From c6fcc4fc5f8b592600c7409e769ab68da0fb1eca Mon Sep 17 00:00:00 2001 From: pravin shelar Date: Fri, 28 Oct 2016 09:59:15 -0700 Subject: [PATCH] vxlan: avoid using stale vxlan socket. When vxlan device is closed vxlan socket is freed. This operation can race with vxlan-xmit function which dereferences vxlan socket. Following patch uses RCU mechanism to avoid this situation. Signed-off-by: Pravin B Shelar Signed-off-by: David S. Miller --- drivers/net/vxlan.c | 80 ++++++++++++++++++++++++++++----------------- include/net/vxlan.h | 4 +-- 2 files changed, 52 insertions(+), 32 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index c1639a3e95a4..f3c2fa3ab0d5 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -943,17 +943,20 @@ static bool vxlan_snoop(struct net_device *dev, static bool vxlan_group_used(struct vxlan_net *vn, struct vxlan_dev *dev) { struct vxlan_dev *vxlan; + struct vxlan_sock *sock4; + struct vxlan_sock *sock6 = NULL; unsigned short family = dev->default_dst.remote_ip.sa.sa_family; + sock4 = rtnl_dereference(dev->vn4_sock); + /* The vxlan_sock is only used by dev, leaving group has * no effect on other vxlan devices. */ - if (family == AF_INET && dev->vn4_sock && - atomic_read(&dev->vn4_sock->refcnt) == 1) + if (family == AF_INET && sock4 && atomic_read(&sock4->refcnt) == 1) return false; #if IS_ENABLED(CONFIG_IPV6) - if (family == AF_INET6 && dev->vn6_sock && - atomic_read(&dev->vn6_sock->refcnt) == 1) + sock6 = rtnl_dereference(dev->vn6_sock); + if (family == AF_INET6 && sock6 && atomic_read(&sock6->refcnt) == 1) return false; #endif @@ -961,10 +964,12 @@ static bool vxlan_group_used(struct vxlan_net *vn, struct vxlan_dev *dev) if (!netif_running(vxlan->dev) || vxlan == dev) continue; - if (family == AF_INET && vxlan->vn4_sock != dev->vn4_sock) + if (family == AF_INET && + rtnl_dereference(vxlan->vn4_sock) != sock4) continue; #if IS_ENABLED(CONFIG_IPV6) - if (family == AF_INET6 && vxlan->vn6_sock != dev->vn6_sock) + if (family == AF_INET6 && + rtnl_dereference(vxlan->vn6_sock) != sock6) continue; #endif @@ -1005,22 +1010,25 @@ static bool __vxlan_sock_release_prep(struct vxlan_sock *vs) static void vxlan_sock_release(struct vxlan_dev *vxlan) { - bool ipv4 = __vxlan_sock_release_prep(vxlan->vn4_sock); + struct vxlan_sock *sock4 = rtnl_dereference(vxlan->vn4_sock); #if IS_ENABLED(CONFIG_IPV6) - bool ipv6 = __vxlan_sock_release_prep(vxlan->vn6_sock); + struct vxlan_sock *sock6 = rtnl_dereference(vxlan->vn6_sock); + + rcu_assign_pointer(vxlan->vn6_sock, NULL); #endif + rcu_assign_pointer(vxlan->vn4_sock, NULL); synchronize_net(); - if (ipv4) { - udp_tunnel_sock_release(vxlan->vn4_sock->sock); - kfree(vxlan->vn4_sock); + if (__vxlan_sock_release_prep(sock4)) { + udp_tunnel_sock_release(sock4->sock); + kfree(sock4); } #if IS_ENABLED(CONFIG_IPV6) - if (ipv6) { - udp_tunnel_sock_release(vxlan->vn6_sock->sock); - kfree(vxlan->vn6_sock); + if (__vxlan_sock_release_prep(sock6)) { + udp_tunnel_sock_release(sock6->sock); + kfree(sock6); } #endif } @@ -1036,18 +1044,21 @@ static int vxlan_igmp_join(struct vxlan_dev *vxlan) int ret = -EINVAL; if (ip->sa.sa_family == AF_INET) { + struct vxlan_sock *sock4 = rtnl_dereference(vxlan->vn4_sock); struct ip_mreqn mreq = { .imr_multiaddr.s_addr = ip->sin.sin_addr.s_addr, .imr_ifindex = ifindex, }; - sk = vxlan->vn4_sock->sock->sk; + sk = sock4->sock->sk; lock_sock(sk); ret = ip_mc_join_group(sk, &mreq); release_sock(sk); #if IS_ENABLED(CONFIG_IPV6) } else { - sk = vxlan->vn6_sock->sock->sk; + struct vxlan_sock *sock6 = rtnl_dereference(vxlan->vn6_sock); + + sk = sock6->sock->sk; lock_sock(sk); ret = ipv6_stub->ipv6_sock_mc_join(sk, ifindex, &ip->sin6.sin6_addr); @@ -1067,18 +1078,21 @@ static int vxlan_igmp_leave(struct vxlan_dev *vxlan) int ret = -EINVAL; if (ip->sa.sa_family == AF_INET) { + struct vxlan_sock *sock4 = rtnl_dereference(vxlan->vn4_sock); struct ip_mreqn mreq = { .imr_multiaddr.s_addr = ip->sin.sin_addr.s_addr, .imr_ifindex = ifindex, }; - sk = vxlan->vn4_sock->sock->sk; + sk = sock4->sock->sk; lock_sock(sk); ret = ip_mc_leave_group(sk, &mreq); release_sock(sk); #if IS_ENABLED(CONFIG_IPV6) } else { - sk = vxlan->vn6_sock->sock->sk; + struct vxlan_sock *sock6 = rtnl_dereference(vxlan->vn6_sock); + + sk = sock6->sock->sk; lock_sock(sk); ret = ipv6_stub->ipv6_sock_mc_drop(sk, ifindex, &ip->sin6.sin6_addr); @@ -1828,11 +1842,15 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan, struct dst_cache *dst_cache, const struct ip_tunnel_info *info) { + struct vxlan_sock *sock6 = rcu_dereference(vxlan->vn6_sock); bool use_cache = ip_tunnel_dst_cache_usable(skb, info); struct dst_entry *ndst; struct flowi6 fl6; int err; + if (!sock6) + return ERR_PTR(-EIO); + if (tos && !info) use_cache = false; if (use_cache) { @@ -1850,7 +1868,7 @@ static struct dst_entry *vxlan6_get_route(struct vxlan_dev *vxlan, fl6.flowi6_proto = IPPROTO_UDP; err = ipv6_stub->ipv6_dst_lookup(vxlan->net, - vxlan->vn6_sock->sock->sk, + sock6->sock->sk, &ndst, &fl6); if (err < 0) return ERR_PTR(err); @@ -1995,9 +2013,11 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, } if (dst->sa.sa_family == AF_INET) { - if (!vxlan->vn4_sock) + struct vxlan_sock *sock4 = rcu_dereference(vxlan->vn4_sock); + + if (!sock4) goto drop; - sk = vxlan->vn4_sock->sock->sk; + sk = sock4->sock->sk; rt = vxlan_get_route(vxlan, skb, rdst ? rdst->remote_ifindex : 0, tos, @@ -2050,12 +2070,13 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev, src_port, dst_port, xnet, !udp_sum); #if IS_ENABLED(CONFIG_IPV6) } else { + struct vxlan_sock *sock6 = rcu_dereference(vxlan->vn6_sock); struct dst_entry *ndst; u32 rt6i_flags; - if (!vxlan->vn6_sock) + if (!sock6) goto drop; - sk = vxlan->vn6_sock->sock->sk; + sk = sock6->sock->sk; ndst = vxlan6_get_route(vxlan, skb, rdst ? rdst->remote_ifindex : 0, tos, @@ -2415,9 +2436,10 @@ static int vxlan_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb) dport = info->key.tp_dst ? : vxlan->cfg.dst_port; if (ip_tunnel_info_af(info) == AF_INET) { + struct vxlan_sock *sock4 = rcu_dereference(vxlan->vn4_sock); struct rtable *rt; - if (!vxlan->vn4_sock) + if (!sock4) return -EINVAL; rt = vxlan_get_route(vxlan, skb, 0, info->key.tos, info->key.u.ipv4.dst, @@ -2429,8 +2451,6 @@ static int vxlan_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb) #if IS_ENABLED(CONFIG_IPV6) struct dst_entry *ndst; - if (!vxlan->vn6_sock) - return -EINVAL; ndst = vxlan6_get_route(vxlan, skb, 0, info->key.tos, info->key.label, &info->key.u.ipv6.dst, &info->key.u.ipv6.src, NULL, info); @@ -2740,10 +2760,10 @@ static int __vxlan_sock_add(struct vxlan_dev *vxlan, bool ipv6) return PTR_ERR(vs); #if IS_ENABLED(CONFIG_IPV6) if (ipv6) - vxlan->vn6_sock = vs; + rcu_assign_pointer(vxlan->vn6_sock, vs); else #endif - vxlan->vn4_sock = vs; + rcu_assign_pointer(vxlan->vn4_sock, vs); vxlan_vs_add_dev(vs, vxlan); return 0; } @@ -2754,9 +2774,9 @@ static int vxlan_sock_add(struct vxlan_dev *vxlan) bool metadata = vxlan->flags & VXLAN_F_COLLECT_METADATA; int ret = 0; - vxlan->vn4_sock = NULL; + RCU_INIT_POINTER(vxlan->vn4_sock, NULL); #if IS_ENABLED(CONFIG_IPV6) - vxlan->vn6_sock = NULL; + RCU_INIT_POINTER(vxlan->vn6_sock, NULL); if (ipv6 || metadata) ret = __vxlan_sock_add(vxlan, true); #endif diff --git a/include/net/vxlan.h b/include/net/vxlan.h index 0255613a54a4..308adc4154f4 100644 --- a/include/net/vxlan.h +++ b/include/net/vxlan.h @@ -225,9 +225,9 @@ struct vxlan_config { struct vxlan_dev { struct hlist_node hlist; /* vni hash table */ struct list_head next; /* vxlan's per namespace list */ - struct vxlan_sock *vn4_sock; /* listening socket for IPv4 */ + struct vxlan_sock __rcu *vn4_sock; /* listening socket for IPv4 */ #if IS_ENABLED(CONFIG_IPV6) - struct vxlan_sock *vn6_sock; /* listening socket for IPv6 */ + struct vxlan_sock __rcu *vn6_sock; /* listening socket for IPv6 */ #endif struct net_device *dev; struct net *net; /* netns for packet i/o */ -- 2.20.1