nginx访问没有问题

nginx配置

 server {
        listen   8080;


        root /opt/nginx-1.7.8/html/demo;
        index index.php index.html index.htm;

        server_name example.com;

        location / {
                try_files $uri $uri/ /index.html;
        }

        error_page 404 /404.html;

        error_page 500 502 503 504 /50x.html;
        location = /50x.html {
              root /opt/nginx-1.7.8/html;
        }

        # pass the PHP scripts to FastCGI server listening on the php-fpm socket
        location ~ \.php$ {
                try_files $uri =404;
                fastcgi_pass  unix:/run/php5-fpm.sock;
                fastcgi_index index.php;
                fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                include fastcgi_params;

        }

在 /opt/nginx-1.7.8/html/demo 目录下游 index.php ，然是访问报错502

 An error occurred.

Sorry, the page you are looking for is currently unavailable.
Please try again later.

If you are the system administrator of this resource then you should check the error log for details.

Faithfully yours, nginx.

日志：

 2015/10/25 10:36:24 [crit] 12149#0: *1 connect() to unix:/run/php5-fpm.sock failed (13: Permission denied) while connecting to upstream, client: 219.217.226.133, server: example.com, request: "GET /index.php HTTP/1.1", upstream: "fastcgi://unix:/run/php5-fpm.sock:", host: "159.203.251.133:8080"

求助~