linux-kernel - Re: [RFC][PATCH] security/selinux: Simplify proc inode to security label mapping.

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Message-ID: <alpine.LRH.2.00.0911251939450.9198@tundra.namei.org>
Date:	Wed, 25 Nov 2009 19:41:48 +1100 (EST)
From:	James Morris <jmorris@...ei.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
cc:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Eric Paris <eparis@...hat.com>
Subject: Re: [RFC][PATCH] security/selinux: Simplify proc inode to security
 label mapping.

On Fri, 20 Nov 2009, Eric W. Biederman wrote:

> 
> Currently selinux has incestuous knowledge of the implementation details
> of procfs and sysctl that it uses to get a pathname from an inode. As it
> happens the point we care is in the security_d_instantiate lsm hook so
> we have a valid dentry that we can use to get the entire pathname on
> the proc filesystem.  With the recent change to sys_sysctl to go through
> proc/sys all proc and sysctl accesses go through the vfs, which
> means we no longer need a sysctl special case.
> 
> So get the path for the dentry, remove the incestuous knowledge
> and simplify the code.
> 
> caveat: Because the dentry may not yet be hashed I think dentry_path will
>         append (deleted) and thus is not the right function to call.

This seems to break labeling.  Prior to this patch, I see:


# ls -lZ /proc/1/net/rpc/nfsd.fh
-rw-------. root root system_u:object_r:sysctl_rpc_t:s0 channel

with the patch:

# ls -lZ /proc/1/net/rpc/nfsd.fh
-rw-------. root root system_u:object_r:proc_t:s0      channel


-- 
James Morris
<jmorris@...ei.org>
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