Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 257 insertions, 0 deletions

diff --git a/ipc/namespace.c b/ipc/namespace.c
new file mode 100644
index 000000000..1e71353bd
--- /dev/null
+++ b/ipc/namespace.c
@@ -0,0 +1,257 @@
+// 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/nstree.h>
+#include <linux/sched/task.h>
+
+#include "util.h"
+
+/*
+ * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
+ */
+static void free_ipc(struct work_struct *unused);
+static DECLARE_WORK(free_ipc_work, free_ipc);
+
+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;
+ again:
+	ucounts = inc_ipc_namespaces(user_ns);
+	if (!ucounts) {
+		/*
+		 * IPC namespaces are freed asynchronously, by free_ipc_work.
+		 * If frees were pending, flush_work will wait, and
+		 * return true. Fail the allocation if no frees are pending.
+		 */
+		if (flush_work(&free_ipc_work))
+			goto again;
+		goto fail;
+	}
+
+	err = -ENOMEM;
+	ns = kzalloc_obj(struct ipc_namespace, GFP_KERNEL_ACCOUNT);
+	if (ns == NULL)
+		goto fail_dec;
+
+	err = ns_common_init(ns);
+	if (err)
+		goto fail_free;
+
+	ns_tree_gen_id(ns);
+	ns->user_ns = get_user_ns(user_ns);
+	ns->ucounts = ucounts;
+
+	err = mq_init_ns(ns);
+	if (err)
+		goto fail_put;
+
+	err = -ENOMEM;
+	if (!setup_mq_sysctls(ns))
+		goto fail_mq_mount;
+
+	if (!setup_ipc_sysctls(ns))
+		goto fail_mq_sysctls;
+
+	err = msg_init_ns(ns);
+	if (err)
+		goto fail_ipc;
+
+	sem_init_ns(ns);
+	shm_init_ns(ns);
+	ns_tree_add_raw(ns);
+
+	return ns;
+
+fail_ipc:
+	retire_ipc_sysctls(ns);
+fail_mq_sysctls:
+	retire_mq_sysctls(ns);
+fail_mq_mount:
+	mntput(ns->mq_mnt);
+fail_put:
+	put_user_ns(ns->user_ns);
+	ns_common_free(ns);
+fail_free:
+	kfree(ns);
+fail_dec:
+	dec_ipc_namespaces(ucounts);
+fail:
+	return ERR_PTR(err);
+}
+
+struct ipc_namespace *copy_ipcs(u64 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)
+{
+	/*
+	 * Caller needs to wait for an RCU grace period to have passed
+	 * after making the mount point inaccessible to new accesses.
+	 */
+	mntput(ns->mq_mnt);
+	sem_exit_ns(ns);
+	msg_exit_ns(ns);
+	shm_exit_ns(ns);
+
+	retire_mq_sysctls(ns);
+	retire_ipc_sysctls(ns);
+
+	dec_ipc_namespaces(ns->ucounts);
+	put_user_ns(ns->user_ns);
+	ns_common_free(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)
+		mnt_make_shortterm(n->mq_mnt);
+
+	/* Wait for any last users to have gone away. */
+	synchronize_rcu();
+
+	llist_for_each_entry_safe(n, t, node, mnt_llist)
+		free_ipc_ns(n);
+}
+
+/*
+ * 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 (ns_ref_put_and_lock(ns, &mq_lock)) {
+		mq_clear_sbinfo(ns);
+		spin_unlock(&mq_lock);
+
+		ns_tree_remove(ns);
+		if (llist_add(&ns->mnt_llist, &free_ipc_list))
+			schedule_work(&free_ipc_work);
+	}
+}
+
+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",
+	.get		= ipcns_get,
+	.put		= ipcns_put,
+	.install	= ipcns_install,
+	.owner		= ipcns_owner,
+};