~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/netfilter/xt_hashlimit.c

Version: ~ [ linux-5.6 ] ~ [ linux-5.5.13 ] ~ [ linux-5.4.28 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.113 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.174 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.217 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.217 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 delayed_work gc_work;
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 reciprocal_scale(hash, ht->cfg.size);
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(struct work_struct *work);
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         INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc);
277         queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work,
278                            msecs_to_jiffies(hinfo->cfg.gc_interval));
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         for (i = 0; i < ht->cfg.size; i++) {
304                 struct dsthash_ent *dh;
305                 struct hlist_node *n;
306 
307                 spin_lock_bh(&ht->lock);
308                 hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) {
309                         if ((*select)(ht, dh))
310                                 dsthash_free(ht, dh);
311                 }
312                 spin_unlock_bh(&ht->lock);
313                 cond_resched();
314         }
315 }
316 
317 static void htable_gc(struct work_struct *work)
318 {
319         struct xt_hashlimit_htable *ht;
320 
321         ht = container_of(work, struct xt_hashlimit_htable, gc_work.work);
322 
323         htable_selective_cleanup(ht, select_gc);
324 
325         queue_delayed_work(system_power_efficient_wq,
326                            &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval));
327 }
328 
329 static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
330 {
331         struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net);
332         struct proc_dir_entry *parent;
333 
334         if (hinfo->family == NFPROTO_IPV4)
335                 parent = hashlimit_net->ipt_hashlimit;
336         else
337                 parent = hashlimit_net->ip6t_hashlimit;
338 
339         if (parent != NULL)
340                 remove_proc_entry(hinfo->name, parent);
341 }
342 
343 static void htable_destroy(struct xt_hashlimit_htable *hinfo)
344 {
345         cancel_delayed_work_sync(&hinfo->gc_work);
346         htable_remove_proc_entry(hinfo);
347         htable_selective_cleanup(hinfo, select_all);
348         kfree(hinfo->name);
349         vfree(hinfo);
350 }
351 
352 static struct xt_hashlimit_htable *htable_find_get(struct net *net,
353                                                    const char *name,
354                                                    u_int8_t family)
355 {
356         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
357         struct xt_hashlimit_htable *hinfo;
358 
359         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) {
360                 if (!strcmp(name, hinfo->name) &&
361                     hinfo->family == family) {
362                         hinfo->use++;
363                         return hinfo;
364                 }
365         }
366         return NULL;
367 }
368 
369 static void htable_put(struct xt_hashlimit_htable *hinfo)
370 {
371         mutex_lock(&hashlimit_mutex);
372         if (--hinfo->use == 0) {
373                 hlist_del(&hinfo->node);
374                 htable_destroy(hinfo);
375         }
376         mutex_unlock(&hashlimit_mutex);
377 }
378 
379 /* The algorithm used is the Simple Token Bucket Filter (TBF)
380  * see net/sched/sch_tbf.c in the linux source tree
381  */
382 
383 /* Rusty: This is my (non-mathematically-inclined) understanding of
384    this algorithm.  The `average rate' in jiffies becomes your initial
385    amount of credit `credit' and the most credit you can ever have
386    `credit_cap'.  The `peak rate' becomes the cost of passing the
387    test, `cost'.
388 
389    `prev' tracks the last packet hit: you gain one credit per jiffy.
390    If you get credit balance more than this, the extra credit is
391    discarded.  Every time the match passes, you lose `cost' credits;
392    if you don't have that many, the test fails.
393 
394    See Alexey's formal explanation in net/sched/sch_tbf.c.
395 
396    To get the maximum range, we multiply by this factor (ie. you get N
397    credits per jiffy).  We want to allow a rate as low as 1 per day
398    (slowest userspace tool allows), which means
399    CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie.
400 */
401 #define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
402 
403 /* Repeated shift and or gives us all 1s, final shift and add 1 gives
404  * us the power of 2 below the theoretical max, so GCC simply does a
405  * shift. */
406 #define _POW2_BELOW2(x) ((x)|((x)>>1))
407 #define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
408 #define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
409 #define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
410 #define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
411 #define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
412 
413 #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
414 
415 /* in byte mode, the lowest possible rate is one packet/second.
416  * credit_cap is used as a counter that tells us how many times we can
417  * refill the "credits available" counter when it becomes empty.
418  */
419 #define MAX_CPJ_BYTES (0xFFFFFFFF / HZ)
420 #define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES)
421 
422 static u32 xt_hashlimit_len_to_chunks(u32 len)
423 {
424         return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1;
425 }
426 
427 /* Precision saver. */
428 static u32 user2credits(u32 user)
429 {
430         /* If multiplying would overflow... */
431         if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
432                 /* Divide first. */
433                 return (user / XT_HASHLIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
434 
435         return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE;
436 }
437 
438 static u32 user2credits_byte(u32 user)
439 {
440         u64 us = user;
441         us *= HZ * CREDITS_PER_JIFFY_BYTES;
442         return (u32) (us >> 32);
443 }
444 
445 static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, u32 mode)
446 {
447         unsigned long delta = now - dh->rateinfo.prev;
448         u32 cap;
449 
450         if (delta == 0)
451                 return;
452 
453         dh->rateinfo.prev = now;
454 
455         if (mode & XT_HASHLIMIT_BYTES) {
456                 u32 tmp = dh->rateinfo.credit;
457                 dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta;
458                 cap = CREDITS_PER_JIFFY_BYTES * HZ;
459                 if (tmp >= dh->rateinfo.credit) {/* overflow */
460                         dh->rateinfo.credit = cap;
461                         return;
462                 }
463         } else {
464                 dh->rateinfo.credit += delta * CREDITS_PER_JIFFY;
465                 cap = dh->rateinfo.credit_cap;
466         }
467         if (dh->rateinfo.credit > cap)
468                 dh->rateinfo.credit = cap;
469 }
470 
471 static void rateinfo_init(struct dsthash_ent *dh,
472                           struct xt_hashlimit_htable *hinfo)
473 {
474         dh->rateinfo.prev = jiffies;
475         if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) {
476                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
477                 dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg);
478                 dh->rateinfo.credit_cap = hinfo->cfg.burst;
479         } else {
480                 dh->rateinfo.credit = user2credits(hinfo->cfg.avg *
481                                                    hinfo->cfg.burst);
482                 dh->rateinfo.cost = user2credits(hinfo->cfg.avg);
483                 dh->rateinfo.credit_cap = dh->rateinfo.credit;
484         }
485 }
486 
487 static inline __be32 maskl(__be32 a, unsigned int l)
488 {
489         return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
490 }
491 
492 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
493 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
494 {
495         switch (p) {
496         case 0 ... 31:
497                 i[0] = maskl(i[0], p);
498                 i[1] = i[2] = i[3] = 0;
499                 break;
500         case 32 ... 63:
501                 i[1] = maskl(i[1], p - 32);
502                 i[2] = i[3] = 0;
503                 break;
504         case 64 ... 95:
505                 i[2] = maskl(i[2], p - 64);
506                 i[3] = 0;
507                 break;
508         case 96 ... 127:
509                 i[3] = maskl(i[3], p - 96);
510                 break;
511         case 128:
512                 break;
513         }
514 }
515 #endif
516 
517 static int
518 hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo,
519                    struct dsthash_dst *dst,
520                    const struct sk_buff *skb, unsigned int protoff)
521 {
522         __be16 _ports[2], *ports;
523         u8 nexthdr;
524         int poff;
525 
526         memset(dst, 0, sizeof(*dst));
527 
528         switch (hinfo->family) {
529         case NFPROTO_IPV4:
530                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP)
531                         dst->ip.dst = maskl(ip_hdr(skb)->daddr,
532                                       hinfo->cfg.dstmask);
533                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP)
534                         dst->ip.src = maskl(ip_hdr(skb)->saddr,
535                                       hinfo->cfg.srcmask);
536 
537                 if (!(hinfo->cfg.mode &
538                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
539                         return 0;
540                 nexthdr = ip_hdr(skb)->protocol;
541                 break;
542 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
543         case NFPROTO_IPV6:
544         {
545                 __be16 frag_off;
546 
547                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) {
548                         memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr,
549                                sizeof(dst->ip6.dst));
550                         hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask);
551                 }
552                 if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) {
553                         memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr,
554                                sizeof(dst->ip6.src));
555                         hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask);
556                 }
557 
558                 if (!(hinfo->cfg.mode &
559                       (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT)))
560                         return 0;
561                 nexthdr = ipv6_hdr(skb)->nexthdr;
562                 protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off);
563                 if ((int)protoff < 0)
564                         return -1;
565                 break;
566         }
567 #endif
568         default:
569                 BUG();
570                 return 0;
571         }
572 
573         poff = proto_ports_offset(nexthdr);
574         if (poff >= 0) {
575                 ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports),
576                                            &_ports);
577         } else {
578                 _ports[0] = _ports[1] = 0;
579                 ports = _ports;
580         }
581         if (!ports)
582                 return -1;
583         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT)
584                 dst->src_port = ports[0];
585         if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT)
586                 dst->dst_port = ports[1];
587         return 0;
588 }
589 
590 static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh)
591 {
592         u64 tmp = xt_hashlimit_len_to_chunks(len);
593         tmp = tmp * dh->rateinfo.cost;
594 
595         if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ))
596                 tmp = CREDITS_PER_JIFFY_BYTES * HZ;
597 
598         if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) {
599                 dh->rateinfo.credit_cap--;
600                 dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ;
601         }
602         return (u32) tmp;
603 }
604 
605 static bool
606 hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
607 {
608         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
609         struct xt_hashlimit_htable *hinfo = info->hinfo;
610         unsigned long now = jiffies;
611         struct dsthash_ent *dh;
612         struct dsthash_dst dst;
613         bool race = false;
614         u32 cost;
615 
616         if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0)
617                 goto hotdrop;
618 
619         rcu_read_lock_bh();
620         dh = dsthash_find(hinfo, &dst);
621         if (dh == NULL) {
622                 dh = dsthash_alloc_init(hinfo, &dst, &race);
623                 if (dh == NULL) {
624                         rcu_read_unlock_bh();
625                         goto hotdrop;
626                 } else if (race) {
627                         /* Already got an entry, update expiration timeout */
628                         dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
629                         rateinfo_recalc(dh, now, hinfo->cfg.mode);
630                 } else {
631                         dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire);
632                         rateinfo_init(dh, hinfo);
633                 }
634         } else {
635                 /* update expiration timeout */
636                 dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire);
637                 rateinfo_recalc(dh, now, hinfo->cfg.mode);
638         }
639 
640         if (info->cfg.mode & XT_HASHLIMIT_BYTES)
641                 cost = hashlimit_byte_cost(skb->len, dh);
642         else
643                 cost = dh->rateinfo.cost;
644 
645         if (dh->rateinfo.credit >= cost) {
646                 /* below the limit */
647                 dh->rateinfo.credit -= cost;
648                 spin_unlock(&dh->lock);
649                 rcu_read_unlock_bh();
650                 return !(info->cfg.mode & XT_HASHLIMIT_INVERT);
651         }
652 
653         spin_unlock(&dh->lock);
654         rcu_read_unlock_bh();
655         /* default match is underlimit - so over the limit, we need to invert */
656         return info->cfg.mode & XT_HASHLIMIT_INVERT;
657 
658  hotdrop:
659         par->hotdrop = true;
660         return false;
661 }
662 
663 static int hashlimit_mt_check(const struct xt_mtchk_param *par)
664 {
665         struct net *net = par->net;
666         struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
667         int ret;
668 
669         if (info->cfg.gc_interval == 0 || info->cfg.expire == 0)
670                 return -EINVAL;
671         if (info->name[sizeof(info->name)-1] != '\0')
672                 return -EINVAL;
673         if (par->family == NFPROTO_IPV4) {
674                 if (info->cfg.srcmask > 32 || info->cfg.dstmask > 32)
675                         return -EINVAL;
676         } else {
677                 if (info->cfg.srcmask > 128 || info->cfg.dstmask > 128)
678                         return -EINVAL;
679         }
680 
681         if (info->cfg.mode & ~XT_HASHLIMIT_ALL) {
682                 pr_info("Unknown mode mask %X, kernel too old?\n",
683                                                 info->cfg.mode);
684                 return -EINVAL;
685         }
686 
687         /* Check for overflow. */
688         if (info->cfg.mode & XT_HASHLIMIT_BYTES) {
689                 if (user2credits_byte(info->cfg.avg) == 0) {
690                         pr_info("overflow, rate too high: %u\n", info->cfg.avg);
691                         return -EINVAL;
692                 }
693         } else if (info->cfg.burst == 0 ||
694                     user2credits(info->cfg.avg * info->cfg.burst) <
695                     user2credits(info->cfg.avg)) {
696                         pr_info("overflow, try lower: %u/%u\n",
697                                 info->cfg.avg, info->cfg.burst);
698                         return -ERANGE;
699         }
700 
701         mutex_lock(&hashlimit_mutex);
702         info->hinfo = htable_find_get(net, info->name, par->family);
703         if (info->hinfo == NULL) {
704                 ret = htable_create(net, info, par->family);
705                 if (ret < 0) {
706                         mutex_unlock(&hashlimit_mutex);
707                         return ret;
708                 }
709         }
710         mutex_unlock(&hashlimit_mutex);
711         return 0;
712 }
713 
714 static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par)
715 {
716         const struct xt_hashlimit_mtinfo1 *info = par->matchinfo;
717 
718         htable_put(info->hinfo);
719 }
720 
721 static struct xt_match hashlimit_mt_reg[] __read_mostly = {
722         {
723                 .name           = "hashlimit",
724                 .revision       = 1,
725                 .family         = NFPROTO_IPV4,
726                 .match          = hashlimit_mt,
727                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
728                 .checkentry     = hashlimit_mt_check,
729                 .destroy        = hashlimit_mt_destroy,
730                 .me             = THIS_MODULE,
731         },
732 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
733         {
734                 .name           = "hashlimit",
735                 .revision       = 1,
736                 .family         = NFPROTO_IPV6,
737                 .match          = hashlimit_mt,
738                 .matchsize      = sizeof(struct xt_hashlimit_mtinfo1),
739                 .checkentry     = hashlimit_mt_check,
740                 .destroy        = hashlimit_mt_destroy,
741                 .me             = THIS_MODULE,
742         },
743 #endif
744 };
745 
746 /* PROC stuff */
747 static void *dl_seq_start(struct seq_file *s, loff_t *pos)
748         __acquires(htable->lock)
749 {
750         struct xt_hashlimit_htable *htable = s->private;
751         unsigned int *bucket;
752 
753         spin_lock_bh(&htable->lock);
754         if (*pos >= htable->cfg.size)
755                 return NULL;
756 
757         bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC);
758         if (!bucket)
759                 return ERR_PTR(-ENOMEM);
760 
761         *bucket = *pos;
762         return bucket;
763 }
764 
765 static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos)
766 {
767         struct xt_hashlimit_htable *htable = s->private;
768         unsigned int *bucket = (unsigned int *)v;
769 
770         *pos = ++(*bucket);
771         if (*pos >= htable->cfg.size) {
772                 kfree(v);
773                 return NULL;
774         }
775         return bucket;
776 }
777 
778 static void dl_seq_stop(struct seq_file *s, void *v)
779         __releases(htable->lock)
780 {
781         struct xt_hashlimit_htable *htable = s->private;
782         unsigned int *bucket = (unsigned int *)v;
783 
784         if (!IS_ERR(bucket))
785                 kfree(bucket);
786         spin_unlock_bh(&htable->lock);
787 }
788 
789 static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family,
790                                    struct seq_file *s)
791 {
792         const struct xt_hashlimit_htable *ht = s->private;
793 
794         spin_lock(&ent->lock);
795         /* recalculate to show accurate numbers */
796         rateinfo_recalc(ent, jiffies, ht->cfg.mode);
797 
798         switch (family) {
799         case NFPROTO_IPV4:
800                 seq_printf(s, "%ld %pI4:%u->%pI4:%u %u %u %u\n",
801                            (long)(ent->expires - jiffies)/HZ,
802                            &ent->dst.ip.src,
803                            ntohs(ent->dst.src_port),
804                            &ent->dst.ip.dst,
805                            ntohs(ent->dst.dst_port),
806                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
807                            ent->rateinfo.cost);
808                 break;
809 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
810         case NFPROTO_IPV6:
811                 seq_printf(s, "%ld %pI6:%u->%pI6:%u %u %u %u\n",
812                            (long)(ent->expires - jiffies)/HZ,
813                            &ent->dst.ip6.src,
814                            ntohs(ent->dst.src_port),
815                            &ent->dst.ip6.dst,
816                            ntohs(ent->dst.dst_port),
817                            ent->rateinfo.credit, ent->rateinfo.credit_cap,
818                            ent->rateinfo.cost);
819                 break;
820 #endif
821         default:
822                 BUG();
823         }
824         spin_unlock(&ent->lock);
825         return seq_has_overflowed(s);
826 }
827 
828 static int dl_seq_show(struct seq_file *s, void *v)
829 {
830         struct xt_hashlimit_htable *htable = s->private;
831         unsigned int *bucket = (unsigned int *)v;
832         struct dsthash_ent *ent;
833 
834         if (!hlist_empty(&htable->hash[*bucket])) {
835                 hlist_for_each_entry(ent, &htable->hash[*bucket], node)
836                         if (dl_seq_real_show(ent, htable->family, s))
837                                 return -1;
838         }
839         return 0;
840 }
841 
842 static const struct seq_operations dl_seq_ops = {
843         .start = dl_seq_start,
844         .next  = dl_seq_next,
845         .stop  = dl_seq_stop,
846         .show  = dl_seq_show
847 };
848 
849 static int dl_proc_open(struct inode *inode, struct file *file)
850 {
851         int ret = seq_open(file, &dl_seq_ops);
852 
853         if (!ret) {
854                 struct seq_file *sf = file->private_data;
855                 sf->private = PDE_DATA(inode);
856         }
857         return ret;
858 }
859 
860 static const struct file_operations dl_file_ops = {
861         .owner   = THIS_MODULE,
862         .open    = dl_proc_open,
863         .read    = seq_read,
864         .llseek  = seq_lseek,
865         .release = seq_release
866 };
867 
868 static int __net_init hashlimit_proc_net_init(struct net *net)
869 {
870         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
871 
872         hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net);
873         if (!hashlimit_net->ipt_hashlimit)
874                 return -ENOMEM;
875 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
876         hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net);
877         if (!hashlimit_net->ip6t_hashlimit) {
878                 remove_proc_entry("ipt_hashlimit", net->proc_net);
879                 return -ENOMEM;
880         }
881 #endif
882         return 0;
883 }
884 
885 static void __net_exit hashlimit_proc_net_exit(struct net *net)
886 {
887         struct xt_hashlimit_htable *hinfo;
888         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
889 
890         /* hashlimit_net_exit() is called before hashlimit_mt_destroy().
891          * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc
892          * entries is empty before trying to remove it.
893          */
894         mutex_lock(&hashlimit_mutex);
895         hlist_for_each_entry(hinfo, &hashlimit_net->htables, node)
896                 htable_remove_proc_entry(hinfo);
897         hashlimit_net->ipt_hashlimit = NULL;
898         hashlimit_net->ip6t_hashlimit = NULL;
899         mutex_unlock(&hashlimit_mutex);
900 
901         remove_proc_entry("ipt_hashlimit", net->proc_net);
902 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
903         remove_proc_entry("ip6t_hashlimit", net->proc_net);
904 #endif
905 }
906 
907 static int __net_init hashlimit_net_init(struct net *net)
908 {
909         struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
910 
911         INIT_HLIST_HEAD(&hashlimit_net->htables);
912         return hashlimit_proc_net_init(net);
913 }
914 
915 static void __net_exit hashlimit_net_exit(struct net *net)
916 {
917         hashlimit_proc_net_exit(net);
918 }
919 
920 static struct pernet_operations hashlimit_net_ops = {
921         .init   = hashlimit_net_init,
922         .exit   = hashlimit_net_exit,
923         .id     = &hashlimit_net_id,
924         .size   = sizeof(struct hashlimit_net),
925 };
926 
927 static int __init hashlimit_mt_init(void)
928 {
929         int err;
930 
931         err = register_pernet_subsys(&hashlimit_net_ops);
932         if (err < 0)
933                 return err;
934         err = xt_register_matches(hashlimit_mt_reg,
935               ARRAY_SIZE(hashlimit_mt_reg));
936         if (err < 0)
937                 goto err1;
938 
939         err = -ENOMEM;
940         hashlimit_cachep = kmem_cache_create("xt_hashlimit",
941                                             sizeof(struct dsthash_ent), 0, 0,
942                                             NULL);
943         if (!hashlimit_cachep) {
944                 pr_warn("unable to create slab cache\n");
945                 goto err2;
946         }
947         return 0;
948 
949 err2:
950         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
951 err1:
952         unregister_pernet_subsys(&hashlimit_net_ops);
953         return err;
954 
955 }
956 
957 static void __exit hashlimit_mt_exit(void)
958 {
959         xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg));
960         unregister_pernet_subsys(&hashlimit_net_ops);
961 
962         rcu_barrier_bh();
963         kmem_cache_destroy(hashlimit_cachep);
964 }
965 
966 module_init(hashlimit_mt_init);
967 module_exit(hashlimit_mt_exit);
968 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp