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 net_device *dev = skb_dst(skb)->dev; 28 struct flow_keys flkeys; 29 unsigned int hh_len; 30 struct dst_entry *dst; 31 int strict = (ipv6_addr_type(&iph->daddr) & 32 (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL)); 33 struct flowi6 fl6 = { 34 .flowi6_l3mdev = l3mdev_master_ifindex(dev), 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 if (sk && sk->sk_bound_dev_if) 43 fl6.flowi6_oif = sk->sk_bound_dev_if; 44 else if (strict) 45 fl6.flowi6_oif = dev->ifindex; 46 47 fib6_rules_early_flow_dissect(net, skb, &fl6, &flkeys); 48 dst = ip6_route_output(net, sk, &fl6); 49 err = dst->error; 50 if (err) { 51 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 52 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 53 dst_release(dst); 54 return err; 55 } 56 57 /* Drop old route. */ 58 skb_dst_drop(skb); 59 60 skb_dst_set(skb, dst); 61 62 #ifdef CONFIG_XFRM 63 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 64 xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 65 skb_dst_set(skb, NULL); 66 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 67 if (IS_ERR(dst)) 68 return PTR_ERR(dst); 69 skb_dst_set(skb, dst); 70 } 71 #endif 72 73 /* Change in oif may mean change in hh_len. */ 74 hh_len = skb_dst(skb)->dev->hard_header_len; 75 if (skb_headroom(skb) < hh_len && 76 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 77 0, GFP_ATOMIC)) 78 return -ENOMEM; 79 80 return 0; 81 } 82 EXPORT_SYMBOL(ip6_route_me_harder); 83 84 static int nf_ip6_reroute(struct sk_buff *skb, 85 const struct nf_queue_entry *entry) 86 { 87 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 88 89 if (entry->state.hook == NF_INET_LOCAL_OUT) { 90 const struct ipv6hdr *iph = ipv6_hdr(skb); 91 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 92 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 93 skb->mark != rt_info->mark) 94 return ip6_route_me_harder(entry->state.net, entry->state.sk, skb); 95 } 96 return 0; 97 } 98 99 int __nf_ip6_route(struct net *net, struct dst_entry **dst, 100 struct flowi *fl, bool strict) 101 { 102 static const struct ipv6_pinfo fake_pinfo; 103 static const struct inet_sock fake_sk = { 104 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 105 .sk.sk_bound_dev_if = 1, 106 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 107 }; 108 const void *sk = strict ? &fake_sk : NULL; 109 struct dst_entry *result; 110 int err; 111 112 result = ip6_route_output(net, sk, &fl->u.ip6); 113 err = result->error; 114 if (err) 115 dst_release(result); 116 else 117 *dst = result; 118 return err; 119 } 120 EXPORT_SYMBOL_GPL(__nf_ip6_route); 121 122 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 123 struct nf_bridge_frag_data *data, 124 int (*output)(struct net *, struct sock *sk, 125 const struct nf_bridge_frag_data *data, 126 struct sk_buff *)) 127 { 128 int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size; 129 bool mono_delivery_time = skb->mono_delivery_time; 130 ktime_t tstamp = skb->tstamp; 131 struct ip6_frag_state state; 132 u8 *prevhdr, nexthdr = 0; 133 unsigned int mtu, hlen; 134 int hroom, err = 0; 135 __be32 frag_id; 136 137 err = ip6_find_1stfragopt(skb, &prevhdr); 138 if (err < 0) 139 goto blackhole; 140 hlen = err; 141 nexthdr = *prevhdr; 142 143 mtu = skb->dev->mtu; 144 if (frag_max_size > mtu || 145 frag_max_size < IPV6_MIN_MTU) 146 goto blackhole; 147 148 mtu = frag_max_size; 149 if (mtu < hlen + sizeof(struct frag_hdr) + 8) 150 goto blackhole; 151 mtu -= hlen + sizeof(struct frag_hdr); 152 153 frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, 154 &ipv6_hdr(skb)->saddr); 155 156 if (skb->ip_summed == CHECKSUM_PARTIAL && 157 (err = skb_checksum_help(skb))) 158 goto blackhole; 159 160 hroom = LL_RESERVED_SPACE(skb->dev); 161 if (skb_has_frag_list(skb)) { 162 unsigned int first_len = skb_pagelen(skb); 163 struct ip6_fraglist_iter iter; 164 struct sk_buff *frag2; 165 166 if (first_len - hlen > mtu || 167 skb_headroom(skb) < (hroom + sizeof(struct frag_hdr))) 168 goto blackhole; 169 170 if (skb_cloned(skb)) 171 goto slow_path; 172 173 skb_walk_frags(skb, frag2) { 174 if (frag2->len > mtu || 175 skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr))) 176 goto blackhole; 177 178 /* Partially cloned skb? */ 179 if (skb_shared(frag2)) 180 goto slow_path; 181 } 182 183 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id, 184 &iter); 185 if (err < 0) 186 goto blackhole; 187 188 for (;;) { 189 /* Prepare header of the next frame, 190 * before previous one went down. 191 */ 192 if (iter.frag) 193 ip6_fraglist_prepare(skb, &iter); 194 195 skb_set_delivery_time(skb, tstamp, mono_delivery_time); 196 err = output(net, sk, data, skb); 197 if (err || !iter.frag) 198 break; 199 200 skb = ip6_fraglist_next(&iter); 201 } 202 203 kfree(iter.tmp_hdr); 204 if (!err) 205 return 0; 206 207 kfree_skb_list(iter.frag); 208 return err; 209 } 210 slow_path: 211 /* This is a linearized skbuff, the original geometry is lost for us. 212 * This may also be a clone skbuff, we could preserve the geometry for 213 * the copies but probably not worth the effort. 214 */ 215 ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom, 216 LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id, 217 &state); 218 219 while (state.left > 0) { 220 struct sk_buff *skb2; 221 222 skb2 = ip6_frag_next(skb, &state); 223 if (IS_ERR(skb2)) { 224 err = PTR_ERR(skb2); 225 goto blackhole; 226 } 227 228 skb_set_delivery_time(skb2, tstamp, mono_delivery_time); 229 err = output(net, sk, data, skb2); 230 if (err) 231 goto blackhole; 232 } 233 consume_skb(skb); 234 return err; 235 236 blackhole: 237 kfree_skb(skb); 238 return 0; 239 } 240 EXPORT_SYMBOL_GPL(br_ip6_fragment); 241 242 static const struct nf_ipv6_ops ipv6ops = { 243 #if IS_MODULE(CONFIG_IPV6) 244 .chk_addr = ipv6_chk_addr, 245 .route_me_harder = ip6_route_me_harder, 246 .dev_get_saddr = ipv6_dev_get_saddr, 247 .route = __nf_ip6_route, 248 #if IS_ENABLED(CONFIG_SYN_COOKIES) 249 .cookie_init_sequence = __cookie_v6_init_sequence, 250 .cookie_v6_check = __cookie_v6_check, 251 #endif 252 #endif 253 .route_input = ip6_route_input, 254 .fragment = ip6_fragment, 255 .reroute = nf_ip6_reroute, 256 #if IS_MODULE(CONFIG_IPV6) 257 .br_fragment = br_ip6_fragment, 258 #endif 259 }; 260 261 int __init ipv6_netfilter_init(void) 262 { 263 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 264 return 0; 265 } 266 267 /* This can be called from inet6_init() on errors, so it cannot 268 * be marked __exit. -DaveM 269 */ 270 void ipv6_netfilter_fini(void) 271 { 272 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 273 } 274