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         struct kmem_cache *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 *, struct kmem_cache *, 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, struct mon_bus *mbus)
  79 {
  80
  81         if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
  82                 return '-';
  83
  84         if (mbus->uses_dma && (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, struct mon_bus *mbus)
  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 (mbus->uses_dma && (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, GFP_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, rp->r.m_bus);
 165         ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
 166                         rp->r.m_bus);
 167
 168         rp->nevents++;
 169         list_add_tail(&ep->e_link, &rp->e_list);
 170         wake_up(&rp->wait);
 171 }
 172
 173 static void mon_text_submit(void *data, struct urb *urb)
 174 {
 175         struct mon_reader_text *rp = data;
 176         mon_text_event(rp, urb, 'S');
 177 }
 178
 179 static void mon_text_complete(void *data, struct urb *urb)
 180 {
 181         struct mon_reader_text *rp = data;
 182         mon_text_event(rp, urb, 'C');
 183 }
 184
 185 static void mon_text_error(void *data, struct urb *urb, int error)
 186 {
 187         struct mon_reader_text *rp = data;
 188         struct mon_event_text *ep;
 189
 190         if (rp->nevents >= EVENT_MAX ||
 191             (ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
 192                 rp->r.m_bus->cnt_text_lost++;
 193                 return;
 194         }
 195
 196         ep->type = 'E';
 197         ep->pipe = urb->pipe;
 198         ep->id = (unsigned long) urb;
 199         ep->tstamp = 0;
 200         ep->length = 0;
 201         ep->status = error;
 202
 203         ep->setup_flag = '-';
 204         ep->data_flag = 'E';
 205
 206         rp->nevents++;
 207         list_add_tail(&ep->e_link, &rp->e_list);
 208         wake_up(&rp->wait);
 209 }
 210
 211 /*
 212  * Fetch next event from the circular buffer.
 213  */
 214 static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
 215     struct mon_bus *mbus)
 216 {
 217         struct list_head *p;
 218         unsigned long flags;
 219
 220         spin_lock_irqsave(&mbus->lock, flags);
 221         if (list_empty(&rp->e_list)) {
 222                 spin_unlock_irqrestore(&mbus->lock, flags);
 223                 return NULL;
 224         }
 225         p = rp->e_list.next;
 226         list_del(p);
 227         --rp->nevents;
 228         spin_unlock_irqrestore(&mbus->lock, flags);
 229         return list_entry(p, struct mon_event_text, e_link);
 230 }
 231
 232 /*
 233  */
 234 static int mon_text_open(struct inode *inode, struct file *file)
 235 {
 236         struct mon_bus *mbus;
 237         struct usb_bus *ubus;
 238         struct mon_reader_text *rp;
 239         int rc;
 240
 241         mutex_lock(&mon_lock);
 242         mbus = inode->i_private;
 243         ubus = mbus->u_bus;
 244
 245         rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
 246         if (rp == NULL) {
 247                 rc = -ENOMEM;
 248                 goto err_alloc;
 249         }
 250         INIT_LIST_HEAD(&rp->e_list);
 251         init_waitqueue_head(&rp->wait);
 252         mutex_init(&rp->printf_lock);
 253
 254         rp->printf_size = PRINTF_DFL;
 255         rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
 256         if (rp->printf_buf == NULL) {
 257                 rc = -ENOMEM;
 258                 goto err_alloc_pr;
 259         }
 260
 261         rp->r.m_bus = mbus;
 262         rp->r.r_data = rp;
 263         rp->r.rnf_submit = mon_text_submit;
 264         rp->r.rnf_error = mon_text_error;
 265         rp->r.rnf_complete = mon_text_complete;
 266
 267         snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
 268             (long)rp);
 269         rp->e_slab = kmem_cache_create(rp->slab_name,
 270             sizeof(struct mon_event_text), sizeof(long), 0,
 271             mon_text_ctor, NULL);
 272         if (rp->e_slab == NULL) {
 273                 rc = -ENOMEM;
 274                 goto err_slab;
 275         }
 276
 277         mon_reader_add(mbus, &rp->r);
 278
 279         file->private_data = rp;
 280         mutex_unlock(&mon_lock);
 281         return 0;
 282
 283 // err_busy:
 284 //      kmem_cache_destroy(rp->e_slab);
 285 err_slab:
 286         kfree(rp->printf_buf);
 287 err_alloc_pr:
 288         kfree(rp);
 289 err_alloc:
 290         mutex_unlock(&mon_lock);
 291         return rc;
 292 }
 293
 294 /*
 295  * For simplicity, we read one record in one system call and throw out
 296  * what does not fit. This means that the following does not work:
 297  *   dd if=/dbg/usbmon/0t bs=10
 298  * Also, we do not allow seeks and do not bother advancing the offset.
 299  */
 300 static ssize_t mon_text_read(struct file *file, char __user *buf,
 301                                 size_t nbytes, loff_t *ppos)
 302 {
 303         struct mon_reader_text *rp = file->private_data;
 304         struct mon_bus *mbus = rp->r.m_bus;
 305         DECLARE_WAITQUEUE(waita, current);
 306         struct mon_event_text *ep;
 307         int cnt, limit;
 308         char *pbuf;
 309         char udir, utype;
 310         int data_len, i;
 311
 312         add_wait_queue(&rp->wait, &waita);
 313         set_current_state(TASK_INTERRUPTIBLE);
 314         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
 315                 if (file->f_flags & O_NONBLOCK) {
 316                         set_current_state(TASK_RUNNING);
 317                         remove_wait_queue(&rp->wait, &waita);
 318                         return -EWOULDBLOCK;    /* Same as EAGAIN in Linux */
 319                 }
 320                 /*
 321                  * We do not count nwaiters, because ->release is supposed
 322                  * to be called when all openers are gone only.
 323                  */
 324                 schedule();
 325                 if (signal_pending(current)) {
 326                         remove_wait_queue(&rp->wait, &waita);
 327                         return -EINTR;
 328                 }
 329                 set_current_state(TASK_INTERRUPTIBLE);
 330         }
 331         set_current_state(TASK_RUNNING);
 332         remove_wait_queue(&rp->wait, &waita);
 333
 334         mutex_lock(&rp->printf_lock);
 335         cnt = 0;
 336         pbuf = rp->printf_buf;
 337         limit = rp->printf_size;
 338
 339         udir = usb_pipein(ep->pipe) ? 'i' : 'o';
 340         switch (usb_pipetype(ep->pipe)) {
 341         case PIPE_ISOCHRONOUS:  utype = 'Z'; break;
 342         case PIPE_INTERRUPT:    utype = 'I'; break;
 343         case PIPE_CONTROL:      utype = 'C'; break;
 344         default: /* PIPE_BULK */  utype = 'B';
 345         }
 346         cnt += snprintf(pbuf + cnt, limit - cnt,
 347             "%lx %u %c %c%c:%03u:%02u",
 348             ep->id, ep->tstamp, ep->type,
 349             utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe));
 350
 351         if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
 352                 cnt += snprintf(pbuf + cnt, limit - cnt,
 353                     " s %02x %02x %04x %04x %04x",
 354                     ep->setup[0],
 355                     ep->setup[1],
 356                     (ep->setup[3] << 8) | ep->setup[2],
 357                     (ep->setup[5] << 8) | ep->setup[4],
 358                     (ep->setup[7] << 8) | ep->setup[6]);
 359         } else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
 360                 cnt += snprintf(pbuf + cnt, limit - cnt,
 361                     " %c __ __ ____ ____ ____", ep->setup_flag);
 362         } else {                     /* No setup for this kind of URB */
 363                 cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->status);
 364         }
 365         cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->length);
 366
 367         if ((data_len = ep->length) > 0) {
 368                 if (ep->data_flag == 0) {
 369                         cnt += snprintf(pbuf + cnt, limit - cnt, " =");
 370                         if (data_len >= DATA_MAX)
 371                                 data_len = DATA_MAX;
 372                         for (i = 0; i < data_len; i++) {
 373                                 if (i % 4 == 0) {
 374                                         cnt += snprintf(pbuf + cnt, limit - cnt,
 375                                             " ");
 376                                 }
 377                                 cnt += snprintf(pbuf + cnt, limit - cnt,
 378                                     "%02x", ep->data[i]);
 379                         }
 380                         cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
 381                 } else {
 382                         cnt += snprintf(pbuf + cnt, limit - cnt,
 383                             " %c\n", ep->data_flag);
 384                 }
 385         } else {
 386                 cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
 387         }
 388
 389         if (copy_to_user(buf, rp->printf_buf, cnt))
 390                 cnt = -EFAULT;
 391         mutex_unlock(&rp->printf_lock);
 392         kmem_cache_free(rp->e_slab, ep);
 393         return cnt;
 394 }
 395
 396 static int mon_text_release(struct inode *inode, struct file *file)
 397 {
 398         struct mon_reader_text *rp = file->private_data;
 399         struct mon_bus *mbus;
 400         /* unsigned long flags; */
 401         struct list_head *p;
 402         struct mon_event_text *ep;
 403
 404         mutex_lock(&mon_lock);
 405         mbus = inode->i_private;
 406
 407         if (mbus->nreaders <= 0) {
 408                 printk(KERN_ERR TAG ": consistency error on close\n");
 409                 mutex_unlock(&mon_lock);
 410                 return 0;
 411         }
 412         mon_reader_del(mbus, &rp->r);
 413
 414         /*
 415          * In theory, e_list is protected by mbus->lock. However,
 416          * after mon_reader_del has finished, the following is the case:
 417          *  - we are not on reader list anymore, so new events won't be added;
 418          *  - whole mbus may be dropped if it was orphaned.
 419          * So, we better not touch mbus.
 420          */
 421         /* spin_lock_irqsave(&mbus->lock, flags); */
 422         while (!list_empty(&rp->e_list)) {
 423                 p = rp->e_list.next;
 424                 ep = list_entry(p, struct mon_event_text, e_link);
 425                 list_del(p);
 426                 --rp->nevents;
 427                 kmem_cache_free(rp->e_slab, ep);
 428         }
 429         /* spin_unlock_irqrestore(&mbus->lock, flags); */
 430
 431         kmem_cache_destroy(rp->e_slab);
 432         kfree(rp->printf_buf);
 433         kfree(rp);
 434
 435         mutex_unlock(&mon_lock);
 436         return 0;
 437 }
 438
 439 const struct file_operations mon_fops_text = {
 440         .owner =        THIS_MODULE,
 441         .open =         mon_text_open,
 442         .llseek =       no_llseek,
 443         .read =         mon_text_read,
 444         /* .write =     mon_text_write, */
 445         /* .poll =              mon_text_poll, */
 446         /* .ioctl =     mon_text_ioctl, */
 447         .release =      mon_text_release,
 448 };
 449
 450 /*
 451  * Slab interface: constructor.
 452  */
 453 static void mon_text_ctor(void *mem, struct kmem_cache *slab, unsigned long sflags)
 454 {
 455         /*
 456          * Nothing to initialize. No, really!
 457          * So, we fill it with garbage to emulate a reused object.
 458          */
 459         memset(mem, 0xe5, sizeof(struct mon_event_text));
 460 }
 461