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