ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 246 insertions, 0 deletions

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 <Jason@zx2c4.com>. 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);
+}