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 <windows.h>
   8 #include <wincrypt.h>
   9
  10 #include "base/basictypes.h"
  11 #include "base/lazy_instance.h"
  12 #include "base/logging.h"
  13 #include "base/win/win_util.h"
  14 #include "base/win/windows_version.h"
  15 #include "net/cert/x509_certificate.h"
  16
  17 namespace net {
  18
  19 namespace {
  20
  21 // Provides a CertDllOpenStoreProv callback provider function, to be called
  22 // by CertOpenStore when the CERT_STORE_PROV_SYSTEM_W store is opened. See
  23 // http://msdn.microsoft.com/en-us/library/aa376043(VS.85).aspx.
  24 BOOL WINAPI InterceptedOpenStoreW(LPCSTR store_provider,
  25                                   DWORD encoding,
  26                                   HCRYPTPROV crypt_provider,
  27                                   DWORD flags,
  28                                   const void* extra,
  29                                   HCERTSTORE memory_store,
  30                                   PCERT_STORE_PROV_INFO store_info);
  31
  32 // CryptoAPIInjector is used to inject a store provider function for system
  33 // certificate stores before the one provided internally by Crypt32.dll.
  34 // Once injected, there is no way to remove, so every call to open a system
  35 // store will be redirected to the injected function.
  36 struct CryptoAPIInjector {
  37   // The previous default function for opening system stores. For most
  38   // configurations, this should point to Crypt32's internal
  39   // I_CertDllOpenSystemStoreProvW function.
  40   PFN_CERT_DLL_OPEN_STORE_PROV_FUNC original_function;
  41
  42   // The handle that CryptoAPI uses to ensure the DLL implementing
  43   // |original_function| remains loaded in memory.
  44   HCRYPTOIDFUNCADDR original_handle;
  45
  46  private:
  47   friend struct base::DefaultLazyInstanceTraits<CryptoAPIInjector>;
  48
  49   CryptoAPIInjector()
  50       : original_function(NULL),
  51         original_handle(NULL) {
  52     HCRYPTOIDFUNCSET registered_functions =
  53         CryptInitOIDFunctionSet(CRYPT_OID_OPEN_STORE_PROV_FUNC, 0);
  54
  55     // Preserve the original handler function in |original_function|. If other
  56     // functions are overridden, they will also need to be preserved.
  57     BOOL ok = CryptGetOIDFunctionAddress(
  58         registered_functions, 0, CERT_STORE_PROV_SYSTEM_W, 0,
  59         reinterpret_cast<void**>(&original_function), &original_handle);
  60     DCHECK(ok);
  61
  62     // For now, intercept only the numeric form of the system store
  63     // function, CERT_STORE_PROV_SYSTEM_W (0x0A), which is what Crypt32
  64     // functionality uses exclusively. Depending on the machine that tests
  65     // are being run on, it may prove necessary to also intercept
  66     // sz_CERT_STORE_PROV_SYSTEM_[A/W] and CERT_STORE_PROV_SYSTEM_A, based
  67     // on whether or not any third-party CryptoAPI modules have been
  68     // installed.
  69     const CRYPT_OID_FUNC_ENTRY kFunctionToIntercept =
  70         { CERT_STORE_PROV_SYSTEM_W, &InterceptedOpenStoreW };
  71
  72     // Inject kFunctionToIntercept at the front of the linked list that
  73     // crypt32 uses when CertOpenStore is called, replacing the existing
  74     // registered function.
  75     ok = CryptInstallOIDFunctionAddress(NULL, 0,
  76                                         CRYPT_OID_OPEN_STORE_PROV_FUNC, 1,
  77                                         &kFunctionToIntercept,
  78                                         CRYPT_INSTALL_OID_FUNC_BEFORE_FLAG);
  79     DCHECK(ok);
  80   }
  81
  82   // This is never called, because this object is intentionally leaked.
  83   // Certificate verification happens on a non-joinable worker thread, which
  84   // may still be running when ~AtExitManager is called, so the LazyInstance
  85   // must be leaky.
  86   ~CryptoAPIInjector() {
  87     original_function = NULL;
  88     CryptFreeOIDFunctionAddress(original_handle, NULL);
  89   }
  90 };
  91
  92 base::LazyInstance<CryptoAPIInjector>::Leaky
  93     g_capi_injector = LAZY_INSTANCE_INITIALIZER;
  94
  95 BOOL WINAPI InterceptedOpenStoreW(LPCSTR store_provider,
  96                                   DWORD encoding,
  97                                   HCRYPTPROV crypt_provider,
  98                                   DWORD flags,
  99                                   const void* store_name,
 100                                   HCERTSTORE memory_store,
 101                                   PCERT_STORE_PROV_INFO store_info) {
 102   // If the high word is all zeroes, then |store_provider| is a numeric ID.
 103   // Otherwise, it's a pointer to a null-terminated ASCII string. See the
 104   // documentation for CryptGetOIDFunctionAddress for more information.
 105   uint32 store_as_uint = reinterpret_cast<uint32>(store_provider);
 106   if (store_as_uint > 0xFFFF || store_provider != CERT_STORE_PROV_SYSTEM_W ||
 107       !g_capi_injector.Get().original_function)
 108     return FALSE;
 109
 110   BOOL ok = g_capi_injector.Get().original_function(store_provider, encoding,
 111                                                     crypt_provider, flags,
 112                                                     store_name, memory_store,
 113                                                     store_info);
 114   // Only the Root store should have certificates injected. If
 115   // CERT_SYSTEM_STORE_RELOCATE_FLAG is set, then |store_name| points to a
 116   // CERT_SYSTEM_STORE_RELOCATE_PARA structure, rather than a
 117   // NULL-terminated wide string, so check before making a string
 118   // comparison.
 119   if (!ok || TestRootCerts::GetInstance()->IsEmpty() ||
 120       (flags & CERT_SYSTEM_STORE_RELOCATE_FLAG) ||
 121       lstrcmpiW(reinterpret_cast<LPCWSTR>(store_name), L"root"))
 122     return ok;
 123
 124   // The result of CertOpenStore with CERT_STORE_PROV_SYSTEM_W is documented
 125   // to be a collection store, and that appears to hold for |memory_store|.
 126   // Attempting to add an individual certificate to |memory_store| causes
 127   // the request to be forwarded to the first physical store in the
 128   // collection that accepts modifications, which will cause a secure
 129   // confirmation dialog to be displayed, confirming the user wishes to
 130   // trust the certificate. However, appending a store to the collection
 131   // will merely modify the temporary collection store, and will not persist
 132   // any changes to the underlying physical store. When the |memory_store| is
 133   // searched to see if a certificate is in the Root store, all the
 134   // underlying stores in the collection will be searched, and any certificate
 135   // in temporary_roots() will be found and seen as trusted.
 136   return CertAddStoreToCollection(
 137       memory_store, TestRootCerts::GetInstance()->temporary_roots(), 0, 0);
 138 }
 139
 140 }  // namespace
 141
 142 bool TestRootCerts::Add(X509Certificate* certificate) {
 143   // Ensure that the default CryptoAPI functionality has been intercepted.
 144   // If a test certificate is never added, then no interception should
 145   // happen.
 146   g_capi_injector.Get();
 147
 148   BOOL ok = CertAddCertificateContextToStore(
 149       temporary_roots_, certificate->os_cert_handle(),
 150       CERT_STORE_ADD_NEW, NULL);
 151   if (!ok) {
 152     // If the certificate is already added, return successfully.
 153     return GetLastError() == CRYPT_E_EXISTS;
 154   }
 155
 156   empty_ = false;
 157   return true;
 158 }
 159
 160 void TestRootCerts::Clear() {
 161   empty_ = true;
 162
 163   for (PCCERT_CONTEXT prev_cert =
 164            CertEnumCertificatesInStore(temporary_roots_, NULL);
 165        prev_cert;
 166        prev_cert = CertEnumCertificatesInStore(temporary_roots_, NULL))
 167     CertDeleteCertificateFromStore(prev_cert);
 168 }
 169
 170 bool TestRootCerts::IsEmpty() const {
 171   return empty_;
 172 }
 173
 174 HCERTCHAINENGINE TestRootCerts::GetChainEngine() const {
 175   if (IsEmpty())
 176     return NULL;  // Default chain engine will suffice.
 177
 178   // Windows versions before 7 don't accept the struct size for later versions.
 179   // We report the size of the old struct since we don't need the new members.
 180   static const DWORD kSizeofCertChainEngineConfig =
 181       SIZEOF_STRUCT_WITH_SPECIFIED_LAST_MEMBER(
 182           CERT_CHAIN_ENGINE_CONFIG, CycleDetectionModulus);
 183
 184   // Each HCERTCHAINENGINE caches both the configured system stores and
 185   // information about each chain that has been built. In order to ensure
 186   // that changes to |temporary_roots_| are properly propagated and that the
 187   // various caches are flushed, when at least one certificate is added,
 188   // return a new chain engine for every call. Each chain engine creation
 189   // should re-open the root store, ensuring the most recent changes are
 190   // visible.
 191   CERT_CHAIN_ENGINE_CONFIG engine_config = {
 192     kSizeofCertChainEngineConfig
 193   };
 194   engine_config.dwFlags =
 195       CERT_CHAIN_ENABLE_CACHE_AUTO_UPDATE |
 196       CERT_CHAIN_ENABLE_SHARE_STORE;
 197   HCERTCHAINENGINE chain_engine = NULL;
 198   BOOL ok = CertCreateCertificateChainEngine(&engine_config, &chain_engine);
 199   DCHECK(ok);
 200   return chain_engine;
 201 }
 202
 203 TestRootCerts::~TestRootCerts() {
 204   CertCloseStore(temporary_roots_, 0);
 205 }
 206
 207 void TestRootCerts::Init() {
 208   empty_ = true;
 209   temporary_roots_ = CertOpenStore(
 210       CERT_STORE_PROV_MEMORY, 0, NULL,
 211       CERT_STORE_DEFER_CLOSE_UNTIL_LAST_FREE_FLAG, NULL);
 212   DCHECK(temporary_roots_);
 213 }
 214
 215 }  // namespace net