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increase custom TLV size limit to UINT16_MAX

pull/828/head
Brett Nicholas 2026-07-21 15:15:10 -06:00
parent 88c0f1fd55
commit 6c148b2e9e
2 changed files with 86 additions and 67 deletions
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10
docs/Signing.md
View File

@ -255,17 +255,23 @@ Provides a value to be set with a custom tag
* `--custom-tlv-buffer tag value`: Adds a TLV entry with arbitrary length to the manifest
header, corresponding to the type identified by `tag`, and assigns the value `value`. The
tag is a 16-bit number. Valid tags are in the range between 0x0030 and 0xFEFE. The length
is implicit, and is the length of the value.
is implicit, and is the length of the value. The maximum length is 65535 bytes.
Value argument is in the form of a hex string, e.g. `--custom-tlv-buffer 0x0030 AABBCCDDEE`
will add a TLV entry with tag 0x0030, length 5 and value 0xAABBCCDDEE.
* `--custom-tlv-string tag ascii-string`: Adds a TLV entry with arbitrary length to the manifest
header, corresponding to the type identified by `tag`, and assigns the value of `ascii-string`. The
tag is a 16-bit number. Valid tags are in the range between 0x0030 and 0xFEFE. The length
is implicit, and is the length of the `ascii-string`. `ascii-string` argument is in the form of a string,
is implicit, and is the length of the `ascii-string`. The maximum length is 65535 bytes.
`ascii-string` argument is in the form of a string,
e.g. `--custom-tlv-string 0x0030 "Version-1"` will add a TLV entry with tag 0x0030,
length 9 and value Version-1.
If the custom TLVs do not fit in the configured header size, the sign tool automatically
increases the size of the manifest header, rounding up to the next power of two. wolfBoot
must be built with a matching `IMAGE_HEADER_SIZE`, or it will fail to locate the firmware
image at boot.
#### Three-steps signing using external provisioning tools
If the private key is not accessible, while it's possible to sign payloads using

143
tools/keytools/sign.c
View File

@ -1377,42 +1377,46 @@ static int make_header_ex(int is_diff, uint8_t *pubkey, uint32_t pubkey_sz,
/* Check certificate chain file size before allocating header, and adjust
* header size if needed */
if (CMD.cert_chain_file != NULL) {
struct stat file_stat;
if ((CMD.cert_chain_file != NULL) || (CMD.custom_tlvs > 0)) {
uint32_t cert_chain_sz = 0;
uint32_t required_space;
/* Get the file size */
if (stat(CMD.cert_chain_file, &file_stat) == 0) {
off_t chain_file_sz = file_stat.st_size;
uint32_t required_space;
if ((chain_file_sz < 0) ||
((uintmax_t)chain_file_sz > (uintmax_t)UINT32_MAX)) {
printf("Warning: certificate chain file size is invalid (%jd)\n",
(intmax_t)chain_file_sz);
}
else {
required_space = header_required_size(is_diff,
(uint32_t)chain_file_sz, secondary_key_sz);
/* If the current header size is too small, increase it */
if (CMD.header_sz < required_space) {
/* Round up to nearest power of 2 that can hold the chain */
const uint32_t min_header_size = 256;
uint32_t new_size = min_header_size;
while (new_size < required_space) {
new_size *= 2;
}
printf("Increasing header size from %u to %u bytes to fit "
"certificate chain\n",
CMD.header_sz, new_size);
CMD.header_sz = new_size;
/* Get the certificate chain file size */
if (CMD.cert_chain_file != NULL) {
struct stat file_stat;
if (stat(CMD.cert_chain_file, &file_stat) == 0) {
off_t chain_file_sz = file_stat.st_size;
if ((chain_file_sz < 0) ||
((uintmax_t)chain_file_sz > (uintmax_t)UINT32_MAX)) {
printf("Warning: certificate chain file size is invalid "
"(%jd)\n", (intmax_t)chain_file_sz);
}
else {
cert_chain_sz = (uint32_t)chain_file_sz;
}
}
else {
printf("Warning: Could not stat certificate chain file %s: %s\n",
CMD.cert_chain_file, strerror(errno));
}
}
else {
printf("Warning: Could not stat certificate chain file %s: %s\n",
CMD.cert_chain_file, strerror(errno));
required_space = header_required_size(is_diff, cert_chain_sz,
secondary_key_sz);
/* If the current header size is too small, increase it */
if (CMD.header_sz < required_space) {
/* Round up to nearest power of 2 that can hold all fields */
const uint32_t min_header_size = 256;
uint32_t new_size = min_header_size;
while (new_size < required_space) {
new_size *= 2;
}
printf("Increasing header size from %u to %u bytes to fit "
"manifest header fields\n",
CMD.header_sz, new_size);
CMD.header_sz = new_size;
}
}
@ -2530,36 +2534,38 @@ static int base_diff(const char *f_base, uint8_t *pubkey, uint32_t pubkey_sz, in
len3++;
}
/* make_header_delta() below calls make_header_ex(is_diff=1), which may grow
* CMD.header_sz to fit the delta TLVs plus certificate chain. Resolve that
* expansion here, using the same logic, so patch_inv_off reflects the header
* size actually written; otherwise HDR_IMG_DELTA_INVERSE would encode a
* stale, too-small offset and break inverse-patch rollback. */
if (CMD.cert_chain_file != NULL) {
struct stat cc_stat;
if ((stat(CMD.cert_chain_file, &cc_stat) == 0) &&
(cc_stat.st_size >= 0)) {
if ((uintmax_t)cc_stat.st_size > (uintmax_t)UINT16_MAX) {
printf("Error: Certificate chain too large for TLV encoding "
"(%ju > %u)\n", (uintmax_t)cc_stat.st_size, UINT16_MAX);
goto cleanup;
}
else {
uint32_t required_space = header_required_size(1,
(uint32_t)cc_stat.st_size, 0);
if (CMD.header_sz < required_space) {
uint32_t new_size = 256;
while (new_size < required_space) {
if (new_size > (UINT32_MAX / 2U)) {
printf("Error: Header size overflow while sizing "
"certificate chain\n");
goto cleanup;
}
new_size *= 2;
}
CMD.header_sz = new_size;
* CMD.header_sz to fit the delta TLVs, custom TLVs and certificate chain.
* Resolve that expansion here, using the same logic, so patch_inv_off
* reflects the header size actually written; otherwise HDR_IMG_DELTA_INVERSE
* would encode a stale, too-small offset and break inverse-patch rollback. */
if ((CMD.cert_chain_file != NULL) || (CMD.custom_tlvs > 0)) {
uint32_t cert_chain_sz = 0;
uint32_t required_space;
if (CMD.cert_chain_file != NULL) {
struct stat cc_stat;
if ((stat(CMD.cert_chain_file, &cc_stat) == 0) &&
(cc_stat.st_size >= 0)) {
if ((uintmax_t)cc_stat.st_size > (uintmax_t)UINT16_MAX) {
printf("Error: Certificate chain too large for TLV encoding "
"(%ju > %u)\n", (uintmax_t)cc_stat.st_size, UINT16_MAX);
goto cleanup;
}
cert_chain_sz = (uint32_t)cc_stat.st_size;
}
}
required_space = header_required_size(1, cert_chain_sz, 0);
if (CMD.header_sz < required_space) {
uint32_t new_size = 256;
while (new_size < required_space) {
if (new_size > (UINT32_MAX / 2U)) {
printf("Error: Header size overflow while sizing "
"manifest header\n");
goto cleanup;
}
new_size *= 2;
}
CMD.header_sz = new_size;
}
}
patch_inv_off = (uint32_t)len3 + CMD.header_sz;
patch_inv_sz = 0;
@ -3202,6 +3208,7 @@ int main(int argc, char** argv)
} else if (strcmp(argv[i], "--custom-tlv-buffer") == 0) {
int p = CMD.custom_tlvs;
uint16_t tag, len;
size_t slen;
uint32_t j;
if (p >= MAX_CUSTOM_TLVS) {
fprintf(stderr, "Too many custom TLVs.\n");
@ -3212,7 +3219,7 @@ int main(int argc, char** argv)
exit(16);
}
tag = (uint16_t)arg2num(argv[i + 1], 2);
len = (uint16_t)strlen(argv[i + 2]) / 2;
slen = strlen(argv[i + 2]);
if (tag < 0x0030) {
fprintf(stderr, "Invalid custom tag: %s\n", argv[i + 1]);
exit(16);
@ -3221,10 +3228,13 @@ int main(int argc, char** argv)
fprintf(stderr, "Invalid custom tag: %s\n", argv[i + 1]);
exit(16);
}
if (len > 255) {
fprintf(stderr, "custom tlv buffer size too big: %s\n", argv[i + 2]);
if ((slen / 2) > UINT16_MAX) {
fprintf(stderr, "custom tlv buffer size too big: "
"%lu bytes (max %u)\n", (unsigned long)(slen / 2),
UINT16_MAX);
exit(16);
}
len = (uint16_t)(slen / 2);
CMD.custom_tlv[p].tag = tag;
CMD.custom_tlv[p].len = len;
CMD.custom_tlv[p].buffer = malloc(len);
@ -3241,6 +3251,7 @@ int main(int argc, char** argv)
} else if (strcmp(argv[i], "--custom-tlv-string") == 0) {
int p = CMD.custom_tlvs;
uint16_t tag, len;
size_t slen;
uint32_t j;
if (p >= MAX_CUSTOM_TLVS) {
fprintf(stderr, "Too many custom TLVs.\n");
@ -3251,7 +3262,7 @@ int main(int argc, char** argv)
exit(16);
}
tag = (uint16_t)arg2num(argv[i + 1], 2);
len = (uint16_t)strlen(argv[i + 2]);
slen = strlen(argv[i + 2]);
if (tag < 0x0030) {
fprintf(stderr, "Invalid custom tag: %s\n", argv[i + 1]);
exit(16);
@ -3260,10 +3271,12 @@ int main(int argc, char** argv)
fprintf(stderr, "Invalid custom tag: %s\n", argv[i + 1]);
exit(16);
}
if (len > 255) {
fprintf(stderr, "custom tlv buffer size too big: %s\n", argv[i + 2]);
if (slen > UINT16_MAX) {
fprintf(stderr, "custom tlv string size too big: "
"%lu bytes (max %u)\n", (unsigned long)slen, UINT16_MAX);
exit(16);
}
len = (uint16_t)slen;
CMD.custom_tlv[p].tag = tag;
CMD.custom_tlv[p].len = len;
CMD.custom_tlv[p].buffer = malloc(len);