blob: c609a4b98e15f9b730701a15e9292fbaffd3000c [file] [log] [blame]
Herbert Xu6fccab62008-07-25 02:54:40 -07001/*
2 * IP Payload Compression Protocol (IPComp) - RFC3173.
3 *
4 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
5 * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au>
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the Free
9 * Software Foundation; either version 2 of the License, or (at your option)
10 * any later version.
11 *
12 * Todo:
13 * - Tunable compression parameters.
14 * - Compression stats.
15 * - Adaptive compression.
16 */
17
18#include <linux/crypto.h>
19#include <linux/err.h>
Herbert Xu7d7e5a62008-07-25 02:55:33 -070020#include <linux/gfp.h>
Herbert Xu6fccab62008-07-25 02:54:40 -070021#include <linux/list.h>
22#include <linux/module.h>
23#include <linux/mutex.h>
24#include <linux/percpu.h>
Herbert Xu6fccab62008-07-25 02:54:40 -070025#include <linux/smp.h>
26#include <linux/vmalloc.h>
27#include <net/ip.h>
28#include <net/ipcomp.h>
29#include <net/xfrm.h>
30
31struct ipcomp_tfms {
32 struct list_head list;
33 struct crypto_comp **tfms;
34 int users;
35};
36
37static DEFINE_MUTEX(ipcomp_resource_mutex);
38static void **ipcomp_scratches;
39static int ipcomp_scratch_users;
40static LIST_HEAD(ipcomp_tfms_list);
41
42static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
43{
44 struct ipcomp_data *ipcd = x->data;
45 const int plen = skb->len;
46 int dlen = IPCOMP_SCRATCH_SIZE;
47 const u8 *start = skb->data;
48 const int cpu = get_cpu();
49 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
50 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
51 int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
Herbert Xu7d7e5a62008-07-25 02:55:33 -070052 int len;
Herbert Xu6fccab62008-07-25 02:54:40 -070053
54 if (err)
55 goto out;
56
57 if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
58 err = -EINVAL;
59 goto out;
60 }
61
Herbert Xu7d7e5a62008-07-25 02:55:33 -070062 len = dlen - plen;
63 if (len > skb_tailroom(skb))
64 len = skb_tailroom(skb);
Herbert Xu6fccab62008-07-25 02:54:40 -070065
Herbert Xu7d7e5a62008-07-25 02:55:33 -070066 skb->truesize += len;
67 __skb_put(skb, len);
68
69 len += plen;
70 skb_copy_to_linear_data(skb, scratch, len);
71
72 while ((scratch += len, dlen -= len) > 0) {
73 skb_frag_t *frag;
74
75 err = -EMSGSIZE;
76 if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
77 goto out;
78
79 frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
80 frag->page = alloc_page(GFP_ATOMIC);
81
82 err = -ENOMEM;
83 if (!frag->page)
84 goto out;
85
86 len = PAGE_SIZE;
87 if (dlen < len)
88 len = dlen;
89
90 memcpy(page_address(frag->page), scratch, len);
91
92 frag->page_offset = 0;
93 frag->size = len;
94 skb->truesize += len;
95 skb->data_len += len;
96 skb->len += len;
97
98 skb_shinfo(skb)->nr_frags++;
99 }
100
101 err = 0;
102
Herbert Xu6fccab62008-07-25 02:54:40 -0700103out:
104 put_cpu();
105 return err;
106}
107
108int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
109{
110 int nexthdr;
111 int err = -ENOMEM;
112 struct ip_comp_hdr *ipch;
113
114 if (skb_linearize_cow(skb))
115 goto out;
116
117 skb->ip_summed = CHECKSUM_NONE;
118
119 /* Remove ipcomp header and decompress original payload */
120 ipch = (void *)skb->data;
121 nexthdr = ipch->nexthdr;
122
123 skb->transport_header = skb->network_header + sizeof(*ipch);
124 __skb_pull(skb, sizeof(*ipch));
125 err = ipcomp_decompress(x, skb);
126 if (err)
127 goto out;
128
129 err = nexthdr;
130
131out:
132 return err;
133}
134EXPORT_SYMBOL_GPL(ipcomp_input);
135
136static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
137{
138 struct ipcomp_data *ipcd = x->data;
139 const int plen = skb->len;
140 int dlen = IPCOMP_SCRATCH_SIZE;
141 u8 *start = skb->data;
142 const int cpu = get_cpu();
143 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
144 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
145 int err;
146
147 local_bh_disable();
148 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
149 local_bh_enable();
150 if (err)
151 goto out;
152
153 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
154 err = -EMSGSIZE;
155 goto out;
156 }
157
158 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
159 put_cpu();
160
161 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
162 return 0;
163
164out:
165 put_cpu();
166 return err;
167}
168
169int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
170{
171 int err;
172 struct ip_comp_hdr *ipch;
173 struct ipcomp_data *ipcd = x->data;
174
175 if (skb->len < ipcd->threshold) {
176 /* Don't bother compressing */
177 goto out_ok;
178 }
179
180 if (skb_linearize_cow(skb))
181 goto out_ok;
182
183 err = ipcomp_compress(x, skb);
184
185 if (err) {
186 goto out_ok;
187 }
188
189 /* Install ipcomp header, convert into ipcomp datagram. */
190 ipch = ip_comp_hdr(skb);
191 ipch->nexthdr = *skb_mac_header(skb);
192 ipch->flags = 0;
193 ipch->cpi = htons((u16 )ntohl(x->id.spi));
194 *skb_mac_header(skb) = IPPROTO_COMP;
195out_ok:
196 skb_push(skb, -skb_network_offset(skb));
197 return 0;
198}
199EXPORT_SYMBOL_GPL(ipcomp_output);
200
201static void ipcomp_free_scratches(void)
202{
203 int i;
204 void **scratches;
205
206 if (--ipcomp_scratch_users)
207 return;
208
209 scratches = ipcomp_scratches;
210 if (!scratches)
211 return;
212
213 for_each_possible_cpu(i)
214 vfree(*per_cpu_ptr(scratches, i));
215
216 free_percpu(scratches);
217}
218
219static void **ipcomp_alloc_scratches(void)
220{
221 int i;
222 void **scratches;
223
224 if (ipcomp_scratch_users++)
225 return ipcomp_scratches;
226
227 scratches = alloc_percpu(void *);
228 if (!scratches)
229 return NULL;
230
231 ipcomp_scratches = scratches;
232
233 for_each_possible_cpu(i) {
234 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
235 if (!scratch)
236 return NULL;
237 *per_cpu_ptr(scratches, i) = scratch;
238 }
239
240 return scratches;
241}
242
243static void ipcomp_free_tfms(struct crypto_comp **tfms)
244{
245 struct ipcomp_tfms *pos;
246 int cpu;
247
248 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
249 if (pos->tfms == tfms)
250 break;
251 }
252
Ilpo Järvinen547b7922008-07-25 21:43:18 -0700253 WARN_ON(!pos);
Herbert Xu6fccab62008-07-25 02:54:40 -0700254
255 if (--pos->users)
256 return;
257
258 list_del(&pos->list);
259 kfree(pos);
260
261 if (!tfms)
262 return;
263
264 for_each_possible_cpu(cpu) {
265 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
266 crypto_free_comp(tfm);
267 }
268 free_percpu(tfms);
269}
270
271static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
272{
273 struct ipcomp_tfms *pos;
274 struct crypto_comp **tfms;
275 int cpu;
276
277 /* This can be any valid CPU ID so we don't need locking. */
278 cpu = raw_smp_processor_id();
279
280 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
281 struct crypto_comp *tfm;
282
283 tfms = pos->tfms;
284 tfm = *per_cpu_ptr(tfms, cpu);
285
286 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
287 pos->users++;
288 return tfms;
289 }
290 }
291
292 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
293 if (!pos)
294 return NULL;
295
296 pos->users = 1;
297 INIT_LIST_HEAD(&pos->list);
298 list_add(&pos->list, &ipcomp_tfms_list);
299
300 pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
301 if (!tfms)
302 goto error;
303
304 for_each_possible_cpu(cpu) {
305 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
306 CRYPTO_ALG_ASYNC);
307 if (IS_ERR(tfm))
308 goto error;
309 *per_cpu_ptr(tfms, cpu) = tfm;
310 }
311
312 return tfms;
313
314error:
315 ipcomp_free_tfms(tfms);
316 return NULL;
317}
318
319static void ipcomp_free_data(struct ipcomp_data *ipcd)
320{
321 if (ipcd->tfms)
322 ipcomp_free_tfms(ipcd->tfms);
323 ipcomp_free_scratches();
324}
325
326void ipcomp_destroy(struct xfrm_state *x)
327{
328 struct ipcomp_data *ipcd = x->data;
329 if (!ipcd)
330 return;
331 xfrm_state_delete_tunnel(x);
332 mutex_lock(&ipcomp_resource_mutex);
333 ipcomp_free_data(ipcd);
334 mutex_unlock(&ipcomp_resource_mutex);
335 kfree(ipcd);
336}
337EXPORT_SYMBOL_GPL(ipcomp_destroy);
338
339int ipcomp_init_state(struct xfrm_state *x)
340{
341 int err;
342 struct ipcomp_data *ipcd;
343 struct xfrm_algo_desc *calg_desc;
344
345 err = -EINVAL;
346 if (!x->calg)
347 goto out;
348
349 if (x->encap)
350 goto out;
351
352 err = -ENOMEM;
353 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
354 if (!ipcd)
355 goto out;
356
357 mutex_lock(&ipcomp_resource_mutex);
358 if (!ipcomp_alloc_scratches())
359 goto error;
360
361 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
362 if (!ipcd->tfms)
363 goto error;
364 mutex_unlock(&ipcomp_resource_mutex);
365
366 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
367 BUG_ON(!calg_desc);
368 ipcd->threshold = calg_desc->uinfo.comp.threshold;
369 x->data = ipcd;
370 err = 0;
371out:
372 return err;
373
374error:
375 ipcomp_free_data(ipcd);
376 mutex_unlock(&ipcomp_resource_mutex);
377 kfree(ipcd);
378 goto out;
379}
380EXPORT_SYMBOL_GPL(ipcomp_init_state);
381
382MODULE_LICENSE("GPL");
383MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
384MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");