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

On Tue, Sep 16, 2025 at 04:43:45PM -0700, Bobby Eshleman wrote:

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;

Why `orig_` prefix?

Maybe I need to review all the series, but it's a bit confusing for now. I guess it's related to the new behaviour to not change the mode of already created sockets (which I like), but IMHO this variable prefix is confusing.It seems we will have another field with the "actual_" mode, but if it's immutable, I'd avoid that prefix.

/* 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 also explained in the next paragraph, should we remove from here?

• • 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;

nit: I'd rewrite in this way, just because it seems easy to read to me, but again not strong opinion, this is fine:

return orig_net_mode == VSOCK_NET_MODE_GLOBAL && orig_net_mode == vsk->orig_net_mode;

+} #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;

sysctl_header, or sysctl_hdr, or sysctl_ctl ? I'd remove `vsock_` prefix and make more clear its used for sysctl.

• spinlock_t lock;
• /* protected by lock */
• enum vsock_net_mode mode;
• bool written;

I would call this `mode_set` or `mode_locked`, I mean with `mode_` prefix to make sure we don't need to rename it when we will add new fields in the future.

Thanks Stefano

+}; +#endif /* __NET_NET_NAMESPACE_VSOCK_H */

-- 2.47.3