drivers/usb/mon/mon_text.c

   1 /*
   2  * The USB Monitor, inspired by Dave Harding's USBMon.
   3  *
   4  * This is a text format reader.
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/list.h>
   9 #include <linux/usb.h>
  10 #include <linux/time.h>
  11 #include <linux/mutex.h>
  12 #include <asm/uaccess.h>
  13
  14 #include "usb_mon.h"
  15
  16 /*
  17  * No, we do not want arbitrarily long data strings.
  18  * Use the binary interface if you want to capture bulk data!
  19  */
  20 #define DATA_MAX  32
  21
  22 /*
  23  * Defined by USB 2.0 clause 9.3, table 9.2.
  24  */
  25 #define SETUP_MAX  8
  26
  27 /*
  28  * This limit exists to prevent OOMs when the user process stops reading.
  29  * If usbmon were available to unprivileged processes, it might be open
  30  * to a local DoS. But we have to keep to root in order to prevent
  31  * password sniffing from HID devices.
  32  */
  33 #define EVENT_MAX  (2*PAGE_SIZE / sizeof(struct mon_event_text))
  34
  35 #define PRINTF_DFL  160
  36
  37 struct mon_event_text {
  38         struct list_head e_link;
  39         int type;               /* submit, complete, etc. */
  40         unsigned int pipe;      /* Pipe */
  41         unsigned long id;       /* From pointer, most of the time */
  42         unsigned int tstamp;
  43         int length;             /* Depends on type: xfer length or act length */
  44         int status;
  45         char setup_flag;
  46         char data_flag;
  47         unsigned char setup[SETUP_MAX];
  48         unsigned char data[DATA_MAX];
  49 };
  50
  51 #define SLAB_NAME_SZ  30
  52 struct mon_reader_text {
  53         kmem_cache_t *e_slab;
  54         int nevents;
  55         struct list_head e_list;
  56         struct mon_reader r;    /* In C, parent class can be placed anywhere */
  57
  58         wait_queue_head_t wait;
  59         int printf_size;
  60         char *printf_buf;
  61         struct mutex printf_lock;
  62
  63         char slab_name[SLAB_NAME_SZ];
  64 };
  65
  66 static void mon_text_ctor(void *, kmem_cache_t *, unsigned long);
  67
  68 /*
  69  * mon_text_submit
  70  * mon_text_complete
  71  *
  72  * May be called from an interrupt.
  73  *
  74  * This is called with the whole mon_bus locked, so no additional lock.
  75  */
  76
  77 static inline char mon_text_get_setup(struct mon_event_text *ep,
  78     struct urb *urb, char ev_type)
  79 {
  80
  81         if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
  82                 return '-';
  83
  84         if (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
  85                 return mon_dmapeek(ep->setup, urb->setup_dma, SETUP_MAX);
  86         if (urb->setup_packet == NULL)
  87                 return 'Z';     /* '0' would be not as pretty. */
  88
  89         memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
  90         return 0;
  91 }
  92
  93 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
  94     int len, char ev_type)
  95 {
  96         int pipe = urb->pipe;
  97
  98         if (len <= 0)
  99                 return 'L';
 100         if (len >= DATA_MAX)
 101                 len = DATA_MAX;
 102
 103         if (usb_pipein(pipe)) {
 104                 if (ev_type == 'S')
 105                         return '<';
 106         } else {
 107                 if (ev_type == 'C')
 108                         return '>';
 109         }
 110
 111         /*
 112          * The check to see if it's safe to poke at data has an enormous
 113          * number of corner cases, but it seems that the following is
 114          * more or less safe.
 115          *
 116          * We do not even try to look at transfer_buffer, because it can
 117          * contain non-NULL garbage in case the upper level promised to
 118          * set DMA for the HCD.
 119          */
 120         if (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)
 121                 return mon_dmapeek(ep->data, urb->transfer_dma, len);
 122
 123         if (urb->transfer_buffer == NULL)
 124                 return 'Z';     /* '0' would be not as pretty. */
 125
 126         memcpy(ep->data, urb->transfer_buffer, len);
 127         return 0;
 128 }
 129
 130 static inline unsigned int mon_get_timestamp(void)
 131 {
 132         struct timeval tval;
 133         unsigned int stamp;
 134
 135         do_gettimeofday(&tval);
 136         stamp = tval.tv_sec & 0xFFFF;   /* 2^32 = 4294967296. Limit to 4096s. */
 137         stamp = stamp * 1000000 + tval.tv_usec;
 138         return stamp;
 139 }
 140
 141 static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
 142     char ev_type)
 143 {
 144         struct mon_event_text *ep;
 145         unsigned int stamp;
 146
 147         stamp = mon_get_timestamp();
 148
 149         if (rp->nevents >= EVENT_MAX ||
 150             (ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
 151                 rp->r.m_bus->cnt_text_lost++;
 152                 return;
 153         }
 154
 155         ep->type = ev_type;
 156         ep->pipe = urb->pipe;
 157         ep->id = (unsigned long) urb;
 158         ep->tstamp = stamp;
 159         ep->length = (ev_type == 'S') ?
 160             urb->transfer_buffer_length : urb->actual_length;
 161         /* Collecting status makes debugging sense for submits, too */
 162         ep->status = urb->status;
 163
 164         ep->setup_flag = mon_text_get_setup(ep, urb, ev_type);
 165         ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type);
 166
 167         rp->nevents++;
 168         list_add_tail(&ep->e_link, &rp->e_list);
 169         wake_up(&rp->wait);
 170 }
 171
 172 static void mon_text_submit(void *data, struct urb *urb)
 173 {
 174         struct mon_reader_text *rp = data;
 175         mon_text_event(rp, urb, 'S');
 176 }
 177
 178 static void mon_text_complete(void *data, struct urb *urb)
 179 {
 180         struct mon_reader_text *rp = data;
 181         mon_text_event(rp, urb, 'C');
 182 }
 183
 184 static void mon_text_error(void *data, struct urb *urb, int error)
 185 {
 186         struct mon_reader_text *rp = data;
 187         struct mon_event_text *ep;
 188
 189         if (rp->nevents >= EVENT_MAX ||
 190             (ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
 191                 rp->r.m_bus->cnt_text_lost++;
 192                 return;
 193         }
 194
 195         ep->type = 'E';
 196         ep->pipe = urb->pipe;
 197         ep->id = (unsigned long) urb;
 198         ep->tstamp = 0;
 199         ep->length = 0;
 200         ep->status = error;
 201
 202         ep->setup_flag = '-';
 203         ep->data_flag = 'E';
 204
 205         rp->nevents++;
 206         list_add_tail(&ep->e_link, &rp->e_list);
 207         wake_up(&rp->wait);
 208 }
 209
 210 /*
 211  * Fetch next event from the circular buffer.
 212  */
 213 static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 214     struct mon_bus *mbus)
 215 {
 216         struct list_head *p;
 217         unsigned long flags;
 218
 219         spin_lock_irqsave(&mbus->lock, flags);
 220         if (list_empty(&rp->e_list)) {
 221                 spin_unlock_irqrestore(&mbus->lock, flags);
 222                 return NULL;
 223         }
 224         p = rp->e_list.next;
 225         list_del(p);
 226         --rp->nevents;
 227         spin_unlock_irqrestore(&mbus->lock, flags);
 228         return list_entry(p, struct mon_event_text, e_link);
 229 }
 230
 231 /*
 232  */
 233 static int mon_text_open(struct inode *inode, struct file *file)
 234 {
 235         struct mon_bus *mbus;
 236         struct usb_bus *ubus;
 237         struct mon_reader_text *rp;
 238         int rc;
 239
 240         mutex_lock(&mon_lock);
 241         mbus = inode->i_private;
 242         ubus = mbus->u_bus;
 243
 244         rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 245         if (rp == NULL) {
 246                 rc = -ENOMEM;
 247                 goto err_alloc;
 248         }
 249         INIT_LIST_HEAD(&rp->e_list);
 250         init_waitqueue_head(&rp->wait);
 251         mutex_init(&rp->printf_lock);
 252
 253         rp->printf_size = PRINTF_DFL;
 254         rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 255         if (rp->printf_buf == NULL) {
 256                 rc = -ENOMEM;
 257                 goto err_alloc_pr;
 258         }
 259
 260         rp->r.m_bus = mbus;
 261         rp->r.r_data = rp;
 262         rp->r.rnf_submit = mon_text_submit;
 263         rp->r.rnf_error = mon_text_error;
 264         rp->r.rnf_complete = mon_text_complete;
 265
 266         snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
 267             (long)rp);
 268         rp->e_slab = kmem_cache_create(rp->slab_name,
 269             sizeof(struct mon_event_text), sizeof(long), 0,
 270             mon_text_ctor, NULL);
 271         if (rp->e_slab == NULL) {
 272                 rc = -ENOMEM;
 273                 goto err_slab;
 274         }
 275
 276         mon_reader_add(mbus, &rp->r);
 277
 278         file->private_data = rp;
 279         mutex_unlock(&mon_lock);
 280         return 0;
 281
 282 // err_busy:
 283 //      kmem_cache_destroy(rp->e_slab);
 284 err_slab:
 285         kfree(rp->printf_buf);
 286 err_alloc_pr:
 287         kfree(rp);
 288 err_alloc:
 289         mutex_unlock(&mon_lock);
 290         return rc;
 291 }
 292
 293 /*
 294  * For simplicity, we read one record in one system call and throw out
 295  * what does not fit. This means that the following does not work:
 296  *   dd if=/dbg/usbmon/0t bs=10
 297  * Also, we do not allow seeks and do not bother advancing the offset.
 298  */
 299 static ssize_t mon_text_read(struct file *file, char __user *buf,
 300                                 size_t nbytes, loff_t *ppos)
 301 {
 302         struct mon_reader_text *rp = file->private_data;
 303         struct mon_bus *mbus = rp->r.m_bus;
 304         DECLARE_WAITQUEUE(waita, current);
 305         struct mon_event_text *ep;
 306         int cnt, limit;
 307         char *pbuf;
 308         char udir, utype;
 309         int data_len, i;
 310
 311         add_wait_queue(&rp->wait, &waita);
 312         set_current_state(TASK_INTERRUPTIBLE);
 313         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 314                 if (file->f_flags & O_NONBLOCK) {
 315                         set_current_state(TASK_RUNNING);
 316                         remove_wait_queue(&rp->wait, &waita);
 317                         return -EWOULDBLOCK;    /* Same as EAGAIN in Linux */
 318                 }
 319                 /*
 320                  * We do not count nwaiters, because ->release is supposed
 321                  * to be called when all openers are gone only.
 322                  */
 323                 schedule();
 324                 if (signal_pending(current)) {
 325                         remove_wait_queue(&rp->wait, &waita);
 326                         return -EINTR;
 327                 }
 328                 set_current_state(TASK_INTERRUPTIBLE);
 329         }
 330         set_current_state(TASK_RUNNING);
 331         remove_wait_queue(&rp->wait, &waita);
 332
 333         mutex_lock(&rp->printf_lock);
 334         cnt = 0;
 335         pbuf = rp->printf_buf;
 336         limit = rp->printf_size;
 337
 338         udir = usb_pipein(ep->pipe) ? 'i' : 'o';
 339         switch (usb_pipetype(ep->pipe)) {
 340         case PIPE_ISOCHRONOUS:  utype = 'Z'; break;
 341         case PIPE_INTERRUPT:    utype = 'I'; break;
 342         case PIPE_CONTROL:      utype = 'C'; break;
 343         default: /* PIPE_BULK */  utype = 'B';
 344         }
 345         cnt += snprintf(pbuf + cnt, limit - cnt,
 346             "%lx %u %c %c%c:%03u:%02u",
 347             ep->id, ep->tstamp, ep->type,
 348             utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe));
 349
 350         if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 351                 cnt += snprintf(pbuf + cnt, limit - cnt,
 352                     " s %02x %02x %04x %04x %04x",
 353                     ep->setup[0],
 354                     ep->setup[1],
 355                     (ep->setup[3] << 8) | ep->setup[2],
 356                     (ep->setup[5] << 8) | ep->setup[4],
 357                     (ep->setup[7] << 8) | ep->setup[6]);
 358         } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 359                 cnt += snprintf(pbuf + cnt, limit - cnt,
 360                     " %c __ __ ____ ____ ____", ep->setup_flag);
 361         } else {                     /* No setup for this kind of URB */
 362                 cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->status);
 363         }
 364         cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->length);
 365
 366         if ((data_len = ep->length) > 0) {
 367                 if (ep->data_flag == 0) {
 368                         cnt += snprintf(pbuf + cnt, limit - cnt, " =");
 369                         if (data_len >= DATA_MAX)
 370                                 data_len = DATA_MAX;
 371                         for (i = 0; i < data_len; i++) {
 372                                 if (i % 4 == 0) {
 373                                         cnt += snprintf(pbuf + cnt, limit - cnt,
 374                                             " ");
 375                                 }
 376                                 cnt += snprintf(pbuf + cnt, limit - cnt,
 377                                     "%02x", ep->data[i]);
 378                         }
 379                         cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
 380                 } else {
 381                         cnt += snprintf(pbuf + cnt, limit - cnt,
 382                             " %c\n", ep->data_flag);
 383                 }
 384         } else {
 385                 cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
 386         }
 387
 388         if (copy_to_user(buf, rp->printf_buf, cnt))
 389                 cnt = -EFAULT;
 390         mutex_unlock(&rp->printf_lock);
 391         kmem_cache_free(rp->e_slab, ep);
 392         return cnt;
 393 }
 394
 395 static int mon_text_release(struct inode *inode, struct file *file)
 396 {
 397         struct mon_reader_text *rp = file->private_data;
 398         struct mon_bus *mbus;
 399         /* unsigned long flags; */
 400         struct list_head *p;
 401         struct mon_event_text *ep;
 402
 403         mutex_lock(&mon_lock);
 404         mbus = inode->i_private;
 405
 406         if (mbus->nreaders <= 0) {
 407                 printk(KERN_ERR TAG ": consistency error on close\n");
 408                 mutex_unlock(&mon_lock);
 409                 return 0;
 410         }
 411         mon_reader_del(mbus, &rp->r);
 412
 413         /*
 414          * In theory, e_list is protected by mbus->lock. However,
 415          * after mon_reader_del has finished, the following is the case:
 416          *  - we are not on reader list anymore, so new events won't be added;
 417          *  - whole mbus may be dropped if it was orphaned.
 418          * So, we better not touch mbus.
 419          */
 420         /* spin_lock_irqsave(&mbus->lock, flags); */
 421         while (!list_empty(&rp->e_list)) {
 422                 p = rp->e_list.next;
 423                 ep = list_entry(p, struct mon_event_text, e_link);
 424                 list_del(p);
 425                 --rp->nevents;
 426                 kmem_cache_free(rp->e_slab, ep);
 427         }
 428         /* spin_unlock_irqrestore(&mbus->lock, flags); */
 429
 430         kmem_cache_destroy(rp->e_slab);
 431         kfree(rp->printf_buf);
 432         kfree(rp);
 433
 434         mutex_unlock(&mon_lock);
 435         return 0;
 436 }
 437
 438 struct file_operations mon_fops_text = {
 439         .owner =        THIS_MODULE,
 440         .open =         mon_text_open,
 441         .llseek =       no_llseek,
 442         .read =         mon_text_read,
 443         /* .write =     mon_text_write, */
 444         /* .poll =              mon_text_poll, */
 445         /* .ioctl =     mon_text_ioctl, */
 446         .release =      mon_text_release,
 447 };
 448
 449 /*
 450  * Slab interface: constructor.
 451  */
 452 static void mon_text_ctor(void *mem, kmem_cache_t *slab, unsigned long sflags)
 453 {
 454         /*
 455          * Nothing to initialize. No, really!
 456          * So, we fill it with garbage to emulate a reused object.
 457          */
 458         memset(mem, 0xe5, sizeof(struct mon_event_text));
 459 }
 460