/*
* Cryptographic API.
*
* Cipher operations.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.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/kernel.h>
#include <linux/crypto.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <asm/scatterlist.h>
#include "internal.h"
#include "scatterwalk.h"
typedef void (cryptfn_t)(void *, u8 *, const u8 *);
typedef void (procfn_t)(struct crypto_tfm *, u8 *,
u8*, cryptfn_t, int enc, void *, int);
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];
}
/*
* 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 block.
*/
static int crypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes, cryptfn_t crfn,
procfn_t prfn, int enc, void *info)
{
struct scatter_walk walk_in, walk_out;
const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
u8 tmp_src[bsize];
u8 tmp_dst[bsize];
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(;;) {
u8 *src_p, *dst_p;
int in_place;
scatterwalk_map(&walk_in, 0);
scatterwalk_map(&walk_out, 1);
src_p = scatterwalk_whichbuf(&walk_in, bsize, tmp_src);
dst_p = scatterwalk_whichbuf(&walk_out, bsize, tmp_dst);
in_place = scatterwalk_samebuf(&walk_in, &walk_out,
src_p, dst_p);
nbytes -= bsize;
scatterwalk_copychunks(src_p, &walk_in, bsize, 0);
prfn(tfm, dst_p, src_p, crfn, enc, info, in_place);
scatterwalk_done(&walk_in, 0, nbytes);
scatterwalk_copychunks(dst_p, &walk_out, bsize, 1);
scatterwalk_done(&walk_out, 1, nbytes);
if (!nbytes)
return 0;
crypto_yield(tfm);
}
}
static void cbc_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
cryptfn_t fn, int enc, void *info, int in_place)
{
u8 *iv = info;
/* Null encryption */
if (!iv)
return;
if (enc) {
tfm->crt_u.cipher.cit_xor_block(iv, src);
fn(crypto_tfm_ctx(tfm), dst, iv);
memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
} else {
u8 stack[in_place ? crypto_tfm_alg_blocksize(tfm) : 0];
u8 *buf = in_place ? stack : dst;
fn(crypto_tfm_ctx(tfm), buf, src);
tfm->crt_u.cipher.cit_xor_block(buf, iv);
memcpy(iv, src, crypto_tfm_alg_blocksize(tfm));
if (buf != dst)
memcpy(dst, buf, crypto_tfm_alg_blocksize(tfm));
}
}
static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
cryptfn_t fn, int enc, void *info, int in_place)
{
fn(crypto_tfm_ctx(tfm), dst, src);
}
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)
{
return crypt(tfm, dst, src, nbytes,
tfm->__crt_alg->cra_cipher.cia_encrypt,
ecb_process, 1, NULL);
}
static int ecb_decrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
return crypt(tfm, dst, src, nbytes,
tfm->__crt_alg->cra_cipher.cia_decrypt,
ecb_process, 1, NULL);
}
static int cbc_encrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
return crypt(tfm, dst, src, nbytes,
tfm->__crt_alg->cra_cipher.cia_encrypt,
cbc_process, 1, tfm->crt_cipher.cit_iv);
}
static int cbc_encrypt_iv(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes, u8 *iv)
{
return crypt(tfm, dst, src, nbytes,
tfm->__crt_alg->cra_cipher.cia_encrypt,
cbc_process, 1, iv);
}
static int cbc_decrypt(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes)
{
return crypt(tfm, dst, src, nbytes,
tfm->__crt_alg->cra_cipher.cia_decrypt,
cbc_process, 0, tfm->crt_cipher.cit_iv);
}
static int cbc_decrypt_iv(struct crypto_tfm *tfm,
struct scatterlist *dst,
struct scatterlist *src,
unsigned int nbytes, u8 *iv)
{
return crypt(tfm, dst, src, nbytes,
tfm->__crt_alg->cra_cipher.cia_decrypt,
cbc_process, 0, iv);
}
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) {
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);
ops->cit_iv = kmalloc(ops->cit_ivsize, GFP_KERNEL);
if (ops->cit_iv == NULL)
ret = -ENOMEM;
}
out:
return ret;
}
void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
{
if (tfm->crt_cipher.cit_iv)
kfree(tfm->crt_cipher.cit_iv);
}
