From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <42999EF1.3020205@redhat.com>
Date: Sun, 29 May 2005 06:52:33 -0400
From: Daniel J Walsh <dwalsh@redhat.com>
MIME-Version: 1.0
To: ivg2@cornell.edu
CC: SELinux@tycho.nsa.gov
Subject: Re: file_type_auto_trans is not sufficient
References: <1117249760.19257.18.camel@localhost.localdomain>	 <1117252045.19698.16.camel@localhost.localdomain>	 <42980072.6090701@redhat.com> <1117336632.24194.8.camel@localhost.localdomain>
In-Reply-To: <1117336632.24194.8.camel@localhost.localdomain>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Sender: owner-selinux@tycho.nsa.gov
List-Id: selinux@tycho.nsa.gov

Ivan Gyurdiev wrote:

>>setfscreatecon takes precedence.
>>    
>>
>
>...on second thought this interface doesn't work at all - 
>apps call higher level functions for portability - the C
>standard functions (fopen...), glib (g_mkdir).
>
>Maybe just add:
>
>/* Performs a context match, and changes the file creation context.
> * On success, returns the old context. On failure, returns NULL.
> * The context returned must be freed with freecon() */
>
>security_context_t switch_context(const char* pathname, mode_t mode) {
>        security_context_t prev_ctx = NULL;
>        security_context_t tmp_ctx = NULL;
>
>        /* Attempt to get the current context. */
>        if (getfscreatecon(&prev_ctx) < 0)
>                return NULL;
>
>        /* Attempt a match. */
>        if (matchpathcon(pathname, mode, &tmp_ctx) >= 0) {
>                if (setfscreatecon(tmp_ctx) < 0) {
>                        freecon(tmp_ctx);
>                        freecon(prev_ctx);
>                        return NULL;
>                }
>                freecon(tmp_ctx);
>        }
>
>        return prev_ctx;
>}
>
>...and then do this in every app that needs it, replacing
>mkdir with the appropriate function. This is annoying.... 
>but I can't think how else to write a better interface.
>
>/* Performs a mkdir call, and sets the context of the directory
> * being created, according to matchpathcon. On SElinux failure
> * returns -1. Otherwise, returns the usual mkdir status. */
>
>int mkdir_restorecon(const char *pathname, mode_t mode) {
>        security_context_t prev_ctx = NULL;
>        int status;
>
>        if (is_selinux_enabled()) {
>                prev_ctx = switch_context(pathname, mode);
>
>                if ((prev_ctx != NULL) && security_getenforce())
>                        return -1;
>        }
>
>        status = mkdir(pathname, mode);
>
>        if (prev_ctx != NULL) {
>                setfscreatecon(prev_ctx);
>                freecon(prev_ctx);
>        }
>
>        return status;
>}
>
>  
>
You do not necessarily want to return an error or matchpathcon failure.  
matchpathcon can return ENOENT to indicate that it matched <<none>>

In this case the setfscreatecon should not be called but the code should 
continue.  IE the
file should get created with the default context.

-- 



--
This message was distributed to subscribers of the selinux mailing list.
If you no longer wish to subscribe, send mail to majordomo@tycho.nsa.gov with
the words "unsubscribe selinux" without quotes as the message.