Module Name: src
Committed By: riastradh
Date: Sun Jul 28 14:40:02 UTC 2024
Modified Files:
src/sys/net: if_wg.c
Log Message:
wg(4): Fix session destruction.
Schedule destruction as soon as the session is created, to ensure key
erasure within 2*reject-after-time seconds. Previously, we would
schedule destruction of the previous session 1 second after the next
one has been established. Combined with a failure to update the
state machine on keepalive packets, this led to temporary deadlock
scenarios.
To keep it simple, there's just one callout which runs every
reject-after-time seconds and erases keys in sessions older than
reject-after-time, so if a session is established the moment after it
runs, the keys might not be erased until (2-eps)*reject-after-time
seconds.
PR kern/55729: net/if_wg/t_misc:wg_rekey test case fails
PR kern/56252: wg(4) state machine has race conditions
PR kern/58463: if_wg does not work when idle.
To generate a diff of this commit:
cvs rdiff -u -r1.99 -r1.100 src/sys/net/if_wg.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/net/if_wg.c
diff -u src/sys/net/if_wg.c:1.99 src/sys/net/if_wg.c:1.100
--- src/sys/net/if_wg.c:1.99 Sun Jul 28 14:39:35 2024
+++ src/sys/net/if_wg.c Sun Jul 28 14:40:02 2024
@@ -1,4 +1,4 @@
-/* $NetBSD: if_wg.c,v 1.99 2024/07/28 14:39:35 riastradh Exp $ */
+/* $NetBSD: if_wg.c,v 1.100 2024/07/28 14:40:02 riastradh Exp $ */
/*
* Copyright (C) Ryota Ozaki <[email protected]>
@@ -41,7 +41,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.99 2024/07/28 14:39:35 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_wg.c,v 1.100 2024/07/28 14:40:02 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_altq_enabled.h"
@@ -1346,7 +1346,6 @@ wg_put_session_index(struct wg_softc *wg
struct wg_peer *wgp __diagused = wgs->wgs_peer;
KASSERT(mutex_owned(wgp->wgp_lock));
- KASSERT(wgs == wgp->wgp_session_unstable);
KASSERT(wgs->wgs_state != WGS_STATE_UNKNOWN);
KASSERT(wgs->wgs_state != WGS_STATE_ESTABLISHED);
@@ -1651,7 +1650,6 @@ wg_handle_msg_init(struct wg_softc *wg,
panic("unstable session can't be established");
case WGS_STATE_DESTROYING: /* rekey initiated by peer */
WG_TRACE("Session destroying, but force to clear");
- callout_halt(&wgp->wgp_session_dtor_timer, NULL);
wg_put_session_index(wg, wgs);
KASSERTMSG(wgs->wgs_state == WGS_STATE_UNKNOWN, "state=%d",
wgs->wgs_state);
@@ -1675,6 +1673,15 @@ wg_handle_msg_init(struct wg_softc *wg,
wg_update_endpoint_if_necessary(wgp, src);
/*
+ * Count the time of the INIT message as the time of
+ * establishment -- this is used to decide when to erase keys,
+ * and we want to start counting as soon as we have generated
+ * keys.
+ */
+ wgs->wgs_time_established = time_uptime;
+ wg_schedule_session_dtor_timer(wgp);
+
+ /*
* Respond to the initiator with our ephemeral public key.
*/
(void)wg_send_handshake_msg_resp(wg, wgp, wgs, wgmi);
@@ -2109,6 +2116,7 @@ wg_handle_msg_resp(struct wg_softc *wg,
KASSERTMSG(wgs->wgs_state == WGS_STATE_INIT_ACTIVE, "state=%d",
wgs->wgs_state);
wgs->wgs_time_established = time_uptime;
+ wg_schedule_session_dtor_timer(wgp);
wgs->wgs_time_last_data_sent = 0;
wgs->wgs_is_initiator = true;
WG_DLOG("session[L=%"PRIx32" R=%"PRIx32"]:"
@@ -2179,9 +2187,6 @@ wg_handle_msg_resp(struct wg_softc *wg,
wgs_prev->wgs_local_index, wgs_prev->wgs_remote_index);
atomic_store_relaxed(&wgs_prev->wgs_state,
WGS_STATE_DESTROYING);
-
- /* We can't destroy the old session immediately */
- wg_schedule_session_dtor_timer(wgp);
} else {
KASSERTMSG(wgs_prev->wgs_state == WGS_STATE_UNKNOWN,
"state=%d", wgs_prev->wgs_state);
@@ -2604,6 +2609,7 @@ wg_session_dtor_timer(void *arg)
WG_TRACE("enter");
+ wg_schedule_session_dtor_timer(wgp);
wg_schedule_peer_task(wgp, WGP_TASK_DESTROY_PREV_SESSION);
}
@@ -2611,8 +2617,19 @@ static void
wg_schedule_session_dtor_timer(struct wg_peer *wgp)
{
- /* 1 second grace period */
- callout_schedule(&wgp->wgp_session_dtor_timer, hz);
+ /*
+ * If the periodic session destructor is already pending to
+ * handle the previous session, that's fine -- leave it in
+ * place; it will be scheduled again.
+ */
+ if (callout_pending(&wgp->wgp_session_dtor_timer)) {
+ WG_DLOG("session dtor already pending\n");
+ return;
+ }
+
+ WG_DLOG("scheduling session dtor in %u secs\n", wg_reject_after_time);
+ callout_schedule(&wgp->wgp_session_dtor_timer,
+ wg_reject_after_time*hz);
}
static bool
@@ -3205,7 +3222,6 @@ wg_task_establish_session(struct wg_soft
/* XXX Can this happen? */
return;
- wgs->wgs_time_established = time_uptime;
wgs->wgs_time_last_data_sent = 0;
wgs->wgs_is_initiator = false;
@@ -3265,9 +3281,6 @@ wg_task_establish_session(struct wg_soft
wgs_prev->wgs_local_index, wgs_prev->wgs_remote_index);
atomic_store_relaxed(&wgs_prev->wgs_state,
WGS_STATE_DESTROYING);
-
- /* We can't destroy the old session immediately */
- wg_schedule_session_dtor_timer(wgp);
} else {
KASSERTMSG(wgs_prev->wgs_state == WGS_STATE_UNKNOWN,
"state=%d", wgs_prev->wgs_state);
@@ -3321,15 +3334,61 @@ static void
wg_task_destroy_prev_session(struct wg_softc *wg, struct wg_peer *wgp)
{
struct wg_session *wgs;
+ time_t age;
WG_TRACE("WGP_TASK_DESTROY_PREV_SESSION");
KASSERT(mutex_owned(wgp->wgp_lock));
+ /*
+ * If theres's any previous unstable session, i.e., one that
+ * was ESTABLISHED and is now DESTROYING, older than
+ * reject-after-time, destroy it. Upcoming sessions are still
+ * in INIT_ACTIVE or INIT_PASSIVE -- we don't touch those here.
+ */
wgs = wgp->wgp_session_unstable;
- if (wgs->wgs_state == WGS_STATE_DESTROYING) {
+ KASSERT(wgs->wgs_state != WGS_STATE_ESTABLISHED);
+ if (wgs->wgs_state == WGS_STATE_DESTROYING &&
+ ((age = (time_uptime - wgs->wgs_time_established)) >=
+ wg_reject_after_time)) {
+ WG_DLOG("destroying past session %"PRIuMAX" sec old\n",
+ (uintmax_t)age);
wg_put_session_index(wg, wgs);
+ KASSERTMSG(wgs->wgs_state == WGS_STATE_UNKNOWN, "state=%d",
+ wgs->wgs_state);
+ }
+
+ /*
+ * If theres's any ESTABLISHED stable session older than
+ * reject-after-time, destroy it. (The stable session can also
+ * be in UNKNOWN state -- nothing to do in that case)
+ */
+ wgs = wgp->wgp_session_stable;
+ KASSERT(wgs->wgs_state != WGS_STATE_INIT_ACTIVE);
+ KASSERT(wgs->wgs_state != WGS_STATE_INIT_PASSIVE);
+ KASSERT(wgs->wgs_state != WGS_STATE_DESTROYING);
+ if (wgs->wgs_state == WGS_STATE_ESTABLISHED &&
+ ((age = (time_uptime - wgs->wgs_time_established)) >=
+ wg_reject_after_time)) {
+ WG_DLOG("destroying current session %"PRIuMAX" sec old\n",
+ (uintmax_t)age);
+ atomic_store_relaxed(&wgs->wgs_state, WGS_STATE_DESTROYING);
+ wg_put_session_index(wg, wgs);
+ KASSERTMSG(wgs->wgs_state == WGS_STATE_UNKNOWN, "state=%d",
+ wgs->wgs_state);
}
+
+ /*
+ * If there's no sessions left, no need to have the timer run
+ * until the next time around -- halt it.
+ *
+ * It is only ever scheduled with wgp_lock held or in the
+ * callout itself, and callout_halt prevents rescheudling
+ * itself, so this never races with rescheduling.
+ */
+ if (wgp->wgp_session_unstable->wgs_state == WGS_STATE_UNKNOWN &&
+ wgp->wgp_session_stable->wgs_state == WGS_STATE_UNKNOWN)
+ callout_halt(&wgp->wgp_session_dtor_timer, NULL);
}
static void
