From: "H. Peter Anvin" <hpa@zytor.com>
To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Dave Anderson <anderson@redhat.com>,
Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, kernel-hardening@lists.openwall.com,
Aaron Durbin <adurbin@google.com>,
Eric Northup <digitaleric@google.com>,
Julien Tinnes <jln@google.com>, Will Drewry <wad@google.com>,
Mathias Krause <minipli@googlemail.com>,
Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
"Discussion list for crash utility usage,
maintenance and development" <crash-utility@redhat.com>
Subject: [kernel-hardening] Re: [PATCH 6/7] x86, kaslr: report kernel offset on panic
Date: Wed, 09 Oct 2013 07:13:26 -0700 [thread overview]
Message-ID: <52556486.9080109@zytor.com> (raw)
In-Reply-To: <52552A2A.8030505@jp.fujitsu.com>
On 10/09/2013 03:04 AM, HATAYAMA Daisuke wrote:
>>>
>>> Sorry, I don't understand why relocation size cannot be calculated when
>>> CONFIG_PHYSICALSTART > CONFIG_PHYSICAL_ALIGN. Could you explain that?
>>
>> I just meant that when CONFIG_PHYSICAL_START > CONFIG_PHYSICAL_ALIGN,
>> the 32-bit x86 kernel
>> gets relocated (like the secondary kdump kernel), but that information
>> is not readily available
>> from the vmlinux/vmcore pair.
>>
>
> My understanding on CONFIG_PHYSICAL_ALIGN was that starting address of
> kernel text area
> is always rounded up to CONFIG_PHYSICAL_ALIGN, only. Your explanation
> would be part I don't
> understand well. I'll reconsider it locally...
>
If CONFIG_PHYSICAL_START == CONFIG_PHYSICAL_ALIGN, then it is very
likely that the kernel (in the absence of kASLR) will be run at the
CONFIG_PHYSICAL_START address, as the initial loading address, usually 1
MB, will be rounded up to CONFIG_PHYSICAL_ALIGN.
Since CONFIG_PHYSICAL_START is the unrelocated linking address, they end
up matching.
-hpa
WARNING: multiple messages have this Message-ID (diff)
From: "H. Peter Anvin" <hpa@zytor.com>
To: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Dave Anderson <anderson@redhat.com>,
Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, kernel-hardening@lists.openwall.com,
Aaron Durbin <adurbin@google.com>,
Eric Northup <digitaleric@google.com>,
Julien Tinnes <jln@google.com>, Will Drewry <wad@google.com>,
Mathias Krause <minipli@googlemail.com>,
Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
"Discussion list for crash utility usage,
maintenance and development" <crash-utility@redhat.com>
Subject: Re: [PATCH 6/7] x86, kaslr: report kernel offset on panic
Date: Wed, 09 Oct 2013 07:13:26 -0700 [thread overview]
Message-ID: <52556486.9080109@zytor.com> (raw)
In-Reply-To: <52552A2A.8030505@jp.fujitsu.com>
On 10/09/2013 03:04 AM, HATAYAMA Daisuke wrote:
>>>
>>> Sorry, I don't understand why relocation size cannot be calculated when
>>> CONFIG_PHYSICALSTART > CONFIG_PHYSICAL_ALIGN. Could you explain that?
>>
>> I just meant that when CONFIG_PHYSICAL_START > CONFIG_PHYSICAL_ALIGN,
>> the 32-bit x86 kernel
>> gets relocated (like the secondary kdump kernel), but that information
>> is not readily available
>> from the vmlinux/vmcore pair.
>>
>
> My understanding on CONFIG_PHYSICAL_ALIGN was that starting address of
> kernel text area
> is always rounded up to CONFIG_PHYSICAL_ALIGN, only. Your explanation
> would be part I don't
> understand well. I'll reconsider it locally...
>
If CONFIG_PHYSICAL_START == CONFIG_PHYSICAL_ALIGN, then it is very
likely that the kernel (in the absence of kASLR) will be run at the
CONFIG_PHYSICAL_START address, as the initial loading address, usually 1
MB, will be rounded up to CONFIG_PHYSICAL_ALIGN.
Since CONFIG_PHYSICAL_START is the unrelocated linking address, they end
up matching.
-hpa
next prev parent reply other threads:[~2013-10-09 14:13 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-01 19:37 [kernel-hardening] [PATCH v6 0/7] Kernel base address randomization Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 1/7] x86, kaslr: move CPU flags out of cpucheck Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 20:48 ` [kernel-hardening] " H. Peter Anvin
2013-10-01 20:48 ` H. Peter Anvin
2013-10-01 21:09 ` [kernel-hardening] " Kees Cook
2013-10-01 21:09 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 2/7] x86, kaslr: return location from decompress_kernel Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 3/7] x86, kaslr: find minimum safe relocation position Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 4/7] x86, kaslr: select random base offset Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 20:46 ` [kernel-hardening] " H. Peter Anvin
2013-10-01 20:46 ` H. Peter Anvin
2013-10-01 21:18 ` [kernel-hardening] " Kees Cook
2013-10-01 21:18 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 5/7] x86, kaslr: select memory region from e820 maps Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 6/7] x86, kaslr: report kernel offset on panic Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-02 0:38 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-02 0:38 ` HATAYAMA Daisuke
2013-10-02 1:06 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-02 1:06 ` HATAYAMA Daisuke
2013-10-02 7:51 ` [kernel-hardening] " Kees Cook
2013-10-02 7:51 ` Kees Cook
2013-10-02 7:48 ` [kernel-hardening] " Kees Cook
2013-10-02 7:48 ` Kees Cook
2013-10-02 9:13 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-02 9:13 ` HATAYAMA Daisuke
2013-10-03 0:33 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-03 0:33 ` HATAYAMA Daisuke
2013-10-03 13:47 ` [kernel-hardening] " Dave Anderson
2013-10-03 13:47 ` Dave Anderson
2013-10-07 1:59 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-07 1:59 ` HATAYAMA Daisuke
2013-10-07 13:21 ` [kernel-hardening] " Dave Anderson
2013-10-07 13:21 ` Dave Anderson
2013-10-08 9:52 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-08 9:52 ` HATAYAMA Daisuke
2013-10-08 13:38 ` [kernel-hardening] " Dave Anderson
2013-10-08 13:38 ` Dave Anderson
2013-10-09 10:04 ` [kernel-hardening] " HATAYAMA Daisuke
2013-10-09 10:04 ` HATAYAMA Daisuke
2013-10-09 14:13 ` H. Peter Anvin [this message]
2013-10-09 14:13 ` H. Peter Anvin
2013-10-09 18:06 ` [kernel-hardening] " Kees Cook
2013-10-09 18:06 ` Kees Cook
2013-10-01 19:37 ` [kernel-hardening] [PATCH 7/7] x86, kaslr: raise max positions to 1GiB on x86_64 Kees Cook
2013-10-01 19:37 ` Kees Cook
2013-10-02 5:07 ` [kernel-hardening] Re: [PATCH v6 0/7] Kernel base address randomization Ingo Molnar
2013-10-02 5:07 ` Ingo Molnar
2013-10-02 5:11 ` [kernel-hardening] " H. Peter Anvin
2013-10-02 5:11 ` H. Peter Anvin
2013-10-02 5:25 ` [kernel-hardening] " Ingo Molnar
2013-10-02 5:25 ` Ingo Molnar
2013-10-02 5:30 ` [kernel-hardening] " H. Peter Anvin
2013-10-02 5:30 ` H. Peter Anvin
2013-10-02 5:36 ` [kernel-hardening] " Kees Cook
2013-10-02 5:36 ` Kees Cook
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