[NET]: Fix "ntohl(ntohs" bugs
[linux-2.6.git] / 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/config.h>
17 #include <linux/module.h>
18 #include <asm/scatterlist.h>
19 #include <asm/semaphore.h>
20 #include <linux/crypto.h>
21 #include <linux/pfkeyv2.h>
22 #include <linux/percpu.h>
23 #include <linux/smp.h>
24 #include <linux/list.h>
25 #include <linux/vmalloc.h>
26 #include <linux/rtnetlink.h>
27 #include <linux/mutex.h>
28 #include <net/ip.h>
29 #include <net/xfrm.h>
30 #include <net/icmp.h>
31 #include <net/ipcomp.h>
32 #include <net/protocol.h>
33
34 struct ipcomp_tfms {
35         struct list_head list;
36         struct crypto_tfm **tfms;
37         int users;
38 };
39
40 static DEFINE_MUTEX(ipcomp_resource_mutex);
41 static void **ipcomp_scratches;
42 static int ipcomp_scratch_users;
43 static LIST_HEAD(ipcomp_tfms_list);
44
45 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
46 {
47         int err, plen, dlen;
48         struct iphdr *iph;
49         struct ipcomp_data *ipcd = x->data;
50         u8 *start, *scratch;
51         struct crypto_tfm *tfm;
52         int cpu;
53         
54         plen = skb->len;
55         dlen = IPCOMP_SCRATCH_SIZE;
56         start = skb->data;
57
58         cpu = get_cpu();
59         scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
60         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
61
62         err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
63         if (err)
64                 goto out;
65
66         if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
67                 err = -EINVAL;
68                 goto out;
69         }
70
71         err = pskb_expand_head(skb, 0, dlen - plen, GFP_ATOMIC);
72         if (err)
73                 goto out;
74                 
75         skb_put(skb, dlen - plen);
76         memcpy(skb->data, scratch, dlen);
77         iph = skb->nh.iph;
78         iph->tot_len = htons(dlen + iph->ihl * 4);
79 out:    
80         put_cpu();
81         return err;
82 }
83
84 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
85 {
86         u8 nexthdr;
87         int err = 0;
88         struct iphdr *iph;
89         union {
90                 struct iphdr    iph;
91                 char            buf[60];
92         } tmp_iph;
93
94
95         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
96             skb_linearize(skb, GFP_ATOMIC) != 0) {
97                 err = -ENOMEM;
98                 goto out;
99         }
100
101         skb->ip_summed = CHECKSUM_NONE;
102
103         /* Remove ipcomp header and decompress original payload */      
104         iph = skb->nh.iph;
105         memcpy(&tmp_iph, iph, iph->ihl * 4);
106         nexthdr = *(u8 *)skb->data;
107         skb_pull(skb, sizeof(struct ip_comp_hdr));
108         skb->nh.raw += sizeof(struct ip_comp_hdr);
109         memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);
110         iph = skb->nh.iph;
111         iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));
112         iph->protocol = nexthdr;
113         skb->h.raw = skb->data;
114         err = ipcomp_decompress(x, skb);
115
116 out:    
117         return err;
118 }
119
120 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
121 {
122         int err, plen, dlen, ihlen;
123         struct iphdr *iph = skb->nh.iph;
124         struct ipcomp_data *ipcd = x->data;
125         u8 *start, *scratch;
126         struct crypto_tfm *tfm;
127         int cpu;
128         
129         ihlen = iph->ihl * 4;
130         plen = skb->len - ihlen;
131         dlen = IPCOMP_SCRATCH_SIZE;
132         start = skb->data + ihlen;
133
134         cpu = get_cpu();
135         scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
136         tfm = *per_cpu_ptr(ipcd->tfms, cpu);
137
138         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
139         if (err)
140                 goto out;
141
142         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
143                 err = -EMSGSIZE;
144                 goto out;
145         }
146         
147         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
148         put_cpu();
149
150         pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
151         return 0;
152         
153 out:    
154         put_cpu();
155         return err;
156 }
157
158 static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
159 {
160         int err;
161         struct iphdr *iph;
162         struct ip_comp_hdr *ipch;
163         struct ipcomp_data *ipcd = x->data;
164         int hdr_len = 0;
165
166         iph = skb->nh.iph;
167         iph->tot_len = htons(skb->len);
168         hdr_len = iph->ihl * 4;
169         if ((skb->len - hdr_len) < ipcd->threshold) {
170                 /* Don't bother compressing */
171                 goto out_ok;
172         }
173
174         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
175             skb_linearize(skb, GFP_ATOMIC) != 0) {
176                 goto out_ok;
177         }
178         
179         err = ipcomp_compress(x, skb);
180         iph = skb->nh.iph;
181
182         if (err) {
183                 goto out_ok;
184         }
185
186         /* Install ipcomp header, convert into ipcomp datagram. */
187         iph->tot_len = htons(skb->len);
188         ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
189         ipch->nexthdr = iph->protocol;
190         ipch->flags = 0;
191         ipch->cpi = htons((u16 )ntohl(x->id.spi));
192         iph->protocol = IPPROTO_COMP;
193         ip_send_check(iph);
194         return 0;
195
196 out_ok:
197         if (x->props.mode)
198                 ip_send_check(iph);
199         return 0;
200 }
201
202 static void ipcomp4_err(struct sk_buff *skb, u32 info)
203 {
204         u32 spi;
205         struct iphdr *iph = (struct iphdr *)skb->data;
206         struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
207         struct xfrm_state *x;
208
209         if (skb->h.icmph->type != ICMP_DEST_UNREACH ||
210             skb->h.icmph->code != ICMP_FRAG_NEEDED)
211                 return;
212
213         spi = htonl(ntohs(ipch->cpi));
214         x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr,
215                               spi, IPPROTO_COMP, AF_INET);
216         if (!x)
217                 return;
218         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%u.%u.%u.%u\n",
219                  spi, NIPQUAD(iph->daddr));
220         xfrm_state_put(x);
221 }
222
223 /* We always hold one tunnel user reference to indicate a tunnel */ 
224 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
225 {
226         struct xfrm_state *t;
227         
228         t = xfrm_state_alloc();
229         if (t == NULL)
230                 goto out;
231
232         t->id.proto = IPPROTO_IPIP;
233         t->id.spi = x->props.saddr.a4;
234         t->id.daddr.a4 = x->id.daddr.a4;
235         memcpy(&t->sel, &x->sel, sizeof(t->sel));
236         t->props.family = AF_INET;
237         t->props.mode = 1;
238         t->props.saddr.a4 = x->props.saddr.a4;
239         t->props.flags = x->props.flags;
240
241         if (xfrm_init_state(t))
242                 goto error;
243
244         atomic_set(&t->tunnel_users, 1);
245 out:
246         return t;
247
248 error:
249         t->km.state = XFRM_STATE_DEAD;
250         xfrm_state_put(t);
251         t = NULL;
252         goto out;
253 }
254
255 /*
256  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
257  * always incremented on success.
258  */
259 static int ipcomp_tunnel_attach(struct xfrm_state *x)
260 {
261         int err = 0;
262         struct xfrm_state *t;
263
264         t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4,
265                               x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
266         if (!t) {
267                 t = ipcomp_tunnel_create(x);
268                 if (!t) {
269                         err = -EINVAL;
270                         goto out;
271                 }
272                 xfrm_state_insert(t);
273                 xfrm_state_hold(t);
274         }
275         x->tunnel = t;
276         atomic_inc(&t->tunnel_users);
277 out:
278         return err;
279 }
280
281 static void ipcomp_free_scratches(void)
282 {
283         int i;
284         void **scratches;
285
286         if (--ipcomp_scratch_users)
287                 return;
288
289         scratches = ipcomp_scratches;
290         if (!scratches)
291                 return;
292
293         for_each_possible_cpu(i)
294                 vfree(*per_cpu_ptr(scratches, i));
295
296         free_percpu(scratches);
297 }
298
299 static void **ipcomp_alloc_scratches(void)
300 {
301         int i;
302         void **scratches;
303
304         if (ipcomp_scratch_users++)
305                 return ipcomp_scratches;
306
307         scratches = alloc_percpu(void *);
308         if (!scratches)
309                 return NULL;
310
311         ipcomp_scratches = scratches;
312
313         for_each_possible_cpu(i) {
314                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
315                 if (!scratch)
316                         return NULL;
317                 *per_cpu_ptr(scratches, i) = scratch;
318         }
319
320         return scratches;
321 }
322
323 static void ipcomp_free_tfms(struct crypto_tfm **tfms)
324 {
325         struct ipcomp_tfms *pos;
326         int cpu;
327
328         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
329                 if (pos->tfms == tfms)
330                         break;
331         }
332
333         BUG_TRAP(pos);
334
335         if (--pos->users)
336                 return;
337
338         list_del(&pos->list);
339         kfree(pos);
340
341         if (!tfms)
342                 return;
343
344         for_each_possible_cpu(cpu) {
345                 struct crypto_tfm *tfm = *per_cpu_ptr(tfms, cpu);
346                 crypto_free_tfm(tfm);
347         }
348         free_percpu(tfms);
349 }
350
351 static struct crypto_tfm **ipcomp_alloc_tfms(const char *alg_name)
352 {
353         struct ipcomp_tfms *pos;
354         struct crypto_tfm **tfms;
355         int cpu;
356
357         /* This can be any valid CPU ID so we don't need locking. */
358         cpu = raw_smp_processor_id();
359
360         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
361                 struct crypto_tfm *tfm;
362
363                 tfms = pos->tfms;
364                 tfm = *per_cpu_ptr(tfms, cpu);
365
366                 if (!strcmp(crypto_tfm_alg_name(tfm), alg_name)) {
367                         pos->users++;
368                         return tfms;
369                 }
370         }
371
372         pos = kmalloc(sizeof(*pos), GFP_KERNEL);
373         if (!pos)
374                 return NULL;
375
376         pos->users = 1;
377         INIT_LIST_HEAD(&pos->list);
378         list_add(&pos->list, &ipcomp_tfms_list);
379
380         pos->tfms = tfms = alloc_percpu(struct crypto_tfm *);
381         if (!tfms)
382                 goto error;
383
384         for_each_possible_cpu(cpu) {
385                 struct crypto_tfm *tfm = crypto_alloc_tfm(alg_name, 0);
386                 if (!tfm)
387                         goto error;
388                 *per_cpu_ptr(tfms, cpu) = tfm;
389         }
390
391         return tfms;
392
393 error:
394         ipcomp_free_tfms(tfms);
395         return NULL;
396 }
397
398 static void ipcomp_free_data(struct ipcomp_data *ipcd)
399 {
400         if (ipcd->tfms)
401                 ipcomp_free_tfms(ipcd->tfms);
402         ipcomp_free_scratches();
403 }
404
405 static void ipcomp_destroy(struct xfrm_state *x)
406 {
407         struct ipcomp_data *ipcd = x->data;
408         if (!ipcd)
409                 return;
410         xfrm_state_delete_tunnel(x);
411         mutex_lock(&ipcomp_resource_mutex);
412         ipcomp_free_data(ipcd);
413         mutex_unlock(&ipcomp_resource_mutex);
414         kfree(ipcd);
415 }
416
417 static int ipcomp_init_state(struct xfrm_state *x)
418 {
419         int err;
420         struct ipcomp_data *ipcd;
421         struct xfrm_algo_desc *calg_desc;
422
423         err = -EINVAL;
424         if (!x->calg)
425                 goto out;
426
427         if (x->encap)
428                 goto out;
429
430         err = -ENOMEM;
431         ipcd = kmalloc(sizeof(*ipcd), GFP_KERNEL);
432         if (!ipcd)
433                 goto out;
434
435         memset(ipcd, 0, sizeof(*ipcd));
436         x->props.header_len = 0;
437         if (x->props.mode)
438                 x->props.header_len += sizeof(struct iphdr);
439
440         mutex_lock(&ipcomp_resource_mutex);
441         if (!ipcomp_alloc_scratches())
442                 goto error;
443
444         ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
445         if (!ipcd->tfms)
446                 goto error;
447         mutex_unlock(&ipcomp_resource_mutex);
448
449         if (x->props.mode) {
450                 err = ipcomp_tunnel_attach(x);
451                 if (err)
452                         goto error_tunnel;
453         }
454
455         calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
456         BUG_ON(!calg_desc);
457         ipcd->threshold = calg_desc->uinfo.comp.threshold;
458         x->data = ipcd;
459         err = 0;
460 out:
461         return err;
462
463 error_tunnel:
464         mutex_lock(&ipcomp_resource_mutex);
465 error:
466         ipcomp_free_data(ipcd);
467         mutex_unlock(&ipcomp_resource_mutex);
468         kfree(ipcd);
469         goto out;
470 }
471
472 static struct xfrm_type ipcomp_type = {
473         .description    = "IPCOMP4",
474         .owner          = THIS_MODULE,
475         .proto          = IPPROTO_COMP,
476         .init_state     = ipcomp_init_state,
477         .destructor     = ipcomp_destroy,
478         .input          = ipcomp_input,
479         .output         = ipcomp_output
480 };
481
482 static struct net_protocol ipcomp4_protocol = {
483         .handler        =       xfrm4_rcv,
484         .err_handler    =       ipcomp4_err,
485         .no_policy      =       1,
486 };
487
488 static int __init ipcomp4_init(void)
489 {
490         if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
491                 printk(KERN_INFO "ipcomp init: can't add xfrm type\n");
492                 return -EAGAIN;
493         }
494         if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
495                 printk(KERN_INFO "ipcomp init: can't add protocol\n");
496                 xfrm_unregister_type(&ipcomp_type, AF_INET);
497                 return -EAGAIN;
498         }
499         return 0;
500 }
501
502 static void __exit ipcomp4_fini(void)
503 {
504         if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
505                 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n");
506         if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
507                 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n");
508 }
509
510 module_init(ipcomp4_init);
511 module_exit(ipcomp4_fini);
512
513 MODULE_LICENSE("GPL");
514 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
515 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
516