[PATCH] netlink: report why a packet is bad
ijackson at chiark.greenend.org.uk
Wed Dec 28 00:46:59 GMT 2011
Earlier today I found that my VPN to my netbook was broken. On
investigation with strace I found secnet blocked on write to fd 12.
This fd appeared to be one of its fds to the userv ipif farm. I ran
out of time before I was able to strace the corresponding copy of cat
and determine which of the userv client's fds it corresponded to. But
I think the fd must have been the one for transferring packet data
from secnet to the kernel. The only reasonable explanation for
blocking on that fd would seem to be a kernel bug in the slip line
discipline. I'm aware of bugs in the slip line discipline - I've seen
regular kernel oopses in slattach in some kernels, at least as
recently as lenny.
I have an experimental but as-yet-unreleased version of userv ipif
which uses tun rather than slattach. I will try to prioritise
(a) releasing it and (b) installing it on chiark.
While I'm on these kind of subjects I noticed that the stderr output
from userv ipif doesn't seem to end up in ~secnet/live/log.
More information about the sgo-software-discuss