1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (c) 2015 Jiri Pirko <jiri@resnulli.us> 4 */ 5 6 #include <linux/module.h> 7 #include <linux/init.h> 8 #include <linux/kernel.h> 9 #include <linux/skbuff.h> 10 #include <linux/rtnetlink.h> 11 #include <linux/filter.h> 12 #include <linux/bpf.h> 13 14 #include <net/netlink.h> 15 #include <net/sock.h> 16 #include <net/pkt_sched.h> 17 #include <net/pkt_cls.h> 18 19 #include <linux/tc_act/tc_bpf.h> 20 #include <net/tc_act/tc_bpf.h> 21 22 #define ACT_BPF_NAME_LEN 256 23 24 struct tcf_bpf_cfg { 25 struct bpf_prog *filter; 26 struct sock_filter *bpf_ops; 27 const char *bpf_name; 28 u16 bpf_num_ops; 29 bool is_ebpf; 30 }; 31 32 static unsigned int bpf_net_id; 33 static struct tc_action_ops act_bpf_ops; 34 35 static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act, 36 struct tcf_result *res) 37 { 38 bool at_ingress = skb_at_tc_ingress(skb); 39 struct tcf_bpf *prog = to_bpf(act); 40 struct bpf_prog *filter; 41 int action, filter_res; 42 43 tcf_lastuse_update(&prog->tcf_tm); 44 bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); 45 46 filter = rcu_dereference(prog->filter); 47 if (at_ingress) { 48 __skb_push(skb, skb->mac_len); 49 bpf_compute_data_pointers(skb); 50 filter_res = bpf_prog_run(filter, skb); 51 __skb_pull(skb, skb->mac_len); 52 } else { 53 bpf_compute_data_pointers(skb); 54 filter_res = bpf_prog_run(filter, skb); 55 } 56 if (skb_sk_is_prefetched(skb) && filter_res != TC_ACT_OK) 57 skb_orphan(skb); 58 59 /* A BPF program may overwrite the default action opcode. 60 * Similarly as in cls_bpf, if filter_res == -1 we use the 61 * default action specified from tc. 62 * 63 * In case a different well-known TC_ACT opcode has been 64 * returned, it will overwrite the default one. 65 * 66 * For everything else that is unknown, TC_ACT_UNSPEC is 67 * returned. 68 */ 69 switch (filter_res) { 70 case TC_ACT_PIPE: 71 case TC_ACT_RECLASSIFY: 72 case TC_ACT_OK: 73 case TC_ACT_REDIRECT: 74 action = filter_res; 75 break; 76 case TC_ACT_SHOT: 77 action = filter_res; 78 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats)); 79 break; 80 case TC_ACT_UNSPEC: 81 action = prog->tcf_action; 82 break; 83 default: 84 action = TC_ACT_UNSPEC; 85 break; 86 } 87 88 return action; 89 } 90 91 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog) 92 { 93 return !prog->bpf_ops; 94 } 95 96 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog, 97 struct sk_buff *skb) 98 { 99 struct nlattr *nla; 100 101 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops)) 102 return -EMSGSIZE; 103 104 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops * 105 sizeof(struct sock_filter)); 106 if (nla == NULL) 107 return -EMSGSIZE; 108 109 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 110 111 return 0; 112 } 113 114 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog, 115 struct sk_buff *skb) 116 { 117 struct nlattr *nla; 118 119 if (prog->bpf_name && 120 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name)) 121 return -EMSGSIZE; 122 123 if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id)) 124 return -EMSGSIZE; 125 126 nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag)); 127 if (nla == NULL) 128 return -EMSGSIZE; 129 130 memcpy(nla_data(nla), prog->filter->tag, nla_len(nla)); 131 132 return 0; 133 } 134 135 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act, 136 int bind, int ref) 137 { 138 unsigned char *tp = skb_tail_pointer(skb); 139 struct tcf_bpf *prog = to_bpf(act); 140 struct tc_act_bpf opt = { 141 .index = prog->tcf_index, 142 .refcnt = refcount_read(&prog->tcf_refcnt) - ref, 143 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind, 144 }; 145 struct tcf_t tm; 146 int ret; 147 148 spin_lock_bh(&prog->tcf_lock); 149 opt.action = prog->tcf_action; 150 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt)) 151 goto nla_put_failure; 152 153 if (tcf_bpf_is_ebpf(prog)) 154 ret = tcf_bpf_dump_ebpf_info(prog, skb); 155 else 156 ret = tcf_bpf_dump_bpf_info(prog, skb); 157 if (ret) 158 goto nla_put_failure; 159 160 tcf_tm_dump(&tm, &prog->tcf_tm); 161 if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm, 162 TCA_ACT_BPF_PAD)) 163 goto nla_put_failure; 164 165 spin_unlock_bh(&prog->tcf_lock); 166 return skb->len; 167 168 nla_put_failure: 169 spin_unlock_bh(&prog->tcf_lock); 170 nlmsg_trim(skb, tp); 171 return -1; 172 } 173 174 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 175 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 176 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 177 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, 178 .len = ACT_BPF_NAME_LEN }, 179 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 180 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 181 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 182 }; 183 184 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 185 { 186 struct sock_filter *bpf_ops; 187 struct sock_fprog_kern fprog_tmp; 188 struct bpf_prog *fp; 189 u16 bpf_size, bpf_num_ops; 190 int ret; 191 192 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 193 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 194 return -EINVAL; 195 196 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 197 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 198 return -EINVAL; 199 200 bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL); 201 if (bpf_ops == NULL) 202 return -ENOMEM; 203 204 fprog_tmp.len = bpf_num_ops; 205 fprog_tmp.filter = bpf_ops; 206 207 ret = bpf_prog_create(&fp, &fprog_tmp); 208 if (ret < 0) { 209 kfree(bpf_ops); 210 return ret; 211 } 212 213 cfg->bpf_ops = bpf_ops; 214 cfg->bpf_num_ops = bpf_num_ops; 215 cfg->filter = fp; 216 cfg->is_ebpf = false; 217 218 return 0; 219 } 220 221 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 222 { 223 struct bpf_prog *fp; 224 char *name = NULL; 225 u32 bpf_fd; 226 227 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 228 229 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT); 230 if (IS_ERR(fp)) 231 return PTR_ERR(fp); 232 233 if (tb[TCA_ACT_BPF_NAME]) { 234 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL); 235 if (!name) { 236 bpf_prog_put(fp); 237 return -ENOMEM; 238 } 239 } 240 241 cfg->bpf_name = name; 242 cfg->filter = fp; 243 cfg->is_ebpf = true; 244 245 return 0; 246 } 247 248 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) 249 { 250 struct bpf_prog *filter = cfg->filter; 251 252 if (filter) { 253 if (cfg->is_ebpf) 254 bpf_prog_put(filter); 255 else 256 bpf_prog_destroy(filter); 257 } 258 259 kfree(cfg->bpf_ops); 260 kfree(cfg->bpf_name); 261 } 262 263 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, 264 struct tcf_bpf_cfg *cfg) 265 { 266 cfg->is_ebpf = tcf_bpf_is_ebpf(prog); 267 /* updates to prog->filter are prevented, since it's called either 268 * with tcf lock or during final cleanup in rcu callback 269 */ 270 cfg->filter = rcu_dereference_protected(prog->filter, 1); 271 272 cfg->bpf_ops = prog->bpf_ops; 273 cfg->bpf_name = prog->bpf_name; 274 } 275 276 static int tcf_bpf_init(struct net *net, struct nlattr *nla, 277 struct nlattr *est, struct tc_action **act, 278 struct tcf_proto *tp, u32 flags, 279 struct netlink_ext_ack *extack) 280 { 281 struct tc_action_net *tn = net_generic(net, bpf_net_id); 282 bool bind = flags & TCA_ACT_FLAGS_BIND; 283 struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; 284 struct tcf_chain *goto_ch = NULL; 285 struct tcf_bpf_cfg cfg, old; 286 struct tc_act_bpf *parm; 287 struct tcf_bpf *prog; 288 bool is_bpf, is_ebpf; 289 int ret, res = 0; 290 u32 index; 291 292 if (!nla) 293 return -EINVAL; 294 295 ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla, 296 act_bpf_policy, NULL); 297 if (ret < 0) 298 return ret; 299 300 if (!tb[TCA_ACT_BPF_PARMS]) 301 return -EINVAL; 302 303 parm = nla_data(tb[TCA_ACT_BPF_PARMS]); 304 index = parm->index; 305 ret = tcf_idr_check_alloc(tn, &index, act, bind); 306 if (!ret) { 307 ret = tcf_idr_create(tn, index, est, act, 308 &act_bpf_ops, bind, true, 0); 309 if (ret < 0) { 310 tcf_idr_cleanup(tn, index); 311 return ret; 312 } 313 314 res = ACT_P_CREATED; 315 } else if (ret > 0) { 316 /* Don't override defaults. */ 317 if (bind) 318 return 0; 319 320 if (!(flags & TCA_ACT_FLAGS_REPLACE)) { 321 tcf_idr_release(*act, bind); 322 return -EEXIST; 323 } 324 } else { 325 return ret; 326 } 327 328 ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 329 if (ret < 0) 330 goto release_idr; 331 332 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 333 is_ebpf = tb[TCA_ACT_BPF_FD]; 334 335 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 336 ret = -EINVAL; 337 goto put_chain; 338 } 339 340 memset(&cfg, 0, sizeof(cfg)); 341 342 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 343 tcf_bpf_init_from_efd(tb, &cfg); 344 if (ret < 0) 345 goto put_chain; 346 347 prog = to_bpf(*act); 348 349 spin_lock_bh(&prog->tcf_lock); 350 if (res != ACT_P_CREATED) 351 tcf_bpf_prog_fill_cfg(prog, &old); 352 353 prog->bpf_ops = cfg.bpf_ops; 354 prog->bpf_name = cfg.bpf_name; 355 356 if (cfg.bpf_num_ops) 357 prog->bpf_num_ops = cfg.bpf_num_ops; 358 359 goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch); 360 rcu_assign_pointer(prog->filter, cfg.filter); 361 spin_unlock_bh(&prog->tcf_lock); 362 363 if (goto_ch) 364 tcf_chain_put_by_act(goto_ch); 365 366 if (res != ACT_P_CREATED) { 367 /* make sure the program being replaced is no longer executing */ 368 synchronize_rcu(); 369 tcf_bpf_cfg_cleanup(&old); 370 } 371 372 return res; 373 374 put_chain: 375 if (goto_ch) 376 tcf_chain_put_by_act(goto_ch); 377 378 release_idr: 379 tcf_idr_release(*act, bind); 380 return ret; 381 } 382 383 static void tcf_bpf_cleanup(struct tc_action *act) 384 { 385 struct tcf_bpf_cfg tmp; 386 387 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp); 388 tcf_bpf_cfg_cleanup(&tmp); 389 } 390 391 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 392 struct netlink_callback *cb, int type, 393 const struct tc_action_ops *ops, 394 struct netlink_ext_ack *extack) 395 { 396 struct tc_action_net *tn = net_generic(net, bpf_net_id); 397 398 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 399 } 400 401 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index) 402 { 403 struct tc_action_net *tn = net_generic(net, bpf_net_id); 404 405 return tcf_idr_search(tn, a, index); 406 } 407 408 static struct tc_action_ops act_bpf_ops __read_mostly = { 409 .kind = "bpf", 410 .id = TCA_ID_BPF, 411 .owner = THIS_MODULE, 412 .act = tcf_bpf_act, 413 .dump = tcf_bpf_dump, 414 .cleanup = tcf_bpf_cleanup, 415 .init = tcf_bpf_init, 416 .walk = tcf_bpf_walker, 417 .lookup = tcf_bpf_search, 418 .size = sizeof(struct tcf_bpf), 419 }; 420 421 static __net_init int bpf_init_net(struct net *net) 422 { 423 struct tc_action_net *tn = net_generic(net, bpf_net_id); 424 425 return tc_action_net_init(net, tn, &act_bpf_ops); 426 } 427 428 static void __net_exit bpf_exit_net(struct list_head *net_list) 429 { 430 tc_action_net_exit(net_list, bpf_net_id); 431 } 432 433 static struct pernet_operations bpf_net_ops = { 434 .init = bpf_init_net, 435 .exit_batch = bpf_exit_net, 436 .id = &bpf_net_id, 437 .size = sizeof(struct tc_action_net), 438 }; 439 440 static int __init bpf_init_module(void) 441 { 442 return tcf_register_action(&act_bpf_ops, &bpf_net_ops); 443 } 444 445 static void __exit bpf_cleanup_module(void) 446 { 447 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops); 448 } 449 450 module_init(bpf_init_module); 451 module_exit(bpf_cleanup_module); 452 453 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 454 MODULE_DESCRIPTION("TC BPF based action"); 455 MODULE_LICENSE("GPL v2"); 456