[TriLUG] Help with setuid C wrapper script

[Clay Stuckey]

Sudo is fine for that. It gives you root privileges. Ownership will not be an issue. I'm not sure what you did but it works great for me without a password. 

--
Clay Stuckey
(843) 469-5467
cstuckey at govsg.com
claystuckey at gmail.com

On Oct 10, 2010, at 9:53 AM, "Ron Kelley" <rkelleyrtp at gmail.com> wrote:

> In this specific case, I need a specific (non-root) user to run the commands "tail -100 /var/log/messages" and "tail -50 /var/log/secure" without requiring a password prompt.  Since the messages and sure files are not viewable by non-root users, sudo will not help here.  I tried various incantations of sudo to make this work and had to resort to a wrapper script instead.  In addition, I want a wrapper that I can use to expand the command set without mucking with sudo.
> 
> 
> -Ron
> 
> 
> 
> 
> 
> 
> 
> On Oct 10, 2010, at 9:30 AM, Clay Stuckey wrote:
> 
>> Why use C when sudo is designed for just that? 
>> 
>> --
>> Clay Stuckey
>> (843) 469-5467
>> cstuckey at govsg.com
>> claystuckey at gmail.com
>> 
>> On Oct 10, 2010, at 9:04 AM, "Ron Kelley" <rkelleyrtp at gmail.com> wrote:
>> 
>>> Greetings all,
>>> 
>>> I need to allow a non-root user to run a couple of system commands and would like to use a setuid C wrapper binary.  I have searched over the 'net and have found the following sample code.  Unfortunately, I get segmentation faults if no command arguments are passed in.   Since I am not a C programmer, I was hoping someone could help me fine-tune the utility.  
>>> 
>>> For some reason, this code requires the "-v" CLI argument.  I would prefer to just pass in the necessary arguments without the "-v".  In addition, if no arguments (or, unknown/invalid args) are passed in, I want the utility to exit immediately.  I want the ability to add additional commands in the future, so I need it to be flexible enough to parse the args instead of writing a single wrapper per external command.
>>> 
>>> Example:
>>> 
>>> #> wrapper my_command
>>> <runs the "my_command" command>
>>> 
>>> #> wrapper another_command
>>> <runs the "another_command" command>
>>> 
>>> #> wrapper 
>>> <exits immediately>
>>> 
>>> #> wrapper -h
>>> <exits immediately - no error output>
>>> 
>>> 
>>> ---------------------------------------------------------------------------------------------------------------------------------------
>>> #include <stdio.h>
>>> #include <sys/types.h>
>>> #include <unistd.h>
>>> #include <signal.h>
>>> #include <strings.h>
>>> #include <stdlib.h>
>>> 
>>> /********************************************
>>> * Inspired by: 
>>> * http://linuxshellaccount.blogspot.com/2007/12/securing-suid-programs-using-simple-c.html *
>>> ********************************************/
>>> 
>>> /* Define global variables */
>>> 
>>> int gid;
>>> 
>>> /* main(int argc, char **argv) - main process loop */
>>> 
>>> int main(int argc, char **argv)
>>> {
>>> 
>>> /* Set uid, gid, euid and egid to root */
>>> 
>>> setegid(0);
>>> seteuid(0);
>>> setgid(0);
>>> setuid(0);
>>> 
>>> if ( strncmp(argv[1], "my_command", 11) == 0 ) {
>>>    if (execl("/usr/local/bin/my_command", "my_command", "-v", NULL) < 0) {
>>>       perror("Execl:");
>>>    }
>>> } else if ( strncmp(argv[1], "another_command", 15) == 0 ) {
>>>    if (execl("/usr/local/bin/another_command", "another_command", "-v", NULL) < 0) {
>>>       perror("Execl:");
>>> }
>>> } else {
>>> exit (1);
>>> }
>>> exit (0);
>>> }
>>> ---------------------------------------------------------------------------------------------------------------------------------------
>>> 
>>> 
>>> 
>>> 
>>> 
>>> Thanks for any help,
>>> 
>>> -Ron
>>> -- 
>>> This message was sent to: Clay Stuckey <cstuckey at govsg.com>
>>> To unsubscribe, send a blank message to trilug-leave at trilug.org from that address.
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>> -- 
>> This message was sent to: Ron Kelley <rkelleyrtp at gmail.com>
>> To unsubscribe, send a blank message to trilug-leave at trilug.org from that address.
>> TriLUG mailing list : http://www.trilug.org/mailman/listinfo/trilug
>> Unsubscribe or edit options on the web    : http://www.trilug.org/mailman/options/trilug/rkelleyrtp%40gmail.com
>> TriLUG FAQ          : http://www.trilug.org/wiki/Frequently_Asked_Questions
> 
> Thanks,
> 
> -Ron
> rkelleyrtp at gmail.com
> 
> -- 
> This message was sent to: Clay Stuckey <cstuckey at govsg.com>
> To unsubscribe, send a blank message to trilug-leave at trilug.org from that address.
> TriLUG mailing list : http://www.trilug.org/mailman/listinfo/trilug
> Unsubscribe or edit options on the web    : http://www.trilug.org/mailman/options/trilug/cstuckey%40govsg.com
> TriLUG FAQ          : http://www.trilug.org/wiki/Frequently_Asked_Questions