From: "Luis R. Rodriguez" <mcgrof@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>,
Djalal Harouni <tixxdz@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
James Morris <james.l.morris@oracle.com>,
Ben Hutchings <ben.hutchings@codethink.co.uk>,
Solar Designer <solar@openwall.com>,
Serge Hallyn <serge@hallyn.com>, Jessica Yu <jeyu@kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>,
LKML <linux-kernel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
kernel-hardening@lists.openwall.com,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Network Development <netdev@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v5 next 1/5] modules:capabilities: add request_module_cap()
Date: Tue, 28 Nov 2017 23:12:37 +0100 [thread overview]
Message-ID: <20171128221237.GR729@wotan.suse.de> (raw)
In-Reply-To: <CAGXu5j+JaFCo+pZKvet==Kh7GQgNXi30P50SMF4cpOGoUw-8ug@mail.gmail.com>
On Tue, Nov 28, 2017 at 01:39:58PM -0800, Kees Cook wrote:
> On Tue, Nov 28, 2017 at 1:16 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > And *all* auto-loading uses aliases? What's the difference between auto-loading
> > and direct-loading?
>
> The difference is the process privileges. Unprivilged autoloading
> (e.g. int n_hdlc = N_HDLC; ioctl(fd,
> TIOCSETD, &n_hdlc)), triggers a privileged call to finit_module()
> under CAP_SYS_MODULE.
Ah, so system call implicated request_module() calls.
> >> We already have a global sysctl for blocking direct-loading (modules_disabled).
> >
> > My point was that even if you have a CAP_NET_ADMIN check on request_module(),
> > finit_module() will not check for it, so a crafty userspace could still try
> > to just finit_module() directly, and completely then bypass the CAP_NET_ADMIN
> > check.
>
> You need CAP_SYS_MODULE to run finit_module().
OK and since CAP_SYS_MODULE is much more restrictive one could argue, what's the
point here?
Luis
WARNING: multiple messages have this Message-ID (diff)
From: mcgrof@kernel.org (Luis R. Rodriguez)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v5 next 1/5] modules:capabilities: add request_module_cap()
Date: Tue, 28 Nov 2017 23:12:37 +0100 [thread overview]
Message-ID: <20171128221237.GR729@wotan.suse.de> (raw)
In-Reply-To: <CAGXu5j+JaFCo+pZKvet==Kh7GQgNXi30P50SMF4cpOGoUw-8ug@mail.gmail.com>
On Tue, Nov 28, 2017 at 01:39:58PM -0800, Kees Cook wrote:
> On Tue, Nov 28, 2017 at 1:16 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > And *all* auto-loading uses aliases? What's the difference between auto-loading
> > and direct-loading?
>
> The difference is the process privileges. Unprivilged autoloading
> (e.g. int n_hdlc = N_HDLC; ioctl(fd,
> TIOCSETD, &n_hdlc)), triggers a privileged call to finit_module()
> under CAP_SYS_MODULE.
Ah, so system call implicated request_module() calls.
> >> We already have a global sysctl for blocking direct-loading (modules_disabled).
> >
> > My point was that even if you have a CAP_NET_ADMIN check on request_module(),
> > finit_module() will not check for it, so a crafty userspace could still try
> > to just finit_module() directly, and completely then bypass the CAP_NET_ADMIN
> > check.
>
> You need CAP_SYS_MODULE to run finit_module().
OK and since CAP_SYS_MODULE is much more restrictive one could argue, what's the
point here?
Luis
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WARNING: multiple messages have this Message-ID (diff)
From: "Luis R. Rodriguez" <mcgrof@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>,
Djalal Harouni <tixxdz@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
James Morris <james.l.morris@oracle.com>,
Ben Hutchings <ben.hutchings@codethink.co.uk>,
Solar Designer <solar@openwall.com>,
Serge Hallyn <serge@hallyn.com>, Jessica Yu <jeyu@kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>,
LKML <linux-kernel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
kernel-hardening@lists.openwall.com,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Network Development <netdev@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [kernel-hardening] Re: [PATCH v5 next 1/5] modules:capabilities: add request_module_cap()
Date: Tue, 28 Nov 2017 23:12:37 +0100 [thread overview]
Message-ID: <20171128221237.GR729@wotan.suse.de> (raw)
In-Reply-To: <CAGXu5j+JaFCo+pZKvet==Kh7GQgNXi30P50SMF4cpOGoUw-8ug@mail.gmail.com>
On Tue, Nov 28, 2017 at 01:39:58PM -0800, Kees Cook wrote:
> On Tue, Nov 28, 2017 at 1:16 PM, Luis R. Rodriguez <mcgrof@kernel.org> wrote:
> > And *all* auto-loading uses aliases? What's the difference between auto-loading
> > and direct-loading?
>
> The difference is the process privileges. Unprivilged autoloading
> (e.g. int n_hdlc = N_HDLC; ioctl(fd,
> TIOCSETD, &n_hdlc)), triggers a privileged call to finit_module()
> under CAP_SYS_MODULE.
Ah, so system call implicated request_module() calls.
> >> We already have a global sysctl for blocking direct-loading (modules_disabled).
> >
> > My point was that even if you have a CAP_NET_ADMIN check on request_module(),
> > finit_module() will not check for it, so a crafty userspace could still try
> > to just finit_module() directly, and completely then bypass the CAP_NET_ADMIN
> > check.
>
> You need CAP_SYS_MODULE to run finit_module().
OK and since CAP_SYS_MODULE is much more restrictive one could argue, what's the
point here?
Luis
next prev parent reply other threads:[~2017-11-28 22:12 UTC|newest]
Thread overview: 266+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-27 17:18 [PATCH v5 next 0/5] Improve Module autoloading infrastructure Djalal Harouni
2017-11-27 17:18 ` [kernel-hardening] " Djalal Harouni
2017-11-27 17:18 ` Djalal Harouni
2017-11-27 17:18 ` [PATCH v5 next 1/5] modules:capabilities: add request_module_cap() Djalal Harouni
2017-11-27 17:18 ` [kernel-hardening] " Djalal Harouni
2017-11-27 17:18 ` Djalal Harouni
2017-11-27 18:48 ` Randy Dunlap
2017-11-27 18:48 ` [kernel-hardening] " Randy Dunlap
2017-11-27 18:48 ` Randy Dunlap
2017-11-27 21:35 ` Djalal Harouni
2017-11-27 21:35 ` [kernel-hardening] " Djalal Harouni
2017-11-27 21:35 ` Djalal Harouni
2017-11-28 19:14 ` Luis R. Rodriguez
2017-11-28 19:14 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-28 19:14 ` Luis R. Rodriguez
2017-11-28 20:11 ` Kees Cook
2017-11-28 20:11 ` [kernel-hardening] " Kees Cook
2017-11-28 20:11 ` Kees Cook
2017-11-28 21:16 ` Luis R. Rodriguez
2017-11-28 21:16 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-28 21:16 ` Luis R. Rodriguez
2017-11-28 21:33 ` Djalal Harouni
2017-11-28 21:33 ` [kernel-hardening] " Djalal Harouni
2017-11-28 21:33 ` Djalal Harouni
2017-11-28 22:18 ` Luis R. Rodriguez
2017-11-28 22:18 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-28 22:18 ` Luis R. Rodriguez
2017-11-28 22:52 ` Djalal Harouni
2017-11-28 22:52 ` [kernel-hardening] " Djalal Harouni
2017-11-28 22:52 ` Djalal Harouni
2017-11-28 21:39 ` Kees Cook
2017-11-28 21:39 ` [kernel-hardening] " Kees Cook
2017-11-28 21:39 ` Kees Cook
2017-11-28 22:12 ` Luis R. Rodriguez [this message]
2017-11-28 22:12 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-28 22:12 ` Luis R. Rodriguez
2017-11-28 22:18 ` Kees Cook
2017-11-28 22:18 ` [kernel-hardening] " Kees Cook
2017-11-28 22:18 ` Kees Cook
2017-11-28 22:48 ` Luis R. Rodriguez
2017-11-28 22:48 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-28 22:48 ` Luis R. Rodriguez
2017-11-29 7:49 ` Michal Kubecek
2017-11-29 7:49 ` [kernel-hardening] " Michal Kubecek
2017-11-29 7:49 ` Michal Kubecek
2017-11-29 13:46 ` Alan Cox
2017-11-29 13:46 ` [kernel-hardening] " Alan Cox
2017-11-29 13:46 ` Alan Cox
2017-11-29 14:50 ` David Miller
2017-11-29 14:50 ` [kernel-hardening] " David Miller
2017-11-29 14:50 ` David Miller
2017-11-29 15:54 ` Theodore Ts'o
2017-11-29 15:54 ` [kernel-hardening] " Theodore Ts'o
2017-11-29 15:54 ` Theodore Ts'o
2017-11-29 15:58 ` David Miller
2017-11-29 15:58 ` [kernel-hardening] " David Miller
2017-11-29 15:58 ` David Miller
2017-11-29 16:29 ` Theodore Ts'o
2017-11-29 16:29 ` [kernel-hardening] " Theodore Ts'o
2017-11-29 16:29 ` Theodore Ts'o
2017-11-29 22:45 ` Linus Torvalds
2017-11-29 22:45 ` [kernel-hardening] " Linus Torvalds
2017-11-29 22:45 ` Linus Torvalds
2017-11-29 22:45 ` Linus Torvalds
2017-11-30 0:06 ` Kees Cook
2017-11-30 0:06 ` [kernel-hardening] " Kees Cook
2017-11-30 0:06 ` Kees Cook
2017-11-30 0:06 ` Kees Cook
2017-11-29 17:28 ` Serge E. Hallyn
2017-11-29 17:28 ` [kernel-hardening] " Serge E. Hallyn
2017-11-29 17:28 ` Serge E. Hallyn
2017-11-30 0:35 ` Theodore Ts'o
2017-11-30 0:35 ` [kernel-hardening] " Theodore Ts'o
2017-11-30 0:35 ` Theodore Ts'o
2017-11-30 17:17 ` Serge E. Hallyn
2017-11-30 17:17 ` [kernel-hardening] " Serge E. Hallyn
2017-11-30 17:17 ` Serge E. Hallyn
2017-11-28 20:18 ` Djalal Harouni
2017-11-28 20:18 ` [kernel-hardening] " Djalal Harouni
2017-11-28 20:18 ` Djalal Harouni
2017-11-27 17:18 ` [PATCH v5 next 2/5] modules:capabilities: add cap_kernel_module_request() permission check Djalal Harouni
2017-11-27 17:18 ` [kernel-hardening] " Djalal Harouni
2017-11-27 17:18 ` Djalal Harouni
2017-11-30 2:05 ` Luis R. Rodriguez
2017-11-30 2:05 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-30 2:05 ` Luis R. Rodriguez
2017-11-27 17:18 ` [PATCH v5 next 3/5] modules:capabilities: automatic module loading restriction Djalal Harouni
2017-11-27 17:18 ` [kernel-hardening] " Djalal Harouni
2017-11-27 17:18 ` Djalal Harouni
2017-11-30 1:23 ` Luis R. Rodriguez
2017-11-30 1:23 ` [kernel-hardening] " Luis R. Rodriguez
2017-11-30 1:23 ` Luis R. Rodriguez
2017-11-30 12:22 ` Djalal Harouni
2017-11-30 12:22 ` [kernel-hardening] " Djalal Harouni
2017-11-30 12:22 ` Djalal Harouni
2017-11-27 17:18 ` [PATCH v5 next 4/5] modules:capabilities: add a per-task modules auto-load mode Djalal Harouni
2017-11-27 17:18 ` [kernel-hardening] " Djalal Harouni
2017-11-27 17:18 ` Djalal Harouni
2017-11-27 17:18 ` [PATCH v5 next 5/5] net: modules: use request_module_cap() to load 'netdev-%s' modules Djalal Harouni
2017-11-27 17:18 ` [kernel-hardening] " Djalal Harouni
2017-11-27 17:18 ` Djalal Harouni
2017-11-27 18:44 ` Linus Torvalds
2017-11-27 18:44 ` [kernel-hardening] " Linus Torvalds
2017-11-27 18:44 ` Linus Torvalds
2017-11-27 18:44 ` Linus Torvalds
2017-11-27 21:41 ` Djalal Harouni
2017-11-27 21:41 ` [kernel-hardening] " Djalal Harouni
2017-11-27 21:41 ` Djalal Harouni
2017-11-27 21:41 ` Djalal Harouni
2017-11-27 22:04 ` Linus Torvalds
2017-11-27 22:04 ` [kernel-hardening] " Linus Torvalds
2017-11-27 22:04 ` Linus Torvalds
2017-11-27 22:04 ` Linus Torvalds
2017-11-27 22:59 ` Kees Cook
2017-11-27 22:59 ` [kernel-hardening] " Kees Cook
2017-11-27 22:59 ` Kees Cook
2017-11-27 22:59 ` Kees Cook
2017-11-27 23:14 ` Linus Torvalds
2017-11-27 23:14 ` [kernel-hardening] " Linus Torvalds
2017-11-27 23:14 ` Linus Torvalds
2017-11-27 23:14 ` Linus Torvalds
2017-11-27 23:19 ` Kees Cook
2017-11-27 23:19 ` [kernel-hardening] " Kees Cook
2017-11-27 23:19 ` Kees Cook
2017-11-27 23:19 ` Kees Cook
2017-11-27 23:35 ` Linus Torvalds
2017-11-27 23:35 ` [kernel-hardening] " Linus Torvalds
2017-11-27 23:35 ` Linus Torvalds
2017-11-27 23:35 ` Linus Torvalds
2017-11-28 1:23 ` Kees Cook
2017-11-28 1:23 ` [kernel-hardening] " Kees Cook
2017-11-28 1:23 ` Kees Cook
2017-11-28 1:23 ` Kees Cook
2017-11-28 12:16 ` [kernel-hardening] " Geo Kozey
2017-11-28 12:16 ` Geo Kozey
2017-11-28 12:16 ` Geo Kozey
2017-11-28 19:32 ` Theodore Ts'o
2017-11-28 19:32 ` Theodore Ts'o
2017-11-28 19:32 ` Theodore Ts'o
2017-11-28 20:08 ` Kees Cook
2017-11-28 20:08 ` Kees Cook
2017-11-28 20:08 ` Kees Cook
2017-11-28 20:12 ` Linus Torvalds
2017-11-28 20:12 ` Linus Torvalds
2017-11-28 20:12 ` Linus Torvalds
2017-11-28 20:20 ` Kees Cook
2017-11-28 20:20 ` Kees Cook
2017-11-28 20:20 ` Kees Cook
2017-11-28 20:33 ` Linus Torvalds
2017-11-28 20:33 ` Linus Torvalds
2017-11-28 20:33 ` Linus Torvalds
2017-11-28 21:10 ` Djalal Harouni
2017-11-28 21:10 ` Djalal Harouni
2017-11-28 21:10 ` Djalal Harouni
2017-11-28 21:33 ` Kees Cook
2017-11-28 21:33 ` Kees Cook
2017-11-28 21:33 ` Kees Cook
2017-11-28 23:23 ` Theodore Ts'o
2017-11-28 23:23 ` Theodore Ts'o
2017-11-28 23:23 ` Theodore Ts'o
2017-11-28 23:29 ` Kees Cook
2017-11-28 23:29 ` Kees Cook
2017-11-28 23:29 ` Kees Cook
2017-11-28 23:49 ` Theodore Ts'o
2017-11-28 23:49 ` Theodore Ts'o
2017-11-28 23:49 ` Theodore Ts'o
2017-11-29 0:18 ` Kees Cook
2017-11-29 0:18 ` Kees Cook
2017-11-29 0:18 ` Kees Cook
2017-11-29 6:36 ` Theodore Ts'o
2017-11-29 6:36 ` Theodore Ts'o
2017-11-29 6:36 ` Theodore Ts'o
2017-11-29 14:46 ` Geo Kozey
2017-11-29 14:46 ` Geo Kozey
2017-11-29 14:46 ` Geo Kozey
2017-12-01 15:22 ` Marcus Meissner
2017-12-01 15:22 ` Marcus Meissner
2017-12-01 15:22 ` Marcus Meissner
2017-11-28 23:53 ` Djalal Harouni
2017-11-28 23:53 ` Djalal Harouni
2017-11-28 23:53 ` Djalal Harouni
2017-11-28 21:51 ` Geo Kozey
2017-11-28 21:51 ` Geo Kozey
2017-11-28 21:51 ` Geo Kozey
2017-11-28 23:51 ` Linus Torvalds
2017-11-28 23:51 ` Linus Torvalds
2017-11-28 23:51 ` Linus Torvalds
2017-11-29 0:17 ` Linus Torvalds
2017-11-29 0:17 ` Linus Torvalds
2017-11-29 0:17 ` Linus Torvalds
2017-11-29 0:26 ` Kees Cook
2017-11-29 0:26 ` Kees Cook
2017-11-29 0:26 ` Kees Cook
2017-11-29 0:50 ` Linus Torvalds
2017-11-29 0:50 ` Linus Torvalds
2017-11-29 0:50 ` Linus Torvalds
2017-11-29 4:26 ` Eric W. Biederman
2017-11-29 4:26 ` Eric W. Biederman
2017-11-29 4:26 ` Eric W. Biederman
2017-11-29 18:30 ` Kees Cook
2017-11-29 18:30 ` Kees Cook
2017-11-29 18:30 ` Kees Cook
2017-11-29 18:46 ` Linus Torvalds
2017-11-29 18:46 ` Linus Torvalds
2017-11-29 18:46 ` Linus Torvalds
2017-11-29 18:53 ` Linus Torvalds
2017-11-29 18:53 ` Linus Torvalds
2017-11-29 18:53 ` Linus Torvalds
2017-11-29 21:17 ` Kees Cook
2017-11-29 21:17 ` Kees Cook
2017-11-29 21:17 ` Kees Cook
2017-11-29 22:14 ` Linus Torvalds
2017-11-29 22:14 ` Linus Torvalds
2017-11-29 22:14 ` Linus Torvalds
2017-11-30 0:44 ` Kees Cook
2017-11-30 0:44 ` Kees Cook
2017-11-30 0:44 ` Kees Cook
2017-11-30 2:08 ` Linus Torvalds
2017-11-30 2:08 ` Linus Torvalds
2017-11-30 2:08 ` Linus Torvalds
2017-11-30 6:51 ` Daniel Micay
2017-11-30 6:51 ` Daniel Micay
2017-11-30 6:51 ` Daniel Micay
2017-11-30 8:50 ` Djalal Harouni
2017-11-30 8:50 ` Djalal Harouni
2017-11-30 8:50 ` Djalal Harouni
2017-11-30 14:16 ` Theodore Ts'o
2017-11-30 14:16 ` Theodore Ts'o
2017-11-30 14:16 ` Theodore Ts'o
2017-11-30 14:51 ` Djalal Harouni
2017-11-30 14:51 ` Djalal Harouni
2017-11-30 14:51 ` Djalal Harouni
2017-12-01 6:39 ` Daniel Micay
2017-12-01 6:39 ` Daniel Micay
2017-12-01 6:39 ` Daniel Micay
2017-11-29 15:28 ` Geo Kozey
2017-11-29 15:28 ` Geo Kozey
2017-11-29 15:28 ` Geo Kozey
2017-11-27 18:41 ` [PATCH v5 next 0/5] Improve Module autoloading infrastructure Linus Torvalds
2017-11-27 18:41 ` [kernel-hardening] " Linus Torvalds
2017-11-27 18:41 ` Linus Torvalds
2017-11-27 18:41 ` Linus Torvalds
2017-11-27 19:02 ` Linus Torvalds
2017-11-27 19:02 ` [kernel-hardening] " Linus Torvalds
2017-11-27 19:02 ` Linus Torvalds
2017-11-27 19:02 ` Linus Torvalds
2017-11-27 19:12 ` Linus Torvalds
2017-11-27 19:12 ` [kernel-hardening] " Linus Torvalds
2017-11-27 19:12 ` Linus Torvalds
2017-11-27 19:12 ` Linus Torvalds
2017-11-27 21:31 ` Djalal Harouni
2017-11-27 21:31 ` [kernel-hardening] " Djalal Harouni
2017-11-27 21:31 ` Djalal Harouni
2017-11-27 21:31 ` Djalal Harouni
2017-11-27 19:14 ` David Miller
2017-11-27 19:14 ` [kernel-hardening] " David Miller
2017-11-27 19:14 ` David Miller
2017-11-27 22:31 ` James Morris
2017-11-27 22:31 ` [kernel-hardening] " James Morris
2017-11-27 22:31 ` James Morris
2017-11-27 23:04 ` Kees Cook
2017-11-27 23:04 ` [kernel-hardening] " Kees Cook
2017-11-27 23:04 ` Kees Cook
2017-11-27 23:44 ` James Morris
2017-11-27 23:44 ` [kernel-hardening] " James Morris
2017-11-27 23:44 ` James Morris
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