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 net *net, struct sk_buff *skb) 22 { 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 int err; 33 34 dst = ip6_route_output(net, skb->sk, &fl6); 35 err = dst->error; 36 if (err) { 37 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 38 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 39 dst_release(dst); 40 return err; 41 } 42 43 /* Drop old route. */ 44 skb_dst_drop(skb); 45 46 skb_dst_set(skb, dst); 47 48 #ifdef CONFIG_XFRM 49 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 50 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 51 skb_dst_set(skb, NULL); 52 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0); 53 if (IS_ERR(dst)) 54 return PTR_ERR(dst); 55 skb_dst_set(skb, dst); 56 } 57 #endif 58 59 /* Change in oif may mean change in hh_len. */ 60 hh_len = skb_dst(skb)->dev->hard_header_len; 61 if (skb_headroom(skb) < hh_len && 62 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 63 0, GFP_ATOMIC)) 64 return -ENOMEM; 65 66 return 0; 67 } 68 EXPORT_SYMBOL(ip6_route_me_harder); 69 70 /* 71 * Extra routing may needed on local out, as the QUEUE target never 72 * returns control to the table. 73 */ 74 75 struct ip6_rt_info { 76 struct in6_addr daddr; 77 struct in6_addr saddr; 78 u_int32_t mark; 79 }; 80 81 static void nf_ip6_saveroute(const struct sk_buff *skb, 82 struct nf_queue_entry *entry) 83 { 84 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 85 86 if (entry->state.hook == NF_INET_LOCAL_OUT) { 87 const struct ipv6hdr *iph = ipv6_hdr(skb); 88 89 rt_info->daddr = iph->daddr; 90 rt_info->saddr = iph->saddr; 91 rt_info->mark = skb->mark; 92 } 93 } 94 95 static int nf_ip6_reroute(struct net *net, struct sk_buff *skb, 96 const struct nf_queue_entry *entry) 97 { 98 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 99 100 if (entry->state.hook == NF_INET_LOCAL_OUT) { 101 const struct ipv6hdr *iph = ipv6_hdr(skb); 102 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 103 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 104 skb->mark != rt_info->mark) 105 return ip6_route_me_harder(net, skb); 106 } 107 return 0; 108 } 109 110 static int nf_ip6_route(struct net *net, struct dst_entry **dst, 111 struct flowi *fl, bool strict) 112 { 113 static const struct ipv6_pinfo fake_pinfo; 114 static const struct inet_sock fake_sk = { 115 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 116 .sk.sk_bound_dev_if = 1, 117 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 118 }; 119 const void *sk = strict ? &fake_sk : NULL; 120 struct dst_entry *result; 121 int err; 122 123 result = ip6_route_output(net, sk, &fl->u.ip6); 124 err = result->error; 125 if (err) 126 dst_release(result); 127 else 128 *dst = result; 129 return err; 130 } 131 132 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook, 133 unsigned int dataoff, u_int8_t protocol) 134 { 135 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 136 __sum16 csum = 0; 137 138 switch (skb->ip_summed) { 139 case CHECKSUM_COMPLETE: 140 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) 141 break; 142 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 143 skb->len - dataoff, protocol, 144 csum_sub(skb->csum, 145 skb_checksum(skb, 0, 146 dataoff, 0)))) { 147 skb->ip_summed = CHECKSUM_UNNECESSARY; 148 break; 149 } 150 /* fall through */ 151 case CHECKSUM_NONE: 152 skb->csum = ~csum_unfold( 153 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 154 skb->len - dataoff, 155 protocol, 156 csum_sub(0, 157 skb_checksum(skb, 0, 158 dataoff, 0)))); 159 csum = __skb_checksum_complete(skb); 160 } 161 return csum; 162 } 163 EXPORT_SYMBOL(nf_ip6_checksum); 164 165 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook, 166 unsigned int dataoff, unsigned int len, 167 u_int8_t protocol) 168 { 169 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 170 __wsum hsum; 171 __sum16 csum = 0; 172 173 switch (skb->ip_summed) { 174 case CHECKSUM_COMPLETE: 175 if (len == skb->len - dataoff) 176 return nf_ip6_checksum(skb, hook, dataoff, protocol); 177 /* fall through */ 178 case CHECKSUM_NONE: 179 hsum = skb_checksum(skb, 0, dataoff, 0); 180 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr, 181 &ip6h->daddr, 182 skb->len - dataoff, 183 protocol, 184 csum_sub(0, hsum))); 185 skb->ip_summed = CHECKSUM_NONE; 186 return __skb_checksum_complete_head(skb, dataoff + len); 187 } 188 return csum; 189 }; 190 191 static const struct nf_ipv6_ops ipv6ops = { 192 .chk_addr = ipv6_chk_addr, 193 .route_input = ip6_route_input, 194 .fragment = ip6_fragment 195 }; 196 197 static const struct nf_afinfo nf_ip6_afinfo = { 198 .family = AF_INET6, 199 .checksum = nf_ip6_checksum, 200 .checksum_partial = nf_ip6_checksum_partial, 201 .route = nf_ip6_route, 202 .saveroute = nf_ip6_saveroute, 203 .reroute = nf_ip6_reroute, 204 .route_key_size = sizeof(struct ip6_rt_info), 205 }; 206 207 int __init ipv6_netfilter_init(void) 208 { 209 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 210 return nf_register_afinfo(&nf_ip6_afinfo); 211 } 212 213 /* This can be called from inet6_init() on errors, so it cannot 214 * be marked __exit. -DaveM 215 */ 216 void ipv6_netfilter_fini(void) 217 { 218 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 219 nf_unregister_afinfo(&nf_ip6_afinfo); 220 } 221