Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

5 files changed, 973 insertions, 0 deletions

diff --git a/drivers/connector/Kconfig b/drivers/connector/Kconfig
new file mode 100644
index 000000000..0c2d2aa82
--- /dev/null
+++ b/drivers/connector/Kconfig
@@ -0,0 +1,23 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menuconfig CONNECTOR
+	tristate "Connector - unified userspace <-> kernelspace linker"
+	depends on NET
+	help
+	  This is unified userspace <-> kernelspace connector working on top
+	  of the netlink socket protocol.
+
+	  Connector support can also be built as a module.  If so, the module
+	  will be called cn.
+
+if CONNECTOR
+
+config PROC_EVENTS
+	bool "Report process events to userspace"
+	depends on CONNECTOR=y
+	default y
+	help
+	  Provide a connector that reports process events to userspace. Send
+	  events such as fork, exec, id change (uid, gid, suid, etc), and exit.
+
+endif # CONNECTOR
diff --git a/drivers/connector/Makefile b/drivers/connector/Makefile
new file mode 100644
index 000000000..1bf67d3df
--- /dev/null
+++ b/drivers/connector/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_CONNECTOR)		+= cn.o
+obj-$(CONFIG_PROC_EVENTS)	+= cn_proc.o
+
+cn-y				+= cn_queue.o connector.o
diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
new file mode 100644
index 000000000..0056ab81f
--- /dev/null
+++ b/drivers/connector/cn_proc.c
@@ -0,0 +1,483 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * cn_proc.c - process events connector
+ *
+ * Copyright (C) Matt Helsley, IBM Corp. 2005
+ * Based on cn_fork.c by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
+ * Original copyright notice follows:
+ * Copyright (C) 2005 BULL SA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/init.h>
+#include <linux/connector.h>
+#include <linux/gfp.h>
+#include <linux/ptrace.h>
+#include <linux/atomic.h>
+#include <linux/pid_namespace.h>
+
+#include <linux/cn_proc.h>
+#include <linux/local_lock.h>
+
+/*
+ * Size of a cn_msg followed by a proc_event structure.  Since the
+ * sizeof struct cn_msg is a multiple of 4 bytes, but not 8 bytes, we
+ * add one 4-byte word to the size here, and then start the actual
+ * cn_msg structure 4 bytes into the stack buffer.  The result is that
+ * the immediately following proc_event structure is aligned to 8 bytes.
+ */
+#define CN_PROC_MSG_SIZE (sizeof(struct cn_msg) + sizeof(struct proc_event) + 4)
+
+/* See comment above; we test our assumption about sizeof struct cn_msg here. */
+static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
+{
+	BUILD_BUG_ON(sizeof(struct cn_msg) != 20);
+	return (struct cn_msg *)(buffer + 4);
+}
+
+static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
+static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
+
+/* local_event.count is used as the sequence number of the netlink message */
+struct local_event {
+	local_lock_t lock;
+	__u32 count;
+};
+static DEFINE_PER_CPU(struct local_event, local_event) = {
+	.lock = INIT_LOCAL_LOCK(lock),
+};
+
+static int cn_filter(struct sock *dsk, struct sk_buff *skb, void *data)
+{
+	__u32 what, exit_code, *ptr;
+	enum proc_cn_mcast_op mc_op;
+	uintptr_t val;
+
+	if (!dsk || !dsk->sk_user_data || !data)
+		return 0;
+
+	ptr = (__u32 *)data;
+	what = *ptr++;
+	exit_code = *ptr;
+	val = ((struct proc_input *)(dsk->sk_user_data))->event_type;
+	mc_op = ((struct proc_input *)(dsk->sk_user_data))->mcast_op;
+
+	if (mc_op == PROC_CN_MCAST_IGNORE)
+		return 1;
+
+	if ((__u32)val == PROC_EVENT_ALL)
+		return 0;
+
+	/*
+	 * Drop packet if we have to report only non-zero exit status
+	 * (PROC_EVENT_NONZERO_EXIT) and exit status is 0
+	 */
+	if (((__u32)val & PROC_EVENT_NONZERO_EXIT) &&
+	    (what == PROC_EVENT_EXIT)) {
+		if (exit_code)
+			return 0;
+	}
+
+	if ((__u32)val & what)
+		return 0;
+
+	return 1;
+}
+
+static inline void send_msg(struct cn_msg *msg)
+{
+	__u32 filter_data[2];
+
+	local_lock(&local_event.lock);
+
+	msg->seq = __this_cpu_inc_return(local_event.count) - 1;
+	((struct proc_event *)msg->data)->cpu = smp_processor_id();
+
+	/*
+	 * local_lock() disables preemption during send to ensure the messages
+	 * are ordered according to their sequence numbers.
+	 *
+	 * If cn_netlink_send() fails, the data is not sent.
+	 */
+	filter_data[0] = ((struct proc_event *)msg->data)->what;
+	if (filter_data[0] == PROC_EVENT_EXIT) {
+		filter_data[1] =
+		((struct proc_event *)msg->data)->event_data.exit.exit_code;
+	} else {
+		filter_data[1] = 0;
+	}
+
+	cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
+			     cn_filter, (void *)filter_data);
+
+	local_unlock(&local_event.lock);
+}
+
+void proc_fork_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct task_struct *parent;
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_FORK;
+	rcu_read_lock();
+	parent = rcu_dereference(task->real_parent);
+	ev->event_data.fork.parent_pid = parent->pid;
+	ev->event_data.fork.parent_tgid = parent->tgid;
+	rcu_read_unlock();
+	ev->event_data.fork.child_pid = task->pid;
+	ev->event_data.fork.child_tgid = task->tgid;
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_exec_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_EXEC;
+	ev->event_data.exec.process_pid = task->pid;
+	ev->event_data.exec.process_tgid = task->tgid;
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_id_connector(struct task_struct *task, int which_id)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	const struct cred *cred;
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->what = which_id;
+	ev->event_data.id.process_pid = task->pid;
+	ev->event_data.id.process_tgid = task->tgid;
+	rcu_read_lock();
+	cred = __task_cred(task);
+	if (which_id == PROC_EVENT_UID) {
+		ev->event_data.id.r.ruid = from_kuid_munged(&init_user_ns, cred->uid);
+		ev->event_data.id.e.euid = from_kuid_munged(&init_user_ns, cred->euid);
+	} else if (which_id == PROC_EVENT_GID) {
+		ev->event_data.id.r.rgid = from_kgid_munged(&init_user_ns, cred->gid);
+		ev->event_data.id.e.egid = from_kgid_munged(&init_user_ns, cred->egid);
+	} else {
+		rcu_read_unlock();
+		return;
+	}
+	rcu_read_unlock();
+	ev->timestamp_ns = ktime_get_ns();
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_sid_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_SID;
+	ev->event_data.sid.process_pid = task->pid;
+	ev->event_data.sid.process_tgid = task->tgid;
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_PTRACE;
+	ev->event_data.ptrace.process_pid  = task->pid;
+	ev->event_data.ptrace.process_tgid = task->tgid;
+	if (ptrace_id == PTRACE_ATTACH) {
+		ev->event_data.ptrace.tracer_pid  = current->pid;
+		ev->event_data.ptrace.tracer_tgid = current->tgid;
+	} else if (ptrace_id == PTRACE_DETACH) {
+		ev->event_data.ptrace.tracer_pid  = 0;
+		ev->event_data.ptrace.tracer_tgid = 0;
+	} else
+		return;
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_comm_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_COMM;
+	ev->event_data.comm.process_pid  = task->pid;
+	ev->event_data.comm.process_tgid = task->tgid;
+	get_task_comm(ev->event_data.comm.comm, task);
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_coredump_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	struct task_struct *parent;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_COREDUMP;
+	ev->event_data.coredump.process_pid = task->pid;
+	ev->event_data.coredump.process_tgid = task->tgid;
+
+	rcu_read_lock();
+	if (pid_alive(task)) {
+		parent = rcu_dereference(task->real_parent);
+		ev->event_data.coredump.parent_pid = parent->pid;
+		ev->event_data.coredump.parent_tgid = parent->tgid;
+	}
+	rcu_read_unlock();
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+void proc_exit_connector(struct task_struct *task)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	struct task_struct *parent;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	ev->timestamp_ns = ktime_get_ns();
+	ev->what = PROC_EVENT_EXIT;
+	ev->event_data.exit.process_pid = task->pid;
+	ev->event_data.exit.process_tgid = task->tgid;
+	ev->event_data.exit.exit_code = task->exit_code;
+	ev->event_data.exit.exit_signal = task->exit_signal;
+
+	rcu_read_lock();
+	if (pid_alive(task)) {
+		parent = rcu_dereference(task->real_parent);
+		ev->event_data.exit.parent_pid = parent->pid;
+		ev->event_data.exit.parent_tgid = parent->tgid;
+	}
+	rcu_read_unlock();
+
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = 0; /* not used */
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+/*
+ * Send an acknowledgement message to userspace
+ *
+ * Use 0 for success, EFOO otherwise.
+ * Note: this is the negative of conventional kernel error
+ * values because it's not being returned via syscall return
+ * mechanisms.
+ */
+static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
+{
+	struct cn_msg *msg;
+	struct proc_event *ev;
+	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+
+	if (atomic_read(&proc_event_num_listeners) < 1)
+		return;
+
+	msg = buffer_to_cn_msg(buffer);
+	ev = (struct proc_event *)msg->data;
+	memset(&ev->event_data, 0, sizeof(ev->event_data));
+	msg->seq = rcvd_seq;
+	ev->timestamp_ns = ktime_get_ns();
+	ev->cpu = -1;
+	ev->what = PROC_EVENT_NONE;
+	ev->event_data.ack.err = err;
+	memcpy(&msg->id, &cn_proc_event_id, sizeof(msg->id));
+	msg->ack = rcvd_ack + 1;
+	msg->len = sizeof(*ev);
+	msg->flags = 0; /* not used */
+	send_msg(msg);
+}
+
+/**
+ * cn_proc_mcast_ctl
+ * @msg: message sent from userspace via the connector
+ * @nsp: NETLINK_CB of the client's socket buffer
+ */
+static void cn_proc_mcast_ctl(struct cn_msg *msg,
+			      struct netlink_skb_parms *nsp)
+{
+	enum proc_cn_mcast_op mc_op = 0, prev_mc_op = 0;
+	struct proc_input *pinput = NULL;
+	enum proc_cn_event ev_type = 0;
+	int err = 0, initial = 0;
+	struct sock *sk = NULL;
+
+	/* 
+	 * Events are reported with respect to the initial pid
+	 * and user namespaces so ignore requestors from
+	 * other namespaces.
+	 */
+	if ((current_user_ns() != &init_user_ns) ||
+	    !task_is_in_init_pid_ns(current))
+		return;
+
+	if (msg->len == sizeof(*pinput)) {
+		pinput = (struct proc_input *)msg->data;
+		mc_op = pinput->mcast_op;
+		ev_type = pinput->event_type;
+	} else if (msg->len == sizeof(mc_op)) {
+		mc_op = *((enum proc_cn_mcast_op *)msg->data);
+		ev_type = PROC_EVENT_ALL;
+	} else {
+		return;
+	}
+
+	ev_type = valid_event((enum proc_cn_event)ev_type);
+
+	if (ev_type == PROC_EVENT_NONE)
+		ev_type = PROC_EVENT_ALL;
+
+	if (nsp->sk) {
+		sk = nsp->sk;
+		if (sk->sk_user_data == NULL) {
+			sk->sk_user_data = kzalloc_obj(struct proc_input);
+			if (sk->sk_user_data == NULL) {
+				err = ENOMEM;
+				goto out;
+			}
+			initial = 1;
+		} else {
+			prev_mc_op =
+			((struct proc_input *)(sk->sk_user_data))->mcast_op;
+		}
+		((struct proc_input *)(sk->sk_user_data))->event_type =
+			ev_type;
+		((struct proc_input *)(sk->sk_user_data))->mcast_op = mc_op;
+	}
+
+	switch (mc_op) {
+	case PROC_CN_MCAST_LISTEN:
+		if (initial || (prev_mc_op != PROC_CN_MCAST_LISTEN))
+			atomic_inc(&proc_event_num_listeners);
+		break;
+	case PROC_CN_MCAST_IGNORE:
+		if (!initial && (prev_mc_op != PROC_CN_MCAST_IGNORE))
+			atomic_dec(&proc_event_num_listeners);
+		((struct proc_input *)(sk->sk_user_data))->event_type =
+			PROC_EVENT_NONE;
+		break;
+	default:
+		err = EINVAL;
+		break;
+	}
+
+out:
+	cn_proc_ack(err, msg->seq, msg->ack);
+}
+
+/*
+ * cn_proc_init - initialization entry point
+ *
+ * Adds the connector callback to the connector driver.
+ */
+static int __init cn_proc_init(void)
+{
+	int err = cn_add_callback(&cn_proc_event_id,
+				  "cn_proc",
+				  &cn_proc_mcast_ctl);
+	if (err) {
+		pr_warn("cn_proc failed to register\n");
+		return err;
+	}
+	return 0;
+}
+device_initcall(cn_proc_init);
diff --git a/drivers/connector/cn_queue.c b/drivers/connector/cn_queue.c
new file mode 100644
index 000000000..2573b3000
--- /dev/null
+++ b/drivers/connector/cn_queue.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	cn_queue.c
+ *
+ * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/workqueue.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/skbuff.h>
+#include <linux/suspend.h>
+#include <linux/connector.h>
+#include <linux/delay.h>
+
+static struct cn_callback_entry *
+cn_queue_alloc_callback_entry(struct cn_queue_dev *dev, const char *name,
+			      const struct cb_id *id,
+			      void (*callback)(struct cn_msg *,
+					       struct netlink_skb_parms *))
+{
+	struct cn_callback_entry *cbq;
+
+	cbq = kzalloc_obj(*cbq);
+	if (!cbq) {
+		pr_err("Failed to create new callback queue.\n");
+		return NULL;
+	}
+
+	refcount_set(&cbq->refcnt, 1);
+
+	atomic_inc(&dev->refcnt);
+	cbq->pdev = dev;
+
+	snprintf(cbq->id.name, sizeof(cbq->id.name), "%s", name);
+	memcpy(&cbq->id.id, id, sizeof(struct cb_id));
+	cbq->callback = callback;
+	return cbq;
+}
+
+void cn_queue_release_callback(struct cn_callback_entry *cbq)
+{
+	if (!refcount_dec_and_test(&cbq->refcnt))
+		return;
+
+	atomic_dec(&cbq->pdev->refcnt);
+	kfree(cbq);
+}
+
+int cn_cb_equal(const struct cb_id *i1, const struct cb_id *i2)
+{
+	return ((i1->idx == i2->idx) && (i1->val == i2->val));
+}
+
+int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,
+			  const struct cb_id *id,
+			  void (*callback)(struct cn_msg *,
+					   struct netlink_skb_parms *))
+{
+	struct cn_callback_entry *cbq, *__cbq;
+	int found = 0;
+
+	cbq = cn_queue_alloc_callback_entry(dev, name, id, callback);
+	if (!cbq)
+		return -ENOMEM;
+
+	spin_lock_bh(&dev->queue_lock);
+	list_for_each_entry(__cbq, &dev->queue_list, callback_entry) {
+		if (cn_cb_equal(&__cbq->id.id, id)) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found)
+		list_add_tail(&cbq->callback_entry, &dev->queue_list);
+	spin_unlock_bh(&dev->queue_lock);
+
+	if (found) {
+		cn_queue_release_callback(cbq);
+		return -EINVAL;
+	}
+
+	cbq->seq = 0;
+	cbq->group = cbq->id.id.idx;
+
+	return 0;
+}
+
+void cn_queue_del_callback(struct cn_queue_dev *dev, const struct cb_id *id)
+{
+	struct cn_callback_entry *cbq, *n;
+	int found = 0;
+
+	spin_lock_bh(&dev->queue_lock);
+	list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry) {
+		if (cn_cb_equal(&cbq->id.id, id)) {
+			list_del(&cbq->callback_entry);
+			found = 1;
+			break;
+		}
+	}
+	spin_unlock_bh(&dev->queue_lock);
+
+	if (found)
+		cn_queue_release_callback(cbq);
+}
+
+struct cn_queue_dev *cn_queue_alloc_dev(const char *name, struct sock *nls)
+{
+	struct cn_queue_dev *dev;
+
+	dev = kzalloc_obj(*dev);
+	if (!dev)
+		return NULL;
+
+	snprintf(dev->name, sizeof(dev->name), "%s", name);
+	atomic_set(&dev->refcnt, 0);
+	INIT_LIST_HEAD(&dev->queue_list);
+	spin_lock_init(&dev->queue_lock);
+
+	dev->nls = nls;
+
+	return dev;
+}
+
+void cn_queue_free_dev(struct cn_queue_dev *dev)
+{
+	struct cn_callback_entry *cbq, *n;
+
+	spin_lock_bh(&dev->queue_lock);
+	list_for_each_entry_safe(cbq, n, &dev->queue_list, callback_entry)
+		list_del(&cbq->callback_entry);
+	spin_unlock_bh(&dev->queue_lock);
+
+	while (atomic_read(&dev->refcnt)) {
+		pr_info("Waiting for %s to become free: refcnt=%d.\n",
+		       dev->name, atomic_read(&dev->refcnt));
+		msleep(1000);
+	}
+
+	kfree(dev);
+	dev = NULL;
+}
diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
new file mode 100644
index 000000000..4028e8eeb
--- /dev/null
+++ b/drivers/connector/connector.c
@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	connector.c
+ *
+ * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * All rights reserved.
+ */
+
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <net/netlink.h>
+#include <linux/moduleparam.h>
+#include <linux/connector.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+
+#include <net/sock.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
+MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
+MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
+
+static struct cn_dev cdev;
+
+static int cn_already_initialized;
+
+/*
+ * Sends mult (multiple) cn_msg at a time.
+ *
+ * msg->seq and msg->ack are used to determine message genealogy.
+ * When someone sends message it puts there locally unique sequence
+ * and random acknowledge numbers.  Sequence number may be copied into
+ * nlmsghdr->nlmsg_seq too.
+ *
+ * Sequence number is incremented with each message to be sent.
+ *
+ * If we expect a reply to our message then the sequence number in
+ * received message MUST be the same as in original message, and
+ * acknowledge number MUST be the same + 1.
+ *
+ * If we receive a message and its sequence number is not equal to the
+ * one we are expecting then it is a new message.
+ *
+ * If we receive a message and its sequence number is the same as one
+ * we are expecting but it's acknowledgement number is not equal to
+ * the acknowledgement number in the original message + 1, then it is
+ * a new message.
+ *
+ * If msg->len != len, then additional cn_msg messages are expected following
+ * the first msg.
+ *
+ * The message is sent to, the portid if given, the group if given, both if
+ * both, or if both are zero then the group is looked up and sent there.
+ */
+int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
+			 gfp_t gfp_mask, netlink_filter_fn filter,
+			 void *filter_data)
+{
+	struct cn_callback_entry *__cbq;
+	unsigned int size;
+	struct sk_buff *skb;
+	struct nlmsghdr *nlh;
+	struct cn_msg *data;
+	struct cn_dev *dev = &cdev;
+	u32 group = 0;
+	int found = 0;
+
+	if (portid || __group) {
+		group = __group;
+	} else {
+		spin_lock_bh(&dev->cbdev->queue_lock);
+		list_for_each_entry(__cbq, &dev->cbdev->queue_list,
+				    callback_entry) {
+			if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
+				found = 1;
+				group = __cbq->group;
+				break;
+			}
+		}
+		spin_unlock_bh(&dev->cbdev->queue_lock);
+
+		if (!found)
+			return -ENODEV;
+	}
+
+	if (!portid && !netlink_has_listeners(dev->nls, group))
+		return -ESRCH;
+
+	size = sizeof(*msg) + len;
+
+	skb = nlmsg_new(size, gfp_mask);
+	if (!skb)
+		return -ENOMEM;
+
+	nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0);
+	if (!nlh) {
+		kfree_skb(skb);
+		return -EMSGSIZE;
+	}
+
+	data = nlmsg_data(nlh);
+
+	memcpy(data, msg, size);
+
+	NETLINK_CB(skb).dst_group = group;
+
+	if (group)
+		return netlink_broadcast_filtered(dev->nls, skb, portid, group,
+						  gfp_mask, filter,
+						  (void *)filter_data);
+	return netlink_unicast(dev->nls, skb, portid,
+			!gfpflags_allow_blocking(gfp_mask));
+}
+EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
+
+/* same as cn_netlink_send_mult except msg->len is used for len */
+int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
+	gfp_t gfp_mask)
+{
+	return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask,
+				    NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(cn_netlink_send);
+
+/*
+ * Callback helper - queues work and setup destructor for given data.
+ */
+static int cn_call_callback(struct sk_buff *skb)
+{
+	struct nlmsghdr *nlh;
+	struct cn_callback_entry *i, *cbq = NULL;
+	struct cn_dev *dev = &cdev;
+	struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
+	struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
+	int err = -ENODEV;
+
+	/* verify msg->len is within skb */
+	nlh = nlmsg_hdr(skb);
+	if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len)
+		return -EINVAL;
+
+	spin_lock_bh(&dev->cbdev->queue_lock);
+	list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
+		if (cn_cb_equal(&i->id.id, &msg->id)) {
+			refcount_inc(&i->refcnt);
+			cbq = i;
+			break;
+		}
+	}
+	spin_unlock_bh(&dev->cbdev->queue_lock);
+
+	if (cbq != NULL) {
+		cbq->callback(msg, nsp);
+		kfree_skb(skb);
+		cn_queue_release_callback(cbq);
+		err = 0;
+	}
+
+	return err;
+}
+
+/*
+ * Allow non-root access for NETLINK_CONNECTOR family having CN_IDX_PROC
+ * multicast group.
+ */
+static int cn_bind(struct net *net, int group)
+{
+	unsigned long groups = (unsigned long) group;
+
+	if (ns_capable(net->user_ns, CAP_NET_ADMIN))
+		return 0;
+
+	if (test_bit(CN_IDX_PROC - 1, &groups))
+		return 0;
+
+	return -EPERM;
+}
+
+static void cn_release(struct sock *sk, unsigned long *groups)
+{
+	if (groups && test_bit(CN_IDX_PROC - 1, groups)) {
+		kfree(sk->sk_user_data);
+		sk->sk_user_data = NULL;
+	}
+}
+
+/*
+ * Main netlink receiving function.
+ *
+ * It checks skb, netlink header and msg sizes, and calls callback helper.
+ */
+static void cn_rx_skb(struct sk_buff *skb)
+{
+	struct nlmsghdr *nlh;
+	int len, err;
+
+	if (skb->len >= NLMSG_HDRLEN) {
+		nlh = nlmsg_hdr(skb);
+		len = nlmsg_len(nlh);
+
+		if (len < (int)sizeof(struct cn_msg) ||
+		    skb->len < nlh->nlmsg_len ||
+		    len > CONNECTOR_MAX_MSG_SIZE)
+			return;
+
+		err = cn_call_callback(skb_get(skb));
+		if (err < 0)
+			kfree_skb(skb);
+	}
+}
+
+/*
+ * Callback add routing - adds callback with given ID and name.
+ * If there is registered callback with the same ID it will not be added.
+ *
+ * May sleep.
+ */
+int cn_add_callback(const struct cb_id *id, const char *name,
+		    void (*callback)(struct cn_msg *,
+				     struct netlink_skb_parms *))
+{
+	struct cn_dev *dev = &cdev;
+
+	if (!cn_already_initialized)
+		return -EAGAIN;
+
+	return cn_queue_add_callback(dev->cbdev, name, id, callback);
+}
+EXPORT_SYMBOL_GPL(cn_add_callback);
+
+/*
+ * Callback remove routing - removes callback
+ * with given ID.
+ * If there is no registered callback with given
+ * ID nothing happens.
+ *
+ * May sleep while waiting for reference counter to become zero.
+ */
+void cn_del_callback(const struct cb_id *id)
+{
+	struct cn_dev *dev = &cdev;
+
+	cn_queue_del_callback(dev->cbdev, id);
+}
+EXPORT_SYMBOL_GPL(cn_del_callback);
+
+static int __maybe_unused cn_proc_show(struct seq_file *m, void *v)
+{
+	struct cn_queue_dev *dev = cdev.cbdev;
+	struct cn_callback_entry *cbq;
+
+	seq_printf(m, "Name            ID\n");
+
+	spin_lock_bh(&dev->queue_lock);
+
+	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
+		seq_printf(m, "%-15s %u:%u\n",
+			   cbq->id.name,
+			   cbq->id.id.idx,
+			   cbq->id.id.val);
+	}
+
+	spin_unlock_bh(&dev->queue_lock);
+
+	return 0;
+}
+
+static int cn_init(void)
+{
+	struct cn_dev *dev = &cdev;
+	struct netlink_kernel_cfg cfg = {
+		.groups	= CN_NETLINK_USERS + 0xf,
+		.input	= cn_rx_skb,
+		.flags  = NL_CFG_F_NONROOT_RECV,
+		.bind   = cn_bind,
+		.release = cn_release,
+	};
+
+	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
+	if (!dev->nls)
+		return -EIO;
+
+	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
+	if (!dev->cbdev) {
+		netlink_kernel_release(dev->nls);
+		return -EINVAL;
+	}
+
+	cn_already_initialized = 1;
+
+	proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show);
+
+	return 0;
+}
+
+static void cn_fini(void)
+{
+	struct cn_dev *dev = &cdev;
+
+	cn_already_initialized = 0;
+
+	remove_proc_entry("connector", init_net.proc_net);
+
+	cn_queue_free_dev(dev->cbdev);
+	netlink_kernel_release(dev->nls);
+}
+
+subsys_initcall(cn_init);
+module_exit(cn_fini);