cipher.c revision e406322b4b963e622f41d76193d8ca9e5435adb8 
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/kernel.h>
15//#include <linux/crypto.h>
16#include "rtl_crypto.h"
17#include <linux/errno.h>
18#include <linux/mm.h>
19#include <linux/slab.h>
20#include <asm/scatterlist.h>
21#include "internal.h"
22#include "scatterwalk.h"
23
24typedef void (cryptfn_t)(void *, u8 *, const u8 *);
25typedef void (procfn_t)(struct crypto_tfm *, u8 *,
26			u8*, cryptfn_t, int enc, void *, int);
27
28static inline void xor_64(u8 *a, const u8 *b)
29{
30	((u32 *)a)[0] ^= ((u32 *)b)[0];
31	((u32 *)a)[1] ^= ((u32 *)b)[1];
32}
33
34static inline void xor_128(u8 *a, const u8 *b)
35{
36	((u32 *)a)[0] ^= ((u32 *)b)[0];
37	((u32 *)a)[1] ^= ((u32 *)b)[1];
38	((u32 *)a)[2] ^= ((u32 *)b)[2];
39	((u32 *)a)[3] ^= ((u32 *)b)[3];
40}
41
42
43/*
44 * Generic encrypt/decrypt wrapper for ciphers, handles operations across
45 * multiple page boundaries by using temporary blocks.  In user context,
46 * the kernel is given a chance to schedule us once per block.
47 */
48static int crypt(struct crypto_tfm *tfm,
49		 struct scatterlist *dst,
50		 struct scatterlist *src,
51		 unsigned int nbytes, cryptfn_t crfn,
52		 procfn_t prfn, int enc, void *info)
53{
54	struct scatter_walk walk_in, walk_out;
55	const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
56	u8 tmp_src[bsize];
57	u8 tmp_dst[bsize];
58
59	if (!nbytes)
60		return 0;
61
62	if (nbytes % bsize) {
63		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
64		return -EINVAL;
65	}
66
67	scatterwalk_start(&walk_in, src);
68	scatterwalk_start(&walk_out, dst);
69
70	for(;;) {
71		u8 *src_p, *dst_p;
72		int in_place;
73
74		scatterwalk_map(&walk_in, 0);
75		scatterwalk_map(&walk_out, 1);
76		src_p = scatterwalk_whichbuf(&walk_in, bsize, tmp_src);
77		dst_p = scatterwalk_whichbuf(&walk_out, bsize, tmp_dst);
78		in_place = scatterwalk_samebuf(&walk_in, &walk_out,
79					       src_p, dst_p);
80
81		nbytes -= bsize;
82
83		scatterwalk_copychunks(src_p, &walk_in, bsize, 0);
84
85		prfn(tfm, dst_p, src_p, crfn, enc, info, in_place);
86
87		scatterwalk_done(&walk_in, 0, nbytes);
88
89		scatterwalk_copychunks(dst_p, &walk_out, bsize, 1);
90		scatterwalk_done(&walk_out, 1, nbytes);
91
92		if (!nbytes)
93			return 0;
94
95		crypto_yield(tfm);
96	}
97}
98
99static void cbc_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
100			cryptfn_t fn, int enc, void *info, int in_place)
101{
102	u8 *iv = info;
103
104	/* Null encryption */
105	if (!iv)
106		return;
107
108	if (enc) {
109		tfm->crt_u.cipher.cit_xor_block(iv, src);
110		fn(crypto_tfm_ctx(tfm), dst, iv);
111		memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
112	} else {
113		u8 stack[in_place ? crypto_tfm_alg_blocksize(tfm) : 0];
114		u8 *buf = in_place ? stack : dst;
115
116		fn(crypto_tfm_ctx(tfm), buf, src);
117		tfm->crt_u.cipher.cit_xor_block(buf, iv);
118		memcpy(iv, src, crypto_tfm_alg_blocksize(tfm));
119		if (buf != dst)
120			memcpy(dst, buf, crypto_tfm_alg_blocksize(tfm));
121	}
122}
123
124static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
125			cryptfn_t fn, int enc, void *info, int in_place)
126{
127	fn(crypto_tfm_ctx(tfm), dst, src);
128}
129
130static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
131{
132	struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
133
134	if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
135		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
136		return -EINVAL;
137	} else
138		return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
139				       &tfm->crt_flags);
140}
141
142static int ecb_encrypt(struct crypto_tfm *tfm,
143		       struct scatterlist *dst,
144		       struct scatterlist *src, unsigned int nbytes)
145{
146	return crypt(tfm, dst, src, nbytes,
147		     tfm->__crt_alg->cra_cipher.cia_encrypt,
148		     ecb_process, 1, NULL);
149}
150
151static int ecb_decrypt(struct crypto_tfm *tfm,
152		       struct scatterlist *dst,
153		       struct scatterlist *src,
154		       unsigned int nbytes)
155{
156	return crypt(tfm, dst, src, nbytes,
157		     tfm->__crt_alg->cra_cipher.cia_decrypt,
158		     ecb_process, 1, NULL);
159}
160
161static int cbc_encrypt(struct crypto_tfm *tfm,
162		       struct scatterlist *dst,
163		       struct scatterlist *src,
164		       unsigned int nbytes)
165{
166	return crypt(tfm, dst, src, nbytes,
167		     tfm->__crt_alg->cra_cipher.cia_encrypt,
168		     cbc_process, 1, tfm->crt_cipher.cit_iv);
169}
170
171static int cbc_encrypt_iv(struct crypto_tfm *tfm,
172			  struct scatterlist *dst,
173			  struct scatterlist *src,
174			  unsigned int nbytes, u8 *iv)
175{
176	return crypt(tfm, dst, src, nbytes,
177		     tfm->__crt_alg->cra_cipher.cia_encrypt,
178		     cbc_process, 1, iv);
179}
180
181static int cbc_decrypt(struct crypto_tfm *tfm,
182		       struct scatterlist *dst,
183		       struct scatterlist *src,
184		       unsigned int nbytes)
185{
186	return crypt(tfm, dst, src, nbytes,
187		     tfm->__crt_alg->cra_cipher.cia_decrypt,
188		     cbc_process, 0, tfm->crt_cipher.cit_iv);
189}
190
191static int cbc_decrypt_iv(struct crypto_tfm *tfm,
192			  struct scatterlist *dst,
193			  struct scatterlist *src,
194			  unsigned int nbytes, u8 *iv)
195{
196	return crypt(tfm, dst, src, nbytes,
197		     tfm->__crt_alg->cra_cipher.cia_decrypt,
198		     cbc_process, 0, iv);
199}
200
201static int nocrypt(struct crypto_tfm *tfm,
202		   struct scatterlist *dst,
203		   struct scatterlist *src,
204		   unsigned int nbytes)
205{
206	return -ENOSYS;
207}
208
209static int nocrypt_iv(struct crypto_tfm *tfm,
210		      struct scatterlist *dst,
211		      struct scatterlist *src,
212		      unsigned int nbytes, u8 *iv)
213{
214	return -ENOSYS;
215}
216
217int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
218{
219	u32 mode = flags & CRYPTO_TFM_MODE_MASK;
220
221	tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
222	if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
223		tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
224
225	return 0;
226}
227
228int crypto_init_cipher_ops(struct crypto_tfm *tfm)
229{
230	int ret = 0;
231	struct cipher_tfm *ops = &tfm->crt_cipher;
232
233	ops->cit_setkey = setkey;
234
235	switch (tfm->crt_cipher.cit_mode) {
236	case CRYPTO_TFM_MODE_ECB:
237		ops->cit_encrypt = ecb_encrypt;
238		ops->cit_decrypt = ecb_decrypt;
239		break;
240
241	case CRYPTO_TFM_MODE_CBC:
242		ops->cit_encrypt = cbc_encrypt;
243		ops->cit_decrypt = cbc_decrypt;
244		ops->cit_encrypt_iv = cbc_encrypt_iv;
245		ops->cit_decrypt_iv = cbc_decrypt_iv;
246		break;
247
248	case CRYPTO_TFM_MODE_CFB:
249		ops->cit_encrypt = nocrypt;
250		ops->cit_decrypt = nocrypt;
251		ops->cit_encrypt_iv = nocrypt_iv;
252		ops->cit_decrypt_iv = nocrypt_iv;
253		break;
254
255	case CRYPTO_TFM_MODE_CTR:
256		ops->cit_encrypt = nocrypt;
257		ops->cit_decrypt = nocrypt;
258		ops->cit_encrypt_iv = nocrypt_iv;
259		ops->cit_decrypt_iv = nocrypt_iv;
260		break;
261
262	default:
263		BUG();
264	}
265
266	if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
267
268		switch (crypto_tfm_alg_blocksize(tfm)) {
269		case 8:
270			ops->cit_xor_block = xor_64;
271			break;
272
273		case 16:
274			ops->cit_xor_block = xor_128;
275			break;
276
277		default:
278			printk(KERN_WARNING "%s: block size %u not supported\n",
279			       crypto_tfm_alg_name(tfm),
280			       crypto_tfm_alg_blocksize(tfm));
281			ret = -EINVAL;
282			goto out;
283		}
284
285		ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
286		ops->cit_iv = kmalloc(ops->cit_ivsize, GFP_KERNEL);
287		if (ops->cit_iv == NULL)
288			ret = -ENOMEM;
289	}
290
291out:
292	return ret;
293}
294
295void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
296{
297	if (tfm->crt_cipher.cit_iv)
298		kfree(tfm->crt_cipher.cit_iv);
299}
300