Fix empty PIN handling for FIPS

.github/workflows/nss-pk12util-debian-test.yml

@@ -179,6 +179,11 @@ jobs:
         if [ -f "/tmp/nss-packages/libnss3_"*.deb ]; then
           echo "Using cached NSS packages:"
           ls -la /tmp/nss-packages/
+
+          # Install build dependencies when using cached packages
+          echo "Installing NSS build dependencies for cached packages..."
+          apt-get build-dep -y libnss3
+
           cd /tmp/nss-packages
         else
           echo "Using freshly built NSS packages:"

src/internal.c

@@ -5757,8 +5757,21 @@ static int HashPIN(char* pin, int pinLen, byte* seed, int seedLen, byte* hash,
                    int hashLen, WP11_Slot* slot)
 {
 #ifdef WOLFPKCS11_PBKDF2
-        return wc_PBKDF2_ex(hash, (byte*)pin, pinLen, seed, seedLen,
+#if defined(HAVE_FIPS) && defined(WOLFPKCS11_NSS)
+    if (pinLen == 0) {
+        /* For FIPS, use empty pin of HMAC_FIPS_MIN_KEY bytes when pinLen is 0.
+         * Otherwise we hit HMAC_MIN_KEYLEN_E.
+         * Certain NSS tools will try to login a blank token with an empty pin
+         * and this needs to succeed, or the tool will fail.
+         */
+        byte emptyPin[HMAC_FIPS_MIN_KEY];
+        XMEMSET(emptyPin, 0, sizeof(emptyPin));
+        return wc_PBKDF2_ex(hash, emptyPin, sizeof(emptyPin), seed, seedLen,
             PBKDF2_ITERATIONS, hashLen, WC_SHA256, NULL, slot->devId);
+    }
+#endif
+    return wc_PBKDF2_ex(hash, (byte*)pin, pinLen, seed, seedLen,
+        PBKDF2_ITERATIONS, hashLen, WC_SHA256, NULL, slot->devId);
 #elif defined(HAVE_SCRYPT)
     /* Convert PIN into secret using scrypt algorithm. */
     (void)slot;

src/slot.c

@@ -1839,6 +1839,9 @@ CK_RV C_Login(CK_SESSION_HANDLE hSession, CK_USER_TYPE userType,
         case PIN_NOT_SET_E:
             rv = CKR_USER_PIN_NOT_INITIALIZED;
             break;
+        /* No better error matches for pin too short for PBKDF2 HMAC */
+        case BAD_LENGTH_E:
+        case HMAC_MIN_KEYLEN_E:
         case PIN_INVALID_E:
             rv = CKR_PIN_INCORRECT;
             break;