aboutsummaryrefslogtreecommitdiff
path: root/crypto/cipher.c
blob: f573c59ed9dc734ca1447c5f3fb33efd421382f4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
/*
 * Cryptographic API.
 *
 * Cipher operations.
 *
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option) 
 * any later version.
 *
 */
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/crypto.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <asm/scatterlist.h>
#include "internal.h"
#include "scatterwalk.h"

static inline void xor_64(u8 *a, const u8 *b)
{
	((u32 *)a)[0] ^= ((u32 *)b)[0];
	((u32 *)a)[1] ^= ((u32 *)b)[1];
}

static inline void xor_128(u8 *a, const u8 *b)
{
	((u32 *)a)[0] ^= ((u32 *)b)[0];
	((u32 *)a)[1] ^= ((u32 *)b)[1];
	((u32 *)a)[2] ^= ((u32 *)b)[2];
	((u32 *)a)[3] ^= ((u32 *)b)[3];
}

static unsigned int crypt_slow(const struct cipher_desc *desc,
			       struct scatter_walk *in,
			       struct scatter_walk *out, unsigned int bsize)
{
	unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
	u8 buffer[bsize * 2 + alignmask];
	u8 *src = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
	u8 *dst = src + bsize;
	unsigned int n;

	n = scatterwalk_copychunks(src, in, bsize, 0);
	scatterwalk_advance(in, n);

	desc->prfn(desc, dst, src, bsize);

	n = scatterwalk_copychunks(dst, out, bsize, 1);
	scatterwalk_advance(out, n);

	return bsize;
}

static inline unsigned int crypt_fast(const struct cipher_desc *desc,
				      struct scatter_walk *in,
				      struct scatter_walk *out,
				      unsigned int nbytes, u8 *tmp)
{
	u8 *src, *dst;

	src = in->data;
	dst = scatterwalk_samebuf(in, out) ? src : out->data;

	if (tmp) {
		memcpy(tmp, in->data, nbytes);
		src = tmp;
		dst = tmp;
	}

	nbytes = desc->prfn(desc, dst, src, nbytes);

	if (tmp)
		memcpy(out->data, tmp, nbytes);

	scatterwalk_advance(in, nbytes);
	scatterwalk_advance(out, nbytes);

	return nbytes;
}

/* 
 * Generic encrypt/decrypt wrapper for ciphers, handles operations across
 * multiple page boundaries by using temporary blocks.  In user context,
 * the kernel is given a chance to schedule us once per page.
 */
static int crypt(const struct cipher_desc *desc,
		 struct scatterlist *dst,
		 struct scatterlist *src,
		 unsigned int nbytes)
{
	struct scatter_walk walk_in, walk_out;
	struct crypto_tfm *tfm = desc->tfm;
	const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
	unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
	unsigned long buffer = 0;

	if (!nbytes)
		return 0;

	if (nbytes % bsize) {
		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
		return -EINVAL;
	}

	scatterwalk_start(&walk_in, src);
	scatterwalk_start(&walk_out, dst);

	for(;;) {
		unsigned int n = nbytes;
		u8 *tmp = NULL;

		if (!scatterwalk_aligned(&walk_in, alignmask) ||
		    !scatterwalk_aligned(&walk_out, alignmask)) {
			if (!buffer) {
				buffer = __get_free_page(GFP_ATOMIC);
				if (!buffer)
					n = 0;
			}
			tmp = (u8 *)buffer;
		}

		scatterwalk_map(&walk_in, 0);
		scatterwalk_map(&walk_out, 1);

		n = scatterwalk_clamp(&walk_in, n);
		n = scatterwalk_clamp(&walk_out, n);

		if (likely(n >= bsize))
			n = crypt_fast(desc, &walk_in, &walk_out, n, tmp);
		else
			n = crypt_slow(desc, &walk_in, &walk_out, bsize);

		nbytes -= n;

		scatterwalk_done(&walk_in, 0, nbytes);
		scatterwalk_done(&walk_out, 1, nbytes);

		if (!nbytes)
			break;

		crypto_yield(tfm->crt_flags);
	}

	if (buffer)
		free_page(buffer);

	return 0;
}

static int crypt_iv_unaligned(struct cipher_desc *desc,
			      struct scatterlist *dst,
			      struct scatterlist *src,
			      unsigned int nbytes)
{
	struct crypto_tfm *tfm = desc->tfm;
	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
	u8 *iv = desc->info;

	if (unlikely(((unsigned long)iv & alignmask))) {
		unsigned int ivsize = tfm->crt_cipher.cit_ivsize;
		u8 buffer[ivsize + alignmask];
		u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
		int err;

		desc->info = memcpy(tmp, iv, ivsize);
		err = crypt(desc, dst, src, nbytes);
		memcpy(iv, tmp, ivsize);

		return err;
	}

	return crypt(desc, dst, src, nbytes);
}

static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
					u8 *dst, const u8 *src,
					unsigned int nbytes)
{
	struct crypto_tfm *tfm = desc->tfm;
	void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
	int bsize = crypto_tfm_alg_blocksize(tfm);

	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
	u8 *iv = desc->info;
	unsigned int done = 0;

	nbytes -= bsize;

	do {
		xor(iv, src);
		fn(tfm, dst, iv);
		memcpy(iv, dst, bsize);

		src += bsize;
		dst += bsize;
	} while ((done += bsize) <= nbytes);

	return done;
}

static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
					u8 *dst, const u8 *src,
					unsigned int nbytes)
{
	struct crypto_tfm *tfm = desc->tfm;
	void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
	int bsize = crypto_tfm_alg_blocksize(tfm);
	unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);

	u8 stack[src == dst ? bsize + alignmask : 0];
	u8 *buf = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
	u8 **dst_p = src == dst ? &buf : &dst;

	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
	u8 *iv = desc->info;
	unsigned int done = 0;

	nbytes -= bsize;

	do {
		u8 *tmp_dst = *dst_p;

		fn(tfm, tmp_dst, src);
		xor(tmp_dst, iv);
		memcpy(iv, src, bsize);
		if (tmp_dst != dst)
			memcpy(dst, tmp_dst, bsize);

		src += bsize;
		dst += bsize;
	} while ((done += bsize) <= nbytes);

	return done;
}

static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
				const u8 *src, unsigned int nbytes)
{
	struct crypto_tfm *tfm = desc->tfm;
	int bsize = crypto_tfm_alg_blocksize(tfm);
	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
	unsigned int done = 0;

	nbytes -= bsize;

	do {
		fn(tfm, dst, src);

		src += bsize;
		dst += bsize;
	} while ((done += bsize) <= nbytes);

	return done;
}

static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
{
	struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
	
	tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
	if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	} else
		return cia->cia_setkey(tfm, key, keylen);
}

static int ecb_encrypt(struct crypto_tfm *tfm,
		       struct scatterlist *dst,
                       struct scatterlist *src, unsigned int nbytes)
{
	struct cipher_desc desc;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	desc.tfm = tfm;
	desc.crfn = cipher->cia_encrypt;
	desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;

	return crypt(&desc, dst, src, nbytes);
}

static int ecb_decrypt(struct crypto_tfm *tfm,
                       struct scatterlist *dst,
                       struct scatterlist *src,
		       unsigned int nbytes)
{
	struct cipher_desc desc;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	desc.tfm = tfm;
	desc.crfn = cipher->cia_decrypt;
	desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;

	return crypt(&desc, dst, src, nbytes);
}

static int cbc_encrypt(struct crypto_tfm *tfm,
                       struct scatterlist *dst,
                       struct scatterlist *src,
		       unsigned int nbytes)
{
	struct cipher_desc desc;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	desc.tfm = tfm;
	desc.crfn = cipher->cia_encrypt;
	desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
	desc.info = tfm->crt_cipher.cit_iv;

	return crypt(&desc, dst, src, nbytes);
}

static int cbc_encrypt_iv(struct crypto_tfm *tfm,
                          struct scatterlist *dst,
                          struct scatterlist *src,
                          unsigned int nbytes, u8 *iv)
{
	struct cipher_desc desc;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	desc.tfm = tfm;
	desc.crfn = cipher->cia_encrypt;
	desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
	desc.info = iv;

	return crypt_iv_unaligned(&desc, dst, src, nbytes);
}

static int cbc_decrypt(struct crypto_tfm *tfm,
                       struct scatterlist *dst,
                       struct scatterlist *src,
		       unsigned int nbytes)
{
	struct cipher_desc desc;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	desc.tfm = tfm;
	desc.crfn = cipher->cia_decrypt;
	desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
	desc.info = tfm->crt_cipher.cit_iv;

	return crypt(&desc, dst, src, nbytes);
}

static int cbc_decrypt_iv(struct crypto_tfm *tfm,
                          struct scatterlist *dst,
                          struct scatterlist *src,
                          unsigned int nbytes, u8 *iv)
{
	struct cipher_desc desc;
	struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;

	desc.tfm = tfm;
	desc.crfn = cipher->cia_decrypt;
	desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
	desc.info = iv;

	return crypt_iv_unaligned(&desc, dst, src, nbytes);
}

static int nocrypt(struct crypto_tfm *tfm,
                   struct scatterlist *dst,
                   struct scatterlist *src,
		   unsigned int nbytes)
{
	return -ENOSYS;
}

static int nocrypt_iv(struct crypto_tfm *tfm,
                      struct scatterlist *dst,
                      struct scatterlist *src,
                      unsigned int nbytes, u8 *iv)
{
	return -ENOSYS;
}

int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
{
	u32 mode = flags & CRYPTO_TFM_MODE_MASK;
	tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
	return 0;
}

int crypto_init_cipher_ops(struct crypto_tfm *tfm)
{
	int ret = 0;
	struct cipher_tfm *ops = &tfm->crt_cipher;

	ops->cit_setkey = setkey;

	switch (tfm->crt_cipher.cit_mode) {
	case CRYPTO_TFM_MODE_ECB:
		ops->cit_encrypt = ecb_encrypt;
		ops->cit_decrypt = ecb_decrypt;
		ops->cit_encrypt_iv = nocrypt_iv;
		ops->cit_decrypt_iv = nocrypt_iv;
		break;
		
	case CRYPTO_TFM_MODE_CBC:
		ops->cit_encrypt = cbc_encrypt;
		ops->cit_decrypt = cbc_decrypt;
		ops->cit_encrypt_iv = cbc_encrypt_iv;
		ops->cit_decrypt_iv = cbc_decrypt_iv;
		break;
		
	case CRYPTO_TFM_MODE_CFB:
		ops->cit_encrypt = nocrypt;
		ops->cit_decrypt = nocrypt;
		ops->cit_encrypt_iv = nocrypt_iv;
		ops->cit_decrypt_iv = nocrypt_iv;
		break;
	
	case CRYPTO_TFM_MODE_CTR:
		ops->cit_encrypt = nocrypt;
		ops->cit_decrypt = nocrypt;
		ops->cit_encrypt_iv = nocrypt_iv;
		ops->cit_decrypt_iv = nocrypt_iv;
		break;

	default:
		BUG();
	}
	
	if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
		unsigned long align;
		unsigned long addr;
	    	
	    	switch (crypto_tfm_alg_blocksize(tfm)) {
	    	case 8:
	    		ops->cit_xor_block = xor_64;
	    		break;
	    		
	    	case 16:
	    		ops->cit_xor_block = xor_128;
	    		break;
	    		
	    	default:
	    		printk(KERN_WARNING "%s: block size %u not supported\n",
	    		       crypto_tfm_alg_name(tfm),
	    		       crypto_tfm_alg_blocksize(tfm));
	    		ret = -EINVAL;
	    		goto out;
	    	}
	    	
		ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
		align = crypto_tfm_alg_alignmask(tfm) + 1;
		addr = (unsigned long)crypto_tfm_ctx(tfm);
		addr = ALIGN(addr, align);
		addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
		ops->cit_iv = (void *)addr;
	}

out:	
	return ret;
}

void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
{
}