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/netfilter/nf_queue.h> 19 #include <net/netfilter/nf_conntrack_bridge.h> 20 #include <net/netfilter/ipv6/nf_defrag_ipv6.h> 21 #include "../bridge/br_private.h" 22 23 int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff *skb) 24 { 25 const struct ipv6hdr *iph = ipv6_hdr(skb); 26 struct sock *sk = sk_to_full_sk(sk_partial); 27 struct flow_keys flkeys; 28 unsigned int hh_len; 29 struct dst_entry *dst; 30 int strict = (ipv6_addr_type(&iph->daddr) & 31 (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL)); 32 struct flowi6 fl6 = { 33 .flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if : 34 strict ? skb_dst(skb)->dev->ifindex : 0, 35 .flowi6_mark = skb->mark, 36 .flowi6_uid = sock_net_uid(net, sk), 37 .daddr = iph->daddr, 38 .saddr = iph->saddr, 39 }; 40 int err; 41 42 fib6_rules_early_flow_dissect(net, skb, &fl6, &flkeys); 43 dst = ip6_route_output(net, sk, &fl6); 44 err = dst->error; 45 if (err) { 46 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 47 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 48 dst_release(dst); 49 return err; 50 } 51 52 /* Drop old route. */ 53 skb_dst_drop(skb); 54 55 skb_dst_set(skb, dst); 56 57 #ifdef CONFIG_XFRM 58 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 59 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 60 skb_dst_set(skb, NULL); 61 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 62 if (IS_ERR(dst)) 63 return PTR_ERR(dst); 64 skb_dst_set(skb, dst); 65 } 66 #endif 67 68 /* Change in oif may mean change in hh_len. */ 69 hh_len = skb_dst(skb)->dev->hard_header_len; 70 if (skb_headroom(skb) < hh_len && 71 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 72 0, GFP_ATOMIC)) 73 return -ENOMEM; 74 75 return 0; 76 } 77 EXPORT_SYMBOL(ip6_route_me_harder); 78 79 static int nf_ip6_reroute(struct sk_buff *skb, 80 const struct nf_queue_entry *entry) 81 { 82 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 83 84 if (entry->state.hook == NF_INET_LOCAL_OUT) { 85 const struct ipv6hdr *iph = ipv6_hdr(skb); 86 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 87 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 88 skb->mark != rt_info->mark) 89 return ip6_route_me_harder(entry->state.net, entry->state.sk, skb); 90 } 91 return 0; 92 } 93 94 int __nf_ip6_route(struct net *net, struct dst_entry **dst, 95 struct flowi *fl, bool strict) 96 { 97 static const struct ipv6_pinfo fake_pinfo; 98 static const struct inet_sock fake_sk = { 99 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 100 .sk.sk_bound_dev_if = 1, 101 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 102 }; 103 const void *sk = strict ? &fake_sk : NULL; 104 struct dst_entry *result; 105 int err; 106 107 result = ip6_route_output(net, sk, &fl->u.ip6); 108 err = result->error; 109 if (err) 110 dst_release(result); 111 else 112 *dst = result; 113 return err; 114 } 115 EXPORT_SYMBOL_GPL(__nf_ip6_route); 116 117 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 118 struct nf_bridge_frag_data *data, 119 int (*output)(struct net *, struct sock *sk, 120 const struct nf_bridge_frag_data *data, 121 struct sk_buff *)) 122 { 123 int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size; 124 bool mono_delivery_time = skb->mono_delivery_time; 125 ktime_t tstamp = skb->tstamp; 126 struct ip6_frag_state state; 127 u8 *prevhdr, nexthdr = 0; 128 unsigned int mtu, hlen; 129 int hroom, err = 0; 130 __be32 frag_id; 131 132 err = ip6_find_1stfragopt(skb, &prevhdr); 133 if (err < 0) 134 goto blackhole; 135 hlen = err; 136 nexthdr = *prevhdr; 137 138 mtu = skb->dev->mtu; 139 if (frag_max_size > mtu || 140 frag_max_size < IPV6_MIN_MTU) 141 goto blackhole; 142 143 mtu = frag_max_size; 144 if (mtu < hlen + sizeof(struct frag_hdr) + 8) 145 goto blackhole; 146 mtu -= hlen + sizeof(struct frag_hdr); 147 148 frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, 149 &ipv6_hdr(skb)->saddr); 150 151 if (skb->ip_summed == CHECKSUM_PARTIAL && 152 (err = skb_checksum_help(skb))) 153 goto blackhole; 154 155 hroom = LL_RESERVED_SPACE(skb->dev); 156 if (skb_has_frag_list(skb)) { 157 unsigned int first_len = skb_pagelen(skb); 158 struct ip6_fraglist_iter iter; 159 struct sk_buff *frag2; 160 161 if (first_len - hlen > mtu || 162 skb_headroom(skb) < (hroom + sizeof(struct frag_hdr))) 163 goto blackhole; 164 165 if (skb_cloned(skb)) 166 goto slow_path; 167 168 skb_walk_frags(skb, frag2) { 169 if (frag2->len > mtu || 170 skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr))) 171 goto blackhole; 172 173 /* Partially cloned skb? */ 174 if (skb_shared(frag2)) 175 goto slow_path; 176 } 177 178 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id, 179 &iter); 180 if (err < 0) 181 goto blackhole; 182 183 for (;;) { 184 /* Prepare header of the next frame, 185 * before previous one went down. 186 */ 187 if (iter.frag) 188 ip6_fraglist_prepare(skb, &iter); 189 190 skb_set_delivery_time(skb, tstamp, mono_delivery_time); 191 err = output(net, sk, data, skb); 192 if (err || !iter.frag) 193 break; 194 195 skb = ip6_fraglist_next(&iter); 196 } 197 198 kfree(iter.tmp_hdr); 199 if (!err) 200 return 0; 201 202 kfree_skb_list(iter.frag); 203 return err; 204 } 205 slow_path: 206 /* This is a linearized skbuff, the original geometry is lost for us. 207 * This may also be a clone skbuff, we could preserve the geometry for 208 * the copies but probably not worth the effort. 209 */ 210 ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom, 211 LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id, 212 &state); 213 214 while (state.left > 0) { 215 struct sk_buff *skb2; 216 217 skb2 = ip6_frag_next(skb, &state); 218 if (IS_ERR(skb2)) { 219 err = PTR_ERR(skb2); 220 goto blackhole; 221 } 222 223 skb_set_delivery_time(skb2, tstamp, mono_delivery_time); 224 err = output(net, sk, data, skb2); 225 if (err) 226 goto blackhole; 227 } 228 consume_skb(skb); 229 return err; 230 231 blackhole: 232 kfree_skb(skb); 233 return 0; 234 } 235 EXPORT_SYMBOL_GPL(br_ip6_fragment); 236 237 static const struct nf_ipv6_ops ipv6ops = { 238 #if IS_MODULE(CONFIG_IPV6) 239 .chk_addr = ipv6_chk_addr, 240 .route_me_harder = ip6_route_me_harder, 241 .dev_get_saddr = ipv6_dev_get_saddr, 242 .route = __nf_ip6_route, 243 #if IS_ENABLED(CONFIG_SYN_COOKIES) 244 .cookie_init_sequence = __cookie_v6_init_sequence, 245 .cookie_v6_check = __cookie_v6_check, 246 #endif 247 #endif 248 .route_input = ip6_route_input, 249 .fragment = ip6_fragment, 250 .reroute = nf_ip6_reroute, 251 #if IS_MODULE(CONFIG_IPV6) 252 .br_fragment = br_ip6_fragment, 253 #endif 254 }; 255 256 int __init ipv6_netfilter_init(void) 257 { 258 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 259 return 0; 260 } 261 262 /* This can be called from inet6_init() on errors, so it cannot 263 * be marked __exit. -DaveM 264 */ 265 void ipv6_netfilter_fini(void) 266 { 267 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 268 } 269