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netfilter.c (3534B)


      1 /*
      2  * IPv6 specific functions of netfilter core
      3  *
      4  * Rusty Russell (C) 2000 -- This code is GPL.
      5  * Patrick McHardy (C) 2006-2012
      6  */
      7 #include <linux/kernel.h>
      8 #include <linux/init.h>
      9 #include <linux/ipv6.h>
     10 #include <linux/netfilter.h>
     11 #include <linux/netfilter_ipv6.h>
     12 #include <linux/export.h>
     13 #include <net/addrconf.h>
     14 #include <net/dst.h>
     15 #include <net/ipv6.h>
     16 #include <net/ip6_route.h>
     17 #include <net/xfrm.h>
     18 #include <net/netfilter/nf_queue.h>
     19 
     20 int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
     21 {
     22 	const struct ipv6hdr *iph = ipv6_hdr(skb);
     23 	struct sock *sk = sk_to_full_sk(skb->sk);
     24 	unsigned int hh_len;
     25 	struct dst_entry *dst;
     26 	int strict = (ipv6_addr_type(&iph->daddr) &
     27 		      (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
     28 	struct flowi6 fl6 = {
     29 		.flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :
     30 			strict ? skb_dst(skb)->dev->ifindex : 0,
     31 		.flowi6_mark = skb->mark,
     32 		.flowi6_uid = sock_net_uid(net, sk),
     33 		.daddr = iph->daddr,
     34 		.saddr = iph->saddr,
     35 	};
     36 	int err;
     37 
     38 	dst = ip6_route_output(net, sk, &fl6);
     39 	err = dst->error;
     40 	if (err) {
     41 		IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
     42 		net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
     43 		dst_release(dst);
     44 		return err;
     45 	}
     46 
     47 	/* Drop old route. */
     48 	skb_dst_drop(skb);
     49 
     50 	skb_dst_set(skb, dst);
     51 
     52 #ifdef CONFIG_XFRM
     53 	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
     54 	    xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
     55 		skb_dst_set(skb, NULL);
     56 		dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
     57 		if (IS_ERR(dst))
     58 			return PTR_ERR(dst);
     59 		skb_dst_set(skb, dst);
     60 	}
     61 #endif
     62 
     63 	/* Change in oif may mean change in hh_len. */
     64 	hh_len = skb_dst(skb)->dev->hard_header_len;
     65 	if (skb_headroom(skb) < hh_len &&
     66 	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
     67 			     0, GFP_ATOMIC))
     68 		return -ENOMEM;
     69 
     70 	return 0;
     71 }
     72 EXPORT_SYMBOL(ip6_route_me_harder);
     73 
     74 static int nf_ip6_reroute(struct sk_buff *skb,
     75 			  const struct nf_queue_entry *entry)
     76 {
     77 	struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
     78 
     79 	if (entry->state.hook == NF_INET_LOCAL_OUT) {
     80 		const struct ipv6hdr *iph = ipv6_hdr(skb);
     81 		if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
     82 		    !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
     83 		    skb->mark != rt_info->mark)
     84 			return ip6_route_me_harder(entry->state.net, skb);
     85 	}
     86 	return 0;
     87 }
     88 
     89 int __nf_ip6_route(struct net *net, struct dst_entry **dst,
     90 		   struct flowi *fl, bool strict)
     91 {
     92 	static const struct ipv6_pinfo fake_pinfo;
     93 	static const struct inet_sock fake_sk = {
     94 		/* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
     95 		.sk.sk_bound_dev_if = 1,
     96 		.pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
     97 	};
     98 	const void *sk = strict ? &fake_sk : NULL;
     99 	struct dst_entry *result;
    100 	int err;
    101 
    102 	result = ip6_route_output(net, sk, &fl->u.ip6);
    103 	err = result->error;
    104 	if (err)
    105 		dst_release(result);
    106 	else
    107 		*dst = result;
    108 	return err;
    109 }
    110 EXPORT_SYMBOL_GPL(__nf_ip6_route);
    111 
    112 static const struct nf_ipv6_ops ipv6ops = {
    113 #if IS_MODULE(CONFIG_IPV6)
    114 	.chk_addr		= ipv6_chk_addr,
    115 	.route_me_harder	= ip6_route_me_harder,
    116 	.dev_get_saddr		= ipv6_dev_get_saddr,
    117 	.route			= __nf_ip6_route,
    118 #endif
    119 	.route_input		= ip6_route_input,
    120 	.fragment		= ip6_fragment,
    121 	.reroute		= nf_ip6_reroute,
    122 };
    123 
    124 int __init ipv6_netfilter_init(void)
    125 {
    126 	RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
    127 	return 0;
    128 }
    129 
    130 /* This can be called from inet6_init() on errors, so it cannot
    131  * be marked __exit. -DaveM
    132  */
    133 void ipv6_netfilter_fini(void)
    134 {
    135 	RCU_INIT_POINTER(nf_ipv6_ops, NULL);
    136 }