Date: Mon, 16 Jun 1997 09:15:11 -0700 (PDT) From: Dominic.Froud@dcs.qmw.ac.uk To: freebsd-gnats-submit@FreeBSD.ORG Subject: misc/3883: @+netgroup entries break +NIS-user entries in passwd when using getpwent(3) Message-ID: <199706161615.JAA13613@hub.freebsd.org> Resent-Message-ID: <199706161620.JAA13803@hub.freebsd.org>
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>Number: 3883
>Category: misc
>Synopsis: @+netgroup entries break +NIS-user entries in passwd when using getpwent(3)
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jun 16 09:20:01 PDT 1997
>Last-Modified:
>Originator: Dominic Froud
>Organization:
Queen Mary & Westfield College
>Release: 2.2-STABLE
>Environment:
FreeBSD iron.dcs.qmw.ac.uk 2.2-STABLE FreeBSD 2.2-STABLE #1: Fri Jun 6 09:49:02 GMT 1997 md@iron.dcs.qmw.ac.uk:/usr/src/sys/compile/IRON i386
>Description:
When getpwent(3) encounters a +@netgroup entry in the /etc/passwd file,
it sets a flag (_pw_stepping_yp) to 1. This short-circuits successive
calls to getpwent() so that they jump to 'grabbing the next NIS entry'.
This flag isn't reset when all the netgroup members have been retrieved.
This causes a problem when another NIS-style entry (specifically named
NIS users) is mentioned because getpwent() is permanently locked to
retrieving the same user entry (and hence loops based around getpwent()
never return).
>How-To-Repeat:
Add lines in the following format to the end of /etc/passwd (using vipw):
+@netgroup-that-exists:::::::::
+NIS-user-that-exists:::::::::
+:::::::::/bin/true
Try: finger NIS-added-user-not-included-above
finger(1) will hang and a kernel trace will show
a NIS lookup in passwd.byname for NIS-user-that-exists followed by
a successful return of their passwd entry.
After that, the trace is filled with nothing but gettimeofday(2) calls.
>Fix:
Non-rebuild workaround:
Place all +user entries before any +@netgroup entries in /etc/passwd
if possible. I don't think inserting a local user between the two
entries will work.
Software fix:
amend /usr/src/lib/libc/gen/getpwent.c as follows, and rebuild libc:
*** getpwent.c Mon Jun 16 17:04:57 1997
--- fixed-getpwent.c Mon Jun 16 16:36:17 1997
***************
*** 409,414 ****
--- 409,415 ----
endgrent();
latch = 0;
gr = NULL;
+ _pw_stepping_yp = 0; /* DOM */
return(0);
}
}
>Audit-Trail:
>Unformatted:
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