Date: Thu, 05 Mar 2026 11:12:51 +0000 From: Olivier Cochard <olivier@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 9f71153aec0c - main - carp: fix global demotion counter to VRRP advertisements Message-ID: <69a96533.3eacf.766f5032@gitrepo.freebsd.org>
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The branch main has been updated by olivier: URL: https://cgit.FreeBSD.org/src/commit/?id=9f71153aec0cb455cd49af6d4ca7e4c16fd45d7a commit 9f71153aec0cb455cd49af6d4ca7e4c16fd45d7a Author: Olivier Cochard <olivier@FreeBSD.org> AuthorDate: 2026-03-05 11:02:20 +0000 Commit: Olivier Cochard <olivier@FreeBSD.org> CommitDate: 2026-03-05 11:02:20 +0000 carp: fix global demotion counter to VRRP advertisements When net.inet.carp.preempt=1 and a physical interface goes down, the global V_carp_demotion counter is incremented. For CARP this was already reflected in outgoing advertisements via DEMOTE_ADVSKEW(), but VRRP sent the raw sc_vrrp_prio unchanged, so demotion had no effect. Add DEMOTE_VRRP_PRIO(), a macro analogous to DEMOTE_ADVSKEW(): It subtracts V_carp_demotion from the configured priority and clamps the result to [0, 254]. Priority 0 is VRRPv3's "resign" signal and causes backups to preempt immediately. Priority 255 (IP address owner) is never demoted. Reviewed by: kp Approved by: kp Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D55558 --- sys/netinet/ip_carp.c | 17 ++++++++++--- tests/sys/netinet/carp.sh | 61 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+), 3 deletions(-) diff --git a/sys/netinet/ip_carp.c b/sys/netinet/ip_carp.c index d33ac4e9a154..3fedbda6b57f 100644 --- a/sys/netinet/ip_carp.c +++ b/sys/netinet/ip_carp.c @@ -331,6 +331,17 @@ SYSCTL_VNET_PCPUSTAT(_net_inet_carp, OID_AUTO, stats, struct carpstats, (((sc)->sc_advskew + V_carp_demotion < 0) ? \ 0 : ((sc)->sc_advskew + V_carp_demotion))) +/* + * VRRPv3 priority is the inverse of CARP advskew: higher is better. + * Subtract the global demotion counter and clamp to [0, 254]. + * Priority 255 (IP address owner) is never demoted. + */ +#define DEMOTE_VRRP_PRIO(sc) \ + ((sc)->sc_vrrp_prio == 255 ? 255 : \ + (((int)(sc)->sc_vrrp_prio - V_carp_demotion < 0) ? 0 : \ + (((int)(sc)->sc_vrrp_prio - V_carp_demotion > 254) ? 254 : \ + (int)(sc)->sc_vrrp_prio - V_carp_demotion))) + static void carp_input_c(struct mbuf *, struct carp_header *, sa_family_t, int); static void vrrp_input_c(struct mbuf *, int, sa_family_t, int, int, uint16_t); static struct carp_softc @@ -1009,7 +1020,7 @@ vrrp_input_c(struct mbuf *m, int off, sa_family_t af, int ttl, * Same if the peer has a higher priority than us. */ if (ntohs(vh->vrrp_max_adver_int) < sc->sc_vrrp_adv_inter || - vh->vrrp_priority > sc->sc_vrrp_prio) { + vh->vrrp_priority > DEMOTE_VRRP_PRIO(sc)) { callout_stop(&sc->sc_ad_tmo); carp_set_state(sc, BACKUP, "more frequent advertisement received"); @@ -1023,7 +1034,7 @@ vrrp_input_c(struct mbuf *m, int off, sa_family_t af, int ttl, * and this one claims to be slower, treat him as down. */ if (V_carp_preempt && (ntohs(vh->vrrp_max_adver_int) > sc->sc_vrrp_adv_inter - || vh->vrrp_priority < sc->sc_vrrp_prio)) { + || vh->vrrp_priority < DEMOTE_VRRP_PRIO(sc))) { carp_master_down_locked(sc, "preempting a slower master"); break; @@ -1359,7 +1370,7 @@ vrrp_send_ad_locked(struct carp_softc *sc) .vrrp_version = CARP_VERSION_VRRPv3, .vrrp_type = VRRP_TYPE_ADVERTISEMENT, .vrrp_vrtid = sc->sc_vhid, - .vrrp_priority = sc->sc_vrrp_prio, + .vrrp_priority = DEMOTE_VRRP_PRIO(sc), .vrrp_count_addr = 0, .vrrp_max_adver_int = htons(sc->sc_vrrp_adv_inter), .vrrp_checksum = 0, diff --git a/tests/sys/netinet/carp.sh b/tests/sys/netinet/carp.sh index 90ed9d6f9baf..e0ef2fd97583 100755 --- a/tests/sys/netinet/carp.sh +++ b/tests/sys/netinet/carp.sh @@ -497,6 +497,66 @@ negative_demotion_cleanup() vnet_cleanup } +atf_test_case "vrrp_preempt" "cleanup" +vrrp_preempt_head() +{ + atf_set descr 'Test VRRP preemption' + atf_set require.user root +} + +vrrp_preempt_body() +{ + carp_init + + epair1=$(vnet_mkepair) + epair2=$(vnet_mkepair) + + vnet_mkjail one ${epair1}a ${epair2}a + jexec one sysctl net.inet.carp.preempt=1 + jexec one ifconfig ${epair1}a 192.0.2.1/24 up + jexec one ifconfig ${epair1}a add vhid 1 carpver 3 192.0.2.254/24 \ + vrrpprio 10 pass foobar1 + jexec one ifconfig ${epair2}a 192.0.3.1/24 up + jexec one ifconfig ${epair2}a add vhid 2 carpver 3 192.0.3.254/24 \ + vrrpprio 10 pass foobar2 + + vnet_mkjail two ${epair1}b ${epair2}b + jexec two sysctl net.inet.carp.preempt=1 + jexec two ifconfig ${epair1}b 192.0.2.2/24 up + jexec two ifconfig ${epair2}b 192.0.3.2/24 up + jexec two ifconfig ${epair1}b add vhid 1 carpver 3 192.0.2.254/24 \ + vrrpprio 1 pass foobar1 + jexec two ifconfig ${epair2}b add vhid 2 carpver 3 192.0.3.254/24 \ + vrrpprio 1 pass foobar2 + + # Allow things to settle + wait_for_carp one ${epair1}a two ${epair1}b + wait_for_carp one ${epair2}a two ${epair2}b + + # Bring down one interface; preemption should demote the second interface too + jexec one ifconfig ${epair1}a down + sleep 3 + + if is_master one ${epair2}a + then + atf_fail "preemption did not affect the second interface" + fi + + # Bring interface back up; one should reclaim master + jexec one ifconfig ${epair1}a up + sleep 3 + + if ! is_master one ${epair2}a + then + atf_fail "Priority router did not take its master role back" + fi +} + +vrrp_preempt_cleanup() +{ + vnet_cleanup +} + atf_test_case "nd6_ns_source_mac" "cleanup" @@ -596,5 +656,6 @@ atf_init_test_cases() atf_add_test_case "unicast_ll_v6" atf_add_test_case "negative_demotion" atf_add_test_case "nd6_ns_source_mac" + atf_add_test_case "vrrp_preempt" atf_add_test_case "switch" }home | help
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