[tip:x86/boot] x86/KASLR, x86/power: Remove x86 hibernation restrictions

[tip-bot for Kees Cook]

Commit-ID:  65fe935dd2387a4faf15314c73f5e6d31ef0217e
Gitweb:     http://git.kernel.org/tip/65fe935dd2387a4faf15314c73f5e6d31ef0217e
Author:     Kees Cook <keescook@xxxxxxxxxxxx>
AuthorDate: Mon, 13 Jun 2016 15:10:02 -0700
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 26 Jun 2016 12:32:03 +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@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Linux PM list <linux-pm@xxxxxxxxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20160613221002.GA29719@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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);