From: Andy Lutomirski <luto@kernel.org>
To: James Morris <jmorris@namei.org>
Cc: Andy Lutomirski <luto@kernel.org>,
Stephen Hemminger <stephen@networkplumber.org>,
Linux API <linux-api@vger.kernel.org>,
Matthew Garrett <matthewgarrett@google.com>,
LSM List <linux-security-module@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Network Development <netdev@vger.kernel.org>,
Chun-Yi Lee <jlee@suse.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kees Cook <keescook@chromium.org>, Will Drewry <wad@chromium.org>
Subject: Re: [PATCH 23/27] bpf: Restrict kernel image access functions when the kernel is locked down
Date: Tue, 26 Mar 2019 12:22:17 -0700 [thread overview]
Message-ID: <CALCETrUZ+oP0xxNt4mwN=AZA+zvkkfPZiAsFmAuqUD48pOHbBg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LRH.2.21.1903270523240.5235@namei.org>
On Tue, Mar 26, 2019 at 11:57 AM James Morris <jmorris@namei.org> wrote:
>
> On Mon, 25 Mar 2019, Andy Lutomirski wrote:
>
> > A while back, I suggested an approach to actually make this stuff
> > mergeable: submit a patch series that adds lockdown mode, enables it
> > by command line option (and maybe sysctl) *only* and has either no
> > effect or only a token effect. Then we can add actual features to
> > lockdown mode one at a time and review them separately.
>
> This makes sense to me.
>
> >
> > And I'm going to complain loudly unless two things change about this
> > whole thing:
> >
> > 1. Lockdown mode becomes three states, not a boolean. The states are:
> > no lockdown, best-effort-to-protect-kernel-integrity, and
> > best-effort-to-protect-kernel-secrecy-and-integrity. And this BPF
> > mess illustrates why: most users will really strongly object to
> > turning off BPF when they actually just want to protect kernel
> > integrity. And as far as I know, things like Secure Boot policy will
> > mostly care about integrity, not secrecy, and tracing and such should
> > work on a normal locked-down kernel. So I think we need this knob.
>
> Another approach would be to make this entirely policy based:
>
> - Assign an ID to each lockdown point
> - Implement a policy mechanism where each ID is mapped to 0 or 1
> - Allow this policy to be specified statically or dynamically
>
> So,
>
> kernel_is_locked_down("ioperm")
>
> becomes
>
> kernel_is_locked_down(LOCKDOWN_IOPERM)
>
> and this function checks e.g.
>
> if (lockdown_polcy[id]) {
> fail or warn;
> }
>
> Thoughts?
I'm concerned that this gives too much useless flexibility to
administrators and user code in general. If you can break kernel
integrity, you can break kernel integrity -- it shouldn't really
matter *how* you break it.
--Andy
next prev parent reply other threads:[~2019-03-26 19:22 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 22:09 [PULL REQUEST] Lockdown patches for 5.2 Matthew Garrett
2019-03-25 22:09 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-03-26 5:30 ` Matthew Garrett
2019-03-25 22:09 ` [PATCH 02/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-03-25 22:09 ` [PATCH 03/27] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-03-25 22:09 ` [PATCH 04/27] kexec_load: Disable at runtime if " Matthew Garrett
2019-03-25 22:09 ` [PATCH 05/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-03-25 22:09 ` [PATCH 06/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-03-25 22:09 ` [PATCH 07/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-03-25 22:09 ` [PATCH 08/27] hibernate: Disable when " Matthew Garrett
2019-03-25 22:09 ` [PATCH 09/27] uswsusp: " Matthew Garrett
2019-03-25 22:09 ` [PATCH 10/27] PCI: Lock down BAR access " Matthew Garrett
2019-03-25 22:09 ` [PATCH 11/27] x86: Lock down IO port " Matthew Garrett
2019-03-25 22:09 ` [PATCH 12/27] x86/msr: Restrict MSR " Matthew Garrett
2019-03-25 23:40 ` Thomas Gleixner
2019-03-25 22:09 ` [PATCH 13/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-03-25 22:09 ` [PATCH 14/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-03-25 22:09 ` [PATCH 15/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-03-25 22:09 ` [PATCH 16/27] acpi: Disable APEI error injection " Matthew Garrett
2019-03-25 22:09 ` [PATCH 17/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-03-25 22:09 ` [PATCH 18/27] Lock down TIOCSSERIAL Matthew Garrett
2019-03-25 22:09 ` [PATCH 19/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-03-25 22:09 ` [PATCH 20/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-03-25 23:35 ` Steven Rostedt
2019-03-25 22:09 ` [PATCH 21/27] Lock down /proc/kcore Matthew Garrett
2019-03-25 22:09 ` [PATCH 22/27] Lock down kprobes Matthew Garrett
2019-03-26 12:29 ` Masami Hiramatsu
2019-03-26 17:41 ` Matthew Garrett
2019-03-26 22:47 ` Masami Hiramatsu
2019-03-25 22:09 ` [PATCH 23/27] bpf: Restrict kernel image access functions when the kernel is locked down Matthew Garrett
2019-03-25 23:42 ` Stephen Hemminger
2019-03-25 23:59 ` Stephen Hemminger
2019-03-26 0:00 ` Daniel Borkmann
2019-03-26 13:54 ` Jordan Glover
2019-03-26 0:10 ` Andy Lutomirski
2019-03-26 18:57 ` James Morris
2019-03-26 19:22 ` Andy Lutomirski [this message]
2019-03-28 3:15 ` James Morris
2019-03-28 18:07 ` Matthew Garrett
2019-03-28 19:23 ` James Morris
2019-03-28 20:08 ` Matthew Garrett
2019-03-26 20:19 ` Matthew Garrett
2019-03-25 22:09 ` [PATCH 24/27] Lock down perf Matthew Garrett
2019-03-25 22:09 ` [PATCH 25/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-03-26 0:31 ` Greg Kroah-Hartman
2019-03-26 0:38 ` Matthew Garrett
2019-03-26 0:43 ` Greg Kroah-Hartman
2019-03-25 22:09 ` [PATCH 26/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-03-25 22:09 ` [PATCH 27/27] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-03-26 15:33 ` Mimi Zohar
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