Path: utzoo!mnetor!uunet!husc6!mit-eddie!ll-xn!ames!umd5!trantor.umd.edu!louie
From: louie@trantor.umd.edu (Louis A. Mamakos)
Newsgroups: comp.bugs.4bsd
Subject: syslog(3) uses sendto() rather than send() - interaction with chroot()
Message-ID: <2186@umd5.umd.edu>
Date: 11 Jan 88 21:39:50 GMT
Sender: ris@umd5.umd.edu
Reply-To: louie@trantor.umd.edu (Louis A. Mamakos)
Distribution: na
Organization: University of Maryland, College Park
Lines: 50
Keywords: chroot sendto send syslog
Index:	/usr/src/lib/libc/gen/syslog.c 4.3BSD


Description:
	The syslog(3) library routine uses sendto() to deliver a message to
the syslog daemon.  The daemon listens on the UNIX domain socket /dev/log.  If
the user process that is logging does a chroot() call, the /dev/log socket is
no longer visable, and logging no longer occurs.

Repeat-By:
	Add code to your FTP server that logs the names of files that are
transferred.  Note that when the user logs into the server with "anonymous",
logging no longer works because the server has done a chroot() to ~ftp.

Fix:

In openlog(), connect() to /dev/log.  Subsequently, use send() on the connected
socket rather than sendto().  User can now do an openlog() before any chroot().

*** /usr/src/lib/libc/gen/syslog.c	Wed May  7 18:18:50 1986
--- syslog.c	Mon Jan 11 15:51:22 1988
***************
*** 120,126 ****
  		c = MAXLINE;
  
  	/* output the message to the local logger */
! 	if (sendto(LogFile, outline, c, 0, &SyslogAddr, sizeof SyslogAddr) >= 0)
  		return;
  	if (!(LogStat & LOG_CONS))
  		return;
--- 120,126 ----
  		c = MAXLINE;
  
  	/* output the message to the local logger */
! 	if (send(LogFile, outline, c, 0) >= 0)
  		return;
  	if (!(LogStat & LOG_CONS))
  		return;
***************
*** 167,172 ****
--- 167,176 ----
  	strncpy(SyslogAddr.sa_data, logname, sizeof SyslogAddr.sa_data);
  	if (LogStat & LOG_NDELAY) {
  		LogFile = socket(AF_UNIX, SOCK_DGRAM, 0);
+ 		if (connect(LogFile, &SyslogAddr, sizeof SyslogAddr) < 0)
+ 			return;
  		fcntl(LogFile, F_SETFD, 1);
  	}
  }


Louis A. Mamakos  WA3YMH    Internet: louie@TRANTOR.UMD.EDU
University of Maryland, Computer Science Center - Systems Programming