[Ocfs2-devel] [PATCH v3 3/7] selinux: Get rid of file_path_has_perm

[Stephen Smalley <sds@tycho.nsa.gov>]

On 10/28/2015 07:48 AM, Andreas Gruenbacher wrote:
> On Tue, Oct 27, 2015 at 5:40 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote:
>> On 10/26/2015 05:15 PM, Andreas Gruenbacher wrote:
>>>
>>> Use path_has_perm directly instead.
>>
>>
>> This reverts:
>>
>> commit 13f8e9810bff12d01807b6f92329111f45218235
>> Author: David Howells <dhowells@redhat.com>
>> Date:   Thu Jun 13 23:37:55 2013 +0100
>>
>>     SELinux: Institute file_path_has_perm()
>>
>>     Create a file_path_has_perm() function that is like path_has_perm() but
>>     instead takes a file struct that is the source of both the path and the
>>     inode (rather than getting the inode from the dentry in the path).  This
>>     is then used where appropriate.
>>
>>     This will be useful for situations like unionmount where it will be
>>     possible to have an apparently-negative dentry (eg. a fallthrough) that
>> is
>>     open with the file struct pointing to an inode on the lower fs.
>>
>>     Signed-off-by: David Howells <dhowells@redhat.com>
>>     Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
>>
>> which I think David was intending to use as part of his SELinux/overlayfs
>> support.
> 
> Okay. As long as overlayfs support in SELinux is in half-finished
> state, let's leave this alone.

Also, the caller is holding a spinlock (tty_files_lock), so you can't call inode_doinit from
here.

Try stress testing your patch series by just always setting isec->initialized to LABEL_INVALID.
Previously the *has_perm functions could be called under essentially any condition, with the exception
of when in a RCU walk and needing to audit the dname (but they did not previously block/sleep).