[PATCH v4 1/3] KASLR: Parse all memmap entries in cmdline
From: Baoquan He
Date: Tue May 09 2017 - 01:58:41 EST
In commit:
f28442497b5c ("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.
In this patch, the whole cmdline will be scanned to search each
memmap, all of them will be parsed and handled.
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
arch/x86/boot/compressed/cmdline.c | 2 +-
arch/x86/boot/compressed/kaslr.c | 136 ++++++++++++++++++++++---------------
arch/x86/boot/string.c | 8 +++
3 files changed, 91 insertions(+), 55 deletions(-)
diff --git a/arch/x86/boot/compressed/cmdline.c b/arch/x86/boot/compressed/cmdline.c
index 73ccf63..9dc1ce6 100644
--- a/arch/x86/boot/compressed/cmdline.c
+++ b/arch/x86/boot/compressed/cmdline.c
@@ -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;
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 54c24f0..106e13b 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -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, ¶m, &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. */
diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
index 5457b02..630e366 100644
--- a/arch/x86/boot/string.c
+++ b/arch/x86/boot/string.c
@@ -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
--
2.5.5