Created attachment 1512763 [details]
Patch to set cloexec flags on upsmon and upssched file descriptors

Description of problem:
I have upssched (spawned from upsmon) setup to call a script that sends
mail when an interesting even occurs.  I was getting SELinux violations with sendmail being denied read access to /etc/ups/upssched.conf... tracked down the problem to the configuration file descriptor being leaked to my script on fd4, and then read by sendmail.

I found that upsmon was leaking descriptors to upssched (which could be a user script instead), and upssched was leaking even more to it's spawned processes.

I've created a patch to add FD_CLOEXEC flags to all the files, pipes and sockets opened by upsmon and upssched so that the spawned processes only receive the normal stdio fds.

I've also submitted the patch upstream, so hopefully will be fixed in the next release.  But it does create very difficult to track down SELinux messages, so I figure it's worth submitting a bug here to fix those.

Version-Release number of selected component (if applicable):
nut-2.7.4-19

How reproducible:
Whenever upsmon spawns a NOTIFYCMD or upssched spawns a CMDSCRIPT

Steps to Reproduce:
1. Create a script, and set NOTIFYCMD or CMDSCRIPT to run it
2. Create an event that triggers the script.

Actual results:
Examine the output of ls -l /proc/$$/fd in the script and
see the leaked file descriptors - you could also run:
 echo test | mail -s test myemail@domain
 and sendmail (postfix version at least) will generate SELinux violations.

Expected results:
No leaked descriptors, no SELinux violations.

Additional info:
I've attached the patch I submitted upstream...I've tested it and it correctly eliminates the leaks.