Big Sur "No tun devices found, trying utun. segmentation fault"

[andrewmunsell]

I'm trying to run iodine as follows:

sudo ./iodine -f -P password t1.mydomain.com

However, I get:

No tun devices found, trying utun
[1]    4469 segmentation fault sudo ./iodine -f -P password t1.mydomain.com

This happens regardless of specifying -d=utun0 (all the way through utun7, only utun0 through utun6 are shown on my ifconfig). There aren't any /dev/tunX or /dev/utunX devices showing in /dev, though I am not sure whether they should be or not.

This is using the latest master commit as of May 12th 2021 on Mac OS X Big Sur 11.3.

Tunnelblick seems to be able to create a new utun7 no problem when it creates an OVPN connection.

[andrewmunsell]

I was able to get this to work with specifying -d utun7, without the equals

[yarrick]

Since a904570 it is supposed to try utun automatically. Can you try running it inside gdb and try to get a stack trace or core dump?

Try this:

$ sudo gdb ./iodine
(gdb) r -f -P password t1.mydomain.com

then a stack trace can be shown by typing where once it stops on the segfault. It is probably some missing error handling in open_utun() if I have to guess.

[andrewmunsell]

Result:

➜  bin sudo gdb ./iodine
Password:
GNU gdb (GDB) 10.2
...
Reading symbols from ./iodine...
(gdb) r -f -P password t1.mydomain.com
Starting program: /Users/andrew/Downloads/iodine-master/bin/iodine -f -P password t1.mydomainc.om
[New Thread 0x2003 of process 13668]
[New Thread 0x2503 of process 13668]
warning: unhandled dyld version (17)
No tun devices found, trying utun

Thread 2 received signal SIGSEGV, Segmentation fault.
0x0000000100003241 in utun_unit (dev=0x0) at tun.c:344
344		while (*unit_str != '\0' && !isdigit(*unit_str))

[yarrick]

Thanks, I spotted an error causing NULL to be passed to the utun setup. Can you try again with the latest code?

It will probably work better now but might log a bit while testing devices in use.

[andrewmunsell]

LGTM, works great now:

➜  bin sudo ./iodine -f -P password t1.mydomain.com
No tun devices found, trying utun
iodine: open_utun: connect: Resource busy
iodine: open_utun: connect: Resource busy
iodine: open_utun: connect: Resource busy
iodine: open_utun: connect: Resource busy
iodine: open_utun: connect: Resource busy
iodine: open_utun: connect: Resource busy
iodine: open_utun: connect: Resource busy
Opened utun7
Opened IPv4 UDP socket
...

[yarrick]

Thanks for the quick test!