access

Table of Contents

Access promises are conditional promises made by resources living on the server.

The promiser is the name of the resource affected and is interpreted to be a path, unless a different resource_type is specified. Access is then granted to hosts listed in admit_ips, admit_keys and admit_hostnames, or denied using the counterparts deny_ips, deny_keys and deny_hostnames.

You layer the access policy by denying all access and then allowing it only to selected clients, then denying to an even more restricted set.

bundle server access_rules()
{
access:

  "/source/directory"
    comment => "Access to file transfer",
    admit_ips   => { "192.168.0.1/24" };
}

For file copy requests, the file becomes transferable to the remote client according to the conditions specified in the access promise. Use ifencrypted to grant access only if the transfer is encrypted in the "classic" CFEngine protocol (the TLS protocol is always encrypted).

When access is granted to a directory, the promise is automatically made about all of its contents and sub-directories.

Use the maproot attribute (like its NFS counterpart) to control which hosts can see file objects not owned by the server process owner.

File resources are specified using an absolute filepath, but can set a shortcut through which clients can access the resource using a logical name, without having any detailed knowledge of the filesystem layout on the server. Specifically in access promises about files, a special variable context connection is available with variables ip, key and hostname, containing information about the connection through which access is attempted.

   "/var/cfengine/cmdb/$(connection.key).json"
      shortcut   => "me.json",
      admit_keys => { "$(connection.key)" };

In this example, requesting the file me.json will transfer the file stored on the server under the name /var/cfengine/cmdb/SHA=....json to the requesting host, where it will be received as me.json. Note that the usage of the $(connection.*) variables is strictly limited to literal strings within the promiser and admit/deny lists; they cannot be passed to functions or stored in other variables.

With CFEngine Enteprise, access promises can be made about additional query data for reporting and orchestration.

  # Grant orchestration communication

  "did.*"
          comment => "Access to class context (enterprise)",
    resource_type => "context",
        admit_ips => { "127.0.0.1" };


  "value of my test_scalar, can expand variables here - $(sys.host)"
          comment => "Grant access to the string in quotes, by name test_scalar",
           handle => "test_scalar",
    resource_type => "literal",
        admit_ips => { "127.0.0.1" };

  "XYZ"
          comment => "Grant access to contents of persistent scalar variable XYZ",
    resource_type => "variable",
        admit_ips => { "127.0.0.1" };

  # Client grants access to CFEngine hub access

  "delta"
               comment => "Grant access to cfengine hub to collect report deltas",
         resource_type => "query",
    report_data_select => default_data_select_host,
                 admit_ips => { "127.0.0.1"  };
  "full"
               comment => "Grant access to cfengine hub to collect full report dump",
         resource_type => "query",
    report_data_select => default_data_select_host,
             admit_ips => { "127.0.0.1"  };

  policy_server::

  "collect_calls"
          comment => "Grant access to cfengine client to request the collection of its reports",
    resource_type => "query",
        admit_ips => { "10.1.2.0/24" };


}

Using the built-in report_data_select body default_data_select_host:

      report_data_select => default_data_select_host,
      admit => { @(def.policy_servers) };

    policy_server.enterprise::
      "$(query_types)"
      handle => "report_access_grant_$(query_types)_for_hub",
      comment => "Grant $(query_types) reporting query for the hub on the policy server",
      resource_type => "query",
      report_data_select => default_data_select_policy_hub,
      admit => { "127.0.0.1", @(def.policy_servers) };
}

The access promise allows overlapping promises to be made, and these are kept on a first-come-first-served basis. Thus file objects (promisers) should be listed in order of most-specific file first. In this way, specific promises will override less specific ones.

Attributes

admit_hostnames

Description: A list of hostnames or domains that should have access to the object.

Type: slist

Allowed input range: (arbitrary string)

Note: The host trying to access the object is identified using a reverse DNS lookup on the connecting IP. This introduces latency for every incoming connection. If possible, avoid this penalty by leaving admit_hostnames empty and only specifying numeric addresses and subnets in admit_ips.

To admit an entire domain, start the string with a dot .. This includes every hostname ending with the domain, but not a machine named after the domain itself.

For example, here we'll admit the entire domain .cfengine.com and the host www.cfengine3.com. A machine named cfengine.com would be refused access because it's not in the cfengine.com domain.

access:

   "/path/file"
   admit_hostnames => { ".cfengine.com", "www.cfengine3.com" };

See also: deny_hostnames, admit_ips, admit_keys

History: Introduced in CFEngine 3.6.0

admit_ips

Description: A list of IP addresses that should have access to the object.

Subnets are specified using CIDR notation. For example, here we'll admit one host, then a subnet, then everyone:

access:

   "/path/file"
   admit_ips => {"192.168.0.1", "192.168.0.0/24", "0.0.0.0/0"};

Type: slist

Allowed input range: (arbitrary string)

See also: deny_ips, admit_hostnames, admit_keys

History: Introduced in CFEngine 3.6.0

admit_keys

Description: A list of RSA keys of hosts that should have access to the object.

For example, here we'll admit the fictitious SHA key abcdef:

access:

   "/path/file"
   admit_keys => {"SHA=abcdef"};

In Community, MD5 keys are used, so similarly we can admit the fictitious MD5 key abcdef:

access:

   "/path/file"
   admit_keys => {"MD5=abcdef"};

Type: slist

Allowed input range: (arbitrary string)

See also: deny_keys, admit_hostnames, admit_ips

History: Introduced in CFEngine 3.6.0

deny_hostnames

Description: A list of hostnames that should be denied access to the object.

This overrides the grants in admit_hostnames, admit_ips and admit_keys.

To deny an entire domain, start the string with a dot .. This includes every hostname ending with the domain, but not a machine named after the domain itself.

For example, here we'll deny the entire domain .cfengine.com and the host www.cfengine3.com. A machine named cfengine.com would be allowed access (unless it's denied by other promises) because it's not in the cfengine.com domain.

access:

   "/path/file"
   deny_hostnames => { ".cfengine.com", "www.cfengine3.com" };

Type: slist

Allowed input range: (arbitrary string)

Notes: Failure to resolve a hostname or it's reverse results in a denial. Since this control is sensitive to temporary DNS failures, and cases, where reverse DNS is not present, it should be used with extreme scrutiny.

See also: admit_hostnames, deny_ips, deny_keys

History: Introduced in CFEngine 3.6.0

deny_ips

Description: A list of IP addresses that should be denied access to the object.

Subnets are specified using CIDR notation.

This overrides the grants in admit_hostnames, admit_ips and admit_keys.

For example, here we'll deny one host, then a subnet, then everyone:

access:

   "/path/file"
   deny_ips => {"192.168.0.1", "192.168.0.0/24", "0.0.0.0/0"};

Type: slist

Allowed input range: (arbitrary string)

See also: admit_ips, deny_hostnames, deny_keys

History: Introduced in CFEngine 3.6.0

deny_keys

Description: A list of RSA keys of hosts that should be denied access to the object.

This overrides the grants in admit_hostnames, admit_ips and admit_keys.

Type: slist

Allowed input range: (arbitrary string)

For example, here we'll deny the fictitious SHA key abcdef:

access:

   "/path/file"
   deny_keys => {"SHA=abcdef"};

In Community, MD5 keys are used, so similarly we can deny the fictitious MD5 key abcdef:

access:

   "/path/file"
   deny_keys => {"MD5=abcdef"};

See also: admit_keys, deny_hostnames, deny_ips

History: Introduced in CFEngine 3.6.0

admit

Description: The admit slist can contain a mix of entries in the syntax of admit_ips, admit_hostnames and admit_keys, and offers the same functionality. It's a legacy attribute that was split in the aforementioned attributes, and it's not recommended to use in new policy.

deny

Description: The deny slist can contain a mix of entries in the syntax of deny_ips, deny_hostnames and deny_keys, and offers the same functionality. It's a legacy attribute that was split in the aforementioned attributes, and it's not recommended to use in new policy. Example:

bundle server access_rules()
{
access:

  "/directory/"

    admit   => { "127.0.0.1", ".example.org" },
    deny    => { "badhost_1.example.org", "badhost_1.example.org" };
}

The best way to write the same policy would be the following:

bundle server access_rules()
{
access:

  "/directory/"

    admit_ips       => { "127.0.0.1" },
    admit_hostnames => { ".example.org" },
    deny_hostnames  => { "badhost_1.example.org", "badhost_1.example.org" };
}

Notes: Only regular expressions or exact matches are allowed in this list, as non-specific matches are too greedy for denial.

deny will be deprecated in CFEngine 3.7 in favor of deny_ips, deny_hostnames, and deny_keys.

maproot

Description: The maproot slist contains host names or IP addresses to grant full read-privilege on the server.

Normally users authenticated by the server are granted access only to files owned by them and no-one else. Even if the cf-serverd process runs with root privileges on the server side of a client-server connection, the client is not automatically granted access to download files owned by non-privileged users. If maproot is true then remote root users are granted access to all files.

A typical case where mapping is important is in making backups of many user files.

Type: slist

Allowed input range: (arbitrary string)

Example:

access:

 "/home"

     admit_hostnames => { "backup_host.example.org" },
 ifencrypted => "true",

     # Backup needs to have access to all users

     maproot => { "backup_host.example.org" };

Notes:

On Windows, cf-serverd, maproot is required to read files if the connecting user does not own the file on the server.

ifencrypted

Description: The ifencrypted menu option determines whether the current file access promise is conditional on the connection from the client being encrypted.

This option has no effect with the TLS CFEngine protocol, where encryption is always enabled.

If this flag is true a client cannot access the file object unless its connection is encrypted.

Type: boolean

Default value: false

Example:

access:

   "/path/file"

    admit_hostnames => { ".example.org" },
    ifencrypted => "true";

Note: This attribute is a noop when used with protocol_version 2 or greater.

See also: protocol_version, allowtlsversion, allowciphers, tls_min_version, tls_ciphers, encrypt, logencryptedtransfers, ifencrypted

report_data_select

This body is only available in CFEngine Enterprise.

Description: The report_data_select body restricts which data is included for query resources, and allows filtering of data reported to the CFEngine Enterprise server.

Use this body template to control the content of reports collected by the CFEngine Enterprise server, and to strip unwanted data (e.g. temporary variables) from reporting.

By default, no filtering is applied. If include and exclude rules are combined, then the exclude statement is applied to the subset from the include statement.

If more than one report_data_select body applies to the same host, all of them are applied.

Usage of this body is only allowed in conjunction with using resource_type => "query", as this is the resource type that is being affected.

Type: body report_data_select

Example:

body report_data_select report_data
{
    metatags_include => { "inventory", "compliance" };
    promise_handle_exclude => { "_.*" };
    monitoring_exclude => { "mem_.*swap" };
}

Example:

Here are the built-in report_data_select bodies default_data_select_host() and default_data_select_policy_hub():

      report_data_select => default_data_select_host,
      admit => { @(def.policy_servers) };

    policy_server.enterprise::
      "$(query_types)"
      handle => "report_access_grant_$(query_types)_for_hub",
      comment => "Grant $(query_types) reporting query for the hub on the policy server",
      resource_type => "query",
      report_data_select => default_data_select_policy_hub,
      admit => { "127.0.0.1", @(def.policy_servers) };
}

      report_data_select => default_data_select_policy_hub,
      admit => { "127.0.0.1", @(def.policy_servers) };
}

See also: Common Body Attributes

History: Introduced in Enterprise 3.5.0

metatags_exclude

Description: List of anchored regular expressions matching metatags of classes or vars to exclude from reporting.

Classes and variables with metatags matching any entry of that list will not be reported to the CFEngine Enterprise server.

When combined with metatags_include, this list is applied to the selected subset.

Type: slist

Allowed input range: .*

See also: metatags_include, promise_handle_exclude, monitoring_exclude

History: Introduced in CFEngine 3.6.0

metatags_include

Description: List of anchored regular expressions matching metatags of classes or vars to include in reporting.

Classes and variables with metatags matching any entry of that list will be reported to the CFENgine Enterprise server.

When combined with metatags_exclude, the exclude list is applied to the subset from this list.

Type: slist

Allowed input range: .*

See also: metatags_exclude, promise_handle_include, monitoring_include

History: Introduced in CFEngine 3.6.0

promise_handle_exclude

Description: List of anchored regular expressions matching promise handles to exclude from reporting.

Information about promises with handles that match any entry in that list will not be reported to the CFEngine Enterprise server.

When combined with promise_handle_include, this list is applied to the selected subset.

Type: slist

Allowed input range: .*

See also: promise_handle_include, metatags_exclude, monitoring_exclude

History: Introduced in CFEngine 3.6.0

promise_handle_include

Description: List of anchored regular expressions matching promise handles to include in reporting.

Information about promises with handles that match any entry in that list will be reported to the CFEngine Enterprise server.

When combined with promise_handle_exclude, the exclude list is applied to the subset from this list.

Type: slist

Allowed input range: .*

See also: promise_handle_exclude, metatags_include, monitoring_include

History: Introduced in CFEngine 3.6.0

monitoring_include

Description: List of anchored regular expressions matching monitoring objects to include in reporting.

Monitoring objects with names matching any entry in that list will be reported to the CFEngine Enterprise server.

When combined with monitoring_exclude, the exclude list is applied to the subset from this list.

Type: slist

Allowed input range: .*

See also: monitoring_exclude, promise_handle_include, metatags_include

History: Introduced in Enterprise 3.5.0

monitoring_exclude

Description: List of anchored regular expressions matching monitoring objects to exclude from reporting.

Monitoring objects with names matching any entry in that list will not be reported to the CFEngine Enterprise server.

When combined with monitoring_include, this list is applied to the selected subset.

Type: slist

Allowed input range: .*

See also: monitoring_include, promise_handle_exclude, metatags_exclude

History: Introduced in Enterprise 3.5.0

classes_include

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by meta-tags instead.

See also: metatags_include, metatags_exclude

classes_exclude

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by meta-tags instead.

See also: metatags_include, metatags_exclude

variables_include

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by meta-tags instead.

See also: metatags_include, metatags_exclude

variables_exclude

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by meta-tags instead.

See also: metatags_include, metatags_exclude

promise_notkept_log_include

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by handle instead.

See also: promise_handle_exclude

promise_notkept_log_exclude

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by handle instead.

See also: promise_handle_exclude

promise_repaired_log_include

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by handle instead.

See also: promise_handle_exclude

promise_repaired_log_exclude

Deprecated: This attribute is deprecated as of CFEngine 3.6.0. It performs no action and is kept for backwards compatibility. Filter data by handle instead.

See also: promise_handle_exclude

resource_type

Description: The resource_type is the type of object being granted access.

By default, access to resources granted by the server are files (resource_type => "path"). However, sometimes it is useful to cache literal strings, hints and data on the server for easy access (e.g. the contents of variables or hashed passwords). In the case of literal data, the promise handle serves as the reference identifier for queries. Queries are instigated by function calls by any agent.

Type: (menu option)

Allowed input range:

  • path
  • literal
  • context
  • query
  • variable
  • bundle

If the resource type is literal, CFEngine will grant access to a literal data string. This string is defined either by the promiser itself, but the name of the variable is the identifier given by the promise handle of the access promise, since the promiser string might be complex.

If the resource type is variable then the promiser is the name of a persistent scalar variable defined on the server-host. Currently persistent scalars are only used internally by Enterprise CFEngine to hold enumerated classes for orchestration purposes.

If you want to send the value of a policy defined variable in the server host (which for some reason is not available directly through policy on the client, e.g. because they have different policies), then you could use the following construction:

access:

  "$(variable_name)"

         handle => "variable_name",
  resource_type => "literal";

If the resource type is context, the promiser is treated as a regular expression to match persistent classes defined on the server host. If these are matched by the request from the client, they will be transmitted (See remoteclassesmatching()).

The term query may also be used in CFEngine Enterprise to query the server for data from embedded databases. This is currently for internal use only, and is used to grant access to report 'menus'. If the promiser of a query request is called collect_calls, this grants access to server peering collect-call tunneling (see also call_collect_interval).

If the resource type is bundle then the specific bundles are allowed to be remotely executed with cf-runagent --remote-bundles from the specified hosts. The promiser is an anchored regular expression.

Example:

bundle server access_rules()
{
access:

  "value of my test_scalar, can expand variables here - $(sys.host)"
    handle => "test_scalar",
    comment => "Grant access to contents of test_scalar VAR",
    resource_type => "literal",
    admit_ips => { "127.0.0.1" };

  "XYZ"
    resource_type => "variable",
    handle => "XYZ",
    admit_ips => { "$(sys.policy_hub)" };

 "delta"
    comment => "Grant access to cfengine hub to collect report deltas",
    resource_type => "query",
    admit_ips   => { "$(sys.policy_hub)"  };

 "full"
          comment => "Grant access to cfengine hub to collect full report dump",
    resource_type => "query",
        admit_ips => { "$(sys.policy_hub)"  };

 "magic_bundle"
          comment => "Grant access to the hub to activate magic_bundle with cf-runagent",
    resource_type => "bundle",
        admit_ips => { "$(sys.policy_hub)" };

 am_policy_hub::

  "collect_calls"
     comment       => "Enable call-collect report collection for the specific client",
     resource_type => "query",
     admit_ips     => { "1.2.3.4" };
}

History:

  • bundle resource_type added in 3.9.0

shortcut

Description: For file promisers, the server will give access to the file under its shortcut name.

Type: string

Allowed input range: (arbitrary string)

Example:

  "/var/cfengine/cmdb/$(connection.key).json"
    shortcut   => "me.json",
    admit_keys => { "$(connection.key)" };

In this example, requesting the file me.json will transfer the file stored on the server under the name /var/cfengine/cmdb/SHA=....json to the requesting host, where it will be received as me.json.

History: Introduced in CFEngine 3.6.0