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.
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.
* src/grpck.c: Avoid implicit conversion of pointer to boolean.
* src/grpck.c: Remove dead code. argc cannot be lower than optind.
Avoid checking twice in a row for NULL != list[i].
and the password field in passwd is not 'x'.
* src/grpck.c: Warn if a group has an entry in group and gshadow,
and the password field in group is not 'x'.
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.
* 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.
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/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/groupmod.c, src/grpck.c, src/login.c, src/logoutd.c,
src/newgrp.c, src/newusers.c, src/passwd.c, src/pwck.c,
src/suauth.c, src/useradd.c, src/userdel.c, src/usermod.c,
src/vipw.c: Complete the switch from the `' quotation style to ''.
Do it also in SYSLOG messages. Quote some parameters. All this
permits to merge some messages.
check_user_name) renamed to is_valid_user_name (resp.
is_valid_group_name). is_valid_user_name and is_valid_group_name
return a bool.
* src/grpck.c, src/newusers.c, src/usermod.c, src/useradd.c,
src/groupmod.c, src/pwck.c, src/groupadd.c: Use is_valid_user_name
and is_valid_group_name, following above change.
* libmisc/chkname.c: Avoid implicit conversion of chars to
booleans. Add brackets and parenthesis.
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".
src/chfn.c, src/passwd.c, src/chage.c, src/login.c, src/sulogin.c,
src/chsh.c: Fix call to puts (remove end of line, or use fputs).
* po/*.po: Unfuzzy PO files according to above change.
* libmisc/Makefile.am, lib/prototypes.h, libmisc/yesno.c, src/grpck.c,
src/pwck.c: move yes_or_no() from grpck/pwck to a separate
libmisc/yesno.c (with a read_only argument).
* libmisc/fields.c, libmisc/yesno.c: Make sure stdout is flushed before
reading the user's answer.
libmisc/xgetXXbyYY.c, libmisc/xgetpwnam.c, libmisc/xgetpwuid.c,
libmisc/xgetgrnam.c, libmisc/xgetgrgid.c, libmisc/xgetspnam.c:
Added functions xgetpwnam(), xgetpwuid(), xgetgrnam(),
xgetgrgid(), and xgetspnam(). They allocate memory for the
returned structure and are more robust to successive calls. They
are implemented with the libc's getxxyyy_r() functions if
available.
* libmisc/limits.c, libmisc/entry.c, libmisc/chowntty.c,
libmisc/addgrps.c, libmisc/myname.c, libmisc/rlogin.c,
libmisc/pwdcheck.c, src/newgrp.c, src/login_nopam.c,
src/userdel.c, src/lastlog.c, src/grpck.c, src/gpasswd.c,
src/newusers.c, src/chpasswd.c, src/chfn.c, src/groupmems.c,
src/usermod.c, src/expiry.c, src/groupdel.c, src/chgpasswd.c,
src/su.c, src/useradd.c, src/groupmod.c, src/passwd.c, src/pwck.c,
src/groupadd.c, src/chage.c, src/login.c, src/suauth.c,
src/faillog.c, src/groups.c, src/chsh.c, src/id.c: Review all the
usage of one of the getpwnam(), getpwuid(), getgrnam(),
getgrgid(), and getspnam() functions. It was noticed on
http://bugs.debian.org/341230 that chfn and chsh use a passwd
structure after calling a pam function, which result in using
information from the passwd structure requested by pam, not the
original one. It is much easier to use the new xget... functions
to avoid these issues. I've checked which call to the original
get... functions could be left (reducing the scope of the
structure if possible), and I've left comments to ease future
reviews (e.g. /* local, no need for xgetpwnam */).
Note: the getpwent/getgrent calls should probably be checked also.
* src/groupdel.c, src/expiry.c: Fix typos in comments.
* src/groupmod.c: Re-indent.
* libmisc/Makefile.am, lib/groupmem.c, lib/groupio.c, lib/pwmem.c,
lib/pwio.c, lib/shadowmem.c, lib/shadowio.c: Move the __<xx>_dup
functions (used by the xget... functions) from the <xx>io.c files
to the new <xx>mem.c files. This avoid linking some utils against
the SELinux library.
