linux-kernel - Re: [PATCH 3/7] SLIM main patch

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Message-Id: <1161367122.29755.209.camel@moss-spartans.epoch.ncsc.mil>
Date:	Fri, 20 Oct 2006 13:58:42 -0400
From:	Stephen Smalley <sds@...ho.nsa.gov>
To:	Kylene Jo Hall <kjhall@...ibm.com>
Cc:	akpm@...l.org, Serge Hallyn <sergeh@...ibm.com>,
	Mimi Zohar <zohar@...ibm.com>,
	Dave Safford <safford@...ibm.com>,
	LSM ML <linux-security-module@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/7] SLIM main patch

On Thu, 2006-10-19 at 13:48 -0700, Kylene Jo Hall wrote:
> --- linux-2.6.19-rc2/security/slim/slm_main.c	2006-10-19 12:05:58.000000000 -0700
> +++ linux-2.6.19-rc2/security/slim/slm_main.c	2006-10-19 12:11:37.000000000 -0700
> @@ -1130,6 +1103,34 @@ static int slm_socket_post_create(struct
>  	return 0;
>  }
>  
> +static int slm_file_receive(struct file *file)
> +{
> +	struct slm_isec_data *isec = file->f_dentry->d_inode->i_security;
> +	struct slm_tsec_data *tsec = current->security;
> +	struct slm_file_xattr level;
> +	int rc = 0;
> +
> +	spin_lock(&isec->lock);
> +	memcpy(&level, &isec->level, sizeof(struct slm_file_xattr));
> +	spin_unlock(&isec->lock);
> +
> +	spin_lock(&tsec->lock);
> +	if (file->f_mode & FMODE_READ) { /* IRAC(process) <= IAC(object) */
> +		if (!is_iac_less_than_or_exempt(&level, tsec->iac_r))
> +			rc = -EPERM;
> +	}
> +	if (file->f_mode & FMODE_WRITE) { /* IWXAC(process) >= IAC(object) */
> +		if (!is_iac_greater_than_or_exempt(&level, tsec->iac_wx))
> +			rc = -EPERM;
> +	}
> +	if (file->f_mode & FMODE_EXEC) { /* IWXAC(process) <= IAC(object) */
> +		if (!is_iac_less_than_or_exempt(&level, tsec->iac_wx))
> +			rc = -EPERM;
> +	}
> +	spin_unlock(&tsec->lock);
> +	return rc;
> +}

Also, given your security model, why do you always have this hook deny
access rather than attempting to demote the task?

-- 
Stephen Smalley
National Security Agency

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