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
27 struct ipcomp_tfms {
28 struct list_head list;
29 struct crypto_comp * __percpu *tfms;
30 int users;
31 };
32
33 static DEFINE_MUTEX(ipcomp_resource_mutex);
34 static void * __percpu *ipcomp_scratches;
35 static int ipcomp_scratch_users;
36 static LIST_HEAD(ipcomp_tfms_list);
37
38 static 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 u8 *scratch = *this_cpu_ptr(ipcomp_scratches);
45 struct crypto_comp *tfm = *this_cpu_ptr(ipcd->tfms);
46 int err = crypto_comp_decompress(tfm, start, plen, scratch, &dlen);
47 int len;
48
49 if (err)
50 return err;
51
52 if (dlen < (plen + sizeof(struct ip_comp_hdr)))
53 return -EINVAL;
54
55 len = dlen - plen;
56 if (len > skb_tailroom(skb))
57 len = skb_tailroom(skb);
58
59 __skb_put(skb, len);
60
61 len += plen;
62 skb_copy_to_linear_data(skb, scratch, len);
63
64 while ((scratch += len, dlen -= len) > 0) {
65 skb_frag_t *frag;
66 struct page *page;
67
68 if (WARN_ON(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS))
69 return -EMSGSIZE;
70
71 frag = skb_shinfo(skb)->frags + skb_shinfo(skb)->nr_frags;
72 page = alloc_page(GFP_ATOMIC);
73
74 if (!page)
75 return -ENOMEM;
76
77 len = PAGE_SIZE;
78 if (dlen < len)
79 len = dlen;
80
81 skb_frag_fill_page_desc(frag, page, 0, len);
82 memcpy(skb_frag_address(frag), scratch, len);
83
84 skb->truesize += len;
85 skb->data_len += len;
86 skb->len += len;
87
88 skb_shinfo(skb)->nr_frags++;
89 }
90
91 return 0;
92 }
93
94 int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
95 {
96 int nexthdr;
97 int err = -ENOMEM;
98 struct ip_comp_hdr *ipch;
99
100 if (skb_linearize_cow(skb))
101 goto out;
102
103 skb->ip_summed = CHECKSUM_NONE;
104
105 /* Remove ipcomp header and decompress original payload */
106 ipch = (void *)skb->data;
107 nexthdr = ipch->nexthdr;
108
109 skb->transport_header = skb->network_header + sizeof(*ipch);
110 __skb_pull(skb, sizeof(*ipch));
111 err = ipcomp_decompress(x, skb);
112 if (err)
113 goto out;
114
115 err = nexthdr;
116
117 out:
118 return err;
119 }
120 EXPORT_SYMBOL_GPL(ipcomp_input);
121
122 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
123 {
124 struct ipcomp_data *ipcd = x->data;
125 const int plen = skb->len;
126 int dlen = IPCOMP_SCRATCH_SIZE;
127 u8 *start = skb->data;
128 struct crypto_comp *tfm;
129 u8 *scratch;
130 int err;
131
132 local_bh_disable();
133 scratch = *this_cpu_ptr(ipcomp_scratches);
134 tfm = *this_cpu_ptr(ipcd->tfms);
135 err = crypto_comp_compress(tfm, start, plen, scratch, &dlen);
136 if (err)
137 goto out;
138
139 if ((dlen + sizeof(struct ip_comp_hdr)) >= plen) {
140 err = -EMSGSIZE;
141 goto out;
142 }
143
144 memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
145 local_bh_enable();
146
147 pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
148 return 0;
149
150 out:
151 local_bh_enable();
152 return err;
153 }
154
155 int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
156 {
157 int err;
158 struct ip_comp_hdr *ipch;
159 struct ipcomp_data *ipcd = x->data;
160
161 if (skb->len < ipcd->threshold) {
162 /* Don't bother compressing */
163 goto out_ok;
164 }
165
166 if (skb_linearize_cow(skb))
167 goto out_ok;
168
169 err = ipcomp_compress(x, skb);
170
171 if (err) {
172 goto out_ok;
173 }
174
175 /* Install ipcomp header, convert into ipcomp datagram. */
176 ipch = ip_comp_hdr(skb);
177 ipch->nexthdr = *skb_mac_header(skb);
178 ipch->flags = 0;
179 ipch->cpi = htons((u16 )ntohl(x->id.spi));
180 *skb_mac_header(skb) = IPPROTO_COMP;
181 out_ok:
182 skb_push(skb, -skb_network_offset(skb));
183 return 0;
184 }
185 EXPORT_SYMBOL_GPL(ipcomp_output);
186
187 static void ipcomp_free_scratches(void)
188 {
189 int i;
190 void * __percpu *scratches;
191
192 if (--ipcomp_scratch_users)
193 return;
194
195 scratches = ipcomp_scratches;
196 if (!scratches)
197 return;
198
199 for_each_possible_cpu(i)
200 vfree(*per_cpu_ptr(scratches, i));
201
202 free_percpu(scratches);
203 ipcomp_scratches = NULL;
204 }
205
206 static void * __percpu *ipcomp_alloc_scratches(void)
207 {
208 void * __percpu *scratches;
209 int i;
210
211 if (ipcomp_scratch_users++)
212 return ipcomp_scratches;
213
214 scratches = alloc_percpu(void *);
215 if (!scratches)
216 return NULL;
217
218 ipcomp_scratches = scratches;
219
220 for_each_possible_cpu(i) {
221 void *scratch;
222
223 scratch = vmalloc_node(IPCOMP_SCRATCH_SIZE, cpu_to_node(i));
224 if (!scratch)
225 return NULL;
226 *per_cpu_ptr(scratches, i) = scratch;
227 }
228
229 return scratches;
230 }
231
232 static void ipcomp_free_tfms(struct crypto_comp * __percpu *tfms)
233 {
234 struct ipcomp_tfms *pos;
235 int cpu;
236
237 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
238 if (pos->tfms == tfms)
239 break;
240 }
241
242 WARN_ON(list_entry_is_head(pos, &ipcomp_tfms_list, list));
243
244 if (--pos->users)
245 return;
246
247 list_del(&pos->list);
248 kfree(pos);
249
250 if (!tfms)
251 return;
252
253 for_each_possible_cpu(cpu) {
254 struct crypto_comp *tfm = *per_cpu_ptr(tfms, cpu);
255 crypto_free_comp(tfm);
256 }
257 free_percpu(tfms);
258 }
259
260 static struct crypto_comp * __percpu *ipcomp_alloc_tfms(const char *alg_name)
261 {
262 struct ipcomp_tfms *pos;
263 struct crypto_comp * __percpu *tfms;
264 int cpu;
265
266
267 list_for_each_entry(pos, &ipcomp_tfms_list, list) {
268 struct crypto_comp *tfm;
269
270 /* This can be any valid CPU ID so we don't need locking. */
271 tfm = this_cpu_read(*pos->tfms);
272
273 if (!strcmp(crypto_comp_name(tfm), alg_name)) {
274 pos->users++;
275 return pos->tfms;
276 }
277 }
278
279 pos = kmalloc(sizeof(*pos), GFP_KERNEL);
280 if (!pos)
281 return NULL;
282
283 pos->users = 1;
284 INIT_LIST_HEAD(&pos->list);
285 list_add(&pos->list, &ipcomp_tfms_list);
286
287 pos->tfms = tfms = alloc_percpu(struct crypto_comp *);
288 if (!tfms)
289 goto error;
290
291 for_each_possible_cpu(cpu) {
292 struct crypto_comp *tfm = crypto_alloc_comp(alg_name, 0,
293 CRYPTO_ALG_ASYNC);
294 if (IS_ERR(tfm))
295 goto error;
296 *per_cpu_ptr(tfms, cpu) = tfm;
297 }
298
299 return tfms;
300
301 error:
302 ipcomp_free_tfms(tfms);
303 return NULL;
304 }
305
306 static void ipcomp_free_data(struct ipcomp_data *ipcd)
307 {
308 if (ipcd->tfms)
309 ipcomp_free_tfms(ipcd->tfms);
310 ipcomp_free_scratches();
311 }
312
313 void ipcomp_destroy(struct xfrm_state *x)
314 {
315 struct ipcomp_data *ipcd = x->data;
316 if (!ipcd)
317 return;
318 xfrm_state_delete_tunnel(x);
319 mutex_lock(&ipcomp_resource_mutex);
320 ipcomp_free_data(ipcd);
321 mutex_unlock(&ipcomp_resource_mutex);
322 kfree(ipcd);
323 }
324 EXPORT_SYMBOL_GPL(ipcomp_destroy);
325
326 int ipcomp_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
327 {
328 int err;
329 struct ipcomp_data *ipcd;
330 struct xfrm_algo_desc *calg_desc;
331
332 err = -EINVAL;
333 if (!x->calg) {
334 NL_SET_ERR_MSG(extack, "Missing required compression algorithm");
335 goto out;
336 }
337
338 if (x->encap) {
339 NL_SET_ERR_MSG(extack, "IPComp is not compatible with encapsulation");
340 goto out;
341 }
342
343 err = -ENOMEM;
344 ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
345 if (!ipcd)
346 goto out;
347
348 mutex_lock(&ipcomp_resource_mutex);
349 if (!ipcomp_alloc_scratches())
350 goto error;
351
352 ipcd->tfms = ipcomp_alloc_tfms(x->calg->alg_name);
353 if (!ipcd->tfms)
354 goto error;
355 mutex_unlock(&ipcomp_resource_mutex);
356
357 calg_desc = xfrm_calg_get_byname(x->calg->alg_name, 0);
358 BUG_ON(!calg_desc);
359 ipcd->threshold = calg_desc->uinfo.comp.threshold;
360 x->data = ipcd;
361 err = 0;
362 out:
363 return err;
364
365 error:
366 ipcomp_free_data(ipcd);
367 mutex_unlock(&ipcomp_resource_mutex);
368 kfree(ipcd);
369 goto out;
370 }
371 EXPORT_SYMBOL_GPL(ipcomp_init_state);
372
373 MODULE_LICENSE("GPL");
374 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) - RFC3173");
375 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
376
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.