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 .flowi6_uid = sock_net_uid(net, skb->sk), 30 .daddr = iph->daddr, 31 .saddr = iph->saddr, 32 }; 33 int err; 34 35 dst = ip6_route_output(net, skb->sk, &fl6); 36 err = dst->error; 37 if (err) { 38 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 39 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 40 dst_release(dst); 41 return err; 42 } 43 44 /* Drop old route. */ 45 skb_dst_drop(skb); 46 47 skb_dst_set(skb, dst); 48 49 #ifdef CONFIG_XFRM 50 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 51 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 52 skb_dst_set(skb, NULL); 53 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0); 54 if (IS_ERR(dst)) 55 return PTR_ERR(dst); 56 skb_dst_set(skb, dst); 57 } 58 #endif 59 60 /* Change in oif may mean change in hh_len. */ 61 hh_len = skb_dst(skb)->dev->hard_header_len; 62 if (skb_headroom(skb) < hh_len && 63 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 64 0, GFP_ATOMIC)) 65 return -ENOMEM; 66 67 return 0; 68 } 69 EXPORT_SYMBOL(ip6_route_me_harder); 70 71 /* 72 * Extra routing may needed on local out, as the QUEUE target never 73 * returns control to the table. 74 */ 75 76 struct ip6_rt_info { 77 struct in6_addr daddr; 78 struct in6_addr saddr; 79 u_int32_t mark; 80 }; 81 82 static void nf_ip6_saveroute(const struct sk_buff *skb, 83 struct nf_queue_entry *entry) 84 { 85 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 86 87 if (entry->state.hook == NF_INET_LOCAL_OUT) { 88 const struct ipv6hdr *iph = ipv6_hdr(skb); 89 90 rt_info->daddr = iph->daddr; 91 rt_info->saddr = iph->saddr; 92 rt_info->mark = skb->mark; 93 } 94 } 95 96 static int nf_ip6_reroute(struct net *net, struct sk_buff *skb, 97 const struct nf_queue_entry *entry) 98 { 99 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 100 101 if (entry->state.hook == NF_INET_LOCAL_OUT) { 102 const struct ipv6hdr *iph = ipv6_hdr(skb); 103 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 104 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 105 skb->mark != rt_info->mark) 106 return ip6_route_me_harder(net, skb); 107 } 108 return 0; 109 } 110 111 static int nf_ip6_route(struct net *net, struct dst_entry **dst, 112 struct flowi *fl, bool strict) 113 { 114 static const struct ipv6_pinfo fake_pinfo; 115 static const struct inet_sock fake_sk = { 116 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 117 .sk.sk_bound_dev_if = 1, 118 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 119 }; 120 const void *sk = strict ? &fake_sk : NULL; 121 struct dst_entry *result; 122 int err; 123 124 result = ip6_route_output(net, sk, &fl->u.ip6); 125 err = result->error; 126 if (err) 127 dst_release(result); 128 else 129 *dst = result; 130 return err; 131 } 132 133 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook, 134 unsigned int dataoff, u_int8_t protocol) 135 { 136 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 137 __sum16 csum = 0; 138 139 switch (skb->ip_summed) { 140 case CHECKSUM_COMPLETE: 141 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) 142 break; 143 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 144 skb->len - dataoff, protocol, 145 csum_sub(skb->csum, 146 skb_checksum(skb, 0, 147 dataoff, 0)))) { 148 skb->ip_summed = CHECKSUM_UNNECESSARY; 149 break; 150 } 151 /* fall through */ 152 case CHECKSUM_NONE: 153 skb->csum = ~csum_unfold( 154 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 155 skb->len - dataoff, 156 protocol, 157 csum_sub(0, 158 skb_checksum(skb, 0, 159 dataoff, 0)))); 160 csum = __skb_checksum_complete(skb); 161 } 162 return csum; 163 } 164 EXPORT_SYMBOL(nf_ip6_checksum); 165 166 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook, 167 unsigned int dataoff, unsigned int len, 168 u_int8_t protocol) 169 { 170 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 171 __wsum hsum; 172 __sum16 csum = 0; 173 174 switch (skb->ip_summed) { 175 case CHECKSUM_COMPLETE: 176 if (len == skb->len - dataoff) 177 return nf_ip6_checksum(skb, hook, dataoff, protocol); 178 /* fall through */ 179 case CHECKSUM_NONE: 180 hsum = skb_checksum(skb, 0, dataoff, 0); 181 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr, 182 &ip6h->daddr, 183 skb->len - dataoff, 184 protocol, 185 csum_sub(0, hsum))); 186 skb->ip_summed = CHECKSUM_NONE; 187 return __skb_checksum_complete_head(skb, dataoff + len); 188 } 189 return csum; 190 }; 191 192 static const struct nf_ipv6_ops ipv6ops = { 193 .chk_addr = ipv6_chk_addr, 194 .route_input = ip6_route_input, 195 .fragment = ip6_fragment 196 }; 197 198 static const struct nf_afinfo nf_ip6_afinfo = { 199 .family = AF_INET6, 200 .checksum = nf_ip6_checksum, 201 .checksum_partial = nf_ip6_checksum_partial, 202 .route = nf_ip6_route, 203 .saveroute = nf_ip6_saveroute, 204 .reroute = nf_ip6_reroute, 205 .route_key_size = sizeof(struct ip6_rt_info), 206 }; 207 208 int __init ipv6_netfilter_init(void) 209 { 210 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 211 return nf_register_afinfo(&nf_ip6_afinfo); 212 } 213 214 /* This can be called from inet6_init() on errors, so it cannot 215 * be marked __exit. -DaveM 216 */ 217 void ipv6_netfilter_fini(void) 218 { 219 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 220 nf_unregister_afinfo(&nf_ip6_afinfo); 221 } 222