From: Oleg Nesterov <oleg@redhat.com>
To: Kees Cook <keescook@chromium.org>
Cc: Jann Horn <jann@thejh.net>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Roland McGrath <roland@hack.frob.com>,
John Johansen <john.johansen@canonical.com>,
James Morris <james.l.morris@oracle.com>,
"Serge E. Hallyn" <serge@hallyn.com>,
Paul Moore <aul@paul-moore.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
Eric Paris <eparis@parisplace.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Andrew Morton <akpm@linux-foundation.org>,
Janis Danisevskis <jdanis@google.com>,
Seth Forshee <seth.forshee@canonical.com>,
"Eric . Biederman" <ebiederm@xmission.com>,
Thomas Gleixner <tglx@linutronix.de>,
Benjamin LaHaise <bcrl@kvack.org>,
Ben Hutchings <ben@decadent.org.uk>,
Andy Lutomirski <luto@amacapital.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
"security@kernel.org" <security@kernel.org>
Subject: Re: [PATCH v2 2/8] exec: turn self_exec_id into self_privunit
Date: Mon, 3 Oct 2016 18:37:53 +0200 [thread overview]
Message-ID: <20161003163753.GA6634@redhat.com> (raw)
In-Reply-To: <CAGXu5j+Oe+Be+ca+V3OKZCUiFzqQtj6CoH=FeEWvY98YfcoJxQ@mail.gmail.com>
On 09/30, Kees Cook wrote:
>
> On Fri, Sep 30, 2016 at 6:44 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> > forgot to mention...
> >
> > On 09/30, Oleg Nesterov wrote:
> >>
> >> On 09/23, Jann Horn wrote:
> >> >
> >> > One reason for doing this is that it prevents an attacker from sending an
> >> > arbitrary signal to a parent process after performing 2^32-1 execve()
> >> > calls.
> >
> > No, sets ->exit_signal = SIGCHLD. So the only problem is that the parent
> > can do clone(SIGKILL), then do execve() 2^32-1 times, then it can be killed
> > by SIGKILL from the exiting child.
> >
> > Honestly, I do not think this is security problem.
>
> It's a corner case, to be sure. But even sending a SIGKILL across
> privilege boundaries should not be allowed to happen.
Agreed, and actually I need to take my words back, of course this is not
nice security-wise.
So lets kill these counters. At least they should not live in task_struct.
Oleg.
next prev parent reply other threads:[~2016-10-03 16:39 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-23 20:40 [PATCH v2 0/8] Various fixes related to ptrace_may_access() Jann Horn
2016-09-23 20:40 ` [PATCH v2 1/8] exec: introduce cred_guard_light Jann Horn
2016-09-30 15:35 ` Oleg Nesterov
2016-09-30 18:27 ` Eric W. Biederman
2016-10-03 16:02 ` Oleg Nesterov
2016-10-30 21:12 ` Jann Horn
2016-09-23 20:40 ` [PATCH v2 2/8] exec: turn self_exec_id into self_privunit Jann Horn
2016-09-23 21:04 ` Andy Lutomirski
2016-09-23 21:33 ` Jann Horn
2016-09-30 13:20 ` Oleg Nesterov
2016-09-30 13:44 ` Oleg Nesterov
2016-09-30 18:30 ` Kees Cook
2016-09-30 18:59 ` Jann Horn
2016-09-30 19:05 ` Kees Cook
2016-10-03 16:37 ` Oleg Nesterov [this message]
2016-09-23 20:40 ` [PATCH v2 3/8] proc: use open()-time creds for ptrace checks Jann Horn
2016-09-23 20:40 ` [PATCH v2 4/8] futex: don't leak robust_list pointer Jann Horn
2016-09-30 14:52 ` Oleg Nesterov
2016-10-30 17:16 ` Jann Horn
2016-11-02 21:39 ` Jann Horn
2016-11-02 22:47 ` Jann Horn
2016-09-23 20:40 ` [PATCH v2 5/8] proc: lock properly in ptrace_may_access callers Jann Horn
2016-09-23 20:40 ` [PATCH v2 6/8] ptrace: warn on ptrace_may_access without proper locking Jann Horn
2016-09-23 20:40 ` [PATCH v2 7/8] fs/proc: fix attr access check Jann Horn
2016-09-23 20:40 ` [PATCH v2 8/8] Documentation: add security/ptrace_checks.txt Jann Horn
2016-10-02 3:16 ` Krister Johansen
2016-10-30 19:09 ` Jann Horn
2016-10-31 4:14 ` Eric W. Biederman
2016-10-31 13:39 ` Jann Horn
2016-11-03 20:43 ` Krister Johansen
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