[SSSD] [PATCH] sss_client: Return a different error when sssd is not running

Jakub Hrozek jhrozek at redhat.com
Fri Dec 5 15:22:28 UTC 2014


On Mon, Nov 24, 2014 at 02:14:27PM +0100, Lukas Slebodnik wrote:
> On (24/11/14 10:47), Jakub Hrozek wrote:
> >On Mon, Nov 24, 2014 at 09:51:58AM +0100, Lukas Slebodnik wrote:
> >> On (22/11/14 17:25), Jakub Hrozek wrote:
> >> >On Sat, Nov 22, 2014 at 05:12:09PM +0100, Jakub Hrozek wrote:
> >> >> On Tue, Nov 18, 2014 at 12:25:40PM +0100, Lukas Slebodnik wrote:
> >> >> > On (18/11/14 12:22), Lukas Slebodnik wrote:
> >> >> > >On (13/11/14 10:08), Simo Sorce wrote:
> >> >> > >>On Thu, 13 Nov 2014 10:44:45 +0100
> >> >> > >>Jakub Hrozek <jhrozek at redhat.com> wrote:
> >> >> > >>
> >> >> > >>> On Wed, Nov 12, 2014 at 08:04:46PM -0500, Simo Sorce wrote:
> >> >> > >>> > On Wed, 12 Nov 2014 16:36:00 +0100
> >> >> > >>> > Lukas Slebodnik <lslebodn at redhat.com> wrote:
> >> >> > >>> > 
> >> >> > >>> > > On (12/11/14 10:00), Simo Sorce wrote:
> >> >> > >>> > > >I would create a helper function to be called on return that
> >> >> > >>> > > >transforms the error accordingly. This will allow to write the
> >> >> > >>> > > >code _and_ the comment once.
> >> >> > >>> > > >
> >> >> > >>> > > In this case, Stephan's patch is better
> >> >> > >>> > > https://bugzilla.redhat.com/attachment.cgi?id=788567
> >> >> > >>> > 
> >> >> > >>> > Yes, this is a valid alternative.
> >> >> > >>> > 
> >> >> > >>> > > >The comment should be changed to something like this in either
> >> >> > >>> > > >case: /* When sssd is stopped return a safe error code as if sss
> >> >> > >>> > > >was not configured at all in nsswitch. This prevents bogus
> >> >> > >>> > > >errors from causing issues in applications, before sssd starts
> >> >> > >>> > > >or if it fails to respond. */
> >> >> > >>> > > >
> >> >> > >>> > > >No need to mention that sss is by default in nsswitch, as it is
> >> >> > >>> > > >not in all distributions and it really is inconsequential, the
> >> >> > >>> > > >same behaviour change hleps when sss is not the default but is
> >> >> > >>> > > >has been manually added and sssd is stopped or not started yet
> >> >> > >>> > > >(for example during boot).
> >> >> > >>> > > nss-pam-ldapd has the same behaviour in the same situation.
> >> >> > >>> > > Will we patch it as well? It's very likely we won't.
> >> >> > >>> > 
> >> >> > >>> > Sorry, I do not see how that matters :)
> >> >> > >>> > 
> >> >> > >>> > > The biggest problem is that sss is by default in nsswitch on
> >> >> > >>> > > fedora/rhel>=7 due to glibc caching and problem with GNOME,
> >> >> > >>> > > a) sssd-client is installed by default on this platforms.
> >> >> > >>> > > b) sssd need't be configured by default and in most cases won't be
> >> >> > >>> > >     => sssd cannot run
> >> >> > >>> > > c) glibc developers don't want to adjust the error return code in
> >> >> > >>> > > glibc
> >> >> > >>> > > 
> >> >> > >>> > > As a result of this, we need to patch sssd.
> >> >> > >>> > > I would say we should patch sssd just in downstream and
> >> >> > >>> > > Stephan's patch works well. I tested it.
> >> >> > >>> > 
> >> >> > >>> > Ok, then let's go with Stephen's patch.
> >> >> > >>> > 
> >> >> > >>> > Simo.
> >> >> > >>> > 
> >> >> > >>> 
> >> >> > >>> I don't personally mind whether we use Lukas' or Stephen's patch but I
> >> >> > >>> would /strongly/ prefer the patch to be pushed upstream.
> >> >> > >>> 
> >> >> > >>> Non-upstream patches should be considered valid only as a temporary
> >> >> > >>> workarounds..
> >> >> > >>
> >> >> > >>I was not aware the patch was not proposed for upstream. I strongly
> >> >> > >>disagree on this kind of patches being platform specific too.
> >> >> > >>
> >> >> > >New version of patch is attached.
> >> >> > >
> >> >> > Ups, one more time.
> >> >> > 
> >> >> > LS
> >> >> 
> >> >> > From eb617a980d50c7081ecb6eda0d489fc0eb8963f7 Mon Sep 17 00:00:00 2001
> >> >> > From: Lukas Slebodnik <lslebodn at redhat.com>
> >> >> > Date: Tue, 18 Nov 2014 12:02:10 +0100
> >> >> > Subject: [PATCH] sss_client: Work around glibc bug
> >> >> > 
> >> >> > glibc is inconsistent with how it treats and returns NSS_STATUS_UNAVAIL.
> >> >> > 
> >> >> > The sss nss plugin is present in nsswitch by default on some platforms
> >> >> > due to glibc caching and problem with long living applications (e.g. GNOME).
> >> >> > The SSSD nss plugin should behave as if it was functioning but had no data even
> >> >> > thought sssd is not running. The errors have to be passed from nss plugin up to
> >> >> > the user with minimal moidiffication.
> >> >> > 
> >> >> > Thanks to Stephen Gallagher for initial patch.
> >> >> > 
> >> >> > Resolves:
> >> >> > https://fedorahosted.org/sssd/ticket/2439
> >> >> > ---
> >> >> >  src/conf_macros.m4      | 13 +++++++++++++
> >> >> >  src/sss_client/common.c | 10 ++++++++++
> >> >> >  2 files changed, 23 insertions(+)
> >> >> > 
> >> >> > diff --git a/src/conf_macros.m4 b/src/conf_macros.m4
> >> >> > index fbee81f56e484b618379f7c987ecee50ae48917e..bb283ef248ee017fd608bd85cc68666db0300fd9 100644
> >> >> > --- a/src/conf_macros.m4
> >> >> > +++ b/src/conf_macros.m4
> >> >> > @@ -708,6 +708,19 @@ AC_ARG_ENABLE([dbus-tests],
> >> >> >                [build_dbus_tests=yes])
> >> >> >  AM_CONDITIONAL([BUILD_DBUS_TESTS], [test x$build_dbus_tests = xyes])
> >> >> >  
> >> >> > +AC_ARG_ENABLE([sss-default-nss-plugin],
> >> >> > +              [AS_HELP_STRING([--enable-sss-default-nss-plugin],
> >> >> > +                              [This option change standard behaviour of sss nss
> >> >> > +                               plugin. If this option is enabled the sss nss
> >> >> > +                               plugin will behave as it was not in
> >> >> > +                               nsswitch.conf when sssd is not running.
> >> >> > +                               [default=no]])],
> >> >> > +              [],
> >> >> 
> >> >> Didn't you mean to add:
> >> >>     enable_sss-default-nss-plugin=$enablevar
> >> >> 
> >> >> here?
> >> >> 
> >> >> Additionally, it would be nice to explain in the commit message why the
> >> >> feature is disabled -- explain the effect enabling by default would have
> >> >> on searches that don't find anything.
> >> >
> >> >Actually, you also need to convert dashes to underscores in the variable
> >> >name. As the autoconf docs say:
> >> >    The option's argument is available to the shell commands
> >> >    action-if-given in the shell variable enableval, which is actually
> >> >    just the value of the shell variable named enable_feature, with any
> >> >    non-alphanumeric characters in feature changed into ‘_’.
> >> >
> >> >This change did the trick for me and I was able to test the return value
> >> >in gdb.
> >> In gdb? really
> >> Could you ellaborate?
> >
> >Once I fixed the config option so the build-time switch actually worked:
> >
> I thought you was able to see value of bash variable
> enable_sss-default-nss-plugin :-)
> 
> New version is attached.
> 
> LS

Thank you, the code looks good. Were you able to reproduce the exact
same error as the user saw, though?

I tested with "files sss ldap" in nsswitch.conf and SSSD was off. Even
without the patch, getent group $ipagroup was able to fall back to
ldap..so I guess I must be missing something.



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