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/ip6_checksum.h> 19 #include <net/netfilter/nf_queue.h> 20 21 int ip6_route_me_harder(struct sk_buff *skb) 22 { 23 struct net *net = dev_net(skb_dst(skb)->dev); 24 const struct ipv6hdr *iph = ipv6_hdr(skb); 25 unsigned int hh_len; 26 struct dst_entry *dst; 27 struct flowi6 fl6 = { 28 .flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0, 29 .flowi6_mark = skb->mark, 30 .daddr = iph->daddr, 31 .saddr = iph->saddr, 32 }; 33 34 dst = ip6_route_output(net, skb->sk, &fl6); 35 if (dst->error) { 36 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 37 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n"); 38 dst_release(dst); 39 return dst->error; 40 } 41 42 /* Drop old route. */ 43 skb_dst_drop(skb); 44 45 skb_dst_set(skb, dst); 46 47 #ifdef CONFIG_XFRM 48 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 49 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 50 skb_dst_set(skb, NULL); 51 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0); 52 if (IS_ERR(dst)) 53 return PTR_ERR(dst); 54 skb_dst_set(skb, dst); 55 } 56 #endif 57 58 /* Change in oif may mean change in hh_len. */ 59 hh_len = skb_dst(skb)->dev->hard_header_len; 60 if (skb_headroom(skb) < hh_len && 61 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 62 0, GFP_ATOMIC)) 63 return -ENOMEM; 64 65 return 0; 66 } 67 EXPORT_SYMBOL(ip6_route_me_harder); 68 69 /* 70 * Extra routing may needed on local out, as the QUEUE target never 71 * returns control to the table. 72 */ 73 74 struct ip6_rt_info { 75 struct in6_addr daddr; 76 struct in6_addr saddr; 77 u_int32_t mark; 78 }; 79 80 static void nf_ip6_saveroute(const struct sk_buff *skb, 81 struct nf_queue_entry *entry) 82 { 83 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 84 85 if (entry->hook == NF_INET_LOCAL_OUT) { 86 const struct ipv6hdr *iph = ipv6_hdr(skb); 87 88 rt_info->daddr = iph->daddr; 89 rt_info->saddr = iph->saddr; 90 rt_info->mark = skb->mark; 91 } 92 } 93 94 static int nf_ip6_reroute(struct sk_buff *skb, 95 const struct nf_queue_entry *entry) 96 { 97 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 98 99 if (entry->hook == NF_INET_LOCAL_OUT) { 100 const struct ipv6hdr *iph = ipv6_hdr(skb); 101 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 102 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 103 skb->mark != rt_info->mark) 104 return ip6_route_me_harder(skb); 105 } 106 return 0; 107 } 108 109 static int nf_ip6_route(struct net *net, struct dst_entry **dst, 110 struct flowi *fl, bool strict) 111 { 112 static const struct ipv6_pinfo fake_pinfo; 113 static const struct inet_sock fake_sk = { 114 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 115 .sk.sk_bound_dev_if = 1, 116 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 117 }; 118 const void *sk = strict ? &fake_sk : NULL; 119 struct dst_entry *result; 120 int err; 121 122 result = ip6_route_output(net, sk, &fl->u.ip6); 123 err = result->error; 124 if (err) 125 dst_release(result); 126 else 127 *dst = result; 128 return err; 129 } 130 131 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook, 132 unsigned int dataoff, u_int8_t protocol) 133 { 134 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 135 __sum16 csum = 0; 136 137 switch (skb->ip_summed) { 138 case CHECKSUM_COMPLETE: 139 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) 140 break; 141 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 142 skb->len - dataoff, protocol, 143 csum_sub(skb->csum, 144 skb_checksum(skb, 0, 145 dataoff, 0)))) { 146 skb->ip_summed = CHECKSUM_UNNECESSARY; 147 break; 148 } 149 /* fall through */ 150 case CHECKSUM_NONE: 151 skb->csum = ~csum_unfold( 152 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 153 skb->len - dataoff, 154 protocol, 155 csum_sub(0, 156 skb_checksum(skb, 0, 157 dataoff, 0)))); 158 csum = __skb_checksum_complete(skb); 159 } 160 return csum; 161 } 162 EXPORT_SYMBOL(nf_ip6_checksum); 163 164 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook, 165 unsigned int dataoff, unsigned int len, 166 u_int8_t protocol) 167 { 168 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 169 __wsum hsum; 170 __sum16 csum = 0; 171 172 switch (skb->ip_summed) { 173 case CHECKSUM_COMPLETE: 174 if (len == skb->len - dataoff) 175 return nf_ip6_checksum(skb, hook, dataoff, protocol); 176 /* fall through */ 177 case CHECKSUM_NONE: 178 hsum = skb_checksum(skb, 0, dataoff, 0); 179 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr, 180 &ip6h->daddr, 181 skb->len - dataoff, 182 protocol, 183 csum_sub(0, hsum))); 184 skb->ip_summed = CHECKSUM_NONE; 185 return __skb_checksum_complete_head(skb, dataoff + len); 186 } 187 return csum; 188 }; 189 190 static const struct nf_ipv6_ops ipv6ops = { 191 .chk_addr = ipv6_chk_addr, 192 }; 193 194 static const struct nf_afinfo nf_ip6_afinfo = { 195 .family = AF_INET6, 196 .checksum = nf_ip6_checksum, 197 .checksum_partial = nf_ip6_checksum_partial, 198 .route = nf_ip6_route, 199 .saveroute = nf_ip6_saveroute, 200 .reroute = nf_ip6_reroute, 201 .route_key_size = sizeof(struct ip6_rt_info), 202 }; 203 204 int __init ipv6_netfilter_init(void) 205 { 206 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 207 return nf_register_afinfo(&nf_ip6_afinfo); 208 } 209 210 /* This can be called from inet6_init() on errors, so it cannot 211 * be marked __exit. -DaveM 212 */ 213 void ipv6_netfilter_fini(void) 214 { 215 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 216 nf_unregister_afinfo(&nf_ip6_afinfo); 217 } 218