linux-kernel - Re: [PATCH] Fix user.* xattr permission check for sticky dirs

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Date:	Fri, 03 Nov 2006 14:57:33 +1000
From:	Timothy Shimmin <tes@....com>
To:	Andreas Gruenbacher <agruen@...e.de>
cc:	linux-kernel@...r.kernel.org, Gerard Neil <xyzzy@...ferret.org>,
	Dave Kleikamp <shaggy@...tin.ibm.com>,
	Linus Torvalds <torvalds@...l.org>,
	Andrew Morton <akpm@...l.org>
Subject: Re: [PATCH] Fix user.* xattr permission check for sticky dirs

Hi Andreas,

--On 2 November 2006 10:51:21 PM +0100 Andreas Gruenbacher <agruen@...e.de> wrote:

> On Thursday 02 November 2006 20:27, Andrew Morton wrote:
>> On Thu, 2 Nov 2006 17:24:02 +0100
>>
>> Andreas Gruenbacher <agruen@...e.de> wrote:
>> > The user.* extended attributes are only allowed on regular files and
>> > directories. Sticky directories further restrict write access to the
>> > owner and privileged users. (See the attr(5) man page for an
>> > explanation.)
>> >
>> > The original check in ext2/ext3 when user.* xattrs were merged was more
>> > restrictive than intended, and when the xattr permission checks were
>> > moved into the VFS, read access to user.* attributes on sticky directores
>> > ended up being denied in addition.
>>
>> Am struggling to understand the impact of this.  I assume this problem was
>> introduced on Jan 9 by e0ad7b073eb7317e5afe0385b02dcb1d52a1eedf "move xattr
>> permission checks into the VFS"?
>
> Commits e0ad7b073eb7317e5afe0385b02dcb1d52a1eedf and
> c37ef806a3e1c0bca65fd03b7590d56d19625da4 move the following check from
> ext3_xattr_user_set() to xattr_permission(), which is used in vfs_getxattr()
> as well as xfs_setxattr() and vfs_removexattr(),

> so this added the check to
> the xfs_getxattr() path by accident:
>
> []	if (!S_ISREG(inode->i_mode) &&
> []	    (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
> []		return -EPERM;
>
>
Now, I'm a bit confused.
xfs_getxattr?
I see the "correct" version of the test in xfs_attr.c/attr_user_capable().

--Tim
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