VSOCK: add sock_diag interface
This patch adds the sock_diag interface for querying sockets from
userspace. Tools like ss(8) and netstat(8) can use this interface to
list open sockets.
The userspace ABI is defined in <linux/vm_sockets_diag.h> and includes
netlink request and response structs. The request can query sockets
based on their sk_state (e.g. listening sockets only) and the response
contains socket information fields including the local/remote addresses,
inode number, etc.
This patch does not dump VMCI pending sockets because I have only tested
the virtio transport, which does not use pending sockets. Support can
be added later by extending vsock_diag_dump() if needed by VMCI users.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/vmw_vsock/diag.c b/net/vmw_vsock/diag.c
new file mode 100644
index 0000000..31b5676
--- /dev/null
+++ b/net/vmw_vsock/diag.c
@@ -0,0 +1,186 @@
+/*
+ * vsock sock_diag(7) module
+ *
+ * Copyright (C) 2017 Red Hat, Inc.
+ * Author: Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation version 2 and no later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/module.h>
+#include <linux/sock_diag.h>
+#include <linux/vm_sockets_diag.h>
+#include <net/af_vsock.h>
+
+static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
+ u32 portid, u32 seq, u32 flags)
+{
+ struct vsock_sock *vsk = vsock_sk(sk);
+ struct vsock_diag_msg *rep;
+ struct nlmsghdr *nlh;
+
+ nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
+ flags);
+ if (!nlh)
+ return -EMSGSIZE;
+
+ rep = nlmsg_data(nlh);
+ rep->vdiag_family = AF_VSOCK;
+
+ /* Lock order dictates that sk_lock is acquired before
+ * vsock_table_lock, so we cannot lock here. Simply don't take
+ * sk_lock; sk is guaranteed to stay alive since vsock_table_lock is
+ * held.
+ */
+ rep->vdiag_type = sk->sk_type;
+ rep->vdiag_state = sk->sk_state;
+ rep->vdiag_shutdown = sk->sk_shutdown;
+ rep->vdiag_src_cid = vsk->local_addr.svm_cid;
+ rep->vdiag_src_port = vsk->local_addr.svm_port;
+ rep->vdiag_dst_cid = vsk->remote_addr.svm_cid;
+ rep->vdiag_dst_port = vsk->remote_addr.svm_port;
+ rep->vdiag_ino = sock_i_ino(sk);
+
+ sock_diag_save_cookie(sk, rep->vdiag_cookie);
+
+ return 0;
+}
+
+static int vsock_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
+{
+ struct vsock_diag_req *req;
+ struct vsock_sock *vsk;
+ unsigned int bucket;
+ unsigned int last_i;
+ unsigned int table;
+ struct net *net;
+ unsigned int i;
+
+ req = nlmsg_data(cb->nlh);
+ net = sock_net(skb->sk);
+
+ /* State saved between calls: */
+ table = cb->args[0];
+ bucket = cb->args[1];
+ i = last_i = cb->args[2];
+
+ /* TODO VMCI pending sockets? */
+
+ spin_lock_bh(&vsock_table_lock);
+
+ /* Bind table (locally created sockets) */
+ if (table == 0) {
+ while (bucket < ARRAY_SIZE(vsock_bind_table)) {
+ struct list_head *head = &vsock_bind_table[bucket];
+
+ i = 0;
+ list_for_each_entry(vsk, head, bound_table) {
+ struct sock *sk = sk_vsock(vsk);
+
+ if (!net_eq(sock_net(sk), net))
+ continue;
+ if (i < last_i)
+ goto next_bind;
+ if (!(req->vdiag_states & (1 << sk->sk_state)))
+ goto next_bind;
+ if (sk_diag_fill(sk, skb,
+ NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq,
+ NLM_F_MULTI) < 0)
+ goto done;
+next_bind:
+ i++;
+ }
+ last_i = 0;
+ bucket++;
+ }
+
+ table++;
+ bucket = 0;
+ }
+
+ /* Connected table (accepted connections) */
+ while (bucket < ARRAY_SIZE(vsock_connected_table)) {
+ struct list_head *head = &vsock_connected_table[bucket];
+
+ i = 0;
+ list_for_each_entry(vsk, head, connected_table) {
+ struct sock *sk = sk_vsock(vsk);
+
+ /* Skip sockets we've already seen above */
+ if (__vsock_in_bound_table(vsk))
+ continue;
+
+ if (!net_eq(sock_net(sk), net))
+ continue;
+ if (i < last_i)
+ goto next_connected;
+ if (!(req->vdiag_states & (1 << sk->sk_state)))
+ goto next_connected;
+ if (sk_diag_fill(sk, skb,
+ NETLINK_CB(cb->skb).portid,
+ cb->nlh->nlmsg_seq,
+ NLM_F_MULTI) < 0)
+ goto done;
+next_connected:
+ i++;
+ }
+ last_i = 0;
+ bucket++;
+ }
+
+done:
+ spin_unlock_bh(&vsock_table_lock);
+
+ cb->args[0] = table;
+ cb->args[1] = bucket;
+ cb->args[2] = i;
+
+ return skb->len;
+}
+
+static int vsock_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
+{
+ int hdrlen = sizeof(struct vsock_diag_req);
+ struct net *net = sock_net(skb->sk);
+
+ if (nlmsg_len(h) < hdrlen)
+ return -EINVAL;
+
+ if (h->nlmsg_flags & NLM_F_DUMP) {
+ struct netlink_dump_control c = {
+ .dump = vsock_diag_dump,
+ };
+ return netlink_dump_start(net->diag_nlsk, skb, h, &c);
+ }
+
+ return -EOPNOTSUPP;
+}
+
+static const struct sock_diag_handler vsock_diag_handler = {
+ .family = AF_VSOCK,
+ .dump = vsock_diag_handler_dump,
+};
+
+static int __init vsock_diag_init(void)
+{
+ return sock_diag_register(&vsock_diag_handler);
+}
+
+static void __exit vsock_diag_exit(void)
+{
+ sock_diag_unregister(&vsock_diag_handler);
+}
+
+module_init(vsock_diag_init);
+module_exit(vsock_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG,
+ 40 /* AF_VSOCK */);