v4.19.13 snapshot.
diff --git a/ipc/namespace.c b/ipc/namespace.c
new file mode 100644
index 0000000..2160779
--- /dev/null
+++ b/ipc/namespace.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/ipc/namespace.c
+ * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
+ */
+
+#include <linux/ipc.h>
+#include <linux/msg.h>
+#include <linux/ipc_namespace.h>
+#include <linux/rcupdate.h>
+#include <linux/nsproxy.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/user_namespace.h>
+#include <linux/proc_ns.h>
+#include <linux/sched/task.h>
+
+#include "util.h"
+
+static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
+}
+
+static void dec_ipc_namespaces(struct ucounts *ucounts)
+{
+ dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
+}
+
+static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
+ struct ipc_namespace *old_ns)
+{
+ struct ipc_namespace *ns;
+ struct ucounts *ucounts;
+ int err;
+
+ err = -ENOSPC;
+ ucounts = inc_ipc_namespaces(user_ns);
+ if (!ucounts)
+ goto fail;
+
+ err = -ENOMEM;
+ ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
+ if (ns == NULL)
+ goto fail_dec;
+
+ err = ns_alloc_inum(&ns->ns);
+ if (err)
+ goto fail_free;
+ ns->ns.ops = &ipcns_operations;
+
+ refcount_set(&ns->count, 1);
+ ns->user_ns = get_user_ns(user_ns);
+ ns->ucounts = ucounts;
+
+ err = mq_init_ns(ns);
+ if (err)
+ goto fail_put;
+
+ sem_init_ns(ns);
+ msg_init_ns(ns);
+ shm_init_ns(ns);
+
+ return ns;
+
+fail_put:
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+fail_free:
+ kfree(ns);
+fail_dec:
+ dec_ipc_namespaces(ucounts);
+fail:
+ return ERR_PTR(err);
+}
+
+struct ipc_namespace *copy_ipcs(unsigned long flags,
+ struct user_namespace *user_ns, struct ipc_namespace *ns)
+{
+ if (!(flags & CLONE_NEWIPC))
+ return get_ipc_ns(ns);
+ return create_ipc_ns(user_ns, ns);
+}
+
+/*
+ * free_ipcs - free all ipcs of one type
+ * @ns: the namespace to remove the ipcs from
+ * @ids: the table of ipcs to free
+ * @free: the function called to free each individual ipc
+ *
+ * Called for each kind of ipc when an ipc_namespace exits.
+ */
+void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
+ void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
+{
+ struct kern_ipc_perm *perm;
+ int next_id;
+ int total, in_use;
+
+ down_write(&ids->rwsem);
+
+ in_use = ids->in_use;
+
+ for (total = 0, next_id = 0; total < in_use; next_id++) {
+ perm = idr_find(&ids->ipcs_idr, next_id);
+ if (perm == NULL)
+ continue;
+ rcu_read_lock();
+ ipc_lock_object(perm);
+ free(ns, perm);
+ total++;
+ }
+ up_write(&ids->rwsem);
+}
+
+static void free_ipc_ns(struct ipc_namespace *ns)
+{
+ sem_exit_ns(ns);
+ msg_exit_ns(ns);
+ shm_exit_ns(ns);
+
+ dec_ipc_namespaces(ns->ucounts);
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+ kfree(ns);
+}
+
+/*
+ * put_ipc_ns - drop a reference to an ipc namespace.
+ * @ns: the namespace to put
+ *
+ * If this is the last task in the namespace exiting, and
+ * it is dropping the refcount to 0, then it can race with
+ * a task in another ipc namespace but in a mounts namespace
+ * which has this ipcns's mqueuefs mounted, doing some action
+ * with one of the mqueuefs files. That can raise the refcount.
+ * So dropping the refcount, and raising the refcount when
+ * accessing it through the VFS, are protected with mq_lock.
+ *
+ * (Clearly, a task raising the refcount on its own ipc_ns
+ * needn't take mq_lock since it can't race with the last task
+ * in the ipcns exiting).
+ */
+void put_ipc_ns(struct ipc_namespace *ns)
+{
+ if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
+ mq_clear_sbinfo(ns);
+ spin_unlock(&mq_lock);
+ mq_put_mnt(ns);
+ free_ipc_ns(ns);
+ }
+}
+
+static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
+{
+ return container_of(ns, struct ipc_namespace, ns);
+}
+
+static struct ns_common *ipcns_get(struct task_struct *task)
+{
+ struct ipc_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ task_lock(task);
+ nsproxy = task->nsproxy;
+ if (nsproxy)
+ ns = get_ipc_ns(nsproxy->ipc_ns);
+ task_unlock(task);
+
+ return ns ? &ns->ns : NULL;
+}
+
+static void ipcns_put(struct ns_common *ns)
+{
+ return put_ipc_ns(to_ipc_ns(ns));
+}
+
+static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
+{
+ struct ipc_namespace *ns = to_ipc_ns(new);
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+ !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Ditch state from the old ipc namespace */
+ exit_sem(current);
+ put_ipc_ns(nsproxy->ipc_ns);
+ nsproxy->ipc_ns = get_ipc_ns(ns);
+ return 0;
+}
+
+static struct user_namespace *ipcns_owner(struct ns_common *ns)
+{
+ return to_ipc_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations ipcns_operations = {
+ .name = "ipc",
+ .type = CLONE_NEWIPC,
+ .get = ipcns_get,
+ .put = ipcns_put,
+ .install = ipcns_install,
+ .owner = ipcns_owner,
+};