[NET]: Supporting UDP-Lite (RFC 3828) in Linux
[linux-2.6.git] / net / ipv4 / xfrm4_policy.c
1 /* 
2  * xfrm4_policy.c
3  *
4  * Changes:
5  *      Kazunori MIYAZAWA @USAGI
6  *      YOSHIFUJI Hideaki @USAGI
7  *              Split up af-specific portion
8  *      
9  */
10
11 #include <linux/compiler.h>
12 #include <linux/inetdevice.h>
13 #include <net/xfrm.h>
14 #include <net/ip.h>
15
16 static struct dst_ops xfrm4_dst_ops;
17 static struct xfrm_policy_afinfo xfrm4_policy_afinfo;
18
19 static int xfrm4_dst_lookup(struct xfrm_dst **dst, struct flowi *fl)
20 {
21         return __ip_route_output_key((struct rtable**)dst, fl);
22 }
23
24 static int xfrm4_get_saddr(xfrm_address_t *saddr, xfrm_address_t *daddr)
25 {
26         struct rtable *rt;
27         struct flowi fl_tunnel = {
28                 .nl_u = {
29                         .ip4_u = {
30                                 .daddr = daddr->a4,
31                         },
32                 },
33         };
34
35         if (!xfrm4_dst_lookup((struct xfrm_dst **)&rt, &fl_tunnel)) {
36                 saddr->a4 = rt->rt_src;
37                 dst_release(&rt->u.dst);
38                 return 0;
39         }
40         return -EHOSTUNREACH;
41 }
42
43 static struct dst_entry *
44 __xfrm4_find_bundle(struct flowi *fl, struct xfrm_policy *policy)
45 {
46         struct dst_entry *dst;
47
48         read_lock_bh(&policy->lock);
49         for (dst = policy->bundles; dst; dst = dst->next) {
50                 struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
51                 if (xdst->u.rt.fl.oif == fl->oif &&     /*XXX*/
52                     xdst->u.rt.fl.fl4_dst == fl->fl4_dst &&
53                     xdst->u.rt.fl.fl4_src == fl->fl4_src &&
54                     xdst->u.rt.fl.fl4_tos == fl->fl4_tos &&
55                     xfrm_bundle_ok(policy, xdst, fl, AF_INET, 0)) {
56                         dst_clone(dst);
57                         break;
58                 }
59         }
60         read_unlock_bh(&policy->lock);
61         return dst;
62 }
63
64 /* Allocate chain of dst_entry's, attach known xfrm's, calculate
65  * all the metrics... Shortly, bundle a bundle.
66  */
67
68 static int
69 __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int nx,
70                       struct flowi *fl, struct dst_entry **dst_p)
71 {
72         struct dst_entry *dst, *dst_prev;
73         struct rtable *rt0 = (struct rtable*)(*dst_p);
74         struct rtable *rt = rt0;
75         __be32 remote = fl->fl4_dst;
76         __be32 local  = fl->fl4_src;
77         struct flowi fl_tunnel = {
78                 .nl_u = {
79                         .ip4_u = {
80                                 .saddr = local,
81                                 .daddr = remote,
82                                 .tos = fl->fl4_tos
83                         }
84                 }
85         };
86         int i;
87         int err;
88         int header_len = 0;
89         int trailer_len = 0;
90
91         dst = dst_prev = NULL;
92         dst_hold(&rt->u.dst);
93
94         for (i = 0; i < nx; i++) {
95                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
96                 struct xfrm_dst *xdst;
97                 int tunnel = 0;
98
99                 if (unlikely(dst1 == NULL)) {
100                         err = -ENOBUFS;
101                         dst_release(&rt->u.dst);
102                         goto error;
103                 }
104
105                 if (!dst)
106                         dst = dst1;
107                 else {
108                         dst_prev->child = dst1;
109                         dst1->flags |= DST_NOHASH;
110                         dst_clone(dst1);
111                 }
112
113                 xdst = (struct xfrm_dst *)dst1;
114                 xdst->route = &rt->u.dst;
115                 xdst->genid = xfrm[i]->genid;
116
117                 dst1->next = dst_prev;
118                 dst_prev = dst1;
119                 if (xfrm[i]->props.mode != XFRM_MODE_TRANSPORT) {
120                         remote = xfrm[i]->id.daddr.a4;
121                         local  = xfrm[i]->props.saddr.a4;
122                         tunnel = 1;
123                 }
124                 header_len += xfrm[i]->props.header_len;
125                 trailer_len += xfrm[i]->props.trailer_len;
126
127                 if (tunnel) {
128                         fl_tunnel.fl4_src = local;
129                         fl_tunnel.fl4_dst = remote;
130                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
131                                               &fl_tunnel, AF_INET);
132                         if (err)
133                                 goto error;
134                 } else
135                         dst_hold(&rt->u.dst);
136         }
137
138         dst_prev->child = &rt->u.dst;
139         dst->path = &rt->u.dst;
140
141         *dst_p = dst;
142         dst = dst_prev;
143
144         dst_prev = *dst_p;
145         i = 0;
146         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
147                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
148                 x->u.rt.fl = *fl;
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->nfheader_len  = 0;
159                 dst_prev->trailer_len   = trailer_len;
160                 memcpy(&dst_prev->metrics, &x->route->metrics, sizeof(dst_prev->metrics));
161
162                 /* Copy neighbout for reachability confirmation */
163                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
164                 dst_prev->input         = rt->u.dst.input;
165                 dst_prev->output        = xfrm4_output;
166                 if (rt->peer)
167                         atomic_inc(&rt->peer->refcnt);
168                 x->u.rt.peer = rt->peer;
169                 /* Sheit... I remember I did this right. Apparently,
170                  * it was magically lost, so this code needs audit */
171                 x->u.rt.rt_flags = rt0->rt_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);
172                 x->u.rt.rt_type = rt->rt_type;
173                 x->u.rt.rt_src = rt0->rt_src;
174                 x->u.rt.rt_dst = rt0->rt_dst;
175                 x->u.rt.rt_gateway = rt->rt_gateway;
176                 x->u.rt.rt_spec_dst = rt0->rt_spec_dst;
177                 x->u.rt.idev = rt0->idev;
178                 in_dev_hold(rt0->idev);
179                 header_len -= x->u.dst.xfrm->props.header_len;
180                 trailer_len -= x->u.dst.xfrm->props.trailer_len;
181         }
182
183         xfrm_init_pmtu(dst);
184         return 0;
185
186 error:
187         if (dst)
188                 dst_free(dst);
189         return err;
190 }
191
192 static void
193 _decode_session4(struct sk_buff *skb, struct flowi *fl)
194 {
195         struct iphdr *iph = skb->nh.iph;
196         u8 *xprth = skb->nh.raw + iph->ihl*4;
197
198         memset(fl, 0, sizeof(struct flowi));
199         if (!(iph->frag_off & htons(IP_MF | IP_OFFSET))) {
200                 switch (iph->protocol) {
201                 case IPPROTO_UDP:
202                 case IPPROTO_UDPLITE:
203                 case IPPROTO_TCP:
204                 case IPPROTO_SCTP:
205                 case IPPROTO_DCCP:
206                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
207                                 __be16 *ports = (__be16 *)xprth;
208
209                                 fl->fl_ip_sport = ports[0];
210                                 fl->fl_ip_dport = ports[1];
211                         }
212                         break;
213
214                 case IPPROTO_ICMP:
215                         if (pskb_may_pull(skb, xprth + 2 - skb->data)) {
216                                 u8 *icmp = xprth;
217
218                                 fl->fl_icmp_type = icmp[0];
219                                 fl->fl_icmp_code = icmp[1];
220                         }
221                         break;
222
223                 case IPPROTO_ESP:
224                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
225                                 __be32 *ehdr = (__be32 *)xprth;
226
227                                 fl->fl_ipsec_spi = ehdr[0];
228                         }
229                         break;
230
231                 case IPPROTO_AH:
232                         if (pskb_may_pull(skb, xprth + 8 - skb->data)) {
233                                 __be32 *ah_hdr = (__be32*)xprth;
234
235                                 fl->fl_ipsec_spi = ah_hdr[1];
236                         }
237                         break;
238
239                 case IPPROTO_COMP:
240                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
241                                 __be16 *ipcomp_hdr = (__be16 *)xprth;
242
243                                 fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
244                         }
245                         break;
246                 default:
247                         fl->fl_ipsec_spi = 0;
248                         break;
249                 };
250         }
251         fl->proto = iph->protocol;
252         fl->fl4_dst = iph->daddr;
253         fl->fl4_src = iph->saddr;
254         fl->fl4_tos = iph->tos;
255 }
256
257 static inline int xfrm4_garbage_collect(void)
258 {
259         xfrm4_policy_afinfo.garbage_collect();
260         return (atomic_read(&xfrm4_dst_ops.entries) > xfrm4_dst_ops.gc_thresh*2);
261 }
262
263 static void xfrm4_update_pmtu(struct dst_entry *dst, u32 mtu)
264 {
265         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
266         struct dst_entry *path = xdst->route;
267
268         path->ops->update_pmtu(path, mtu);
269 }
270
271 static void xfrm4_dst_destroy(struct dst_entry *dst)
272 {
273         struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
274
275         if (likely(xdst->u.rt.idev))
276                 in_dev_put(xdst->u.rt.idev);
277         xfrm_dst_destroy(xdst);
278 }
279
280 static void xfrm4_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
281                              int unregister)
282 {
283         struct xfrm_dst *xdst;
284
285         if (!unregister)
286                 return;
287
288         xdst = (struct xfrm_dst *)dst;
289         if (xdst->u.rt.idev->dev == dev) {
290                 struct in_device *loopback_idev = in_dev_get(&loopback_dev);
291                 BUG_ON(!loopback_idev);
292
293                 do {
294                         in_dev_put(xdst->u.rt.idev);
295                         xdst->u.rt.idev = loopback_idev;
296                         in_dev_hold(loopback_idev);
297                         xdst = (struct xfrm_dst *)xdst->u.dst.child;
298                 } while (xdst->u.dst.xfrm);
299
300                 __in_dev_put(loopback_idev);
301         }
302
303         xfrm_dst_ifdown(dst, dev);
304 }
305
306 static struct dst_ops xfrm4_dst_ops = {
307         .family =               AF_INET,
308         .protocol =             __constant_htons(ETH_P_IP),
309         .gc =                   xfrm4_garbage_collect,
310         .update_pmtu =          xfrm4_update_pmtu,
311         .destroy =              xfrm4_dst_destroy,
312         .ifdown =               xfrm4_dst_ifdown,
313         .gc_thresh =            1024,
314         .entry_size =           sizeof(struct xfrm_dst),
315 };
316
317 static struct xfrm_policy_afinfo xfrm4_policy_afinfo = {
318         .family =               AF_INET,
319         .dst_ops =              &xfrm4_dst_ops,
320         .dst_lookup =           xfrm4_dst_lookup,
321         .get_saddr =            xfrm4_get_saddr,
322         .find_bundle =          __xfrm4_find_bundle,
323         .bundle_create =        __xfrm4_bundle_create,
324         .decode_session =       _decode_session4,
325 };
326
327 static void __init xfrm4_policy_init(void)
328 {
329         xfrm_policy_register_afinfo(&xfrm4_policy_afinfo);
330 }
331
332 static void __exit xfrm4_policy_fini(void)
333 {
334         xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
335 }
336
337 void __init xfrm4_init(void)
338 {
339         xfrm4_state_init();
340         xfrm4_policy_init();
341 }
342