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ext4 crypto: use dget_parent() in ext4_d_revalidate()

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This avoids potential problems caused by a race where the inode gets
renamed out from its parent directory and the parent directory is
deleted while ext4_d_revalidate() is running.

Fixes: 28b4c26396
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
This commit is contained in:
Theodore Ts'o 2016-03-26 16:15:42 -04:00
parent c0a37d4878
commit 3d43bcfef5
1 changed files with 8 additions and 4 deletions
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12
fs/ext4/crypto.c
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@ -478,13 +478,16 @@ uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
*/ */
static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags) static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
{ {
struct inode *dir = d_inode(dentry->d_parent); struct dentry *dir;
struct ext4_crypt_info *ci = EXT4_I(dir)->i_crypt_info; struct ext4_crypt_info *ci;
int dir_has_key, cached_with_key; int dir_has_key, cached_with_key;
if (!ext4_encrypted_inode(dir)) dir = dget_parent(dentry);
if (!ext4_encrypted_inode(d_inode(dir))) {
dput(dir);
return 0; return 0;
}
ci = EXT4_I(d_inode(dir))->i_crypt_info;
if (ci && ci->ci_keyring_key && if (ci && ci->ci_keyring_key &&
(ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) | (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
(1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_REVOKED) |
@ -494,6 +497,7 @@ static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
/* this should eventually be an flag in d_flags */ /* this should eventually be an flag in d_flags */
cached_with_key = dentry->d_fsdata != NULL; cached_with_key = dentry->d_fsdata != NULL;
dir_has_key = (ci != NULL); dir_has_key = (ci != NULL);
dput(dir);
/* /*
* If the dentry was cached without the key, and it is a * If the dentry was cached without the key, and it is a