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/ctype.h>
  12 #include <linux/export.h>
  13 #include <linux/jhash.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/types.h>
  16 #include <linux/slab.h>
  17
  18 #include <net/netfilter/nf_conntrack_ecache.h>
  19 #include <net/netfilter/nf_conntrack_labels.h>
  20
  21 static unsigned int label_bits(const struct nf_conn_labels *l)
  22 {
  23         unsigned int longs = l->words;
  24         return longs * BITS_PER_LONG;
  25 }
  26
  27 bool nf_connlabel_match(const struct nf_conn *ct, u16 bit)
  28 {
  29         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  30
  31         if (!labels)
  32                 return false;
  33
  34         return bit < label_bits(labels) && test_bit(bit, labels->bits);
  35 }
  36 EXPORT_SYMBOL_GPL(nf_connlabel_match);
  37
  38 int nf_connlabel_set(struct nf_conn *ct, u16 bit)
  39 {
  40         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  41
  42         if (!labels || bit >= label_bits(labels))
  43                 return -ENOSPC;
  44
  45         if (test_bit(bit, labels->bits))
  46                 return 0;
  47
  48         if (test_and_set_bit(bit, labels->bits))
  49                 nf_conntrack_event_cache(IPCT_LABEL, ct);
  50
  51         return 0;
  52 }
  53 EXPORT_SYMBOL_GPL(nf_connlabel_set);
  54
  55 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  56 static void replace_u32(u32 *address, u32 mask, u32 new)
  57 {
  58         u32 old, tmp;
  59
  60         do {
  61                 old = *address;
  62                 tmp = (old & mask) ^ new;
  63         } while (cmpxchg(address, old, tmp) != old);
  64 }
  65
  66 int nf_connlabels_replace(struct nf_conn *ct,
  67                           const u32 *data,
  68                           const u32 *mask, unsigned int words32)
  69 {
  70         struct nf_conn_labels *labels;
  71         unsigned int size, i;
  72         u32 *dst;
  73
  74         labels = nf_ct_labels_find(ct);
  75         if (!labels)
  76                 return -ENOSPC;
  77
  78         size = labels->words * sizeof(long);
  79         if (size < (words32 * sizeof(u32)))
  80                 words32 = size / sizeof(u32);
  81
  82         dst = (u32 *) labels->bits;
  83         if (words32) {
  84                 for (i = 0; i < words32; i++)
  85                         replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
  86         }
  87
  88         size /= sizeof(u32);
  89         for (i = words32; i < size; i++) /* pad */
  90                 replace_u32(&dst[i], 0, 0);
  91
  92         nf_conntrack_event_cache(IPCT_LABEL, ct);
  93         return 0;
  94 }
  95 EXPORT_SYMBOL_GPL(nf_connlabels_replace);
  96 #endif
  97
  98 static struct nf_ct_ext_type labels_extend __read_mostly = {
  99         .len    = sizeof(struct nf_conn_labels),
 100         .align  = __alignof__(struct nf_conn_labels),
 101         .id     = NF_CT_EXT_LABELS,
 102 };
 103
 104 int nf_conntrack_labels_init(void)
 105 {
 106         return nf_ct_extend_register(&labels_extend);
 107 }
 108
 109 void nf_conntrack_labels_fini(void)
 110 {
 111         nf_ct_extend_unregister(&labels_extend);
 112 }