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