Forces TPM slot to be "Friendly", allowing NSS to avoid locking

crypto/nss_util.cc

 // Copyright (c) 2012 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 "crypto/nss_util.h"
 #include "crypto/nss_util_internal.h"
 
 #include <nss.h>
 #include <plarena.h>
 #include <prerror.h>
@@ skipping 178 matching lines @@
       PK11SlotInfo* slot = item->module->slots[i];
       if (PK11_GetTokenName(slot) == token_name)
         return PK11_ReferenceSlot(slot);
     }
   }
   return NULL;
 }
 
 #endif  // defined(USE_NSS)
 
+#if defined(OS_CHROMEOS)
+void LogSlotInfo() {
+  AutoSECMODListReadLock auto_lock;
+  SECMODModuleList* head = SECMOD_GetDefaultModuleList();
+  VLOG(1) << "Current PK11 Slot Status:";
+  for (SECMODModuleList* item = head; item != NULL; item = item->next) {
+    int slot_count = item->module->loaded ? item->module->slotCount : 0;
+    for (int i = 0; i < slot_count; i++) {
+      PK11SlotInfo* slot = item->module->slots[i];
+      if (slot) {
+        VLOG(1) << "  ###############################";
+        VLOG(1) << "  Token Name   : " << PK11_GetTokenName(slot);
+        VLOG(1) << "  Slot Name    : " << PK11_GetSlotName(slot);
+        VLOG(1) << "  Slot ID      : " << PK11_GetSlotID(slot);
+        VLOG(1) << "  Is Friendly  : "
+            << (PK11_IsFriendly(slot) ? "True" : "False");
+        VLOG(1) << "  Default Flags: " << PK11_GetDefaultFlags(slot);
+        VLOG(1) << "  Need Login   : "
+            << (PK11_NeedLogin(slot) ? "Yes" : "No");
+        VLOG(1) << "  Is Hardware  :" << (PK11_IsHW(slot) ? "Yes" : "No");
+      }
+    }
+  }
+}
+#endif
+
 // A singleton to initialize/deinitialize NSPR.
 // Separate from the NSS singleton because we initialize NSPR on the UI thread.
 // Now that we're leaking the singleton, we could merge back with the NSS
 // singleton.
 class NSPRInitSingleton {
  private:
   friend struct base::DefaultLazyInstanceTraits<NSPRInitSingleton>;
 
   NSPRInitSingleton() {
     PR_Init(PR_USER_THREAD, PR_PRIORITY_NORMAL, 0);
@@ skipping 323 matching lines @@
   void InitializeTPMTokenInternal(InitializeTPMTokenCallback callback,
                                   bool is_token_ready) {
     if (is_token_ready) {
       // This tries to load the Chaps module so NSS can talk to the hardware
       // TPM.
       if (!chaps_module_) {
         chaps_module_ = LoadModule(
             kChapsModuleName,
             kChapsPath,
             // trustOrder=100 -- means it'll select this as the most
             //   trusted slot for the mechanisms it provides.

[wtc, 2012/04/03 23:00:58]

This comment is incorrect.  'trustOrder' is defined as:
  trustOrder - integer value specifying the order in
  which the trust information for certificates specified
  by tokens on this PKCS #11 library should be rolled up.
  '0' means that tokens on this library should not supply
  trust information (default). The relative order of two
  pkcs#11 libraries which have the same trustOrder value
  is undefined.

I doubt the CHAPS module provides certificate trust
information, so I recommend removing trustOrder=100.

I suspect what you intended may be cipherOrder.  In
any case, I recommend not specifying cipherOrder unless
we know it's necessary.

slotFlags=RSA means "This token should be used for all RSA
operations (other than Private key operations where the key
lives in another token)".  This doesn't seem appropriate for
the CHAPS module.

             // slotParams=... -- selects RSA as the only mechanism, and only
             //   asks for the password when necessary (instead of every
             //   time, or after a timeout).
             "trustOrder=100 slotParams=(1={slotFlags=[RSA] askpw=only})");

[wtc, 2012/04/03 19:56:55]

I can now prove that adding the SECMOD_LoadUserModule function
called by LoadModule won't add SECMOD_FRIENDLY_FLAG to the NSS
slot structure.  I don't know how to fix it yet, but this
confirms the code that rsleevi gave you is necessary.

Did you open a new bug report for this issue?  I can enter
more info there.

[wtc, 2012/04/03 20:47:27]

rsleevi showed that my proof is wrong because I missed one
code path.  So please ignore my declaration of victory.
We still don't know why this doesn't work.

[Ryan Sleevi, 2012/04/03 21:57:14]

This should be
NSS=\"trustOrder=100 slotParams=(1={slotFlags=[RSA] askpw=only})\"

As per https://developer.mozilla.org/en/PKCS11_Module_Specs, the NSS parameters
should be wrapped in a NSS=quoted-string.

Doing this properly causes SECMOD_LoadUserModule to recognize these flags.

[wtc, 2012/04/03 22:17:24]

rsleevi: good job!  Thank you for tracking this down.

I also noticed the lack of NSS= in our module spec
string, but I wasn't sure if the NSS documentation was
talking about some higher-level string that required NSS=.

       }
-      if (chaps_module_) {
+      if (chaps_module_ && chaps_module_->loaded) {
+        int size = 0;
+        PK11DefaultArrayEntry* entries = PK11_GetDefaultArray(&size);

[wtc, 2012/04/03 19:27:26]

It would be a good idea to document where this cryptic code
comes from.  (I think it comes from the NSS command-line tool
'modutil'.)

+        PK11DefaultArrayEntry* friendly_entry = NULL;
+        for (int i = 0; i < size; ++i) {
+          if (entries[i].flag == SECMOD_FRIENDLY_FLAG) {
+            friendly_entry = &entries[i];
+            break;
+          }
+        }
+
         // If this gets set, then we'll use the TPM for certs with
         // private keys, otherwise we'll fall back to the software
         // implementation.
         tpm_slot_ = GetTPMSlot();
+
+        // Force the TPM slot to be "Friendly", since it seems to ignore setting
+        // "PublicCerts" above, and otherwise NSS does some unnecessary locking,

[wtc, 2012/04/03 19:27:26]

Nit: this comment still references "PublicCerts".  I think
you can clarify it by mentioning the LoadModule() call.

+        // and slows things down.
+        if (tpm_slot_ && friendly_entry)
+          PK11_UpdateSlotAttribute(tpm_slot_, friendly_entry, PR_TRUE);
+
+        if (VLOG_IS_ON(1))
+          LogSlotInfo();
+
         callback.Run(tpm_slot_ != NULL);
         return;
       }
     }
     callback.Run(false);
   }
-#endif
+#endif  // defined(OS_CHROMEOS)
 
 #if defined(USE_NSS)
   // Load nss's built-in root certs.
   SECMODModule* InitDefaultRootCerts() {
     SECMODModule* root = LoadModule("Root Certs", "libnssckbi.so", NULL);
     if (root)
       return root;
 
     // Aw, snap.  Can't find/load root cert shared library.
     // This will make it hard to talk to anybody via https.
@@ skipping 60 matching lines @@
   // is fixed, we will no longer need the lock.
   base::Lock write_lock_;
 #endif  // defined(USE_NSS)
 };
 
 // static
 bool NSSInitSingleton::force_nodb_init_ = false;
 
 base::LazyInstance<NSSInitSingleton>::Leaky
     g_nss_singleton = LAZY_INSTANCE_INITIALIZER;
-
 }  // namespace
 
 #if defined(USE_NSS)
 void EarlySetupForNSSInit() {
   FilePath database_dir = GetInitialConfigDirectory();
   if (!database_dir.empty())
     UseLocalCacheOfNSSDatabaseIfNFS(database_dir);
 }
 #endif
 
@@ skipping 147 matching lines @@
 
 PK11SlotInfo* GetPublicNSSKeySlot() {
   return g_nss_singleton.Get().GetPublicNSSKeySlot();
 }
 
 PK11SlotInfo* GetPrivateNSSKeySlot() {
   return g_nss_singleton.Get().GetPrivateNSSKeySlot();
 }
 
 }  // namespace crypto