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fix(publication): authenticate rotation handoffs #48

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Merged
rynfar merged 1 commit into from
Sep 2, 2026
Merged

fix(publication): authenticate rotation handoffs #48

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80 changes: 74 additions & 6 deletions scripts/lib/pylon-bounded-file.mjs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import { createHash } from "node:crypto";
import {
closeSync,
constants,
Expand All @@ -11,10 +12,33 @@ export const PYLON_PUBLICATION_MANIFEST_MAX_BYTES = 64 * 1024;
export const PYLON_STABLE_HISTORY_MAX_MANIFESTS = 4096;
export const PYLON_STABLE_HISTORY_MAX_BYTES = 32 * 1024 * 1024;

export class BoundedFileUnlinkedDuringReadError extends Error {
constructor(path, description, bytes, expectedSha256) {
super(`${description} changed while it was read because the same opened inode was removed.`);
this.name = "BoundedFileUnlinkedDuringReadError";
this.path = path;
this.description = description;
this.bytes = Buffer.from(bytes);
this.expectedSha256 = expectedSha256;
}
}

function sameStat(left, right) {
function sameInodeReadBounds(left, right) {
return left.dev === right.dev && left.ino === right.ino && left.size === right.size &&
left.mtimeMs === right.mtimeMs && left.ctimeMs === right.ctimeMs;
left.mtimeMs === right.mtimeMs;
}

function sameStat(left, right) {
return sameInodeReadBounds(left, right) && left.ctimeMs === right.ctimeMs && left.nlink === right.nlink;
}

function isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing) {
return finalPathMissing && extraBytes === 0 && sameStat(pathEntry, before) &&
sameInodeReadBounds(before, after) && before.nlink > 0 && after.nlink === 0;
}

function exactSha256(bytes, expectedSha256) {
return expectedSha256 !== null && createHash("sha256").update(bytes).digest("hex") === expectedSha256;
}

export async function readBoundedRegularFile(
Expand All @@ -27,9 +51,13 @@ export async function readBoundedRegularFile(
lstatEntry = lstat,
validateHandle,
hooks,
expectedSha256 = null,
} = {},
) {
if (!Number.isSafeInteger(maxBytes) || maxBytes < 1 || !Number.isSafeInteger(minBytes) || minBytes < 0 || minBytes > maxBytes) {
if (
!Number.isSafeInteger(maxBytes) || maxBytes < 1 || !Number.isSafeInteger(minBytes) || minBytes < 0 || minBytes > maxBytes ||
!(expectedSha256 === null || /^[0-9a-f]{64}$/.test(expectedSha256))
) {
throw new Error("Bounded file limits are invalid.");
}
let pathEntry;
Expand All @@ -56,6 +84,7 @@ export async function readBoundedRegularFile(
let before = await handle.stat();
if (!before.isFile()) throw new Error(`${description} is not one regular non-symlink file.`);
if (validateHandle) before = await validateHandle(handle, before, description);
if (!sameStat(pathEntry, before)) throw new Error(`${description} changed while it was read.`);
if (before.size < minBytes || before.size > maxBytes) throw new Error(`${description} exceeds its format byte limit or is malformed.`);
await hooks?.afterInitialStat?.({ path, handle, stat: before });
const bytes = Buffer.alloc(before.size);
Expand All @@ -69,7 +98,24 @@ export async function readBoundedRegularFile(
const { bytesRead: extraBytes } = await handle.read(extra, 0, 1, bytes.length);
await hooks?.beforeFinalStat?.({ path, handle, bytes });
const after = await handle.stat();
if (extraBytes !== 0 || !sameStat(before, after)) throw new Error(`${description} changed while it was read.`);
let finalPathEntry;
let finalPathMissing = false;
try {
finalPathEntry = await lstatEntry(path);
} catch (error) {
if (error?.code !== "ENOENT") throw error;
finalPathMissing = true;
}
if (
isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing) &&
exactSha256(bytes, expectedSha256)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
}
if (
extraBytes !== 0 || finalPathMissing || finalPathEntry.isSymbolicLink?.() || !finalPathEntry.isFile() ||
!sameStat(before, after) || !sameStat(after, finalPathEntry)
) throw new Error(`${description} changed while it was read.`);
return bytes;
} finally {
await handle.close();
Expand All @@ -89,9 +135,13 @@ export function readBoundedRegularFileSync(
readFile = readSync,
closeFile = closeSync,
hooks,
expectedSha256 = null,
} = {},
) {
if (!Number.isSafeInteger(maxBytes) || maxBytes < 1 || !Number.isSafeInteger(minBytes) || minBytes < 0 || minBytes > maxBytes) {
if (
!Number.isSafeInteger(maxBytes) || maxBytes < 1 || !Number.isSafeInteger(minBytes) || minBytes < 0 || minBytes > maxBytes ||
!(expectedSha256 === null || /^[0-9a-f]{64}$/.test(expectedSha256))
) {
throw new Error("Bounded file limits are invalid.");
}
let pathEntry;
Expand All @@ -115,6 +165,7 @@ export function readBoundedRegularFileSync(
try {
const before = statFile(descriptor);
if (!before.isFile()) throw new Error(`${description} is not one regular non-symlink file.`);
if (!sameStat(pathEntry, before)) throw new Error(`${description} changed while it was read.`);
if (before.size < minBytes || before.size > maxBytes) throw new Error(`${description} exceeds its format byte limit or is malformed.`);
hooks?.afterInitialStat?.({ path, descriptor, stat: before });
const bytes = Buffer.alloc(before.size);
Expand All @@ -128,7 +179,24 @@ export function readBoundedRegularFileSync(
const extraBytes = readFile(descriptor, extra, 0, 1, bytes.length);
hooks?.beforeFinalStat?.({ path, descriptor, bytes });
const after = statFile(descriptor);
if (extraBytes !== 0 || !sameStat(before, after)) throw new Error(`${description} changed while it was read.`);
let finalPathEntry;
let finalPathMissing = false;
try {
finalPathEntry = lstatEntry(path);
} catch (error) {
if (error?.code !== "ENOENT") throw error;
finalPathMissing = true;
}
if (
isPinnedHandleRemoval(pathEntry, before, after, extraBytes, finalPathMissing) &&
exactSha256(bytes, expectedSha256)
) {
throw new BoundedFileUnlinkedDuringReadError(path, description, bytes, expectedSha256);
}
if (
extraBytes !== 0 || finalPathMissing || finalPathEntry.isSymbolicLink?.() || !finalPathEntry.isFile() ||
!sameStat(before, after) || !sameStat(after, finalPathEntry)
) throw new Error(`${description} changed while it was read.`);
return bytes;
} finally {
closeFile(descriptor);
Expand Down
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