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/*
* 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 <linux/debugfs.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 (4*PAGE_SIZE / sizeof(struct mon_event_text))
/*
* Potentially unlimited number; we limit it for similar allocations.
* The usbfs limits this to 128, but we're not quite as generous.
*/
#define ISODESC_MAX 5
#define PRINTF_DFL 250 /* with 5 ISOs segs */
struct mon_iso_desc {
int status;
unsigned int offset;
unsigned int length; /* Unsigned here, signed in URB. Historic. */
};
struct mon_event_text {
struct list_head e_link;
int type; /* submit, complete, etc. */
unsigned long id; /* From pointer, most of the time */
unsigned int tstamp;
int busnum;
char devnum;
char epnum;
char is_in;
char xfertype;
int length; /* Depends on type: xfer length or act length */
int status;
int interval;
int start_frame;
int error_count;
char setup_flag;
char data_flag;
int numdesc; /* Full number */
struct mon_iso_desc isodesc[ISODESC_MAX];
unsigned char setup[SETUP_MAX];
unsigned char data[DATA_MAX];
};
#define SLAB_NAME_SZ 30
struct mon_reader_text {
struct kmem_cache *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 struct dentry *mon_dir; /* Usually /sys/kernel/debug/usbmon */
static void mon_text_ctor(struct kmem_cache *, void *);
struct mon_text_ptr {
int cnt, limit;
char *pbuf;
};
static struct mon_event_text *
mon_text_read_wait(struct mon_reader_text *rp, struct file *file);
static void mon_text_read_head_t(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
static void mon_text_read_head_u(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
static void mon_text_read_statset(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
static void mon_text_read_intstat(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
static void mon_text_read_isostat(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
static void mon_text_read_isodesc(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
static void mon_text_read_data(struct mon_reader_text *rp,
struct mon_text_ptr *p, const struct mon_event_text *ep);
/*
* 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 (ep->xfertype != USB_ENDPOINT_XFER_CONTROL || ev_type != 'S')
return '-';
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)
{
if (len <= 0)
return 'L';
if (len >= DATA_MAX)
len = DATA_MAX;
if (ep->is_in) {
if (ev_type != 'C')
return '<';
} else {
if (ev_type != 'S')
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 (urb->dev->bus->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, int status)
{
struct mon_event_text *ep;
unsigned int stamp;
struct usb_iso_packet_descriptor *fp;
struct mon_iso_desc *dp;
int i, ndesc;
stamp = mon_get_timestamp();
if (rp->nevents >= EVENT_MAX ||
(ep = kmem_cache_alloc(rp->e_slab, GFP_ATOMIC)) == NULL) {
rp->r.m_bus->cnt_text_lost++;
return;
}
ep->type = ev_type;
ep->id = (unsigned long)
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