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 unsigned int label_bits(const struct nf_conn_labels *l)
  18 {
  19         unsigned int longs = l->words;
  20         return longs * BITS_PER_LONG;
  21 }
  22
  23 bool nf_connlabel_match(const struct nf_conn *ct, u16 bit)
  24 {
  25         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  26
  27         if (!labels)
  28                 return false;
  29
  30         return bit < label_bits(labels) && test_bit(bit, labels->bits);
  31 }
  32 EXPORT_SYMBOL_GPL(nf_connlabel_match);
  33
  34 int nf_connlabel_set(struct nf_conn *ct, u16 bit)
  35 {
  36         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  37
  38         if (!labels || bit >= label_bits(labels))
  39                 return -ENOSPC;
  40
  41         if (test_bit(bit, labels->bits))
  42                 return 0;
  43
  44         if (!test_and_set_bit(bit, labels->bits))
  45                 nf_conntrack_event_cache(IPCT_LABEL, ct);
  46
  47         return 0;
  48 }
  49 EXPORT_SYMBOL_GPL(nf_connlabel_set);
  50
  51 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  52 static void replace_u32(u32 *address, u32 mask, u32 new)
  53 {
  54         u32 old, tmp;
  55
  56         do {
  57                 old = *address;
  58                 tmp = (old & mask) ^ new;
  59         } while (cmpxchg(address, old, tmp) != old);
  60 }
  61
  62 int nf_connlabels_replace(struct nf_conn *ct,
  63                           const u32 *data,
  64                           const u32 *mask, unsigned int words32)
  65 {
  66         struct nf_conn_labels *labels;
  67         unsigned int size, i;
  68         u32 *dst;
  69
  70         labels = nf_ct_labels_find(ct);
  71         if (!labels)
  72                 return -ENOSPC;
  73
  74         size = labels->words * sizeof(long);
  75         if (size < (words32 * sizeof(u32)))
  76                 words32 = size / sizeof(u32);
  77
  78         dst = (u32 *) labels->bits;
  79         if (words32) {
  80                 for (i = 0; i < words32; i++)
  81                         replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
  82         }
  83
  84         size /= sizeof(u32);
  85         for (i = words32; i < size; i++) /* pad */
  86                 replace_u32(&dst[i], 0, 0);
  87
  88         nf_conntrack_event_cache(IPCT_LABEL, ct);
  89         return 0;
  90 }
  91 EXPORT_SYMBOL_GPL(nf_connlabels_replace);
  92 #endif
  93
  94 static struct nf_ct_ext_type labels_extend __read_mostly = {
  95         .len    = sizeof(struct nf_conn_labels),
  96         .align  = __alignof__(struct nf_conn_labels),
  97         .id     = NF_CT_EXT_LABELS,
  98 };
  99
 100 int nf_conntrack_labels_init(void)
 101 {
 102         return nf_ct_extend_register(&labels_extend);
 103 }
 104
 105 void nf_conntrack_labels_fini(void)
 106 {
 107         nf_ct_extend_unregister(&labels_extend);
 108 }