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yaml --- r: 75971 b: refs/heads/master c: 7f47073 h: refs/heads/master i: 75969: 7f8c9f2 75967: 4b4532c v: v3
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Herbert Xu
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Jan 10, 2008
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/* | ||
* 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. | ||
* | ||
*/ | ||
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#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> | ||
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struct chainiv_ctx { | ||
spinlock_t lock; | ||
char iv[]; | ||
}; | ||
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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; | ||
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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); | ||
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spin_lock_bh(&ctx->lock); | ||
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ivsize = crypto_ablkcipher_ivsize(geniv); | ||
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memcpy(req->giv, ctx->iv, ivsize); | ||
memcpy(subreq->info, ctx->iv, ivsize); | ||
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err = crypto_ablkcipher_encrypt(subreq); | ||
if (err) | ||
goto unlock; | ||
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memcpy(ctx->iv, subreq->info, ivsize); | ||
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unlock: | ||
spin_unlock_bh(&ctx->lock); | ||
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return err; | ||
} | ||
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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); | ||
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spin_lock_bh(&ctx->lock); | ||
if (crypto_ablkcipher_crt(geniv)->givencrypt != | ||
chainiv_givencrypt_first) | ||
goto unlock; | ||
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crypto_ablkcipher_crt(geniv)->givencrypt = chainiv_givencrypt; | ||
get_random_bytes(ctx->iv, crypto_ablkcipher_ivsize(geniv)); | ||
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unlock: | ||
spin_unlock_bh(&ctx->lock); | ||
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return chainiv_givencrypt(req); | ||
} | ||
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static int chainiv_init(struct crypto_tfm *tfm) | ||
{ | ||
struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); | ||
struct chainiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | ||
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spin_lock_init(&ctx->lock); | ||
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tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); | ||
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return skcipher_geniv_init(tfm); | ||
} | ||
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static struct crypto_template chainiv_tmpl; | ||
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static struct crypto_instance *chainiv_alloc(struct rtattr **tb) | ||
{ | ||
struct crypto_instance *inst; | ||
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inst = skcipher_geniv_alloc(&chainiv_tmpl, tb, 0, | ||
CRYPTO_ALG_ASYNC); | ||
if (IS_ERR(inst)) | ||
goto out; | ||
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inst->alg.cra_ablkcipher.givencrypt = chainiv_givencrypt_first; | ||
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inst->alg.cra_init = chainiv_init; | ||
inst->alg.cra_exit = skcipher_geniv_exit; | ||
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inst->alg.cra_ctxsize = sizeof(struct chainiv_ctx) + | ||
inst->alg.cra_ablkcipher.ivsize; | ||
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out: | ||
return inst; | ||
} | ||
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static struct crypto_template chainiv_tmpl = { | ||
.name = "chainiv", | ||
.alloc = chainiv_alloc, | ||
.free = skcipher_geniv_free, | ||
.module = THIS_MODULE, | ||
}; | ||
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static int __init chainiv_module_init(void) | ||
{ | ||
return crypto_register_template(&chainiv_tmpl); | ||
} | ||
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static void __exit chainiv_module_exit(void) | ||
{ | ||
crypto_unregister_template(&chainiv_tmpl); | ||
} | ||
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module_init(chainiv_module_init); | ||
module_exit(chainiv_module_exit); | ||
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MODULE_LICENSE("GPL"); | ||
MODULE_DESCRIPTION("Chain IV Generator"); |