linux-kernel - Re: [PATCH 4/7] SLIM: secfs patch

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Message-Id: <1159360214.32075.29.camel@moss-spartans.epoch.ncsc.mil>
Date:	Wed, 27 Sep 2006 08:30:14 -0400
From:	Stephen Smalley <sds@...ho.nsa.gov>
To:	Kylene Jo Hall <kjhall@...ibm.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	LSM ML <linux-security-module@...r.kernel.org>,
	Dave Safford <safford@...ibm.com>,
	Mimi Zohar <zohar@...ibm.com>,
	Serge Hallyn <sergeh@...ibm.com>, akpm@...l.org
Subject: Re: [PATCH 4/7] SLIM: secfs patch

On Mon, 2006-09-18 at 13:50 -0700, Kylene Jo Hall wrote:
> On Mon, 2006-09-18 at 16:30 -0400, Stephen Smalley wrote:
> > On Tue, 2006-09-12 at 10:57 -0700, Kylene Jo Hall wrote:
> > > This patch provides the securityfs used by SLIM.
> > > 
> > > Signed-off-by: Mimi Zohar <zohar@...ibm.com>
> > > Signed-off-by: Kylene Hall <kjhall@...ibm.com>
> > > --- 
> > >  security/slim/slm_secfs.c |   73 ++++++++++++++++++++++++++++++++++++
> > >  1 files changed, 73 insertions(+)
> > > 
> > > --- linux-2.6.18/security/slim/slm_secfs.c	1969-12-31 16:00:00.000000000 -0800
> > > +++ linux-2.6.17-working/security/slim/slm_secfs.c	2006-09-06 11:49:09.000000000 -0700
> > > @@ -0,0 +1,73 @@
> > > +/*
> > > + * SLIM securityfs support: debugging control files
> > > + *
> > > + * Copyright (C) 2005, 2006 IBM Corporation
> > > + * Author: Mimi Zohar <zohar@...ibm.com>
> > > + *	   Kylene Hall <kjhall@...ibm.com>
> > > + *
> > > + *      This program is free software; you can redistribute it and/or modify
> > > + *      it under the terms of the GNU General Public License as published by
> > > + *      the Free Software Foundation, version 2 of the License.
> > > + */
> > > +
> > > +#include <asm/uaccess.h>
> > > +#include <linux/config.h>
> > > +#include <linux/module.h>
> > > +#include <linux/kernel.h>
> > > +#include <linux/security.h>
> > > +#include <linux/debugfs.h>
> > > +#include "slim.h"
> > > +
> > > +static struct dentry *slim_sec_dir, *slim_level;
> > > +
> > > +static ssize_t slm_read_level(struct file *file, char __user *buf,
> > > +			      size_t buflen, loff_t *ppos)
> > > +{
> > > +	struct slm_tsec_data *cur_tsec = current->security;
> > > +	ssize_t len;
> > > +	char data[28]; 
> > > +	if (is_kernel_thread(current))
> > > +		len = snprintf(data, sizeof(data), "KERNEL\n");
> > > +	else if (!cur_tsec)
> > > +		len = snprintf(data, sizeof(data), "UNKNOWN\n");
> > > +	else {
> > > +		if (cur_tsec->iac_wx != cur_tsec->iac_r)
> > > +			len = snprintf(data, sizeof(data), "GUARD wx:%s r:%s\n",
> > > +				      slm_iac_str[cur_tsec->iac_wx],
> > > +				      slm_iac_str[cur_tsec->iac_r]);
> > > +		else
> > > +			len = snprintf(data, sizeof(data), "%s\n",
> > > +				      slm_iac_str[cur_tsec->iac_wx]);
> > > +	}
> > > +	return simple_read_from_buffer(buf, buflen, ppos, data, len);
> > > +}
> > 
> > Why do you need this when you implement getprocattr and return the same
> > data that way?
> > 
> True you can get the same info that way but we find it very useful to be
> able to cat this file and get the level of the current process.

It is duplicated code and interface for no obvious purpose - why cannot
you cat /proc/self/attr/current instead?

-- 
Stephen Smalley
National Security Agency

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