[Bug 1371984] New: /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Bug ID: 1371984
           Summary: /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/epam needs
                    to be installed setuid root
           Product: Fedora
           Version: 24
         Component: erlang-p1_pam
          Severity: high
          Priority: high
          Assignee: [e-mail]
          Reporter: [e-mail]
        QA Contact: [e-mail]
                CC: [e-mail],
                    [e-mail], [e-mail],
                    [e-mail], [e-mail]

The epam binary needs to be installed setuid root so that it can read
/etc/shadow for pam authentication. This is documented upstream at
https://docs.ejabberd.im/admin/guide/configuration/#pam-authentication. The
version of ejabberd distributed with Fedora 22 and Fedora 23 had a patch to
install this binary this way, but that patch was dropped when we released
Fedora 24.

This bug was originally reported in the comments of #1337216[0].

[0] https://bugzilla.redhat.com/show_bug.cgi?id=1337216

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

--- Comment #1 from Randy Barlow  ---
Created attachment 1196590
  --> https://bugzilla.redhat.com/attachment.cgi?id=1196590&action=edit
p1_pam patch for the facl solution

One of the challenges with making this change is that there's a slight chicken
and egg problem. We need to set the epam binary to mode 4750 (we don't want
just any user executing it), which means that we want to set the group to
ejabberd so that the ejabberd user can execute it. However, this erlang-p1_pam
package is a dependency of the ejabberd package which means that the ejabberd
user/group won't exist when erlang-p1_pam is installed.

I considered having the p1_pam package create the ejabberd group if the group
doesn't already exist, and we could solve this problem that way. p1_pam is
currently only used by ejabberd so it wouldn't be that dirty. However, the
upstream package is separated from ejabberd, presumably because they want it to
be generally useful so it does seem strange for it to create an ejabberd group.

Another option is to set the epam binary mode to 4700, but then have the
ejabberd package set a facl on it that gives the ejabberd user the rx bits.
This is a little strange as well, since it also seems wrong for a package to
modify an artifact of another package.

I lean towards the facl solution, but I'm interested in hearing some input from
others. I'm attaching an extremely simple patch that would be applied to p1_pam
for the facl solution, but if we go this route there would also be a required
change to ejabberd so that it sets the ejabberd rx facl upon install.

I've also considered that perhaps it makes sense to leave this problem up to
the end user to solve, and deliver documentation about the various options. I
think I lean away from doing it this way and towards solving it automatically
through one of the above, but I thought it was worth consideration nonetheless.

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

--- Comment #2 from Randy Barlow  ---
I decided to write the fedora-devel mailing list to get their input on how to
best solve this chicken and egg problem[0]. While writing that post, I realized
that there was a problem with the plan to use facls: if the p1_pam package were
updated after the ejabberd package set the needed facls on the binary, the
facls would be removed and the problem would return. Thus, I don't think that's
a viable option.

Perhaps having p1_pam create the ejabberd group is the best alternative I've
thought of so far, but I'll be interested to see if we get any replies on the
devel list.

[0]
https://lists.fedoraproject.org/archives/list/[e-mail]/...

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

[Red Hat Bugzilla]

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW

--- Comment #3 from Randy Barlow  ---
Fixing this sounds more complicated than I currently have time for, so I will
unfortunately have to put this down for now. I think the best thing is to work
with upstream ejabberd to make it compatible with sssd as well. It doesn't seem
like a good idea for the distribution to setuid root on this library for all
users, and doing so only for ejabberd is complicated.

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |1427123

Referenced Bugs:

https://bugzilla.redhat.com/show_bug.cgi?id=1427123
[Bug 1427123] ejabberd-17.07 is available

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|1427123                     |

Referenced Bugs:

https://bugzilla.redhat.com/show_bug.cgi?id=1427123
[Bug 1427123] ejabberd-17.07 is available

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
            Version|24                          |rawhide

--- Comment #4 from Randy Barlow  ---
I am going to fix this in Rawhide, with erlang-p1_pam-1.0.3-1.fc27. With that
build, upstream has made the so be SUID in the installer.

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |CLOSED
            Version|rawhide                     |26
   Fixed In Version|                            |erlang-p1_pam-1.0.0-3.fc26
         Resolution|---                         |RAWHIDE
        Last Closed|                            |2017-07-07 18:07:40

--- Comment #5 from Randy Barlow  ---
Well, it turned out that I actually did this myself in the specfile and just
forgot to close this bug. It was fixed in erlang-p1_pam-1.0.0-3.fc26.

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|CLOSED                      |NEW
         Resolution|RAWHIDE                     |---
           Keywords|                            |Reopened

--- Comment #6 from Randy Barlow  ---
And to be even more confusing, I did not release the fix to this. I think I
just had a stale change to my spec file on my machine that corresponded to the
version in F26 that made me think this. I confirmed that F26 is not suid root.

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Randy Barlow  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|26                          |24

[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

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[Bug 1371984] /usr/lib/erlang/lib/p1_pam-1.0.0/priv/bin/ epam needs to be installed setuid root

https://bugzilla.redhat.com/show_bug.cgi?id=1371984

Fedora End Of Life  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |CLOSED
         Resolution|---                         |EOL
        Last Closed|2017-07-07 18:07:40         |2017-08-08 12:57:23

--- Comment #8 from Fedora End Of Life  ---
Fedora 24 changed to end-of-life (EOL) status on 2017-08-08. Fedora 24 is
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