Re: [PATCH 2/2] user_namespaces.7: Update the documention to reflect the fixes for negative groups

[Alban Crequy]

Hello,

Thanks for updating the man page.

On 12 December 2014 at 22:54, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
(...)
> Furthermore to preserve in some form the useful applications that have
> been setting gid_map without privilege the file /proc/[pid]/setgroups
> was added to allow disabling setgroups.  With the setgroups system
> call permanently disabled in a user namespace it again becomes safe to
> allow writes to gid_map without privilege.
>
> Here is my meager attempt to update user_namespaces.7 to reflect these
> issues.

The program userns_child_exec.c in user_namespaces.7 should be updated
to write in /proc/.../setgroups, near the line:
/* Update the UID and GID maps in the child */

Otherwise, the example given in the manpage does not work:
$ ./userns_child_exec -p -m -U -M '0 1000 1' -G '0 1000 1' bash

Cheers,
Alban
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