From: Matthew Garrett <mjg59@google.com>
To: Mimi Zohar <zohar@linux.ibm.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 17:01:59 -0800 [thread overview]
Message-ID: <CACdnJutqg26pk5xnK2ii3ia9JabAnBptE3YQ3yLvVT93as666Q@mail.gmail.com> (raw)
In-Reply-To: <1551398720.10911.270.camel@linux.ibm.com>
On Thu, Feb 28, 2019 at 4:05 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
>
> On Thu, 2019-02-28 at 15:13 -0800, Matthew Garrett wrote:
> > On Thu, Feb 28, 2019 at 2:20 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > > Where/when was this latest version of the patches posted?
> >
> > They should have followed this, but git-send-email choked on some
> > reviewed-by: lines so I'm just trying to sort that out.
>
> I'm a little perplexed as to why you would send a pull request, before
> re-posting the patches with the changes for review.
They should be there now. There's no substantive change to the
patches, other than having dropped a few from the series.
> > It's a little more complicated than this. We can't just rely on IMA
> > appraisal - it has to be based on digital signatures, and the existing
> > patch only made that implicit by enabling the secure_boot policy.
>
> Right, which is the reason the IMA architecture specific policy
> requires file signatures. [1][2]
The current patches seem to require ima signatures - shouldn't this
allow ima digests as long as there's an evm signature?
> > I
> > think we do want to integrate these, but there's a few things we need
> > to take into account:
> >
> > 1) An integrated solution can't depend on xattrs, both because of the
> > lagging support for distributing those signatures but also because we
> > need to support filesystems that don't support xattrs
>
> 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.
> > 2) An integrated solution can't depend on the current secure_boot
> > policy because that requires signed IMA policy updates, but
> > distributions have no way of knowing what IMA policy end users require
>
> Both the "CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS" and the IMA
> architecture policy rules persist after loading a custom policy.
> Neither of them require loading or signing a custom policy.
The previous version of the lockdown patchset sets the secure_boot
policy when lockdown is enabled, which does require that any custom
policy be signed.
> > In any case, I do agree that we should aim to make this more
> > reasonable - having orthogonal signing code doesn't benefit anyone.
> > Once there's solid agreement on that we can extend this support.
> >
>
> Having multiple signature verification methods is going to be around
> for a while. The solution is to coordinate the signature verification
> methods, without requiring both types of signatures. [1][2]
Agree, and once we have a solution to this we should integrate that
with lockdown. I don't think merging this first makes that any harder.
Importantly, this version of the patchset doesn't enable lockdown
automatically unless explicitly configured to do so, which means you
can build a lockdown kernel without interfering with IMA.
next prev parent reply other threads:[~2019-03-01 1:02 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 21:28 [PULL REQUEST] Lock down patches 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 [this message]
2019-03-01 1:44 ` Mimi Zohar
2019-03-01 3:33 ` Matthew Garrett
2019-03-01 4:16 ` Mimi Zohar
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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