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From: Jiri Olsa <jolsa@redhat.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Paul Moore <paul@paul-moore.com>,
	Ondrej Mosnacek <omosnace@redhat.com>,
	linux-security-module@vger.kernel.org,
	James Morris <jmorris@namei.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	selinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Casey Schaufler <casey@schaufler-ca.com>,
	andrii.nakryiko@gmail.com
Subject: Re: [PATCH v2] lockdown,selinux: avoid bogus SELinux lockdown permission checks
Date: Fri, 28 May 2021 12:16:11 +0200	[thread overview]
Message-ID: <YLDC6zQUtoITdX4s@krava> (raw)
In-Reply-To: <4fee8c12-194f-3f85-e28b-f7f24ab03c91@iogearbox.net>

On Fri, May 28, 2021 at 11:56:02AM +0200, Daniel Borkmann wrote:

SNIP

> 
> Ondrej / Paul / Jiri: at least for the BPF tracing case specifically (I haven't looked
> at the rest but it's also kind of independent), the attached fix should address both
> reported issues, please take a look & test.
> 
> Thanks a lot,
> Daniel

> From 5893ad528dc0a0a68933b8f2a81b18d3f539660d Mon Sep 17 00:00:00 2001
> From: Daniel Borkmann <daniel@iogearbox.net>
> Date: Fri, 28 May 2021 09:16:31 +0000
> Subject: [PATCH bpf] bpf, audit, lockdown: Fix bogus SELinux lockdown permission checks
> 
> Commit 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown")
> added an implementation of the locked_down LSM hook to SELinux, with the aim
> to restrict which domains are allowed to perform operations that would breach
> lockdown. This is indirectly also getting audit subsystem involved to report
> events. The latter is problematic, as reported by Ondrej and Serhei, since it
> can bring down the whole system via audit:
> 
>   i) The audit events that are triggered due to calls to security_locked_down()
>      can OOM kill a machine, see below details [0].
> 
>  ii) It seems to be causing a deadlock via slow_avc_audit() -> audit_log_end()
>      when presumingly trying to wake up kauditd [1].
> 
> Fix both at the same time by taking a completely different approach, that is,
> move the check into the program verification phase where we actually retrieve
> the func proto. This also reliably gets the task (current) that is trying to
> install the tracing program, e.g. bpftrace/bcc/perf/systemtap/etc, and it also
> fixes the OOM since we're moving this out of the BPF helpers which can be called
> millions of times per second.

nice idea.. I'll try to reproduce and test

jirka


WARNING: multiple messages have this Message-ID (diff)
From: Jiri Olsa <jolsa@redhat.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Paul Moore <paul@paul-moore.com>,
	selinux@vger.kernel.org, netdev@vger.kernel.org,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	James Morris <jmorris@namei.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ondrej Mosnacek <omosnace@redhat.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	linux-security-module@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>,
	linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org,
	andrii.nakryiko@gmail.com, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] lockdown,selinux: avoid bogus SELinux lockdown permission checks
Date: Fri, 28 May 2021 12:16:11 +0200	[thread overview]
Message-ID: <YLDC6zQUtoITdX4s@krava> (raw)
In-Reply-To: <4fee8c12-194f-3f85-e28b-f7f24ab03c91@iogearbox.net>

On Fri, May 28, 2021 at 11:56:02AM +0200, Daniel Borkmann wrote:

SNIP

> 
> Ondrej / Paul / Jiri: at least for the BPF tracing case specifically (I haven't looked
> at the rest but it's also kind of independent), the attached fix should address both
> reported issues, please take a look & test.
> 
> Thanks a lot,
> Daniel

> From 5893ad528dc0a0a68933b8f2a81b18d3f539660d Mon Sep 17 00:00:00 2001
> From: Daniel Borkmann <daniel@iogearbox.net>
> Date: Fri, 28 May 2021 09:16:31 +0000
> Subject: [PATCH bpf] bpf, audit, lockdown: Fix bogus SELinux lockdown permission checks
> 
> Commit 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown")
> added an implementation of the locked_down LSM hook to SELinux, with the aim
> to restrict which domains are allowed to perform operations that would breach
> lockdown. This is indirectly also getting audit subsystem involved to report
> events. The latter is problematic, as reported by Ondrej and Serhei, since it
> can bring down the whole system via audit:
> 
>   i) The audit events that are triggered due to calls to security_locked_down()
>      can OOM kill a machine, see below details [0].
> 
>  ii) It seems to be causing a deadlock via slow_avc_audit() -> audit_log_end()
>      when presumingly trying to wake up kauditd [1].
> 
> Fix both at the same time by taking a completely different approach, that is,
> move the check into the program verification phase where we actually retrieve
> the func proto. This also reliably gets the task (current) that is trying to
> install the tracing program, e.g. bpftrace/bcc/perf/systemtap/etc, and it also
> fixes the OOM since we're moving this out of the BPF helpers which can be called
> millions of times per second.

nice idea.. I'll try to reproduce and test

jirka


  reply	other threads:[~2021-05-28 10:16 UTC|newest]

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-17  9:20 [PATCH v2] lockdown,selinux: avoid bogus SELinux lockdown permission checks Ondrej Mosnacek
2021-05-17  9:20 ` [PATCH v2] lockdown, selinux: " Ondrej Mosnacek
2021-05-17 11:00 ` [PATCH v2] lockdown,selinux: " Michael Ellerman
2021-05-17 11:00   ` Michael Ellerman
2021-05-26 11:44   ` Ondrej Mosnacek
2021-05-26 11:44     ` Ondrej Mosnacek
2021-05-27  4:28     ` James Morris
2021-05-27  4:28       ` James Morris
2021-05-27 14:18       ` Paul Moore
2021-05-27 14:18         ` Paul Moore
2021-05-28  1:37 ` Paul Moore
2021-05-28  1:37   ` Paul Moore
2021-05-28  7:09   ` Daniel Borkmann
2021-05-28  7:09     ` Daniel Borkmann
2021-05-28  9:53     ` Jiri Olsa
2021-05-28  9:53       ` Jiri Olsa
2021-05-28  9:56     ` Daniel Borkmann
2021-05-28  9:56       ` Daniel Borkmann
2021-05-28 10:16       ` Jiri Olsa [this message]
2021-05-28 10:16         ` Jiri Olsa
2021-05-28 11:47       ` Jiri Olsa
2021-05-28 11:47         ` Jiri Olsa
2021-05-28 11:54         ` Daniel Borkmann
2021-05-28 11:54           ` Daniel Borkmann
2021-05-28 13:42       ` Ondrej Mosnacek
2021-05-28 13:42         ` Ondrej Mosnacek
2021-05-28 14:20         ` Daniel Borkmann
2021-05-28 14:20           ` Daniel Borkmann
2021-05-28 15:54           ` Paul Moore
2021-05-28 15:54             ` Paul Moore
2021-05-28 15:47     ` Paul Moore
2021-05-28 15:47       ` Paul Moore
2021-05-28 18:10       ` Daniel Borkmann
2021-05-28 18:10         ` Daniel Borkmann
2021-05-28 22:52         ` Paul Moore
2021-05-28 22:52           ` Paul Moore
2021-05-29 18:48         ` Paul Moore
2021-05-29 18:48           ` Paul Moore
2021-05-31  8:24           ` Daniel Borkmann
2021-05-31  8:24             ` Daniel Borkmann
2021-06-01 20:47             ` Paul Moore
2021-06-01 20:47               ` Paul Moore
2021-06-02 12:40               ` Daniel Borkmann
2021-06-02 12:40                 ` Daniel Borkmann
2021-06-02 15:13                 ` Paul Moore
2021-06-02 15:13                   ` Paul Moore
2021-06-03 18:52                   ` Daniel Borkmann
2021-06-03 18:52                     ` Daniel Borkmann
2021-06-04  4:50                     ` Paul Moore
2021-06-04  4:50                       ` Paul Moore
2021-06-04 18:02                       ` Daniel Borkmann
2021-06-04 18:02                         ` Daniel Borkmann
2021-06-04 23:34                         ` Paul Moore
2021-06-04 23:34                           ` Paul Moore
2021-06-05  0:08                           ` Alexei Starovoitov
2021-06-05  0:08                             ` Alexei Starovoitov
2021-06-05 18:10                             ` Casey Schaufler
2021-06-05 18:10                               ` Casey Schaufler
2021-06-05 18:17                               ` Linus Torvalds
2021-06-05 18:17                                 ` Linus Torvalds
2021-06-06  2:11                                 ` Paul Moore
2021-06-06  2:11                                   ` Paul Moore
2021-06-06  1:30                             ` Paul Moore
2021-06-06  1:30                               ` Paul Moore
2021-06-02 13:39   ` Ondrej Mosnacek
2021-06-02 13:39     ` Ondrej Mosnacek
2021-06-03 17:46     ` Paul Moore
2021-06-03 17:46       ` Paul Moore
2021-06-08 11:01       ` Ondrej Mosnacek
2021-06-08 11:01         ` Ondrej Mosnacek
2021-06-09  2:40         ` Paul Moore
2021-06-09  2:40           ` Paul Moore
2021-05-28 13:58 ` Steven Rostedt
2021-05-28 13:58   ` Steven Rostedt

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