Bug 1257990

This error is caused by SELinux:

Aug 31 07:47:13 rawhide-virt audit[1]: USER_AVC pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='Unknown permission start for class system exe="/usr/lib/systemd/systemd" sauid=0 hostname=? addr=? terminal=?'
Aug 31 07:47:13 rawhide-virt audit[485]: AVC avc:  denied  { read write } for  pid=485 comm="dbus-daemon" path="/dev/ptmx" dev="devtmpfs" ino=1137 scontext=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:ptmx_t:s0 tclass=chr_file permissive=0

On my other machine (rawhide as well), I'm also getting

Aug 31 11:28:18 rawhide audit[1865]: AVC avc:  denied  { transition } for  pid=1865 comm="(sh)" path="/usr/bin/bash" dev="sda3" ino=84406 scontext=system_u:system_r:init_t:s0 tcontext=unconfined
Aug 31 11:28:18 rawhide systemd[1865]: container-shell: Failed at step EXEC spawning /bin/sh: Permission denied

(In reply to Jan Synacek from comment #2)
> On my other machine (rawhide as well), I'm also getting
> 
> Aug 31 11:28:18 rawhide audit[1865]: AVC avc:  denied  { transition } for 
> pid=1865 comm="(sh)" path="/usr/bin/bash" dev="sda3" ino=84406
> scontext=system_u:system_r:init_t:s0 tcontext=unconfined
> Aug 31 11:28:18 rawhide systemd[1865]: container-shell: Failed at
> step EXEC spawning /bin/sh: Permission denied

Yes, that's a problem which we will need to discuss. We will need to make it working to reflect SELinux users.

The point is we have pam_selinux here so it requires "transition" perms. Also not sure if it reflect MCS/MLS range. Need to do more testing.

Dan, Dominick
any chance you have been playing with that?

what does machinectl shell supposed to do?  Start a shell within a container or VM?

time->Fri Sep 11 15:28:02 2015
type=USER_AVC msg=audit(1441999682.293:4830): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='Unknown permission stop for class system exe="/usr/lib/systemd/systemd" sauid=0 hostname=? addr=? terminal=?'

I am seeing the following when I execute that command on rawhide.  It looks like the SELinux/systemd code is broken.

We could probably add a transition from init_t to unconfined_t.  systemd should probably be maching the label of the pid 1 on a container.

https://github.com/fedora-selinux/selinux-policy/commit/c7d98ff11daa0743f46c1500196ef1eae9b79f74

It still fails to work correctly

[darrell@localhost ~]$ machinectl shell
Failed to get shell PTY: Message recipient disconnected from message bus without replying

selinux-policy.noarch                                              3.13.1-148.fc24                                               @koji

systemd.x86_64                                                    226-3.fc24                                                     @koji

There would be a transition.

Could you attach AVCs?

Created attachment 1076987 [details]
journalctl log

Created attachment 1079458 [details]
journalctl log again

With 	selinux-policy-3.13.1-150.fc24 there is still no shell

https://github.com/fedora-selinux/selinux-policy/commit/53c0f7b97b0165f46276ad20b28d694d6b5119f2

commit 53c0f7b97b0165f46276ad20b28d694d6b5119f2
Author: Miroslav Grepl <mgrepl>
Date:   Tue Oct 13 10:12:47 2015 +0200

    Allow systemd_machined_t to send dbus msgs to all users and read/write /dev/ptmx to make 'machinectl shell' working correctly.

Created attachment 1082614 [details]
Latest messages

Still fails to work

Failed to get shell PTY: No such file or directory

Latest log attached

I believe this option is gone with the kdbus removal from rawhide. Looked in the man page and didn't see it any more.

This bug probably still is valid - "machinectl shell" is no longer a valid subcommand, but "machinectl login" produces the same error on F23. Reported as BZ #1310464

Confirming the problem on Fedora 25. Only setting selinux in permissive mode I could use "machinectl shell" command


SELinux is preventing (sh) from lock access on the file /var/log/lastlog.

Additional Information:
Source Context                system_u:system_r:init_t:s0
Target Context                system_u:object_r:lastlog_t:s0
Target Objects                /var/log/lastlog [ file ]
Source                        (sh)
Source Path                   (sh)
Port                          <Unknown>
Host                          host
Source RPM Packages           
Target RPM Packages           
Policy RPM                    <Unknown>
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Platform                      Linux host 4.10.5-200.fc25.x86_64 #1 SMP Wed
                              Mar 22 20:37:08 UTC 2017 x86_64 x86_64
Alert Count                   1
First Seen                    2017-03-29 17:51:11 CEST
Last Seen                     2017-03-29 17:51:11 CEST


Raw Audit Messages
type=AVC msg=audit(1490802671.895:358): avc:  denied  { lock } for  pid=13847 comm="(sh)" path="/var/log/lastlog" dev="sdb2" ino=20948 scontext=system_u:system_r:init_t:s0 tcontext=system_u:object_r:lastlog_t:s0 tclass=file permissive=1


Hash: (sh),init_t,lastlog_t,file,lock
selinux-policy.noarch              3.13.1-225.11.fc25

Confirmed

With SELinux in enforcing mode and default targeted policy, running

# whoami
root
# machinectl shell --uid=root
Failed to get shell PTY: Access denied

even when run as root (if not password prompt will escalate if I understand correctly).

Switching SELinux in permissive mode with setenforce 0 makes it work. It's not a solution it's just to point to SELinux as the source of the problem. audit logs are now showing any AVC, even if build with donotautid disabled (semodule -BD), which puzzles me.

Strace-ing systemd-machined shows

8800  open("/dev/ptmx", O_RDWR|O_NOCTTY|O_CLOEXEC) = 8
8800  ioctl(8, TIOCSPTLCK, [0])         = 0
8800  ioctl(8, TIOCGPTN, [14])          = 0
8800  open("/dev/pts/14", O_RDWR|O_NOCTTY|O_CLOEXEC) = -1 EACCES (Permission denied)
8800  close(8)                          = 0
8800  sendmsg(6, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\3\1\1\26\0\0\0B\0\0\0O\0\0\0\5\1u\0\3\0\0\0\6\1s\0\6\0\0\0:1.164\0\0\4\1s\0'\0\0\0org.freedesktop.DBus.Error.AccessDenied\0\10\1g\0\1s\0\0", iov_len=96}, {iov_base="\21\0\0\0Permission denied\0", iov_len=22}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 118

So it could be that systemd_machined_t cannot access user_devpts_t

Still present in F26.

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Still the same problem on F27:

$ machinectl login
Failed to get login PTY: Access denied
$ sudo machinectl login
Failed to get login PTY: Access denied
$ sudo setenforce 0
$ machinectl login
Connected to the local host. Press ^] three times within 1s to exit session.
...


Someone with privileges please bump the version on this bug.

Does anyone care that one Red Hat-championed product (SELinux) has now been breaking key functionality of another Red Hat-funded and championed product (systemd) for THREE releases now?

Correction: FOUR Fedora releases.

I (we) care. 

I'll contact systemd folks and we try to make it working.

It is still broken on F29:

# machinectl login
Failed to get login PTY: Access denied

USER_AVC pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 msg='avc:  denied  { start } for auid=n/a uid=0 gid=0 path="/usr/lib/systemd/system/container-getty@.service" cmdline="/usr/lib/systemd/systemd-machined" scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:object_r:getty_unit_file_t:s0 tclass=service permissive=0
                                   exe="/usr/lib/systemd/systemd" sauid=0 hostname=? addr=? terminal=?'


# machinectl shell
Failed to get shell PTY: Message recipient disconnected from message bus without replying

----
time->Wed Nov 21 23:55:45 2018
type=AVC msg=audit(1542840945.792:1746): avc:  denied  { read write } for  pid=987 comm="dbus-daemon" path="/dev/pts/9" dev="devpts" ino=12 scontext=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:devpts_t:s0 tclass=chr_file permissive=0

Please update the version of this bug....

> I (we) care.

SIX Fedora releases.

Following PRs should fix the issue:

https://github.com/fedora-selinux/selinux-policy/pull/255

https://github.com/fedora-selinux/selinux-policy-contrib/pull/99

*** Bug 1416540 has been marked as a duplicate of this bug. ***

selinux-policy-3.14.2-53.fc29 has been submitted as an update to Fedora 29. https://bodhi.fedoraproject.org/updates/FEDORA-2019-bf377d92c7

selinux-policy-3.14.2-53.fc29 has been pushed to the Fedora 29 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2019-bf377d92c7

selinux-policy-3.14.2-53.fc29 has been pushed to the Fedora 29 stable repository. If problems still persist, please make note of it in this bug report.

hi,

on a fedora 31 workstation I have the same problems, so its not really fixed I am afraid.

I have set the systemd_machined_d to permissive and most things work except machinectl shell or login.

# machinectl login kdc
Failed to get login PTY: Remote peer disconnected

If I try that I get this in auditlogd:

# ausearch -m avc -ts recent
----
time->Sat Feb 29 13:57:22 2020
type=AVC msg=audit(1582981042.746:349): avc:  denied  { read } for  pid=6892 comm="(sd-openpt)" name="ptmx" dev="tmpfs" ino=95850 scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:object_r:tmpfs_t:s0 tclass=lnk_file permissive=1
----
time->Sat Feb 29 13:57:22 2020
type=AVC msg=audit(1582981042.746:350): avc:  denied  { open } for  pid=6892 comm="(sd-openpt)" path="/dev/pts/ptmx" dev="devpts" ino=2 scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:object_r:devpts_t:s0 tclass=chr_file permissive=1
----
time->Sat Feb 29 13:57:22 2020
type=AVC msg=audit(1582981042.748:351): avc:  denied  { write } for  pid=6896 comm="(sd-buscntr)" name="system_bus_socket" dev="tmpfs" ino=98837 scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:object_r:tmpfs_t:s0 tclass=sock_file permissive=1
----
time->Sat Feb 29 13:57:22 2020
type=AVC msg=audit(1582981042.748:352): avc:  denied  { connectto } for  pid=6896 comm="(sd-buscntr)" path="/run/dbus/system_bus_socket" scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:system_r:unconfined_service_t:s0 tclass=unix_stream_socket permissive=1
----
time->Sat Feb 29 13:57:22 2020
type=AVC msg=audit(1582981042.750:353): avc:  denied  { read write } for  pid=1084 comm="dbus-broker" path="/dev/pts/ptmx" dev="devpts" ino=2 scontext=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:devpts_t:s0 tclass=chr_file permissive=0

and the only way to enter the console of the container is setenforce 0, then it works.

So if anyone is still interested in fixing this, ..., :-)

another problem, probably related, with the same permissive domain, I cannot access the journal of the container. If I set selinux in permissive mode globally, then it works:

# semodule -l | grep permissive
permissive_systemd_machined_t
permissivedomains

# sestatus 
SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Memory protection checking:     actual (secure)
Max kernel policy version:      32

# journalctl -M centos1
Failed to open root directory: Remote peer disconnected

# ausearch -m avc -ts recent

time->Wed Mar  4 19:09:08 2020
type=AVC msg=audit(1583345348.434:352): avc:  denied  { search } for  pid=8879 comm="systemd-machine" name="5997" dev="proc" ino=117733 scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:system_r:unconfined_service_t:s0 tclass=dir permissive=1
----
time->Wed Mar  4 19:09:08 2020
type=AVC msg=audit(1583345348.434:353): avc:  denied  { read } for  pid=8879 comm="systemd-machine" name="mnt" dev="proc" ino=123349 scontext=system_u:system_r:systemd_machined_t:s0 tcontext=system_u:system_r:unconfined_service_t:s0 tclass=lnk_file permissive=1
----
time->Wed Mar  4 19:09:08 2020
type=AVC msg=audit(1583345348.436:354): avc:  denied  { read } for  pid=1098 comm="dbus-broker" path="/" dev="dm-1" ino=4104961 scontext=system_u:system_r:system_dbusd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:systemd_machined_var_lib_t:s0 tclass=dir permissive=0

# setenforce 0

# journalctl -M centos1
-- Logs begin at Sun 2020-03-01 22:32:25 CET, end at Wed 2020-03-04 19:05:05 CET. --
Mar 01 22:32:25 centos8 systemd-journald[17]: Journal started
Mar 01 22:32:25 centos8 systemd-journald[17]: Runtime journal (/run/log/journal/1b019ef3b8794cd0abf27514f0e5cc0a) is 8.0M, max 794.1M, 786.1M free.
Mar 01 22:32:25 centos8 systemd[1]: Starting Flush Journal to Persistent Storage...
Mar 01 22:32:25 centos8 systemd-journald[17]: Time spent on flushing to /var is 1.121ms for 3 entries.
....

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I am currently experiencing this issue in Fedora 34. For me, this was also related to: https://bugzilla.redhat.com/show_bug.cgi?id=1760146 After a while of adjusting the SELinux policy, I was eventually able to get nspawn and machinectl working properly, including the shell and login commands. I am attaching the SELinux policy changes that I made to this bug for further investigation.

Created attachment 1821667 [details]
SELinux Policy Changes for machinectl

SELinux policy changes for machinectl shell and login to function properly. Source for custom policy module that fixes the issue.

The needinfo request[s] on this closed bug have been removed as they have been unresolved for 500 days