net/cert/test_root_certs_win.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/cert/test_root_certs.h"
   6
   7 #include "base/basictypes.h"
   8 #include "base/lazy_instance.h"
   9 #include "base/logging.h"
  10 #include "base/win/win_util.h"
  11 #include "base/win/windows_version.h"
  12 #include "net/cert/x509_certificate.h"
  13
  14 namespace net {
  15
  16 namespace {
  17
  18 // Provides a CertDllOpenStoreProv callback provider function, to be called
  19 // by CertOpenStore when the CERT_STORE_PROV_SYSTEM_W store is opened. See
  20 // http://msdn.microsoft.com/en-us/library/aa376043(VS.85).aspx.
  21 BOOL WINAPI InterceptedOpenStoreW(LPCSTR store_provider,
  22                                   DWORD encoding,
  23                                   HCRYPTPROV crypt_provider,
  24                                   DWORD flags,
  25                                   const void* extra,
  26                                   HCERTSTORE memory_store,
  27                                   PCERT_STORE_PROV_INFO store_info);
  28
  29 // CryptoAPIInjector is used to inject a store provider function for system
  30 // certificate stores before the one provided internally by Crypt32.dll.
  31 // Once injected, there is no way to remove, so every call to open a system
  32 // store will be redirected to the injected function.
  33 struct CryptoAPIInjector {
  34   // The previous default function for opening system stores. For most
  35   // configurations, this should point to Crypt32's internal
  36   // I_CertDllOpenSystemStoreProvW function.
  37   PFN_CERT_DLL_OPEN_STORE_PROV_FUNC original_function;
  38
  39   // The handle that CryptoAPI uses to ensure the DLL implementing
  40   // |original_function| remains loaded in memory.
  41   HCRYPTOIDFUNCADDR original_handle;
  42
  43  private:
  44   friend struct base::DefaultLazyInstanceTraits<CryptoAPIInjector>;
  45
  46   CryptoAPIInjector()
  47       : original_function(NULL),
  48         original_handle(NULL) {
  49     HCRYPTOIDFUNCSET registered_functions =
  50         CryptInitOIDFunctionSet(CRYPT_OID_OPEN_STORE_PROV_FUNC, 0);
  51
  52     // Preserve the original handler function in |original_function|. If other
  53     // functions are overridden, they will also need to be preserved.
  54     BOOL ok = CryptGetOIDFunctionAddress(
  55         registered_functions, 0, CERT_STORE_PROV_SYSTEM_W, 0,
  56         reinterpret_cast<void**>(&original_function), &original_handle);
  57     DCHECK(ok);
  58
  59     // For now, intercept only the numeric form of the system store
  60     // function, CERT_STORE_PROV_SYSTEM_W (0x0A), which is what Crypt32
  61     // functionality uses exclusively. Depending on the machine that tests
  62     // are being run on, it may prove necessary to also intercept
  63     // sz_CERT_STORE_PROV_SYSTEM_[A/W] and CERT_STORE_PROV_SYSTEM_A, based
  64     // on whether or not any third-party CryptoAPI modules have been
  65     // installed.
  66     const CRYPT_OID_FUNC_ENTRY kFunctionToIntercept =
  67         { CERT_STORE_PROV_SYSTEM_W, &InterceptedOpenStoreW };
  68
  69     // Inject kFunctionToIntercept at the front of the linked list that
  70     // crypt32 uses when CertOpenStore is called, replacing the existing
  71     // registered function.
  72     ok = CryptInstallOIDFunctionAddress(NULL, 0,
  73                                         CRYPT_OID_OPEN_STORE_PROV_FUNC, 1,
  74                                         &kFunctionToIntercept,
  75                                         CRYPT_INSTALL_OID_FUNC_BEFORE_FLAG);
  76     DCHECK(ok);
  77   }
  78
  79   // This is never called, because this object is intentionally leaked.
  80   // Certificate verification happens on a non-joinable worker thread, which
  81   // may still be running when ~AtExitManager is called, so the LazyInstance
  82   // must be leaky.
  83   ~CryptoAPIInjector() {
  84     original_function = NULL;
  85     CryptFreeOIDFunctionAddress(original_handle, NULL);
  86   }
  87 };
  88
  89 base::LazyInstance<CryptoAPIInjector>::Leaky
  90     g_capi_injector = LAZY_INSTANCE_INITIALIZER;
  91
  92 BOOL WINAPI InterceptedOpenStoreW(LPCSTR store_provider,
  93                                   DWORD encoding,
  94                                   HCRYPTPROV crypt_provider,
  95                                   DWORD flags,
  96                                   const void* store_name,
  97                                   HCERTSTORE memory_store,
  98                                   PCERT_STORE_PROV_INFO store_info) {
  99   // If the high word is all zeroes, then |store_provider| is a numeric ID.
 100   // Otherwise, it's a pointer to a null-terminated ASCII string. See the
 101   // documentation for CryptGetOIDFunctionAddress for more information.
 102   uint32 store_as_uint = reinterpret_cast<uint32>(store_provider);
 103   if (store_as_uint > 0xFFFF || store_provider != CERT_STORE_PROV_SYSTEM_W ||
 104       !g_capi_injector.Get().original_function)
 105     return FALSE;
 106
 107   BOOL ok = g_capi_injector.Get().original_function(store_provider, encoding,
 108                                                     crypt_provider, flags,
 109                                                     store_name, memory_store,
 110                                                     store_info);
 111   // Only the Root store should have certificates injected. If
 112   // CERT_SYSTEM_STORE_RELOCATE_FLAG is set, then |store_name| points to a
 113   // CERT_SYSTEM_STORE_RELOCATE_PARA structure, rather than a
 114   // NULL-terminated wide string, so check before making a string
 115   // comparison.
 116   if (!ok || TestRootCerts::GetInstance()->IsEmpty() ||
 117       (flags & CERT_SYSTEM_STORE_RELOCATE_FLAG) ||
 118       lstrcmpiW(reinterpret_cast<LPCWSTR>(store_name), L"root"))
 119     return ok;
 120
 121   // The result of CertOpenStore with CERT_STORE_PROV_SYSTEM_W is documented
 122   // to be a collection store, and that appears to hold for |memory_store|.
 123   // Attempting to add an individual certificate to |memory_store| causes
 124   // the request to be forwarded to the first physical store in the
 125   // collection that accepts modifications, which will cause a secure
 126   // confirmation dialog to be displayed, confirming the user wishes to
 127   // trust the certificate. However, appending a store to the collection
 128   // will merely modify the temporary collection store, and will not persist
 129   // any changes to the underlying physical store. When the |memory_store| is
 130   // searched to see if a certificate is in the Root store, all the
 131   // underlying stores in the collection will be searched, and any certificate
 132   // in temporary_roots() will be found and seen as trusted.
 133   return CertAddStoreToCollection(
 134       memory_store, TestRootCerts::GetInstance()->temporary_roots(), 0, 0);
 135 }
 136
 137 }  // namespace
 138
 139 bool TestRootCerts::Add(X509Certificate* certificate) {
 140   // Ensure that the default CryptoAPI functionality has been intercepted.
 141   // If a test certificate is never added, then no interception should
 142   // happen.
 143   g_capi_injector.Get();
 144
 145   BOOL ok = CertAddCertificateContextToStore(
 146       temporary_roots_, certificate->os_cert_handle(),
 147       CERT_STORE_ADD_NEW, NULL);
 148   if (!ok) {
 149     // If the certificate is already added, return successfully.
 150     return GetLastError() == CRYPT_E_EXISTS;
 151   }
 152
 153   empty_ = false;
 154   return true;
 155 }
 156
 157 void TestRootCerts::Clear() {
 158   empty_ = true;
 159
 160   for (PCCERT_CONTEXT prev_cert =
 161            CertEnumCertificatesInStore(temporary_roots_, NULL);
 162        prev_cert;
 163        prev_cert = CertEnumCertificatesInStore(temporary_roots_, NULL))
 164     CertDeleteCertificateFromStore(prev_cert);
 165 }
 166
 167 bool TestRootCerts::IsEmpty() const {
 168   return empty_;
 169 }
 170
 171 HCERTCHAINENGINE TestRootCerts::GetChainEngine() const {
 172   if (IsEmpty())
 173     return NULL;  // Default chain engine will suffice.
 174
 175   // Windows versions before 7 don't accept the struct size for later versions.
 176   // We report the size of the old struct since we don't need the new members.
 177   static const DWORD kSizeofCertChainEngineConfig =
 178       SIZEOF_STRUCT_WITH_SPECIFIED_LAST_MEMBER(
 179           CERT_CHAIN_ENGINE_CONFIG, CycleDetectionModulus);
 180
 181   // Each HCERTCHAINENGINE caches both the configured system stores and
 182   // information about each chain that has been built. In order to ensure
 183   // that changes to |temporary_roots_| are properly propagated and that the
 184   // various caches are flushed, when at least one certificate is added,
 185   // return a new chain engine for every call. Each chain engine creation
 186   // should re-open the root store, ensuring the most recent changes are
 187   // visible.
 188   CERT_CHAIN_ENGINE_CONFIG engine_config = {
 189     kSizeofCertChainEngineConfig
 190   };
 191   engine_config.dwFlags =
 192       CERT_CHAIN_ENABLE_CACHE_AUTO_UPDATE |
 193       CERT_CHAIN_ENABLE_SHARE_STORE;
 194   HCERTCHAINENGINE chain_engine = NULL;
 195   BOOL ok = CertCreateCertificateChainEngine(&engine_config, &chain_engine);
 196   DCHECK(ok);
 197   return chain_engine;
 198 }
 199
 200 TestRootCerts::~TestRootCerts() {
 201   CertCloseStore(temporary_roots_, 0);
 202 }
 203
 204 void TestRootCerts::Init() {
 205   empty_ = true;
 206   temporary_roots_ = CertOpenStore(
 207       CERT_STORE_PROV_MEMORY, 0, NULL,
 208       CERT_STORE_DEFER_CLOSE_UNTIL_LAST_FREE_FLAG, NULL);
 209   DCHECK(temporary_roots_);
 210 }
 211
 212 }  // namespace net