Re: [PATCH 2/2] groups: Allow unprivileged processes to use setgroups to drop groups

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On November 15, 2014 6:05:11 PM PST, Theodore Ts'o <tytso@xxxxxxx> wrote:
>On Sat, Nov 15, 2014 at 12:20:42PM -0800, Josh Triplett wrote:
>> > However, sudoers seems to allow negative group matches.  So maybe
>> > allowing this only with no_new_privs already set would make sense.
>> 
>> Sigh, bad sudo.  Sure, restricting this to no_new_privs only seems
>fine.
>> I'll do that in v2, and document that in the manpage.
>
>I've also seen use cases (generally back in the bad old days of big
>timesharing VAX 750's :-) where the system admin might assign someone
>to the "games-abusers" group, and then set /usr/games to mode 705
>root:games-abusers --- presumably because it's easier to add a few
>people to the deny list rather than having to add all of the EECS
>department to the games group minus the abusers.
>
>So arbitrarily anyone to drop groups from their supplemental group
>list will result in a change from both existing practice and legacy
>Unix systems, and it could potentially lead to a security exposure.

As Andy pointed out, you can already do that with a user namespace, for any case not involving a setuid or setgid (or otherwise privilege-gaining) program.  And requiring no_new_privs handles that.

Given the combination of those two things, do you still see any problematic cases?

- Josh Triplett

--
To unsubscribe from this list: send the line "unsubscribe linux-api" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux