1 files changed, 225 insertions, 0 deletions
diff --git a/ipc/namespace.c b/ipc/namespace.c
new file mode 100644
index 000000000..24e7b4532
--- /dev/null
+++ b/ipc/namespace.c
@@ -0,0 +1,225 @@
+// 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 = kzalloc(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)
+{
+	/* mq_put_mnt() waits for a grace period as kern_unmount()
+	 * uses synchronize_rcu().
+	 */
+	mq_put_mnt(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);
+}
+
+static LLIST_HEAD(free_ipc_list);
+static void free_ipc(struct work_struct *unused)
+{
+	struct llist_node *node = llist_del_all(&free_ipc_list);
+	struct ipc_namespace *n, *t;
+
+	llist_for_each_entry_safe(n, t, node, mnt_llist)
+		free_ipc_ns(n);
+}
+
+/*
+ * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
+ */
+static DECLARE_WORK(free_ipc_work, free_ipc);
+
+/*
+ * 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);
+
+		if (llist_add(&ns->mnt_llist, &free_ipc_list))
+			schedule_work(&free_ipc_work);
+	}
+}
+
+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 nsset *nsset, struct ns_common *new)
+{
+	struct nsproxy *nsproxy = nsset->nsproxy;
+	struct ipc_namespace *ns = to_ipc_ns(new);
+	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
+	    !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
+		return -EPERM;
+
+	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,
+};