The branch main has been updated by ronald:
URL:
https://cgit.FreeBSD.org/src/commit/?id=590493c1419092e98f7ad1dcadb886973502341e
commit 590493c1419092e98f7ad1dcadb886973502341e
Author: Ronald Klop <ron...@freebsd.org>
AuthorDate: 2025-07-03 16:33:03 +0000
Commit: Ronald Klop <ron...@freebsd.org>
CommitDate: 2025-08-05 14:53:04 +0000
if_epair(4): use ether_gen_addr(9) for stable MAC address
Before this change epair interfaces get a random MAC. This does
not help dhcp/dyndns when an epair gets destroyed/recreated
after restart of a jail.
With this change:
$ sysctl net.link.epair.ether_gen_addr=0
$ ifconfig epair8 create > /dev/null; ifconfig epair8a | grep ether;
ifconfig epair8b | grep ether; ifconfig epair8a destroy
ether 02:cb:78:56:e4:0a
ether 02:cb:78:56:e4:0b
$ ifconfig epair8 create > /dev/null; ifconfig epair8a | grep ether;
ifconfig epair8b | grep ether; ifconfig epair8a destroy
ether 02:8b:9b:6a:8f:0a
ether 02:8b:9b:6a:8f:0b
$ sysctl net.link.epair.ether_gen_addr=1
$ ifconfig epair8 create > /dev/null; ifconfig epair8a | grep ether;
ifconfig epair8b | grep ether; ifconfig epair8a destroy
ether 58:9c:fc:10:2b:b4
ether 58:9c:fc:00:39:10
$ ifconfig epair8 create > /dev/null; ifconfig epair8a | grep ether;
ifconfig epair8b | grep ether; ifconfig epair8a destroy
ether 58:9c:fc:10:2b:b4
ether 58:9c:fc:00:39:10
A follow up commit will change the default to 1 in main.
Approved by: bz,ivy,kp
MFC after: 2 weeks
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D51157
---
sys/net/if_epair.c | 35 +++++++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)
diff --git a/sys/net/if_epair.c b/sys/net/if_epair.c
index 7051e31565d4..4d35584925a1 100644
--- a/sys/net/if_epair.c
+++ b/sys/net/if_epair.c
@@ -58,6 +58,7 @@
#include <sys/smp.h>
#include <sys/socket.h>
#include <sys/sockio.h>
+#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <net/bpf.h>
@@ -97,6 +98,15 @@ static unsigned int next_index = 0;
#define EPAIR_LOCK() mtx_lock(&epair_n_index_mtx)
#define EPAIR_UNLOCK() mtx_unlock(&epair_n_index_mtx)
+SYSCTL_DECL(_net_link);
+static SYSCTL_NODE(_net_link, OID_AUTO, epair, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
+ "Pair of virtual cross-over connected Ethernet-like interfaces");
+
+static bool use_ether_gen_addr = false;
+SYSCTL_BOOL(_net_link_epair, OID_AUTO, ether_gen_addr, CTLFLAG_RWTUN,
+ &use_ether_gen_addr, false,
+ "Generate MAC with FreeBSD OUI using ether_gen_addr(9)");
+
struct epair_softc;
struct epair_queue {
struct mtx mtx;
@@ -495,6 +505,17 @@ epair_clone_match(struct if_clone *ifc, const char *name)
return (1);
}
+static void
+epair_generate_mac_byname(struct epair_softc *sc, uint8_t eaddr[])
+{
+ struct ether_addr gen_eaddr;
+ int i;
+
+ ether_gen_addr_byname(if_name(sc->ifp), &gen_eaddr);
+ for (i = 0; i < ETHER_ADDR_LEN; i++)
+ eaddr[i] = gen_eaddr.octet[i];
+}
+
static void
epair_clone_add(struct if_clone *ifc, struct epair_softc *scb)
{
@@ -502,9 +523,12 @@ epair_clone_add(struct if_clone *ifc, struct epair_softc
*scb)
uint8_t eaddr[ETHER_ADDR_LEN]; /* 00:00:00:00:00:00 */
ifp = scb->ifp;
- /* Copy epairNa etheraddr and change the last byte. */
- memcpy(eaddr, scb->oifp->if_hw_addr, ETHER_ADDR_LEN);
- eaddr[5] = 0x0b;
+ if (!use_ether_gen_addr) {
+ /* Copy epairNa etheraddr and change the last byte. */
+ memcpy(eaddr, scb->oifp->if_hw_addr, ETHER_ADDR_LEN);
+ eaddr[5] = 0x0b;
+ } else
+ epair_generate_mac_byname(scb, eaddr);
ether_ifattach(ifp, eaddr);
if_clone_addif(ifc, ifp);
@@ -719,7 +743,10 @@ epair_clone_create(struct if_clone *ifc, char *name,
size_t len,
/* Finish initialization of interface <n>a. */
ifp = sca->ifp;
epair_setup_ifp(sca, name, unit);
- epair_generate_mac(sca, eaddr);
+ if (!use_ether_gen_addr)
+ epair_generate_mac(sca, eaddr);
+ else
+ epair_generate_mac_byname(sca, eaddr);
ether_ifattach(ifp, eaddr);
