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Subject[tip:x86/boot] x86/KASLR, x86/power: Remove x86 hibernation restrictions
Commit-ID:  36f79151e74bbca512cac092c2c56c5cbc5f2f03
Gitweb: http://git.kernel.org/tip/36f79151e74bbca512cac092c2c56c5cbc5f2f03
Author: Kees Cook <keescook@chromium.org>
AuthorDate: Mon, 13 Jun 2016 15:10:02 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 14 Jun 2016 12:14:13 +0200

x86/KASLR, x86/power: Remove x86 hibernation restrictions

With the following fix:

70595b479ce1 ("x86/power/64: Fix crash whan the hibernation code passes control to the image kernel")

... there is no longer a problem with hibernation resuming a
KASLR-booted kernel image, so remove the restriction.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux PM list <linux-pm@vger.kernel.org>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20160613221002.GA29719@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
Documentation/kernel-parameters.txt | 10 ++++------
arch/x86/boot/compressed/kaslr.c | 7 -------
kernel/power/hibernate.c | 6 ------
3 files changed, 4 insertions(+), 19 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 82b42c9..fa8c6d4 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1803,12 +1803,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
js= [HW,JOY] Analog joystick
See Documentation/input/joystick.txt.

- kaslr/nokaslr [X86]
- Enable/disable kernel and module base offset ASLR
- (Address Space Layout Randomization) if built into
- the kernel. When CONFIG_HIBERNATION is selected,
- kASLR is disabled by default. When kASLR is enabled,
- hibernation will be disabled.
+ nokaslr [KNL]
+ When CONFIG_RANDOMIZE_BASE is set, this disables
+ kernel and module base offset ASLR (Address Space
+ Layout Randomization).

keepinitrd [HW,ARM]

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index cfeb025..dff4217 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -471,17 +471,10 @@ unsigned char *choose_random_location(unsigned long input,
unsigned long choice = output;
unsigned long random_addr;

-#ifdef CONFIG_HIBERNATION
- if (!cmdline_find_option_bool("kaslr")) {
- warn("KASLR disabled: 'kaslr' not on cmdline (hibernation selected).");
- goto out;
- }
-#else
if (cmdline_find_option_bool("nokaslr")) {
warn("KASLR disabled: 'nokaslr' on cmdline.");
goto out;
}
-#endif

boot_params->hdr.loadflags |= KASLR_FLAG;

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index fca9254..9021387 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -1154,11 +1154,6 @@ static int __init nohibernate_setup(char *str)
return 1;
}

-static int __init kaslr_nohibernate_setup(char *str)
-{
- return nohibernate_setup(str);
-}
-
static int __init page_poison_nohibernate_setup(char *str)
{
#ifdef CONFIG_PAGE_POISONING_ZERO
@@ -1182,5 +1177,4 @@ __setup("hibernate=", hibernate_setup);
__setup("resumewait", resumewait_setup);
__setup("resumedelay=", resumedelay_setup);
__setup("nohibernate", nohibernate_setup);
-__setup("kaslr", kaslr_nohibernate_setup);
__setup("page_poison=", page_poison_nohibernate_setup);
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