LXR linux/net/ipv4/netfilter/nf_defrag

   1/* (C) 1999-2001 Paul `Rusty' Russell
   2 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#include <linux/types.h>
  10#include <linux/ip.h>
  11#include <linux/netfilter.h>
  12#include <linux/module.h>
  13#include <linux/skbuff.h>
  14#include <net/route.h>
  15#include <net/ip.h>
  16
  17#include <linux/netfilter_bridge.h>
  18#include <linux/netfilter_ipv4.h>
  19#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
  20#if IS_ENABLED(CONFIG_NF_CONNTRACK)
  21#include <net/netfilter/nf_conntrack.h>
  22#endif
  23#include <net/netfilter/nf_conntrack_zones.h>
  24
  25static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb,
  26                                   u_int32_t user)
  27{
  28        int err;
  29
  30        local_bh_disable();
  31        err = ip_defrag(net, skb, user);
  32        local_bh_enable();
  33
  34        if (!err)
  35                skb->ignore_df = 1;
  36
  37        return err;
  38}
  39
  40static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
  41                                              struct sk_buff *skb)
  42{
  43        u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
  44#if IS_ENABLED(CONFIG_NF_CONNTRACK)
  45        if (skb->nfct) {
  46                enum ip_conntrack_info ctinfo;
  47                const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  48
  49                zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
  50        }
  51#endif
  52        if (nf_bridge_in_prerouting(skb))
  53                return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
  54
  55        if (hooknum == NF_INET_PRE_ROUTING)
  56                return IP_DEFRAG_CONNTRACK_IN + zone_id;
  57        else
  58                return IP_DEFRAG_CONNTRACK_OUT + zone_id;
  59}
  60
  61static unsigned int ipv4_conntrack_defrag(void *priv,
  62                                          struct sk_buff *skb,
  63                                          const struct nf_hook_state *state)
  64{
  65        struct sock *sk = skb->sk;
  66
  67        if (sk && sk_fullsock(sk) && (sk->sk_family == PF_INET) &&
  68            inet_sk(sk)->nodefrag)
  69                return NF_ACCEPT;
  70
  71#if IS_ENABLED(CONFIG_NF_CONNTRACK)
  72#if !IS_ENABLED(CONFIG_NF_NAT)
  73        /* Previously seen (loopback)?  Ignore.  Do this before
  74           fragment check. */
  75        if (skb->nfct && !nf_ct_is_template((struct nf_conn *)skb->nfct))
  76                return NF_ACCEPT;
  77#endif
  78#endif
  79        /* Gather fragments. */
  80        if (ip_is_fragment(ip_hdr(skb))) {
  81                enum ip_defrag_users user =
  82                        nf_ct_defrag_user(state->hook, skb);
  83
  84                if (nf_ct_ipv4_gather_frags(state->net, skb, user))
  85                        return NF_STOLEN;
  86        }
  87        return NF_ACCEPT;
  88}
  89
  90static struct nf_hook_ops ipv4_defrag_ops[] = {
  91        {
  92                .hook           = ipv4_conntrack_defrag,
  93                .pf             = NFPROTO_IPV4,
  94                .hooknum        = NF_INET_PRE_ROUTING,
  95                .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
  96        },
  97        {
  98                .hook           = ipv4_conntrack_defrag,
  99                .pf             = NFPROTO_IPV4,
 100                .hooknum        = NF_INET_LOCAL_OUT,
 101                .priority       = NF_IP_PRI_CONNTRACK_DEFRAG,
 102        },
 103};
 104
 105static int __init nf_defrag_init(void)
 106{
 107        return nf_register_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 108}
 109
 110static void __exit nf_defrag_fini(void)
 111{
 112        nf_unregister_hooks(ipv4_defrag_ops, ARRAY_SIZE(ipv4_defrag_ops));
 113}
 114
 115void nf_defrag_ipv4_enable(void)
 116{
 117}
 118EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
 119
 120module_init(nf_defrag_init);
 121module_exit(nf_defrag_fini);
 122
 123MODULE_LICENSE("GPL");
 124