sandbox/src/restricted_token_utils.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 <aclapi.h>
   6 #include <sddl.h>
   7 #include <vector>
   8
   9 #include "sandbox/src/restricted_token_utils.h"
  10
  11 #include "base/logging.h"
  12 #include "base/win/scoped_handle.h"
  13 #include "base/win/scoped_process_information.h"
  14 #include "base/win/windows_version.h"
  15 #include "sandbox/src/job.h"
  16 #include "sandbox/src/restricted_token.h"
  17 #include "sandbox/src/security_level.h"
  18 #include "sandbox/src/sid.h"
  19
  20 namespace sandbox {
  21
  22 DWORD CreateRestrictedToken(HANDLE *token_handle,
  23                             TokenLevel security_level,
  24                             IntegrityLevel integrity_level,
  25                             TokenType token_type) {
  26   if (!token_handle)
  27     return ERROR_BAD_ARGUMENTS;
  28
  29   RestrictedToken restricted_token;
  30   restricted_token.Init(NULL);  // Initialized with the current process token
  31
  32   std::vector<std::wstring> privilege_exceptions;
  33   std::vector<Sid> sid_exceptions;
  34
  35   bool deny_sids = true;
  36   bool remove_privileges = true;
  37
  38   switch (security_level) {
  39     case USER_UNPROTECTED: {
  40       deny_sids = false;
  41       remove_privileges = false;
  42       break;
  43     }
  44     case USER_RESTRICTED_SAME_ACCESS: {
  45       deny_sids = false;
  46       remove_privileges = false;
  47
  48       unsigned err_code = restricted_token.AddRestrictingSidAllSids();
  49       if (ERROR_SUCCESS != err_code)
  50         return err_code;
  51
  52       break;
  53     }
  54     case USER_NON_ADMIN: {
  55       sid_exceptions.push_back(WinBuiltinUsersSid);
  56       sid_exceptions.push_back(WinWorldSid);
  57       sid_exceptions.push_back(WinInteractiveSid);
  58       sid_exceptions.push_back(WinAuthenticatedUserSid);
  59       privilege_exceptions.push_back(SE_CHANGE_NOTIFY_NAME);
  60       break;
  61     }
  62     case USER_INTERACTIVE: {
  63       sid_exceptions.push_back(WinBuiltinUsersSid);
  64       sid_exceptions.push_back(WinWorldSid);
  65       sid_exceptions.push_back(WinInteractiveSid);
  66       sid_exceptions.push_back(WinAuthenticatedUserSid);
  67       privilege_exceptions.push_back(SE_CHANGE_NOTIFY_NAME);
  68       restricted_token.AddRestrictingSid(WinBuiltinUsersSid);
  69       restricted_token.AddRestrictingSid(WinWorldSid);
  70       restricted_token.AddRestrictingSid(WinRestrictedCodeSid);
  71       restricted_token.AddRestrictingSidCurrentUser();
  72       restricted_token.AddRestrictingSidLogonSession();
  73       break;
  74     }
  75     case USER_LIMITED: {
  76       sid_exceptions.push_back(WinBuiltinUsersSid);
  77       sid_exceptions.push_back(WinWorldSid);
  78       sid_exceptions.push_back(WinInteractiveSid);
  79       privilege_exceptions.push_back(SE_CHANGE_NOTIFY_NAME);
  80       restricted_token.AddRestrictingSid(WinBuiltinUsersSid);
  81       restricted_token.AddRestrictingSid(WinWorldSid);
  82       restricted_token.AddRestrictingSid(WinRestrictedCodeSid);
  83
  84       // This token has to be able to create objects in BNO.
  85       // Unfortunately, on vista, it needs the current logon sid
  86       // in the token to achieve this. You should also set the process to be
  87       // low integrity level so it can't access object created by other
  88       // processes.
  89       if (base::win::GetVersion() >= base::win::VERSION_VISTA)
  90         restricted_token.AddRestrictingSidLogonSession();
  91       break;
  92     }
  93     case USER_RESTRICTED: {
  94       privilege_exceptions.push_back(SE_CHANGE_NOTIFY_NAME);
  95       restricted_token.AddUserSidForDenyOnly();
  96       restricted_token.AddRestrictingSid(WinRestrictedCodeSid);
  97       break;
  98     }
  99     case USER_LOCKDOWN: {
 100       restricted_token.AddUserSidForDenyOnly();
 101       restricted_token.AddRestrictingSid(WinNullSid);
 102       break;
 103     }
 104     default: {
 105       return ERROR_BAD_ARGUMENTS;
 106     }
 107   }
 108
 109   DWORD err_code = ERROR_SUCCESS;
 110   if (deny_sids) {
 111     err_code = restricted_token.AddAllSidsForDenyOnly(&sid_exceptions);
 112     if (ERROR_SUCCESS != err_code)
 113       return err_code;
 114   }
 115
 116   if (remove_privileges) {
 117     err_code = restricted_token.DeleteAllPrivileges(&privilege_exceptions);
 118     if (ERROR_SUCCESS != err_code)
 119       return err_code;
 120   }
 121
 122   restricted_token.SetIntegrityLevel(integrity_level);
 123
 124   switch (token_type) {
 125     case PRIMARY: {
 126       err_code = restricted_token.GetRestrictedTokenHandle(token_handle);
 127       break;
 128     }
 129     case IMPERSONATION: {
 130       err_code = restricted_token.GetRestrictedTokenHandleForImpersonation(
 131           token_handle);
 132       break;
 133     }
 134     default: {
 135       err_code = ERROR_BAD_ARGUMENTS;
 136       break;
 137     }
 138   }
 139
 140   return err_code;
 141 }
 142
 143 DWORD StartRestrictedProcessInJob(wchar_t *command_line,
 144                                   TokenLevel primary_level,
 145                                   TokenLevel impersonation_level,
 146                                   JobLevel job_level,
 147                                   HANDLE *const job_handle_ret) {
 148   Job job;
 149   DWORD err_code = job.Init(job_level, NULL, 0);
 150   if (ERROR_SUCCESS != err_code)
 151     return err_code;
 152
 153   if (JOB_UNPROTECTED != job_level) {
 154     // Share the Desktop handle to be able to use MessageBox() in the sandboxed
 155     // application.
 156     err_code = job.UserHandleGrantAccess(GetDesktopWindow());
 157     if (ERROR_SUCCESS != err_code)
 158       return err_code;
 159   }
 160
 161   // Create the primary (restricted) token for the process
 162   HANDLE primary_token_handle = NULL;
 163   err_code = CreateRestrictedToken(&primary_token_handle,
 164                                    primary_level,
 165                                    INTEGRITY_LEVEL_LAST,
 166                                    PRIMARY);
 167   if (ERROR_SUCCESS != err_code) {
 168     return err_code;
 169   }
 170   base::win::ScopedHandle primary_token(primary_token_handle);
 171
 172   // Create the impersonation token (restricted) to be able to start the
 173   // process.
 174   HANDLE impersonation_token_handle;
 175   err_code = CreateRestrictedToken(&impersonation_token_handle,
 176                                    impersonation_level,
 177                                    INTEGRITY_LEVEL_LAST,
 178                                    IMPERSONATION);
 179   if (ERROR_SUCCESS != err_code) {
 180     return err_code;
 181   }
 182   base::win::ScopedHandle impersonation_token(impersonation_token_handle);
 183
 184   // Start the process
 185   STARTUPINFO startup_info = {0};
 186   base::win::ScopedProcessInformation process_info;
 187
 188   if (!::CreateProcessAsUser(primary_token.Get(),
 189                              NULL,   // No application name.
 190                              command_line,
 191                              NULL,   // No security attribute.
 192                              NULL,   // No thread attribute.
 193                              FALSE,  // Do not inherit handles.
 194                              CREATE_SUSPENDED | CREATE_BREAKAWAY_FROM_JOB,
 195                              NULL,   // Use the environment of the caller.
 196                              NULL,   // Use current directory of the caller.
 197                              &startup_info,
 198                              process_info.Receive())) {
 199     return ::GetLastError();
 200   }
 201
 202   // Change the token of the main thread of the new process for the
 203   // impersonation token with more rights.
 204   {
 205     HANDLE temp_thread = process_info.thread_handle();
 206     if (!::SetThreadToken(&temp_thread, impersonation_token.Get())) {
 207       ::TerminateProcess(process_info.process_handle(),
 208                          0);  // exit code
 209       return ::GetLastError();
 210     }
 211   }
 212
 213   err_code = job.AssignProcessToJob(process_info.process_handle());
 214   if (ERROR_SUCCESS != err_code) {
 215     ::TerminateProcess(process_info.process_handle(),
 216                        0);  // exit code
 217     return ::GetLastError();
 218   }
 219
 220   // Start the application
 221   ::ResumeThread(process_info.thread_handle());
 222
 223   (*job_handle_ret) = job.Detach();
 224
 225   return ERROR_SUCCESS;
 226 }
 227
 228 DWORD SetObjectIntegrityLabel(HANDLE handle, SE_OBJECT_TYPE type,
 229                               const wchar_t* ace_access,
 230                               const wchar_t* integrity_level_sid) {
 231   // Build the SDDL string for the label.
 232   std::wstring sddl = L"S:(";     // SDDL for a SACL.
 233   sddl += SDDL_MANDATORY_LABEL;   // Ace Type is "Mandatory Label".
 234   sddl += L";;";                  // No Ace Flags.
 235   sddl += ace_access;             // Add the ACE access.
 236   sddl += L";;;";                 // No ObjectType and Inherited Object Type.
 237   sddl += integrity_level_sid;    // Trustee Sid.
 238   sddl += L")";
 239
 240   DWORD error = ERROR_SUCCESS;
 241   PSECURITY_DESCRIPTOR sec_desc = NULL;
 242
 243   PACL sacl = NULL;
 244   BOOL sacl_present = FALSE;
 245   BOOL sacl_defaulted = FALSE;
 246
 247   if (::ConvertStringSecurityDescriptorToSecurityDescriptorW(sddl.c_str(),
 248                                                              SDDL_REVISION,
 249                                                              &sec_desc, NULL)) {
 250     if (::GetSecurityDescriptorSacl(sec_desc, &sacl_present, &sacl,
 251                                     &sacl_defaulted)) {
 252       error = ::SetSecurityInfo(handle, type,
 253                                 LABEL_SECURITY_INFORMATION, NULL, NULL, NULL,
 254                                 sacl);
 255     } else {
 256       error = ::GetLastError();
 257     }
 258
 259     ::LocalFree(sec_desc);
 260   } else {
 261     return::GetLastError();
 262   }
 263
 264   return error;
 265 }
 266
 267 const wchar_t* GetIntegrityLevelString(IntegrityLevel integrity_level) {
 268   switch (integrity_level) {
 269     case INTEGRITY_LEVEL_SYSTEM:
 270       return L"S-1-16-16384";
 271     case INTEGRITY_LEVEL_HIGH:
 272       return L"S-1-16-12288";
 273     case INTEGRITY_LEVEL_MEDIUM:
 274       return L"S-1-16-8192";
 275     case INTEGRITY_LEVEL_MEDIUM_LOW:
 276       return L"S-1-16-6144";
 277     case INTEGRITY_LEVEL_LOW:
 278       return L"S-1-16-4096";
 279     case INTEGRITY_LEVEL_BELOW_LOW:
 280       return L"S-1-16-2048";
 281     case INTEGRITY_LEVEL_UNTRUSTED:
 282       return L"S-1-16-0";
 283     case INTEGRITY_LEVEL_LAST:
 284       return NULL;
 285   }
 286
 287   NOTREACHED();
 288   return NULL;
 289 }
 290 DWORD SetTokenIntegrityLevel(HANDLE token, IntegrityLevel integrity_level) {
 291   if (base::win::GetVersion() < base::win::VERSION_VISTA)
 292     return ERROR_SUCCESS;
 293
 294   const wchar_t* integrity_level_str = GetIntegrityLevelString(integrity_level);
 295   if (!integrity_level_str) {
 296     // No mandatory level specified, we don't change it.
 297     return ERROR_SUCCESS;
 298   }
 299
 300   PSID integrity_sid = NULL;
 301   if (!::ConvertStringSidToSid(integrity_level_str, &integrity_sid))
 302     return ::GetLastError();
 303
 304   TOKEN_MANDATORY_LABEL label = {0};
 305   label.Label.Attributes = SE_GROUP_INTEGRITY;
 306   label.Label.Sid = integrity_sid;
 307
 308   DWORD size = sizeof(TOKEN_MANDATORY_LABEL) + ::GetLengthSid(integrity_sid);
 309   BOOL result = ::SetTokenInformation(token, TokenIntegrityLevel, &label,
 310                                       size);
 311   ::LocalFree(integrity_sid);
 312
 313   return result ? ERROR_SUCCESS : ::GetLastError();
 314 }
 315
 316 DWORD SetProcessIntegrityLevel(IntegrityLevel integrity_level) {
 317   if (base::win::GetVersion() < base::win::VERSION_VISTA)
 318     return ERROR_SUCCESS;
 319
 320   // We don't check for an invalid level here because we'll just let it
 321   // fail on the SetTokenIntegrityLevel call later on.
 322   if (integrity_level == INTEGRITY_LEVEL_LAST) {
 323     // No mandatory level specified, we don't change it.
 324     return ERROR_SUCCESS;
 325   }
 326
 327   HANDLE token_handle;
 328   if (!::OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_DEFAULT,
 329                           &token_handle))
 330     return ::GetLastError();
 331
 332   base::win::ScopedHandle token(token_handle);
 333
 334   return SetTokenIntegrityLevel(token.Get(), integrity_level);
 335 }
 336
 337 }  // namespace sandbox