Nginx avec php-fpm renvoie une erreur 403 lors de la navigation sur le site

J'ai configuré un bloc serveur pour mon site tournant sur Nginx sur un VPS CentOS 7.

Lorsque j'essaie d'accéder à mon site web, j'obtiens une erreur 403 Forbidden. C'est apparemment un problème courant, mais je n'ai pas pu trouver de réponse satisfaisante :

Nginx et PHP-FPM 403 Forbidden

Voici la configuration nginx par défaut :

server {
    listen       80;
    server_name  ;
    root /var/www/html;
    index index.php index.html index.htm;

    location / {
        try_files $uri $uri/ =404;
    }
    error_page 404 /404.html;
    error_page 500 502 503 504  /50x.html;
    location = /50x.html {
        root   /var/www/html;
    }

    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }

}

Voici le fichier .conf pour mon site :

server {
  listen 80;
  server_name nativeleaf.co.uk www.nativeleaf.co.uk;
  access_log /var/www/html/nativeleaf.co.uk/access.log combined;
  root /var/www/html/nativeleaf.co.uk;

  location ~ \.php$ {
    try_files $uri =404;
    fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
    fastcgi_index index.php;
    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    include fastcgi_params;
  }
}

Et voici la configuration pour php-fpm :

; Start a new pool named 'www'.
[www]

; The address on which to accept FastCGI requests.
; Valid syntaxes are:
;   'ip.add.re.ss:port'    - to listen on a TCP socket to a specific address on
;                            a specific port;
;   'port'                 - to listen on a TCP socket to all addresses on a
;                            a specific port;
;   '/path/to/unix/socket' - to listen on a unix socket.
; Note: This value is mandatory.
;listen = 127.0.0.1:9000
listen = /var/run/php-fpm/php-fpm.sock

; Set listen(2) backlog. A value of '-1' means unlimited.
; Default Value: -1
;listen.backlog = -1

; List of ipv4 addresses of FastCGI clients which are allowed to connect.
; Equivalent to the FCGI_WEB_SERVER_ADDRS environment variable in the original
; PHP FCGI (5.2.2+). Makes sense only with a tcp listening socket. Each address
; must be separated by a comma. If this value is left blank, connections will be
; accepted from any ip address.
; Default Value: any
listen.allowed_clients = 127.0.0.1

; Set permissions for unix socket, if one is used. In Linux, read/write
; permissions must be set in order to allow connections from a web server. Many
; BSD-derived systems allow connections regardless of permissions.
; Default Values: user and group are set as the running user
;                 mode is set to 0666
listen.owner = nginx
listen.group = nginx
listen.mode = 0750

; Unix user/group of processes
; Note: The user is mandatory. If the group is not set, the default user's group
;       will be used.
; RPM: apache Choosed to be able to access some dir as httpd
user = nginx
; RPM: Keep a group allowed to write in log dir.
group = nginx

Vérification des journaux

Quand je regarde les logs Nginx avec un tail error.log, je vois ceci :

2018/04/26 14:54:01 [error] 12616#12616: *46 directory index of "/usr/share/nginx/html/nativeleaf.co.uk/" is forbidden, client: 31.205.255.43, server: nativeleaf.co.uk, request: "GET / HTTP/1.1", host: "nativeleaf.co.uk"
2018/04/26 14:54:02 [error] 12616#12616: *46 directory index of "/usr/share/nginx/html/nativeleaf.co.uk/" is forbidden, client: 31.205.255.43, server: nativeleaf.co.uk, request: "GET / HTTP/1.1", host: "nativeleaf.co.uk"
2018/04/26 14:54:03 [error] 12616#12616: *46 directory index of "/usr/share/nginx/html/nativeleaf.co.uk/" is forbidden, client: 31.205.255.43, server: nativeleaf.co.uk, request: "GET / HTTP/1.1", host: "nativeleaf.co.uk"
2018/04/26 15:12:00 [error] 13495#13495: *5 "/usr/share/nginx/html/nativeleaf.co.uk/what-is-yerba-mate/index.html" is not found (2: No such file or directory), client: 194.28.51.189, server: nativeleaf.co.uk, request: "GET /what-is-yerba-mate/ HTTP/1.0", host: "www.nativeleaf.co.uk", referrer: "https://www.nativeleaf.co.uk/what-is-yerba-mate/"
2018/04/26 15:15:43 [error] 14163#14163: *7 directory index of "/var/www/html/nativeleaf.co.uk/" is forbidden, client: 31.205.255.43, server: nativeleaf.co.uk, request: "GET / HTTP/1.1", host: "www.nativeleaf.co.uk"
2018/04/26 15:15:44 [error] 14163#14163: *7 directory index of "/var/www/html/nativeleaf.co.uk/" is forbidden, client: 31.205.255.43, server: nativeleaf.co.uk, request: "GET / HTTP/1.1", host: "www.nativeleaf.co.uk"
2018/04/26 15:15:44 [error] 14163#14163: *7 directory index of "/var/www/html/nativeleaf.co.uk/" is forbidden, client: 31.205.255.43, server: nativeleaf.co.uk, request: "GET / HTTP/1.1", host: "www.nativeleaf.co.uk"

Les permissions sur le dossier sont les suivantes :

drwxr-xr-x. 7 nginx  nginx   4096 Mar 26 07:07 nativeleaf.co.uk

Quant aux fichiers à l'intérieur, les permissions sont les suivantes :

-rw-r--r--.  1 nginx  nginx       418 Mar 23 11:39 index.php