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
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