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Have bootconfig size and checksum be little endian

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In case the bootconfig is created on one kind of endian machine, and then
 read on the other kind of endian kernel, the size and checksum will be
 incorrect. Instead, have both the size and checksum always be little
 endian and have the tool and the kernel convert it from little endian to
 or from the host endian.
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Merge tag 'trace-v5.10-rc6-bootconfig' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull bootconfig fixes from Steven Rostedt:
 "Have bootconfig size and checksum be little endian

  In case the bootconfig is created on one kind of endian machine, and
  then read on the other kind of endian kernel, the size and checksum
  will be incorrect. Instead, have both the size and checksum always be
  little endian and have the tool and the kernel convert it from little
  endian to or from the host endian"

* tag 'trace-v5.10-rc6-bootconfig' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  docs: bootconfig: Add the endianness of fields
  tools/bootconfig: Store size and checksum in footer as le32
  bootconfig: Load size and checksum in the footer as le32
This commit is contained in:
Linus Torvalds 2020-12-02 12:09:36 -08:00
commit 8a02ec8f35
3 changed files with 10 additions and 5 deletions
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4
Documentation/admin-guide/bootconfig.rst
View File

@ -140,7 +140,9 @@ Since the boot configuration file is loaded with initrd, it will be added
to the end of the initrd (initramfs) image file with padding, size,
checksum and 12-byte magic word as below.
[initrd][bootconfig][padding][size(u32)][checksum(u32)][#BOOTCONFIG\n]
[initrd][bootconfig][padding][size(le32)][checksum(le32)][#BOOTCONFIG\n]
The size and checksum fields are unsigned 32bit little endian value.
When the boot configuration is added to the initrd image, the total
file size is aligned to 4 bytes. To fill the gap, null characters

4
init/main.c
View File

@ -288,8 +288,8 @@ static void * __init get_boot_config_from_initrd(u32 *_size, u32 *_csum)
found:
hdr = (u32 *)(data - 8);
size = hdr[0];
csum = hdr[1];
size = le32_to_cpu(hdr[0]);
csum = le32_to_cpu(hdr[1]);
data = ((void *)hdr) - size;
if ((unsigned long)data < initrd_start) {

7
tools/bootconfig/main.c
View File

@ -10,6 +10,7 @@
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <endian.h>
#include <linux/kernel.h>
#include <linux/bootconfig.h>
@ -183,9 +184,11 @@ static int load_xbc_from_initrd(int fd, char **buf)
if (read(fd, &size, sizeof(u32)) < 0)
return pr_errno("Failed to read size", -errno);
size = le32toh(size);
if (read(fd, &csum, sizeof(u32)) < 0)
return pr_errno("Failed to read checksum", -errno);
csum = le32toh(csum);
/* Wrong size error */
if (stat.st_size < size + 8 + BOOTCONFIG_MAGIC_LEN) {
@ -407,10 +410,10 @@ static int apply_xbc(const char *path, const char *xbc_path)
/* Add a footer */
p = data + size;
*(u32 *)p = size;
*(u32 *)p = htole32(size);
p += sizeof(u32);
*(u32 *)p = csum;
*(u32 *)p = htole32(csum);
p += sizeof(u32);
memcpy(p, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);