Convert IPDIVERT into a loadable module. This makes use of the dynamic loadability

of protocols.  The call to divert_packet() is done through a function pointer.  All
semantics of IPDIVERT remain intact.  If IPDIVERT is not loaded ipfw will refuse to
install divert rules and  natd will complain about 'protocol not supported'.  Once
it is loaded both will work and accept rules and open the divert socket.  The module
can only be unloaded if no divert sockets are open.  It does not close any divert
sockets when an unload is requested but will return EBUSY instead.

6 files changed, 100 insertions, 37 deletions

diff --git a/sys/modules/ipdivert/Makefile b/sys/modules/ipdivert/Makefile
new file mode 100644
index 0000000..203b4bf
--- /dev/null
+++ b/sys/modules/ipdivert/Makefile
@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+.PATH: ${.CURDIR}/../../netinet
+
+KMOD=   ipdivert
+SRCS=   ip_divert.c
+
+.include <bsd.kmod.mk>
diff --git a/sys/netinet/in_proto.c b/sys/netinet/in_proto.c
index 8e8279d..a9158bf 100644
--- a/sys/netinet/in_proto.c
+++ b/sys/netinet/in_proto.c
@@ -30,7 +30,6 @@
  * $FreeBSD$
  */
 
-#include "opt_ipdivert.h"
 #include "opt_ipx.h"
 #include "opt_mrouting.h"
 #include "opt_ipsec.h"
@@ -54,7 +53,6 @@
 #include <netinet/ip.h>
 #include <netinet/ip_var.h>
 #include <netinet/ip_icmp.h>
-#include <netinet/ip_divert.h>
 #include <netinet/igmp_var.h>
 #ifdef PIM
 #include <netinet/pim_var.h>
@@ -215,14 +213,6 @@ struct protosw inetsw[] = {
   &rip_usrreqs
 },
 #endif
-#ifdef IPDIVERT
-{ SOCK_RAW,	&inetdomain,	IPPROTO_DIVERT,	PR_ATOMIC|PR_ADDR,
-  div_input,	0,		div_ctlinput,	ip_ctloutput,
-  0,
-  div_init,	0,		0,		0,
-  &div_usrreqs,
-},
-#endif
 #ifdef IPXIP
 { SOCK_RAW,	&inetdomain,	IPPROTO_IDP,	PR_ATOMIC|PR_ADDR|PR_LASTHDR,
   ipxip_input,	0,		ipxip_ctlinput,	0,
@@ -297,9 +287,6 @@ SYSCTL_NODE(_net_inet, IPPROTO_AH,	ipsec,	CTLFLAG_RW, 0,	"IPSEC");
 #endif /* IPSEC */
 #endif /* !FAST_IPSEC */
 SYSCTL_NODE(_net_inet, IPPROTO_RAW,	raw,	CTLFLAG_RW, 0,	"RAW");
-#ifdef IPDIVERT
-SYSCTL_NODE(_net_inet, IPPROTO_DIVERT,	divert,	CTLFLAG_RW, 0,	"DIVERT");
-#endif
 #ifdef PIM
 SYSCTL_NODE(_net_inet, IPPROTO_PIM,    pim,    CTLFLAG_RW, 0,  "PIM");
 #endif
diff --git a/sys/netinet/ip_divert.c b/sys/netinet/ip_divert.c
index fa8a6ea..f2fa212 100644
--- a/sys/netinet/ip_divert.c
+++ b/sys/netinet/ip_divert.c
@@ -29,15 +29,13 @@
  * $FreeBSD$
  */
 
+#if !defined(KLD_MODULE)
 #include "opt_inet.h"
-#include "opt_ipfw.h"
-#include "opt_ipdivert.h"
-#include "opt_ipsec.h"
 #include "opt_mac.h"
-
 #ifndef INET
 #error "IPDIVERT requires INET."
 #endif
+#endif
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -45,6 +43,8 @@
 #include <sys/malloc.h>
 #include <sys/mac.h>
 #include <sys/mbuf.h>
+#include <sys/module.h>
+#include <sys/kernel.h>
 #include <sys/proc.h>
 #include <sys/protosw.h>
 #include <sys/signalvar.h>
@@ -102,7 +102,7 @@
  * will cause it to be effectively considered as a standard packet).
  */
 
-/* Internal variables */
+/* Internal variables. */
 static struct inpcbhead divcb;
 static struct inpcbinfo divcbinfo;
 
@@ -147,7 +147,7 @@ div_input(struct mbuf *m, int off)
  * Setup generic address and protocol structures for div_input routine,
  * then pass them along with mbuf chain.
  */
-void
+static void
 divert_packet(struct mbuf *m, int incoming)
 {
 	struct ip *ip;
@@ -650,10 +650,11 @@ div_peeraddr(struct socket *so, struct sockaddr **nam)
 	return (in_setpeeraddr(so, nam, &divcbinfo));
 }
 
-
-SYSCTL_DECL(_net_inet_divert);
+#ifdef SYSCTL_NODE
+SYSCTL_NODE(_net_inet, IPPROTO_DIVERT, divert, CTLFLAG_RW, 0, "IPDIVERT");
 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, 0, 0,
 	    div_pcblist, "S,xinpcb", "List of active divert sockets");
+#endif
 
 struct pr_usrreqs div_usrreqs = {
 	div_abort, pru_accept_notsupp, div_attach, div_bind,
@@ -662,3 +663,61 @@ struct pr_usrreqs div_usrreqs = {
 	pru_rcvoob_notsupp, div_send, pru_sense_null, div_shutdown,
 	div_sockaddr, sosend, soreceive, sopoll, in_pcbsosetlabel
 };
+
+struct protosw div_protosw = {
+  SOCK_RAW,	NULL,		IPPROTO_DIVERT,	PR_ATOMIC|PR_ADDR,
+  div_input,	NULL,		div_ctlinput,	ip_ctloutput,
+  NULL,
+  div_init,	NULL,		NULL,		NULL,
+  &div_usrreqs
+};
+
+static int
+div_modevent(module_t mod, int type, void *unused)
+{
+	int err = 0;
+	int n;
+
+	switch (type) {
+	case MOD_LOAD:
+		/*
+		 * Protocol will be initialized by pf_proto_register().
+		 * We don't have to register ip_protox because we are not
+		 * a true IP protocol that goes over the wire.
+		 */
+		err = pf_proto_register(PF_INET, &div_protosw);
+		ip_divert_ptr = divert_packet;
+		break;
+	case MOD_UNLOAD:
+		/*
+		 * Module ipdivert can only be unloaded if no sockets are
+		 * connected.  Maybe this can be changed later to forcefully
+		 * disconnect any open sockets.
+		 */
+		INP_INFO_RLOCK(&divcbinfo);
+		n = divcbinfo.ipi_count;
+		INP_INFO_RUNLOCK(&divcbinfo);
+		if (n != 0) {
+			err = EBUSY;
+			break;
+		}
+		ip_divert_ptr = NULL;
+		err = pf_proto_unregister(PF_INET, IPPROTO_DIVERT, SOCK_RAW);
+		INP_INFO_LOCK_DESTROY(&divcbinfo);
+		break;
+	default:
+		return EINVAL;
+		break;
+	}
+	return err;
+}
+
+static moduledata_t ipdivertmod = {
+        "ipdivert",
+        div_modevent,
+        0
+};
+
+DECLARE_MODULE(ipdivert, ipdivertmod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
+MODULE_DEPEND(dummynet, ipfw, 2, 2, 2);
+MODULE_VERSION(ipdivert, 1);
diff --git a/sys/netinet/ip_divert.h b/sys/netinet/ip_divert.h
index d925918..1bb0944 100644
--- a/sys/netinet/ip_divert.h
+++ b/sys/netinet/ip_divert.h
@@ -36,9 +36,15 @@
 #define	_NETINET_IP_DIVERT_H_
 
 /*
- * Divert socket definitions.
+ * Sysctl declaration.
  */
+#ifdef SYSCTL_DECL
+SYSCTL_DECL(_net_inet_divert);
+#endif
 
+/*
+ * Divert socket definitions.
+ */
 struct divert_tag {
 	u_int32_t	info;		/* port & flags */
 	u_int16_t	cookie;		/* ipfw rule number */
@@ -74,10 +80,10 @@ divert_find_info(struct mbuf *m)
 	return mtag ? divert_info(mtag) : 0;
 }
 
+typedef	void ip_divert_packet_t(struct mbuf *m, int incoming);
+extern	ip_divert_packet_t *ip_divert_ptr;
+
 extern	void div_init(void);
 extern	void div_input(struct mbuf *, int);
 extern	void div_ctlinput(int, struct sockaddr *, void *);
-extern	void divert_packet(struct mbuf *m, int incoming);
-extern	struct mbuf *divert_clone(struct mbuf *);
-extern struct pr_usrreqs div_usrreqs;
 #endif /* _NETINET_IP_DIVERT_H_ */
diff --git a/sys/netinet/ip_fw2.c b/sys/netinet/ip_fw2.c
index c45a04f..36b4e48 100644
--- a/sys/netinet/ip_fw2.c
+++ b/sys/netinet/ip_fw2.c
@@ -35,7 +35,6 @@
 #if !defined(KLD_MODULE)
 #include "opt_ipfw.h"
 #include "opt_ipdn.h"
-#include "opt_ipdivert.h"
 #include "opt_inet.h"
 #include "opt_ipsec.h"
 #ifndef INET
@@ -3077,9 +3076,8 @@ check_ipfw_struct(struct ip_fw *rule, int size)
 
 		case O_DIVERT:
 		case O_TEE:
-#ifndef	IPDIVERT
-			return EINVAL;
-#endif
+			if (ip_divert_ptr == NULL)
+				return EINVAL;
 		case O_FORWARD_MAC: /* XXX not implemented yet */
 		case O_CHECK_STATE:
 		case O_COUNT:
diff --git a/sys/netinet/ip_fw_pfil.c b/sys/netinet/ip_fw_pfil.c
index 3b08f69..80c7d05 100644
--- a/sys/netinet/ip_fw_pfil.c
+++ b/sys/netinet/ip_fw_pfil.c
@@ -29,7 +29,6 @@
 #if !defined(KLD_MODULE)
 #include "opt_ipfw.h"
 #include "opt_ipdn.h"
-#include "opt_ipdivert.h"
 #include "opt_inet.h"
 #ifndef INET
 #error IPFIREWALL requires INET.
@@ -67,10 +66,13 @@ static	int ipfw_pfil_hooked = 0;
 /* Dummynet hooks. */
 ip_dn_ruledel_t	*ip_dn_ruledel_ptr = NULL;
 
-#define	DIV_DIR_IN	1
-#define	DIV_DIR_OUT	0
+/* Divert hooks. */
+ip_divert_packet_t *ip_divert_ptr = NULL;
 
+/* Forward declarations. */
 static int	ipfw_divert(struct mbuf **, int, int);
+#define	DIV_DIR_IN	1
+#define	DIV_DIR_OUT	0
 
 int
 ipfw_check_in(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
@@ -255,13 +257,16 @@ ipfw_divert(struct mbuf **m, int incoming, int tee)
 	 * If tee is set, copy packet and return original.
 	 * If not tee, consume packet and send it to divert socket.
 	 */
-#ifdef IPDIVERT
 	struct mbuf *clone, *reass;
 	struct ip *ip;
 	int hlen;
 
 	reass = NULL;
 
+	/* Is divert module loaded? */
+	if (ip_divert_ptr == NULL)
+		goto nodivert;
+
 	/* Cloning needed for tee? */
 	if (tee)
 		clone = m_dup(*m, M_DONTWAIT);
@@ -309,8 +314,8 @@ ipfw_divert(struct mbuf **m, int incoming, int tee)
 	}
 
 	/* Do the dirty job... */
-	if (clone)
-		divert_packet(clone, incoming);
+	if (clone && ip_divert_ptr != NULL)
+		ip_divert_ptr(clone, incoming);
 
 teeout:
 	/*
@@ -322,10 +327,10 @@ teeout:
 
 	/* Packet diverted and consumed */
 	return 1;
-#else
+
+nodivert:
 	m_freem(*m);
 	return 1;
-#endif	/* ipdivert */
 }
 
 static int