libsecurity_codesigning/lib/cdbuilder.cpp

   1 /*
   2  * Copyright (c) 2006-2010 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,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 //
  25 // cdbuilder - constructor for CodeDirectories
  26 //
  27 #include "cdbuilder.h"
  28 #include <security_utilities/memutils.h>
  29 #include <cmath>
  30
  31 using namespace UnixPlusPlus;
  32 using LowLevelMemoryUtilities::alignUp;
  33
  34
  35 namespace Security {
  36 namespace CodeSigning {
  37
  38
  39 //
  40 // Create an (empty) builder
  41 //
  42 CodeDirectory::Builder::Builder(HashAlgorithm digestAlgorithm)
  43         : mFlags(0),
  44           mHashType(digestAlgorithm),
  45           mSpecialSlots(0),
  46           mCodeSlots(0),
  47           mScatter(NULL),
  48           mScatterSize(0),
  49           mDir(NULL)
  50 {
  51         mDigestLength = MakeHash<Builder>(this)->digestLength();
  52         mSpecial = (unsigned char *)calloc(cdSlotMax, mDigestLength);
  53 }
  54
  55 CodeDirectory::Builder::~Builder()
  56 {
  57         ::free(mSpecial);
  58         ::free(mScatter);
  59 }
  60
  61
  62 //
  63 // Set the source of the main executable (i.e. the code pages)
  64 //
  65 void CodeDirectory::Builder::executable(string path,
  66         size_t pagesize, size_t offset, size_t length)
  67 {
  68         mExec.close();                  // any previously opened one
  69         mExec.open(path);
  70         mPageSize = pagesize;
  71         mExecOffset = offset;
  72         mExecLength = length;
  73 }
  74
  75 void CodeDirectory::Builder::reopen(string path, size_t offset, size_t length)
  76 {
  77         assert(mExec);                                  // already called executable()
  78         mExec.close();
  79         mExec.open(path);
  80         mExecOffset = offset;
  81         mExecLength = length;
  82 }
  83
  84
  85 //
  86 // Set the source for one special slot
  87 //
  88 void CodeDirectory::Builder::specialSlot(SpecialSlot slot, CFDataRef data)
  89 {
  90         assert(slot <= cdSlotMax);
  91         MakeHash<Builder> hash(this);
  92         hash->update(CFDataGetBytePtr(data), CFDataGetLength(data));
  93         hash->finish(specialSlot(slot));
  94         if (slot >= mSpecialSlots)
  95                 mSpecialSlots = slot;
  96 }
  97
  98
  99 //
 100 // Allocate a Scatter vector
 101 //
 102 CodeDirectory::Scatter *CodeDirectory::Builder::scatter(unsigned count)
 103 {
 104         mScatterSize = (count + 1) * sizeof(Scatter);
 105         if (!(mScatter = (Scatter *)::realloc(mScatter, mScatterSize)))
 106                 UnixError::throwMe(ENOMEM);
 107         ::memset(mScatter, 0, mScatterSize);
 108         return mScatter;
 109 }
 110
 111
 112 //
 113 // Calculate the size we'll need for the CodeDirectory as described so far
 114 //
 115 size_t CodeDirectory::Builder::size()
 116 {
 117         assert(mExec);                  // must have called executable()
 118         if (mExecLength == 0)
 119                 mExecLength = mExec.fileSize() - mExecOffset;
 120
 121         // how many code pages?
 122         if (mPageSize == 0) {   // indefinite - one page
 123                 mCodeSlots = (mExecLength > 0);
 124         } else {                                // finite - calculate from file size
 125                 mCodeSlots = (mExecLength + mPageSize - 1) / mPageSize; // round up
 126         }
 127
 128         size_t offset = sizeof(CodeDirectory);
 129         offset += mScatterSize;                         // scatter vector
 130         offset += mIdentifier.size() + 1;       // size of identifier (with null byte)
 131         offset += (mCodeSlots + mSpecialSlots) * mDigestLength; // hash vector
 132         return offset;
 133 }
 134
 135
 136 //
 137 // Take everything added to date and wrap it up in a shiny new CodeDirectory.
 138 //
 139 // Note that this only constructs a CodeDirectory; it does not touch any subsidiary
 140 // structures (resource tables, etc.), nor does it create any signature to secure
 141 // the CodeDirectory.
 142 // The returned CodeDirectory object is yours, and you may modify it as desired.
 143 // But the memory layout is set here, so the various sizes and counts should be good
 144 // when you call build().
 145 // It's up to us to order the dynamic fields as we wish; but note that we currently
 146 // don't pad them, and so they should be allocated in non-increasing order of required
 147 // alignment. Make sure to keep the code here in sync with the size-calculating code above.
 148 //
 149 CodeDirectory *CodeDirectory::Builder::build()
 150 {
 151         assert(mExec);                  // must have (successfully) called executable()
 152
 153         // size and allocate
 154         size_t identLength = mIdentifier.size() + 1;
 155         size_t total = size();
 156         if (!(mDir = (CodeDirectory *)calloc(1, total)))        // initialize to zero
 157                 UnixError::throwMe(ENOMEM);
 158
 159         // fill header
 160         mDir->initialize(total);
 161         mDir->version = currentVersion;
 162         mDir->flags = mFlags;
 163         mDir->nSpecialSlots = mSpecialSlots;
 164         mDir->nCodeSlots = mCodeSlots;
 165         mDir->codeLimit = mExecLength;
 166         mDir->hashType = mHashType;
 167         mDir->hashSize = mDigestLength;
 168         if (mPageSize) {
 169                 int pglog;
 170                 assert(frexp(mPageSize, &pglog) == 0.5); // must be power of 2
 171                 frexp(mPageSize, &pglog);
 172                 assert(pglog < 256);
 173                 mDir->pageSize = pglog - 1;
 174         } else
 175                 mDir->pageSize = 0;     // means infinite page size
 176
 177         // locate and fill flex fields
 178         size_t offset = sizeof(CodeDirectory);
 179
 180         if (mScatter) {
 181                 mDir->scatterOffset = offset;
 182                 memcpy(mDir->scatterVector(), mScatter, mScatterSize);
 183                 offset += mScatterSize;
 184         }
 185
 186         mDir->identOffset = offset;
 187         memcpy(mDir->identifier(), mIdentifier.c_str(), identLength);
 188         offset += identLength;
 189
 190         // (add new flexibly-allocated fields here)
 191
 192         mDir->hashOffset = offset + mSpecialSlots * mDigestLength;
 193         offset += (mSpecialSlots + mCodeSlots) * mDigestLength;
 194         assert(offset == total);        // matches allocated size
 195
 196         // fill special slots
 197         memset((*mDir)[-mSpecialSlots], 0, mDigestLength * mSpecialSlots);
 198         for (size_t slot = 1; slot <= mSpecialSlots; ++slot)
 199                 memcpy((*mDir)[-slot], specialSlot(slot), mDigestLength);
 200
 201         // fill code slots
 202         mExec.seek(mExecOffset);
 203         size_t remaining = mExecLength;
 204         for (unsigned int slot = 0; slot < mCodeSlots; ++slot) {
 205                 size_t thisPage = min(mPageSize, remaining);
 206                 MakeHash<Builder> hasher(this);
 207                 generateHash(hasher, mExec, (*mDir)[slot], thisPage);
 208                 remaining -= thisPage;
 209         }
 210
 211         // all done. Pass ownership to caller
 212         return mDir;
 213 }
 214
 215
 216 }       // CodeSigning
 217 }       // Security