[IPSEC]: Separate inner/outer mode processing on input
[linux-2.6] / net / ipv4 / ipcomp.c
1 /*
2  * IP Payload Compression Protocol (IPComp) - RFC3173.
3  *
4  * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  * Todo:
12  *   - Tunable compression parameters.
13  *   - Compression stats.
14  *   - Adaptive compression.
15  */
16 #include <linux/module.h>
17 #include <asm/semaphore.h>
18 #include <linux/crypto.h>
19 #include <linux/err.h>
20 #include <linux/pfkeyv2.h>
21 #include <linux/percpu.h>
22 #include <linux/smp.h>
23 #include <linux/list.h>
24 #include <linux/vmalloc.h>
25 #include <linux/rtnetlink.h>
26 #include <linux/mutex.h>
27 #include <net/ip.h>
28 #include <net/xfrm.h>
29 #include <net/icmp.h>
30 #include <net/ipcomp.h>
31 #include <net/protocol.h>
32
33 struct ipcomp_tfms {
34         struct list_head list;
35         struct crypto_comp **tfms;
36         int users;
37 };
38
39 static DEFINE_MUTEX(ipcomp_resource_mutex);
40 static void **ipcomp_scratches;
41 static int ipcomp_scratch_users;
42 static LIST_HEAD(ipcomp_tfms_list);
43
44 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
45 {
46         struct ipcomp_data *ipcd = x->data;
47         const int plen = skb->len;
48         int dlen = IPCOMP_SCRATCH_SIZE;
49         const u8 *start = skb->data;
50         const int cpu = get_cpu();
51         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
52         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
53         int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
54
55         if (err)
56                 goto out;
57
58         if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
59                 err = -EINVAL;
60                 goto out;
61         }
62
63         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
64         if (err)
65                 goto out;
66
67         skb->truesize += dlen - plen;
68         __skb_put(skb, dlen - plen);
69         skb_copy_to_linear_data(skb, scratch, dlen);
70 out:
71         put_cpu();
72         return err;
73 }
74
75 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
76 {
77         int err = -ENOMEM;
78         struct ip_comp_hdr *ipch;
79
80         if (skb_linearize_cow(skb))
81                 goto out;
82
83         skb->ip_summed = CHECKSUM_NONE;
84
85         /* Remove ipcomp header and decompress original payload */
86         ipch = (void *)skb->data;
87         skb->transport_header = skb->network_header + sizeof(*ipch);
88         __skb_pull(skb, sizeof(*ipch));
89         err = ipcomp_decompress(x, skb);
90         if (err)
91                 goto out;
92
93         err = ipch->nexthdr;
94
95 out:
96         return err;
97 }
98
99 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
100 {
101         struct ipcomp_data *ipcd = x->data;
102         const int plen = skb->len;
103         int dlen = IPCOMP_SCRATCH_SIZE;
104         u8 *start = skb->data;
105         const int cpu = get_cpu();
106         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
107         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
108         int err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
109
110         if (err)
111                 goto out;
112
113         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
114                 err = -EMSGSIZE;
115                 goto out;
116         }
117
118         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
119         put_cpu();
120
121         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
122         return 0;
123
124 out:
125         put_cpu();
126         return err;
127 }
128
129 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
130 {
131         int err;
132         struct ip_comp_hdr *ipch;
133         struct ipcomp_data *ipcd = x->data;
134
135         if (skb->len < ipcd->threshold) {
136                 /* Don't bother compressing */
137                 goto out_ok;
138         }
139
140         if (skb_linearize_cow(skb))
141                 goto out_ok;
142
143         err = ipcomp_compress(x, skb);
144
145         if (err) {
146                 goto out_ok;
147         }
148
149         /* Install ipcomp header, convert into ipcomp datagram. */
150         ipch = ip_comp_hdr(skb);
151         ipch->nexthdr = *skb_mac_header(skb);
152         ipch->flags = 0;
153         ipch->cpi = htons((u16 )ntohl(x->id.spi));
154         *skb_mac_header(skb) = IPPROTO_COMP;
155 out_ok:
156         skb_push(skb, -skb_network_offset(skb));
157         return 0;
158 }
159
160 static void ipcomp4_err(struct sk_buff *skb, u32 info)
161 {
162         __be32 spi;
163         struct iphdr *iph = (struct iphdr *)skb->data;
164         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
165         struct xfrm_state *x;
166
167         if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH ||
168             icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
169                 return;
170
171         spi = htonl(ntohs(ipch->cpi));
172         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
173                               spi, IPPROTO_COMP, AF_INET);
174         if (!x)
175                 return;
176         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
177                  spi, NIPQUAD(iph->daddr));
178         xfrm_state_put(x);
179 }
180
181 /* We always hold one tunnel user reference to indicate a tunnel */
182 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
183 {
184         struct xfrm_state *t;
185
186         t = xfrm_state_alloc();
187         if (t == NULL)
188                 goto out;
189
190         t->id.proto = IPPROTO_IPIP;
191         t->id.spi = x->props.saddr.a4;
192         t->id.daddr.a4 = x->id.daddr.a4;
193         memcpy(&t->sel, &x->sel, sizeof(t->sel));
194         t->props.family = AF_INET;
195         t->props.mode = x->props.mode;
196         t->props.saddr.a4 = x->props.saddr.a4;
197         t->props.flags = x->props.flags;
198
199         if (xfrm_init_state(t))
200                 goto error;
201
202         atomic_set(&t->tunnel_users, 1);
203 out:
204         return t;
205
206 error:
207         t->km.state = XFRM_STATE_DEAD;
208         xfrm_state_put(t);
209         t = NULL;
210         goto out;
211 }
212
213 /*
214  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
215  * always incremented on success.
216  */
217 static int ipcomp_tunnel_attach(struct xfrm_state *x)
218 {
219         int err = 0;
220         struct xfrm_state *t;
221
222         t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
223                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
224         if (!t) {
225                 t = ipcomp_tunnel_create(x);
226                 if (!t) {
227                         err = -EINVAL;
228                         goto out;
229                 }
230                 xfrm_state_insert(t);
231                 xfrm_state_hold(t);
232         }
233         x->tunnel = t;
234         atomic_inc(&t->tunnel_users);
235 out:
236         return err;
237 }
238
239 static void ipcomp_free_scratches(void)
240 {
241         int i;
242         void **scratches;
243
244         if (--ipcomp_scratch_users)
245                 return;
246
247         scratches = ipcomp_scratches;
248         if (!scratches)
249                 return;
250
251         for_each_possible_cpu(i)
252                 vfree(*per_cpu_ptr(scratches, i));
253
254         free_percpu(scratches);
255 }
256
257 static void **ipcomp_alloc_scratches(void)
258 {
259         int i;
260         void **scratches;
261
262         if (ipcomp_scratch_users++)
263                 return ipcomp_scratches;
264
265         scratches = alloc_percpu(void *);
266         if (!scratches)
267                 return NULL;
268
269         ipcomp_scratches = scratches;
270
271         for_each_possible_cpu(i) {
272                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
273                 if (!scratch)
274                         return NULL;
275                 *per_cpu_ptr(scratches, i) = scratch;
276         }
277
278         return scratches;
279 }
280
281 static void ipcomp_free_tfms(struct crypto_comp **tfms)
282 {
283         struct ipcomp_tfms *pos;
284         int cpu;
285
286         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
287                 if (pos->tfms == tfms)
288                         break;
289         }
290
291         BUG_TRAP(pos);
292
293         if (--pos->users)
294                 return;
295
296         list_del(&pos->list);
297         kfree(pos);
298
299         if (!tfms)
300                 return;
301
302         for_each_possible_cpu(cpu) {
303                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
304                 crypto_free_comp(tfm);
305         }
306         free_percpu(tfms);
307 }
308
309 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
310 {
311         struct ipcomp_tfms *pos;
312         struct crypto_comp **tfms;
313         int cpu;
314
315         /* This can be any valid CPU ID so we don't need locking. */
316         cpu = raw_smp_processor_id();
317
318         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
319                 struct crypto_comp *tfm;
320
321                 tfms = pos->tfms;
322                 tfm = *per_cpu_ptr(tfms, cpu);
323
324                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
325                         pos->users++;
326                         return tfms;
327                 }
328         }
329
330         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
331         if (!pos)
332                 return NULL;
333
334         pos->users = 1;
335         INIT_LIST_HEAD(&pos->list);
336         list_add(&pos->list, &ipcomp_tfms_list);
337
338         pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
339         if (!tfms)
340                 goto error;
341
342         for_each_possible_cpu(cpu) {
343                 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
344                                                             CRYPTO_ALG_ASYNC);
345                 if (IS_ERR(tfm))
346                         goto error;
347                 *per_cpu_ptr(tfms, cpu) = tfm;
348         }
349
350         return tfms;
351
352 error:
353         ipcomp_free_tfms(tfms);
354         return NULL;
355 }
356
357 static void ipcomp_free_data(struct ipcomp_data *ipcd)
358 {
359         if (ipcd->tfms)
360                 ipcomp_free_tfms(ipcd->tfms);
361         ipcomp_free_scratches();
362 }
363
364 static void ipcomp_destroy(struct xfrm_state *x)
365 {
366         struct ipcomp_data *ipcd = x->data;
367         if (!ipcd)
368                 return;
369         xfrm_state_delete_tunnel(x);
370         mutex_lock(&ipcomp_resource_mutex);
371         ipcomp_free_data(ipcd);
372         mutex_unlock(&ipcomp_resource_mutex);
373         kfree(ipcd);
374 }
375
376 static int ipcomp_init_state(struct xfrm_state *x)
377 {
378         int err;
379         struct ipcomp_data *ipcd;
380         struct xfrm_algo_desc *calg_desc;
381
382         err = -EINVAL;
383         if (!x->calg)
384                 goto out;
385
386         if (x->encap)
387                 goto out;
388
389         x->props.header_len = 0;
390         switch (x->props.mode) {
391         case XFRM_MODE_TRANSPORT:
392                 break;
393         case XFRM_MODE_TUNNEL:
394                 x->props.header_len += sizeof(struct iphdr);
395                 break;
396         default:
397                 goto out;
398         }
399
400         err = -ENOMEM;
401         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
402         if (!ipcd)
403                 goto out;
404
405         mutex_lock(&ipcomp_resource_mutex);
406         if (!ipcomp_alloc_scratches())
407                 goto error;
408
409         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
410         if (!ipcd->tfms)
411                 goto error;
412         mutex_unlock(&ipcomp_resource_mutex);
413
414         if (x->props.mode == XFRM_MODE_TUNNEL) {
415                 err = ipcomp_tunnel_attach(x);
416                 if (err)
417                         goto error_tunnel;
418         }
419
420         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
421         BUG_ON(!calg_desc);
422         ipcd->threshold = calg_desc->uinfo.comp.threshold;
423         x->data = ipcd;
424         err = 0;
425 out:
426         return err;
427
428 error_tunnel:
429         mutex_lock(&ipcomp_resource_mutex);
430 error:
431         ipcomp_free_data(ipcd);
432         mutex_unlock(&ipcomp_resource_mutex);
433         kfree(ipcd);
434         goto out;
435 }
436
437 static struct xfrm_type ipcomp_type = {
438         .description    = "IPCOMP4",
439         .owner          = THIS_MODULE,
440         .proto          = IPPROTO_COMP,
441         .init_state     = ipcomp_init_state,
442         .destructor     = ipcomp_destroy,
443         .input          = ipcomp_input,
444         .output         = ipcomp_output
445 };
446
447 static struct net_protocol ipcomp4_protocol = {
448         .handler        =       xfrm4_rcv,
449         .err_handler    =       ipcomp4_err,
450         .no_policy      =       1,
451 };
452
453 static int __init ipcomp4_init(void)
454 {
455         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
456                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
457                 return -EAGAIN;
458         }
459         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
460                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
461                 xfrm_unregister_type(&ipcomp_type, AF_INET);
462                 return -EAGAIN;
463         }
464         return 0;
465 }
466
467 static void __exit ipcomp4_fini(void)
468 {
469         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
470                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
471         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
472                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
473 }
474
475 module_init(ipcomp4_init);
476 module_exit(ipcomp4_fini);
477
478 MODULE_LICENSE("GPL");
479 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
480 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
481
482 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);