net: Support nuking IPv6 sockets as well as IPv4.

On Linux, when an interface goes down all its IPv6
addresses are deleted, so relying on knowing the previous
IPv6 addresses on the interface is brittle. Instead,
support nuking all sockets that are bound to IP addresses
that are not configured and up on the system. This
behaviour is triggered by specifying the unspecified
address (:: or 0.0.0.0). If an IP address is specified, the
behaviour is unchanged, except the ioctl now supports IPv6
as well as IPv4.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>

3 files changed, 98 insertions, 45 deletions

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index b5aad2b..a829824 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -916,8 +916,7 @@ int devinet_ioctl(struct net *net, unsigned int cmd, void __user *arg)
 		}
 		break;
 	case SIOCKILLADDR:	/* Nuke all connections on this address */
-		ret = 0;
-		tcp_v4_nuke_addr(sin->sin_addr.s_addr);
+		ret = tcp_nuke_addr(net, (struct sockaddr *) sin);
 		break;
 	}
 done:
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 7764d4c..58da8e1 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -272,6 +272,7 @@
 #include <net/tcp.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
+#include <net/ip6_route.h>
 #include <net/netdma.h>
 #include <net/sock.h>
 
@@ -3328,3 +3329,99 @@ void __init tcp_init(void)
 	tcp_secret_retiring = &tcp_secret_two;
 	tcp_secret_secondary = &tcp_secret_two;
 }
+
+static int tcp_is_local(struct net *net, __be32 addr) {
+	struct rtable *rt;
+	struct flowi fl = { .nl_u = { .ip4_u = { .daddr = addr } } };
+	if (ip_route_output_key(net, &rt, &fl) || !rt)
+		return 0;
+	return rt->dst.dev && (rt->dst.dev->flags & IFF_LOOPBACK);
+}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+static int tcp_is_local6(struct net *net, struct in6_addr *addr) {
+	struct rt6_info *rt6 = rt6_lookup(net, addr, addr, 0, 0);
+	return rt6 && rt6->rt6i_dev && (rt6->rt6i_dev->flags & IFF_LOOPBACK);
+}
+#endif
+
+/*
+ * tcp_nuke_addr - destroy all sockets on the given local address
+ * if local address is the unspecified address (0.0.0.0 or ::), destroy all
+ * sockets with local addresses that are not configured.
+ */
+int tcp_nuke_addr(struct net *net, struct sockaddr *addr)
+{
+	int family = addr->sa_family;
+	unsigned int bucket;
+
+	struct in_addr *in;
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+	struct in6_addr *in6;
+#endif
+	if (family == AF_INET) {
+		in = &((struct sockaddr_in *)addr)->sin_addr;
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+	} else if (family == AF_INET6) {
+		in6 = &((struct sockaddr_in6 *)addr)->sin6_addr;
+#endif
+	} else {
+		return -EAFNOSUPPORT;
+	}
+
+	for (bucket = 0; bucket < tcp_hashinfo.ehash_mask; bucket++) {
+		struct hlist_nulls_node *node;
+		struct sock *sk;
+		spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, bucket);
+
+restart:
+		spin_lock_bh(lock);
+		sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[bucket].chain) {
+			struct inet_sock *inet = inet_sk(sk);
+
+			if (family == AF_INET) {
+				__be32 s4 = inet->inet_rcv_saddr;
+				if (in->s_addr != s4 &&
+				    !(in->s_addr == INADDR_ANY &&
+				      !tcp_is_local(net, s4)))
+					continue;
+			}
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+			if (family == AF_INET6) {
+				struct in6_addr *s6;
+				if (!inet->pinet6)
+					continue;
+				s6 = &inet->pinet6->rcv_saddr;
+				if (!ipv6_addr_equal(in6, s6) &&
+				    !(ipv6_addr_equal(in6, &in6addr_any) &&
+				      !tcp_is_local6(net, s6)))
+				continue;
+			}
+#endif
+
+			if (sysctl_ip_dynaddr && sk->sk_state == TCP_SYN_SENT)
+				continue;
+			if (sock_flag(sk, SOCK_DEAD))
+				continue;
+
+			sock_hold(sk);
+			spin_unlock_bh(lock);
+
+			local_bh_disable();
+			bh_lock_sock(sk);
+			sk->sk_err = ETIMEDOUT;
+			sk->sk_error_report(sk);
+
+			tcp_done(sk);
+			bh_unlock_sock(sk);
+			local_bh_enable();
+			sock_put(sk);
+
+			goto restart;
+		}
+		spin_unlock_bh(lock);
+	}
+
+	return 0;
+}
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4186c76..a7d6671 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1954,49 +1954,6 @@ void tcp_v4_destroy_sock(struct sock *sk)
 }
 EXPORT_SYMBOL(tcp_v4_destroy_sock);
 
-/*
- * tcp_v4_nuke_addr - destroy all sockets on the given local address
- */
-void tcp_v4_nuke_addr(__u32 saddr)
-{
-	unsigned int bucket;
-
-	for (bucket = 0; bucket < tcp_hashinfo.ehash_mask; bucket++) {
-		struct hlist_nulls_node *node;
-		struct sock *sk;
-		spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, bucket);
-
-restart:
-		spin_lock_bh(lock);
-		sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[bucket].chain) {
-			struct inet_sock *inet = inet_sk(sk);
-
-			if (inet->inet_rcv_saddr != saddr)
-				continue;
-			if (sysctl_ip_dynaddr && sk->sk_state == TCP_SYN_SENT)
-				continue;
-			if (sock_flag(sk, SOCK_DEAD))
-				continue;
-
-			sock_hold(sk);
-			spin_unlock_bh(lock);
-
-			local_bh_disable();
-			bh_lock_sock(sk);
-			sk->sk_err = ETIMEDOUT;
-			sk->sk_error_report(sk);
-
-			tcp_done(sk);
-			bh_unlock_sock(sk);
-			local_bh_enable();
-			sock_put(sk);
-
-			goto restart;
-		}
-		spin_unlock_bh(lock);
-	}
-}
-
 #ifdef CONFIG_PROC_FS
 /* Proc filesystem TCP sock list dumping. */