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 ACT_BPF_NAME_LEN 256 25 26 struct tcf_bpf_cfg { 27 struct bpf_prog *filter; 28 struct sock_filter *bpf_ops; 29 const char *bpf_name; 30 u16 bpf_num_ops; 31 bool is_ebpf; 32 }; 33 34 static unsigned int bpf_net_id; 35 static struct tc_action_ops act_bpf_ops; 36 37 static int tcf_bpf_act(struct sk_buff *skb, const struct tc_action *act, 38 struct tcf_result *res) 39 { 40 bool at_ingress = skb_at_tc_ingress(skb); 41 struct tcf_bpf *prog = to_bpf(act); 42 struct bpf_prog *filter; 43 int action, filter_res; 44 45 tcf_lastuse_update(&prog->tcf_tm); 46 bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); 47 48 rcu_read_lock(); 49 filter = rcu_dereference(prog->filter); 50 if (at_ingress) { 51 __skb_push(skb, skb->mac_len); 52 bpf_compute_data_pointers(skb); 53 filter_res = BPF_PROG_RUN(filter, skb); 54 __skb_pull(skb, skb->mac_len); 55 } else { 56 bpf_compute_data_pointers(skb); 57 filter_res = BPF_PROG_RUN(filter, skb); 58 } 59 rcu_read_unlock(); 60 61 /* A BPF program may overwrite the default action opcode. 62 * Similarly as in cls_bpf, if filter_res == -1 we use the 63 * default action specified from tc. 64 * 65 * In case a different well-known TC_ACT opcode has been 66 * returned, it will overwrite the default one. 67 * 68 * For everything else that is unkown, TC_ACT_UNSPEC is 69 * returned. 70 */ 71 switch (filter_res) { 72 case TC_ACT_PIPE: 73 case TC_ACT_RECLASSIFY: 74 case TC_ACT_OK: 75 case TC_ACT_REDIRECT: 76 action = filter_res; 77 break; 78 case TC_ACT_SHOT: 79 action = filter_res; 80 qstats_drop_inc(this_cpu_ptr(prog->common.cpu_qstats)); 81 break; 82 case TC_ACT_UNSPEC: 83 action = prog->tcf_action; 84 break; 85 default: 86 action = TC_ACT_UNSPEC; 87 break; 88 } 89 90 return action; 91 } 92 93 static bool tcf_bpf_is_ebpf(const struct tcf_bpf *prog) 94 { 95 return !prog->bpf_ops; 96 } 97 98 static int tcf_bpf_dump_bpf_info(const struct tcf_bpf *prog, 99 struct sk_buff *skb) 100 { 101 struct nlattr *nla; 102 103 if (nla_put_u16(skb, TCA_ACT_BPF_OPS_LEN, prog->bpf_num_ops)) 104 return -EMSGSIZE; 105 106 nla = nla_reserve(skb, TCA_ACT_BPF_OPS, prog->bpf_num_ops * 107 sizeof(struct sock_filter)); 108 if (nla == NULL) 109 return -EMSGSIZE; 110 111 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 112 113 return 0; 114 } 115 116 static int tcf_bpf_dump_ebpf_info(const struct tcf_bpf *prog, 117 struct sk_buff *skb) 118 { 119 struct nlattr *nla; 120 121 if (prog->bpf_name && 122 nla_put_string(skb, TCA_ACT_BPF_NAME, prog->bpf_name)) 123 return -EMSGSIZE; 124 125 if (nla_put_u32(skb, TCA_ACT_BPF_ID, prog->filter->aux->id)) 126 return -EMSGSIZE; 127 128 nla = nla_reserve(skb, TCA_ACT_BPF_TAG, sizeof(prog->filter->tag)); 129 if (nla == NULL) 130 return -EMSGSIZE; 131 132 memcpy(nla_data(nla), prog->filter->tag, nla_len(nla)); 133 134 return 0; 135 } 136 137 static int tcf_bpf_dump(struct sk_buff *skb, struct tc_action *act, 138 int bind, int ref) 139 { 140 unsigned char *tp = skb_tail_pointer(skb); 141 struct tcf_bpf *prog = to_bpf(act); 142 struct tc_act_bpf opt = { 143 .index = prog->tcf_index, 144 .refcnt = refcount_read(&prog->tcf_refcnt) - ref, 145 .bindcnt = atomic_read(&prog->tcf_bindcnt) - bind, 146 }; 147 struct tcf_t tm; 148 int ret; 149 150 spin_lock_bh(&prog->tcf_lock); 151 opt.action = prog->tcf_action; 152 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt)) 153 goto nla_put_failure; 154 155 if (tcf_bpf_is_ebpf(prog)) 156 ret = tcf_bpf_dump_ebpf_info(prog, skb); 157 else 158 ret = tcf_bpf_dump_bpf_info(prog, skb); 159 if (ret) 160 goto nla_put_failure; 161 162 tcf_tm_dump(&tm, &prog->tcf_tm); 163 if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm, 164 TCA_ACT_BPF_PAD)) 165 goto nla_put_failure; 166 167 spin_unlock_bh(&prog->tcf_lock); 168 return skb->len; 169 170 nla_put_failure: 171 spin_unlock_bh(&prog->tcf_lock); 172 nlmsg_trim(skb, tp); 173 return -1; 174 } 175 176 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 177 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 178 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 179 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, 180 .len = ACT_BPF_NAME_LEN }, 181 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 182 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 183 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 184 }; 185 186 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 187 { 188 struct sock_filter *bpf_ops; 189 struct sock_fprog_kern fprog_tmp; 190 struct bpf_prog *fp; 191 u16 bpf_size, bpf_num_ops; 192 int ret; 193 194 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 195 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 196 return -EINVAL; 197 198 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 199 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 200 return -EINVAL; 201 202 bpf_ops = kmemdup(nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size, GFP_KERNEL); 203 if (bpf_ops == NULL) 204 return -ENOMEM; 205 206 fprog_tmp.len = bpf_num_ops; 207 fprog_tmp.filter = bpf_ops; 208 209 ret = bpf_prog_create(&fp, &fprog_tmp); 210 if (ret < 0) { 211 kfree(bpf_ops); 212 return ret; 213 } 214 215 cfg->bpf_ops = bpf_ops; 216 cfg->bpf_num_ops = bpf_num_ops; 217 cfg->filter = fp; 218 cfg->is_ebpf = false; 219 220 return 0; 221 } 222 223 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 224 { 225 struct bpf_prog *fp; 226 char *name = NULL; 227 u32 bpf_fd; 228 229 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 230 231 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT); 232 if (IS_ERR(fp)) 233 return PTR_ERR(fp); 234 235 if (tb[TCA_ACT_BPF_NAME]) { 236 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL); 237 if (!name) { 238 bpf_prog_put(fp); 239 return -ENOMEM; 240 } 241 } 242 243 cfg->bpf_name = name; 244 cfg->filter = fp; 245 cfg->is_ebpf = true; 246 247 return 0; 248 } 249 250 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) 251 { 252 struct bpf_prog *filter = cfg->filter; 253 254 if (filter) { 255 if (cfg->is_ebpf) 256 bpf_prog_put(filter); 257 else 258 bpf_prog_destroy(filter); 259 } 260 261 kfree(cfg->bpf_ops); 262 kfree(cfg->bpf_name); 263 } 264 265 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, 266 struct tcf_bpf_cfg *cfg) 267 { 268 cfg->is_ebpf = tcf_bpf_is_ebpf(prog); 269 /* updates to prog->filter are prevented, since it's called either 270 * with tcf lock or during final cleanup in rcu callback 271 */ 272 cfg->filter = rcu_dereference_protected(prog->filter, 1); 273 274 cfg->bpf_ops = prog->bpf_ops; 275 cfg->bpf_name = prog->bpf_name; 276 } 277 278 static int tcf_bpf_init(struct net *net, struct nlattr *nla, 279 struct nlattr *est, struct tc_action **act, 280 int replace, int bind, bool rtnl_held, 281 struct netlink_ext_ack *extack) 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, NULL); 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 ret = tcf_idr_check_alloc(tn, &parm->index, act, bind); 304 if (!ret) { 305 ret = tcf_idr_create(tn, parm->index, est, act, 306 &act_bpf_ops, bind, true); 307 if (ret < 0) { 308 tcf_idr_cleanup(tn, parm->index); 309 return ret; 310 } 311 312 res = ACT_P_CREATED; 313 } else if (ret > 0) { 314 /* Don't override defaults. */ 315 if (bind) 316 return 0; 317 318 if (!replace) { 319 tcf_idr_release(*act, bind); 320 return -EEXIST; 321 } 322 } else { 323 return ret; 324 } 325 326 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 327 is_ebpf = tb[TCA_ACT_BPF_FD]; 328 329 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 330 ret = -EINVAL; 331 goto out; 332 } 333 334 memset(&cfg, 0, sizeof(cfg)); 335 336 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 337 tcf_bpf_init_from_efd(tb, &cfg); 338 if (ret < 0) 339 goto out; 340 341 prog = to_bpf(*act); 342 343 spin_lock_bh(&prog->tcf_lock); 344 if (res != ACT_P_CREATED) 345 tcf_bpf_prog_fill_cfg(prog, &old); 346 347 prog->bpf_ops = cfg.bpf_ops; 348 prog->bpf_name = cfg.bpf_name; 349 350 if (cfg.bpf_num_ops) 351 prog->bpf_num_ops = cfg.bpf_num_ops; 352 353 prog->tcf_action = parm->action; 354 rcu_assign_pointer(prog->filter, cfg.filter); 355 spin_unlock_bh(&prog->tcf_lock); 356 357 if (res == ACT_P_CREATED) { 358 tcf_idr_insert(tn, *act); 359 } else { 360 /* make sure the program being replaced is no longer executing */ 361 synchronize_rcu(); 362 tcf_bpf_cfg_cleanup(&old); 363 } 364 365 return res; 366 out: 367 tcf_idr_release(*act, bind); 368 369 return ret; 370 } 371 372 static void tcf_bpf_cleanup(struct tc_action *act) 373 { 374 struct tcf_bpf_cfg tmp; 375 376 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp); 377 tcf_bpf_cfg_cleanup(&tmp); 378 } 379 380 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 381 struct netlink_callback *cb, int type, 382 const struct tc_action_ops *ops, 383 struct netlink_ext_ack *extack) 384 { 385 struct tc_action_net *tn = net_generic(net, bpf_net_id); 386 387 return tcf_generic_walker(tn, skb, cb, type, ops, extack); 388 } 389 390 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index) 391 { 392 struct tc_action_net *tn = net_generic(net, bpf_net_id); 393 394 return tcf_idr_search(tn, a, index); 395 } 396 397 static struct tc_action_ops act_bpf_ops __read_mostly = { 398 .kind = "bpf", 399 .type = TCA_ACT_BPF, 400 .owner = THIS_MODULE, 401 .act = tcf_bpf_act, 402 .dump = tcf_bpf_dump, 403 .cleanup = tcf_bpf_cleanup, 404 .init = tcf_bpf_init, 405 .walk = tcf_bpf_walker, 406 .lookup = tcf_bpf_search, 407 .size = sizeof(struct tcf_bpf), 408 }; 409 410 static __net_init int bpf_init_net(struct net *net) 411 { 412 struct tc_action_net *tn = net_generic(net, bpf_net_id); 413 414 return tc_action_net_init(tn, &act_bpf_ops); 415 } 416 417 static void __net_exit bpf_exit_net(struct list_head *net_list) 418 { 419 tc_action_net_exit(net_list, bpf_net_id); 420 } 421 422 static struct pernet_operations bpf_net_ops = { 423 .init = bpf_init_net, 424 .exit_batch = bpf_exit_net, 425 .id = &bpf_net_id, 426 .size = sizeof(struct tc_action_net), 427 }; 428 429 static int __init bpf_init_module(void) 430 { 431 return tcf_register_action(&act_bpf_ops, &bpf_net_ops); 432 } 433 434 static void __exit bpf_cleanup_module(void) 435 { 436 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops); 437 } 438 439 module_init(bpf_init_module); 440 module_exit(bpf_cleanup_module); 441 442 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 443 MODULE_DESCRIPTION("TC BPF based action"); 444 MODULE_LICENSE("GPL v2"); 445