makedumpfile: Add support of mm randomization

PATCH In review Baoquan He 1 participant 5 messages Oct 6, 2016

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Baoquan He

author

2016-10-06 09:50 UTC #0 lore raw

v2 cover makedumpfile: Add support of mm randomization

This is v2 post.

Because of Thomas's kernel patchset, direct mapping, vmalloc and vmemmap could have random starting address. They need be exported to VMCOREINFO and let makedumpfile know this so that makedumpfile can identify these memory areas correctly.

Below is the kernel patchset from Thomas:
x86/mm: memory area address KASLR
https://lwn.net/Articles/692289/

I have posted a new kernel patchset to export the base of direct mapping, vmalloc and vmemmap. The subject is:
kexec: Export memory sections virtual addresses to vmcoreinfo

v1->v2:
According to Atsushi's comment, mainly change patch 3/3.
- Remove VMALLOC_END_ORIG, VMEMMAP_END_ORIG , VMALLOC_END_2_6_31 and VMEMMAP_END_2_6_31 since they are not needed anymore.
- Put those number table member value assignment into get_versiondep_info_x86_64.

Baoquan He (3):
makedumpfile: Get info->kernel_version from SYMBOL(init_uts_ns)
earlier
makedumpfile: Move get_versiondep_info calling earlier
makedumpfile: Add support for MM randomization

 arch/x86_64.c  | 51 ++++++++++++++++++++++++++++++++++-----------------
 makedumpfile.c | 33 ++++++++++++++++-----------------
 makedumpfile.h |  7 +++----
 3 files changed, 53 insertions(+), 38 deletions(-)

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Baoquan He

author

2016-10-06 09:50 UTC #1 lore raw

PATCH v2 1/3 makedumpfile: Get info->kernel_version from SYMBOL(init_uts_ns) earlier

The current code assign value to info->kernel_version in check_release, this is too late and buggy. Because in check_release(), it needs calling readmem, however earlier get_value_for_old_linux depends on info->kernel_version to get correct KERNEL_IMAGE_SIZE for MODULES_VADDR which is used in is_vmalloc_addr_x86_64(). This looks a weird circle.

Since we have exported "OSRELEASE=%s\n" explicitly in kernel, we should always use it to get kernel version. And this breaks above weird circle. Otherwise MM randomization will come and make it worse.

Signed-off-by Baoquan He <[email protected]>

---
 makedumpfile.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

makedumpfile.c +6 -6

index d168dfd..89e1089 100644
@@ -1139,12 +1139,6 @@ check_release(void)
 		}
 	}
 
-	info->kernel_version = get_kernel_version(info->system_utsname.release);
-	if (info->kernel_version == FALSE) {
-		ERRMSG("Can't get the kernel version.\n");
-		return FALSE;
-	}
-
 	return TRUE;
 }

@@ -3832,6 +3826,12 @@ initial(void)
 		debug_info = TRUE;
 	}
 
+	info->kernel_version = get_kernel_version(info->release);
+	if (info->kernel_version == FALSE) {
+		ERRMSG("Can't get the kernel version.\n");
+		return FALSE;
+	}
+
 	if (!get_value_for_old_linux())
 		return FALSE;

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Baoquan He

author

2016-10-06 09:50 UTC #2 lore raw

PATCH v2 2/3 makedumpfile: Move get_versiondep_info calling earlier

In reply to Baoquan He

Because is_vmalloc_addr_x86_64 need be called very early, e.g in readmem(). So we have to move get_versiondep_info calling earlier to let PAGE_OFFSET/VMALLOC_START/VMEMMAP_START get value before use them.

Signed-off-by Baoquan He <[email protected]>

---
 makedumpfile.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

makedumpfile.c +3 -3

index 89e1089..e132550 100644
@@ -3835,6 +3835,9 @@ initial(void)
 	if (!get_value_for_old_linux())
 		return FALSE;
 
+	if (!get_versiondep_info())
+		return FALSE;
+
 	if (info->flag_mem_usage && !get_kcore_dump_loads())
 		return FALSE;

@@ -3986,9 +3989,6 @@ out:
 		if (!check_release())
 			return FALSE;
 
-		if (!get_versiondep_info())
-			return FALSE;
-
 		/*
 		 * NOTE: This must be done before refering to
 		 * VMALLOC'ed memory. The first 640kB contains data

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Baoquan He

author

2016-10-06 09:50 UTC #3 lore raw

PATCH v2 3/3 makedumpfile: Add support for MM randomization

In reply to Baoquan He

In kernel patchset "x86/mm: memory area address KASLR", PAGE_OFFSET, VMALLOC_START and VMEMMAP_START are all randomized. Please check below link:

	https://lwn.net/Articles/692289/

And these need be exported into vmcoreinfo and tell makedumpfile. In this patch get and handle them to support MM randomization.

Signed-off-by Baoquan He <[email protected]>

---
 arch/x86_64.c  | 51 ++++++++++++++++++++++++++++++++++-----------------
 makedumpfile.c | 15 +++++++--------
 makedumpfile.h |  7 +++----
 3 files changed, 44 insertions(+), 29 deletions(-)

arch/x86_64.c +34 ~~-17~~

index ddf7be6..1fd193f 100644
@@ -146,8 +146,9 @@ get_machdep_info_x86_64(void)
 	return TRUE;
 }
 
-int
-get_versiondep_info_x86_64(void)
+#define VMALLOC_SIZE            (0x200000000000)
+#define VMEMMAP_SIZE            (0x10000000000)
+int get_versiondep_info_x86_64(void)
 {
 	/*
 	 * On linux-2.6.26, MAX_PHYSMEM_BITS is changed to 44 from 40.

@@ -159,22 +160,38 @@ get_versiondep_info_x86_64(void)
 	else
 		info->max_physmem_bits  = _MAX_PHYSMEM_BITS_2_6_31;
 
-	if (info->kernel_version < KERNEL_VERSION(2, 6, 27))
-		info->page_offset = __PAGE_OFFSET_ORIG;
-	else
-		info->page_offset = __PAGE_OFFSET_2_6_27;
-
-	if (info->kernel_version < KERNEL_VERSION(2, 6, 31)) {
-		info->vmalloc_start = VMALLOC_START_ORIG;
-		info->vmalloc_end   = VMALLOC_END_ORIG;
-		info->vmemmap_start = VMEMMAP_START_ORIG;
-		info->vmemmap_end   = VMEMMAP_END_ORIG;
-	} else {
-		info->vmalloc_start = VMALLOC_START_2_6_31;
-		info->vmalloc_end   = VMALLOC_END_2_6_31;
-		info->vmemmap_start = VMEMMAP_START_2_6_31;
-		info->vmemmap_end   = VMEMMAP_END_2_6_31;
+	if (NUMBER(KERNEL_IMAGE_SIZE) == NOT_FOUND_NUMBER) {
+		if (info->kernel_version < KERNEL_VERSION(2, 6, 26))
+			NUMBER(KERNEL_IMAGE_SIZE) = KERNEL_IMAGE_SIZE_ORIG;
+		else
+			NUMBER(KERNEL_IMAGE_SIZE) = KERNEL_IMAGE_SIZE_2_6_26;
+	}
+	if (NUMBER(page_offset) == NOT_FOUND_NUMBER) {
+		if (info->kernel_version < KERNEL_VERSION(2, 6, 27))
+			NUMBER(page_offset) = __PAGE_OFFSET_ORIG;
+		else
+			NUMBER(page_offset) = __PAGE_OFFSET_2_6_27;
 	}
+	if (NUMBER(vmalloc_start) == NOT_FOUND_NUMBER) {
+		if (info->kernel_version < KERNEL_VERSION(2, 6, 31)) {
+			NUMBER(vmalloc_start) = VMALLOC_START_ORIG;
+		} else {
+			NUMBER(vmalloc_start) = VMALLOC_START_2_6_31;
+		}
+	}
+	if (NUMBER(vmemmap_start) == NOT_FOUND_NUMBER) {
+		if (info->kernel_version < KERNEL_VERSION(2, 6, 31))
+			NUMBER(vmemmap_start) = VMEMMAP_START_ORIG;
+		else
+			NUMBER(vmemmap_start) = VMEMMAP_START_2_6_31;
+	}
+
+	info->page_offset = NUMBER(page_offset);
+
+	info->vmalloc_start = NUMBER(vmalloc_start);
+	info->vmalloc_end   = info->vmalloc_start + VMALLOC_SIZE - 1;
+	info->vmemmap_start = NUMBER(vmemmap_start);
+	info->vmemmap_end   = info->vmemmap_start + VMEMMAP_SIZE - 1;
 
 	return TRUE;
 }

makedumpfile.c +7 -8

index e132550..bf990f1 100644
@@ -1985,14 +1985,7 @@ get_value_for_old_linux(void)
 			NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE) =
 			PAGE_BUDDY_MAPCOUNT_VALUE_v2_6_39_to_latest_version;
 	}
-#ifdef __x86_64__
-	if (NUMBER(KERNEL_IMAGE_SIZE) == NOT_FOUND_NUMBER) {
-		if (info->kernel_version < KERNEL_VERSION(2, 6, 26))
-			NUMBER(KERNEL_IMAGE_SIZE) = KERNEL_IMAGE_SIZE_ORIG;
-		else
-			NUMBER(KERNEL_IMAGE_SIZE) = KERNEL_IMAGE_SIZE_2_6_26;
-	}
-#endif
+
 	if (SIZE(pageflags) == NOT_FOUND_STRUCTURE) {
 		if (info->kernel_version >= KERNEL_VERSION(2, 6, 27))
 			SIZE(pageflags) =

@@ -2249,6 +2242,9 @@ write_vmcoreinfo_data(void)
 
 	WRITE_NUMBER("PAGE_BUDDY_MAPCOUNT_VALUE", PAGE_BUDDY_MAPCOUNT_VALUE);
 	WRITE_NUMBER("KERNEL_IMAGE_SIZE", KERNEL_IMAGE_SIZE);
+	WRITE_NUMBER("PAGE_OFFSET", page_offset);
+	WRITE_NUMBER("VMALLOC_START", vmalloc_start);
+	WRITE_NUMBER("VMEMMAP_START", vmemmap_start);
 
 	WRITE_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR);

@@ -2595,6 +2591,9 @@ read_vmcoreinfo(void)
 
 	READ_NUMBER("PAGE_BUDDY_MAPCOUNT_VALUE", PAGE_BUDDY_MAPCOUNT_VALUE);
 	READ_NUMBER("KERNEL_IMAGE_SIZE", KERNEL_IMAGE_SIZE);
+	READ_NUMBER("PAGE_OFFSET", page_offset);
+	READ_NUMBER("VMALLOC_START", vmalloc_start);
+	READ_NUMBER("VMEMMAP_START", vmemmap_start);
 
 	READ_NUMBER("HUGETLB_PAGE_DTOR", HUGETLB_PAGE_DTOR);

makedumpfile.h +3 -4

index 1814139..17f71a3 100644
@@ -564,13 +564,9 @@ int get_va_bits_arm64(void);
 
 #define VMALLOC_START_ORIG	(0xffffc20000000000) /* 2.6.30, or former */
 #define VMALLOC_START_2_6_31	(0xffffc90000000000) /* 2.6.31, or later  */
-#define VMALLOC_END_ORIG	(0xffffe1ffffffffff) /* 2.6.30, or former */
-#define VMALLOC_END_2_6_31	(0xffffe8ffffffffff) /* 2.6.31, or later  */
 
 #define VMEMMAP_START_ORIG	(0xffffe20000000000) /* 2.6.30, or former */
 #define VMEMMAP_START_2_6_31	(0xffffea0000000000) /* 2.6.31, or later  */
-#define VMEMMAP_END_ORIG	(0xffffe2ffffffffff) /* 2.6.30, or former */
-#define VMEMMAP_END_2_6_31	(0xffffeaffffffffff) /* 2.6.31, or later  */
 
 #define __START_KERNEL_map	(0xffffffff80000000)
 #define KERNEL_IMAGE_SIZE_ORIG		(0x0000000008000000) /* 2.6.25, or former */

@@ -1685,6 +1681,9 @@ struct number_table {
 
 	long	PAGE_BUDDY_MAPCOUNT_VALUE;
 	long	KERNEL_IMAGE_SIZE;
+	long	page_offset;
+	long	vmalloc_start;
+	long	vmemmap_start;
 	long	SECTION_SIZE_BITS;
 	long	MAX_PHYSMEM_BITS;
 	long    HUGETLB_PAGE_DTOR;

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Baoquan He

author

2016-10-06 10:24 UTC #4 lore raw

In reply to Baoquan He

Oops, I just sent to Atsushi's old mail. Sorry about this!

Quoted 28 lines · Baoquan He

This is v2 post.
Because of Thomas's kernel patchset, direct mapping, vmalloc and vmemmap could have random starting address. They need be exported to VMCOREINFO and let makedumpfile know this so that makedumpfile can identify these memory areas correctly.
Below is the kernel patchset from Thomas:
x86/mm: memory area address KASLR
https://lwn.net/Articles/692289/
I have posted a new kernel patchset to export the base of direct mapping, vmalloc and vmemmap. The subject is:
kexec: Export memory sections virtual addresses to vmcoreinfo
v1->v2:
According to Atsushi's comment, mainly change patch 3/3.
- Remove VMALLOC_END_ORIG, VMEMMAP_END_ORIG , VMALLOC_END_2_6_31 and VMEMMAP_END_2_6_31 since they are not needed anymore.
- Put those number table member value assignment into get_versiondep_info_x86_64.
Baoquan He (3):
makedumpfile: Get info->kernel_version from SYMBOL(init_uts_ns)
earlier
makedumpfile: Move get_versiondep_info calling earlier
makedumpfile: Add support for MM randomization

Quoted 8 lines

 arch/x86_64.c  | 51 ++++++++++++++++++++++++++++++++++-----------------
 makedumpfile.c | 33 ++++++++++++++++-----------------
 makedumpfile.h |  7 +++----
 3 files changed, 53 insertions(+), 38 deletions(-)

Signature · 1 line

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