Requeue mbuf via netisr when we use IPSec tunnel mode and IPv6.

ipsec6_common_input_cb() uses partial copy of ip6_input() to parse
headers. But this isn't correct, when we use tunnel mode IPSec.

When we stripped outer IPv6 header from the decrypted packet, it
can become IPv4 packet and should be handled by ip_input. Also when
we use tunnel mode IPSec with IPv6 traffic, we should pass decrypted
packet with inner IPv6 header to ip6_input, it will correctly handle
it and also can decide to forward it.

The "skip" variable points to offset where payload starts. In tunnel
mode we reset it to zero after stripping the outer header. So, when
it is zero, we should requeue mbuf via netisr.

Differential Revision:	https://reviews.freebsd.org/D2306
Reviewed by:	adrian, gnn
Sponsored by:	Yandex LLC

1 files changed, 30 insertions, 1 deletions

diff --git a/sys/netipsec/ipsec_input.c b/sys/netipsec/ipsec_input.c
index 1eac8db..846fefa 100644
--- a/sys/netipsec/ipsec_input.c
+++ b/sys/netipsec/ipsec_input.c
@@ -627,7 +627,7 @@ ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip,
 	struct m_tag *mtag;
 	struct tdb_ident *tdbi;
 	struct secasindex *saidx;
-	int nxt;
+	int nxt, isr_prot;
 	u_int8_t nxt8;
 	int error, nest;
 #ifdef notyet
@@ -803,6 +803,35 @@ ipsec6_common_input_cb(struct mbuf *m, struct secasvar *sav, int skip,
 	if ((error = ipsec_filter(&m, PFIL_IN, ENC_IN|ENC_AFTER)) != 0)
 		return (error);
 #endif /* DEV_ENC */
+	if (skip == 0) {
+		/*
+		 * We stripped outer IPv6 header.
+		 * Now we should requeue decrypted packet via netisr.
+		 */
+		switch (prot) {
+#ifdef INET
+		case IPPROTO_IPIP:
+			isr_prot = NETISR_IP;
+			break;
+#endif
+		case IPPROTO_IPV6:
+			isr_prot = NETISR_IPV6;
+			break;
+		default:
+			DPRINTF(("%s: cannot handle inner ip proto %d\n",
+			    __func__, prot));
+			IPSEC_ISTAT(sproto, nopf);
+			error = EPFNOSUPPORT;
+			goto bad;
+		}
+		error = netisr_queue_src(isr_prot, (uintptr_t)sav->spi, m);
+		if (error) {
+			IPSEC_ISTAT(sproto, qfull);
+			DPRINTF(("%s: queue full; proto %u packet dropped\n",
+			    __func__, sproto));
+		}
+		return (error);
+	}
 	/*
 	 * See the end of ip6_input for this logic.
 	 * IPPROTO_IPV[46] case will be processed just like other ones