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ifwitool: Calculate checksum for subpart_dir 

Checksum is calculated by using 2s complement method. 8-bit sum of the
entire subpart directory from first byte of header to last byte of last
partition directory entry.

BUG=chrome-os-partner:53508

Change-Id: I991d79dfdb5331ab732bf0d71cf8223d63426fa8
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/15200
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
This commit is contained in:
Furquan Shaikh 2016-06-15 08:01:10 -07:00
parent 4b373ca8a0
commit e51c20bf2c
1 changed files with 50 additions and 6 deletions
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56
util/cbfstool/ifwitool.c
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@ -101,8 +101,8 @@ struct subpart_dir_header {
/* Length of directory header in bytes. */
uint8_t header_length;
/*
* TODO(furquan): Add checksum calculation once more details are
* available.
* 2s complement of 8-bit sum from first byte of header to last byte of
* last directory entry.
*/
uint8_t checksum;
/* ASCII short name of sub-partition. */
@ -750,7 +750,27 @@ static void parse_sbpdt(void *data, size_t size)
"S-BPDT");
}
static void validate_subpart_dir(struct subpart_dir *s, const char *name)
static uint8_t calc_checksum(struct subpart_dir *s)
{
size_t size = subpart_dir_size(&s->h);
uint8_t *data = (uint8_t *)s;
uint8_t checksum = 0;
size_t i;
uint8_t old_checksum = s->h.checksum;
s->h.checksum = 0;
for (i = 0; i < size; i++)
checksum += data[i];
s->h.checksum = old_checksum;
/* 2s complement */
return -checksum;
}
static void validate_subpart_dir(struct subpart_dir *s, const char *name,
bool checksum_check)
{
if ((s->h.marker != SUBPART_DIR_MARKER) ||
(s->h.header_version != SUBPART_DIR_HEADER_VERSION_SUPPORTED) ||
@ -759,6 +779,27 @@ static void validate_subpart_dir(struct subpart_dir *s, const char *name)
ERROR("Invalid subpart_dir for %s.\n", name);
exit(-1);
}
if (checksum_check == false)
return;
uint8_t checksum = calc_checksum(s);
if (checksum != s->h.checksum)
ERROR("Invalid checksum for %s (Expected=0x%x, Actual=0x%x).\n",
name, checksum, s->h.checksum);
}
static void validate_subpart_dir_without_checksum(struct subpart_dir *s,
const char *name)
{
validate_subpart_dir(s, name, 0);
}
static void validate_subpart_dir_with_checksum(struct subpart_dir *s,
const char *name)
{
validate_subpart_dir(s, name, 1);
}
static void parse_subpart_dir(struct buffer *subpart_dir_buf,
@ -784,7 +825,7 @@ static void parse_subpart_dir(struct buffer *subpart_dir_buf,
memcpy(hdr.name, data + offset, sizeof(hdr.name));
offset += sizeof(hdr.name);
validate_subpart_dir((struct subpart_dir *)&hdr, name);
validate_subpart_dir_without_checksum((struct subpart_dir *)&hdr, name);
assert(size > subpart_dir_size(&hdr));
alloc_buffer(subpart_dir_buf, subpart_dir_size(&hdr), "Subpart Dir");
@ -805,6 +846,8 @@ static void parse_subpart_dir(struct buffer *subpart_dir_buf,
&e[i].rsvd);
}
validate_subpart_dir_with_checksum(subpart_dir, name);
print_subpart_dir(subpart_dir);
}
@ -1353,7 +1396,7 @@ static void create_subpart(struct buffer *dst, struct buffer *info[],
buffer_size(info[i]));
}
h->checksum = 0;
h->checksum = calc_checksum(buffer_get(&subpart_dir_buff));
struct subpart_dir *dir = buffer_get(&subpart_dir_buff);
@ -1717,7 +1760,8 @@ static enum ifwi_ret ifwi_dir_replace(int type)
s->e[i].offset += offset;
}
s->h.checksum = 0;
/* Re-calculate checksum. */
s->h.checksum = calc_checksum(s);
/* Convert members to litte-endian. */
subpart_dir_fixup_write_buffer(&subpart_dir_buf);