aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/ctr.c
diff options
context:
space:
mode:
Diffstat (limited to 'crypto/ctr.c')
-rw-r--r--crypto/ctr.c369
1 files changed, 369 insertions, 0 deletions
diff --git a/crypto/ctr.c b/crypto/ctr.c
new file mode 100644
index 000000000000..810d5ec2d5d2
--- /dev/null
+++ b/crypto/ctr.c
@@ -0,0 +1,369 @@
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
22struct ctr_instance_ctx {
23 struct crypto_spawn alg;
24 unsigned int noncesize;
25 unsigned int ivsize;
26};
27
28struct crypto_ctr_ctx {
29 struct crypto_cipher *child;
30 u8 *nonce;
31};
32
33static inline void __ctr_inc_byte(u8 *a, unsigned int size)
34{
35 u8 *b = (a + size);
36 u8 c;
37
38 for (; size; size--) {
39 c = *--b + 1;
40 *b = c;
41 if (c)
42 break;
43 }
44}
45
46static void ctr_inc_quad(u8 *a, unsigned int size)
47{
48 __be32 *b = (__be32 *)(a + size);
49 u32 c;
50
51 for (; size >= 4; size -=4) {
52 c = be32_to_cpu(*--b) + 1;
53 *b = cpu_to_be32(c);
54 if (c)
55 return;
56 }
57
58 __ctr_inc_byte(a, size);
59}
60
61static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
62{
63 for (; bs; bs--)
64 *a++ ^= *b++;
65}
66
67static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
68{
69 u32 *a = (u32 *)dst;
70 u32 *b = (u32 *)src;
71
72 for (; bs >= 4; bs -= 4)
73 *a++ ^= *b++;
74
75 xor_byte((u8 *)a, (u8 *)b, bs);
76}
77
78static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
79 unsigned int keylen)
80{
81 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
82 struct crypto_cipher *child = ctx->child;
83 struct ctr_instance_ctx *ictx =
84 crypto_instance_ctx(crypto_tfm_alg_instance(parent));
85 unsigned int noncelen = ictx->noncesize;
86 int err = 0;
87
88 /* the nonce is stored in bytes at end of key */
89 if (keylen < noncelen)
90 return -EINVAL;
91
92 memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);
93
94 keylen -= noncelen;
95
96 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
97 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
98 CRYPTO_TFM_REQ_MASK);
99 err = crypto_cipher_setkey(child, key, keylen);
100 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
101 CRYPTO_TFM_RES_MASK);
102
103 return err;
104}
105
106static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
107 struct crypto_cipher *tfm, u8 *ctrblk,
108 unsigned int countersize)
109{
110 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
111 crypto_cipher_alg(tfm)->cia_encrypt;
112 unsigned int bsize = crypto_cipher_blocksize(tfm);
113 unsigned long alignmask = crypto_cipher_alignmask(tfm);
114 u8 ks[bsize + alignmask];
115 u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
116 u8 *src = walk->src.virt.addr;
117 u8 *dst = walk->dst.virt.addr;
118 unsigned int nbytes = walk->nbytes;
119
120 do {
121 /* create keystream */
122 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
123 xor_quad(keystream, src, min(nbytes, bsize));
124
125 /* copy result into dst */
126 memcpy(dst, keystream, min(nbytes, bsize));
127
128 /* increment counter in counterblock */
129 ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
130
131 if (nbytes < bsize)
132 break;
133
134 src += bsize;
135 dst += bsize;
136 nbytes -= bsize;
137
138 } while (nbytes);
139
140 return 0;
141}
142
143static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
144 struct crypto_cipher *tfm, u8 *ctrblk,
145 unsigned int countersize)
146{
147 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
148 crypto_cipher_alg(tfm)->cia_encrypt;
149 unsigned int bsize = crypto_cipher_blocksize(tfm);
150 unsigned long alignmask = crypto_cipher_alignmask(tfm);
151 unsigned int nbytes = walk->nbytes;
152 u8 *src = walk->src.virt.addr;
153 u8 ks[bsize + alignmask];
154 u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
155
156 do {
157 /* create keystream */
158 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
159 xor_quad(src, keystream, min(nbytes, bsize));
160
161 /* increment counter in counterblock */
162 ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
163
164 if (nbytes < bsize)
165 break;
166
167 src += bsize;
168 nbytes -= bsize;
169
170 } while (nbytes);
171
172 return 0;
173}
174
175static int crypto_ctr_crypt(struct blkcipher_desc *desc,
176 struct scatterlist *dst, struct scatterlist *src,
177 unsigned int nbytes)
178{
179 struct blkcipher_walk walk;
180 struct crypto_blkcipher *tfm = desc->tfm;
181 struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
182 struct crypto_cipher *child = ctx->child;
183 unsigned int bsize = crypto_cipher_blocksize(child);
184 struct ctr_instance_ctx *ictx =
185 crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
186 unsigned long alignmask = crypto_cipher_alignmask(child);
187 u8 cblk[bsize + alignmask];
188 u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
189 unsigned int countersize;
190 int err;
191
192 blkcipher_walk_init(&walk, dst, src, nbytes);
193 err = blkcipher_walk_virt_block(desc, &walk, bsize);
194
195 /* set up counter block */
196 memset(counterblk, 0 , bsize);
197 memcpy(counterblk, ctx->nonce, ictx->noncesize);
198 memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize);
199
200 /* initialize counter portion of counter block */
201 countersize = bsize - ictx->noncesize - ictx->ivsize;
202 ctr_inc_quad(counterblk + (bsize - countersize), countersize);
203
204 while (walk.nbytes) {
205 if (walk.src.virt.addr == walk.dst.virt.addr)
206 nbytes = crypto_ctr_crypt_inplace(&walk, child,
207 counterblk,
208 countersize);
209 else
210 nbytes = crypto_ctr_crypt_segment(&walk, child,
211 counterblk,
212 countersize);
213
214 err = blkcipher_walk_done(desc, &walk, nbytes);
215 }
216 return err;
217}
218
219static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
220{
221 struct crypto_instance *inst = (void *)tfm->__crt_alg;
222 struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
223 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
224 struct crypto_cipher *cipher;
225
226 ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
227 if (!ctx->nonce)
228 return -ENOMEM;
229
230 cipher = crypto_spawn_cipher(&ictx->alg);
231 if (IS_ERR(cipher))
232 return PTR_ERR(cipher);
233
234 ctx->child = cipher;
235
236 return 0;
237}
238
239static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
240{
241 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
242
243 kfree(ctx->nonce);
244 crypto_free_cipher(ctx->child);
245}
246
247static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
248{
249 struct crypto_instance *inst;
250 struct crypto_alg *alg;
251 struct ctr_instance_ctx *ictx;
252 unsigned int noncesize;
253 unsigned int ivsize;
254 int err;
255
256 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
257 if (err)
258 return ERR_PTR(err);
259
260 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
261 CRYPTO_ALG_TYPE_MASK);
262 if (IS_ERR(alg))
263 return ERR_PTR(PTR_ERR(alg));
264
265 err = crypto_attr_u32(tb[2], &noncesize);
266 if (err)
267 goto out_put_alg;
268
269 err = crypto_attr_u32(tb[3], &ivsize);
270 if (err)
271 goto out_put_alg;
272
273 /* verify size of nonce + iv + counter */
274 err = -EINVAL;
275 if ((noncesize + ivsize) >= alg->cra_blocksize)
276 goto out_put_alg;
277
278 inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
279 err = -ENOMEM;
280 if (!inst)
281 goto out_put_alg;
282
283 err = -ENAMETOOLONG;
284 if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
285 "ctr(%s,%u,%u)", alg->cra_name, noncesize,
286 ivsize) >= CRYPTO_MAX_ALG_NAME) {
287 goto err_free_inst;
288 }
289
290 if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
291 "ctr(%s,%u,%u)", alg->cra_driver_name, noncesize,
292 ivsize) >= CRYPTO_MAX_ALG_NAME) {
293 goto err_free_inst;
294 }
295
296 ictx = crypto_instance_ctx(inst);
297 ictx->noncesize = noncesize;
298 ictx->ivsize = ivsize;
299
300 err = crypto_init_spawn(&ictx->alg, alg, inst,
301 CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
302 if (err)
303 goto err_free_inst;
304
305 err = 0;
306 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
307 inst->alg.cra_priority = alg->cra_priority;
308 inst->alg.cra_blocksize = 1;
309 inst->alg.cra_alignmask = 3;
310 inst->alg.cra_type = &crypto_blkcipher_type;
311
312 inst->alg.cra_blkcipher.ivsize = ivsize;
313 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
314 + noncesize;
315 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
316 + noncesize;
317
318 inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
319
320 inst->alg.cra_init = crypto_ctr_init_tfm;
321 inst->alg.cra_exit = crypto_ctr_exit_tfm;
322
323 inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
324 inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
325 inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
326
327err_free_inst:
328 if (err)
329 kfree(inst);
330
331out_put_alg:
332 crypto_mod_put(alg);
333
334 if (err)
335 inst = ERR_PTR(err);
336
337 return inst;
338}
339
340static void crypto_ctr_free(struct crypto_instance *inst)
341{
342 struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
343
344 crypto_drop_spawn(&ictx->alg);
345 kfree(inst);
346}
347
348static struct crypto_template crypto_ctr_tmpl = {
349 .name = "ctr",
350 .alloc = crypto_ctr_alloc,
351 .free = crypto_ctr_free,
352 .module = THIS_MODULE,
353};
354
355static int __init crypto_ctr_module_init(void)
356{
357 return crypto_register_template(&crypto_ctr_tmpl);
358}
359
360static void __exit crypto_ctr_module_exit(void)
361{
362 crypto_unregister_template(&crypto_ctr_tmpl);
363}
364
365module_init(crypto_ctr_module_init);
366module_exit(crypto_ctr_module_exit);
367
368MODULE_LICENSE("GPL");
369MODULE_DESCRIPTION("CTR Counter block mode");
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-04 01:05:11 -0500