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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
/* exported ProductAddonChecker */
var EXPORTED_SYMBOLS = ["ProductAddonChecker"];
const { XPCOMUtils } = ChromeUtils.import(
);
const { Log } = ChromeUtils.import("resource://gre/modules/Log.jsm");
const { CertUtils } = ChromeUtils.import(
);
const { OS } = ChromeUtils.import("resource://gre/modules/osfile.jsm");
XPCOMUtils.defineLazyModuleGetters(this, {
});
// This exists so that tests can override the ServiceRequest behaviour for
// downloading the addon update XML file.
var CreateServiceRequest = function() {
return new ServiceRequest();
};
// This will inherit settings from the "addons" logger.
var logger = Log.repository.getLogger("addons.productaddons");
// We want to set the level of this logger independent from its parent to help
// debug things like GMP updates. Link this to its own level pref.
logger.manageLevelFromPref("extensions.logging.productaddons.level");
/**
* Number of milliseconds after which we need to cancel `downloadXMLWithRequest`.
*
* Bug 1087674 suggests that the XHR/ServiceRequest we use in
* `downloadXMLWithRequest` may never terminate in presence of network nuisances
* (e.g. strange antivirus behavior). This timeout is a defensive measure to
* ensure that we fail cleanly in such case.
*/
const TIMEOUT_DELAY_MS = 20000;
// How much of a file to read into memory at a time for hashing
const HASH_CHUNK_SIZE = 8192;
/**
* Gets the status of an XMLHttpRequest either directly or from its underlying
* channel.
*
* @param request
* The XMLHttpRequest.
* @return an integer status value.
*/
function getRequestStatus(request) {
let status = null;
try {
status = request.status;
} catch (e) {}
if (status != null) {
return status;
}
return request.channel.QueryInterface(Ci.nsIRequest).status;
}
/**
* A wrapper around `ServiceRequest` that behaves like a limited `fetch()`.
* This doesn't handle headers like fetch, but can be expanded as callers need.
*
* Use this in order to leverage the `beConservative` flag, for
* example to avoid using HTTP3 to fetch critical data.
*
* @param input a resource
* @returns a Response object
*/
async function conservativeFetch(input) {
return new Promise(function(resolve, reject) {
const request = new ServiceRequest({ mozAnon: true });
request.onerror = () =>
reject(new TypeError("NetworkError: Network request failed"));
request.ontimeout = () =>
reject(new TypeError("Timeout: Network request failed"));
request.onabort = () => reject(new DOMException("Aborted", "AbortError"));
request.onload = () => {
const responseAttributes = {
status: request.status,
statusText: request.statusText,
url: request.responseURL,
};
resolve(new Response(request.response, responseAttributes));
};
const method = "GET";
request.open(method, input, true);
request.send();
});
}
/**
* Verifies the content signature on GMP's update.xml. When we fetch update.xml
* balrog should send back content signature headers, which this function
* is used to verify.
*
* @param data
* The data received from balrog. I.e. the xml contents of update.xml.
* @param contentSignatureHeader
* The contents of the 'content-signature' header received along with
* `data`.
* @return A promise that will resolve to nothing if the signature verification
* succeeds, or rejects on failure, with an Error containing a string
* that explains what failed.
*/
async function verifyGmpContentSignature(data, contentSignatureHeader) {
if (!contentSignatureHeader) {
logger.warn(
"Unexpected missing content signature header during content signature validation"
);
throw new Error(
"Content signature validation failed: missing content signature header"
);
}
// Split out the header. It should contain a the following fields, separated by a semicolon
// - x5u - a URI to the cert chain. See also https://datatracker.ietf.org/doc/html/rfc7515#section-4.1.5
const headerFields = contentSignatureHeader
.split(";") // Split fields...
.map(s => s.trim()) // Remove whitespace...
.map(s => [
// Break each field into it's name and value. This more verbose version is
// used instead of `split()` to handle values that contain = characters. This
// shouldn't happen for the signature because it's base64_url (no = padding),
// but it's not clear if it's possible for the x5u URL (as part of a query).
// Guard anyway, better safe than sorry.
s.substring(0, s.indexOf("=")), // Get field name...
s.substring(s.indexOf("=") + 1), // and field value.
]);
let x5u;
let signature;
for (const [fieldName, fieldValue] of headerFields) {
if (fieldName == "x5u") {
x5u = fieldValue;
} else if (fieldName == "p384ecdsa") {
// The signature needs to contain 'p384ecdsa', so stich it back together.
signature = `p384ecdsa=${fieldValue}`;
}
}
if (!x5u) {
logger.warn("Unexpected missing x5u during content signature validation");
throw new Error("Content signature validation failed: missing x5u");
}
if (!signature) {
logger.warn(
"Unexpected missing signature during content signature validation"
);
throw new Error("Content signature validation failed: missing signature");
}
// The x5u field should contain the location of the cert chain, fetch it.
// Use `conservativeFetch` so we get conservative behaviour and ensure (more)
// reliable fetching.
const certChain = await (await conservativeFetch(x5u)).text();
const verifier = Cc[
"@mozilla.org/security/contentsignatureverifier;1"
].createInstance(Ci.nsIContentSignatureVerifier);
let valid;
try {
valid = await verifier.asyncVerifyContentSignature(
data,
signature,
certChain,
"aus.content-signature.mozilla.org"
);
} catch (err) {
logger.warn(`Unexpected error while validating content signature: ${err}`);
throw new Error(`Content signature validation failed: ${err}`);
}
if (!valid) {
logger.warn("Unexpected invalid content signature found during validation");
throw new Error("Content signature is not valid");
}
}
/**
* Downloads an XML document from a URL optionally testing the SSL certificate
* for certain attributes.
*
* @param url
* The url to download from.
* @param allowNonBuiltIn
* Whether to trust SSL certificates without a built-in CA issuer.
* @param allowedCerts
* The list of certificate attributes to match the SSL certificate
* against or null to skip checks.
* @return a promise that resolves to the ServiceRequest request on success or
* rejects with a JS exception in case of error.
*/
function downloadXMLWithRequest(
url,
allowNonBuiltIn = false,
allowedCerts = null
) {
return new Promise((resolve, reject) => {
let request = CreateServiceRequest();
// This is here to let unit test code override the ServiceRequest.
if (request.wrappedJSObject) {
request = request.wrappedJSObject;
}
request.open("GET", url, true);
request.channel.notificationCallbacks = new CertUtils.BadCertHandler(
allowNonBuiltIn
);
// Prevent the request from reading from the cache.
request.channel.loadFlags |= Ci.nsIRequest.LOAD_BYPASS_CACHE;
// Prevent the request from writing to the cache.
request.channel.loadFlags |= Ci.nsIRequest.INHIBIT_CACHING;
// Don't send any cookies
request.channel.loadFlags |= Ci.nsIRequest.LOAD_ANONYMOUS;
request.timeout = TIMEOUT_DELAY_MS;
request.overrideMimeType("text/xml");
// The Cache-Control header is only interpreted by proxies and the
// final destination. It does not help if a resource is already
// cached locally.
request.setRequestHeader("Cache-Control", "no-cache");
// HTTP/1.0 servers might not implement Cache-Control and
// might only implement Pragma: no-cache
request.setRequestHeader("Pragma", "no-cache");
let fail = event => {
let request = event.target;
let status = getRequestStatus(request);
let message =
"Failed downloading XML, status: " + status + ", reason: " + event.type;
logger.warn(message);
let ex = new Error(message);
ex.status = status;
reject(ex);
};
let success = event => {
logger.info("Completed downloading document");
let request = event.target;
try {
CertUtils.checkCert(request.channel, allowNonBuiltIn, allowedCerts);
} catch (ex) {
logger.error("Request failed certificate checks: " + ex);
ex.status = getRequestStatus(request);
reject(ex);
return;
}
resolve(request);
};
request.addEventListener("error", fail);
request.addEventListener("abort", fail);
request.addEventListener("timeout", fail);
request.addEventListener("load", success);
logger.info("sending request to: " + url);
request.send(null);
});
}
/**
* Downloads an XML document from a URL optionally testing the SSL certificate
* for certain attributes, and/or testing the content signature.
*
* @param url
* The url to download from.
* @param allowNonBuiltIn
* Whether to trust SSL certificates without a built-in CA issuer.
* @param allowedCerts
* The list of certificate attributes to match the SSL certificate
* against or null to skip checks.
* @param verifyContentSignature
* When true, will verify the content signature information from the
* response header. Failure to verify will result in an error.
* @return a promise that resolves to the DOM document downloaded or rejects
* with a JS exception in case of error.
*/
async function downloadXML(
url,
allowNonBuiltIn = false,
allowedCerts = null,
verifyContentSignature = false
) {
let request = await downloadXMLWithRequest(
url,
allowNonBuiltIn,
allowedCerts
);
if (verifyContentSignature) {
await verifyGmpContentSignature(
request.response,
request.getResponseHeader("content-signature")
);
}
return request.responseXML;
}
/**
* Parses a list of add-ons from a DOM document.
*
* @param document
* The DOM document to parse.
* @return null if there is no <addons> element otherwise an object containing
* an array of the addons listed and a field notifying whether the
* fallback was used.
*/
function parseXML(document) {
// Check that the root element is correct
if (document.documentElement.localName != "updates") {
throw new Error(
"got node name: " +
document.documentElement.localName +
", expected: updates"
);
}
// Check if there are any addons elements in the updates element
let addons = document.querySelector("updates:root > addons");
if (!addons) {
return null;
}
let results = [];
let addonList = document.querySelectorAll("updates:root > addons > addon");
for (let addonElement of addonList) {
let addon = {};
for (let name of [
"id",
"URL",
"hashFunction",
"hashValue",
"version",
"size",
]) {
if (addonElement.hasAttribute(name)) {
addon[name] = addonElement.getAttribute(name);
}
}
addon.size = Number(addon.size) || undefined;
results.push(addon);
}
return {
usedFallback: false,
addons: results,
};
}
/**
* Downloads file from a URL using ServiceRequest.
*
* @param url
* The url to download from.
* @param options (optional)
* @param options.httpsOnlyNoUpgrade
* Prevents upgrade to https:// when HTTPS-Only Mode is enabled.
* @return a promise that resolves to the path of a temporary file or rejects
* with a JS exception in case of error.
*/
function downloadFile(url, options = { httpsOnlyNoUpgrade: false }) {
return new Promise((resolve, reject) => {
let sr = new ServiceRequest();
sr.onload = function(response) {
logger.info("downloadFile File download. status=" + sr.status);
if (sr.status != 200 && sr.status != 206) {
reject(Components.Exception("File download failed", sr.status));
return;
}
(async function() {
let f = await OS.File.openUnique(
OS.Path.join(OS.Constants.Path.tmpDir, "tmpaddon")
);
let path = f.path;
logger.info(`Downloaded file will be saved to ${path}`);
await f.file.close();
await OS.File.writeAtomic(path, new Uint8Array(sr.response));
return path;
})().then(resolve, reject);
};
let fail = event => {
let request = event.target;
let status = getRequestStatus(request);
let message =
"Failed downloading via ServiceRequest, status: " +
status +
", reason: " +
event.type;
logger.warn(message);
let ex = new Error(message);
ex.status = status;
reject(ex);
};
sr.addEventListener("error", fail);
sr.addEventListener("abort", fail);
sr.responseType = "arraybuffer";
try {
sr.open("GET", url);
if (options.httpsOnlyNoUpgrade) {
sr.channel.loadInfo.httpsOnlyStatus |= Ci.nsILoadInfo.HTTPS_ONLY_EXEMPT;
}
// Allow deprecated HTTP request from SystemPrincipal
sr.channel.loadInfo.allowDeprecatedSystemRequests = true;
sr.send(null);
} catch (ex) {
reject(ex);
}
});
}
/**
* Convert a string containing binary values to hex.
*/
function binaryToHex(input) {
let result = "";
for (let i = 0; i < input.length; ++i) {
let hex = input.charCodeAt(i).toString(16);
if (hex.length == 1) {
hex = "0" + hex;
}
result += hex;
}
return result;
}
/**
* Calculates the hash of a file.
*
* @param hashFunction
* The type of hash function to use, must be supported by nsICryptoHash.
* @param path
* The path of the file to hash.
* @return a promise that resolves to hash of the file or rejects with a JS
* exception in case of error.
*/
var computeHash = async function(hashFunction, path) {
let file = await OS.File.open(path, { existing: true, read: true });
try {
let hasher = Cc["@mozilla.org/security/hash;1"].createInstance(
Ci.nsICryptoHash
);
hasher.initWithString(hashFunction);
let bytes;
do {
bytes = await file.read(HASH_CHUNK_SIZE);
hasher.update(bytes, bytes.length);
} while (bytes.length == HASH_CHUNK_SIZE);
return binaryToHex(hasher.finish(false));
} finally {
await file.close();
}
};
/**
* Verifies that a downloaded file matches what was expected.
*
* @param properties
* The properties to check, `hashFunction` with `hashValue`
* are supported. Any properties missing won't be checked.
* @param path
* The path of the file to check.
* @return a promise that resolves if the file matched or rejects with a JS
* exception in case of error.
*/
var verifyFile = async function(properties, path) {
if (properties.size !== undefined) {
let stat = await OS.File.stat(path);
if (stat.size != properties.size) {
throw new Error(
"Downloaded file was " +
stat.size +
" bytes but expected " +
properties.size +
" bytes."
);
}
}
if (properties.hashFunction !== undefined) {
let expectedDigest = properties.hashValue.toLowerCase();
let digest = await computeHash(properties.hashFunction, path);
if (digest != expectedDigest) {
throw new Error(
"Hash was `" + digest + "` but expected `" + expectedDigest + "`."
);
}
}
};
const ProductAddonChecker = {
/**
* Downloads a list of add-ons from a URL optionally testing the SSL
* certificate for certain attributes, and/or testing the content signature.
*
* @param url
* The url to download from.
* @param allowNonBuiltIn
* Whether to trust SSL certificates without a built-in CA issuer.
* @param allowedCerts
* The list of certificate attributes to match the SSL certificate
* against or null to skip checks.
* @param verifyContentSignature
* When true, will verify the content signature information from the
* response header. Failure to verify will result in an error.
* @return a promise that resolves to an object containing the list of add-ons
* and whether the local fallback was used, or rejects with a JS
* exception in case of error.
*/
getProductAddonList(
url,
allowNonBuiltIn = false,
allowedCerts = null,
verifyContentSignature = false
) {
return downloadXML(
url,
allowNonBuiltIn,
allowedCerts,
verifyContentSignature
).then(parseXML);
},
/**
* Downloads an add-on to a local file and checks that it matches the expected
* file. The caller is responsible for deleting the temporary file returned.
*
* @param addon
* The addon to download.
* @param options (optional)
* @param options.httpsOnlyNoUpgrade
* Prevents upgrade to https:// when HTTPS-Only Mode is enabled.
* @return a promise that resolves to the temporary file downloaded or rejects
* with a JS exception in case of error.
*/
async downloadAddon(addon, options = { httpsOnlyNoUpgrade: false }) {
let path = await downloadFile(addon.URL, options);
try {
await verifyFile(addon, path);
return path;
} catch (e) {
await OS.File.remove(path);
throw e;
}
},
// For test use only.
computeHash,
};