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From: Matthew Garrett <mjg59@google.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: James Morris <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] Kernel lockdown patches for 5.2
Date: Mon, 11 Mar 2019 17:42:38 -0700
Message-ID: <CACdnJuszfo4gTUD88p+8jeHU5e3hSdp+GEr8_=F1AMThPb7yWg@mail.gmail.com> (raw)
In-Reply-To: <CACdnJuuib7kYEw1o0Bh1p=X+MmJH+pqupECWnWTJ2e2jE2XRkg@mail.gmail.com>

On Wed, Mar 6, 2019 at 8:24 PM Matthew Garrett <mjg59@google.com> wrote:
>
> On Wed, Mar 6, 2019 at 7:56 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > The kexec and kernel modules patches in this patch set continues to
> > ignore IMA.  This patch set should up front either provide an
> > alternative solution to coordinate the different signature
> > verification methods or rely on the architecture specific policy for
> > that coordination.
>
> Hi Mimi,
>
> I'm working on a patch for this at the moment which can then be added
> to either patchset. Is there a tree that contains the proposed Power
> architecture policy? I want to make sure I don't accidentally end up
> depending on anything x86.

I've been digging into this some more, and want to ensure that I get
the appropriate semantics. Are we happy with the x86 solution for
module signing (ie, if the arch policy is enabled and the kernel
supports module signatures, use module signatures rather than IMA
signatures)? If so, that just leaves kexec. For platforms that support
PE signing for kernels (x86 and arm), are we ok punting to that? If so
then to maintain the semantics we have for lockdown in general (ie, no
way for a user to modify ring 0 code) then I think that would mean
allowing kexec_file() only when the following criteria are met:

1) IMA is appraising kexec with digital signatures, either ima digital
signatures or ima hashes with associated EVM digital signatures
2) CONFIG_INTEGRITY_TRUSTED_KEYRING is set in order to prevent an
attacker being able to add a key to the keyring

Does this sound reasonable? Are there any further criteria that are
required for this?

  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-06 23:58 Matthew Garrett
2019-03-06 23:58 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-03-06 23:58 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-03-07  0:09   ` Randy Dunlap
2019-03-07  0:12     ` Matthew Garrett
2019-03-06 23:58 ` [PATCH 03/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-03-08 23:00   ` James Morris
2019-03-08 23:30     ` Matthew Garrett
2019-03-09  4:45       ` James Morris
2019-03-06 23:58 ` [PATCH 04/27] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-03-06 23:58 ` [PATCH 05/27] kexec_load: Disable at runtime if " Matthew Garrett
2019-03-06 23:58 ` [PATCH 06/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-03-06 23:58 ` [PATCH 07/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-03-06 23:58 ` [PATCH 08/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-03-06 23:58 ` [PATCH 09/27] hibernate: Disable when " Matthew Garrett
2019-03-07 14:55   ` Alan Cox
2019-03-07 17:32     ` Matthew Garrett
2019-03-18 18:55       ` Alan Cox
2019-03-06 23:58 ` [PATCH 10/27] uswsusp: " Matthew Garrett
2019-03-06 23:58 ` [PATCH 11/27] PCI: Lock down BAR access " Matthew Garrett
2019-03-06 23:58 ` [PATCH 12/27] x86: Lock down IO port " Matthew Garrett
2019-03-06 23:58 ` [PATCH 13/27] x86/msr: Restrict MSR " Matthew Garrett
2019-03-06 23:59 ` [PATCH 14/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-03-06 23:59 ` [PATCH 15/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-03-06 23:59 ` [PATCH 16/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-03-06 23:59 ` [PATCH 17/27] acpi: Disable APEI error injection " Matthew Garrett
2019-03-06 23:59 ` [PATCH 18/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-03-06 23:59 ` [PATCH 19/27] Lock down TIOCSSERIAL Matthew Garrett
2019-03-06 23:59 ` [PATCH 20/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-03-06 23:59 ` [PATCH 21/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-03-06 23:59 ` [PATCH 22/27] Lock down /proc/kcore Matthew Garrett
2019-03-06 23:59 ` [PATCH 23/27] Lock down kprobes Matthew Garrett
2019-03-06 23:59 ` [PATCH 24/27] bpf: Restrict kernel image access functions when the kernel is locked down Matthew Garrett
2019-03-06 23:59 ` [PATCH 25/27] Lock down perf Matthew Garrett
2019-03-06 23:59 ` [PATCH 26/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-04-25 10:49   ` Vasily Gorbik
2019-04-25 21:44     ` Matthew Garrett
2019-03-06 23:59 ` [PATCH 27/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-03-07  3:56 ` [PULL REQUEST] Kernel lockdown patches for 5.2 Mimi Zohar
2019-03-07  4:24   ` Matthew Garrett
2019-03-12  0:42     ` Matthew Garrett [this message]
2019-03-12  1:52       ` Mimi Zohar
2019-03-07 15:59 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown David Howells

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