xref: /kernel/linux/linux-5.10/net/xfrm/xfrm_ipcomp.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IP Payload Compression Protocol (IPComp) - RFC3173.
4 *
5 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
6 * Copyright (c) 2003-2008 Herbert Xu <herbert@gondor.apana.org.au>
7 *
8 * Todo:
9 *   - Tunable compression parameters.
10 *   - Compression stats.
11 *   - Adaptive compression.
12 */
13
14#include <linux/crypto.h>
15#include <linux/err.h>
16#include <linux/list.h>
17#include <linux/module.h>
18#include <linux/mutex.h>
19#include <linux/percpu.h>
20#include <linux/slab.h>
21#include <linux/smp.h>
22#include <linux/vmalloc.h>
23#include <net/ip.h>
24#include <net/ipcomp.h>
25#include <net/xfrm.h>
26
27struct ipcomp_tfms {
28	struct list_head list;
29	struct crypto_comp * __percpu *tfms;
30	int users;
31};
32
33static DEFINE_MUTEX(ipcomp_resource_mutex);
34static void * __percpu *ipcomp_scratches;
35static int ipcomp_scratch_users;
36static LIST_HEAD(ipcomp_tfms_list);
37
38static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
39{
40	struct ipcomp_data *ipcd = x->data;
41	const int plen = skb->len;
42	int dlen = IPCOMP_SCRATCH_SIZE;
43	const u8 *start = skb->data;
44	const int cpu = get_cpu();
45	u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
46	struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
47	int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
48	int len;
49
50	if (err)
51		goto out;
52
53	if (dlen < (plen + sizeof(struct ip_comp_hdr))) {
54		err = -EINVAL;
55		goto out;
56	}
57
58	len = dlen - plen;
59	if (len > skb_tailroom(skb))
60		len = skb_tailroom(skb);
61
62	__skb_put(skb, len);
63
64	len += plen;
65	skb_copy_to_linear_data(skb, scratch, len);
66
67	while ((scratch += len, dlen -= len) > 0) {
68		skb_frag_t *frag;
69		struct page *page;
70
71		err = -EMSGSIZE;
72		if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
73			goto out;
74
75		frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
76		page = alloc_page(GFP_ATOMIC);
77
78		err = -ENOMEM;
79		if (!page)
80			goto out;
81
82		__skb_frag_set_page(frag, page);
83
84		len = PAGE_SIZE;
85		if (dlen < len)
86			len = dlen;
87
88		skb_frag_off_set(frag, 0);
89		skb_frag_size_set(frag, len);
90		memcpy(skb_frag_address(frag), scratch, len);
91
92		skb->truesize += len;
93		skb->data_len += len;
94		skb->len += len;
95
96		skb_shinfo(skb)->nr_frags++;
97	}
98
99	err = 0;
100
101out:
102	put_cpu();
103	return err;
104}
105
106int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
107{
108	int nexthdr;
109	int err = -ENOMEM;
110	struct ip_comp_hdr *ipch;
111
112	if (skb_linearize_cow(skb))
113		goto out;
114
115	skb->ip_summed = CHECKSUM_NONE;
116
117	/* Remove ipcomp header and decompress original payload */
118	ipch = (void *)skb->data;
119	nexthdr = ipch->nexthdr;
120
121	skb->transport_header = skb->network_header + sizeof(*ipch);
122	__skb_pull(skb, sizeof(*ipch));
123	err = ipcomp_decompress(x, skb);
124	if (err)
125		goto out;
126
127	err = nexthdr;
128
129out:
130	return err;
131}
132EXPORT_SYMBOL_GPL(ipcomp_input);
133
134static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
135{
136	struct ipcomp_data *ipcd = x->data;
137	const int plen = skb->len;
138	int dlen = IPCOMP_SCRATCH_SIZE;
139	u8 *start = skb->data;
140	struct crypto_comp *tfm;
141	u8 *scratch;
142	int err;
143
144	local_bh_disable();
145	scratch = *this_cpu_ptr(ipcomp_scratches);
146	tfm = *this_cpu_ptr(ipcd->tfms);
147	err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
148	if (err)
149		goto out;
150
151	if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
152		err = -EMSGSIZE;
153		goto out;
154	}
155
156	memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
157	local_bh_enable();
158
159	pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
160	return 0;
161
162out:
163	local_bh_enable();
164	return err;
165}
166
167int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
168{
169	int err;
170	struct ip_comp_hdr *ipch;
171	struct ipcomp_data *ipcd = x->data;
172
173	if (skb->len < ipcd->threshold) {
174		/* Don't bother compressing */
175		goto out_ok;
176	}
177
178	if (skb_linearize_cow(skb))
179		goto out_ok;
180
181	err = ipcomp_compress(x, skb);
182
183	if (err) {
184		goto out_ok;
185	}
186
187	/* Install ipcomp header, convert into ipcomp datagram. */
188	ipch = ip_comp_hdr(skb);
189	ipch->nexthdr = *skb_mac_header(skb);
190	ipch->flags = 0;
191	ipch->cpi = htons((u16 )ntohl(x->id.spi));
192	*skb_mac_header(skb) = IPPROTO_COMP;
193out_ok:
194	skb_push(skb, -skb_network_offset(skb));
195	return 0;
196}
197EXPORT_SYMBOL_GPL(ipcomp_output);
198
199static void ipcomp_free_scratches(void)
200{
201	int i;
202	void * __percpu *scratches;
203
204	if (--ipcomp_scratch_users)
205		return;
206
207	scratches = ipcomp_scratches;
208	if (!scratches)
209		return;
210
211	for_each_possible_cpu(i)
212		vfree(*per_cpu_ptr(scratches, i));
213
214	free_percpu(scratches);
215	ipcomp_scratches = NULL;
216}
217
218static void * __percpu *ipcomp_alloc_scratches(void)
219{
220	void * __percpu *scratches;
221	int i;
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;
234
235		scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
236		if (!scratch)
237			return NULL;
238		*per_cpu_ptr(scratches, i) = scratch;
239	}
240
241	return scratches;
242}
243
244static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
245{
246	struct ipcomp_tfms *pos;
247	int cpu;
248
249	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
250		if (pos->tfms == tfms)
251			break;
252	}
253
254	WARN_ON(list_entry_is_head(pos, &ipcomp_tfms_list, list));
255
256	if (--pos->users)
257		return;
258
259	list_del(&pos->list);
260	kfree(pos);
261
262	if (!tfms)
263		return;
264
265	for_each_possible_cpu(cpu) {
266		struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
267		crypto_free_comp(tfm);
268	}
269	free_percpu(tfms);
270}
271
272static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
273{
274	struct ipcomp_tfms *pos;
275	struct crypto_comp * __percpu *tfms;
276	int cpu;
277
278
279	list_for_each_entry(pos, &ipcomp_tfms_list, list) {
280		struct crypto_comp *tfm;
281
282		/* This can be any valid CPU ID so we don't need locking. */
283		tfm = this_cpu_read(*pos->tfms);
284
285		if (!strcmp(crypto_comp_name(tfm), alg_name)) {
286			pos->users++;
287			return pos->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
313error:
314	ipcomp_free_tfms(tfms);
315	return NULL;
316}
317
318static 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
325void 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}
336EXPORT_SYMBOL_GPL(ipcomp_destroy);
337
338int 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;
370out:
371	return err;
372
373error:
374	ipcomp_free_data(ipcd);
375	mutex_unlock(&ipcomp_resource_mutex);
376	kfree(ipcd);
377	goto out;
378}
379EXPORT_SYMBOL_GPL(ipcomp_init_state);
380
381MODULE_LICENSE("GPL");
382MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
383MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
384