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

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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: Chao Fan <fanc.fnst@cn.fujitsu.com>
Signed-off-by: Borislav 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
This commit is contained in:
Chao Fan 2019-01-23 19:08:50 +08:00 committed by Borislav Petkov
parent 02a3e3cdb7
commit 690eaa5320
2 changed files with 61 additions and 11 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

71
arch/x86/boot/compressed/kaslr.c
View file

@ -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);
@ -568,9 +573,9 @@ static unsigned long slots_fetch_random(void)
return 0;
}
static void process_mem_region(struct mem_vector *entry,
unsigned long minimum,
unsigned long image_size)
static void __process_mem_region(struct mem_vector *entry,
unsigned long minimum,
unsigned long image_size)
{
struct mem_vector region, overlap;
unsigned long start_orig, end;
@ -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
@ -711,11 +766,8 @@ 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;
}
@ -742,11 +794,8 @@ 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;
}
}
}

1
arch/x86/boot/compressed/misc.h
View file

@ -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; }