[sudo-users] restrict shell out to root using sudo

Muhammad Habib mhabib73 at gmail.com
Sat Jul 10 23:20:38 EDT 2010

Hi Chris/Todd/Jackson,

Thanks very much and I appreciate your valuable input. This will help me to
finalize our sudo procedures and control for application team.



On Sat, Jul 10, 2010 at 1:51 PM, <highc at stny.rr.com> wrote:

> Muhammad Habib wrote:
>> Hi,
>> I am looking for restricting users to do shell out in their scripts. [...]
>>  I tried to stop it using "NOEXEC" function but that
>> will cause this script1 to run OK , but all commands in this script (eg.
>> ps
>> , uname etc.) will fail to run as well.
>> script1 is as follows:
>> ==============================
>> #!/bin/ksh
>> uname >> /tmp/myhost
>> ps -ef | grep db  >> /tmp/myproc
>> /bin/sh
>> ===============================
>> Thanks
>> Habib
>>  Todd's right, there's no way to stop someone from running arbitrary
> commands; however, you can consider instead authorizing them to run the
> commands withing the script; for instance...
> > ==============================
>  #!/bin/ksh
>  cp /tmp/myhost /tmp/$$.tmp
>  uname >> /tmp/$$.tmp
>  sudo cp /tmp/$$.tmp /tmp/myhost
>  cp /tmp/myproc /tmp/$$.tmp
>  ps -ef | grep db  >> /tmp/$$.tmp
>  sudo cp /tmp/$$.tmp /tmp/myproc
>  rm /tmp/$$.tmp
> Then you authorize them to run sudo for cp, with as tight as possible
> definition, instead of the script.  Modifiction of the script is less
> problematic since they can change 'details' around how the script can run,
> but cannot introduce any commands to run with root authority they are not
> already authorized to run.  You may need to set the sudo authorization with
> 'NOPASSWD' for the command, depending on how long the script might run, etc.
> Of course, you still need to trust this person, as there's some very
> unpleasent things they can do with cp as allowed above; but it has to be
> less risk than allowing them to run arbitrary commands.
> I know we are using this as 'just an example', but it seems to me the
> simplest solution here is to assign the user to a group; and give that group
> write authority to /tmp/myhost and /tmp/myproc.
> For example, say someone wants to be able to take a snap shot of how full
> -all- file systems are, now and again.
> capturedf.ksh
> #!/bin/ksh
> sudo df -k > /tmp/$$.tmp
> date >> /tmp/collected.df
> cat /tmp/$$.tmp >> /tmp/collected.df
> # do some processing on the file /tmp/$$.tmp
> # For instance, send an alert if a filesystem is over 90% full.
> [...]
> rm /tmp/$$.tmp
> =====
> You assign a particular group to be able to update /tmp/collected.df
> (presumably so someone debugging full file systems can see any historical
> data); the only thing in the script they need root authority for is 'df', so
> you authorize -that-.  The rest of the invokation doesn't need root
> authority, so you don't have them run as root... much safer.  (df can
> sometimes require root authority (or more authority than a particular user
> has) depending on the ownership/access rights on the mount points.) If they
> need to modify the script, it's not a big deal since all you really have
> done is give them the authority to run df.
> --
>  Good luck... Chris.
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