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authorKees Cook2016-04-18 09:42:14 -0700
committerIngo Molnar2016-04-19 10:30:51 +0200
commit7de828dfe607013546ece7ce25aa9839e8f93a66 (patch)
treeb95b70071b3cf1dcc0b653b964528ffa5d250b0e
parentc04028813221c2d39a4f368586795ac4466d311c (diff)
x86/KASLR: Clarify purpose of kaslr.c
The name "choose_kernel_location" isn't specific enough, and doesn't describe the primary thing it does: choosing a random location. This patch renames it to "choose_random_location", and clarifies the what routines are contained in the kaslr.c source file. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: H.J. Lu <hjl.tools@gmail.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1460997735-24785-6-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/boot/compressed/kaslr.c13
-rw-r--r--arch/x86/boot/compressed/misc.c2
-rw-r--r--arch/x86/boot/compressed/misc.h4
3 files changed, 15 insertions, 4 deletions
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index a51ec841c9b9..9e03190d00ad 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -1,3 +1,14 @@
+/*
+ * kaslr.c
+ *
+ * This contains the routines needed to generate a reasonable level of
+ * entropy to choose a randomized kernel base address offset in support
+ * of Kernel Address Space Layout Randomization (KASLR). Additionally
+ * handles walking the physical memory maps (and tracking memory regions
+ * to avoid) in order to select a physical memory location that can
+ * contain the entire properly aligned running kernel image.
+ *
+ */
#include "misc.h"
#include <asm/msr.h>
@@ -295,7 +306,7 @@ static unsigned long find_random_addr(unsigned long minimum,
return slots_fetch_random();
}
-unsigned char *choose_kernel_location(unsigned char *input,
+unsigned char *choose_random_location(unsigned char *input,
unsigned long input_size,
unsigned char *output,
unsigned long output_size)
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 0d69e809673a..ad8c01ac2885 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -431,7 +431,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
* the entire decompressed kernel plus relocation table, or the
* entire decompressed kernel plus .bss and .brk sections.
*/
- output = choose_kernel_location(input_data, input_len, output,
+ output = choose_random_location(input_data, input_len, output,
output_len > run_size ? output_len
: run_size);
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 1f750a516580..9887e0d4aaeb 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -67,7 +67,7 @@ int cmdline_find_option_bool(const char *option);
#if CONFIG_RANDOMIZE_BASE
/* kaslr.c */
-unsigned char *choose_kernel_location(unsigned char *input,
+unsigned char *choose_random_location(unsigned char *input,
unsigned long input_size,
unsigned char *output,
unsigned long output_size);
@@ -75,7 +75,7 @@ unsigned char *choose_kernel_location(unsigned char *input,
bool has_cpuflag(int flag);
#else
static inline
-unsigned char *choose_kernel_location(unsigned char *input,
+unsigned char *choose_random_location(unsigned char *input,
unsigned long input_size,
unsigned char *output,
unsigned long output_size)