| // SPDX-License-Identifier: GPL-2.0-only |
| /* (C) 1999-2001 Paul `Rusty' Russell |
| * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
| */ |
| |
| #include <linux/types.h> |
| #include <linux/ip.h> |
| #include <linux/netfilter.h> |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <net/netns/generic.h> |
| #include <net/route.h> |
| #include <net/ip.h> |
| |
| #include <linux/netfilter_bridge.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <net/netfilter/ipv4/nf_defrag_ipv4.h> |
| #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
| #include <net/netfilter/nf_conntrack.h> |
| #endif |
| #include <net/netfilter/nf_conntrack_zones.h> |
| |
| static unsigned int defrag4_pernet_id __read_mostly; |
| static DEFINE_MUTEX(defrag4_mutex); |
| |
| struct defrag4_pernet { |
| unsigned int users; |
| }; |
| |
| static int nf_ct_ipv4_gather_frags(struct net *net, struct sk_buff *skb, |
| u_int32_t user) |
| { |
| int err; |
| |
| local_bh_disable(); |
| err = ip_defrag(net, skb, user); |
| local_bh_enable(); |
| |
| if (!err) |
| skb->ignore_df = 1; |
| |
| return err; |
| } |
| |
| static enum ip_defrag_users nf_ct_defrag_user(unsigned int hooknum, |
| struct sk_buff *skb) |
| { |
| u16 zone_id = NF_CT_DEFAULT_ZONE_ID; |
| #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
| if (skb_nfct(skb)) { |
| enum ip_conntrack_info ctinfo; |
| const struct nf_conn *ct = nf_ct_get(skb, &ctinfo); |
| |
| zone_id = nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo)); |
| } |
| #endif |
| if (nf_bridge_in_prerouting(skb)) |
| return IP_DEFRAG_CONNTRACK_BRIDGE_IN + zone_id; |
| |
| if (hooknum == NF_INET_PRE_ROUTING) |
| return IP_DEFRAG_CONNTRACK_IN + zone_id; |
| else |
| return IP_DEFRAG_CONNTRACK_OUT + zone_id; |
| } |
| |
| static unsigned int ipv4_conntrack_defrag(void *priv, |
| struct sk_buff *skb, |
| const struct nf_hook_state *state) |
| { |
| struct sock *sk = skb->sk; |
| |
| if (sk && sk_fullsock(sk) && (sk->sk_family == PF_INET) && |
| inet_sk(sk)->nodefrag) |
| return NF_ACCEPT; |
| |
| #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
| #if !IS_ENABLED(CONFIG_NF_NAT) |
| /* Previously seen (loopback)? Ignore. Do this before |
| fragment check. */ |
| if (skb_nfct(skb) && !nf_ct_is_template((struct nf_conn *)skb_nfct(skb))) |
| return NF_ACCEPT; |
| #endif |
| if (skb->_nfct == IP_CT_UNTRACKED) |
| return NF_ACCEPT; |
| #endif |
| /* Gather fragments. */ |
| if (ip_is_fragment(ip_hdr(skb))) { |
| enum ip_defrag_users user = |
| nf_ct_defrag_user(state->hook, skb); |
| |
| if (nf_ct_ipv4_gather_frags(state->net, skb, user)) |
| return NF_STOLEN; |
| } |
| return NF_ACCEPT; |
| } |
| |
| static const struct nf_hook_ops ipv4_defrag_ops[] = { |
| { |
| .hook = ipv4_conntrack_defrag, |
| .pf = NFPROTO_IPV4, |
| .hooknum = NF_INET_PRE_ROUTING, |
| .priority = NF_IP_PRI_CONNTRACK_DEFRAG, |
| }, |
| { |
| .hook = ipv4_conntrack_defrag, |
| .pf = NFPROTO_IPV4, |
| .hooknum = NF_INET_LOCAL_OUT, |
| .priority = NF_IP_PRI_CONNTRACK_DEFRAG, |
| }, |
| }; |
| |
| static void __net_exit defrag4_net_exit(struct net *net) |
| { |
| struct defrag4_pernet *nf_defrag = net_generic(net, defrag4_pernet_id); |
| |
| if (nf_defrag->users) { |
| nf_unregister_net_hooks(net, ipv4_defrag_ops, |
| ARRAY_SIZE(ipv4_defrag_ops)); |
| nf_defrag->users = 0; |
| } |
| } |
| |
| static struct pernet_operations defrag4_net_ops = { |
| .exit = defrag4_net_exit, |
| .id = &defrag4_pernet_id, |
| .size = sizeof(struct defrag4_pernet), |
| }; |
| |
| static int __init nf_defrag_init(void) |
| { |
| return register_pernet_subsys(&defrag4_net_ops); |
| } |
| |
| static void __exit nf_defrag_fini(void) |
| { |
| unregister_pernet_subsys(&defrag4_net_ops); |
| } |
| |
| int nf_defrag_ipv4_enable(struct net *net) |
| { |
| struct defrag4_pernet *nf_defrag = net_generic(net, defrag4_pernet_id); |
| int err = 0; |
| |
| mutex_lock(&defrag4_mutex); |
| if (nf_defrag->users == UINT_MAX) { |
| err = -EOVERFLOW; |
| goto out_unlock; |
| } |
| |
| if (nf_defrag->users) { |
| nf_defrag->users++; |
| goto out_unlock; |
| } |
| |
| err = nf_register_net_hooks(net, ipv4_defrag_ops, |
| ARRAY_SIZE(ipv4_defrag_ops)); |
| if (err == 0) |
| nf_defrag->users = 1; |
| |
| out_unlock: |
| mutex_unlock(&defrag4_mutex); |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(nf_defrag_ipv4_enable); |
| |
| void nf_defrag_ipv4_disable(struct net *net) |
| { |
| struct defrag4_pernet *nf_defrag = net_generic(net, defrag4_pernet_id); |
| |
| mutex_lock(&defrag4_mutex); |
| if (nf_defrag->users) { |
| nf_defrag->users--; |
| if (nf_defrag->users == 0) |
| nf_unregister_net_hooks(net, ipv4_defrag_ops, |
| ARRAY_SIZE(ipv4_defrag_ops)); |
| } |
| |
| mutex_unlock(&defrag4_mutex); |
| } |
| EXPORT_SYMBOL_GPL(nf_defrag_ipv4_disable); |
| |
| module_init(nf_defrag_init); |
| module_exit(nf_defrag_fini); |
| |
| MODULE_LICENSE("GPL"); |