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x86/mm: Add memory hotplug support for KASLR memory randomization

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Add a new option (CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING) to define
the padding used for the physical memory mapping section when KASLR
memory is enabled. It ensures there is enough virtual address space when
CONFIG_MEMORY_HOTPLUG is used. The default value is 10 terabytes. If
CONFIG_MEMORY_HOTPLUG is not used, no space is reserved increasing the
entropy available.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1466556426-32664-10-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Thomas Garnier 2016-06-21 17:47:06 -07:00 committed by Ingo Molnar
parent a95ae27c2e
commit 90397a4177
2 changed files with 21 additions and 1 deletions
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15
arch/x86/Kconfig
View file

@ -2010,6 +2010,21 @@ config RANDOMIZE_MEMORY
If unsure, say N.
config RANDOMIZE_MEMORY_PHYSICAL_PADDING
hex "Physical memory mapping padding" if EXPERT
depends on RANDOMIZE_MEMORY
default "0xa" if MEMORY_HOTPLUG
default "0x0"
range 0x1 0x40 if MEMORY_HOTPLUG
range 0x0 0x40
---help---
Define the padding in terabytes added to the existing physical
memory size during kernel memory randomization. It is useful
for memory hotplug support but reduces the entropy available for
address randomization.
If unsure, leave at the default value.
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
depends on SMP

7
arch/x86/mm/kaslr.c
View file

@ -92,8 +92,13 @@ void __init kernel_randomize_memory(void)
if (!kaslr_memory_enabled())
return;
/*
* Update Physical memory mapping to available and
* add padding if needed (especially for memory hotplug support).
*/
BUG_ON(kaslr_regions[0].base != &page_offset_base);
memory_tb = ((max_pfn << PAGE_SHIFT) >> TB_SHIFT);
memory_tb = ((max_pfn << PAGE_SHIFT) >> TB_SHIFT) +
CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
/* Adapt phyiscal memory region size based on available memory */
if (memory_tb < kaslr_regions[0].size_tb)