/*
* The USB Monitor, inspired by Dave Harding's USBMon.
*
* This is a text format reader.
*/
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/usb.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include "usb_mon.h"
/*
* No, we do not want arbitrarily long data strings.
* Use the binary interface if you want to capture bulk data!
*/
#define DATA_MAX 32
/*
* Defined by USB 2.0 clause 9.3, table 9.2.
*/
#define SETUP_MAX 8
/*
* This limit exists to prevent OOMs when the user process stops reading.
* If usbmon were available to unprivileged processes, it might be open
* to a local DoS. But we have to keep to root in order to prevent
* password sniffing from HID devices.
*/
#define EVENT_MAX (2*PAGE_SIZE / sizeof(struct mon_event_text))
#define PRINTF_DFL 160
struct mon_event_text {
struct list_head e_link;
int type; /* submit, complete, etc. */
unsigned int pipe; /* Pipe */
unsigned long id; /* From pointer, most of the time */
unsigned int tstamp;
int length; /* Depends on type: xfer length or act length */
int status;
char setup_flag;
char data_flag;
unsigned char setup[SETUP_MAX];
unsigned char data[DATA_MAX];
};
#define SLAB_NAME_SZ 30
struct mon_reader_text {
kmem_cache_t *e_slab;
int nevents;
struct list_head e_list;
struct mon_reader r; /* In C, parent class can be placed anywhere */
wait_queue_head_t wait;
int printf_size;
char *printf_buf;
struct mutex printf_lock;
char slab_name[SLAB_NAME_SZ];
};
static void mon_text_ctor(void *, kmem_cache_t *, unsigned long);
/*
* mon_text_submit
* mon_text_complete
*
* May be called from an interrupt.
*
* This is called with the whole mon_bus locked, so no additional lock.
*/
static inline char mon_text_get_setup(struct mon_event_text *ep,
struct urb *urb, char ev_type, struct mon_bus *mbus)
{
if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
return '-';
if (mbus->uses_dma && (urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
return mon_dmapeek(ep->setup, urb->setup_dma, SETUP_MAX);
if (urb->setup_packet == NULL)
return 'Z'; /* '0' would be not as pretty. */
memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
return 0;
}
static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
int len, char ev_type, struct mon_bus *mbus)
{
int pipe = urb->pipe;
if (len <= 0)
return 'L';
if (len >= DATA_MAX)
len = DATA_MAX;
if (usb_pipein(pipe)) {
if (ev_type == 'S')
return '<';
} else {
if (ev_type == 'C')
return '>';
}
/*
* The check to see if it's safe to poke at data has an enormous
* number of corner cases, but it seems that the following is
* more or less safe.
*
* We do not even try to look at transfer_buffer, because it can
* contain non-NULL garbage in case the upper level promised to
* set DMA for the HCD.
*/
if (mbus->uses_dma && (urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
return mon_dmapeek(ep->data, urb->transfer_dma, len);
if (urb->transfer_buffer == NULL)
return 'Z'; /* '0' would be not as pretty. */
memcpy(ep->data, urb->transfer_buffer, len);
return 0;
}
static inline unsigned int mon_get_timestamp(void)
{
struct timeval tval;
unsigned int stamp;
do_gettimeofday(&tval);
stamp = tval.tv_sec & 0xFFFF; /* 2^32 = 4294967296. Limit to 4096s. */
stamp = stamp * 1000000 + tval.tv_usec;
return stamp;
}
static void mon_text_event(struct mon_reader_text *rp, struct urb *urb,
char ev_type)
{
struct mon_event_text *ep;
unsigned int stamp;
stamp = mon_get_timestamp();
if (rp->nevents >= EVENT_MAX ||
(ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
rp->r.m_bus->cnt_text_lost++;
return;
}
ep->type = ev_type;
ep->pipe = urb->pipe;
ep->id = (unsigned long) urb;
ep->tstamp = stamp;
ep->length = (ev_type == 'S') ?
urb->transfer_buffer_length : urb->actual_length;
/* Collecting status makes debugging sense for submits, too */
ep->status = urb->status;
ep->setup_flag = mon_text_get_setup(ep, urb, ev_type, rp->r.m_bus);
ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type,
rp->r.m_bus);
rp->nevents++;
list_add_tail(&ep->e_link, &rp->e_list);
wake_up(&rp->wait);
}
static void mon_text_submit(void *data, struct urb *urb)
{
struct mon_reader_text *rp = data;
mon_text_event(rp, urb, 'S');
}
static void mon_text_complete(void *data, struct urb *urb)
{
struct mon_reader_text *rp = data;
mon_text_event(rp, urb, 'C');
}
static void mon_text_error(void *data, struct urb *urb, int error)
{
struct mon_reader_text *rp = data;
struct mon_event_text *ep;
if (rp->nevents >= EVENT_MAX ||
(ep = kmem_cache_alloc(rp->e_slab, SLAB_ATOMIC)) == NULL) {
rp->r.m_bus->cnt_text_lost++;
return;
}
ep->type = 'E';
ep->pipe = urb->pipe;
ep->id = (unsigned long) urb;
ep->tstamp = 0;
ep->length = 0;
ep->status = error;
ep->setup_flag = '-';
ep->data_flag = 'E';
rp->nevents++;
list_add_tail(&ep->e_link, &rp->e_list);
wake_up(&rp->wait);
}
/*
* Fetch next event from the circular buffer.
*/
static struct mon_event_text *mon_text_fetch(struct mon_reader_text *rp,
struct mon_bus *mbus)
{
struct list_head *p;
unsigned long flags;
spin_lock_irqsave(&mbus->lock, flags);
if (list_empty(&rp->e_list)) {
spin_unlock_irqrestore(&mbus->lock, flags);
return NULL;
}
p = rp->e_list.next;
list_del(p);
--rp->nevents;
spin_unlock_irqrestore(&mbus->lock, flags);
return list_entry(p, struct mon_event_text, e_link);
}
/*
*/
static int mon_text_open(struct inode *inode, struct file *file)
{
struct mon_bus *mbus;
struct usb_bus *ubus;
struct mon_reader_text *rp;
int rc;
mutex_lock(&mon_lock);
mbus = inode->i_private;
ubus = mbus->u_bus;
rp = kzalloc(sizeof(struct mon_reader_text), GFP_KERNEL);
if (rp == NULL) {
rc = -ENOMEM;
goto err_alloc;
}
INIT_LIST_HEAD(&rp->e_list);
init_waitqueue_head(&rp->wait);
mutex_init(&rp->printf_lock);
rp->printf_size = PRINTF_DFL;
rp->printf_buf = kmalloc(rp->printf_size, GFP_KERNEL);
if (rp->printf_buf == NULL) {
rc = -ENOMEM;
goto err_alloc_pr;
}
rp->r.m_bus = mbus;
rp->r.r_data = rp;
rp->r.rnf_submit = mon_text_submit;
rp->r.rnf_error = mon_text_error;
rp->r.rnf_complete = mon_text_complete;
snprintf(rp->slab_name, SLAB_NAME_SZ, "mon%dt_%lx", ubus->busnum,
(long)rp);
rp->e_slab = kmem_cache_create(rp->slab_name,
sizeof(struct mon_event_text), sizeof(long), 0,
mon_text_ctor, NULL);
if (rp->e_slab == NULL) {
rc = -ENOMEM;
goto err_slab;
}
mon_reader_add(mbus, &rp->r);
file->private_data = rp;
mutex_unlock(&mon_lock);
return 0;
// err_busy:
// kmem_cache_destroy(rp->e_slab);
err_slab:
kfree(rp->printf_buf);
err_alloc_pr:
kfree(rp);
err_alloc:
mutex_unlock(&mon_lock);
return rc;
}
/*
* For simplicity, we read one record in one system call and throw out
* what does not fit. This means that the following does not work:
* dd if=/dbg/usbmon/0t bs=10
* Also, we do not allow seeks and do not bother advancing the offset.
*/
static ssize_t mon_text_read(struct file *file, char __user *buf,
size_t nbytes, loff_t *ppos)
{
struct mon_reader_text *rp = file->private_data;
struct mon_bus *mbus = rp->r.m_bus;
DECLARE_WAITQUEUE(waita, current);
struct mon_event_text *ep;
int cnt, limit;
char *pbuf;
char udir, utype;
int data_len, i;
add_wait_queue(&rp->wait, &waita);
set_current_state(TASK_INTERRUPTIBLE);
while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
if (file->f_flags & O_NONBLOCK) {
set_current_state(TASK_RUNNING);
remove_wait_queue(&rp->wait, &waita);
return -EWOULDBLOCK; /* Same as EAGAIN in Linux */
}
/*
* We do not count nwaiters, because ->release is supposed
* to be called when all openers are gone only.
*/
schedule();
if (signal_pending(current)) {
remove_wait_queue(&rp->wait, &waita);
return -EINTR;
}
set_current_state(TASK_INTERRUPTIBLE);
}
set_current_state(TASK_RUNNING);
remove_wait_queue(&rp->wait, &waita);
mutex_lock(&rp->printf_lock);
cnt = 0;
pbuf = rp->printf_buf;
limit = rp->printf_size;
udir = usb_pipein(ep->pipe) ? 'i' : 'o';
switch (usb_pipetype(ep->pipe)) {
case PIPE_ISOCHRONOUS: utype = 'Z'; break;
case PIPE_INTERRUPT: utype = 'I'; break;
case PIPE_CONTROL: utype = 'C'; break;
default: /* PIPE_BULK */ utype = 'B';
}
cnt += snprintf(pbuf + cnt, limit - cnt,
"%lx %u %c %c%c:%03u:%02u",
ep->id, ep->tstamp, ep->type,
utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe));
if (ep->setup_flag == 0) { /* Setup packet is present and captured */
cnt += snprintf(pbuf + cnt, limit - cnt,
" s %02x %02x %04x %04x %04x",
ep->setup[0],
ep->setup[1],
(ep->setup[3] << 8) | ep->setup[2],
(ep->setup[5] << 8) | ep->setup[4],
(ep->setup[7] << 8) | ep->setup[6]);
} else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
cnt += snprintf(pbuf + cnt, limit - cnt,
" %c __ __ ____ ____ ____", ep->setup_flag);
} else { /* No setup for this kind of URB */
cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->status);
}
cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->length);
if ((data_len = ep->length) > 0) {
if (ep->data_flag == 0) {
cnt += snprintf(pbuf + cnt, limit - cnt, " =");
if (data_len >= DATA_MAX)
data_len = DATA_MAX;
for (i = 0; i < data_len; i++) {
if (i % 4 == 0) {
cnt += snprintf(pbuf + cnt, limit - cnt,
" ");
}
cnt += snprintf(pbuf + cnt, limit - cnt,
"%02x", ep->data[i]);
}
cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
} else {
cnt += snprintf(pbuf + cnt, limit - cnt,
" %c\n", ep->data_flag);
}
} else {
cnt += snprintf(pbuf + cnt, limit - cnt, "\n");
}
if (copy_to_user(buf, rp->printf_buf, cnt))
cnt = -EFAULT;
mutex_unlock(&rp->printf_lock);
kmem_cache_free(rp->e_slab, ep);
return cnt;
}
static int mon_text_release(struct inode *inode, struct file *file)
{
struct mon_reader_text *rp = file->private_data;
struct mon_bus *mbus;
/* unsigned long flags; */
struct list_head *p;
struct mon_event_text *ep;
mutex_lock(&mon_lock);
mbus = inode->i_private;
if (mbus->nreaders <= 0) {
printk(KERN_ERR TAG ": consistency error on close\n");
mutex_unlock(&mon_lock);
return 0;
}
mon_reader_del(mbus, &rp->r);
/*
* In theory, e_list is protected by mbus->lock. However,
* after mon_reader_del has finished, the following is the case:
* - we are not on reader list anymore, so new events won't be added;
* - whole mbus may be dropped if it was orphaned.
* So, we better not touch mbus.
*/
/* spin_lock_irqsave(&mbus->lock, flags); */
while (!list_empty(&rp->e_list)) {
p = rp->e_list.next;
ep = list_entry(p, struct mon_event_text, e_link);
list_del(p);
--rp->nevents;
kmem_cache_free(rp->e_slab, ep);
}
/* spin_unlock_irqrestore(&mbus->lock, flags); */
kmem_cache_destroy(rp->e_slab);
kfree(rp->printf_buf);
kfree(rp);
mutex_unlock(&mon_lock);
return 0;
}
const struct file_operations mon_fops_text = {
.owner = THIS_MODULE,
.open = mon_text_open,
.llseek = no_llseek,
.read = mon_text_read,
/* .write = mon_text_write, */
/* .poll = mon_text_poll, */
/* .ioctl = mon_text_ioctl, */
.release = mon_text_release,
};
/*
* Slab interface: constructor.
*/
static void mon_text_ctor(void *mem, kmem_cache_t *slab, unsigned long sflags)
{
/*
* Nothing to initialize. No, really!
* So, we fill it with garbage to emulate a reused object.
*/
memset(mem, 0xe5, sizeof(struct mon_event_text));
}
