OSX/libsecurity_codesigning/lib/cdbuilder.cpp

   1 /*
   2  * Copyright (c) 2006-2012,2014 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,
  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           mPlatform(0),
  46           mSpecialSlots(0),
  47           mCodeSlots(0),
  48           mScatter(NULL),
  49           mScatterSize(0),
  50           mExecSegOffset(0),
  51           mExecSegLimit(0),
  52           mExecSegFlags(0),
  53           mDir(NULL)
  54 {
  55         mDigestLength = (uint32_t)MakeHash<Builder>(this)->digestLength();
  56         mSpecial = (unsigned char *)calloc(cdSlotMax, mDigestLength);
  57 }
  58
  59 CodeDirectory::Builder::~Builder()
  60 {
  61         ::free(mSpecial);
  62         ::free(mScatter);
  63 }
  64
  65
  66 //
  67 // Set the source of the main executable (i.e. the code pages)
  68 //
  69 void CodeDirectory::Builder::executable(string path,
  70         size_t pagesize, size_t offset, size_t length)
  71 {
  72         mExec.close();                  // any previously opened one
  73         mExec.open(path);
  74         mPageSize = pagesize;
  75         mExecOffset = offset;
  76         mExecLength = length;
  77 }
  78
  79 void CodeDirectory::Builder::reopen(string path, size_t offset, size_t length)
  80 {
  81         assert(mExec);                                  // already called executable()
  82         mExec.close();
  83         mExec.open(path);
  84         mExecOffset = offset;
  85         mExecLength = length;
  86 }
  87
  88
  89 //
  90 // Set the source for one special slot
  91 //
  92 void CodeDirectory::Builder::specialSlot(SpecialSlot slot, CFDataRef data)
  93 {
  94         assert(slot <= cdSlotMax);
  95         MakeHash<Builder> hash(this);
  96         hash->update(CFDataGetBytePtr(data), CFDataGetLength(data));
  97         hash->finish(specialSlot(slot));
  98         mFilledSpecialSlots.insert(slot);
  99         if (slot >= mSpecialSlots)
 100                 mSpecialSlots = slot;
 101 }
 102
 103
 104 //
 105 // Allocate a Scatter vector
 106 //
 107 CodeDirectory::Scatter *CodeDirectory::Builder::scatter(unsigned count)
 108 {
 109         mScatterSize = (count + 1) * sizeof(Scatter);
 110         if (!(mScatter = (Scatter *)::realloc(mScatter, mScatterSize)))
 111                 UnixError::throwMe(ENOMEM);
 112         ::memset(mScatter, 0, mScatterSize);
 113         return mScatter;
 114 }
 115
 116 //
 117 // Keep the allocated size of the (static) CodeDirectory consistent with
 118 // the version chosen. We dynamically picked the least-needed version
 119 // to provide stability of virtual signatures.
 120 //
 121 size_t CodeDirectory::Builder::fixedSize(const uint32_t version)
 122 {
 123         size_t cdSize = sizeof(CodeDirectory);
 124         if (version < supportsExecSegment)
 125                 cdSize -= sizeof(mDir->execSegBase) + sizeof(mDir->execSegLimit) + sizeof(mDir->execSegFlags);
 126         if (version < supportsCodeLimit64)
 127                 cdSize -= sizeof(mDir->spare3) + sizeof(mDir->codeLimit64);
 128         if (version < supportsTeamID)
 129                 cdSize -= sizeof(mDir->teamIDOffset);
 130
 131         return cdSize;
 132 }
 133
 134 //
 135 // Calculate the size we'll need for the CodeDirectory as described so far
 136 //
 137 size_t CodeDirectory::Builder::size(const uint32_t version)
 138 {
 139         assert(mExec);                  // must have called executable()
 140         if (mExecLength == 0)
 141                 mExecLength = mExec.fileSize() - mExecOffset;
 142
 143         // how many code pages?
 144         if (mExecLength <= 0) { // no code, no slots
 145                 mCodeSlots = 0;
 146         } else if (mPageSize == 0) {    // indefinite - one page
 147                 mCodeSlots = 1;
 148         } else {                                // finite - calculate from file size
 149                 mCodeSlots = (mExecLength - 1) / mPageSize + 1;
 150         }
 151
 152         size_t offset = fixedSize(version);
 153         size_t offset0 = offset;
 154
 155         offset += mScatterSize;                         // scatter vector
 156         offset += mIdentifier.size() + 1;       // size of identifier (with null byte)
 157         if (mTeamID.size())
 158                 offset += mTeamID.size() + 1;   // size of teamID (with null byte)
 159         offset += (mCodeSlots + mSpecialSlots) * mDigestLength; // hash vector
 160         if (offset <= offset0)
 161                 UnixError::throwMe(ENOEXEC);
 162
 163         return offset;
 164 }
 165
 166
 167 //
 168 // Take everything added to date and wrap it up in a shiny new CodeDirectory.
 169 //
 170 // Note that this only constructs a CodeDirectory; it does not touch any subsidiary
 171 // structures (resource tables, etc.), nor does it create any signature to secure
 172 // the CodeDirectory.
 173 // The returned CodeDirectory object is yours, and you may modify it as desired.
 174 // But the memory layout is set here, so the various sizes and counts should be good
 175 // when you call build().
 176 // It's up to us to order the dynamic fields as we wish; but note that we currently
 177 // don't pad them, and so they should be allocated in non-increasing order of required
 178 // alignment. Make sure to keep the code here in sync with the size-calculating code above.
 179 //
 180 CodeDirectory *CodeDirectory::Builder::build()
 181 {
 182         assert(mExec);                  // must have (successfully) called executable()
 183         uint32_t version;
 184
 185         // size and allocate
 186         size_t identLength = mIdentifier.size() + 1;
 187         size_t teamIDLength = mTeamID.size() + 1;
 188
 189         // Determine the version
 190         if (mExecSegLimit > 0) {
 191                 version = currentVersion;
 192         } else if (mExecLength > UINT32_MAX) {
 193                 version = supportsCodeLimit64;
 194         } else if (mTeamID.size()) {
 195                 version = supportsTeamID;
 196         } else {
 197                 version = supportsScatter;
 198         }
 199
 200         if (mCodeSlots > UINT32_MAX)    // (still limited to 32 bits)
 201                 MacOSError::throwMe(errSecCSTooBig);
 202
 203         size_t total = size(version);
 204         if (!(mDir = (CodeDirectory *)calloc(1, total)))        // initialize to zero
 205                 UnixError::throwMe(ENOMEM);
 206
 207         // fill header
 208         mDir->initialize(total);
 209         mDir->version = version;
 210         mDir->flags = mFlags;
 211         mDir->nSpecialSlots = (uint32_t)mSpecialSlots;
 212         mDir->nCodeSlots = (uint32_t)mCodeSlots;
 213         if (mExecLength > UINT32_MAX) {
 214                 mDir->codeLimit = UINT32_MAX;
 215                 mDir->codeLimit64 = mExecLength;
 216         } else {
 217                 mDir->codeLimit = uint32_t(mExecLength);
 218         }
 219         mDir->hashType = mHashType;
 220         mDir->platform = mPlatform;
 221         mDir->hashSize = mDigestLength;
 222         if (mPageSize) {
 223                 int pglog;
 224                 assert(frexp(mPageSize, &pglog) == 0.5); // must be power of 2
 225                 frexp(mPageSize, &pglog);
 226                 assert(pglog < 256);
 227                 mDir->pageSize = pglog - 1;
 228         } else
 229                 mDir->pageSize = 0;     // means infinite page size
 230
 231         mDir->execSegBase = mExecSegOffset;
 232         mDir->execSegLimit = mExecSegLimit;
 233         mDir->execSegFlags = mExecSegFlags;
 234
 235         // locate and fill flex fields
 236         size_t offset = fixedSize(mDir->version);
 237
 238         if (mScatter) {
 239                 mDir->scatterOffset = (uint32_t)offset;
 240                 memcpy(mDir->scatterVector(), mScatter, mScatterSize);
 241                 offset += mScatterSize;
 242         }
 243
 244         mDir->identOffset = (uint32_t)offset;
 245         memcpy(mDir->identifier(), mIdentifier.c_str(), identLength);
 246         offset += identLength;
 247
 248         if (mTeamID.size()) {
 249                 mDir->teamIDOffset = (uint32_t)offset;
 250                 memcpy(mDir->teamID(), mTeamID.c_str(), teamIDLength);
 251                 offset += teamIDLength;
 252         }
 253         // (add new flexibly-allocated fields here)
 254
 255         mDir->hashOffset = (uint32_t)(offset + mSpecialSlots * mDigestLength);
 256         offset += (mSpecialSlots + mCodeSlots) * mDigestLength;
 257         assert(offset == total);        // matches allocated size
 258
 259         (void)offset;
 260
 261         // fill special slots
 262         memset((*mDir)[(int)-mSpecialSlots], 0, mDigestLength * mSpecialSlots);
 263         for (size_t slot = 1; slot <= mSpecialSlots; ++slot)
 264                 memcpy((*mDir)[(int)-slot], specialSlot((SpecialSlot)slot), mDigestLength);
 265
 266         // fill code slots
 267         mExec.seek(mExecOffset);
 268         size_t remaining = mExecLength;
 269         for (unsigned int slot = 0; slot < mCodeSlots; ++slot) {
 270                 size_t thisPage = remaining;
 271                 if (mPageSize)
 272                         thisPage = min(thisPage, mPageSize);
 273                 MakeHash<Builder> hasher(this);
 274                 generateHash(hasher, mExec, (*mDir)[slot], thisPage);
 275                 remaining -= thisPage;
 276         }
 277         assert(remaining == 0);
 278
 279         // all done. Pass ownership to caller
 280         return mDir;
 281 }
 282
 283
 284 }       // CodeSigning
 285 }       // Security