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.
Otherwise our spw_next() will cause us to skip an entry.
Ideally we'd be able to do an swp_rewind(1), but I don't
see a helper for this.
Closes#60
Signed-off-by: Serge Hallyn <shallyn@cisco.com>
passwd, shadow, group, gshadow etc. can be managed via nss -
e.g. system default accounts can be specified using nss_altfiles,
rather than in /etc/. Thus despite having default accounts, these
files can be missing on disk and thus should be opened with O_CREATE
whenever they are attempted to be opened in O_RDWR modes.
annotations.
* src/pwconv.c, src/pwunconv.c, src/grpconv.c, src/grpunconv.c:
Ignore return value of spw_rewind, pw_rewind, sgr_rewind, and
gr_rewind.
* lib/commonio.h: Both head and tail cannot be owned. Set tail as
dependent.
* src/expiry.c: Ignore return value of expire ().
* src/expiry.c: The catch_signals function does not use its sig
parameter.
* src/userdel.c: Last audit_logger parameter is a
shadow_audit_result, use SHADOW_AUDIT_FAILURE instead of 0.
* src/grpconv.c: At the end of main, the passwd and shadow files
are locked. No need to check before unlocking. No need to set the
lock as false neither since there cannot be anymore failures.
src/newusers.c, src/pwconv.c, src/chpasswd.c, src/logoutd.c,
src/chfn.c, src/groupmems.c, src/usermod.c, src/pwunconv.c,
src/expiry.c, src/groupdel.c, src/chgpasswd.c, src/useradd.c,
src/su.c, src/groupmod.c, src/passwd.c, src/pwck.c,
src/groupadd.c, src/chage.c, src/login.c, src/grpconv.c,
src/groups.c, src/grpunconv.c, src/chsh.c: Prog is now global (not
static to the file) so that it can be used by the helper functions
of libmisc.
* lib/prototypes.h: Added extern char *Prog.
* libmisc/find_new_gid.c, libmisc/find_new_uid.c: Indicate the
program name with the warning.
prototypes of the static functions.
* src/grpconv.c: Fail if unexpected parameters are provided.
* src/grpconv.c: Indicate that argc is not used in the no
SHADOWGRP version.
* src/chage.c, src/chfn.c, src/chgpasswd.c, src/chpasswd.c,
src/chsh.c, src/gpasswd.c, src/groupadd.c, src/groupmems.c,
src/groupmod.c, src/grpck.c, src/grpconv.c, src/grpunconv.c,
src/passwd.c, src/pwck.c, src/pwconv.c, src/pwunconv.c,
src/useradd.c, src/userdel.c, src/usermod.c: Harmonize the error
message sent to stderr in case of *_update () failure.
* src/chage.c, src/chsh.c, src/groupadd.c, src/passwd.c: Do not
log to syslog when pw_update() or spw_update() fail.
* src/newusers.c: Do not log specific error message to stderr when
sgr_update() fails.
* src/pwconv.c: Remove duplicated definition of Prog.
* src/grpconv.c, src/grpunconv.c, src/pwconv.c, src/pwunconv.c,
src/vipw.c: Open syslog with the right identification name.
* src/vipw.c: Log unlock errors to syslog.
* src/vipw.c: Log edits to syslog.
* src/chage.c, src/chfn.c, src/chsh.c, src/gpasswd.c,
src/groupadd.c, src/groupdel.c, src/groupmod.c, src/grpconv.c,
src/grpunconv.c, src/passwd.c, src/pwck.c, src/pwunconv.c,
src/useradd.c, src/usermod.c: Harmonize the syslog levels. Failure
to close or unlock are errors. Failure to open files are warnings.
files. Report errors to stderr and syslog, but continue.
* src/grpconv.c: Check failure to unlock files. Report errors to
stderr and syslog, but continue.
src/groupadd.c, src/groupdel.c, src/groupmems.c, src/groupmod.c,
src/grpconv.c, src/grpunconv.c, src/newusers.c, src/pwconv.c,
src/pwunconv.c, src/useradd.c, src/userdel.c: Harmonize the name
of the variables keeping the lock status, to match the shadow
library prefixes.
src/gpasswd.c, src/groupadd.c, src/groupdel.c, src/groupmems.c,
src/groupmod.c, src/grpck.c, src/grpconv.c, src/grpunconv.c,
src/newusers.c, src/passwd.c, src/pwck.c, src/pwconv.c,
src/pwunconv.c, src/useradd.c, src/userdel.c, src/usermod.c: In
case of a lock failure, indicate to the user that she can try
again later. Do not log to syslog.
lib/sgroupio.c, lib/sgroupio.h, lib/shadowio.c, lib/shadowio.h:
Added *_dbname() functions to retrieve the name of the databases.
* lib/groupio.c, lib/groupio.h, lib/pwio.c, lib/pwio.h,
lib/sgroupio.c, lib/sgroupio.h, lib/shadowio.c, lib/shadowio.h:
*_name() functions renamed *setname().
* src/grpck.c, src/pwck.c: Likewise.
* lib/groupio.h, lib/pwio.h, lib/sgroupio.h, lib/shadowio.h: Added
the name of the arguments to the prototypes.
* src/chage, src/chfn.c, src/chgpasswd.c, src/chpasswd.c,
src/chsh.c, src/gpasswd.c, src/groupadd.c, src/groupdel.c,
src/groupmod.c, src/grpck.c, src/grpconv.c, src/grpunconv.c,
src/newusers.c, src/passwd.c, src/pwck.c, src/pwconv.c,
src/pwunconv.c, src/useradd.c, src/userdel.c, src/usermod.c:
Harmonize the erro & syslog messages in case of failure of the
*_lock(), *_open(), *_close(), *_unlock(), *_remove() functions.
* src/chgpasswd.c, src/chpasswd.c, src/usermod.c: Avoid
capitalized messages.
* src/chpasswd.c, src/useradd.c, src/usermod.c: Harmonize messages
in case of inexistent entries.
* src/usermod.c: Harmonize messages in case of already existing
entries.
* src/newusers.c, src/useradd.c: Simplify PAM error handling.
* src/useradd.c: Report failures to unlock files (stderr, syslog,
and audit). But do not fail (continue).
* src/useradd.c (open_files): Do not report to syslog & audit
failures to lock or open the databases. This might be harmless,
and the logs were not already informed that a change was
requested.
* src/usermod.c: It's not the account which is unlocked, but its
password.
* src/grpconv.c: Add brackets and parenthesis.
* src/grpconv.c: Ignore return value of setlocale(),
bindtextdomain(), and textdomain().
* src/grpconv.c: Avoid implicit conversion of pointers / integers
to booleans.
Files with no license use the default 3-clauses BSD license. The copyright
were mostly not recorded; they were updated according to the Changelog.
"Julianne Frances Haugh and contributors" changed to "copyright holders
and contributors".
