From: Vivek Goyal <vgoyal@redhat.com>
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
James Morris <jmorris@namei.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL
Date: Thu, 21 Mar 2013 11:52:20 -0400 [thread overview]
Message-ID: <20130321155220.GL3934@redhat.com> (raw)
In-Reply-To: <20130321153725.GA3656@austin.hallyn.com>
On Thu, Mar 21, 2013 at 10:37:25AM -0500, Serge E. Hallyn wrote:
> Quoting Vivek Goyal (vgoyal@redhat.com):
> ...
> > Giving CAP_MODIFY_KERNEL to processess upon signature verification
> > will simplify things a bit.
> >
> > Only thing is that signature verification alone is not sufficient. We
> > also need to make sure after signature verification executable can
> > not be modified in memory in any way. So that means atleast couple of
> > things.
>
> Also what about context? If I construct a mounts namespace a certain
> way, can I trick this executable into loading an old singed bzImage that
> I had laying around?
We were thinking that /sbin/kexec will need to verify bzImage signature
before loading it.
Key for verification is in kernel so idea was to take kernel's help
in verifying signature.
Not sure how exactly the interface should look like.
- I was thinking may be process can mmap() the bzImage with MAP_LOCKED.
We can create additional flag say MAP_VERIFY_SIG_POST, which tries
to verify signature/integrity of mapped region of file after mapping and
locking pages and mmap() fails if signature verification fails.
There have been suggestions about creating new system call altogether.
>
> ISTM the only sane thing to do, if you're going down this road,
> is to have CAP_MODIFIY_KERNEL pulled from bounding set for everyone
> except a getty started by init on ttyS0. Then log in on serial
> to update. Or run a damon with CAP_MODIFIY_KERNEL which listens
> to a init_net_ns netlink socket for very basic instructions, like
> "find and install latest signed bzImage in /boot". Then you can
> at least trust that /boot for that daemon is not faked.
daemon does not have the key and can't verify signature of signed
bzImage. Even if it had the key, it can't trust the crypto code for
signature verification as none of that is signed.
Thanks
Vivek
next prev parent reply other threads:[~2013-03-21 15:52 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-18 21:32 [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL Matthew Garrett
2013-03-18 21:32 ` [PATCH 02/12] SELinux: define mapping for CAP_COMPROMISE_KERNEL Matthew Garrett
2013-03-18 21:32 ` [PATCH 03/12] Secure boot: Add a dummy kernel parameter that will switch on Secure Boot mode Matthew Garrett
2013-03-18 21:32 ` [PATCH 04/12] efi: Enable secure boot lockdown automatically when enabled in firmware Matthew Garrett
2013-03-18 21:32 ` [PATCH 05/12] PCI: Require CAP_COMPROMISE_KERNEL for PCI BAR access Matthew Garrett
2013-03-27 15:03 ` Josh Boyer
2013-03-27 15:08 ` Kyle McMartin
2013-03-28 12:46 ` Josh Boyer
2013-03-18 21:32 ` [PATCH 06/12] x86: Require CAP_COMPROMISE_KERNEL for IO port access Matthew Garrett
2013-03-20 1:00 ` H. Peter Anvin
2013-03-18 21:32 ` [PATCH 07/12] ACPI: Limit access to custom_method Matthew Garrett
2013-03-18 21:32 ` [PATCH 08/12] asus-wmi: Restrict debugfs interface Matthew Garrett
2013-03-18 21:32 ` [PATCH 09/12] Require CAP_COMPROMISE_KERNEL for /dev/mem and /dev/kmem access Matthew Garrett
2013-03-18 21:32 ` [PATCH 10/12] acpi: Ignore acpi_rsdp kernel parameter in a secure boot environment Matthew Garrett
2013-03-19 8:47 ` Dave Young
2013-03-19 11:19 ` Josh Boyer
2013-03-19 17:07 ` [PATCH v2] " Josh Boyer
2013-03-18 21:32 ` [PATCH 11/12] x86: Require CAP_COMPROMISE_KERNEL for MSR writing Matthew Garrett
2013-03-18 21:32 ` [PATCH 12/12] kexec: Require CAP_SYS_COMPROMISE_KERNEL Matthew Garrett
2013-03-19 4:47 ` [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL James Morris
2013-03-20 1:03 ` H. Peter Anvin
2013-03-20 16:41 ` Mimi Zohar
2013-03-20 16:49 ` Matthew Garrett
2013-03-20 18:01 ` Mimi Zohar
2013-03-20 18:12 ` Matthew Garrett
2013-03-20 19:16 ` Mimi Zohar
2013-03-20 20:37 ` Matthew Garrett
2013-03-20 21:11 ` Mimi Zohar
2013-03-20 21:18 ` Matthew Garrett
2013-03-21 13:43 ` Vivek Goyal
2013-03-21 15:37 ` Serge E. Hallyn
2013-03-21 15:52 ` Vivek Goyal [this message]
2013-03-21 15:58 ` Serge E. Hallyn
2013-03-21 16:04 ` Vivek Goyal
2013-03-21 16:19 ` Serge E. Hallyn
2013-03-21 17:15 ` Vivek Goyal
2013-03-21 1:58 ` James Morris
2013-03-19 7:18 ` Yves-Alexis Perez
2013-03-20 1:02 ` H. Peter Anvin
2013-03-20 1:05 ` H. Peter Anvin
2013-03-20 13:15 ` Matthew Garrett
2013-03-20 15:03 ` H. Peter Anvin
2013-03-20 15:14 ` Matthew Garrett
2013-03-20 16:45 ` H. Peter Anvin
-- strict thread matches above, loose matches on Subject: below --
2013-03-20 1:07 Matthew Garrett
2013-03-20 1:11 ` H. Peter Anvin
2013-03-20 1:09 Matthew Garrett
2013-03-20 1:28 Matthew Garrett
2013-03-20 2:48 ` H. Peter Anvin
2013-03-20 3:08 ` H. Peter Anvin
2013-03-20 3:18 ` Alex Williamson
2013-03-20 3:22 ` H. Peter Anvin
2013-03-20 3:27 ` Alex Williamson
2013-03-21 16:32 Matthew Garrett
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