Re: bin/55278: inetd dies while starting Samba smbd

[RVP <rvp%SDF.ORG@localhost>]

The following reply was made to PR bin/55278; it has been noted by GNATS.

From: RVP <rvp%SDF.ORG@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: bin/55278: inetd dies while starting Samba smbd
Date: Mon, 6 Nov 2023 23:11:26 +0000 (UTC)

 On Mon, 12 Apr 2021, Hauke Fath wrote:
 
 > 0x0000760f81244bba in _sys___kevent50 () from /usr/lib/libc.so.12
 > (gdb) cont
 > Continuing.
 > [New process 25550]
 >
 > Thread 2 received signal SIGTERM, Terminated.
 >
 
 smbd registers a cleanup function via atexit() in main() called killkids()
 which does[1]:
 
 ```
   133	if(am_parent) kill(0,SIGTERM);
 ```
 
 [1]: https://gitlab.com/samba-team/samba/-/blob/master/source3/smbd/server.c?ref_type=heads
 
 When running in the foreground (-d) inetd does setsid(), but, it _doesn't_
 do this when running in the background, And, since smbd is run as root, inetd
 gets the SIGTERM sent to the process-group by samba to kill its children.
 
 A simple reproducer is this "server":
 
 ```
 #include <signal.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 int
 main(void)
 {
  	sleep(5);
  	kill(0, SIGTERM);
  	exit(EXIT_FAILURE);
 }
 ```
 
 which you can (temporarily) run in /etc/inetd.conf instead of smbd:
 
 ```
 netbios-ssn     stream  tcp     nowait  root    /tmp/foo foo
 ```
 
 It should kill inetd just as effectively.
 
 This should fix the issue:
 
 ```
 diff -urN a/src/usr.sbin/inetd/inetd.c b/src/usr.sbin/inetd/inetd.c
 --- a/src/usr.sbin/inetd/inetd.c	2022-08-10 08:37:53.000000000 +0000
 +++ b/src/usr.sbin/inetd/inetd.c	2023-11-06 22:43:54.650415000 +0000
 @@ -499,9 +499,9 @@
 
   			for (n = 0; n < __arraycount(my_signals); n++)
   				(void) signal(my_signals[n], SIG_DFL);
 -			/* Don't put services in terminal session */
 -			if (foreground)
 -				setsid();
 +			/* Always create new process-group: PR #55278 */
 +			if (setsid() == -1)
 +				syslog(LOG_ERR, "setsid: %m");
   		}
   	}
   	if (pid == 0) {
 ```
 
 Should eventually be pulled-up to -8, -9, -10.
 
 -RVP