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Diffstat (limited to 'arch/x86/boot/compressed/aslr.c')
-rw-r--r--arch/x86/boot/compressed/aslr.c339
1 files changed, 0 insertions, 339 deletions
diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
deleted file mode 100644
index 6a9b96b4624d..000000000000
--- a/arch/x86/boot/compressed/aslr.c
+++ /dev/null
@@ -1,339 +0,0 @@
-#include "misc.h"
-
-#include <asm/msr.h>
-#include <asm/archrandom.h>
-#include <asm/e820.h>
-
-#include <generated/compile.h>
-#include <linux/module.h>
-#include <linux/uts.h>
-#include <linux/utsname.h>
-#include <generated/utsrelease.h>
-
-/* Simplified build-specific string for starting entropy. */
-static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
- LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
-
-#define I8254_PORT_CONTROL 0x43
-#define I8254_PORT_COUNTER0 0x40
-#define I8254_CMD_READBACK 0xC0
-#define I8254_SELECT_COUNTER0 0x02
-#define I8254_STATUS_NOTREADY 0x40
-static inline u16 i8254(void)
-{
- u16 status, timer;
-
- do {
- outb(I8254_PORT_CONTROL,
- I8254_CMD_READBACK | I8254_SELECT_COUNTER0);
- status = inb(I8254_PORT_COUNTER0);
- timer = inb(I8254_PORT_COUNTER0);
- timer |= inb(I8254_PORT_COUNTER0) << 8;
- } while (status & I8254_STATUS_NOTREADY);
-
- return timer;
-}
-
-static unsigned long rotate_xor(unsigned long hash, const void *area,
- size_t size)
-{
- size_t i;
- unsigned long *ptr = (unsigned long *)area;
-
- for (i = 0; i < size / sizeof(hash); i++) {
- /* Rotate by odd number of bits and XOR. */
- hash = (hash << ((sizeof(hash) * 8) - 7)) | (hash >> 7);
- hash ^= ptr[i];
- }
-
- return hash;
-}
-
-/* Attempt to create a simple but unpredictable starting entropy. */
-static unsigned long get_random_boot(void)
-{
- unsigned long hash = 0;
-
- hash = rotate_xor(hash, build_str, sizeof(build_str));
- hash = rotate_xor(hash, real_mode, sizeof(*real_mode));
-
- return hash;
-}
-
-static unsigned long get_random_long(void)
-{
-#ifdef CONFIG_X86_64
- const unsigned long mix_const = 0x5d6008cbf3848dd3UL;
-#else
- const unsigned long mix_const = 0x3f39e593UL;
-#endif
- unsigned long raw, random = get_random_boot();
- bool use_i8254 = true;
-
- debug_putstr("KASLR using");
-
- if (has_cpuflag(X86_FEATURE_RDRAND)) {
- debug_putstr(" RDRAND");
- if (rdrand_long(&raw)) {
- random ^= raw;
- use_i8254 = false;
- }
- }
-
- if (has_cpuflag(X86_FEATURE_TSC)) {
- debug_putstr(" RDTSC");
- raw = rdtsc();
-
- random ^= raw;
- use_i8254 = false;
- }
-
- if (use_i8254) {
- debug_putstr(" i8254");
- random ^= i8254();
- }
-
- /* Circular multiply for better bit diffusion */
- asm("mul %3"
- : "=a" (random), "=d" (raw)
- : "a" (random), "rm" (mix_const));
- random += raw;
-
- debug_putstr("...\n");
-
- return random;
-}
-
-struct mem_vector {
- unsigned long start;
- unsigned long size;
-};
-
-#define MEM_AVOID_MAX 5
-static struct mem_vector mem_avoid[MEM_AVOID_MAX];
-
-static bool mem_contains(struct mem_vector *region, struct mem_vector *item)
-{
- /* Item at least partially before region. */
- if (item->start < region->start)
- return false;
- /* Item at least partially after region. */
- if (item->start + item->size > region->start + region->size)
- return false;
- return true;
-}
-
-static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two)
-{
- /* Item one is entirely before item two. */
- if (one->start + one->size <= two->start)
- return false;
- /* Item one is entirely after item two. */
- if (one->start >= two->start + two->size)
- return false;
- return true;
-}
-
-static void mem_avoid_init(unsigned long input, unsigned long input_size,
- unsigned long output, unsigned long output_size)
-{
- u64 initrd_start, initrd_size;
- u64 cmd_line, cmd_line_size;
- unsigned long unsafe, unsafe_len;
- char *ptr;
-
- /*
- * Avoid the region that is unsafe to overlap during
- * decompression (see calculations at top of misc.c).
- */
- unsafe_len = (output_size >> 12) + 32768 + 18;
- unsafe = (unsigned long)input + input_size - unsafe_len;
- mem_avoid[0].start = unsafe;
- mem_avoid[0].size = unsafe_len;
-
- /* Avoid initrd. */
- initrd_start = (u64)real_mode->ext_ramdisk_image << 32;
- initrd_start |= real_mode->hdr.ramdisk_image;
- initrd_size = (u64)real_mode->ext_ramdisk_size << 32;
- initrd_size |= real_mode->hdr.ramdisk_size;
- mem_avoid[1].start = initrd_start;
- mem_avoid[1].size = initrd_size;
-
- /* Avoid kernel command line. */
- cmd_line = (u64)real_mode->ext_cmd_line_ptr << 32;
- cmd_line |= real_mode->hdr.cmd_line_ptr;
- /* Calculate size of cmd_line. */
- ptr = (char *)(unsigned long)cmd_line;
- for (cmd_line_size = 0; ptr[cmd_line_size++]; )
- ;
- mem_avoid[2].start = cmd_line;
- mem_avoid[2].size = cmd_line_size;
-
- /* Avoid heap memory. */
- mem_avoid[3].start = (unsigned long)free_mem_ptr;
- mem_avoid[3].size = BOOT_HEAP_SIZE;
-
- /* Avoid stack memory. */
- mem_avoid[4].start = (unsigned long)free_mem_end_ptr;
- mem_avoid[4].size = BOOT_STACK_SIZE;
-}
-
-/* Does this memory vector overlap a known avoided area? */
-static bool mem_avoid_overlap(struct mem_vector *img)
-{
- int i;
- struct setup_data *ptr;
-
- for (i = 0; i < MEM_AVOID_MAX; i++) {
- if (mem_overlaps(img, &mem_avoid[i]))
- return true;
- }
-
- /* Avoid all entries in the setup_data linked list. */
- ptr = (struct setup_data *)(unsigned long)real_mode->hdr.setup_data;
- while (ptr) {
- struct mem_vector avoid;
-
- avoid.start = (unsigned long)ptr;
- avoid.size = sizeof(*ptr) + ptr->len;
-
- if (mem_overlaps(img, &avoid))
- return true;
-
- ptr = (struct setup_data *)(unsigned long)ptr->next;
- }
-
- return false;
-}
-
-static unsigned long slots[CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
- CONFIG_PHYSICAL_ALIGN];
-static unsigned long slot_max;
-
-static void slots_append(unsigned long addr)
-{
- /* Overflowing the slots list should be impossible. */
- if (slot_max >= CONFIG_RANDOMIZE_BASE_MAX_OFFSET /
- CONFIG_PHYSICAL_ALIGN)
- return;
-
- slots[slot_max++] = addr;
-}
-
-static unsigned long slots_fetch_random(void)
-{
- /* Handle case of no slots stored. */
- if (slot_max == 0)
- return 0;
-
- return slots[get_random_long() % slot_max];
-}
-
-static void process_e820_entry(struct e820entry *entry,
- unsigned long minimum,
- unsigned long image_size)
-{
- struct mem_vector region, img;
-
- /* Skip non-RAM entries. */
- if (entry->type != E820_RAM)
- return;
-
- /* Ignore entries entirely above our maximum. */
- if (entry->addr >= CONFIG_RANDOMIZE_BASE_MAX_OFFSET)
- return;
-
- /* Ignore entries entirely below our minimum. */
- if (entry->addr + entry->size < minimum)
- return;
-
- region.start = entry->addr;
- region.size = entry->size;
-
- /* Potentially raise address to minimum location. */
- if (region.start < minimum)
- region.start = minimum;
-
- /* Potentially raise address to meet alignment requirements. */
- region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
-
- /* Did we raise the address above the bounds of this e820 region? */
- if (region.start > entry->addr + entry->size)
- return;
-
- /* Reduce size by any delta from the original address. */
- region.size -= region.start - entry->addr;
-
- /* Reduce maximum size to fit end of image within maximum limit. */
- if (region.start + region.size > CONFIG_RANDOMIZE_BASE_MAX_OFFSET)
- region.size = CONFIG_RANDOMIZE_BASE_MAX_OFFSET - region.start;
-
- /* Walk each aligned slot and check for avoided areas. */
- for (img.start = region.start, img.size = image_size ;
- mem_contains(&region, &img) ;
- img.start += CONFIG_PHYSICAL_ALIGN) {
- if (mem_avoid_overlap(&img))
- continue;
- slots_append(img.start);
- }
-}
-
-static unsigned long find_random_addr(unsigned long minimum,
- unsigned long size)
-{
- int i;
- unsigned long addr;
-
- /* Make sure minimum is aligned. */
- minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
-
- /* Verify potential e820 positions, appending to slots list. */
- for (i = 0; i < real_mode->e820_entries; i++) {
- process_e820_entry(&real_mode->e820_map[i], minimum, size);
- }
-
- return slots_fetch_random();
-}
-
-unsigned char *choose_kernel_location(struct boot_params *boot_params,
- unsigned char *input,
- unsigned long input_size,
- unsigned char *output,
- unsigned long output_size)
-{
- unsigned long choice = (unsigned long)output;
- unsigned long random;
-
-#ifdef CONFIG_HIBERNATION
- if (!cmdline_find_option_bool("kaslr")) {
- debug_putstr("KASLR disabled by default...\n");
- goto out;
- }
-#else
- if (cmdline_find_option_bool("nokaslr")) {
- debug_putstr("KASLR disabled by cmdline...\n");
- goto out;
- }
-#endif
-
- boot_params->hdr.loadflags |= KASLR_FLAG;
-
- /* Record the various known unsafe memory ranges. */
- mem_avoid_init((unsigned long)input, input_size,
- (unsigned long)output, output_size);
-
- /* Walk e820 and find a random address. */
- random = find_random_addr(choice, output_size);
- if (!random) {
- debug_putstr("KASLR could not find suitable E820 region...\n");
- goto out;
- }
-
- /* Always enforce the minimum. */
- if (random < choice)
- goto out;
-
- choice = random;
-out:
- return (unsigned char *)choice;
-}
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