Bug 1567988

Summary: dac_read_search AVC from pam_systemd
Product: [Fedora] Fedora Reporter: Pierre Ossman <ossman>
Component: selinux-policyAssignee: Lukas Vrabec <lvrabec>
Status: CLOSED EOL QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 27CC: dwalsh, lvrabec, mgrepl, plautrba
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Last Closed: 2018-11-30 22:49:20 UTC Type: Bug
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Description Pierre Ossman 2018-04-16 14:12:33 UTC
We've very recently started seeing these AVCs on login with ThinLinc:

type=AVC msg=audit(1523887506.616:384): avc:  denied  { dac_read_search } for  pid=4290 comm="tl-session" capability=2  scontext=system_u:system_r:thinlinc_session_t:s0 tcontext=system_u:system_r:thinlinc_session_t:s0 tclass=capability permissive=0

After a lot of digging it turns out that the issue is accessing /run/user/<uid>/bus in order to start or verify the user d-bus. I'm not sure what PAM module is responsible for this, but I guess it is pam_systemd.

This seems similar to the issues with unix_chkpwd that happened recently:


ThinLinc has the following policy:

type thinlinc_session_exec_t;
type thinlinc_session_t;
domain_entry_file(thinlinc_session_t, thinlinc_session_exec_t)



allow thinlinc_session_t self:capability { kill chown dac_override fowner setgid setuid sys_resource };
allow thinlinc_session_t self:process { getcap setsched setexec setrlimit };
allow thinlinc_session_t self:fifo_file rw_fifo_file_perms;





I would have hoped that auth_login_pgm_domain() would have set everything up, but perhaps another macro needs to be added?

Comment 1 Pierre Ossman 2018-04-16 14:21:10 UTC
I guess I didn't read our own policy carefully enough. I see that we were already forced to explicitly mention dac_override. And I see that upstream has added dac_read_search explicitly to a bunch of domains, so I guess that is the correct solution here?

Comment 2 Ben Cotton 2018-11-27 14:25:23 UTC
This message is a reminder that Fedora 27 is nearing its end of life.
On 2018-Nov-30  Fedora will stop maintaining and issuing updates for
Fedora 27. It is Fedora's policy to close all bug reports from releases
that are no longer maintained. At that time this bug will be closed as
EOL if it remains open with a Fedora  'version' of '27'.

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Comment 3 Ben Cotton 2018-11-30 22:49:20 UTC
Fedora 27 changed to end-of-life (EOL) status on 2018-11-30. Fedora 27 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

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