sandbox/win/src/policy_target.cc

// Copyright (c) 2006-2008 The Chromium 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 "sandbox/win/src/policy_target.h"

#include <stddef.h>

#include "sandbox/win/src/crosscall_client.h"
#include "sandbox/win/src/ipc_tags.h"
#include "sandbox/win/src/policy_engine_processor.h"
#include "sandbox/win/src/policy_low_level.h"
#include "sandbox/win/src/policy_params.h"
#include "sandbox/win/src/sandbox_factory.h"
#include "sandbox/win/src/sandbox_nt_util.h"
#include "sandbox/win/src/sharedmem_ipc_client.h"
#include "sandbox/win/src/target_services.h"

namespace sandbox {

// Handle for our private heap.
extern void* g_heap;

// This is the list of all imported symbols from ntdll.dll.
SANDBOX_INTERCEPT NtExports g_nt;

// Policy data.
extern void* volatile g_shared_policy_memory;
SANDBOX_INTERCEPT size_t g_shared_policy_size;

bool QueryBroker(int ipc_id, CountedParameterSetBase* params) {
  DCHECK_NT(static_cast<size_t>(ipc_id) < kMaxServiceCount);
  DCHECK_NT(g_shared_policy_memory);
  DCHECK_NT(g_shared_policy_size > 0);

  if (static_cast<size_t>(ipc_id) >= kMaxServiceCount)
    return false;

  PolicyGlobal* global_policy =
      reinterpret_cast<PolicyGlobal*>(g_shared_policy_memory);

  if (!global_policy->entry[ipc_id])
    return false;

  PolicyBuffer* policy = reinterpret_cast<PolicyBuffer*>(
      reinterpret_cast<char*>(g_shared_policy_memory) +
      reinterpret_cast<size_t>(global_policy->entry[ipc_id]));

  if ((reinterpret_cast<size_t>(global_policy->entry[ipc_id]) >
       global_policy->data_size) ||
      (g_shared_policy_size < global_policy->data_size)) {
    NOTREACHED_NT();
    return false;
  }

  for (size_t i = 0; i < params->count; i++) {
    if (!params->parameters[i].IsValid()) {
      NOTREACHED_NT();
      return false;
    }
  }

  PolicyProcessor processor(policy);
  PolicyResult result =
      processor.Evaluate(kShortEval, params->parameters, params->count);
  DCHECK_NT(POLICY_ERROR != result);

  return POLICY_MATCH == result && ASK_BROKER == processor.GetAction();
}

// -----------------------------------------------------------------------

// Hooks NtSetInformationThread to block RevertToSelf from being
// called before the actual call to LowerToken.
NTSTATUS WINAPI TargetNtSetInformationThread(
    NtSetInformationThreadFunction orig_SetInformationThread,
    HANDLE thread,
    NT_THREAD_INFORMATION_CLASS thread_info_class,
    PVOID thread_information,
    ULONG thread_information_bytes) {
  do {
    if (SandboxFactory::GetTargetServices()->GetState()->RevertedToSelf())
      break;
    if (ThreadImpersonationToken != thread_info_class)
      break;
    // This is a revert to self.
    return STATUS_SUCCESS;
  } while (false);

  return orig_SetInformationThread(
      thread, thread_info_class, thread_information, thread_information_bytes);
}

// Hooks NtOpenThreadToken to force the open_as_self parameter to be set to
// false if we are still running with the impersonation token. open_as_self set
// to true means that the token will be open using the process token instead of
// the impersonation token. This is bad because the process token does not have
// access to open the thread token.
NTSTATUS WINAPI
TargetNtOpenThreadToken(NtOpenThreadTokenFunction orig_OpenThreadToken,
                        HANDLE thread,
                        ACCESS_MASK desired_access,
                        BOOLEAN open_as_self,
                        PHANDLE token) {
  if (!SandboxFactory::GetTargetServices()->GetState()->RevertedToSelf())
    open_as_self = false;

  return orig_OpenThreadToken(thread, desired_access, open_as_self, token);
}

// See comment for TargetNtOpenThreadToken
NTSTATUS WINAPI
TargetNtOpenThreadTokenEx(NtOpenThreadTokenExFunction orig_OpenThreadTokenEx,
                          HANDLE thread,
                          ACCESS_MASK desired_access,
                          BOOLEAN open_as_self,
                          ULONG handle_attributes,
                          PHANDLE token) {
  if (!SandboxFactory::GetTargetServices()->GetState()->RevertedToSelf())
    open_as_self = false;

  return orig_OpenThreadTokenEx(thread, desired_access, open_as_self,
                                handle_attributes, token);
}

}  // namespace sandbox