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RFC 8341

Network Configuration Access Control Model

Pages: 58
STD 91
Obsoletes:  6536
Part 2 of 3 – Pages 14 to 31
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Top   ToC   RFC8341 - Page 14   prevText
3.2.  Datastore Access

   The same access control rules apply to all datastores that support
   the NACM -- for example, the candidate configuration datastore or the
   running configuration datastore.

   All conventional configuration datastores and the operational state
   datastore are controlled by the NACM.  Local files, remote files, or
   datastores accessed via the <url> parameter are not controlled by
   the NACM.

3.2.1.  Mapping New Datastores to NACM

   It is possible that new datastores will be defined over time for use
   with NETCONF.  The NACM MAY be applied to other datastores that have
   similar access rights as defined in the NACM.  To apply the NACM to a
   new datastore, the new datastore specification needs to define how it
   maps to the NACM CRUDX (Create, Read, Update, Delete, eXec) access
   rights.  It is possible that only a subset of the NACM access rights
   would be applicable.  For example, only retrieval access control
   would be needed for a read-only datastore.  Operations and access
   rights not supported by the NACM CRUDX model are outside the scope of
   this document.  A datastore does not need to use the NACM, e.g., the
   datastore specification defines something else or does not use access
   control.

3.2.2.  Access Rights

   A small set of hard-wired datastore access rights is needed to
   control access to all possible protocol operations, including vendor
   extensions to the standard protocol operation set.

   The CRUDX model can support all protocol operations:

   o  Create: allows the client to add a new data node instance to a
      datastore.

   o  Read: allows the client to read a data node instance from a
      datastore or receive the notification event type.

   o  Update: allows the client to update an existing data node instance
      in a datastore.

   o  Delete: allows the client to delete a data node instance from a
      datastore.

   o  eXec: allows the client to execute the operation.
Top   ToC   RFC8341 - Page 15
3.2.3.  RESTCONF Methods

   The RESTCONF protocol utilizes HTTP methods to perform datastore
   operations, similar to NETCONF.  The NACM procedures were originally
   written for NETCONF protocol operations, so the RESTCONF methods are
   mapped to NETCONF operations for the purpose of access control
   processing.  The enforcement procedures described within this
   document apply to both protocols unless explicitly stated otherwise.

   The request URI needs to be considered when processing RESTCONF
   requests on data resources:

   o  For HEAD and GET requests, any data nodes that are ancestor nodes
      of the target resource are considered to be part of the retrieval
      request for access control purposes.

   o  For PUT, PATCH, and DELETE requests, any data nodes that are
      ancestor nodes of the target resource are not considered to be
      part of the edit request for access control purposes.  The access
      operation for these nodes is considered to be "none".  The edit
      begins at the target resource.

   o  For POST requests on data resources, any data nodes that are
      specified in the request URI, including the target resource, are
      not considered to be part of the edit request for access control
      purposes.  The access operation for these nodes is considered to
      be "none".  The edit begins at a child node of the target
      resource, specified in the message body.
Top   ToC   RFC8341 - Page 16
   Not all RESTCONF methods are subject to access control.  The
   following table specifies how each method is mapped to NETCONF
   protocol operations.  The value "none" indicates that the NACM is not
   applied at all to the specific RESTCONF method.

   +---------+-----------------+---------------------+-----------------+
   | Method  | Resource class  | NETCONF operation   | Access          |
   |         |                 |                     | operation       |
   +---------+-----------------+---------------------+-----------------+
   | OPTIONS | all             | none                | none            |
   | HEAD    | all             | <get>, <get-config> | read            |
   | GET     | all             | <get>, <get-config> | read            |
   | POST    | datastore, data | <edit-config>       | create          |
   | POST    | operation       | specified operation | execute         |
   | PUT     | data            | <edit-config>       | create, update  |
   | PUT     | datastore       | <copy-config>       | update          |
   | PATCH   | data, datastore | <edit-config>       | update          |
   | DELETE  | data            | <edit-config>       | delete          |
   +---------+-----------------+---------------------+-----------------+

               Table 1: Mapping RESTCONF Methods to NETCONF

3.2.4.  <get> and <get-config> Operations

   The NACM access rights are not directly coupled to the <get> and
   <get-config> protocol operations but apply to all <rpc> operations
   that would result in a "read" access operation to the target
   datastore.  This section describes how these access rights apply to
   the specific access operations supported by the <get> and
   <get-config> protocol operations.

   Data nodes to which the client does not have read access are silently
   omitted, along with any descendants, from the <rpc-reply> message.
   This is done to allow NETCONF filters for <get> and <get-config> to
   function properly, instead of causing an "access-denied" error
   because the filter criteria would otherwise include unauthorized read
   access to some data nodes.  For NETCONF filtering purposes, the
   selection criteria are applied to the subset of nodes that the user
   is authorized to read, not the entire datastore.

3.2.5.  <edit-config> Operation

   The NACM access rights are not directly coupled to the <edit-config>
   "operation" attribute, although they are similar.  Instead, a NACM
   access right applies to all protocol operations that would result in
   a particular access operation to the target datastore.  This section
   describes how these access rights apply to the specific access
   operations supported by the <edit-config> protocol operation.
Top   ToC   RFC8341 - Page 17
   If the effective access operation is "none" (i.e.,
   default-operation="none") for a particular data node, then no access
   control is applied to that data node.  This is required to allow
   access to a subtree within a larger data structure.  For example, a
   user may be authorized to create a new "/interfaces/interface" list
   entry but not be authorized to create or delete its parent container
   ("/interfaces").  If the "/interfaces" container already exists in
   the target datastore, then the effective operation will be "none" for
   the "/interfaces" node if an "/interfaces/interface" list entry is
   edited.

   If the protocol operation would result in the creation of a datastore
   node and the user does not have "create" access permission for that
   node, the protocol operation is rejected with an "access-denied"
   error.

   If the protocol operation would result in the deletion of a datastore
   node and the user does not have "delete" access permission for that
   node, the protocol operation is rejected with an "access-denied"
   error.

   If the protocol operation would result in the modification of a
   datastore node and the user does not have "update" access permission
   for that node, the protocol operation is rejected with an
   "access-denied" error.

   A "merge" or "replace" <edit-config> operation may include data nodes
   that do not alter portions of the existing datastore.  For example, a
   container or list node may be present for naming purposes but does
   not actually alter the corresponding datastore node.  These unaltered
   data nodes are ignored by the server and do not require any access
   rights by the client.

   A "merge" <edit-config> operation may include data nodes but not
   include particular child data nodes that are present in the
   datastore.  These missing data nodes within the scope of a "merge"
   <edit-config> operation are ignored by the server and do not require
   any access rights by the client.

   The contents of specific restricted datastore nodes MUST NOT be
   exposed in any <rpc-error> elements within the reply.

   An <edit-config> operation may cause data nodes to be implicitly
   created or deleted as an implicit side effect of a requested
   operation.  For example, a YANG when-stmt expression may evaluate to
   a different result, causing data nodes to be deleted, or created with
   default values; or if a data node is created under one branch of a
   YANG choice-stmt, then all data nodes under the other branches are
Top   ToC   RFC8341 - Page 18
   implicitly removed.  No NACM access rights are required on any data
   nodes that are implicitly changed as a side effect of another allowed
   operation.

3.2.6.  <copy-config> Operation

   Access control for the <copy-config> protocol operation requires
   special consideration because the administrator may be replacing the
   entire target datastore.

   If the source of the <copy-config> protocol operation is the running
   configuration datastore and the target is the startup configuration
   datastore, the client is only required to have permission to execute
   the <copy-config> protocol operation.

   Otherwise:

   o  If the source of the <copy-config> operation is a datastore, then
      data nodes to which the client does not have read access are
      silently omitted.

   o  If the target of the <copy-config> operation is a datastore, the
      client needs access to the modified nodes.  Specifically:

      *  If the protocol operation would result in the creation of a
         datastore node and the user does not have "create" access
         permission for that node, the protocol operation is rejected
         with an "access-denied" error.

      *  If the protocol operation would result in the deletion of a
         datastore node and the user does not have "delete" access
         permission for that node, the protocol operation is rejected
         with an "access-denied" error.

      *  If the protocol operation would result in the modification of a
         datastore node and the user does not have "update" access
         permission for that node, the protocol operation is rejected
         with an "access-denied" error.

3.2.7.  <delete-config> Operation

   Access to the <delete-config> protocol operation is denied by
   default.  The "exec-default" leaf does not apply to this protocol
   operation.  Access control rules must be explicitly configured to
   allow invocation by a non-recovery session.
Top   ToC   RFC8341 - Page 19
3.2.8.  <commit> Operation

   The server MUST determine the exact nodes in the running
   configuration datastore that are actually different and only check
   "create", "update", and "delete" access permissions for this set of
   nodes, which could be empty.

   For example, if a session can read the entire datastore but only
   change one leaf, that session needs to be able to edit and commit
   that one leaf.

3.2.9.  <discard-changes> Operation

   The client is only required to have permission to execute the
   <discard-changes> protocol operation.  No datastore permissions are
   needed.

3.2.10.  <kill-session> Operation

   The <kill-session> operation does not directly alter a datastore.
   However, it allows one session to disrupt another session that is
   editing a datastore.

   Access to the <kill-session> protocol operation is denied by default.
   The "exec-default" leaf does not apply to this protocol operation.
   Access control rules must be explicitly configured to allow
   invocation by a non-recovery session.

3.3.  Model Components

   This section defines the conceptual components related to the access
   control model.

3.3.1.  Users

   A "user" is the conceptual entity that is associated with the access
   permissions granted to a particular session.  A user is identified by
   a string that is unique within the server.

   As described in [RFC6241], the username string is derived from the
   transport layer during session establishment.  If the transport layer
   cannot authenticate the user, the session is terminated.
Top   ToC   RFC8341 - Page 20
3.3.2.  Groups

   Access to a specific NETCONF protocol operation is granted to a
   session.  The session is associated with a group (i.e., not with
   a user).

   A group is identified by its name.  All group names are unique within
   the server.

   Access control is applied at the level of groups.  A group contains
   zero or more group members.

   A group member is identified by a username string.

   The same user can be a member of multiple groups.

3.3.3.  Emergency Recovery Session

   The server MAY support a recovery session mechanism, which will
   bypass all access control enforcement.  This is useful for
   restricting initial access and repairing a broken access control
   configuration.

3.3.4.  Global Enforcement Controls

   There are five global controls that are used to help control how
   access control is enforced.

3.3.4.1.  enable-nacm Switch

   A global "enable-nacm" on/off switch is provided to enable or disable
   all access control enforcement.  When this global switch is set to
   "true", all requests are checked against the access control rules and
   only permitted if configured to allow the specific access request.
   When this global switch is set to "false", all access requests are
   permitted.

3.3.4.2.  read-default Switch

   An on/off "read-default" switch is provided to enable or disable
   default access to receive data in replies and notifications.  When
   the "enable-nacm" global switch is set to "true", this global switch
   is relevant if no matching access control rule is found to explicitly
   permit or deny read access to the requested datastore data or
   notification event type.
Top   ToC   RFC8341 - Page 21
   When this global switch is set to "permit" and no matching access
   control rule is found for the datastore read or notification event
   requested, access is permitted.

   When this global switch is set to "deny" and no matching access
   control rule is found for the datastore read or notification event
   requested, access is denied.  This means that the requested data is
   not sent to the client.  See step 11 in Section 3.4.5 for details.

3.3.4.3.  write-default Switch

   An on/off "write-default" switch is provided to enable or disable
   default access to alter configuration data.  When the "enable-nacm"
   global switch is set to "true", this global switch is relevant if no
   matching access control rule is found to explicitly permit or deny
   write access to the requested datastore data.

   When this global switch is set to "permit" and no matching access
   control rule is found for the datastore write requested, access is
   permitted.

   When this global switch is set to "deny" and no matching access
   control rule is found for the datastore write requested, access is
   denied.  See step 12 in Section 3.4.5 for details.

3.3.4.4.  exec-default Switch

   An on/off "exec-default" switch is provided to enable or disable
   default access to execute protocol operations.  When the
   "enable-nacm" global switch is set to "true", this global switch is
   relevant if no matching access control rule is found to explicitly
   permit or deny access to the requested NETCONF protocol operation.

   When this global switch is set to "permit" and no matching access
   control rule is found for the NETCONF protocol operation requested,
   access is permitted.

   When this global switch is set to "deny" and no matching access
   control rule is found for the NETCONF protocol operation requested,
   access is denied.  See step 12 in Section 3.4.4 and step 13 in
   Section 3.4.5 for details.
Top   ToC   RFC8341 - Page 22
3.3.4.5.  enable-external-groups Switch

   When this global switch is set to "true", the group names reported by
   the transport layer for a session are used together with the locally
   configured group names to determine the access control rules for the
   session.

   When this switch is set to "false", the group names reported by the
   transport layer are ignored by the NACM.

3.3.5.  Access Control Rules

   There are four types of rules available in the NACM:

   module rule:  controls access for definitions in a specific YANG
      module, identified by its name.

   protocol operation rule:  controls access for a specific protocol
      operation, identified by its YANG module and name.

   data node rule:  controls access for a specific data node and its
      descendants, identified by its path location within the conceptual
      XML document for the data node.

   notification rule:  controls access for a specific notification event
      type, identified by its YANG module and name.

3.4.  Access Control Enforcement Procedures

   There are six separate phases that need to be addressed, four of
   which are related to the NETCONF message processing model
   (Section 3.1.3):

   1.  Initial operation

   2.  Session establishment

   3.  "access-denied" error handling

   4.  Incoming RPC message validation

   5.  Data node access validation

   6.  Outgoing <notification> authorization

   In addition, the initial startup mode for a NETCONF server, session
   establishment, and "access-denied" error-handling procedures also
   need to be considered.
Top   ToC   RFC8341 - Page 23
   The server MUST use the access control rules in effect at the time it
   starts processing the message.  The same access control rules MUST
   stay in effect for the processing of the entire message.

3.4.1.  Initial Operation

   Upon the very first startup of the NETCONF server, the access control
   configuration will probably not be present.  If it isn't, a server
   MUST NOT allow any write access to any session role except a recovery
   session.

   Access rules are enforced any time a request is initiated from a user
   session.  Access control is not enforced for server-initiated access
   requests, such as the initial load of the running configuration
   datastore, during bootup.

3.4.2.  Session Establishment

   The access control model applies specifically to the well-formed XML
   content transferred between a client and a server after session
   establishment has been completed and after the <hello> exchange has
   been successfully completed.

   Once session establishment is completed and a user has been
   authenticated, the transport layer reports the username and a
   possibly empty set of group names associated with the user to the
   NETCONF server.  The NETCONF server will enforce the access control
   rules, based on the supplied username, group names, and the
   configuration data stored on the server.

3.4.3.  "access-denied" Error Handling

   The "access-denied" error-tag is generated when the access control
   system denies access to either a request to invoke a protocol
   operation or a request to perform a particular access operation on
   the configuration datastore.

   A server MUST NOT include any information the client is not allowed
   to read in any <error-info> elements within the <rpc-error> response.
Top   ToC   RFC8341 - Page 24
3.4.4.  Incoming RPC Message Validation

   The diagram below shows the basic conceptual structure of the access
   control processing model for incoming NETCONF <rpc> messages within a
   server.

              NETCONF server
              +------------+
              |    XML     |
              |   message  |
              | dispatcher |
              +------------+
                     |
                     |
                     V
             +---------------+
             | <rpc> message |
             +---------------+
               |    |     |
               |    |     +--------------------------------+
               |    +---------------+                      |
               V                    V                      V
     +------------------+ +--------------------+ +--------------------+
     | vendor operation | | standard operation | | standard operation |
     |    <my-edit>     | |   <edit-config>    | |      <unlock>      |
     +------------------+ +--------------------+ +--------------------+
                 |                 |
                 |                 |
                 V                 V
                +----------------------+
                |    configuration     |
                |      datastore       |
                +----------------------+

                                 Figure 3

   Access control begins with the message dispatcher.

   After the server validates the <rpc> element and determines the
   namespace URI and the element name of the protocol operation being
   requested, the server verifies that the user is authorized to invoke
   the protocol operation.
Top   ToC   RFC8341 - Page 25
   The server MUST separately authorize every protocol operation by
   following these steps:

   1.   If the "enable-nacm" leaf is set to "false", then the protocol
        operation is permitted.

   2.   If the requesting session is identified as a recovery session,
        then the protocol operation is permitted.

   3.   If the requested operation is the NETCONF <close-session>
        protocol operation, then the protocol operation is permitted.

   4.   Check all the "group" entries to see if any of them contain a
        "user-name" entry that equals the username for the session
        making the request.  If the "enable-external-groups" leaf is
        "true", add to these groups the set of groups provided by the
        transport layer.

   5.   If no groups are found, continue with step 10.

   6.   Process all rule-list entries, in the order they appear in the
        configuration.  If a rule-list's "group" leaf-list does not
        match any of the user's groups, proceed to the next rule-list
        entry.

   7.   For each rule-list entry found, process all rules, in order,
        until a rule that matches the requested access operation is
        found.  A rule matches if all of the following criteria are met:

        *  The rule's "module-name" leaf is "*" or equals the name of
           the YANG module where the protocol operation is defined.

        *  Either (1) the rule does not have a "rule-type" defined or
           (2) the "rule-type" is "protocol-operation" and the
           "rpc-name" is "*" or equals the name of the requested
           protocol operation.

        *  The rule's "access-operations" leaf has the "exec" bit set or
           has the special value "*".

   8.   If a matching rule is found, then the "action" leaf is checked.
        If it is equal to "permit", then the protocol operation is
        permitted; otherwise, it is denied.

   9.   At this point, no matching rule was found in any rule-list
        entry.
Top   ToC   RFC8341 - Page 26
   10.  If the requested protocol operation is defined in a YANG module
        advertised in the server capabilities and the "rpc" statement
        contains a "nacm:default-deny-all" statement, then the protocol
        operation is denied.

   11.  If the requested protocol operation is the NETCONF
        <kill-session> or <delete-config>, then the protocol operation
        is denied.

   12.  If the "exec-default" leaf is set to "permit", then permit the
        protocol operation; otherwise, deny the request.

   If the user is not authorized to invoke the protocol operation, then
   an <rpc-error> is generated with the following information:

   error-tag:  access-denied

   error-path:  Identifies the requested protocol operation.  The
      following example represents the <edit-config> protocol operation
      in the NETCONF base namespace:

         <error-path
           xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
             /nc:rpc/nc:edit-config
         </error-path>

   If a datastore is accessed, either directly or as a side effect of
   the protocol operation, then the server MUST intercept the access
   operation and make sure that the user is authorized to perform the
   requested access operation on the specified data, as defined in
   Section 3.4.5.

3.4.5.  Data Node Access Validation

   If (1) a data node within a datastore is accessed or (2) an action or
   notification is tied to a data node, then the server MUST ensure that
   the user is authorized to perform the requested "read", "create",
   "update", "delete", or "execute" access operation on the specified
   data node.

   If an action is requested to be executed, the server MUST ensure that
   the user is authorized to perform the "execute" access operation on
   the requested action.

   If a notification tied to a data node is generated, the server MUST
   ensure that the user is authorized to perform the "read" access
   operation on the requested notification.
Top   ToC   RFC8341 - Page 27
   The data node access request is authorized by following these steps:

   1.   If the "enable-nacm" leaf is set to "false", then the access
        operation is permitted.

   2.   If the requesting session is identified as a recovery session,
        then the access operation is permitted.

   3.   Check all the "group" entries to see if any of them contain a
        "user-name" entry that equals the username for the session
        making the request.  If the "enable-external-groups" leaf is
        "true", add to these groups the set of groups provided by the
        transport layer.

   4.   If no groups are found, continue with step 9.

   5.   Process all rule-list entries, in the order they appear in the
        configuration.  If a rule-list's "group" leaf-list does not
        match any of the user's groups, proceed to the next rule-list
        entry.

   6.   For each rule-list entry found, process all rules, in order,
        until a rule that matches the requested access operation is
        found.  A rule matches if all of the following criteria are met:

        *  The rule's "module-name" leaf is "*" or equals the name of
           the YANG module where the requested data node is defined.

        *  Either (1) the rule does not have a "rule-type" defined or
           (2) the "rule-type" is "data-node" and the "path" matches the
           requested data node, action node, or notification node.  A
           path is considered to match if the requested node is the node
           specified by the path or is a descendant node of the path.

        *  For a "read" access operation, the rule's "access-operations"
           leaf has the "read" bit set or has the special value "*".

        *  For a "create" access operation, the rule's
           "access-operations" leaf has the "create" bit set or has the
           special value "*".

        *  For a "delete" access operation, the rule's
           "access-operations" leaf has the "delete" bit set or has the
           special value "*".
Top   ToC   RFC8341 - Page 28
        *  For an "update" access operation, the rule's
           "access-operations" leaf has the "update" bit set or has the
           special value "*".

        *  For an "execute" access operation, the rule's
           "access-operations" leaf has the "exec" bit set or has the
           special value "*".

   7.   If a matching rule is found, then the "action" leaf is checked.
        If it is equal to "permit", then the data node access is
        permitted; otherwise, it is denied.  For a "read" access
        operation, "denied" means that the requested data is not
        returned in the reply.

   8.   At this point, no matching rule was found in any rule-list
        entry.

   9.   For a "read" access operation, if the requested data node is
        defined in a YANG module advertised in the server capabilities
        and the data definition statement contains a
        "nacm:default-deny-all" statement, then the requested data node
        and all its descendants are not included in the reply.

   10.  For a "write" access operation, if the requested data node is
        defined in a YANG module advertised in the server capabilities
        and the data definition statement contains a
        "nacm:default-deny-write" or a "nacm:default-deny-all"
        statement, then the access request is denied for the data node
        and all its descendants.

   11.  For a "read" access operation, if the "read-default" leaf is set
        to "permit", then include the requested data node in the reply;
        otherwise, do not include the requested data node or any of its
        descendants in the reply.

   12.  For a "write" access operation, if the "write-default" leaf is
        set to "permit", then permit the data node access request;
        otherwise, deny the request.

   13.  For an "execute" access operation, if the "exec-default" leaf is
        set to "permit", then permit the request; otherwise, deny the
        request.
Top   ToC   RFC8341 - Page 29
3.4.6.  Outgoing <notification> Authorization

   Configuration of access control rules specifically for descendant
   nodes of the notification event type are outside the scope of this
   document.  If the user is authorized to receive the notification
   event type, then it is also authorized to receive any data it
   contains.

   If the notification is specified within a data subtree, as specified
   in [RFC7950], then read access to the notification is required.
   Processing continues as described in Section 3.4.5.

   The following figure shows the conceptual message processing model
   for outgoing <notification> messages.

                               NETCONF server
                              +------------+
                              |    XML     |
                              |   message  |
                              | generator  |
                              +------------+
                                    ^
                                    |
                            +----------------+
                            | <notification> |
                            |  generator     |
                            +----------------+
                                    ^
                                    |
                           +=================+
                           | <notification>  |
                           |  access control |
                           |  <eventType>    |
                           +=================+
                                    ^
                                    |
                        +------------------------+
                        | server instrumentation |
                        +------------------------+
                                  |     ^
                                  V     |
                         +----------------------+
                         |    configuration     |
                         |      datastore       |
                         +----------------------+

                                 Figure 4
Top   ToC   RFC8341 - Page 30
   The generation of a notification for a specific subscription
   [RFC5277] is authorized by following these steps:

   1.   If the "enable-nacm" leaf is set to "false", then the
        notification is permitted.

   2.   If the session is identified as a recovery session, then the
        notification is permitted.

   3.   If the notification is the NETCONF <replayComplete> or
        <notificationComplete> event type [RFC5277], then the
        notification is permitted.

   4.   Check all the "group" entries to see if any of them contain a
        "user-name" entry that equals the username for the session
        making the request.  If the "enable-external-groups" leaf is
        "true", add to these groups the set of groups provided by the
        transport layer.

   5.   If no groups are found, continue with step 10.

   6.   Process all rule-list entries, in the order they appear in the
        configuration.  If a rule-list's "group" leaf-list does not
        match any of the user's groups, proceed to the next rule-list
        entry.

   7.   For each rule-list entry found, process all rules, in order,
        until a rule that matches the requested access operation is
        found.  A rule matches if all of the following criteria are met:

        *  The rule's "module-name" leaf is "*" or equals the name of
           the YANG module where the notification is defined.

        *  Either (1) the rule does not have a "rule-type" defined or
           (2) the "rule-type" is "notification" and the
           "notification-name" is "*" or equals the name of the
           notification.

        *  The rule's "access-operations" leaf has the "read" bit set or
           has the special value "*".

   8.   If a matching rule is found, then the "action" leaf is checked.
        If it is equal to "permit", then permit the notification;
        otherwise, drop the notification for the associated
        subscription.

   9.   Otherwise, no matching rule was found in any rule-list entry.
Top   ToC   RFC8341 - Page 31
   10.  If the requested notification is defined in a YANG module
        advertised in the server capabilities and the "notification"
        statement contains a "nacm:default-deny-all" statement, then the
        notification is dropped for the associated subscription.

   11.  If the "read-default" leaf is set to "permit", then permit the
        notification; otherwise, drop the notification for the
        associated subscription.



(page 31 continued on part 3)

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