1 /*
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>
20 #include <linux/gfp.h>
21 #include <linux/list.h>
22 #include <linux/module.h>
23 #include <linux/mutex.h>
24 #include <linux/percpu.h>
25 #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
31 struct ipcomp_tfms {
32 struct list_head list;
33 struct crypto_comp **tfms;
34 int users;
35 };
36
37 static DEFINE_MUTEX(ipcomp_resource_mutex);
38 static void **ipcomp_scratches;
39 static int ipcomp_scratch_users;
40 static LIST_HEAD(ipcomp_tfms_list);
41
42 static 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);
52 int len;
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 len = dlen - plen;
63 if (len > skb_tailroom(skb))
64 len = skb_tailroom(skb);
65
66 __skb_put(skb, len);
67
68 len += plen;
69 skb_copy_to_linear_data(skb, scratch, len);
70
71 while ((scratch += len, dlen -= len) > 0) {
72 skb_frag_t *frag;
73
74 err = -EMSGSIZE;
75 if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
76 goto out;
77
78 frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
79 frag->page = alloc_page(GFP_ATOMIC);
80
81 err = -ENOMEM;
82 if (!frag->page)
83 goto out;
84
85 len = PAGE_SIZE;
86 if (dlen < len)
87 len = dlen;
88
89 memcpy(page_address(frag->page), scratch, len);
90
91 frag->page_offset = 0;
92 frag->size = len;
93 skb->truesize += len;
94 skb->data_len += len;
95 skb->len += len;
96
97 skb_shinfo(skb)->nr_frags++;
98 }
99
100 err = 0;
101
102 out:
103 put_cpu();
104 return err;
105 }
106
107 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
108 {
109 int nexthdr;
110 int err = -ENOMEM;
111 struct ip_comp_hdr *ipch;
112
113 if (skb_linearize_cow(skb))
114 goto out;
115
116 skb->ip_summed = CHECKSUM_NONE;
117
118 /* Remove ipcomp header and decompress original payload */
119 ipch = (void *)skb->data;
120 nexthdr = ipch->nexthdr;
121
122 skb->transport_header = skb->network_header + sizeof(*ipch);
123 __skb_pull(skb, sizeof(*ipch));
124 err = ipcomp_decompress(x, skb);
125 if (err)
126 goto out;
127
128 err = nexthdr;
129
130 out:
131 return err;
132 }
133 EXPORT_SYMBOL_GPL(ipcomp_input);
134
135 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
136 {
137 struct ipcomp_data *ipcd = x->data;
138 const int plen = skb->len;
139 int dlen = IPCOMP_SCRATCH_SIZE;
140 u8 *start = skb->data;
141 const int cpu = get_cpu();
142 u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
143 struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
144 int err;
145
146 local_bh_disable();
147 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
148 local_bh_enable();
149 if (err)
150 goto out;
151
152 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
153 err = -EMSGSIZE;
154 goto out;
155 }
156
157 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
158 put_cpu();
159
160 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
161 return 0;
162
163 out:
164 put_cpu();
165 return err;
166 }
167
168 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
169 {
170 int err;
171 struct ip_comp_hdr *ipch;
172 struct ipcomp_data *ipcd = x->data;
173
174 if (skb->len < ipcd->threshold) {
175 /* Don't bother compressing */
176 goto out_ok;
177 }
178
179 if (skb_linearize_cow(skb))
180 goto out_ok;
181
182 err = ipcomp_compress(x, skb);
183
184 if (err) {
185 goto out_ok;
186 }
187
188 /* Install ipcomp header, convert into ipcomp datagram. */
189 ipch = ip_comp_hdr(skb);
190 ipch->nexthdr = *skb_mac_header(skb);
191 ipch->flags = 0;
192 ipch->cpi = htons((u16 )ntohl(x->id.spi));
193 *skb_mac_header(skb) = IPPROTO_COMP;
194 out_ok:
195 skb_push(skb, -skb_network_offset(skb));
196 return 0;
197 }
198 EXPORT_SYMBOL_GPL(ipcomp_output);
199
200 static void ipcomp_free_scratches(void)
201 {
202 int i;
203 void **scratches;
204
205 if (--ipcomp_scratch_users)
206 return;
207
208 scratches = ipcomp_scratches;
209 if (!scratches)
210 return;
211
212 for_each_possible_cpu(i)
213 vfree(*per_cpu_ptr(scratches, i));
214
215 free_percpu(scratches);
216 }
217
218 static void **ipcomp_alloc_scratches(void)
219 {
220 int i;
221 void **scratches;
222
223 if (ipcomp_scratch_users++)
224 return ipcomp_scratches;
225
226 scratches = alloc_percpu(void *);
227 if (!scratches)
228 return NULL;
229
230 ipcomp_scratches = scratches;
231
232 for_each_possible_cpu(i) {
233 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
234 if (!scratch)
235 return NULL;
236 *per_cpu_ptr(scratches, i) = scratch;
237 }
238
239 return scratches;
240 }
241
242 static void ipcomp_free_tfms(struct crypto_comp **tfms)
243 {
244 struct ipcomp_tfms *pos;
245 int cpu;
246
247 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
248 if (pos->tfms == tfms)
249 break;
250 }
251
252 WARN_ON(!pos);
253
254 if (--pos->users)
255 return;
256
257 list_del(&pos->list);
258 kfree(pos);
259
260 if (!tfms)
261 return;
262
263 for_each_possible_cpu(cpu) {
264 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
265 crypto_free_comp(tfm);
266 }
267 free_percpu(tfms);
268 }
269
270 static struct crypto_comp **ipcomp_alloc_tfms(const char *alg_name)
271 {
272 struct ipcomp_tfms *pos;
273 struct crypto_comp **tfms;
274 int cpu;
275
276 /* This can be any valid CPU ID so we don't need locking. */
277 cpu = raw_smp_processor_id();
278
279 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
280 struct crypto_comp *tfm;
281
282 tfms = pos->tfms;
283 tfm = *per_cpu_ptr(tfms, cpu);
284
285 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
286 pos->users++;
287 return tfms;
288 }
289 }
290
291 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
292 if (!pos)
293 return NULL;
294
295 pos->users = 1;
296 INIT_LIST_HEAD(&pos->list);
297 list_add(&pos->list, &ipcomp_tfms_list);
298
299 pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
300 if (!tfms)
301 goto error;
302
303 for_each_possible_cpu(cpu) {
304 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
305 CRYPTO_ALG_ASYNC);
306 if (IS_ERR(tfm))
307 goto error;
308 *per_cpu_ptr(tfms, cpu) = tfm;
309 }
310
311 return tfms;
312
313 error:
314 ipcomp_free_tfms(tfms);
315 return NULL;
316 }
317
318 static void ipcomp_free_data(struct ipcomp_data *ipcd)
319 {
320 if (ipcd->tfms)
321 ipcomp_free_tfms(ipcd->tfms);
322 ipcomp_free_scratches();
323 }
324
325 void ipcomp_destroy(struct xfrm_state *x)
326 {
327 struct ipcomp_data *ipcd = x->data;
328 if (!ipcd)
329 return;
330 xfrm_state_delete_tunnel(x);
331 mutex_lock(&ipcomp_resource_mutex);
332 ipcomp_free_data(ipcd);
333 mutex_unlock(&ipcomp_resource_mutex);
334 kfree(ipcd);
335 }
336 EXPORT_SYMBOL_GPL(ipcomp_destroy);
337
338 int ipcomp_init_state(struct xfrm_state *x)
339 {
340 int err;
341 struct ipcomp_data *ipcd;
342 struct xfrm_algo_desc *calg_desc;
343
344 err = -EINVAL;
345 if (!x->calg)
346 goto out;
347
348 if (x->encap)
349 goto out;
350
351 err = -ENOMEM;
352 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
353 if (!ipcd)
354 goto out;
355
356 mutex_lock(&ipcomp_resource_mutex);
357 if (!ipcomp_alloc_scratches())
358 goto error;
359
360 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
361 if (!ipcd->tfms)
362 goto error;
363 mutex_unlock(&ipcomp_resource_mutex);
364
365 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
366 BUG_ON(!calg_desc);
367 ipcd->threshold = calg_desc->uinfo.comp.threshold;
368 x->data = ipcd;
369 err = 0;
370 out:
371 return err;
372
373 error:
374 ipcomp_free_data(ipcd);
375 mutex_unlock(&ipcomp_resource_mutex);
376 kfree(ipcd);
377 goto out;
378 }
379 EXPORT_SYMBOL_GPL(ipcomp_init_state);
380
381 MODULE_LICENSE("GPL");
382 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
383 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
384
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