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@xxxxxxxxxxxx>
---
Documentation/kernel-parameters.txt | 11 +++++++----
arch/x86/Kconfig | 1 -
arch/x86/boot/compressed/aslr.c | 9 ++++++++-
kernel/power/hibernate.c | 6 ++++++
4 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index f8f0466b8b1d..884904975d0b 100644
--- 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 b660088c220d..7fdb639f1b63 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1671,7 +1671,6 @@ 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 4dbf967da50d..fc6091abedb7 100644
--- 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 fd3e785dbc37..c1e0daa032b3 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -1150,6 +1150,11 @@ 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);
@@ -1157,3 +1162,4 @@ __setup("hibernate=", hibernate_setup);
__setup("resumewait", resumewait_setup);
__setup("resumedelay=", resumedelay_setup);
__setup("nohibernate", nohibernate_setup);
+__setup("kaslr", kaslr_nohibernate_setup);
--
1.7.9.5
--
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