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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;
unsigned int n;
n = scatterwalk_copychunks(src, in, bsize, 0);
scatterwalk_advance(in, n);
desc->prfn(desc, dst, src, bsize);
n = scatterwalk_copychunks(dst, out, bsize, 1);
scatterwalk_advance(out, n);
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;
src = in->data;
dst = scatterwalk_samebuf(in, out) ? src : out->data;
if (tmp) {
memcpy(tmp, in->data, nbytes);
src = tmp;
dst = tmp;
}
nbytes = desc->prfn(desc, dst, src, nbytes);
if (tmp)
memcpy(out->data, tmp, nbytes);
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;
}
scatterwalk_map(&walk_in, 0);
scatterwalk_map(&walk_out, 1);
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);
}
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)(void *, u8 *, const u8 *) = desc->crfn;
u8 *iv = desc->info;
unsigned int done = 0;
do {
xor(iv, src);
fn(crypto_tfm_ctx(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);
u8 stack[src == dst ? bsize : 0];
u8 *buf = stack;
u8 **dst_p = src == dst ? &buf : &dst;
void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
u8 *iv = desc->info;
unsigned int done = 0;
do {
u8 *tmp_dst = *dst_p;
fn(crypto_tfm_ctx(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)(void *, u8 *, const u8 *) = desc->crfn;
unsigned int done = 0;
do {
fn(crypto_tfm_ctx(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;
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(crypto_tfm_ctx(tfm), key, keylen,
&tfm->crt_flags);
}
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;
if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
return 0;
}
int crypto_init_cipher_ops(struct crypto_tfm *tfm)
{
int ret = 0;
struct cipher_tfm *ops = &tfm->crt_cipher;
ops->cit_setkey = setkey;
switch (tfm->crt_cipher.cit_mode) {
case CRYPTO_TFM_MODE_ECB:
ops->cit_encrypt = ecb_encrypt;
ops->cit_decrypt = ecb_decrypt;
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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