Merge branch 'wireguard-fixes-for-6-9-rc1'

Jason A. Donenfeld says:

====================
wireguard fixes for 6.9-rc1

This series has four WireGuard fixes:

1) Annotate a data race that KCSAN found by using READ_ONCE/WRITE_ONCE,
   which has been causing syzkaller noise.

2) Use the generic netdev tstats allocation and stats getters instead of
   doing this within the driver.

3) Explicitly check a flag variable instead of an empty list in the
   netlink code, to prevent a UaF situation when paging through GET
   results during a remove-all SET operation.

4) Set a flag in the RISC-V CI config so the selftests continue to boot.
====================

Link: https://lore.kernel.org/r/20240314224911.6653-1-Jason@zx2c4.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

5 files changed, 12 insertions, 17 deletions

diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c
index deb9636b0ecf8f..3feb36ee5bfb44 100644
--- a/drivers/net/wireguard/device.c
+++ b/drivers/net/wireguard/device.c
@@ -237,7 +237,6 @@ static const struct net_device_ops netdev_ops = {
 	.ndo_open		= wg_open,
 	.ndo_stop		= wg_stop,
 	.ndo_start_xmit		= wg_xmit,
-	.ndo_get_stats64	= dev_get_tstats64
 };
 
 static void wg_destruct(struct net_device *dev)
@@ -262,7 +261,6 @@ static void wg_destruct(struct net_device *dev)
 	rcu_barrier(); /* Wait for all the peers to be actually freed. */
 	wg_ratelimiter_uninit();
 	memzero_explicit(&wg->static_identity, sizeof(wg->static_identity));
-	free_percpu(dev->tstats);
 	kvfree(wg->index_hashtable);
 	kvfree(wg->peer_hashtable);
 	mutex_unlock(&wg->device_update_lock);
@@ -297,6 +295,7 @@ static void wg_setup(struct net_device *dev)
 	dev->hw_enc_features |= WG_NETDEV_FEATURES;
 	dev->mtu = ETH_DATA_LEN - overhead;
 	dev->max_mtu = round_down(INT_MAX, MESSAGE_PADDING_MULTIPLE) - overhead;
+	dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
 
 	SET_NETDEV_DEVTYPE(dev, &device_type);
 
@@ -331,14 +330,10 @@ static int wg_newlink(struct net *src_net, struct net_device *dev,
 	if (!wg->index_hashtable)
 		goto err_free_peer_hashtable;
 
-	dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
-	if (!dev->tstats)
-		goto err_free_index_hashtable;
-
 	wg->handshake_receive_wq = alloc_workqueue("wg-kex-%s",
 			WQ_CPU_INTENSIVE | WQ_FREEZABLE, 0, dev->name);
 	if (!wg->handshake_receive_wq)
-		goto err_free_tstats;
+		goto err_free_index_hashtable;
 
 	wg->handshake_send_wq = alloc_workqueue("wg-kex-%s",
 			WQ_UNBOUND | WQ_FREEZABLE, 0, dev->name);
@@ -397,8 +392,6 @@ err_destroy_handshake_send:
 	destroy_workqueue(wg->handshake_send_wq);
 err_destroy_handshake_receive:
 	destroy_workqueue(wg->handshake_receive_wq);
-err_free_tstats:
-	free_percpu(dev->tstats);
 err_free_index_hashtable:
 	kvfree(wg->index_hashtable);
 err_free_peer_hashtable:
diff --git a/drivers/net/wireguard/netlink.c b/drivers/net/wireguard/netlink.c
index e220d761b1f27a..f7055180ba4aab 100644
--- a/drivers/net/wireguard/netlink.c
+++ b/drivers/net/wireguard/netlink.c
@@ -164,8 +164,8 @@ get_peer(struct wg_peer *peer, struct sk_buff *skb, struct dump_ctx *ctx)
 	if (!allowedips_node)
 		goto no_allowedips;
 	if (!ctx->allowedips_seq)
-		ctx->allowedips_seq = peer->device->peer_allowedips.seq;
-	else if (ctx->allowedips_seq != peer->device->peer_allowedips.seq)
+		ctx->allowedips_seq = ctx->wg->peer_allowedips.seq;
+	else if (ctx->allowedips_seq != ctx->wg->peer_allowedips.seq)
 		goto no_allowedips;
 
 	allowedips_nest = nla_nest_start(skb, WGPEER_A_ALLOWEDIPS);
@@ -255,17 +255,17 @@ static int wg_get_device_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	if (!peers_nest)
 		goto out;
 	ret = 0;
-	/* If the last cursor was removed via list_del_init in peer_remove, then
+	lockdep_assert_held(&wg->device_update_lock);
+	/* If the last cursor was removed in peer_remove or peer_remove_all, then
 	 * we just treat this the same as there being no more peers left. The
 	 * reason is that seq_nr should indicate to userspace that this isn't a
 	 * coherent dump anyway, so they'll try again.
 	 */
 	if (list_empty(&wg->peer_list) ||
-	    (ctx->next_peer && list_empty(&ctx->next_peer->peer_list))) {
+	    (ctx->next_peer && ctx->next_peer->is_dead)) {
 		nla_nest_cancel(skb, peers_nest);
 		goto out;
 	}
-	lockdep_assert_held(&wg->device_update_lock);
 	peer = list_prepare_entry(ctx->next_peer, &wg->peer_list, peer_list);
 	list_for_each_entry_continue(peer, &wg->peer_list, peer_list) {
 		if (get_peer(peer, skb, ctx)) {
diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c
index df275b4fccb6d0..eb8851113654f5 100644
--- a/drivers/net/wireguard/receive.c
+++ b/drivers/net/wireguard/receive.c
@@ -251,7 +251,7 @@ static bool decrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair)
 
 	if (unlikely(!READ_ONCE(keypair->receiving.is_valid) ||
 		  wg_birthdate_has_expired(keypair->receiving.birthdate, REJECT_AFTER_TIME) ||
-		  keypair->receiving_counter.counter >= REJECT_AFTER_MESSAGES)) {
+		  READ_ONCE(keypair->receiving_counter.counter) >= REJECT_AFTER_MESSAGES)) {
 		WRITE_ONCE(keypair->receiving.is_valid, false);
 		return false;
 	}
@@ -318,7 +318,7 @@ static bool counter_validate(struct noise_replay_counter *counter, u64 their_cou
 		for (i = 1; i <= top; ++i)
 			counter->backtrack[(i + index_current) &
 				((COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1)] = 0;
-		counter->counter = their_counter;
+		WRITE_ONCE(counter->counter, their_counter);
 	}
 
 	index &= (COUNTER_BITS_TOTAL / BITS_PER_LONG) - 1;
@@ -463,7 +463,7 @@ int wg_packet_rx_poll(struct napi_struct *napi, int budget)
 			net_dbg_ratelimited("%s: Packet has invalid nonce %llu (max %llu)\n",
 					    peer->device->dev->name,
 					    PACKET_CB(skb)->nonce,
-					    keypair->receiving_counter.counter);
+					    READ_ONCE(keypair->receiving_counter.counter));
 			goto next;
 		}
 
diff --git a/tools/testing/selftests/wireguard/qemu/arch/riscv32.config b/tools/testing/selftests/wireguard/qemu/arch/riscv32.config
index 2fc36efb166dc9..a7f8e8a9562593 100644
--- a/tools/testing/selftests/wireguard/qemu/arch/riscv32.config
+++ b/tools/testing/selftests/wireguard/qemu/arch/riscv32.config
@@ -3,6 +3,7 @@ CONFIG_ARCH_RV32I=y
 CONFIG_MMU=y
 CONFIG_FPU=y
 CONFIG_SOC_VIRT=y
+CONFIG_RISCV_ISA_FALLBACK=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
diff --git a/tools/testing/selftests/wireguard/qemu/arch/riscv64.config b/tools/testing/selftests/wireguard/qemu/arch/riscv64.config
index dc266f3b191557..daeb3e5e096585 100644
--- a/tools/testing/selftests/wireguard/qemu/arch/riscv64.config
+++ b/tools/testing/selftests/wireguard/qemu/arch/riscv64.config
@@ -2,6 +2,7 @@ CONFIG_ARCH_RV64I=y
 CONFIG_MMU=y
 CONFIG_FPU=y
 CONFIG_SOC_VIRT=y
+CONFIG_RISCV_ISA_FALLBACK=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y