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From: Mimi Zohar <zohar@linux.ibm.com>
To: Matthew Garrett <mjg59@google.com>
Cc: jmorris@namei.org,
	LSM List <linux-security-module@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	David Howells <dhowells@redhat.com>
Subject: Re: [PULL REQUEST] Lock down patches
Date: Thu, 28 Feb 2019 23:16:14 -0500
Message-ID: <1551413774.10911.308.camel@linux.ibm.com> (raw)
In-Reply-To: <CACdnJuvn4uC075+Z99CaO3YGjJ+4nviPj=4TEQpkndC3JwFovg@mail.gmail.com>

On Thu, 2019-02-28 at 19:33 -0800, Matthew Garrett wrote:
> On Thu, Feb 28, 2019 at 5:45 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> >
> > On Thu, 2019-02-28 at 17:01 -0800, Matthew Garrett wrote:
> >
> > > > That's not a valid reason for preventing systems that do use IMA for
> > > > verifying the kexec kernel image signature or kernel module signatures
> > > > from enabling "lock down".  This just means that there needs to be
> > > > some coordination between the different signature verification
> > > > methods. [1][2]
> > >
> > > I agree, but the current form of the integration makes it impossible
> > > for anyone using an IMA-enabled kernel (but not using IMA) to do
> > > anything unless they have IMA signatures. It's a problem we need to
> > > solve, I just don't think it's a problem we need to solve before
> > > merging the patchset.
> >
> > That's simply not true.  Have you even looked at the IMA architecture
> > patches?
> 
> Sorry, I think we're talking at cross purposes - I was referring to
> your patch "ima: require secure_boot rules in lockdown mode"
> (https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?h=efi-lock-down&id=7fa3734bd31a4b3fe71358fcba8d4878e5005b7f).

With the "secure_boot" rules it was difficult to coordinate the
different signature verification methods.  Plus they weren't
persistent after loading a custom policy.

> If the goal is just to use the architecture rules then I don't see any
> conflict, 

yes

> and as far as I can tell things would just work as is if I
> drop the ima portion from "kexec_file: Restrict at runtime if the
> kernel is locked down"?

That code is a remnant left over from when the "secure_boot" policy
was enabled.  However, dropping the IMA portion there would result in
allowing only PE signed kernel images.  (On Power, for example, there
aren't any PE signatures.)

My suggestion would be to drop this patch and require the architecture
specific policy in "lock down" mode.

>  Apologies, I'd thought that the secure_boot
> ruleset was still intended to be used in a lockdown environment.

No, not any longer.

Mimi


  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-28 21:28 Matthew Garrett
2019-02-28 22:20 ` Mimi Zohar
2019-02-28 23:13   ` Matthew Garrett
2019-03-01  0:05     ` Mimi Zohar
2019-03-01  1:01       ` Matthew Garrett
2019-03-01  1:44         ` Mimi Zohar
2019-03-01  3:33           ` Matthew Garrett
2019-03-01  4:16             ` Mimi Zohar [this message]
2019-02-28 22:44 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 22:44   ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:10 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:10   ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:11   ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:11   ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11   ` [PATCH 03/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-02-28 23:11   ` [PATCH 04/27] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-02-28 23:11   ` [PATCH 05/27] kexec_load: Disable at runtime if " Matthew Garrett
2019-02-28 23:11   ` [PATCH 06/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-02-28 23:11   ` [PATCH 07/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-02-28 23:11   ` [PATCH 08/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-03-01  2:05     ` Mimi Zohar
2019-02-28 23:11   ` [PATCH 09/27] hibernate: Disable when " Matthew Garrett
2019-03-19 22:15     ` Pavel Machek
2019-02-28 23:11   ` [PATCH 10/27] uswsusp: " Matthew Garrett
2019-02-28 23:11   ` [PATCH 11/27] PCI: Lock down BAR access " Matthew Garrett
2019-02-28 23:11   ` [PATCH 12/27] x86: Lock down IO port " Matthew Garrett
2019-02-28 23:11   ` [PATCH 13/27] x86/msr: Restrict MSR " Matthew Garrett
2019-02-28 23:11   ` [PATCH 14/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-02-28 23:11   ` [PATCH 15/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-02-28 23:11   ` [PATCH 16/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-02-28 23:11   ` [PATCH 17/27] acpi: Disable APEI error injection " Matthew Garrett
2019-02-28 23:11   ` [PATCH 18/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-02-28 23:11   ` [PATCH 19/27] Lock down TIOCSSERIAL Matthew Garrett
2019-02-28 23:11   ` [PATCH 20/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-02-28 23:11   ` [PATCH 21/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-02-28 23:11   ` [PATCH 22/27] Lock down /proc/kcore Matthew Garrett
2019-02-28 23:11   ` [PATCH 23/27] Lock down kprobes Matthew Garrett
2019-02-28 23:12   ` [PATCH 24/27] bpf: Restrict kernel image access functions when the kernel is locked down Matthew Garrett
2019-02-28 23:12   ` [PATCH 25/27] Lock down perf Matthew Garrett
2019-02-28 23:12   ` [PATCH 26/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-02-28 23:12   ` [PATCH 27/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-02-28 23:24 ` [PULL REQUEST] Lock down patches Randy Dunlap
2019-03-04 22:10 ` Matthew Garrett

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