[RFC][PATCH 0/2] Correct behavior for listxattr and 'trusted'xattrs

From: James Morris
Date: Tue Mar 02 2010 - 03:01:33 EST

I noticed that there are differences in the behavior of listxattr(2) for
xattrs in the trusted namespace.

Some filesystems, such as ext[234], require CAP_SYS_ADMIN for this, i.e.
trusted xattr names are hidden from unprivileged users.

I audited the kernel for users of the trusted xattr namespace, and found
the following filesystems not checking for CAP_SYS_ADMIN:

- jffs2
- ocfs2
- btrfs
- xfs

I've created patches for jffs2 (tested) and ocfs2 (not tested) to add the
check -- see following emails. btrfs and xfs have custom listxattr
operations and will need a bit more work to fix.

I'm not sure what the initial intention was for the behavior, although
given that several major filesystems are have been fielded with the
CAP_SYS_ADMIN check, it seems most prudent to make this the standard
behavior for all filesystems, in case any users are depending on it.


- James
James Morris
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