vsock: add netns to vsock core

Add netns logic to vsock core. Additionally, modify transport hook
prototypes to be used by later transport-specific patches (e.g.,
*_seqpacket_allow()).

Namespaces are supported primarily by changing socket lookup functions
(e.g., vsock_find_connected_socket()) to take into account the socket
namespace and the namespace mode before considering a candidate socket a
"match".

This patch also introduces the sysctl /proc/sys/net/vsock/ns_mode to
report the mode and /proc/sys/net/vsock/child_ns_mode to set the mode
for new namespaces.

Add netns functionality (initialization, passing to transports, procfs,
etc...) to the af_vsock socket layer. Later patches that add netns
support to transports depend on this patch.

This patch changes the allocation of random ports for connectible vsocks
in order to avoid leaking the random port range starting point to other
namespaces.

dgram_allow(), stream_allow(), and seqpacket_allow() callbacks are
modified to take a vsk in order to perform logic on namespace modes. In
future patches, the net will also be used for socket
lookups in these functions.

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260121-vsock-vmtest-v16-1-2859a7512097@meta.com
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

4 files changed, 85 insertions, 5 deletions

diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 0c67543a45c8..1845e8d4f78d 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -256,10 +256,10 @@ void virtio_transport_notify_buffer_size(struct vsock_sock *vsk, u64 *val);
 
 u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk);
 bool virtio_transport_stream_is_active(struct vsock_sock *vsk);
-bool virtio_transport_stream_allow(u32 cid, u32 port);
+bool virtio_transport_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port);
 int virtio_transport_dgram_bind(struct vsock_sock *vsk,
 				struct sockaddr_vm *addr);
-bool virtio_transport_dgram_allow(u32 cid, u32 port);
+bool virtio_transport_dgram_allow(struct vsock_sock *vsk, u32 cid, u32 port);
 
 int virtio_transport_connect(struct vsock_sock *vsk);
 
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index d40e978126e3..d3ff48a2fbe0 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -10,6 +10,7 @@
 
 #include <linux/kernel.h>
 #include <linux/workqueue.h>
+#include <net/netns/vsock.h>
 #include <net/sock.h>
 #include <uapi/linux/vm_sockets.h>
 
@@ -124,7 +125,7 @@ struct vsock_transport {
 			     size_t len, int flags);
 	int (*dgram_enqueue)(struct vsock_sock *, struct sockaddr_vm *,
 			     struct msghdr *, size_t len);
-	bool (*dgram_allow)(u32 cid, u32 port);
+	bool (*dgram_allow)(struct vsock_sock *vsk, u32 cid, u32 port);
 
 	/* STREAM. */
 	/* TODO: stream_bind() */
@@ -136,14 +137,14 @@ struct vsock_transport {
 	s64 (*stream_has_space)(struct vsock_sock *);
 	u64 (*stream_rcvhiwat)(struct vsock_sock *);
 	bool (*stream_is_active)(struct vsock_sock *);
-	bool (*stream_allow)(u32 cid, u32 port);
+	bool (*stream_allow)(struct vsock_sock *vsk, u32 cid, u32 port);
 
 	/* SEQ_PACKET. */
 	ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
 				     int flags);
 	int (*seqpacket_enqueue)(struct vsock_sock *vsk, struct msghdr *msg,
 				 size_t len);
-	bool (*seqpacket_allow)(u32 remote_cid);
+	bool (*seqpacket_allow)(struct vsock_sock *vsk, u32 remote_cid);
 	u32 (*seqpacket_has_data)(struct vsock_sock *vsk);
 
 	/* Notification. */
@@ -216,6 +217,11 @@ void vsock_remove_connected(struct vsock_sock *vsk);
 struct sock *vsock_find_bound_socket(struct sockaddr_vm *addr);
 struct sock *vsock_find_connected_socket(struct sockaddr_vm *src,
 					 struct sockaddr_vm *dst);
+struct sock *vsock_find_bound_socket_net(struct sockaddr_vm *addr,
+					 struct net *net);
+struct sock *vsock_find_connected_socket_net(struct sockaddr_vm *src,
+					     struct sockaddr_vm *dst,
+					     struct net *net);
 void vsock_remove_sock(struct vsock_sock *vsk);
 void vsock_for_each_connected_socket(struct vsock_transport *transport,
 				     void (*fn)(struct sock *sk));
@@ -256,4 +262,53 @@ static inline bool vsock_msgzerocopy_allow(const struct vsock_transport *t)
 {
 	return t->msgzerocopy_allow && t->msgzerocopy_allow();
 }
+
+static inline enum vsock_net_mode vsock_net_mode(struct net *net)
+{
+	if (!net)
+		return VSOCK_NET_MODE_GLOBAL;
+
+	return READ_ONCE(net->vsock.mode);
+}
+
+static inline bool vsock_net_mode_global(struct vsock_sock *vsk)
+{
+	return vsock_net_mode(sock_net(sk_vsock(vsk))) == VSOCK_NET_MODE_GLOBAL;
+}
+
+static inline void vsock_net_set_child_mode(struct net *net,
+					    enum vsock_net_mode mode)
+{
+	WRITE_ONCE(net->vsock.child_ns_mode, mode);
+}
+
+static inline enum vsock_net_mode vsock_net_child_mode(struct net *net)
+{
+	return READ_ONCE(net->vsock.child_ns_mode);
+}
+
+/* Return true if two namespaces pass the mode rules. Otherwise, return false.
+ *
+ * A NULL namespace is treated as VSOCK_NET_MODE_GLOBAL.
+ *
+ * Read more about modes in the comment header of net/vmw_vsock/af_vsock.c.
+ */
+static inline bool vsock_net_check_mode(struct net *ns0, struct net *ns1)
+{
+	enum vsock_net_mode mode0, mode1;
+
+	/* Any vsocks within the same network namespace are always reachable,
+	 * regardless of the mode.
+	 */
+	if (net_eq(ns0, ns1))
+		return true;
+
+	mode0 = vsock_net_mode(ns0);
+	mode1 = vsock_net_mode(ns1);
+
+	/* Different namespaces are only reachable if they are both
+	 * global mode.
+	 */
+	return mode0 == VSOCK_NET_MODE_GLOBAL && mode0 == mode1;
+}
 #endif /* __AF_VSOCK_H__ */
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index cb664f6e3558..66d3de1d935f 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -37,6 +37,7 @@
 #include <net/netns/smc.h>
 #include <net/netns/bpf.h>
 #include <net/netns/mctp.h>
+#include <net/netns/vsock.h>
 #include <net/net_trackers.h>
 #include <linux/ns_common.h>
 #include <linux/idr.h>
@@ -196,6 +197,9 @@ struct net {
 	/* Move to a better place when the config guard is removed. */
 	struct mutex		rtnl_mutex;
 #endif
+#if IS_ENABLED(CONFIG_VSOCKETS)
+	struct netns_vsock	vsock;
+#endif
 } __randomize_layout;
 
 #include <linux/seq_file_net.h>
diff --git a/include/net/netns/vsock.h b/include/net/netns/vsock.h
new file mode 100644
index 000000000000..b34d69a22fa8
--- /dev/null
+++ b/include/net/netns/vsock.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_NET_NAMESPACE_VSOCK_H
+#define __NET_NET_NAMESPACE_VSOCK_H
+
+#include <linux/types.h>
+
+enum vsock_net_mode {
+	VSOCK_NET_MODE_GLOBAL,
+	VSOCK_NET_MODE_LOCAL,
+};
+
+struct netns_vsock {
+	struct ctl_table_header *sysctl_hdr;
+
+	/* protected by the vsock_table_lock in af_vsock.c */
+	u32 port;
+
+	enum vsock_net_mode mode;
+	enum vsock_net_mode child_ns_mode;
+};
+#endif /* __NET_NET_NAMESPACE_VSOCK_H */