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-rw-r--r--arch/x86/boot/compressed/kaslr.c140
1 files changed, 137 insertions, 3 deletions
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index a66854d99ee1..8b7c9e75edcb 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -11,6 +11,7 @@
*/
#include "misc.h"
#include "error.h"
+#include "../boot.h"
#include <generated/compile.h>
#include <linux/module.h>
@@ -52,15 +53,22 @@ static unsigned long get_boot_seed(void)
#include "../../lib/kaslr.c"
struct mem_vector {
- unsigned long start;
- unsigned long size;
+ unsigned long long start;
+ unsigned long long size;
};
+/* Only supporting at most 4 unusable memmap regions with kaslr */
+#define MAX_MEMMAP_REGIONS 4
+
+static bool memmap_too_large;
+
enum mem_avoid_index {
MEM_AVOID_ZO_RANGE = 0,
MEM_AVOID_INITRD,
MEM_AVOID_CMDLINE,
MEM_AVOID_BOOTPARAMS,
+ MEM_AVOID_MEMMAP_BEGIN,
+ MEM_AVOID_MEMMAP_END = MEM_AVOID_MEMMAP_BEGIN + MAX_MEMMAP_REGIONS - 1,
MEM_AVOID_MAX,
};
@@ -77,6 +85,123 @@ static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two)
return true;
}
+/**
+ * _memparse - Parse a string with mem suffixes into a number
+ * @ptr: Where parse begins
+ * @retptr: (output) Optional pointer to next char after parse completes
+ *
+ * Parses a string into a number. The number stored at @ptr is
+ * potentially suffixed with K, M, G, T, P, E.
+ */
+static unsigned long long _memparse(const char *ptr, char **retptr)
+{
+ char *endptr; /* Local pointer to end of parsed string */
+
+ unsigned long long ret = simple_strtoull(ptr, &endptr, 0);
+
+ switch (*endptr) {
+ case 'E':
+ case 'e':
+ ret <<= 10;
+ case 'P':
+ case 'p':
+ ret <<= 10;
+ case 'T':
+ case 't':
+ ret <<= 10;
+ case 'G':
+ case 'g':
+ ret <<= 10;
+ case 'M':
+ case 'm':
+ ret <<= 10;
+ case 'K':
+ case 'k':
+ ret <<= 10;
+ endptr++;
+ default:
+ break;
+ }
+
+ if (retptr)
+ *retptr = endptr;
+
+ return ret;
+}
+
+static int
+parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
+{
+ char *oldp;
+
+ if (!p)
+ return -EINVAL;
+
+ /* We don't care about this option here */
+ if (!strncmp(p, "exactmap", 8))
+ return -EINVAL;
+
+ oldp = p;
+ *size = _memparse(p, &p);
+ if (p == oldp)
+ return -EINVAL;
+
+ switch (*p) {
+ case '@':
+ /* Skip this region, usable */
+ *start = 0;
+ *size = 0;
+ return 0;
+ case '#':
+ case '$':
+ case '!':
+ *start = _memparse(p + 1, &p);
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static void mem_avoid_memmap(void)
+{
+ char arg[128];
+ int rc;
+ int i;
+ char *str;
+
+ /* See if we have any memmap areas */
+ rc = cmdline_find_option("memmap", arg, sizeof(arg));
+ if (rc <= 0)
+ return;
+
+ i = 0;
+ str = arg;
+ while (str && (i < MAX_MEMMAP_REGIONS)) {
+ int rc;
+ unsigned long long start, size;
+ char *k = strchr(str, ',');
+
+ if (k)
+ *k++ = 0;
+
+ rc = parse_memmap(str, &start, &size);
+ if (rc < 0)
+ break;
+ str = k;
+ /* A usable region that should not be skipped */
+ if (size == 0)
+ continue;
+
+ mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
+ mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
+ i++;
+ }
+
+ /* More than 4 memmaps, fail kaslr */
+ if ((i >= MAX_MEMMAP_REGIONS) && str)
+ memmap_too_large = true;
+}
+
/*
* In theory, KASLR can put the kernel anywhere in the range of [16M, 64T).
* The mem_avoid array is used to store the ranges that need to be avoided
@@ -197,6 +322,9 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
/* We don't need to set a mapping for setup_data. */
+ /* Mark the memmap regions we need to avoid */
+ mem_avoid_memmap();
+
#ifdef CONFIG_X86_VERBOSE_BOOTUP
/* Make sure video RAM can be used. */
add_identity_map(0, PMD_SIZE);
@@ -379,6 +507,12 @@ static unsigned long find_random_phys_addr(unsigned long minimum,
int i;
unsigned long addr;
+ /* Check if we had too many memmaps. */
+ if (memmap_too_large) {
+ debug_putstr("Aborted e820 scan (more than 4 memmap= args)!\n");
+ return 0;
+ }
+
/* Make sure minimum is aligned. */
minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
@@ -456,7 +590,7 @@ void choose_random_location(unsigned long input,
/* Walk e820 and find a random address. */
random_addr = find_random_phys_addr(min_addr, output_size);
if (!random_addr) {
- warn("KASLR disabled: could not find suitable E820 region!");
+ warn("Physical KASLR disabled: no suitable memory region!");
} else {
/* Update the new physical address location. */
if (*output != random_addr) {