diff options
Diffstat (limited to 'crypto/ctr.c')
| -rw-r--r-- | crypto/ctr.c | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/crypto/ctr.c b/crypto/ctr.c new file mode 100644 index 0000000..2d7425f --- /dev/null +++ b/crypto/ctr.c @@ -0,0 +1,422 @@ +/* + * CTR: Counter mode + * + * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + * + */ + +#include <crypto/algapi.h> +#include <crypto/ctr.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/random.h> +#include <linux/scatterlist.h> +#include <linux/slab.h> + +struct crypto_ctr_ctx { + struct crypto_cipher *child; +}; + +struct crypto_rfc3686_ctx { + struct crypto_blkcipher *child; + u8 nonce[CTR_RFC3686_NONCE_SIZE]; +}; + +static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key, + unsigned int keylen) +{ + struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent); + struct crypto_cipher *child = ctx->child; + int err; + + crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); + crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + err = crypto_cipher_setkey(child, key, keylen); + crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & + CRYPTO_TFM_RES_MASK); + + return err; +} + +static void crypto_ctr_crypt_final(struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + unsigned int bsize = crypto_cipher_blocksize(tfm); + unsigned long alignmask = crypto_cipher_alignmask(tfm); + u8 *ctrblk = walk->iv; + u8 tmp[bsize + alignmask]; + u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + unsigned int nbytes = walk->nbytes; + + crypto_cipher_encrypt_one(tfm, keystream, ctrblk); + crypto_xor(keystream, src, nbytes); + memcpy(dst, keystream, nbytes); + + crypto_inc(ctrblk, bsize); +} + +static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + unsigned int bsize = crypto_cipher_blocksize(tfm); + u8 *ctrblk = walk->iv; + u8 *src = walk->src.virt.addr; + u8 *dst = walk->dst.virt.addr; + unsigned int nbytes = walk->nbytes; + + do { + /* create keystream */ + fn(crypto_cipher_tfm(tfm), dst, ctrblk); + crypto_xor(dst, src, bsize); + + /* increment counter in counterblock */ + crypto_inc(ctrblk, bsize); + + src += bsize; + dst += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk, + struct crypto_cipher *tfm) +{ + void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = + crypto_cipher_alg(tfm)->cia_encrypt; + unsigned int bsize = crypto_cipher_blocksize(tfm); + unsigned long alignmask = crypto_cipher_alignmask(tfm); + unsigned int nbytes = walk->nbytes; + u8 *ctrblk = walk->iv; + u8 *src = walk->src.virt.addr; + u8 tmp[bsize + alignmask]; + u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); + + do { + /* create keystream */ + fn(crypto_cipher_tfm(tfm), keystream, ctrblk); + crypto_xor(src, keystream, bsize); + + /* increment counter in counterblock */ + crypto_inc(ctrblk, bsize); + + src += bsize; + } while ((nbytes -= bsize) >= bsize); + + return nbytes; +} + +static int crypto_ctr_crypt(struct blkcipher_desc *desc, + struct scatterlist *dst, struct scatterlist *src, + unsigned int nbytes) +{ + struct blkcipher_walk walk; + struct crypto_blkcipher *tfm = desc->tfm; + struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_cipher *child = ctx->child; + unsigned int bsize = crypto_cipher_blocksize(child); + int err; + + blkcipher_walk_init(&walk, dst, src, nbytes); + err = blkcipher_walk_virt_block(desc, &walk, bsize); + + while (walk.nbytes >= bsize) { + if (walk.src.virt.addr == walk.dst.virt.addr) + nbytes = crypto_ctr_crypt_inplace(&walk, child); + else + nbytes = crypto_ctr_crypt_segment(&walk, child); + + err = blkcipher_walk_done(desc, &walk, nbytes); + } + + if (walk.nbytes) { + crypto_ctr_crypt_final(&walk, child); + err = blkcipher_walk_done(desc, &walk, 0); + } + + return err; +} + +static int crypto_ctr_init_tfm(struct crypto_tfm *tfm) +{ + struct crypto_instance *inst = (void *)tfm->__crt_alg; + struct crypto_spawn *spawn = crypto_instance_ctx(inst); + struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); + struct crypto_cipher *cipher; + + cipher = crypto_spawn_cipher(spawn); + if (IS_ERR(cipher)) + return PTR_ERR(cipher); + + ctx->child = cipher; + + return 0; +} + +static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm) +{ + struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); + + crypto_free_cipher(ctx->child); +} + +static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb) +{ + struct crypto_instance *inst; + struct crypto_alg *alg; + int err; + + err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); + if (err) + return ERR_PTR(err); + + alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, + CRYPTO_ALG_TYPE_MASK); + if (IS_ERR(alg)) + return ERR_PTR(PTR_ERR(alg)); + + /* Block size must be >= 4 bytes. */ + err = -EINVAL; + if (alg->cra_blocksize < 4) + goto out_put_alg; + + /* If this is false we'd fail the alignment of crypto_inc. */ + if (alg->cra_blocksize % 4) + goto out_put_alg; + + inst = crypto_alloc_instance("ctr", alg); + if (IS_ERR(inst)) + goto out; + + inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; + inst->alg.cra_priority = alg->cra_priority; + inst->alg.cra_blocksize = 1; + inst->alg.cra_alignmask = alg->cra_alignmask | (__alignof__(u32) - 1); + inst->alg.cra_type = &crypto_blkcipher_type; + + inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; + inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize; + inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; + + inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx); + + inst->alg.cra_init = crypto_ctr_init_tfm; + inst->alg.cra_exit = crypto_ctr_exit_tfm; + + inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey; + inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt; + inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt; + +out: + crypto_mod_put(alg); + return inst; + +out_put_alg: + inst = ERR_PTR(err); + goto out; +} + +static void crypto_ctr_free(struct crypto_instance *inst) +{ + crypto_drop_spawn(crypto_instance_ctx(inst)); + kfree(inst); +} + +static struct crypto_template crypto_ctr_tmpl = { + .name = "ctr", + .alloc = crypto_ctr_alloc, + .free = crypto_ctr_free, + .module = THIS_MODULE, +}; + +static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key, + unsigned int keylen) +{ + struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent); + struct crypto_blkcipher *child = ctx->child; + int err; + + /* the nonce is stored in bytes at end of key */ + if (keylen < CTR_RFC3686_NONCE_SIZE) + return -EINVAL; + + memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), + CTR_RFC3686_NONCE_SIZE); + + keylen -= CTR_RFC3686_NONCE_SIZE; + + crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); + crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) & + CRYPTO_TFM_REQ_MASK); + err = crypto_blkcipher_setkey(child, key, keylen); + crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) & + CRYPTO_TFM_RES_MASK); + + return err; +} + +static int crypto_rfc3686_crypt(struct blkcipher_desc *desc, + struct scatterlist *dst, + struct scatterlist *src, unsigned int nbytes) +{ + struct crypto_blkcipher *tfm = desc->tfm; + struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm); + struct crypto_blkcipher *child = ctx->child; + unsigned long alignmask = crypto_blkcipher_alignmask(tfm); + u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask]; + u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1); + u8 *info = desc->info; + int err; + + /* set up counter block */ + memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); + memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE); + + /* initialize counter portion of counter block */ + *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = + cpu_to_be32(1); + + desc->tfm = child; + desc->info = iv; + err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes); + desc->tfm = tfm; + desc->info = info; + + return err; +} + +static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm) +{ + struct crypto_instance *inst = (void *)tfm->__crt_alg; + struct crypto_spawn *spawn = crypto_instance_ctx(inst); + struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm); + struct crypto_blkcipher *cipher; + + cipher = crypto_spawn_blkcipher(spawn); + if (IS_ERR(cipher)) + return PTR_ERR(cipher); + + ctx->child = cipher; + + return 0; +} + +static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm) +{ + struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm); + + crypto_free_blkcipher(ctx->child); +} + +static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb) +{ + struct crypto_instance *inst; + struct crypto_alg *alg; + int err; + + err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); + if (err) + return ERR_PTR(err); + + alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER, + CRYPTO_ALG_TYPE_MASK); + err = PTR_ERR(alg); + if (IS_ERR(alg)) + return ERR_PTR(err); + + /* We only support 16-byte blocks. */ + err = -EINVAL; + if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE) + goto out_put_alg; + + /* Not a stream cipher? */ + if (alg->cra_blocksize != 1) + goto out_put_alg; + + inst = crypto_alloc_instance("rfc3686", alg); + if (IS_ERR(inst)) + goto out; + + inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; + inst->alg.cra_priority = alg->cra_priority; + inst->alg.cra_blocksize = 1; + inst->alg.cra_alignmask = alg->cra_alignmask; + inst->alg.cra_type = &crypto_blkcipher_type; + + inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE; + inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize + + CTR_RFC3686_NONCE_SIZE; + inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize + + CTR_RFC3686_NONCE_SIZE; + + inst->alg.cra_blkcipher.geniv = "seqiv"; + + inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); + + inst->alg.cra_init = crypto_rfc3686_init_tfm; + inst->alg.cra_exit = crypto_rfc3686_exit_tfm; + + inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey; + inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt; + inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt; + +out: + crypto_mod_put(alg); + return inst; + +out_put_alg: + inst = ERR_PTR(err); + goto out; +} + +static struct crypto_template crypto_rfc3686_tmpl = { + .name = "rfc3686", + .alloc = crypto_rfc3686_alloc, + .free = crypto_ctr_free, + .module = THIS_MODULE, +}; + +static int __init crypto_ctr_module_init(void) +{ + int err; + + err = crypto_register_template(&crypto_ctr_tmpl); + if (err) + goto out; + + err = crypto_register_template(&crypto_rfc3686_tmpl); + if (err) + goto out_drop_ctr; + +out: + return err; + +out_drop_ctr: + crypto_unregister_template(&crypto_ctr_tmpl); + goto out; +} + +static void __exit crypto_ctr_module_exit(void) +{ + crypto_unregister_template(&crypto_rfc3686_tmpl); + crypto_unregister_template(&crypto_ctr_tmpl); +} + +module_init(crypto_ctr_module_init); +module_exit(crypto_ctr_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("CTR Counter block mode"); +MODULE_ALIAS("rfc3686"); |
