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23e353c8 JL |
1 | /* |
2 | * CTR: Counter mode | |
3 | * | |
4 | * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the Free | |
8 | * Software Foundation; either version 2 of the License, or (at your option) | |
9 | * any later version. | |
10 | * | |
11 | */ | |
12 | ||
13 | #include <crypto/algapi.h> | |
14 | #include <linux/err.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/random.h> | |
19 | #include <linux/scatterlist.h> | |
20 | #include <linux/slab.h> | |
21 | ||
22 | struct ctr_instance_ctx { | |
23 | struct crypto_spawn alg; | |
24 | unsigned int noncesize; | |
25 | unsigned int ivsize; | |
41fdab3d | 26 | unsigned int countersize; |
23e353c8 JL |
27 | }; |
28 | ||
29 | struct crypto_ctr_ctx { | |
30 | struct crypto_cipher *child; | |
31 | u8 *nonce; | |
32 | }; | |
33 | ||
23e353c8 JL |
34 | static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key, |
35 | unsigned int keylen) | |
36 | { | |
37 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent); | |
38 | struct crypto_cipher *child = ctx->child; | |
39 | struct ctr_instance_ctx *ictx = | |
40 | crypto_instance_ctx(crypto_tfm_alg_instance(parent)); | |
41 | unsigned int noncelen = ictx->noncesize; | |
42 | int err = 0; | |
43 | ||
44 | /* the nonce is stored in bytes at end of key */ | |
45 | if (keylen < noncelen) | |
46 | return -EINVAL; | |
47 | ||
48 | memcpy(ctx->nonce, key + (keylen - noncelen), noncelen); | |
49 | ||
50 | keylen -= noncelen; | |
51 | ||
52 | crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); | |
53 | crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & | |
54 | CRYPTO_TFM_REQ_MASK); | |
55 | err = crypto_cipher_setkey(child, key, keylen); | |
56 | crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & | |
57 | CRYPTO_TFM_RES_MASK); | |
58 | ||
59 | return err; | |
60 | } | |
61 | ||
0971eb0d HX |
62 | static void crypto_ctr_crypt_final(struct blkcipher_walk *walk, |
63 | struct crypto_cipher *tfm, u8 *ctrblk, | |
64 | unsigned int countersize) | |
65 | { | |
66 | unsigned int bsize = crypto_cipher_blocksize(tfm); | |
67 | u8 *keystream = ctrblk + bsize; | |
68 | u8 *src = walk->src.virt.addr; | |
69 | u8 *dst = walk->dst.virt.addr; | |
70 | unsigned int nbytes = walk->nbytes; | |
71 | ||
72 | crypto_cipher_encrypt_one(tfm, keystream, ctrblk); | |
73 | crypto_xor(keystream, src, nbytes); | |
74 | memcpy(dst, keystream, nbytes); | |
75 | } | |
76 | ||
23e353c8 JL |
77 | static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk, |
78 | struct crypto_cipher *tfm, u8 *ctrblk, | |
79 | unsigned int countersize) | |
80 | { | |
81 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = | |
82 | crypto_cipher_alg(tfm)->cia_encrypt; | |
83 | unsigned int bsize = crypto_cipher_blocksize(tfm); | |
23e353c8 JL |
84 | u8 *src = walk->src.virt.addr; |
85 | u8 *dst = walk->dst.virt.addr; | |
86 | unsigned int nbytes = walk->nbytes; | |
87 | ||
88 | do { | |
89 | /* create keystream */ | |
0971eb0d HX |
90 | fn(crypto_cipher_tfm(tfm), dst, ctrblk); |
91 | crypto_xor(dst, src, bsize); | |
23e353c8 JL |
92 | |
93 | /* increment counter in counterblock */ | |
3f8214ea | 94 | crypto_inc(ctrblk + bsize - countersize, countersize); |
23e353c8 | 95 | |
23e353c8 JL |
96 | src += bsize; |
97 | dst += bsize; | |
0971eb0d | 98 | } while ((nbytes -= bsize) >= bsize); |
23e353c8 | 99 | |
0971eb0d | 100 | return nbytes; |
23e353c8 JL |
101 | } |
102 | ||
103 | static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk, | |
104 | struct crypto_cipher *tfm, u8 *ctrblk, | |
105 | unsigned int countersize) | |
106 | { | |
107 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = | |
108 | crypto_cipher_alg(tfm)->cia_encrypt; | |
109 | unsigned int bsize = crypto_cipher_blocksize(tfm); | |
23e353c8 JL |
110 | unsigned int nbytes = walk->nbytes; |
111 | u8 *src = walk->src.virt.addr; | |
0971eb0d | 112 | u8 *keystream = ctrblk + bsize; |
23e353c8 JL |
113 | |
114 | do { | |
115 | /* create keystream */ | |
116 | fn(crypto_cipher_tfm(tfm), keystream, ctrblk); | |
0971eb0d | 117 | crypto_xor(src, keystream, bsize); |
23e353c8 JL |
118 | |
119 | /* increment counter in counterblock */ | |
3f8214ea | 120 | crypto_inc(ctrblk + bsize - countersize, countersize); |
23e353c8 | 121 | |
23e353c8 | 122 | src += bsize; |
0971eb0d | 123 | } while ((nbytes -= bsize) >= bsize); |
23e353c8 | 124 | |
0971eb0d | 125 | return nbytes; |
23e353c8 JL |
126 | } |
127 | ||
128 | static int crypto_ctr_crypt(struct blkcipher_desc *desc, | |
129 | struct scatterlist *dst, struct scatterlist *src, | |
130 | unsigned int nbytes) | |
131 | { | |
132 | struct blkcipher_walk walk; | |
133 | struct crypto_blkcipher *tfm = desc->tfm; | |
134 | struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm); | |
135 | struct crypto_cipher *child = ctx->child; | |
136 | unsigned int bsize = crypto_cipher_blocksize(child); | |
137 | struct ctr_instance_ctx *ictx = | |
138 | crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base)); | |
3f8214ea HX |
139 | unsigned long alignmask = crypto_cipher_alignmask(child) | |
140 | (__alignof__(u32) - 1); | |
0971eb0d | 141 | u8 cblk[bsize * 2 + alignmask]; |
23e353c8 | 142 | u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1); |
23e353c8 JL |
143 | int err; |
144 | ||
145 | blkcipher_walk_init(&walk, dst, src, nbytes); | |
146 | err = blkcipher_walk_virt_block(desc, &walk, bsize); | |
147 | ||
148 | /* set up counter block */ | |
149 | memset(counterblk, 0 , bsize); | |
150 | memcpy(counterblk, ctx->nonce, ictx->noncesize); | |
151 | memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize); | |
152 | ||
153 | /* initialize counter portion of counter block */ | |
3f8214ea | 154 | crypto_inc(counterblk + bsize - ictx->countersize, ictx->countersize); |
23e353c8 | 155 | |
0971eb0d | 156 | while (walk.nbytes >= bsize) { |
23e353c8 JL |
157 | if (walk.src.virt.addr == walk.dst.virt.addr) |
158 | nbytes = crypto_ctr_crypt_inplace(&walk, child, | |
159 | counterblk, | |
41fdab3d | 160 | ictx->countersize); |
23e353c8 JL |
161 | else |
162 | nbytes = crypto_ctr_crypt_segment(&walk, child, | |
163 | counterblk, | |
41fdab3d | 164 | ictx->countersize); |
23e353c8 JL |
165 | |
166 | err = blkcipher_walk_done(desc, &walk, nbytes); | |
167 | } | |
0971eb0d HX |
168 | |
169 | if (walk.nbytes) { | |
170 | crypto_ctr_crypt_final(&walk, child, counterblk, | |
171 | ictx->countersize); | |
172 | err = blkcipher_walk_done(desc, &walk, 0); | |
173 | } | |
174 | ||
23e353c8 JL |
175 | return err; |
176 | } | |
177 | ||
178 | static int crypto_ctr_init_tfm(struct crypto_tfm *tfm) | |
179 | { | |
180 | struct crypto_instance *inst = (void *)tfm->__crt_alg; | |
181 | struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst); | |
182 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); | |
183 | struct crypto_cipher *cipher; | |
184 | ||
185 | ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL); | |
186 | if (!ctx->nonce) | |
187 | return -ENOMEM; | |
188 | ||
189 | cipher = crypto_spawn_cipher(&ictx->alg); | |
190 | if (IS_ERR(cipher)) | |
191 | return PTR_ERR(cipher); | |
192 | ||
193 | ctx->child = cipher; | |
194 | ||
195 | return 0; | |
196 | } | |
197 | ||
198 | static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm) | |
199 | { | |
200 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); | |
201 | ||
202 | kfree(ctx->nonce); | |
203 | crypto_free_cipher(ctx->child); | |
204 | } | |
205 | ||
206 | static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb) | |
207 | { | |
208 | struct crypto_instance *inst; | |
209 | struct crypto_alg *alg; | |
210 | struct ctr_instance_ctx *ictx; | |
211 | unsigned int noncesize; | |
212 | unsigned int ivsize; | |
41fdab3d | 213 | unsigned int countersize; |
23e353c8 JL |
214 | int err; |
215 | ||
216 | err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); | |
217 | if (err) | |
218 | return ERR_PTR(err); | |
219 | ||
220 | alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, | |
221 | CRYPTO_ALG_TYPE_MASK); | |
222 | if (IS_ERR(alg)) | |
223 | return ERR_PTR(PTR_ERR(alg)); | |
224 | ||
225 | err = crypto_attr_u32(tb[2], &noncesize); | |
226 | if (err) | |
227 | goto out_put_alg; | |
228 | ||
229 | err = crypto_attr_u32(tb[3], &ivsize); | |
230 | if (err) | |
231 | goto out_put_alg; | |
232 | ||
41fdab3d JL |
233 | err = crypto_attr_u32(tb[4], &countersize); |
234 | if (err) | |
235 | goto out_put_alg; | |
236 | ||
237 | /* verify size of nonce + iv + counter | |
238 | * counter must be >= 4 bytes. | |
239 | */ | |
23e353c8 | 240 | err = -EINVAL; |
41fdab3d JL |
241 | if (((noncesize + ivsize + countersize) < alg->cra_blocksize) || |
242 | ((noncesize + ivsize) > alg->cra_blocksize) || | |
243 | (countersize > alg->cra_blocksize) || (countersize < 4)) | |
23e353c8 JL |
244 | goto out_put_alg; |
245 | ||
3f8214ea HX |
246 | /* If this is false we'd fail the alignment of crypto_inc. */ |
247 | if ((alg->cra_blocksize - countersize) % 4) | |
248 | goto out_put_alg; | |
249 | ||
23e353c8 JL |
250 | inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL); |
251 | err = -ENOMEM; | |
252 | if (!inst) | |
253 | goto out_put_alg; | |
254 | ||
255 | err = -ENAMETOOLONG; | |
256 | if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME, | |
41fdab3d JL |
257 | "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize, |
258 | ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) { | |
23e353c8 JL |
259 | goto err_free_inst; |
260 | } | |
261 | ||
262 | if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME, | |
41fdab3d JL |
263 | "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize, |
264 | ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) { | |
23e353c8 JL |
265 | goto err_free_inst; |
266 | } | |
267 | ||
268 | ictx = crypto_instance_ctx(inst); | |
269 | ictx->noncesize = noncesize; | |
270 | ictx->ivsize = ivsize; | |
41fdab3d | 271 | ictx->countersize = countersize; |
23e353c8 JL |
272 | |
273 | err = crypto_init_spawn(&ictx->alg, alg, inst, | |
274 | CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC); | |
275 | if (err) | |
276 | goto err_free_inst; | |
277 | ||
278 | err = 0; | |
279 | inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; | |
280 | inst->alg.cra_priority = alg->cra_priority; | |
281 | inst->alg.cra_blocksize = 1; | |
0971eb0d | 282 | inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1); |
23e353c8 JL |
283 | inst->alg.cra_type = &crypto_blkcipher_type; |
284 | ||
285 | inst->alg.cra_blkcipher.ivsize = ivsize; | |
286 | inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize | |
287 | + noncesize; | |
288 | inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize | |
289 | + noncesize; | |
290 | ||
291 | inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx); | |
292 | ||
293 | inst->alg.cra_init = crypto_ctr_init_tfm; | |
294 | inst->alg.cra_exit = crypto_ctr_exit_tfm; | |
295 | ||
296 | inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey; | |
297 | inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt; | |
298 | inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt; | |
299 | ||
300 | err_free_inst: | |
301 | if (err) | |
302 | kfree(inst); | |
303 | ||
304 | out_put_alg: | |
305 | crypto_mod_put(alg); | |
306 | ||
307 | if (err) | |
308 | inst = ERR_PTR(err); | |
309 | ||
310 | return inst; | |
311 | } | |
312 | ||
313 | static void crypto_ctr_free(struct crypto_instance *inst) | |
314 | { | |
315 | struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst); | |
316 | ||
317 | crypto_drop_spawn(&ictx->alg); | |
318 | kfree(inst); | |
319 | } | |
320 | ||
321 | static struct crypto_template crypto_ctr_tmpl = { | |
322 | .name = "ctr", | |
323 | .alloc = crypto_ctr_alloc, | |
324 | .free = crypto_ctr_free, | |
325 | .module = THIS_MODULE, | |
326 | }; | |
327 | ||
328 | static int __init crypto_ctr_module_init(void) | |
329 | { | |
330 | return crypto_register_template(&crypto_ctr_tmpl); | |
331 | } | |
332 | ||
333 | static void __exit crypto_ctr_module_exit(void) | |
334 | { | |
335 | crypto_unregister_template(&crypto_ctr_tmpl); | |
336 | } | |
337 | ||
338 | module_init(crypto_ctr_module_init); | |
339 | module_exit(crypto_ctr_module_exit); | |
340 | ||
341 | MODULE_LICENSE("GPL"); | |
342 | MODULE_DESCRIPTION("CTR Counter block mode"); |