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 bool at_ingress = skb_at_tc_ingress(skb); 43 struct tcf_bpf *prog = to_bpf(act); 44 struct bpf_prog *filter; 45 int action, filter_res; 46 47 tcf_lastuse_update(&prog->tcf_tm); 48 bstats_cpu_update(this_cpu_ptr(prog->common.cpu_bstats), skb); 49 50 rcu_read_lock(); 51 filter = rcu_dereference(prog->filter); 52 if (at_ingress) { 53 __skb_push(skb, skb->mac_len); 54 bpf_compute_data_end(skb); 55 filter_res = BPF_PROG_RUN(filter, skb); 56 __skb_pull(skb, skb->mac_len); 57 } else { 58 bpf_compute_data_end(skb); 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 = to_bpf(act); 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 tcf_tm_dump(&tm, &prog->tcf_tm); 156 if (nla_put_64bit(skb, TCA_ACT_BPF_TM, sizeof(tm), &tm, 157 TCA_ACT_BPF_PAD)) 158 goto nla_put_failure; 159 160 return skb->len; 161 162 nla_put_failure: 163 nlmsg_trim(skb, tp); 164 return -1; 165 } 166 167 static const struct nla_policy act_bpf_policy[TCA_ACT_BPF_MAX + 1] = { 168 [TCA_ACT_BPF_PARMS] = { .len = sizeof(struct tc_act_bpf) }, 169 [TCA_ACT_BPF_FD] = { .type = NLA_U32 }, 170 [TCA_ACT_BPF_NAME] = { .type = NLA_NUL_STRING, 171 .len = ACT_BPF_NAME_LEN }, 172 [TCA_ACT_BPF_OPS_LEN] = { .type = NLA_U16 }, 173 [TCA_ACT_BPF_OPS] = { .type = NLA_BINARY, 174 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 175 }; 176 177 static int tcf_bpf_init_from_ops(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 178 { 179 struct sock_filter *bpf_ops; 180 struct sock_fprog_kern fprog_tmp; 181 struct bpf_prog *fp; 182 u16 bpf_size, bpf_num_ops; 183 int ret; 184 185 bpf_num_ops = nla_get_u16(tb[TCA_ACT_BPF_OPS_LEN]); 186 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 187 return -EINVAL; 188 189 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 190 if (bpf_size != nla_len(tb[TCA_ACT_BPF_OPS])) 191 return -EINVAL; 192 193 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 194 if (bpf_ops == NULL) 195 return -ENOMEM; 196 197 memcpy(bpf_ops, nla_data(tb[TCA_ACT_BPF_OPS]), bpf_size); 198 199 fprog_tmp.len = bpf_num_ops; 200 fprog_tmp.filter = bpf_ops; 201 202 ret = bpf_prog_create(&fp, &fprog_tmp); 203 if (ret < 0) { 204 kfree(bpf_ops); 205 return ret; 206 } 207 208 cfg->bpf_ops = bpf_ops; 209 cfg->bpf_num_ops = bpf_num_ops; 210 cfg->filter = fp; 211 cfg->is_ebpf = false; 212 213 return 0; 214 } 215 216 static int tcf_bpf_init_from_efd(struct nlattr **tb, struct tcf_bpf_cfg *cfg) 217 { 218 struct bpf_prog *fp; 219 char *name = NULL; 220 u32 bpf_fd; 221 222 bpf_fd = nla_get_u32(tb[TCA_ACT_BPF_FD]); 223 224 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_ACT); 225 if (IS_ERR(fp)) 226 return PTR_ERR(fp); 227 228 if (tb[TCA_ACT_BPF_NAME]) { 229 name = kmemdup(nla_data(tb[TCA_ACT_BPF_NAME]), 230 nla_len(tb[TCA_ACT_BPF_NAME]), 231 GFP_KERNEL); 232 if (!name) { 233 bpf_prog_put(fp); 234 return -ENOMEM; 235 } 236 } 237 238 cfg->bpf_fd = bpf_fd; 239 cfg->bpf_name = name; 240 cfg->filter = fp; 241 cfg->is_ebpf = true; 242 243 return 0; 244 } 245 246 static void tcf_bpf_cfg_cleanup(const struct tcf_bpf_cfg *cfg) 247 { 248 if (cfg->is_ebpf) 249 bpf_prog_put(cfg->filter); 250 else 251 bpf_prog_destroy(cfg->filter); 252 253 kfree(cfg->bpf_ops); 254 kfree(cfg->bpf_name); 255 } 256 257 static void tcf_bpf_prog_fill_cfg(const struct tcf_bpf *prog, 258 struct tcf_bpf_cfg *cfg) 259 { 260 cfg->is_ebpf = tcf_bpf_is_ebpf(prog); 261 /* updates to prog->filter are prevented, since it's called either 262 * with rtnl lock or during final cleanup in rcu callback 263 */ 264 cfg->filter = rcu_dereference_protected(prog->filter, 1); 265 266 cfg->bpf_ops = prog->bpf_ops; 267 cfg->bpf_name = prog->bpf_name; 268 } 269 270 static int tcf_bpf_init(struct net *net, struct nlattr *nla, 271 struct nlattr *est, struct tc_action **act, 272 int replace, int bind) 273 { 274 struct tc_action_net *tn = net_generic(net, bpf_net_id); 275 struct nlattr *tb[TCA_ACT_BPF_MAX + 1]; 276 struct tcf_bpf_cfg cfg, old; 277 struct tc_act_bpf *parm; 278 struct tcf_bpf *prog; 279 bool is_bpf, is_ebpf; 280 int ret, res = 0; 281 282 if (!nla) 283 return -EINVAL; 284 285 ret = nla_parse_nested(tb, TCA_ACT_BPF_MAX, nla, act_bpf_policy); 286 if (ret < 0) 287 return ret; 288 289 if (!tb[TCA_ACT_BPF_PARMS]) 290 return -EINVAL; 291 292 parm = nla_data(tb[TCA_ACT_BPF_PARMS]); 293 294 if (!tcf_hash_check(tn, parm->index, act, bind)) { 295 ret = tcf_hash_create(tn, parm->index, est, act, 296 &act_bpf_ops, bind, true); 297 if (ret < 0) 298 return ret; 299 300 res = ACT_P_CREATED; 301 } else { 302 /* Don't override defaults. */ 303 if (bind) 304 return 0; 305 306 tcf_hash_release(*act, bind); 307 if (!replace) 308 return -EEXIST; 309 } 310 311 is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; 312 is_ebpf = tb[TCA_ACT_BPF_FD]; 313 314 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) { 315 ret = -EINVAL; 316 goto out; 317 } 318 319 memset(&cfg, 0, sizeof(cfg)); 320 321 ret = is_bpf ? tcf_bpf_init_from_ops(tb, &cfg) : 322 tcf_bpf_init_from_efd(tb, &cfg); 323 if (ret < 0) 324 goto out; 325 326 prog = to_bpf(*act); 327 ASSERT_RTNL(); 328 329 if (res != ACT_P_CREATED) 330 tcf_bpf_prog_fill_cfg(prog, &old); 331 332 prog->bpf_ops = cfg.bpf_ops; 333 prog->bpf_name = cfg.bpf_name; 334 335 if (cfg.bpf_num_ops) 336 prog->bpf_num_ops = cfg.bpf_num_ops; 337 if (cfg.bpf_fd) 338 prog->bpf_fd = cfg.bpf_fd; 339 340 prog->tcf_action = parm->action; 341 rcu_assign_pointer(prog->filter, cfg.filter); 342 343 if (res == ACT_P_CREATED) { 344 tcf_hash_insert(tn, *act); 345 } else { 346 /* make sure the program being replaced is no longer executing */ 347 synchronize_rcu(); 348 tcf_bpf_cfg_cleanup(&old); 349 } 350 351 return res; 352 out: 353 if (res == ACT_P_CREATED) 354 tcf_hash_cleanup(*act, est); 355 356 return ret; 357 } 358 359 static void tcf_bpf_cleanup(struct tc_action *act, int bind) 360 { 361 struct tcf_bpf_cfg tmp; 362 363 tcf_bpf_prog_fill_cfg(to_bpf(act), &tmp); 364 tcf_bpf_cfg_cleanup(&tmp); 365 } 366 367 static int tcf_bpf_walker(struct net *net, struct sk_buff *skb, 368 struct netlink_callback *cb, int type, 369 const struct tc_action_ops *ops) 370 { 371 struct tc_action_net *tn = net_generic(net, bpf_net_id); 372 373 return tcf_generic_walker(tn, skb, cb, type, ops); 374 } 375 376 static int tcf_bpf_search(struct net *net, struct tc_action **a, u32 index) 377 { 378 struct tc_action_net *tn = net_generic(net, bpf_net_id); 379 380 return tcf_hash_search(tn, a, index); 381 } 382 383 static struct tc_action_ops act_bpf_ops __read_mostly = { 384 .kind = "bpf", 385 .type = TCA_ACT_BPF, 386 .owner = THIS_MODULE, 387 .act = tcf_bpf, 388 .dump = tcf_bpf_dump, 389 .cleanup = tcf_bpf_cleanup, 390 .init = tcf_bpf_init, 391 .walk = tcf_bpf_walker, 392 .lookup = tcf_bpf_search, 393 .size = sizeof(struct tcf_bpf), 394 }; 395 396 static __net_init int bpf_init_net(struct net *net) 397 { 398 struct tc_action_net *tn = net_generic(net, bpf_net_id); 399 400 return tc_action_net_init(tn, &act_bpf_ops, BPF_TAB_MASK); 401 } 402 403 static void __net_exit bpf_exit_net(struct net *net) 404 { 405 struct tc_action_net *tn = net_generic(net, bpf_net_id); 406 407 tc_action_net_exit(tn); 408 } 409 410 static struct pernet_operations bpf_net_ops = { 411 .init = bpf_init_net, 412 .exit = bpf_exit_net, 413 .id = &bpf_net_id, 414 .size = sizeof(struct tc_action_net), 415 }; 416 417 static int __init bpf_init_module(void) 418 { 419 return tcf_register_action(&act_bpf_ops, &bpf_net_ops); 420 } 421 422 static void __exit bpf_cleanup_module(void) 423 { 424 tcf_unregister_action(&act_bpf_ops, &bpf_net_ops); 425 } 426 427 module_init(bpf_init_module); 428 module_exit(bpf_cleanup_module); 429 430 MODULE_AUTHOR("Jiri Pirko <jiri@resnulli.us>"); 431 MODULE_DESCRIPTION("TC BPF based action"); 432 MODULE_LICENSE("GPL v2"); 433