1 /* 2 * xt_hashlimit - Netfilter module to limit the number of packets per time 3 * separately for each hashbucket (sourceip/sourceport/dstip/dstport) 4 * 5 * (C) 2003-2004 by Harald Welte <laforge@netfilter.org> 6 * (C) 2006-2012 Patrick McHardy <kaber@trash.net> 7 * Copyright © CC Computer Consultants GmbH, 2007 - 2008 8 * 9 * Development of this code was funded by Astaro AG, http://www.astaro.com/ 10 */ 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 12 #include <linux/module.h> 13 #include <linux/spinlock.h> 14 #include <linux/random.h> 15 #include <linux/jhash.h> 16 #include <linux/slab.h> 17 #include <linux/vmalloc.h> 18 #include <linux/proc_fs.h> 19 #include <linux/seq_file.h> 20 #include <linux/list.h> 21 #include <linux/skbuff.h> 22 #include <linux/mm.h> 23 #include <linux/in.h> 24 #include <linux/ip.h> 25 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 26 #include <linux/ipv6.h> 27 #include <net/ipv6.h> 28 #endif 29 30 #include <net/net_namespace.h> 31 #include <net/netns/generic.h> 32 33 #include <linux/netfilter/x_tables.h> 34 #include <linux/netfilter_ipv4/ip_tables.h> 35 #include <linux/netfilter_ipv6/ip6_tables.h> 36 #include <linux/netfilter/xt_hashlimit.h> 37 #include <linux/mutex.h> 38 39 MODULE_LICENSE("GPL"); 40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); 41 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); 42 MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match"); 43 MODULE_ALIAS("ipt_hashlimit"); 44 MODULE_ALIAS("ip6t_hashlimit"); 45 46 struct hashlimit_net { 47 struct hlist_head htables; 48 struct proc_dir_entry *ipt_hashlimit; 49 struct proc_dir_entry *ip6t_hashlimit; 50 }; 51 52 static int hashlimit_net_id; 53 static inline struct hashlimit_net *hashlimit_pernet(struct net *net) 54 { 55 return net_generic(net, hashlimit_net_id); 56 } 57 58 /* need to declare this at the top */ 59 static const struct file_operations dl_file_ops; 60 61 /* hash table crap */ 62 struct dsthash_dst { 63 union { 64 struct { 65 __be32 src; 66 __be32 dst; 67 } ip; 68 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 69 struct { 70 __be32 src[4]; 71 __be32 dst[4]; 72 } ip6; 73 #endif 74 }; 75 __be16 src_port; 76 __be16 dst_port; 77 }; 78 79 struct dsthash_ent { 80 /* static / read-only parts in the beginning */ 81 struct hlist_node node; 82 struct dsthash_dst dst; 83 84 /* modified structure members in the end */ 85 spinlock_t lock; 86 unsigned long expires; /* precalculated expiry time */ 87 struct { 88 unsigned long prev; /* last modification */ 89 u_int32_t credit; 90 u_int32_t credit_cap, cost; 91 } rateinfo; 92 struct rcu_head rcu; 93 }; 94 95 struct xt_hashlimit_htable { 96 struct hlist_node node; /* global list of all htables */ 97 int use; 98 u_int8_t family; 99 bool rnd_initialized; 100 101 struct hashlimit_cfg1 cfg; /* config */ 102 103 /* used internally */ 104 spinlock_t lock; /* lock for list_head */ 105 u_int32_t rnd; /* random seed for hash */ 106 unsigned int count; /* number entries in table */ 107 struct timer_list timer; /* timer for gc */ 108 109 /* seq_file stuff */ 110 struct proc_dir_entry *pde; 111 const char *name; 112 struct net *net; 113 114 struct hlist_head hash[0]; /* hashtable itself */ 115 }; 116 117 static DEFINE_MUTEX(hashlimit_mutex); /* protects htables list */ 118 static struct kmem_cache *hashlimit_cachep __read_mostly; 119 120 static inline bool dst_cmp(const struct dsthash_ent *ent, 121 const struct dsthash_dst *b) 122 { 123 return !memcmp(&ent->dst, b, sizeof(ent->dst)); 124 } 125 126 static u_int32_t 127 hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst) 128 { 129 u_int32_t hash = jhash2((const u32 *)dst, 130 sizeof(*dst)/sizeof(u32), 131 ht->rnd); 132 /* 133 * Instead of returning hash % ht->cfg.size (implying a divide) 134 * we return the high 32 bits of the (hash * ht->cfg.size) that will 135 * give results between [0 and cfg.size-1] and same hash distribution, 136 * but using a multiply, less expensive than a divide 137 */ 138 return ((u64)hash * ht->cfg.size) >> 32; 139 } 140 141 static struct dsthash_ent * 142 dsthash_find(const struct xt_hashlimit_htable *ht, 143 const struct dsthash_dst *dst) 144 { 145 struct dsthash_ent *ent; 146 u_int32_t hash = hash_dst(ht, dst); 147 148 if (!hlist_empty(&ht->hash[hash])) { 149 hlist_for_each_entry_rcu(ent, &ht->hash[hash], node) 150 if (dst_cmp(ent, dst)) { 151 spin_lock(&ent->lock); 152 return ent; 153 } 154 } 155 return NULL; 156 } 157 158 /* allocate dsthash_ent, initialize dst, put in htable and lock it */ 159 static struct dsthash_ent * 160 dsthash_alloc_init(struct xt_hashlimit_htable *ht, 161 const struct dsthash_dst *dst, bool *race) 162 { 163 struct dsthash_ent *ent; 164 165 spin_lock(&ht->lock); 166 167 /* Two or more packets may race to create the same entry in the 168 * hashtable, double check if this packet lost race. 169 */ 170 ent = dsthash_find(ht, dst); 171 if (ent != NULL) { 172 spin_unlock(&ht->lock); 173 *race = true; 174 return ent; 175 } 176 177 /* initialize hash with random val at the time we allocate 178 * the first hashtable entry */ 179 if (unlikely(!ht->rnd_initialized)) { 180 get_random_bytes(&ht->rnd, sizeof(ht->rnd)); 181 ht->rnd_initialized = true; 182 } 183 184 if (ht->cfg.max && ht->count >= ht->cfg.max) { 185 /* FIXME: do something. question is what.. */ 186 net_err_ratelimited("max count of %u reached\n", ht->cfg.max); 187 ent = NULL; 188 } else 189 ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC); 190 if (ent) { 191 memcpy(&ent->dst, dst, sizeof(ent->dst)); 192 spin_lock_init(&ent->lock); 193 194 spin_lock(&ent->lock); 195 hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]); 196 ht->count++; 197 } 198 spin_unlock(&ht->lock); 199 return ent; 200 } 201 202 static void dsthash_free_rcu(struct rcu_head *head) 203 { 204 struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu); 205 206 kmem_cache_free(hashlimit_cachep, ent); 207 } 208 209 static inline void 210 dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent) 211 { 212 hlist_del_rcu(&ent->node); 213 call_rcu_bh(&ent->rcu, dsthash_free_rcu); 214 ht->count--; 215 } 216 static void htable_gc(unsigned long htlong); 217 218 static int htable_create(struct net *net, struct xt_hashlimit_mtinfo1 *minfo, 219 u_int8_t family) 220 { 221 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); 222 struct xt_hashlimit_htable *hinfo; 223 unsigned int size; 224 unsigned int i; 225 226 if (minfo->cfg.size) { 227 size = minfo->cfg.size; 228 } else { 229 size = (totalram_pages << PAGE_SHIFT) / 16384 / 230 sizeof(struct list_head); 231 if (totalram_pages > 1024 * 1024 * 1024 / PAGE_SIZE) 232 size = 8192; 233 if (size < 16) 234 size = 16; 235 } 236 /* FIXME: don't use vmalloc() here or anywhere else -HW */ 237 hinfo = vmalloc(sizeof(struct xt_hashlimit_htable) + 238 sizeof(struct list_head) * size); 239 if (hinfo == NULL) 240 return -ENOMEM; 241 minfo->hinfo = hinfo; 242 243 /* copy match config into hashtable config */ 244 memcpy(&hinfo->cfg, &minfo->cfg, sizeof(hinfo->cfg)); 245 hinfo->cfg.size = size; 246 if (hinfo->cfg.max == 0) 247 hinfo->cfg.max = 8 * hinfo->cfg.size; 248 else if (hinfo->cfg.max < hinfo->cfg.size) 249 hinfo->cfg.max = hinfo->cfg.size; 250 251 for (i = 0; i < hinfo->cfg.size; i++) 252 INIT_HLIST_HEAD(&hinfo->hash[i]); 253 254 hinfo->use = 1; 255 hinfo->count = 0; 256 hinfo->family = family; 257 hinfo->rnd_initialized = false; 258 hinfo->name = kstrdup(minfo->name, GFP_KERNEL); 259 if (!hinfo->name) { 260 vfree(hinfo); 261 return -ENOMEM; 262 } 263 spin_lock_init(&hinfo->lock); 264 265 hinfo->pde = proc_create_data(minfo->name, 0, 266 (family == NFPROTO_IPV4) ? 267 hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit, 268 &dl_file_ops, hinfo); 269 if (hinfo->pde == NULL) { 270 kfree(hinfo->name); 271 vfree(hinfo); 272 return -ENOMEM; 273 } 274 hinfo->net = net; 275 276 setup_timer(&hinfo->timer, htable_gc, (unsigned long)hinfo); 277 hinfo->timer.expires = jiffies + msecs_to_jiffies(hinfo->cfg.gc_interval); 278 add_timer(&hinfo->timer); 279 280 hlist_add_head(&hinfo->node, &hashlimit_net->htables); 281 282 return 0; 283 } 284 285 static bool select_all(const struct xt_hashlimit_htable *ht, 286 const struct dsthash_ent *he) 287 { 288 return 1; 289 } 290 291 static bool select_gc(const struct xt_hashlimit_htable *ht, 292 const struct dsthash_ent *he) 293 { 294 return time_after_eq(jiffies, he->expires); 295 } 296 297 static void htable_selective_cleanup(struct xt_hashlimit_htable *ht, 298 bool (*select)(const struct xt_hashlimit_htable *ht, 299 const struct dsthash_ent *he)) 300 { 301 unsigned int i; 302 303 /* lock hash table and iterate over it */ 304 spin_lock_bh(&ht->lock); 305 for (i = 0; i < ht->cfg.size; i++) { 306 struct dsthash_ent *dh; 307 struct hlist_node *n; 308 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) { 309 if ((*select)(ht, dh)) 310 dsthash_free(ht, dh); 311 } 312 } 313 spin_unlock_bh(&ht->lock); 314 } 315 316 /* hash table garbage collector, run by timer */ 317 static void htable_gc(unsigned long htlong) 318 { 319 struct xt_hashlimit_htable *ht = (struct xt_hashlimit_htable *)htlong; 320 321 htable_selective_cleanup(ht, select_gc); 322 323 /* re-add the timer accordingly */ 324 ht->timer.expires = jiffies + msecs_to_jiffies(ht->cfg.gc_interval); 325 add_timer(&ht->timer); 326 } 327 328 static void htable_destroy(struct xt_hashlimit_htable *hinfo) 329 { 330 struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net); 331 struct proc_dir_entry *parent; 332 333 del_timer_sync(&hinfo->timer); 334 335 if (hinfo->family == NFPROTO_IPV4) 336 parent = hashlimit_net->ipt_hashlimit; 337 else 338 parent = hashlimit_net->ip6t_hashlimit; 339 340 if(parent != NULL) 341 remove_proc_entry(hinfo->name, parent); 342 343 htable_selective_cleanup(hinfo, select_all); 344 kfree(hinfo->name); 345 vfree(hinfo); 346 } 347 348 static struct xt_hashlimit_htable *htable_find_get(struct net *net, 349 const char *name, 350 u_int8_t family) 351 { 352 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); 353 struct xt_hashlimit_htable *hinfo; 354 355 hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) { 356 if (!strcmp(name, hinfo->name) && 357 hinfo->family == family) { 358 hinfo->use++; 359 return hinfo; 360 } 361 } 362 return NULL; 363 } 364 365 static void htable_put(struct xt_hashlimit_htable *hinfo) 366 { 367 mutex_lock(&hashlimit_mutex); 368 if (--hinfo->use == 0) { 369 hlist_del(&hinfo->node); 370 htable_destroy(hinfo); 371 } 372 mutex_unlock(&hashlimit_mutex); 373 } 374 375 /* The algorithm used is the Simple Token Bucket Filter (TBF) 376 * see net/sched/sch_tbf.c in the linux source tree 377 */ 378 379 /* Rusty: This is my (non-mathematically-inclined) understanding of 380 this algorithm. The `average rate' in jiffies becomes your initial 381 amount of credit `credit' and the most credit you can ever have 382 `credit_cap'. The `peak rate' becomes the cost of passing the 383 test, `cost'. 384 385 `prev' tracks the last packet hit: you gain one credit per jiffy. 386 If you get credit balance more than this, the extra credit is 387 discarded. Every time the match passes, you lose `cost' credits; 388 if you don't have that many, the test fails. 389 390 See Alexey's formal explanation in net/sched/sch_tbf.c. 391 392 To get the maximum range, we multiply by this factor (ie. you get N 393 credits per jiffy). We want to allow a rate as low as 1 per day 394 (slowest userspace tool allows), which means 395 CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie. 396 */ 397 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24)) 398 399 /* Repeated shift and or gives us all 1s, final shift and add 1 gives 400 * us the power of 2 below the theoretical max, so GCC simply does a 401 * shift. */ 402 #define _POW2_BELOW2(x) ((x)|((x)>>1)) 403 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2)) 404 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4)) 405 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8)) 406 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16)) 407 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1) 408 409 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ) 410 411 /* in byte mode, the lowest possible rate is one packet/second. 412 * credit_cap is used as a counter that tells us how many times we can 413 * refill the "credits available" counter when it becomes empty. 414 */ 415 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ) 416 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES) 417 418 static u32 xt_hashlimit_len_to_chunks(u32 len) 419 { 420 return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1; 421 } 422 423 /* Precision saver. */ 424 static u32 user2credits(u32 user) 425 { 426 /* If multiplying would overflow... */ 427 if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY)) 428 /* Divide first. */ 429 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY; 430 431 return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE; 432 } 433 434 static u32 user2credits_byte(u32 user) 435 { 436 u64 us = user; 437 us *= HZ * CREDITS_PER_JIFFY_BYTES; 438 return (u32) (us >> 32); 439 } 440 441 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, u32 mode) 442 { 443 unsigned long delta = now - dh->rateinfo.prev; 444 u32 cap; 445 446 if (delta == 0) 447 return; 448 449 dh->rateinfo.prev = now; 450 451 if (mode & XT_HASHLIMIT_BYTES) { 452 u32 tmp = dh->rateinfo.credit; 453 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta; 454 cap = CREDITS_PER_JIFFY_BYTES * HZ; 455 if (tmp >= dh->rateinfo.credit) {/* overflow */ 456 dh->rateinfo.credit = cap; 457 return; 458 } 459 } else { 460 dh->rateinfo.credit += delta * CREDITS_PER_JIFFY; 461 cap = dh->rateinfo.credit_cap; 462 } 463 if (dh->rateinfo.credit > cap) 464 dh->rateinfo.credit = cap; 465 } 466 467 static void rateinfo_init(struct dsthash_ent *dh, 468 struct xt_hashlimit_htable *hinfo) 469 { 470 dh->rateinfo.prev = jiffies; 471 if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) { 472 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ; 473 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg); 474 dh->rateinfo.credit_cap = hinfo->cfg.burst; 475 } else { 476 dh->rateinfo.credit = user2credits(hinfo->cfg.avg * 477 hinfo->cfg.burst); 478 dh->rateinfo.cost = user2credits(hinfo->cfg.avg); 479 dh->rateinfo.credit_cap = dh->rateinfo.credit; 480 } 481 } 482 483 static inline __be32 maskl(__be32 a, unsigned int l) 484 { 485 return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0; 486 } 487 488 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 489 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p) 490 { 491 switch (p) { 492 case 0 ... 31: 493 i[0] = maskl(i[0], p); 494 i[1] = i[2] = i[3] = 0; 495 break; 496 case 32 ... 63: 497 i[1] = maskl(i[1], p - 32); 498 i[2] = i[3] = 0; 499 break; 500 case 64 ... 95: 501 i[2] = maskl(i[2], p - 64); 502 i[3] = 0; 503 break; 504 case 96 ... 127: 505 i[3] = maskl(i[3], p - 96); 506 break; 507 case 128: 508 break; 509 } 510 } 511 #endif 512 513 static int 514 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo, 515 struct dsthash_dst *dst, 516 const struct sk_buff *skb, unsigned int protoff) 517 { 518 __be16 _ports[2], *ports; 519 u8 nexthdr; 520 int poff; 521 522 memset(dst, 0, sizeof(*dst)); 523 524 switch (hinfo->family) { 525 case NFPROTO_IPV4: 526 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) 527 dst->ip.dst = maskl(ip_hdr(skb)->daddr, 528 hinfo->cfg.dstmask); 529 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) 530 dst->ip.src = maskl(ip_hdr(skb)->saddr, 531 hinfo->cfg.srcmask); 532 533 if (!(hinfo->cfg.mode & 534 (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT))) 535 return 0; 536 nexthdr = ip_hdr(skb)->protocol; 537 break; 538 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 539 case NFPROTO_IPV6: 540 { 541 __be16 frag_off; 542 543 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) { 544 memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr, 545 sizeof(dst->ip6.dst)); 546 hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask); 547 } 548 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) { 549 memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr, 550 sizeof(dst->ip6.src)); 551 hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask); 552 } 553 554 if (!(hinfo->cfg.mode & 555 (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT))) 556 return 0; 557 nexthdr = ipv6_hdr(skb)->nexthdr; 558 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off); 559 if ((int)protoff < 0) 560 return -1; 561 break; 562 } 563 #endif 564 default: 565 BUG(); 566 return 0; 567 } 568 569 poff = proto_ports_offset(nexthdr); 570 if (poff >= 0) { 571 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports), 572 &_ports); 573 } else { 574 _ports[0] = _ports[1] = 0; 575 ports = _ports; 576 } 577 if (!ports) 578 return -1; 579 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT) 580 dst->src_port = ports[0]; 581 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT) 582 dst->dst_port = ports[1]; 583 return 0; 584 } 585 586 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh) 587 { 588 u64 tmp = xt_hashlimit_len_to_chunks(len); 589 tmp = tmp * dh->rateinfo.cost; 590 591 if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ)) 592 tmp = CREDITS_PER_JIFFY_BYTES * HZ; 593 594 if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) { 595 dh->rateinfo.credit_cap--; 596 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ; 597 } 598 return (u32) tmp; 599 } 600 601 static bool 602 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) 603 { 604 const struct xt_hashlimit_mtinfo1 *info = par->matchinfo; 605 struct xt_hashlimit_htable *hinfo = info->hinfo; 606 unsigned long now = jiffies; 607 struct dsthash_ent *dh; 608 struct dsthash_dst dst; 609 bool race = false; 610 u32 cost; 611 612 if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0) 613 goto hotdrop; 614 615 rcu_read_lock_bh(); 616 dh = dsthash_find(hinfo, &dst); 617 if (dh == NULL) { 618 dh = dsthash_alloc_init(hinfo, &dst, &race); 619 if (dh == NULL) { 620 rcu_read_unlock_bh(); 621 goto hotdrop; 622 } else if (race) { 623 /* Already got an entry, update expiration timeout */ 624 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); 625 rateinfo_recalc(dh, now, hinfo->cfg.mode); 626 } else { 627 dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire); 628 rateinfo_init(dh, hinfo); 629 } 630 } else { 631 /* update expiration timeout */ 632 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); 633 rateinfo_recalc(dh, now, hinfo->cfg.mode); 634 } 635 636 if (info->cfg.mode & XT_HASHLIMIT_BYTES) 637 cost = hashlimit_byte_cost(skb->len, dh); 638 else 639 cost = dh->rateinfo.cost; 640 641 if (dh->rateinfo.credit >= cost) { 642 /* below the limit */ 643 dh->rateinfo.credit -= cost; 644 spin_unlock(&dh->lock); 645 rcu_read_unlock_bh(); 646 return !(info->cfg.mode & XT_HASHLIMIT_INVERT); 647 } 648 649 spin_unlock(&dh->lock); 650 rcu_read_unlock_bh(); 651 /* default match is underlimit - so over the limit, we need to invert */ 652 return info->cfg.mode & XT_HASHLIMIT_INVERT; 653 654 hotdrop: 655 par->hotdrop = true; 656 return false; 657 } 658 659 static int hashlimit_mt_check(const struct xt_mtchk_param *par) 660 { 661 struct net *net = par->net; 662 struct xt_hashlimit_mtinfo1 *info = par->matchinfo; 663 int ret; 664 665 if (info->cfg.gc_interval == 0 || info->cfg.expire == 0) 666 return -EINVAL; 667 if (info->name[sizeof(info->name)-1] != '\0') 668 return -EINVAL; 669 if (par->family == NFPROTO_IPV4) { 670 if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32) 671 return -EINVAL; 672 } else { 673 if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128) 674 return -EINVAL; 675 } 676 677 if (info->cfg.mode & ~XT_HASHLIMIT_ALL) { 678 pr_info("Unknown mode mask %X, kernel too old?\n", 679 info->cfg.mode); 680 return -EINVAL; 681 } 682 683 /* Check for overflow. */ 684 if (info->cfg.mode & XT_HASHLIMIT_BYTES) { 685 if (user2credits_byte(info->cfg.avg) == 0) { 686 pr_info("overflow, rate too high: %u\n", info->cfg.avg); 687 return -EINVAL; 688 } 689 } else if (info->cfg.burst == 0 || 690 user2credits(info->cfg.avg * info->cfg.burst) < 691 user2credits(info->cfg.avg)) { 692 pr_info("overflow, try lower: %u/%u\n", 693 info->cfg.avg, info->cfg.burst); 694 return -ERANGE; 695 } 696 697 mutex_lock(&hashlimit_mutex); 698 info->hinfo = htable_find_get(net, info->name, par->family); 699 if (info->hinfo == NULL) { 700 ret = htable_create(net, info, par->family); 701 if (ret < 0) { 702 mutex_unlock(&hashlimit_mutex); 703 return ret; 704 } 705 } 706 mutex_unlock(&hashlimit_mutex); 707 return 0; 708 } 709 710 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par) 711 { 712 const struct xt_hashlimit_mtinfo1 *info = par->matchinfo; 713 714 htable_put(info->hinfo); 715 } 716 717 static struct xt_match hashlimit_mt_reg[] __read_mostly = { 718 { 719 .name = "hashlimit", 720 .revision = 1, 721 .family = NFPROTO_IPV4, 722 .match = hashlimit_mt, 723 .matchsize = sizeof(struct xt_hashlimit_mtinfo1), 724 .checkentry = hashlimit_mt_check, 725 .destroy = hashlimit_mt_destroy, 726 .me = THIS_MODULE, 727 }, 728 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 729 { 730 .name = "hashlimit", 731 .revision = 1, 732 .family = NFPROTO_IPV6, 733 .match = hashlimit_mt, 734 .matchsize = sizeof(struct xt_hashlimit_mtinfo1), 735 .checkentry = hashlimit_mt_check, 736 .destroy = hashlimit_mt_destroy, 737 .me = THIS_MODULE, 738 }, 739 #endif 740 }; 741 742 /* PROC stuff */ 743 static void *dl_seq_start(struct seq_file *s, loff_t *pos) 744 __acquires(htable->lock) 745 { 746 struct xt_hashlimit_htable *htable = s->private; 747 unsigned int *bucket; 748 749 spin_lock_bh(&htable->lock); 750 if (*pos >= htable->cfg.size) 751 return NULL; 752 753 bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC); 754 if (!bucket) 755 return ERR_PTR(-ENOMEM); 756 757 *bucket = *pos; 758 return bucket; 759 } 760 761 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos) 762 { 763 struct xt_hashlimit_htable *htable = s->private; 764 unsigned int *bucket = (unsigned int *)v; 765 766 *pos = ++(*bucket); 767 if (*pos >= htable->cfg.size) { 768 kfree(v); 769 return NULL; 770 } 771 return bucket; 772 } 773 774 static void dl_seq_stop(struct seq_file *s, void *v) 775 __releases(htable->lock) 776 { 777 struct xt_hashlimit_htable *htable = s->private; 778 unsigned int *bucket = (unsigned int *)v; 779 780 if (!IS_ERR(bucket)) 781 kfree(bucket); 782 spin_unlock_bh(&htable->lock); 783 } 784 785 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family, 786 struct seq_file *s) 787 { 788 int res; 789 const struct xt_hashlimit_htable *ht = s->private; 790 791 spin_lock(&ent->lock); 792 /* recalculate to show accurate numbers */ 793 rateinfo_recalc(ent, jiffies, ht->cfg.mode); 794 795 switch (family) { 796 case NFPROTO_IPV4: 797 res = seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n", 798 (long)(ent->expires - jiffies)/HZ, 799 &ent->dst.ip.src, 800 ntohs(ent->dst.src_port), 801 &ent->dst.ip.dst, 802 ntohs(ent->dst.dst_port), 803 ent->rateinfo.credit, ent->rateinfo.credit_cap, 804 ent->rateinfo.cost); 805 break; 806 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 807 case NFPROTO_IPV6: 808 res = seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n", 809 (long)(ent->expires - jiffies)/HZ, 810 &ent->dst.ip6.src, 811 ntohs(ent->dst.src_port), 812 &ent->dst.ip6.dst, 813 ntohs(ent->dst.dst_port), 814 ent->rateinfo.credit, ent->rateinfo.credit_cap, 815 ent->rateinfo.cost); 816 break; 817 #endif 818 default: 819 BUG(); 820 res = 0; 821 } 822 spin_unlock(&ent->lock); 823 return res; 824 } 825 826 static int dl_seq_show(struct seq_file *s, void *v) 827 { 828 struct xt_hashlimit_htable *htable = s->private; 829 unsigned int *bucket = (unsigned int *)v; 830 struct dsthash_ent *ent; 831 832 if (!hlist_empty(&htable->hash[*bucket])) { 833 hlist_for_each_entry(ent, &htable->hash[*bucket], node) 834 if (dl_seq_real_show(ent, htable->family, s)) 835 return -1; 836 } 837 return 0; 838 } 839 840 static const struct seq_operations dl_seq_ops = { 841 .start = dl_seq_start, 842 .next = dl_seq_next, 843 .stop = dl_seq_stop, 844 .show = dl_seq_show 845 }; 846 847 static int dl_proc_open(struct inode *inode, struct file *file) 848 { 849 int ret = seq_open(file, &dl_seq_ops); 850 851 if (!ret) { 852 struct seq_file *sf = file->private_data; 853 sf->private = PDE_DATA(inode); 854 } 855 return ret; 856 } 857 858 static const struct file_operations dl_file_ops = { 859 .owner = THIS_MODULE, 860 .open = dl_proc_open, 861 .read = seq_read, 862 .llseek = seq_lseek, 863 .release = seq_release 864 }; 865 866 static int __net_init hashlimit_proc_net_init(struct net *net) 867 { 868 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); 869 870 hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net); 871 if (!hashlimit_net->ipt_hashlimit) 872 return -ENOMEM; 873 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 874 hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net); 875 if (!hashlimit_net->ip6t_hashlimit) { 876 remove_proc_entry("ipt_hashlimit", net->proc_net); 877 return -ENOMEM; 878 } 879 #endif 880 return 0; 881 } 882 883 static void __net_exit hashlimit_proc_net_exit(struct net *net) 884 { 885 struct xt_hashlimit_htable *hinfo; 886 struct proc_dir_entry *pde; 887 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); 888 889 /* recent_net_exit() is called before recent_mt_destroy(). Make sure 890 * that the parent xt_recent proc entry is is empty before trying to 891 * remove it. 892 */ 893 mutex_lock(&hashlimit_mutex); 894 pde = hashlimit_net->ipt_hashlimit; 895 if (pde == NULL) 896 pde = hashlimit_net->ip6t_hashlimit; 897 898 hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) 899 remove_proc_entry(hinfo->name, pde); 900 901 hashlimit_net->ipt_hashlimit = NULL; 902 hashlimit_net->ip6t_hashlimit = NULL; 903 mutex_unlock(&hashlimit_mutex); 904 905 remove_proc_entry("ipt_hashlimit", net->proc_net); 906 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) 907 remove_proc_entry("ip6t_hashlimit", net->proc_net); 908 #endif 909 } 910 911 static int __net_init hashlimit_net_init(struct net *net) 912 { 913 struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); 914 915 INIT_HLIST_HEAD(&hashlimit_net->htables); 916 return hashlimit_proc_net_init(net); 917 } 918 919 static void __net_exit hashlimit_net_exit(struct net *net) 920 { 921 hashlimit_proc_net_exit(net); 922 } 923 924 static struct pernet_operations hashlimit_net_ops = { 925 .init = hashlimit_net_init, 926 .exit = hashlimit_net_exit, 927 .id = &hashlimit_net_id, 928 .size = sizeof(struct hashlimit_net), 929 }; 930 931 static int __init hashlimit_mt_init(void) 932 { 933 int err; 934 935 err = register_pernet_subsys(&hashlimit_net_ops); 936 if (err < 0) 937 return err; 938 err = xt_register_matches(hashlimit_mt_reg, 939 ARRAY_SIZE(hashlimit_mt_reg)); 940 if (err < 0) 941 goto err1; 942 943 err = -ENOMEM; 944 hashlimit_cachep = kmem_cache_create("xt_hashlimit", 945 sizeof(struct dsthash_ent), 0, 0, 946 NULL); 947 if (!hashlimit_cachep) { 948 pr_warning("unable to create slab cache\n"); 949 goto err2; 950 } 951 return 0; 952 953 err2: 954 xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg)); 955 err1: 956 unregister_pernet_subsys(&hashlimit_net_ops); 957 return err; 958 959 } 960 961 static void __exit hashlimit_mt_exit(void) 962 { 963 xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg)); 964 unregister_pernet_subsys(&hashlimit_net_ops); 965 966 rcu_barrier_bh(); 967 kmem_cache_destroy(hashlimit_cachep); 968 } 969 970 module_init(hashlimit_mt_init); 971 module_exit(hashlimit_mt_exit); 972