Ticket History #1011: fix for the known utmpx bug described in krb5-1.2.2/README

From aswab@panda.isbu.digex.net Mon Nov 5 19:35:42 2001
Received: from fort-point-station.mit.edu (FORT-POINT-STATION.MIT.EDU [18.72.0.53])
by rt-11.mit.edu (8.9.3/8.9.3) with ESMTP id TAA12242
for <bugs@RT-11.mit.edu>; Mon, 5 Nov 2001 19:35:42 -0500 (EST)
Received: from panda.isbu.digex.net (panda.isbu.digex.net [164.109.8.60])
by fort-point-station.mit.edu (8.9.2/8.9.2) with ESMTP id TAA29894
for <krb5-bugs@mit.edu>; Mon, 5 Nov 2001 19:35:41 -0500 (EST)
Received: (from aswab@localhost)
by panda.isbu.digex.net (8.10.2+Sun/8.10.2) id fA60ZBs19687;
Mon, 5 Nov 2001 19:35:11 -0500 (EST)
Message-Id: <200111060035.fA60ZBs19687@panda.isbu.digex.net>
Date: Mon, 5 Nov 2001 19:35:11 -0500 (EST)
From: Alex.Swab@digex.com
Reply-To: Alex.Swab@digex.com
To: krb5-bugs@mit.edu
Subject: patch to fix utmpx updates on Solaris 8 for krb5-1.2.2 update_utmp.c
X-Send-Pr-Version: 3.99

Digex, Inc.
sparc, Solaris 8
System: SunOS csgate.corp.digex.com 5.8 Generic_108528-09 sun4u sparc SUNW,Ultra-60
Architecture: sun4

The utmpx bug is known and documented in the krb5-1.2.2/README.
The utmpx filename becomes littered with random characters when Kerberos
programs call the pty_update_utmp function. On Solaris 8 sparc, the
littered filename becomes /var/adm/utmp*x where '*' seems to be a random
number of random characters. A new file is created with a different
littered name and contains a single utmpx entry each time the
pty_update_utmp function is called. The 'who' command on Solaris 8
reads the /var/adm/utmpx file by default, so when pty_update_utmp
creates an utmpx entry into a littered filename, 'who' will not show
the Kerberos login, however the 'last' command does show the login
because wtmpx updates seem to be working fine.
To test, for example, install Kerberos 1.2.2 or some earlier versions
onto Solaris 8 sparc and setup klogind server to run from inetd, then
use Kerberos rlogin from a remote machine to login to the klogind.
I'm using the following line in the /etc/inet/inetd.conf for klogind:

eklogin stream tcp nowait root /usr/local/sbin/klogind klogind -5 -c -e -w ip

The results for me is that the user can login and function fine,
but the utmpx file name is littered as described above.
I'm including a patch that fixes the utmpx problem on Solaris 8 sparc.
I haven't tested the patched code on other platforms, so I'm not sure
if it won't break another platform. I left most of the code as-is
by still first populating an utmp structure when utmpx is available.
However, I setup preprocessor directives to avoid calling most of the
utmp functions (utmpname, setutent, pututline, and endutent) when
HAVE_SETUTXENT is defined. As original, the code still copies the utmp
structure 'ent' to utmpx structure 'utx' with the getutmpx function
else does the HP-UX/DEC workaround. I moved the setutxent call from
before the getutmpx down to after the utmpx structure is complete just
before the pututxline call. I addeded a utmpxname call just before the
new setutxent and gave it an argument of the preprocessed UTMPX_FILE.

Here is the patch:


*** DIST/krb5-1.2.2/src/util/pty/update_utmp.c Wed Feb 28 17:08:33 2001
--- PATCHED/krb5-1.2.2/src/util/pty/update_utmp.c Mon Nov 5 15:08:10 2001
***************
*** 112,119 ****
--- 112,122 ----

#ifdef HAVE_SETUTENT

+ #ifndef HAVE_SETUTXENT
utmpname(UTMP_FILE);
setutent();
+ #endif
+
/* If we need to preserve the user name in the wtmp structure and
* Our flags tell us we can obtain it from the utmp and we succeed in
* obtaining it, we then save the utmp structure we obtain, write
***************
*** 131,141 ****
}
#endif

pututline(&ent);
endutent();

#ifdef HAVE_SETUTXENT
! setutxent();
#ifdef HAVE_GETUTMPX
getutmpx(&ent, &utx);
#else
--- 134,146 ----
}
#endif

+ #ifndef HAVE_SETUTXENT
pututline(&ent);
endutent();
+ #endif

#ifdef HAVE_SETUTXENT
!
#ifdef HAVE_GETUTMPX
getutmpx(&ent, &utx);
#else
***************
*** 163,168 ****
--- 168,175 ----
strncpy(utx.ut_host, host, sizeof(utx.ut_host));
else
utx.ut_host[0] = 0;
+ utmpxname(UTMPX_FILE);
+ setutxent();
pututxline(&utx);
endutxent();
#endif /* HAVE_SETUTXENT */