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 inline void __ctr_inc_byte(u8 *a, unsigned int size)
39 for (; size; size--) {
47 static void ctr_inc_quad(u8 *a, unsigned int size)
49 __be32 *b = (__be32 *)(a + size);
52 for (; size >= 4; size -=4) {
53 c = be32_to_cpu(*--b) + 1;
59 __ctr_inc_byte(a, size);
62 static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
68 static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
73 for (; bs >= 4; bs -= 4)
76 xor_byte((u8 *)a, (u8 *)b, bs);
79 static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
82 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
83 struct crypto_cipher *child = ctx->child;
84 struct ctr_instance_ctx *ictx =
85 crypto_instance_ctx(crypto_tfm_alg_instance(parent));
86 unsigned int noncelen = ictx->noncesize;
89 /* the nonce is stored in bytes at end of key */
90 if (keylen < noncelen)
93 memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);
97 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
98 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
100 err = crypto_cipher_setkey(child, key, keylen);
101 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
102 CRYPTO_TFM_RES_MASK);
107 static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
108 struct crypto_cipher *tfm, u8 *ctrblk,
109 unsigned int countersize)
111 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
112 crypto_cipher_alg(tfm)->cia_encrypt;
113 unsigned int bsize = crypto_cipher_blocksize(tfm);
114 unsigned long alignmask = crypto_cipher_alignmask(tfm);
115 u8 ks[bsize + alignmask];
116 u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
117 u8 *src = walk->src.virt.addr;
118 u8 *dst = walk->dst.virt.addr;
119 unsigned int nbytes = walk->nbytes;
122 /* create keystream */
123 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
124 xor_quad(keystream, src, min(nbytes, bsize));
126 /* copy result into dst */
127 memcpy(dst, keystream, min(nbytes, bsize));
129 /* increment counter in counterblock */
130 ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
144 static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
145 struct crypto_cipher *tfm, u8 *ctrblk,
146 unsigned int countersize)
148 void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
149 crypto_cipher_alg(tfm)->cia_encrypt;
150 unsigned int bsize = crypto_cipher_blocksize(tfm);
151 unsigned long alignmask = crypto_cipher_alignmask(tfm);
152 unsigned int nbytes = walk->nbytes;
153 u8 *src = walk->src.virt.addr;
154 u8 ks[bsize + alignmask];
155 u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
158 /* create keystream */
159 fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
160 xor_quad(src, keystream, min(nbytes, bsize));
162 /* increment counter in counterblock */
163 ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
176 static int crypto_ctr_crypt(struct blkcipher_desc *desc,
177 struct scatterlist *dst, struct scatterlist *src,
180 struct blkcipher_walk walk;
181 struct crypto_blkcipher *tfm = desc->tfm;
182 struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
183 struct crypto_cipher *child = ctx->child;
184 unsigned int bsize = crypto_cipher_blocksize(child);
185 struct ctr_instance_ctx *ictx =
186 crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
187 unsigned long alignmask = crypto_cipher_alignmask(child);
188 u8 cblk[bsize + alignmask];
189 u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
192 blkcipher_walk_init(&walk, dst, src, nbytes);
193 err = blkcipher_walk_virt_block(desc, &walk, bsize);
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);
200 /* initialize counter portion of counter block */
201 ctr_inc_quad(counterblk + (bsize - ictx->countersize),
204 while (walk.nbytes) {
205 if (walk.src.virt.addr == walk.dst.virt.addr)
206 nbytes = crypto_ctr_crypt_inplace(&walk, child,
210 nbytes = crypto_ctr_crypt_segment(&walk, child,
214 err = blkcipher_walk_done(desc, &walk, nbytes);
219 static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
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;
226 ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
230 cipher = crypto_spawn_cipher(&ictx->alg);
232 return PTR_ERR(cipher);
239 static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
241 struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
244 crypto_free_cipher(ctx->child);
247 static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
249 struct crypto_instance *inst;
250 struct crypto_alg *alg;
251 struct ctr_instance_ctx *ictx;
252 unsigned int noncesize;
254 unsigned int countersize;
257 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
261 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
262 CRYPTO_ALG_TYPE_MASK);
264 return ERR_PTR(PTR_ERR(alg));
266 err = crypto_attr_u32(tb[2], &noncesize);
270 err = crypto_attr_u32(tb[3], &ivsize);
274 err = crypto_attr_u32(tb[4], &countersize);
278 /* verify size of nonce + iv + counter
279 * counter must be >= 4 bytes.
282 if (((noncesize + ivsize + countersize) < alg->cra_blocksize) ||
283 ((noncesize + ivsize) > alg->cra_blocksize) ||
284 (countersize > alg->cra_blocksize) || (countersize < 4))
287 inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
293 if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
294 "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize,
295 ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
299 if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
300 "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize,
301 ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
305 ictx = crypto_instance_ctx(inst);
306 ictx->noncesize = noncesize;
307 ictx->ivsize = ivsize;
308 ictx->countersize = countersize;
310 err = crypto_init_spawn(&ictx->alg, alg, inst,
311 CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
316 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
317 inst->alg.cra_priority = alg->cra_priority;
318 inst->alg.cra_blocksize = 1;
319 inst->alg.cra_alignmask = 3;
320 inst->alg.cra_type = &crypto_blkcipher_type;
322 inst->alg.cra_blkcipher.ivsize = ivsize;
323 inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
325 inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
328 inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
330 inst->alg.cra_init = crypto_ctr_init_tfm;
331 inst->alg.cra_exit = crypto_ctr_exit_tfm;
333 inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
334 inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
335 inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
350 static void crypto_ctr_free(struct crypto_instance *inst)
352 struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
354 crypto_drop_spawn(&ictx->alg);
358 static struct crypto_template crypto_ctr_tmpl = {
360 .alloc = crypto_ctr_alloc,
361 .free = crypto_ctr_free,
362 .module = THIS_MODULE,
365 static int __init crypto_ctr_module_init(void)
367 return crypto_register_template(&crypto_ctr_tmpl);
370 static void __exit crypto_ctr_module_exit(void)
372 crypto_unregister_template(&crypto_ctr_tmpl);
375 module_init(crypto_ctr_module_init);
376 module_exit(crypto_ctr_module_exit);
378 MODULE_LICENSE("GPL");
379 MODULE_DESCRIPTION("CTR Counter block mode");