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/pkt_sched.h> 16 #include <net/pkt_cls.h> 17 18 #include <linux/tc_act/tc_bpf.h> 19 #include <net/tc_act/tc_bpf.h> 20 21 #define ACT_BPF_NAME_LEN 256 22 23 struct tcf_bpf_cfg { 24 struct bpf_prog *filter; 25 struct sock_filter *bpf_ops; 26 const char *bpf_name; 27 u16 bpf_num_ops; 28 bool is_ebpf; 29 }; 30 31 static unsigned int bpf_net_id; 32 static struct tc_action_ops act_bpf_ops; 33 34 static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act, 35 struct tcf_result *res) 36 { 37 bool at_ingress = skb_at_tc_ingress(skb); 38 struct tcf_bpf *prog = to_bpf(act); 39 struct bpf_prog *filter; 40 int action, filter_res; 41 42 tcf_lastuse_update(&prog->tcf_tm); 43 bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); 44 45 rcu_read_lock(); 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 rcu_read_unlock(); 57 58 /* A BPF program may overwrite the default action opcode. 59 * Similarly as in cls_bpf, if filter_res == -1 we use the 60 * default action specified from tc. 61 * 62 * In case a different well-known TC_ACT opcode has been 63 * returned, it will overwrite the default one. 64 * 65 * For everything else that is unkown, TC_ACT_UNSPEC is 66 * returned. 67 */ 68 switch (filter_res) { 69 case TC_ACT_PIPE: 70 case TC_ACT_RECLASSIFY: 71 case TC_ACT_OK: 72 case TC_ACT_REDIRECT: 73 action = filter_res; 74 break; 75 case TC_ACT_SHOT: 76 action = filter_res; 77 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats)); 78 break; 79 case TC_ACT_UNSPEC: 80 action = prog->tcf_action; 81 break; 82 default: 83 action = TC_ACT_UNSPEC; 84 break; 85 } 86 87 return action; 88 } 89 90 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog) 91 { 92 return !prog->bpf_ops; 93 } 94 95 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog, 96 struct sk_buff *skb) 97 { 98 struct nlattr *nla; 99 100 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops)) 101 return -EMSGSIZE; 102 103 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops * 104 sizeof(struct sock_filter)); 105 if (nla == NULL) 106 return -EMSGSIZE; 107 108 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 109 110 return 0; 111 } 112 113 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog, 114 struct sk_buff *skb) 115 { 116 struct nlattr *nla; 117 118 if (prog->bpf_name && 119 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name)) 120 return -EMSGSIZE; 121 122 if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id)) 123 return -EMSGSIZE; 124 125 nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag)); 126 if (nla == NULL) 127 return -EMSGSIZE; 128 129 memcpy(nla_data(nla), prog->filter->tag, nla_len(nla)); 130 131 return 0; 132 } 133 134 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act, 135 int bind, int ref) 136 { 137 unsigned char *tp = skb_tail_pointer(skb); 138 struct tcf_bpf *prog = to_bpf(act); 139 struct tc_act_bpf opt = { 140 .index = prog->tcf_index, 141 .refcnt = refcount_read(&prog->tcf_refcnt) - ref, 142 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind, 143 }; 144 struct tcf_t tm; 145 int ret; 146 147 spin_lock_bh(&prog->tcf_lock); 148 opt.action = prog->tcf_action; 149 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt)) 150 goto nla_put_failure; 151 152 if (tcf_bpf_is_ebpf(prog)) 153 ret = tcf_bpf_dump_ebpf_info(prog, skb); 154 else 155 ret = tcf_bpf_dump_bpf_info(prog, skb); 156 if (ret) 157 goto nla_put_failure; 158 159 tcf_tm_dump(&tm, &prog->tcf_tm); 160 if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm, 161 TCA_ACT_BPF_PAD)) 162 goto nla_put_failure; 163 164 spin_unlock_bh(&prog->tcf_lock); 165 return skb->len; 166 167 nla_put_failure: 168 spin_unlock_bh(&prog->tcf_lock); 169 nlmsg_trim(skb, tp); 170 return -1; 171 } 172 173 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 174 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 175 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 176 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, 177 .len = ACT_BPF_NAME_LEN }, 178 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 179 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 180 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 181 }; 182 183 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 184 { 185 struct sock_filter *bpf_ops; 186 struct sock_fprog_kern fprog_tmp; 187 struct bpf_prog *fp; 188 u16 bpf_size, bpf_num_ops; 189 int ret; 190 191 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 192 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 193 return -EINVAL; 194 195 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 196 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 197 return -EINVAL; 198 199 bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL); 200 if (bpf_ops == NULL) 201 return -ENOMEM; 202 203 fprog_tmp.len = bpf_num_ops; 204 fprog_tmp.filter = bpf_ops; 205 206 ret = bpf_prog_create(&fp, &fprog_tmp); 207 if (ret < 0) { 208 kfree(bpf_ops); 209 return ret; 210 } 211 212 cfg->bpf_ops = bpf_ops; 213 cfg->bpf_num_ops = bpf_num_ops; 214 cfg->filter = fp; 215 cfg->is_ebpf = false; 216 217 return 0; 218 } 219 220 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 221 { 222 struct bpf_prog *fp; 223 char *name = NULL; 224 u32 bpf_fd; 225 226 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 227 228 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT); 229 if (IS_ERR(fp)) 230 return PTR_ERR(fp); 231 232 if (tb[TCA_ACT_BPF_NAME]) { 233 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL); 234 if (!name) { 235 bpf_prog_put(fp); 236 return -ENOMEM; 237 } 238 } 239 240 cfg->bpf_name = name; 241 cfg->filter = fp; 242 cfg->is_ebpf = true; 243 244 return 0; 245 } 246 247 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) 248 { 249 struct bpf_prog *filter = cfg->filter; 250 251 if (filter) { 252 if (cfg->is_ebpf) 253 bpf_prog_put(filter); 254 else 255 bpf_prog_destroy(filter); 256 } 257 258 kfree(cfg->bpf_ops); 259 kfree(cfg->bpf_name); 260 } 261 262 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, 263 struct tcf_bpf_cfg *cfg) 264 { 265 cfg->is_ebpf = tcf_bpf_is_ebpf(prog); 266 /* updates to prog->filter are prevented, since it's called either 267 * with tcf lock or during final cleanup in rcu callback 268 */ 269 cfg->filter = rcu_dereference_protected(prog->filter, 1); 270 271 cfg->bpf_ops = prog->bpf_ops; 272 cfg->bpf_name = prog->bpf_name; 273 } 274 275 static int tcf_bpf_init(struct net *net, struct nlattr *nla, 276 struct nlattr *est, struct tc_action **act, 277 int replace, int bind, bool rtnl_held, 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 struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; 283 struct tcf_chain *goto_ch = NULL; 284 struct tcf_bpf_cfg cfg, old; 285 struct tc_act_bpf *parm; 286 struct tcf_bpf *prog; 287 bool is_bpf, is_ebpf; 288 int ret, res = 0; 289 u32 index; 290 291 if (!nla) 292 return -EINVAL; 293 294 ret = nla_parse_nested_deprecated(tb, TCA_ACT_BPF_MAX, nla, 295 act_bpf_policy, NULL); 296 if (ret < 0) 297 return ret; 298 299 if (!tb[TCA_ACT_BPF_PARMS]) 300 return -EINVAL; 301 302 parm = nla_data(tb[TCA_ACT_BPF_PARMS]); 303 index = parm->index; 304 ret = tcf_idr_check_alloc(tn, &index, act, bind); 305 if (!ret) { 306 ret = tcf_idr_create(tn, index, est, act, 307 &act_bpf_ops, bind, true, 0); 308 if (ret < 0) { 309 tcf_idr_cleanup(tn, index); 310 return ret; 311 } 312 313 res = ACT_P_CREATED; 314 } else if (ret > 0) { 315 /* Don't override defaults. */ 316 if (bind) 317 return 0; 318 319 if (!replace) { 320 tcf_idr_release(*act, bind); 321 return -EEXIST; 322 } 323 } else { 324 return ret; 325 } 326 327 ret = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack); 328 if (ret < 0) 329 goto release_idr; 330 331 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 332 is_ebpf = tb[TCA_ACT_BPF_FD]; 333 334 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 335 ret = -EINVAL; 336 goto put_chain; 337 } 338 339 memset(&cfg, 0, sizeof(cfg)); 340 341 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 342 tcf_bpf_init_from_efd(tb, &cfg); 343 if (ret < 0) 344 goto put_chain; 345 346 prog = to_bpf(*act); 347 348 spin_lock_bh(&prog->tcf_lock); 349 if (res != ACT_P_CREATED) 350 tcf_bpf_prog_fill_cfg(prog, &old); 351 352 prog->bpf_ops = cfg.bpf_ops; 353 prog->bpf_name = cfg.bpf_name; 354 355 if (cfg.bpf_num_ops) 356 prog->bpf_num_ops = cfg.bpf_num_ops; 357 358 goto_ch = tcf_action_set_ctrlact(*act, parm->action, goto_ch); 359 rcu_assign_pointer(prog->filter, cfg.filter); 360 spin_unlock_bh(&prog->tcf_lock); 361 362 if (goto_ch) 363 tcf_chain_put_by_act(goto_ch); 364 365 if (res == ACT_P_CREATED) { 366 tcf_idr_insert(tn, *act); 367 } else { 368 /* make sure the program being replaced is no longer executing */ 369 synchronize_rcu(); 370 tcf_bpf_cfg_cleanup(&old); 371 } 372 373 return res; 374 375 put_chain: 376 if (goto_ch) 377 tcf_chain_put_by_act(goto_ch); 378 379 release_idr: 380 tcf_idr_release(*act, bind); 381 return ret; 382 } 383 384 static void tcf_bpf_cleanup(struct tc_action *act) 385 { 386 struct tcf_bpf_cfg tmp; 387 388 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp); 389 tcf_bpf_cfg_cleanup(&tmp); 390 } 391 392 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 393 struct netlink_callback *cb, int type, 394 const struct tc_action_ops *ops, 395 struct netlink_ext_ack *extack) 396 { 397 struct tc_action_net *tn = net_generic(net, bpf_net_id); 398 399 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 400 } 401 402 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index) 403 { 404 struct tc_action_net *tn = net_generic(net, bpf_net_id); 405 406 return tcf_idr_search(tn, a, index); 407 } 408 409 static struct tc_action_ops act_bpf_ops __read_mostly = { 410 .kind = "bpf", 411 .id = TCA_ID_BPF, 412 .owner = THIS_MODULE, 413 .act = tcf_bpf_act, 414 .dump = tcf_bpf_dump, 415 .cleanup = tcf_bpf_cleanup, 416 .init = tcf_bpf_init, 417 .walk = tcf_bpf_walker, 418 .lookup = tcf_bpf_search, 419 .size = sizeof(struct tcf_bpf), 420 }; 421 422 static __net_init int bpf_init_net(struct net *net) 423 { 424 struct tc_action_net *tn = net_generic(net, bpf_net_id); 425 426 return tc_action_net_init(net, tn, &act_bpf_ops); 427 } 428 429 static void __net_exit bpf_exit_net(struct list_head *net_list) 430 { 431 tc_action_net_exit(net_list, bpf_net_id); 432 } 433 434 static struct pernet_operations bpf_net_ops = { 435 .init = bpf_init_net, 436 .exit_batch = bpf_exit_net, 437 .id = &bpf_net_id, 438 .size = sizeof(struct tc_action_net), 439 }; 440 441 static int __init bpf_init_module(void) 442 { 443 return tcf_register_action(&act_bpf_ops, &bpf_net_ops); 444 } 445 446 static void __exit bpf_cleanup_module(void) 447 { 448 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops); 449 } 450 451 module_init(bpf_init_module); 452 module_exit(bpf_cleanup_module); 453 454 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 455 MODULE_DESCRIPTION("TC BPF based action"); 456 MODULE_LICENSE("GPL v2"); 457