[TriLUG] Help with setuid C wrapper script

[Ron Kelley]

What is the syntax in your /etc/sudoers file?



On Oct 10, 2010, at 10:30 AM, Clay Stuckey wrote:

> 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
> -- 
> 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