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Commit 690eaa53 authored by Chao Fan's avatar Chao Fan Committed by Borislav Petkov
Browse files

x86/boot/KASLR: Limit KASLR to extract the kernel in immovable memory only 



KASLR may randomly choose a range which is located in movable memory
regions. As a result, this will break memory hotplug and make the
movable memory chosen by KASLR immovable.

Therefore, limit KASLR to choose memory regions in the immovable range
after consulting the SRAT table.

 [ bp:
    - Rewrite commit message.
    - Trim comments.
 ]

Signed-off-by: default avatarChao Fan <fanc.fnst@cn.fujitsu.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: caoj.fnst@cn.fujitsu.com
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: indou.takao@jp.fujitsu.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: kasong@redhat.com
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: msys.mizuma@gmail.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190123110850.12433-8-fanc.fnst@cn.fujitsu.com
parent 02a3e3cd

arch/x86/boot/compressed/kaslr.c

+60 −11
Original line number Diff line number Diff line
@@ -97,6 +97,8 @@ static bool memmap_too_large; 
/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */

static unsigned long long mem_limit = ULLONG_MAX;



/* Number of immovable memory regions */

static int num_immovable_mem;



enum mem_avoid_index {

	MEM_AVOID_ZO_RANGE = 0,
@@ -413,6 +415,9 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size, 
	/* Mark the memmap regions we need to avoid */

	handle_mem_options();



	/* Enumerate the immovable memory regions */

	num_immovable_mem = count_immovable_mem_regions();



#ifdef CONFIG_X86_VERBOSE_BOOTUP

	/* Make sure video RAM can be used. */

	add_identity_map(0, PMD_SIZE);
@@ -568,7 +573,7 @@ static unsigned long slots_fetch_random(void) 
	return 0;

}



static void process_mem_region(struct mem_vector *entry,

static void __process_mem_region(struct mem_vector *entry,

				 unsigned long minimum,

				 unsigned long image_size)

{
@@ -646,6 +651,56 @@ static void process_mem_region(struct mem_vector *entry, 
	}

}



static bool process_mem_region(struct mem_vector *region,

			       unsigned long long minimum,

			       unsigned long long image_size)

{

	int i;

	/*

	 * If no immovable memory found, or MEMORY_HOTREMOVE disabled,

	 * use @region directly.

	 */

	if (!num_immovable_mem) {

		__process_mem_region(region, minimum, image_size);



		if (slot_area_index == MAX_SLOT_AREA) {

			debug_putstr("Aborted e820/efi memmap scan (slot_areas full)!\n");

			return 1;

		}

		return 0;

	}



#ifdef CONFIG_MEMORY_HOTREMOVE

	/*

	 * If immovable memory found, filter the intersection between

	 * immovable memory and @region.

	 */

	for (i = 0; i < num_immovable_mem; i++) {

		unsigned long long start, end, entry_end, region_end;

		struct mem_vector entry;



		if (!mem_overlaps(region, &immovable_mem[i]))

			continue;



		start = immovable_mem[i].start;

		end = start + immovable_mem[i].size;

		region_end = region->start + region->size;



		entry.start = clamp(region->start, start, end);

		entry_end = clamp(region_end, start, end);

		entry.size = entry_end - entry.start;



		__process_mem_region(&entry, minimum, image_size);



		if (slot_area_index == MAX_SLOT_AREA) {

			debug_putstr("Aborted e820/efi memmap scan when walking immovable regions(slot_areas full)!\n");

			return 1;

		}

	}

	return 0;

#endif

}



#ifdef CONFIG_EFI

/*

 * Returns true if mirror region found (and must have been processed
@@ -711,12 +766,9 @@ process_efi_entries(unsigned long minimum, unsigned long image_size) 


		region.start = md->phys_addr;

		region.size = md->num_pages << EFI_PAGE_SHIFT;

		process_mem_region(&region, minimum, image_size);

		if (slot_area_index == MAX_SLOT_AREA) {

			debug_putstr("Aborted EFI scan (slot_areas full)!\n");

		if (process_mem_region(&region, minimum, image_size))

			break;

	}

	}

	return true;

}

#else
@@ -742,13 +794,10 @@ static void process_e820_entries(unsigned long minimum, 
			continue;

		region.start = entry->addr;

		region.size = entry->size;

		process_mem_region(&region, minimum, image_size);

		if (slot_area_index == MAX_SLOT_AREA) {

			debug_putstr("Aborted e820 scan (slot_areas full)!\n");

		if (process_mem_region(&region, minimum, image_size))

			break;

	}

}

}



static unsigned long find_random_phys_addr(unsigned long minimum,

					   unsigned long image_size)

arch/x86/boot/compressed/misc.h

+1 −0
Original line number Diff line number Diff line
@@ -132,6 +132,7 @@ static inline acpi_physical_address get_rsdp_addr(void) { return 0; } 
#endif



#if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE)

extern struct mem_vector immovable_mem[MAX_NUMNODES*2];

int count_immovable_mem_regions(void);

#else

static inline int count_immovable_mem_regions(void) { return 0; }