From 690eaa53205769fd5c0c36e3aa737a615135f969 Mon Sep 17 00:00:00 2001 From: Chao Fan Date: Wed, 23 Jan 2019 19:08:50 +0800 Subject: [PATCH] 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: Chao Fan Signed-off-by: Borislav Petkov Cc: Ard Biesheuvel Cc: Baoquan He Cc: caoj.fnst@cn.fujitsu.com Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: indou.takao@jp.fujitsu.com Cc: Ingo Molnar Cc: Juergen Gross Cc: kasong@redhat.com Cc: Kees Cook Cc: "Kirill A. Shutemov" Cc: msys.mizuma@gmail.com Cc: Thomas Gleixner Cc: Tom Lendacky Cc: x86-ml Link: https://lkml.kernel.org/r/20190123110850.12433-8-fanc.fnst@cn.fujitsu.com --- arch/x86/boot/compressed/kaslr.c | 71 +++++++++++++++++++++++++++----- arch/x86/boot/compressed/misc.h | 1 + 2 files changed, 61 insertions(+), 11 deletions(-) diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index b251572e77af..a2039afe14a7 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -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(®ion, minimum, image_size); - if (slot_area_index == MAX_SLOT_AREA) { - debug_putstr("Aborted EFI scan (slot_areas full)!\n"); + if (process_mem_region(®ion, 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(®ion, minimum, image_size); - if (slot_area_index == MAX_SLOT_AREA) { - debug_putstr("Aborted e820 scan (slot_areas full)!\n"); + if (process_mem_region(®ion, minimum, image_size)) break; - } } } diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index 9911d11c5d09..19e8231a6fd6 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -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; }