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Commit 7c51bb00 authored by Dmitry Kasatkin's avatar Dmitry Kasatkin Committed by Mimi Zohar
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evm: fix potential race when removing xattrs 



EVM needs to be atomically updated when removing xattrs.
Otherwise concurrent EVM verification may fail in between.
This patch fixes by moving i_mutex unlocking after calling
EVM hook. fsnotify_xattr() is also now called while locked
the same way as it is done in __vfs_setxattr_noperm.

Changelog:
- remove unused 'inode' variable.

Signed-off-by: default avatarDmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
parent 5101a185

fs/xattr.c

+5 −5
Original line number Original line Diff line number Diff line
@@ -298,18 +298,18 @@ vfs_removexattr(struct dentry *dentry, const char *name) 




	mutex_lock(&inode->i_mutex);

	mutex_lock(&inode->i_mutex);

	error = security_inode_removexattr(dentry, name);

	error = security_inode_removexattr(dentry, name);

	if (error) {

	if (error)

		mutex_unlock(&inode->i_mutex);

		goto out;

		return error;

	}





	error = inode->i_op->removexattr(dentry, name);

	error = inode->i_op->removexattr(dentry, name);

	mutex_unlock(&inode->i_mutex);





	if (!error) {

	if (!error) {

		fsnotify_xattr(dentry);

		fsnotify_xattr(dentry);

		evm_inode_post_removexattr(dentry, name);

		evm_inode_post_removexattr(dentry, name);

	}

	}



out:

	mutex_unlock(&inode->i_mutex);

	return error;

	return error;

}

}

EXPORT_SYMBOL_GPL(vfs_removexattr);

EXPORT_SYMBOL_GPL(vfs_removexattr);

security/integrity/evm/evm_main.c

+3 −4
Original line number Original line Diff line number Diff line
@@ -387,17 +387,16 @@ void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name, 
 * @xattr_name: pointer to the affected extended attribute name

 * @xattr_name: pointer to the affected extended attribute name

 *

 *

 * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.

 * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.

 *

 * No need to take the i_mutex lock here, as this function is called from

 * vfs_removexattr() which takes the i_mutex.

 */

 */

void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)

void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)

{

{

	struct inode *inode = d_backing_inode(dentry);



	if (!evm_initialized || !evm_protected_xattr(xattr_name))

	if (!evm_initialized || !evm_protected_xattr(xattr_name))

		return;

		return;





	mutex_lock(&inode->i_mutex);

	evm_update_evmxattr(dentry, xattr_name, NULL, 0);

	evm_update_evmxattr(dentry, xattr_name, NULL, 0);

	mutex_unlock(&inode->i_mutex);

}

}





/**

/**