Create a core dump when running a program with sudo?

Question

Cores apparently are not dumped when the using sudo despite ulimit -c being set to unlimited. Is there any way around this?

Answer 1

sudo will reset the core dump settings, like it does for a lot of other environment state. You can run the program via a helper that first enables core dumps and then runs the program. Create for example a wrapper /usr/local/bin/coredump and then chmod +x:

$ cat /usr/local/bin/coredump

#!/bin/sh
ulimit -c unlimited
exec "$@"

Then

sudo /usr/local/bin/coredump /your/crashing/program

Answer 2

Since sudo 1.9.11, coredumps are explicitly disabled by default, as per the man 5 sudoers manual and this github comment confirming it. Which means that whatever settings you have for ulimit -c in your shell, or anything in /etc/limits.conf, /etc/security/limits.conf and /etc/login.defs are completely overridden by sudo: ie.

$ ulimit -c
134
$ sudo -u user -- bash -c "ulimit -c"
0

I use this line Defaults rlimit_core=infinity in /etc/sudoers file (or similar, eg. /etc/sudoers.d/90-coredumpsize) to have sudo do the equivalent of ulimit -c unlimited while inside sudo.

$ sudo -u user -- bash -c "ulimit -c"
unlimited

But still heed the 2 caveats from Catskul's (accepted)answer!

Answer 3

It seems it can be done using the -s option like:

sudo -s "ulimit -c unlimited; ./segfaultProg"

However 2 caveats:

1. You may need to set the suid_dumpable parameter with sysctl -w kernel.suid_dumpable=2
2. You may need to move an old core out of the way. Apparently there are special rules where it may refuse to write a core if the suid bit is set, and there's already a core there.

See the following for details:

http://www.randombugs.com/linux/core-dumps-linux.html