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