// SPDX-License-Identifier: GPL-2.0-only
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*/
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#include <linux/types.h>
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#include <linux/ip.h>
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#include <linux/netfilter.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <net/netns/generic.h>
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#include <net/route.h>
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#include <net/ip.h>
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#include <linux/netfilter_bridge.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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#include <net/netfilter/nf_conntrack.h>
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#endif
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#include <net/netfilter/nf_conntrack_zones.h>
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static DEFINE_MUTEX(defrag4_mutex);
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static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb,
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u_int32_t user)
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{
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int err;
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local_bh_disable();
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err = ip_defrag(net, skb, user);
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local_bh_enable();
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if (!err)
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skb->ignore_df = 1;
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return err;
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}
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static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum,
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struct sk_buff *skb)
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{
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u16 zone_id = NF_CT_DEFAULT_ZONE_ID;
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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if (skb_nfct(skb)) {
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enum ip_conntrack_info ctinfo;
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const struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
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zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo));
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}
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#endif
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if (nf_bridge_in_prerouting(skb))
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return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id;
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if (hooknum == NF_INET_PRE_ROUTING)
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return IP_DEFRAG_CONNTRACK_IN + zone_id;
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else
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return IP_DEFRAG_CONNTRACK_OUT + zone_id;
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}
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static unsigned int ipv4_conntrack_defrag(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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struct sock *sk = skb->sk;
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if (sk && sk_fullsock(sk) && (sk->sk_family == PF_INET) &&
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inet_sk(sk)->nodefrag)
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return NF_ACCEPT;
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#if IS_ENABLED(CONFIG_NF_CONNTRACK)
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#if !IS_ENABLED(CONFIG_NF_NAT)
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/* Previously seen (loopback)? Ignore. Do this before
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fragment check. */
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if (skb_nfct(skb) && !nf_ct_is_template((struct nf_conn *)skb_nfct(skb)))
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return NF_ACCEPT;
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#endif
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if (skb->_nfct == IP_CT_UNTRACKED)
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return NF_ACCEPT;
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#endif
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/* Gather fragments. */
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if (ip_is_fragment(ip_hdr(skb))) {
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enum ip_defrag_users user =
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nf_ct_defrag_user(state->hook, skb);
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if (nf_ct_ipv4_gather_frags(state->net, skb, user))
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return NF_STOLEN;
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}
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return NF_ACCEPT;
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}
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static const struct nf_hook_ops ipv4_defrag_ops[] = {
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{
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.hook = ipv4_conntrack_defrag,
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.pf = NFPROTO_IPV4,
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.hooknum = NF_INET_PRE_ROUTING,
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.priority = NF_IP_PRI_CONNTRACK_DEFRAG,
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},
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{
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.hook = ipv4_conntrack_defrag,
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.pf = NFPROTO_IPV4,
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.hooknum = NF_INET_LOCAL_OUT,
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.priority = NF_IP_PRI_CONNTRACK_DEFRAG,
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},
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};
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static void __net_exit defrag4_net_exit(struct net *net)
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{
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if (net->nf.defrag_ipv4) {
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nf_unregister_net_hooks(net, ipv4_defrag_ops,
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ARRAY_SIZE(ipv4_defrag_ops));
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net->nf.defrag_ipv4 = false;
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}
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}
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static struct pernet_operations defrag4_net_ops = {
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.exit = defrag4_net_exit,
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};
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static int __init nf_defrag_init(void)
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{
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return register_pernet_subsys(&defrag4_net_ops);
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}
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static void __exit nf_defrag_fini(void)
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{
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unregister_pernet_subsys(&defrag4_net_ops);
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}
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int nf_defrag_ipv4_enable(struct net *net)
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{
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int err = 0;
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might_sleep();
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if (net->nf.defrag_ipv4)
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return 0;
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mutex_lock(&defrag4_mutex);
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if (net->nf.defrag_ipv4)
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goto out_unlock;
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err = nf_register_net_hooks(net, ipv4_defrag_ops,
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ARRAY_SIZE(ipv4_defrag_ops));
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if (err == 0)
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net->nf.defrag_ipv4 = true;
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out_unlock:
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mutex_unlock(&defrag4_mutex);
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return err;
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}
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EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable);
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module_init(nf_defrag_init);
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module_exit(nf_defrag_fini);
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MODULE_LICENSE("GPL");
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