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

Jakub Hrozek jhrozek at redhat.com
Sat Nov 22 16:12:09 UTC 2014


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.



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