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