// SPDX-License-Identifier: GPL-2.0
/*
* The USB Monitor, inspired by Dave Harding's USBMon.
*
* mon_main.c: Main file, module initiation and exit, registrations, etc.
*
* Copyright (C) 2005 Pete Zaitcev ([email protected])
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/mutex.h>
#include "usb_mon.h"
static void mon_stop(struct mon_bus *mbus);
static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
static void mon_bus_drop(struct kref *r);
static void mon_bus_init(struct usb_bus *ubus);
DEFINE_MUTEX(mon_lock);
struct mon_bus mon_bus0; /* Pseudo bus meaning "all buses" */
static LIST_HEAD(mon_buses); /* All buses we know: struct mon_bus */
/*
* Link a reader into the bus.
*
* This must be called with mon_lock taken because of mbus->ref.
*/
void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
{
unsigned long flags;
struct list_head *p;
spin_lock_irqsave(&mbus->lock, flags);
if (mbus->nreaders == 0) {
if (mbus == &mon_bus0) {
list_for_each (p, &mon_buses) {
struct mon_bus *m1;
m1 = list_entry(p, struct mon_bus, bus_link);
m1->u_bus->monitored = 1;
}
} else {
mbus->u_bus->monitored = 1;
}
}
mbus->nreaders++;
list_add_tail(&r->r_link, &mbus->r_list);
spin_unlock_irqrestore(&mbus->lock, flags);
kref_get(&mbus->ref);
}
/*
* Unlink reader from the bus.
*
* This is called with mon_lock taken, so we can decrement mbus->ref.
*/
void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
{
unsigned long flags;
spin_lock_irqsave(&mbus->lock, flags);
list_del(&r->r_link);
--mbus->nreaders;
if (mbus->nreaders == 0)
mon_stop(mbus);
spin_unlock_irqrestore(&mbus->lock, flags);
kref_put(&mbus->ref, mon_bus_drop);
}
/*
*/
static void mon_bus_submit(struct mon_bus *mbus, struct urb *urb)
{
unsigned long flags;
struct mon_reader *r;
spin_lock_irqsave(&mbus->lock, flags);
mbus->cnt_events++;
list_for_each_entry(r, &mbus->r_list, r_link)
r->rnf_submit(r->r_data, urb);
spin_unlock_irqrestore(&mbus->lock, flags);
}
static void mon_submit(struct usb_bus *ubus, struct urb *urb)
{
struct mon_bus *mbus;
mbus = ubus->mon_bus;
if (mbus != NULL)
mon_bus_submit(mbus, urb);
mon_bus_submit(&mon_bus0, urb);
}
/*
*/
static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
{
unsigned long flags;
struct mon_reader *r;
spin_lock_irqsave(&mbus->lock, flags);
mbus->cnt_events++;
list_for_each_entry(r, &mbus->r_list, r_link)
r->rnf_error(r->r_data, urb, error);
spin_unlock_irqrestore(&mbus->lock, flags);
}
static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
{
struct mon_bus *mbus;
mbus = ubus->mon_bus;
if (mbus != NULL)
mon_bus_submit_error(mbus, urb, error);
mon_bus_submit_error(&mon_bus0, urb, error);
}
/*
*/
static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb, int status)
{
unsigned long flags;
struct mon_reader *r;
spin_lock_irqsave(&mbus->lock, flags);
mbus->cnt_events++;
list_for_each_entry(r, &mbus->r_list, r_link)
r->rnf_complete(r->r_data, urb, status);
spin_unlock_irqrestore(&mbus->lock, flags);
}
static void mon_complete(struct usb_bus *ubus, struct urb *urb, int status)
{
struct mon_bus *mbus;
mbus = ubus->mon_bus;
if (mbus != NULL)
mon_bus_complete(mbus, urb, status);
mon_bus_complete(&mon_bus0, urb, status);
}
/* int (*unlink_urb) (struct urb *urb, int status); */
/*
* Stop monitoring.
*/
static void mon_stop(struct mon_bus *mbus)
{
struct usb_bus *ubus;
if (mbus == &mon_bus0) {
list_for_each_entry(mbus, &mon_buses, bus_link) {
/*
* We do not change nreaders here, so rely on mon_lock.
*/
if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
ubus->monitored = 0;
}
} else {
/*
* A stop can be called for a dissolved mon_bus in case of
* a reader staying across an rmmod foo_hcd, so test ->u_bus.
*/
if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
ubus->monitored = 0;
mb();
}
}
}
/*
* Add a USB bus (usually by a modprobe foo-hcd)
*
* This does not return an error code because the core cannot care less
* if monitoring is not established.
*/
static void mon_bus_add(struct usb_bus *ubus)
{
mon_bus_init(ubus);
mutex_lock(&mon_lock);
if (mon_bus0.nreaders != 0)
ubus->monitored = 1;
mutex_unlock(&mon_lock);
}
/*
* Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
*/
static void mon_bus_remove(struct usb_bus *ubus)
{
struct mon_bus *mbus = ubus->mon_bus;
mutex_lock(&mon_lock);
list_del(&mbus->bus_link);
if (mbus->text_inited)
mon_text_del(mbus);
if (mbus->bin_inited)
mon_bin_del(mbus);
mon_dissolve(mbus, ubus);
kref_put(&mbus->ref, mon_bus_drop);
mutex_unlock(&mon_lock);
}
static int mon_notify(struct notifier_block *self, unsigned long action,
void *dev)
{
switch (action) {
case USB_BUS_ADD:
mon_bus_add(dev);
break;
case USB_BUS_REMOVE:
mon_bus_remove(dev);
}
return NOTIFY_OK;
}
static struct notifier_block mon_nb = {
.notifier_call = mon_notify,
};
/*
* Ops
*/
static const struct usb_mon_operations mon_ops_0 = {
.urb_submit = mon_submit,
.urb_submit_error = mon_submit_error,
.urb_complete = mon_complete,
};
/*
* Tear usb_bus and mon_bus apart.
*/
static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
{
if (ubus->monitored) {
ubus->monitored = 0;
mb();
}
ubus->mon_bus = NULL;
mbus->u_bus = NULL;
mb();
/* We want synchronize_irq() here, but that needs an argument. */
}
/*
*/
static void mon_bus_drop(struct kref *r)
{
struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
kfree(mbus);
}
/*
* Initialize a bus for us:
* - allocate mon_bus
* - refcount USB bus struct
* - link
*/
static void mon_bus_init(struct usb_bus *ubus)
{
struct mon_bus *mbus;
mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL);
if (mbus == NULL)
goto err_alloc;
kref_init(&mbus->ref);
spin_lock_init(&mbus->lock);
INIT_LIST_HEAD(&mbus->r_list);
/*
* We don't need to take a reference to ubus, because we receive
* a notification if the bus is about to be removed.
*/
mbus->u_bus = ubus;
ubus->mon_bus = mbus;
mbus->text_inited = mon_text_add(mbus, ubus);
mbus->bin_inited = mon_bin_add(mbus, ubus);
mutex_lock(&mon_lock);
list_add_tail(&mbus->bus_link, &mon_buses);
mutex_unlock(&mon_lock);
return;
err_alloc:
return;
}
static void mon_bus0_init(void)
{
struct mon_bus *mbus = &mon_bus0;
kref_init(&mbus->ref);
spin_lock_init(&mbus->lock);
INIT_LIST_HEAD(&mbus->r_list);
mbus->text_inited = mon_text_add(mbus, NULL);
mbus->bin_inited = mon_bin_add(mbus, NULL);
}
/*
* Search a USB bus by number. Notice that USB bus numbers start from one,
* which we may later use to identify "all" with zero.
*
* This function must be called with mon_lock held.
*
* This is obviously inefficient and may be revised in the future.
*/
struct mon_bus *mon_bus_lookup(unsigned int num)
{
struct mon_bus *mbus;
if (num == 0) {
return &mon_bus0;
}
list_for_each_entry(mbus, &mon_buses, bus_link) {
if (mbus->u_bus->busnum == num) {
return mbus;
}
}
return NULL;
}
static int __init mon_init(void)
{
struct usb_bus *ubus;
int rc, id;
if ((rc = mon_text_init()) != 0)
goto err_text;
if ((rc = mon_bin_init()) != 0)
goto err_bin;
mon_bus0_init();
if (usb_mon_register(&mon_ops_0) != 0) {
printk(KERN_NOTICE TAG ": unable to register with the core\n");
rc = -ENODEV;
goto err_reg;
}
// MOD_INC_USE_COUNT(which_module?);
mutex_lock(&usb_bus_idr_lock);
idr_for_each_entry(&usb_bus_idr, ubus, id)
mon_bus_init(ubus);
usb_register_notify(&mon_nb);
mutex_unlock(&usb_bus_idr_lock);
return 0;
err_reg:
mon_bin_exit();
err_bin:
mon_text_exit();
err_text:
return rc;
}
static void __exit mon_exit(void)
{
struct mon_bus *mbus;
struct list_head *p;
usb_unregister_notify(&mon_nb);
usb_mon_deregister();
mutex_lock(&mon_lock);
while (!list_empty(&mon_buses)) {
p = mon_buses.next;
mbus = list_entry(p, struct mon_bus, bus_link);
list_del(p);
if (mbus->text_inited)
mon_text_del(mbus);
if (mbus->bin_inited)
mon_bin_del(mbus);
/*
* This never happens, because the open/close paths in
* file level maintain module use counters and so rmmod fails
* before reaching here. However, better be safe...
*/
if (mbus->nreaders) {
printk(KERN_ERR TAG
": Outstanding opens (%d) on usb%d, leaking...\n",
mbus->nreaders, mbus->u_bus->busnum);
kref_get(&mbus->ref); /* Force leak */
}
mon_dissolve(mbus, mbus->u_bus);
kref_put(&mbus->ref, mon_bus_drop);
}
mbus = &mon_bus0;
if (mbus->text_inited)
mon_text_del(mbus);
if (mbus->bin_inited)
mon_bin_del(mbus);
mutex_unlock(&mon_lock);
mon_text_exit();
mon_bin_exit();
}
module_init(mon_init);
module_exit(mon_exit);
MODULE_DESCRIPTION("USB Monitor");
MODULE_LICENSE("GPL");
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