v4.19.13 snapshot.
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
new file mode 100644
index 0000000..b3d5150
--- /dev/null
+++ b/net/unix/sysctl_net_unix.c
@@ -0,0 +1,61 @@
+/*
+ * NET4: Sysctl interface to net af_unix subsystem.
+ *
+ * Authors: Mike Shaver.
+ *
+ * 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; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
+
+#include <net/af_unix.h>
+
+static struct ctl_table unix_table[] = {
+ {
+ .procname = "max_dgram_qlen",
+ .data = &init_net.unx.sysctl_max_dgram_qlen,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec
+ },
+ { }
+};
+
+int __net_init unix_sysctl_register(struct net *net)
+{
+ struct ctl_table *table;
+
+ table = kmemdup(unix_table, sizeof(unix_table), GFP_KERNEL);
+ if (table == NULL)
+ goto err_alloc;
+
+ /* Don't export sysctls to unprivileged users */
+ if (net->user_ns != &init_user_ns)
+ table[0].procname = NULL;
+
+ table[0].data = &net->unx.sysctl_max_dgram_qlen;
+ net->unx.ctl = register_net_sysctl(net, "net/unix", table);
+ if (net->unx.ctl == NULL)
+ goto err_reg;
+
+ return 0;
+
+err_reg:
+ kfree(table);
+err_alloc:
+ return -ENOMEM;
+}
+
+void unix_sysctl_unregister(struct net *net)
+{
+ struct ctl_table *table;
+
+ table = net->unx.ctl->ctl_table_arg;
+ unregister_net_sysctl_table(net->unx.ctl);
+ kfree(table);
+}