Role Based Access Control

The Role Based Access Control (RBAC) filter checks if the incoming request is authorized or not. Unlike external authorization, the check of RBAC filter happens in the Envoy process and is based on a list of policies from the filter config.

The RBAC filter can be either configured as a network filter, or as a HTTP filter or both. If the request is deemed unauthorized by the network filter then the connection will be closed. If the request is deemed unauthorized by the HTTP filter the request will be denied with 403 (Forbidden) response.

Policy

The RBAC filter checks the request based on a list of policies. A policy consists of a list of permissions and principals. The permission specifies the actions of the request, for example, the method and path of a HTTP request. The principal specifies the downstream client identities of the request, for example, the URI SAN of the downstream client certificate. A policy is matched if its permissions and principals are matched at the same time.

Shadow Policy

The filter can be configured with a shadow policy that doesn’t have any effect (i.e. not deny the request) but only emit stats and log the result. This is useful for testing a rule before applying in production.

Condition

In addition to the pre-defined permissions and principals, a policy may optionally provide an authorization condition written in the Common Expression Language. The condition specifies an extra clause that must be satisfied for the policy to match. For example, the following condition checks whether the request path starts with /v1/:

call_expr:
  function: startsWith
  args:
  - select_expr:
     operand:
       ident_expr:
         name: request
     field: path
  - const_expr:
     string_value: /v1/

The following attributes are exposed to the language runtime:

Attribute

Type

Description

request.path

string

The path portion of the URL

request.url_path

string

The path portion of the URL without the query string

request.host

string

The host portion of the URL

request.scheme

string

The scheme portion of the URL

request.method

string

Request method

request.headers

string map

All request headers

request.referer

string

Referer request header

request.useragent

string

User agent request header

request.time

timestamp

Time of the first byte received

request.duration

duration

Total duration of the request

request.id

string

Request ID

request.size

int

Size of the request body

request.total_size

int

Total size of the request including the headers

request.protocol

string

Request protocol e.g. “HTTP/2”

response.code

int

Response HTTP status code

response.grpc_status

int

Response gRPC status code

response.headers

string map

All response headers

response.trailers

string map

All response trailers

response.size

int

Size of the response body

response.total_size

int

Total size of the response including the approximate uncompressed size of the headers and the trailers

response.flags

int

Additional details about the response beyond the standard response code

source.address

string

Downstream connection remote address

source.port

int

Downstream connection remote port

destination.address

string

Downstream connection local address

destination.port

int

Downstream connection local port

metadata

Metadata

Dynamic metadata

connection.mtls

bool

Indicates whether TLS is applied to the downstream connection and the peer ceritificate is presented

connection.requested_server_name

string

Requested server name in the downstream TLS connection

connection.tls_version

string

TLS version of the downstream TLS connection

connection.subject_local_certificate

string

The subject field of the local certificate in the downstream TLS connection

connection.subject_peer_certificate

string

The subject field of the peer certificate in the downstream TLS connection

connection.dns_san_local_certificate

string

The first DNS entry in the SAN field of the local certificate in the downstream TLS connection

connection.dns_san_peer_certificate

string

The first DNS entry in the SAN field of the peer certificate in the downstream TLS connection

connection.uri_san_local_certificate

string

The first URI entry in the SAN field of the local certificate in the downstream TLS connection

connection.uri_san_peer_certificate

string

The first URI entry in the SAN field of the peer certificate in the downstream TLS connection

upstream.address

string

Upstream connection remote address

upstream.port

int

Upstream connection remote port

upstream.tls_version

string

TLS version of the upstream TLS connection

upstream.subject_local_certificate

string

The subject field of the local certificate in the upstream TLS connection

upstream.subject_peer_certificate

string

The subject field of the peer certificate in the upstream TLS connection

upstream.dns_san_local_certificate

string

The first DNS entry in the SAN field of the local certificate in the upstream TLS connection

upstream.dns_san_peer_certificate

string

The first DNS entry in the SAN field of the peer certificate in the upstream TLS connection

upstream.uri_san_local_certificate

string

The first URI entry in the SAN field of the local certificate in the upstream TLS connection

upstream.uri_san_peer_certificate

string

The first URI entry in the SAN field of the peer certificate in the upstream TLS connection

upstream.local_address

string

The local address of the upstream connection

upstream.transport_failure_reason

string

The upstream transport failure reason e.g. certificate validation failed

Most attributes are optional and provide the default value based on the type of the attribute. CEL supports presence checks for attributes and maps using has() syntax, e.g. has(request.referer).