From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <43846B71.6000806@tresys.com>
Date: Wed, 23 Nov 2005 08:15:30 -0500
From: Joshua Brindle <jbrindle@tresys.com>
MIME-Version: 1.0
To: Ivan Gyurdiev <ivg2@cornell.edu>
CC: selinux@tycho.nsa.gov, Stephen Smalley <sds@tycho.nsa.gov>
Subject: Re: [ SEPOL ] Check if policy file is MLS enabled
References: <438452BD.30101@cornell.edu>
In-Reply-To: <438452BD.30101@cornell.edu>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Sender: owner-selinux@tycho.nsa.gov
List-Id: selinux@tycho.nsa.gov

A much better way to do this would be to extract the header reading from 
policydb_read and make a helper function that does it. You will still be 
able to do a partial parse of the binary but only 1 function will have 
to be changed when a format change happens.


Ivan Gyurdiev wrote:
> 
> 
> ------------------------------------------------------------------------
> 
> diff -Naurp --exclude CVS --exclude ChangeLog --exclude VERSION --exclude policycoreutils --exclude libsemanage --exclude 'booleans_kernel.*' --exclude 'database_pserver.*' old/libsepol/include/sepol/policydb.h new/libsepol/include/sepol/policydb.h
> --- old/libsepol/include/sepol/policydb.h	2005-10-18 10:08:39.000000000 -0400
> +++ new/libsepol/include/sepol/policydb.h	2005-11-23 05:54:09.000000000 -0500
> @@ -53,6 +53,14 @@ extern void sepol_policy_file_set_fp(sep
>  extern void sepol_policy_file_set_handle(sepol_policy_file_t *pf,
>  					 sepol_handle_t *handle);
>  
> +/*
> + * Check if the policy file enables MLS
> + */
> +
> +extern int sepol_policy_file_mls_enabled(
> +	sepol_policy_file_t* spf,
> +	int* mls_enabled);
> +
>  /* Policydb public interfaces. */
>  
>  /* Create and free memory associated with a policydb. */
> diff -Naurp --exclude CVS --exclude ChangeLog --exclude VERSION --exclude policycoreutils --exclude libsemanage --exclude 'booleans_kernel.*' --exclude 'database_pserver.*' old/libsepol/src/policydb_public.c new/libsepol/src/policydb_public.c
> --- old/libsepol/src/policydb_public.c	2005-11-01 17:32:59.000000000 -0500
> +++ new/libsepol/src/policydb_public.c	2005-11-23 05:57:42.000000000 -0500
> @@ -1,6 +1,8 @@
>  #include <stdlib.h>
>  
> +#include "handle.h"
>  #include "debug.h"
> +#include "private.h"
>  #include <sepol/policydb/policydb.h>
>  #include "policydb_internal.h"
>  
> @@ -60,6 +62,64 @@ void sepol_policy_file_free(sepol_policy
>  	free(pf);
>  }
>  
> +int sepol_policy_file_mls_enabled(
> +	sepol_policy_file_t* spf,
> +        int* mls_enabled)  {
> +
> +	sepol_handle_t* handle = spf->pf.handle;
> +	struct policy_file* pf = &spf->pf;
> +	unsigned int policy_type;
> +	uint32_t *buf;
> +
> +	/**
> +	 * 4 bytes magic
> +	 * 4 bytes ID length x
> +	 * x bytes ID string
> +	 * (modules only): 4 bytes module type
> +	 * 4 bytes policy version
> +	 * 4 bytes mls status */
> +
> +	/* Magic, ID length */
> +	if (!(buf = next_entry(pf, sizeof(uint32_t)*2)))
> +		goto err;
> +
> +	/* Check policy type */
> +	buf[0] = le32_to_cpu(buf[0]);
> +	if (buf[0] == POLICYDB_MAGIC)
> +		policy_type = POLICY_KERN;
> +        else if (buf[0] == POLICYDB_MOD_MAGIC)
> +		policy_type = POLICY_MOD;
> +        else {
> +                ERR(handle, "policydb magic number %#08x does not "
> +			"match expected magic number %#08x or %#08x",
> +			buf[0], POLICYDB_MAGIC, POLICYDB_MOD_MAGIC);
> +		return STATUS_ERR;
> +	}
> +
> +	/* Skip ID string */
> +	buf[1] = le32_to_cpu(buf[1]);
> +	if (!next_entry(pf, buf[1]))
> +		goto err;
> +
> +	/* Skip module type */
> +	if (policy_type == POLICY_MOD &&
> +		!next_entry(pf, sizeof(uint32_t)))
> +		goto err;
> +
> +	/* Skip policy version */
> +	if (!(buf = next_entry(pf, sizeof(uint32_t)*2)))
> +		goto err;
> +
> +	/* Is MLS enabled? */
> +	buf[1] = le32_to_cpu(buf[1]);
> +	*mls_enabled = (buf[1] & POLICYDB_CONFIG_MLS)? 1:0;
> +	return STATUS_SUCCESS;
> +
> +	err:
> +	ERR(handle, "truncated policy file - could not check MLS status");
> +	return STATUS_ERR;
> +}
> +
>  /* Policydb interfaces. */
>  
>  int sepol_policydb_create(sepol_policydb_t **sp)
> diff -Naurp --exclude CVS --exclude ChangeLog --exclude VERSION --exclude policycoreutils --exclude libsemanage --exclude 'booleans_kernel.*' --exclude 'database_pserver.*' old/libsepol/src/user_record.c new/libsepol/src/user_record.c
> --- old/libsepol/src/user_record.c	2005-11-19 00:51:25.000000000 -0500
> +++ new/libsepol/src/user_record.c	2005-11-23 05:58:22.000000000 -0500
> @@ -271,7 +271,7 @@ int sepol_user_get_roles(
>  hidden_def(sepol_user_get_roles)
>  
>  void sepol_user_del_role(
> -	sepol_handle_t* handle,	
> +	sepol_handle_t* handle,
>  	sepol_user_t* user, 
>  	const char* role) {
>  


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