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gerrit-public.fairphone.software / fp2-dev / kernel / msm / fef1c772fa154c16e0a54577e9ecb5480f7b937e / . / crypto / cipher.c
blob: f434ce7c2d0b372aa75b3c4d8d2ac1b333e2f4e2 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/*
2 * Cryptographic API.
3 *
4 * Cipher operations.
5 *
6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2 of the License, or (at your option)
11 * any later version.
12 *
13 */
14#include <linux/compiler.h>
15#include <linux/kernel.h>
16#include <linux/crypto.h>
17#include <linux/errno.h>
18#include <linux/mm.h>
19#include <linux/slab.h>
20#include <linux/string.h>
21#include <asm/scatterlist.h>
22#include "internal.h"
23#include "scatterwalk.h"
24
25typedef void (cryptfn_t)(void *, u8 *, const u8 *);
26typedef void (procfn_t)(struct crypto_tfm *, u8 *,
27 u8*, cryptfn_t, void *);
28
29static inline void xor_64(u8 *a, const u8 *b)
30{
31 ((u32 *)a)[0] ^= ((u32 *)b)[0];
32 ((u32 *)a)[1] ^= ((u32 *)b)[1];
33}
34
35static inline void xor_128(u8 *a, const u8 *b)
36{
37 ((u32 *)a)[0] ^= ((u32 *)b)[0];
38 ((u32 *)a)[1] ^= ((u32 *)b)[1];
39 ((u32 *)a)[2] ^= ((u32 *)b)[2];
40 ((u32 *)a)[3] ^= ((u32 *)b)[3];
41}
42
43static inline void *prepare_src(struct scatter_walk *walk, int bsize,
44 void *tmp, int in_place)
45{
46 void *src = walk->data;
47 int n = bsize;
48
49 if (unlikely(scatterwalk_across_pages(walk, bsize))) {
50 src = tmp;
51 n = scatterwalk_copychunks(src, walk, bsize, 0);
52 }
53 scatterwalk_advance(walk, n);
54 return src;
55}
56
57static inline void *prepare_dst(struct scatter_walk *walk, int bsize,
58 void *tmp, int in_place)
59{
60 void *dst = walk->data;
61
62 if (unlikely(scatterwalk_across_pages(walk, bsize)) || in_place)
63 dst = tmp;
64 return dst;
65}
66
67static inline void complete_src(struct scatter_walk *walk, int bsize,
68 void *src, int in_place)
69{
70}
71
72static inline void complete_dst(struct scatter_walk *walk, int bsize,
73 void *dst, int in_place)
74{
75 int n = bsize;
76
77 if (unlikely(scatterwalk_across_pages(walk, bsize)))
78 n = scatterwalk_copychunks(dst, walk, bsize, 1);
79 else if (in_place)
80 memcpy(walk->data, dst, bsize);
81 scatterwalk_advance(walk, n);
82}
83
84/*
85 * Generic encrypt/decrypt wrapper for ciphers, handles operations across
86 * multiple page boundaries by using temporary blocks. In user context,
87 * the kernel is given a chance to schedule us once per block.
88 */
89static int crypt(struct crypto_tfm *tfm,
90 struct scatterlist *dst,
91 struct scatterlist *src,
92 unsigned int nbytes, cryptfn_t crfn,
93 procfn_t prfn, void *info)
94{
95 struct scatter_walk walk_in, walk_out;
96 const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
97 u8 tmp_src[bsize];
98 u8 tmp_dst[bsize];
99
100 if (!nbytes)
101 return 0;
102
103 if (nbytes % bsize) {
104 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
105 return -EINVAL;
106 }
107
108 scatterwalk_start(&walk_in, src);
109 scatterwalk_start(&walk_out, dst);
110
111 for(;;) {
112 u8 *src_p, *dst_p;
113 int in_place;
114
115 scatterwalk_map(&walk_in, 0);
116 scatterwalk_map(&walk_out, 1);
117
118 in_place = scatterwalk_samebuf(&walk_in, &walk_out);
119
120 do {
121 src_p = prepare_src(&walk_in, bsize, tmp_src,
122 in_place);
123 dst_p = prepare_dst(&walk_out, bsize, tmp_dst,
124 in_place);
125
126 prfn(tfm, dst_p, src_p, crfn, info);
127
128 complete_src(&walk_in, bsize, src_p, in_place);
129 complete_dst(&walk_out, bsize, dst_p, in_place);
130
131 nbytes -= bsize;
132 } while (nbytes &&
133 !scatterwalk_across_pages(&walk_in, bsize) &&
134 !scatterwalk_across_pages(&walk_out, bsize));
135
136 scatterwalk_done(&walk_in, 0, nbytes);
137 scatterwalk_done(&walk_out, 1, nbytes);
138
139 if (!nbytes)
140 return 0;
141
142 crypto_yield(tfm);
143 }
144}
145
146static void cbc_process_encrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
147 cryptfn_t fn, void *info)
148{
149 u8 *iv = info;
150
151 tfm->crt_u.cipher.cit_xor_block(iv, src);
152 fn(crypto_tfm_ctx(tfm), dst, iv);
153 memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
154}
155
156static void cbc_process_decrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
157 cryptfn_t fn, void *info)
158{
159 u8 *iv = info;
160
161 fn(crypto_tfm_ctx(tfm), dst, src);
162 tfm->crt_u.cipher.cit_xor_block(dst, iv);
163 memcpy(iv, src, crypto_tfm_alg_blocksize(tfm));
164}
165
166static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
167 cryptfn_t fn, void *info)
168{
169 fn(crypto_tfm_ctx(tfm), dst, src);
170}
171
172static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
173{
174 struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
175
176 if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
177 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
178 return -EINVAL;
179 } else
180 return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
181 &tfm->crt_flags);
182}
183
184static int ecb_encrypt(struct crypto_tfm *tfm,
185 struct scatterlist *dst,
186 struct scatterlist *src, unsigned int nbytes)
187{
188 return crypt(tfm, dst, src, nbytes,
189 tfm->__crt_alg->cra_cipher.cia_encrypt,
190 ecb_process, NULL);
191}
192
193static int ecb_decrypt(struct crypto_tfm *tfm,
194 struct scatterlist *dst,
195 struct scatterlist *src,
196 unsigned int nbytes)
197{
198 return crypt(tfm, dst, src, nbytes,
199 tfm->__crt_alg->cra_cipher.cia_decrypt,
200 ecb_process, NULL);
201}
202
203static int cbc_encrypt(struct crypto_tfm *tfm,
204 struct scatterlist *dst,
205 struct scatterlist *src,
206 unsigned int nbytes)
207{
208 return crypt(tfm, dst, src, nbytes,
209 tfm->__crt_alg->cra_cipher.cia_encrypt,
210 cbc_process_encrypt, tfm->crt_cipher.cit_iv);
211}
212
213static int cbc_encrypt_iv(struct crypto_tfm *tfm,
214 struct scatterlist *dst,
215 struct scatterlist *src,
216 unsigned int nbytes, u8 *iv)
217{
218 return crypt(tfm, dst, src, nbytes,
219 tfm->__crt_alg->cra_cipher.cia_encrypt,
220 cbc_process_encrypt, iv);
221}
222
223static int cbc_decrypt(struct crypto_tfm *tfm,
224 struct scatterlist *dst,
225 struct scatterlist *src,
226 unsigned int nbytes)
227{
228 return crypt(tfm, dst, src, nbytes,
229 tfm->__crt_alg->cra_cipher.cia_decrypt,
230 cbc_process_decrypt, tfm->crt_cipher.cit_iv);
231}
232
233static int cbc_decrypt_iv(struct crypto_tfm *tfm,
234 struct scatterlist *dst,
235 struct scatterlist *src,
236 unsigned int nbytes, u8 *iv)
237{
238 return crypt(tfm, dst, src, nbytes,
239 tfm->__crt_alg->cra_cipher.cia_decrypt,
240 cbc_process_decrypt, iv);
241}
242
243static int nocrypt(struct crypto_tfm *tfm,
244 struct scatterlist *dst,
245 struct scatterlist *src,
246 unsigned int nbytes)
247{
248 return -ENOSYS;
249}
250
251static int nocrypt_iv(struct crypto_tfm *tfm,
252 struct scatterlist *dst,
253 struct scatterlist *src,
254 unsigned int nbytes, u8 *iv)
255{
256 return -ENOSYS;
257}
258
259int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
260{
261 u32 mode = flags & CRYPTO_TFM_MODE_MASK;
262
263 tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
264 if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
265 tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
266
267 return 0;
268}
269
270int crypto_init_cipher_ops(struct crypto_tfm *tfm)
271{
272 int ret = 0;
273 struct cipher_tfm *ops = &tfm->crt_cipher;
274
275 ops->cit_setkey = setkey;
276
277 switch (tfm->crt_cipher.cit_mode) {
278 case CRYPTO_TFM_MODE_ECB:
279 ops->cit_encrypt = ecb_encrypt;
280 ops->cit_decrypt = ecb_decrypt;
281 break;
282
283 case CRYPTO_TFM_MODE_CBC:
284 ops->cit_encrypt = cbc_encrypt;
285 ops->cit_decrypt = cbc_decrypt;
286 ops->cit_encrypt_iv = cbc_encrypt_iv;
287 ops->cit_decrypt_iv = cbc_decrypt_iv;
288 break;
289
290 case CRYPTO_TFM_MODE_CFB:
291 ops->cit_encrypt = nocrypt;
292 ops->cit_decrypt = nocrypt;
293 ops->cit_encrypt_iv = nocrypt_iv;
294 ops->cit_decrypt_iv = nocrypt_iv;
295 break;
296
297 case CRYPTO_TFM_MODE_CTR:
298 ops->cit_encrypt = nocrypt;
299 ops->cit_decrypt = nocrypt;
300 ops->cit_encrypt_iv = nocrypt_iv;
301 ops->cit_decrypt_iv = nocrypt_iv;
302 break;
303
304 default:
305 BUG();
306 }
307
308 if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
309
310 switch (crypto_tfm_alg_blocksize(tfm)) {
311 case 8:
312 ops->cit_xor_block = xor_64;
313 break;
314
315 case 16:
316 ops->cit_xor_block = xor_128;
317 break;
318
319 default:
320 printk(KERN_WARNING "%s: block size %u not supported\n",
321 crypto_tfm_alg_name(tfm),
322 crypto_tfm_alg_blocksize(tfm));
323 ret = -EINVAL;
324 goto out;
325 }
326
327 ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
328 ops->cit_iv = kmalloc(ops->cit_ivsize, GFP_KERNEL);
329 if (ops->cit_iv == NULL)
330 ret = -ENOMEM;
331 }
332
333out:
334 return ret;
335}
336
337void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
338{
339 if (tfm->crt_cipher.cit_iv)
340 kfree(tfm->crt_cipher.cit_iv);
341}