1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * IPv6 specific functions of netfilter core 4 * 5 * Rusty Russell (C) 2000 6 * Patrick McHardy (C) 2006-2012 7 */ 8 #include <linux/kernel.h> 9 #include <linux/init.h> 10 #include <linux/ipv6.h> 11 #include <linux/netfilter.h> 12 #include <linux/netfilter_ipv6.h> 13 #include <linux/export.h> 14 #include <net/addrconf.h> 15 #include <net/dst.h> 16 #include <net/ipv6.h> 17 #include <net/ip6_route.h> 18 #include <net/xfrm.h> 19 #include <net/netfilter/nf_queue.h> 20 #include <net/netfilter/nf_conntrack_bridge.h> 21 #include <net/netfilter/ipv6/nf_defrag_ipv6.h> 22 #include "../bridge/br_private.h" 23 24 int ip6_route_me_harder(struct net *net, struct sock *sk_partial, struct sk_buff *skb) 25 { 26 const struct ipv6hdr *iph = ipv6_hdr(skb); 27 struct sock *sk = sk_to_full_sk(sk_partial); 28 struct net_device *dev = skb_dst_dev(skb); 29 struct flow_keys flkeys; 30 unsigned int hh_len; 31 struct dst_entry *dst; 32 int strict = (ipv6_addr_type(&iph->daddr) & 33 (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL)); 34 struct flowi6 fl6 = { 35 .flowi6_l3mdev = l3mdev_master_ifindex(dev), 36 .flowi6_mark = skb->mark, 37 .flowi6_uid = sock_net_uid(net, sk), 38 .daddr = iph->daddr, 39 .saddr = iph->saddr, 40 .flowlabel = ip6_flowinfo(iph), 41 }; 42 int err; 43 44 if (sk && sk->sk_bound_dev_if) 45 fl6.flowi6_oif = sk->sk_bound_dev_if; 46 else if (strict) 47 fl6.flowi6_oif = dev->ifindex; 48 49 fib6_rules_early_flow_dissect(net, skb, &fl6, &flkeys); 50 dst = ip6_route_output(net, sk, &fl6); 51 err = dst->error; 52 if (err) { 53 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); 54 net_dbg_ratelimited("ip6_route_me_harder: No more route\n"); 55 dst_release(dst); 56 return err; 57 } 58 59 /* Drop old route. */ 60 skb_dst_drop(skb); 61 62 skb_dst_set(skb, dst); 63 64 #ifdef CONFIG_XFRM 65 if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) && 66 xfrm_decode_session(net, skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) { 67 /* ignore return value from skb_dstref_steal, xfrm_lookup takes 68 * care of dropping the refcnt if needed. 69 */ 70 skb_dstref_steal(skb); 71 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 72 if (IS_ERR(dst)) 73 return PTR_ERR(dst); 74 skb_dst_set(skb, dst); 75 } 76 #endif 77 78 /* Change in oif may mean change in hh_len. */ 79 hh_len = skb_dst_dev(skb)->hard_header_len; 80 if (skb_headroom(skb) < hh_len && 81 pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)), 82 0, GFP_ATOMIC)) 83 return -ENOMEM; 84 85 return 0; 86 } 87 EXPORT_SYMBOL(ip6_route_me_harder); 88 89 int __nf_ip6_route(struct net *net, struct dst_entry **dst, 90 struct flowi *fl, bool strict) 91 { 92 static const struct ipv6_pinfo fake_pinfo; 93 static const struct inet_sock fake_sk = { 94 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */ 95 .sk.sk_bound_dev_if = 1, 96 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo, 97 }; 98 const void *sk = strict ? &fake_sk : NULL; 99 struct dst_entry *result; 100 int err; 101 102 result = ip6_route_output(net, sk, &fl->u.ip6); 103 err = result->error; 104 if (err) 105 dst_release(result); 106 else 107 *dst = result; 108 return err; 109 } 110 EXPORT_SYMBOL_GPL(__nf_ip6_route); 111 112 int br_ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 113 struct nf_bridge_frag_data *data, 114 int (*output)(struct net *, struct sock *sk, 115 const struct nf_bridge_frag_data *data, 116 struct sk_buff *)) 117 { 118 int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size; 119 u8 tstamp_type = skb->tstamp_type; 120 ktime_t tstamp = skb->tstamp; 121 struct ip6_frag_state state; 122 u8 *prevhdr, nexthdr = 0; 123 unsigned int mtu, hlen; 124 int hroom, err = 0; 125 __be32 frag_id; 126 127 err = ip6_find_1stfragopt(skb, &prevhdr); 128 if (err < 0) 129 goto blackhole; 130 hlen = err; 131 nexthdr = *prevhdr; 132 133 mtu = skb->dev->mtu; 134 if (frag_max_size > mtu || 135 frag_max_size < IPV6_MIN_MTU) 136 goto blackhole; 137 138 mtu = frag_max_size; 139 if (mtu < hlen + sizeof(struct frag_hdr) + 8) 140 goto blackhole; 141 mtu -= hlen + sizeof(struct frag_hdr); 142 143 frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, 144 &ipv6_hdr(skb)->saddr); 145 146 if (skb->ip_summed == CHECKSUM_PARTIAL && 147 (err = skb_checksum_help(skb))) 148 goto blackhole; 149 150 hroom = LL_RESERVED_SPACE(skb->dev); 151 if (skb_has_frag_list(skb)) { 152 unsigned int first_len = skb_pagelen(skb); 153 struct ip6_fraglist_iter iter; 154 struct sk_buff *frag2; 155 156 if (first_len - hlen > mtu) 157 goto blackhole; 158 159 if (skb_cloned(skb) || 160 skb_headroom(skb) < (hroom + sizeof(struct frag_hdr))) 161 goto slow_path; 162 163 skb_walk_frags(skb, frag2) { 164 if (frag2->len > mtu) 165 goto blackhole; 166 167 /* Partially cloned skb? */ 168 if (skb_shared(frag2) || 169 skb_headroom(frag2) < (hlen + hroom + sizeof(struct frag_hdr))) 170 goto slow_path; 171 } 172 173 err = ip6_fraglist_init(skb, hlen, prevhdr, nexthdr, frag_id, 174 &iter); 175 if (err < 0) 176 goto blackhole; 177 178 for (;;) { 179 /* Prepare header of the next frame, 180 * before previous one went down. 181 */ 182 if (iter.frag) 183 ip6_fraglist_prepare(skb, &iter); 184 185 skb_set_delivery_time(skb, tstamp, tstamp_type); 186 err = output(net, sk, data, skb); 187 if (err || !iter.frag) 188 break; 189 190 skb = ip6_fraglist_next(&iter); 191 } 192 193 kfree(iter.tmp_hdr); 194 if (!err) 195 return 0; 196 197 kfree_skb_list(iter.frag); 198 return err; 199 } 200 slow_path: 201 /* This is a linearized skbuff, the original geometry is lost for us. 202 * This may also be a clone skbuff, we could preserve the geometry for 203 * the copies but probably not worth the effort. 204 */ 205 ip6_frag_init(skb, hlen, mtu, skb->dev->needed_tailroom, 206 LL_RESERVED_SPACE(skb->dev), prevhdr, nexthdr, frag_id, 207 &state); 208 209 while (state.left > 0) { 210 struct sk_buff *skb2; 211 212 skb2 = ip6_frag_next(skb, &state); 213 if (IS_ERR(skb2)) { 214 err = PTR_ERR(skb2); 215 goto blackhole; 216 } 217 218 skb_set_delivery_time(skb2, tstamp, tstamp_type); 219 err = output(net, sk, data, skb2); 220 if (err) 221 goto blackhole; 222 } 223 consume_skb(skb); 224 return err; 225 226 blackhole: 227 kfree_skb(skb); 228 return 0; 229 } 230 EXPORT_SYMBOL_GPL(br_ip6_fragment); 231