v4.19.13 snapshot.
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
new file mode 100644
index 0000000..9aed6fe
--- /dev/null
+++ b/net/sysctl_net.c
@@ -0,0 +1,128 @@
+/* -*- linux-c -*-
+ * sysctl_net.c: sysctl interface to net subsystem.
+ *
+ * Begun April 1, 1996, Mike Shaver.
+ * Added /proc/sys/net directories for each protocol family. [MS]
+ *
+ * Revision 1.2 1996/05/08 20:24:40 shaver
+ * Added bits for NET_BRIDGE and the NET_IPV4_ARP stuff and
+ * NET_IPV4_IP_FORWARD.
+ *
+ *
+ */
+
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/sysctl.h>
+#include <linux/nsproxy.h>
+
+#include <net/sock.h>
+
+#ifdef CONFIG_INET
+#include <net/ip.h>
+#endif
+
+#ifdef CONFIG_NET
+#include <linux/if_ether.h>
+#endif
+
+static struct ctl_table_set *
+net_ctl_header_lookup(struct ctl_table_root *root)
+{
+ return ¤t->nsproxy->net_ns->sysctls;
+}
+
+static int is_seen(struct ctl_table_set *set)
+{
+ return ¤t->nsproxy->net_ns->sysctls == set;
+}
+
+/* Return standard mode bits for table entry. */
+static int net_ctl_permissions(struct ctl_table_header *head,
+ struct ctl_table *table)
+{
+ struct net *net = container_of(head->set, struct net, sysctls);
+
+ /* Allow network administrator to have same access as root. */
+ if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {
+ int mode = (table->mode >> 6) & 7;
+ return (mode << 6) | (mode << 3) | mode;
+ }
+
+ return table->mode;
+}
+
+static void net_ctl_set_ownership(struct ctl_table_header *head,
+ struct ctl_table *table,
+ kuid_t *uid, kgid_t *gid)
+{
+ struct net *net = container_of(head->set, struct net, sysctls);
+ kuid_t ns_root_uid;
+ kgid_t ns_root_gid;
+
+ ns_root_uid = make_kuid(net->user_ns, 0);
+ if (uid_valid(ns_root_uid))
+ *uid = ns_root_uid;
+
+ ns_root_gid = make_kgid(net->user_ns, 0);
+ if (gid_valid(ns_root_gid))
+ *gid = ns_root_gid;
+}
+
+static struct ctl_table_root net_sysctl_root = {
+ .lookup = net_ctl_header_lookup,
+ .permissions = net_ctl_permissions,
+ .set_ownership = net_ctl_set_ownership,
+};
+
+static int __net_init sysctl_net_init(struct net *net)
+{
+ setup_sysctl_set(&net->sysctls, &net_sysctl_root, is_seen);
+ return 0;
+}
+
+static void __net_exit sysctl_net_exit(struct net *net)
+{
+ retire_sysctl_set(&net->sysctls);
+}
+
+static struct pernet_operations sysctl_pernet_ops = {
+ .init = sysctl_net_init,
+ .exit = sysctl_net_exit,
+};
+
+static struct ctl_table_header *net_header;
+__init int net_sysctl_init(void)
+{
+ static struct ctl_table empty[1];
+ int ret = -ENOMEM;
+ /* Avoid limitations in the sysctl implementation by
+ * registering "/proc/sys/net" as an empty directory not in a
+ * network namespace.
+ */
+ net_header = register_sysctl("net", empty);
+ if (!net_header)
+ goto out;
+ ret = register_pernet_subsys(&sysctl_pernet_ops);
+ if (ret)
+ goto out1;
+out:
+ return ret;
+out1:
+ unregister_sysctl_table(net_header);
+ net_header = NULL;
+ goto out;
+}
+
+struct ctl_table_header *register_net_sysctl(struct net *net,
+ const char *path, struct ctl_table *table)
+{
+ return __register_sysctl_table(&net->sysctls, path, table);
+}
+EXPORT_SYMBOL_GPL(register_net_sysctl);
+
+void unregister_net_sysctl_table(struct ctl_table_header *header)
+{
+ unregister_sysctl_table(header);
+}
+EXPORT_SYMBOL_GPL(unregister_net_sysctl_table);