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linux/crypto/cipher.c
Herbert Xu 5c64097aa0 [CRYPTO] scatterwalk: Prepare for block ciphers 
This patch prepares the scatterwalk code for use by the new block cipher
type.

Firstly it halves the size of scatter_walk on 32-bit platforms.  This
is important as we allocate at least two of these objects on the stack
for each block cipher operation.

It also exports the symbols since the block cipher code can be built as
a module.

Finally there is a hack in scatterwalk_unmap that relies on progress
being made.  Unfortunately, for hardware crypto we can't guarantee
progress to be made since the hardware can fail.

So this also gets rid of the hack by not advancing the address returned
by scatterwalk_map.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2006-09-21 11:41:52 +10:00

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/*
* Cryptographic API.
*
* Cipher operations.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* Copyright (c) 2005 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 <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/crypto.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <asm/scatterlist.h>
#include "internal.h"
#include "scatterwalk.h"
static inline void xor_64(u8 *a, const u8 *b)
{
((u32 *)a)[0] ^= ((u32 *)b)[0];
((u32 *)a)[1] ^= ((u32 *)b)[1];
}
static inline void xor_128(u8 *a, const u8 *b)
{
((u32 *)a)[0] ^= ((u32 *)b)[0];
((u32 *)a)[1] ^= ((u32 *)b)[1];
((u32 *)a)[2] ^= ((u32 *)b)[2];
((u32 *)a)[3] ^= ((u32 *)b)[3];
}
static unsigned int crypt_slow(const struct cipher_desc *desc,
struct scatter_walk *in,
struct scatter_walk *out, unsigned int bsize)
{
unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
u8 buffer[bsize * 2 + alignmask];
u8 *src = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
u8 *dst = src + bsize;
scatterwalk_copychunks(src, in, bsize, 0);
desc->prfn(desc, dst, src, bsize);
scatterwalk_copychunks(dst, out, bsize, 1);
return bsize;
}
static inline unsigned int crypt_fast(const struct cipher_desc *desc,
struct scatter_walk *in,
struct scatter_walk *out,
unsigned int nbytes, u8 *tmp)
{
u8 *src, *dst;
u8 *real_src, *real_dst;
real_src = scatterwalk_map(in, 0);
real_dst = scatterwalk_map(out, 1);
src = real_src;
dst = scatterwalk_samebuf(in, out) ? src : real_dst;
if (tmp) {
memcpy(tmp, src, nbytes);
src = tmp;
dst = tmp;
}
nbytes = desc->prfn(desc, dst, src, nbytes);
if (tmp)
memcpy(real_dst, tmp, nbytes);
scatterwalk_unmap(real_src, 0);
scatterwalk_unmap(real_dst, 1);
scatterwalk_advance(in, nbytes);
scatterwalk_advance(out, nbytes);
return nbytes;
}
/*
* Generic encrypt/decrypt wrapper for ciphers, handles operations across
* multiple page boundaries by using temporary blocks. In user context,
* the kernel is given a chance to schedule us once per page.
*/
static int crypt(const struct cipher_desc *desc,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
struct scatter_walk walk_in, walk_out;
struct crypto_tfm *tfm = desc->tfm;
const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
unsigned int alignmask = crypto_tfm_alg_alignmask(tfm);
unsigned long buffer = 0;
if (!nbytes)
return 0;
if (nbytes % bsize) {
tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
return -EINVAL;
}
scatterwalk_start(&walk_in, src);
scatterwalk_start(&walk_out, dst);
for(;;) {
unsigned int n = nbytes;
u8 *tmp = NULL;
if (!scatterwalk_aligned(&walk_in, alignmask) ||
!scatterwalk_aligned(&walk_out, alignmask)) {
if (!buffer) {
buffer = __get_free_page(GFP_ATOMIC);
if (!buffer)
n = 0;
}
tmp = (u8 *)buffer;
}
n = scatterwalk_clamp(&walk_in, n);
n = scatterwalk_clamp(&walk_out, n);
if (likely(n >= bsize))
n = crypt_fast(desc, &walk_in, &walk_out, n, tmp);
else
n = crypt_slow(desc, &walk_in, &walk_out, bsize);
nbytes -= n;
scatterwalk_done(&walk_in, 0, nbytes);
scatterwalk_done(&walk_out, 1, nbytes);
if (!nbytes)
break;
crypto_yield(tfm->crt_flags);
}
if (buffer)
free_page(buffer);
return 0;
}
static int crypt_iv_unaligned(struct cipher_desc *desc,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
struct crypto_tfm *tfm = desc->tfm;
unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
u8 *iv = desc->info;
if (unlikely(((unsigned long)iv & alignmask))) {
unsigned int ivsize = tfm->crt_cipher.cit_ivsize;
u8 buffer[ivsize + alignmask];
u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
int err;
desc->info = memcpy(tmp, iv, ivsize);
err = crypt(desc, dst, src, nbytes);
memcpy(iv, tmp, ivsize);
return err;
}
return crypt(desc, dst, src, nbytes);
}
static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
u8 *dst, const u8 *src,
unsigned int nbytes)
{
struct crypto_tfm *tfm = desc->tfm;
void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
int bsize = crypto_tfm_alg_blocksize(tfm);
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
u8 *iv = desc->info;
unsigned int done = 0;
nbytes -= bsize;
do {
xor(iv, src);
fn(tfm, dst, iv);
memcpy(iv, dst, bsize);
src += bsize;
dst += bsize;
} while ((done += bsize) <= nbytes);
return done;
}
static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
u8 *dst, const u8 *src,
unsigned int nbytes)
{
struct crypto_tfm *tfm = desc->tfm;
void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
int bsize = crypto_tfm_alg_blocksize(tfm);
unsigned long alignmask = crypto_tfm_alg_alignmask(desc->tfm);
u8 stack[src == dst ? bsize + alignmask : 0];
u8 *buf = (u8 *)ALIGN((unsigned long)stack, alignmask + 1);
u8 **dst_p = src == dst ? &buf : &dst;
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
u8 *iv = desc->info;
unsigned int done = 0;
nbytes -= bsize;
do {
u8 *tmp_dst = *dst_p;
fn(tfm, tmp_dst, src);
xor(tmp_dst, iv);
memcpy(iv, src, bsize);
if (tmp_dst != dst)
memcpy(dst, tmp_dst, bsize);
src += bsize;
dst += bsize;
} while ((done += bsize) <= nbytes);
return done;
}
static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
const u8 *src, unsigned int nbytes)
{
struct crypto_tfm *tfm = desc->tfm;
int bsize = crypto_tfm_alg_blocksize(tfm);
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = desc->crfn;
unsigned int done = 0;
nbytes -= bsize;
do {
fn(tfm, dst, src);
src += bsize;
dst += bsize;
} while ((done += bsize) <= nbytes);
return done;
}
static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
{
struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
tfm->crt_flags &= ~CRYPTO_TFM_RES_MASK;
if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
} else
return cia->cia_setkey(tfm, key, keylen);
}
static int ecb_encrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct cipher_desc desc;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
desc.tfm = tfm;
desc.crfn = cipher->cia_encrypt;
desc.prfn = cipher->cia_encrypt_ecb ?: ecb_process;
return crypt(&desc, dst, src, nbytes);
}
static int ecb_decrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
struct cipher_desc desc;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
desc.tfm = tfm;
desc.crfn = cipher->cia_decrypt;
desc.prfn = cipher->cia_decrypt_ecb ?: ecb_process;
return crypt(&desc, dst, src, nbytes);
}
static int cbc_encrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
struct cipher_desc desc;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
desc.tfm = tfm;
desc.crfn = cipher->cia_encrypt;
desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
desc.info = tfm->crt_cipher.cit_iv;
return crypt(&desc, dst, src, nbytes);
}
static int cbc_encrypt_iv(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes, u8 *iv)
{
struct cipher_desc desc;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
desc.tfm = tfm;
desc.crfn = cipher->cia_encrypt;
desc.prfn = cipher->cia_encrypt_cbc ?: cbc_process_encrypt;
desc.info = iv;
return crypt_iv_unaligned(&desc, dst, src, nbytes);
}
static int cbc_decrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
struct cipher_desc desc;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
desc.tfm = tfm;
desc.crfn = cipher->cia_decrypt;
desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
desc.info = tfm->crt_cipher.cit_iv;
return crypt(&desc, dst, src, nbytes);
}
static int cbc_decrypt_iv(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes, u8 *iv)
{
struct cipher_desc desc;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
desc.tfm = tfm;
desc.crfn = cipher->cia_decrypt;
desc.prfn = cipher->cia_decrypt_cbc ?: cbc_process_decrypt;
desc.info = iv;
return crypt_iv_unaligned(&desc, dst, src, nbytes);
}
static int nocrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
return -ENOSYS;
}
static int nocrypt_iv(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes, u8 *iv)
{
return -ENOSYS;
}
int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
{
u32 mode = flags & CRYPTO_TFM_MODE_MASK;
tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
return 0;
}
static void cipher_crypt_unaligned(void (*fn)(struct crypto_tfm *, u8 *,
const u8 *),
struct crypto_tfm *tfm,
u8 *dst, const u8 *src)
{
unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
unsigned int size = crypto_tfm_alg_blocksize(tfm);
u8 buffer[size + alignmask];
u8 *tmp = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
memcpy(tmp, src, size);
fn(tfm, tmp, tmp);
memcpy(dst, tmp, size);
}
static void cipher_encrypt_unaligned(struct crypto_tfm *tfm,
u8 *dst, const u8 *src)
{
unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
cipher_crypt_unaligned(cipher->cia_encrypt, tfm, dst, src);
return;
}
cipher->cia_encrypt(tfm, dst, src);
}
static void cipher_decrypt_unaligned(struct crypto_tfm *tfm,
u8 *dst, const u8 *src)
{
unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
if (unlikely(((unsigned long)dst | (unsigned long)src) & alignmask)) {
cipher_crypt_unaligned(cipher->cia_decrypt, tfm, dst, src);
return;
}
cipher->cia_decrypt(tfm, dst, src);
}
int crypto_init_cipher_ops(struct crypto_tfm *tfm)
{
int ret = 0;
struct cipher_tfm *ops = &tfm->crt_cipher;
struct cipher_alg *cipher = &tfm->__crt_alg->cra_cipher;
ops->cit_setkey = setkey;
ops->cit_encrypt_one = crypto_tfm_alg_alignmask(tfm) ?
cipher_encrypt_unaligned : cipher->cia_encrypt;
ops->cit_decrypt_one = crypto_tfm_alg_alignmask(tfm) ?
cipher_decrypt_unaligned : cipher->cia_decrypt;
switch (tfm->crt_cipher.cit_mode) {
case CRYPTO_TFM_MODE_ECB:
ops->cit_encrypt = ecb_encrypt;
ops->cit_decrypt = ecb_decrypt;
ops->cit_encrypt_iv = nocrypt_iv;
ops->cit_decrypt_iv = nocrypt_iv;
break;
case CRYPTO_TFM_MODE_CBC:
ops->cit_encrypt = cbc_encrypt;
ops->cit_decrypt = cbc_decrypt;
ops->cit_encrypt_iv = cbc_encrypt_iv;
ops->cit_decrypt_iv = cbc_decrypt_iv;
break;
case CRYPTO_TFM_MODE_CFB:
ops->cit_encrypt = nocrypt;
ops->cit_decrypt = nocrypt;
ops->cit_encrypt_iv = nocrypt_iv;
ops->cit_decrypt_iv = nocrypt_iv;
break;
case CRYPTO_TFM_MODE_CTR:
ops->cit_encrypt = nocrypt;
ops->cit_decrypt = nocrypt;
ops->cit_encrypt_iv = nocrypt_iv;
ops->cit_decrypt_iv = nocrypt_iv;
break;
default:
BUG();
}
if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
unsigned long align;
unsigned long addr;
switch (crypto_tfm_alg_blocksize(tfm)) {
case 8:
ops->cit_xor_block = xor_64;
break;
case 16:
ops->cit_xor_block = xor_128;
break;
default:
printk(KERN_WARNING "%s: block size %u not supported\n",
crypto_tfm_alg_name(tfm),
crypto_tfm_alg_blocksize(tfm));
ret = -EINVAL;
goto out;
}
ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
align = crypto_tfm_alg_alignmask(tfm) + 1;
addr = (unsigned long)crypto_tfm_ctx(tfm);
addr = ALIGN(addr, align);
addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
ops->cit_iv = (void *)addr;
}
out:
return ret;
}
void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
{
}
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