[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Sat, 21 Oct 2017 00:40:25 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Kees Cook <keescook@...omium.org>, kernel-hardening@...ts.openwall.com
Cc: David Windsor <dave@...lcore.net>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 00/23] Hardened usercopy whitelisting
On 20/06/2017 01:36, Kees Cook wrote:
>
> This updates the slab allocator to add annotations (useroffset and
> usersize) to define allowed usercopy regions. Currently, hardened
> usercopy performs dynamic bounds checking on whole slab cache objects.
> This is good, but still leaves a lot of kernel slab memory available to
> be copied to/from userspace in the face of bugs. To further restrict
> what memory is available for copying, this creates a way to whitelist
> specific areas of a given slab cache object for copying to/from userspace,
> allowing much finer granularity of access control. Slab caches that are
> never exposed to userspace can declare no whitelist for their objects,
> thereby keeping them unavailable to userspace via dynamic copy operations.
> (Note, an implicit form of whitelisting is the use of constant sizes
> in usercopy operations and get_user()/put_user(); these bypass hardened
> usercopy checks since these sizes cannot change at runtime.)
This breaks KVM completely on x86, due to two ioctls
(KVM_GET/SET_CPUID2) accessing the cpuid_entries field of struct
kvm_vcpu_arch.
There's also another broken ioctl, KVM_XEN_HVM_CONFIG, but it is
obsolete and not a big deal at all.
I can post some patches, but probably not until the beginning of
November due to travelling. Please do not send this too close to the
beginning of the merge window.
Paolo
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
