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Subject: Re: [PATCH 2/5] selinux: adds a private inode operation
From: Stephen Smalley <sds@epoch.ncsc.mil>
To: Jeffrey Mahoney <jeffm@novell.com>
Cc: Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       ReiserFS List <reiserfs-list@namesys.com>,
       James Morris <jmorris@redhat.com>
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Organization: National Security Agency
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Date: Mon, 22 Nov 2004 08:35:21 -0500
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On Sat, 2004-11-20 at 19:13, Jeffrey Mahoney wrote:
<snip>
> diff -ruNpX dontdiff linux-2.6.9/security/selinux/hooks.c linux-2.6.9.selinux/security/selinux/hooks.c
> --- linux-2.6.9/security/selinux/hooks.c	2004-11-19 14:40:58.000000000 -0500
> +++ linux-2.6.9.selinux/security/selinux/hooks.c	2004-11-20 17:11:22.000000000 -0500
> @@ -740,6 +740,15 @@ static int inode_doinit_with_dentry(stru
>  	if (isec->initialized)
>  		goto out;
>  
> +	if (opt_dentry && opt_dentry->d_parent && opt_dentry->d_parent->d_inode) {
> +		struct inode_security_struct *pisec = opt_dentry->d_parent->d_inode->i_security;
> +		if (pisec->inherit) {
> +			isec->sid = pisec->sid;
> +			isec->initialized = 1;
> +			goto out;
> +		}
> +	}
> +

Shouldn't this be using dget_parent() for safety?

> @@ -2391,6 +2400,15 @@ static int selinux_inode_listsecurity(st
>  	return len;
>  }
>  
> +static void selinux_inode_mark_private(struct inode *inode)
> +{
> +	struct inode_security_struct *isec = inode->i_security;
> +
> +	isec->sid = SECINITSID_KERNEL;
> +	isec->initialized = 1;
> +	isec->inherit = 1;
> +}
> +

Don't we also need to modify inode_has_perm() to skip checking if the
inode has the kernel SID (as is already done by socket_has_perm) to
avoid the search checks when the reiserfs code looks up xattrs? 
Otherwise, we'll see access attempts by the process context on
directories with the kernel SID upon such lookups.

-- 
Stephen Smalley <sds@epoch.ncsc.mil>
National Security Agency

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