Bug 1567768

Hi, 

Could you reproduce, but full auditing? 

*****  Plugin dac_override (91.4 confidence) suggests   **********************

If you want to help identify if domain needs this access or you have a file with the wrong permissions on your system
Then turn on full auditing to get path information about the offending file and generate the error again.
Do

Turn on full auditing
# auditctl -w /etc/shadow -p w
Try to recreate AVC. Then execute
# ausearch -m avc -ts recent
If you see PATH record check ownership/permissions on file, and fix it,
otherwise report as a bugzilla.

Same here with selinux-policy-3.14.1-21.fc28.noarch

With full auditing:

time->Tue Apr 17 18:09:19 2018
type=AVC msg=audit(1523981359.846:520): avc:  denied  { dac_override } for  pid=3418 comm="nginx" capability=1  scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=capability permissive=0
----
time->Tue Apr 17 18:09:20 2018
type=AVC msg=audit(1523981360.512:521): avc:  denied  { dac_override } for  pid=3418 comm="nginx" capability=1  scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=capability permissive=0

I get this with a brand new unconfigured nginx install out of the box on Fedora 28, with nginx-1.12.1-5.fc28.x86_64 and selinux-policy-3.14.1-21.fc28.noarch

Yep, same result as Juan for me. systemctl status says:

# systemctl start nginx
Job for nginx.service failed because the control process exited with error code.
See "systemctl status nginx.service" and "journalctl -xe" for details.
# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Fri 2018-04-27 01:47:53 UTC; 7s ago
  Process: 16038 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=1/FAILURE)
  Process: 16037 ExecStartPre=/usr/bin/rm -f /run/nginx.pid (code=exited, status=0/SUCCESS)

Apr 27 01:47:52 zenbook.sfo1.in.logic.net systemd[1]: Starting The nginx HTTP and reverse proxy server...
Apr 27 01:47:52 zenbook.sfo1.in.logic.net nginx[16038]: nginx: [alert] could not open error log file: open() "/var/log/nginx/error.log" failed (13: Permission denied)
Apr 27 01:47:52 zenbook.sfo1.in.logic.net nginx[16038]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
Apr 27 01:47:52 zenbook.sfo1.in.logic.net nginx[16038]: 2018/04/27 01:47:52 [emerg] 16038#0: open() "/var/log/nginx/error.log" failed (13: Permission denied)
Apr 27 01:47:52 zenbook.sfo1.in.logic.net nginx[16038]: nginx: configuration file /etc/nginx/nginx.conf test failed
Apr 27 01:47:53 zenbook.sfo1.in.logic.net systemd[1]: nginx.service: Control process exited, code=exited status=1
Apr 27 01:47:53 zenbook.sfo1.in.logic.net systemd[1]: nginx.service: Failed with result 'exit-code'.
Apr 27 01:47:53 zenbook.sfo1.in.logic.net systemd[1]: Failed to start The nginx HTTP and reverse proxy server.

Looks like this came up in the context of AppArmor policies too?
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=819751
https://serverfault.com/questions/776940/does-nginx-really-need-dac-override-in-its-apparmor-policy

I'm having the same issue.  Upgraded from FC27 to FC28 and nginx no longer starts.

* nginx-1.12.1-5.fc28.x86_64

* selinux-policy-3.14.1-21.fc28.noarch

*** This bug has been marked as a duplicate of bug 1573942 ***

I'm unable to see bug 1573942 because it's marked private, so I'm re-opening this bug.  Feel free to close again if needed.

After installing nginx-1.12.1-7.fc28.x86_64, I'm still seeing this.  I get:
SELinux is preventing nginx from using the dac_override capability.

*****  Plugin dac_override (91.4 confidence) suggests   **********************

If you want to help identify if domain needs this access or you have a file with the wrong permissions on your system
Then turn on full auditing to get path information about the offending file and generate the error again.
Do

Turn on full auditing
# auditctl -w /etc/shadow -p w
Try to recreate AVC. Then execute
# ausearch -m avc -ts recent
If you see PATH record check ownership/permissions on file, and fix it,
otherwise report as a bugzilla.


After turning on full auditing, I get the following:
----
time->Sun May  6 07:17:55 2018
type=AVC msg=audit(1525591075.044:178): avc:  denied  { dac_override } for  pid=998 comm="nginx" capability=1  scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=capability permissive=1
----
time->Sun May  6 07:18:14 2018
type=AVC msg=audit(1525591094.369:194): avc:  denied  { dac_override } for  pid=1036 comm="nginx" capability=1  scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=capability permissive=1

Hey Jonathan,

I made bug 1573942 public. I tried to reproduce the SELinux dac_override issue, but I was not successful. 

With new version of nginx, I'm able to start nginx server without any problems:

# rpm -qa nginx
nginx-1.12.1-7.fc28.x86_64
# systemctl start nginx

Ok, I've figured it out.  I did an upgrade from Fedora 27 to Fedora 28, and apparently the owner of the files in /var/log/nginx has changed from nginx to root.  After changing the owner and group of /var/log/nginx/access.log and /var/log/nginx/error.log to root, the problem disappeared.

This should probably be documented somewhere, but I'll go ahead and change my karma since it seems to be an upgrade issue.

Description of problem:
I just trie to start nginx after my Fedora 28 upgrade.

Version-Release number of selected component:
selinux-policy-3.14.1-24.fc28.noarch

Additional info:
reporter:       libreport-2.9.5
hashmarkername: setroubleshoot
kernel:         4.16.6-302.fc28.x86_64
type:           libreport

(In reply to Jonathan Dieter from comment #9)
> Ok, I've figured it out.  I did an upgrade from Fedora 27 to Fedora 28, and
> apparently the owner of the files in /var/log/nginx has changed from nginx
> to root.  After changing the owner and group of /var/log/nginx/access.log
> and /var/log/nginx/error.log to root, the problem disappeared.

Thanks for this tip Jonathan -- changing the owner of the files to root does indeed fix the problem for me. I'm not sure if this is the "right" solution or not, but at least it lets me re-enable SELinux.

As an FYI, it looks like the logrotate configuration also needs to be updated to the new permissions/ownership, or the problem will show up again after nginx restarts following a log rotation.

Hi Ed, you are right logrotate configuration needs to be update. I will create new build today with patch, which should fix problems with owner/group permissions after USR1 signal is sent.

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