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 .flowlabel = ip6_flowinfo(iph), 40 }; 41 int err; 42 43 if (sk && sk->sk_bound_dev_if) 44 fl6.flowi6_oif = sk->sk_bound_dev_if; 45 else if (strict) 46 fl6.flowi6_oif = dev->ifindex; 47 48 fib6_rules_early_flow_dissect(net, skb, &fl6, &flkeys); 49 dst = ip6_route_output(net, sk, &fl6); 50 err = dst->error; 51 if (err) { 52 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 53 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 54 dst_release(dst); 55 return err; 56 } 57 58 /* Drop old route. */ 59 skb_dst_drop(skb); 60 61 skb_dst_set(skb, dst); 62 63 #ifdef CONFIG_XFRM 64 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 65 xfrm_decode_session(net, skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 66 skb_dst_set(skb, NULL); 67 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 68 if (IS_ERR(dst)) 69 return PTR_ERR(dst); 70 skb_dst_set(skb, dst); 71 } 72 #endif 73 74 /* Change in oif may mean change in hh_len. */ 75 hh_len = skb_dst(skb)->dev->hard_header_len; 76 if (skb_headroom(skb) < hh_len && 77 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 78 0, GFP_ATOMIC)) 79 return -ENOMEM; 80 81 return 0; 82 } 83 EXPORT_SYMBOL(ip6_route_me_harder); 84 85 static int nf_ip6_reroute(struct sk_buff *skb, 86 const struct nf_queue_entry *entry) 87 { 88 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 89 90 if (entry->state.hook == NF_INET_LOCAL_OUT) { 91 const struct ipv6hdr *iph = ipv6_hdr(skb); 92 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) || 93 !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) || 94 skb->mark != rt_info->mark) 95 return ip6_route_me_harder(entry->state.net, entry->state.sk, skb); 96 } 97 return 0; 98 } 99 100 int __nf_ip6_route(struct net *net, struct dst_entry **dst, 101 struct flowi *fl, bool strict) 102 { 103 static const struct ipv6_pinfo fake_pinfo; 104 static const struct inet_sock fake_sk = { 105 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 106 .sk.sk_bound_dev_if = 1, 107 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 108 }; 109 const void *sk = strict ? &fake_sk : NULL; 110 struct dst_entry *result; 111 int err; 112 113 result = ip6_route_output(net, sk, &fl->u.ip6); 114 err = result->error; 115 if (err) 116 dst_release(result); 117 else 118 *dst = result; 119 return err; 120 } 121 EXPORT_SYMBOL_GPL(__nf_ip6_route); 122 123 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 124 struct nf_bridge_frag_data *data, 125 int (*output)(struct net *, struct sock *sk, 126 const struct nf_bridge_frag_data *data, 127 struct sk_buff *)) 128 { 129 int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size; 130 u8 tstamp_type = skb->tstamp_type; 131 ktime_t tstamp = skb->tstamp; 132 struct ip6_frag_state state; 133 u8 *prevhdr, nexthdr = 0; 134 unsigned int mtu, hlen; 135 int hroom, err = 0; 136 __be32 frag_id; 137 138 err = ip6_find_1stfragopt(skb, &prevhdr); 139 if (err < 0) 140 goto blackhole; 141 hlen = err; 142 nexthdr = *prevhdr; 143 144 mtu = skb->dev->mtu; 145 if (frag_max_size > mtu || 146 frag_max_size < IPV6_MIN_MTU) 147 goto blackhole; 148 149 mtu = frag_max_size; 150 if (mtu < hlen + sizeof(struct frag_hdr) + 8) 151 goto blackhole; 152 mtu -= hlen + sizeof(struct frag_hdr); 153 154 frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, 155 &ipv6_hdr(skb)->saddr); 156 157 if (skb->ip_summed == CHECKSUM_PARTIAL && 158 (err = skb_checksum_help(skb))) 159 goto blackhole; 160 161 hroom = LL_RESERVED_SPACE(skb->dev); 162 if (skb_has_frag_list(skb)) { 163 unsigned int first_len = skb_pagelen(skb); 164 struct ip6_fraglist_iter iter; 165 struct sk_buff *frag2; 166 167 if (first_len - hlen > mtu || 168 skb_headroom(skb) < (hroom + sizeof(struct frag_hdr))) 169 goto blackhole; 170 171 if (skb_cloned(skb)) 172 goto slow_path; 173 174 skb_walk_frags(skb, frag2) { 175 if (frag2->len > mtu || 176 skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr))) 177 goto blackhole; 178 179 /* Partially cloned skb? */ 180 if (skb_shared(frag2)) 181 goto slow_path; 182 } 183 184 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id, 185 &iter); 186 if (err < 0) 187 goto blackhole; 188 189 for (;;) { 190 /* Prepare header of the next frame, 191 * before previous one went down. 192 */ 193 if (iter.frag) 194 ip6_fraglist_prepare(skb, &iter); 195 196 skb_set_delivery_time(skb, tstamp, tstamp_type); 197 err = output(net, sk, data, skb); 198 if (err || !iter.frag) 199 break; 200 201 skb = ip6_fraglist_next(&iter); 202 } 203 204 kfree(iter.tmp_hdr); 205 if (!err) 206 return 0; 207 208 kfree_skb_list(iter.frag); 209 return err; 210 } 211 slow_path: 212 /* This is a linearized skbuff, the original geometry is lost for us. 213 * This may also be a clone skbuff, we could preserve the geometry for 214 * the copies but probably not worth the effort. 215 */ 216 ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom, 217 LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id, 218 &state); 219 220 while (state.left > 0) { 221 struct sk_buff *skb2; 222 223 skb2 = ip6_frag_next(skb, &state); 224 if (IS_ERR(skb2)) { 225 err = PTR_ERR(skb2); 226 goto blackhole; 227 } 228 229 skb_set_delivery_time(skb2, tstamp, tstamp_type); 230 err = output(net, sk, data, skb2); 231 if (err) 232 goto blackhole; 233 } 234 consume_skb(skb); 235 return err; 236 237 blackhole: 238 kfree_skb(skb); 239 return 0; 240 } 241 EXPORT_SYMBOL_GPL(br_ip6_fragment); 242 243 static const struct nf_ipv6_ops ipv6ops = { 244 #if IS_MODULE(CONFIG_IPV6) 245 .chk_addr = ipv6_chk_addr, 246 .route_me_harder = ip6_route_me_harder, 247 .dev_get_saddr = ipv6_dev_get_saddr, 248 .route = __nf_ip6_route, 249 #if IS_ENABLED(CONFIG_SYN_COOKIES) 250 .cookie_init_sequence = __cookie_v6_init_sequence, 251 .cookie_v6_check = __cookie_v6_check, 252 #endif 253 #endif 254 .route_input = ip6_route_input, 255 .fragment = ip6_fragment, 256 .reroute = nf_ip6_reroute, 257 #if IS_MODULE(CONFIG_IPV6) 258 .br_fragment = br_ip6_fragment, 259 #endif 260 }; 261 262 int __init ipv6_netfilter_init(void) 263 { 264 RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops); 265 return 0; 266 } 267 268 /* This can be called from inet6_init() on errors, so it cannot 269 * be marked __exit. -DaveM 270 */ 271 void ipv6_netfilter_fini(void) 272 { 273 RCU_INIT_POINTER(nf_ipv6_ops, NULL); 274 } 275