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enforce trailerField==1 in DecodeRsaPssParams

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This commit is contained in:
Hideki Miyazaki
2026-06-04 10:32:27 +09:00
parent 3bc1575e12
commit 2e34433c52
2 changed files with 69 additions and 0 deletions
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tests/api/test_asn.c
+41
View File
@@ -1097,6 +1097,47 @@ int test_wc_DecodeRsaPssParams(void)
&hash, &mgf, &saltLen), WC_NO_ERR_TRACE(ASN_PARSE_E));
}
/* --- Test 9: trailerField = 1 (trailerFieldBC) => valid in all modes --- */
/* SEQUENCE { [3] CONSTRUCTED { INTEGER 1 } } = 30 05 a3 03 02 01 01 */
{
static const byte trailerValid[] = {
0x30, 0x05, 0xa3, 0x03, 0x02, 0x01, 0x01
};
hash = WC_HASH_TYPE_NONE;
mgf = 0;
saltLen = 0;
ExpectIntEQ(wc_DecodeRsaPssParams(trailerValid,
(word32)sizeof(trailerValid), &hash, &mgf, &saltLen), 0);
ExpectIntEQ((int)hash, (int)WC_HASH_TYPE_SHA);
ExpectIntEQ(mgf, WC_MGF1SHA1);
ExpectIntEQ(saltLen, 20);
}
#ifndef WOLFSSL_NO_ASN_STRICT
/* --- Test 10: trailerField = 2 => ASN_PARSE_E (strict mode) --- */
/* RFC 8017 A.2.3: trailerField SHALL be trailerFieldBC(1). */
/* SEQUENCE { [3] CONSTRUCTED { INTEGER 2 } } = 30 05 a3 03 02 01 02 */
{
static const byte trailerTwo[] = {
0x30, 0x05, 0xa3, 0x03, 0x02, 0x01, 0x02
};
ExpectIntEQ(wc_DecodeRsaPssParams(trailerTwo,
(word32)sizeof(trailerTwo), &hash, &mgf, &saltLen),
WC_NO_ERR_TRACE(ASN_PARSE_E));
}
/* --- Test 11: trailerField = 0 => ASN_PARSE_E (strict mode) --- */
/* SEQUENCE { [3] CONSTRUCTED { INTEGER 0 } } = 30 05 a3 03 02 01 00 */
{
static const byte trailerZero[] = {
0x30, 0x05, 0xa3, 0x03, 0x02, 0x01, 0x00
};
ExpectIntEQ(wc_DecodeRsaPssParams(trailerZero,
(word32)sizeof(trailerZero), &hash, &mgf, &saltLen),
WC_NO_ERR_TRACE(ASN_PARSE_E));
}
#endif /* !WOLFSSL_NO_ASN_STRICT */
#endif /* WC_RSA_PSS && !NO_RSA && !NO_ASN */
return EXPECT_RESULT();
}
wolfcrypt/src/asn.c
+28
View File
@@ -8074,6 +8074,9 @@ static int DecodeRsaPssParams(const byte* params, word32 sz,
{
DECL_ASNGETDATA(dataASN, rsaPssParamsASN_Length);
int ret = 0;
#ifndef WOLFSSL_NO_ASN_STRICT
word16 trailerVal = 1;
#endif
word16 sLen = 20;
/* Default values. */
@@ -8089,6 +8092,10 @@ static int DecodeRsaPssParams(const byte* params, word32 sz,
GetASN_OID(&dataASN[RSAPSSPARAMSASN_IDX_MGFHOID], oidHashType);
/* Place the salt length into 16-bit var sLen. */
GetASN_Int16Bit(&dataASN[RSAPSSPARAMSASN_IDX_SALTLENINT], &sLen);
#ifndef WOLFSSL_NO_ASN_STRICT
/* Capture trailerField value for RFC 8017 A.2.3 validation. */
GetASN_Int16Bit(&dataASN[RSAPSSPARAMSASN_IDX_TRAILERINT], &trailerVal);
#endif
/* Decode the algorithm identifier. */
ret = GetASN_Items(rsaPssParamsASN, dataASN, rsaPssParamsASN_Length, 1,
params, &inOutIdx, sz);
@@ -8105,6 +8112,15 @@ static int DecodeRsaPssParams(const byte* params, word32 sz,
word32 oid = dataASN[RSAPSSPARAMSASN_IDX_MGFHOID].data.oid.sum;
ret = RsaPssHashOidToMgf1(oid, mgf);
}
#ifndef WOLFSSL_NO_ASN_STRICT
/* RFC 8017 A.2.3: trailerField SHALL be trailerFieldBC(1). */
if ((ret == 0) && (dataASN[RSAPSSPARAMSASN_IDX_TRAILERINT].tag != 0)) {
if (trailerVal != 1) {
WOLFSSL_MSG("DecodeRsaPssParams: trailerField must be 1");
ret = ASN_PARSE_E;
}
}
#endif
if (ret == 0) {
*saltLen = sLen;
}
@@ -8251,12 +8267,24 @@ static int DecodeRsaPssParams(const byte* params, word32 sz,
}
if (ret == 0) {
ret = GetInteger16Bit(params, &idx, sz);
#ifndef WOLFSSL_NO_ASN_STRICT
/* RFC 8017 A.2.3: trailerField SHALL be trailerFieldBC(1). */
if (ret == 1) {
ret = 0;
}
else {
WOLFSSL_MSG("DecodeRsaPssParams: trailerField must be 1");
if (ret >= 0)
ret = ASN_PARSE_E;
}
#else
if (ret > 0) {
ret = 0;
}
else if (ret != 0) {
WOLFSSL_MSG("DecodeRsaPssParams: fail at trailer_value");
}
#endif
}
}
}