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