How Does the Security access_control Work?

1. Matching Options

Symfony uses ChainRequestMatcher for each access_control entry, which determines which implementation of RequestMatcherInterface should be used on this request. The following access_control options are used for matching:

• path: a regular expression (without delimiters)
• ip or ips: netmasks are also supported (can be a comma-separated string)
• port: an integer
• host: a regular expression
• methods: one or many HTTP methods
• request_matcher: a service implementing RequestMatcherInterface
• attributes: an array, which can be used to specify one or more request attributes that must match exactly
• route: a route name

Take the following access_control entries as an example:

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# config/packages/security.yaml
parameters:
    env(TRUSTED_IPS): '10.0.0.1, 10.0.0.2'

security:
    # ...
    access_control:
        - { path: '^/admin', roles: ROLE_USER_PORT, ip: 127.0.0.1, port: 8080 }
        - { path: '^/admin', roles: ROLE_USER_IP, ip: 127.0.0.1 }
        - { path: '^/admin', roles: ROLE_USER_HOST, host: symfony\.com$ }
        - { path: '^/admin', roles: ROLE_USER_METHOD, methods: [POST, PUT] }

        # ips can be comma-separated, which is especially useful when using env variables
        - { path: '^/admin', roles: ROLE_USER_IP, ips: '%env(TRUSTED_IPS)%' }
        - { path: '^/admin', roles: ROLE_USER_IP, ips: [127.0.0.1, ::1, '%env(TRUSTED_IPS)%'] }

        # for custom matching needs, use a request matcher service
        - { roles: ROLE_USER, request_matcher: App\Security\RequestMatcher\MyRequestMatcher }

        # require ROLE_ADMIN for 'admin' route. You can use the shortcut "route: "xxx", instead of "attributes": ["_route": "xxx"]
        - { attributes: {'_route': 'admin'}, roles: ROLE_ADMIN }
        - { route: 'admin', roles: ROLE_ADMIN }

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// config/packages/security.php
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Config\SecurityConfig;

return static function (ContainerBuilder $container, SecurityConfig $security): void {
    $container->setParameter('env(TRUSTED_IPS)', '10.0.0.1, 10.0.0.2');
    // ...

    $security->accessControl()
        ->path('^/admin')
        ->roles(['ROLE_USER_PORT'])
        ->ips(['127.0.0.1'])
        ->port(8080)
    ;
    $security->accessControl()
        ->path('^/admin')
        ->roles(['ROLE_USER_IP'])
        ->ips(['127.0.0.1'])
    ;
    $security->accessControl()
        ->path('^/admin')
        ->roles(['ROLE_USER_HOST'])
        ->host('symfony\.com$')
    ;
    $security->accessControl()
        ->path('^/admin')
        ->roles(['ROLE_USER_METHOD'])
        ->methods(['POST', 'PUT'])
    ;
    // ips can be comma-separated, which is especially useful when using env variables
    $security->accessControl()
        ->path('^/admin')
        ->roles(['ROLE_USER_IP'])
        ->ips([env('TRUSTED_IPS')])
    ;
    $security->accessControl()
        ->path('^/admin')
        ->roles(['ROLE_USER_IP'])
        ->ips(['127.0.0.1', '::1', env('TRUSTED_IPS')])
    ;

    // for custom matching needs, use a request matcher service
    $security->accessControl()
        ->roles(['ROLE_USER'])
        ->requestMatcher('App\Security\RequestMatcher\MyRequestMatcher')
    ;

    // require ROLE_ADMIN for 'admin' route. You can use the shortcut route('xxx') method,
    // instead of attributes(['_route' => 'xxx']) method
    $security->accessControl()
        ->roles(['ROLE_ADMIN'])
        ->attributes(['_route' => 'admin'])
    ;
    $security->accessControl()
        ->roles(['ROLE_ADMIN'])
        ->route('admin')
    ;
};

For each incoming request, Symfony will decide which access_control to use based on the URI, the client's IP address, the incoming host name, and the request method. Remember, the first rule that matches is used, and if ip, port, host or method are not specified for an entry, that access_control will match any ip, port, host or method. See the following examples:

Example #1:

• URI /admin/user
• IP: 127.0.0.1, Port: 80, Host: example.com, Method: GET
• Rule applied: rule #2 (ROLE_USER_IP)
• Why? The URI matches path and the IP matches ip.

Example #2:

• URI /admin/user
• IP: 127.0.0.1, Port: 80, Host: symfony.com, Method: GET
• Rule applied: rule #2 (ROLE_USER_IP)
• Why? The path and ip still match. This would also match the ROLE_USER_HOST entry, but only the first access_control match is used.

Example #3:

• URI /admin/user
• IP: 127.0.0.1, Port: 8080, Host: symfony.com, Method: GET
• Rule applied: rule #1 (ROLE_USER_PORT)
• Why? The path, ip and port match.

Example #4:

• URI /admin/user
• IP: 168.0.0.1, Port: 80, Host: symfony.com, Method: GET
• Rule applied: rule #3 (ROLE_USER_HOST)
• Why? The ip doesn't match neither the first rule nor the second rule.
• So the third rule (which matches) is used.

Example #5:

• URI /admin/user
• IP: 168.0.0.1, Port: 80, Host: symfony.com, Method: POST
• Rule applied: rule #3 (ROLE_USER_HOST)
• Why? The third rule still matches. This would also match the fourth rule
• (ROLE_USER_METHOD), but only the first matched access_control is used.

Example #6:

• URI /admin/user
• IP: 168.0.0.1, Port: 80, Host: example.com, Method: POST
• Rule applied: rule #4 (ROLE_USER_METHOD)
• Why? The ip and host don't match the first three entries, but
• the fourth - ROLE_USER_METHOD - matches and is used.

Example #7:

• URI /foo
• IP: 127.0.0.1, Port: 80, Host: symfony.com, Method: POST
• Rule applied: matches no entries
• Why? This doesn't match any access_control rules, since its URI
• doesn't match any of the path values.

2. Access Enforcement

Once Symfony has decided which access_control entry matches (if any), it then enforces access restrictions based on the roles, allow_if and requires_channel options:

• roles If the user does not have the given role, then access is denied (internally, an AccessDeniedException is thrown).
• allow_if If the expression returns false, then access is denied;
• requires_channel If the incoming request's channel (e.g. http) does not match this value (e.g. https), the user will be redirected (e.g. redirected from http to https, or vice versa).

Matching access_control By IP

Certain situations may arise when you need to have an access_control entry that only matches requests coming from some IP address or range. For example, this could be used to deny access to a URL pattern to all requests except those from a trusted, internal server.

Here is an example of how you configure some example /internal* URL pattern so that it is only accessible by requests from the local server itself:

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# config/packages/security.yaml
security:
    # ...
    access_control:
        #
        # the 'ips' option supports IP addresses and subnet masks
        - { path: '^/internal', roles: PUBLIC_ACCESS, ips: [127.0.0.1, ::1, 192.168.0.1/24] }
        - { path: '^/internal', roles: ROLE_NO_ACCESS }

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// config/packages/security.php
use Symfony\Config\SecurityConfig;

return static function (SecurityConfig $security): void {
    // ...

    $security->accessControl()
        ->path('^/internal')
        ->roles(['PUBLIC_ACCESS'])
        // the 'ips' option supports IP addresses and subnet masks
        ->ips(['127.0.0.1', '::1'])
    ;

    $security->accessControl()
        ->path('^/internal')
        ->roles(['ROLE_NO_ACCESS'])
    ;
};

Here is how it works when the path is /internal/something coming from the external IP address 10.0.0.1:

• The first access control rule is ignored as the path matches but the IP address does not match either of the IPs listed;
• The second access control rule is enabled (the only restriction being the path) and so it matches. If you make sure that no users ever have ROLE_NO_ACCESS, then access is denied (ROLE_NO_ACCESS can be anything that does not match an existing role, it only serves as a trick to always deny access).

But if the same request comes from 127.0.0.1 or ::1 (the IPv6 loopback address):

• Now, the first access control rule is enabled as both the path and the ip match: access is allowed as the user always has the PUBLIC_ACCESS role.
• The second access rule is not examined as the first rule matched.

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# config/packages/security.yaml
security:
    # ...
    access_control:
        -
            path: ^/_internal/secure
            # the 'roles' and 'allow_if' options work like an OR expression, so
            # access is granted if the expression is TRUE or the user has ROLE_ADMIN
            roles: 'ROLE_ADMIN'
            allow_if: "'127.0.0.1' == request.getClientIp() or request.headers.has('X-Secure-Access')"

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// config/packages/security.php
use Symfony\Config\SecurityConfig;

return static function (SecurityConfig $security): void {
    // ...

    $security->accessControl()
        ->path('^/_internal/secure')
        // the 'role' and 'allow-if' options work like an OR expression, so
        // access is granted if the expression is TRUE or the user has ROLE_ADMIN
        ->roles(['ROLE_ADMIN'])
        ->allowIf('"127.0.0.1" == request.getClientIp() or request.headers.has("X-Secure-Access")')
    ;
};

Restrict to a port

Add the port option to any access_control entries to require users to access those URLs via a specific port. This could be useful for example for localhost:8080.

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# config/packages/security.yaml
security:
    # ...
    access_control:
        - { path: ^/cart/checkout, roles: PUBLIC_ACCESS, port: 8080 }

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// config/packages/security.php
use Symfony\Config\SecurityConfig;

return static function (SecurityConfig $security): void {
    // ...

    $security->accessControl()
        ->path('^/cart/checkout')
        ->roles(['PUBLIC_ACCESS'])
        ->port(8080)
    ;
};

Forcing a Channel (http, https)

You can also require a user to access a URL via SSL; use the requires_channel argument in any access_control entries. If this access_control is matched and the request is using the http channel, the user will be redirected to https:

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# config/packages/security.yaml
security:
    # ...
    access_control:
        - { path: ^/cart/checkout, roles: PUBLIC_ACCESS, requires_channel: https }

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// config/packages/security.php
use Symfony\Config\SecurityConfig;

return static function (SecurityConfig $security): void {
    // ...

    $security->accessControl()
        ->path('^/cart/checkout')
        ->roles(['PUBLIC_ACCESS'])
        ->requiresChannel('https')
    ;
};