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      1 // Copyright (c) 2011 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 "chrome/browser/importer/nss_decryptor_system_nss.h"
      6 
      7 #include <pk11pub.h>
      8 #include <pk11sdr.h>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/file_path.h"
     12 #include "base/string_util.h"
     13 #include "base/sys_string_conversions.h"
     14 #include "crypto/nss_util.h"
     15 
     16 NSSDecryptor::NSSDecryptor() : is_nss_initialized_(false), db_slot_(NULL) {}
     17 NSSDecryptor::~NSSDecryptor() {
     18   if (db_slot_) {
     19     // Deliberately leave the user db open, just in case we need to open more
     20     // than one, because there's an NSS bug with reopening user dbs.
     21     // https://bugzilla.mozilla.org/show_bug.cgi?id=506140
     22     // SECMOD_CloseUserDB(db_slot_);
     23     PK11_FreeSlot(db_slot_);
     24   }
     25 }
     26 
     27 bool NSSDecryptor::Init(const FilePath& dll_path, const FilePath& db_path) {
     28   crypto::EnsureNSSInit();
     29   is_nss_initialized_ = true;
     30   const std::string modspec =
     31       StringPrintf("configDir='%s' tokenDescription='Firefox NSS database' "
     32                    "flags=readOnly", db_path.value().c_str());
     33   db_slot_ = SECMOD_OpenUserDB(modspec.c_str());
     34   return db_slot_ != NULL;
     35 }
     36 
     37 // This method is based on some NSS code in
     38 //   security/nss/lib/pk11wrap/pk11sdr.c, CVS revision 1.22
     39 // This code is copied because the implementation assumes the use of the
     40 // internal key slot for decryption, but we need to use another slot.
     41 // The license block is:
     42 /* ***** BEGIN LICENSE BLOCK *****
     43  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
     44  *
     45  * The contents of this file are subject to the Mozilla Public License Version
     46  * 1.1 (the "License"); you may not use this file except in compliance with
     47  * the License. You may obtain a copy of the License at
     48  * http://www.mozilla.org/MPL/
     49  *
     50  * Software distributed under the License is distributed on an "AS IS" basis,
     51  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
     52  * for the specific language governing rights and limitations under the
     53  * License.
     54  *
     55  * The Original Code is the Netscape security libraries.
     56  *
     57  * The Initial Developer of the Original Code is
     58  * Netscape Communications Corporation.
     59  * Portions created by the Initial Developer are Copyright (C) 1994-2000
     60  * the Initial Developer. All Rights Reserved.
     61  *
     62  * Contributor(s):
     63  *   thayes (at) netscape.com
     64  *
     65  * Alternatively, the contents of this file may be used under the terms of
     66  * either the GNU General Public License Version 2 or later (the "GPL"), or
     67  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
     68  * in which case the provisions of the GPL or the LGPL are applicable instead
     69  * of those above. If you wish to allow use of your version of this file only
     70  * under the terms of either the GPL or the LGPL, and not to allow others to
     71  * use your version of this file under the terms of the MPL, indicate your
     72  * decision by deleting the provisions above and replace them with the notice
     73  * and other provisions required by the GPL or the LGPL. If you do not delete
     74  * the provisions above, a recipient may use your version of this file under
     75  * the terms of any one of the MPL, the GPL or the LGPL.
     76  *
     77  * ***** END LICENSE BLOCK ***** */
     78 
     79 /*
     80  * Data structure and template for encoding the result of an SDR operation
     81  *  This is temporary.  It should include the algorithm ID of the encryption
     82  *  mechanism
     83  */
     84 struct SDRResult
     85 {
     86   SECItem keyid;
     87   SECAlgorithmID alg;
     88   SECItem data;
     89 };
     90 typedef struct SDRResult SDRResult;
     91 
     92 static SEC_ASN1Template g_template[] = {
     93   { SEC_ASN1_SEQUENCE, 0, NULL, sizeof (SDRResult) },
     94   { SEC_ASN1_OCTET_STRING, offsetof(SDRResult, keyid) },
     95   { SEC_ASN1_INLINE | SEC_ASN1_XTRN, offsetof(SDRResult, alg),
     96     SEC_ASN1_SUB(SECOID_AlgorithmIDTemplate) },
     97   { SEC_ASN1_OCTET_STRING, offsetof(SDRResult, data) },
     98   { 0 }
     99 };
    100 
    101 static SECStatus
    102 unpadBlock(SECItem *data, int blockSize, SECItem *result)
    103 {
    104   SECStatus rv = SECSuccess;
    105   int padLength;
    106   int i;
    107 
    108   result->data = 0;
    109   result->len = 0;
    110 
    111   /* Remove the padding from the end if the input data */
    112   if (data->len == 0 || data->len % blockSize  != 0) {
    113     rv = SECFailure;
    114     goto loser;
    115   }
    116 
    117   padLength = data->data[data->len-1];
    118   if (padLength > blockSize) { rv = SECFailure; goto loser; }
    119 
    120   /* verify padding */
    121   for (i=data->len - padLength; static_cast<uint32>(i) < data->len; i++) {
    122     if (data->data[i] != padLength) {
    123         rv = SECFailure;
    124         goto loser;
    125     }
    126   }
    127 
    128   result->len = data->len - padLength;
    129   result->data = (unsigned char *)PORT_Alloc(result->len);
    130   if (!result->data) { rv = SECFailure; goto loser; }
    131 
    132   PORT_Memcpy(result->data, data->data, result->len);
    133 
    134   if (padLength < 2) {
    135     return SECWouldBlock;
    136   }
    137 
    138 loser:
    139   return rv;
    140 }
    141 
    142 /* decrypt a block */
    143 static SECStatus
    144 pk11Decrypt(PK11SlotInfo *slot, PLArenaPool *arena,
    145             CK_MECHANISM_TYPE type, PK11SymKey *key,
    146             SECItem *params, SECItem *in, SECItem *result)
    147 {
    148   PK11Context *ctx = 0;
    149   SECItem paddedResult;
    150   SECStatus rv;
    151 
    152   paddedResult.len = 0;
    153   paddedResult.data = 0;
    154 
    155   ctx = PK11_CreateContextBySymKey(type, CKA_DECRYPT, key, params);
    156   if (!ctx) { rv = SECFailure; goto loser; }
    157 
    158   paddedResult.len = in->len;
    159   paddedResult.data = static_cast<unsigned char*>(
    160       PORT_ArenaAlloc(arena, paddedResult.len));
    161 
    162   rv = PK11_CipherOp(ctx, paddedResult.data,
    163                         (int*)&paddedResult.len, paddedResult.len,
    164                         in->data, in->len);
    165   if (rv != SECSuccess) goto loser;
    166 
    167   PK11_Finalize(ctx);
    168 
    169   /* Remove the padding */
    170   rv = unpadBlock(&paddedResult, PK11_GetBlockSize(type, 0), result);
    171   if (rv) goto loser;
    172 
    173 loser:
    174   if (ctx) PK11_DestroyContext(ctx, PR_TRUE);
    175   return rv;
    176 }
    177 
    178 SECStatus NSSDecryptor::PK11SDR_DecryptWithSlot(
    179     PK11SlotInfo* slot, SECItem* data, SECItem* result, void* cx) const {
    180   SECStatus rv = SECSuccess;
    181   PK11SymKey *key = 0;
    182   CK_MECHANISM_TYPE type;
    183   SDRResult sdrResult;
    184   SECItem *params = 0;
    185   SECItem possibleResult = { siBuffer, NULL, 0 };
    186   PLArenaPool *arena = 0;
    187 
    188   arena = PORT_NewArena(SEC_ASN1_DEFAULT_ARENA_SIZE);
    189   if (!arena) { rv = SECFailure; goto loser; }
    190 
    191   /* Decode the incoming data */
    192   memset(&sdrResult, 0, sizeof sdrResult);
    193   rv = SEC_QuickDERDecodeItem(arena, &sdrResult, g_template, data);
    194   if (rv != SECSuccess) goto loser;  /* Invalid format */
    195 
    196   /* Get the parameter values from the data */
    197   params = PK11_ParamFromAlgid(&sdrResult.alg);
    198   if (!params) { rv = SECFailure; goto loser; }
    199 
    200   /* Use triple-DES (Should look up the algorithm) */
    201   type = CKM_DES3_CBC;
    202   key = PK11_FindFixedKey(slot, type, &sdrResult.keyid, cx);
    203   if (!key) {
    204     rv = SECFailure;
    205   } else {
    206     rv = pk11Decrypt(slot, arena, type, key, params,
    207                      &sdrResult.data, result);
    208   }
    209 
    210   /*
    211    * if the pad value was too small (1 or 2), then it's statistically
    212    * 'likely' that (1 in 256) that we may not have the correct key.
    213    * Check the other keys for a better match. If we find none, use
    214    * this result.
    215    */
    216   if (rv == SECWouldBlock)
    217     possibleResult = *result;
    218 
    219   /*
    220    * handle the case where your key indicies may have been broken
    221    */
    222   if (rv != SECSuccess) {
    223     PK11SymKey *keyList = PK11_ListFixedKeysInSlot(slot, NULL, cx);
    224     PK11SymKey *testKey = NULL;
    225     PK11SymKey *nextKey = NULL;
    226 
    227     for (testKey = keyList; testKey;
    228          testKey = PK11_GetNextSymKey(testKey)) {
    229       rv = pk11Decrypt(slot, arena, type, testKey, params,
    230                        &sdrResult.data, result);
    231       if (rv == SECSuccess)
    232         break;
    233 
    234       /* found a close match. If it's our first remember it */
    235       if (rv == SECWouldBlock) {
    236         if (possibleResult.data) {
    237           /* this is unlikely but possible. If we hit this condition,
    238            * we have no way of knowing which possibility to prefer.
    239            * in this case we just match the key the application
    240            * thought was the right one */
    241           SECITEM_ZfreeItem(result, PR_FALSE);
    242         } else {
    243           possibleResult = *result;
    244         }
    245       }
    246     }
    247 
    248     /* free the list */
    249     for (testKey = keyList; testKey; testKey = nextKey) {
    250          nextKey = PK11_GetNextSymKey(testKey);
    251       PK11_FreeSymKey(testKey);
    252     }
    253   }
    254 
    255   /* we didn't find a better key, use the one with a small pad value */
    256   if ((rv != SECSuccess) && (possibleResult.data)) {
    257     *result = possibleResult;
    258     possibleResult.data = NULL;
    259     rv = SECSuccess;
    260   }
    261 
    262  loser:
    263   if (arena) PORT_FreeArena(arena, PR_TRUE);
    264   if (key) PK11_FreeSymKey(key);
    265   if (params) SECITEM_ZfreeItem(params, PR_TRUE);
    266   if (possibleResult.data) SECITEM_ZfreeItem(&possibleResult, PR_FALSE);
    267 
    268   return rv;
    269 }
    270