net/netfilter/nf_conntrack_labels.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * test/set flag bits stored in conntrack extension area.
   4  *
   5  * (C) 2013 Astaro GmbH & Co KG
   6  */
   7
   8 #include <linux/export.h>
   9 #include <linux/types.h>
  10
  11 #include <net/netfilter/nf_conntrack_ecache.h>
  12 #include <net/netfilter/nf_conntrack_labels.h>
  13
  14 static int replace_u32(u32 *address, u32 mask, u32 new)
  15 {
  16         u32 old, tmp;
  17
  18         do {
  19                 old = *address;
  20                 tmp = (old & mask) ^ new;
  21                 if (old == tmp)
  22                         return 0;
  23         } while (cmpxchg(address, old, tmp) != old);
  24
  25         return 1;
  26 }
  27
  28 int nf_connlabels_replace(struct nf_conn *ct,
  29                           const u32 *data,
  30                           const u32 *mask, unsigned int words32)
  31 {
  32         struct nf_conn_labels *labels;
  33         unsigned int size, i;
  34         int changed = 0;
  35         u32 *dst;
  36
  37         labels = nf_ct_labels_find(ct);
  38         if (!labels)
  39                 return -ENOSPC;
  40
  41         size = sizeof(labels->bits);
  42         if (size < (words32 * sizeof(u32)))
  43                 words32 = size / sizeof(u32);
  44
  45         dst = (u32 *) labels->bits;
  46         for (i = 0; i < words32; i++)
  47                 changed |= replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
  48
  49         size /= sizeof(u32);
  50         for (i = words32; i < size; i++) /* pad */
  51                 replace_u32(&dst[i], 0, 0);
  52
  53         if (changed)
  54                 nf_conntrack_event_cache(IPCT_LABEL, ct);
  55         return 0;
  56 }
  57 EXPORT_SYMBOL_GPL(nf_connlabels_replace);
  58
  59 int nf_connlabels_get(struct net *net, unsigned int bits)
  60 {
  61         int v;
  62
  63         if (BIT_WORD(bits) >= NF_CT_LABELS_MAX_SIZE / sizeof(long))
  64                 return -ERANGE;
  65
  66         BUILD_BUG_ON(NF_CT_LABELS_MAX_SIZE / sizeof(long) >= U8_MAX);
  67
  68         v = atomic_inc_return_relaxed(&net->ct.labels_used);
  69         WARN_ON_ONCE(v <= 0);
  70
  71         return 0;
  72 }
  73 EXPORT_SYMBOL_GPL(nf_connlabels_get);
  74
  75 void nf_connlabels_put(struct net *net)
  76 {
  77         int v = atomic_dec_return_relaxed(&net->ct.labels_used);
  78
  79         WARN_ON_ONCE(v < 0);
  80 }
  81 EXPORT_SYMBOL_GPL(nf_connlabels_put);