From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Thomas Garnier <thgarnie@google.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@suse.de>,
Andy Lutomirski <luto@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Dan Williams <dan.j.williams@intel.com>,
Kees Cook <keescook@chromium.org>,
Stephen Smalley <sds@tycho.nsa.gov>,
Seth Jennings <sjennings@variantweb.net>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Jonathan Corbet <corbet@lwn.net>,
Matt Fleming <matt@codeblueprint.co.uk>,
Toshi Kani <toshi.kani@hpe.com>,
Alexander Kuleshov <kuleshovmail@gmail.com>,
Alexander Popov <alpopov@ptsecurity.com>,
Joerg Roedel <jroedel@suse.de>, Dave Young <dyoung@redhat.com>,
Baoquan He <bhe@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Mark Salter <msalter@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, gthelen@google.com,
kernel-hardening@lists.openwall.com
Subject: [kernel-hardening] Re: [RFC v1 3/4] x86, boot: Implement ASLR for kernel memory sections (x86_64)
Date: Thu, 21 Apr 2016 09:30:24 -0400 [thread overview]
Message-ID: <5718D5F0.8010501@oracle.com> (raw)
In-Reply-To: <1460757793-59020-4-git-send-email-thgarnie@google.com>
On 04/15/2016 06:03 PM, Thomas Garnier wrote:
> +void __init kernel_randomize_memory(void)
> +{
> + size_t i;
> + unsigned long addr = memory_rand_start;
> + unsigned long padding, rand, mem_tb;
> + struct rnd_state rnd_st;
> + unsigned long remain_padding = memory_rand_end - memory_rand_start;
> +
> + if (!kaslr_enabled())
> + return;
> +
> + /* Take the additional space when Xen is not active. */
> + if (!xen_domain())
> + page_offset_base -= __XEN_SPACE;
This should be !xen_pv_domain(). Xen HVM guests are no different from
bare metal as far as address ranges are concerned. (Technically it's
probably !xen_pv_domain() && !xen_pvh_domain() but we can ignore PVH for
now since it is being replaced by an HVM-type guest)
Having said that, I am not sure I understand why page_offset_base is
shifted. I thought 0xffff800000000000 - 0xffff87ffffffffff is not
supposed to be used by anyone, whether we are running under a hypervisor
or not.
-boris
WARNING: multiple messages have this Message-ID (diff)
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Thomas Garnier <thgarnie@google.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@suse.de>,
Andy Lutomirski <luto@kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Dan Williams <dan.j.williams@intel.com>,
Kees Cook <keescook@chromium.org>,
Stephen Smalley <sds@tycho.nsa.gov>,
Seth Jennings <sjennings@variantweb.net>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Jonathan Corbet <corbet@lwn.net>,
Matt Fleming <matt@codeblueprint.co.uk>,
Toshi Kani <toshi.kani@hpe.com>,
Alexander Kuleshov <kuleshovmail@gmail.com>,
Alexander Popov <alpopov@ptsecurity.com>,
Joerg Roedel <jroedel@suse.de>, Dave Young <dyoung@redhat.com>,
Baoquan He <bhe@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Mark Salter <msalter@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, gthelen@google.com,
kernel-hardening@lists.openwall.com
Subject: Re: [RFC v1 3/4] x86, boot: Implement ASLR for kernel memory sections (x86_64)
Date: Thu, 21 Apr 2016 09:30:24 -0400 [thread overview]
Message-ID: <5718D5F0.8010501@oracle.com> (raw)
In-Reply-To: <1460757793-59020-4-git-send-email-thgarnie@google.com>
On 04/15/2016 06:03 PM, Thomas Garnier wrote:
> +void __init kernel_randomize_memory(void)
> +{
> + size_t i;
> + unsigned long addr = memory_rand_start;
> + unsigned long padding, rand, mem_tb;
> + struct rnd_state rnd_st;
> + unsigned long remain_padding = memory_rand_end - memory_rand_start;
> +
> + if (!kaslr_enabled())
> + return;
> +
> + /* Take the additional space when Xen is not active. */
> + if (!xen_domain())
> + page_offset_base -= __XEN_SPACE;
This should be !xen_pv_domain(). Xen HVM guests are no different from
bare metal as far as address ranges are concerned. (Technically it's
probably !xen_pv_domain() && !xen_pvh_domain() but we can ignore PVH for
now since it is being replaced by an HVM-type guest)
Having said that, I am not sure I understand why page_offset_base is
shifted. I thought 0xffff800000000000 - 0xffff87ffffffffff is not
supposed to be used by anyone, whether we are running under a hypervisor
or not.
-boris
next prev parent reply other threads:[~2016-04-21 13:30 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-15 22:03 [kernel-hardening] [RFC v1 0/4] x86, boot: KASLR memory implementation (x86_64) Thomas Garnier
2016-04-15 22:03 ` Thomas Garnier
2016-04-15 22:03 ` [kernel-hardening] [RFC v1 1/4] x86, boot: Refactor KASLR entropy functions Thomas Garnier
2016-04-15 22:03 ` Thomas Garnier
2016-04-15 22:03 ` [kernel-hardening] [RFC v1 2/4] x86, boot: PUD VA support for physical mapping (x86_64) Thomas Garnier
2016-04-15 22:03 ` Thomas Garnier
2016-04-15 22:03 ` [kernel-hardening] [RFC v1 3/4] x86, boot: Implement ASLR for kernel memory sections (x86_64) Thomas Garnier
2016-04-15 22:03 ` Thomas Garnier
2016-04-18 14:46 ` [kernel-hardening] " Joerg Roedel
2016-04-18 14:46 ` Joerg Roedel
2016-04-18 14:56 ` [kernel-hardening] " Thomas Garnier
2016-04-18 14:56 ` Thomas Garnier
2016-04-18 19:01 ` [kernel-hardening] " H. Peter Anvin
2016-04-18 19:01 ` H. Peter Anvin
2016-04-19 14:27 ` [kernel-hardening] " Joerg Roedel
2016-04-19 14:27 ` Joerg Roedel
2016-04-19 15:49 ` [kernel-hardening] " Thomas Garnier
2016-04-19 15:49 ` Thomas Garnier
2016-04-21 13:30 ` Boris Ostrovsky [this message]
2016-04-21 13:30 ` Boris Ostrovsky
2016-04-21 15:11 ` [kernel-hardening] " Thomas Garnier
2016-04-21 15:11 ` Thomas Garnier
2016-04-21 15:46 ` [kernel-hardening] " H. Peter Anvin
2016-04-21 15:46 ` H. Peter Anvin
2016-04-21 15:52 ` [kernel-hardening] " Thomas Garnier
2016-04-21 15:52 ` Thomas Garnier
2016-04-21 20:15 ` [kernel-hardening] " H. Peter Anvin
2016-04-21 20:15 ` H. Peter Anvin
2016-04-21 20:18 ` [kernel-hardening] " Thomas Garnier
2016-04-21 20:18 ` Thomas Garnier
2016-06-17 9:07 ` [kernel-hardening] " Ingo Molnar
2016-06-17 9:07 ` Ingo Molnar
2016-06-17 9:35 ` [kernel-hardening] " Ingo Molnar
2016-06-17 9:35 ` Ingo Molnar
2016-06-17 9:40 ` [kernel-hardening] " Ingo Molnar
2016-06-17 9:40 ` Ingo Molnar
2016-04-15 22:03 ` [kernel-hardening] [RFC v1 4/4] x86, boot: Memory hotplug support for KASLR memory randomization Thomas Garnier
2016-04-15 22:03 ` Thomas Garnier
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