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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 | ||
25 | typedef void (cryptfn_t)(void *, u8 *, const u8 *); | |
26 | typedef void (procfn_t)(struct crypto_tfm *, u8 *, | |
27 | u8*, cryptfn_t, void *); | |
28 | ||
29 | static 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 | ||
35 | static 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 | ||
43 | static 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 | ||
57 | static 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 | ||
67 | static inline void complete_src(struct scatter_walk *walk, int bsize, | |
68 | void *src, int in_place) | |
69 | { | |
70 | } | |
71 | ||
72 | static 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 | */ | |
89 | static 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 | ||
146 | static 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 | ||
156 | static 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 | ||
166 | static 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 | ||
172 | static 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 | ||
184 | static 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 | ||
193 | static 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 | ||
203 | static 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 | ||
213 | static 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 | ||
223 | static 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 | ||
233 | static 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 | ||
243 | static int nocrypt(struct crypto_tfm *tfm, | |
244 | struct scatterlist *dst, | |
245 | struct scatterlist *src, | |
246 | unsigned int nbytes) | |
247 | { | |
248 | return -ENOSYS; | |
249 | } | |
250 | ||
251 | static 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 | ||
259 | int 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 | ||
270 | int 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 | ||
333 | out: | |
334 | return ret; | |
335 | } | |
336 | ||
337 | void crypto_exit_cipher_ops(struct crypto_tfm *tfm) | |
338 | { | |
339 | kfree(tfm->crt_cipher.cit_iv); | |
340 | } |