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 #include <linux/idr.h> 21 22 #include <net/rtnetlink.h> 23 #include <net/pkt_cls.h> 24 #include <net/sock.h> 25 26 MODULE_LICENSE("GPL"); 27 MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>"); 28 MODULE_DESCRIPTION("TC BPF based classifier"); 29 30 #define CLS_BPF_NAME_LEN 256 31 #define CLS_BPF_SUPPORTED_GEN_FLAGS \ 32 (TCA_CLS_FLAGS_SKIP_HW | TCA_CLS_FLAGS_SKIP_SW) 33 34 struct cls_bpf_head { 35 struct list_head plist; 36 struct idr handle_idr; 37 struct rcu_head rcu; 38 }; 39 40 struct cls_bpf_prog { 41 struct bpf_prog *filter; 42 struct list_head link; 43 struct tcf_result res; 44 bool exts_integrated; 45 u32 gen_flags; 46 struct tcf_exts exts; 47 u32 handle; 48 u16 bpf_num_ops; 49 struct sock_filter *bpf_ops; 50 const char *bpf_name; 51 struct tcf_proto *tp; 52 union { 53 struct work_struct work; 54 struct rcu_head rcu; 55 }; 56 }; 57 58 static const struct nla_policy bpf_policy[TCA_BPF_MAX + 1] = { 59 [TCA_BPF_CLASSID] = { .type = NLA_U32 }, 60 [TCA_BPF_FLAGS] = { .type = NLA_U32 }, 61 [TCA_BPF_FLAGS_GEN] = { .type = NLA_U32 }, 62 [TCA_BPF_FD] = { .type = NLA_U32 }, 63 [TCA_BPF_NAME] = { .type = NLA_NUL_STRING, 64 .len = CLS_BPF_NAME_LEN }, 65 [TCA_BPF_OPS_LEN] = { .type = NLA_U16 }, 66 [TCA_BPF_OPS] = { .type = NLA_BINARY, 67 .len = sizeof(struct sock_filter) * BPF_MAXINSNS }, 68 }; 69 70 static int cls_bpf_exec_opcode(int code) 71 { 72 switch (code) { 73 case TC_ACT_OK: 74 case TC_ACT_SHOT: 75 case TC_ACT_STOLEN: 76 case TC_ACT_TRAP: 77 case TC_ACT_REDIRECT: 78 case TC_ACT_UNSPEC: 79 return code; 80 default: 81 return TC_ACT_UNSPEC; 82 } 83 } 84 85 static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp, 86 struct tcf_result *res) 87 { 88 struct cls_bpf_head *head = rcu_dereference_bh(tp->root); 89 bool at_ingress = skb_at_tc_ingress(skb); 90 struct cls_bpf_prog *prog; 91 int ret = -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 (tc_skip_sw(prog->gen_flags)) { 101 filter_res = prog->exts_integrated ? TC_ACT_UNSPEC : 0; 102 } else if (at_ingress) { 103 /* It is safe to push/pull even if skb_shared() */ 104 __skb_push(skb, skb->mac_len); 105 bpf_compute_data_pointers(skb); 106 filter_res = BPF_PROG_RUN(prog->filter, skb); 107 __skb_pull(skb, skb->mac_len); 108 } else { 109 bpf_compute_data_pointers(skb); 110 filter_res = BPF_PROG_RUN(prog->filter, skb); 111 } 112 113 if (prog->exts_integrated) { 114 res->class = 0; 115 res->classid = TC_H_MAJ(prog->res.classid) | 116 qdisc_skb_cb(skb)->tc_classid; 117 118 ret = cls_bpf_exec_opcode(filter_res); 119 if (ret == TC_ACT_UNSPEC) 120 continue; 121 break; 122 } 123 124 if (filter_res == 0) 125 continue; 126 if (filter_res != -1) { 127 res->class = 0; 128 res->classid = filter_res; 129 } else { 130 *res = prog->res; 131 } 132 133 ret = tcf_exts_exec(skb, &prog->exts, res); 134 if (ret < 0) 135 continue; 136 137 break; 138 } 139 rcu_read_unlock(); 140 141 return ret; 142 } 143 144 static bool cls_bpf_is_ebpf(const struct cls_bpf_prog *prog) 145 { 146 return !prog->bpf_ops; 147 } 148 149 static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog, 150 struct cls_bpf_prog *oldprog) 151 { 152 struct tcf_block *block = tp->chain->block; 153 struct tc_cls_bpf_offload cls_bpf = {}; 154 struct cls_bpf_prog *obj; 155 bool skip_sw; 156 int err; 157 158 skip_sw = prog && tc_skip_sw(prog->gen_flags); 159 obj = prog ?: oldprog; 160 161 tc_cls_common_offload_init(&cls_bpf.common, tp); 162 cls_bpf.command = TC_CLSBPF_OFFLOAD; 163 cls_bpf.exts = &obj->exts; 164 cls_bpf.prog = prog ? prog->filter : NULL; 165 cls_bpf.oldprog = oldprog ? oldprog->filter : NULL; 166 cls_bpf.name = obj->bpf_name; 167 cls_bpf.exts_integrated = obj->exts_integrated; 168 cls_bpf.gen_flags = obj->gen_flags; 169 170 err = tc_setup_cb_call(block, NULL, TC_SETUP_CLSBPF, &cls_bpf, skip_sw); 171 if (prog) { 172 if (err < 0) { 173 cls_bpf_offload_cmd(tp, oldprog, prog); 174 return err; 175 } else if (err > 0) { 176 prog->gen_flags |= TCA_CLS_FLAGS_IN_HW; 177 } 178 } 179 180 if (prog && skip_sw && !(prog->gen_flags & TCA_CLS_FLAGS_IN_HW)) 181 return -EINVAL; 182 183 return 0; 184 } 185 186 static u32 cls_bpf_flags(u32 flags) 187 { 188 return flags & CLS_BPF_SUPPORTED_GEN_FLAGS; 189 } 190 191 static int cls_bpf_offload(struct tcf_proto *tp, struct cls_bpf_prog *prog, 192 struct cls_bpf_prog *oldprog) 193 { 194 if (prog && oldprog && 195 cls_bpf_flags(prog->gen_flags) != 196 cls_bpf_flags(oldprog->gen_flags)) 197 return -EINVAL; 198 199 if (prog && tc_skip_hw(prog->gen_flags)) 200 prog = NULL; 201 if (oldprog && tc_skip_hw(oldprog->gen_flags)) 202 oldprog = NULL; 203 if (!prog && !oldprog) 204 return 0; 205 206 return cls_bpf_offload_cmd(tp, prog, oldprog); 207 } 208 209 static void cls_bpf_stop_offload(struct tcf_proto *tp, 210 struct cls_bpf_prog *prog) 211 { 212 int err; 213 214 err = cls_bpf_offload_cmd(tp, NULL, prog); 215 if (err) 216 pr_err("Stopping hardware offload failed: %d\n", err); 217 } 218 219 static void cls_bpf_offload_update_stats(struct tcf_proto *tp, 220 struct cls_bpf_prog *prog) 221 { 222 struct tcf_block *block = tp->chain->block; 223 struct tc_cls_bpf_offload cls_bpf = {}; 224 225 tc_cls_common_offload_init(&cls_bpf.common, tp); 226 cls_bpf.command = TC_CLSBPF_STATS; 227 cls_bpf.exts = &prog->exts; 228 cls_bpf.prog = prog->filter; 229 cls_bpf.name = prog->bpf_name; 230 cls_bpf.exts_integrated = prog->exts_integrated; 231 cls_bpf.gen_flags = prog->gen_flags; 232 233 tc_setup_cb_call(block, NULL, TC_SETUP_CLSBPF, &cls_bpf, false); 234 } 235 236 static int cls_bpf_init(struct tcf_proto *tp) 237 { 238 struct cls_bpf_head *head; 239 240 head = kzalloc(sizeof(*head), GFP_KERNEL); 241 if (head == NULL) 242 return -ENOBUFS; 243 244 INIT_LIST_HEAD_RCU(&head->plist); 245 idr_init(&head->handle_idr); 246 rcu_assign_pointer(tp->root, head); 247 248 return 0; 249 } 250 251 static void cls_bpf_free_parms(struct cls_bpf_prog *prog) 252 { 253 if (cls_bpf_is_ebpf(prog)) 254 bpf_prog_put(prog->filter); 255 else 256 bpf_prog_destroy(prog->filter); 257 258 kfree(prog->bpf_name); 259 kfree(prog->bpf_ops); 260 } 261 262 static void __cls_bpf_delete_prog(struct cls_bpf_prog *prog) 263 { 264 tcf_exts_destroy(&prog->exts); 265 tcf_exts_put_net(&prog->exts); 266 267 cls_bpf_free_parms(prog); 268 kfree(prog); 269 } 270 271 static void cls_bpf_delete_prog_work(struct work_struct *work) 272 { 273 struct cls_bpf_prog *prog = container_of(work, struct cls_bpf_prog, work); 274 275 rtnl_lock(); 276 __cls_bpf_delete_prog(prog); 277 rtnl_unlock(); 278 } 279 280 static void cls_bpf_delete_prog_rcu(struct rcu_head *rcu) 281 { 282 struct cls_bpf_prog *prog = container_of(rcu, struct cls_bpf_prog, rcu); 283 284 INIT_WORK(&prog->work, cls_bpf_delete_prog_work); 285 tcf_queue_work(&prog->work); 286 } 287 288 static void __cls_bpf_delete(struct tcf_proto *tp, struct cls_bpf_prog *prog) 289 { 290 struct cls_bpf_head *head = rtnl_dereference(tp->root); 291 292 idr_remove_ext(&head->handle_idr, prog->handle); 293 cls_bpf_stop_offload(tp, prog); 294 list_del_rcu(&prog->link); 295 tcf_unbind_filter(tp, &prog->res); 296 if (tcf_exts_get_net(&prog->exts)) 297 call_rcu(&prog->rcu, cls_bpf_delete_prog_rcu); 298 else 299 __cls_bpf_delete_prog(prog); 300 } 301 302 static int cls_bpf_delete(struct tcf_proto *tp, void *arg, bool *last) 303 { 304 struct cls_bpf_head *head = rtnl_dereference(tp->root); 305 306 __cls_bpf_delete(tp, arg); 307 *last = list_empty(&head->plist); 308 return 0; 309 } 310 311 static void cls_bpf_destroy(struct tcf_proto *tp) 312 { 313 struct cls_bpf_head *head = rtnl_dereference(tp->root); 314 struct cls_bpf_prog *prog, *tmp; 315 316 list_for_each_entry_safe(prog, tmp, &head->plist, link) 317 __cls_bpf_delete(tp, prog); 318 319 idr_destroy(&head->handle_idr); 320 kfree_rcu(head, rcu); 321 } 322 323 static void *cls_bpf_get(struct tcf_proto *tp, u32 handle) 324 { 325 struct cls_bpf_head *head = rtnl_dereference(tp->root); 326 struct cls_bpf_prog *prog; 327 328 list_for_each_entry(prog, &head->plist, link) { 329 if (prog->handle == handle) 330 return prog; 331 } 332 333 return NULL; 334 } 335 336 static int cls_bpf_prog_from_ops(struct nlattr **tb, struct cls_bpf_prog *prog) 337 { 338 struct sock_filter *bpf_ops; 339 struct sock_fprog_kern fprog_tmp; 340 struct bpf_prog *fp; 341 u16 bpf_size, bpf_num_ops; 342 int ret; 343 344 bpf_num_ops = nla_get_u16(tb[TCA_BPF_OPS_LEN]); 345 if (bpf_num_ops > BPF_MAXINSNS || bpf_num_ops == 0) 346 return -EINVAL; 347 348 bpf_size = bpf_num_ops * sizeof(*bpf_ops); 349 if (bpf_size != nla_len(tb[TCA_BPF_OPS])) 350 return -EINVAL; 351 352 bpf_ops = kzalloc(bpf_size, GFP_KERNEL); 353 if (bpf_ops == NULL) 354 return -ENOMEM; 355 356 memcpy(bpf_ops, nla_data(tb[TCA_BPF_OPS]), bpf_size); 357 358 fprog_tmp.len = bpf_num_ops; 359 fprog_tmp.filter = bpf_ops; 360 361 ret = bpf_prog_create(&fp, &fprog_tmp); 362 if (ret < 0) { 363 kfree(bpf_ops); 364 return ret; 365 } 366 367 prog->bpf_ops = bpf_ops; 368 prog->bpf_num_ops = bpf_num_ops; 369 prog->bpf_name = NULL; 370 prog->filter = fp; 371 372 return 0; 373 } 374 375 static int cls_bpf_prog_from_efd(struct nlattr **tb, struct cls_bpf_prog *prog, 376 u32 gen_flags, const struct tcf_proto *tp) 377 { 378 struct bpf_prog *fp; 379 char *name = NULL; 380 bool skip_sw; 381 u32 bpf_fd; 382 383 bpf_fd = nla_get_u32(tb[TCA_BPF_FD]); 384 skip_sw = gen_flags & TCA_CLS_FLAGS_SKIP_SW; 385 386 fp = bpf_prog_get_type_dev(bpf_fd, BPF_PROG_TYPE_SCHED_CLS, skip_sw); 387 if (IS_ERR(fp)) 388 return PTR_ERR(fp); 389 390 if (tb[TCA_BPF_NAME]) { 391 name = nla_memdup(tb[TCA_BPF_NAME], GFP_KERNEL); 392 if (!name) { 393 bpf_prog_put(fp); 394 return -ENOMEM; 395 } 396 } 397 398 prog->bpf_ops = NULL; 399 prog->bpf_name = name; 400 prog->filter = fp; 401 402 if (fp->dst_needed && !(tp->q->flags & TCQ_F_INGRESS)) 403 netif_keep_dst(qdisc_dev(tp->q)); 404 405 return 0; 406 } 407 408 static int cls_bpf_set_parms(struct net *net, struct tcf_proto *tp, 409 struct cls_bpf_prog *prog, unsigned long base, 410 struct nlattr **tb, struct nlattr *est, bool ovr) 411 { 412 bool is_bpf, is_ebpf, have_exts = false; 413 u32 gen_flags = 0; 414 int ret; 415 416 is_bpf = tb[TCA_BPF_OPS_LEN] && tb[TCA_BPF_OPS]; 417 is_ebpf = tb[TCA_BPF_FD]; 418 if ((!is_bpf && !is_ebpf) || (is_bpf && is_ebpf)) 419 return -EINVAL; 420 421 ret = tcf_exts_validate(net, tp, tb, est, &prog->exts, ovr); 422 if (ret < 0) 423 return ret; 424 425 if (tb[TCA_BPF_FLAGS]) { 426 u32 bpf_flags = nla_get_u32(tb[TCA_BPF_FLAGS]); 427 428 if (bpf_flags & ~TCA_BPF_FLAG_ACT_DIRECT) 429 return -EINVAL; 430 431 have_exts = bpf_flags & TCA_BPF_FLAG_ACT_DIRECT; 432 } 433 if (tb[TCA_BPF_FLAGS_GEN]) { 434 gen_flags = nla_get_u32(tb[TCA_BPF_FLAGS_GEN]); 435 if (gen_flags & ~CLS_BPF_SUPPORTED_GEN_FLAGS || 436 !tc_flags_valid(gen_flags)) 437 return -EINVAL; 438 } 439 440 prog->exts_integrated = have_exts; 441 prog->gen_flags = gen_flags; 442 443 ret = is_bpf ? cls_bpf_prog_from_ops(tb, prog) : 444 cls_bpf_prog_from_efd(tb, prog, gen_flags, tp); 445 if (ret < 0) 446 return ret; 447 448 if (tb[TCA_BPF_CLASSID]) { 449 prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]); 450 tcf_bind_filter(tp, &prog->res, base); 451 } 452 453 return 0; 454 } 455 456 static int cls_bpf_change(struct net *net, struct sk_buff *in_skb, 457 struct tcf_proto *tp, unsigned long base, 458 u32 handle, struct nlattr **tca, 459 void **arg, bool ovr) 460 { 461 struct cls_bpf_head *head = rtnl_dereference(tp->root); 462 struct cls_bpf_prog *oldprog = *arg; 463 struct nlattr *tb[TCA_BPF_MAX + 1]; 464 struct cls_bpf_prog *prog; 465 unsigned long idr_index; 466 int ret; 467 468 if (tca[TCA_OPTIONS] == NULL) 469 return -EINVAL; 470 471 ret = nla_parse_nested(tb, TCA_BPF_MAX, tca[TCA_OPTIONS], bpf_policy, 472 NULL); 473 if (ret < 0) 474 return ret; 475 476 prog = kzalloc(sizeof(*prog), GFP_KERNEL); 477 if (!prog) 478 return -ENOBUFS; 479 480 ret = tcf_exts_init(&prog->exts, TCA_BPF_ACT, TCA_BPF_POLICE); 481 if (ret < 0) 482 goto errout; 483 484 if (oldprog) { 485 if (handle && oldprog->handle != handle) { 486 ret = -EINVAL; 487 goto errout; 488 } 489 } 490 491 if (handle == 0) { 492 ret = idr_alloc_ext(&head->handle_idr, prog, &idr_index, 493 1, 0x7FFFFFFF, GFP_KERNEL); 494 if (ret) 495 goto errout; 496 prog->handle = idr_index; 497 } else { 498 if (!oldprog) { 499 ret = idr_alloc_ext(&head->handle_idr, prog, &idr_index, 500 handle, handle + 1, GFP_KERNEL); 501 if (ret) 502 goto errout; 503 } 504 prog->handle = handle; 505 } 506 507 ret = cls_bpf_set_parms(net, tp, prog, base, tb, tca[TCA_RATE], ovr); 508 if (ret < 0) 509 goto errout_idr; 510 511 ret = cls_bpf_offload(tp, prog, oldprog); 512 if (ret) 513 goto errout_parms; 514 515 if (!tc_in_hw(prog->gen_flags)) 516 prog->gen_flags |= TCA_CLS_FLAGS_NOT_IN_HW; 517 518 if (oldprog) { 519 idr_replace_ext(&head->handle_idr, prog, handle); 520 list_replace_rcu(&oldprog->link, &prog->link); 521 tcf_unbind_filter(tp, &oldprog->res); 522 tcf_exts_get_net(&oldprog->exts); 523 call_rcu(&oldprog->rcu, cls_bpf_delete_prog_rcu); 524 } else { 525 list_add_rcu(&prog->link, &head->plist); 526 } 527 528 *arg = prog; 529 return 0; 530 531 errout_parms: 532 cls_bpf_free_parms(prog); 533 errout_idr: 534 if (!oldprog) 535 idr_remove_ext(&head->handle_idr, prog->handle); 536 errout: 537 tcf_exts_destroy(&prog->exts); 538 kfree(prog); 539 return ret; 540 } 541 542 static int cls_bpf_dump_bpf_info(const struct cls_bpf_prog *prog, 543 struct sk_buff *skb) 544 { 545 struct nlattr *nla; 546 547 if (nla_put_u16(skb, TCA_BPF_OPS_LEN, prog->bpf_num_ops)) 548 return -EMSGSIZE; 549 550 nla = nla_reserve(skb, TCA_BPF_OPS, prog->bpf_num_ops * 551 sizeof(struct sock_filter)); 552 if (nla == NULL) 553 return -EMSGSIZE; 554 555 memcpy(nla_data(nla), prog->bpf_ops, nla_len(nla)); 556 557 return 0; 558 } 559 560 static int cls_bpf_dump_ebpf_info(const struct cls_bpf_prog *prog, 561 struct sk_buff *skb) 562 { 563 struct nlattr *nla; 564 565 if (prog->bpf_name && 566 nla_put_string(skb, TCA_BPF_NAME, prog->bpf_name)) 567 return -EMSGSIZE; 568 569 if (nla_put_u32(skb, TCA_BPF_ID, prog->filter->aux->id)) 570 return -EMSGSIZE; 571 572 nla = nla_reserve(skb, TCA_BPF_TAG, sizeof(prog->filter->tag)); 573 if (nla == NULL) 574 return -EMSGSIZE; 575 576 memcpy(nla_data(nla), prog->filter->tag, nla_len(nla)); 577 578 return 0; 579 } 580 581 static int cls_bpf_dump(struct net *net, struct tcf_proto *tp, void *fh, 582 struct sk_buff *skb, struct tcmsg *tm) 583 { 584 struct cls_bpf_prog *prog = fh; 585 struct nlattr *nest; 586 u32 bpf_flags = 0; 587 int ret; 588 589 if (prog == NULL) 590 return skb->len; 591 592 tm->tcm_handle = prog->handle; 593 594 cls_bpf_offload_update_stats(tp, prog); 595 596 nest = nla_nest_start(skb, TCA_OPTIONS); 597 if (nest == NULL) 598 goto nla_put_failure; 599 600 if (prog->res.classid && 601 nla_put_u32(skb, TCA_BPF_CLASSID, prog->res.classid)) 602 goto nla_put_failure; 603 604 if (cls_bpf_is_ebpf(prog)) 605 ret = cls_bpf_dump_ebpf_info(prog, skb); 606 else 607 ret = cls_bpf_dump_bpf_info(prog, skb); 608 if (ret) 609 goto nla_put_failure; 610 611 if (tcf_exts_dump(skb, &prog->exts) < 0) 612 goto nla_put_failure; 613 614 if (prog->exts_integrated) 615 bpf_flags |= TCA_BPF_FLAG_ACT_DIRECT; 616 if (bpf_flags && nla_put_u32(skb, TCA_BPF_FLAGS, bpf_flags)) 617 goto nla_put_failure; 618 if (prog->gen_flags && 619 nla_put_u32(skb, TCA_BPF_FLAGS_GEN, prog->gen_flags)) 620 goto nla_put_failure; 621 622 nla_nest_end(skb, nest); 623 624 if (tcf_exts_dump_stats(skb, &prog->exts) < 0) 625 goto nla_put_failure; 626 627 return skb->len; 628 629 nla_put_failure: 630 nla_nest_cancel(skb, nest); 631 return -1; 632 } 633 634 static void cls_bpf_bind_class(void *fh, u32 classid, unsigned long cl) 635 { 636 struct cls_bpf_prog *prog = fh; 637 638 if (prog && prog->res.classid == classid) 639 prog->res.class = cl; 640 } 641 642 static void cls_bpf_walk(struct tcf_proto *tp, struct tcf_walker *arg) 643 { 644 struct cls_bpf_head *head = rtnl_dereference(tp->root); 645 struct cls_bpf_prog *prog; 646 647 list_for_each_entry(prog, &head->plist, link) { 648 if (arg->count < arg->skip) 649 goto skip; 650 if (arg->fn(tp, prog, arg) < 0) { 651 arg->stop = 1; 652 break; 653 } 654 skip: 655 arg->count++; 656 } 657 } 658 659 static struct tcf_proto_ops cls_bpf_ops __read_mostly = { 660 .kind = "bpf", 661 .owner = THIS_MODULE, 662 .classify = cls_bpf_classify, 663 .init = cls_bpf_init, 664 .destroy = cls_bpf_destroy, 665 .get = cls_bpf_get, 666 .change = cls_bpf_change, 667 .delete = cls_bpf_delete, 668 .walk = cls_bpf_walk, 669 .dump = cls_bpf_dump, 670 .bind_class = cls_bpf_bind_class, 671 }; 672 673 static int __init cls_bpf_init_mod(void) 674 { 675 return register_tcf_proto_ops(&cls_bpf_ops); 676 } 677 678 static void __exit cls_bpf_exit_mod(void) 679 { 680 unregister_tcf_proto_ops(&cls_bpf_ops); 681 } 682 683 module_init(cls_bpf_init_mod); 684 module_exit(cls_bpf_exit_mod); 685