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 bool at_ingress = skb_at_tc_ingress(skb); 83 struct cls_bpf_prog *prog; 84 int ret = -1; 85 86 if (unlikely(!skb_mac_header_was_set(skb))) 87 return -1; 88 89 /* Needed here for accessing maps. */ 90 rcu_read_lock(); 91 list_for_each_entry_rcu(prog, &head->plist, link) { 92 int filter_res; 93 94 qdisc_skb_cb(skb)->tc_classid = prog->res.classid; 95 96 if (at_ingress) { 97 /* It is safe to push/pull even if skb_shared() */ 98 __skb_push(skb, skb->mac_len); 99 filter_res = BPF_PROG_RUN(prog->filter, skb); 100 __skb_pull(skb, skb->mac_len); 101 } else { 102 filter_res = BPF_PROG_RUN(prog->filter, skb); 103 } 104 105 if (prog->exts_integrated) { 106 res->class = 0; 107 res->classid = TC_H_MAJ(prog->res.classid) | 108 qdisc_skb_cb(skb)->tc_classid; 109 110 ret = cls_bpf_exec_opcode(filter_res); 111 if (ret == TC_ACT_UNSPEC) 112 continue; 113 break; 114 } 115 116 if (filter_res == 0) 117 continue; 118 if (filter_res != -1) { 119 res->class = 0; 120 res->classid = filter_res; 121 } else { 122 *res = prog->res; 123 } 124 125 ret = tcf_exts_exec(skb, &prog->exts, res); 126 if (ret < 0) 127 continue; 128 129 break; 130 } 131 rcu_read_unlock(); 132 133 return ret; 134 } 135 136 static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog) 137 { 138 return !prog->bpf_ops; 139 } 140 141 static int cls_bpf_init(struct tcf_proto *tp) 142 { 143 struct cls_bpf_head *head; 144 145 head = kzalloc(sizeof(*head), GFP_KERNEL); 146 if (head == NULL) 147 return -ENOBUFS; 148 149 INIT_LIST_HEAD_RCU(&head->plist); 150 rcu_assign_pointer(tp->root, head); 151 152 return 0; 153 } 154 155 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) 156 { 157 tcf_exts_destroy(&prog->exts); 158 159 if (cls_bpf_is_ebpf(prog)) 160 bpf_prog_put(prog->filter); 161 else 162 bpf_prog_destroy(prog->filter); 163 164 kfree(prog->bpf_name); 165 kfree(prog->bpf_ops); 166 kfree(prog); 167 } 168 169 static void __cls_bpf_delete_prog(struct rcu_head *rcu) 170 { 171 struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); 172 173 cls_bpf_delete_prog(prog->tp, prog); 174 } 175 176 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) 177 { 178 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg; 179 180 list_del_rcu(&prog->link); 181 tcf_unbind_filter(tp, &prog->res); 182 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 183 184 return 0; 185 } 186 187 static bool cls_bpf_destroy(struct tcf_proto *tp, bool force) 188 { 189 struct cls_bpf_head *head = rtnl_dereference(tp->root); 190 struct cls_bpf_prog *prog, *tmp; 191 192 if (!force && !list_empty(&head->plist)) 193 return false; 194 195 list_for_each_entry_safe(prog, tmp, &head->plist, link) { 196 list_del_rcu(&prog->link); 197 tcf_unbind_filter(tp, &prog->res); 198 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 199 } 200 201 RCU_INIT_POINTER(tp->root, NULL); 202 kfree_rcu(head, rcu); 203 return true; 204 } 205 206 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) 207 { 208 struct cls_bpf_head *head = rtnl_dereference(tp->root); 209 struct cls_bpf_prog *prog; 210 unsigned long ret = 0UL; 211 212 if (head == NULL) 213 return 0UL; 214 215 list_for_each_entry(prog, &head->plist, link) { 216 if (prog->handle == handle) { 217 ret = (unsigned long) prog; 218 break; 219 } 220 } 221 222 return ret; 223 } 224 225 static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog) 226 { 227 struct sock_filter *bpf_ops; 228 struct sock_fprog_kern fprog_tmp; 229 struct bpf_prog *fp; 230 u16 bpf_size, bpf_num_ops; 231 int ret; 232 233 bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]); 234 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 235 return -EINVAL; 236 237 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 238 if (bpf_size != nla_len(tb[TCA_BPF_OPS])) 239 return -EINVAL; 240 241 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 242 if (bpf_ops == NULL) 243 return -ENOMEM; 244 245 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); 246 247 fprog_tmp.len = bpf_num_ops; 248 fprog_tmp.filter = bpf_ops; 249 250 ret = bpf_prog_create(&fp, &fprog_tmp); 251 if (ret < 0) { 252 kfree(bpf_ops); 253 return ret; 254 } 255 256 prog->bpf_ops = bpf_ops; 257 prog->bpf_num_ops = bpf_num_ops; 258 prog->bpf_name = NULL; 259 prog->filter = fp; 260 261 return 0; 262 } 263 264 static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog, 265 const struct tcf_proto *tp) 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 if (fp->dst_needed && !(tp->q->flags & TCQ_F_INGRESS)) 298 netif_keep_dst(qdisc_dev(tp->q)); 299 300 return 0; 301 } 302 303 static int cls_bpf_modify_existing(struct net *net, struct tcf_proto *tp, 304 struct cls_bpf_prog *prog, 305 unsigned long base, struct nlattr **tb, 306 struct nlattr *est, bool ovr) 307 { 308 bool is_bpf, is_ebpf, have_exts = false; 309 struct tcf_exts exts; 310 int ret; 311 312 is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS]; 313 is_ebpf = tb[TCA_BPF_FD]; 314 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) 315 return -EINVAL; 316 317 tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE); 318 ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr); 319 if (ret < 0) 320 return ret; 321 322 if (tb[TCA_BPF_FLAGS]) { 323 u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]); 324 325 if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) { 326 tcf_exts_destroy(&exts); 327 return -EINVAL; 328 } 329 330 have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT; 331 } 332 333 prog->exts_integrated = have_exts; 334 335 ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) : 336 cls_bpf_prog_from_efd(tb, prog, tp); 337 if (ret < 0) { 338 tcf_exts_destroy(&exts); 339 return ret; 340 } 341 342 if (tb[TCA_BPF_CLASSID]) { 343 prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]); 344 tcf_bind_filter(tp, &prog->res, base); 345 } 346 347 tcf_exts_change(tp, &prog->exts, &exts); 348 return 0; 349 } 350 351 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp, 352 struct cls_bpf_head *head) 353 { 354 unsigned int i = 0x80000000; 355 u32 handle; 356 357 do { 358 if (++head->hgen == 0x7FFFFFFF) 359 head->hgen = 1; 360 } while (--i > 0 && cls_bpf_get(tp, head->hgen)); 361 362 if (unlikely(i == 0)) { 363 pr_err("Insufficient number of handles\n"); 364 handle = 0; 365 } else { 366 handle = head->hgen; 367 } 368 369 return handle; 370 } 371 372 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 373 struct tcf_proto *tp, unsigned long base, 374 u32 handle, struct nlattr **tca, 375 unsigned long *arg, bool ovr) 376 { 377 struct cls_bpf_head *head = rtnl_dereference(tp->root); 378 struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg; 379 struct nlattr *tb[TCA_BPF_MAX + 1]; 380 struct cls_bpf_prog *prog; 381 int ret; 382 383 if (tca[TCA_OPTIONS] == NULL) 384 return -EINVAL; 385 386 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy); 387 if (ret < 0) 388 return ret; 389 390 prog = kzalloc(sizeof(*prog), GFP_KERNEL); 391 if (!prog) 392 return -ENOBUFS; 393 394 tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); 395 396 if (oldprog) { 397 if (handle && oldprog->handle != handle) { 398 ret = -EINVAL; 399 goto errout; 400 } 401 } 402 403 if (handle == 0) 404 prog->handle = cls_bpf_grab_new_handle(tp, head); 405 else 406 prog->handle = handle; 407 if (prog->handle == 0) { 408 ret = -EINVAL; 409 goto errout; 410 } 411 412 ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr); 413 if (ret < 0) 414 goto errout; 415 416 if (oldprog) { 417 list_replace_rcu(&oldprog->link, &prog->link); 418 tcf_unbind_filter(tp, &oldprog->res); 419 call_rcu(&oldprog->rcu, __cls_bpf_delete_prog); 420 } else { 421 list_add_rcu(&prog->link, &head->plist); 422 } 423 424 *arg = (unsigned long) prog; 425 return 0; 426 errout: 427 kfree(prog); 428 429 return ret; 430 } 431 432 static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog, 433 struct sk_buff *skb) 434 { 435 struct nlattr *nla; 436 437 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops)) 438 return -EMSGSIZE; 439 440 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops * 441 sizeof(struct sock_filter)); 442 if (nla == NULL) 443 return -EMSGSIZE; 444 445 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 446 447 return 0; 448 } 449 450 static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog, 451 struct sk_buff *skb) 452 { 453 if (nla_put_u32(skb, TCA_BPF_FD, prog->bpf_fd)) 454 return -EMSGSIZE; 455 456 if (prog->bpf_name && 457 nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name)) 458 return -EMSGSIZE; 459 460 return 0; 461 } 462 463 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 464 struct sk_buff *skb, struct tcmsg *tm) 465 { 466 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh; 467 struct nlattr *nest; 468 u32 bpf_flags = 0; 469 int ret; 470 471 if (prog == NULL) 472 return skb->len; 473 474 tm->tcm_handle = prog->handle; 475 476 nest = nla_nest_start(skb, TCA_OPTIONS); 477 if (nest == NULL) 478 goto nla_put_failure; 479 480 if (prog->res.classid && 481 nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) 482 goto nla_put_failure; 483 484 if (cls_bpf_is_ebpf(prog)) 485 ret = cls_bpf_dump_ebpf_info(prog, skb); 486 else 487 ret = cls_bpf_dump_bpf_info(prog, skb); 488 if (ret) 489 goto nla_put_failure; 490 491 if (tcf_exts_dump(skb, &prog->exts) < 0) 492 goto nla_put_failure; 493 494 if (prog->exts_integrated) 495 bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT; 496 if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags)) 497 goto nla_put_failure; 498 499 nla_nest_end(skb, nest); 500 501 if (tcf_exts_dump_stats(skb, &prog->exts) < 0) 502 goto nla_put_failure; 503 504 return skb->len; 505 506 nla_put_failure: 507 nla_nest_cancel(skb, nest); 508 return -1; 509 } 510 511 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) 512 { 513 struct cls_bpf_head *head = rtnl_dereference(tp->root); 514 struct cls_bpf_prog *prog; 515 516 list_for_each_entry(prog, &head->plist, link) { 517 if (arg->count < arg->skip) 518 goto skip; 519 if (arg->fn(tp, (unsigned long) prog, arg) < 0) { 520 arg->stop = 1; 521 break; 522 } 523 skip: 524 arg->count++; 525 } 526 } 527 528 static struct tcf_proto_ops cls_bpf_ops __read_mostly = { 529 .kind = "bpf", 530 .owner = THIS_MODULE, 531 .classify = cls_bpf_classify, 532 .init = cls_bpf_init, 533 .destroy = cls_bpf_destroy, 534 .get = cls_bpf_get, 535 .change = cls_bpf_change, 536 .delete = cls_bpf_delete, 537 .walk = cls_bpf_walk, 538 .dump = cls_bpf_dump, 539 }; 540 541 static int __init cls_bpf_init_mod(void) 542 { 543 return register_tcf_proto_ops(&cls_bpf_ops); 544 } 545 546 static void __exit cls_bpf_exit_mod(void) 547 { 548 unregister_tcf_proto_ops(&cls_bpf_ops); 549 } 550 551 module_init(cls_bpf_init_mod); 552 module_exit(cls_bpf_exit_mod); 553