xref: /openbmc/linux/net/ipv6/netfilter.c (revision c537b994)
1 #include <linux/kernel.h>
2 #include <linux/init.h>
3 #include <linux/ipv6.h>
4 #include <linux/netfilter.h>
5 #include <linux/netfilter_ipv6.h>
6 #include <net/dst.h>
7 #include <net/ipv6.h>
8 #include <net/ip6_route.h>
9 #include <net/xfrm.h>
10 #include <net/ip6_checksum.h>
11 
12 int ip6_route_me_harder(struct sk_buff *skb)
13 {
14 	struct ipv6hdr *iph = skb->nh.ipv6h;
15 	struct dst_entry *dst;
16 	struct flowi fl = {
17 		.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
18 		.mark = skb->mark,
19 		.nl_u =
20 		{ .ip6_u =
21 		  { .daddr = iph->daddr,
22 		    .saddr = iph->saddr, } },
23 	};
24 
25 	dst = ip6_route_output(skb->sk, &fl);
26 
27 #ifdef CONFIG_XFRM
28 	if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
29 	    xfrm_decode_session(skb, &fl, AF_INET6) == 0)
30 		if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
31 			return -1;
32 #endif
33 
34 	if (dst->error) {
35 		IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
36 		LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
37 		dst_release(dst);
38 		return -EINVAL;
39 	}
40 
41 	/* Drop old route. */
42 	dst_release(skb->dst);
43 
44 	skb->dst = dst;
45 	return 0;
46 }
47 EXPORT_SYMBOL(ip6_route_me_harder);
48 
49 /*
50  * Extra routing may needed on local out, as the QUEUE target never
51  * returns control to the table.
52  */
53 
54 struct ip6_rt_info {
55 	struct in6_addr daddr;
56 	struct in6_addr saddr;
57 };
58 
59 static void nf_ip6_saveroute(const struct sk_buff *skb, struct nf_info *info)
60 {
61 	struct ip6_rt_info *rt_info = nf_info_reroute(info);
62 
63 	if (info->hook == NF_IP6_LOCAL_OUT) {
64 		struct ipv6hdr *iph = skb->nh.ipv6h;
65 
66 		rt_info->daddr = iph->daddr;
67 		rt_info->saddr = iph->saddr;
68 	}
69 }
70 
71 static int nf_ip6_reroute(struct sk_buff **pskb, const struct nf_info *info)
72 {
73 	struct ip6_rt_info *rt_info = nf_info_reroute(info);
74 
75 	if (info->hook == NF_IP6_LOCAL_OUT) {
76 		struct ipv6hdr *iph = (*pskb)->nh.ipv6h;
77 		if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
78 		    !ipv6_addr_equal(&iph->saddr, &rt_info->saddr))
79 			return ip6_route_me_harder(*pskb);
80 	}
81 	return 0;
82 }
83 
84 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
85 			     unsigned int dataoff, u_int8_t protocol)
86 {
87 	struct ipv6hdr *ip6h = skb->nh.ipv6h;
88 	__sum16 csum = 0;
89 
90 	switch (skb->ip_summed) {
91 	case CHECKSUM_COMPLETE:
92 		if (hook != NF_IP6_PRE_ROUTING && hook != NF_IP6_LOCAL_IN)
93 			break;
94 		if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
95 				     skb->len - dataoff, protocol,
96 				     csum_sub(skb->csum,
97 					      skb_checksum(skb, 0,
98 							   dataoff, 0)))) {
99 			skb->ip_summed = CHECKSUM_UNNECESSARY;
100 			break;
101 		}
102 		/* fall through */
103 	case CHECKSUM_NONE:
104 		skb->csum = ~csum_unfold(
105 				csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
106 					     skb->len - dataoff,
107 					     protocol,
108 					     csum_sub(0,
109 						      skb_checksum(skb, 0,
110 								   dataoff, 0))));
111 		csum = __skb_checksum_complete(skb);
112 	}
113 	return csum;
114 }
115 
116 EXPORT_SYMBOL(nf_ip6_checksum);
117 
118 static struct nf_afinfo nf_ip6_afinfo = {
119 	.family		= AF_INET6,
120 	.checksum	= nf_ip6_checksum,
121 	.saveroute	= nf_ip6_saveroute,
122 	.reroute	= nf_ip6_reroute,
123 	.route_key_size	= sizeof(struct ip6_rt_info),
124 };
125 
126 int __init ipv6_netfilter_init(void)
127 {
128 	return nf_register_afinfo(&nf_ip6_afinfo);
129 }
130 
131 /* This can be called from inet6_init() on errors, so it cannot
132  * be marked __exit. -DaveM
133  */
134 void ipv6_netfilter_fini(void)
135 {
136 	nf_unregister_afinfo(&nf_ip6_afinfo);
137 }
138