4aaf05d72e
Some distributions, notably Fedora, have the following order of nsswitch
modules by default:
passwd: sss files
group: sss files
The advantage of serving local users through SSSD is that the nss_sss
module has a fast mmapped-cache that speeds up NSS lookups compared to
accessing the disk an opening the files on each NSS request.
Traditionally, this has been done with the help of nscd, but using nscd
in parallel with sssd is cumbersome, as both SSSD and nscd use their own
independent caching, so using nscd in setups where sssd is also serving
users from some remote domain (LDAP, AD, ...) can result in a bit of
unpredictability.
More details about why Fedora chose to use sss before files can be found
on e.g.:
https://fedoraproject.org//wiki/Changes/SSSDCacheForLocalUsers
or:
https://docs.pagure.org/SSSD.sssd/design_pages/files_provider.html
Now, even though sssd watches the passwd and group files with the help
of inotify, there can still be a small window where someone requests a
user or a group, finds that it doesn't exist, adds the entry and checks
again. Without some support in shadow-utils that would explicitly drop
the sssd caches, the inotify watch can fire a little late, so a
combination of commands like this:
getent passwd user || useradd user; getent passwd user
can result in the second getent passwd not finding the newly added user
as the racy behaviour might still return the cached negative hit from
the first getent passwd.
This patch more or less copies the already existing support that
shadow-utils had for dropping nscd caches, except using the "sss_cache"
tool that sssd ships.
Shadow SITES ============ Homepage http://pkg-shadow.alioth.debian.org/ FTP site ftp://pkg-shadow.alioth.debian.org/pub/pkg-shadow SVN repository anonymous read only access: svn://svn.debian.org/pkg-shadow/upstream SVN web interface http://svn.debian.org/wsvn/pkg-shadow/upstream or http://svn.debian.org/viewsvn/pkg-shadow/upstream Mailing lists for general discuss: pkg-shadow-devel@lists.alioth.debian.org commit list: pkg-shadow-commits@lists.alioth.debian.org Mailing lists subscription http://lists.alioth.debian.org/mailman/listinfo/pkg-shadow-devel http://lists.alioth.debian.org/mailman/listinfo/pkg-shadow-commits Mailing lists archives: http://lists.alioth.debian.org/pipermail/pkg-shadow-devel/ http://lists.alioth.debian.org/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 http://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> 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> 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> 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> 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)