range(struct inet_connection_sock, icsk_ca_priv): 92 end = offsetofend(struct inet_connection_sock, icsk_ca_priv); 93 break; 94 case offsetof(struct inet_connection_sock, icsk_ack.pending): 95 end = offsetofend(struct inet_connection_sock, 96 icsk_ack.pending); 97 break; 98 case offsetof(struct tcp_sock, snd_cwnd): 99 end = offsetofend(struct tcp_sock, snd_cwnd); 100 break; 101 case offsetof(struct tcp_sock, snd_cwnd_cnt): 102 end = offsetofend(struct tcp_sock, snd_cwnd_cnt); 103 break; 104 case offsetof(struct tcp_sock, snd_ssthresh): 105 end = offsetofend(struct tcp_sock, snd_ssthresh); 106 break; 107 case offsetof(struct tcp_sock, ecn_flags): 108 end = offsetofend(struct tcp_sock, ecn_flags); 109 break; 110 case offsetof(struct tcp_sock, app_limited): 111 end = offsetofend(struct tcp_sock, app_limited); 112 break; 113 default: 114 bpf_log(log, "no write support to tcp_sock at off %d\n", off); 115 return -EACCES; 116 } 117 118 if (off + size > end) { 119 bpf_log(log, 120 "write access at off %d with size %d beyond the member of tcp_sock ended at %zu\n", 121 off, size, end); 122 return -EACCES; 123 } 124 125 return 0; 126} 127 128BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) 129{ 130 /* bpf_tcp_ca prog cannot have NULL tp */ 131 __tcp_send_ack((struct sock *)tp, rcv_nxt); 132 return 0; 133} 134 135static const struct bpf_func_proto bpf_tcp_send_ack_proto = { 136 .func = bpf_tcp_send_ack, 137 .gpl_only = false, 138 /* In case we want to report error later */ 139 .ret_type = RET_INTEGER, 140 .arg1_type = ARG_PTR_TO_BTF_ID, 141 .arg1_btf_id = &tcp_sock_id, 142 .arg2_type = ARG_ANYTHING, 143}; 144 145static u32 prog_ops_moff(const struct bpf_prog *prog) 146{ 147 const struct btf_member *m; 148 const struct btf_type *t; 149 u32 midx; 150 151 midx = prog->expected_attach_type; 152 t = bpf_tcp_congestion_ops.type; 153 m = &btf_type_member(t)[midx]; 154 155 return __btf_member_bit_offset(t, m) / 8; 156} 157 158static const struct bpf_func_proto * 159bpf_tcp_ca_get_func_proto(enum bpf_func_id func_id, 160 const struct bpf_prog *prog) 161{ 162 switch (func_id) { 163 case BPF_FUNC_tcp_send_ack: 164 return &bpf_tcp_send_ack_proto; 165 case BPF_FUNC_sk_storage_get: 166 return &bpf_sk_storage_get_proto; 167 case BPF_FUNC_sk_storage_delete: 168 return &bpf_sk_storage_delete_proto; 169 case BPF_FUNC_setsockopt: 170 /* Does not allow release() to call setsockopt. 171 * release() is called when the current bpf-tcp-cc 172 * is retiring. It is not allowed to call 173 * setsockopt() to make further changes which 174 * may potentially allocate new resources. 175 */ 176 if (prog_ops_moff(prog) != 177 offsetof(struct tcp_congestion_ops, release)) 178 return &bpf_sk_setsockopt_proto; 179 return NULL; 180 case BPF_FUNC_getsockopt: 181 /* Since get/setsockopt is usually expected to 182 * be available together, disable getsockopt for 183 * release also to avoid usage surprise. 184 * The bpf-tcp-cc already has a more powerful way 185 * to read tcp_sock from the PTR_TO_BTF_ID. 186 */ 187 if (prog_ops_moff(prog) != 188 offsetof(struct tcp_congestion_ops, release)) 189 return &bpf_sk_getsockopt_proto; 190 return NULL; 191 case BPF_FUNC_ktime_get_coarse_ns: 192 return &bpf_ktime_get_coarse_ns_proto; 193 default: 194 return bpf_base_func_proto(func_id); 195 } 196} 197 198BTF_SET8_START(bpf_tcp_ca_check_kfunc_ids) 199BTF_ID_FLAGS(func, tcp_reno_ssthresh) 200BTF_ID_FLAGS(func, tcp_reno_cong_avoid) 201BTF_ID_FLAGS(func, tcp_reno_undo_cwnd) 202BTF_ID_FLAGS(func, tcp_slow_start) 203BTF_ID_FLAGS(func, tcp_cong_avoid_ai) 204BTF_SET8_END(bpf_tcp_ca_check_kfunc_ids) 205 206static const struct btf_kfunc_id_set bpf_tcp_ca_kfunc_set = { 207 .owner = THIS_MODULE, 208 .set = &bpf_tcp_ca_check_kfunc_ids, 209}; 210 211static const struct bpf_verifier_ops bpf_tcp_ca_verifier_ops = { 212 .get_func_proto = bpf_tcp_ca_get_func_proto, 213 .is_valid_access = bpf_tcp_ca_is_valid_access, 214 .btf_struct_access = bpf_tcp_ca_btf_struct_access, 215}; 216 217static int bpf_tcp_ca_init_member(const struct btf_type *t, 218 const struct btf_member *member, 219 void *kdata, const void *udata) 220{ 221 const struct tcp_congestion_ops *utcp_ca; 222 struct tcp_congestion_ops *tcp_ca; 223 u32 moff; 224 225 utcp_ca = (const struct tcp_congestion_ops *)udata; 226 tcp_ca = (struct tcp_congestion_ops *)kdata; 227 228 moff = __btf_member_bit_offset(t, member) / 8; 229 switch (moff) { 230 case offsetof(struct tcp_congestion_ops, flags): 231 if (utcp_ca->flags & ~TCP_CONG_MASK) 232 return -EINVAL; 233 tcp_ca->flags = utcp_ca->flags; 234 return 1; 235 case offsetof(struct tcp_congestion_ops, name): 236 if (bpf_obj_name_cpy(tcp_ca->name, utcp_ca->name, 237 sizeof(tcp_ca->name)) <= 0) 238 return -EINVAL; 239 return 1; 240 } 241 242 return 0; 243} 244 245static int bpf_tcp_ca_check_member(const struct btf_type *t, 246 const struct btf_member *member, 247 const struct bpf_prog *prog) 248{ 249 if (is_unsupported(__btf_member_bit_offset(t, member) / 8)) 250 return -ENOTSUPP; 251 return 0; 252} 253 254static int bpf_tcp_ca_reg(void *kdata) 255{ 256 return tcp_register_congestion_control(kdata); 257} 258 259static void bpf_tcp_ca_unreg(void *kdata) 260{ 261 tcp_unregister_congestion_control(kdata); 262} 263 264static int bpf_tcp_ca_update(void *kdata, void *old_kdata) 265{ 266 return tcp_update_congestion_control(kdata, old_kdata); 267} 268 269static int bpf_tcp_ca_validate(void *kdata) 270{ 271 return tcp_validate_congestion_control(kdata); 272} 273 274struct bpf_struct_ops bpf_tcp_congestion_ops = { 275 .verifier_ops = &bpf_tcp_ca_verifier_ops, 276 .reg = bpf_tcp_ca_reg, 277 .unreg = bpf_tcp_ca_unreg, 278 .update = bpf_tcp_ca_update, 279 .check_member = bpf_tcp_ca_check_member, 280 .init_member = bpf_tcp_ca_init_member, 281 .init = bpf_tcp_ca_init, 282 .validate = bpf_tcp_ca_validate, 283 .name = "tcp_congestion_ops", 284}; 285 286static int __init bpf_tcp_ca_kfunc_init(void) 287{ 288 return register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_tcp_ca_kfunc_set); 289} 290late_initcall(bpf_tcp_ca_kfunc_init); 291