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Validate ECC curve in user auth, document auth callback contracts #1141

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Validate ECC curve in user auth, document auth callback contracts #1141

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04645d6
ssh.h: document the WS_CallbackUserAuth contract
ejohnstown Aug 3, 2026
30a12a9
ssh.h: document the WS_CallbackPublicKeyCheck contract
ejohnstown Aug 3, 2026
710fa4e
internal: validate the ECC curve name in user auth
ejohnstown Aug 3, 2026
272c1da
tests: add test_ByteHighwater
ejohnstown Aug 3, 2026
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37 changes: 28 additions & 9 deletions src/internal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8507,6 +8507,8 @@ static int DoUserAuthRequestEcc(WOLFSSH* ssh, WS_UserAuthData_PublicKey* pk,
word32 sz, qSz, rSz, sSz;
word32 i = 0, asnSigSz = ECDSA_ASN_SIG_SZ;
int ret = WS_SUCCESS;
int primeId = ECC_CURVE_INVALID;
byte keyId = ID_NONE;
ecc_key *key_ptr = NULL;
byte* asnSig = NULL;
#ifndef WOLFSSH_SMALL_STACK
Expand Down Expand Up @@ -8559,26 +8561,43 @@ static int DoUserAuthRequestEcc(WOLFSSH* ssh, WS_UserAuthData_PublicKey* pk,
}
}

/* Derive the curve from the declared algorithm, not from the blob. */
if (ret == WS_SUCCESS) {
keyId = NameToId((const char*)pk->publicKeyType, pk->publicKeyTypeSz);
primeId = wcPrimeForId(keyId);
if (primeId == ECC_CURVE_INVALID) {
ret = WS_INVALID_PRIME_CURVE;
}
}

if (ret == WS_SUCCESS)
ret = GetSize(&curveNameSz, pk->publicKey, pk->publicKeySz, &i);

/* The curve name (RFC 5656 section 3.1) in the blob must match the
* curve of the declared algorithm. */
if (ret == WS_SUCCESS) {
const char* primeName = PrimeNameForId(keyId);

curveName = pk->publicKey + i;
WOLFSSH_UNUSED(curveName);
/* Not used at the moment, hush the compiler. */
i += curveNameSz;
ret = GetSize(&qSz, pk->publicKey, pk->publicKeySz, &i);
if (curveNameSz != (word32)WSTRLEN(primeName)
|| WMEMCMP(curveName, primeName, curveNameSz) != 0) {
WLOG(WS_LOG_DEBUG,
"Public Key's curve name does not match its type");
ret = WS_INVALID_PRIME_CURVE;
}
}

if (ret == WS_SUCCESS)
ret = GetSize(&qSz, pk->publicKey, pk->publicKeySz, &i);

if (ret == WS_SUCCESS) {
q = pk->publicKey + i;
i += qSz;
ret = wc_ecc_import_x963(q, qSz, key_ptr);
}

if (ret != 0) {
WLOG(WS_LOG_DEBUG, "Could not decode public key");
ret = WS_CRYPTO_FAILED;
if (wc_ecc_import_x963_ex(q, qSz, key_ptr, primeId) != 0) {
WLOG(WS_LOG_DEBUG, "Could not decode public key");
ret = WS_CRYPTO_FAILED;
}
}

if (ret == WS_SUCCESS) {
Expand Down
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