Fix the the SCTP_WITH_NO_CSUM option when used in combination with

interface supporting CRC offload. While at it, make use of the
feature that the loopback interface provides CRC offloading.

MFC after: 4 weeks

7 files changed, 123 insertions, 101 deletions

diff --git a/sys/netinet/sctp_crc32.c b/sys/netinet/sctp_crc32.c
index d9ae238..0ab8039 100644
--- a/sys/netinet/sctp_crc32.c
+++ b/sys/netinet/sctp_crc32.c
@@ -115,20 +115,15 @@ sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
 	return (base);
 }
 
-#else
-
-uint32_t
-sctp_calculate_cksum(struct mbuf *m, uint32_t offset)
-{
-	return (0);
-}
-
 #endif				/* !defined(SCTP_WITH_NO_CSUM) */
 
 
 void
 sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
 {
+#if defined(SCTP_WITH_NO_CSUM)
+	panic("sctp_delayed_cksum() called when using no SCTP CRC.");
+#else
 	struct ip *ip;
 	uint32_t checksum;
 
@@ -149,4 +144,5 @@ sctp_delayed_cksum(struct mbuf *m, uint32_t offset)
 		return;
 	}
 	*(uint32_t *) (m->m_data + offset) = checksum;
+#endif
 }
diff --git a/sys/netinet/sctp_crc32.h b/sys/netinet/sctp_crc32.h
index e66815e..eb7a1bc 100644
--- a/sys/netinet/sctp_crc32.h
+++ b/sys/netinet/sctp_crc32.h
@@ -36,11 +36,12 @@ __FBSDID("$FreeBSD$");
 #ifndef __crc32c_h__
 #define __crc32c_h__
 
-#if defined(_KERNEL) || defined(__Userspace__)
-
+#if defined(_KERNEL)
+#if !defined(SCTP_WITH_NO_CSUM)
 uint32_t sctp_calculate_cksum(struct mbuf *, uint32_t);
+
+#endif
 void sctp_delayed_cksum(struct mbuf *, uint32_t offset);
 
 #endif				/* _KERNEL */
-
 #endif				/* __crc32c_h__ */
diff --git a/sys/netinet/sctp_input.c b/sys/netinet/sctp_input.c
index 089c9b6..5da86ff 100644
--- a/sys/netinet/sctp_input.c
+++ b/sys/netinet/sctp_input.c
@@ -3068,7 +3068,7 @@ process_chunk_drop(struct sctp_tcb *stcb, struct sctp_chunk_desc *desc,
     struct sctp_nets *net, uint8_t flg)
 {
 	switch (desc->chunk_type) {
-		case SCTP_DATA:
+	case SCTP_DATA:
 		/* find the tsn to resend (possibly */
 		{
 			uint32_t tsn;
@@ -5717,14 +5717,17 @@ sctp_input_with_port(struct mbuf *i_pak, int off, uint16_t port)
 	struct ip *ip;
 	struct sctphdr *sh;
 	struct sctp_inpcb *inp = NULL;
-
-	uint32_t check, calc_check;
 	struct sctp_nets *net;
 	struct sctp_tcb *stcb = NULL;
 	struct sctp_chunkhdr *ch;
 	int refcount_up = 0;
 	int length, mlen, offset;
 
+#if !defined(SCTP_WITH_NO_CSUM)
+	uint32_t check, calc_check;
+
+#endif
+
 	if (SCTP_GET_PKT_VRFID(i_pak, vrf_id)) {
 		SCTP_RELEASE_PKT(i_pak);
 		return;
@@ -5799,18 +5802,14 @@ sctp_input_with_port(struct mbuf *i_pak, int off, uint16_t port)
 	    m->m_pkthdr.len,
 	    if_name(m->m_pkthdr.rcvif),
 	    m->m_pkthdr.csum_flags);
+#if defined(SCTP_WITH_NO_CSUM)
+	SCTP_STAT_INCR(sctps_recvnocrc);
+#else
 	if (m->m_pkthdr.csum_flags & CSUM_SCTP_VALID) {
 		SCTP_STAT_INCR(sctps_recvhwcrc);
 		goto sctp_skip_csum_4;
 	}
 	check = sh->checksum;	/* save incoming checksum */
-	if ((check == 0) && (SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback)) &&
-	    ((ip->ip_src.s_addr == ip->ip_dst.s_addr) ||
-	    (SCTP_IS_IT_LOOPBACK(m)))
-	    ) {
-		SCTP_STAT_INCR(sctps_recvnocrc);
-		goto sctp_skip_csum_4;
-	}
 	sh->checksum = 0;	/* prepare for calc */
 	calc_check = sctp_calculate_cksum(m, iphlen);
 	sh->checksum = check;
@@ -5840,6 +5839,7 @@ sctp_input_with_port(struct mbuf *i_pak, int off, uint16_t port)
 		goto bad;
 	}
 sctp_skip_csum_4:
+#endif
 	/* destination port of 0 is illegal, based on RFC2960. */
 	if (sh->dest_port == 0) {
 		SCTP_STAT_INCR(sctps_hdrops);
diff --git a/sys/netinet/sctp_os_bsd.h b/sys/netinet/sctp_os_bsd.h
index cec568d..883d6dd 100644
--- a/sys/netinet/sctp_os_bsd.h
+++ b/sys/netinet/sctp_os_bsd.h
@@ -433,20 +433,21 @@ typedef struct rtentry sctp_rtentry_t;
  */
 #define SCTP_IP_OUTPUT(result, o_pak, ro, stcb, vrf_id) \
 { \
-	int o_flgs = 0; \
-	if (stcb && stcb->sctp_ep && stcb->sctp_ep->sctp_socket) { \
-		o_flgs = IP_RAWOUTPUT | (stcb->sctp_ep->sctp_socket->so_options & SO_DONTROUTE); \
-	} else { \
-		o_flgs = IP_RAWOUTPUT; \
-	} \
+	int o_flgs = IP_RAWOUTPUT; \
+	struct sctp_tcb *local_stcb = stcb; \
+	if (local_stcb && \
+	    local_stcb->sctp_ep && \
+	    local_stcb->sctp_ep->sctp_socket) \
+		o_flgs |= local_stcb->sctp_ep->sctp_socket->so_options & SO_DONTROUTE; \
 	result = ip_output(o_pak, NULL, ro, o_flgs, 0, NULL); \
 }
 
 #define SCTP_IP6_OUTPUT(result, o_pak, ro, ifp, stcb, vrf_id) \
 { \
- 	if (stcb && stcb->sctp_ep) \
+	struct sctp_tcb *local_stcb = stcb; \
+	if (local_stcb && local_stcb->sctp_ep) \
 		result = ip6_output(o_pak, \
-				    ((struct in6pcb *)(stcb->sctp_ep))->in6p_outputopts, \
+				    ((struct in6pcb *)(local_stcb->sctp_ep))->in6p_outputopts, \
 				    (ro), 0, 0, ifp, NULL); \
 	else \
 		result = ip6_output(o_pak, NULL, (ro), 0, 0, ifp, NULL); \
diff --git a/sys/netinet/sctp_output.c b/sys/netinet/sctp_output.c
index d322d07..a9d00b8 100644
--- a/sys/netinet/sctp_output.c
+++ b/sys/netinet/sctp_output.c
@@ -3741,6 +3741,9 @@ sctp_lowlevel_chunk_output(struct sctp_inpcb *inp,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, m, packet_length);
 		if (port) {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
 			    (stcb) &&
 			    (stcb->asoc.loopback_scope))) {
@@ -3749,17 +3752,16 @@ sctp_lowlevel_chunk_output(struct sctp_inpcb *inp,
 			} else {
 				SCTP_STAT_INCR(sctps_sendnocrc);
 			}
+#endif
 			SCTP_ENABLE_UDP_CSUM(o_pak);
 		} else {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				m->m_pkthdr.csum_flags = CSUM_SCTP;
-				m->m_pkthdr.csum_data = 0;
-				SCTP_STAT_INCR(sctps_sendhwcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			m->m_pkthdr.csum_flags = CSUM_SCTP;
+			m->m_pkthdr.csum_data = 0;
+			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
 		/* send it out.  table id is taken from stcb */
 #if defined (__APPLE__) || defined(SCTP_SO_LOCK_TESTING)
@@ -4051,6 +4053,9 @@ sctp_lowlevel_chunk_output(struct sctp_inpcb *inp,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, m, packet_length);
 		if (port) {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
 			    (stcb) &&
 			    (stcb->asoc.loopback_scope))) {
@@ -4059,10 +4064,14 @@ sctp_lowlevel_chunk_output(struct sctp_inpcb *inp,
 			} else {
 				SCTP_STAT_INCR(sctps_sendnocrc);
 			}
+#endif
 			if ((udp->uh_sum = in6_cksum(o_pak, IPPROTO_UDP, sizeof(struct ip6_hdr), packet_length - sizeof(struct ip6_hdr))) == 0) {
 				udp->uh_sum = 0xffff;
 			}
 		} else {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
 			    (stcb) &&
 			    (stcb->asoc.loopback_scope))) {
@@ -4072,6 +4081,7 @@ sctp_lowlevel_chunk_output(struct sctp_inpcb *inp,
 			} else {
 				SCTP_STAT_INCR(sctps_sendnocrc);
 			}
+#endif
 		}
 		/* send it out. table id is taken from stcb */
 #if defined (__APPLE__) || defined(SCTP_SO_LOCK_TESTING)
@@ -10571,7 +10581,6 @@ sctp_send_shutdown_complete2(struct mbuf *m, int iphlen, struct sctphdr *sh,
 	if (iph_out != NULL) {
 		sctp_route_t ro;
 		int ret;
-		struct sctp_tcb *stcb = NULL;
 
 		mlen = SCTP_BUF_LEN(mout);
 		bzero(&ro, sizeof ro);
@@ -10582,17 +10591,25 @@ sctp_send_shutdown_complete2(struct mbuf *m, int iphlen, struct sctphdr *sh,
 			sctp_packet_log(mout, mlen);
 #endif
 		if (port) {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			comp_cp->sh.checksum = sctp_calculate_cksum(mout, offset_out);
 			SCTP_STAT_INCR(sctps_sendswcrc);
+#endif
 			SCTP_ENABLE_UDP_CSUM(mout);
 		} else {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			mout->m_pkthdr.csum_flags = CSUM_SCTP;
 			mout->m_pkthdr.csum_data = 0;
 			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
 		SCTP_ATTACH_CHAIN(o_pak, mout, mlen);
 		/* out it goes */
-		SCTP_IP_OUTPUT(ret, o_pak, &ro, stcb, vrf_id);
+		SCTP_IP_OUTPUT(ret, o_pak, &ro, NULL, vrf_id);
 
 		/* Free the route if we got one back */
 		if (ro.ro_rt)
@@ -10602,7 +10619,6 @@ sctp_send_shutdown_complete2(struct mbuf *m, int iphlen, struct sctphdr *sh,
 	if (ip6_out != NULL) {
 		struct route_in6 ro;
 		int ret;
-		struct sctp_tcb *stcb = NULL;
 		struct ifnet *ifp = NULL;
 
 		bzero(&ro, sizeof(ro));
@@ -10613,29 +10629,25 @@ sctp_send_shutdown_complete2(struct mbuf *m, int iphlen, struct sctphdr *sh,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, mout, mlen);
 		if (port) {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				comp_cp->sh.checksum = sctp_calculate_cksum(mout, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
-				SCTP_STAT_INCR(sctps_sendswcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			comp_cp->sh.checksum = sctp_calculate_cksum(mout, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
+			SCTP_STAT_INCR(sctps_sendswcrc);
+#endif
 			if ((udp->uh_sum = in6_cksum(o_pak, IPPROTO_UDP, sizeof(struct ip6_hdr), mlen - sizeof(struct ip6_hdr))) == 0) {
 				udp->uh_sum = 0xffff;
 			}
 		} else {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				mout->m_pkthdr.csum_flags = CSUM_SCTP;
-				mout->m_pkthdr.csum_data = 0;
-				SCTP_STAT_INCR(sctps_sendhwcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			mout->m_pkthdr.csum_flags = CSUM_SCTP;
+			mout->m_pkthdr.csum_data = 0;
+			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
-		SCTP_IP6_OUTPUT(ret, o_pak, &ro, &ifp, stcb, vrf_id);
+		SCTP_IP6_OUTPUT(ret, o_pak, &ro, &ifp, NULL, vrf_id);
 
 		/* Free the route if we got one back */
 		if (ro.ro_rt)
@@ -11632,7 +11644,6 @@ sctp_send_abort(struct mbuf *m, int iphlen, struct sctphdr *sh, uint32_t vtag,
 	}
 	if (iph_out != NULL) {
 		sctp_route_t ro;
-		struct sctp_tcb *stcb = NULL;
 		int ret;
 
 		/* zap the stack pointer to the route */
@@ -11652,15 +11663,23 @@ sctp_send_abort(struct mbuf *m, int iphlen, struct sctphdr *sh, uint32_t vtag,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, mout, len);
 		if (port) {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			abm->sh.checksum = sctp_calculate_cksum(mout, iphlen_out);
 			SCTP_STAT_INCR(sctps_sendswcrc);
+#endif
 			SCTP_ENABLE_UDP_CSUM(o_pak);
 		} else {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			mout->m_pkthdr.csum_flags = CSUM_SCTP;
 			mout->m_pkthdr.csum_data = 0;
 			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
-		SCTP_IP_OUTPUT(ret, o_pak, &ro, stcb, vrf_id);
+		SCTP_IP_OUTPUT(ret, o_pak, &ro, NULL, vrf_id);
 
 		/* Free the route if we got one back */
 		if (ro.ro_rt)
@@ -11670,7 +11689,6 @@ sctp_send_abort(struct mbuf *m, int iphlen, struct sctphdr *sh, uint32_t vtag,
 	if (ip6_out != NULL) {
 		struct route_in6 ro;
 		int ret;
-		struct sctp_tcb *stcb = NULL;
 		struct ifnet *ifp = NULL;
 
 		/* zap the stack pointer to the route */
@@ -11687,29 +11705,25 @@ sctp_send_abort(struct mbuf *m, int iphlen, struct sctphdr *sh, uint32_t vtag,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, mout, len);
 		if (port) {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				abm->sh.checksum = sctp_calculate_cksum(mout, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
-				SCTP_STAT_INCR(sctps_sendswcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			abm->sh.checksum = sctp_calculate_cksum(mout, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
+			SCTP_STAT_INCR(sctps_sendswcrc);
+#endif
 			if ((udp->uh_sum = in6_cksum(o_pak, IPPROTO_UDP, sizeof(struct ip6_hdr), len - sizeof(struct ip6_hdr))) == 0) {
 				udp->uh_sum = 0xffff;
 			}
 		} else {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				mout->m_pkthdr.csum_flags = CSUM_SCTP;
-				mout->m_pkthdr.csum_data = 0;
-				SCTP_STAT_INCR(sctps_sendhwcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			mout->m_pkthdr.csum_flags = CSUM_SCTP;
+			mout->m_pkthdr.csum_data = 0;
+			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
-		SCTP_IP6_OUTPUT(ret, o_pak, &ro, &ifp, stcb, vrf_id);
+		SCTP_IP6_OUTPUT(ret, o_pak, &ro, &ifp, NULL, vrf_id);
 
 		/* Free the route if we got one back */
 		if (ro.ro_rt)
@@ -11872,7 +11886,6 @@ sctp_send_operr_to(struct mbuf *m, int iphlen, struct mbuf *scm, uint32_t vtag,
 	}
 	if (iph_out != NULL) {
 		sctp_route_t ro;
-		struct sctp_tcb *stcb = NULL;
 		int ret;
 
 		/* zap the stack pointer to the route */
@@ -11890,15 +11903,23 @@ sctp_send_operr_to(struct mbuf *m, int iphlen, struct mbuf *scm, uint32_t vtag,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, mout, len);
 		if (port) {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			sh_out->checksum = sctp_calculate_cksum(mout, iphlen_out);
 			SCTP_STAT_INCR(sctps_sendswcrc);
+#endif
 			SCTP_ENABLE_UDP_CSUM(o_pak);
 		} else {
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
 			mout->m_pkthdr.csum_flags = CSUM_SCTP;
 			mout->m_pkthdr.csum_data = 0;
 			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
-		SCTP_IP_OUTPUT(ret, o_pak, &ro, stcb, vrf_id);
+		SCTP_IP_OUTPUT(ret, o_pak, &ro, NULL, vrf_id);
 
 		/* Free the route if we got one back */
 		if (ro.ro_rt)
@@ -11908,7 +11929,6 @@ sctp_send_operr_to(struct mbuf *m, int iphlen, struct mbuf *scm, uint32_t vtag,
 	if (ip6_out != NULL) {
 		struct route_in6 ro;
 		int ret;
-		struct sctp_tcb *stcb = NULL;
 		struct ifnet *ifp = NULL;
 
 		/* zap the stack pointer to the route */
@@ -11923,29 +11943,25 @@ sctp_send_operr_to(struct mbuf *m, int iphlen, struct mbuf *scm, uint32_t vtag,
 #endif
 		SCTP_ATTACH_CHAIN(o_pak, mout, len);
 		if (port) {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				sh_out->checksum = sctp_calculate_cksum(mout, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
-				SCTP_STAT_INCR(sctps_sendswcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			sh_out->checksum = sctp_calculate_cksum(mout, sizeof(struct ip6_hdr) + sizeof(struct udphdr));
+			SCTP_STAT_INCR(sctps_sendswcrc);
+#endif
 			if ((udp->uh_sum = in6_cksum(o_pak, IPPROTO_UDP, sizeof(struct ip6_hdr), len - sizeof(struct ip6_hdr))) == 0) {
 				udp->uh_sum = 0xffff;
 			}
 		} else {
-			if (!(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) &&
-			    (stcb) &&
-			    (stcb->asoc.loopback_scope))) {
-				mout->m_pkthdr.csum_flags = CSUM_SCTP;
-				mout->m_pkthdr.csum_data = 0;
-				SCTP_STAT_INCR(sctps_sendhwcrc);
-			} else {
-				SCTP_STAT_INCR(sctps_sendnocrc);
-			}
+#if defined(SCTP_WITH_NO_CSUM)
+			SCTP_STAT_INCR(sctps_sendnocrc);
+#else
+			mout->m_pkthdr.csum_flags = CSUM_SCTP;
+			mout->m_pkthdr.csum_data = 0;
+			SCTP_STAT_INCR(sctps_sendhwcrc);
+#endif
 		}
-		SCTP_IP6_OUTPUT(ret, o_pak, &ro, &ifp, stcb, vrf_id);
+		SCTP_IP6_OUTPUT(ret, o_pak, &ro, &ifp, NULL, vrf_id);
 
 		/* Free the route if we got one back */
 		if (ro.ro_rt)
diff --git a/sys/netinet/sctp_sysctl.c b/sys/netinet/sctp_sysctl.c
index 9ba7dd4..f4b9c77 100644
--- a/sys/netinet/sctp_sysctl.c
+++ b/sys/netinet/sctp_sysctl.c
@@ -54,7 +54,9 @@ sctp_init_sysctls()
 	SCTP_BASE_SYSCTL(sctp_ecn_enable) = SCTPCTL_ECN_ENABLE_DEFAULT;
 	SCTP_BASE_SYSCTL(sctp_ecn_nonce) = SCTPCTL_ECN_NONCE_DEFAULT;
 	SCTP_BASE_SYSCTL(sctp_strict_sacks) = SCTPCTL_STRICT_SACKS_DEFAULT;
+#if !defined(SCTP_WITH_NO_CSUM)
 	SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback) = SCTPCTL_LOOPBACK_NOCSUM_DEFAULT;
+#endif
 	SCTP_BASE_SYSCTL(sctp_strict_init) = SCTPCTL_STRICT_INIT_DEFAULT;
 	SCTP_BASE_SYSCTL(sctp_peer_chunk_oh) = SCTPCTL_PEER_CHKOH_DEFAULT;
 	SCTP_BASE_SYSCTL(sctp_max_burst_default) = SCTPCTL_MAXBURST_DEFAULT;
@@ -568,7 +570,9 @@ sysctl_sctp_check(SYSCTL_HANDLER_ARGS)
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_ecn_enable), SCTPCTL_ECN_ENABLE_MIN, SCTPCTL_ECN_ENABLE_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_ecn_nonce), SCTPCTL_ECN_NONCE_MIN, SCTPCTL_ECN_NONCE_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_strict_sacks), SCTPCTL_STRICT_SACKS_MIN, SCTPCTL_STRICT_SACKS_MAX);
+#if !defined(SCTP_WITH_NO_CSUM)
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback), SCTPCTL_LOOPBACK_NOCSUM_MIN, SCTPCTL_LOOPBACK_NOCSUM_MAX);
+#endif
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_strict_init), SCTPCTL_STRICT_INIT_MIN, SCTPCTL_STRICT_INIT_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_peer_chunk_oh), SCTPCTL_PEER_CHKOH_MIN, SCTPCTL_PEER_CHKOH_MAX);
 		RANGECHK(SCTP_BASE_SYSCTL(sctp_max_burst_default), SCTPCTL_MAXBURST_MIN, SCTPCTL_MAXBURST_MAX);
@@ -829,9 +833,11 @@ SYSCTL_PROC(_net_inet_sctp, OID_AUTO, strict_sacks, CTLTYPE_INT | CTLFLAG_RW,
     &SCTP_BASE_SYSCTL(sctp_strict_sacks), 0, sysctl_sctp_check, "IU",
     SCTPCTL_STRICT_SACKS_DESC);
 
+#if !defined(SCTP_WITH_NO_CSUM)
 SYSCTL_PROC(_net_inet_sctp, OID_AUTO, loopback_nocsum, CTLTYPE_INT | CTLFLAG_RW,
     &SCTP_BASE_SYSCTL(sctp_no_csum_on_loopback), 0, sysctl_sctp_check, "IU",
     SCTPCTL_LOOPBACK_NOCSUM_DESC);
+#endif
 
 SYSCTL_PROC(_net_inet_sctp, OID_AUTO, strict_init, CTLTYPE_INT | CTLFLAG_RW,
     &SCTP_BASE_SYSCTL(sctp_strict_init), 0, sysctl_sctp_check, "IU",
diff --git a/sys/netinet/sctp_sysctl.h b/sys/netinet/sctp_sysctl.h
index 477ee36..1140b97 100644
--- a/sys/netinet/sctp_sysctl.h
+++ b/sys/netinet/sctp_sysctl.h
@@ -45,7 +45,9 @@ struct sctp_sysctl {
 	uint32_t sctp_ecn_enable;
 	uint32_t sctp_ecn_nonce;
 	uint32_t sctp_strict_sacks;
+#if !defined(SCTP_WITH_NO_CSUM)
 	uint32_t sctp_no_csum_on_loopback;
+#endif
 	uint32_t sctp_strict_init;
 	uint32_t sctp_peer_chunk_oh;
 	uint32_t sctp_max_burst_default;