diff --git a/docs/antrea-network-policy.md b/docs/antrea-network-policy.md index 1e3304d7950..f53663f5720 100644 --- a/docs/antrea-network-policy.md +++ b/docs/antrea-network-policy.md @@ -27,25 +27,26 @@ - [Ordering based on Tier priority](#ordering-based-on-tier-priority) - [Ordering based on policy priority](#ordering-based-on-policy-priority) - [Rule enforcement based on priorities](#rule-enforcement-based-on-priorities) +- [Advanced peer selection mechanisms of Antrea-native Policies](#advanced-peer-selection-mechanisms-of-antrea-native-policies) + - [Selecting Namespace by Name](#selecting-namespace-by-name) + - [K8s clusters with version 1.21 and above](#k8s-clusters-with-version-121-and-above) + - [K8s clusters with version 1.20 and below](#k8s-clusters-with-version-120-and-below) + - [Selecting Pods in the same Namespace with Self](#selecting-pods-in-the-same-namespace-with-self) + - [FQDN based filtering](#fqdn-based-filtering) + - [Node Selector](#node-selector) + - [toServices egress rules](#toservices-egress-rules) + - [ServiceAccount based selection](#serviceaccount-based-selection) - [ClusterGroup](#clustergroup) - [The ClusterGroup resource](#the-clustergroup-resource) - [kubectl commands for ClusterGroup](#kubectl-commands-for-clustergroup) -- [Audit logging for Antrea-native policies](#audit-logging-for-antrea-native-policies) -- [Select Namespace by Name](#select-namespace-by-name) - - [K8s clusters with version 1.21 and above](#k8s-clusters-with-version-121-and-above) - - [K8s clusters with version 1.20 and below](#k8s-clusters-with-version-120-and-below) -- [FQDN based filtering](#fqdn-based-filtering) -- [Node Selector](#node-selector) -- [toServices instruction](#toservices-instruction) -- [ServiceAccount based selection](#serviceaccount-based-selection) - [RBAC](#rbac) -- [Notes](#notes) +- [Notes and constraints](#notes-and-constraints) ## Summary -Antrea supports standard K8s NetworkPolicies to secure traffic between Pods. -These NetworkPolicies are written from an application developer's perspective, +Antrea supports standard K8s NetworkPolicies to secure ingress/egress traffic for +Pods. These NetworkPolicies are written from an application developer's perspective, hence they lack the ability to gain a finer-grained control over the security policies that a cluster administrator would require. This document describes a few new CRDs supported by Antrea to provide the administrator with more control @@ -61,11 +62,12 @@ Antrea-native policy CRDs. Antrea supports grouping Antrea-native policy CRDs together in a tiered fashion to provide a hierarchy of security policies. This is achieved by setting the `tier` field when defining an Antrea-native policy CRD (e.g. an Antrea -ClusterNetworkPolicy object) to the appropriate tier name. Each tier has a -priority associated with it, which determines its relative order among all tiers. +ClusterNetworkPolicy object) to the appropriate Tier name. Each Tier has a +priority associated with it, which determines its relative order among other Tiers. -**Note**: K8s NetworkPolicies will be enforced once all tiers have been -enforced. +**Note**: K8s NetworkPolicies will be enforced once all policies in all Tiers (except +for the baseline Tier) have been enforced. For more information, refer to the following +[Static Tiers section](#static-tiers) ### Tier CRDs @@ -88,7 +90,7 @@ spec: Tiers have the following characteristics: - Policies can associate themselves with an existing Tier by setting the `tier` - field in a Antrea NetworkPolicy CRD spec to the Tier's name. + field in an Antrea NetworkPolicy CRD spec to the Tier's name. - A Tier must exist before an Antrea-native policy can reference it. - Policies associated with higher ordered (low `priority` value) Tiers are enforced first. @@ -100,10 +102,10 @@ Tiers have the following characteristics: Antrea release 0.9.x introduced support for 5 static tiers. These static tiers have been removed in favor of Tier CRDs as mentioned in the previous section. -On startup, antrea-controller will create 5 Read-Only Tier resources +On startup, antrea-controller will create 5 static, read-only Tier CRD resources corresponding to the static tiers for default consumption, as well as a "baseline" Tier CRD object, that will be enforced after developer-created K8s NetworkPolicies. -The details for these tiers are shown below: +The details for these Tiers are shown below: ```text Emergency -> Tier name "emergency" with priority "50" @@ -117,32 +119,36 @@ The details for these tiers are shown below: Any Antrea-native policy CRD referencing a static tier in its spec will now internally reference the corresponding Tier resource, thus maintaining the order of enforcement. -The static tier resources are created as follows in the relative order of +The static Tier CRD Resources are created as follows in the relative order of precedence compared to K8s NetworkPolicies: ```text Emergency > SecurityOps > NetworkOps > Platform > Application > K8s NetworkPolicy > Baseline ``` -Thus, all Antrea-native Policy resources associated with the "emergency" tier will be +Thus, all Antrea-native Policy resources associated with the "emergency" Tier will be enforced before any Antrea-native Policy resource associated with any other -tiers, until a match occurs, in which case the policy rule's `action` will be +Tiers, until a match occurs, in which case the policy rule's `action` will be applied. **Any Antrea-native Policy resource without a `tier` name set in its spec -will be associated with the "application" tier.** Policies associated with the first -5 static, read-only tiers, as well as with all the custom tiers created with a priority +will be associated with the "application" Tier.** Policies associated with the first +5 static, read-only Tiers, as well as with all the custom Tiers created with a priority value lower than 250 (priority values greater than or equal to 250 are not allowed -for custom tiers), will be enforced before K8s NetworkPolicies. -Policies created in the "baseline" tier, on the other hand, will have lower precedence +for custom Tiers), will be enforced before K8s NetworkPolicies. + +Policies created in the "baseline" Tier, on the other hand, will have lower precedence than developer-created K8s NetworkPolicies, which comes in handy when administrators want to enforce baseline policies like "default-deny inter-namespace traffic" for some specific Namespace, while still allowing individual developers to lift the restriction if needed using K8s NetworkPolicies. + Note that baseline policies cannot counteract the isolated Pod behavior provided by -K8s NetworkPolicies. If a Pod becomes isolated because a K8s NetworkPolicy is applied -to it, and the policy does not explicitly allow communications with another Pod, -this behavior cannot be changed by creating an Antrea-native policy with an "allow" -action in the "baseline" tier. For this reason, it generally does not make sense to -create policies in the "baseline" tier with the "allow" action. +K8s NetworkPolicies. To read more about this Pod isolation behavior, refer to [this +document](https://kubernetes.io/docs/concepts/services-networking/network-policies/#the-two-sorts-of-pod-isolation). +If a Pod becomes isolated because a K8s NetworkPolicy is applied to it, and the policy +does not explicitly allow communications with another Pod, this behavior cannot be changed +by creating an Antrea-native policy with an "allow" action in the "baseline" Tier. +For this reason, it generally does not make sense to create policies in the "baseline" +Tier with the "allow" action. ### kubectl commands for Tier @@ -165,7 +171,7 @@ The following kubectl commands can be used to retrieve Tier resources: kubectl get tiers --sort-by=.spec.priority ``` -All of the above commands produce output similar to what is shown below: +All the above commands produce output similar to what is shown below: ```text NAME PRIORITY AGE @@ -199,45 +205,45 @@ kind: ClusterNetworkPolicy metadata: name: acnp-with-stand-alone-selectors spec: - priority: 5 - tier: securityops - appliedTo: - - podSelector: - matchLabels: - role: db - - namespaceSelector: - matchLabels: - env: prod - ingress: - - action: Allow - from: - - podSelector: - matchLabels: - role: frontend - - podSelector: - matchLabels: - role: nondb - namespaceSelector: - matchLabels: - role: db - ports: - - protocol: TCP - port: 8080 - endPort: 9000 - - protocol: TCP - port: 6379 - name: AllowFromFrontend - enableLogging: false - egress: - - action: Drop - to: - - ipBlock: - cidr: 10.0.10.0/24 - ports: - - protocol: TCP - port: 5978 - name: DropToThirdParty - enableLogging: true + priority: 5 + tier: securityops + appliedTo: + - podSelector: + matchLabels: + role: db + - namespaceSelector: + matchLabels: + env: prod + ingress: + - action: Allow + from: + - podSelector: + matchLabels: + role: frontend + - podSelector: + matchLabels: + role: nondb + namespaceSelector: + matchLabels: + role: db + ports: + - protocol: TCP + port: 8080 + endPort: 9000 + - protocol: TCP + port: 6379 + name: AllowFromFrontend + enableLogging: false + egress: + - action: Drop + to: + - ipBlock: + cidr: 10.0.10.0/24 + ports: + - protocol: TCP + port: 5978 + name: DropToThirdParty + enableLogging: true ``` #### ACNP with ClusterGroup reference @@ -310,7 +316,9 @@ spec: priority: 5 tier: securityops appliedTo: - - namespaceSelector: {} # Selects all Namespaces in the cluster + - namespaceSelector: # Selects all non-system Namespaces in the cluster + matchExpressions: + - {key: kubernetes.io/metadata.name, operator: NotIn, values: [kube-system]} ingress: - action: Pass from: @@ -363,22 +371,22 @@ kind: ClusterNetworkPolicy metadata: name: acnp-drop-to-services spec: - priority: 5 - tier: securityops - appliedTo: - - podSelector: - matchLabels: - role: client - namespaceSelector: - matchLabels: - env: prod - egress: - - action: Drop - toServices: - - name: svcName - namespace: svcNamespace - name: DropToServices - enableLogging: true + priority: 5 + tier: securityops + appliedTo: + - podSelector: + matchLabels: + role: client + namespaceSelector: + matchLabels: + env: prod + egress: + - action: Drop + toServices: + - name: svcName + namespace: svcNamespace + name: DropToServices + enableLogging: true ``` **spec**: The ClusterNetworkPolicy `spec` has all the information needed to @@ -397,6 +405,7 @@ An IPBlock ClusterGroup referenced in an `appliedTo` field will be ignored, and the policy will have no effect. This `appliedTo` field must not be set, if `appliedTo` per rule is used. + In the [first example](#acnp-with-stand-alone-selectors), the policy applies to Pods, which either match the labels "role=db" in all the Namespaces, or are from Namespaces which match the labels "env=prod". @@ -449,6 +458,7 @@ name of some other rules in the same policy, it will cause a conflict, and the policy will be rejected. A ClusterGroup name can be set in the `group` field of an ingress `from` section in place of stand-alone selectors to allow traffic from workloads/ipBlocks set in the ClusterGroup. + The [first example](#acnp-with-stand-alone-selectors) policy contains a single rule, which allows matched traffic on a single port, from one of two sources: the first specified by a `podSelector` and the second specified by a combination of a `podSelector` and a @@ -476,7 +486,9 @@ a rule, it will be auto-generated by Antrea. The rule name auto-generation proce is the same as ingress rules. A ClusterGroup name can be set in the `group` field of a egress `to` section in place of stand-alone selectors to allow traffic to workloads/ipBlocks set in the ClusterGroup. -`toServices` field contains a list of combinations of Service Namespace and Service Name to match traffic to this Service. +`toServices` field contains a list of combinations of Service Namespace and Service Name +to match traffic to this Service. + More details can be found in the [toServices](#toservices-instruction) section. The [first example](#acnp-with-stand-alone-selectors) policy contains a single rule, which drops matched traffic on a single port, to the 10.0.10.0/24 subnet specified by the `ipBlock` field. @@ -519,7 +531,10 @@ The rules are logged in the following format: 2021/06/24 23:56:41.346165 AntreaPolicyEgressRule AntreaNetworkPolicy:default/test-anp Drop 44900 10.10.1.65 35402 10.0.0.5 80 TCP 60 [3 packets in 1.011379442s] ``` -**`appliedTo` per rule**: A ClusterNetworkPolicy ingress or egress rule may +Fluentd can be used to assist with collecting and analyzing the logs. Refer to the +[Fluentd cookbook](cookbooks/fluentd) for documentation. + +**appliedTo per rule**: A ClusterNetworkPolicy ingress or egress rule may optionally contain the `appliedTo` field. Semantically, the `appliedTo` field per rule is similar to the `appliedTo` field at the policy level, except that it is valid for that rule itself, as opposed to spanning over all the rules. @@ -532,8 +547,8 @@ Usage of ClusterGroups along with stand-alone selectors is not allowed. ### Behavior of *to* and *from* selectors -There are seven kinds of selectors that can be specified in an ingress `from` -section or egress `to` section: +The following selectors can be specified in an ingress `from` section or egress `to` +section when defining networking peers for policy rules: **podSelector**: This selects particular Pods from all Namespaces as "sources", if set in `ingress` section, or as "destinations", if set in `egress` section. @@ -542,26 +557,26 @@ if set in `ingress` section, or as "destinations", if set in `egress` section. are grouped as `ingress` "sources" or `egress` "destinations". Cannot be set with `namespaces` field. -**podSelector** and **namespaceSelector**: A single to/from entry that +**podSelector** and **namespaceSelector**: A single to/from entry that specifies both namespaceSelector and podSelector selects particular Pods within particular Namespaces. **nodeSelector**: This selects particular Nodes in cluster. The selected Node's IPs will be set as "sources" if `nodeSelector` set in `ingress` section, or as -"destinations" if is set in the `egress` section. - -**namespaces**: A `namespaces` field allows users to perform advanced matching on -Namespace objects which cannot be done via label selectors. Currently, the -`namespaces` field has only one matching strategy, `Self`. If set to `Self`, it indicates -that the corresponding `podSelector` (or all Pods if `podSelector` is not set) -should only select Pods belonging to the same Namespace as the workload targeted -(either through a policy-level AppliedTo or a rule-level Applied-To) by the current -ingress or egress rule. This enables policy writers to create per-Namespace rules within a -single policy. See the [example](#acnp-for-strict-namespace-isolation) YAML above. This field is -optional and cannot be set along with a `namespaceSelector` within the same peer. +"destinations" if is set in the `egress` section. For more information on its +usage, refer to [this section](#node-selector). + +**namespaces**: The `namespaces` field allows users to perform advanced matching on +Namespace objects which cannot be done via label selectors. Refer to +[this section](#matching-self-namespace-for-appliedtos) for more details, and +[this sample yaml](#acnp-for-strict-namespace-isolation) for usage. **group**: A `group` refers to a ClusterGroup to which this ingress/egress peer, or -an `appliedTo` must resolve to. More information on ClusterGroups can be found [here](#clustergroup). +an `appliedTo` must resolve to. More information on ClusterGroups can be found in +[this section](#clustergroup). + +**serviceAccount**: This selects all the Pods which have been assigned a specific ServiceAccount. +For more information on its usage, refer to [this section](#serviceaccount-based-selection). **ipBlock**: This selects particular IP CIDR ranges to allow as `ingress` "sources" or `egress` "destinations". These should be cluster-external IPs, @@ -569,7 +584,8 @@ since Pod IPs are ephemeral and unpredictable. **fqdn**: This selector is applicable only to the `to` section in an `egress` block. It is used to select Fully Qualified Domain Names (FQDNs), specified either by exact name or wildcard -expressions, when defining `egress` rules. +expressions, when defining `egress` rules. For more information on its usage, refer to +[this section](#fqdn-based-filtering). ### Key differences from K8s NetworkPolicy @@ -602,7 +618,7 @@ The following kubectl commands can be used to retrieve ACNP resources: kubectl get acnp.crd.antrea.io ``` -All of the above commands produce output similar to what is shown below: +All the above commands produce output similar to what is shown below: ```text NAME TIER PRIORITY AGE @@ -629,40 +645,40 @@ metadata: name: test-anp namespace: default spec: - priority: 5 - tier: securityops - appliedTo: - - podSelector: - matchLabels: - role: db - ingress: - - action: Allow - from: - - podSelector: - matchLabels: - role: frontend - - podSelector: - matchLabels: - role: nondb - namespaceSelector: - matchLabels: - role: db - ports: - - protocol: TCP - port: 8080 - endPort: 9000 - name: AllowFromFrontend - enableLogging: false - egress: - - action: Drop - to: - - ipBlock: - cidr: 10.0.10.0/24 - ports: - - protocol: TCP - port: 5978 - name: DropToThirdParty - enableLogging: true + priority: 5 + tier: securityops + appliedTo: + - podSelector: + matchLabels: + role: db + ingress: + - action: Allow + from: + - podSelector: + matchLabels: + role: frontend + - podSelector: + matchLabels: + role: nondb + namespaceSelector: + matchLabels: + role: db + ports: + - protocol: TCP + port: 8080 + endPort: 9000 + name: AllowFromFrontend + enableLogging: false + egress: + - action: Drop + to: + - ipBlock: + cidr: 10.0.10.0/24 + ports: + - protocol: TCP + port: 5978 + name: DropToThirdParty + enableLogging: true ``` ### Key differences from Antrea ClusterNetworkPolicy @@ -698,7 +714,7 @@ The following kubectl commands can be used to retrieve ANP resources: kubectl get anp.crd.antrea.io ``` -All of the above commands produce output similar to what is shown below: +All the above commands produce output similar to what is shown below: ```text NAME TIER PRIORITY AGE @@ -711,17 +727,17 @@ Antrea-native policy CRDs are ordered based on priorities set at various levels. ### Ordering based on Tier priority -With the introduction of tiers, Antrea Policies, like ClusterNetworkPolicies, +With the introduction of Tiers, Antrea Policies, like ClusterNetworkPolicies, are first enforced based on the Tier to which they are associated. i.e. all -policies belonging to a high Tier are enforced first, followed by policies -belonging to the next Tier and so on, until the "application" Tier policies -are enforced. K8s NetworkPolicies are enforced next, and "baseline" Tier -policies will be enforced last. +policies belonging to a high-precedenced Tier are enforced first, followed by +policies belonging to the next Tier and so on, until the "application" Tier +policies are enforced. K8s NetworkPolicies are enforced next, and "baseline" +Tier policies will be enforced last. ### Ordering based on policy priority -Within a tier, Antrea-native policy CRDs are ordered by the `priority` at the policy -level. Thus, the policy with the highest precedence (lowest priority number +Within a Tier, Antrea-native policy CRDs are ordered by the `priority` at the policy +level. Thus, the policy with the highest precedence (the smallest numeric priority value) is enforced first. This ordering is performed solely based on the `priority` assigned, as opposed to the "Kind" of the resource, i.e. the relative ordering between a [ClusterNetworkPolicy resource](#antrea-clusternetworkpolicy) and @@ -766,179 +782,19 @@ The [ovs-pipeline doc](design/ovs-pipeline.md) contains more information on how policy rules are realized by OpenFlow, and how the priority of flows reflects the order in which they are enforced. -## ClusterGroup - -A ClusterGroup (CG) CRD is a specification of how workloads are grouped together. -It allows admins to group Pods using traditional label selectors, which can then -be referenced in ACNP in place of stand-alone `podSelector` and/or `namespaceSelector`. -In addition to `podSelector` and `namespaceSelector`, ClusterGroup also supports the -following ways to select endpoints: - -- Pod grouping by `serviceReference`. ClusterGroup specified by `serviceReference` will - contain the same Pod members that are currently selected by the Service's selector. -- `ipBlock` or `ipBlocks` to share IPBlocks between ACNPs. -- `childGroups` to select other ClusterGroups by name. - -ClusterGroups allow admins to separate the concern of grouping of workloads from -the security aspect of Antrea-native policies. -It adds another level of indirection allowing users to update group membership -without having to update individual policy rules. - -### The ClusterGroup resource - -An example ClusterGroup might look like this: - -```yaml -apiVersion: crd.antrea.io/v1alpha3 -kind: ClusterGroup -metadata: - name: test-cg-sel -spec: - podSelector: - matchLabels: - role: db - namespaceSelector: - matchLabels: - env: prod -status: - conditions: - - type: "GroupMembersComputed" - status: "True" - lastTransitionTime: "2021-01-29T19:59:39Z" ---- -apiVersion: crd.antrea.io/v1alpha3 -kind: ClusterGroup -metadata: - name: test-cg-ip-block -spec: - # IPBlocks cannot be set along with PodSelector, NamespaceSelector or serviceReference. - ipBlocks: - - cidr: 10.0.10.0/24 -status: - conditions: - - type: "GroupMembersComputed" - status: "True" - lastTransitionTime: "2021-01-29T19:59:39Z" ---- -apiVersion: crd.antrea.io/v1alpha3 -kind: ClusterGroup -metadata: - name: test-cg-svc-ref -spec: - # ServiceReference cannot be set along with PodSelector, NamespaceSelector or ipBlocks. - serviceReference: - name: test-service - namespace: default -status: - conditions: - - type: "GroupMembersComputed" - status: "True" - lastTransitionTime: "2021-01-29T20:21:46Z" ---- -apiVersion: crd.antrea.io/v1alpha3 -kind: ClusterGroup -metadata: - name: test-cg-nested -spec: - childGroups: [test-cg-sel, test-cg-ip-blocks, test-cg-svc-ref] -status: - conditions: - - type: "GroupMembersComputed" - status: "True" - lastTransitionTime: "2021-01-29T20:21:48Z" -``` - -There are a few **restrictions** on how ClusterGroups can be configured: - -- A ClusterGroup is a cluster-scoped resource and therefore can only be set in an Antrea - ClusterNetworkPolicy's `appliedTo` and `to`/`from` peers. -- For the `childGroup` field, currently only one level of nesting is supported: - If a ClusterGroup has childGroups, it cannot be selected as a childGroup by other ClusterGroups. -- ClusterGroup must exist before another ClusterGroup can select it by name as its childGroup. - A ClusterGroup cannot be deleted if it is referred to by other ClusterGroup as childGroup. - This restriction may be lifted in future releases. -- At most one of `podSelector`, `serviceReference`, `ipBlock`, `ipBlocks` or `childGroups` - can be set for a ClusterGroup, i.e. a single ClusterGroup can either group workloads, - represent IP CIDRs or select other ClusterGroups. A parent ClusterGroup can select different - types of ClusterGroups (Pod/Service/CIDRs), but as mentioned above, it cannot select a - ClusterGroup that has childGroups itself. - -**spec**: The ClusterGroup `spec` has all the information needed to define a -cluster-wide group. - -**podSelector**: Pods can be grouped cluster-wide using `podSelector`. -If set with a `namespaceSelector`, all matching Pods from Namespaces selected -by the `namespaceSelector` will be grouped. - -**namespaceSelector**: All Pods from Namespaces selected by the namespaceSelector -will be grouped. -If set with a `podSelector`, all matching Pods from Namespaces selected by the -`namespaceSelector` will be grouped. - -**ipBlock**: This selects a particular IP CIDR range to allow as `ingress` -"sources" or `egress` "destinations". -A ClusterGroup with `ipBlock` referenced in an ACNP's `appliedTo` field will be -ignored, and the policy will have no effect. -For a same ClusterGroup, `ipBlock` and `ipBlocks` cannot be set concurrently. -ipBlock will be deprecated for ipBlocks in future versions of ClusterGroup. - -**ipBlocks**: This selects a list of IP CIDR ranges to allow as `ingress` -"sources" or `egress` "destinations". -A ClusterGroup with `ipBlocks` referenced in an ACNP's `appliedTo` field will be -ignored, and the policy will have no effect. -For a same ClusterGroup, `ipBlock` and `ipBlocks` cannot be set concurrently. - -**serviceReference**: Pods that serve as the backend for the specified Service -will be grouped. Services without selectors are currently not supported, and will -be ignored if referred by `serviceReference` in a ClusterGroup. -When ClusterGroups with `serviceReference` are used in ACNPs as `appliedTo` or -`to`/`from` peers, no Service port information will be automatically assumed for -traffic enforcement. `ServiceReference` is merely a mechanism to group Pods and -ensure that a ClusterGroup stays in sync with the set of Pods selected by a given -Service. - -**childGroups**: This selects existing ClusterGroups by name. The effective members -of the "parent" ClusterGrup will be the union of all its childGroups' members. -See the section above for restrictions. - -**status**: The ClusterGroup `status` field determines the overall realization -status of the group. - -**groupMembersComputed**: The "GroupMembersComputed" condition is set to "True" -when the controller has calculated all the corresponding workloads that match the -selectors set in the group. - -### kubectl commands for ClusterGroup - -The following kubectl commands can be used to retrieve CG resources: - -```bash - # Use long name with API Group - kubectl get clustergroups.crd.antrea.io - - # Use short name - kubectl get cg +## Advanced peer selection mechanisms of Antrea-native Policies - # Use short name with API Group - kubectl get cg.crd.antrea.io -``` - -## Audit logging for Antrea-native policies - -Logs are recorded in `/var/log/antrea/networkpolicy` when `enableLogging` is configured. -Fluentd can be used to assist with analyzing the logs. Refer to the -[Fluentd cookbook](cookbooks/fluentd) for documentation. - -## Select Namespace by Name +### Selecting Namespace by Name Kubernetes NetworkPolicies and Antrea-native policies allow selecting workloads from Namespaces with the use of a label selector (i.e. `namespaceSelector`). However, it is often desirable to be able to select Namespaces directly by their `name` as opposed to using the `labels` associated with the Namespaces. -### K8s clusters with version 1.21 and above +#### K8s clusters with version 1.21 and above -Starting with K8s v1.21, all Namespaces are labeled with the `kubernetes.io/metadata.name: ` [label](https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/#automatic-labelling) +Starting with K8s v1.21, all Namespaces are labeled with the `kubernetes.io/metadata.name: ` +[label](https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/#automatic-labelling) provided that the `NamespaceDefaultLabelName` feature gate (enabled by default) is not disabled in K8s. K8s NetworkPolicy and Antrea-native policy users can take advantage of this reserved label to select Namespaces directly by their `name` in `namespaceSelectors` as follows: @@ -959,7 +815,7 @@ spec: to: - podSelector: matchLabels: - app: core-dns + k8s-app: kube-dns namespaceSelector: matchLabels: kubernetes.io/metadata.name: kube-system @@ -974,7 +830,7 @@ spec: **Note**: `NamespaceDefaultLabelName` feature gate is scheduled to be removed in K8s v1.24, thereby ensuring that labeling Namespaces by their name cannot be disabled. -### K8s clusters with version 1.20 and below +#### K8s clusters with version 1.20 and below In order to select Namespaces by name, Antrea labels Namespaces with a reserved label `antrea.io/metadata.name`, whose value is set to the Namespace's name. Users can then use this label in the @@ -1030,7 +886,7 @@ spec: to: - podSelector: matchLabels: - app: core-dns + k8s-app: kube-dns namespaceSelector: matchLabels: antrea.io/metadata.name: kube-system @@ -1042,13 +898,83 @@ spec: name: AllowToCoreDNS ``` -The above example allows all Pods from Namespace "default" to connect to all "core-dns" +The above example allows all Pods from Namespace "default" to connect to all "kube-dns" Pods from Namespace "kube-system" on TCP port 53. -## FQDN based filtering +### Selecting Pods in the same Namespace with Self + +The `namespaces` field allows users to perform advanced matching on Namespace objects that cannot +be done via label selectors. Currently, the `namespaces` field has only one matching strategy, `Self`. +If set to `Self`, for each Pod targeted by the appliedTo of the policy/rule, this field will cause the +rule to select endpoints in the same Namespace as that Pod. It enables policy writers to create per-Namespace +rules within a single policy. +This field is optional and cannot be set along with a `namespaceSelector` within the same peer. + +Consider a minimalistic cluster, where there are only three Namespaces labeled ns=x, ns=y and ns=z. +Inside each of these Namespaces, there are three Pods labeled app=a, app=b and app=c. + +```yaml +apiVersion: crd.antrea.io/v1alpha1 +kind: ClusterNetworkPolicy +metadata: + name: allow-self-ns +spec: + priority: 1 + tier: platform + appliedTo: + - namespaceSelector: {} + ingress: + - action: Allow + from: + - namespaces: + match: Self + - action: Deny + egress: + - action: Allow + to: + - namespaces: + match: Self + - action: Deny +``` + +The policy above ensures that x/a, x/b and x/c can communicate with each other, but nothing else +(unless there are higher precedenced policies which say otherwise). Same for Namespaces y and z. + +```yaml +apiVersion: crd.antrea.io/v1alpha1 +kind: ClusterNetworkPolicy +metadata: + name: deny-self-ns-a-to-b +spec: + priority: 1 + tier: securityops + appliedTo: + - namespaceSelector: {} + podSelector: + matchLabels: + app: b + ingress: + - action: Deny + from: + - namespaces: + match: Self + podSelector: + matchLabels: + app: a +``` + +The `deny-self-ns-a-to-b` policy ensures that traffic from x/a to x/b, y/a to y/b and z/a to z/b are +denied. It can be used in conjunction with the `allow-self-ns` policy. If both policies are applied, +the only other Pod that x/a can reach in the cluster will be Pod x/c. + +These two policies shown above are for demonstration purposes only. For more realistic usage of the +`namespaces` field, refer to this [sample](#acnp-for-strict-namespace-isolation) YAML in the previous +section. + +### FQDN based filtering -Antrea-native policy accepts a `fqdn` field to select Fully Qualified Domain Names (FQDNs), -specified either by exact name or wildcard expressions, when defining `egress` rules. +Antrea-native policy features a `fqdn` field in egress rules to select Fully Qualified Domain Names +(FQDNs), specified either by exact FQDN name or wildcard expressions. The standard `Allow`, `Drop` and `Reject` actions apply to FQDN egress rules. @@ -1066,14 +992,26 @@ spec: matchLabels: app: client egress: - - action: Drop + - action: Allow to: - fqdn: "*foobar.com" + ports: + - protocol: TCP + port: 8080 + - action: Drop # Drop all other egress traffic, in-cluster or out-of-cluster ``` -The above example drops all traffic destined to any FQDN that matches the wildcard -expression `*foobar.com` originating from any Pod with label `app` set to `client` -across any Namespace. This feature only works at the L3/L4 level. +The above example allows all traffic destined to any FQDN that matches the wildcard expression +`*foobar.com` on port 8080, originating from any Pod with label `app` set to `client` +across any Namespace. For these `client` Pods, all other egress traffic are dropped. + +Note that for FQDN wildcard expressions, the `*` character can match multiple subdomains (i.e. +`*foobar.com` will match `foobar.com`, `www.foobar.com` and `test.uswest.foobar.com`). + +This feature only works at the L3/L4 level, which means that Antrea will only program datapath +rules for actual egress traffic towards these FQDNs, based on DNS results. It will not interfere +with DNS packets, unless there is a separate policy dropping/rejecting communication between +the DNS components and the Pods selected. Note that FQDN based policies do not work for [Service DNS names created by Kubernetes](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/#services) @@ -1107,14 +1045,14 @@ spec: - fqdn: "svcA.default.svc.cluster.local" ``` -## Node Selector +### Node Selector NodeSelector selects certain Nodes which match the label selector. When used in the `to` field of an egress rule, it adds the Node IPs to the rule's destination address group; when used in the `from` field of an ingress rule, it adds the Node IPs to the rule's source address group. Notice that when a rule with a nodeSelector applies to a Node, it only restricts the traffic to/from certain IPs of the Node. -The IPs include: +The IPs include: 1. The Node IP (the IP address in the Node API object) 2. The Antrea gateway IP (the IP address of the interface antrea-agent will create and use for Node-to-Pod communication) @@ -1151,24 +1089,31 @@ spec: port: 6443 ``` -## toServices instruction +### toServices egress rules + +A combination of Service name and Service Namespace can be used in `toServices` in egress rules to refer to a K8s Service. +`toServices` match traffic based on the clusterIP, port and protocol of Services. Thus, headless Service is not supported +by this field. A sample policy can be found [here](#acnp-for-toservices-rule). -A combination of Service name and Service Namespace can be used in `toServices` to refer to a Service. -`toServices` match traffic based on the clusterIP, port and protocol of Services. So headless Service is not supported. -Since `toServices` represents a combination of IP+port, it can't be used with `to` or `ports`. Also, this match process -relies on the groupID assigned to the Service by AntreaProxy. So it can only be used when AntreaProxy is enabled. -This clusterIP based match has one caveat: directly access to the Endpoints of this Service is not controlled by -`toServices`. To control the access to the backend Endpoints, you could use `ClusterGroup` with `ServiceReference`. -Because `ClusterGroup` with `ServiceReference` is equivalent to a podSelector that selects all backend Endpoints Pods of -the Service referred in `ServiceReference`. +Since `toServices` represents a combination of IP+port, it cannot be used with `to` or `ports` within the same egress rule. +Also, since the matching process relies on the groupID assigned to Service by AntreaProxy, this field can only be used when +AntreaProxy is enabled. -## ServiceAccount based selection +This clusterIP-based match has one caveat: direct access to the Endpoints of this Service is not affected by +`toServices` rules. To restrict access towards backend Endpoints of a Service, define a `ClusterGroup` with `ServiceReference` +and use the name of ClusterGroup in the Antrea-native policy rule's `group` field instead. +`ServiceReference` of a ClusterGroup is equivalent to a `podSelector` of a ClusterGroup that selects all backend Pods of a +Service, based on the Service spec's matchLabels. Antrea will keep the Endpoint selection up-to-date in case the Service's +matchLabels change, or Endpoints are added/deleted for that Service. For more information on `ServiceReference`, refer to the +`serviceReference` paragraph of the [ClusterGroup section](#the-clustergroup-resource). -Antrea ClusterNetworkPolicy accepts a `serviceAccount` field to select all Pods that have been assigned the -ServiceAccount selected by this field. This field could be used in `appliedTo`, ingress `from` and egress `to` section. -No matter `serviceAccount` is used in which sections, it cannot be used with any other fields. +### ServiceAccount based selection -`serviceAccount` uses `namespace` + `name` to select the ServiceAccount with a specific name under a specific namespace. +Antrea ClusterNetworkPolicy features a `serviceAccount` field to select all Pods that have been assigned the +ServiceAccount referenced in this field. This field could be used in `appliedTo`, ingress `from` and egress `to` section. +No matter which sections the `serviceAccount` field is used in, it cannot be used with any other fields. + +`serviceAccount` uses `namespace` and `name` to select the ServiceAccount with a specific name under a specific namespace. An example policy using `serviceAccount` could look like this: @@ -1194,18 +1139,172 @@ spec: enableLogging: false ``` -In this example, the policy will be applied to all Pods whose ServiceAccount is in `ns-1` namespace and name as `sa-1`. +In this example, the policy will be applied to all Pods whose ServiceAccount is `sa-1` of `ns-1`. Let's call those Pods "appliedToPods". The egress `to` section will select all Pods whose ServiceAccount is in `ns-2` namespace and name as `sa-2`. Let's call those Pods "egressPods". +After this policy is applied, traffic from "appliedToPods" to "egressPods" will be dropped. -So after this policy is applied, traffic from "appliedToPods" to "egressPods" will be dropped. +Note: Antrea will use a reserved label key for internal processing `serviceAccount`. +The reserved label looks like: `internal.antrea.io/service-account:[ServiceAccountName]`. Users should avoid using +this label key in any entities no matter if a policy with `serviceAccount` is applied in the cluster. -There is a CAVEAT after introducing `serviceAccount`: +## ClusterGroup -Antrea will use a reserved label key for internal processing `serviceAccount`. -The reserved label looks like: `internal.antrea.io/service-account:[ServiceAccountName]`. Users should avoid using -this label key in any entities whether a policy with `serviceAccount` is applied in the cluster. +A ClusterGroup (CG) CRD is a specification of how workloads are grouped together. +It allows admins to group Pods using traditional label selectors, which can then +be referenced in ACNP in place of stand-alone `podSelector` and/or `namespaceSelector`. +In addition to `podSelector` and `namespaceSelector`, ClusterGroup also supports the +following ways to select endpoints: + +- Pod grouping by `serviceReference`. ClusterGroup specified by `serviceReference` will + contain the same Pod members that are currently selected by the Service's selector. +- `ipBlock` or `ipBlocks` to share IPBlocks between ACNPs. +- `childGroups` to select other ClusterGroups by name. + +ClusterGroups allow admins to separate the concern of grouping of workloads from +the security aspect of Antrea-native policies. +It adds another level of indirection allowing users to update group membership +without having to update individual policy rules. + +### The ClusterGroup resource + +An example ClusterGroup might look like this: + +```yaml +apiVersion: crd.antrea.io/v1alpha3 +kind: ClusterGroup +metadata: + name: test-cg-sel +spec: + podSelector: + matchLabels: + role: db + namespaceSelector: + matchLabels: + env: prod +status: + conditions: + - type: "GroupMembersComputed" + status: "True" + lastTransitionTime: "2021-01-29T19:59:39Z" +--- +apiVersion: crd.antrea.io/v1alpha3 +kind: ClusterGroup +metadata: + name: test-cg-ip-block +spec: + # IPBlocks cannot be set along with PodSelector, NamespaceSelector or serviceReference. + ipBlocks: + - cidr: 10.0.10.0/24 +status: + conditions: + - type: "GroupMembersComputed" + status: "True" + lastTransitionTime: "2021-01-29T19:59:39Z" +--- +apiVersion: crd.antrea.io/v1alpha3 +kind: ClusterGroup +metadata: + name: test-cg-svc-ref +spec: + # ServiceReference cannot be set along with PodSelector, NamespaceSelector or ipBlocks. + serviceReference: + name: test-service + namespace: default +status: + conditions: + - type: "GroupMembersComputed" + status: "True" + lastTransitionTime: "2021-01-29T20:21:46Z" +--- +apiVersion: crd.antrea.io/v1alpha3 +kind: ClusterGroup +metadata: + name: test-cg-nested +spec: + childGroups: [test-cg-sel, test-cg-ip-blocks, test-cg-svc-ref] +status: + conditions: + - type: "GroupMembersComputed" + status: "True" + lastTransitionTime: "2021-01-29T20:21:48Z" +``` + +There are a few **restrictions** on how ClusterGroups can be configured: + +- A ClusterGroup is a cluster-scoped resource and therefore can only be set in an Antrea + ClusterNetworkPolicy's `appliedTo` and `to`/`from` peers. +- For the `childGroup` field, currently only one level of nesting is supported: + If a ClusterGroup has childGroups, it cannot be selected as a childGroup by other ClusterGroups. +- ClusterGroup must exist before another ClusterGroup can select it by name as its childGroup. + A ClusterGroup cannot be deleted if it is referred to by other ClusterGroup as childGroup. + This restriction may be lifted in future releases. +- At most one of `podSelector`, `serviceReference`, `ipBlock`, `ipBlocks` or `childGroups` + can be set for a ClusterGroup, i.e. a single ClusterGroup can either group workloads, + represent IP CIDRs or select other ClusterGroups. A parent ClusterGroup can select different + types of ClusterGroups (Pod/Service/CIDRs), but as mentioned above, it cannot select a + ClusterGroup that has childGroups itself. + +**spec**: The ClusterGroup `spec` has all the information needed to define a +cluster-wide group. + +- **podSelector**: Pods can be grouped cluster-wide using `podSelector`. + If set with a `namespaceSelector`, all matching Pods from Namespaces selected + by the `namespaceSelector` will be grouped. + +- **namespaceSelector**: All Pods from Namespaces selected by the namespaceSelector + will be grouped. + If set with a `podSelector`, all matching Pods from Namespaces selected by the + `namespaceSelector` will be grouped. + +- **ipBlock**: This selects a particular IP CIDR range to allow as `ingress` + "sources" or `egress` "destinations". + A ClusterGroup with `ipBlock` referenced in an ACNP's `appliedTo` field will be + ignored, and the policy will have no effect. + For a same ClusterGroup, `ipBlock` and `ipBlocks` cannot be set concurrently. + ipBlock will be deprecated for ipBlocks in future versions of ClusterGroup. + +- **ipBlocks**: This selects a list of IP CIDR ranges to allow as `ingress` + "sources" or `egress` "destinations". + A ClusterGroup with `ipBlocks` referenced in an ACNP's `appliedTo` field will be + ignored, and the policy will have no effect. + For a same ClusterGroup, `ipBlock` and `ipBlocks` cannot be set concurrently. + +- **serviceReference**: Pods that serve as the backend for the specified Service + will be grouped. Services without selectors are currently not supported, and will + be ignored if referred by `serviceReference` in a ClusterGroup. + When ClusterGroups with `serviceReference` are used in ACNPs as `appliedTo` or + `to`/`from` peers, no Service port information will be automatically assumed for + traffic enforcement. `ServiceReference` is merely a mechanism to group Pods and + ensure that a ClusterGroup stays in sync with the set of Pods selected by a given + Service. + +- **childGroups**: This selects existing ClusterGroups by name. The effective members + of the "parent" ClusterGrup will be the union of all its childGroups' members. + See the section above for restrictions. + +**status**: The ClusterGroup `status` field determines the overall realization +status of the group. + +- **groupMembersComputed**: The "GroupMembersComputed" condition is set to "True" + when the controller has calculated all the corresponding workloads that match the + selectors set in the group. + +### kubectl commands for ClusterGroup + +The following kubectl commands can be used to retrieve CG resources: + +```bash + # Use long name with API Group + kubectl get clustergroups.crd.antrea.io + + # Use short name + kubectl get cg + + # Use short name with API Group + kubectl get cg.crd.antrea.io +``` ## RBAC @@ -1221,16 +1320,33 @@ share the `view` ClusterRole to a wider range of subjects to allow them to read the policies that may affect their workloads. Similar RBAC is applied to the ClusterGroup resource. -## Notes +## Notes and constraints - There is a soft limit of 20 on the maximum number of Tier resources that are supported. But for optimal performance, it is recommended that the number of Tiers in a cluster be less than or equal to 10. - In order to reduce the churn in the agent, it is recommended to set the policy - priority within the range 1.0 to 100.0. + priority (acnp/anp.spec.priority) within the range 1.0 to 100.0. - The v1alpha1 policy CRDs support up to 10,000 unique priorities at policy level, - and up to 50,000 unique priorities at rule level, across all tiers except for - the "baseline" tier. For any two policy rules, their rule level priorities are only - considered equal if they share the same tier, and have the same policy priority - as well as rule priority. -- For the "baseline" tier, the max supported unique priorities (at rule level）is 150. + and up to 50,000 unique priorities at rule level, across all Tiers except for + the "baseline" Tier. For any two Antrea-native policy rules, their rule level + priorities are only considered equal if their policy objects share the same Tier + and have the same policy priority, plus the rules themselves are of the same rule + priority (rule priority is the sequence number of the rule within the policy's + ingress or egress section). +- For the "baseline" Tier, the max supported unique priorities (at rule level) is 150. +- If there are multiple Antrea-native policy rules created at the same rule-level + priority (same policy Tier, policy priority and rule priority), who happen to select + overlapping traffic patterns but have conflicting rule actions (e.g.`Allow`v.s.`Deny`), + the behavior of such traffic will be undeterministic. For example, consider two + AntreaNetworkPolicies created in the same Namespace and Tier with the same policy + priority. The first policy applies to all `app=web` Pods in the Namespace and has only + one ingress rule to `Deny` all traffic from `role=dev` Pods. The other policy also + applies to all `app=web` Pods in the Namespace and has only one ingress rule, which is + to `Allow` all traffic from `app=client` Pods. Those two ingress rules might not always + conflict, but in case a Pod with both `app=client` and `role=dev` labels initiate + traffic towards the web Pods in the Namespace, both rules will be matched at the same + priority with conflicting actions. It will be the policy writer's responsibility to + identify such ambiguities in rule definitions and avoid potential undeterministic + rule enforcement results. In general, it is recommended that rules of conflicting + actions are always created at different rule-level priorities.