Internet DRAFT - draft-dbb-netmod-acl
draft-dbb-netmod-acl
netmod O. G. D. Dios
Internet-Draft S. Barguil
Intended status: Standards Track Telefonica
Expires: 27 April 2023 M. Boucadair
Orange
24 October 2022
Extensions to the Access Control Lists (ACLs) YANG Model
draft-dbb-netmod-acl-03
Abstract
RFC 8519 defines a YANG data model for Access Control Lists (ACLs).
This document discusses a set of extensions that fix many of the
limitations of the ACL model as initially defined in RFC 8519.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the Network Modeling
Working Group mailing list (netmod@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/netmod/.
Source for this draft and an issue tracker can be found at
https://github.com/oscargdd/draft-dbb-netmod-enhanced-acl.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 27 April 2023.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Problem Statement & Gap Analysis . . . . . . . . . . . . . . 4
3.1. Suboptimal Configuration: Lack of Support for Lists of
Prefixes . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Manageability: Impossibility to Use Aliases or Defined
Sets . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. Bind ACLs to Devices, Not Only Interfaces . . . . . . . . 9
3.4. Partial or Lack of IPv4/IPv6 Fragment Handling . . . . . 9
3.5. Suboptimal TCP Flags Handling . . . . . . . . . . . . . . 10
3.6. Rate-Limit Action . . . . . . . . . . . . . . . . . . . . 10
3.7. Payload-based Filtering . . . . . . . . . . . . . . . . . 10
3.8. Reuse the ACLs Content Across Several Devices . . . . . . 10
4. Overall Module Structure . . . . . . . . . . . . . . . . . . 11
4.1. Enhanced ACL . . . . . . . . . . . . . . . . . . . . . . 11
4.2. Defined sets . . . . . . . . . . . . . . . . . . . . . . 13
4.3. TCP Flags Handling . . . . . . . . . . . . . . . . . . . 13
4.4. Fragments Handling . . . . . . . . . . . . . . . . . . . 14
4.5. Rate-Limit Traffic . . . . . . . . . . . . . . . . . . . 18
5. YANG Modules . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1. Enhanced ACL . . . . . . . . . . . . . . . . . . . . . . 18
6. Security Considerations (TBC) . . . . . . . . . . . . . . . . 29
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
7.1. URI Registration . . . . . . . . . . . . . . . . . . . . 30
7.2. YANG Module Name Registration . . . . . . . . . . . . . . 30
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
8.1. Normative References . . . . . . . . . . . . . . . . . . 30
8.2. Informative References . . . . . . . . . . . . . . . . . 31
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 32
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32
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1. Introduction
[RFC8519] defines Access control lists (ACLs) as a user-ordered set
of filtering rules. The model targets the configuration of the
filtering behaviour of a device. However, the model structure, as
defined in [RFC8519], suffers from a set of limitations. This
document describes these limitations and proposes an enhanced ACL
structure. The YANG module in this document is solely based on
augmentations to the ACL YANG module defined in [RFC8519].
The motivation of such enhanced ACL structure is discussed in detail
in Section 3.
When managing ACLs, it is common for network operators to group match
elements in pre-defined sets. The consolidation into group matches
allows for reducing the number of rules, especially in large scale
networks. If it is needed, for example, to find a match against 100
IP addresses (or prefixes), a single rule will suffice rather than
creating individual Access Control Entries (ACEs) for each IP address
(or prefix). In doing so, implementations would optimize the
performance of matching lists vs multiple rules matching.
The enhanced ACL structure is also meant to facilitate the management
of network operators. Instead of entering the IP address or port
number literals, using user-named lists decouples the creation of the
rule from the management of the sets. Hence, it is possible to
remove/add entries to the list without redefining the (parent) ACL
rule.
In addition, the notion of Access Control List (ACL) and defined sets
is generalized so that it is not device-specific as per [RFC8519].
ACLs and defined sets may be defined at network / administrative
domain level and associated to devices. This approach facilitates
the reusability across multiple network elements. For example,
managing the IP prefix sets from a network level makes it easier to
maintain by the security groups.
Network operators maintain sets of IP prefixes that are related to
each other, e.g., deny-lists or accept-lists that are associated with
those provided by a VPN customer. These lists are maintained and
manipulated by security expert teams.
Note that ACLs are used locally in devices but are triggered by other
tools such as DDoS mitigation [RFC9132] or BGP Flow Spec [RFC8955]
[RFC8956]. Therefore, supporting means to easily map to the
filtering rules conveyed in messages triggered by these tools is
valuable from a network operation standpoint.
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2. Terminology
The keywords *MUST*, *MUST NOT*, *REQUIRED*, *SHALL*, *SHALL NOT*,
*SHOULD*, *SHOULD NOT*, *RECOMMENDED*, *MAY*, and *OPTIONAL*, when
they appear in this document, are to be interpreted as described in
[RFC2119].
The terminology for describing YANG modules is defined in [RFC7950].
The meaning of the symbols in the tree diagrams is defined in
[RFC8340].
In addition to the terms defined in [RFC8519], this document makes
use of the following terms:
* Defined set: Refers to reusable description of one or multiple
information elements (e.g., IP address, IP prefix, port number, or
ICMP type).
3. Problem Statement & Gap Analysis
3.1. Suboptimal Configuration: Lack of Support for Lists of Prefixes
IP prefix related data nodes, e.g., "destination-ipv4-network" or
"destination-ipv6-network", do not support handling a list of IP
prefixes, which may then lead to having to support large numbers of
ACL entries in a configuration file.
The same issue is encountered when ACLs have to be in place to
mitigate DDoS attacks (e.g., [RFC9132] when a set of sources are
involved in such an attack. The situation is even worse when both a
list of sources and destination prefixes are involved.
Figure 1 shows an example of the required ACL configuration for
filtering traffic from two prefixes.
{
"ietf-access-control-list:acls": {
"acl": [
{
"name": "first-prefix",
"type": "ipv6-acl-type",
"aces": {
"ace": [
{
"name": "my-test-ace",
"matches": {
"ipv6": {
"destination-ipv6-network":
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"2001:db8:6401:1::/64",
"source-ipv6-network":
"2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
},
{
"name": "second-prefix",
"type": "ipv6-acl-type",
"aces": {
"ace": [
{
"name": "my-test-ace",
"matches": {
"ipv6": {
"destination-ipv6-network":
"2001:db8:6401:c::/64",
"source-ipv6-network":
"2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
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}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 1: Example Illustrating Sub-optimal Use of the ACL Model
with a Prefix List
Such a configuration is suboptimal for both: - Network controllers
that need to manipulate large files. All or a subset for this
configuration will need to be passed to the underlying network
devices
* Devices may receive such a confirguration and thus will need to
maintain it locally.
(Figure 2 depicts an example of an optimized structure:
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{
"ietf-access-control-list:acls": {
"acl": [
{
"name": "prefix-list-support",
"type": "ipv6-acl-type",
"aces": {
"ace": [
{
"name": "my-test-ace",
"matches": {
"ipv6": {
"destination-ipv6-network": [
"2001:db8:6401:1::/64",
"2001:db8:6401:c::/64"
],
"source-ipv6-network":
"2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 2: Example Illustrating Optimal Use of the ACL Model in a
Network Context.
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3.2. Manageability: Impossibility to Use Aliases or Defined Sets
The same approach as the one discussed for IP prefixes can be
generalized by introduing the concept of "aliases" or "defined sets".
The defined sets are reusable definitions across several ACLs. Each
category is modelled in YANG as a list of parameters related to the
class it represents. The following sets can be considered:
* Prefix sets: Used to create lists of IPv4 or IPv6 prefixes.
* Protocol sets: Used to create a list of protocols.
* Port number sets: Used to create lists of TCP or UDP port values
(or any other transport protocol that makes uses of port numbers).
The identity of the protocols is identified by the protocol set,
if present. Otherwise, a set applies to any protocol.
* ICMP sets: Uses to create lists of ICMP-based filters. This
applies only when the protocol is set to ICMP or ICMPv6.
A candidate structure is shown in Figure 3:
+--rw defined-sets
| +--rw prefix-sets
| | +--rw prefix-set* [name]
| | +--rw name string
| | +--rw ip-prefix* inet:ip-prefix
| +--rw port-sets
| | +--rw port-set* [name]
| | +--rw name string
| | +--rw port* inet:port-number
| +--rw protocol-sets
| | +--rw protocol-set* [name]
| | +--rw name string
| | +--rw protocol-name* identityref
| +--rw icmp-type-sets
| +--rw icmp-type-set* [name]
| +--rw name string
| +--rw types* [type]
| +--rw type uint8
| +--rw code? uint8
| +--rw rest-of-header? binary
Figure 3: Examples of Defined Sets.
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Aliases may also be considered to managed resources that are
identified by a combination of various parameters as shown in the
candidate tree in Figure 4. Note that some aliases can be provided
by decomposing them into separate sets.
| +--rw aliases
| | +--rw alias* [name]
| | +--rw name string
| | +--rw prefix* inet:ip-prefix
| | +--rw port-range* [lower-port]
| | | +--rw lower-port inet:port-number
| | | +--rw upper-port? inet:port-number
| | +--rw protocol* uint8
| | +--rw fqdn* inet:domain-name
| | +--rw uri* inet:uri
| +--rw acls
| ...
| +--rw rest-of-header? binary
Figure 4: Examples of Aliases.
3.3. Bind ACLs to Devices, Not Only Interfaces
In the context of network management, an ACL may be enforced in many
network locations. As such, the ACL module should allow for binding
an ACL to multiple devices, not only (abstract) interfaces.
The ACL name must, thus, be unique at the scale of the network, but
the same name may be used in many devices when enforcing node-
specific ACLs.
3.4. Partial or Lack of IPv4/IPv6 Fragment Handling
[RFC8519] does not support fragment handling capability for IPv6 but
offers a partial support for IPv4 by means of 'flags'. Nevertheless,
the use of 'flags' is problematic since it does not allow a bitmask
to be defined. For example, setting other bits not covered by the
'flags' filtering clause in a packet will allow that packet to get
through (because it won't match the ACE).
Defining a new IPv4/IPv6 matching field called 'fragment' is thus
required to efficiently handle fragment-related filtering rules.
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3.5. Suboptimal TCP Flags Handling
[RFC8519] supports including flags in the TCP match fields, however
that structure does not support matching operations as those
supported in BGP Flow Spec. Defining this field to be defined as a
flag bitmask together with a set of operations is meant to
efficiently handle TCP flags filtering rules.
3.6. Rate-Limit Action
[RFC8519] specifies that forwarding actions can be 'accept' (i.e.,
accept matching traffic), 'drop' (i.e., drop matching traffic without
sending any ICMP error message), or 'reject' (i.e., drop matching
traffic and send an ICMP error message to the source). However,
there are situations where the matching traffic can be accepted, but
with a rate-limit policy. Such capability is not currently supported
by [RFC8519].
3.7. Payload-based Filtering
Some transport protocols use existing protocols (e.g., TCP or UDP) as
substrate. The match criteria for such protocols may rely upon the
'protocol' under 'l3', TCP/UDP match criteria, part of the TCP/UDP
payload, or a combination thereof. [RFC8519] does not support
matching based on the payload.
Likewise, the current version of the ACL model does not support
filtering of encapsulated traffic.
3.8. Reuse the ACLs Content Across Several Devices
Having a global network view of the ACLs is highly valuable for
service providers. An ACL could be defined and applied following the
hierarchy of the network topology. So, an ACL can be defined at the
network level and, then, that same ACL can be used (or referenced to)
in several devices (including termination points) within the same
network.
This network/device ACLs differentiation introduces several new
requirements, e.g.:
* An ACL name can be used at both network and device levels.
* An ACL content updated at the network level should imply a
transaction that updates the relevant content in all the nodes
using this ACL.
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* ACLs defined at the device level have a local meaning for the
specific node.
* A device can be associated with a router, a VRF, a logical system,
or a virtual node. ACLs can be applied in physical and logical
infrastructure.
4. Overall Module Structure
4.1. Enhanced ACL
module: ietf-acl-enh
augment /ietf-acl:acls/ietf-acl:acl:
+--rw defined-sets
+--rw ipv4-prefix-sets
| +--rw prefix-set* [name]
| +--rw name string
| +--rw description? string
| +--rw prefix* inet:ipv4-prefix
+--rw ipv6-prefix-sets
| +--rw prefix-set* [name]
| +--rw name string
| +--rw description? string
| +--rw prefix* inet:ipv6-prefix
+--rw port-sets
| +--rw port-set* [name]
| +--rw name string
| +--rw port* [id]
| +--rw id string
| +--rw (port)?
| +--:(port-range-or-operator)
| +--rw port-range-or-operator
| +--rw (port-range-or-operator)?
| +--:(range)
| | +--rw lower-port inet:port-number
| | +--rw upper-port inet:port-number
| +--:(operator)
| +--rw operator? operator
| +--rw port inet:port-number
+--rw protocol-sets
| +--rw protocol-set* [name]
| +--rw name string
| +--rw protocol* union
+--rw icmp-type-sets
+--rw icmp-type-set* [name]
+--rw name string
+--rw types* [type]
+--rw type uint8
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+--rw code? uint8
+--rw rest-of-header? binary
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:matches:
+--rw (payload)?
+--:(prefix-pattern)
+--rw prefix-pattern {match-on-payload}?
+--rw offset? identityref
+--rw offset-end? uint64
+--rw operator? operator
+--rw prefix? binary
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:matches/ietf-acl:l3/ietf-acl:ipv4:
+--rw ipv4-fragment
| +--rw operator? operator
| +--rw type? fragment-type
+--rw source-ipv4-prefix-list? leafref
+--rw destination-ipv4-prefix-list? leafref
+--rw next-header-set? leafref
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:matches/ietf-acl:l3/ietf-acl:ipv6:
+--rw ipv6-fragment
| +--rw operator? operator
| +--rw type? fragment-type
+--rw source-ipv6-prefix-list? leafref
+--rw destination-ipv6-prefix-list? leafref
+--rw protocol-set? leafref
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:matches/ietf-acl:l4/ietf-acl:tcp:
+--rw flags-bitmask
| +--rw operator? operator
| +--rw bitmask? uint16
+--rw source-tcp-port-set?
| -> ../../../../defined-sets/port-sets/port-set/name
+--rw destination-tcp-port-set?
-> ../../../../defined-sets/port-sets/port-set/name
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:matches/ietf-acl:l4/ietf-acl:udp:
+--rw source-udp-port-set?
| -> ../../../../defined-sets/port-sets/port-set/name
+--rw destination-udp-port-set?
-> ../../../../defined-sets/port-sets/port-set/name
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:matches/ietf-acl:l4/ietf-acl:icmp:
+--rw icmp-set? leafref
augment /ietf-acl:acls/ietf-acl:acl/ietf-acl:aces/ietf-acl:ace
/ietf-acl:actions:
+--rw rate-limit? decimal64
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Figure 5: Enhanced ACL tree
4.2. Defined sets
The augmented ACL structure includes several containers to manage
reusable sets of elements that can be matched in an ACL entry. Each
set is uniquely identified by a name, and can be called from the
relevant entry. The following sets are defined:
* IPv4 prefix set: It contains a list of IPv4 prefixes. A match
will be considered if the IP address (source or destination,
depending on the ACL entry) is contained in any of the prefixes.
* IPv6 prefix set: It contains a list of IPv6 prefixes. A match
will be considered if the IP address (source or destination,
depending on the ACL entry) is contained in any of the prefixes.
* Port sets: It contains a list of port numbers to be used in TCP /
UDP entries. The ports can be individual port numbers, a range of
ports, and an operation.
* Protocol sets: It contains a list of protocol values. Each
protocol can be identified either by a number (e.g., 17) or a name
(e.g., UDP).
* ICMP sets: It contains a list of ICMP types, each of them
identified by a type value, optionally the code and the rest of
the header.
4.3. TCP Flags Handling
The augmented ACL structure includes a new leaf 'flags-bitmask' to
better handle flags.
Clients that support both 'flags-bitmask' and 'flags' matching fields
MUST NOT set these fields in the same request.
Figure 6 shows an example of a request to install a filter to discard
incoming TCP messages having all flags unset.
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{
"ietf-access-control-list:acls": {
"acl": [{
"name": "tcp-flags-example",
"aces": {
"ace": [{
"name": "null-attack",
"matches": {
"tcp": {
"flags-bitmask": {
"operator": "not any",
"bitmask": 4095
}
}
},
"actions": {
"forwarding": "drop"
}
}]
}
}]
}
}
Figure 6: Example to Deny TCP Null Attack Messages
4.4. Fragments Handling
The augmented ACL structure includes a new leaf 'fragment' to better
handle fragments.
Clients that support both 'fragment' and 'flags' matching fields MUST
NOT set these fields in the same request.
Figure 7 shows the content of a POST request to allow the traffic
destined to 198.51.100.0/24 and UDP port number 53, but to drop all
fragmented packets. The following ACEs are defined (in this order):
* "drop-all-fragments" ACE: discards all fragments.
* "allow-dns-packets" ACE: accepts DNS packets destined to
198.51.100.0/24.
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{
"ietf-access-control-list:acls": {
"acl": [
{
"name": "dns-fragments",
"type": "ipv4-acl-type",
"aces": {
"ace": [
{
"name": "drop-all-fragments",
"matches": {
"ipv4": {
"ipv4-fragment": {
"operator": "match",
"type": "isf"
}
}
},
"actions": {
"forwarding": "drop"
}
},
{
"name": "allow-dns-packets",
"matches": {
"ipv4": {
"destination-ipv4-network": "198.51.100.0/24"
},
"udp": {
"destination-port": {
"operator": "eq",
"port": 53
}
},
"actions": {
"forwarding": "accept"
}
}
}
]
}
}
]
}
}
Figure 7: Example Illustrating Candidate Filtering of IPv4
Fragmented Packets.
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Figure 8 shows an example of the body of a POST request to allow the
traffic destined to 2001:db8::/32 and UDP port number 53, but to drop
all fragmented packets. The following ACEs are defined (in this
order):
* "drop-all-fragments" ACE: discards all fragments (including atomic
fragments). That is, IPv6 packets that include a Fragment header
(44) are dropped.
* "allow-dns-packets" ACE: accepts DNS packets destined to
2001:db8::/32.
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{
"ietf-access-control-list:acls": {
"acl": [
{
"name": "dns-fragments",
"type": "ipv6-acl-type",
"aces": {
"ace": [
{
"name": "drop-all-fragments",
"matches": {
"ipv6": {
"ipv6-fragment": {
"operator": "match",
"type": "isf"
}
}
},
"actions": {
"forwarding": "drop"
}
},
{
"name": "allow-dns-packets",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8::/32"
},
"udp": {
"destination-port": {
"operator": "eq",
"port": 53
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 8: Example Illustrating Candidate Filtering of IPv6
Fragmented Packets.
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4.5. Rate-Limit Traffic
In order to support rate-limiting (see Section 3.6), a new action
called "rate-limit" is defined.
(#example_5) shows an ACL example to rate-limit incoming SYNs during
a SYN flood attack.
{
"ietf-access-control-list:acls": {
"acl": [{
"name": "tcp-flags-example-with-rate-limit",
"aces": {
"ace": [{
"name": "rate-limit-syn",
"matches": {
"tcp": {
"flags-bitmask": {
"operator": "match",
"bitmask": 2
}
}
},
"actions": {
"forwarding": "accept",
"rate-limit": "20.00"
}
}]
}
}]
}
}
Figure 9: Example Rate-Limit Incoming TCP SYNs
5. YANG Modules
5.1. Enhanced ACL
<CODE BEGINS> file "ietf-acl-enh@2022-10-24.yang"
module ietf-acl-enh {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-acl-enh";
prefix enh-acl;
import ietf-inet-types {
prefix inet;
reference
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"RFC 6991: Common YANG Data Types";
}
import ietf-access-control-list {
prefix ietf-acl;
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs), Section 4.1";
}
import ietf-packet-fields {
prefix packet-fields;
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs), Section 4.2";
}
organization
"IETF NETMOD Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/netmod/>
WG List: <mailto:netmod@ietf.org>
Author: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Author: Samier Barguil
<mailto:samier.barguilgiraldo.ext@telefonica.com>
Author: Oscar Gonzalez de Dios
<mailto:oscar.gonzalezdedios@telefonica.com>";
description
"This module contains YANG definitions for enhanced ACLs.
Copyright (c) 2022 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Revised BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2022-10-24 {
description
"Initial revision.";
reference
"RFC XXXX: Extensions to the Access Control Lists (ACLs)
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YANG Model";
}
feature match-on-payload {
description
"Match based on a pattern is supported.";
}
identity offset-type {
description
"Base identity for payload offset type.";
}
identity layer3 {
base offset-type;
description
"IP header.";
}
identity layer4 {
base offset-type;
description
"Transport header (e.g., TCP or UDP).";
}
identity payload {
base offset-type;
description
"Transport payload. For example, this represents the beginning
of the TCP data right after any TCP options.";
}
typedef operator {
type bits {
bit not {
position 0;
description
"If set, logical negation of operation.";
}
bit match {
position 1;
description
"Match bit. This is a bitwise match operation
defined as '(data & value) == value'.";
}
bit any {
position 2;
description
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"Any bit. This is a match on any of the bits in
bitmask. It evaluates to 'true' if any of the bits
in the value mask are set in the data,
i.e., '(data & value) != 0'.";
}
}
description
"Specifies how to apply the defined bitmask.
'any' and 'match' bits must not be set simultaneously.";
}
typedef fragment-type {
type bits {
bit df {
position 0;
description
"Don't fragment bit for IPv4.
Must be set to 0 when it appears in an IPv6 filter.";
}
bit isf {
position 1;
description
"Is a fragment.";
}
bit ff {
position 2;
description
"First fragment.";
}
bit lf {
position 3;
description
"Last fragment.";
}
}
description
"Different fragment types to match against.";
}
grouping tcp-flags {
description
"Operations on TCP flags.";
leaf operator {
type operator;
default "match";
description
"How to interpret the TCP flags.";
}
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leaf bitmask {
type uint16;
description
"The bitmask matches the last 4 bits of byte 12
and byte 13 of the TCP header. For clarity, the 4 bits
of byte 12 corresponding to the TCP data offset field
are not included in any matching.";
}
}
grouping fragment-fields {
description
"Operations on fragment types.";
leaf operator {
type operator;
default "match";
description
"How to interpret the fragment type.";
}
leaf type {
type fragment-type;
description
"What fragment type to look for.";
}
}
grouping payload {
description
"Operations on payload match.";
leaf offset {
type identityref {
base offset-type;
}
description
"Indicates the payload offset.";
}
leaf offset-end {
type uint64;
description
"Indicates the number of bytes to cover when
performing the prefix match.";
}
leaf operator {
type operator;
default "match";
description
"How to interpret the prefix match.";
}
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leaf prefix {
type binary;
description
"The pattern to match against.";
}
}
augment "/ietf-acl:acls/ietf-acl:acl" {
description
"add a new container to store sets (prefix
sets, port sets, etc";
container defined-sets {
description
"Predefined sets of attributes used in policy match
statements.";
container ipv4-prefix-sets {
description
"Data definitions for a list of IPv4 or IPv6
prefixes which are matched as part of a policy.";
list prefix-set {
key "name";
description
"List of the defined prefix sets.";
leaf name {
type string;
description
"Name of the prefix set -- this is used as a label to
reference the set in match conditions.";
}
leaf description {
type string;
description
"Defined Set description.";
}
leaf-list prefix {
type inet:ipv4-prefix;
description
"List of IPv4 prefixes to be used in match
conditions.";
}
}
}
container ipv6-prefix-sets {
description
"Data definitions for a list of IPv6 prefixes
which are matched as part of a policy.";
list prefix-set {
key "name";
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description
"List of the defined prefix sets.";
leaf name {
type string;
description
"Name of the prefix set -- this is used as a label to
reference the set in match conditions.";
}
leaf description {
type string;
description
"A textual description of the prefix list.";
}
leaf-list prefix {
type inet:ipv6-prefix;
description
"List of IPv6 prefixes to be used in match
conditions.";
}
}
}
container port-sets {
description
"Data definitions for a list of ports which can
be matched in policies.";
list port-set {
key "name";
description
"List of port set definitions.";
leaf name {
type string;
description
"Name of the port set -- this is used as a label to
reference the set in match conditions.";
}
list port {
key "id";
description
"Port numbers along with the operator on which to
match.";
leaf id {
type string;
description
"Identifier of the list of port numbers.";
}
choice port {
description
"Choice of specifying the port number or referring
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to a group of port numbers.";
container port-range-or-operator {
description
"Indicates a set of ports.";
uses packet-fields:port-range-or-operator;
}
}
}
}
}
container protocol-sets {
description
"Data definitions for a list of protocols which can
be matched in policies.";
list protocol-set {
key "name";
description
"List of protocol set definitions.";
leaf name {
type string;
description
"Name of the protocols set -- this is used as a label to
reference the set in match conditions.";
}
leaf-list protocol {
type union {
type uint8;
type string; //Check if we can reuse an IANA-maintained module
}
description
"Value of the protocl set.";
}
}
}
container icmp-type-sets {
description
"Data definitions for a list of ICMP types which can
be matched in policies.";
list icmp-type-set {
key "name";
description
"List of ICMP type set definitions.";
leaf name {
type string;
description
"Name of the ICMP type set -- this is used as a label to
reference the set in match conditions.";
}
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list types {
key "type";
description
"Includes a list of ICMP types.";
uses packet-fields:acl-icmp-header-fields;
}
}
}
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:matches" {
description
"Add a new match types.";
choice payload {
description
"Match a prefix pattern.";
container prefix-pattern {
if-feature "match-on-payload";
description
"Rule to perform payload-based match.";
uses payload;
}
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:matches/ietf-acl:l3/ietf-acl:ipv4" {
description
"Handle non-initial and initial fragments for IPv4 packets.";
container ipv4-fragment {
description
"Indicates how to handle IPv4 fragments.";
uses fragment-fields;
}
leaf source-ipv4-prefix-list {
type leafref {
path "../../../../defined-sets/ipv4-prefix-sets/prefix-set/name";
}
description
"A reference to a prefix list to match the source address.";
}
leaf destination-ipv4-prefix-list {
type leafref {
path "../../../../defined-sets/ipv4-prefix-sets/prefix-set/name";
}
description
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"A reference to a prefix list to match the destination address.";
}
leaf next-header-set {
type leafref {
path "../../../../defined-sets/protocol-sets/protocol-set/name";
}
description
"A reference to a protocol set to match the next-header field.";
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:matches/ietf-acl:l3/ietf-acl:ipv6" {
description
"Handles non-initial and initial fragments for IPv6 packets.";
container ipv6-fragment {
description
"Indicates how to handle IPv6 fragments.";
uses fragment-fields;
}
leaf source-ipv6-prefix-list {
type leafref {
path "../../../../defined-sets/ipv6-prefix-sets/prefix-set/name";
}
description
"A reference to a prefix list to match the source address.";
}
leaf destination-ipv6-prefix-list {
type leafref {
path "../../../../defined-sets/ipv6-prefix-sets/prefix-set/name";
}
description
"A reference to a prefix list to match the destination address.";
}
leaf protocol-set {
type leafref {
path "../../../../defined-sets/protocol-sets/protocol-set/name";
}
description
"A reference to a protocol set to match the protocol field.";
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:matches/ietf-acl:l4/ietf-acl:tcp" {
description
"Handles TCP flags and port sets.";
container flags-bitmask {
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description
"Indicates how to handle TCP flags.";
uses tcp-flags;
}
leaf source-tcp-port-set {
type leafref {
path "../../../../defined-sets/port-sets/port-set/name";
}
description
"A reference to a port set to match the source port.";
}
leaf destination-tcp-port-set {
type leafref {
path "../../../../defined-sets/port-sets/port-set/name";
}
description
"A reference to a port set to match the destination port.";
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:matches/ietf-acl:l4/ietf-acl:udp" {
description
"Handle UDP port sets.";
leaf source-udp-port-set {
type leafref {
path "../../../../defined-sets/port-sets/port-set/name";
}
description
"A reference to a port set to match the source port.";
}
leaf destination-udp-port-set {
type leafref {
path "../../../../defined-sets/port-sets/port-set/name";
}
description
"A reference to a port set to match the destination port.";
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:matches/ietf-acl:l4/ietf-acl:icmp" {
description
"Handle ICMP type sets.";
leaf icmp-set {
type leafref {
path "../../../../defined-sets/icmp-type-sets/icmp-type-set/name";
}
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description
"A reference to an ICMP type set to match the ICMP type field.";
}
}
augment "/ietf-acl:acls/ietf-acl:acl/ietf-acl:aces"
+ "/ietf-acl:ace/ietf-acl:actions" {
description
"Rate-limit action.";
leaf rate-limit {
when "../ietf-acl:forwarding = 'ietf-acl:accept'" {
description
"Rate-limit valid only when accept action is used.";
}
type decimal64 {
fraction-digits 2;
}
units "bytes per second";
description
"Indicates a rate-limit for the matched traffic.";
}
}
}
<CODE ENDS>
6. Security Considerations (TBC)
The YANG modules specified in this document define a schema for data
that is designed to be accessed via network management protocol such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The Network Configuration Access Control Model (NACM) [RFC8341]
provides the means to restrict access for particular NETCONF or
RESTCONF users to a preconfigured subset of all available NETCONF or
RESTCONF protocol operations and content.
There are a number of data nodes defined in this YANG module that are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
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* TBC
Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get, get-config, or
notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
* TBC
7. IANA Considerations
7.1. URI Registration
This document requests IANA to register the following URI in the "ns"
subregistry within the "IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-acl-enh
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
7.2. YANG Module Name Registration
This document requests IANA to register the following YANG module in
the "YANG Module Names" subregistry [RFC6020] within the "YANG
Parameters" registry.
name: ietf-acl-enh
namespace: urn:ietf:params:xml:ns:yang:ietf-ietf-acl-enh
maintained by IANA: N
prefix: enh-acl
reference: RFC XXXX
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/rfc/rfc3688>.
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[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/rfc/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/rfc/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/rfc/rfc6242>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/rfc/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/rfc/rfc8040>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/rfc/rfc8341>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.
[RFC8519] Jethanandani, M., Agarwal, S., Huang, L., and D. Blair,
"YANG Data Model for Network Access Control Lists (ACLs)",
RFC 8519, DOI 10.17487/RFC8519, March 2019,
<https://www.rfc-editor.org/rfc/rfc8519>.
[RFC8956] Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
"Dissemination of Flow Specification Rules for IPv6",
RFC 8956, DOI 10.17487/RFC8956, December 2020,
<https://www.rfc-editor.org/rfc/rfc8956>.
8.2. Informative References
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/rfc/rfc8340>.
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[RFC8955] Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
Bacher, "Dissemination of Flow Specification Rules",
RFC 8955, DOI 10.17487/RFC8955, December 2020,
<https://www.rfc-editor.org/rfc/rfc8955>.
[RFC9132] Boucadair, M., Ed., Shallow, J., and T. Reddy.K,
"Distributed Denial-of-Service Open Threat Signaling
(DOTS) Signal Channel Specification", RFC 9132,
DOI 10.17487/RFC9132, September 2021,
<https://www.rfc-editor.org/rfc/rfc9132>.
Appendix A. Acknowledgements
Many thanks to Jon Shallow and Miguel Cros for the review and
comments to the document, incuding priror to publishing the document.
Thanks for Qin Wu for the comments and suggestions.
This work is partially supported by the European Commission under
Horizon 2020 Secured autonomic traffic management for a Tera of SDN
flows (Teraflow) project (grant agreement number 101015857).
Authors' Addresses
Oscar Gonzalez de Dios
Telefonica
Email: oscar.gonzalezdedios@telefonica.com
Samier Barguil
Telefonica
Email: samier.barguilgiraldo.ext@telefonica.com
Mohamed Boucadair
Orange
Email: mohamed.boucadair@orange.com
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