Re: For review: user_namespace(7) man page

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

 



On Tue, Sep 9, 2014 at 9:05 AM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>
> We may also want to discuss the specific restrictions on chroot.
>
> The text about chroot at least gives people a strong hint that the
> chroot rules are affected by user namespaces.
>
> The restrictions that we have settled on to avoid chroot being a problem
> are the creator of a user namespace must not be chrooted in their
> current mount namespace, and the creator of the user namespace must not
> be threaded.
>
> Andy can you check me on this it looks like unshare is currently buggy
> in that it will allow a threaded application to create a user namespace.

I think it's this code in unshare:

    /*
     * If unsharing a user namespace must also unshare the thread.
     */
    if (unshare_flags & CLONE_NEWUSER)
        unshare_flags |= CLONE_THREAD | CLONE_FS;

I suppose that this should be documented.

CLONE_FS prevents the chroot from leaking out of the namespace.  (But
see the other thread that I'm about to start...)

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




[Index of Archives]     [Kernel Documentation]     [Netdev]     [Linux Ethernet Bridging]     [Linux Wireless]     [Kernel Newbies]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]

  Powered by Linux