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

Jakub Hrozek jhrozek at redhat.com
Sat Nov 22 16:25:11 UTC 2014


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.



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