lib/requirement.h

   1 /*
   2  * Copyright (c) 2006-2007 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 // requirement - Code Requirement Blob description
  26 //
  27 #ifndef _H_REQUIREMENT
  28 #define _H_REQUIREMENT
  29
  30 #include <security_utilities/blob.h>
  31 #include <security_utilities/superblob.h>
  32 #include <security_utilities/hashing.h>
  33 #include <Security/CodeSigning.h>
  34 #include "codedirectory.h"
  35 #include <map>
  36
  37 namespace Security {
  38 namespace CodeSigning {
  39
  40
  41 //
  42 // Single requirement.
  43 // This is a contiguous binary blob, starting with this header
  44 // and followed by binary expr-code. All links within the blob
  45 // are offset-relative to the start of the header.
  46 // This is designed to be a binary stable format. Note that we restrict
  47 // outselves to 4GB maximum size (4 byte size/offset), and we expect real
  48 // Requirement blobs to be fairly small (a few kilobytes at most).
  49 //
  50 // The "kind" field allows for adding different kinds of Requirements altogether
  51 // in the future. We expect to stay within the framework of "opExpr" requirements,
  52 // but it never hurts to have a way out.
  53 //
  54 class Requirement: public Blob<Requirement, 0xfade0c00> {
  55 public:
  56         class Maker;                            // makes Requirement blobs
  57         class Context;                          // evaluation context
  58         class Reader;                           // structured reader
  59         class Interpreter;                      // evaluation engine
  60
  61         // different forms of Requirements. Right now, we only support exprForm ("opExprs")
  62         enum Kind {
  63                 exprForm = 1                    // prefix expr form
  64         };
  65
  66         void kind(Kind k) { mKind = k; }
  67         Kind kind() const { return Kind(uint32_t(mKind)); }
  68
  69         // validate this requirement against a code context
  70         void validate(const Context &ctx, OSStatus failure = errSecCSReqFailed) const;  // throws on all failures
  71         bool validates(const Context &ctx, OSStatus failure = errSecCSReqFailed) const; // returns on clean miss
  72
  73         // certificate positions (within a standard certificate chain)
  74         static const int leafCert = 0;          // index for leaf (first in chain)
  75         static const int anchorCert = -1;       // index for anchor (last in chain)
  76
  77         // the SHA1 hash of the canonical "Apple Anchor", i.e. the X509 Anchor
  78         // that is considered "Apple's anchor certificate", as defined by hashOfCertificate().
  79         static const SHA1::Digest &appleAnchorHash();
  80 #if defined(TEST_APPLE_ANCHOR)
  81         static const char testAppleAnchorEnv[];
  82         static const SHA1::Digest &testAppleAnchorHash();
  83 #endif //TEST_APPLE_ANCHOR
  84
  85         // common alignment rule for all requirement forms
  86         static const size_t baseAlignment = sizeof(uint32_t); // (we might as well say "four")
  87
  88     // canonical (source) names of Requirement types (matched to SecRequirementType in CSCommon.h)
  89     static const char *const typeNames[];
  90
  91         IFDUMP(void dump() const);
  92
  93 private:
  94         Endian<uint32_t> mKind;                 // expression kind
  95 };
  96
  97
  98 //
  99 // An interpretation context
 100 //
 101 struct Requirement::Context {
 102         Context(CFArrayRef certChain, CFDictionaryRef infoDict, CFDictionaryRef entitlementDict, const CodeDirectory *dir)
 103                 : certs(certChain), info(infoDict), entitlements(entitlementDict), directory(dir) { }
 104
 105         const CFArrayRef certs;                                         // certificate chain
 106         const CFDictionaryRef info;                                     // Info.plist
 107         const CFDictionaryRef entitlements;                     // entitlement plist
 108         const CodeDirectory * const directory;          // CodeDirectory
 109
 110         SecCertificateRef cert(int ix) const;           // get a cert from the cert chain
 111         unsigned int certCount() const;                         // length of cert chain
 112 };
 113
 114
 115 //
 116 // exprForm opcodes.
 117 //
 118 // Opcodes are broken into flags in the (HBO) high byte, and an opcode value
 119 // in the remaining 24 bits. Note that opcodes will remain fairly small
 120 // (almost certainly <60000), so we have the third byte to play around with
 121 // in the future, if needed. For now, small opcodes effective reserve this byte
 122 // as zero.
 123 // The flag byte allows for limited understanding of unknown opcodes. It allows
 124 // the interpreter to use the known opcode parts of the program while semi-creatively
 125 // disregarding the parts it doesn't know about. An unrecognized opcode with zero
 126 // flag byte causes evaluation to categorically fail, since the semantics of such
 127 // an opcode cannot safely be predicted.
 128 //
 129 enum {
 130         // semantic bits or'ed into the opcode
 131         opFlagMask =     0xFF000000,    // high bit flags
 132         opGenericFalse = 0x80000000,    // has size field; okay to default to false
 133         opGenericSkip =  0x40000000,    // has size field; skip and continue
 134 };
 135
 136 enum ExprOp {
 137         opFalse,                                                // unconditionally false
 138         opTrue,                                                 // unconditionally true
 139         opIdent,                                                // match canonical code [string]
 140         opAppleAnchor,                                  // signed by Apple as Apple's product
 141         opAnchorHash,                                   // match anchor [cert hash]
 142         opInfoKeyValue,                                 // *legacy* - use opInfoKeyField [key; value]
 143         opAnd,                                                  // binary prefix expr AND expr [expr; expr]
 144         opOr,                                                   // binary prefix expr OR expr [expr; expr]
 145         opCDHash,                                               // match hash of CodeDirectory directly [cd hash]
 146         opNot,                                                  // logical inverse [expr]
 147         opInfoKeyField,                                 // Info.plist key field [string; match suffix]
 148         opCertField,                                    // Certificate field [cert index; field name; match suffix]
 149         opTrustedCert,                                  // require trust settings to approve one particular cert [cert index]
 150         opTrustedCerts,                                 // require trust settings to approve the cert chain
 151         opCertGeneric,                                  // Certificate component by OID [cert index; oid; match suffix]
 152         opAppleGenericAnchor,                   // signed by Apple in any capacity
 153         opEntitlementField,                             // entitlement dictionary field [string; match suffix]
 154         opCertPolicy,                                   // Certificate policy by OID [cert index; oid; match suffix]
 155         opNamedAnchor,                                  // named anchor type
 156         opNamedCode,                                    // named subroutine
 157         exprOpCount                                             // (total opcode count in use)
 158 };
 159
 160 // match suffix opcodes
 161 enum MatchOperation {
 162         matchExists,                                    // anything but explicit "false" - no value stored
 163         matchEqual,                                             // equal (CFEqual)
 164         matchContains,                                  // partial match (substring)
 165         matchBeginsWith,                                // partial match (initial substring)
 166         matchEndsWith,                                  // partial match (terminal substring)
 167         matchLessThan,                                  // less than (string with numeric comparison)
 168         matchGreaterThan,                               // greater than (string with numeric comparison)
 169         matchLessEqual,                                 // less or equal (string with numeric comparison)
 170         matchGreaterEqual,                              // greater or equal (string with numeric comparison)
 171 };
 172
 173
 174 //
 175 // We keep Requirement groups in SuperBlobs, indexed by SecRequirementType
 176 //
 177 typedef SuperBlob<0xfade0c01> Requirements;
 178
 179
 180 //
 181 // A helper to deal with the magic merger logic of internal requirements
 182 //
 183 class InternalRequirements : public Requirements::Maker {
 184 public:
 185         InternalRequirements() : mReqs(NULL) { }
 186         ~InternalRequirements() { ::free((void *)mReqs); }
 187         void operator () (const Requirements *given, const Requirements *defaulted);
 188         operator const Requirements * () const { return mReqs; }
 189
 190 private:
 191         const Requirements *mReqs;
 192 };
 193
 194
 195 //
 196 // Byte order flippers
 197 //
 198 inline CodeSigning::ExprOp h2n(CodeSigning::ExprOp op)
 199 {
 200         uint32_t intOp = (uint32_t) op;
 201         return (CodeSigning::ExprOp) ::h2n(intOp);
 202 }
 203
 204 inline CodeSigning::ExprOp n2h(CodeSigning::ExprOp op)
 205 {
 206         uint32_t intOp = (uint32_t) op;
 207         return (CodeSigning::ExprOp) ::n2h(intOp);
 208 }
 209
 210
 211 inline CodeSigning::MatchOperation h2n(CodeSigning::MatchOperation op)
 212 {
 213         return CodeSigning::MatchOperation(::h2n((uint32_t) op));
 214 }
 215
 216 inline CodeSigning::MatchOperation n2h(CodeSigning::MatchOperation op)
 217 {
 218         return CodeSigning::MatchOperation(::n2h((uint32_t) op));
 219 }
 220
 221
 222 }       // CodeSigning
 223 }       // Security
 224
 225 #endif //_H_REQUIREMENT