From 39b375bd406e8b4605d00eed64114bd273931051 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 28 Nov 2012 14:26:58 +0100 Subject: [PATCH] docs: KnownIssues: document VLAN filtering Signed-off-by: Daniel Borkmann --- Documentation/KnownIssues | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/Documentation/KnownIssues b/Documentation/KnownIssues index 0665adb1..458e9817 100644 --- a/Documentation/KnownIssues +++ b/Documentation/KnownIssues @@ -47,6 +47,31 @@ A: Yes and no. The way how VLAN headers are handled in PF_PACKET sockets by the [1] http://lkml.indiana.edu/hypermail/linux/kernel/0710.3/3816.html + Update (28.11.2012): the Linux kernel and also bpfc has built-in support + for VLAN filtering, even though tags might not be visible in the payload + itself as reported here. However, the filtering for VLANs works reliable. + bpfc example for filtering for any tags ("VLAN tag is present"): + + _main: + ld #vlanp + jgt #0, keep, drop + keep: + ret #-1 + drop: + ret #0 + + Filtering for a particular VLAN tag: + + _main: + ld #vlant + jeq #10, keep, drop + keep: + ret #-1 + drop: + ret #0 + + where '10' is VLAN ID 10 in this example. + Q: When I start trafgen, my kernel crashes! What is happening? A: We have fixed this ``bug'' in the Linux kernel under commit 7f5c3e3a80e6654cf48dfba7cf94f88c6b505467 (http://bit.ly/PcH5Nd). Either -- 2.11.4.GIT