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eCryptfs: Do not allocate hash tfm in NORECLAIM context

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You cannot allocate crypto tfm objects in NORECLAIM or NOFS contexts.
The ecryptfs code currently does exactly that for the MD5 tfm.

This patch fixes it by preallocating the MD5 tfm in a safe context.

The MD5 tfm is also reentrant so this patch removes the superfluous
cs_hash_tfm_mutex.

Reported-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu
2016-04-16 15:01:09 +08:00
parent b3ab30a7cb
commit e81f3340bb
4 changed files with 26 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fs/ecryptfs/crypto.c
+16 -16
View File
@@ -105,19 +105,7 @@ static int ecryptfs_calculate_md5(char *dst,
struct crypto_shash *tfm;
int rc = 0;
mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
tfm = crypt_stat->hash_tfm;
if (!tfm) {
tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
if (IS_ERR(tfm)) {
rc = PTR_ERR(tfm);
ecryptfs_printk(KERN_ERR, "Error attempting to "
"allocate crypto context; rc = [%d]\n",
rc);
goto out;
}
crypt_stat->hash_tfm = tfm;
}
rc = ecryptfs_hash_digest(tfm, src, len, dst);
if (rc) {
printk(KERN_ERR
@@ -126,7 +114,6 @@ static int ecryptfs_calculate_md5(char *dst,
goto out;
}
out:
mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
return rc;
}
@@ -207,16 +194,29 @@ out:
*
* Initialize the crypt_stat structure.
*/
void
ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
{
struct crypto_shash *tfm;
int rc;
tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
if (IS_ERR(tfm)) {
rc = PTR_ERR(tfm);
ecryptfs_printk(KERN_ERR, "Error attempting to "
"allocate crypto context; rc = [%d]\n",
rc);
return rc;
}
memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
INIT_LIST_HEAD(&crypt_stat->keysig_list);
mutex_init(&crypt_stat->keysig_list_mutex);
mutex_init(&crypt_stat->cs_mutex);
mutex_init(&crypt_stat->cs_tfm_mutex);
mutex_init(&crypt_stat->cs_hash_tfm_mutex);
crypt_stat->hash_tfm = tfm;
crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
return 0;
}
/**