1 /* 2 * Berkeley Packet Filter based traffic classifier 3 * 4 * Might be used to classify traffic through flexible, user-defined and 5 * possibly JIT-ed BPF filters for traffic control as an alternative to 6 * ematches. 7 * 8 * (C) 2013 Daniel Borkmann <dborkman@redhat.com> 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14 15 #include <linux/module.h> 16 #include <linux/types.h> 17 #include <linux/skbuff.h> 18 #include <linux/filter.h> 19 #include <linux/bpf.h> 20 21 #include <net/rtnetlink.h> 22 #include <net/pkt_cls.h> 23 #include <net/sock.h> 24 25 MODULE_LICENSE("GPL"); 26 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); 27 MODULE_DESCRIPTION("TC BPF based classifier"); 28 29 #define CLS_BPF_NAME_LEN 256 30 31 struct cls_bpf_head { 32 struct list_head plist; 33 u32 hgen; 34 struct rcu_head rcu; 35 }; 36 37 struct cls_bpf_prog { 38 struct bpf_prog *filter; 39 struct list_head link; 40 struct tcf_result res; 41 bool exts_integrated; 42 struct tcf_exts exts; 43 u32 handle; 44 union { 45 u32 bpf_fd; 46 u16 bpf_num_ops; 47 }; 48 struct sock_filter *bpf_ops; 49 const char *bpf_name; 50 struct tcf_proto *tp; 51 struct rcu_head rcu; 52 }; 53 54 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { 55 [TCA_BPF_CLASSID] = { .type = NLA_U32 }, 56 [TCA_BPF_FLAGS] = { .type = NLA_U32 }, 57 [TCA_BPF_FD] = { .type = NLA_U32 }, 58 [TCA_BPF_NAME] = { .type = NLA_NUL_STRING, .len = CLS_BPF_NAME_LEN }, 59 [TCA_BPF_OPS_LEN] = { .type = NLA_U16 }, 60 [TCA_BPF_OPS] = { .type = NLA_BINARY, 61 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 62 }; 63 64 static int cls_bpf_exec_opcode(int code) 65 { 66 switch (code) { 67 case TC_ACT_OK: 68 case TC_ACT_SHOT: 69 case TC_ACT_STOLEN: 70 case TC_ACT_REDIRECT: 71 case TC_ACT_UNSPEC: 72 return code; 73 default: 74 return TC_ACT_UNSPEC; 75 } 76 } 77 78 static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, 79 struct tcf_result *res) 80 { 81 struct cls_bpf_head *head = rcu_dereference_bh(tp->root); 82 struct cls_bpf_prog *prog; 83 #ifdef CONFIG_NET_CLS_ACT 84 bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS; 85 #else 86 bool at_ingress = false; 87 #endif 88 int ret = -1; 89 90 if (unlikely(!skb_mac_header_was_set(skb))) 91 return -1; 92 93 /* Needed here for accessing maps. */ 94 rcu_read_lock(); 95 list_for_each_entry_rcu(prog, &head->plist, link) { 96 int filter_res; 97 98 qdisc_skb_cb(skb)->tc_classid = prog->res.classid; 99 100 if (at_ingress) { 101 /* It is safe to push/pull even if skb_shared() */ 102 __skb_push(skb, skb->mac_len); 103 filter_res = BPF_PROG_RUN(prog->filter, skb); 104 __skb_pull(skb, skb->mac_len); 105 } else { 106 filter_res = BPF_PROG_RUN(prog->filter, skb); 107 } 108 109 if (prog->exts_integrated) { 110 res->class = prog->res.class; 111 res->classid = qdisc_skb_cb(skb)->tc_classid; 112 113 ret = cls_bpf_exec_opcode(filter_res); 114 if (ret == TC_ACT_UNSPEC) 115 continue; 116 break; 117 } 118 119 if (filter_res == 0) 120 continue; 121 122 *res = prog->res; 123 if (filter_res != -1) 124 res->classid = filter_res; 125 126 ret = tcf_exts_exec(skb, &prog->exts, res); 127 if (ret < 0) 128 continue; 129 130 break; 131 } 132 rcu_read_unlock(); 133 134 return ret; 135 } 136 137 static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog) 138 { 139 return !prog->bpf_ops; 140 } 141 142 static int cls_bpf_init(struct tcf_proto *tp) 143 { 144 struct cls_bpf_head *head; 145 146 head = kzalloc(sizeof(*head), GFP_KERNEL); 147 if (head == NULL) 148 return -ENOBUFS; 149 150 INIT_LIST_HEAD_RCU(&head->plist); 151 rcu_assign_pointer(tp->root, head); 152 153 return 0; 154 } 155 156 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) 157 { 158 tcf_exts_destroy(&prog->exts); 159 160 if (cls_bpf_is_ebpf(prog)) 161 bpf_prog_put(prog->filter); 162 else 163 bpf_prog_destroy(prog->filter); 164 165 kfree(prog->bpf_name); 166 kfree(prog->bpf_ops); 167 kfree(prog); 168 } 169 170 static void __cls_bpf_delete_prog(struct rcu_head *rcu) 171 { 172 struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); 173 174 cls_bpf_delete_prog(prog->tp, prog); 175 } 176 177 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) 178 { 179 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg; 180 181 list_del_rcu(&prog->link); 182 tcf_unbind_filter(tp, &prog->res); 183 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 184 185 return 0; 186 } 187 188 static bool cls_bpf_destroy(struct tcf_proto *tp, bool force) 189 { 190 struct cls_bpf_head *head = rtnl_dereference(tp->root); 191 struct cls_bpf_prog *prog, *tmp; 192 193 if (!force && !list_empty(&head->plist)) 194 return false; 195 196 list_for_each_entry_safe(prog, tmp, &head->plist, link) { 197 list_del_rcu(&prog->link); 198 tcf_unbind_filter(tp, &prog->res); 199 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 200 } 201 202 RCU_INIT_POINTER(tp->root, NULL); 203 kfree_rcu(head, rcu); 204 return true; 205 } 206 207 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) 208 { 209 struct cls_bpf_head *head = rtnl_dereference(tp->root); 210 struct cls_bpf_prog *prog; 211 unsigned long ret = 0UL; 212 213 if (head == NULL) 214 return 0UL; 215 216 list_for_each_entry(prog, &head->plist, link) { 217 if (prog->handle == handle) { 218 ret = (unsigned long) prog; 219 break; 220 } 221 } 222 223 return ret; 224 } 225 226 static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog) 227 { 228 struct sock_filter *bpf_ops; 229 struct sock_fprog_kern fprog_tmp; 230 struct bpf_prog *fp; 231 u16 bpf_size, bpf_num_ops; 232 int ret; 233 234 bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]); 235 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 236 return -EINVAL; 237 238 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 239 if (bpf_size != nla_len(tb[TCA_BPF_OPS])) 240 return -EINVAL; 241 242 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 243 if (bpf_ops == NULL) 244 return -ENOMEM; 245 246 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); 247 248 fprog_tmp.len = bpf_num_ops; 249 fprog_tmp.filter = bpf_ops; 250 251 ret = bpf_prog_create(&fp, &fprog_tmp); 252 if (ret < 0) { 253 kfree(bpf_ops); 254 return ret; 255 } 256 257 prog->bpf_ops = bpf_ops; 258 prog->bpf_num_ops = bpf_num_ops; 259 prog->bpf_name = NULL; 260 prog->filter = fp; 261 262 return 0; 263 } 264 265 static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog) 266 { 267 struct bpf_prog *fp; 268 char *name = NULL; 269 u32 bpf_fd; 270 271 bpf_fd = nla_get_u32(tb[TCA_BPF_FD]); 272 273 fp = bpf_prog_get(bpf_fd); 274 if (IS_ERR(fp)) 275 return PTR_ERR(fp); 276 277 if (fp->type != BPF_PROG_TYPE_SCHED_CLS) { 278 bpf_prog_put(fp); 279 return -EINVAL; 280 } 281 282 if (tb[TCA_BPF_NAME]) { 283 name = kmemdup(nla_data(tb[TCA_BPF_NAME]), 284 nla_len(tb[TCA_BPF_NAME]), 285 GFP_KERNEL); 286 if (!name) { 287 bpf_prog_put(fp); 288 return -ENOMEM; 289 } 290 } 291 292 prog->bpf_ops = NULL; 293 prog->bpf_fd = bpf_fd; 294 prog->bpf_name = name; 295 prog->filter = fp; 296 297 return 0; 298 } 299 300 static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, 301 struct cls_bpf_prog *prog, 302 unsigned long base, struct nlattr **tb, 303 struct nlattr *est, bool ovr) 304 { 305 bool is_bpf, is_ebpf, have_exts = false; 306 struct tcf_exts exts; 307 int ret; 308 309 is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS]; 310 is_ebpf = tb[TCA_BPF_FD]; 311 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) 312 return -EINVAL; 313 314 tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE); 315 ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr); 316 if (ret < 0) 317 return ret; 318 319 if (tb[TCA_BPF_FLAGS]) { 320 u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]); 321 322 if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) { 323 tcf_exts_destroy(&exts); 324 return -EINVAL; 325 } 326 327 have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT; 328 } 329 330 prog->exts_integrated = have_exts; 331 332 ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) : 333 cls_bpf_prog_from_efd(tb, prog); 334 if (ret < 0) { 335 tcf_exts_destroy(&exts); 336 return ret; 337 } 338 339 if (tb[TCA_BPF_CLASSID]) { 340 prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]); 341 tcf_bind_filter(tp, &prog->res, base); 342 } 343 344 tcf_exts_change(tp, &prog->exts, &exts); 345 return 0; 346 } 347 348 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp, 349 struct cls_bpf_head *head) 350 { 351 unsigned int i = 0x80000000; 352 u32 handle; 353 354 do { 355 if (++head->hgen == 0x7FFFFFFF) 356 head->hgen = 1; 357 } while (--i > 0 && cls_bpf_get(tp, head->hgen)); 358 359 if (unlikely(i == 0)) { 360 pr_err("Insufficient number of handles\n"); 361 handle = 0; 362 } else { 363 handle = head->hgen; 364 } 365 366 return handle; 367 } 368 369 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 370 struct tcf_proto *tp, unsigned long base, 371 u32 handle, struct nlattr **tca, 372 unsigned long *arg, bool ovr) 373 { 374 struct cls_bpf_head *head = rtnl_dereference(tp->root); 375 struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg; 376 struct nlattr *tb[TCA_BPF_MAX + 1]; 377 struct cls_bpf_prog *prog; 378 int ret; 379 380 if (tca[TCA_OPTIONS] == NULL) 381 return -EINVAL; 382 383 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy); 384 if (ret < 0) 385 return ret; 386 387 prog = kzalloc(sizeof(*prog), GFP_KERNEL); 388 if (!prog) 389 return -ENOBUFS; 390 391 tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); 392 393 if (oldprog) { 394 if (handle && oldprog->handle != handle) { 395 ret = -EINVAL; 396 goto errout; 397 } 398 } 399 400 if (handle == 0) 401 prog->handle = cls_bpf_grab_new_handle(tp, head); 402 else 403 prog->handle = handle; 404 if (prog->handle == 0) { 405 ret = -EINVAL; 406 goto errout; 407 } 408 409 ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr); 410 if (ret < 0) 411 goto errout; 412 413 if (oldprog) { 414 list_replace_rcu(&oldprog->link, &prog->link); 415 tcf_unbind_filter(tp, &oldprog->res); 416 call_rcu(&oldprog->rcu, __cls_bpf_delete_prog); 417 } else { 418 list_add_rcu(&prog->link, &head->plist); 419 } 420 421 *arg = (unsigned long) prog; 422 return 0; 423 errout: 424 kfree(prog); 425 426 return ret; 427 } 428 429 static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog, 430 struct sk_buff *skb) 431 { 432 struct nlattr *nla; 433 434 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops)) 435 return -EMSGSIZE; 436 437 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops * 438 sizeof(struct sock_filter)); 439 if (nla == NULL) 440 return -EMSGSIZE; 441 442 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 443 444 return 0; 445 } 446 447 static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog, 448 struct sk_buff *skb) 449 { 450 if (nla_put_u32(skb, TCA_BPF_FD, prog->bpf_fd)) 451 return -EMSGSIZE; 452 453 if (prog->bpf_name && 454 nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name)) 455 return -EMSGSIZE; 456 457 return 0; 458 } 459 460 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 461 struct sk_buff *skb, struct tcmsg *tm) 462 { 463 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh; 464 struct nlattr *nest; 465 u32 bpf_flags = 0; 466 int ret; 467 468 if (prog == NULL) 469 return skb->len; 470 471 tm->tcm_handle = prog->handle; 472 473 nest = nla_nest_start(skb, TCA_OPTIONS); 474 if (nest == NULL) 475 goto nla_put_failure; 476 477 if (prog->res.classid && 478 nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) 479 goto nla_put_failure; 480 481 if (cls_bpf_is_ebpf(prog)) 482 ret = cls_bpf_dump_ebpf_info(prog, skb); 483 else 484 ret = cls_bpf_dump_bpf_info(prog, skb); 485 if (ret) 486 goto nla_put_failure; 487 488 if (tcf_exts_dump(skb, &prog->exts) < 0) 489 goto nla_put_failure; 490 491 if (prog->exts_integrated) 492 bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT; 493 if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags)) 494 goto nla_put_failure; 495 496 nla_nest_end(skb, nest); 497 498 if (tcf_exts_dump_stats(skb, &prog->exts) < 0) 499 goto nla_put_failure; 500 501 return skb->len; 502 503 nla_put_failure: 504 nla_nest_cancel(skb, nest); 505 return -1; 506 } 507 508 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) 509 { 510 struct cls_bpf_head *head = rtnl_dereference(tp->root); 511 struct cls_bpf_prog *prog; 512 513 list_for_each_entry(prog, &head->plist, link) { 514 if (arg->count < arg->skip) 515 goto skip; 516 if (arg->fn(tp, (unsigned long) prog, arg) < 0) { 517 arg->stop = 1; 518 break; 519 } 520 skip: 521 arg->count++; 522 } 523 } 524 525 static struct tcf_proto_ops cls_bpf_ops __read_mostly = { 526 .kind = "bpf", 527 .owner = THIS_MODULE, 528 .classify = cls_bpf_classify, 529 .init = cls_bpf_init, 530 .destroy = cls_bpf_destroy, 531 .get = cls_bpf_get, 532 .change = cls_bpf_change, 533 .delete = cls_bpf_delete, 534 .walk = cls_bpf_walk, 535 .dump = cls_bpf_dump, 536 }; 537 538 static int __init cls_bpf_init_mod(void) 539 { 540 return register_tcf_proto_ops(&cls_bpf_ops); 541 } 542 543 static void __exit cls_bpf_exit_mod(void) 544 { 545 unregister_tcf_proto_ops(&cls_bpf_ops); 546 } 547 548 module_init(cls_bpf_init_mod); 549 module_exit(cls_bpf_exit_mod); 550