From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- drivers/net/wireguard/timers.c | 246 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 246 insertions(+) create mode 100644 drivers/net/wireguard/timers.c (limited to 'drivers/net/wireguard/timers.c') diff --git a/drivers/net/wireguard/timers.c b/drivers/net/wireguard/timers.c new file mode 100644 index 000000000..4016a3065 --- /dev/null +++ b/drivers/net/wireguard/timers.c @@ -0,0 +1,246 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015-2019 Jason A. Donenfeld . All Rights Reserved. + */ + +#include "timers.h" +#include "device.h" +#include "peer.h" +#include "queueing.h" +#include "socket.h" + +/* + * - Timer for retransmitting the handshake if we don't hear back after + * `REKEY_TIMEOUT + jitter` ms. + * + * - Timer for sending empty packet if we have received a packet but after have + * not sent one for `KEEPALIVE_TIMEOUT` ms. + * + * - Timer for initiating new handshake if we have sent a packet but after have + * not received one (even empty) for `(KEEPALIVE_TIMEOUT + REKEY_TIMEOUT) + + * jitter` ms. + * + * - Timer for zeroing out all ephemeral keys after `(REJECT_AFTER_TIME * 3)` ms + * if no new keys have been received. + * + * - Timer for, if enabled, sending an empty authenticated packet every user- + * specified seconds. + */ + +static inline void mod_peer_timer(struct wg_peer *peer, + struct timer_list *timer, + unsigned long expires) +{ + rcu_read_lock_bh(); + if (likely(netif_running(peer->device->dev) && + !READ_ONCE(peer->is_dead))) + mod_timer(timer, expires); + rcu_read_unlock_bh(); +} + +static void wg_expired_retransmit_handshake(struct timer_list *timer) +{ + struct wg_peer *peer = timer_container_of(peer, timer, + timer_retransmit_handshake); + + if (peer->timer_handshake_attempts > MAX_TIMER_HANDSHAKES) { + pr_debug("%s: Handshake for peer %llu (%pISpfsc) did not complete after %d attempts, giving up\n", + peer->device->dev->name, peer->internal_id, + &peer->endpoint.addr, (int)MAX_TIMER_HANDSHAKES + 2); + + timer_delete(&peer->timer_send_keepalive); + /* We drop all packets without a keypair and don't try again, + * if we try unsuccessfully for too long to make a handshake. + */ + wg_packet_purge_staged_packets(peer); + + /* We set a timer for destroying any residue that might be left + * of a partial exchange. + */ + if (!timer_pending(&peer->timer_zero_key_material)) + mod_peer_timer(peer, &peer->timer_zero_key_material, + jiffies + REJECT_AFTER_TIME * 3 * HZ); + } else { + ++peer->timer_handshake_attempts; + pr_debug("%s: Handshake for peer %llu (%pISpfsc) did not complete after %d seconds, retrying (try %d)\n", + peer->device->dev->name, peer->internal_id, + &peer->endpoint.addr, (int)REKEY_TIMEOUT, + peer->timer_handshake_attempts + 1); + + /* We clear the endpoint address src address, in case this is + * the cause of trouble. + */ + wg_socket_clear_peer_endpoint_src(peer); + + wg_packet_send_queued_handshake_initiation(peer, true); + } +} + +static void wg_expired_send_keepalive(struct timer_list *timer) +{ + struct wg_peer *peer = timer_container_of(peer, timer, + timer_send_keepalive); + + wg_packet_send_keepalive(peer); + if (peer->timer_need_another_keepalive) { + peer->timer_need_another_keepalive = false; + mod_peer_timer(peer, &peer->timer_send_keepalive, + jiffies + KEEPALIVE_TIMEOUT * HZ); + } +} + +static void wg_expired_new_handshake(struct timer_list *timer) +{ + struct wg_peer *peer = timer_container_of(peer, timer, + timer_new_handshake); + + pr_debug("%s: Retrying handshake with peer %llu (%pISpfsc) because we stopped hearing back after %d seconds\n", + peer->device->dev->name, peer->internal_id, + &peer->endpoint.addr, (int)(KEEPALIVE_TIMEOUT + REKEY_TIMEOUT)); + /* We clear the endpoint address src address, in case this is the cause + * of trouble. + */ + wg_socket_clear_peer_endpoint_src(peer); + wg_packet_send_queued_handshake_initiation(peer, false); +} + +static void wg_expired_zero_key_material(struct timer_list *timer) +{ + struct wg_peer *peer = timer_container_of(peer, timer, + timer_zero_key_material); + + rcu_read_lock_bh(); + if (!READ_ONCE(peer->is_dead)) { + wg_peer_get(peer); + if (!queue_work(peer->device->handshake_send_wq, + &peer->clear_peer_work)) + /* If the work was already on the queue, we want to drop + * the extra reference. + */ + wg_peer_put(peer); + } + rcu_read_unlock_bh(); +} + +static void wg_queued_expired_zero_key_material(struct work_struct *work) +{ + struct wg_peer *peer = container_of(work, struct wg_peer, + clear_peer_work); + + pr_debug("%s: Zeroing out all keys for peer %llu (%pISpfsc), since we haven't received a new one in %d seconds\n", + peer->device->dev->name, peer->internal_id, + &peer->endpoint.addr, (int)REJECT_AFTER_TIME * 3); + wg_noise_handshake_clear(&peer->handshake); + wg_noise_keypairs_clear(&peer->keypairs); + wg_peer_put(peer); +} + +static void wg_expired_send_persistent_keepalive(struct timer_list *timer) +{ + struct wg_peer *peer = timer_container_of(peer, timer, + timer_persistent_keepalive); + + if (likely(peer->persistent_keepalive_interval)) + wg_packet_send_keepalive(peer); +} + +/* Should be called after an authenticated data packet is sent. */ +void wg_timers_data_sent(struct wg_peer *peer) +{ + if (!timer_pending(&peer->timer_new_handshake)) + mod_peer_timer(peer, &peer->timer_new_handshake, + jiffies + (KEEPALIVE_TIMEOUT + REKEY_TIMEOUT) * HZ + + get_random_u32_below(REKEY_TIMEOUT_JITTER_MAX_JIFFIES)); +} + +/* Should be called after an authenticated data packet is received. */ +void wg_timers_data_received(struct wg_peer *peer) +{ + if (likely(netif_running(peer->device->dev))) { + if (!timer_pending(&peer->timer_send_keepalive)) + mod_peer_timer(peer, &peer->timer_send_keepalive, + jiffies + KEEPALIVE_TIMEOUT * HZ); + else + peer->timer_need_another_keepalive = true; + } +} + +/* Should be called after any type of authenticated packet is sent, whether + * keepalive, data, or handshake. + */ +void wg_timers_any_authenticated_packet_sent(struct wg_peer *peer) +{ + timer_delete(&peer->timer_send_keepalive); +} + +/* Should be called after any type of authenticated packet is received, whether + * keepalive, data, or handshake. + */ +void wg_timers_any_authenticated_packet_received(struct wg_peer *peer) +{ + timer_delete(&peer->timer_new_handshake); +} + +/* Should be called after a handshake initiation message is sent. */ +void wg_timers_handshake_initiated(struct wg_peer *peer) +{ + mod_peer_timer(peer, &peer->timer_retransmit_handshake, + jiffies + REKEY_TIMEOUT * HZ + + get_random_u32_below(REKEY_TIMEOUT_JITTER_MAX_JIFFIES)); +} + +/* Should be called after a handshake response message is received and processed + * or when getting key confirmation via the first data message. + */ +void wg_timers_handshake_complete(struct wg_peer *peer) +{ + timer_delete(&peer->timer_retransmit_handshake); + peer->timer_handshake_attempts = 0; + peer->sent_lastminute_handshake = false; + ktime_get_real_ts64(&peer->walltime_last_handshake); +} + +/* Should be called after an ephemeral key is created, which is before sending a + * handshake response or after receiving a handshake response. + */ +void wg_timers_session_derived(struct wg_peer *peer) +{ + mod_peer_timer(peer, &peer->timer_zero_key_material, + jiffies + REJECT_AFTER_TIME * 3 * HZ); +} + +/* Should be called before a packet with authentication, whether + * keepalive, data, or handshakem is sent, or after one is received. + */ +void wg_timers_any_authenticated_packet_traversal(struct wg_peer *peer) +{ + if (peer->persistent_keepalive_interval) + mod_peer_timer(peer, &peer->timer_persistent_keepalive, + jiffies + peer->persistent_keepalive_interval * HZ); +} + +void wg_timers_init(struct wg_peer *peer) +{ + timer_setup(&peer->timer_retransmit_handshake, + wg_expired_retransmit_handshake, 0); + timer_setup(&peer->timer_send_keepalive, wg_expired_send_keepalive, 0); + timer_setup(&peer->timer_new_handshake, wg_expired_new_handshake, 0); + timer_setup(&peer->timer_zero_key_material, + wg_expired_zero_key_material, 0); + timer_setup(&peer->timer_persistent_keepalive, + wg_expired_send_persistent_keepalive, 0); + INIT_WORK(&peer->clear_peer_work, wg_queued_expired_zero_key_material); + peer->timer_handshake_attempts = 0; + peer->sent_lastminute_handshake = false; + peer->timer_need_another_keepalive = false; +} + +void wg_timers_stop(struct wg_peer *peer) +{ + timer_delete_sync(&peer->timer_retransmit_handshake); + timer_delete_sync(&peer->timer_send_keepalive); + timer_delete_sync(&peer->timer_new_handshake); + timer_delete_sync(&peer->timer_zero_key_material); + timer_delete_sync(&peer->timer_persistent_keepalive); + flush_work(&peer->clear_peer_work); +} -- cgit v1.3.1