From 4ee806d51176ba7b8ff1efd81f271d7252e03a1d Mon Sep 17 00:00:00 2001 From: Dan Streetman Date: Thu, 18 Jan 2018 16:14:26 -0500 Subject: net: tcp: close sock if net namespace is exiting When a tcp socket is closed, if it detects that its net namespace is exiting, close immediately and do not wait for FIN sequence. For normal sockets, a reference is taken to their net namespace, so it will never exit while the socket is open. However, kernel sockets do not take a reference to their net namespace, so it may begin exiting while the kernel socket is still open. In this case if the kernel socket is a tcp socket, it will stay open trying to complete its close sequence. The sock's dst(s) hold a reference to their interface, which are all transferred to the namespace's loopback interface when the real interfaces are taken down. When the namespace tries to take down its loopback interface, it hangs waiting for all references to the loopback interface to release, which results in messages like: unregister_netdevice: waiting for lo to become free. Usage count = 1 These messages continue until the socket finally times out and closes. Since the net namespace cleanup holds the net_mutex while calling its registered pernet callbacks, any new net namespace initialization is blocked until the current net namespace finishes exiting. After this change, the tcp socket notices the exiting net namespace, and closes immediately, releasing its dst(s) and their reference to the loopback interface, which lets the net namespace continue exiting. Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=97811 Signed-off-by: Dan Streetman Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 3 +++ net/ipv4/tcp_timer.c | 15 +++++++++++++++ 2 files changed, 18 insertions(+) (limited to 'net/ipv4') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f08eebe60446..8e053ad7cae2 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2298,6 +2298,9 @@ adjudge_to_death: tcp_send_active_reset(sk, GFP_ATOMIC); __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); + } else if (!check_net(sock_net(sk))) { + /* Not possible to send reset; just close */ + tcp_set_state(sk, TCP_CLOSE); } } diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 968fda198376..388158c9d9f6 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -48,11 +48,19 @@ static void tcp_write_err(struct sock *sk) * to prevent DoS attacks. It is called when a retransmission timeout * or zero probe timeout occurs on orphaned socket. * + * Also close if our net namespace is exiting; in that case there is no + * hope of ever communicating again since all netns interfaces are already + * down (or about to be down), and we need to release our dst references, + * which have been moved to the netns loopback interface, so the namespace + * can finish exiting. This condition is only possible if we are a kernel + * socket, as those do not hold references to the namespace. + * * Criteria is still not confirmed experimentally and may change. * We kill the socket, if: * 1. If number of orphaned sockets exceeds an administratively configured * limit. * 2. If we have strong memory pressure. + * 3. If our net namespace is exiting. */ static int tcp_out_of_resources(struct sock *sk, bool do_reset) { @@ -81,6 +89,13 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset) __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY); return 1; } + + if (!check_net(sock_net(sk))) { + /* Not possible to send reset; just close */ + tcp_done(sk); + return 1; + } + return 0; } -- cgit v1.2.3-59-g8ed1b From f15ca723c1ebe6c1a06bc95fda6b62cd87b44559 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Thu, 25 Jan 2018 19:03:03 +0100 Subject: net: don't call update_pmtu unconditionally Some dst_ops (e.g. md_dst_ops)) doesn't set this handler. It may result to: "BUG: unable to handle kernel NULL pointer dereference at (null)" Let's add a helper to check if update_pmtu is available before calling it. Fixes: 52a589d51f10 ("geneve: update skb dst pmtu on tx path") Fixes: a93bf0ff4490 ("vxlan: update skb dst pmtu on tx path") CC: Roman Kapl CC: Xin Long Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller --- drivers/infiniband/ulp/ipoib/ipoib_cm.c | 3 +-- drivers/net/geneve.c | 4 ++-- drivers/net/vxlan.c | 6 ++---- include/net/dst.h | 8 ++++++++ net/ipv4/ip_tunnel.c | 3 +-- net/ipv4/ip_vti.c | 2 +- net/ipv6/ip6_tunnel.c | 6 ++---- net/ipv6/ip6_vti.c | 2 +- net/ipv6/sit.c | 4 ++-- 9 files changed, 20 insertions(+), 18 deletions(-) (limited to 'net/ipv4') diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c index 2c13123bfd69..71ea9e26666c 100644 --- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c +++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c @@ -1456,8 +1456,7 @@ void ipoib_cm_skb_too_long(struct net_device *dev, struct sk_buff *skb, struct ipoib_dev_priv *priv = ipoib_priv(dev); int e = skb_queue_empty(&priv->cm.skb_queue); - if (skb_dst(skb)) - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); skb_queue_tail(&priv->cm.skb_queue, skb); if (e) diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c index 0a48b3073d3d..64fda2e1040e 100644 --- a/drivers/net/geneve.c +++ b/drivers/net/geneve.c @@ -829,7 +829,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev, int mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr) - GENEVE_BASE_HLEN - info->options_len - 14; - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); } sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true); @@ -875,7 +875,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev, int mtu = dst_mtu(dst) - sizeof(struct ipv6hdr) - GENEVE_BASE_HLEN - info->options_len - 14; - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); } sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true); diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 31f4b7911ef8..c3e34e3c82a7 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -2158,8 +2158,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, if (skb_dst(skb)) { int mtu = dst_mtu(ndst) - VXLAN_HEADROOM; - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, - skb, mtu); + skb_dst_update_pmtu(skb, mtu); } tos = ip_tunnel_ecn_encap(tos, old_iph, skb); @@ -2200,8 +2199,7 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, if (skb_dst(skb)) { int mtu = dst_mtu(ndst) - VXLAN6_HEADROOM; - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, - skb, mtu); + skb_dst_update_pmtu(skb, mtu); } tos = ip_tunnel_ecn_encap(tos, old_iph, skb); diff --git a/include/net/dst.h b/include/net/dst.h index b091fd536098..d49d607dd2b3 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -521,4 +521,12 @@ static inline struct xfrm_state *dst_xfrm(const struct dst_entry *dst) } #endif +static inline void skb_dst_update_pmtu(struct sk_buff *skb, u32 mtu) +{ + struct dst_entry *dst = skb_dst(skb); + + if (dst && dst->ops->update_pmtu) + dst->ops->update_pmtu(dst, NULL, skb, mtu); +} + #endif /* _NET_DST_H */ diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index 5ddb1cb52bd4..6d21068f9b55 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -520,8 +520,7 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb, else mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu; - if (skb_dst(skb)) - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); if (skb->protocol == htons(ETH_P_IP)) { if (!skb_is_gso(skb) && diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c index 949f432a5f04..51b1669334fe 100644 --- a/net/ipv4/ip_vti.c +++ b/net/ipv4/ip_vti.c @@ -200,7 +200,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev, mtu = dst_mtu(dst); if (skb->len > mtu) { - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); if (skb->protocol == htons(ETH_P_IP)) { icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c index 9a7cf355bc8c..1ee5584c3555 100644 --- a/net/ipv6/ip6_tunnel.c +++ b/net/ipv6/ip6_tunnel.c @@ -642,8 +642,7 @@ ip4ip6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, if (rel_info > dst_mtu(skb_dst(skb2))) goto out; - skb_dst(skb2)->ops->update_pmtu(skb_dst(skb2), NULL, skb2, - rel_info); + skb_dst_update_pmtu(skb2, rel_info); } icmp_send(skb2, rel_type, rel_code, htonl(rel_info)); @@ -1131,8 +1130,7 @@ route_lookup: mtu = 576; } - if (skb_dst(skb) && !t->parms.collect_md) - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); if (skb->len - t->tun_hlen - eth_hlen > mtu && !skb_is_gso(skb)) { *pmtu = mtu; err = -EMSGSIZE; diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index dbb74f3c57a7..8c184f84f353 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -483,7 +483,7 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl) mtu = dst_mtu(dst); if (!skb->ignore_df && skb->len > mtu) { - skb_dst(skb)->ops->update_pmtu(dst, NULL, skb, mtu); + skb_dst_update_pmtu(skb, mtu); if (skb->protocol == htons(ETH_P_IPV6)) { if (mtu < IPV6_MIN_MTU) diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c index d7dc23c1b2ca..3873d3877135 100644 --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -934,8 +934,8 @@ static netdev_tx_t ipip6_tunnel_xmit(struct sk_buff *skb, df = 0; } - if (tunnel->parms.iph.daddr && skb_dst(skb)) - skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu); + if (tunnel->parms.iph.daddr) + skb_dst_update_pmtu(skb, mtu); if (skb->len > mtu && !skb_is_gso(skb)) { icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); -- cgit v1.2.3-59-g8ed1b