Linux Kernel  3.7.1
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cipher.c
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1 /*
2  * Cryptographic API.
3  *
4  * Cipher operations.
5  *
6  * Copyright (c) 2002 James Morris <[email protected]>
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 
24 typedef void (cryptfn_t)(void *, u8 *, const u8 *);
25 typedef void (procfn_t)(struct crypto_tfm *, u8 *,
26  u8*, cryptfn_t, int enc, void *, int);
27 
28 static 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 
34 static 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  */
48 static 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);
75  scatterwalk_map(&walk_out);
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, nbytes);
88 
89  scatterwalk_copychunks(dst_p, &walk_out, bsize, 1);
90  scatterwalk_done(&walk_out, nbytes);
91 
92  if (!nbytes)
93  return 0;
94 
95  crypto_yield(tfm);
96  }
97 }
98 
99 static 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 
124 static 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 
130 static 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 
142 static 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 
151 static 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 
161 static 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 
171 static 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 
181 static 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 
191 static 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 
201 static int nocrypt(struct crypto_tfm *tfm,
202  struct scatterlist *dst,
203  struct scatterlist *src,
204  unsigned int nbytes)
205 {
206  return -ENOSYS;
207 }
208 
209 static 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 
217 int 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 
228 int 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 
291 out:
292  return ret;
293 }
294 
295 void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
296 {
297  kfree(tfm->crt_cipher.cit_iv);
298 }
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