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Subject[PATCH v2 4/8] bootconfig: Remove unneeded checksum
Date
Remove checksum of bootconfig because we already use a magic
word to identify bootconfig. This checksum was used for
checking whether there is a bootconfig at the end of initrd
or not. Since we have a bootconfig magic word to identify
the bootconfig data, we do not this checksum anymore.

Thus the block image of the initrd file with bootconfig is
as follows.

[initrd][bootconfig][size(u32)][#BOOTCONFIG\n]

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
V2: Update Kconfig comment.
---
Documentation/admin-guide/bootconfig.rst | 6 ++--
init/Kconfig | 2 +
init/main.c | 20 +-------------
tools/bootconfig/main.c | 42 ++++++------------------------
tools/bootconfig/test-bootconfig.sh | 2 +
5 files changed, 16 insertions(+), 56 deletions(-)

diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst
index 5e7609936507..48675052c963 100644
--- a/Documentation/admin-guide/bootconfig.rst
+++ b/Documentation/admin-guide/bootconfig.rst
@@ -102,10 +102,10 @@ Boot Kernel With a Boot Config
==============================

Since the boot configuration file is loaded with initrd, it will be added
-to the end of the initrd (initramfs) image file with size, checksum and
-12-byte magic word as below.
+to the end of the initrd (initramfs) image file with 4-byte size and 12-byte
+magic word as below.

-[initrd][bootconfig][size(u32)][checksum(u32)][#BOOTCONFIG\n]
+[initrd][bootconfig][size][#BOOTCONFIG\n]

The Linux kernel decodes the last part of the initrd image in memory to
get the boot configuration data.
diff --git a/init/Kconfig b/init/Kconfig
index 6ffaf4940f3e..631ef2864608 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1231,7 +1231,7 @@ config BOOT_CONFIG
Extra boot config allows system admin to pass a config file as
complemental extension of kernel cmdline when booting.
The boot config file must be attached at the end of initramfs
- with checksum, size and magic word.
+ with size and magic word.
See <file:Documentation/admin-guide/bootconfig.rst> for details.

If unsure, say Y.
diff --git a/init/main.c b/init/main.c
index fe3ed874c748..821c582af49b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -335,16 +335,6 @@ static char * __init xbc_make_cmdline(const char *key)
return new_cmdline;
}

-u32 boot_config_checksum(unsigned char *p, u32 size)
-{
- u32 ret = 0;
-
- while (size--)
- ret += *p++;
-
- return ret;
-}
-
static int __init bootconfig_params(char *param, char *val,
const char *unused, void *arg)
{
@@ -359,7 +349,7 @@ static int __init bootconfig_params(char *param, char *val,
static void __init setup_boot_config(const char *cmdline)
{
static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
- u32 size, csum;
+ u32 size;
char *data, *copy;
u32 *hdr;
int ret;
@@ -378,9 +368,8 @@ static void __init setup_boot_config(const char *cmdline)
if (memcmp(data, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN))
goto not_found;

- hdr = (u32 *)(data - 8);
+ hdr = (u32 *)(data - sizeof(u32));
size = hdr[0];
- csum = hdr[1];

if (size >= XBC_DATA_MAX) {
pr_err("bootconfig size %d greater than max size %d\n",
@@ -392,11 +381,6 @@ static void __init setup_boot_config(const char *cmdline)
if ((unsigned long)data < initrd_start)
goto not_found;

- if (boot_config_checksum((unsigned char *)data, size) != csum) {
- pr_err("bootconfig checksum failed\n");
- return;
- }
-
copy = memblock_alloc(size + 1, SMP_CACHE_BYTES);
if (!copy) {
pr_err("Failed to allocate memory for bootconfig\n");
diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index a9b97814d1a9..01acb86c6273 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -75,17 +75,6 @@ static void xbc_show_compact_tree(void)
}
}

-/* Simple real checksum */
-int checksum(unsigned char *buf, int len)
-{
- int i, sum = 0;
-
- for (i = 0; i < len; i++)
- sum += buf[i];
-
- return sum;
-}
-
#define PAGE_SIZE 4096

int load_xbc_fd(int fd, char **buf, int size)
@@ -128,14 +117,14 @@ int load_xbc_from_initrd(int fd, char **buf)
{
struct stat stat;
int ret;
- u32 size = 0, csum = 0, rcsum;
+ u32 size = 0;
char magic[BOOTCONFIG_MAGIC_LEN];

ret = fstat(fd, &stat);
if (ret < 0)
return -errno;

- if (stat.st_size < 8 + BOOTCONFIG_MAGIC_LEN)
+ if (stat.st_size < 4 + BOOTCONFIG_MAGIC_LEN)
return 0;

if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0) {
@@ -148,7 +137,7 @@ int load_xbc_from_initrd(int fd, char **buf)
if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0)
return 0;

- if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0) {
+ if (lseek(fd, -(4 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0) {
pr_err("Failed to lseek: %d\n", -errno);
return -errno;
}
@@ -156,16 +145,13 @@ int load_xbc_from_initrd(int fd, char **buf)
if (read(fd, &size, sizeof(u32)) < 0)
return -errno;

- if (read(fd, &csum, sizeof(u32)) < 0)
- return -errno;
-
/* Wrong size error */
- if (stat.st_size < size + 8 + BOOTCONFIG_MAGIC_LEN) {
+ if (stat.st_size < size + 4 + BOOTCONFIG_MAGIC_LEN) {
pr_err("bootconfig size is too big\n");
return -E2BIG;
}

- if (lseek(fd, stat.st_size - (size + 8 + BOOTCONFIG_MAGIC_LEN),
+ if (lseek(fd, stat.st_size - (size + 4 + BOOTCONFIG_MAGIC_LEN),
SEEK_SET) < 0) {
pr_err("Failed to lseek: %d\n", -errno);
return -errno;
@@ -175,13 +161,6 @@ int load_xbc_from_initrd(int fd, char **buf)
if (ret < 0)
return ret;

- /* Wrong Checksum */
- rcsum = checksum((unsigned char *)*buf, size);
- if (csum != rcsum) {
- pr_err("checksum error: %d != %d\n", csum, rcsum);
- return -EINVAL;
- }
-
ret = xbc_init(*buf);
/* Wrong data */
if (ret < 0)
@@ -233,7 +212,7 @@ int delete_xbc(const char *path)
ret = fstat(fd, &stat);
if (!ret)
ret = ftruncate(fd, stat.st_size
- - size - 8 - BOOTCONFIG_MAGIC_LEN);
+ - size - 4 - BOOTCONFIG_MAGIC_LEN);
if (ret)
ret = -errno;
} /* Ignore if there is no boot config in initrd */
@@ -246,7 +225,7 @@ int delete_xbc(const char *path)

int apply_xbc(const char *path, const char *xbc_path)
{
- u32 size, csum;
+ u32 size;
char *buf, *data;
int ret, fd;

@@ -256,15 +235,13 @@ int apply_xbc(const char *path, const char *xbc_path)
return ret;
}
size = strlen(buf) + 1;
- csum = checksum((unsigned char *)buf, size);

/* Prepare xbc_path data */
- data = malloc(size + 8);
+ data = malloc(size + 4);
if (!data)
return -ENOMEM;
strcpy(data, buf);
*(u32 *)(data + size) = size;
- *(u32 *)(data + size + 4) = csum;

/* Check the data format */
ret = xbc_init(buf);
@@ -277,7 +254,6 @@ int apply_xbc(const char *path, const char *xbc_path)
printf("Apply %s to %s\n", xbc_path, path);
printf("\tNumber of nodes: %d\n", ret);
printf("\tSize: %u bytes\n", (unsigned int)size);
- printf("\tChecksum: %d\n", (unsigned int)csum);

/* TODO: Check the options by schema */
xbc_destroy_all();
@@ -297,7 +273,7 @@ int apply_xbc(const char *path, const char *xbc_path)
return fd;
}
/* TODO: Ensure the @path is initramfs/initrd image */
- ret = write(fd, data, size + 8);
+ ret = write(fd, data, size + 4);
if (ret < 0) {
pr_err("Failed to apply a boot config: %d\n", ret);
return ret;
diff --git a/tools/bootconfig/test-bootconfig.sh b/tools/bootconfig/test-bootconfig.sh
index adafb7c50940..c5965eff62c5 100755
--- a/tools/bootconfig/test-bootconfig.sh
+++ b/tools/bootconfig/test-bootconfig.sh
@@ -49,7 +49,7 @@ xpass $BOOTCONF -a $TEMPCONF $INITRD
new_size=$(stat -c %s $INITRD)

echo "File size check"
-xpass test $new_size -eq $(expr $bconf_size + $initrd_size + 9 + 12)
+xpass test $new_size -eq $(expr $bconf_size + $initrd_size + 5 + 12)

echo "Apply command repeat test"
xpass $BOOTCONF -a $TEMPCONF $INITRD
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