Re: [monit-dev] "check program" change uid preliminary patch

[Igor Homyakov]

Hi guys,

Is it really necessary to re-implement su/sudo functionality ?  I
don't think so.  From my point of view we've got over-engineering
here.  I believe that su developers are smart enough to deal with
security/race issues.

So "check program su username -c command" is more secure, more
flexible and more simple way  to do that.

Kind regards
Igor Homyakov

On Fri, Mar 16, 2012 at 11:11, Jan-Henrik Haukeland <address@hidden> wrote:
> Hi
>
> Looks like a fine start to me. Thanks for the work. It should be possible to 
> avoid the global stuff and use the local struct myprogram programset object. 
> I'll take a look and add the refactored patch.
>
>
> On Mar 16, 2012, at 5:11 AM, Leif Gustafson wrote:
>
>> Hello,
>>  Following up on the conversation in monit-general about adding an option
>> to "check program" to drop root privileges, I took a look at the source code
>> and tried to see how difficult it would be to add it.  I'm not extremely
>> familiar with the source tree nor do I usually use C for my day job so be
>> gentle, but I was able to mock up a preliminary working patch (against
>> 5.3.2).  I think this is a pretty important security feature for "check
>> program" because if the user isn't careful a malicious trojan could be
>> executed as root.
>>
>>  I had to make a couple of workarounds to get this to work.  The "check"
>> statements appear to be designed to only take one parameter (in this case,
>> the path to the program), so I had to modify the grammar of "check program"
>> a bit.  But also, the order in which the statement is being parsed means the
>> Service_t hasn't been created yet when uid/gid are parsed.  So, I have to
>> save those in static global variables and then set them in the instance of
>> Service_t once it has been created.
>>
>>  So, testing this with something like "check program test-script with path
>> '/home/lgustafson/test-uid.sh' as uid 1000 as gid 1000 if status != 0 then
>> alert" worked for me.  The script was indeed run as my uid/gid.  The caveat
>> is the supplemental group list still contains root, so the script could
>> still modify writeable files owned by gid 0.  I'm not certain that there is
>> a portable solution for that, but it could be resolved on some of the
>> platforms you support.
>>
>>  Like I said, this is just a preliminary patch/brainstorming exercise.
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