check for invalid values of the Crypto-Binding Flags field

diff --git a/src/modules/rlm_eap/types/rlm_eap_teap/eap_teap.c b/src/modules/rlm_eap/types/rlm_eap_teap/eap_teap.c
index a8f61ddcce41c44016b9bd285bb336e5218ead49..b31bfdee7b3887de424253b36bf23a7d4e1730eb 100644 (file)
--- a/src/modules/rlm_eap/types/rlm_eap_teap/eap_teap.c
+++ b/src/modules/rlm_eap/types/rlm_eap_teap/eap_teap.c
@@ -1443,18 +1443,33 @@ static PW_CODE eap_teap_validate_crypto_binding(REQUEST *request, UNUSED eap_han
         *      binding->received_version is what they got from us.
         */
        if (binding->version != t->received_version || binding->received_version != EAP_TEAP_VERSION) {
-               RDEBUG2("Phase 2: Crypto-Binding TLV version mis-match (possible downgrade attack!)");
-               RDEBUG2("Phase 2: Expected client to send %d, got %d.  We sent %d, they echoed back %d",
+               RWDEBUG2("Phase 2: Crypto-Binding TLV version mis-match (possible downgrade attack!)");
+               RWDEBUG2("Phase 2: Expected client to send %d, got %d.  We sent %d, they echoed back %d",
                        t->received_version, binding->version,
                        EAP_TEAP_VERSION, binding->received_version);
                return PW_CODE_ACCESS_REJECT;
        }
        if ((binding->subtype & 0xf) != EAP_TEAP_TLV_CRYPTO_BINDING_SUBTYPE_RESPONSE) {
-               RDEBUG2("Phase 2: Crypto-Binding TLV contains unexpected response");
+               RWDEBUG2("Phase 2: Crypto-Binding TLV contains unexpected response");
                return PW_CODE_ACCESS_REJECT;
        }
        flags = binding->subtype >> 4;
 
+       /*
+        *      The Flags field is 4 bits:
+        *
+        *              0 - EMSK (may or may not be set)
+        *              1 - MSK (always set)
+        *              2 - MUST be zero
+        *              3 - MUST be zero
+        */
+       if ((flags == 0) || (flags > 3)) {
+               RWDEBUG2("Phase 2: Invalid Crypto-Binding Flags=%d", flags);
+               return PW_CODE_ACCESS_REJECT;
+       }
+
+       RDEBUG("Phase 2: Received Crypto-Binding Flags=%d", flags);
+
        CRYPTO_BINDING_BUFFER_INIT(cbb);
        memcpy(&cbb->binding, binding, sizeof(cbb->binding) - sizeof(cbb->binding.emsk_compound_mac) - sizeof(cbb->binding.msk_compound_mac));
 
@@ -1483,8 +1498,6 @@ static PW_CODE eap_teap_validate_crypto_binding(REQUEST *request, UNUSED eap_han
         */
        const EVP_MD *md = SSL_CIPHER_get_handshake_digest(SSL_get_current_cipher(tls_session->ssl));
 
-       RDEBUG("Phase 2: Crypto-Binding flags=%d", flags);
-
        /*
         *      We verify cryptobinding MSK and EMSK, but we prefer
         *      EMSK for the later IMCK deriviation.