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