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
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