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Diffstat (limited to 'arch/x86/boot/compressed/kaslr.c')
-rw-r--r--arch/x86/boot/compressed/kaslr.c325
1 files changed, 240 insertions, 85 deletions
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 56a7e9201741..a63fbc25ce84 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
/*
* kaslr.c
*
@@ -9,15 +10,43 @@
* contain the entire properly aligned running kernel image.
*
*/
+
+/*
+ * isspace() in linux/ctype.h is expected by next_args() to filter
+ * out "space/lf/tab". While boot/ctype.h conflicts with linux/ctype.h,
+ * since isdigit() is implemented in both of them. Hence disable it
+ * here.
+ */
+#define BOOT_CTYPE_H
+
+/*
+ * _ctype[] in lib/ctype.c is needed by isspace() of linux/ctype.h.
+ * While both lib/ctype.c and lib/cmdline.c will bring EXPORT_SYMBOL
+ * which is meaningless and will cause compiling error in some cases.
+ * So do not include linux/export.h and define EXPORT_SYMBOL(sym)
+ * as empty.
+ */
+#define _LINUX_EXPORT_H
+#define EXPORT_SYMBOL(sym)
+
#include "misc.h"
#include "error.h"
-#include "../boot.h"
+#include "../string.h"
#include <generated/compile.h>
#include <linux/module.h>
#include <linux/uts.h>
#include <linux/utsname.h>
+#include <linux/ctype.h>
+#include <linux/efi.h>
#include <generated/utsrelease.h>
+#include <asm/efi.h>
+
+/* Macros used by the included decompressor code below. */
+#define STATIC
+#include <linux/decompress/mm.h>
+
+extern unsigned long get_cmd_line_ptr(void);
/* Simplified build-specific string for starting entropy. */
static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
@@ -62,6 +91,11 @@ struct mem_vector {
static bool memmap_too_large;
+
+/* Store memory limit specified by "mem=nn[KMG]" or "memmap=nn[KMG]" */
+unsigned long long mem_limit = ULLONG_MAX;
+
+
enum mem_avoid_index {
MEM_AVOID_ZO_RANGE = 0,
MEM_AVOID_INITRD,
@@ -85,49 +119,14 @@ 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 *skip_spaces(const char *str)
{
- 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;
+ while (isspace(*str))
+ ++str;
+ return (char *)str;
}
+#include "../../../../lib/ctype.c"
+#include "../../../../lib/cmdline.c"
static int
parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
@@ -142,40 +141,41 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
return -EINVAL;
oldp = p;
- *size = _memparse(p, &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);
+ *start = memparse(p + 1, &p);
+ return 0;
+ case '@':
+ /* memmap=nn@ss specifies usable region, should be skipped */
+ *size = 0;
+ /* Fall through */
+ default:
+ /*
+ * If w/o offset, only size specified, memmap=nn[KMG] has the
+ * same behaviour as mem=nn[KMG]. It limits the max address
+ * system can use. Region above the limit should be avoided.
+ */
+ *start = 0;
return 0;
}
return -EINVAL;
}
-static void mem_avoid_memmap(void)
+static void mem_avoid_memmap(char *str)
{
- char arg[128];
+ static int i;
int rc;
- int i;
- char *str;
- /* See if we have any memmap areas */
- rc = cmdline_find_option("memmap", arg, sizeof(arg));
- if (rc <= 0)
+ if (i >= MAX_MEMMAP_REGIONS)
return;
- i = 0;
- str = arg;
while (str && (i < MAX_MEMMAP_REGIONS)) {
int rc;
unsigned long long start, size;
@@ -188,9 +188,14 @@ static void mem_avoid_memmap(void)
if (rc < 0)
break;
str = k;
- /* A usable region that should not be skipped */
- if (size == 0)
+
+ if (start == 0) {
+ /* Store the specified memory limit if size > 0 */
+ if (size > 0)
+ mem_limit = size;
+
continue;
+ }
mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].start = start;
mem_avoid[MEM_AVOID_MEMMAP_BEGIN + i].size = size;
@@ -202,6 +207,57 @@ static void mem_avoid_memmap(void)
memmap_too_large = true;
}
+static int handle_mem_memmap(void)
+{
+ char *args = (char *)get_cmd_line_ptr();
+ size_t len = strlen((char *)args);
+ char *tmp_cmdline;
+ char *param, *val;
+ u64 mem_size;
+
+ if (!strstr(args, "memmap=") && !strstr(args, "mem="))
+ return 0;
+
+ tmp_cmdline = malloc(len + 1);
+ if (!tmp_cmdline )
+ error("Failed to allocate space for tmp_cmdline");
+
+ memcpy(tmp_cmdline, args, len);
+ tmp_cmdline[len] = 0;
+ args = tmp_cmdline;
+
+ /* Chew leading spaces */
+ args = skip_spaces(args);
+
+ while (*args) {
+ args = next_arg(args, &param, &val);
+ /* Stop at -- */
+ if (!val && strcmp(param, "--") == 0) {
+ warn("Only '--' specified in cmdline");
+ free(tmp_cmdline);
+ return -1;
+ }
+
+ if (!strcmp(param, "memmap")) {
+ mem_avoid_memmap(val);
+ } else if (!strcmp(param, "mem")) {
+ char *p = val;
+
+ if (!strcmp(p, "nopentium"))
+ continue;
+ mem_size = memparse(p, &p);
+ if (mem_size == 0) {
+ free(tmp_cmdline);
+ return -EINVAL;
+ }
+ mem_limit = mem_size;
+ }
+ }
+
+ free(tmp_cmdline);
+ return 0;
+}
+
/*
* 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
@@ -323,7 +379,7 @@ 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();
+ handle_mem_memmap();
#ifdef CONFIG_X86_VERBOSE_BOOTUP
/* Make sure video RAM can be used. */
@@ -426,28 +482,32 @@ static unsigned long slots_fetch_random(void)
return 0;
}
-static void process_e820_entry(struct boot_e820_entry *entry,
+static void process_mem_region(struct mem_vector *entry,
unsigned long minimum,
unsigned long image_size)
{
struct mem_vector region, overlap;
struct slot_area slot_area;
- unsigned long start_orig;
-
- /* Skip non-RAM entries. */
- if (entry->type != E820_TYPE_RAM)
- return;
+ unsigned long start_orig, end;
+ struct mem_vector cur_entry;
/* On 32-bit, ignore entries entirely above our maximum. */
- if (IS_ENABLED(CONFIG_X86_32) && entry->addr >= KERNEL_IMAGE_SIZE)
+ if (IS_ENABLED(CONFIG_X86_32) && entry->start >= KERNEL_IMAGE_SIZE)
return;
/* Ignore entries entirely below our minimum. */
- if (entry->addr + entry->size < minimum)
+ if (entry->start + entry->size < minimum)
+ return;
+
+ /* Ignore entries above memory limit */
+ end = min(entry->size + entry->start, mem_limit);
+ if (entry->start >= end)
return;
+ cur_entry.start = entry->start;
+ cur_entry.size = end - entry->start;
- region.start = entry->addr;
- region.size = entry->size;
+ region.start = cur_entry.start;
+ region.size = cur_entry.size;
/* Give up if slot area array is full. */
while (slot_area_index < MAX_SLOT_AREA) {
@@ -460,8 +520,8 @@ static void process_e820_entry(struct boot_e820_entry *entry,
/* Potentially raise address to meet alignment needs. */
region.start = ALIGN(region.start, CONFIG_PHYSICAL_ALIGN);
- /* Did we raise the address above this e820 region? */
- if (region.start > entry->addr + entry->size)
+ /* Did we raise the address above the passed in memory entry? */
+ if (region.start > cur_entry.start + cur_entry.size)
return;
/* Reduce size by any delta from the original address. */
@@ -501,31 +561,126 @@ static void process_e820_entry(struct boot_e820_entry *entry,
}
}
-static unsigned long find_random_phys_addr(unsigned long minimum,
- unsigned long image_size)
+#ifdef CONFIG_EFI
+/*
+ * Returns true if mirror region found (and must have been processed
+ * for slots adding)
+ */
+static bool
+process_efi_entries(unsigned long minimum, unsigned long image_size)
{
+ struct efi_info *e = &boot_params->efi_info;
+ bool efi_mirror_found = false;
+ struct mem_vector region;
+ efi_memory_desc_t *md;
+ unsigned long pmap;
+ char *signature;
+ u32 nr_desc;
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;
+ signature = (char *)&e->efi_loader_signature;
+ if (strncmp(signature, EFI32_LOADER_SIGNATURE, 4) &&
+ strncmp(signature, EFI64_LOADER_SIGNATURE, 4))
+ return false;
+
+#ifdef CONFIG_X86_32
+ /* Can't handle data above 4GB at this time */
+ if (e->efi_memmap_hi) {
+ warn("EFI memmap is above 4GB, can't be handled now on x86_32. EFI should be disabled.\n");
+ return false;
}
+ pmap = e->efi_memmap;
+#else
+ pmap = (e->efi_memmap | ((__u64)e->efi_memmap_hi << 32));
+#endif
- /* Make sure minimum is aligned. */
- minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
+ nr_desc = e->efi_memmap_size / e->efi_memdesc_size;
+ for (i = 0; i < nr_desc; i++) {
+ md = efi_early_memdesc_ptr(pmap, e->efi_memdesc_size, i);
+ if (md->attribute & EFI_MEMORY_MORE_RELIABLE) {
+ efi_mirror_found = true;
+ break;
+ }
+ }
+
+ for (i = 0; i < nr_desc; i++) {
+ md = efi_early_memdesc_ptr(pmap, e->efi_memdesc_size, i);
+
+ /*
+ * Here we are more conservative in picking free memory than
+ * the EFI spec allows:
+ *
+ * According to the spec, EFI_BOOT_SERVICES_{CODE|DATA} are also
+ * free memory and thus available to place the kernel image into,
+ * but in practice there's firmware where using that memory leads
+ * to crashes.
+ *
+ * Only EFI_CONVENTIONAL_MEMORY is guaranteed to be free.
+ */
+ if (md->type != EFI_CONVENTIONAL_MEMORY)
+ continue;
+
+ if (efi_mirror_found &&
+ !(md->attribute & EFI_MEMORY_MORE_RELIABLE))
+ continue;
+
+ 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");
+ break;
+ }
+ }
+ return true;
+}
+#else
+static inline bool
+process_efi_entries(unsigned long minimum, unsigned long image_size)
+{
+ return false;
+}
+#endif
+
+static void process_e820_entries(unsigned long minimum,
+ unsigned long image_size)
+{
+ int i;
+ struct mem_vector region;
+ struct boot_e820_entry *entry;
/* Verify potential e820 positions, appending to slots list. */
for (i = 0; i < boot_params->e820_entries; i++) {
- process_e820_entry(&boot_params->e820_table[i], minimum,
- image_size);
+ entry = &boot_params->e820_table[i];
+ /* Skip non-RAM entries. */
+ if (entry->type != E820_TYPE_RAM)
+ 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");
break;
}
}
+}
+
+static unsigned long find_random_phys_addr(unsigned long minimum,
+ unsigned long image_size)
+{
+ /* Check if we had too many memmaps. */
+ if (memmap_too_large) {
+ debug_putstr("Aborted memory entries scan (more than 4 memmap= args)!\n");
+ return 0;
+ }
+
+ /* Make sure minimum is aligned. */
+ minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN);
+
+ if (process_efi_entries(minimum, image_size))
+ return slots_fetch_random();
+ process_e820_entries(minimum, image_size);
return slots_fetch_random();
}
@@ -584,7 +739,7 @@ void choose_random_location(unsigned long input,
*/
min_addr = min(*output, 512UL << 20);
- /* Walk e820 and find a random address. */
+ /* Walk available memory entries to find a random address. */
random_addr = find_random_phys_addr(min_addr, output_size);
if (!random_addr) {
warn("Physical KASLR disabled: no suitable memory region!");
generated by cgit (git 2.34.1) at 2025-04-24 08:12:02 +0000