4 * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
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)
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>
22 struct ctr_instance_ctx {
23 struct crypto_spawn alg;
24 unsigned int noncesize;
26 unsigned int countersize;
29 struct crypto_ctr_ctx {
30 struct crypto_cipher *child;
34 static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
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;
44 /* the nonce is stored in bytes at end of key */
45 if (keylen < noncelen)
48 memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);
52 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
53 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
55 err = crypto_cipher_setkey(child, key, keylen);
56 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
62 static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
63 struct crypto_cipher *tfm, u8 *ctrblk,
64 unsigned int countersize)
66 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
67 crypto_cipher_alg(tfm)->cia_encrypt;
68 unsigned int bsize = crypto_cipher_blocksize(tfm);
69 unsigned long alignmask = crypto_cipher_alignmask(tfm) |
70 (__alignof__(u32) - 1);
71 u8 ks[bsize + alignmask];
72 u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
73 u8 *src = walk->src.virt.addr;
74 u8 *dst = walk->dst.virt.addr;
75 unsigned int nbytes = walk->nbytes;
78 /* create keystream */
79 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
80 crypto_xor(keystream, src, min(nbytes, bsize));
82 /* copy result into dst */
83 memcpy(dst, keystream, min(nbytes, bsize));
85 /* increment counter in counterblock */
86 crypto_inc(ctrblk + bsize - countersize, countersize);
100 static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
101 struct crypto_cipher *tfm, u8 *ctrblk,
102 unsigned int countersize)
104 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
105 crypto_cipher_alg(tfm)->cia_encrypt;
106 unsigned int bsize = crypto_cipher_blocksize(tfm);
107 unsigned long alignmask = crypto_cipher_alignmask(tfm) |
108 (__alignof__(u32) - 1);
109 unsigned int nbytes = walk->nbytes;
110 u8 *src = walk->src.virt.addr;
111 u8 ks[bsize + alignmask];
112 u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
115 /* create keystream */
116 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
117 crypto_xor(src, keystream, min(nbytes, bsize));
119 /* increment counter in counterblock */
120 crypto_inc(ctrblk + bsize - countersize, countersize);
133 static int crypto_ctr_crypt(struct blkcipher_desc *desc,
134 struct scatterlist *dst, struct scatterlist *src,
137 struct blkcipher_walk walk;
138 struct crypto_blkcipher *tfm = desc->tfm;
139 struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
140 struct crypto_cipher *child = ctx->child;
141 unsigned int bsize = crypto_cipher_blocksize(child);
142 struct ctr_instance_ctx *ictx =
143 crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
144 unsigned long alignmask = crypto_cipher_alignmask(child) |
145 (__alignof__(u32) - 1);
146 u8 cblk[bsize + alignmask];
147 u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
150 blkcipher_walk_init(&walk, dst, src, nbytes);
151 err = blkcipher_walk_virt_block(desc, &walk, bsize);
153 /* set up counter block */
154 memset(counterblk, 0 , bsize);
155 memcpy(counterblk, ctx->nonce, ictx->noncesize);
156 memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize);
158 /* initialize counter portion of counter block */
159 crypto_inc(counterblk + bsize - ictx->countersize, ictx->countersize);
161 while (walk.nbytes) {
162 if (walk.src.virt.addr == walk.dst.virt.addr)
163 nbytes = crypto_ctr_crypt_inplace(&walk, child,
167 nbytes = crypto_ctr_crypt_segment(&walk, child,
171 err = blkcipher_walk_done(desc, &walk, nbytes);
176 static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
178 struct crypto_instance *inst = (void *)tfm->__crt_alg;
179 struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
180 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
181 struct crypto_cipher *cipher;
183 ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
187 cipher = crypto_spawn_cipher(&ictx->alg);
189 return PTR_ERR(cipher);
196 static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
198 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
201 crypto_free_cipher(ctx->child);
204 static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
206 struct crypto_instance *inst;
207 struct crypto_alg *alg;
208 struct ctr_instance_ctx *ictx;
209 unsigned int noncesize;
211 unsigned int countersize;
214 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
218 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
219 CRYPTO_ALG_TYPE_MASK);
221 return ERR_PTR(PTR_ERR(alg));
223 err = crypto_attr_u32(tb[2], &noncesize);
227 err = crypto_attr_u32(tb[3], &ivsize);
231 err = crypto_attr_u32(tb[4], &countersize);
235 /* verify size of nonce + iv + counter
236 * counter must be >= 4 bytes.
239 if (((noncesize + ivsize + countersize) < alg->cra_blocksize) ||
240 ((noncesize + ivsize) > alg->cra_blocksize) ||
241 (countersize > alg->cra_blocksize) || (countersize < 4))
244 /* If this is false we'd fail the alignment of crypto_inc. */
245 if ((alg->cra_blocksize - countersize) % 4)
248 inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
254 if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
255 "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize,
256 ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
260 if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
261 "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize,
262 ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
266 ictx = crypto_instance_ctx(inst);
267 ictx->noncesize = noncesize;
268 ictx->ivsize = ivsize;
269 ictx->countersize = countersize;
271 err = crypto_init_spawn(&ictx->alg, alg, inst,
272 CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
277 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
278 inst->alg.cra_priority = alg->cra_priority;
279 inst->alg.cra_blocksize = 1;
280 inst->alg.cra_alignmask = __alignof__(u32) - 1;
281 inst->alg.cra_type = &crypto_blkcipher_type;
283 inst->alg.cra_blkcipher.ivsize = ivsize;
284 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
286 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
289 inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
291 inst->alg.cra_init = crypto_ctr_init_tfm;
292 inst->alg.cra_exit = crypto_ctr_exit_tfm;
294 inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
295 inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
296 inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
311 static void crypto_ctr_free(struct crypto_instance *inst)
313 struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
315 crypto_drop_spawn(&ictx->alg);
319 static struct crypto_template crypto_ctr_tmpl = {
321 .alloc = crypto_ctr_alloc,
322 .free = crypto_ctr_free,
323 .module = THIS_MODULE,
326 static int __init crypto_ctr_module_init(void)
328 return crypto_register_template(&crypto_ctr_tmpl);
331 static void __exit crypto_ctr_module_exit(void)
333 crypto_unregister_template(&crypto_ctr_tmpl);
336 module_init(crypto_ctr_module_init);
337 module_exit(crypto_ctr_module_exit);
339 MODULE_LICENSE("GPL");
340 MODULE_DESCRIPTION("CTR Counter block mode");