Adding method to create process using LowBox token in sandbox code.

sandbox/win/src/sandbox_policy_base.cc

Index: sandbox/win/src/sandbox_policy_base.cc
diff --git a/sandbox/win/src/sandbox_policy_base.cc b/sandbox/win/src/sandbox_policy_base.cc
index d3c920e6429c0e7119a34d423747ec921113603e..b297035c19a0552d4c9e3ed7b77a46edfbfbf2c5 100644
--- a/sandbox/win/src/sandbox_policy_base.cc
+++ b/sandbox/win/src/sandbox_policy_base.cc
@@ -98,7 +98,8 @@ PolicyBase::PolicyBase()
       mitigations_(0),
       delayed_mitigations_(0),
       policy_maker_(NULL),
-      policy_(NULL) {
+      policy_(NULL),
+      lowbox_sid_(NULL) {
   ::InitializeCriticalSection(&lock_);
   // Initialize the IPC dispatcher array.
   memset(&ipc_targets_, NULL, sizeof(ipc_targets_));
@@ -152,6 +153,10 @@ PolicyBase::~PolicyBase() {
   delete ipc_targets_[IPC_DUPLICATEHANDLEPROXY_TAG];
   delete policy_maker_;
   delete policy_;
+
+  if (lowbox_sid_)
+    LocalFree(lowbox_sid_);
+
   ::DeleteCriticalSection(&lock_);
 }
 
@@ -331,6 +336,22 @@ ResultCode PolicyBase::SetCapability(const wchar_t* sid) {
   return SBOX_ALL_OK;
 }
 
+ResultCode PolicyBase::SetLowBox(const wchar_t* sid) {
+  // SetLowBox and SetAppContainer are mutually exclusive.
+  if (appcontainer_list_.get())
+    return SBOX_ERROR_UNEXPECTED_CALL;
+
+  DCHECK(sid);
+
+  if (lowbox_sid_)

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: This should be an error.

[Shrikant Kelkar, 2015/02/28 01:55:41]

Done.

+    LocalFree(lowbox_sid_);
+
+  if (!ConvertStringSidToSid(sid, &lowbox_sid_))

[rvargas (doing something else), 2015/02/28 01:10:06]

The should be an OS version check here

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+    return SBOX_ERROR_GENERIC;
+
+  return SBOX_ALL_OK;
+}
+
 ResultCode PolicyBase::SetProcessMitigations(
     MitigationFlags flags) {
   if (!CanSetProcessMitigationsPreStartup(flags))
@@ -448,6 +469,11 @@ ResultCode PolicyBase::MakeJobObject(HANDLE* job) {
 }
 
 ResultCode PolicyBase::MakeTokens(HANDLE* initial, HANDLE* lockdown) {
+  if (appcontainer_list_.get() &&
+      appcontainer_list_->HasAppContainer() &&

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: send this to the previous line

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+      lowbox_sid_)

[rvargas (doing something else), 2015/02/28 01:10:06]

nit : requires {}

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+    return SBOX_ERROR_UNEXPECTED_CALL;

[rvargas (doing something else), 2015/02/28 01:10:06]

SBOX_ERROR_BAD_PARAMS ?

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+
   // Create the 'naked' token. This will be the permanent token associated
   // with the process and therefore with any thread that is not impersonating.
   DWORD result = CreateRestrictedToken(lockdown, lockdown_level_,
@@ -476,6 +502,9 @@ ResultCode PolicyBase::MakeTokens(HANDLE* initial, HANDLE* lockdown) {
     alternate_desktop_integrity_level_label_ = integrity_level_;
   }
 
+  // We are maintaining two approaches this time and making them mutually

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: this time? (aka, remove)

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: we are not making them mutually exclusive... they are mutually exclusive :p

[Shrikant Kelkar, 2015/02/28 01:55:41]

Done.

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+  // exclusive. One is to start appcontainer process through StartupInfoEx

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: start an AppContainer

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+  // and other is by attaching LowBox token after process creation.

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: We don't attach a token, we replace the token

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

   if (appcontainer_list_.get() && appcontainer_list_->HasAppContainer()) {
     // Windows refuses to work with an impersonation token. See SetAppContainer
     // implementation for more details.
@@ -484,6 +513,30 @@ ResultCode PolicyBase::MakeTokens(HANDLE* initial, HANDLE* lockdown) {
 
     *initial = INVALID_HANDLE_VALUE;
     return SBOX_ALL_OK;
+  } else if (lowbox_sid_) {
+    NtCreateLowBoxToken CreateLowBox = NULL;
+    ResolveNTFunctionPtr("NtCreateLowBoxToken", &CreateLowBox);
+
+    HANDLE token_lowbox = NULL;
+

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: remove empty line. In fact, move line 520 to 524

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+    OBJECT_ATTRIBUTES obj_attr;
+    InitializeObjectAttributes(&obj_attr, NULL, 0, NULL, NULL);
+
+    NTSTATUS status = CreateLowBox(&token_lowbox,
+                                   *lockdown,

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: we can fit more arguments per line here...

[Shrikant Kelkar, 2015/02/28 01:55:42]

Done.

+                                   TOKEN_ALL_ACCESS,
+                                   &obj_attr,
+                                   lowbox_sid_,
+                                   0,
+                                   NULL,
+                                   0,
+                                   NULL);
+    if (!NT_SUCCESS(status)) {

[rvargas (doing something else), 2015/02/28 01:10:06]

nit: no {}

[Shrikant Kelkar, 2015/02/28 01:55:41]

Done.

+      return SBOX_ERROR_GENERIC;
+    }
+    DCHECK(token_lowbox);
+    ::CloseHandle(*lockdown);
+    *lockdown = token_lowbox;
   }
 
   // Create the 'better' token. We use this token as the one that the main
@@ -505,6 +558,10 @@ const AppContainerAttributes* PolicyBase::GetAppContainer() const {
   return appcontainer_list_.get();
 }
 
+const PSID PolicyBase::GetLowBoxSid() const {
+  return lowbox_sid_;
+}
+
 bool PolicyBase::AddTarget(TargetProcess* target) {
   if (NULL != policy_)
     policy_maker_->Done();