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 u16 bpf_num_ops; 32 bool is_ebpf; 33 }; 34 35 static unsigned int bpf_net_id; 36 static struct tc_action_ops act_bpf_ops; 37 38 static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act, 39 struct tcf_result *res) 40 { 41 bool at_ingress = skb_at_tc_ingress(skb); 42 struct tcf_bpf *prog = to_bpf(act); 43 struct bpf_prog *filter; 44 int action, filter_res; 45 46 tcf_lastuse_update(&prog->tcf_tm); 47 bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); 48 49 rcu_read_lock(); 50 filter = rcu_dereference(prog->filter); 51 if (at_ingress) { 52 __skb_push(skb, skb->mac_len); 53 bpf_compute_data_end(skb); 54 filter_res = BPF_PROG_RUN(filter, skb); 55 __skb_pull(skb, skb->mac_len); 56 } else { 57 bpf_compute_data_end(skb); 58 filter_res = BPF_PROG_RUN(filter, skb); 59 } 60 rcu_read_unlock(); 61 62 /* A BPF program may overwrite the default action opcode. 63 * Similarly as in cls_bpf, if filter_res == -1 we use the 64 * default action specified from tc. 65 * 66 * In case a different well-known TC_ACT opcode has been 67 * returned, it will overwrite the default one. 68 * 69 * For everything else that is unkown, TC_ACT_UNSPEC is 70 * returned. 71 */ 72 switch (filter_res) { 73 case TC_ACT_PIPE: 74 case TC_ACT_RECLASSIFY: 75 case TC_ACT_OK: 76 case TC_ACT_REDIRECT: 77 action = filter_res; 78 break; 79 case TC_ACT_SHOT: 80 action = filter_res; 81 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats)); 82 break; 83 case TC_ACT_UNSPEC: 84 action = prog->tcf_action; 85 break; 86 default: 87 action = TC_ACT_UNSPEC; 88 break; 89 } 90 91 return action; 92 } 93 94 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog) 95 { 96 return !prog->bpf_ops; 97 } 98 99 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog, 100 struct sk_buff *skb) 101 { 102 struct nlattr *nla; 103 104 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops)) 105 return -EMSGSIZE; 106 107 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops * 108 sizeof(struct sock_filter)); 109 if (nla == NULL) 110 return -EMSGSIZE; 111 112 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 113 114 return 0; 115 } 116 117 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog, 118 struct sk_buff *skb) 119 { 120 struct nlattr *nla; 121 122 if (prog->bpf_name && 123 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name)) 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 = prog->tcf_refcnt - ref, 143 .bindcnt = prog->tcf_bindcnt - bind, 144 .action = prog->tcf_action, 145 }; 146 struct tcf_t tm; 147 int ret; 148 149 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 return skb->len; 165 166 nla_put_failure: 167 nlmsg_trim(skb, tp); 168 return -1; 169 } 170 171 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 172 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 173 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 174 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, 175 .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_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 if (cfg->is_ebpf) 250 bpf_prog_put(cfg->filter); 251 else 252 bpf_prog_destroy(cfg->filter); 253 254 kfree(cfg->bpf_ops); 255 kfree(cfg->bpf_name); 256 } 257 258 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, 259 struct tcf_bpf_cfg *cfg) 260 { 261 cfg->is_ebpf = tcf_bpf_is_ebpf(prog); 262 /* updates to prog->filter are prevented, since it's called either 263 * with rtnl lock or during final cleanup in rcu callback 264 */ 265 cfg->filter = rcu_dereference_protected(prog->filter, 1); 266 267 cfg->bpf_ops = prog->bpf_ops; 268 cfg->bpf_name = prog->bpf_name; 269 } 270 271 static int tcf_bpf_init(struct net *net, struct nlattr *nla, 272 struct nlattr *est, struct tc_action **act, 273 int replace, int bind) 274 { 275 struct tc_action_net *tn = net_generic(net, bpf_net_id); 276 struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; 277 struct tcf_bpf_cfg cfg, old; 278 struct tc_act_bpf *parm; 279 struct tcf_bpf *prog; 280 bool is_bpf, is_ebpf; 281 int ret, res = 0; 282 283 if (!nla) 284 return -EINVAL; 285 286 ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy, NULL); 287 if (ret < 0) 288 return ret; 289 290 if (!tb[TCA_ACT_BPF_PARMS]) 291 return -EINVAL; 292 293 parm = nla_data(tb[TCA_ACT_BPF_PARMS]); 294 295 if (!tcf_hash_check(tn, parm->index, act, bind)) { 296 ret = tcf_hash_create(tn, parm->index, est, act, 297 &act_bpf_ops, bind, true); 298 if (ret < 0) 299 return ret; 300 301 res = ACT_P_CREATED; 302 } else { 303 /* Don't override defaults. */ 304 if (bind) 305 return 0; 306 307 tcf_hash_release(*act, bind); 308 if (!replace) 309 return -EEXIST; 310 } 311 312 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 313 is_ebpf = tb[TCA_ACT_BPF_FD]; 314 315 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 316 ret = -EINVAL; 317 goto out; 318 } 319 320 memset(&cfg, 0, sizeof(cfg)); 321 322 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 323 tcf_bpf_init_from_efd(tb, &cfg); 324 if (ret < 0) 325 goto out; 326 327 prog = to_bpf(*act); 328 ASSERT_RTNL(); 329 330 if (res != ACT_P_CREATED) 331 tcf_bpf_prog_fill_cfg(prog, &old); 332 333 prog->bpf_ops = cfg.bpf_ops; 334 prog->bpf_name = cfg.bpf_name; 335 336 if (cfg.bpf_num_ops) 337 prog->bpf_num_ops = cfg.bpf_num_ops; 338 339 prog->tcf_action = parm->action; 340 rcu_assign_pointer(prog->filter, cfg.filter); 341 342 if (res == ACT_P_CREATED) { 343 tcf_hash_insert(tn, *act); 344 } else { 345 /* make sure the program being replaced is no longer executing */ 346 synchronize_rcu(); 347 tcf_bpf_cfg_cleanup(&old); 348 } 349 350 return res; 351 out: 352 if (res == ACT_P_CREATED) 353 tcf_hash_cleanup(*act, est); 354 355 return ret; 356 } 357 358 static void tcf_bpf_cleanup(struct tc_action *act, int bind) 359 { 360 struct tcf_bpf_cfg tmp; 361 362 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp); 363 tcf_bpf_cfg_cleanup(&tmp); 364 } 365 366 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 367 struct netlink_callback *cb, int type, 368 const struct tc_action_ops *ops) 369 { 370 struct tc_action_net *tn = net_generic(net, bpf_net_id); 371 372 return tcf_generic_walker(tn, skb, cb, type, ops); 373 } 374 375 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index) 376 { 377 struct tc_action_net *tn = net_generic(net, bpf_net_id); 378 379 return tcf_hash_search(tn, a, index); 380 } 381 382 static struct tc_action_ops act_bpf_ops __read_mostly = { 383 .kind = "bpf", 384 .type = TCA_ACT_BPF, 385 .owner = THIS_MODULE, 386 .act = tcf_bpf, 387 .dump = tcf_bpf_dump, 388 .cleanup = tcf_bpf_cleanup, 389 .init = tcf_bpf_init, 390 .walk = tcf_bpf_walker, 391 .lookup = tcf_bpf_search, 392 .size = sizeof(struct tcf_bpf), 393 }; 394 395 static __net_init int bpf_init_net(struct net *net) 396 { 397 struct tc_action_net *tn = net_generic(net, bpf_net_id); 398 399 return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK); 400 } 401 402 static void __net_exit bpf_exit_net(struct net *net) 403 { 404 struct tc_action_net *tn = net_generic(net, bpf_net_id); 405 406 tc_action_net_exit(tn); 407 } 408 409 static struct pernet_operations bpf_net_ops = { 410 .init = bpf_init_net, 411 .exit = bpf_exit_net, 412 .id = &bpf_net_id, 413 .size = sizeof(struct tc_action_net), 414 }; 415 416 static int __init bpf_init_module(void) 417 { 418 return tcf_register_action(&act_bpf_ops, &bpf_net_ops); 419 } 420 421 static void __exit bpf_cleanup_module(void) 422 { 423 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops); 424 } 425 426 module_init(bpf_init_module); 427 module_exit(bpf_cleanup_module); 428 429 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 430 MODULE_DESCRIPTION("TC BPF based action"); 431 MODULE_LICENSE("GPL v2"); 432