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Linux/net/xfrm/xfrm_ipcomp.c

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  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/list.h>
 21 #include <linux/module.h>
 22 #include <linux/mutex.h>
 23 #include <linux/percpu.h>
 24 #include <linux/slab.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 * __percpu *tfms;
 34         int users;
 35 };
 36 
 37 static DEFINE_MUTEX(ipcomp_resource_mutex);
 38 static void * __percpu *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                 struct page *page;
 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                 page = alloc_page(GFP_ATOMIC);
 81 
 82                 err = -ENOMEM;
 83                 if (!page)
 84                         goto out;
 85 
 86                 __skb_frag_set_page(frag, page);
 87 
 88                 len = PAGE_SIZE;
 89                 if (dlen < len)
 90                         len = dlen;
 91 
 92                 frag->page_offset = 0;
 93                 skb_frag_size_set(frag, len);
 94                 memcpy(skb_frag_address(frag), scratch, len);
 95 
 96                 skb->truesize += len;
 97                 skb->data_len += len;
 98                 skb->len += len;
 99 
100                 skb_shinfo(skb)->nr_frags++;
101         }
102 
103         err = 0;
104 
105 out:
106         put_cpu();
107         return err;
108 }
109 
110 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
111 {
112         int nexthdr;
113         int err = -ENOMEM;
114         struct ip_comp_hdr *ipch;
115 
116         if (skb_linearize_cow(skb))
117                 goto out;
118 
119         skb->ip_summed = CHECKSUM_NONE;
120 
121         /* Remove ipcomp header and decompress original payload */
122         ipch = (void *)skb->data;
123         nexthdr = ipch->nexthdr;
124 
125         skb->transport_header = skb->network_header + sizeof(*ipch);
126         __skb_pull(skb, sizeof(*ipch));
127         err = ipcomp_decompress(x, skb);
128         if (err)
129                 goto out;
130 
131         err = nexthdr;
132 
133 out:
134         return err;
135 }
136 EXPORT_SYMBOL_GPL(ipcomp_input);
137 
138 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
139 {
140         struct ipcomp_data *ipcd = x->data;
141         const int plen = skb->len;
142         int dlen = IPCOMP_SCRATCH_SIZE;
143         u8 *start = skb->data;
144         const int cpu = get_cpu();
145         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
146         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
147         int err;
148 
149         local_bh_disable();
150         err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
151         local_bh_enable();
152         if (err)
153                 goto out;
154 
155         if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
156                 err = -EMSGSIZE;
157                 goto out;
158         }
159 
160         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
161         put_cpu();
162 
163         pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
164         return 0;
165 
166 out:
167         put_cpu();
168         return err;
169 }
170 
171 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
172 {
173         int err;
174         struct ip_comp_hdr *ipch;
175         struct ipcomp_data *ipcd = x->data;
176 
177         if (skb->len < ipcd->threshold) {
178                 /* Don't bother compressing */
179                 goto out_ok;
180         }
181 
182         if (skb_linearize_cow(skb))
183                 goto out_ok;
184 
185         err = ipcomp_compress(x, skb);
186 
187         if (err) {
188                 goto out_ok;
189         }
190 
191         /* Install ipcomp header, convert into ipcomp datagram. */
192         ipch = ip_comp_hdr(skb);
193         ipch->nexthdr = *skb_mac_header(skb);
194         ipch->flags = 0;
195         ipch->cpi = htons((u16 )ntohl(x->id.spi));
196         *skb_mac_header(skb) = IPPROTO_COMP;
197 out_ok:
198         skb_push(skb, -skb_network_offset(skb));
199         return 0;
200 }
201 EXPORT_SYMBOL_GPL(ipcomp_output);
202 
203 static void ipcomp_free_scratches(void)
204 {
205         int i;
206         void * __percpu *scratches;
207 
208         if (--ipcomp_scratch_users)
209                 return;
210 
211         scratches = ipcomp_scratches;
212         if (!scratches)
213                 return;
214 
215         for_each_possible_cpu(i)
216                 vfree(*per_cpu_ptr(scratches, i));
217 
218         free_percpu(scratches);
219 }
220 
221 static void * __percpu *ipcomp_alloc_scratches(void)
222 {
223         int i;
224         void * __percpu *scratches;
225 
226         if (ipcomp_scratch_users++)
227                 return ipcomp_scratches;
228 
229         scratches = alloc_percpu(void *);
230         if (!scratches)
231                 return NULL;
232 
233         ipcomp_scratches = scratches;
234 
235         for_each_possible_cpu(i) {
236                 void *scratch = vmalloc(IPCOMP_SCRATCH_SIZE);
237                 if (!scratch)
238                         return NULL;
239                 *per_cpu_ptr(scratches, i) = scratch;
240         }
241 
242         return scratches;
243 }
244 
245 static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
246 {
247         struct ipcomp_tfms *pos;
248         int cpu;
249 
250         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
251                 if (pos->tfms == tfms)
252                         break;
253         }
254 
255         WARN_ON(!pos);
256 
257         if (--pos->users)
258                 return;
259 
260         list_del(&pos->list);
261         kfree(pos);
262 
263         if (!tfms)
264                 return;
265 
266         for_each_possible_cpu(cpu) {
267                 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
268                 crypto_free_comp(tfm);
269         }
270         free_percpu(tfms);
271 }
272 
273 static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
274 {
275         struct ipcomp_tfms *pos;
276         struct crypto_comp * __percpu *tfms;
277         int cpu;
278 
279 
280         list_for_each_entry(pos, &ipcomp_tfms_list, list) {
281                 struct crypto_comp *tfm;
282 
283                 /* This can be any valid CPU ID so we don't need locking. */
284                 tfm = __this_cpu_read(*pos->tfms);
285 
286                 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
287                         pos->users++;
288                         return pos->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 
314 error:
315         ipcomp_free_tfms(tfms);
316         return NULL;
317 }
318 
319 static 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 
326 void 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 }
337 EXPORT_SYMBOL_GPL(ipcomp_destroy);
338 
339 int 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;
371 out:
372         return err;
373 
374 error:
375         ipcomp_free_data(ipcd);
376         mutex_unlock(&ipcomp_resource_mutex);
377         kfree(ipcd);
378         goto out;
379 }
380 EXPORT_SYMBOL_GPL(ipcomp_init_state);
381 
382 MODULE_LICENSE("GPL");
383 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
384 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
385 

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