net/netfilter/nf_conntrack_labels.c

   1 /*
   2  * test/set flag bits stored in conntrack extension area.
   3  *
   4  * (C) 2013 Astaro GmbH & Co KG
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/export.h>
  12 #include <linux/types.h>
  13
  14 #include <net/netfilter/nf_conntrack_ecache.h>
  15 #include <net/netfilter/nf_conntrack_labels.h>
  16
  17 static spinlock_t nf_connlabels_lock;
  18
  19 static int replace_u32(u32 *address, u32 mask, u32 new)
  20 {
  21         u32 old, tmp;
  22
  23         do {
  24                 old = *address;
  25                 tmp = (old & mask) ^ new;
  26                 if (old == tmp)
  27                         return 0;
  28         } while (cmpxchg(address, old, tmp) != old);
  29
  30         return 1;
  31 }
  32
  33 int nf_connlabels_replace(struct nf_conn *ct,
  34                           const u32 *data,
  35                           const u32 *mask, unsigned int words32)
  36 {
  37         struct nf_conn_labels *labels;
  38         unsigned int size, i;
  39         int changed = 0;
  40         u32 *dst;
  41
  42         labels = nf_ct_labels_find(ct);
  43         if (!labels)
  44                 return -ENOSPC;
  45
  46         size = sizeof(labels->bits);
  47         if (size < (words32 * sizeof(u32)))
  48                 words32 = size / sizeof(u32);
  49
  50         dst = (u32 *) labels->bits;
  51         for (i = 0; i < words32; i++)
  52                 changed |= replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
  53
  54         size /= sizeof(u32);
  55         for (i = words32; i < size; i++) /* pad */
  56                 replace_u32(&dst[i], 0, 0);
  57
  58         if (changed)
  59                 nf_conntrack_event_cache(IPCT_LABEL, ct);
  60         return 0;
  61 }
  62 EXPORT_SYMBOL_GPL(nf_connlabels_replace);
  63
  64 int nf_connlabels_get(struct net *net, unsigned int bits)
  65 {
  66         if (BIT_WORD(bits) >= NF_CT_LABELS_MAX_SIZE / sizeof(long))
  67                 return -ERANGE;
  68
  69         spin_lock(&nf_connlabels_lock);
  70         net->ct.labels_used++;
  71         spin_unlock(&nf_connlabels_lock);
  72
  73         return 0;
  74 }
  75 EXPORT_SYMBOL_GPL(nf_connlabels_get);
  76
  77 void nf_connlabels_put(struct net *net)
  78 {
  79         spin_lock(&nf_connlabels_lock);
  80         net->ct.labels_used--;
  81         spin_unlock(&nf_connlabels_lock);
  82 }
  83 EXPORT_SYMBOL_GPL(nf_connlabels_put);
  84
  85 static const struct nf_ct_ext_type labels_extend = {
  86         .len    = sizeof(struct nf_conn_labels),
  87         .align  = __alignof__(struct nf_conn_labels),
  88         .id     = NF_CT_EXT_LABELS,
  89 };
  90
  91 int nf_conntrack_labels_init(void)
  92 {
  93         BUILD_BUG_ON(NF_CT_LABELS_MAX_SIZE / sizeof(long) >= U8_MAX);
  94
  95         spin_lock_init(&nf_connlabels_lock);
  96         return nf_ct_extend_register(&labels_extend);
  97 }
  98
  99 void nf_conntrack_labels_fini(void)
 100 {
 101         nf_ct_extend_unregister(&labels_extend);
 102 }