diff options
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/Makefile | 1 | ||||
| -rw-r--r-- | crypto/chainiv.c | 139 |
2 files changed, 140 insertions, 0 deletions
diff --git a/crypto/Makefile b/crypto/Makefile index 2a1883fabf42..4b2e0c387cc2 100644 --- a/crypto/Makefile +++ b/crypto/Makefile @@ -13,6 +13,7 @@ obj-$(CONFIG_CRYPTO_AEAD) += aead.o crypto_blkcipher-objs := ablkcipher.o crypto_blkcipher-objs += blkcipher.o obj-$(CONFIG_CRYPTO_BLKCIPHER) += crypto_blkcipher.o +obj-$(CONFIG_CRYPTO_BLKCIPHER) += chainiv.o crypto_hash-objs := hash.o obj-$(CONFIG_CRYPTO_HASH) += crypto_hash.o diff --git a/crypto/chainiv.c b/crypto/chainiv.c new file mode 100644 index 000000000000..38868d160b47 --- /dev/null +++ b/crypto/chainiv.c @@ -0,0 +1,139 @@ +/* + * chainiv: Chain IV Generator + * + * Generate IVs simply be using the last block of the previous encryption. + * This is mainly useful for CBC with a synchronous algorithm. + * + * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> + * + * 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/internal/skcipher.h> +#include <linux/err.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/random.h> +#include <linux/spinlock.h> +#include <linux/string.h> + +struct chainiv_ctx { + spinlock_t lock; + char iv[]; +}; + +static int chainiv_givencrypt(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); + unsigned int ivsize; + int err; + + ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); + ablkcipher_request_set_callback(subreq, req->creq.base.flags & + ~CRYPTO_TFM_REQ_MAY_SLEEP, + req->creq.base.complete, + req->creq.base.data); + ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst, + req->creq.nbytes, req->creq.info); + + spin_lock_bh(&ctx->lock); + + ivsize = crypto_ablkcipher_ivsize(geniv); + + memcpy(req->giv, ctx->iv, ivsize); + memcpy(subreq->info, ctx->iv, ivsize); + + err = crypto_ablkcipher_encrypt(subreq); + if (err) + goto unlock; + + memcpy(ctx->iv, subreq->info, ivsize); + +unlock: + spin_unlock_bh(&ctx->lock); + + return err; +} + +static int chainiv_givencrypt_first(struct skcipher_givcrypt_request *req) +{ + struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); + struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + + spin_lock_bh(&ctx->lock); + if (crypto_ablkcipher_crt(geniv)->givencrypt != + chainiv_givencrypt_first) + goto unlock; + + crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt; + get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv)); + +unlock: + spin_unlock_bh(&ctx->lock); + + return chainiv_givencrypt(req); +} + +static int chainiv_init(struct crypto_tfm *tfm) +{ + struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); + struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); + + spin_lock_init(&ctx->lock); + + tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); + + return skcipher_geniv_init(tfm); +} + +static struct crypto_template chainiv_tmpl; + +static struct crypto_instance *chainiv_alloc(struct rtattr **tb) +{ + struct crypto_instance *inst; + + inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(inst)) + goto out; + + inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first; + + inst->alg.cra_init = chainiv_init; + inst->alg.cra_exit = skcipher_geniv_exit; + + inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx) + + inst->alg.cra_ablkcipher.ivsize; + +out: + return inst; +} + +static struct crypto_template chainiv_tmpl = { + .name = "chainiv", + .alloc = chainiv_alloc, + .free = skcipher_geniv_free, + .module = THIS_MODULE, +}; + +static int __init chainiv_module_init(void) +{ + return crypto_register_template(&chainiv_tmpl); +} + +static void __exit chainiv_module_exit(void) +{ + crypto_unregister_template(&chainiv_tmpl); +} + +module_init(chainiv_module_init); +module_exit(chainiv_module_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Chain IV Generator"); |