Use tags to detect loops. In the future, perhaps we'll use them to

actually also send the packet out the right interface.

1 files changed, 17 insertions, 18 deletions

diff --git a/sys/net/if_gre.c b/sys/net/if_gre.c
index 0386437295f..5d8d63cf7c2 100644
--- a/sys/net/if_gre.c
+++ b/sys/net/if_gre.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: if_gre.c,v 1.14 2001/06/25 01:50:16 fgsch Exp $ */
+/*      $OpenBSD: if_gre.c,v 1.15 2001/06/25 06:30:22 angelos Exp $ */
 /*	$NetBSD: if_gre.c,v 1.9 1999/10/25 19:18:11 drochner Exp $ */
 
 /*
@@ -168,15 +168,25 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	struct ip *inp = NULL;
 	u_short etype = 0;
 	struct mobile_h mob_h;
-	static int recursions = 0;	/* XXX MUTEX */
+	struct m_tag *mtag;
 
-	/* Try to limit infinite recursion through misconfiguration */
-	if (++recursions >= GRE_RECURSION_LIMIT) {
-		IF_DROP(&ifp->if_snd);
+	/* Try to limit infinite recursion through misconfiguration. */
+	for (mtag = m_tag_find(m, PACKET_TAG_GRE, NULL); mtag;
+	     mtag = m_tag_find(m, PACKET_TAG_GRE, mtag)) {
+		if (!bcmp((caddr_t)(mtag + 1), &ifp, sizeof(struct ifnet *))) {
+			IF_DROP(&ifp->if_snd);
+			m_freem(m);
+			return (EIO);	/* Use the same as in if_gif.c */
+		}
+	}
+
+	mtag = m_tag_get(PACKET_TAG_GRE, sizeof(struct ifnet *), M_NOWAIT);
+	if (mtag == NULL) {
 		m_freem(m);
-		recursions = 0;
-		return (EIO);	/* Use the same as in if_gif.c */
+		return (ENOBUFS);
 	}
+	bcopy(&ifp, (caddr_t)(mtag + 1), sizeof(struct ifnet *));
+	m_tag_prepend(m, mtag);
 
 #if NBPFILTER >0
 	if (ifp->if_bpf)
@@ -187,7 +197,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 		if (ip_mobile_allow == 0) {
 			IF_DROP(&ifp->if_snd);
 			m_freem(m);
-			recursions = 0;
 			return (EACCES);
 		}
 
@@ -203,7 +212,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 				m = m_pullup(m, sizeof(struct ip));
 				if (m == NULL) {
 					IF_DROP(&ifp->if_snd);
-					recursions = 0;
 					return (ENOBUFS);
 				} else
 					inp = mtod(m, struct ip *);
@@ -213,7 +221,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 					    sizeof(inp->ip_hl << 2));
 					if (m == NULL) {
 						IF_DROP(&ifp->if_snd);
-						recursions = 0;
 						return (ENOBUFS);
 					}
 				}
@@ -250,7 +257,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 				if (m0 == NULL) {
 					IF_DROP(&ifp->if_snd);
 					m_freem(m);
-					recursions = 0;
 					return (ENOBUFS);
 				}
 				M_COPY_HDR(m0, m);
@@ -282,14 +288,12 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 		} else {  /* AF_INET */
 			IF_DROP(&ifp->if_snd);
 			m_freem(m);
-			recursions = 0;
 			return (EINVAL);
 		}
 	} else if (sc->g_proto == IPPROTO_GRE) {
 		if (gre_allow == 0) {
 			IF_DROP(&ifp->if_snd);
 			m_freem(m);
-			recursions = 0;
 			return (EACCES);
 		}
 
@@ -299,7 +303,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 				m = m_pullup(m, sizeof(struct ip));
 				if (m == NULL) {
 					IF_DROP(&ifp->if_snd);
-					recursions = 0;
 					return (ENOBUFS);
 				}
 			}
@@ -320,7 +323,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 		default:
 			IF_DROP(&ifp->if_snd);
 			m_freem(m);
-			recursions = 0;
 			return (EAFNOSUPPORT);
 		}
 
@@ -329,13 +331,11 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 		error = EINVAL;
 		IF_DROP(&ifp->if_snd);
 		m_freem(m);
-		recursions = 0;
 		return (error);
 	}
 
 	if (m == NULL) {
 		IF_DROP(&ifp->if_snd);
-		recursions = 0;
 		return (ENOBUFS);
 	}
 
@@ -364,7 +364,6 @@ gre_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	error = ip_output(m, NULL, &sc->route, 0, NULL, NULL);
 	if (error)
 		ifp->if_oerrors++;
-	recursions = 0;
 	return (error);
 }