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From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>,
	David Howells <dhowells@redhat.com>
Cc: torvalds@linux-foundation.org, linux-man@vger.kernel.org,
	linux-api@vger.kernel.org, jmorris@namei.org,
	linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org
Subject: Re: [PATCH 06/24] kexec_load: Disable at runtime if the kernel is locked down
Date: Wed, 11 Apr 2018 16:09:35 -0400	[thread overview]
Message-ID: <1523477375.5268.78.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <87po35k1q6.fsf@xmission.com>

On Wed, 2018-04-11 at 14:00 -0500, Eric W. Biederman wrote:
> David Howells <dhowells@redhat.com> writes:
> 
> > From: Matthew Garrett <mjg59@srcf.ucam.org>
> >
> > The kexec_load() syscall permits the loading and execution of arbitrary
> > code in ring 0, which is something that lock-down is meant to prevent. It
> > makes sense to disable kexec_load() in this situation.
> >
> > This does not affect kexec_file_load() syscall which can check for a
> > signature on the image to be booted.
> 
> Maybing I am missing it but I am not seeing anything that would require
> kexec_file_load be configured such that it checks the loaded kernel.
> 
> Without that I don't see the point of disabling kexec_load.
> 
> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>

The IMA "secure boot" policy requires the kexec image to be signed.
 This call to kernel_is_locked_down() could be replaced with a call
to security_kernel_read_file(NULL, READING_KEXEC_IMAGE).

It would be similar to the existing init_module syscall calling
security_kernel_read_file().

Mimi


  reply	other threads:[~2018-04-11 20:09 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-11 16:24 [PATCH 00/24] security: Add kernel lockdown David Howells
2018-04-11 16:24 ` [PATCH 01/24] Add the ability to lock down access to the running kernel image David Howells
2018-04-11 16:44   ` Jann Horn
2018-04-11 17:37   ` Randy Dunlap
2018-04-11 18:50     ` Miguel Ojeda
2018-04-11 19:56       ` Greg KH
2018-04-11 17:49   ` David Howells
2018-04-11 18:09   ` Linus Torvalds
2018-04-11 18:35     ` Justin Forbes
2018-04-11 21:05     ` Jordan Glover
2018-04-11 22:38       ` Linus Torvalds
2018-04-12 13:09         ` Justin Forbes
2018-04-12 16:52           ` Linus Torvalds
2018-04-12  2:57   ` Andy Lutomirski
2018-04-11 16:24 ` [PATCH 02/24] Add a SysRq option to lift kernel lockdown David Howells
2018-04-11 17:05   ` Jann Horn
2018-04-13 20:22   ` Pavel Machek
2018-04-11 16:24 ` [PATCH 03/24] ima: require secure_boot rules in lockdown mode David Howells
2018-04-11 16:25 ` [PATCH 04/24] Enforce module signatures if the kernel is locked down David Howells
2018-04-11 16:25 ` [PATCH 05/24] Restrict /dev/{mem, kmem, port} when " David Howells
2018-04-11 16:25 ` [PATCH 06/24] kexec_load: Disable at runtime if " David Howells
2018-04-11 19:00   ` Eric W. Biederman
2018-04-11 20:09     ` Mimi Zohar [this message]
2018-04-12 11:38       ` Mimi Zohar
2018-04-11 20:05   ` David Howells
2018-04-11 16:25 ` [PATCH 07/24] hibernate: Disable when " David Howells
2018-04-13 20:22   ` Pavel Machek
2018-04-19 14:38   ` David Howells
2018-04-22 14:34     ` Andy Lutomirski
2018-04-26  7:26     ` Pavel Machek
2018-04-26  7:34       ` Rafael J. Wysocki
2018-04-26  8:20       ` Jiri Kosina
2018-05-23  8:46         ` joeyli
2018-04-11 16:25 ` [PATCH 08/24] uswsusp: " David Howells
2018-04-11 16:25 ` [PATCH 09/24] PCI: Lock down BAR access " David Howells
2018-04-11 16:25 ` [PATCH 10/24] x86: Lock down IO port " David Howells
2018-04-11 16:25 ` [PATCH 11/24] x86/msr: Restrict MSR " David Howells
2018-04-11 16:25 ` [PATCH 12/24] ACPI: Limit access to custom_method " David Howells
2018-04-11 16:26 ` [PATCH 13/24] acpi: Ignore acpi_rsdp kernel param when the kernel has been " David Howells
2018-04-11 16:26 ` [PATCH 14/24] acpi: Disable ACPI table override if the kernel is " David Howells
2018-04-11 16:26 ` [PATCH 15/24] acpi: Disable APEI error injection " David Howells
2018-04-11 16:26 ` [PATCH 16/24] Prohibit PCMCIA CIS storage when " David Howells
2018-04-11 16:26 ` [PATCH 17/24] Lock down TIOCSSERIAL David Howells
2018-04-11 16:26 ` [PATCH 18/24] Lock down module params that specify hardware parameters (eg. ioport) David Howells
2018-04-11 17:22   ` Randy Dunlap
2018-04-11 16:26 ` [PATCH 19/24] x86/mmiotrace: Lock down the testmmiotrace module David Howells
2018-04-11 16:26 ` [PATCH 20/24] Lock down /proc/kcore David Howells
2018-04-11 16:26 ` [PATCH 21/24] Lock down kprobes David Howells
2018-04-11 16:27 ` [PATCH 22/24] bpf: Restrict kernel image access functions when the kernel is locked down David Howells
2018-04-11 16:27 ` [PATCH 23/24] Lock down perf David Howells
2018-04-11 16:27 ` [PATCH 24/24] debugfs: Restrict debugfs when the kernel is locked down David Howells
2018-04-11 17:26   ` Randy Dunlap
2018-04-11 18:50   ` Eric W. Biederman
2018-04-11 19:54   ` Greg KH
2018-04-11 20:08   ` David Howells
2018-04-11 20:09   ` David Howells
2018-04-11 20:33     ` Greg KH
2018-04-12  2:54       ` Andy Lutomirski
2018-04-12  8:23         ` Greg KH
2018-04-12 14:19           ` Andy Lutomirski
2018-04-13 20:22   ` Pavel Machek
2018-04-19 14:35   ` David Howells
2018-05-10 11:01     ` Pavel Machek

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