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A couple of fixes for errors reported by rpmlint #7794

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A couple of fixes for errors reported by rpmlint #7794

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scabrero
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rpmlint reports a couple of security related issues:

  • The krb5 child does not drop supplementary groups after setresuid() and setresgid()
  • <allow> directives in the infopipe service without send_destination

Reported in https://bugzilla.suse.com/show_bug.cgi?id=1235724

@alexey-tikhonov alexey-tikhonov self-assigned this Jan 15, 2025
@alexey-tikhonov alexey-tikhonov self-requested a review January 15, 2025 11:44
alexey-tikhonov
alexey-tikhonov reviewed Jan 15, 2025
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src/providers/krb5/krb5_ccache.c Outdated
@@ -54,6 +55,11 @@ errno_t switch_to_user(void)
return errno;
}

ret = setgroups(0, NULL);
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There are several reasons why this is not needed and, most probably, won't work.

First of all, those functions - 'switch_to_*()' - are exclusively used by 'krb5_child' only.
And the first thing 'krb5_child' does - it calls privileged_krb5_setup().
First thing privileged_krb5_setup() does - it calls setgroups(0, NULL) if appropriate.
So groups are either already dropped, or can't be dropped (see comment

sssd/src/providers/krb5/krb5_child.c

Line 3997 in c6294f5

} /* Otherwise keep supplementary groups to have access to DB_PATH to store FAST ccache */
)

Moreover, next thing 'krb5_child' does - sss_drop_all_caps().
Due to this setgroups() here will fail with EPERM

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I'm not sure if this would make 'rpmlint' happy, but maybe addition of else keep-SSSD-group-only in privileged_krb5_setup() would be better.

But imo it's not worth bothering.

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Hi Alexey, thanks for the detailed explanation.

Adding the else part to privileged_krb5_setup() will not help because rpmlint just scans the shared library for function calls. In libsss_krb5_common.so it finds the the setresuid() inside switch_to_xxx() without a setgroups() call, and privileged_krb5_setup() is not part of this library.

I will just add an exemption for this error. What's about the other patch? I will update this PR if it makes sense.

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What's about the other patch?

d-bus policy patch looks good to me (but will require a 2nd reviewer).

@alexey-tikhonov
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@scabrero, FYI, we plan sssd-2.10.2 release soon.

ikerexxe
ikerexxe reviewed Jan 22, 2025
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The second patch looks good.

@scabrero
IFP: Restrict destination
dfd4122 
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Domains"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Domains.Domain"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Users"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Users.User"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Groups"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Groups.Group"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Cache"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Cache.Object"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> sssd-dbus.x86_64: E: dbus-policy-allow-without-destination <allow send_interface="org.freedesktop.sssd.infopipe.Components"/> /usr/share/dbus-1/system.d/org.freedesktop.sssd.infopipe.conf
> 'allow' directives must always specify a 'send_destination'.

Signed-off-by: Samuel Cabrero <[email protected]>
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Thanks, I dropped the first patch and rebased. I hope it is on time for 2.10.2.

ikerexxe
ikerexxe approved these changes Jan 22, 2025
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LGTM. Thank you for taking into account the feedback.

@alexey-tikhonov
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Pushed PR: #7794

  • master
    • afc643d - IFP: Restrict destination
  • sssd-2-10
    • 961742c - IFP: Restrict destination

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