Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!xanth!cs.odu.edu!tadguy
From: tadguy@cs.odu.edu (Tad Guy)
Newsgroups: comp.unix.wizards
Subject: Re: anonymous ftp, and chroot
Summary: connecting unix datagram sockets works in 4.3BSD
Message-ID: <6840@xanth.cs.odu.edu>
Date: 14 Dec 88 14:30:52 GMT
Sender: news@xanth.cs.odu.edu
Reply-To: tadguy@cs.odu.edu (Tad Guy)
Organization: Old Dominion University, Norfolk, VA
Lines: 63
Supersedes: <6834@xanth.cs.odu.edu>

[ My apologies if you've seen this article more than once.  I keep
finding errors in it and keep superseding it.  What a great feature... ]

In article <3024@watale.waterloo.edu>, daemon@watale.waterloo.edu writes:
>> [ describes how logging info from ftpd is lost after the chroot() ]

In article <1379@mcgill-vision.UUCP>, mouse@mcgill-vision (der Mouse) writes:
>That's a sendto(), which passes the address ("/dev/log") at the
>time of the sendto(), which is after the chroot.  And after the chroot,
>there is no /dev/log.
> ...
>What we need is a syslogd that allows tcp connections, or perhaps a
>connect() on a datagram socket (I think this might work now).

Yes, this does work in 4.3BSD.

>The proper fix is to rework syslog() and syslogd so they can be made to
>work even after the client chroot()s.  This is probably beyond most
>people.  I don't see any simple fix.

What I did was give ftpd its own copy of syslog.c, which I modified to
connect() the datagram socket to "/dev/log" at the time of openlog()
if LOG_NDELAY was specified, then just use send().  Don't forget to
add LOG_NDELAY to the openlog() call in ftpd.c.  A more generic
solution is needed, but this works fine for ftpd.

My diffs (your line numbers may vary):

*** /usr/src/lib/libc/gen/syslog.c	Wed May  7 18:18:50 1986
--- syslog.c	Tue Dec  6 20:02:27 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 ****
--- 167,173 ----
  	strncpy(SyslogAddr.sa_data, logname, sizeof SyslogAddr.sa_data);
  	if (LogStat & LOG_NDELAY) {
  		LogFile = socket(AF_UNIX, SOCK_DGRAM, 0);
+ 		connect(LogFile, &SyslogAddr, sizeof SyslogAddr);
  		fcntl(LogFile, F_SETFD, 1);
  	}
  }

-- 
Tad Guy              Comp Sci, Old Dominion University, Norfolk, VA  23529-0162
tadguy@cs.odu.edu    tadguy@xanth.cs.odu.edu [128.82.8.1]     tadguy@xanth.uucp

"Think twice before speaking, but don't say `think think click click'."
                                                            -- John Owens