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linux/crypto/ctr.c
Ard Biesheuvel 45fe93dff2 crypto: algapi - make crypto_xor() take separate dst and src arguments 
There are quite a number of occurrences in the kernel of the pattern

  if (dst != src)
          memcpy(dst, src, walk.total % AES_BLOCK_SIZE);
  crypto_xor(dst, final, walk.total % AES_BLOCK_SIZE);

or

  crypto_xor(keystream, src, nbytes);
  memcpy(dst, keystream, nbytes);

where crypto_xor() is preceded or followed by a memcpy() invocation
that is only there because crypto_xor() uses its output parameter as
one of the inputs. To avoid having to add new instances of this pattern
in the arm64 code, which will be refactored to implement non-SIMD
fallbacks, add an alternative implementation called crypto_xor_cpy(),
taking separate input and output arguments. This removes the need for
the separate memcpy().

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-08-04 09:27:15 +08:00

488 lines
13 KiB
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/*
* 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 <crypto/internal/skcipher.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_skcipher *child;
u8 nonce[CTR_RFC3686_NONCE_SIZE];
};
struct crypto_rfc3686_req_ctx {
u8 iv[CTR_RFC3686_BLOCK_SIZE];
struct skcipher_request subreq CRYPTO_MINALIGN_ATTR;
};
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_cpy(dst, keystream, src, 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_attr_type *algt;
struct crypto_alg *alg;
u32 mask;
int err;
err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
if (err)
return ERR_PTR(err);
algt = crypto_get_attr_type(tb);
if (IS_ERR(algt))
return ERR_CAST(algt);
mask = CRYPTO_ALG_TYPE_MASK |
crypto_requires_off(algt->type, algt->mask,
CRYPTO_ALG_NEED_FALLBACK);
alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, mask);
if (IS_ERR(alg))
return ERR_CAST(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;
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;
inst->alg.cra_blkcipher.geniv = "chainiv";
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_skcipher *parent,
const u8 *key, unsigned int keylen)
{
struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent);
struct crypto_skcipher *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_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
CRYPTO_TFM_REQ_MASK);
err = crypto_skcipher_setkey(child, key, keylen);
crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
CRYPTO_TFM_RES_MASK);
return err;
}
static int crypto_rfc3686_crypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
struct crypto_skcipher *child = ctx->child;
unsigned long align = crypto_skcipher_alignmask(tfm);
struct crypto_rfc3686_req_ctx *rctx =
(void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1);
struct skcipher_request *subreq = &rctx->subreq;
u8 *iv = rctx->iv;
/* set up counter block */
memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE);
/* initialize counter portion of counter block */
*(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
cpu_to_be32(1);
skcipher_request_set_tfm(subreq, child);
skcipher_request_set_callback(subreq, req->base.flags,
req->base.complete, req->base.data);
skcipher_request_set_crypt(subreq, req->src, req->dst,
req->cryptlen, iv);
return crypto_skcipher_encrypt(subreq);
}
static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm)
{
struct skcipher_instance *inst = skcipher_alg_instance(tfm);
struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
struct crypto_skcipher *cipher;
unsigned long align;
unsigned int reqsize;
cipher = crypto_spawn_skcipher(spawn);
if (IS_ERR(cipher))
return PTR_ERR(cipher);
ctx->child = cipher;
align = crypto_skcipher_alignmask(tfm);
align &= ~(crypto_tfm_ctx_alignment() - 1);
reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) +
crypto_skcipher_reqsize(cipher);
crypto_skcipher_set_reqsize(tfm, reqsize);
return 0;
}
static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm)
{
struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
crypto_free_skcipher(ctx->child);
}
static void crypto_rfc3686_free(struct skcipher_instance *inst)
{
struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
crypto_drop_skcipher(spawn);
kfree(inst);
}
static int crypto_rfc3686_create(struct crypto_template *tmpl,
struct rtattr **tb)
{
struct crypto_attr_type *algt;
struct skcipher_instance *inst;
struct skcipher_alg *alg;
struct crypto_skcipher_spawn *spawn;
const char *cipher_name;
u32 mask;
int err;
algt = crypto_get_attr_type(tb);
if (IS_ERR(algt))
return PTR_ERR(algt);
if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
return -EINVAL;
cipher_name = crypto_attr_alg_name(tb[1]);
if (IS_ERR(cipher_name))
return PTR_ERR(cipher_name);
inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
if (!inst)
return -ENOMEM;
mask = crypto_requires_sync(algt->type, algt->mask) |
crypto_requires_off(algt->type, algt->mask,
CRYPTO_ALG_NEED_FALLBACK);
spawn = skcipher_instance_ctx(inst);
crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
err = crypto_grab_skcipher(spawn, cipher_name, 0, mask);
if (err)
goto err_free_inst;
alg = crypto_spawn_skcipher_alg(spawn);
/* We only support 16-byte blocks. */
err = -EINVAL;
if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE)
goto err_drop_spawn;
/* Not a stream cipher? */
if (alg->base.cra_blocksize != 1)
goto err_drop_spawn;
err = -ENAMETOOLONG;
if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
"rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
goto err_drop_spawn;
if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
"rfc3686(%s)", alg->base.cra_driver_name) >=
CRYPTO_MAX_ALG_NAME)
goto err_drop_spawn;
inst->alg.base.cra_priority = alg->base.cra_priority;
inst->alg.base.cra_blocksize = 1;
inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
inst->alg.ivsize = CTR_RFC3686_IV_SIZE;
inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg);
inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
CTR_RFC3686_NONCE_SIZE;
inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
CTR_RFC3686_NONCE_SIZE;
inst->alg.setkey = crypto_rfc3686_setkey;
inst->alg.encrypt = crypto_rfc3686_crypt;
inst->alg.decrypt = crypto_rfc3686_crypt;
inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
inst->alg.init = crypto_rfc3686_init_tfm;
inst->alg.exit = crypto_rfc3686_exit_tfm;
inst->free = crypto_rfc3686_free;
err = skcipher_register_instance(tmpl, inst);
if (err)
goto err_drop_spawn;
out:
return err;
err_drop_spawn:
crypto_drop_skcipher(spawn);
err_free_inst:
kfree(inst);
goto out;
}
static struct crypto_template crypto_rfc3686_tmpl = {
.name = "rfc3686",
.create = crypto_rfc3686_create,
.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_CRYPTO("rfc3686");
MODULE_ALIAS_CRYPTO("ctr");
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