svn commit: r365869 - in head/sys: netinet netinet6
Navdeep Parhar
np at FreeBSD.org
Fri Sep 18 02:21:16 UTC 2020
Author: np
Date: Fri Sep 18 02:21:15 2020
New Revision: 365869
URL: https://svnweb.freebsd.org/changeset/base/365869
Log:
Add a knob to allow zero UDP checksums for UDP/IPv6 traffic on the given UDP port.
This will be used by some upcoming changes to if_vxlan(4). RFC 7348 (VXLAN)
says that the UDP checksum "SHOULD be transmitted as zero. When a packet is
received with a UDP checksum of zero, it MUST be accepted for decapsulation."
But the original IPv6 RFCs did not allow zero UDP checksum. RFC 6935 attempts
to resolve this.
Reviewed by: kib@
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D25873
Modified:
head/sys/netinet/udp_var.h
head/sys/netinet6/udp6_usrreq.c
Modified: head/sys/netinet/udp_var.h
==============================================================================
--- head/sys/netinet/udp_var.h Fri Sep 18 02:10:28 2020 (r365868)
+++ head/sys/netinet/udp_var.h Fri Sep 18 02:21:15 2020 (r365869)
@@ -154,6 +154,9 @@ VNET_DECLARE(int, udp_log_in_vain);
#define V_udp_blackhole VNET(udp_blackhole)
#define V_udp_log_in_vain VNET(udp_log_in_vain)
+VNET_DECLARE(int, zero_checksum_port);
+#define V_zero_checksum_port VNET(zero_checksum_port)
+
static __inline struct inpcbinfo *
udp_get_inpcbinfo(int protocol)
{
Modified: head/sys/netinet6/udp6_usrreq.c
==============================================================================
--- head/sys/netinet6/udp6_usrreq.c Fri Sep 18 02:10:28 2020 (r365868)
+++ head/sys/netinet6/udp6_usrreq.c Fri Sep 18 02:21:15 2020 (r365869)
@@ -124,6 +124,11 @@ __FBSDID("$FreeBSD$");
#include <security/mac/mac_framework.h>
+VNET_DEFINE(int, zero_checksum_port) = 0;
+#define V_zero_checksum_port VNET(zero_checksum_port)
+SYSCTL_INT(_net_inet6_udp6, OID_AUTO, rfc6935_port, CTLFLAG_VNET | CTLFLAG_RW,
+ &VNET_NAME(zero_checksum_port), 0,
+ "Zero UDP checksum allowed for traffic to/from this port.");
/*
* UDP protocol implementation.
* Per RFC 768, August, 1980.
@@ -267,7 +272,14 @@ udp6_input(struct mbuf **mp, int *offp, int proto)
}
if (uh->uh_sum == 0) {
UDPSTAT_INC(udps_nosum);
- goto badunlocked;
+ /*
+ * dport 0 was rejected earlier so this is OK even if
+ * zero_checksum_port is 0 (which is its default value).
+ */
+ if (ntohs(uh->uh_dport) == V_zero_checksum_port)
+ goto skip_checksum;
+ else
+ goto badunlocked;
}
}
@@ -287,6 +299,7 @@ udp6_input(struct mbuf **mp, int *offp, int proto)
goto badunlocked;
}
+skip_checksum:
/*
* Construct sockaddr format source address.
*/
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