v4.19.13 snapshot.
diff --git a/kernel/utsname.c b/kernel/utsname.c
new file mode 100644
index 0000000..dcd6be1
--- /dev/null
+++ b/kernel/utsname.c
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2004 IBM Corporation
+ *
+ * Author: Serge Hallyn <serue@us.ibm.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 of the
+ * License.
+ */
+
+#include <linux/export.h>
+#include <linux/uts.h>
+#include <linux/utsname.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/user_namespace.h>
+#include <linux/proc_ns.h>
+#include <linux/sched/task.h>
+
+static struct kmem_cache *uts_ns_cache __ro_after_init;
+
+static struct ucounts *inc_uts_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_UTS_NAMESPACES);
+}
+
+static void dec_uts_namespaces(struct ucounts *ucounts)
+{
+ dec_ucount(ucounts, UCOUNT_UTS_NAMESPACES);
+}
+
+static struct uts_namespace *create_uts_ns(void)
+{
+ struct uts_namespace *uts_ns;
+
+ uts_ns = kmem_cache_alloc(uts_ns_cache, GFP_KERNEL);
+ if (uts_ns)
+ kref_init(&uts_ns->kref);
+ return uts_ns;
+}
+
+/*
+ * Clone a new ns copying an original utsname, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return ERR_PTR(-ENOMEM) on error (failure to allocate), new ns otherwise
+ */
+static struct uts_namespace *clone_uts_ns(struct user_namespace *user_ns,
+ struct uts_namespace *old_ns)
+{
+ struct uts_namespace *ns;
+ struct ucounts *ucounts;
+ int err;
+
+ err = -ENOSPC;
+ ucounts = inc_uts_namespaces(user_ns);
+ if (!ucounts)
+ goto fail;
+
+ err = -ENOMEM;
+ ns = create_uts_ns();
+ if (!ns)
+ goto fail_dec;
+
+ err = ns_alloc_inum(&ns->ns);
+ if (err)
+ goto fail_free;
+
+ ns->ucounts = ucounts;
+ ns->ns.ops = &utsns_operations;
+
+ down_read(&uts_sem);
+ memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+ ns->user_ns = get_user_ns(user_ns);
+ up_read(&uts_sem);
+ return ns;
+
+fail_free:
+ kmem_cache_free(uts_ns_cache, ns);
+fail_dec:
+ dec_uts_namespaces(ucounts);
+fail:
+ return ERR_PTR(err);
+}
+
+/*
+ * Copy task tsk's utsname namespace, or clone it if flags
+ * specifies CLONE_NEWUTS. In latter case, changes to the
+ * utsname of this process won't be seen by parent, and vice
+ * versa.
+ */
+struct uts_namespace *copy_utsname(unsigned long flags,
+ struct user_namespace *user_ns, struct uts_namespace *old_ns)
+{
+ struct uts_namespace *new_ns;
+
+ BUG_ON(!old_ns);
+ get_uts_ns(old_ns);
+
+ if (!(flags & CLONE_NEWUTS))
+ return old_ns;
+
+ new_ns = clone_uts_ns(user_ns, old_ns);
+
+ put_uts_ns(old_ns);
+ return new_ns;
+}
+
+void free_uts_ns(struct kref *kref)
+{
+ struct uts_namespace *ns;
+
+ ns = container_of(kref, struct uts_namespace, kref);
+ dec_uts_namespaces(ns->ucounts);
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+ kmem_cache_free(uts_ns_cache, ns);
+}
+
+static inline struct uts_namespace *to_uts_ns(struct ns_common *ns)
+{
+ return container_of(ns, struct uts_namespace, ns);
+}
+
+static struct ns_common *utsns_get(struct task_struct *task)
+{
+ struct uts_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ task_lock(task);
+ nsproxy = task->nsproxy;
+ if (nsproxy) {
+ ns = nsproxy->uts_ns;
+ get_uts_ns(ns);
+ }
+ task_unlock(task);
+
+ return ns ? &ns->ns : NULL;
+}
+
+static void utsns_put(struct ns_common *ns)
+{
+ put_uts_ns(to_uts_ns(ns));
+}
+
+static int utsns_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+ struct uts_namespace *ns = to_uts_ns(new);
+
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+ !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+ return -EPERM;
+
+ get_uts_ns(ns);
+ put_uts_ns(nsproxy->uts_ns);
+ nsproxy->uts_ns = ns;
+ return 0;
+}
+
+static struct user_namespace *utsns_owner(struct ns_common *ns)
+{
+ return to_uts_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations utsns_operations = {
+ .name = "uts",
+ .type = CLONE_NEWUTS,
+ .get = utsns_get,
+ .put = utsns_put,
+ .install = utsns_install,
+ .owner = utsns_owner,
+};
+
+void __init uts_ns_init(void)
+{
+ uts_ns_cache = kmem_cache_create_usercopy(
+ "uts_namespace", sizeof(struct uts_namespace), 0,
+ SLAB_PANIC|SLAB_ACCOUNT,
+ offsetof(struct uts_namespace, name),
+ sizeof_field(struct uts_namespace, name),
+ NULL);
+}