MFp4 CH=183052 183053 183258:

In protosw we define pr_protocol as short, while on the wire
  it is an uint8_t.  That way we can have "internal" protocols
  like DIVERT, SEND or gaps for modules (PROTO_SPACER).
  Switch ipproto_{un,}register to accept a short protocol number(*)
  and do an upfront check for valid boundries. With this we
  also consistently report EPROTONOSUPPORT for out of bounds
  protocols, as we did for proto == 0.  This allows a caller
  to not error for this case, which is especially important
  if we want to automatically call these from domain handling.

  (*) the functions have been without any in-tree consumer
  since the initial introducation, so this is considered save.

  Implement ip6proto_{un,}register() similarly to their legacy IP
  counter parts to allow modules to hook up dynamically.

Reviewed by:	philip, will
MFC after:	1 week

sys/netinet/ip_input.c

@@ -1287,12 +1287,12 @@ ip_drain(void)
  * in inetsw[], either statically or through pf_proto_register().
  */
 int
-ipproto_register(u_char ipproto)
+ipproto_register(short ipproto)
 {
 	struct protosw *pr;
 
 	/* Sanity checks. */
-	if (ipproto == 0)
+	if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
 		return (EPROTONOSUPPORT);
 
 	/*
@@ -1310,24 +1310,20 @@ ipproto_register(u_char ipproto)
 	     pr < inetdomain.dom_protoswNPROTOSW; pr++) {
 		if (pr->pr_domain->dom_family == PF_INET &&
 		    pr->pr_protocol && pr->pr_protocol == ipproto) {
-			/* Be careful to only index valid IP protocols. */
-			if (pr->pr_protocol < IPPROTO_MAX) {
-				ip_protox[pr->pr_protocol] = pr - inetsw;
-				return (0);
-			} else
-				return (EINVAL);
+			ip_protox[pr->pr_protocol] = pr - inetsw;
+			return (0);
 		}
 	}
 	return (EPROTONOSUPPORT);
 }
 
 int
-ipproto_unregister(u_char ipproto)
+ipproto_unregister(short ipproto)
 {
 	struct protosw *pr;
 
 	/* Sanity checks. */
-	if (ipproto == 0)
+	if (ipproto <= 0 || ipproto >= IPPROTO_MAX)
 		return (EPROTONOSUPPORT);
 
 	/* Check if the protocol was indeed registered. */

sys/netinet/ip_var.h

@@ -220,8 +220,8 @@ extern int
 int	ip_output(struct mbuf *,
 	    struct mbuf *, struct route *, int, struct ip_moptions *,
 	    struct inpcb *);
-int	ipproto_register(u_char);
-int	ipproto_unregister(u_char);
+int	ipproto_register(short);
+int	ipproto_unregister(short);
 struct mbuf *
 	ip_reass(struct mbuf *);
 struct in_ifaddr *

sys/netinet6/ip6_input.c

@@ -227,6 +227,64 @@ ip6_init(void)
 	netisr_register(&ip6_nh);
 }
 
+/*
+ * The protocol to be inserted into ip6_protox[] must be already registered
+ * in inet6sw[], either statically or through pf_proto_register().
+ */
+int
+ip6proto_register(short ip6proto)
+{
+	struct ip6protosw *pr;
+
+	/* Sanity checks. */
+	if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
+		return (EPROTONOSUPPORT);
+
+	/*
+	 * The protocol slot must not be occupied by another protocol
+	 * already.  An index pointing to IPPROTO_RAW is unused.
+	 */
+	pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
+	if (pr == NULL)
+		return (EPFNOSUPPORT);
+	if (ip6_protox[ip6proto] != pr - inet6sw)	/* IPPROTO_RAW */
+		return (EEXIST);
+
+	/*
+	 * Find the protocol position in inet6sw[] and set the index.
+	 */
+	for (pr = (struct ip6protosw *)inet6domain.dom_protosw;
+	    pr < (struct ip6protosw *)inet6domain.dom_protoswNPROTOSW; pr++) {
+		if (pr->pr_domain->dom_family == PF_INET6 &&
+		    pr->pr_protocol && pr->pr_protocol == ip6proto) {
+			ip6_protox[pr->pr_protocol] = pr - inet6sw;
+			return (0);
+		}
+	}
+	return (EPROTONOSUPPORT);
+}
+
+int
+ip6proto_unregister(short ip6proto)
+{
+	struct ip6protosw *pr;
+
+	/* Sanity checks. */
+	if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
+		return (EPROTONOSUPPORT);
+
+	/* Check if the protocol was indeed registered. */
+	pr = (struct ip6protosw *)pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
+	if (pr == NULL)
+		return (EPFNOSUPPORT);
+	if (ip6_protox[ip6proto] == pr - inet6sw)	/* IPPROTO_RAW */
+		return (ENOENT);
+
+	/* Reset the protocol slot to IPPROTO_RAW. */
+	ip6_protox[ip6proto] = pr - inet6sw;
+	return (0);
+}
+
 #ifdef VIMAGE
 void
 ip6_destroy()

sys/netinet6/ip6_var.h

@@ -368,6 +368,9 @@ void	ip6_init __P((void));
 #ifdef VIMAGE
 void	ip6_destroy __P((void));
 #endif
+int	ip6proto_register(short);
+int	ip6proto_unregister(short);
+
 void	ip6_input __P((struct mbuf *));
 struct in6_ifaddr *ip6_getdstifaddr __P((struct mbuf *));
 void	ip6_freepcbopts __P((struct ip6_pktopts *));