1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * The USB Monitor, inspired by Dave Harding's USBMon.
4 *
5 * mon_main.c: Main file, module initiation and exit, registrations, etc.
6 *
7 * Copyright (C) 2005 Pete Zaitcev (zaitcev@redhat.com)
8 */
9
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/usb.h>
13 #include <linux/usb/hcd.h>
14 #include <linux/slab.h>
15 #include <linux/notifier.h>
16 #include <linux/mutex.h>
17
18 #include "usb_mon.h"
19
20
21 static void mon_stop(struct mon_bus *mbus);
22 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus);
23 static void mon_bus_drop(struct kref *r);
24 static void mon_bus_init(struct usb_bus *ubus);
25
26 DEFINE_MUTEX(mon_lock);
27
28 struct mon_bus mon_bus0; /* Pseudo bus meaning "all buses" */
29 static LIST_HEAD(mon_buses); /* All buses we know: struct mon_bus */
30
31 /*
32 * Link a reader into the bus.
33 *
34 * This must be called with mon_lock taken because of mbus->ref.
35 */
mon_reader_add(struct mon_bus * mbus,struct mon_reader * r)36 void mon_reader_add(struct mon_bus *mbus, struct mon_reader *r)
37 {
38 unsigned long flags;
39 struct list_head *p;
40
41 spin_lock_irqsave(&mbus->lock, flags);
42 if (mbus->nreaders == 0) {
43 if (mbus == &mon_bus0) {
44 list_for_each (p, &mon_buses) {
45 struct mon_bus *m1;
46 m1 = list_entry(p, struct mon_bus, bus_link);
47 m1->u_bus->monitored = 1;
48 }
49 } else {
50 mbus->u_bus->monitored = 1;
51 }
52 }
53 mbus->nreaders++;
54 list_add_tail(&r->r_link, &mbus->r_list);
55 spin_unlock_irqrestore(&mbus->lock, flags);
56
57 kref_get(&mbus->ref);
58 }
59
60 /*
61 * Unlink reader from the bus.
62 *
63 * This is called with mon_lock taken, so we can decrement mbus->ref.
64 */
mon_reader_del(struct mon_bus * mbus,struct mon_reader * r)65 void mon_reader_del(struct mon_bus *mbus, struct mon_reader *r)
66 {
67 unsigned long flags;
68
69 spin_lock_irqsave(&mbus->lock, flags);
70 list_del(&r->r_link);
71 --mbus->nreaders;
72 if (mbus->nreaders == 0)
73 mon_stop(mbus);
74 spin_unlock_irqrestore(&mbus->lock, flags);
75
76 kref_put(&mbus->ref, mon_bus_drop);
77 }
78
79 /*
80 */
mon_bus_submit(struct mon_bus * mbus,struct urb * urb)81 static void mon_bus_submit(struct mon_bus *mbus, struct urb *urb)
82 {
83 unsigned long flags;
84 struct list_head *pos;
85 struct mon_reader *r;
86
87 spin_lock_irqsave(&mbus->lock, flags);
88 mbus->cnt_events++;
89 list_for_each (pos, &mbus->r_list) {
90 r = list_entry(pos, struct mon_reader, r_link);
91 r->rnf_submit(r->r_data, urb);
92 }
93 spin_unlock_irqrestore(&mbus->lock, flags);
94 }
95
mon_submit(struct usb_bus * ubus,struct urb * urb)96 static void mon_submit(struct usb_bus *ubus, struct urb *urb)
97 {
98 struct mon_bus *mbus;
99
100 mbus = ubus->mon_bus;
101 if (mbus != NULL)
102 mon_bus_submit(mbus, urb);
103 mon_bus_submit(&mon_bus0, urb);
104 }
105
106 /*
107 */
mon_bus_submit_error(struct mon_bus * mbus,struct urb * urb,int error)108 static void mon_bus_submit_error(struct mon_bus *mbus, struct urb *urb, int error)
109 {
110 unsigned long flags;
111 struct list_head *pos;
112 struct mon_reader *r;
113
114 spin_lock_irqsave(&mbus->lock, flags);
115 mbus->cnt_events++;
116 list_for_each (pos, &mbus->r_list) {
117 r = list_entry(pos, struct mon_reader, r_link);
118 r->rnf_error(r->r_data, urb, error);
119 }
120 spin_unlock_irqrestore(&mbus->lock, flags);
121 }
122
mon_submit_error(struct usb_bus * ubus,struct urb * urb,int error)123 static void mon_submit_error(struct usb_bus *ubus, struct urb *urb, int error)
124 {
125 struct mon_bus *mbus;
126
127 mbus = ubus->mon_bus;
128 if (mbus != NULL)
129 mon_bus_submit_error(mbus, urb, error);
130 mon_bus_submit_error(&mon_bus0, urb, error);
131 }
132
133 /*
134 */
mon_bus_complete(struct mon_bus * mbus,struct urb * urb,int status)135 static void mon_bus_complete(struct mon_bus *mbus, struct urb *urb, int status)
136 {
137 unsigned long flags;
138 struct list_head *pos;
139 struct mon_reader *r;
140
141 spin_lock_irqsave(&mbus->lock, flags);
142 mbus->cnt_events++;
143 list_for_each (pos, &mbus->r_list) {
144 r = list_entry(pos, struct mon_reader, r_link);
145 r->rnf_complete(r->r_data, urb, status);
146 }
147 spin_unlock_irqrestore(&mbus->lock, flags);
148 }
149
mon_complete(struct usb_bus * ubus,struct urb * urb,int status)150 static void mon_complete(struct usb_bus *ubus, struct urb *urb, int status)
151 {
152 struct mon_bus *mbus;
153
154 mbus = ubus->mon_bus;
155 if (mbus != NULL)
156 mon_bus_complete(mbus, urb, status);
157 mon_bus_complete(&mon_bus0, urb, status);
158 }
159
160 /* int (*unlink_urb) (struct urb *urb, int status); */
161
162 /*
163 * Stop monitoring.
164 */
mon_stop(struct mon_bus * mbus)165 static void mon_stop(struct mon_bus *mbus)
166 {
167 struct usb_bus *ubus;
168 struct list_head *p;
169
170 if (mbus == &mon_bus0) {
171 list_for_each (p, &mon_buses) {
172 mbus = list_entry(p, struct mon_bus, bus_link);
173 /*
174 * We do not change nreaders here, so rely on mon_lock.
175 */
176 if (mbus->nreaders == 0 && (ubus = mbus->u_bus) != NULL)
177 ubus->monitored = 0;
178 }
179 } else {
180 /*
181 * A stop can be called for a dissolved mon_bus in case of
182 * a reader staying across an rmmod foo_hcd, so test ->u_bus.
183 */
184 if (mon_bus0.nreaders == 0 && (ubus = mbus->u_bus) != NULL) {
185 ubus->monitored = 0;
186 mb();
187 }
188 }
189 }
190
191 /*
192 * Add a USB bus (usually by a modprobe foo-hcd)
193 *
194 * This does not return an error code because the core cannot care less
195 * if monitoring is not established.
196 */
mon_bus_add(struct usb_bus * ubus)197 static void mon_bus_add(struct usb_bus *ubus)
198 {
199 mon_bus_init(ubus);
200 mutex_lock(&mon_lock);
201 if (mon_bus0.nreaders != 0)
202 ubus->monitored = 1;
203 mutex_unlock(&mon_lock);
204 }
205
206 /*
207 * Remove a USB bus (either from rmmod foo-hcd or from a hot-remove event).
208 */
mon_bus_remove(struct usb_bus * ubus)209 static void mon_bus_remove(struct usb_bus *ubus)
210 {
211 struct mon_bus *mbus = ubus->mon_bus;
212
213 mutex_lock(&mon_lock);
214 list_del(&mbus->bus_link);
215 if (mbus->text_inited)
216 mon_text_del(mbus);
217 if (mbus->bin_inited)
218 mon_bin_del(mbus);
219
220 mon_dissolve(mbus, ubus);
221 kref_put(&mbus->ref, mon_bus_drop);
222 mutex_unlock(&mon_lock);
223 }
224
mon_notify(struct notifier_block * self,unsigned long action,void * dev)225 static int mon_notify(struct notifier_block *self, unsigned long action,
226 void *dev)
227 {
228 switch (action) {
229 case USB_BUS_ADD:
230 mon_bus_add(dev);
231 break;
232 case USB_BUS_REMOVE:
233 mon_bus_remove(dev);
234 }
235 return NOTIFY_OK;
236 }
237
238 static struct notifier_block mon_nb = {
239 .notifier_call = mon_notify,
240 };
241
242 /*
243 * Ops
244 */
245 static const struct usb_mon_operations mon_ops_0 = {
246 .urb_submit = mon_submit,
247 .urb_submit_error = mon_submit_error,
248 .urb_complete = mon_complete,
249 };
250
251 /*
252 * Tear usb_bus and mon_bus apart.
253 */
mon_dissolve(struct mon_bus * mbus,struct usb_bus * ubus)254 static void mon_dissolve(struct mon_bus *mbus, struct usb_bus *ubus)
255 {
256
257 if (ubus->monitored) {
258 ubus->monitored = 0;
259 mb();
260 }
261
262 ubus->mon_bus = NULL;
263 mbus->u_bus = NULL;
264 mb();
265
266 /* We want synchronize_irq() here, but that needs an argument. */
267 }
268
269 /*
270 */
mon_bus_drop(struct kref * r)271 static void mon_bus_drop(struct kref *r)
272 {
273 struct mon_bus *mbus = container_of(r, struct mon_bus, ref);
274 kfree(mbus);
275 }
276
277 /*
278 * Initialize a bus for us:
279 * - allocate mon_bus
280 * - refcount USB bus struct
281 * - link
282 */
mon_bus_init(struct usb_bus * ubus)283 static void mon_bus_init(struct usb_bus *ubus)
284 {
285 struct mon_bus *mbus;
286
287 mbus = kzalloc(sizeof(struct mon_bus), GFP_KERNEL);
288 if (mbus == NULL)
289 goto err_alloc;
290 kref_init(&mbus->ref);
291 spin_lock_init(&mbus->lock);
292 INIT_LIST_HEAD(&mbus->r_list);
293
294 /*
295 * We don't need to take a reference to ubus, because we receive
296 * a notification if the bus is about to be removed.
297 */
298 mbus->u_bus = ubus;
299 ubus->mon_bus = mbus;
300
301 mbus->text_inited = mon_text_add(mbus, ubus);
302 mbus->bin_inited = mon_bin_add(mbus, ubus);
303
304 mutex_lock(&mon_lock);
305 list_add_tail(&mbus->bus_link, &mon_buses);
306 mutex_unlock(&mon_lock);
307 return;
308
309 err_alloc:
310 return;
311 }
312
mon_bus0_init(void)313 static void mon_bus0_init(void)
314 {
315 struct mon_bus *mbus = &mon_bus0;
316
317 kref_init(&mbus->ref);
318 spin_lock_init(&mbus->lock);
319 INIT_LIST_HEAD(&mbus->r_list);
320
321 mbus->text_inited = mon_text_add(mbus, NULL);
322 mbus->bin_inited = mon_bin_add(mbus, NULL);
323 }
324
325 /*
326 * Search a USB bus by number. Notice that USB bus numbers start from one,
327 * which we may later use to identify "all" with zero.
328 *
329 * This function must be called with mon_lock held.
330 *
331 * This is obviously inefficient and may be revised in the future.
332 */
mon_bus_lookup(unsigned int num)333 struct mon_bus *mon_bus_lookup(unsigned int num)
334 {
335 struct list_head *p;
336 struct mon_bus *mbus;
337
338 if (num == 0) {
339 return &mon_bus0;
340 }
341 list_for_each (p, &mon_buses) {
342 mbus = list_entry(p, struct mon_bus, bus_link);
343 if (mbus->u_bus->busnum == num) {
344 return mbus;
345 }
346 }
347 return NULL;
348 }
349
mon_init(void)350 static int __init mon_init(void)
351 {
352 struct usb_bus *ubus;
353 int rc, id;
354
355 if ((rc = mon_text_init()) != 0)
356 goto err_text;
357 if ((rc = mon_bin_init()) != 0)
358 goto err_bin;
359
360 mon_bus0_init();
361
362 if (usb_mon_register(&mon_ops_0) != 0) {
363 printk(KERN_NOTICE TAG ": unable to register with the core\n");
364 rc = -ENODEV;
365 goto err_reg;
366 }
367 // MOD_INC_USE_COUNT(which_module?);
368
369 mutex_lock(&usb_bus_idr_lock);
370 idr_for_each_entry(&usb_bus_idr, ubus, id)
371 mon_bus_init(ubus);
372 usb_register_notify(&mon_nb);
373 mutex_unlock(&usb_bus_idr_lock);
374 return 0;
375
376 err_reg:
377 mon_bin_exit();
378 err_bin:
379 mon_text_exit();
380 err_text:
381 return rc;
382 }
383
mon_exit(void)384 static void __exit mon_exit(void)
385 {
386 struct mon_bus *mbus;
387 struct list_head *p;
388
389 usb_unregister_notify(&mon_nb);
390 usb_mon_deregister();
391
392 mutex_lock(&mon_lock);
393
394 while (!list_empty(&mon_buses)) {
395 p = mon_buses.next;
396 mbus = list_entry(p, struct mon_bus, bus_link);
397 list_del(p);
398
399 if (mbus->text_inited)
400 mon_text_del(mbus);
401 if (mbus->bin_inited)
402 mon_bin_del(mbus);
403
404 /*
405 * This never happens, because the open/close paths in
406 * file level maintain module use counters and so rmmod fails
407 * before reaching here. However, better be safe...
408 */
409 if (mbus->nreaders) {
410 printk(KERN_ERR TAG
411 ": Outstanding opens (%d) on usb%d, leaking...\n",
412 mbus->nreaders, mbus->u_bus->busnum);
413 kref_get(&mbus->ref); /* Force leak */
414 }
415
416 mon_dissolve(mbus, mbus->u_bus);
417 kref_put(&mbus->ref, mon_bus_drop);
418 }
419
420 mbus = &mon_bus0;
421 if (mbus->text_inited)
422 mon_text_del(mbus);
423 if (mbus->bin_inited)
424 mon_bin_del(mbus);
425
426 mutex_unlock(&mon_lock);
427
428 mon_text_exit();
429 mon_bin_exit();
430 }
431
432 module_init(mon_init);
433 module_exit(mon_exit);
434
435 MODULE_LICENSE("GPL");
436