Hi all, I'm sorry for my poor English.
I am a member of Kondara Project, we are providing a Linux
distribution. I found bugs of the linux kernel version 2.2.14 through
our bug tracking system.
- What happen?
When you enable promiscuous mode using the tcpdump command
provided by us, the ifconfig command displays wrong status. We noticed
that this problem caused by the linux kernel.
- Description
We are providing ipv6-enabled tcpdump tool. This tcpdump(libpcap)
calls setsockopt() to enter promiscuous mode as below:
/* snip */
mr.mr_type = promisc ? PACKET_MR_PROMISC : PACKET_MR_ALLMULTI;
if (setsockopt(p->fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
(char *)&mr, sizeof(mr)) < 0) {
this setsockopt() call is handled in linux-2.2.14:
/* snip */
packet_dev_mc() net/packet/packet.c:892
dev_set_promiscuity() net/core/dev.c:1353
In the meanwhile, the original tcpdump calls ioctl() to enter
promiscuous mode as below:
/* snip */
ifr.ifr_flags |= IFF_PROMISC;
if (ioctl(p->fd, SIOCSIFFLAGS, &ifr) < 0 ) {
this ioctl() call is handled in linux-2.2.14:
/* snip */
dev_change_flags() net/core/dev.c:1396
dev_set_promiscuity() net/core/dev.c:1353
Thus, the dev_set_promiscuity() may be called by packet_dev_mc()
and dev_change_flags(), but the dev_change_flags() looks like
forgetting the existence of packet_dev_mc().
Concretely, the variable dev->gflags (which is concerned with
promiscuity settings) is changed on the out of dev_set_promiscuity(),
but then this variable is ignored in packet_dev_mc().
I checked kernel version 2.2.14, 2.2.15pre20, and 2.3.99pre6, but
this problem is not fixed yet.
- How to reproduce the bug
1. build tpcdump with ipv6 patch:
RPM packages:
http://www.kondara.org/rpm2html/TByName.html
tcpdump-3.4a6+ipv6-16k6.*.rpm
SRPM package:
http://www.kondara.org/ftplist.html
tcpdump-3.4a6+ipv6-16k6.nosrc.rpm
(it requires some sources)
Original Sources:
http://www.inner.net/pub/ipv6/tcpdump-3.4a6.tar.gz
http://www.inner.net/pub/ipv6/tcpdump-3.4a6+ipv6-1.diff.gz
http://www.inner.net/pub/ipv6/libpcap-0.4a6.tar.gz
http://www.inner.net/pub/ipv6/libpcap-0.4a6+ipv6-1.diff.gz
2. run tcpdump command; this means that the interface becomes
promiscuous mode.
3. run ifconfig command to check the interface's status.
"PROMISC" is NOT displayed...
- Patch
The followed patch is made for linux-2.2.15pre20. But it is
available for linux-2.2.14 and linux-2.3.99pre6 too.
- Check my patch, please!
Check my patch, please!
Thanks.
---- cut here ---- cut here ---- cut here ---- cut here ----
begin 644 linux-2.2.15pre20-promisc.patch.gz
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M:9OL%>%RSG/._3T/JJI"0,+TIVHVS(9AKV-LZEJ($\V+8JPM\(^&)YBZKFNZ
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MHL'G_O1ZJ$"^$Q3)E/);EE)8/\R1RH+&]L[\`>F%J'UD.T&'+<BQGPRT_$HI
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end
---- cut here ---- cut here ---- cut here ---- cut here ----
--
Tatsuo Sekine:
[EMAIL PROTECTED] (private) ISOTERNET ASSOCIATION JAPAN
[EMAIL PROTECTED] (business) System Design & Research Inst. Co.,Ltd.
[EMAIL PROTECTED] (Kondara MNU/Linux) Kondara Project
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