WIP Github SLSA Provenance

Signed-off-by: Adolfo García Veytia (Puerco) <[email protected]>

rule-types/github/attestation_slsa_github.yaml

@@ -0,0 +1,135 @@
+---
+version: v1
+type: rule-type
+name: artifact_signature
+context:
+  provider: github
+description: |
+  Verifies a provenance attestation with a GitHub build definition matches the
+  expected values. 
+guidance: |
+  Provenance attestation capture the build environment and parameters where a
+  software artifact was created. By controlling the build environment, developers
+  can make sure no malicious artifacts where injected into the build process.
+def:
+  # Defines the section of the pipeline the rule will appear in.
+  # This will affect the template used to render multiple parts
+  # of the rule.
+  in_entity: artifact
+  # Defines the schema for parameters that will be passed to the rule
+  param_schema:
+    type: object
+    properties:
+      name:
+        type: string
+        description: "The name of the artifact to check."
+      tags:
+        "type": array
+        "items": {
+          "type": "string"
+        }
+        description: "The tags of the artifact to check. Must be a subset of the tags the artifact has"
+      tag_regex:
+        type: string
+        description: "The regex to match the tags of the artifact to check. Conflicts with tags."
+      type:
+        "type": string
+        "default": "container"
+        "enum": ["container"]
+        description: "The type of artifact to check. Currently only container is supported."
+      sigstore:
+        type: string
+        description: "URL of the sigstore TUF root to use for verification."
+        default: "tuf-repo-cdn.sigstore.dev"
+    required:
+      - tags
+  # Defines the schema for writing a rule with this rule being checked
+  rule_schema:
+    type: "object"
+    properties:
+      event:
+        type: array
+        description: "Events allowed to trigger a build"
+        enum:
+          - worflow_dispatch
+          - push
+        default: ["worflow_dispatch", "push"]
+      workflow_repository:
+        type: string
+        description: "Tepository expected to produce the artifact, i.e. https://github.com/stacklok/minder"
+      workflow_ref:
+        type: string
+        description: "The git reference of the executed workflow"
+      is_verified:
+        type: boolean
+        description: "Set to true to enforce artifact signature being verified."
+      signer_identity:
+        type: string
+        description: "Set the signer identity that is expected to produce the artifact, i.e. docker-image-build-push.yml or an email address"
+      runner_environment:
+        type: string
+        description: "Set the runner environment that is expected to produce the artifact, i.e. github-hosted"
+      allowed_workflow:
+        type: boolean
+        description: "Set to true to enforce checking if the workflow that build this artifact is part of the allowed workflows"
+      cert_issuer:
+        type: string
+        description: "Set the certificate issuer that is expected to produce the artifact provenance, i.e. https://token.actions.githubusercontent.com"
+  # Defines the configuration for ingesting data relevant for the rule
+  ingest:
+    type: artifact
+    # Currently no configuration
+    artifact: {}
+  # Defines the configuration for evaluating data ingested against the given profile
+  eval:
+    type: rego
+    rego:
+      type: deny-by-default
+      def: |
+        package minder
+
+        import rego.v1
+
+        default allow := false
+        
+        allow if {
+          some artifact in input.ingested
+          artifact.Verification.attestation.predicate_type == "https://slsa.dev/provenance/v1"
+
+          # These parameters only apply when the slsa attestation has a 
+          # buildDefinition.buildType of https://slsa-framework.github.io/github-actions-buildtypes/workflow/v1
+          
+          # Check the external parameters
+          artifact.Verification.attestation.predicate.buildDefinition.externalParameters.workflow.path == ".github/workflows/build-image-signed-ghat.yml"
+          artifact.Verification.attestation.predicate.buildDefinition.externalParameters.workflow.ref == "refs/heads/main"
+          artifact.Verification.attestation.predicate.buildDefinition.externalParameters.workflow.repository == "https://github.com/jakubtestorg/good-repo-go"
+          
+          # Internal parameters 
+          # Event is anm arrau
+          artifact.Verification.attestation.predicate.buildDefinition.internalParameters.github.event_name == "workflow_dispatch"
+        }
+
+
+        #every artifactVersion in input.ingested {
+        #  some x in artifactVersion.Verification.attestation.predicateType
+        #  x == "https://slsa.dev/provenance/v1"
+          ##artifactVersion.Verification.attestation.predicateType == "https://slsa.dev/provenance/v1" {
+          #  artifactVersion.Verification["is_signed"]
+          #}
+        #}
+
+        #allow if {
+        #  every artifactVersion in input.ingested {
+        #    if artifactVersion.Verification.attestation.predicateType == "https://slsa.dev/provenance/v1" {
+        #      artifactVersion.Verification["is_signed"]
+        #    }
+        ##    #every key, value in input.profile {
+        # #   #  artifactVersion.Verification[key] == value
+        #    #}
+        #  }
+        #}
+  # Defines the configuration for alerting on the rule
+  alert:
+    type: security_advisory
+    security_advisory:
+      severity: "medium"