linux-stable/crypto/cbc.c
Ard Biesheuvel db91af0fbe crypto: algapi - make crypto_xor() and crypto_inc() alignment agnostic
Instead of unconditionally forcing 4 byte alignment for all generic
chaining modes that rely on crypto_xor() or crypto_inc() (which may
result in unnecessary copying of data when the underlying hardware
can perform unaligned accesses efficiently), make those functions
deal with unaligned input explicitly, but only if the Kconfig symbol
HAVE_EFFICIENT_UNALIGNED_ACCESS is set. This will allow us to drop
the alignmasks from the CBC, CMAC, CTR, CTS, PCBC and SEQIV drivers.

For crypto_inc(), this simply involves making the 4-byte stride
conditional on HAVE_EFFICIENT_UNALIGNED_ACCESS being set, given that
it typically operates on 16 byte buffers.

For crypto_xor(), an algorithm is implemented that simply runs through
the input using the largest strides possible if unaligned accesses are
allowed. If they are not, an optimal sequence of memory accesses is
emitted that takes the relative alignment of the input buffers into
account, e.g., if the relative misalignment of dst and src is 4 bytes,
the entire xor operation will be completed using 4 byte loads and stores
(modulo unaligned bits at the start and end). Note that all expressions
involving misalign are simply eliminated by the compiler when
HAVE_EFFICIENT_UNALIGNED_ACCESS is defined.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-02-11 17:52:28 +08:00

198 lines
4.8 KiB
C

/*
* CBC: Cipher Block Chaining mode
*
* Copyright (c) 2006-2016 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/cbc.h>
#include <crypto/internal/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/slab.h>
struct crypto_cbc_ctx {
struct crypto_cipher *child;
};
static int crypto_cbc_setkey(struct crypto_skcipher *parent, const u8 *key,
unsigned int keylen)
{
struct crypto_cbc_ctx *ctx = crypto_skcipher_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_skcipher_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_cipher_setkey(child, key, keylen);
crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
return err;
}
static inline void crypto_cbc_encrypt_one(struct crypto_skcipher *tfm,
const u8 *src, u8 *dst)
{
struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_cipher_encrypt_one(ctx->child, dst, src);
}
static int crypto_cbc_encrypt(struct skcipher_request *req)
{
return crypto_cbc_encrypt_walk(req, crypto_cbc_encrypt_one);
}
static inline void crypto_cbc_decrypt_one(struct crypto_skcipher *tfm,
const u8 *src, u8 *dst)
{
struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_cipher_decrypt_one(ctx->child, dst, src);
}
static int crypto_cbc_decrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct skcipher_walk walk;
int err;
err = skcipher_walk_virt(&walk, req, false);
while (walk.nbytes) {
err = crypto_cbc_decrypt_blocks(&walk, tfm,
crypto_cbc_decrypt_one);
err = skcipher_walk_done(&walk, err);
}
return err;
}
static int crypto_cbc_init_tfm(struct crypto_skcipher *tfm)
{
struct skcipher_instance *inst = skcipher_alg_instance(tfm);
struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
struct crypto_cbc_ctx *ctx = crypto_skcipher_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_cbc_exit_tfm(struct crypto_skcipher *tfm)
{
struct crypto_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_free_cipher(ctx->child);
}
static void crypto_cbc_free(struct skcipher_instance *inst)
{
crypto_drop_skcipher(skcipher_instance_ctx(inst));
kfree(inst);
}
static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct skcipher_instance *inst;
struct crypto_spawn *spawn;
struct crypto_alg *alg;
int err;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
if (err)
return err;
inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
if (!inst)
return -ENOMEM;
alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
CRYPTO_ALG_TYPE_MASK);
err = PTR_ERR(alg);
if (IS_ERR(alg))
goto err_free_inst;
spawn = skcipher_instance_ctx(inst);
err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
CRYPTO_ALG_TYPE_MASK);
crypto_mod_put(alg);
if (err)
goto err_free_inst;
err = crypto_inst_setname(skcipher_crypto_instance(inst), "cbc", alg);
if (err)
goto err_drop_spawn;
err = -EINVAL;
if (!is_power_of_2(alg->cra_blocksize))
goto err_drop_spawn;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;
inst->alg.base.cra_alignmask = alg->cra_alignmask;
inst->alg.ivsize = alg->cra_blocksize;
inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
inst->alg.base.cra_ctxsize = sizeof(struct crypto_cbc_ctx);
inst->alg.init = crypto_cbc_init_tfm;
inst->alg.exit = crypto_cbc_exit_tfm;
inst->alg.setkey = crypto_cbc_setkey;
inst->alg.encrypt = crypto_cbc_encrypt;
inst->alg.decrypt = crypto_cbc_decrypt;
inst->free = crypto_cbc_free;
err = skcipher_register_instance(tmpl, inst);
if (err)
goto err_drop_spawn;
out:
return err;
err_drop_spawn:
crypto_drop_spawn(spawn);
err_free_inst:
kfree(inst);
goto out;
}
static struct crypto_template crypto_cbc_tmpl = {
.name = "cbc",
.create = crypto_cbc_create,
.module = THIS_MODULE,
};
static int __init crypto_cbc_module_init(void)
{
return crypto_register_template(&crypto_cbc_tmpl);
}
static void __exit crypto_cbc_module_exit(void)
{
crypto_unregister_template(&crypto_cbc_tmpl);
}
module_init(crypto_cbc_module_init);
module_exit(crypto_cbc_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CBC block cipher algorithm");
MODULE_ALIAS_CRYPTO("cbc");