net/ipv4/inet_fragment.c

   1 /*
   2  * inet fragments management
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  *              Authors:        Pavel Emelyanov <xemul@openvz.org>
  10  *                              Started as consolidation of ipv4/ip_fragment.c,
  11  *                              ipv6/reassembly. and ipv6 nf conntrack reassembly
  12  */
  13
  14 #include <linux/list.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/module.h>
  17 #include <linux/timer.h>
  18 #include <linux/mm.h>
  19 #include <linux/random.h>
  20
  21 #include <net/inet_frag.h>
  22
  23 static void inet_frag_secret_rebuild(unsigned long dummy)
  24 {
  25         struct inet_frags *f = (struct inet_frags *)dummy;
  26         unsigned long now = jiffies;
  27         int i;
  28
  29         write_lock(&f->lock);
  30         get_random_bytes(&f->rnd, sizeof(u32));
  31         for (i = 0; i < INETFRAGS_HASHSZ; i++) {
  32                 struct inet_frag_queue *q;
  33                 struct hlist_node *p, *n;
  34
  35                 hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) {
  36                         unsigned int hval = f->hashfn(q);
  37
  38                         if (hval != i) {
  39                                 hlist_del(&q->list);
  40
  41                                 /* Relink to new hash chain. */
  42                                 hlist_add_head(&q->list, &f->hash[hval]);
  43                         }
  44                 }
  45         }
  46         write_unlock(&f->lock);
  47
  48         mod_timer(&f->secret_timer, now + f->ctl->secret_interval);
  49 }
  50
  51 void inet_frags_init(struct inet_frags *f)
  52 {
  53         int i;
  54
  55         for (i = 0; i < INETFRAGS_HASHSZ; i++)
  56                 INIT_HLIST_HEAD(&f->hash[i]);
  57
  58         INIT_LIST_HEAD(&f->lru_list);
  59         rwlock_init(&f->lock);
  60
  61         f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^
  62                                    (jiffies ^ (jiffies >> 6)));
  63
  64         f->nqueues = 0;
  65         atomic_set(&f->mem, 0);
  66
  67         init_timer(&f->secret_timer);
  68         f->secret_timer.function = inet_frag_secret_rebuild;
  69         f->secret_timer.data = (unsigned long)f;
  70         f->secret_timer.expires = jiffies + f->ctl->secret_interval;
  71         add_timer(&f->secret_timer);
  72 }
  73 EXPORT_SYMBOL(inet_frags_init);
  74
  75 void inet_frags_fini(struct inet_frags *f)
  76 {
  77         del_timer(&f->secret_timer);
  78 }
  79 EXPORT_SYMBOL(inet_frags_fini);
  80
  81 static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
  82 {
  83         write_lock(&f->lock);
  84         hlist_del(&fq->list);
  85         list_del(&fq->lru_list);
  86         f->nqueues--;
  87         write_unlock(&f->lock);
  88 }
  89
  90 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
  91 {
  92         if (del_timer(&fq->timer))
  93                 atomic_dec(&fq->refcnt);
  94
  95         if (!(fq->last_in & COMPLETE)) {
  96                 fq_unlink(fq, f);
  97                 atomic_dec(&fq->refcnt);
  98                 fq->last_in |= COMPLETE;
  99         }
 100 }
 101
 102 EXPORT_SYMBOL(inet_frag_kill);