xref: /openbmc/linux/net/xfrm/xfrm_ipcomp.c (revision b6dcefde)
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