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Commit 4bea5805 authored by David P. Quigley's avatar David P. Quigley Committed by Linus Torvalds
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VFS: Reorder vfs_getxattr to avoid unnecessary calls to the LSM 



Originally vfs_getxattr would pull the security xattr variable using
the inode getxattr handle and then proceed to clobber it with a subsequent call
to the LSM.

This patch reorders the two operations such that when the xattr requested is
in the security namespace it first attempts to grab the value from the LSM
directly.

If it fails to obtain the value because there is no module present or the
module does not support the operation it will fall back to using the inode
getxattr operation.

In the event that both are inaccessible it returns EOPNOTSUPP.

Signed-off-by: default avatarDavid P. Quigley <dpquigl@tycho.nsa.gov>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Acked-by: default avatarJames Morris <jmorris@namei.org>
Acked-by: default avatarSerge Hallyn <serue@us.ibm.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 42492594

fs/xattr.c

+8 −7
Original line number Diff line number Diff line
@@ -145,11 +145,6 @@ vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size) 
	if (error)

		return error;



	if (inode->i_op->getxattr)

		error = inode->i_op->getxattr(dentry, name, value, size);

	else

		error = -EOPNOTSUPP;



	if (!strncmp(name, XATTR_SECURITY_PREFIX,

				XATTR_SECURITY_PREFIX_LEN)) {

		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
@@ -158,9 +153,15 @@ vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size) 
		 * Only overwrite the return value if a security module

		 * is actually active.

		 */

		if (ret != -EOPNOTSUPP)

			error = ret;

		if (ret == -EOPNOTSUPP)

			goto nolsm;

		return ret;

	}

nolsm:

	if (inode->i_op->getxattr)

		error = inode->i_op->getxattr(dentry, name, value, size);

	else

		error = -EOPNOTSUPP;



	return error;

}