You will need to change the SELinux context for all files where Drupal needs to write to httpd_sys_rw_content_t, something like this:
semanage fcontext -a -t httpd_sys_rw_content_t '/usr/share/nginx/html/drupal/admin/config/media/file-system(/.*)?'
I don't know what are your paths and you need to check in Drupal interface in Configuration ->Media ->Filesystem for more information.