libsecurity_codesigning/lib/csutilities.h

   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 // csutilities - miscellaneous utilities for the code signing implementation
  26 //
  27 // This is a collection of odds and ends that wouldn't fit anywhere else.
  28 // The common theme is that the contents are otherwise naturally homeless.
  29 //
  30 #ifndef _H_CSUTILITIES
  31 #define _H_CSUTILITIES
  32
  33 #include <Security/Security.h>
  34 #include <security_utilities/hashing.h>
  35 #include <security_utilities/unix++.h>
  36 #include <security_cdsa_utilities/cssmdata.h>
  37 #include <copyfile.h>
  38 #include <asl.h>
  39 #include <cstdarg>
  40
  41 namespace Security {
  42 namespace CodeSigning {
  43
  44
  45 //
  46 // Test for the canonical Apple CA certificate
  47 //
  48 bool isAppleCA(SecCertificateRef cert);
  49 bool isAppleCA(const Hashing::Byte *sha1);
  50
  51
  52 //
  53 // Calculate canonical hashes of certificate.
  54 // This is simply defined as (always) the SHA1 hash of the DER.
  55 //
  56 void hashOfCertificate(const void *certData, size_t certLength, SHA1::Digest digest);
  57 void hashOfCertificate(SecCertificateRef cert, SHA1::Digest digest);
  58 bool verifyHash(SecCertificateRef cert, const Hashing::Byte *digest);
  59
  60
  61 //
  62 // Calculate hashes of (a section of) a file.
  63 // Starts at the current file position.
  64 // Extends to end of file, or (if limit > 0) at most limit bytes.
  65 // Returns number of bytes digested.
  66 //
  67 template <class _Hash>
  68 size_t hashFileData(UnixPlusPlus::FileDesc fd, _Hash *hasher, size_t limit = 0)
  69 {
  70         unsigned char buffer[4096];
  71         size_t total = 0;
  72         for (;;) {
  73                 size_t size = sizeof(buffer);
  74                 if (limit && limit < size)
  75                         size = limit;
  76                 size_t got = fd.read(buffer, size);
  77                 total += got;
  78                 if (fd.atEnd())
  79                         break;
  80                 hasher->update(buffer, got);
  81                 if (limit && (limit -= got) == 0)
  82                         break;
  83         }
  84         return total;
  85 }
  86
  87 template <class _Hash>
  88 size_t hashFileData(const char *path, _Hash *hasher)
  89 {
  90         UnixPlusPlus::AutoFileDesc fd(path);
  91         return hashFileData(fd, hasher);
  92 }
  93
  94
  95 //
  96 // Check to see if a certificate contains a particular field, by OID. This works for extensions,
  97 // even ones not recognized by the local CL. It does not return any value, only presence.
  98 //
  99 bool certificateHasField(SecCertificateRef cert, const CSSM_OID &oid);
 100 bool certificateHasPolicy(SecCertificateRef cert, const CSSM_OID &policyOid);
 101
 102
 103 //
 104 // Encapsulation of the copyfile(3) API.
 105 // This is slated to go into utilities once stable.
 106 //
 107 class Copyfile {
 108 public:
 109         Copyfile();
 110         ~Copyfile()     { copyfile_state_free(mState); }
 111
 112         operator copyfile_state_t () const { return mState; }
 113
 114         void set(uint32_t flag, const void *value);
 115         void get(uint32_t flag, void *value);
 116
 117         void operator () (const char *src, const char *dst, copyfile_flags_t flags);
 118
 119 private:
 120         void check(int rc);
 121
 122 private:
 123         copyfile_state_t mState;
 124 };
 125
 126
 127 //
 128 // MessageTracer support
 129 //
 130 class MessageTrace {
 131 public:
 132         MessageTrace(const char *domain, const char *signature);
 133         void add(const char *key, const char *format, ...);
 134         void send(const char *format, ...);
 135
 136 private:
 137         aslmsg mAsl;
 138 };
 139
 140
 141 //
 142 // A reliable uid set/reset bracket
 143 //
 144 class UidGuard {
 145 public:
 146         UidGuard() : mPrevious(-1) { }
 147         UidGuard(uid_t uid) : mPrevious(-1) { seteuid(uid); }
 148         ~UidGuard()
 149         {
 150                 if (active())
 151                         UnixError::check(::seteuid(mPrevious));
 152         }
 153
 154         bool seteuid(uid_t uid)
 155         {
 156                 if (uid == geteuid())
 157                         return true;    // no change, don't bother the kernel
 158                 if (!active())
 159                         mPrevious = ::geteuid();
 160                 return ::seteuid(uid) == 0;
 161         }
 162
 163         bool active() const { return mPrevious != uid_t(-1); }
 164         operator bool () const { return active(); }
 165         uid_t saved() const { assert(active()); return mPrevious; }
 166
 167 private:
 168         uid_t mPrevious;
 169 };
 170
 171
 172 } // end namespace CodeSigning
 173 } // end namespace Security
 174
 175 #endif // !_H_CSUTILITIES