x86, kaslr: boot-time selectable with hibernation

Changes kASLR from being compile-time selectable (blocked by
CONFIG_HIBERNATION), to being boot-time selectable (with hibernation
available by default) via the "kaslr" kernel command line.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f8f0466..8849049 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1474,6 +1474,13 @@ 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.
+
        keepinitrd      [HW,ARM]
 
        kernelcore=nn[KMG]      [KNL,X86,IA-64,PPC] This parameter
@@ -2110,10 +2117,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
        noapic          [SMP,APIC] Tells the kernel to not make use of any
                        IOAPICs that may be present in the system.
 
-       nokaslr         [X86]
-                       Disable kernel and module base offset ASLR (Address
-                       Space Layout Randomization) if built into the kernel.
-
        noautogroup     Disable scheduler automatic task group creation.
 
        nobats          [PPC] Do not use BATs for mapping kernel lowmem

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fcefdda..a8f749e 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1672,7 +1672,6 @@ config RELOCATABLE
 config RANDOMIZE_BASE
        bool "Randomize the address of the kernel image"
        depends on RELOCATABLE
-       depends on !HIBERNATION
        default n
        ---help---
           Randomizes the physical and virtual address at which the

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index 4dbf967..fc6091a 100644 (file)
--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -289,10 +289,17 @@ unsigned char *choose_kernel_location(unsigned char *input,
        unsigned long choice = (unsigned long)output;
        unsigned long random;
 
+#ifdef CONFIG_HIBERNATION
+       if (!cmdline_find_option_bool("kaslr")) {
+               debug_putstr("KASLR disabled by default...\n");
+               goto out;
+       }
+#else
        if (cmdline_find_option_bool("nokaslr")) {
-               debug_putstr("KASLR disabled...\n");
+               debug_putstr("KASLR disabled by cmdline...\n");
                goto out;
        }
+#endif
 
        /* Record the various known unsafe memory ranges. */
        mem_avoid_init((unsigned long)input, input_size,

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 258f492..fcc2611 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -1153,6 +1153,11 @@ static int __init nohibernate_setup(char *str)
        return 1;
 }
 
+static int __init kaslr_nohibernate_setup(char *str)
+{
+       return nohibernate_setup(str);
+}
+
 __setup("noresume", noresume_setup);
 __setup("resume_offset=", resume_offset_setup);
 __setup("resume=", resume_setup);
@@ -1160,3 +1165,4 @@ __setup("hibernate=", hibernate_setup);
 __setup("resumewait", resumewait_setup);
 __setup("resumedelay=", resumedelay_setup);
 __setup("nohibernate", nohibernate_setup);
+__setup("kaslr", kaslr_nohibernate_setup);