}
-/** Validates the requesting client NAS
- *
- * Calculates the request Authenticator based on the clients private key.
- */
-static int calc_acctdigest(RADIUS_PACKET *packet, char const *secret)
-{
- uint8_t digest[AUTH_VECTOR_LEN];
- FR_MD5_CTX context;
-
- /*
- * Zero out the auth_vector in the received packet.
- * Then append the shared secret to the received packet,
- * and calculate the MD5 sum. This must be the same
- * as the original MD5 sum (packet->vector).
- */
- memset(packet->data + 4, 0, AUTH_VECTOR_LEN);
-
- /*
- * MD5(packet + secret);
- */
- fr_md5_init(&context);
- fr_md5_update(&context, packet->data, packet->data_len);
- fr_md5_update(&context, (uint8_t const *) secret, talloc_array_length(secret) - 1);
- fr_md5_final(digest, &context);
-
- /*
- * Return 0 if OK, 2 if not OK.
- */
- if (fr_radius_digest_cmp(digest, packet->vector, AUTH_VECTOR_LEN) != 0) return 2;
- return 0;
-}
-
-
-/** Validates the requesting client NAS
- *
- * Calculates the response Authenticator based on the clients
- * private key.
- */
-static int calc_replydigest(RADIUS_PACKET *packet, RADIUS_PACKET *original,
- char const *secret)
-{
- uint8_t calc_digest[AUTH_VECTOR_LEN];
- FR_MD5_CTX context;
-
- /*
- * Very bad!
- */
- if (original == NULL) {
- return 3;
- }
-
- /*
- * Copy the original vector in place.
- */
- memcpy(packet->data + 4, original->vector, AUTH_VECTOR_LEN);
-
- /*
- * MD5(packet + secret);
- */
- fr_md5_init(&context);
- fr_md5_update(&context, packet->data, packet->data_len);
- fr_md5_update(&context, (uint8_t const *) secret, talloc_array_length(secret) - 1);
- fr_md5_final(calc_digest, &context);
-
- /*
- * Copy the packet's vector back to the packet.
- */
- memcpy(packet->data + 4, packet->vector, AUTH_VECTOR_LEN);
-
- /*
- * Return 0 if OK, 2 if not OK.
- */
- if (fr_radius_digest_cmp(packet->vector, calc_digest, AUTH_VECTOR_LEN) != 0) return 2;
- return 0;
-}
-
-
/** See if the data pointed to by PTR is a valid RADIUS packet.
*
* Packet is not 'const * const' because we may update data_len, if there's more data
return packet;
}
-/** Verify the Request/Response Authenticator (and Message-Authenticator if present) of a packet
+
+/** Verify a request / response packet
+ *
+ * This function does its work by calling fr_radius_sign(), and then
+ * comparing the signature in the packet with the one we calculated.
+ * If they differ, there's a problem.
*
+ * @param packet the raw RADIUS packet (request or response)
+ * @param original the raw original request (if this is a response)
+ * @param secret the shared secret
+ * @param secret_len the length of the secret
+ * @return
+ * - <0 on error
+ * - 0 on success
*/
-int fr_radius_packet_verify(RADIUS_PACKET *packet, RADIUS_PACKET *original, char const *secret)
+static int fr_radius_verify(uint8_t *packet, uint8_t const *original,
+ uint8_t const *secret, size_t secret_len)
{
- uint8_t *ptr;
- int length;
- int attrlen;
- int rcode;
- char buffer[INET6_ADDRSTRLEN];
+ int rcode;
+ uint8_t *msg, *end;
+ size_t packet_len = (packet[2] << 8) | packet[3];
+ uint8_t request_authenticator[AUTH_VECTOR_LEN];
+ uint8_t message_authenticator[AUTH_VECTOR_LEN];
- if (!packet || !packet->data) return -1;
+ if (packet_len < RADIUS_HDR_LEN) {
+ fr_strerror_printf("invalid packet length %zd", packet_len);
+ return -1;
+ }
+
+ memcpy(request_authenticator, packet + 4, sizeof(request_authenticator));
/*
- * Before we allocate memory for the attributes, do more
- * sanity checking.
+ * Find Message-Authenticator. Its value has to be
+ * calculated before we calculate the Request
+ * Authenticator or the Response Authenticator.
*/
- ptr = packet->data + RADIUS_HDR_LEN;
- length = packet->data_len - RADIUS_HDR_LEN;
- while (length > 0) {
- uint8_t msg_auth_vector[AUTH_VECTOR_LEN];
- uint8_t calc_auth_vector[AUTH_VECTOR_LEN];
-
- attrlen = ptr[1];
-
- switch (ptr[0]) {
- default: /* don't do anything. */
- break;
-
- /*
- * Note that more than one Message-Authenticator
- * attribute is invalid.
- */
- case PW_MESSAGE_AUTHENTICATOR:
- memcpy(msg_auth_vector, &ptr[2], sizeof(msg_auth_vector));
- memset(&ptr[2], 0, AUTH_VECTOR_LEN);
-
- switch (packet->code) {
- default:
- break;
-
- case PW_CODE_ACCOUNTING_RESPONSE:
- if (original &&
- (original->code == PW_CODE_STATUS_SERVER)) {
- goto do_ack;
- }
-
- case PW_CODE_ACCOUNTING_REQUEST:
- case PW_CODE_DISCONNECT_REQUEST:
- case PW_CODE_COA_REQUEST:
- memset(packet->data + 4, 0, AUTH_VECTOR_LEN);
- break;
+ msg = packet + RADIUS_HDR_LEN;
+ end = packet + packet_len;
- do_ack:
- case PW_CODE_ACCESS_ACCEPT:
- case PW_CODE_ACCESS_REJECT:
- case PW_CODE_ACCESS_CHALLENGE:
- case PW_CODE_DISCONNECT_ACK:
- case PW_CODE_DISCONNECT_NAK:
- case PW_CODE_COA_ACK:
- case PW_CODE_COA_NAK:
- if (!original) {
- fr_strerror_printf("Cannot validate Message-Authenticator in response "
- "packet without a request packet");
- return -1;
- }
- memcpy(packet->data + 4, original->vector, AUTH_VECTOR_LEN);
- break;
- }
+ while (msg < end) {
+ if (msg[0] != PW_MESSAGE_AUTHENTICATOR) {
+ if (msg[1] < 2) goto invalid_attribute;
- fr_hmac_md5(calc_auth_vector, packet->data, packet->data_len,
- (uint8_t const *) secret, talloc_array_length(secret) - 1);
- if (fr_radius_digest_cmp(calc_auth_vector, msg_auth_vector,
- sizeof(calc_auth_vector)) != 0) {
- fr_strerror_printf("Received packet from %s with invalid Message-Authenticator! "
- "(Shared secret is incorrect.)",
- inet_ntop(packet->src_ipaddr.af,
- &packet->src_ipaddr.ipaddr,
- buffer, sizeof(buffer)));
- /* Silently drop packet, according to RFC 3579 */
+ if ((msg + msg[1]) > end) {
+ invalid_attribute:
+ fr_strerror_printf("invalid attribute at offset %zd", msg - packet);
return -1;
- } /* else the message authenticator was good */
+ }
+ msg += msg[1];
+ continue;
+ }
- /*
- * Reinitialize Authenticators.
- */
- memcpy(&ptr[2], msg_auth_vector, AUTH_VECTOR_LEN);
- memcpy(packet->data + 4, packet->vector, AUTH_VECTOR_LEN);
- break;
- } /* switch over the attributes */
+ if (msg[1] < 18) {
+ fr_strerror_printf("too small Message-Authenticator");
+ return -1;
+ }
- ptr += attrlen;
- length -= attrlen;
- } /* loop over the packet, sanity checking the attributes */
+ /*
+ * Found it. Copy it over.
+ */
+ memcpy(message_authenticator, msg + 2, sizeof(message_authenticator));
+ break;
+ }
- /*
- * It looks like a RADIUS packet, but we don't know what it is
- * so can't validate the authenticators.
- */
- if ((packet->code == 0) || (packet->code >= FR_MAX_PACKET_CODE)) {
- fr_strerror_printf("Received Unknown packet code %d "
- "from client %s port %d: Cannot validate Request/Response-Authenticator.",
- packet->code,
- inet_ntop(packet->src_ipaddr.af,
- &packet->src_ipaddr.ipaddr,
- buffer, sizeof(buffer)),
- packet->src_port);
+ rcode = fr_radius_sign(packet, original, secret, secret_len);
+ if (rcode < 0) {
+ fr_strerror_printf("unknown packet code");
return -1;
}
/*
- * Calculate and/or verify Request or Response Authenticator.
+ * Check the Message-Authenticator first.
+ *
+ * If it's invalid, restore the original
+ * Message-Authenticator and Request Authenticator
+ * fields.
*/
- switch (packet->code) {
- case PW_CODE_ACCESS_REQUEST:
- case PW_CODE_STATUS_SERVER:
- /*
- * The authentication vector is random
- * nonsense, invented by the client.
- */
- break;
+ if ((msg < end) &&
+ (fr_radius_digest_cmp(message_authenticator, msg + 2, sizeof(message_authenticator)) != 0)) {
+ memcpy(msg + 2, message_authenticator, sizeof(message_authenticator));
+ memcpy(packet + 4, request_authenticator, sizeof(request_authenticator));
- case PW_CODE_COA_REQUEST:
- case PW_CODE_DISCONNECT_REQUEST:
- case PW_CODE_ACCOUNTING_REQUEST:
- if (calc_acctdigest(packet, secret) > 1) {
- fr_strerror_printf("Received %s packet "
- "from client %s with invalid Request-Authenticator! "
- "(Shared secret is incorrect.)",
- fr_packet_codes[packet->code],
- inet_ntop(packet->src_ipaddr.af,
- &packet->src_ipaddr.ipaddr,
- buffer, sizeof(buffer)));
- return -1;
- }
- break;
+ fr_strerror_printf("invalid Message-Authenticator (shared secret is incorrect)");
+ return -1;
+ }
- /* Verify the reply digest */
- case PW_CODE_ACCESS_ACCEPT:
- case PW_CODE_ACCESS_REJECT:
- case PW_CODE_ACCESS_CHALLENGE:
- case PW_CODE_ACCOUNTING_RESPONSE:
- case PW_CODE_DISCONNECT_ACK:
- case PW_CODE_DISCONNECT_NAK:
- case PW_CODE_COA_ACK:
- case PW_CODE_COA_NAK:
- rcode = calc_replydigest(packet, original, secret);
- if (rcode > 1) {
- fr_strerror_printf("Received %s packet "
- "from home server %s port %d with invalid Response-Authenticator! "
- "(Shared secret is incorrect.)",
- fr_packet_codes[packet->code],
- inet_ntop(packet->src_ipaddr.af,
- &packet->src_ipaddr.ipaddr,
- buffer, sizeof(buffer)),
- packet->src_port);
- return -1;
+ if (fr_radius_digest_cmp(request_authenticator, packet + 4, sizeof(request_authenticator)) != 0) {
+ memcpy(packet + 4, request_authenticator, sizeof(request_authenticator));
+ if (original) {
+ fr_strerror_printf("invalid Response Authenticator (shared secret is incorrect)");
+ } else {
+ fr_strerror_printf("invalid Request Authenticator (shared secret is incorrect)");
}
- break;
+ }
- default:
- fr_strerror_printf("Received Unknown packet code %d "
- "from client %s port %d: Cannot validate Request/Response-Authenticator",
- packet->code,
- inet_ntop(packet->src_ipaddr.af,
- &packet->src_ipaddr.ipaddr,
- buffer, sizeof(buffer)),
- packet->src_port);
+ return 0;
+}
+
+
+/** Verify the Request/Response Authenticator (and Message-Authenticator if present) of a packet
+ *
+ */
+int fr_radius_packet_verify(RADIUS_PACKET *packet, RADIUS_PACKET *original, char const *secret)
+{
+ uint8_t const *original_data;
+ char buffer[INET6_ADDRSTRLEN];
+
+ if (!packet || !packet->data) return -1;
+
+ if (original) {
+ original_data = original->data;
+ } else {
+ original_data = NULL;
+ }
+
+ if (fr_radius_verify(packet->data, original_data,
+ (uint8_t const *) secret, talloc_array_length(secret) - 1) < 0) {
+ fr_strerror_printf("Received packet from %s with %s",
+ inet_ntop(packet->src_ipaddr.af, &packet->src_ipaddr.ipaddr,
+ buffer, sizeof(buffer)),
+ fr_strerror());
return -1;
}
projects / thirdparty / freeradius-server.git / commitdiff
