xref: /linux/net/ipv6/xfrm6_policy.c (revision f3d9478b2ce468c3115b02ecae7e975990697f15) 
1 /*
2  * xfrm6_policy.c: based on xfrm4_policy.c
3  *
4  * Authors:
5  *	Mitsuru KANDA @USAGI
6  * 	Kazunori MIYAZAWA @USAGI
7  * 	Kunihiro Ishiguro <kunihiro@ipinfusion.com>
8  * 		IPv6 support
9  * 	YOSHIFUJI Hideaki
10  * 		Split up af-specific portion
11  *
12  */
13 
14 #include <linux/compiler.h>
15 #include <linux/config.h>
16 #include <linux/netdevice.h>
17 #include <net/addrconf.h>
18 #include <net/xfrm.h>
19 #include <net/ip.h>
20 #include <net/ipv6.h>
21 #include <net/ip6_route.h>
22 
23 static struct dst_ops xfrm6_dst_ops;
24 static struct xfrm_policy_afinfo xfrm6_policy_afinfo;
25 
26 static int xfrm6_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
27 {
28 	int err = 0;
29 	*dst = (struct xfrm_dst*)ip6_route_output(NULL, fl);
30 	if (!*dst)
31 		err = -ENETUNREACH;
32 	return err;
33 }
34 
35 static struct dst_entry *
36 __xfrm6_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
37 {
38 	struct dst_entry *dst;
39 
40 	/* Still not clear if we should set fl->fl6_{src,dst}... */
41 	read_lock_bh(&policy->lock);
42 	for (dst = policy->bundles; dst; dst = dst->next) {
43 		struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
44 		struct in6_addr fl_dst_prefix, fl_src_prefix;
45 
46 		ipv6_addr_prefix(&fl_dst_prefix,
47 				 &fl->fl6_dst,
48 				 xdst->u.rt6.rt6i_dst.plen);
49 		ipv6_addr_prefix(&fl_src_prefix,
50 				 &fl->fl6_src,
51 				 xdst->u.rt6.rt6i_src.plen);
52 		if (ipv6_addr_equal(&xdst->u.rt6.rt6i_dst.addr, &fl_dst_prefix) &&
53 		    ipv6_addr_equal(&xdst->u.rt6.rt6i_src.addr, &fl_src_prefix) &&
54 		    xfrm_bundle_ok(xdst, fl, AF_INET6)) {
55 			dst_clone(dst);
56 			break;
57 		}
58 	}
59 	read_unlock_bh(&policy->lock);
60 	return dst;
61 }
62 
63 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
64  * all the metrics... Shortly, bundle a bundle.
65  */
66 
67 static int
68 __xfrm6_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
69 		      struct flowi *fl, struct dst_entry **dst_p)
70 {
71 	struct dst_entry *dst, *dst_prev;
72 	struct rt6_info *rt0 = (struct rt6_info*)(*dst_p);
73 	struct rt6_info *rt  = rt0;
74 	struct in6_addr *remote = &fl->fl6_dst;
75 	struct in6_addr *local  = &fl->fl6_src;
76 	struct flowi fl_tunnel = {
77 		.nl_u = {
78 			.ip6_u = {
79 				.saddr = *local,
80 				.daddr = *remote
81 			}
82 		}
83 	};
84 	int i;
85 	int err = 0;
86 	int header_len = 0;
87 	int trailer_len = 0;
88 
89 	dst = dst_prev = NULL;
90 	dst_hold(&rt->u.dst);
91 
92 	for (i = 0; i < nx; i++) {
93 		struct dst_entry *dst1 = dst_alloc(&xfrm6_dst_ops);
94 		struct xfrm_dst *xdst;
95 		int tunnel = 0;
96 
97 		if (unlikely(dst1 == NULL)) {
98 			err = -ENOBUFS;
99 			dst_release(&rt->u.dst);
100 			goto error;
101 		}
102 
103 		if (!dst)
104 			dst = dst1;
105 		else {
106 			dst_prev->child = dst1;
107 			dst1->flags |= DST_NOHASH;
108 			dst_clone(dst1);
109 		}
110 
111 		xdst = (struct xfrm_dst *)dst1;
112 		xdst->route = &rt->u.dst;
113 		if (rt->rt6i_node)
114 			xdst->route_cookie = rt->rt6i_node->fn_sernum;
115 
116 		dst1->next = dst_prev;
117 		dst_prev = dst1;
118 		if (xfrm[i]->props.mode) {
119 			remote = (struct in6_addr*)&xfrm[i]->id.daddr;
120 			local  = (struct in6_addr*)&xfrm[i]->props.saddr;
121 			tunnel = 1;
122 		}
123 		header_len += xfrm[i]->props.header_len;
124 		trailer_len += xfrm[i]->props.trailer_len;
125 
126 		if (tunnel) {
127 			ipv6_addr_copy(&fl_tunnel.fl6_dst, remote);
128 			ipv6_addr_copy(&fl_tunnel.fl6_src, local);
129 			err = xfrm_dst_lookup((struct xfrm_dst **) &rt,
130 					      &fl_tunnel, AF_INET6);
131 			if (err)
132 				goto error;
133 		} else
134 			dst_hold(&rt->u.dst);
135 	}
136 
137 	dst_prev->child = &rt->u.dst;
138 	dst->path = &rt->u.dst;
139 	if (rt->rt6i_node)
140 		((struct xfrm_dst *)dst)->path_cookie = rt->rt6i_node->fn_sernum;
141 
142 	*dst_p = dst;
143 	dst = dst_prev;
144 
145 	dst_prev = *dst_p;
146 	i = 0;
147 	for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
148 		struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
149 
150 		dst_prev->xfrm = xfrm[i++];
151 		dst_prev->dev = rt->u.dst.dev;
152 		if (rt->u.dst.dev)
153 			dev_hold(rt->u.dst.dev);
154 		dst_prev->obsolete	= -1;
155 		dst_prev->flags	       |= DST_HOST;
156 		dst_prev->lastuse	= jiffies;
157 		dst_prev->header_len	= header_len;
158 		dst_prev->trailer_len	= trailer_len;
159 		memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
160 
161 		/* Copy neighbour for reachability confirmation */
162 		dst_prev->neighbour	= neigh_clone(rt->u.dst.neighbour);
163 		dst_prev->input		= rt->u.dst.input;
164 		dst_prev->output	= xfrm6_output;
165 		/* Sheit... I remember I did this right. Apparently,
166 		 * it was magically lost, so this code needs audit */
167 		x->u.rt6.rt6i_flags    = rt0->rt6i_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
168 		x->u.rt6.rt6i_metric   = rt0->rt6i_metric;
169 		x->u.rt6.rt6i_node     = rt0->rt6i_node;
170 		x->u.rt6.rt6i_gateway  = rt0->rt6i_gateway;
171 		memcpy(&x->u.rt6.rt6i_gateway, &rt0->rt6i_gateway, sizeof(x->u.rt6.rt6i_gateway));
172 		x->u.rt6.rt6i_dst      = rt0->rt6i_dst;
173 		x->u.rt6.rt6i_src      = rt0->rt6i_src;
174 		x->u.rt6.rt6i_idev     = rt0->rt6i_idev;
175 		in6_dev_hold(rt0->rt6i_idev);
176 		header_len -= x->u.dst.xfrm->props.header_len;
177 		trailer_len -= x->u.dst.xfrm->props.trailer_len;
178 	}
179 
180 	xfrm_init_pmtu(dst);
181 	return 0;
182 
183 error:
184 	if (dst)
185 		dst_free(dst);
186 	return err;
187 }
188 
189 static inline void
190 _decode_session6(struct sk_buff *skb, struct flowi *fl)
191 {
192 	u16 offset = skb->h.raw - skb->nh.raw;
193 	struct ipv6hdr *hdr = skb->nh.ipv6h;
194 	struct ipv6_opt_hdr *exthdr;
195 	u8 nexthdr = skb->nh.raw[IP6CB(skb)->nhoff];
196 
197 	memset(fl, 0, sizeof(struct flowi));
198 	ipv6_addr_copy(&fl->fl6_dst, &hdr->daddr);
199 	ipv6_addr_copy(&fl->fl6_src, &hdr->saddr);
200 
201 	while (pskb_may_pull(skb, skb->nh.raw + offset + 1 - skb->data)) {
202 		exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
203 
204 		switch (nexthdr) {
205 		case NEXTHDR_ROUTING:
206 		case NEXTHDR_HOP:
207 		case NEXTHDR_DEST:
208 			offset += ipv6_optlen(exthdr);
209 			nexthdr = exthdr->nexthdr;
210 			exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
211 			break;
212 
213 		case IPPROTO_UDP:
214 		case IPPROTO_TCP:
215 		case IPPROTO_SCTP:
216 		case IPPROTO_DCCP:
217 			if (pskb_may_pull(skb, skb->nh.raw + offset + 4 - skb->data)) {
218 				u16 *ports = (u16 *)exthdr;
219 
220 				fl->fl_ip_sport = ports[0];
221 				fl->fl_ip_dport = ports[1];
222 			}
223 			fl->proto = nexthdr;
224 			return;
225 
226 		case IPPROTO_ICMPV6:
227 			if (pskb_may_pull(skb, skb->nh.raw + offset + 2 - skb->data)) {
228 				u8 *icmp = (u8 *)exthdr;
229 
230 				fl->fl_icmp_type = icmp[0];
231 				fl->fl_icmp_code = icmp[1];
232 			}
233 			fl->proto = nexthdr;
234 			return;
235 
236 		/* XXX Why are there these headers? */
237 		case IPPROTO_AH:
238 		case IPPROTO_ESP:
239 		case IPPROTO_COMP:
240 		default:
241 			fl->fl_ipsec_spi = 0;
242 			fl->proto = nexthdr;
243 			return;
244 		};
245 	}
246 }
247 
248 static inline int xfrm6_garbage_collect(void)
249 {
250 	xfrm6_policy_afinfo.garbage_collect();
251 	return (atomic_read(&xfrm6_dst_ops.entries) > xfrm6_dst_ops.gc_thresh*2);
252 }
253 
254 static void xfrm6_update_pmtu(struct dst_entry *dst, u32 mtu)
255 {
256 	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
257 	struct dst_entry *path = xdst->route;
258 
259 	path->ops->update_pmtu(path, mtu);
260 }
261 
262 static void xfrm6_dst_destroy(struct dst_entry *dst)
263 {
264 	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
265 
266 	if (likely(xdst->u.rt6.rt6i_idev))
267 		in6_dev_put(xdst->u.rt6.rt6i_idev);
268 	xfrm_dst_destroy(xdst);
269 }
270 
271 static void xfrm6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
272 			     int unregister)
273 {
274 	struct xfrm_dst *xdst;
275 
276 	if (!unregister)
277 		return;
278 
279 	xdst = (struct xfrm_dst *)dst;
280 	if (xdst->u.rt6.rt6i_idev->dev == dev) {
281 		struct inet6_dev *loopback_idev = in6_dev_get(&loopback_dev);
282 		BUG_ON(!loopback_idev);
283 
284 		do {
285 			in6_dev_put(xdst->u.rt6.rt6i_idev);
286 			xdst->u.rt6.rt6i_idev = loopback_idev;
287 			in6_dev_hold(loopback_idev);
288 			xdst = (struct xfrm_dst *)xdst->u.dst.child;
289 		} while (xdst->u.dst.xfrm);
290 
291 		__in6_dev_put(loopback_idev);
292 	}
293 
294 	xfrm_dst_ifdown(dst, dev);
295 }
296 
297 static struct dst_ops xfrm6_dst_ops = {
298 	.family =		AF_INET6,
299 	.protocol =		__constant_htons(ETH_P_IPV6),
300 	.gc =			xfrm6_garbage_collect,
301 	.update_pmtu =		xfrm6_update_pmtu,
302 	.destroy =		xfrm6_dst_destroy,
303 	.ifdown =		xfrm6_dst_ifdown,
304 	.gc_thresh =		1024,
305 	.entry_size =		sizeof(struct xfrm_dst),
306 };
307 
308 static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
309 	.family =		AF_INET6,
310 	.dst_ops =		&xfrm6_dst_ops,
311 	.dst_lookup =		xfrm6_dst_lookup,
312 	.find_bundle =		__xfrm6_find_bundle,
313 	.bundle_create =	__xfrm6_bundle_create,
314 	.decode_session =	_decode_session6,
315 };
316 
317 static void __init xfrm6_policy_init(void)
318 {
319 	xfrm_policy_register_afinfo(&xfrm6_policy_afinfo);
320 }
321 
322 static void xfrm6_policy_fini(void)
323 {
324 	xfrm_policy_unregister_afinfo(&xfrm6_policy_afinfo);
325 }
326 
327 void __init xfrm6_init(void)
328 {
329 	xfrm6_policy_init();
330 	xfrm6_state_init();
331 }
332 
333 void xfrm6_fini(void)
334 {
335 	//xfrm6_input_fini();
336 	xfrm6_policy_fini();
337 	xfrm6_state_fini();
338 }
339