Message-Id: <20181001084320.32453-2-mmanning@vyatta.att-mail.com>
Date:   Mon,  1 Oct 2018 09:43:11 +0100
From:   Mike Manning <mmanning@...tta.att-mail.com>
To:     netdev@...r.kernel.org
Cc:     Robert Shearman <rshearma@...tta.att-mail.com>
Subject: [PATCH net-next v2 01/10] net: allow binding socket in a VRF when there's an unbound socket

From: Robert Shearman <rshearma@...tta.att-mail.com>

There is no easy way currently for applications that want to receive
packets in the default VRF to be isolated from packets arriving in
VRFs, which makes using VRF-unaware applications in a VRF-aware system
a potential security risk.

So change the inet socket lookup to avoid packets arriving on a device
enslaved to an l3mdev from matching unbound sockets by removing the
wildcard for non sk_bound_dev_if and instead relying on check against
the secondary device index, which will be 0 when the input device is
not enslaved to an l3mdev and so match against an unbound socket and
not match when the input device is enslaved.

Change the socket binding to take the l3mdev into account to allow an
unbound socket to not conflict sockets bound to an l3mdev given the
datapath isolation now guaranteed.

Signed-off-by: Robert Shearman <rshearma@...tta.att-mail.com>
Signed-off-by: Mike Manning <mmanning@...tta.att-mail.com>
---
 Documentation/networking/vrf.txt |  9 +++++----
 include/net/inet6_hashtables.h   |  5 ++---
 include/net/inet_hashtables.h    | 13 ++++++-------
 include/net/inet_sock.h          | 13 +++++++++++++
 net/ipv4/inet_connection_sock.c  | 13 ++++++++++---
 net/ipv4/inet_hashtables.c       | 20 +++++++++++++++-----
 6 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/Documentation/networking/vrf.txt b/Documentation/networking/vrf.txt
index 8ff7b4c8f91b..d4b129402d57 100644
--- a/Documentation/networking/vrf.txt
+++ b/Documentation/networking/vrf.txt
@@ -103,6 +103,11 @@ VRF device:
 
 or to specify the output device using cmsg and IP_PKTINFO.
 
+By default the scope of the port bindings for unbound sockets is
+limited to the default VRF. That is, it will not be matched by packets
+arriving on interfaces enslaved to an l3mdev and processes may bind to
+the same port if they bind to an l3mdev.
+
 TCP & UDP services running in the default VRF context (ie., not bound
 to any VRF device) can work across all VRF domains by enabling the
 tcp_l3mdev_accept and udp_l3mdev_accept sysctl options:
@@ -112,10 +117,6 @@ tcp_l3mdev_accept and udp_l3mdev_accept sysctl options:
 netfilter rules on the VRF device can be used to limit access to services
 running in the default VRF context as well.
 
-The default VRF does not have limited scope with respect to port bindings.
-That is, if a process does a wildcard bind to a port in the default VRF it
-owns the port across all VRF domains within the network namespace.
-
 ################################################################################
 
 Using iproute2 for VRFs
diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h
index 6e91e38a31da..9db98af46985 100644
--- a/include/net/inet6_hashtables.h
+++ b/include/net/inet6_hashtables.h
@@ -115,9 +115,8 @@ int inet6_hash(struct sock *sk);
 	 ((__sk)->sk_family == AF_INET6)			&&	\
 	 ipv6_addr_equal(&(__sk)->sk_v6_daddr, (__saddr))		&&	\
 	 ipv6_addr_equal(&(__sk)->sk_v6_rcv_saddr, (__daddr))	&&	\
-	 (!(__sk)->sk_bound_dev_if	||				\
-	   ((__sk)->sk_bound_dev_if == (__dif))	||			\
-	   ((__sk)->sk_bound_dev_if == (__sdif)))		&&	\
+	 (((__sk)->sk_bound_dev_if == (__dif))	||			\
+	  ((__sk)->sk_bound_dev_if == (__sdif)))		&&	\
 	 net_eq(sock_net(__sk), (__net)))
 
 #endif /* _INET6_HASHTABLES_H */
diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 9141e95529e7..4ae060b4bac2 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -79,6 +79,7 @@ struct inet_ehash_bucket {
 
 struct inet_bind_bucket {
 	possible_net_t		ib_net;
+	int			l3mdev;
 	unsigned short		port;
 	signed char		fastreuse;
 	signed char		fastreuseport;
@@ -191,7 +192,7 @@ static inline void inet_ehash_locks_free(struct inet_hashinfo *hashinfo)
 struct inet_bind_bucket *
 inet_bind_bucket_create(struct kmem_cache *cachep, struct net *net,
 			struct inet_bind_hashbucket *head,
-			const unsigned short snum);
+			const unsigned short snum, int l3mdev);
 void inet_bind_bucket_destroy(struct kmem_cache *cachep,
 			      struct inet_bind_bucket *tb);
 
@@ -282,9 +283,8 @@ static inline struct sock *inet_lookup_listener(struct net *net,
 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
 	(((__sk)->sk_portpair == (__ports))			&&	\
 	 ((__sk)->sk_addrpair == (__cookie))			&&	\
-	 (!(__sk)->sk_bound_dev_if	||				\
-	   ((__sk)->sk_bound_dev_if == (__dif))			||	\
-	   ((__sk)->sk_bound_dev_if == (__sdif)))		&&	\
+	 (((__sk)->sk_bound_dev_if == (__dif))			||	\
+	  ((__sk)->sk_bound_dev_if == (__sdif)))		&&	\
 	 net_eq(sock_net(__sk), (__net)))
 #else /* 32-bit arch */
 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
@@ -294,9 +294,8 @@ static inline struct sock *inet_lookup_listener(struct net *net,
 	(((__sk)->sk_portpair == (__ports))		&&		\
 	 ((__sk)->sk_daddr	== (__saddr))		&&		\
 	 ((__sk)->sk_rcv_saddr	== (__daddr))		&&		\
-	 (!(__sk)->sk_bound_dev_if	||				\
-	   ((__sk)->sk_bound_dev_if == (__dif))		||		\
-	   ((__sk)->sk_bound_dev_if == (__sdif)))	&&		\
+	 (((__sk)->sk_bound_dev_if == (__dif))		||		\
+	  ((__sk)->sk_bound_dev_if == (__sdif)))	&&		\
 	 net_eq(sock_net(__sk), (__net)))
 #endif /* 64-bit arch */
 
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index e03b93360f33..92e0aa3958f6 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -130,6 +130,19 @@ static inline int inet_request_bound_dev_if(const struct sock *sk,
 	return sk->sk_bound_dev_if;
 }
 
+static inline int inet_sk_bound_l3mdev(const struct sock *sk)
+{
+#ifdef CONFIG_NET_L3_MASTER_DEV
+	struct net *net = sock_net(sk);
+
+	if (!net->ipv4.sysctl_tcp_l3mdev_accept)
+		return l3mdev_master_ifindex_by_index(net,
+						      sk->sk_bound_dev_if);
+#endif
+
+	return 0;
+}
+
 static inline struct ip_options_rcu *ireq_opt_deref(const struct inet_request_sock *ireq)
 {
 	return rcu_dereference_check(ireq->ireq_opt,
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index dfd5009f96ef..97bba5b3d69f 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -183,7 +183,9 @@ inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *
 	int i, low, high, attempt_half;
 	struct inet_bind_bucket *tb;
 	u32 remaining, offset;
+	int l3mdev;
 
+	l3mdev = inet_sk_bound_l3mdev(sk);
 	attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 other_half_scan:
 	inet_get_local_port_range(net, &low, &high);
@@ -219,7 +221,8 @@ inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *
 						  hinfo->bhash_size)];
 		spin_lock_bh(&head->lock);
 		inet_bind_bucket_for_each(tb, &head->chain)
-			if (net_eq(ib_net(tb), net) && tb->port == port) {
+			if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
+			    tb->port == port) {
 				if (!inet_csk_bind_conflict(sk, tb, false, false))
 					goto success;
 				goto next_port;
@@ -293,6 +296,9 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 	struct net *net = sock_net(sk);
 	struct inet_bind_bucket *tb = NULL;
 	kuid_t uid = sock_i_uid(sk);
+	int l3mdev;
+
+	l3mdev = inet_sk_bound_l3mdev(sk);
 
 	if (!port) {
 		head = inet_csk_find_open_port(sk, &tb, &port);
@@ -306,11 +312,12 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 					  hinfo->bhash_size)];
 	spin_lock_bh(&head->lock);
 	inet_bind_bucket_for_each(tb, &head->chain)
-		if (net_eq(ib_net(tb), net) && tb->port == port)
+		if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
+		    tb->port == port)
 			goto tb_found;
 tb_not_found:
 	tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
-				     net, head, port);
+				     net, head, port, l3mdev);
 	if (!tb)
 		goto fail_unlock;
 tb_found:
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index f5c9ef2586de..260531dc6458 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -65,12 +65,14 @@ static u32 sk_ehashfn(const struct sock *sk)
 struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
 						 struct net *net,
 						 struct inet_bind_hashbucket *head,
-						 const unsigned short snum)
+						 const unsigned short snum,
+						 int l3mdev)
 {
 	struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
 
 	if (tb) {
 		write_pnet(&tb->ib_net, net);
+		tb->l3mdev    = l3mdev;
 		tb->port      = snum;
 		tb->fastreuse = 0;
 		tb->fastreuseport = 0;
@@ -135,6 +137,7 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child)
 			table->bhash_size);
 	struct inet_bind_hashbucket *head = &table->bhash[bhash];
 	struct inet_bind_bucket *tb;
+	int l3mdev;
 
 	spin_lock(&head->lock);
 	tb = inet_csk(sk)->icsk_bind_hash;
@@ -143,6 +146,8 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child)
 		return -ENOENT;
 	}
 	if (tb->port != port) {
+		l3mdev = inet_sk_bound_l3mdev(sk);
+
 		/* NOTE: using tproxy and redirecting skbs to a proxy
 		 * on a different listener port breaks the assumption
 		 * that the listener socket's icsk_bind_hash is the same
@@ -150,12 +155,13 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child)
 		 * create a new bind bucket for the child here. */
 		inet_bind_bucket_for_each(tb, &head->chain) {
 			if (net_eq(ib_net(tb), sock_net(sk)) &&
-			    tb->port == port)
+			    tb->l3mdev == l3mdev && tb->port == port)
 				break;
 		}
 		if (!tb) {
 			tb = inet_bind_bucket_create(table->bind_bucket_cachep,
-						     sock_net(sk), head, port);
+						     sock_net(sk), head, port,
+						     l3mdev);
 			if (!tb) {
 				spin_unlock(&head->lock);
 				return -ENOMEM;
@@ -675,6 +681,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	u32 remaining, offset;
 	int ret, i, low, high;
 	static u32 hint;
+	int l3mdev;
 
 	if (port) {
 		head = &hinfo->bhash[inet_bhashfn(net, port,
@@ -693,6 +700,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		return ret;
 	}
 
+	l3mdev = inet_sk_bound_l3mdev(sk);
+
 	inet_get_local_port_range(net, &low, &high);
 	high++; /* [32768, 60999] -> [32768, 61000[ */
 	remaining = high - low;
@@ -719,7 +728,8 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		 * the established check is already unique enough.
 		 */
 		inet_bind_bucket_for_each(tb, &head->chain) {
-			if (net_eq(ib_net(tb), net) && tb->port == port) {
+			if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
+			    tb->port == port) {
 				if (tb->fastreuse >= 0 ||
 				    tb->fastreuseport >= 0)
 					goto next_port;
@@ -732,7 +742,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 		}
 
 		tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
-					     net, head, port);
+					     net, head, port, l3mdev);
 		if (!tb) {
 			spin_unlock_bh(&head->lock);
 			return -ENOMEM;
-- 
2.11.0

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