From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Will Drewry <wad@chromium.org>,
linux-kernel@vger.kernel.org, keescook@chromium.org,
john.johansen@canonical.com, serge.hallyn@canonical.com,
coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com,
djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org,
jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com,
penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu,
akpm@linux-foundation.org, khilman@ti.com,
borislav.petkov@amd.com, amwang@redhat.com, oleg@redhat.com,
ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de,
dhowells@redhat.com, daniel.lezcano@free.fr,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, olofj@chromium.org,
mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch
Date: Thu, 12 Jan 2012 16:57:20 -0800 [thread overview]
Message-ID: <CA+55aFzzRNHfSo-1DyzsAwYvj1Da-vyhMQP-OdrA-rWywsebcg@mail.gmail.com> (raw)
In-Reply-To: <CAObL_7FErN5CHmfSehJYcM0_Lz-WTywG7cHe2jZyQbf-GkOQjg@mail.gmail.com>
On Thu, Jan 12, 2012 at 4:42 PM, Andrew Lutomirski <luto@mit.edu> wrote:
>
> That may prevent another use: set this new flag, chroot, drop
> privileges, accept network connections. (The idea being that chroot
> might work unprivileged if this flag is set.)
Well, if you have privileges, then just do
chroot();
drop privileges
and if you depend on the new flag, then you do
drop privileges
set new flag
chroot
and if you want to work either way then you just do
error = chroot
drop privileges
set new flag
if error
chroot
which does the right thing regardless of whether you had privileges
and/or a new kernel or not.
In any of the three cases I don't see why you'd ever want to drop
privileges *after* setting the new flag.
Linus
WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Will Drewry <wad@chromium.org>,
linux-kernel@vger.kernel.org, keescook@chromium.org,
john.johansen@canonical.com, serge.hallyn@canonical.com,
coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com,
djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org,
jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com,
penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu,
akpm@linux-foundation.org, khilman@ti.com,
borislav.petkov@amd.com, amwang@redhat.com, oleg@redhat.com,
ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de,
dhowells@redhat.com, daniel.lezcano@free.fr,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, olofj@chromium.org,
mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch
Date: Thu, 12 Jan 2012 16:57:20 -0800 [thread overview]
Message-ID: <CA+55aFzzRNHfSo-1DyzsAwYvj1Da-vyhMQP-OdrA-rWywsebcg@mail.gmail.com> (raw)
In-Reply-To: <CAObL_7FErN5CHmfSehJYcM0_Lz-WTywG7cHe2jZyQbf-GkOQjg@mail.gmail.com>
On Thu, Jan 12, 2012 at 4:42 PM, Andrew Lutomirski <luto@mit.edu> wrote:
>
> That may prevent another use: set this new flag, chroot, drop
> privileges, accept network connections. (The idea being that chroot
> might work unprivileged if this flag is set.)
Well, if you have privileges, then just do
chroot();
drop privileges
and if you depend on the new flag, then you do
drop privileges
set new flag
chroot
and if you want to work either way then you just do
error = chroot
drop privileges
set new flag
if error
chroot
which does the right thing regardless of whether you had privileges
and/or a new kernel or not.
In any of the three cases I don't see why you'd ever want to drop
privileges *after* setting the new flag.
Linus
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next prev parent reply other threads:[~2012-01-13 0:57 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-12 23:38 [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Will Drewry
2012-01-12 23:38 ` [PATCH v3 2/3] seccomp_filters: system call filtering using BPF Will Drewry
2012-01-13 0:51 ` Randy Dunlap
2012-01-12 23:59 ` Will Drewry
2012-01-12 23:59 ` Will Drewry
2012-01-13 1:35 ` Randy Dunlap
2012-01-13 17:39 ` Eric Paris
2012-01-13 18:50 ` Will Drewry
2012-01-13 18:50 ` Will Drewry
2012-01-12 23:38 ` [PATCH v3 3/3] Documentation: prctl/seccomp_filter Will Drewry
2012-01-15 1:52 ` Randy Dunlap
2012-01-16 1:41 ` Will Drewry
2012-01-17 23:29 ` Eric Paris
2012-01-17 23:29 ` Eric Paris
2012-01-17 23:54 ` Will Drewry
2012-01-12 23:47 ` [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Linus Torvalds
2012-01-13 0:03 ` Will Drewry
2012-01-13 0:42 ` Andrew Lutomirski
2012-01-13 0:57 ` Linus Torvalds [this message]
2012-01-13 0:57 ` Linus Torvalds
2012-01-13 1:11 ` Andrew Lutomirski
2012-01-13 1:11 ` Andrew Lutomirski
2012-01-13 1:17 ` Linus Torvalds
2012-01-14 13:30 ` Jamie Lokier
2012-01-14 19:21 ` Will Drewry
2012-01-14 19:21 ` Will Drewry
2012-01-14 20:22 ` Linus Torvalds
2012-01-14 21:04 ` Andrew Lutomirski
2012-01-15 20:16 ` Casey Schaufler
2012-01-15 20:59 ` Andrew Lutomirski
2012-01-15 21:32 ` Casey Schaufler
2012-01-15 21:32 ` Casey Schaufler
2012-01-15 22:07 ` Andrew Lutomirski
2012-01-16 2:04 ` Will Drewry
2012-01-16 2:04 ` Will Drewry
2012-01-18 3:12 ` Eric W. Biederman
2012-01-18 3:12 ` Eric W. Biederman
2012-01-16 2:41 ` Casey Schaufler
2012-01-16 2:41 ` Casey Schaufler
2012-01-16 7:45 ` Andrew Lutomirski
2012-01-16 18:02 ` Casey Schaufler
2012-01-16 18:02 ` Casey Schaufler
2012-01-13 1:37 ` Will Drewry
2012-01-13 1:41 ` Andrew Lutomirski
2012-01-13 1:41 ` Andrew Lutomirski
2012-01-13 2:09 ` Kees Cook
2012-01-13 2:09 ` Kees Cook
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