Re: [CFT][PATCH 7/8] userns: Add a knob to disable setgroups on a per user namespace basis

From: Andy Lutomirski
Date: Tue Dec 09 2014 - 19:21:53 EST

On Tue, Dec 9, 2014 at 4:04 PM, Eric W.Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> On December 9, 2014 4:28:38 PM CST, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>>On Tue, Dec 9, 2014 at 12:42 PM, Eric W. Biederman
>><ebiederm@xxxxxxxxxxxx> wrote:
>>> - Expose the knob to user space through a proc file
>>> A value of "deny" means the setgroups system call is disabled in
>>> current processes user namespace and can not be enabled in the
>>> future in this user namespace.
>>> A value of "allow" means the segtoups system call is enabled.
>>> - Descendant user namespaces inherit the value of setgroups from
>>> their parents.
>>> - A proc file is used (instead of a sysctl) as sysctls
>>> currently do not pass in a struct file so file_ns_capable
>>> is unusable.
>>Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
>>But I still don't like the name "setgroups". People may look at that
>>and have no clue what the scope of the setting is. And anyone who, as
>>root, writes "deny" to /proc/self/setgroups, thinking that it acts on
>>self, will be in for a surprise.
> True setgroups isn't perfect. Documenting it in a manpage may have to be enough. The only real improvement I can think of would be to make the setting a sysctl. But I think pursuing that approaches the point where perfection is the enemy of getting this problem fixed.

Would "userns_setgroups" be okay?


> Eric

Andy Lutomirski
AMA Capital Management, LLC
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