From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id 7B9B26B036B for ; Thu, 17 Nov 2016 18:14:25 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id i131so986223wmf.3 for ; Thu, 17 Nov 2016 15:14:25 -0800 (PST) Received: from mail-wm0-x22d.google.com (mail-wm0-x22d.google.com. [2a00:1450:400c:c09::22d]) by mx.google.com with ESMTPS id bt18si4905247wjb.137.2016.11.17.15.14.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 17 Nov 2016 15:14:24 -0800 (PST) Received: by mail-wm0-x22d.google.com with SMTP id c184so900830wmd.0 for ; Thu, 17 Nov 2016 15:14:23 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <87oa1eavfx.fsf_-_@xmission.com> References: <87twcbq696.fsf@x220.int.ebiederm.org> <20161018135031.GB13117@dhcp22.suse.cz> <8737jt903u.fsf@xmission.com> <20161018150507.GP14666@pc.thejh.net> <87twc9656s.fsf@xmission.com> <20161018191206.GA1210@laptop.thejh.net> <87r37dnz74.fsf@xmission.com> <87k2d5nytz.fsf_-_@xmission.com> <87y41kjn6l.fsf@xmission.com> <20161019172917.GE1210@laptop.thejh.net> <87pomwi5p2.fsf@xmission.com> <87pomwghda.fsf@xmission.com> <87twb6avk8.fsf_-_@xmission.com> <87oa1eavfx.fsf_-_@xmission.com> From: Kees Cook Date: Thu, 17 Nov 2016 15:14:22 -0800 Message-ID: Subject: Re: [REVIEW][PATCH 1/3] ptrace: Capture the ptracer's creds not PT_PTRACE_CAP Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: "Eric W. Biederman" Cc: Linux Containers , Oleg Nesterov , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Linux FS Devel , Michal Hocko , Jann Horn , Willy Tarreau , Andy Lutomirski On Thu, Nov 17, 2016 at 9:05 AM, Eric W. Biederman wrote: > > When the flag PT_PTRACE_CAP was added the PTRACE_TRACEME path was > overlooked. This can result in incorrect behavior when an application > like strace traces an exec of a setuid executable. > > Further PT_PTRACE_CAP does not have enough information for making good > security decisions as it does not report which user namespace the > capability is in. This has already allowed one mistake through > insufficient granulariy. > > I found this issue when I was testing another corner case of exec and > discovered that I could not get strace to set PT_PTRACE_CAP even when > running strace as root with a full set of caps. > > This change fixes the above issue with strace allowing stracing as > root a setuid executable without disabling setuid. More fundamentaly > this change allows what is allowable at all times, by using the correct > information in it's decision. > > Cc: stable@vger.kernel.org > Fixes: 4214e42f96d4 ("v2.4.9.11 -> v2.4.9.12") > Signed-off-by: "Eric W. Biederman" > --- > [...] > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 348f51b0ec92..8fe58255d219 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1656,6 +1656,7 @@ struct task_struct { > struct list_head cpu_timers[3]; > > /* process credentials */ > + const struct cred __rcu *ptracer_cred; /* Tracer's dredentials at attach */ Typo: credentials. -Kees -- Kees Cook Nexus Security -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org