v4.19.13 snapshot.
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
new file mode 100644
index 0000000..d6b74b9
--- /dev/null
+++ b/include/linux/user_namespace.h
@@ -0,0 +1,175 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_USER_NAMESPACE_H
+#define _LINUX_USER_NAMESPACE_H
+
+#include <linux/kref.h>
+#include <linux/nsproxy.h>
+#include <linux/ns_common.h>
+#include <linux/sched.h>
+#include <linux/workqueue.h>
+#include <linux/rwsem.h>
+#include <linux/sysctl.h>
+#include <linux/err.h>
+
+#define UID_GID_MAP_MAX_BASE_EXTENTS 5
+#define UID_GID_MAP_MAX_EXTENTS 340
+
+struct uid_gid_extent {
+ u32 first;
+ u32 lower_first;
+ u32 count;
+};
+
+struct uid_gid_map { /* 64 bytes -- 1 cache line */
+ u32 nr_extents;
+ union {
+ struct uid_gid_extent extent[UID_GID_MAP_MAX_BASE_EXTENTS];
+ struct {
+ struct uid_gid_extent *forward;
+ struct uid_gid_extent *reverse;
+ };
+ };
+};
+
+#define USERNS_SETGROUPS_ALLOWED 1UL
+
+#define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED
+
+struct ucounts;
+
+enum ucount_type {
+ UCOUNT_USER_NAMESPACES,
+ UCOUNT_PID_NAMESPACES,
+ UCOUNT_UTS_NAMESPACES,
+ UCOUNT_IPC_NAMESPACES,
+ UCOUNT_NET_NAMESPACES,
+ UCOUNT_MNT_NAMESPACES,
+ UCOUNT_CGROUP_NAMESPACES,
+#ifdef CONFIG_INOTIFY_USER
+ UCOUNT_INOTIFY_INSTANCES,
+ UCOUNT_INOTIFY_WATCHES,
+#endif
+ UCOUNT_COUNTS,
+};
+
+struct user_namespace {
+ struct uid_gid_map uid_map;
+ struct uid_gid_map gid_map;
+ struct uid_gid_map projid_map;
+ atomic_t count;
+ struct user_namespace *parent;
+ int level;
+ kuid_t owner;
+ kgid_t group;
+ struct ns_common ns;
+ unsigned long flags;
+
+ /* Register of per-UID persistent keyrings for this namespace */
+#ifdef CONFIG_PERSISTENT_KEYRINGS
+ struct key *persistent_keyring_register;
+ struct rw_semaphore persistent_keyring_register_sem;
+#endif
+ struct work_struct work;
+#ifdef CONFIG_SYSCTL
+ struct ctl_table_set set;
+ struct ctl_table_header *sysctls;
+#endif
+ struct ucounts *ucounts;
+ int ucount_max[UCOUNT_COUNTS];
+} __randomize_layout;
+
+struct ucounts {
+ struct hlist_node node;
+ struct user_namespace *ns;
+ kuid_t uid;
+ int count;
+ atomic_t ucount[UCOUNT_COUNTS];
+};
+
+extern struct user_namespace init_user_ns;
+
+bool setup_userns_sysctls(struct user_namespace *ns);
+void retire_userns_sysctls(struct user_namespace *ns);
+struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid, enum ucount_type type);
+void dec_ucount(struct ucounts *ucounts, enum ucount_type type);
+
+#ifdef CONFIG_USER_NS
+
+static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
+{
+ if (ns)
+ atomic_inc(&ns->count);
+ return ns;
+}
+
+extern int create_user_ns(struct cred *new);
+extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);
+extern void __put_user_ns(struct user_namespace *ns);
+
+static inline void put_user_ns(struct user_namespace *ns)
+{
+ if (ns && atomic_dec_and_test(&ns->count))
+ __put_user_ns(ns);
+}
+
+struct seq_operations;
+extern const struct seq_operations proc_uid_seq_operations;
+extern const struct seq_operations proc_gid_seq_operations;
+extern const struct seq_operations proc_projid_seq_operations;
+extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
+extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);
+extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);
+extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
+extern int proc_setgroups_show(struct seq_file *m, void *v);
+extern bool userns_may_setgroups(const struct user_namespace *ns);
+extern bool in_userns(const struct user_namespace *ancestor,
+ const struct user_namespace *child);
+extern bool current_in_userns(const struct user_namespace *target_ns);
+struct ns_common *ns_get_owner(struct ns_common *ns);
+#else
+
+static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
+{
+ return &init_user_ns;
+}
+
+static inline int create_user_ns(struct cred *new)
+{
+ return -EINVAL;
+}
+
+static inline int unshare_userns(unsigned long unshare_flags,
+ struct cred **new_cred)
+{
+ if (unshare_flags & CLONE_NEWUSER)
+ return -EINVAL;
+ return 0;
+}
+
+static inline void put_user_ns(struct user_namespace *ns)
+{
+}
+
+static inline bool userns_may_setgroups(const struct user_namespace *ns)
+{
+ return true;
+}
+
+static inline bool in_userns(const struct user_namespace *ancestor,
+ const struct user_namespace *child)
+{
+ return true;
+}
+
+static inline bool current_in_userns(const struct user_namespace *target_ns)
+{
+ return true;
+}
+
+static inline struct ns_common *ns_get_owner(struct ns_common *ns)
+{
+ return ERR_PTR(-EPERM);
+}
+#endif
+
+#endif /* _LINUX_USER_H */