Configuring The Authorization Service

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The authorization section in a Trapperkeeper configuration file controls the logic that the wrap-with-authorization-check handler uses to authorize a Ring request. Here is one example of an authorization section, using the HOCON configuration format:

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "^/my_path/([^/]+)$"
                    type: regex
                    method: get
                }
                allow: "$1"
                sort-order: 1
                name: "user-specific my_path"
            },
            {
                match-request: {
                    path: "/my_other_path"
                    type: path
                }
                allow-unauthenticated: true
                sort-order: 2
                name: "my_other_path"
            },
    ]
}

This document covers the individual settings in the authorization section, including information about how the service evaluates rules when authorizing a request.

`version`

authorization: {
    version: 1
    rules: [...]
}

Required. Version of the rule definitions that the authorization service should use. The only supported value is "1".

`allow-header-cert-info`

authorization: {
    version: 1
    allow-header-cert-info: true
    rules: [...]
}

Optional. Controls how the authenticated user "name" is derived for a request being authorized. Default value for the setting is false.

For a value of false, the authenticated "name" for the request is derived from the Common Name (CN) attribute within an X.509 certificate's Subject Distinguished Name (DN). The wrap-with-authorization-check middleware tries to get the request's X.509 certificate from the ssl-client-cert key in the Ring request map. If the certificate cannot be found, e.g., if the request was made over plaintext or was made over SSL/TLS but no certificate was provided by the client, or the CN is not present in the certificate, the request is considered "unauthenticated".

For a value of true, the authenticated "name" for the request is derived from evaluating the values set for the X-Client-DN and X-Client-Verify HTTP headers in the request. The value for an X-Client-DN HTTP header should be in the form of a Subject DN from an X.509 certificate (e.g., CN=myname). A value of SUCCESS for the X-Client-Verify HTTP header indicates that the request was validated successfully. If the X-Client-Verify HTTP header is not present or does not have a value of SUCCESS and/or the CN cannot be extracted from the X-Client-DN value, the request is considered "unauthenticated".

The X-Client-DN will attempt to be parsed first as a DN per RFC 2253. For example:

O=tester\, inc., CN=tester.test.org

If the DN is not found to conform to the RFC 2253 format, the X-Client-DN will be parsed per the OpenSSL compat DN format, where attribute key/value pairs are delimited by solidus, /, characters:

/O=tester, inc./CN=tester.test.org

If a CN value cannot be derived via either parsing approach, the handler returns an HTTP 400/Bad Request response.

Note: The "compat" OpenSSL DN format does not provide a way to escape special characters in the DN. If a solidus character were intended to be part of the value of an attribute, an unintended CN value could be derived. For example, the CN extracted from a DN of /CN=tester/ inc. is interpreted as tester rather than as tester/ inc.. The RFC 2253 format has a specified approach for escaping special characters and is, therefore, preferred for expressing DN values, where possible.

An "unauthenticated" request can only be "allowed" when the first matching rule has an allow-unauthenticated setting with a value of true. If allow-unauthenticated is set to false for the first rule matching the request, the request is "denied" - in which case the handler returns an HTTP 403/Forbidden response. For an "authenticated" request, the authenticated "name" for the request is evaluated against the allow and/or deny settings for the first rule which matches the request. See the documentation for the allow and deny settings for more information.

`rules`

Required. An array in which each of the elements is a map of settings pertaining to a rule. Here is an example of an array with two rules:

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "^/my_path/([^/]+)$"
                    type: regex
                }
                ...
            },
            {
                match-request: {
                    path: "/my_other_path"
                    type: path
                }
                ...
            },
    ]
}

The request is evaluated against each rule until either a rule is determined to be a match for the request or no match can be found for the request. If no rule can be matched to the request, the request is considered to be "denied" and, therefore, an HTTP 403/Forbidden response is returned from the wrap-with-authorization-check handler. If a rule is considered a match for the request, the authenticated "name" associated with the request is compared to the Access Control Entries (ACEs) in the rule - represented within allow, deny, and/or allow-unauthenticated settings - to determine whether the request should be "allowed" - in which case the handler calls through to the next handler in the middleware chain - or "denied". If a rule is found to be a match for the request but no allow, deny, or allow-unauthenticated setting matches the authenticated "name" for the request, the request is implicitly "denied".

A request is considered a match for the rule if it satisfies all of the criteria in the rule's match-request section. The authenticated "name" associated with the request is determined by the value set for the allow-header-cert-info setting.

Rules are ordered in memory prior to authorization being performed. Rules are ordered primarily by the numeric value in their sort-order fields, where the lower-numbered rules (e.g., 1) are evaluated before higher-numbered rules (e.g., 2). More than one rule can use the same sort-order value. In these cases, rules are secondarily sorted by the values in their name field. The name sort is lexicographical, using the Unicode code points of characters in the value, and does not account for locale-specific character ordering. Where the relative order in which rules are evaluated is critical, appropriate unique values should be used for the sort-order field in the rules.

The following settings in this section pertain to the fields for individual rule entries.

`match-request`

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "/my_path"
                    type: path
                }
                ...
            }
    ]
}

Required. In order for a rule to be considered a match for the request, the request must match each of the settings in the rule's match-request section. For example, if the rule were to specify values for path, type, and method and the request were to match the values for all three settings, the rule would be considered a match for the request and the result of the authorization attempt would be determined by matching the authenticated request's "name" to one of the ACEs in the rule. If the request were to only match the path and type but not the method in the rule, however, the rule would not be considered a match for the request and the service would move on to the next rule to see if it matches the request.

`path`

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "/my_path"
                    type: path
                }
                ...
            }
    ]
}

Required. The path setting is matched up against the [path component] (https://tools.ietf.org/html/rfc3986#section-3.3) of the request's URL. For example, if the request URL were "http://my-host:8080/the/path?myvar1=myvarval", the portion of the URL matched up against the path would be "/the/path". The type of match to be performed depends upon the value of the corresponding type setting for the rule.

`type`

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "/my_path"
                    type: path
                }
                ...
            }
    ]
}

Required. The type setting controls the type of match which is done with the value in the path setting against the path component in the request URL. The available values are:

path - Any request's path component starting with the literal value in the path setting would be a match. For example, a request URL of "http://my-host:8080/the/path?myvar1=myvarval" would be a match for a rule path of "/the/path/something/else" for a type of path. A request URL of "http://my-host:8080/the/wrong/path?myvar1=myvarval"`, however, would not be considered a match.
regex - Any request's path component matching the full regular expression in the path setting would be a match. For example, a request URL of "http://my-host:8080/the/path?myvar1=myvarval" would be a match for a rule path of "^/the/path$" for a type of regex. A request URL of "http://my-host:8080/the/path/something?myvar1=myvarval", however, would not be considered a match.

`method`

Optional. The method setting controls which HTTP methods (see section 5.1.1 of http://www.w3.org/Protocols/rfc2616/rfc2616.txt) would be considered a match for a request. If the method from the request matches any of the methods specified for the rule, the request is considered a match. If the method setting is omitted from the rule definition, any request would be considered a match. The method can be represented either as a single string value ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "/my_path"
                    type: path
                    method: get
                }
                ...
            }
    ]
}

... or as an array of values ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "/my_path"
                    type: path
                    method: [ get, post ]
                }
                ...
            }
    ]
}

Allowed values for method include get, post, put, delete, and head.

`query-params`

Optional. If present, the value should be a map of key/value pairs which are matched against the [query component] (https://tools.ietf.org/html/rfc3986#section-3.4) of the request URL. The rule is only considered a match if each of the keys listed in the query-params section are present in the request's query string and at least one of the corresponding values for each key is present in the values in the rule.

For example, the query-params section may have the following content:

authorization: {
    version: 1
    rules: [
            {
                match-request: {
                    path: "/my_path"
                    type: path
                    query-params: {
                        oneparam: [ valuea, valueb ]
                        twoparam: valuec
                    }
                }
                ...
            }
    ]
}

The following request URLs would be considered a match for this query-params section:

The following request URLs would not be considered a match for this query-params section:

If the query-params is omitted from the rule, any request - regardless of what query string is associated with it - would be considered a match.

`sort-order`

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow: "*"
                sort-order: 1
                name: "my path"
            }
    ]
}

Required. sort-order is a numeric value, where any value from 1 to 999 (inclusive) is valid. sort-order controls the order in which one rule is evaluated relative to another rule when authorizing a request. Rules with lower-numbered values are evaluated before rules with higher-numbered values. In these cases, rules are secondarily sorted by the values in their name field. The name sort is lexicographic, using the Unicode code points of each character, and does not account for locale-specific character ordering. Where the order in which rules are relatively are evaluated is critical, appropriate unique values should be used for the sort-order field in the rules.

A block in the middle of the sort-order range - from 400 to 600 (inclusive) is reserved for use by Puppet, e.g., for the default rules delivered with a package. Rules from 1 to 399 (inclusive) are reserved for users to insert custom rules ahead of any default Puppet ones and from 601 to 998 (inclusive) for inserting custom rules behind any default Puppet ones.

The 999 sort-order is reserved for a Puppet rule that denies all users access to all routes in the event that no other rule in the configuration was a match for the request.

`name`

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow: "*"
                sort-order: 1
                name: "my path"
            }
    ]
}

Required. name values are represented as a string and each rule's name value must be unique from any other rule's name value. The presence of the same name value in one or more rules would result in a service startup failure. When choosing a value, consider that the name may be written both to server logs and in the body of an error response returned to an unauthorized client.

`allow`

One of allow, deny, or allow-unauthenticated is required to be present for a rule. If allow-unauthenticated is set to true for a rule, allow may not be used.

The value for an allow setting can be represented either as a single string value ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow: node1
                sort-order: 1
                name: "my path"
            }
    ]
}

... or a single map value with an extensions key (see the extensions doc for more on working with extensions)...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow: {
                    extensions: {
                        my_ssl_extension: some_value
                        my_other_extension: a_value
                    }
                }
                sort-order: 1
                name: "my path"
            }
    ]
}

... or a single map value with a certname key (equivalent to a bare string) ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow: {
                    certname: node1
                }
                sort-order: 1
                name: "my path"
            }
    ]
}

... or as an array of values ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow: [ node1, node2, node3, {extensions:{ext_shortname1: value1, ext_shortname2: value2}} ]
                sort-order: 1
                name: "my path"
            }
    ]
}

If a request matches the criteria in the [match-request] (#match-request) section of the rule and the authenticated "name" of the request matches one of the allow entries, the request is "allowed" - in which case the handler calls through to the next handler in the middleware chain. See the [allow-header-cert-info] (#allow-header-cert-info) setting for information on how the authenticated "name" is derived for a request.

Note that if both allow and deny settings are included in the rule and the authenticated "name" matches an entry in both settings, the request is denied.

One of the following forms may be used as the value for an allow entry:

An exact name. For example: www.domain.org. In this case, only a request whose "name" were www.domain.org would be considered a match for the entry.
A glob of names, with an asterisk, *, in place of the leftmost segment. For example: *.domain.org. In this case, either www.domain.org or test.domain.org would be considered a match for the entry.
A regular expression, with surrounding solidus, /, characters. For example: /domain/. In this case, www.domain.org, test.domain.org, or www.domain.com would be considered a match for the entry.
A backreference to a capture group, only applicable when used with a rule whose type is regex. For example, if the path for the rule were "^/the/path/([^/]+)$", a backreference to the first capture group in the regular expression could be made by using a value like "$1.domain.org".
In this case, if the authenticated user's "name" were www.domain.org and the request URL were "http://my-host:8080/the/path/www", the authenticated "name" would be considered a match for the entry. An authenticated "name" of xyz.domain.org and a request URL of "http://my-host:8080/the/path/xyz", however, would not be considered a match for the entry.

A map with either a certname or extensions key. The former behaves exactly as a standalone string. The latter is used to specify a set of X.509 extensions to match. Each key specified in the extensions map must appear in the request and the values are matched exactly (no wildcarding). Extensions in the request not explicitly listed here are ignored. Note that a given extension map won't match if not all keys match. If you want an "or" relationship between extensions, split them into different extension maps. You may also use a list of values when writing an extension map. A request will match as long as it has an extension value that appears in the list for a given key.

For example, given the rules:

allow: [{extensions: {role: "compilemaster"
                      env: "prod1"}}
        {extensions: {role: console"
                      env: ["appgroup1", "prod1"]}}],
deny: [{extensions: {env: ["test", "dev"]}}
       {extensions: {role: "puppetdb"}}
       {extensions: {role: "console", pp_env: "demo"}}]

Requests with the following extension maps would be denied:

;; Denied by env: test rule
{:role "compilemaster"
 :env "test"
  ;; irrelevant keys elided
}

;; Denied since this combo of role and env does not appear in an allow rule
{:role "compilemaster"
 :env "appgroup2"
 ;; irrelevant keys elided
}

;; Denied by role: puppetdb rule
{:role "puppetdb"
 :env "prod1"
 ;; irrelevant keys elided
}

;; Denied since role nor env keys are never matched by an auth rule
{:role "mco"
 :env "prod1"
 ;; irrelevant keys elided
}

;; Denied since experimental is neither appgroup1 nor prod1
{:role "console"
 :env "experimental"
 ;; irrelevant keys elided
}

The following request extension maps would be allowed:

{:role "compilemaster"
 :env "prod1"
 ;; irrelevant keys elided
}

{:role "console"
 :env "prod1"
 ;; irrelevant keys elided
}

{:role "console"
 :env "appgroup1"
 ;; irrelevant keys elided
}

{:role "console"
 :env "appgroup1"
 ;; irrelevant keys elided
}

`deny`

One of allow, deny, or allow-unauthenticated is required to be present for a rule. If allow-unauthenticated is set to true for a rule, deny may not be used.

The value for a deny setting can be represented either as a single string value ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                deny: node1
                sort-order: 1
                name: "my path"
            }
    ]
}

... or a single map value with an extensions key (see the extensions doc for more on working with extensions)...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                deny: {
                    extensions: {
                        my_ssl_extension: some_value
                        my_other_extension: a_value
                    }
                }
                sort-order: 1
                name: "my path"
            }
    ]
}

... or a single map value with a certname key (equivalent to a bare string) ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                deny: {
                    certname: node1
                }
                sort-order: 1
                name: "my path"
            }
    ]
}

... or as an array of values ...

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                deny: [ node1, node2, node3, {extensions:{ext_name:value}} ]
                sort-order: 1
                name: "my path"
            }
    ]
}

If a request matches the criteria in the [match-request] (#match-request) section of the rule and the authenticated "name" of the request matches one of the deny entries, the request is "denied" - in which case the handler returns an HTTP 403/Forbidden response. See the [allow-header-cert-info] (#allow-header-cert-info) setting for information on how the authenticated "name" is derived for a request.

Note that if both allow and deny settings are included in the rule and the authenticated "name" matches an entry in both settings, the request is denied.

The supported forms for a deny entry are the same as those for an allow entry. See documentation for the [allow] (#allow) setting for more information.

`allow-unauthenticated`

authorization: {
    version: 1
    rules: [
            {
                match-request: {...}
                allow-unauthenticated: true
                sort-order: 1
                name: "my path"
            }
    ]
}

One of allow, deny, or allow-unauthenticated is required to be present for a rule. If allow-unauthenticated is set to true for a rule, neither allow nor deny may be used.

If a request matches the criteria in the [match-request] (#match-request) section of the rule and allow-unauthenticated is either omitted from the rule or explicitly set to false, the request is "allowed" or "denied" per the result of evaluating the request's authenticated "name" against the [allow] (#allow) and [deny] (#deny) setting entries. If no authenticated "name" can be determined for the request, the request is "denied" - in which case the handler returns an HTTP 403/Forbidden response.

If a request matches the criteria in the match-request section of the rule and allow-unauthenticated is set to true, the request is "allowed" - in which case the handler calls through to the next handler in the middleware chain. Whether or not an authenticated "name" can be determined for the request, the request is "allowed".

Working with x.509 Extensions in tk-auth❯

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