分类: Android平台
2016-08-23 18:47:18
原文地址:linux下的usb抓包方法 作者:zxg623
1、配置内核使能usb monitor:
make menuconfig
Device Drivers -->
USB Support -->
USB Monitor --> Select * not M
2、build kernel
sudo insmod /lib/modules/3.2.1/kernel/drivers/usb/mon/usbmon.ko
3、启动内核后执行
#mount -t debugfs none_debugs /sys/kernel/debug
检查是否存在目录 /sys/kernel/debug/usb/usbmon
#ls /sys/kernel/debug/usb/usbmon
0s 0u 1s 1t 1u 2s 2t 2u 3s 3t 3u
# cat /sys/kernel/debug/usb/devices 确定你要监视的usb设备所在总线号和设备号
# 选择包含有 : Vendor=148f ProdID=5370 Rev= 1.01 的段落
# as follows:
# T: Bus=01Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=480 MxCh= 0
# D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
# P: Vendor=148f ProdID=5370 Rev= 1.01
# S: Manufacturer=Ralink
# S: Product=802.11 n WLAN
# S: SerialNumber=1.0
# C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=450mA
# I:* If#= 0 Alt= 0 #EPs= 5 Cls=ff(vend.) Sub=ff Prot=ff Driver=rtusbSTA
# E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
# E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
# E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
# E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
# E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
# 可以从第一行看到 Bus= 01,设备号是2
The usbmon reports requests made by peripheral-specific drivers to Host
Controller Drivers (HCD). So, if HCD is buggy, the traces reported by
usbmon may not correspond to bus transactions precisely. This is the same
situation as with tcpdump.
上面的基本说明了usbmon主要的工作原理,他会把usb host drivers发送到hcd的所有请求(usb_submit_urb)和请求的回调内容(即改请求对应的回调函数:urb->complete)都报告出来。
urb = usb_alloc_urb(0, mem_flags);
由于一个urb对应一个端口,所以同一个端口他们的urb tag都是一样的。
002e2002999116296 C Ci:1:008:0 0 4 = 8d2b0000
Timestampin microseconds, a decimal number. The timestamp's resolution
depends on available clock, and so it can be much worse than a microsecond
(if the implementation uses jiffies, for example).
e002e200 2999116296Ci:1:008:0 0 4 = 8d2b0000
注意单位是微秒。
- Event Type. This type refers to the format of the event, not URB type.
Available types are:S - submission, C - callback, E - submission error.
e002e200 2999116296 C Ci:1:008:0 0 4 = 8d2b0000
表示的意思是:usb host drivers通过usb_submit_urb函数向linuxusb core提交了一个urb传输请求,我们知道所有的usb传输,都是host端主动发起的,所以必须要有host drivers主动发出submit urb的动作
- "Address" word (formerly a "pipe"). It consists of four fields, separated by
colons: URB type and direction, Bus number, Device address, Endpoint number.
Type and direction are encoded with two bytes in the following manner:
Ci Co Control input and output
Zi Zo Isochronous input and output
Ii Io Interrupt input and output
Bi Bo Bulk input and output
Bus number, Device address, and Endpoint are decimal numbers, but they may
have leading zeros, for the sake of human readers.
所以地址字段的格式是如下:
URB type and direction:Bus number:Device address:Endpoint number
如下列子:
e002e200 2999116296 C Ci:1:008:0 0 4 = 8d2b0000
意思是:控制传输输入,总线号为1,设备地址为008,由于所有的控制传输都是在endpoint 0上的,所以最后的端口自然也是0了。
这里需要注意,由于我们的这个抓包命令,只能指定是抓哪个总线上,但同一个总线通常会有很多usb设备的,如果我们只是关注特定的某个usb设备的话,我自己就需要留意设备地址字段,通过这个字段,我们就可以区分这个传输是不是我们要监听的设备发送出来的。
例如下面一段usb sniffer log:
edda2b80 3500379613 C Ii:1:006:1 0:1 8 = 0e06010d 08004700
edda2b80 3500394156 S Ii:1:006:1-115:1 16 <
eea76f80 3500394226 C Ii:1:003:3 0:128 16 = a12a0000 01000800 00e1f505 00e1f505
eea76f80 3500394236 S Ii:1:003:3 -115:128 16 <
同样都是usb总线1下面的,由于一个usb总线就对应一个usb host controller,但一个设备地址是006,另一个则是003,前者对应的是usb bluetooth dongle的中断传输,而后者则是usb鼠标的中断传输,他们接在同一个总线的usb hub下面。我们真正需要监听只是usb bluetooth dongle,所以就可以不受usb鼠标的干扰。
- URB Status word. This is either a letter, or several numbers separated
by colons: URB status, interval, start frame, and error count. Unlike the
"address" word, all fields save the status are optional. Interval is printed
only for interrupt and isochronous URBs. Start frame is printed only for
isochronous URBs. Error count is printed only for isochronous callback
events.
这里的意思就是,urb的状态字,有两种可能,一种是“字母”;一种是“数字”,如果是前者则一般就是字母“s”,表示一个控制传输,而如果是数字,他们的格式则分两种情况:
如果是中断传输,格式如下: URB status:interval,注意状态字段只对C类型的事件有意义,对S类型的事件没有意思。
如果是同步传输,格式如下:URB status:interval:{start frame}:{error count}
The status field is a decimal number, sometimes negative, which represents
a "status" field of the URB. This field makes no sense for submissions, but
is present anyway to help scripts with parsing. When an error occurs, the
field contains the error code.
e002e200 2999116296 C Ci:1:008:0 0 4 = 8d2b0000
状态域:status就是struct urb结构体中的status字段,该字段直接说明当前的usb请求是否成功执行。所以只有在回调的时候才有意思。
In case of a submission of a Control packet, this field contains a Setup Tag
instead of an group of numbers. It is easy to tell whether the Setup Tag is
present because it is never a number. Thus if scripts find a set of numbers
in this word, they proceed to read Data Length (except for isochronous URBs).
If they find something else, like a letter, they read the setup packet before
reading the Data Length or isochronous descriptors.
e002e200 2999116113 S Ci:1:008:0 s c0 07 0000 1134 0004 4 <
字母“s”是控制传输的标志
- Setup packet, if present, consists of 5 words: one of each for bmRequestType,
bRequest, wValue, wIndex, wLength, as specified by the USB Specification 2.0.
These words are safe to decode if Setup Tag was 's'. Otherwise, the setup
packet was present, but not captured, and the fields contain filler.
即控制传输包的格式如下:
bmRequestType(请求类型):bRequest(请求号):wValue:wIndex(下标):wLength(数据字段的长度,如果为0,说明没有数据段)
usbmon is a facility in kernel which is used to collect traces of I/O on the USB bus. usbmon collects raw text/binary which are not easily human-readable. Here, the idea is to use Wireshark as frontend to produces a human-readable representation of these data. However Wireshark does not support usbmon raw data as is, so we have to parse these data in the pcap format. tcpdump is a good candidate to capture USB data from usbmon and generate pcap traces
前提条件,是需要最新的tcpdump工具才行,有编译好的,可以直接download下来push到板子上就可以使用。也有可以自己手动来编译的。这里就不详细来说了。
步骤:
1.eth0
2.usbmon1 (USB bus number 1)
3.usbmon2 (USB bus number 2)
4.usbmon3 (USB bus number 3)
5.any (Pseudo-device that captures on all interfaces)
6.lo有以上红色部分输出,说明你的tcpdump已经安装下,可以正常使用
上个图参考下,打开后是什么样子: