[PATCH net-next v6 1/9] vsock: a per-net vsock NS mode state

[Bobby Eshleman <bobbyeshleman@gmail.com>]

From: Bobby Eshleman <bobbyeshleman@meta.com>

Add the per-net vsock NS mode state. This only adds the structure for
holding the mode and some of the functions for setting/getting and
checking the mode, but does not integrate the functionality yet.

Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>

---
Changes in v6:
- add orig_net_mode to store mode at creation time which will be used to
  avoid breakage when namespace changes mode during socket/VM lifespan

Changes in v5:
- use /proc/sys/net/vsock/ns_mode instead of /proc/net/vsock_ns_mode
- change from net->vsock.ns_mode to net->vsock.mode
- change vsock_net_set_mode() to vsock_net_write_mode()
- vsock_net_write_mode() returns bool for write success to avoid
  need to use vsock_net_mode_can_set()
- remove vsock_net_mode_can_set()
---
 MAINTAINERS                 |  1 +
 include/net/af_vsock.h      | 55 +++++++++++++++++++++++++++++++++++++++++++++
 include/net/net_namespace.h |  4 ++++
 include/net/netns/vsock.h   | 20 +++++++++++++++++
 4 files changed, 80 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 47bc35743f22..bc53c67e0926 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26634,6 +26634,7 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/vhost/vsock.c
 F:	include/linux/virtio_vsock.h
+F:	include/net/netns/vsock.h
 F:	include/uapi/linux/virtio_vsock.h
 F:	net/vmw_vsock/virtio_transport.c
 F:	net/vmw_vsock/virtio_transport_common.c
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index d40e978126e3..2857e97699de 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>
 
@@ -65,6 +66,7 @@ struct vsock_sock {
 	u32 peer_shutdown;
 	bool sent_request;
 	bool ignore_connecting_rst;
+	enum vsock_net_mode orig_net_mode;
 
 	/* Protected by lock_sock(sk) */
 	u64 buffer_size;
@@ -256,4 +258,57 @@ 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)
+{
+	enum vsock_net_mode ret;
+
+	spin_lock_bh(&net->vsock.lock);
+	ret = net->vsock.mode;
+	spin_unlock_bh(&net->vsock.lock);
+	return ret;
+}
+
+static inline bool vsock_net_write_mode(struct net *net, u8 mode)
+{
+	bool ret;
+
+	spin_lock_bh(&net->vsock.lock);
+
+	if (net->vsock.written) {
+		ret = false;
+		goto skip;
+	}
+
+	net->vsock.mode = mode;
+	net->vsock.written = true;
+	ret = true;
+
+skip:
+	spin_unlock_bh(&net->vsock.lock);
+	return ret;
+}
+
+/* Return true if vsock_sock passes the mode rules for a given net and
+ * orig_net_mode. Otherwise, return false.
+ *
+ * net is the current net namespace of the object being checked. orig_net_mode
+ * is the mode of net when the object was created.
+ *
+ * orig_net_mode is the mode of arg 'net' at the time of creation for the
+ * object being checked. For example, if searching for a vsock_sock then
+ * orig_net_mode is arg net's mode at the time the vsock_sock was created.
+ *
+ * Read more about modes in the comment header of net/vmw_vsock/af_vsock.c.
+ */
+static inline bool vsock_net_check_mode(struct vsock_sock *vsk, struct net *net,
+					enum vsock_net_mode orig_net_mode)
+{
+	struct net *vsk_net = sock_net(sk_vsock(vsk));
+
+	if (net_eq(vsk_net, net))
+		return true;
+
+	return orig_net_mode == VSOCK_NET_MODE_GLOBAL && vsk->orig_net_mode == VSOCK_NET_MODE_GLOBAL;
+}
 #endif /* __AF_VSOCK_H__ */
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 025a7574b275..005c0da4fb62 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..d4593c0b8dc4
--- /dev/null
+++ b/include/net/netns/vsock.h
@@ -0,0 +1,20 @@
+/* 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 *vsock_hdr;
+	spinlock_t lock;
+
+	/* protected by lock */
+	enum vsock_net_mode mode;
+	bool written;
+};
+#endif /* __NET_NET_NAMESPACE_VSOCK_H */

-- 
2.47.3