Add a pseudo interface for packet filtering IPSec connections before or after

encryption. There are two functions, a bpf tap which has a basic header with
the SPI number which our current tcpdump knows how to display, and handoff to
pfil(9) for packet filtering.

Obtained from:	OpenBSD
Based on:	kern/94829
No objections:	arch, net
MFC after:	1 month

4 files changed, 35 insertions, 0 deletions

diff --git a/sys/netipsec/ipsec.h b/sys/netipsec/ipsec.h
index 7dfe1ac..e514ce5 100644
--- a/sys/netipsec/ipsec.h
+++ b/sys/netipsec/ipsec.h
@@ -417,6 +417,8 @@ extern	void m_checkalignment(const char* where, struct mbuf *m0,
 extern	struct mbuf *m_makespace(struct mbuf *m0, int skip, int hlen, int *off);
 extern	caddr_t m_pad(struct mbuf *m, int n);
 extern	int m_striphdr(struct mbuf *m, int skip, int hlen);
+extern	int ipsec_filter(struct mbuf **, int);
+extern	void ipsec_bpf(struct mbuf *, struct secasvar *, int);
 #endif /* _KERNEL */
 
 #ifndef _KERNEL
diff --git a/sys/netipsec/ipsec_input.c b/sys/netipsec/ipsec_input.c
index 753b78a..24bc1c3 100644
--- a/sys/netipsec/ipsec_input.c
+++ b/sys/netipsec/ipsec_input.c
@@ -43,6 +43,7 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
+#include "opt_enc.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -442,6 +443,18 @@ ipsec4_common_input_cb(struct mbuf *m, struct secasvar *sav,
 
 	key_sa_recordxfer(sav, m);		/* record data transfer */
 
+#ifdef DEV_ENC
+	/*
+	 * Pass the mbuf to enc0 for bpf and pfil. We will filter the IPIP
+	 * packet later after it has been decapsulated.
+	 */
+	ipsec_bpf(m, sav, AF_INET);
+
+	if (prot != IPPROTO_IPIP)
+		if ((error = ipsec_filter(&m, 1)) != 0)
+			return (error);
+#endif
+
 	/*
 	 * Re-dispatch via software interrupt.
 	 */
diff --git a/sys/netipsec/ipsec_output.c b/sys/netipsec/ipsec_output.c
index 788e07a..51dce82 100644
--- a/sys/netipsec/ipsec_output.c
+++ b/sys/netipsec/ipsec_output.c
@@ -32,6 +32,7 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
+#include "opt_enc.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -358,6 +359,13 @@ ipsec4_process_packet(
 		goto bad;
 
 	sav = isr->sav;
+
+#ifdef DEV_ENC
+	/* pass the mbuf to enc0 for packet filtering */
+	if ((error = ipsec_filter(&m, 2)) != 0)
+		goto bad;
+#endif
+
 	if (!tunalready) {
 		union sockaddr_union *dst = &sav->sah->saidx.dst;
 		int setdf;
@@ -455,6 +463,11 @@ ipsec4_process_packet(
 		}
 	}
 
+#ifdef DEV_ENC
+	/* pass the mbuf to enc0 for bpf processing */
+	ipsec_bpf(m, sav, AF_INET);
+#endif
+
 	/*
 	 * Dispatch to the appropriate IPsec transform logic.  The
 	 * packet will be returned for transmission after crypto
diff --git a/sys/netipsec/xform_ipip.c b/sys/netipsec/xform_ipip.c
index 4bb0b54..8191009 100644
--- a/sys/netipsec/xform_ipip.c
+++ b/sys/netipsec/xform_ipip.c
@@ -41,6 +41,7 @@
  */
 #include "opt_inet.h"
 #include "opt_inet6.h"
+#include "opt_enc.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -345,6 +346,12 @@ _ipip_input(struct mbuf *m, int iphlen, struct ifnet *gifp)
 	/* Statistics */
 	ipipstat.ipips_ibytes += m->m_pkthdr.len - iphlen;
 
+#ifdef DEV_ENC
+	/* pass the mbuf to enc0 for packet filtering */
+	if (ipsec_filter(&m, 1) != 0)
+		return;
+#endif
+
 	/*
 	 * Interface pointer stays the same; if no IPsec processing has
 	 * been done (or will be done), this will point to a normal