client_body_temp_path umask

location /upload {
client_body_temp_path /var/www/staging/;
#use clean in prod
client_body_in_file_only on;
client_body_buffer_size 128K;
client_max_body_size 100M;

proxy_pass_request_headers on;
proxy_set_header X-FILE $request_body_file;
proxy_set_body off;
proxy_redirect off;
proxy_pass http://localhost/process;
}

files created by nginx:
2014/02/26 21:47:23 [notice] 4533#0: *1 a client request body is buffered to a temporary file /var/www/staging/0000000001, client: 127.0.0.1, server:.com, request: "POST /upload HTTP/1.1", host: "localhost"

created file has owner nobody and very restrictive permissions
-rw------- 1 nobody admin 140257 26 Feb 21:47 0000000001

I'd like to read the file and process it's contents in the backend but I can't seem to figure out how to tell nginx to use a different umask (022) for the files it creates. Can anybody help me please?

cheers
Ronny