Commit 4bea5805 authored Feb 04, 2008 by David P. Quigley Committed by Linus Torvalds Feb 05, 2008

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: David P. Quigley <dpquigl@tycho.nsa.gov>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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;
		}

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