libsecurity_codesigning/lib/requirement.h

   1 /*
   2  * Copyright (c) 2006-2012 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 class Requirement::Context {
 102 protected:
 103         Context()
 104                 : certs(NULL), info(NULL), entitlements(NULL), identifier(""), directory(NULL) { }
 105
 106 public:
 107         Context(CFArrayRef certChain, CFDictionaryRef infoDict, CFDictionaryRef entitlementDict,
 108                         const std::string &ident, const CodeDirectory *dir)
 109                 : certs(certChain), info(infoDict), entitlements(entitlementDict), identifier(ident), directory(dir) { }
 110
 111         CFArrayRef certs;                                                               // certificate chain
 112         CFDictionaryRef info;                                                   // Info.plist
 113         CFDictionaryRef entitlements;                                   // entitlement plist
 114         std::string identifier;                                         // signing identifier
 115         const CodeDirectory *directory;                         // CodeDirectory
 116
 117         SecCertificateRef cert(int ix) const;                   // get a cert from the cert chain (NULL if not found)
 118         unsigned int certCount() const;                         // length of cert chain (including root)
 119 };
 120
 121
 122 //
 123 // exprForm opcodes.
 124 //
 125 // Opcodes are broken into flags in the (HBO) high byte, and an opcode value
 126 // in the remaining 24 bits. Note that opcodes will remain fairly small
 127 // (almost certainly <60000), so we have the third byte to play around with
 128 // in the future, if needed. For now, small opcodes effective reserve this byte
 129 // as zero.
 130 // The flag byte allows for limited understanding of unknown opcodes. It allows
 131 // the interpreter to use the known opcode parts of the program while semi-creatively
 132 // disregarding the parts it doesn't know about. An unrecognized opcode with zero
 133 // flag byte causes evaluation to categorically fail, since the semantics of such
 134 // an opcode cannot safely be predicted.
 135 //
 136 enum {
 137         // semantic bits or'ed into the opcode
 138         opFlagMask =     0xFF000000,    // high bit flags
 139         opGenericFalse = 0x80000000,    // has size field; okay to default to false
 140         opGenericSkip =  0x40000000,    // has size field; skip and continue
 141 };
 142
 143 enum ExprOp {
 144         opFalse,                                                // unconditionally false
 145         opTrue,                                                 // unconditionally true
 146         opIdent,                                                // match canonical code [string]
 147         opAppleAnchor,                                  // signed by Apple as Apple's product
 148         opAnchorHash,                                   // match anchor [cert hash]
 149         opInfoKeyValue,                                 // *legacy* - use opInfoKeyField [key; value]
 150         opAnd,                                                  // binary prefix expr AND expr [expr; expr]
 151         opOr,                                                   // binary prefix expr OR expr [expr; expr]
 152         opCDHash,                                               // match hash of CodeDirectory directly [cd hash]
 153         opNot,                                                  // logical inverse [expr]
 154         opInfoKeyField,                                 // Info.plist key field [string; match suffix]
 155         opCertField,                                    // Certificate field [cert index; field name; match suffix]
 156         opTrustedCert,                                  // require trust settings to approve one particular cert [cert index]
 157         opTrustedCerts,                                 // require trust settings to approve the cert chain
 158         opCertGeneric,                                  // Certificate component by OID [cert index; oid; match suffix]
 159         opAppleGenericAnchor,                   // signed by Apple in any capacity
 160         opEntitlementField,                             // entitlement dictionary field [string; match suffix]
 161         opCertPolicy,                                   // Certificate policy by OID [cert index; oid; match suffix]
 162         opNamedAnchor,                                  // named anchor type
 163         opNamedCode,                                    // named subroutine
 164         exprOpCount                                             // (total opcode count in use)
 165 };
 166
 167 // match suffix opcodes
 168 enum MatchOperation {
 169         matchExists,                                    // anything but explicit "false" - no value stored
 170         matchEqual,                                             // equal (CFEqual)
 171         matchContains,                                  // partial match (substring)
 172         matchBeginsWith,                                // partial match (initial substring)
 173         matchEndsWith,                                  // partial match (terminal substring)
 174         matchLessThan,                                  // less than (string with numeric comparison)
 175         matchGreaterThan,                               // greater than (string with numeric comparison)
 176         matchLessEqual,                                 // less or equal (string with numeric comparison)
 177         matchGreaterEqual,                              // greater or equal (string with numeric comparison)
 178 };
 179
 180
 181 //
 182 // We keep Requirement groups in SuperBlobs, indexed by SecRequirementType
 183 //
 184 typedef SuperBlob<0xfade0c01> Requirements;
 185
 186
 187 //
 188 // Byte order flippers
 189 //
 190 inline CodeSigning::ExprOp h2n(CodeSigning::ExprOp op)
 191 {
 192         uint32_t intOp = (uint32_t) op;
 193         return (CodeSigning::ExprOp) ::h2n(intOp);
 194 }
 195
 196 inline CodeSigning::ExprOp n2h(CodeSigning::ExprOp op)
 197 {
 198         uint32_t intOp = (uint32_t) op;
 199         return (CodeSigning::ExprOp) ::n2h(intOp);
 200 }
 201
 202
 203 inline CodeSigning::MatchOperation h2n(CodeSigning::MatchOperation op)
 204 {
 205         return CodeSigning::MatchOperation(::h2n((uint32_t) op));
 206 }
 207
 208 inline CodeSigning::MatchOperation n2h(CodeSigning::MatchOperation op)
 209 {
 210         return CodeSigning::MatchOperation(::n2h((uint32_t) op));
 211 }
 212
 213
 214 }       // CodeSigning
 215 }       // Security
 216
 217 #endif //_H_REQUIREMENT