Security/libsecurity_keychain/lib/defaultcreds.cpp

   1 /*
   2  * Copyright (c) 2004,2011-2012,2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  18  * Please see the License for the specific language governing rights and
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  22  */
  23
  24 //
  25 // defaultcreds - default computations for keychain open credentials
  26 //
  27 #include "Keychains.h"
  28 #include "defaultcreds.h"
  29 #include "StorageManager.h"
  30 #include "Globals.h"
  31 #include "KCCursor.h"
  32 #include <security_cdsa_utilities/Schema.h>
  33 #include <algorithm>
  34
  35
  36 namespace Security {
  37 namespace KeychainCore {
  38
  39 using namespace CssmClient;
  40
  41
  42 DefaultCredentials::DefaultCredentials(KeychainImpl* kcImpl, Allocator &alloc)
  43         : TrackingAllocator(alloc), AutoCredentials(static_cast<TrackingAllocator&>(*this)),
  44           mMade(false), mKeychainImpl (kcImpl)
  45 {
  46 }
  47
  48
  49 void DefaultCredentials::clear()
  50 {
  51         TrackingAllocator::reset();
  52         mNeededItems.clear();
  53         mMade = false;
  54 }
  55
  56
  57 //
  58 // The main driver.
  59 // This scans a database for referral records and forms corresponding
  60 // credentials to trigger unlocks.
  61 // Returns true if any valid unlock credentials were found; false otherwise.
  62 // Only throws if the database is messed up.
  63 //
  64 bool DefaultCredentials::operator () (Db database)
  65 {
  66         if (!mMade) {
  67                 try {
  68                         // before we do anything else, see if we have a relation in the database of the appropriate type
  69                         KeychainSchema keychainSchema = mKeychainImpl->keychainSchema();
  70                         if (keychainSchema->hasRecordType(UnlockReferralRecord::recordType))
  71                         {
  72                                 clear();
  73                                 Table<UnlockReferralRecord> referrals(database);
  74                                 for (Table<UnlockReferralRecord>::iterator it = referrals.begin(); it != referrals.end(); it++) {
  75                                         switch ((*it)->type()) {
  76                                         case CSSM_APPLE_UNLOCK_TYPE_KEY_DIRECT:
  77                                         case CSSM_APPLE_UNLOCK_TYPE_WRAPPED_PRIVATE:
  78                                                 keyReferral(**it);
  79                                                 break;
  80                                         default:
  81                                                 secdebug("kcreferral", "referral type %lu (to %s) not supported",
  82                                                         (unsigned long)(*it)->type(), (*it)->dbName().c_str());
  83                                                 break;
  84                                         }
  85                                 }
  86                         }
  87                         secdebug("kcreferral", "%lu samples generated", (unsigned long)size());
  88                 } catch (...) {
  89                         secdebug("kcreferral", "exception setting default credentials for %s; using standard value", database->name());
  90                 }
  91                 mMade = true;
  92         }
  93
  94         return size() > 0;      // got credentials?
  95 }
  96
  97
  98 //
  99 // Process a single referral record. This will handle all known types
 100 // of referrals.
 101 //
 102 void DefaultCredentials::keyReferral(const UnlockReferralRecord &ref)
 103 {
 104         secdebug("kcreferral", "processing type %ld referral to %s",
 105                 (long)ref.type(), ref.dbName().c_str());
 106         DLDbIdentifier identifier(ref.dbName().c_str(), ref.dbGuid(), ref.dbSSID(), ref.dbSSType());
 107
 108         // first, try the keychain indicated
 109         try {
 110                 KeychainList list;
 111                 list.push_back(globals().storageManager.keychain(identifier));
 112                 if (unlockKey(ref, list))       // try just this database...
 113                         return;                                         // ... bingo!
 114         } catch (...) { }
 115
 116         // try the entire search list (just in case)
 117         try {
 118                 secdebug("kcreferral", "no joy with %s; trying the entire keychain list for guid %s",
 119                         ref.dbName().c_str(), ref.dbGuid().toString().c_str());
 120                 unlockKey(ref, fallbackSearchList(identifier));
 121                 return;
 122         } catch (...) { }
 123         secdebug("kcreferral", "no luck at all; we'll skip this record");
 124 }
 125
 126
 127 bool DefaultCredentials::unlockKey(const UnlockReferralRecord &ref, const KeychainList &list)
 128 {
 129         bool foundSome = false;
 130         try {
 131                 // form the query
 132                 SecKeychainAttribute attributes[1] = {
 133                         { kSecKeyLabel, (UInt32)ref.keyLabel().length(), ref.keyLabel().data() }
 134                 };
 135                 SecKeychainAttributeList search = { 1, attributes };
 136                 CSSM_DB_RECORDTYPE recordType =
 137                         (ref.type() == CSSM_APPLE_UNLOCK_TYPE_KEY_DIRECT) ?
 138                                 CSSM_DL_DB_RECORD_SYMMETRIC_KEY : CSSM_DL_DB_RECORD_PRIVATE_KEY;
 139                 KCCursor cursor(list, recordType, &search);
 140
 141                 Item keyItem;
 142                 while (cursor->next(keyItem)) {
 143                         secdebug("kcreferral", "located source key in %s", keyItem->keychain()->name());
 144
 145                         // get a reference to the key in the provider keychain
 146                         CssmClient::Key key = dynamic_cast<KeyItem &>(*keyItem).key();
 147                         const CssmKey &masterKey = key;
 148
 149                         // get the CSP handle FOR THE UNLOCKING KEY'S KEYCHAIN
 150                         CSSM_CSP_HANDLE cspHandle = key->csp()->handle();
 151
 152                         // (a)symmetric-key form: KCLOCK, (A)SYMMETRIC_KEY, cspHandle, masterKey
 153                         // Note that the last list element ("ref") is doing an implicit cast to a
 154                         // CssmData, which passes the data portion of the UnlockReferralRecord
 155                         append(TypedList(allocator, CSSM_SAMPLE_TYPE_KEYCHAIN_LOCK,
 156                                 new(allocator) ListElement((recordType==CSSM_DL_DB_RECORD_SYMMETRIC_KEY)?
 157                                         CSSM_WORDID_SYMMETRIC_KEY:CSSM_WORDID_ASYMMETRIC_KEY),
 158                                 new(allocator) ListElement(allocator, CssmData::wrap(cspHandle)),
 159                                 new(allocator) ListElement(allocator, CssmData::wrap(masterKey)),
 160                                 new(allocator) ListElement(allocator, ref.get())
 161                                 ));
 162
 163                         // let's make sure everything we need stays around
 164                         mNeededItems.insert(keyItem);
 165                         foundSome = true;
 166                 }
 167         } catch (...) {
 168                 // (ignore it)
 169         }
 170         return foundSome;
 171 }
 172
 173
 174 //
 175 // Take the official keychain search list, and return those keychains whose
 176 // module Guid matches the one given. Essentially, this focuses the search list
 177 // to a particular type of keychain.
 178 //
 179 struct NotGuid {
 180         NotGuid(const Guid &g) : guid(g) { }
 181         const Guid &guid;
 182         bool operator () (Keychain kc) { return kc->database()->dl()->guid() != guid; }
 183 };
 184
 185 DefaultCredentials::KeychainList DefaultCredentials::fallbackSearchList(const DLDbIdentifier &ident)
 186 {
 187         KeychainList list;
 188         globals().storageManager.getSearchList(list);
 189         list.erase(remove_if(list.begin(), list.end(), NotGuid(ident.ssuid().guid())), list.end());
 190         return list;
 191 }
 192
 193
 194 }       // namespace KeychainCore
 195 }       // namespace Security