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/dst.h> 14 #include <net/ipv6.h> 15 #include <net/ip6_route.h> 16 #include <net/xfrm.h> 17 #include <net/ip6_checksum.h> 18 #include <net/netfilter/nf_queue.h> 19 20 int ip6_route_me_harder(struct sk_buff *skb) 21 { 22 struct net *net = dev_net(skb_dst(skb)->dev); 23 const struct ipv6hdr *iph = ipv6_hdr(skb); 24 unsigned int hh_len; 25 struct dst_entry *dst; 26 struct flowi6 fl6 = { 27 .flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0, 28 .flowi6_mark = skb->mark, 29 .daddr = iph->daddr, 30 .saddr = iph->saddr, 31 }; 32 33 dst = ip6_route_output(net, skb->sk, &fl6); 34 if (dst->error) { 35 IP6_INC_STATS(net, 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 dst->error; 39 } 40 41 /* Drop old route. */ 42 skb_dst_drop(skb); 43 44 skb_dst_set(skb, dst); 45 46 #ifdef CONFIG_XFRM 47 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 48 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 49 skb_dst_set(skb, NULL); 50 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0); 51 if (IS_ERR(dst)) 52 return PTR_ERR(dst); 53 skb_dst_set(skb, dst); 54 } 55 #endif 56 57 /* Change in oif may mean change in hh_len. */ 58 hh_len = skb_dst(skb)->dev->hard_header_len; 59 if (skb_headroom(skb) < hh_len && 60 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 61 0, GFP_ATOMIC)) 62 return -ENOMEM; 63 64 return 0; 65 } 66 EXPORT_SYMBOL(ip6_route_me_harder); 67 68 /* 69 * Extra routing may needed on local out, as the QUEUE target never 70 * returns control to the table. 71 */ 72 73 struct ip6_rt_info { 74 struct in6_addr daddr; 75 struct in6_addr saddr; 76 u_int32_t mark; 77 }; 78 79 static void nf_ip6_saveroute(const struct sk_buff *skb, 80 struct nf_queue_entry *entry) 81 { 82 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 83 84 if (entry->hook == NF_INET_LOCAL_OUT) { 85 const struct ipv6hdr *iph = ipv6_hdr(skb); 86 87 rt_info->daddr = iph->daddr; 88 rt_info->saddr = iph->saddr; 89 rt_info->mark = skb->mark; 90 } 91 } 92 93 static int nf_ip6_reroute(struct sk_buff *skb, 94 const struct nf_queue_entry *entry) 95 { 96 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 97 98 if (entry->hook == NF_INET_LOCAL_OUT) { 99 const struct ipv6hdr *iph = ipv6_hdr(skb); 100 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 101 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 102 skb->mark != rt_info->mark) 103 return ip6_route_me_harder(skb); 104 } 105 return 0; 106 } 107 108 static int nf_ip6_route(struct net *net, struct dst_entry **dst, 109 struct flowi *fl, bool strict) 110 { 111 static const struct ipv6_pinfo fake_pinfo; 112 static const struct inet_sock fake_sk = { 113 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 114 .sk.sk_bound_dev_if = 1, 115 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 116 }; 117 const void *sk = strict ? &fake_sk : NULL; 118 struct dst_entry *result; 119 int err; 120 121 result = ip6_route_output(net, sk, &fl->u.ip6); 122 err = result->error; 123 if (err) 124 dst_release(result); 125 else 126 *dst = result; 127 return err; 128 } 129 130 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook, 131 unsigned int dataoff, u_int8_t protocol) 132 { 133 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 134 __sum16 csum = 0; 135 136 switch (skb->ip_summed) { 137 case CHECKSUM_COMPLETE: 138 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) 139 break; 140 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 141 skb->len - dataoff, protocol, 142 csum_sub(skb->csum, 143 skb_checksum(skb, 0, 144 dataoff, 0)))) { 145 skb->ip_summed = CHECKSUM_UNNECESSARY; 146 break; 147 } 148 /* fall through */ 149 case CHECKSUM_NONE: 150 skb->csum = ~csum_unfold( 151 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 152 skb->len - dataoff, 153 protocol, 154 csum_sub(0, 155 skb_checksum(skb, 0, 156 dataoff, 0)))); 157 csum = __skb_checksum_complete(skb); 158 } 159 return csum; 160 } 161 EXPORT_SYMBOL(nf_ip6_checksum); 162 163 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook, 164 unsigned int dataoff, unsigned int len, 165 u_int8_t protocol) 166 { 167 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 168 __wsum hsum; 169 __sum16 csum = 0; 170 171 switch (skb->ip_summed) { 172 case CHECKSUM_COMPLETE: 173 if (len == skb->len - dataoff) 174 return nf_ip6_checksum(skb, hook, dataoff, protocol); 175 /* fall through */ 176 case CHECKSUM_NONE: 177 hsum = skb_checksum(skb, 0, dataoff, 0); 178 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr, 179 &ip6h->daddr, 180 skb->len - dataoff, 181 protocol, 182 csum_sub(0, hsum))); 183 skb->ip_summed = CHECKSUM_NONE; 184 return __skb_checksum_complete_head(skb, dataoff + len); 185 } 186 return csum; 187 }; 188 189 static const struct nf_afinfo nf_ip6_afinfo = { 190 .family = AF_INET6, 191 .checksum = nf_ip6_checksum, 192 .checksum_partial = nf_ip6_checksum_partial, 193 .route = nf_ip6_route, 194 .saveroute = nf_ip6_saveroute, 195 .reroute = nf_ip6_reroute, 196 .route_key_size = sizeof(struct ip6_rt_info), 197 }; 198 199 int __init ipv6_netfilter_init(void) 200 { 201 return nf_register_afinfo(&nf_ip6_afinfo); 202 } 203 204 /* This can be called from inet6_init() on errors, so it cannot 205 * be marked __exit. -DaveM 206 */ 207 void ipv6_netfilter_fini(void) 208 { 209 nf_unregister_afinfo(&nf_ip6_afinfo); 210 } 211