Merge branch 'tip-x86-kaslr' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp into x86/urgent

Pull ASLR and kASLR fixes from Borislav Petkov:

  - Add a global flag announcing KASLR state so that relevant code can do
    informed decisions based on its setting. (Jiri Kosina)

  - Fix a stack randomization entropy decrease bug. (Hector Marco-Gisbert)

Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/boot/compressed/aslr.c

@@ -14,6 +14,13 @@
 static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
 		LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
 
+struct kaslr_setup_data {
+	__u64 next;
+	__u32 type;
+	__u32 len;
+	__u8 data[1];
+} kaslr_setup_data;
+
 #define I8254_PORT_CONTROL	0x43
 #define I8254_PORT_COUNTER0	0x40
 #define I8254_CMD_READBACK	0xC0
@@ -295,7 +302,29 @@ static unsigned long find_random_addr(unsigned long minimum,
 	return slots_fetch_random();
 }
 
-unsigned char *choose_kernel_location(unsigned char *input,
+static void add_kaslr_setup_data(struct boot_params *params, __u8 enabled)
+{
+	struct setup_data *data;
+
+	kaslr_setup_data.type = SETUP_KASLR;
+	kaslr_setup_data.len = 1;
+	kaslr_setup_data.next = 0;
+	kaslr_setup_data.data[0] = enabled;
+
+	data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
+
+	while (data && data->next)
+		data = (struct setup_data *)(unsigned long)data->next;
+
+	if (data)
+		data->next = (unsigned long)&kaslr_setup_data;
+	else
+		params->hdr.setup_data = (unsigned long)&kaslr_setup_data;
+
+}
+
+unsigned char *choose_kernel_location(struct boot_params *params,
+				      unsigned char *input,
 				      unsigned long input_size,
 				      unsigned char *output,
 				      unsigned long output_size)
@@ -306,14 +335,17 @@ unsigned char *choose_kernel_location(unsigned char *input,
 #ifdef CONFIG_HIBERNATION
 	if (!cmdline_find_option_bool("kaslr")) {
 		debug_putstr("KASLR disabled by default...\n");
+		add_kaslr_setup_data(params, 0);
 		goto out;
 	}
 #else
 	if (cmdline_find_option_bool("nokaslr")) {
 		debug_putstr("KASLR disabled by cmdline...\n");
+		add_kaslr_setup_data(params, 0);
 		goto out;
 	}
 #endif
+	add_kaslr_setup_data(params, 1);
 
 	/* Record the various known unsafe memory ranges. */
 	mem_avoid_init((unsigned long)input, input_size,

arch/x86/boot/compressed/misc.c

@@ -401,7 +401,8 @@ asmlinkage __visible void *decompress_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_kernel_location(real_mode, input_data, input_len,
+					output,
 					output_len > run_size ? output_len
 							      : run_size);
 

arch/x86/boot/compressed/misc.h

@@ -56,7 +56,8 @@ int cmdline_find_option_bool(const char *option);
 
 #if CONFIG_RANDOMIZE_BASE
 /* aslr.c */
-unsigned char *choose_kernel_location(unsigned char *input,
+unsigned char *choose_kernel_location(struct boot_params *params,
+				      unsigned char *input,
 				      unsigned long input_size,
 				      unsigned char *output,
 				      unsigned long output_size);
@@ -64,7 +65,8 @@ 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_kernel_location(struct boot_params *params,
+				      unsigned char *input,
 				      unsigned long input_size,
 				      unsigned char *output,
 				      unsigned long output_size)

arch/x86/include/asm/page_types.h

@@ -3,6 +3,7 @@
 
 #include <linux/const.h>
 #include <linux/types.h>
+#include <asm/bootparam.h>
 
 /* PAGE_SHIFT determines the page size */
 #define PAGE_SHIFT	12
@@ -51,6 +52,8 @@ extern int devmem_is_allowed(unsigned long pagenr);
 extern unsigned long max_low_pfn_mapped;
 extern unsigned long max_pfn_mapped;
 
+extern bool kaslr_enabled;
+
 static inline phys_addr_t get_max_mapped(void)
 {
 	return (phys_addr_t)max_pfn_mapped << PAGE_SHIFT;

arch/x86/include/uapi/asm/bootparam.h

@@ -7,6 +7,7 @@
 #define SETUP_DTB			2
 #define SETUP_PCI			3
 #define SETUP_EFI			4
+#define SETUP_KASLR			5
 
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK	0x07FF

arch/x86/kernel/module.c

@@ -32,6 +32,7 @@
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
+#include <asm/page_types.h>
 
 #if 0
 #define DEBUGP(fmt, ...)				\
@@ -46,21 +47,13 @@ do {							\
 
 #ifdef CONFIG_RANDOMIZE_BASE
 static unsigned long module_load_offset;
-static int randomize_modules = 1;
 
 /* Mutex protects the module_load_offset. */
 static DEFINE_MUTEX(module_kaslr_mutex);
 
-static int __init parse_nokaslr(char *p)
-{
-	randomize_modules = 0;
-	return 0;
-}
-early_param("nokaslr", parse_nokaslr);
-
 static unsigned long int get_module_load_offset(void)
 {
-	if (randomize_modules) {
+	if (kaslr_enabled) {
 		mutex_lock(&module_kaslr_mutex);
 		/*
 		 * Calculate the module_load_offset the first time this

arch/x86/kernel/setup.c

@@ -121,6 +121,8 @@
 unsigned long max_low_pfn_mapped;
 unsigned long max_pfn_mapped;
 
+bool __read_mostly kaslr_enabled = false;
+
 #ifdef CONFIG_DMI
 RESERVE_BRK(dmi_alloc, 65536);
 #endif
@@ -424,6 +426,11 @@ static void __init reserve_initrd(void)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+static void __init parse_kaslr_setup(u64 pa_data, u32 data_len)
+{
+	kaslr_enabled = (bool)(pa_data + sizeof(struct setup_data));
+}
+
 static void __init parse_setup_data(void)
 {
 	struct setup_data *data;
@@ -449,6 +456,9 @@ static void __init parse_setup_data(void)
 		case SETUP_EFI:
 			parse_efi_setup(pa_data, data_len);
 			break;
+		case SETUP_KASLR:
+			parse_kaslr_setup(pa_data, data_len);
+			break;
 		default:
 			break;
 		}
@@ -831,10 +841,14 @@ static void __init trim_low_memory_range(void)
 static int
 dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 {
-	pr_emerg("Kernel Offset: 0x%lx from 0x%lx "
-		 "(relocation range: 0x%lx-0x%lx)\n",
-		 (unsigned long)&_text - __START_KERNEL, __START_KERNEL,
-		 __START_KERNEL_map, MODULES_VADDR-1);
+	if (kaslr_enabled)
+		pr_emerg("Kernel Offset: 0x%lx from 0x%lx (relocation range: 0x%lx-0x%lx)\n",
+			 (unsigned long)&_text - __START_KERNEL,
+			 __START_KERNEL,
+			 __START_KERNEL_map,
+			 MODULES_VADDR-1);
+	else
+		pr_emerg("Kernel Offset: disabled\n");
 
 	return 0;
 }

arch/x86/mm/mmap.c

@@ -35,12 +35,12 @@ struct va_alignment __read_mostly va_align = {
 	.flags = -1,
 };
 
-static unsigned int stack_maxrandom_size(void)
+static unsigned long stack_maxrandom_size(void)
 {
-	unsigned int max = 0;
+	unsigned long max = 0;
 	if ((current->flags & PF_RANDOMIZE) &&
 		!(current->personality & ADDR_NO_RANDOMIZE)) {
-		max = ((-1U) & STACK_RND_MASK) << PAGE_SHIFT;
+		max = ((-1UL) & STACK_RND_MASK) << PAGE_SHIFT;
 	}
 
 	return max;

fs/binfmt_elf.c

@@ -645,11 +645,12 @@ out:
 
 static unsigned long randomize_stack_top(unsigned long stack_top)
 {
-	unsigned int random_variable = 0;
+	unsigned long random_variable = 0;
 
 	if ((current->flags & PF_RANDOMIZE) &&
 		!(current->personality & ADDR_NO_RANDOMIZE)) {
-		random_variable = get_random_int() & STACK_RND_MASK;
+		random_variable = (unsigned long) get_random_int();
+		random_variable &= STACK_RND_MASK;
 		random_variable <<= PAGE_SHIFT;
 	}
 #ifdef CONFIG_STACK_GROWSUP