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624d57c08c
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Tobias Stoeckmann 624d57c08c Improve child error handling 
Always set SIGCHLD handler to default, even if the caller of vipw has
set SIGCHLD to ignore. If SIGCHLD is ignored no zombie processes would
be created, which in turn could mean that kill is called with an already
recycled pid.

Proof of Concept:

1. Compile nochld:
 --
 #include <signal.h>
 #include <unistd.h>
 int main(void) {
 char *argv[] = { "vipw", NULL };
 signal(SIGCHLD, SIG_IGN);
 execvp("vipw", argv);
 return 1;
 }
 --
2. Run nochld
3. Suspend child vi, which suspends vipw too:
`kill -STOP childpid`
4. Kill vi:
`kill -9 childpid`
5. You can see with ps that childpid is no zombie but disappeared
6. Bring vipw back into foreground
`fg`

The kill call sends SIGCONT to "childpid" which in turn could have been
already recycled for another process.

This is definitely not a vulnerability. It would take super user
operations, at which point an attacker would have already elevated
permissions.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
2021-11-14 12:01:32 +01:00
.github/workflows initial github actions attempt 2021-10-15 16:21:19 -05:00
contrib fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
doc fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
docs fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
etc fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
lib Add missing chmod() 2021-10-28 11:16:59 +11:00
libmisc Handle malformed lines in hushlogins file. 2021-10-29 19:50:38 +02:00
libsubid Fixes the linking issues when libsubid is static and linked to 2021-10-27 20:14:42 +11:00
man manpages: fix 'File Formats and Conversions" 2021-10-15 16:28:12 -05:00
po updated Dutch translation 2021-09-13 21:05:45 +02:00
src Improve child error handling 2021-11-14 12:01:32 +01:00
tests fix some shellcheck-identified issues in scripts 2021-08-18 18:21:06 +00:00
.gitignore ignore config.cache & dist files 2016-12-05 15:48:10 -05:00
.travis.yml subids: support nsswitch 2021-04-16 21:02:37 -05:00
acinclude.m4 [svn-upgrade] Integrating new upstream version, shadow (4.0.13) 2007-10-07 11:47:01 +00:00
autogen.sh Add Christian Brauner to SECURITY.md 2021-10-25 14:26:37 -05:00
ChangeLog fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
configure.ac Fix parentheses in configure.ac 2021-09-22 09:42:15 -07:00
COPYING fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
Makefile.am fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
NEWS fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00
README README: Use HTTPS URLs where possible 2021-09-12 12:06:02 +02:00
SECURITY.md Add Christian Brauner to SECURITY.md 2021-10-25 14:26:37 -05:00
shadow.spec.in * shadow.spec.in: Fix the source (new FTP). 2008-08-31 17:30:45 +00:00
TODO fix spelling and unify whitespace 2021-08-18 18:06:02 +00:00

README 

Shadow SITES
============

Homepage
	https://github.com/shadow-maint/shadow

Issue tracker
	https://github.com/shadow-maint/shadow/issues

Releases
	https://github.com/shadow-maint/shadow/releases

Mailing lists
	for general discuss: pkg-shadow-devel@alioth-lists.debian.net
	commit list: pkg-shadow-commits@alioth-lists.debian.net

Mailing lists subscription
	https://alioth-lists.debian.net/mailman/listinfo/pkg-shadow-devel
	https://alioth-lists.debian.net/mailman/listinfo/pkg-shadow-commits

Mailing lists archives:
	https://alioth-lists.debian.net/pipermail/pkg-shadow-devel/
	https://alioth-lists.debian.net/pipermail/pkg-shadow-commits/

S/Key support:
	Shadow can be built with S/Key support using the S/Key package from:

	http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libskey/
	or
	https://gentoo.osuosl.org/distfiles/skey-1.1.5.tar.bz2

Authors and contributors
========================

Thanks to at least the following people for sending patches, bug
reports and various comments.  This list may be incomplete, I received
a lot of mail...


Adam Rudnicki <adam@v-lo.krakow.pl>
Alan Curry <pacman@tardis.mars.net>
Aleksa Sarai <cyphar@cyphar.com>
Alexander O. Yuriev <alex@bach.cis.temple.edu>
Algis Rudys <arudys@rice.edu>
Andreas Jaeger <aj@arthur.rhein-neckar.de>
Aniello Del Sorbo <anidel@edu-gw.dia.unisa.it>
Anton Gluck <gluc@midway.uchicago.edu>
Arkadiusz Miskiewicz <misiek@pld.org.pl>
Ben Collins <bcollins@debian.org>
Brian R. Gaeke <brg@dgate.org>
Calle Karlsson <ckn@kash.se>
Chip Rosenthal <chip@unicom.com>
Chris Evans <lady0110@sable.ox.ac.uk>
Chris Lamb <chris@chris-lamb.co.uk>
Cristian Gafton <gafton@sorosis.ro>
Dan Walsh <dwalsh@redhat.com>
Darcy Boese <possum@chardonnay.niagara.com>
Dave Hagewood <admin@arrowweb.com>
David A. Holland <dholland@hcs.harvard.edu>
David Frey <David.Frey@lugs.ch>
Ed Carp <ecarp@netcom.com>
Ed Neville <ed@s5h.net>
Eric W. Biederman" <ebiederm@xmission.com>
Floody <flood@evcom.net>
Frank Denis <j@4u.net>
George Kraft IV <gk4@us.ibm.com>
Greg Mortensen <loki@world.std.com>
Guido van Rooij
Guy Maor <maor@debian.org>
Hrvoje Dogan <hdogan@bjesomar.srce.hr>
Jakub Hrozek <jhrozek@redhat.com>
Janos Farkas <chexum@bankinf.banki.hu>
Jason Franklin <jason.franklin@quoininc.com>
Jay Soffian <jay@lw.net>
Jesse Thilo <Jesse.Thilo@pobox.com>
Joey Hess <joey@kite.ml.org>
John Adelsberger <jja@umr.edu>
Jonathan Hankins <jhankins@mailserv.homewood.k12.al.us>
Jon Lewis <jlewis@lewis.org>
Joshua Cowan <jcowan@hermit.reslife.okstate.edu>
Judd Bourgeois <shagboy@bluesky.net>
Juergen Heinzl <unicorn@noris.net>
Juha Virtanen <jiivee@iki.fi>
Julian Pidancet <julian.pidancet@gmail.com>
Julianne Frances Haugh <jockgrrl@ix.netcom.com>
Leonard N. Zubkoff <lnz@dandelion.com>
Luca Berra <bluca@www.polimi.it>
Lukáš Kuklínek <lkukline@redhat.com>
Lutz Schwalowsky <schwalow@mineralogie.uni-hamburg.de>
Marc Ewing <marc@redhat.com>
Martin Bene <mb@sime.com>
Martin Mares <mj@gts.cz>
Michael Meskes <meskes@topsystem.de>
Michael Talbot-Wilson <mike@calypso.bns.com.au>
Michael Vetter <jubalh@iodoru.org>
Mike Frysinger <vapier@gentoo.org>
Mike Pakovic <mpakovic@users.southeast.net>
Nicolas François <nicolas.francois@centraliens.net>
Nikos Mavroyanopoulos <nmav@i-net.paiko.gr>
Pavel Machek <pavel@bug.ucw.cz>
Peter Vrabec <pvrabec@redhat.com>
Phillip Street
Rafał Maszkowski <rzm@icm.edu.pl>
Rani Chouha <ranibey@smartec.com>
Sami Kerola <kerolasa@rocketmail.com>
Scott Garman <scott.a.garman@intel.com>
Sebastian Rick Rijkers <srrijkers@gmail.com>
Seraphim Mellos <mellos@ceid.upatras.gr>
Shane Watts <shane@nexus.mlckew.edu.au>
Steve M. Robbins <steve@nyongwa.montreal.qc.ca>
Thorsten Kukuk <kukuk@suse.de>
Tim Hockin <thockin@eagle.ais.net>
Timo Karjalainen <timok@iki.fi>
Ulisses Alonso Camaro <ulisses@pusa.eleinf.uv.es>
Werner Fink <werner@suse.de>

Maintainers
===========

Tomasz Kłoczko <kloczek@pld.org.pl> (2000-2007)
Nicolas François <nicolas.francois@centraliens.net> (2007-2014)
Serge E. Hallyn <serge@hallyn.com> (2014-now)
Christian Brauner <christian@brauner.io> (2019-now)