From 11717797814ecc227f5bc4759d3f39f3cc22ddcf Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Fri, 14 Feb 2020 23:57:21 +0100 Subject: wireguard: receive: reset last_under_load to zero This is a small optimization that prevents more expensive comparisons from happening when they are no longer necessary, by clearing the last_under_load variable whenever we wind up in a state where we were under load but we no longer are. Signed-off-by: Jason A. Donenfeld Suggested-by: Matt Dunwoodie Signed-off-by: David S. Miller --- drivers/net/wireguard/receive.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireguard/receive.c b/drivers/net/wireguard/receive.c index 9c6bab9..4a15389 100644 --- a/drivers/net/wireguard/receive.c +++ b/drivers/net/wireguard/receive.c @@ -118,10 +118,13 @@ static void wg_receive_handshake_packet(struct wg_device *wg, under_load = skb_queue_len(&wg->incoming_handshakes) >= MAX_QUEUED_INCOMING_HANDSHAKES / 8; - if (under_load) + if (under_load) { last_under_load = ktime_get_coarse_boottime_ns(); - else if (last_under_load) + } else if (last_under_load) { under_load = !wg_birthdate_has_expired(last_under_load, 1); + if (!under_load) + last_under_load = 0; + } mac_state = wg_cookie_validate_packet(&wg->cookie_checker, skb, under_load); if ((under_load && mac_state == VALID_MAC_WITH_COOKIE) || -- cgit v1.2.3 From c28f11bf68bb34f9f0ead94b9eee0123dc86aad5 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Fri, 14 Feb 2020 23:57:22 +0100 Subject: wireguard: send: account for mtu=0 devices It turns out there's an easy way to get packets queued up while still having an MTU of zero, and that's via persistent keep alive. This commit makes sure that in whatever condition, we don't wind up dividing by zero. Note that an MTU of zero for a wireguard interface is something quasi-valid, so I don't think the correct fix is to limit it via min_mtu. This can be reproduced easily with: ip link add wg0 type wireguard ip link add wg1 type wireguard ip link set wg0 up mtu 0 ip link set wg1 up wg set wg0 private-key <(wg genkey) wg set wg1 listen-port 1 private-key <(wg genkey) peer $(wg show wg0 public-key) wg set wg0 peer $(wg show wg1 public-key) persistent-keepalive 1 endpoint 127.0.0.1:1 However, while min_mtu=0 seems fine, it makes sense to restrict the max_mtu. This commit also restricts the maximum MTU to the greatest number for which rounding up to the padding multiple won't overflow a signed integer. Packets this large were always rejected anyway eventually, due to checks deeper in, but it seems more sound not to even let the administrator configure something that won't work anyway. We use this opportunity to clean up this function a bit so that it's clear which paths we're expecting. Signed-off-by: Jason A. Donenfeld Cc: Eric Dumazet Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/wireguard/device.c | 7 ++++--- drivers/net/wireguard/send.c | 16 +++++++++++----- 2 files changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c index 43db442..cdc9696 100644 --- a/drivers/net/wireguard/device.c +++ b/drivers/net/wireguard/device.c @@ -258,6 +258,8 @@ static void wg_setup(struct net_device *dev) enum { WG_NETDEV_FEATURES = NETIF_F_HW_CSUM | NETIF_F_RXCSUM | NETIF_F_SG | NETIF_F_GSO | NETIF_F_GSO_SOFTWARE | NETIF_F_HIGHDMA }; + const int overhead = MESSAGE_MINIMUM_LENGTH + sizeof(struct udphdr) + + max(sizeof(struct ipv6hdr), sizeof(struct iphdr)); dev->netdev_ops = &netdev_ops; dev->hard_header_len = 0; @@ -271,9 +273,8 @@ static void wg_setup(struct net_device *dev) dev->features |= WG_NETDEV_FEATURES; dev->hw_features |= WG_NETDEV_FEATURES; dev->hw_enc_features |= WG_NETDEV_FEATURES; - dev->mtu = ETH_DATA_LEN - MESSAGE_MINIMUM_LENGTH - - sizeof(struct udphdr) - - max(sizeof(struct ipv6hdr), sizeof(struct iphdr)); + dev->mtu = ETH_DATA_LEN - overhead; + dev->max_mtu = round_down(INT_MAX, MESSAGE_PADDING_MULTIPLE) - overhead; SET_NETDEV_DEVTYPE(dev, &device_type); diff --git a/drivers/net/wireguard/send.c b/drivers/net/wireguard/send.c index c132605..7348c10 100644 --- a/drivers/net/wireguard/send.c +++ b/drivers/net/wireguard/send.c @@ -143,16 +143,22 @@ static void keep_key_fresh(struct wg_peer *peer) static unsigned int calculate_skb_padding(struct sk_buff *skb) { + unsigned int padded_size, last_unit = skb->len; + + if (unlikely(!PACKET_CB(skb)->mtu)) + return ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE) - last_unit; + /* We do this modulo business with the MTU, just in case the networking * layer gives us a packet that's bigger than the MTU. In that case, we * wouldn't want the final subtraction to overflow in the case of the - * padded_size being clamped. + * padded_size being clamped. Fortunately, that's very rarely the case, + * so we optimize for that not happening. */ - unsigned int last_unit = skb->len % PACKET_CB(skb)->mtu; - unsigned int padded_size = ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE); + if (unlikely(last_unit > PACKET_CB(skb)->mtu)) + last_unit %= PACKET_CB(skb)->mtu; - if (padded_size > PACKET_CB(skb)->mtu) - padded_size = PACKET_CB(skb)->mtu; + padded_size = min(PACKET_CB(skb)->mtu, + ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE)); return padded_size - last_unit; } -- cgit v1.2.3 From 5c80736eb84941b393338b8af1e032a829d78654 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Fri, 14 Feb 2020 23:57:23 +0100 Subject: wireguard: socket: remove extra call to synchronize_net synchronize_net() is a wrapper around synchronize_rcu(), so there's no point in having synchronize_net and synchronize_rcu back to back, despite the documentation comment suggesting maybe it's somewhat useful, "Wait for packets currently being received to be done." This commit removes the extra call. Signed-off-by: Jason A. Donenfeld Suggested-by: Eric Dumazet Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/wireguard/socket.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/net/wireguard/socket.c b/drivers/net/wireguard/socket.c index 262f3b5..b0d6541 100644 --- a/drivers/net/wireguard/socket.c +++ b/drivers/net/wireguard/socket.c @@ -432,7 +432,6 @@ void wg_socket_reinit(struct wg_device *wg, struct sock *new4, wg->incoming_port = ntohs(inet_sk(new4)->inet_sport); mutex_unlock(&wg->socket_update_lock); synchronize_rcu(); - synchronize_net(); sock_free(old4); sock_free(old6); } -- cgit v1.2.3