Nginx 403 forbidden for all files

If you still see permission denied after verifying the permissions of the parent folders, it may be SELinux restricting access.

To check if SELinux is running:

# getenforce

To disable SELinux until next reboot:

# setenforce Permissive

Restart Nginx and see if the problem persists. To allow nginx to serve your www directory (make sure you turn SELinux back on before testing this. i.e, setenforce Enforcing)

# chcon -Rt httpd_sys_content_t /path/to/www

See my answer here for more details

One permission requirement that is often overlooked is a user needs x permissions in every parent directory of a file to access that file. Check the permissions on /, /home, /home/demo, etc. for www-data x access. My guess is that /home is probably 770 and www-data can't chdir through it to get to any subdir. If it is, try chmod o+x /home (or whatever dir is denying the request).

EDIT: To easily display all the permissions on a path, you can use namei -om /path/to/check