Fix refiltering when kaslr enabled

If we have to erase a symbol from vmcore whose address is not present in vmcoreinfo, then we need to pass vmlinux as well to get the symbol address.
When kaslr is enabled, virtual address of all the kernel symbols are randomized with an offset. vmlinux always has a static address, but all the arch specific calculation are based on run time kernel address. So we need to find a way to translate symbol address from vmlinux to kernel run time address.

without this patch:

  # cat > scrub.conf << EOF
  [vmlinux]
  erase jiffies
  erase init_task.utime
  for tsk in init_task.tasks.next within task_struct:tasks
      erase tsk.utime
  endfor
  EOF

   # makedumpfile --split  -d 5 -x vmlinux --config scrub.conf vmcore dumpfile_{1,2,3}

readpage_kdump_compressed: pfn(f97ea) is excluded from vmcore.
readmem: type_addr: 1, addr:f97eaff8, size:8
vtop4_x86_64: Can't get pml4 (page_dir:f97eaff8).
readmem: Can't convert a virtual address(ffffffff819f1284) to physical address.
readmem: type_addr: 0, addr:ffffffff819f1284, size:390
check_release: Can't get the address of system_utsname.

After this patch check_release() is ok, and also we are able to erase symbol from vmcore.

Signed-off-by Pratyush Anand <[email protected]>

---

arch/x86_64.c  | 36 ++++++++++++++++++++++++++++++++++++
erase_info.c   |  1 +
makedumpfile.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
makedumpfile.h | 16 ++++++++++++++++
4 files changed, 106 insertions(+)

arch/x86_64.c +36 -0

index e978a36f8878..fd2e8ac154d6 100644
@@ -33,6 +33,42 @@ get_xen_p2m_mfn(void)
 	return NOT_FOUND_LONG_VALUE;
 }
 
+unsigned long
+get_kaslr_offset_x86_64(unsigned long vaddr)
+{
+	unsigned int i;
+	char buf[BUFSIZE_FGETS], *endp;
+
+	if (!info->kaslr_offset && info->file_vmcoreinfo) {
+		if (fseek(info->file_vmcoreinfo, 0, SEEK_SET) < 0) {
+			ERRMSG("Can't seek the vmcoreinfo file(%s). %s\n",
+					info->name_vmcoreinfo, strerror(errno));
+			return FALSE;
+		}
+
+		while (fgets(buf, BUFSIZE_FGETS, info->file_vmcoreinfo)) {
+			i = strlen(buf);
+			if (!i)
+				break;
+			if (buf[i - 1] == '\n')
+				buf[i - 1] = '\0';
+			if (strncmp(buf, STR_KERNELOFFSET,
+					strlen(STR_KERNELOFFSET)) == 0)
+				info->kaslr_offset =
+					strtoul(buf+strlen(STR_KERNELOFFSET),&endp,16);
+		}
+	}
+	if (vaddr >= __START_KERNEL_map &&
+			vaddr < __START_KERNEL_map + info->kaslr_offset)
+		return info->kaslr_offset;
+	else
+		/*
+		 * TODO: we need to check if it is vmalloc/vmmemmap/module
+		 * address, we will have different offset
+		 */
+		return 0;
+}
+

static int
get_page_offset_x86_64(void)
{

erase_info.c +1 -0

index f2ba9149e93e..60abfa1a1adf 100644
@@ -1088,6 +1088,7 @@ resolve_config_entry(struct config_entry *ce, unsigned long long base_vaddr,
 							ce->line, ce->name);
 			return FALSE;
 		}
+		ce->sym_addr += get_kaslr_offset(ce->sym_addr);
 		ce->type_name = get_symbol_type_name(ce->name,
 					DWARF_INFO_GET_SYMBOL_TYPE,
 					&ce->size, &ce->type_flag);

makedumpfile.c +0 -0

index 301772a8820c..4986d098d69a 100644

makedumpfile.c +1 -0

+	/*
 	 * write 1st kernel's OSRELEASE
 	 */
 	fprintf(info->file_vmcoreinfo, "%s%s\n", STR_OSRELEASE,

@@ -3782,6 +3789,46 @@ free_for_parallel()
 }
 

int

makedumpfile.c +40 -0

+find_kaslr_offsets()
+{
+	off_t offset;
+	unsigned long size;
+	int ret = FALSE;
+
+	get_vmcoreinfo(&offset, &size);
+
+	if (!(info->name_vmcoreinfo = strdup(FILENAME_VMCOREINFO))) {
+		MSG("Can't duplicate strings(%s).\n", FILENAME_VMCOREINFO);
+		return FALSE;
+	}
+	if (!copy_vmcoreinfo(offset, size))
+		goto out;
+
+	if (!open_vmcoreinfo("r"))
+		goto out;
+
+	unlink(info->name_vmcoreinfo);
+
+	/*
+	 * This arch specific function should update info->kaslr_offset. If
+	 * kaslr is not enabled then offset will be set to 0. arch specific
+	 * function might need to read from vmcoreinfo, therefore we have
+	 * called this function between open_vmcoreinfo() and
+	 * close_vmcoreinfo()
+	 */
+	get_kaslr_offset(SYMBOL(_stext));
+
+	close_vmcoreinfo();
+
+	ret = TRUE;
+out:
+	free(info->name_vmcoreinfo);
+	info->name_vmcoreinfo = NULL;
+
+	return ret;
+}
+
+int

initial(void)

{
	off_t offset;

makedumpfile.c +3 -0

@@ -3833,6 +3880,9 @@ initial(void)
 		set_dwarf_debuginfo("vmlinux", NULL,
 					info->name_vmlinux, info->fd_vmlinux);
 
+		if (has_vmcoreinfo() && !find_kaslr_offsets())
+			return FALSE;
+
 
 
 

		if (!get_symbol_info())
			return FALSE;

makedumpfile.c +1 -0

@@ -8635,6 +8685,7 @@ close_vmcoreinfo(void)
 	if(fclose(info->file_vmcoreinfo) < 0)
 		ERRMSG("Can't close the vmcoreinfo file(%s). %s\n",
 		    info->name_vmcoreinfo, strerror(errno));
+	info->file_vmcoreinfo = NULL;
 }
 

void

makedumpfile.c +2 -0

@@ -11026,11 +11077,13 @@ main(int argc, char *argv[])
 		    strerror(errno));
 		goto out;
 	}
+	info->file_vmcoreinfo = NULL;
 	info->fd_vmlinux = -1;
 	info->fd_xen_syms = -1;
 	info->fd_memory = -1;
 	info->fd_dumpfile = -1;
 	info->fd_bitmap = -1;
+	info->kaslr_offset = 0;
 	initialize_tables();
 
 	/*

makedumpfile.h +16 -1

index e32e567018f6..9f16becadd55 100644
@@ -253,10 +253,14 @@ static inline int string_exists(char *s) { return (s ? TRUE : FALSE); }
 #define SYMBOL_INIT(symbol, str_symbol) \
 do { \
 	SYMBOL(symbol) = get_symbol_addr(str_symbol); \
+	if (SYMBOL(symbol) != NOT_FOUND_SYMBOL) \
+		SYMBOL(symbol) += info->kaslr_offset; \
 } while (0)
 #define SYMBOL_INIT_NEXT(symbol, str_symbol) \
 do { \
 	SYMBOL(symbol) = get_next_symbol_addr(str_symbol); \
+	if (SYMBOL(symbol) != NOT_FOUND_SYMBOL) \
+		SYMBOL(symbol) += info->kaslr_offset; \
 } while (0)
 #define WRITE_SYMBOL(str_symbol, symbol) \
 do { \

@@ -495,6 +499,7 @@ do { \
 #define STR_CONFIG_X86_PAE	"CONFIG_X86_PAE=y"
 #define STR_CONFIG_PGTABLE_4	"CONFIG_PGTABLE_4=y"
 #define STR_CONFIG_PGTABLE_3	"CONFIG_PGTABLE_3=y"
+#define STR_KERNELOFFSET	"KERNELOFFSET="
 
 /*
 * common value

@@ -838,6 +843,7 @@ int get_xen_info_arm64(void);
 #define get_phys_base()		get_phys_base_arm64()
 #define get_machdep_info()	get_machdep_info_arm64()
 #define get_versiondep_info()	get_versiondep_info_arm64()
+#define get_kaslr_offset(X)	FALSE
 #define get_xen_basic_info_arch(X) get_xen_basic_info_arm64(X)
 #define get_xen_info_arch(X) get_xen_info_arm64(X)
 #define is_phys_addr(X)		stub_true_ul(X)

@@ -851,6 +857,7 @@ unsigned long long vaddr_to_paddr_arm(unsigned long vaddr);
 #define get_phys_base()		get_phys_base_arm()
 #define get_machdep_info()	get_machdep_info_arm()
 #define get_versiondep_info()	stub_true()
+#define get_kaslr_offset(X)	FALSE
 #define vaddr_to_paddr(X)	vaddr_to_paddr_arm(X)
 #define is_phys_addr(X)		stub_true_ul(X)
 #endif /* arm */

@@ -863,11 +870,13 @@ unsigned long long vaddr_to_paddr_x86(unsigned long vaddr);
 #define get_phys_base()		stub_true()
 #define get_machdep_info()	get_machdep_info_x86()
 #define get_versiondep_info()	get_versiondep_info_x86()
+#define get_kaslr_offset(X)	FALSE
 #define vaddr_to_paddr(X)	vaddr_to_paddr_x86(X)
 #define is_phys_addr(X)		stub_true_ul(X)
 #endif /* x86 */
 
 #ifdef __x86_64__
+unsigned long get_kaslr_offset_x86_64(unsigned long vaddr);
 int get_phys_base_x86_64(void);
 int get_machdep_info_x86_64(void);
 int get_versiondep_info_x86_64(void);

@@ -876,6 +885,7 @@ unsigned long long vtop4_x86_64(unsigned long vaddr);
 #define get_phys_base()		get_phys_base_x86_64()
 #define get_machdep_info()	get_machdep_info_x86_64()
 #define get_versiondep_info()	get_versiondep_info_x86_64()
+#define get_kaslr_offset(X)	get_kaslr_offset_x86_64(X)
 #define vaddr_to_paddr(X)	vtop4_x86_64(X)
 #define is_phys_addr(X)		stub_true_ul(X)
 #endif /* x86_64 */

@@ -888,6 +898,7 @@ unsigned long long vaddr_to_paddr_ppc64(unsigned long vaddr);
 #define get_phys_base()		stub_true()
 #define get_machdep_info()	get_machdep_info_ppc64()
 #define get_versiondep_info()	get_versiondep_info_ppc64()
+#define get_kaslr_offset(X)	FALSE
 #define vaddr_to_paddr(X)	vaddr_to_paddr_ppc64(X)
 #define is_phys_addr(X)		stub_true_ul(X)
 #endif          /* powerpc64 */

@@ -899,6 +910,7 @@ unsigned long long vaddr_to_paddr_ppc(unsigned long vaddr);
 #define get_phys_base()		stub_true()
 #define get_machdep_info()	get_machdep_info_ppc()
 #define get_versiondep_info()	stub_true()
+#define get_kaslr_offset(X)	FALSE
 #define vaddr_to_paddr(X)	vaddr_to_paddr_ppc(X)
 #define is_phys_addr(X)		stub_true_ul(X)
 #endif          /* powerpc32 */

@@ -911,6 +923,7 @@ int is_iomem_phys_addr_s390x(unsigned long addr);
 #define get_phys_base()		stub_true()
 #define get_machdep_info()	get_machdep_info_s390x()
 #define get_versiondep_info()	stub_true()
+#define get_kaslr_offset(X)	FALSE
 #define vaddr_to_paddr(X)	vaddr_to_paddr_s390x(X)
 #define is_phys_addr(X)		is_iomem_phys_addr_s390x(X)
 #endif          /* s390x */

@@ -923,6 +936,7 @@ unsigned long long vaddr_to_paddr_ia64(unsigned long vaddr);
 #define get_machdep_info()	get_machdep_info_ia64()
 #define get_phys_base()		get_phys_base_ia64()
 #define get_versiondep_info()	stub_true()
+#define get_kaslr_offset(X)	FALSE
 #define vaddr_to_paddr(X)	vaddr_to_paddr_ia64(X)
 #define VADDR_REGION(X)		(((unsigned long)(X)) >> REGION_SHIFT)
 #define is_phys_addr(X)		stub_true_ul(X)

@@ -1152,6 +1166,7 @@ struct DumpInfo {
 	int		vmemmap_psize;
 	int		vmemmap_cnt;
 	struct ppc64_vmemmap	*vmemmap_list;
+	unsigned long	kaslr_offset;
 
 	/*
 	 * page table info for ppc64

@@ -1803,6 +1818,7 @@ struct memory_range {
 struct memory_range crash_reserved_mem[CRASH_RESERVED_MEM_NR];
 int crash_reserved_mem_nr;
 
+unsigned long read_vmcoreinfo_symbol(char *str_symbol);
 int readmem(int type_addr, unsigned long long addr, void *bufptr, size_t size);
 int get_str_osrelease_from_vmlinux(void);
 int read_vmcoreinfo_xen(void);
--

2.9.3

Hello Pratyush,

Quoted 106 lines

If we have to erase a symbol from vmcore whose address is not present in vmcoreinfo, then we need to pass vmlinux as well to get the symbol address.
When kaslr is enabled, virtual address of all the kernel symbols are randomized with an offset. vmlinux always has a static address, but all the arch specific calculation are based on run time kernel address. So we need to find a way to translate symbol address from vmlinux to kernel run time address.

without this patch:

  # cat > scrub.conf << EOF
  [vmlinux]
  erase jiffies
  erase init_task.utime
  for tsk in init_task.tasks.next within task_struct:tasks
      erase tsk.utime
  endfor
  EOF

   # makedumpfile --split  -d 5 -x vmlinux --config scrub.conf vmcore dumpfile_{1,2,3}

readpage_kdump_compressed: pfn(f97ea) is excluded from vmcore.
readmem: type_addr: 1, addr:f97eaff8, size:8
vtop4_x86_64: Can't get pml4 (page_dir:f97eaff8).
readmem: Can't convert a virtual address(ffffffff819f1284) to physical address.
readmem: type_addr: 0, addr:ffffffff819f1284, size:390
check_release: Can't get the address of system_utsname.

After this patch check_release() is ok, and also we are able to erase symbol from vmcore.

Signed-off-by Pratyush Anand <[email protected]>

---

arch/x86_64.c  | 36 ++++++++++++++++++++++++++++++++++++
erase_info.c   |  1 +
makedumpfile.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
makedumpfile.h | 16 ++++++++++++++++
4 files changed, 106 insertions(+)

arch/x86_64.c +36 -0

index e978a36f8878..fd2e8ac154d6 100644
@@ -33,6 +33,42 @@ get_xen_p2m_mfn(void)
 	return NOT_FOUND_LONG_VALUE;
 }
 
+unsigned long
+get_kaslr_offset_x86_64(unsigned long vaddr)
+{
+	unsigned int i;
+	char buf[BUFSIZE_FGETS], *endp;
+
+	if (!info->kaslr_offset && info->file_vmcoreinfo) {
+		if (fseek(info->file_vmcoreinfo, 0, SEEK_SET) < 0) {
+			ERRMSG("Can't seek the vmcoreinfo file(%s). %s\n",
+					info->name_vmcoreinfo, strerror(errno));
+			return FALSE;
+		}
+
+		while (fgets(buf, BUFSIZE_FGETS, info->file_vmcoreinfo)) {
+			i = strlen(buf);
+			if (!i)
+				break;
+			if (buf[i - 1] == '\n')
+				buf[i - 1] = '\0';
+			if (strncmp(buf, STR_KERNELOFFSET,
+					strlen(STR_KERNELOFFSET)) == 0)
+				info->kaslr_offset =
+					strtoul(buf+strlen(STR_KERNELOFFSET),&endp,16);
+		}
+	}
+	if (vaddr >= __START_KERNEL_map &&
+			vaddr < __START_KERNEL_map + info->kaslr_offset)
+		return info->kaslr_offset;
+	else
+		/*
+		 * TODO: we need to check if it is vmalloc/vmmemmap/module
+		 * address, we will have different offset
+		 */
+		return 0;
+}
+

static int
get_page_offset_x86_64(void)
{

erase_info.c +1 -0

index f2ba9149e93e..60abfa1a1adf 100644
@@ -1088,6 +1088,7 @@ resolve_config_entry(struct config_entry *ce, unsigned long long base_vaddr,
 							ce->line, ce->name);
 			return FALSE;
 		}
+		ce->sym_addr += get_kaslr_offset(ce->sym_addr);
 		ce->type_name = get_symbol_type_name(ce->name,
 					DWARF_INFO_GET_SYMBOL_TYPE,
 					&ce->size, &ce->type_flag);

makedumpfile.c +0 -0

index 301772a8820c..4986d098d69a 100644
@@ -2099,6 +2099,13 @@ void
 write_vmcoreinfo_data(void)
 {
 	/*

makedumpfile.c void · line 2106

Quoted 5 lines

makedumpfile.c +5 -0

+	 * write 1st kernel's KERNELOFFSET
+	 */
+	if (info->kaslr_offset)
+		fprintf(info->file_vmcoreinfo, "%s%lx\n", STR_KERNELOFFSET,
+		    info->kaslr_offset);

When will this data written to VMCOREINFO file be used ? info->kaslr_offset is necessary for vmlinux but -x and -i are exclusive.

Quoted 8 lines

Quoted 8 lines

makedumpfile.c +0 -0

index 301772a8820c..4986d098d69a 100644
@@ -2099,6 +2099,13 @@ void
 write_vmcoreinfo_data(void)
 {
 	/*

Quoted 8 lines

makedumpfile.c void · line 2106

Quoted 5 lines

makedumpfile.c +5 -0

+	 * write 1st kernel's KERNELOFFSET
+	 */
+	if (info->kaslr_offset)
+		fprintf(info->file_vmcoreinfo, "%s%lx\n", STR_KERNELOFFSET,
+		    info->kaslr_offset);

When will this data written to VMCOREINFO file be used ? info->kaslr_offset is necessary for vmlinux but -x and -i are exclusive.

This is what I thought:

Lets says we have got a vmcore1 after re-filtering original vmcore. Now, if we would like to re-filter vmcore1 then we will need kaslr_offset again. So, should we not right kaslr_offset in vmcoreinfo of vmcore1 as well?

Quoted 10 lines

Quoted 10 lines

makedumpfile.c void · line 2106

Quoted 8 lines

write_vmcoreinfo_data(void)

{
	/*

makedumpfile.c +5 -0

+	 * write 1st kernel's KERNELOFFSET
+	 */
+	if (info->kaslr_offset)
+		fprintf(info->file_vmcoreinfo, "%s%lx\n", STR_KERNELOFFSET,
+		    info->kaslr_offset);

When will this data written to VMCOREINFO file be used ? info->kaslr_offset is necessary for vmlinux but -x and -i are exclusive.

Quoted 5 lines

This is what I thought:

Lets says we have got a vmcore1 after re-filtering original vmcore. Now, if we would like to re-filter vmcore1 then we will need kaslr_offset again. So, should we not right kaslr_offset in vmcoreinfo of vmcore1 as well?

write_vmcoreinfo_data() is called only for -g option, it makes a VMCOREINFO file as a separate file, it doesn't overwrite VMCOREINFO in vmcore.