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Commit d52e7d5a authored by Baoquan He's avatar Baoquan He Committed by Ingo Molnar
Browse files

x86/KASLR: Parse all 'memmap=' boot option entries 



In commit:

  f2844249 ("x86/boot: Fix KASLR and memmap= collision")

... the memmap= option is parsed so that KASLR can avoid those reserved
regions. It uses cmdline_find_option() to get the value if memmap=
is specified, however the problem is that cmdline_find_option() can only
find the last entry if multiple memmap entries are provided. This
is not correct.

Address this by checking each command line token for a "memmap=" match
and parse each instance instead of using cmdline_find_option().

Signed-off-by: default avatarBaoquan He <bhe@redhat.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dan.j.williams@intel.com
Cc: douly.fnst@cn.fujitsu.com
Cc: dyoung@redhat.com
Cc: m.mizuma@jp.fujitsu.com
Link: http://lkml.kernel.org/r/1494654390-23861-2-git-send-email-bhe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 56fff1bb

arch/x86/boot/compressed/cmdline.c

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ static inline char rdfs8(addr_t addr) 
	return *((char *)(fs + addr));

}

#include "../cmdline.c"

static unsigned long get_cmd_line_ptr(void)

unsigned long get_cmd_line_ptr(void)

{

	unsigned long cmd_line_ptr = boot_params->hdr.cmd_line_ptr;

arch/x86/boot/compressed/kaslr.c

+82 −54
Original line number Diff line number Diff line
@@ -9,16 +9,41 @@ 
 * 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 <generated/compile.h>

#include <linux/module.h>

#include <linux/uts.h>

#include <linux/utsname.h>

#include <linux/ctype.h>

#include <generated/utsrelease.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 "@"

		LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
@@ -62,6 +87,7 @@ struct mem_vector { 


static bool memmap_too_large;





enum mem_avoid_index {

	MEM_AVOID_ZO_RANGE = 0,

	MEM_AVOID_INITRD,
@@ -85,49 +111,14 @@ 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)
@@ -142,7 +133,7 @@ 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;
@@ -155,27 +146,21 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size) 
	case '#':

	case '$':

	case '!':

		*start = _memparse(p + 1, &p);

		*start = memparse(p + 1, &p);

		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;
@@ -202,6 +187,49 @@ static void mem_avoid_memmap(void) 
		memmap_too_large = true;

}





/*

 * handle_mem_memmap will also cover 'mem=' issue in next patch. Will remove

 * this note later.

 */

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;



	if (!strstr(args, "memmap="))

		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);

	}



	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 +351,7 @@ 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. */

arch/x86/boot/string.c

+8 −0
Original line number Diff line number Diff line
@@ -122,6 +122,14 @@ unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int bas 
	return result;

}



long simple_strtol(const char *cp, char **endp, unsigned int base)

{

	if (*cp == '-')

		return -simple_strtoull(cp + 1, endp, base);



	return simple_strtoull(cp, endp, base);

}



/**

 * strlen - Find the length of a string

 * @s: The string to be sized