From: Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org>
To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: Linux FS Devel
<linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Linux Containers
<containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [REVIEW][PATCH 1/2] userns: Better restrictions on when proc and sysfs can be mounted
Date: Tue, 3 Sep 2013 10:40:36 -0700 [thread overview]
Message-ID: <CALCETrXRD3J-jrKXMSz=pC+m0xcL02ovf1xydKDOPmyCYNEM7Q@mail.gmail.com> (raw)
In-Reply-To: <87eh99noa0.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
On Sat, Aug 31, 2013 at 9:45 PM, Eric W. Biederman
<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> wrote:
> ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) writes:
>
>> Andy Lutomirski <luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org> writes:
>>
>>> On Tue, Aug 27, 2013 at 2:44 PM, Eric W. Biederman
>>> <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> wrote:
>>>>
>>>> Rely on the fact that another flavor of the filesystem is already
>>>> mounted and do not rely on state in the user namespace.
>>>
>>> Possibly dumb question: does this check whether the pre-existing mount
>>> has hidepid set?
>>
>> Not currently.
>>
>> It may be worth doing something with respect to hidepid. I forget what
>> hidepid tries to do, and I need to dash. But feel free to cook up a
>> follow on patch.
>
> So I have thought about this a bit more.
>
> hidepid hides the processes that ptrace_may_access will fail on.
>
> You can only reach the point where an unprivileged mount of a pid
> namespace is possible if you have created both a user namespace and a
> pid namespace. Which means the creator of the pid namespace will be
> capable of ptracing all of the other processes in the pid namespace
> (ignoring setns).
>
> So I don't see a point of worry about hidepid or the hidepid gid on
> child pid namespaces. The cases it is attempting to protecting against
> really don't exist.
Fair enough. I didn't realize that you had to own the pid namespace.
--Andy
next prev parent reply other threads:[~2013-09-03 17:40 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-27 21:44 [REVIEW][PATCH 1/2] userns: Better restrictions on when proc and sysfs can be mounted Eric W. Biederman
[not found] ` <878uzmhkqg.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-08-27 21:46 ` [REVIEW][PATCH 2/2] sysfs: Restrict mounting sysfs Eric W. Biederman
[not found] ` <874naahkng.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-08-28 19:00 ` Greg Kroah-Hartman
2013-09-23 10:33 ` James Hogan
[not found] ` <524018EA.9070202-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
2013-09-23 21:41 ` [PATCH] sysfs: Allow mounting without CONFIG_NET Eric W. Biederman
[not found] ` <87ioxrrzb6.fsf_-_-HxuHnoDHeQZYhcs0q7wBk77fW72O3V7zAL8bYrjMMd8@public.gmane.org>
2013-09-24 11:25 ` James Hogan
2013-08-27 21:47 ` [REVIEW][PATCH 1/2] userns: Better restrictions on when proc and sysfs can be mounted Andy Lutomirski
[not found] ` <CALCETrWPDzuoaJp2ko5jAbwYUBqSdPjvO5uGo-gZVsS4Wm1PKQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-08-27 21:57 ` Eric W. Biederman
2013-09-01 4:45 ` Eric W. Biederman
[not found] ` <87eh99noa0.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-09-03 17:40 ` Andy Lutomirski [this message]
2013-11-02 6:06 ` Gao feng
[not found] ` <52749663.2000701-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-11-04 7:00 ` Janne Karhunen
[not found] ` <CAE=NcrY+CzX+H4XQTdGj7CSZ98a5T=bNgT6=jGZzcjyaHb-ttw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-11-09 5:22 ` Eric W. Biederman
2013-11-08 2:33 ` Gao feng
[not found] ` <527C4D88.10907-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-11-09 5:42 ` Eric W. Biederman
[not found] ` <87k3gigmgj.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-11-13 7:26 ` Gao feng
[not found] ` <5283299B.8080702-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-11-14 11:10 ` Gao feng
[not found] ` <5284AF90.7060506-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-11-14 16:54 ` Andy Lutomirski
2013-11-15 1:16 ` Gao feng
[not found] ` <528575EC.2030309-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-11-15 4:54 ` Eric W. Biederman
[not found] ` <87txfexo25.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2013-11-15 6:14 ` Gao feng
[not found] ` <5285BBE2.7010001-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
2013-11-15 8:37 ` Eric W. Biederman
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