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(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 = prog->tcf_refcnt - ref, 145 .bindcnt = prog->tcf_bindcnt - bind, 146 .action = prog->tcf_action, 147 }; 148 struct tcf_t tm; 149 int ret; 150 151 if (nla_put(skb, TCA_ACT_BPF_PARMS, sizeof(opt), &opt)) 152 goto nla_put_failure; 153 154 if (tcf_bpf_is_ebpf(prog)) 155 ret = tcf_bpf_dump_ebpf_info(prog, skb); 156 else 157 ret = tcf_bpf_dump_bpf_info(prog, skb); 158 if (ret) 159 goto nla_put_failure; 160 161 tcf_tm_dump(&tm, &prog->tcf_tm); 162 if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm, 163 TCA_ACT_BPF_PAD)) 164 goto nla_put_failure; 165 166 return skb->len; 167 168 nla_put_failure: 169 nlmsg_trim(skb, tp); 170 return -1; 171 } 172 173 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 174 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 175 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 176 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, 177 .len = ACT_BPF_NAME_LEN }, 178 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 179 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 180 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 181 }; 182 183 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 184 { 185 struct sock_filter *bpf_ops; 186 struct sock_fprog_kern fprog_tmp; 187 struct bpf_prog *fp; 188 u16 bpf_size, bpf_num_ops; 189 int ret; 190 191 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 192 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 193 return -EINVAL; 194 195 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 196 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 197 return -EINVAL; 198 199 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 200 if (bpf_ops == NULL) 201 return -ENOMEM; 202 203 memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size); 204 205 fprog_tmp.len = bpf_num_ops; 206 fprog_tmp.filter = bpf_ops; 207 208 ret = bpf_prog_create(&fp, &fprog_tmp); 209 if (ret < 0) { 210 kfree(bpf_ops); 211 return ret; 212 } 213 214 cfg->bpf_ops = bpf_ops; 215 cfg->bpf_num_ops = bpf_num_ops; 216 cfg->filter = fp; 217 cfg->is_ebpf = false; 218 219 return 0; 220 } 221 222 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 223 { 224 struct bpf_prog *fp; 225 char *name = NULL; 226 u32 bpf_fd; 227 228 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 229 230 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT); 231 if (IS_ERR(fp)) 232 return PTR_ERR(fp); 233 234 if (tb[TCA_ACT_BPF_NAME]) { 235 name = nla_memdup(tb[TCA_ACT_BPF_NAME], GFP_KERNEL); 236 if (!name) { 237 bpf_prog_put(fp); 238 return -ENOMEM; 239 } 240 } 241 242 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, NULL); 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_idr_check(tn, parm->index, act, bind)) { 298 ret = tcf_idr_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_idr_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; 340 341 prog->tcf_action = parm->action; 342 rcu_assign_pointer(prog->filter, cfg.filter); 343 344 if (res == ACT_P_CREATED) { 345 tcf_idr_insert(tn, *act); 346 } else { 347 /* make sure the program being replaced is no longer executing */ 348 synchronize_rcu(); 349 tcf_bpf_cfg_cleanup(&old); 350 } 351 352 return res; 353 out: 354 if (res == ACT_P_CREATED) 355 tcf_idr_cleanup(*act, est); 356 357 return ret; 358 } 359 360 static void tcf_bpf_cleanup(struct tc_action *act) 361 { 362 struct tcf_bpf_cfg tmp; 363 364 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp); 365 tcf_bpf_cfg_cleanup(&tmp); 366 } 367 368 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 369 struct netlink_callback *cb, int type, 370 const struct tc_action_ops *ops) 371 { 372 struct tc_action_net *tn = net_generic(net, bpf_net_id); 373 374 return tcf_generic_walker(tn, skb, cb, type, ops); 375 } 376 377 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index) 378 { 379 struct tc_action_net *tn = net_generic(net, bpf_net_id); 380 381 return tcf_idr_search(tn, a, index); 382 } 383 384 static struct tc_action_ops act_bpf_ops __read_mostly = { 385 .kind = "bpf", 386 .type = TCA_ACT_BPF, 387 .owner = THIS_MODULE, 388 .act = tcf_bpf, 389 .dump = tcf_bpf_dump, 390 .cleanup = tcf_bpf_cleanup, 391 .init = tcf_bpf_init, 392 .walk = tcf_bpf_walker, 393 .lookup = tcf_bpf_search, 394 .size = sizeof(struct tcf_bpf), 395 }; 396 397 static __net_init int bpf_init_net(struct net *net) 398 { 399 struct tc_action_net *tn = net_generic(net, bpf_net_id); 400 401 return tc_action_net_init(tn, &act_bpf_ops); 402 } 403 404 static void __net_exit bpf_exit_net(struct list_head *net_list) 405 { 406 tc_action_net_exit(net_list, bpf_net_id); 407 } 408 409 static struct pernet_operations bpf_net_ops = { 410 .init = bpf_init_net, 411 .exit_batch = 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