Bug 14456
| Summary: | usbmon: binary interface reports URB data wrongly | ||
|---|---|---|---|
| Product: | Drivers | Reporter: | Márton Németh (nm127) |
| Component: | USB | Assignee: | Pete Zaitcev (zaitcev) |
| Status: | RESOLVED INVALID | ||
| Severity: | normal | CC: | zaitcev |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 2.6.32-rc5 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
| Attachments: |
URBs captured through the text interface
URBs captured through binary interface caputre data saved from Wireshark Patch for Wireshark to dump URBs on stdout Linux kernel configuration 2.6.32-rc5 Some debug messages for usbmon binary interface Repeated with wireshark the debug messages from dmesg Some more debug messages Patch for Wireshark to dump URBs on stdout (typo corrected) strace verbose output while running Wireshark stdout of the previous Wireshark capture the bad capture file saved from Wireshark |
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Created attachment 23497 [details]
URBs captured through binary interface
Created attachment 23498 [details]
caputre data saved from Wireshark
Created attachment 23499 [details]
Patch for Wireshark to dump URBs on stdout
Created attachment 23500 [details]
Linux kernel configuration 2.6.32-rc5
Created attachment 23501 [details]
Some debug messages for usbmon binary interface
Created attachment 23502 [details]
Repeated with wireshark
Created attachment 23503 [details] the debug messages from dmesg The attachment 23502 [details] and this one was created at the same time. On Fri, Oct 23, 2009 at 07:33:48AM +0000, bugzilla-daemon@bugzilla.kernel.org wrote: > http://bugzilla.kernel.org/show_bug.cgi?id=14456 > > Summary: usbmon: binary interface reports URB data wrongly Can you please post this information on the linux-usb@vger.kernel.org mailing list so that the linux usb developers can comment on it? Created attachment 23511 [details]
Some more debug messages
Note that there is one additional layer between kernel and Wireshark: this is libpcap from http://www.tcpdump.org/ . Created attachment 23512 [details]
Patch for Wireshark to dump URBs on stdout (typo corrected)
Created attachment 23519 [details] strace verbose output while running Wireshark I checked usbmon from http://people.redhat.com/zaitcev/linux/usbmon-5.4.tar.gz which works correctly without debugfs and usbfs mounted. The packages are shown correctly. Wireshark can only start capturing if usbfs is mounted, debugfs is not necessary. I run Wireshark with strace, the output is attached. The packages are captured wrongly. You might also want to see attachment 23511 [details] which is created from dmesg with a patched usbmon kernel module. On that log the function calls are also shown. (In reply to comment #12) > You might also want to see attachment 23511 [details] which is created from > dmesg with a patched usbmon kernel module. On that log the function calls are > also shown. I mean attachment 23503 [details]... Created attachment 23520 [details]
stdout of the previous Wireshark capture
Created attachment 23521 [details]
the bad capture file saved from Wireshark
Thanks, that helps a lot.
So, Wireshark (libpcap) does this:
4849 open("/dev/usbmon1", O_RDONLY|O_LARGEFILE) = 3
.........
4849 select(4, [3], NULL, NULL, {0, 250000} <unfinished ...>
4849 <... select resumed> ) = 1 (in [3], left {0, 241497})
4849 ioctl(3, 0xc00c9207, 0xbfc161a0) = 0 <---- 32 bit MON_IOCX_MFETCH
4849 ioctl(3, 0x9208, 0x1) = 1 <---- MON_IOCH_MFLUSH
4849 time(NULL) = 1256456277
4849 select(4, [3], NULL, NULL, {0, 250000}) = 1 (in [3], left {0, 247121})
4849 ioctl(3, 0xc00c9207, 0xbfc161a0) = 0
4849 ioctl(3, 0x9208, 0x1) = 1
And usbmon(8) does this:
open("/dev/usbmon0", O_RDWR) = 3
ioctl(3, 0x4018920a, 0x7fff258c5c70) = 0 <---- MON_IOCX_GETX
write(1, "26092318 0.800486 S Ci:1:001:0 s "..., 58) = 58
ioctl(3, 0x4018920a, 0x7fff258c5c70) = 0
write(1, "26092318 0.800791 C Ci:1:001:0 0 "..., 46) = 46
It's one of:
- I never tested MFETCH implementation and it's buggy, or
- Paolo never tested his code for binary API and it's buggy, or
- Something bitrotted and Paolo's code stopped working
I see from the text output that it's a 32-bit kernel, so there are
no issues with the compat implementation.
Upgrading to libpcap git 339d28cefc11bbadaa92005b4f7b365f4732432c ("git clone git://bpf.tcpdump.org/libpcap") fixes the problem.
Thanks a lot. I already started writing tests but you pre-empted that. Let's close the bug. |
Created attachment 23496 [details] URBs captured through the text interface There is a difference in binary data what is reported through the text interface /sys/kernel/debug/usb/usbmon/1u and through /dev/usbmon1. The URB data is wrong on binary interface. How to reproduce: 1. modprobe -k usbmon 2. mount debugfs /sys/kernel/debug/ -t debugfs 3. Open two xterm windows: "A" and "B" 4. On "A" execute: cat /sys/kernel/debug/usb/usbmon/1u >usbmon_1u.txt 5. On "B" execute a patched version of Wireshark. Redirect stdout to usbmon_binary_wireshark.txt . The patch just prints out what Wireshark reads from /dev/usbmon1 in human readable form. The lines starting with pcap_read_linux_usb_pseudoheader() show the pseudoheader. Lines starting with libpcap_read_rec_data() show the URB packet data. 6. Start capturing in Wireshark on USB bus 1. 7. Plug in Genius NetScroll 110 USB mouse to USB bus 1. Current result: The URBs captured through text interface seems to be OK, the URBs captured on binary interface are bad. Expected result: The same URB data is read through the text interface and the binary interface.