Error inserting module on linux 6.0.6

[c-nixon]

I get the following error in dmesg while trying out drawbridge from the latest master (commit 99376d4aea) on Arch Linux using the distro provided 6.0.6 package.

Command:

insmod drawbridge.ko ports=22,445 

dmesg output:

[-] Could not attach bpf zero filter to socket -12 
[-] drawbridge: Unable to setup child thread

I added a few printk's and it seems like the failure is coming from the refcount check in db_sk_filter_charge.

Is there anything I can do to help debug?

[landhb]

@c-nixon Thanks for the report.

Just curious, what value to you have for:

sudo sysctl net.core.optmem_max

Since that's the value that ends up checked here:

https://github.com/landhb/DrawBridge/blob/master/module/src/sk_filter.c#L70

More information on the configuration value:

https://stackoverflow.com/questions/47723793/in-linux-how-do-i-determine-optimal-value-of-optmem-max

If increasing that value doesn't work we could try running under gdb with nixmodule to see where it's failing.

[landhb]

Didn't have my coffee this morning, just noticing you said it was from the refcount_inc_not_zero. That is more confusing haha. I'll try to take a look

[landhb]

@c-nixon I think https://github.com/landhb/DrawBridge/commit/5386fb917408c2cac2cf9f18382d1f5f4ffaa183 should do it.

Please let me know if that works. Thanks!

[c-nixon]

Success! Thanks for the help!

# uname -r
6.0.6-arch1-2-01033-g2eddb2cf20dd
# insmod drawbridge.ko ports=22,445
# dmesg -t | tail -n1
[+] drawbridge: Loaded module into kernel - monitoring 2 port(s)