nhrpd: fixes duplicate auth extension

When an NHRP server was forwarding a message, it was copying all extensions from the originally received packet. The authentication extension must be regenerated hop by hop per RFC2332. The copied auth extension had an incorrect length. This fix checks for the auth extension when copying extensions and omits the original packet auth and instead regenerates a new auth extension. Fix bug #16466 Signed-off-by: Dave LeRoy <[email protected]>
FRRouting · Jul 26, 2024 · fba6f03 · fba6f03
1 parent 353efe7
commit fba6f03
Showing 1 changed file with 12 additions and 9 deletions.
diff --git a/nhrpd/nhrp_peer.c b/nhrpd/nhrp_peer.c
@@ -959,9 +959,12 @@ static void nhrp_peer_forward(struct nhrp_peer *p,
 		if (type == NHRP_EXTENSION_END)
 			break;
 
-		dst = nhrp_ext_push(zb, hdr, htons(ext->type));
-		if (!dst)
-			goto err;
+		dst = NULL;
+		if (type != NHRP_EXTENSION_AUTHENTICATION) {
+			dst = nhrp_ext_push(zb, hdr, htons(ext->type));
+			if (!dst)
+				goto err;
+		}
 
 		switch (type) {
 		case NHRP_EXTENSION_FORWARD_TRANSIT_NHS:
@@ -1047,12 +1050,11 @@ static void nhrp_peer_forward(struct nhrp_peer *p,
 			}
 			break;
 		case NHRP_EXTENSION_AUTHENTICATION:
-			/* At this point, received packet has been authenticated.
-			 *  Just need to regenerate auth extension before forwarding.
-			 *  This will be done below in nhrp_packet_complete_auth().
-			 */
+			/* Extensions can be copied from original packet except
+		 * authentication extension which must be regenerated
+		 * hop by hop.
+		 */
 			break;
-
 		default:
 			if (htons(ext->type) & NHRP_EXTENSION_FLAG_COMPULSORY)
 				/* FIXME: RFC says to just copy, but not
@@ -1068,7 +1070,8 @@ static void nhrp_peer_forward(struct nhrp_peer *p,
 			zbuf_copy(zb, &extpl, len);
 			break;
 		}
-		nhrp_ext_complete(zb, dst);
+		if (dst)
+			nhrp_ext_complete(zb, dst);
 	}
 
 	nhrp_packet_complete_auth(zb, hdr, pp->ifp, true);