linux-kernel - Re: [PATCH 2/2] RFC: selinux: sysctl: fix selinux labeling broken by last patch

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Date:	Mon, 31 Jan 2011 11:59:35 -0500
From:	Stephen Smalley <sds@...ho.nsa.gov>
To:	Lucian Adrian Grijincu <lucian.grijincu@...il.com>
Cc:	James Morris <jmorris@...ei.org>,
	Eric Paris <eparis@...isplace.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Christoph Hellwig <hch@....de>,
	Dave Chinner <dchinner@...hat.com>,
	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	selinux <selinux@...ho.nsa.gov>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH 2/2] RFC: selinux: sysctl: fix selinux labeling broken
 by last patch

On Mon, 2011-01-31 at 18:27 +0200, Lucian Adrian Grijincu wrote:
> There are now fewer differences than before, but I'd like to point
> something out: *without* the patches files in /proc/sys/* get labeled
> like this.
> -r--r--r-- unknown                          /proc/sys/fs/file-nr
> -rw-r--r-- unknown                          /proc/sys/debug/exception-trace
> -rw-r--r-- unknown                          /proc/sys/dev/cdrom/autoclose
> -rw-r--r-- unknown                          /proc/sys/kernel/sem
> -rw-r--r-- unknown
> /proc/sys/net/ipv4/conf/all/accept_local
> 
> but with the patches:
> -r--r--r-- system_u:object_r:sysctl_fs_t:s0 /proc/sys/fs/file-nr
> -rw-r--r-- system_u:object_r:sysctl_t:s0    /proc/sys/debug/exception-trace
> -rw-r--r-- system_u:object_r:sysctl_dev_t:s0 /proc/sys/dev/cdrom/autoclose
> -rw-r--r-- system_u:object_r:sysctl_kernel_t:s0 /proc/sys/kernel/sem
> -rw-r--r-- system_u:object_r:sysctl_net_t:s0
> /proc/sys/net/ipv4/conf/all/accept_local
> 
> 
> There seem to be no labeling mismatches elsewhere. So either sysctl
> labeling is broken in 2.6.37 or my test setup is broken.

/proc/sys inode labeling was disabled earlier (hence marked S_PRIVATE)
when /proc/sys was reimplemented by Eric, so all access control
on /proc/sys was switched to using the sysctl hook rather than the
inode-based checking.  That's why you don't get a result from ls -Z
on /proc/sys on current kernels.  Getting actual labeling working again
for those inodes would be a win, so your patch is an improvement in that
regard for selinux.

-- 
Stephen Smalley
National Security Agency

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