[@actions/attest] Fix bug with customized OIDC issuer

packages/attest/RELEASES.md

@@ -1,5 +1,8 @@
 # @actions/attest Releases
 
+### 1.4.2
+
+- Fix bug in `buildSLSAProvenancePredicate`/`attestProvenance` when generating provenance statement for enterprise account using customized OIDC issuer value [#1823](https://github.com/actions/toolkit/pull/1823)
 ### 1.4.1
 
 - Bump @actions/http-client from 2.2.1 to 2.2.3 [#1805](https://github.com/actions/toolkit/pull/1805)
@@ -8,7 +11,6 @@
 
 - Add new `headers` parameter to the `attest` and `attestProvenance` functions [#1790](https://github.com/actions/toolkit/pull/1790)
 - Update `buildSLSAProvenancePredicate`/`attestProvenance` to automatically derive default OIDC issuer URL from current execution context [#1796](https://github.com/actions/toolkit/pull/1796)
-
 ### 1.3.1
 
 - Fix bug with proxy support when retrieving JWKS for OIDC issuer [#1776](https://github.com/actions/toolkit/pull/1776)

packages/attest/__tests__/oidc.test.ts

@@ -68,6 +68,55 @@ describe('getIDTokenClaims', () => {
     })
   })
 
+  describe('when ID token is valid (w/ enterprise slug)', () => {
+    const claims = {
+      iss: `${issuer}/foo-bar`,
+      aud: audience,
+      ref: 'ref',
+      sha: 'sha',
+      repository: 'repo',
+      event_name: 'push',
+      job_workflow_ref: 'job_workflow_ref',
+      workflow_ref: 'workflow',
+      repository_id: '1',
+      repository_owner_id: '1',
+      runner_environment: 'github-hosted',
+      run_id: '1',
+      run_attempt: '1'
+    }
+
+    beforeEach(async () => {
+      const jwt = await new jose.SignJWT(claims)
+        .setProtectedHeader({alg: 'PS256'})
+        .sign(key.privateKey)
+
+      nock(issuer).get(tokenPath).query({audience}).reply(200, {value: jwt})
+    })
+
+    it('returns the ID token claims', async () => {
+      const result = await getIDTokenClaims(issuer)
+      expect(result).toEqual(claims)
+    })
+  })
+
+  describe('when ID token is missing the "iss" claim', () => {
+    const claims = {
+      aud: audience
+    }
+
+    beforeEach(async () => {
+      const jwt = await new jose.SignJWT(claims)
+        .setProtectedHeader({alg: 'PS256'})
+        .sign(key.privateKey)
+
+      nock(issuer).get(tokenPath).query({audience}).reply(200, {value: jwt})
+    })
+
+    it('throws an error', async () => {
+      await expect(getIDTokenClaims(issuer)).rejects.toThrow(/missing "iss"/i)
+    })
+  })
+
   describe('when ID token is missing required claims', () => {
     const claims = {
       iss: issuer,
@@ -99,7 +148,9 @@ describe('getIDTokenClaims', () => {
     })
 
     it('throws an error', async () => {
-      await expect(getIDTokenClaims(issuer)).rejects.toThrow(/unexpected "iss"/)
+      await expect(getIDTokenClaims(issuer)).rejects.toThrow(
+        /unexpected "iss"/i
+      )
     })
   })
 

packages/attest/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/attest",
-  "version": "1.4.1",
+  "version": "1.4.2",
   "description": "Actions attestation lib",
   "keywords": [
     "github",

packages/attest/src/oidc.ts

@@ -49,10 +49,19 @@ const decodeOIDCToken = async (
   // Verify and decode token
   const jwks = jose.createLocalJWKSet(await getJWKS(issuer))
   const {payload} = await jose.jwtVerify(token, jwks, {
-    audience: OIDC_AUDIENCE,
-    issuer
+    audience: OIDC_AUDIENCE
   })
 
+  if (!payload.iss) {
+    throw new Error('Missing "iss" claim')
+  }
+
+  // Check that the issuer STARTS WITH the expected issuer URL to account for
+  // the fact that the value may include an enterprise-specific slug
+  if (!payload.iss.startsWith(issuer)) {
+    throw new Error(`Unexpected "iss" claim: ${payload.iss}`)
+  }
+
   return payload
 }