Revision 7fb5409df092589b86cc9412d926879cb572b7f0 authored by Jan Kara on 10 February 2008, 06:08:38 UTC, committed by Theodore Ts'o on 10 February 2008, 06:08:38 UTC
We cannot start transaction in ext4_direct_IO() and just let it last during the whole write because dio_get_page() acquires mmap_sem which ranks above transaction start (e.g. because we have dependency chain mmap_sem->PageLock->journal_start, or because we update atime while holding mmap_sem) and thus deadlocks could happen. We solve the problem by starting a transaction separately for each ext4_get_block() call. We *could* have a problem that we allocate a block and before its data are written out the machine crashes and thus we expose stale data. But that does not happen because for hole-filling generic code falls back to buffered writes and for file extension, we add inode to orphan list and thus in case of crash, journal replay will truncate inode back to the original size. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
1 parent 8009f9f
michael_mic.c
/*
* Cryptographic API
*
* Michael MIC (IEEE 802.11i/TKIP) keyed digest
*
* Copyright (c) 2004 Jouni Malinen <j@w1.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <asm/byteorder.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/types.h>
struct michael_mic_ctx {
u8 pending[4];
size_t pending_len;
u32 l, r;
};
static inline u32 xswap(u32 val)
{
return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8);
}
#define michael_block(l, r) \
do { \
r ^= rol32(l, 17); \
l += r; \
r ^= xswap(l); \
l += r; \
r ^= rol32(l, 3); \
l += r; \
r ^= ror32(l, 2); \
l += r; \
} while (0)
static void michael_init(struct crypto_tfm *tfm)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
mctx->pending_len = 0;
}
static void michael_update(struct crypto_tfm *tfm, const u8 *data,
unsigned int len)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
const __le32 *src;
if (mctx->pending_len) {
int flen = 4 - mctx->pending_len;
if (flen > len)
flen = len;
memcpy(&mctx->pending[mctx->pending_len], data, flen);
mctx->pending_len += flen;
data += flen;
len -= flen;
if (mctx->pending_len < 4)
return;
src = (const __le32 *)mctx->pending;
mctx->l ^= le32_to_cpup(src);
michael_block(mctx->l, mctx->r);
mctx->pending_len = 0;
}
src = (const __le32 *)data;
while (len >= 4) {
mctx->l ^= le32_to_cpup(src++);
michael_block(mctx->l, mctx->r);
len -= 4;
}
if (len > 0) {
mctx->pending_len = len;
memcpy(mctx->pending, src, len);
}
}
static void michael_final(struct crypto_tfm *tfm, u8 *out)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
u8 *data = mctx->pending;
__le32 *dst = (__le32 *)out;
/* Last block and padding (0x5a, 4..7 x 0) */
switch (mctx->pending_len) {
case 0:
mctx->l ^= 0x5a;
break;
case 1:
mctx->l ^= data[0] | 0x5a00;
break;
case 2:
mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000;
break;
case 3:
mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) |
0x5a000000;
break;
}
michael_block(mctx->l, mctx->r);
/* l ^= 0; */
michael_block(mctx->l, mctx->r);
dst[0] = cpu_to_le32(mctx->l);
dst[1] = cpu_to_le32(mctx->r);
}
static int michael_setkey(struct crypto_tfm *tfm, const u8 *key,
unsigned int keylen)
{
struct michael_mic_ctx *mctx = crypto_tfm_ctx(tfm);
const __le32 *data = (const __le32 *)key;
if (keylen != 8) {
tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
mctx->l = le32_to_cpu(data[0]);
mctx->r = le32_to_cpu(data[1]);
return 0;
}
static struct crypto_alg michael_mic_alg = {
.cra_name = "michael_mic",
.cra_flags = CRYPTO_ALG_TYPE_DIGEST,
.cra_blocksize = 8,
.cra_ctxsize = sizeof(struct michael_mic_ctx),
.cra_module = THIS_MODULE,
.cra_alignmask = 3,
.cra_list = LIST_HEAD_INIT(michael_mic_alg.cra_list),
.cra_u = { .digest = {
.dia_digestsize = 8,
.dia_init = michael_init,
.dia_update = michael_update,
.dia_final = michael_final,
.dia_setkey = michael_setkey } }
};
static int __init michael_mic_init(void)
{
return crypto_register_alg(&michael_mic_alg);
}
static void __exit michael_mic_exit(void)
{
crypto_unregister_alg(&michael_mic_alg);
}
module_init(michael_mic_init);
module_exit(michael_mic_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Michael MIC");
MODULE_AUTHOR("Jouni Malinen <j@w1.fi>");
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