JamieMagee
diff --git a/‎workspaces/arborist/lib/script-allowed.js‎
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+const npa = require('npm-package-arg')
+const semver = require('semver')
+const versionFromTgz = require('./version-from-tgz.js')
+
+// Identity matcher for the allowScripts policy.
+//
+// Returns:
+//   - true: at least one allow entry matches and no deny entry matches
+//   - false: at least one deny entry matches (deny wins on conflict)
+//   - null: no entry matches (unreviewed)
+//
+// `policy` is a flat object of `spec-key -> boolean`, where spec-key is
+// anything `npm-package-arg` can parse. `node` is an arborist Node.
+//
+// Identity rules (see RFC npm/rfcs#868):
+//   - registry deps match by the name+version parsed from the lockfile's
+//     resolved URL, NOT by `node.packageName` / `node.version`. Those two
+//     getters return `node.package.name` / `node.package.version`, which
+//     come from the tarball's own package.json and are therefore
+//     attacker-controlled. A package can publish a tarball claiming any
+//     name; the only trusted name is the one baked into the registry URL.
+//   - tarball / file / link / remote: exact match on node.resolved
+//   - git: match on hosted.ssh() plus a short-SHA prefix of the
+//     resolved committish
+
+const isScriptAllowed = (node, policy) => {
+  // Bundled dependencies cannot be allowlisted in Phase 1. The RFC defers
+  // allowlisting them to a follow-up RFC because matching by name@version
+  // from the bundled tarball would reintroduce manifest confusion (a
+  // bundled tarball can claim any name and version). Returning null here
+  // marks bundled deps as unreviewed regardless of any policy entries, so
+  // their install scripts surface in the Phase 1 advisory warning and
+  // (eventually) get blocked at the install-time gate.
+  if (node.inBundle) {
+    return null
+  }
+
+  if (!policy || typeof policy !== 'object') {
+    return null
+  }
+
+  let anyAllow = false
+  let anyDeny = false
+
+  for (const [key, value] of Object.entries(policy)) {
+    if (!matches(node, key)) {
+      continue
+    }
+    if (value === false) {
+      anyDeny = true
+      continue
+    }
+    /* istanbul ignore else: policy values are strictly true/false;
+       defensive guard against unexpected coercions. */
+    if (value === true) {
+      anyAllow = true
+    }
+  }
+
+  if (anyDeny) {
+    return false
+  }
+  if (anyAllow) {
+    return true
+  }
+  return null
+}
+
+const matches = (node, key) => {
+  let parsed
+  try {
+    parsed = npa(key)
+  } catch {
+    return false
+  }
+
+  switch (parsed.type) {
+    case 'tag':
+    case 'range':
+    case 'version':
+      return matchRegistry(node, parsed)
+    case 'git':
+      return matchGit(node, parsed)
+    case 'file':
+    case 'directory':
+      return matchFileOrDir(node, parsed)
+    case 'remote':
+      return matchRemote(node, parsed)
+    case 'alias':
+      // Disallowed: aliases as policy keys do not match anything.
+      // The user has to address the real package name.
+      return false
+    /* istanbul ignore next: switch above covers every npa type we expect;
+       defensive fallback for future npa types. */
+    default:
+      return false
+  }
+}
+
+const matchRegistry = (node, parsed) => {
+  // If this node is not a registry dep, refuse the match. A registry-style
+  // key (`pkg`, `pkg@1`, `pkg@1 || 2`) must not match a tarball or git node
+  // even if their names happen to coincide.
+  if (!isRegistryNode(node)) {
+    return false
+  }
+
+  // Derive the trusted name+version from the lockfile's resolved URL.
+  // Never use `node.packageName` / `node.version` here: those read from
+  // the tarball's own package.json and can be forged by a malicious
+  // publisher to bypass an allowScripts entry.
+  const trusted = getTrustedRegistryIdentity(node)
+  if (!trusted || trusted.name !== parsed.name) {
+    return false
+  }
+
+  // `tag` covers `pkg@latest`. Treat as name-only allow.
+  if (parsed.type === 'tag') {
+    return true
+  }
+
+  // `range` includes `pkg@^1`, `pkg@1 || 2`, `pkg@*`, `pkg@>=0`, and bare
+  // names like `pkg` (npa parses these as range with fetchSpec='*'). The
+  // RFC permits bare names (name-only allow) and exact versions joined by
+  // `||`; ranges like ^/~/>=/< are rejected because they would silently
+  // allow versions the user has never reviewed.
+  if (parsed.type === 'range') {
+    // Bare name or `pkg@*`: treat as name-only allow.
+    if (parsed.fetchSpec === '*' || parsed.rawSpec === '' || parsed.rawSpec === '*') {
+      return true
+    }
+    if (!trusted.version || !isExactVersionDisjunction(parsed.fetchSpec)) {
+      return false
+    }
+    return semver.satisfies(trusted.version, parsed.fetchSpec, { loose: true })
+  }
+
+  // `version` is an exact pin like `pkg@1.2.3`.
+  /* istanbul ignore else: parsed.type at this point is always 'version';
+     the istanbul-ignored fallback below handles the impossible case. */
+  if (parsed.type === 'version') {
+    return trusted.version === parsed.fetchSpec
+  }
+
+  /* istanbul ignore next: parsed.type is constrained to tag/range/version
+     by the caller; this final fallback is defensive. */
+  return false
+}
+
+// Derive a registry node's trusted name+version.
+//
+// Preferred source: the lockfile's resolved URL parsed via
+// versionFromTgz. arborist records the URL when it first adds the dep,
+// before any tarball is unpacked, so the URL cannot be forged by the
+// package's own package.json.
+//
+// Fallback for lockfiles produced with omit-lockfile-registry-resolved
+// (where the URL is absent): take the dep name from an incoming
+// dependency edge. The edge's spec was written by the consumer (or by an
+// upstream package.json), not by the installed tarball. For aliases like
+// `"trusted": "npm:naughty@1.0.0"`, the underlying registered package
+// name is parsed out of the alias `subSpec`. The install location
+// (`node_modules/trusted`) is deliberately not consulted because for
+// aliases it carries only the alias name, which would let a malicious
+// publisher bypass an allowScripts entry written for the real package.
+//
+// Version is left null in the fallback case because the only remaining
+// source for it (`node.version`) reads from the tarball.
+//
+// Returns `{ name, version }` or `null` if no trusted identity exists.
+const getTrustedRegistryIdentity = (node) => {
+  if (node.resolved && typeof node.resolved === 'string') {
+    const parsed = versionFromTgz('', node.resolved)
+    /* istanbul ignore else: versionFromTgz returns either a complete
+       { name, version } or null; partial objects are not produced. */
+    if (parsed && parsed.name && parsed.version) {
+      return parsed
+    }
+  }
+  const name = nameFromEdges(node)
+  if (name) {
+    return { name, version: null }
+  }
+  return null
+}
+
+const nameFromEdges = (node) => {
+  if (!node.edgesIn || typeof node.edgesIn[Symbol.iterator] !== 'function') {
+    return null
+  }
+  for (const edge of node.edgesIn) {
+    let parsed
+    try {
+      parsed = npa.resolve(edge.name, edge.spec)
+    } catch {
+      continue
+    }
+    // Aliases: trust the underlying registered package, not the alias.
+    if (parsed.type === 'alias' && parsed.subSpec && parsed.subSpec.registry) {
+      return parsed.subSpec.name
+    }
+    // Non-aliased registry edge: the edge name is the package name as
+    // written by the consumer / upstream, which is trusted (it is not
+    // read from the installed tarball).
+    if (parsed.registry) {
+      return parsed.name
+    }
+  }
+  return null
+}
+
+// True if `rangeSpec` is one or more exact versions joined by `||`. Anything
+// containing comparator operators (^, ~, >=, <, *) returns false.
+const isExactVersionDisjunction = (rangeSpec) => {
+  /* istanbul ignore next: caller always passes parsed.fetchSpec, which
+     npa guarantees to be a non-empty string for range specs. */
+  if (typeof rangeSpec !== 'string' || rangeSpec.trim() === '') {
+    return false
+  }
+  const parts = rangeSpec.split('||').map(p => p.trim())
+  /* istanbul ignore next: String.prototype.split always returns at least
+     one element; defensive guard only. */
+  if (parts.length === 0) {
+    return false
+  }
+  return parts.every(p => p !== '' && semver.valid(p) !== null)
+}
+
+const matchGit = (node, parsed) => {
+  if (!node.resolved || !node.resolved.startsWith('git')) {
+    return false
+  }
+
+  let nodeParsed
+  try {
+    nodeParsed = npa(node.resolved)
+  } catch {
+    /* istanbul ignore next: npa parsing a git URL we already validated
+       starts with `git` should not throw; defensive guard only. */
+    return false
+  }
+
+  // Compare the host/repo. Both sides should resolve to the same canonical
+  // ssh URL.
+  const noCommittish = { noCommittish: true }
+  const keyHost = parsed.hosted?.ssh(noCommittish)
+  const nodeHost = nodeParsed.hosted?.ssh(noCommittish)
+  if (keyHost && nodeHost) {
+    if (keyHost !== nodeHost) {
+      return false
+    }
+  } else if (parsed.fetchSpec && nodeParsed.fetchSpec) {
+    // Non-hosted git URLs: fall back to fetch spec.
+    if (parsed.fetchSpec !== nodeParsed.fetchSpec) {
+      return false
+    }
+  } else {
+    return false
+  }
+
+  // If the policy key has no committish, name-only match.
+  const keyCommittish = parsed.gitCommittish || parsed.hosted?.committish
+  if (!keyCommittish) {
+    return true
+  }
+
+  // Match the resolved full SHA against the key's committish. Users
+  // typically write short SHAs in the policy; the lockfile stores 40-char
+  // SHAs. Direction matters: the lockfile's full SHA must START WITH the
+  // key's short SHA, never the reverse. A longer key matching a shorter
+  // resolved committish would let a malformed lockfile or a divergent
+  // resolver allow scripts the user never approved.
+  const nodeCommittish = nodeParsed.gitCommittish || nodeParsed.hosted?.committish || ''
+  if (!nodeCommittish) {
+    return false
+  }
+  return nodeCommittish.startsWith(keyCommittish)
+}
+
+const matchFileOrDir = (node, parsed) => {
+  if (!node.resolved) {
+    return false
+  }
+  return node.resolved === parsed.saveSpec || node.resolved === parsed.fetchSpec
+}
+
+const matchRemote = (node, parsed) => {
+  if (!node.resolved) {
+    return false
+  }
+  return node.resolved === parsed.fetchSpec || node.resolved === parsed.saveSpec
+}
+
+const isRegistryNode = (node) => {
+  // Prefer arborist's edge-based check when available (real Node objects).
+  // It inspects the incoming edges' specs and only returns true if every
+  // edge resolves to a registry spec, which is much harder to spoof than
+  // the URL.
+  if (typeof node.isRegistryDependency === 'boolean') {
+    return node.isRegistryDependency
+  }
+  // Fall back to URL parsing for nodes without the arborist getter
+  // (e.g. test fixtures, lockfiles with omit-lockfile-registry-resolved).
+  // Treat the node as a registry dep when:
+  //   - resolved is missing entirely (omitLockfileRegistryResolved),
+  //   - resolved is an https/http URL pointing at a registry tarball, or
+  //   - resolved is undefined and the node has a version (defensive).
+  if (!node.resolved) {
+    return !!node.version
+  }
+  // Registry tarballs live at `<host>/<pkg-name>/-/<pkg-name>-<version>.tgz`.
+  // Require a path segment before `/-/` so an attacker can't lift a
+  // registry-style allow entry to a hostile URL like
+  // `https://evil.com/-/trusted-1.0.0.tgz`.
+  return /^https?:\/\/[^/]+\/.+\/-\/[^/]+-\d/.test(node.resolved)
+}
+
+module.exports = isScriptAllowed
+module.exports.isScriptAllowed = isScriptAllowed
+module.exports.isExactVersionDisjunction = isExactVersionDisjunction
+module.exports.getTrustedRegistryIdentity = getTrustedRegistryIdentity