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