net/netfilter/nf_conntrack_extend.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Structure dynamic extension infrastructure
   3  * Copyright (C) 2004 Rusty Russell IBM Corporation
   4  * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
   5  * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/kmemleak.h>
   9 #include <linux/module.h>
  10 #include <linux/mutex.h>
  11 #include <linux/rcupdate.h>
  12 #include <linux/slab.h>
  13 #include <linux/skbuff.h>
  14 #include <net/netfilter/nf_conntrack_extend.h>
  15
  16 #include <net/netfilter/nf_conntrack_helper.h>
  17 #include <net/netfilter/nf_conntrack_acct.h>
  18 #include <net/netfilter/nf_conntrack_seqadj.h>
  19 #include <net/netfilter/nf_conntrack_ecache.h>
  20 #include <net/netfilter/nf_conntrack_zones.h>
  21 #include <net/netfilter/nf_conntrack_timestamp.h>
  22 #include <net/netfilter/nf_conntrack_timeout.h>
  23 #include <net/netfilter/nf_conntrack_labels.h>
  24 #include <net/netfilter/nf_conntrack_synproxy.h>
  25 #include <net/netfilter/nf_conntrack_act_ct.h>
  26 #include <net/netfilter/nf_nat.h>
  27
  28 #define NF_CT_EXT_PREALLOC      128u /* conntrack events are on by default */
  29
  30 atomic_t nf_conntrack_ext_genid __read_mostly = ATOMIC_INIT(1);
  31
  32 static const u8 nf_ct_ext_type_len[NF_CT_EXT_NUM] = {
  33         [NF_CT_EXT_HELPER] = sizeof(struct nf_conn_help),
  34 #if IS_ENABLED(CONFIG_NF_NAT)
  35         [NF_CT_EXT_NAT] = sizeof(struct nf_conn_nat),
  36 #endif
  37         [NF_CT_EXT_SEQADJ] = sizeof(struct nf_conn_seqadj),
  38         [NF_CT_EXT_ACCT] = sizeof(struct nf_conn_acct),
  39 #ifdef CONFIG_NF_CONNTRACK_EVENTS
  40         [NF_CT_EXT_ECACHE] = sizeof(struct nf_conntrack_ecache),
  41 #endif
  42 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
  43         [NF_CT_EXT_TSTAMP] = sizeof(struct nf_conn_acct),
  44 #endif
  45 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
  46         [NF_CT_EXT_TIMEOUT] = sizeof(struct nf_conn_tstamp),
  47 #endif
  48 #ifdef CONFIG_NF_CONNTRACK_LABELS
  49         [NF_CT_EXT_LABELS] = sizeof(struct nf_conn_labels),
  50 #endif
  51 #if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
  52         [NF_CT_EXT_SYNPROXY] = sizeof(struct nf_conn_synproxy),
  53 #endif
  54 #if IS_ENABLED(CONFIG_NET_ACT_CT)
  55         [NF_CT_EXT_ACT_CT] = sizeof(struct nf_conn_act_ct_ext),
  56 #endif
  57 };
  58
  59 static __always_inline unsigned int total_extension_size(void)
  60 {
  61         /* remember to add new extensions below */
  62         BUILD_BUG_ON(NF_CT_EXT_NUM > 10);
  63
  64         return sizeof(struct nf_ct_ext) +
  65                sizeof(struct nf_conn_help)
  66 #if IS_ENABLED(CONFIG_NF_NAT)
  67                 + sizeof(struct nf_conn_nat)
  68 #endif
  69                 + sizeof(struct nf_conn_seqadj)
  70                 + sizeof(struct nf_conn_acct)
  71 #ifdef CONFIG_NF_CONNTRACK_EVENTS
  72                 + sizeof(struct nf_conntrack_ecache)
  73 #endif
  74 #ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
  75                 + sizeof(struct nf_conn_tstamp)
  76 #endif
  77 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
  78                 + sizeof(struct nf_conn_timeout)
  79 #endif
  80 #ifdef CONFIG_NF_CONNTRACK_LABELS
  81                 + sizeof(struct nf_conn_labels)
  82 #endif
  83 #if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
  84                 + sizeof(struct nf_conn_synproxy)
  85 #endif
  86 #if IS_ENABLED(CONFIG_NET_ACT_CT)
  87                 + sizeof(struct nf_conn_act_ct_ext)
  88 #endif
  89         ;
  90 }
  91
  92 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
  93 {
  94         unsigned int newlen, newoff, oldlen, alloc;
  95         struct nf_ct_ext *new;
  96
  97         /* Conntrack must not be confirmed to avoid races on reallocation. */
  98         WARN_ON(nf_ct_is_confirmed(ct));
  99
 100         /* struct nf_ct_ext uses u8 to store offsets/size */
 101         BUILD_BUG_ON(total_extension_size() > 255u);
 102
 103         if (ct->ext) {
 104                 const struct nf_ct_ext *old = ct->ext;
 105
 106                 if (__nf_ct_ext_exist(old, id))
 107                         return NULL;
 108                 oldlen = old->len;
 109         } else {
 110                 oldlen = sizeof(*new);
 111         }
 112
 113         newoff = ALIGN(oldlen, __alignof__(struct nf_ct_ext));
 114         newlen = newoff + nf_ct_ext_type_len[id];
 115
 116         alloc = max(newlen, NF_CT_EXT_PREALLOC);
 117         new = krealloc(ct->ext, alloc, gfp);
 118         if (!new)
 119                 return NULL;
 120
 121         if (!ct->ext) {
 122                 memset(new->offset, 0, sizeof(new->offset));
 123                 new->gen_id = atomic_read(&nf_conntrack_ext_genid);
 124         }
 125
 126         new->offset[id] = newoff;
 127         new->len = newlen;
 128         memset((void *)new + newoff, 0, newlen - newoff);
 129
 130         ct->ext = new;
 131         return (void *)new + newoff;
 132 }
 133 EXPORT_SYMBOL(nf_ct_ext_add);
 134
 135 /* Use nf_ct_ext_find wrapper. This is only useful for unconfirmed entries. */
 136 void *__nf_ct_ext_find(const struct nf_ct_ext *ext, u8 id)
 137 {
 138         unsigned int gen_id = atomic_read(&nf_conntrack_ext_genid);
 139         unsigned int this_id = READ_ONCE(ext->gen_id);
 140
 141         if (!__nf_ct_ext_exist(ext, id))
 142                 return NULL;
 143
 144         if (this_id == 0 || ext->gen_id == gen_id)
 145                 return (void *)ext + ext->offset[id];
 146
 147         return NULL;
 148 }
 149 EXPORT_SYMBOL(__nf_ct_ext_find);
 150
 151 void nf_ct_ext_bump_genid(void)
 152 {
 153         unsigned int value = atomic_inc_return(&nf_conntrack_ext_genid);
 154
 155         if (value == UINT_MAX)
 156                 atomic_set(&nf_conntrack_ext_genid, 1);
 157
 158         msleep(HZ);
 159 }