blob: f04179bde502e093ad641f96079b2533582e143c [file] [log] [blame]
// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <string>
#include <base/basictypes.h>
#include <curl/curl.h>
#include <gtest/gtest_prod.h> // for FRIEND_TEST
#include <openssl/ssl.h>
class MetricsLibraryInterface;
namespace chromeos_update_engine { class PrefsInterface; }
namespace chromeos_update_engine {
// Wrapper for openssl operations with the certificates.
class OpenSSLWrapper {
OpenSSLWrapper() {}
virtual ~OpenSSLWrapper() {}
// Takes an openssl X509_STORE_CTX, extracts the corresponding certificate
// from it and calculates its fingerprint (SHA256 digest). Returns true on
// success and false otherwise.
// |x509_ctx| is the pointer to the openssl object that holds the certificate.
// |out_depth| is the depth of the current certificate, in the certificate
// chain.
// |out_digest_length| is the length of the generated digest.
// |out_digest| is the byte array where the digest itself will be written.
// It should be big enough to hold a SHA1 digest (e.g. EVP_MAX_MD_SIZE).
virtual bool GetCertificateDigest(X509_STORE_CTX* x509_ctx,
int* out_depth,
unsigned int* out_digest_length,
unsigned char* out_digest) const;
// Responsible for checking whether update server certificates change, and
// reporting to UMA when this happens. Since all state information is persisted,
// and openssl forces us to use a static callback with no data pointer, this
// class is entirely static.
class CertificateChecker {
// These values are used to generate the keys of files persisted via prefs.
// This means that changing these will cause loss of information on metrics
// reporting, during the transition.
enum ServerToCheck {
kUpdate = 0,
kDownload = 1,
kNone = 2 // This needs to be the last element. Changing its value is ok.
CertificateChecker() {}
virtual ~CertificateChecker() {}
// This callback is called by libcurl just before the initialization of an
// SSL connection after having processed all other SSL related options. Used
// to check if server certificates change. |ptr| is expected to be a
// pointer to a ServerToCheck.
static CURLcode ProcessSSLContext(CURL* curl_handle, SSL_CTX* ssl_ctx,
void* ptr);
// Flushes to UMA any certificate-related report that was persisted.
static void FlushReport();
// Setters.
static void set_metrics_lib(MetricsLibraryInterface* metrics_lib) {
metrics_lib_ = metrics_lib;
static void set_prefs(PrefsInterface* prefs) {
prefs_ = prefs;
static void set_openssl_wrapper(OpenSSLWrapper* openssl_wrapper) {
openssl_wrapper_ = openssl_wrapper;
FRIEND_TEST(CertificateCheckerTest, NewCertificate);
FRIEND_TEST(CertificateCheckerTest, SameCertificate);
FRIEND_TEST(CertificateCheckerTest, ChangedCertificate);
FRIEND_TEST(CertificateCheckerTest, FailedCertificate);
FRIEND_TEST(CertificateCheckerTest, FlushReport);
FRIEND_TEST(CertificateCheckerTest, FlushNothingToReport);
// These callbacks are called by openssl after initial SSL verification. They
// are used to perform any additional security verification on the connection,
// but we use them here to get hold of the server certificate, in order to
// determine if it has changed since the last connection. Since openssl forces
// us to do this statically, we define two different callbacks for the two
// different official update servers, and only assign the correspondent one.
// The assigned callback is then called once per each certificate on the
// server and returns 1 for success and 0 for failure.
static int VerifySSLCallbackUpdateCheck(int preverify_ok,
X509_STORE_CTX* x509_ctx);
static int VerifySSLCallbackDownload(int preverify_ok,
X509_STORE_CTX* x509_ctx);
// Checks if server certificate for |server_to_check|, stored in |x509_ctx|,
// has changed since last connection to that same server. This is called by
// one of the two callbacks defined above. If certificate fails to check or
// changes, a report is generated and persisted, to be later sent by
// FlushReport. Returns true on success and false otherwise.
static bool CheckCertificateChange(ServerToCheck server_to_check,
int preverify_ok,
X509_STORE_CTX* x509_ctx);
// Metrics library used to report to UMA.
static MetricsLibraryInterface* metrics_lib_;
// Prefs used to store certificates and UMA reports.
static PrefsInterface* prefs_;
// The wrapper for openssl operations.
static OpenSSLWrapper* openssl_wrapper_;
} // namespace chromeos_update_engine