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 bpf_compute_data_end(skb); 100 filter_res = BPF_PROG_RUN(prog->filter, skb); 101 __skb_pull(skb, skb->mac_len); 102 } else { 103 bpf_compute_data_end(skb); 104 filter_res = BPF_PROG_RUN(prog->filter, skb); 105 } 106 107 if (prog->exts_integrated) { 108 res->class = 0; 109 res->classid = TC_H_MAJ(prog->res.classid) | 110 qdisc_skb_cb(skb)->tc_classid; 111 112 ret = cls_bpf_exec_opcode(filter_res); 113 if (ret == TC_ACT_UNSPEC) 114 continue; 115 break; 116 } 117 118 if (filter_res == 0) 119 continue; 120 if (filter_res != -1) { 121 res->class = 0; 122 res->classid = filter_res; 123 } else { 124 *res = prog->res; 125 } 126 127 ret = tcf_exts_exec(skb, &prog->exts, res); 128 if (ret < 0) 129 continue; 130 131 break; 132 } 133 rcu_read_unlock(); 134 135 return ret; 136 } 137 138 static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog) 139 { 140 return !prog->bpf_ops; 141 } 142 143 static int cls_bpf_init(struct tcf_proto *tp) 144 { 145 struct cls_bpf_head *head; 146 147 head = kzalloc(sizeof(*head), GFP_KERNEL); 148 if (head == NULL) 149 return -ENOBUFS; 150 151 INIT_LIST_HEAD_RCU(&head->plist); 152 rcu_assign_pointer(tp->root, head); 153 154 return 0; 155 } 156 157 static void cls_bpf_delete_prog(struct tcf_proto *tp, struct cls_bpf_prog *prog) 158 { 159 tcf_exts_destroy(&prog->exts); 160 161 if (cls_bpf_is_ebpf(prog)) 162 bpf_prog_put(prog->filter); 163 else 164 bpf_prog_destroy(prog->filter); 165 166 kfree(prog->bpf_name); 167 kfree(prog->bpf_ops); 168 kfree(prog); 169 } 170 171 static void __cls_bpf_delete_prog(struct rcu_head *rcu) 172 { 173 struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); 174 175 cls_bpf_delete_prog(prog->tp, prog); 176 } 177 178 static int cls_bpf_delete(struct tcf_proto *tp, unsigned long arg) 179 { 180 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) arg; 181 182 list_del_rcu(&prog->link); 183 tcf_unbind_filter(tp, &prog->res); 184 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 185 186 return 0; 187 } 188 189 static bool cls_bpf_destroy(struct tcf_proto *tp, bool force) 190 { 191 struct cls_bpf_head *head = rtnl_dereference(tp->root); 192 struct cls_bpf_prog *prog, *tmp; 193 194 if (!force && !list_empty(&head->plist)) 195 return false; 196 197 list_for_each_entry_safe(prog, tmp, &head->plist, link) { 198 list_del_rcu(&prog->link); 199 tcf_unbind_filter(tp, &prog->res); 200 call_rcu(&prog->rcu, __cls_bpf_delete_prog); 201 } 202 203 RCU_INIT_POINTER(tp->root, NULL); 204 kfree_rcu(head, rcu); 205 return true; 206 } 207 208 static unsigned long cls_bpf_get(struct tcf_proto *tp, u32 handle) 209 { 210 struct cls_bpf_head *head = rtnl_dereference(tp->root); 211 struct cls_bpf_prog *prog; 212 unsigned long ret = 0UL; 213 214 if (head == NULL) 215 return 0UL; 216 217 list_for_each_entry(prog, &head->plist, link) { 218 if (prog->handle == handle) { 219 ret = (unsigned long) prog; 220 break; 221 } 222 } 223 224 return ret; 225 } 226 227 static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog) 228 { 229 struct sock_filter *bpf_ops; 230 struct sock_fprog_kern fprog_tmp; 231 struct bpf_prog *fp; 232 u16 bpf_size, bpf_num_ops; 233 int ret; 234 235 bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]); 236 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 237 return -EINVAL; 238 239 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 240 if (bpf_size != nla_len(tb[TCA_BPF_OPS])) 241 return -EINVAL; 242 243 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 244 if (bpf_ops == NULL) 245 return -ENOMEM; 246 247 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); 248 249 fprog_tmp.len = bpf_num_ops; 250 fprog_tmp.filter = bpf_ops; 251 252 ret = bpf_prog_create(&fp, &fprog_tmp); 253 if (ret < 0) { 254 kfree(bpf_ops); 255 return ret; 256 } 257 258 prog->bpf_ops = bpf_ops; 259 prog->bpf_num_ops = bpf_num_ops; 260 prog->bpf_name = NULL; 261 prog->filter = fp; 262 263 return 0; 264 } 265 266 static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog, 267 const struct tcf_proto *tp) 268 { 269 struct bpf_prog *fp; 270 char *name = NULL; 271 u32 bpf_fd; 272 273 bpf_fd = nla_get_u32(tb[TCA_BPF_FD]); 274 275 fp = bpf_prog_get_type(bpf_fd, BPF_PROG_TYPE_SCHED_CLS); 276 if (IS_ERR(fp)) 277 return PTR_ERR(fp); 278 279 if (tb[TCA_BPF_NAME]) { 280 name = kmemdup(nla_data(tb[TCA_BPF_NAME]), 281 nla_len(tb[TCA_BPF_NAME]), 282 GFP_KERNEL); 283 if (!name) { 284 bpf_prog_put(fp); 285 return -ENOMEM; 286 } 287 } 288 289 prog->bpf_ops = NULL; 290 prog->bpf_fd = bpf_fd; 291 prog->bpf_name = name; 292 prog->filter = fp; 293 294 if (fp->dst_needed && !(tp->q->flags & TCQ_F_INGRESS)) 295 netif_keep_dst(qdisc_dev(tp->q)); 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 ret = tcf_exts_init(&exts, TCA_BPF_ACT, TCA_BPF_POLICE); 315 if (ret < 0) 316 return ret; 317 ret = tcf_exts_validate(net, tp, tb, est, &exts, ovr); 318 if (ret < 0) 319 goto errout; 320 321 if (tb[TCA_BPF_FLAGS]) { 322 u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]); 323 324 if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) { 325 ret = -EINVAL; 326 goto errout; 327 } 328 329 have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT; 330 } 331 332 prog->exts_integrated = have_exts; 333 334 ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) : 335 cls_bpf_prog_from_efd(tb, prog, tp); 336 if (ret < 0) 337 goto errout; 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 errout: 348 tcf_exts_destroy(&exts); 349 return ret; 350 } 351 352 static u32 cls_bpf_grab_new_handle(struct tcf_proto *tp, 353 struct cls_bpf_head *head) 354 { 355 unsigned int i = 0x80000000; 356 u32 handle; 357 358 do { 359 if (++head->hgen == 0x7FFFFFFF) 360 head->hgen = 1; 361 } while (--i > 0 && cls_bpf_get(tp, head->hgen)); 362 363 if (unlikely(i == 0)) { 364 pr_err("Insufficient number of handles\n"); 365 handle = 0; 366 } else { 367 handle = head->hgen; 368 } 369 370 return handle; 371 } 372 373 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 374 struct tcf_proto *tp, unsigned long base, 375 u32 handle, struct nlattr **tca, 376 unsigned long *arg, bool ovr) 377 { 378 struct cls_bpf_head *head = rtnl_dereference(tp->root); 379 struct cls_bpf_prog *oldprog = (struct cls_bpf_prog *) *arg; 380 struct nlattr *tb[TCA_BPF_MAX + 1]; 381 struct cls_bpf_prog *prog; 382 int ret; 383 384 if (tca[TCA_OPTIONS] == NULL) 385 return -EINVAL; 386 387 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy); 388 if (ret < 0) 389 return ret; 390 391 prog = kzalloc(sizeof(*prog), GFP_KERNEL); 392 if (!prog) 393 return -ENOBUFS; 394 395 ret = tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); 396 if (ret < 0) 397 goto errout; 398 399 if (oldprog) { 400 if (handle && oldprog->handle != handle) { 401 ret = -EINVAL; 402 goto errout; 403 } 404 } 405 406 if (handle == 0) 407 prog->handle = cls_bpf_grab_new_handle(tp, head); 408 else 409 prog->handle = handle; 410 if (prog->handle == 0) { 411 ret = -EINVAL; 412 goto errout; 413 } 414 415 ret = cls_bpf_modify_existing(net, tp, prog, base, tb, tca[TCA_RATE], ovr); 416 if (ret < 0) 417 goto errout; 418 419 if (oldprog) { 420 list_replace_rcu(&oldprog->link, &prog->link); 421 tcf_unbind_filter(tp, &oldprog->res); 422 call_rcu(&oldprog->rcu, __cls_bpf_delete_prog); 423 } else { 424 list_add_rcu(&prog->link, &head->plist); 425 } 426 427 *arg = (unsigned long) prog; 428 return 0; 429 430 errout: 431 tcf_exts_destroy(&prog->exts); 432 kfree(prog); 433 return ret; 434 } 435 436 static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog, 437 struct sk_buff *skb) 438 { 439 struct nlattr *nla; 440 441 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops)) 442 return -EMSGSIZE; 443 444 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops * 445 sizeof(struct sock_filter)); 446 if (nla == NULL) 447 return -EMSGSIZE; 448 449 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 450 451 return 0; 452 } 453 454 static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog, 455 struct sk_buff *skb) 456 { 457 if (nla_put_u32(skb, TCA_BPF_FD, prog->bpf_fd)) 458 return -EMSGSIZE; 459 460 if (prog->bpf_name && 461 nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name)) 462 return -EMSGSIZE; 463 464 return 0; 465 } 466 467 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 468 struct sk_buff *skb, struct tcmsg *tm) 469 { 470 struct cls_bpf_prog *prog = (struct cls_bpf_prog *) fh; 471 struct nlattr *nest; 472 u32 bpf_flags = 0; 473 int ret; 474 475 if (prog == NULL) 476 return skb->len; 477 478 tm->tcm_handle = prog->handle; 479 480 nest = nla_nest_start(skb, TCA_OPTIONS); 481 if (nest == NULL) 482 goto nla_put_failure; 483 484 if (prog->res.classid && 485 nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) 486 goto nla_put_failure; 487 488 if (cls_bpf_is_ebpf(prog)) 489 ret = cls_bpf_dump_ebpf_info(prog, skb); 490 else 491 ret = cls_bpf_dump_bpf_info(prog, skb); 492 if (ret) 493 goto nla_put_failure; 494 495 if (tcf_exts_dump(skb, &prog->exts) < 0) 496 goto nla_put_failure; 497 498 if (prog->exts_integrated) 499 bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT; 500 if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags)) 501 goto nla_put_failure; 502 503 nla_nest_end(skb, nest); 504 505 if (tcf_exts_dump_stats(skb, &prog->exts) < 0) 506 goto nla_put_failure; 507 508 return skb->len; 509 510 nla_put_failure: 511 nla_nest_cancel(skb, nest); 512 return -1; 513 } 514 515 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) 516 { 517 struct cls_bpf_head *head = rtnl_dereference(tp->root); 518 struct cls_bpf_prog *prog; 519 520 list_for_each_entry(prog, &head->plist, link) { 521 if (arg->count < arg->skip) 522 goto skip; 523 if (arg->fn(tp, (unsigned long) prog, arg) < 0) { 524 arg->stop = 1; 525 break; 526 } 527 skip: 528 arg->count++; 529 } 530 } 531 532 static struct tcf_proto_ops cls_bpf_ops __read_mostly = { 533 .kind = "bpf", 534 .owner = THIS_MODULE, 535 .classify = cls_bpf_classify, 536 .init = cls_bpf_init, 537 .destroy = cls_bpf_destroy, 538 .get = cls_bpf_get, 539 .change = cls_bpf_change, 540 .delete = cls_bpf_delete, 541 .walk = cls_bpf_walk, 542 .dump = cls_bpf_dump, 543 }; 544 545 static int __init cls_bpf_init_mod(void) 546 { 547 return register_tcf_proto_ops(&cls_bpf_ops); 548 } 549 550 static void __exit cls_bpf_exit_mod(void) 551 { 552 unregister_tcf_proto_ops(&cls_bpf_ops); 553 } 554 555 module_init(cls_bpf_init_mod); 556 module_exit(cls_bpf_exit_mod); 557