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Created attachment 524467[details]
kernel module that dumps IP packets at NF_INET_PRE_ROUTING hook
Description of problem:
Packets captured in NF_INET_PRE_ROUTING, or NF_INET_LOCAL_INPUT hook over a virtio NIC shows rubbish starting at offset 0x80 from raw-Ethernet.
Version-Release number of selected component (if applicable):
QEMU emulator version 0.14.1 (qemu-kvm-0.14.1) in host.
centos6.0 (kernel 2.6.32-71.29.1.el6.x86_64) in VM
and
scientific-linux-6.1 (kernel 2.6.32-131.12.1.el6.x86_64) in VM
How reproducible:
To show this, I made a simple kernel module with netfilter hook for nfho.hooknum = NF_INET_PRE_ROUTING; - runned it and tested with pings (dump the ping packet). You can download the sources of this module here: http://dl.free.fr/gXETj3izM (or attached to this report)
Steps to Reproduce:
1.Use a VM running centos6 (or sl-6.1) with the latest kernel. Have 2 NICs types: e1000 and virtio.
2. Take the attached module and compile it (run ./build.sh) => get mymodule.ko
3. insmod the compiled kernel module (./reload.sh) => see mymodule in lsmod
4. from another host, ping each of the NIC of the VM that has mymodule running using: ping x.x.x.x -p AA -s 1000 (filled with 0xAA 1000bytes).
Actual results:
When pinging the virtio NIC:
Dump ICMP packet, size of: 1028
45 00 04 04 00 00 40 00 40 01 bf 07 c0 a8 7b 01 E.....@.@.....{.
c0 a8 7b 9f 08 00 f9 ce 69 8a 00 05 d2 b1 5b 4e ..{.....i.....[N
00 00 00 00 5d a1 09 00 00 00 00 00 aa aa aa aa ....]...........
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 01 c0 0c 00 10 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
60 86 c3 00 00 ea ff ff aa 00 00 00 74 03 00 00 `...........t...
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 76 61 68 69 2e 63 6f 00 00 00 00 00 00 00 00 .vahi
Expected results:
When pinging the e1000 NIC:
Dump ICMP packet, size of: 1028
45 00 04 04 00 00 40 00 40 01 0b 0d xx xx xx xx E.....@.@....d..
yy yy yy yy 08 00 73 10 c1 7e 00 1c 83 b1 5b 4e .d....s.......[N
00 00 00 00 d8 54 0c 00 00 00 00 00 aa aa aa aa .....T..........
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................
aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa .....
Additional info:
This problem didn't occur with older kernels (2.6.18-centos, or vanilla 2.6.25)!
(In reply to comment #2)
> This is not the place to report centos issues and the above versions are too
> old in respect to rhel6 series.
Unfortunately, it's not a CentOS issue: it's about virtio and latest linux kernels. Besides Centos and ScientificLinux, I tried it also on the latest Debian and ubuntu - same problems. Just try the code I posted in your favorite linux - and you'll see the problem.
Kind regards,
Mihai