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 unsigned int label_bits(const struct nf_conn_labels *l)
  20 {
  21         unsigned int longs = l->words;
  22         return longs * BITS_PER_LONG;
  23 }
  24
  25 bool nf_connlabel_match(const struct nf_conn *ct, u16 bit)
  26 {
  27         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  28
  29         if (!labels)
  30                 return false;
  31
  32         return bit < label_bits(labels) && test_bit(bit, labels->bits);
  33 }
  34 EXPORT_SYMBOL_GPL(nf_connlabel_match);
  35
  36 int nf_connlabel_set(struct nf_conn *ct, u16 bit)
  37 {
  38         struct nf_conn_labels *labels = nf_ct_labels_find(ct);
  39
  40         if (!labels || bit >= label_bits(labels))
  41                 return -ENOSPC;
  42
  43         if (test_bit(bit, labels->bits))
  44                 return 0;
  45
  46         if (!test_and_set_bit(bit, labels->bits))
  47                 nf_conntrack_event_cache(IPCT_LABEL, ct);
  48
  49         return 0;
  50 }
  51 EXPORT_SYMBOL_GPL(nf_connlabel_set);
  52
  53 static void replace_u32(u32 *address, u32 mask, u32 new)
  54 {
  55         u32 old, tmp;
  56
  57         do {
  58                 old = *address;
  59                 tmp = (old & mask) ^ new;
  60         } while (cmpxchg(address, old, tmp) != old);
  61 }
  62
  63 int nf_connlabels_replace(struct nf_conn *ct,
  64                           const u32 *data,
  65                           const u32 *mask, unsigned int words32)
  66 {
  67         struct nf_conn_labels *labels;
  68         unsigned int size, i;
  69         u32 *dst;
  70
  71         labels = nf_ct_labels_find(ct);
  72         if (!labels)
  73                 return -ENOSPC;
  74
  75         size = labels->words * sizeof(long);
  76         if (size < (words32 * sizeof(u32)))
  77                 words32 = size / sizeof(u32);
  78
  79         dst = (u32 *) labels->bits;
  80         if (words32) {
  81                 for (i = 0; i < words32; i++)
  82                         replace_u32(&dst[i], mask ? ~mask[i] : 0, data[i]);
  83         }
  84
  85         size /= sizeof(u32);
  86         for (i = words32; i < size; i++) /* pad */
  87                 replace_u32(&dst[i], 0, 0);
  88
  89         nf_conntrack_event_cache(IPCT_LABEL, ct);
  90         return 0;
  91 }
  92 EXPORT_SYMBOL_GPL(nf_connlabels_replace);
  93
  94 int nf_connlabels_get(struct net *net, unsigned int n_bits)
  95 {
  96         size_t words;
  97
  98         if (n_bits > (NF_CT_LABELS_MAX_SIZE * BITS_PER_BYTE))
  99                 return -ERANGE;
 100
 101         words = BITS_TO_LONGS(n_bits);
 102
 103         spin_lock(&nf_connlabels_lock);
 104         net->ct.labels_used++;
 105         if (words > net->ct.label_words)
 106                 net->ct.label_words = words;
 107         spin_unlock(&nf_connlabels_lock);
 108
 109         return 0;
 110 }
 111 EXPORT_SYMBOL_GPL(nf_connlabels_get);
 112
 113 void nf_connlabels_put(struct net *net)
 114 {
 115         spin_lock(&nf_connlabels_lock);
 116         net->ct.labels_used--;
 117         if (net->ct.labels_used == 0)
 118                 net->ct.label_words = 0;
 119         spin_unlock(&nf_connlabels_lock);
 120 }
 121 EXPORT_SYMBOL_GPL(nf_connlabels_put);
 122
 123 static struct nf_ct_ext_type labels_extend __read_mostly = {
 124         .len    = sizeof(struct nf_conn_labels),
 125         .align  = __alignof__(struct nf_conn_labels),
 126         .id     = NF_CT_EXT_LABELS,
 127 };
 128
 129 int nf_conntrack_labels_init(void)
 130 {
 131         spin_lock_init(&nf_connlabels_lock);
 132         return nf_ct_extend_register(&labels_extend);
 133 }
 134
 135 void nf_conntrack_labels_fini(void)
 136 {
 137         nf_ct_extend_unregister(&labels_extend);
 138 }