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 filter_res = BPF_PROG_RUN(filter, skb); 57 __skb_pull(skb, skb->mac_len); 58 } else { 59 filter_res = BPF_PROG_RUN(filter, skb); 60 } 61 rcu_read_unlock(); 62 63 /* A BPF program may overwrite the default action opcode. 64 * Similarly as in cls_bpf, if filter_res == -1 we use the 65 * default action specified from tc. 66 * 67 * In case a different well-known TC_ACT opcode has been 68 * returned, it will overwrite the default one. 69 * 70 * For everything else that is unkown, TC_ACT_UNSPEC is 71 * returned. 72 */ 73 switch (filter_res) { 74 case TC_ACT_PIPE: 75 case TC_ACT_RECLASSIFY: 76 case TC_ACT_OK: 77 case TC_ACT_REDIRECT: 78 action = filter_res; 79 break; 80 case TC_ACT_SHOT: 81 action = filter_res; 82 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats)); 83 break; 84 case TC_ACT_UNSPEC: 85 action = prog->tcf_action; 86 break; 87 default: 88 action = TC_ACT_UNSPEC; 89 break; 90 } 91 92 return action; 93 } 94 95 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog) 96 { 97 return !prog->bpf_ops; 98 } 99 100 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog, 101 struct sk_buff *skb) 102 { 103 struct nlattr *nla; 104 105 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops)) 106 return -EMSGSIZE; 107 108 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops * 109 sizeof(struct sock_filter)); 110 if (nla == NULL) 111 return -EMSGSIZE; 112 113 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 114 115 return 0; 116 } 117 118 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog, 119 struct sk_buff *skb) 120 { 121 if (nla_put_u32(skb, TCA_ACT_BPF_FD, prog->bpf_fd)) 122 return -EMSGSIZE; 123 124 if (prog->bpf_name && 125 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name)) 126 return -EMSGSIZE; 127 128 return 0; 129 } 130 131 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act, 132 int bind, int ref) 133 { 134 unsigned char *tp = skb_tail_pointer(skb); 135 struct tcf_bpf *prog = act->priv; 136 struct tc_act_bpf opt = { 137 .index = prog->tcf_index, 138 .refcnt = prog->tcf_refcnt - ref, 139 .bindcnt = prog->tcf_bindcnt - bind, 140 .action = prog->tcf_action, 141 }; 142 struct tcf_t tm; 143 int ret; 144 145 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt)) 146 goto nla_put_failure; 147 148 if (tcf_bpf_is_ebpf(prog)) 149 ret = tcf_bpf_dump_ebpf_info(prog, skb); 150 else 151 ret = tcf_bpf_dump_bpf_info(prog, skb); 152 if (ret) 153 goto nla_put_failure; 154 155 tm.install = jiffies_to_clock_t(jiffies - prog->tcf_tm.install); 156 tm.lastuse = jiffies_to_clock_t(jiffies - prog->tcf_tm.lastuse); 157 tm.expires = jiffies_to_clock_t(prog->tcf_tm.expires); 158 159 if (nla_put(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm)) 160 goto nla_put_failure; 161 162 return skb->len; 163 164 nla_put_failure: 165 nlmsg_trim(skb, tp); 166 return -1; 167 } 168 169 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 170 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 171 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 172 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, .len = ACT_BPF_NAME_LEN }, 173 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 174 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 175 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 176 }; 177 178 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 179 { 180 struct sock_filter *bpf_ops; 181 struct sock_fprog_kern fprog_tmp; 182 struct bpf_prog *fp; 183 u16 bpf_size, bpf_num_ops; 184 int ret; 185 186 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 187 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 188 return -EINVAL; 189 190 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 191 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 192 return -EINVAL; 193 194 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 195 if (bpf_ops == NULL) 196 return -ENOMEM; 197 198 memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size); 199 200 fprog_tmp.len = bpf_num_ops; 201 fprog_tmp.filter = bpf_ops; 202 203 ret = bpf_prog_create(&fp, &fprog_tmp); 204 if (ret < 0) { 205 kfree(bpf_ops); 206 return ret; 207 } 208 209 cfg->bpf_ops = bpf_ops; 210 cfg->bpf_num_ops = bpf_num_ops; 211 cfg->filter = fp; 212 cfg->is_ebpf = false; 213 214 return 0; 215 } 216 217 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 218 { 219 struct bpf_prog *fp; 220 char *name = NULL; 221 u32 bpf_fd; 222 223 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 224 225 fp = bpf_prog_get(bpf_fd); 226 if (IS_ERR(fp)) 227 return PTR_ERR(fp); 228 229 if (fp->type != BPF_PROG_TYPE_SCHED_ACT) { 230 bpf_prog_put(fp); 231 return -EINVAL; 232 } 233 234 if (tb[TCA_ACT_BPF_NAME]) { 235 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]), 236 nla_len(tb[TCA_ACT_BPF_NAME]), 237 GFP_KERNEL); 238 if (!name) { 239 bpf_prog_put(fp); 240 return -ENOMEM; 241 } 242 } 243 244 cfg->bpf_fd = bpf_fd; 245 cfg->bpf_name = name; 246 cfg->filter = fp; 247 cfg->is_ebpf = true; 248 249 return 0; 250 } 251 252 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) 253 { 254 if (cfg->is_ebpf) 255 bpf_prog_put(cfg->filter); 256 else 257 bpf_prog_destroy(cfg->filter); 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 rtnl 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 int replace, int bind) 279 { 280 struct tc_action_net *tn = net_generic(net, bpf_net_id); 281 struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; 282 struct tcf_bpf_cfg cfg, old; 283 struct tc_act_bpf *parm; 284 struct tcf_bpf *prog; 285 bool is_bpf, is_ebpf; 286 int ret, res = 0; 287 288 if (!nla) 289 return -EINVAL; 290 291 ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy); 292 if (ret < 0) 293 return ret; 294 295 if (!tb[TCA_ACT_BPF_PARMS]) 296 return -EINVAL; 297 298 parm = nla_data(tb[TCA_ACT_BPF_PARMS]); 299 300 if (!tcf_hash_check(tn, parm->index, act, bind)) { 301 ret = tcf_hash_create(tn, parm->index, est, act, 302 sizeof(*prog), bind, true); 303 if (ret < 0) 304 return ret; 305 306 res = ACT_P_CREATED; 307 } else { 308 /* Don't override defaults. */ 309 if (bind) 310 return 0; 311 312 tcf_hash_release(act, bind); 313 if (!replace) 314 return -EEXIST; 315 } 316 317 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 318 is_ebpf = tb[TCA_ACT_BPF_FD]; 319 320 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 321 ret = -EINVAL; 322 goto out; 323 } 324 325 memset(&cfg, 0, sizeof(cfg)); 326 327 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 328 tcf_bpf_init_from_efd(tb, &cfg); 329 if (ret < 0) 330 goto out; 331 332 prog = to_bpf(act); 333 ASSERT_RTNL(); 334 335 if (res != ACT_P_CREATED) 336 tcf_bpf_prog_fill_cfg(prog, &old); 337 338 prog->bpf_ops = cfg.bpf_ops; 339 prog->bpf_name = cfg.bpf_name; 340 341 if (cfg.bpf_num_ops) 342 prog->bpf_num_ops = cfg.bpf_num_ops; 343 if (cfg.bpf_fd) 344 prog->bpf_fd = cfg.bpf_fd; 345 346 prog->tcf_action = parm->action; 347 rcu_assign_pointer(prog->filter, cfg.filter); 348 349 if (res == ACT_P_CREATED) { 350 tcf_hash_insert(tn, act); 351 } else { 352 /* make sure the program being replaced is no longer executing */ 353 synchronize_rcu(); 354 tcf_bpf_cfg_cleanup(&old); 355 } 356 357 return res; 358 out: 359 if (res == ACT_P_CREATED) 360 tcf_hash_cleanup(act, est); 361 362 return ret; 363 } 364 365 static void tcf_bpf_cleanup(struct tc_action *act, int bind) 366 { 367 struct tcf_bpf_cfg tmp; 368 369 tcf_bpf_prog_fill_cfg(act->priv, &tmp); 370 tcf_bpf_cfg_cleanup(&tmp); 371 } 372 373 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 374 struct netlink_callback *cb, int type, 375 struct tc_action *a) 376 { 377 struct tc_action_net *tn = net_generic(net, bpf_net_id); 378 379 return tcf_generic_walker(tn, skb, cb, type, a); 380 } 381 382 static int tcf_bpf_search(struct net *net, struct tc_action *a, u32 index) 383 { 384 struct tc_action_net *tn = net_generic(net, bpf_net_id); 385 386 return tcf_hash_search(tn, a, index); 387 } 388 389 static struct tc_action_ops act_bpf_ops __read_mostly = { 390 .kind = "bpf", 391 .type = TCA_ACT_BPF, 392 .owner = THIS_MODULE, 393 .act = tcf_bpf, 394 .dump = tcf_bpf_dump, 395 .cleanup = tcf_bpf_cleanup, 396 .init = tcf_bpf_init, 397 .walk = tcf_bpf_walker, 398 .lookup = tcf_bpf_search, 399 }; 400 401 static __net_init int bpf_init_net(struct net *net) 402 { 403 struct tc_action_net *tn = net_generic(net, bpf_net_id); 404 405 return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK); 406 } 407 408 static void __net_exit bpf_exit_net(struct net *net) 409 { 410 struct tc_action_net *tn = net_generic(net, bpf_net_id); 411 412 tc_action_net_exit(tn); 413 } 414 415 static struct pernet_operations bpf_net_ops = { 416 .init = bpf_init_net, 417 .exit = bpf_exit_net, 418 .id = &bpf_net_id, 419 .size = sizeof(struct tc_action_net), 420 }; 421 422 static int __init bpf_init_module(void) 423 { 424 return tcf_register_action(&act_bpf_ops, &bpf_net_ops); 425 } 426 427 static void __exit bpf_cleanup_module(void) 428 { 429 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops); 430 } 431 432 module_init(bpf_init_module); 433 module_exit(bpf_cleanup_module); 434 435 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 436 MODULE_DESCRIPTION("TC BPF based action"); 437 MODULE_LICENSE("GPL v2"); 438