feat: add provenanceFile option for libnpmpublish

bdehamer · bdehamer · commit 879a8c89711e · 2023-05-23T13:51:20.000-07:00
Signed-off-by: Brian DeHamer &lt;bdehamer@github.com&gt;
diff --git a/workspaces/libnpmpublish/README.md b/workspaces/libnpmpublish/README.md
@@ -51,6 +51,14 @@ A couple of options of note:
   token for the registry. For other ways to pass in auth details, see the
   n-r-f docs.
 
+* `opts.provenance` - when running in a suppoted CI environment, will trigger
+  the generation of a signed provenance statement to be published alongside
+  the package. Mutually exclusive with the `provenanceFile` option.
+
+* `opts.provenanceFile` - specifies the path to an externally-generated
+  provenance statement to be published alongside the package. Mutually
+  exclusive with the `provenance` option.
+
 #### <a name="publish"></a> `> libpub.publish(manifest, tarData, [opts]) -> Promise`
 
 Sends the package represented by the `manifest` and `tarData` to the
diff --git a/workspaces/libnpmpublish/lib/provenance.js b/workspaces/libnpmpublish/lib/provenance.js
@@ -1,4 +1,5 @@
 const { sigstore } = require('sigstore')
+const { readFile } = require('fs/promises')
 
 const INTOTO_PAYLOAD_TYPE = 'application/vnd.in-toto+json'
 const INTOTO_STATEMENT_TYPE = 'https://in-toto.io/Statement/v0.1'
@@ -66,6 +67,50 @@ const generateProvenance = async (subject, opts) => {
   return sigstore.attest(Buffer.from(JSON.stringify(payload)), INTOTO_PAYLOAD_TYPE, opts)
 }
 
+const verifyProvenance = async (subject, provenancePath) => {
+  let provenanceBundle
+  try {
+    provenanceBundle = JSON.parse(await readFile(provenancePath))
+  } catch (err) {
+    err.message = `Invalid provenance provided: ${err.message}`
+    throw err
+  }
+
+  const payload = extractProvenance(provenanceBundle)
+  if (!payload.subject || !payload.subject.length) {
+    throw new Error('No subject found in sigstore bundle payload')
+  }
+  if (payload.subject.length > 1) {
+    throw new Error('Found more than one subject in the sigstore bundle payload')
+  }
+
+  const bundleSubject = payload.subject[0]
+  if (subject.name !== bundleSubject.name) {
+    throw new Error(
+      `Provenance subject ${bundleSubject.name} does not match the package: ${subject.name}`
+    )
+  }
+  if (subject.digest.sha512 !== bundleSubject.digest.sha512) {
+    throw new Error('Provenance subject digest does not match the package')
+  }
+
+  await sigstore.verify(provenanceBundle)
+  return provenanceBundle
+}
+
+const extractProvenance = (bundle) => {
+  if (!bundle?.dsseEnvelope?.payload) {
+    throw new Error('No dsseEnvelope with payload found in sigstore bundle')
+  }
+  try {
+    return JSON.parse(Buffer.from(bundle.dsseEnvelope.payload, 'base64').toString('utf8'))
+  } catch (err) {
+    err.message = `Failed to parse payload from dsseEnvelope: ${err.message}`
+    throw err
+  }
+}
+
 module.exports = {
   generateProvenance,
+  verifyProvenance,
 }
diff --git a/workspaces/libnpmpublish/lib/publish.js b/workspaces/libnpmpublish/lib/publish.js
@@ -7,7 +7,7 @@ const { URL } = require('url')
 const ssri = require('ssri')
 const ciInfo = require('ci-info')
 
-const { generateProvenance } = require('./provenance')
+const { generateProvenance, verifyProvenance } = require('./provenance')
 
 const TLOG_BASE_URL = 'https://search.sigstore.dev/'
 
@@ -111,7 +111,7 @@ const patchManifest = (_manifest, opts) => {
 }
 
 const buildMetadata = async (registry, manifest, tarballData, spec, opts) => {
-  const { access, defaultTag, algorithms, provenance } = opts
+  const { access, defaultTag, algorithms, provenance, provenanceFile } = opts
   const root = {
     _id: manifest.name,
     name: manifest.name,
@@ -154,66 +154,31 @@ const buildMetadata = async (registry, manifest, tarballData, spec, opts) => {
 
   // Handle case where --provenance flag was set to true
   let transparencyLogUrl
-  if (provenance === true) {
+  if (provenance === true || provenanceFile) {
+    let provenanceBundle
     const subject = {
       name: npa.toPurl(spec),
       digest: { sha512: integrity.sha512[0].hexDigest() },
     }
 
-    // Ensure that we're running in GHA, currently the only supported build environment
-    if (ciInfo.name !== 'GitHub Actions') {
-      throw Object.assign(
-        new Error('Automatic provenance generation not supported outside of GitHub Actions'),
-        { code: 'EUSAGE' }
-      )
-    }
-
-    // Ensure that the GHA OIDC token is available
-    if (!process.env.ACTIONS_ID_TOKEN_REQUEST_URL) {
-      throw Object.assign(
-        /* eslint-disable-next-line max-len */
-        new Error('Provenance generation in GitHub Actions requires "write" access to the "id-token" permission'),
-        { code: 'EUSAGE' }
-      )
-    }
-
-    // Some registries (e.g. GH packages) require auth to check visibility,
-    // and always return 404 when no auth is supplied. In this case we assume
-    // the package is always private and require `--access public` to publish
-    // with provenance.
-    let visibility = { public: false }
-    if (opts.provenance === true && opts.access !== 'public') {
-      try {
-        const res = await npmFetch
-          .json(`${registry}/-/package/${spec.escapedName}/visibility`, opts)
-        visibility = res
-      } catch (err) {
-        if (err.code !== 'E404') {
-          throw err
-        }
+    if (provenance === true) {
+      await ensureProvenanceGeneration(registry, spec, opts)
+      provenanceBundle = await generateProvenance([subject], opts)
+
+      /* eslint-disable-next-line max-len */
+      log.notice('publish', 'Signed provenance statement with source and build information from GitHub Actions')
+
+      const tlogEntry = provenanceBundle?.verificationMaterial?.tlogEntries[0]
+      /* istanbul ignore else */
+      if (tlogEntry) {
+        transparencyLogUrl = `${TLOG_BASE_URL}?logIndex=${tlogEntry.logIndex}`
+        log.notice(
+          'publish',
+          `Provenance statement published to transparency log: ${transparencyLogUrl}`
+        )
       }
-    }
-
-    if (!visibility.public && opts.provenance === true && opts.access !== 'public') {
-      throw Object.assign(
-        /* eslint-disable-next-line max-len */
-        new Error("Can't generate provenance for new or private package, you must set `access` to public."),
-        { code: 'EUSAGE' }
-      )
-    }
-    const provenanceBundle = await generateProvenance([subject], opts)
-
-    /* eslint-disable-next-line max-len */
-    log.notice('publish', 'Signed provenance statement with source and build information from GitHub Actions')
-
-    const tlogEntry = provenanceBundle?.verificationMaterial?.tlogEntries[0]
-    /* istanbul ignore else */
-    if (tlogEntry) {
-      transparencyLogUrl = `${TLOG_BASE_URL}?logIndex=${tlogEntry.logIndex}`
-      log.notice(
-        'publish',
-        `Provenance statement published to transparency log: ${transparencyLogUrl}`
-      )
+    } else {
+      provenanceBundle = await verifyProvenance(subject, provenanceFile)
     }
 
     const serializedBundle = JSON.stringify(provenanceBundle)
@@ -275,4 +240,49 @@ const patchMetadata = (current, newData) => {
   return current
 }
 
+// Check that all the prereqs are met for provenance generation
+const ensureProvenanceGeneration = async (registry, spec, opts) => {
+  // Ensure that we're running in GHA, currently the only supported build environment
+  if (ciInfo.name !== 'GitHub Actions') {
+    throw Object.assign(
+      new Error('Automatic provenance generation not supported outside of GitHub Actions'),
+      { code: 'EUSAGE' }
+    )
+  }
+
+  // Ensure that the GHA OIDC token is available
+  if (!process.env.ACTIONS_ID_TOKEN_REQUEST_URL) {
+    throw Object.assign(
+      /* eslint-disable-next-line max-len */
+      new Error('Provenance generation in GitHub Actions requires "write" access to the "id-token" permission'),
+      { code: 'EUSAGE' }
+    )
+  }
+
+  // Some registries (e.g. GH packages) require auth to check visibility,
+  // and always return 404 when no auth is supplied. In this case we assume
+  // the package is always private and require `--access public` to publish
+  // with provenance.
+  let visibility = { public: false }
+  if (true && opts.access !== 'public') {
+    try {
+      const res = await npmFetch
+        .json(`${registry}/-/package/${spec.escapedName}/visibility`, opts)
+      visibility = res
+    } catch (err) {
+      if (err.code !== 'E404') {
+        throw err
+      }
+    }
+  }
+
+  if (!visibility.public && opts.provenance === true && opts.access !== 'public') {
+    throw Object.assign(
+      /* eslint-disable-next-line max-len */
+      new Error("Can't generate provenance for new or private package, you must set `access` to public."),
+      { code: 'EUSAGE' }
+    )
+  }
+}
+
 module.exports = publish
diff --git a/workspaces/libnpmpublish/test/publish.js b/workspaces/libnpmpublish/test/publish.js
