nginx permission denied to certificate files for ssl configuration

Question

I'm installing an nginx ssl proxy on my Fedora server.

I've created a cert and key pair under /etc/nginx. They look like this:

ls -l /etc/nginx/
total 84
...
-rw-r--r--. 1 root root 1346 Sep 20 12:11 demo.crt
-rw-r--r--. 1 root root 1679 Sep 20 12:11 demo.key

...

As root, I'm trying to start the nginx service:

systemctl start nginx.service

I get the following error:

nginx[30854]: nginx: [emerg]
SSL_CTX_use_certificate_chain_file("/etc/nginx/demo.crt") failed (SSL: error:0200100D:system     library:fopen:Permission denied...e:system lib)
nginx[30854]: nginx: configuration file /etc/nginx/nginx.conf test failed

Is there something wrong with the permissions on these files?

Answer 1

You probably have SELinux in enforcing mode (the default for Fedora):

sestatus -v

If this is the case, check the audit logs, you should find the access error:

ausearch -m avc -ts today | audit2allow

You also probably moved the filed instead of copying it, so the security context of the file might be wrong.

ls -lrtZ /etc/nginx/demo.* 

and correct it if needed:

restorecon -v -R /etc/nginx

Answer 2

I guess it's SELinux that denies permission. Check their SELinux context. Theirs should be httpd_config_t. If not, run

restorecon /etc/nginx/demo.*

or

chcon httpd_config_t /etc/nginx/demo.*

as root.

You can check logs under /var/log/audit/ to see if it's SELinux that denies permission. You can also run

setenforce 0

to set SELinux into permissive mode. This way, SELinux still generates AVC messages (in /var/log/audit/) but permits access.