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Subject[PATCH v5 1/3] KASLR: Parse all memmap entries in command line
Date
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.

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: Baoquan He <bhe@redhat.com>
---
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, &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. */
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
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