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 struct sock *sk = sk_to_full_sk(skb->sk); 25 unsigned int hh_len; 26 struct dst_entry *dst; 27 struct flowi6 fl6 = { 28 .flowi6_oif = sk ? sk->sk_bound_dev_if : 0, 29 .flowi6_mark = skb->mark, 30 .flowi6_uid = sock_net_uid(net, sk), 31 .daddr = iph->daddr, 32 .saddr = iph->saddr, 33 }; 34 int err; 35 36 dst = ip6_route_output(net, sk, &fl6); 37 err = dst->error; 38 if (err) { 39 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 40 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 41 dst_release(dst); 42 return err; 43 } 44 45 /* Drop old route. */ 46 skb_dst_drop(skb); 47 48 skb_dst_set(skb, dst); 49 50 #ifdef CONFIG_XFRM 51 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 52 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 53 skb_dst_set(skb, NULL); 54 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 55 if (IS_ERR(dst)) 56 return PTR_ERR(dst); 57 skb_dst_set(skb, dst); 58 } 59 #endif 60 61 /* Change in oif may mean change in hh_len. */ 62 hh_len = skb_dst(skb)->dev->hard_header_len; 63 if (skb_headroom(skb) < hh_len && 64 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 65 0, GFP_ATOMIC)) 66 return -ENOMEM; 67 68 return 0; 69 } 70 EXPORT_SYMBOL(ip6_route_me_harder); 71 72 static int nf_ip6_reroute(struct sk_buff *skb, 73 const struct nf_queue_entry *entry) 74 { 75 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 76 77 if (entry->state.hook == NF_INET_LOCAL_OUT) { 78 const struct ipv6hdr *iph = ipv6_hdr(skb); 79 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 80 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 81 skb->mark != rt_info->mark) 82 return ip6_route_me_harder(entry->state.net, skb); 83 } 84 return 0; 85 } 86 87 static int nf_ip6_route(struct net *net, struct dst_entry **dst, 88 struct flowi *fl, bool strict) 89 { 90 static const struct ipv6_pinfo fake_pinfo; 91 static const struct inet_sock fake_sk = { 92 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 93 .sk.sk_bound_dev_if = 1, 94 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 95 }; 96 const void *sk = strict ? &fake_sk : NULL; 97 struct dst_entry *result; 98 int err; 99 100 result = ip6_route_output(net, sk, &fl->u.ip6); 101 err = result->error; 102 if (err) 103 dst_release(result); 104 else 105 *dst = result; 106 return err; 107 } 108 109 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook, 110 unsigned int dataoff, u_int8_t protocol) 111 { 112 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 113 __sum16 csum = 0; 114 115 switch (skb->ip_summed) { 116 case CHECKSUM_COMPLETE: 117 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN) 118 break; 119 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 120 skb->len - dataoff, protocol, 121 csum_sub(skb->csum, 122 skb_checksum(skb, 0, 123 dataoff, 0)))) { 124 skb->ip_summed = CHECKSUM_UNNECESSARY; 125 break; 126 } 127 /* fall through */ 128 case CHECKSUM_NONE: 129 skb->csum = ~csum_unfold( 130 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, 131 skb->len - dataoff, 132 protocol, 133 csum_sub(0, 134 skb_checksum(skb, 0, 135 dataoff, 0)))); 136 csum = __skb_checksum_complete(skb); 137 } 138 return csum; 139 } 140 EXPORT_SYMBOL(nf_ip6_checksum); 141 142 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook, 143 unsigned int dataoff, unsigned int len, 144 u_int8_t protocol) 145 { 146 const struct ipv6hdr *ip6h = ipv6_hdr(skb); 147 __wsum hsum; 148 __sum16 csum = 0; 149 150 switch (skb->ip_summed) { 151 case CHECKSUM_COMPLETE: 152 if (len == skb->len - dataoff) 153 return nf_ip6_checksum(skb, hook, dataoff, protocol); 154 /* fall through */ 155 case CHECKSUM_NONE: 156 hsum = skb_checksum(skb, 0, dataoff, 0); 157 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr, 158 &ip6h->daddr, 159 skb->len - dataoff, 160 protocol, 161 csum_sub(0, hsum))); 162 skb->ip_summed = CHECKSUM_NONE; 163 return __skb_checksum_complete_head(skb, dataoff + len); 164 } 165 return csum; 166 }; 167 168 static const struct nf_ipv6_ops ipv6ops = { 169 .chk_addr = ipv6_chk_addr, 170 .route_input = ip6_route_input, 171 .fragment = ip6_fragment, 172 .checksum = nf_ip6_checksum, 173 .checksum_partial = nf_ip6_checksum_partial, 174 .route = nf_ip6_route, 175 .reroute = nf_ip6_reroute, 176 }; 177 178 int __init ipv6_netfilter_init(void) 179 { 180 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 181 return 0; 182 } 183 184 /* This can be called from inet6_init() on errors, so it cannot 185 * be marked __exit. -DaveM 186 */ 187 void ipv6_netfilter_fini(void) 188 { 189 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 190 } 191