OSX/libsecurity_codesigning/lib/requirement.h

   1 /*
   2  * Copyright (c) 2006-2012 Apple Inc. All Rights Reserved.
   3  *
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   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
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   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,
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  18  * Please see the License for the specific language governing rights and
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  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 #if defined(TEST_APPLE_ANCHOR)
  78         static const char testAppleAnchorEnv[];
  79         static const SHA1::Digest &testAppleAnchorHash();
  80 #endif //TEST_APPLE_ANCHOR
  81
  82         // common alignment rule for all requirement forms
  83         static const size_t baseAlignment = sizeof(uint32_t); // (we might as well say "four")
  84
  85     // canonical (source) names of Requirement types (matched to SecRequirementType in CSCommon.h)
  86     static const char *const typeNames[];
  87
  88         IFDUMP(void dump() const);
  89
  90 private:
  91         Endian<uint32_t> mKind;                 // expression kind
  92 };
  93
  94
  95 //
  96 // An interpretation context
  97 //
  98 class Requirement::Context {
  99 protected:
 100         Context()
 101                 : certs(NULL), info(NULL), entitlements(NULL), identifier(""), directory(NULL) { }
 102
 103 public:
 104         Context(CFArrayRef certChain, CFDictionaryRef infoDict, CFDictionaryRef entitlementDict,
 105                         const std::string &ident, const CodeDirectory *dir)
 106                 : certs(certChain), info(infoDict), entitlements(entitlementDict), identifier(ident), directory(dir) { }
 107
 108         CFArrayRef certs;                                                               // certificate chain
 109         CFDictionaryRef info;                                                   // Info.plist
 110         CFDictionaryRef entitlements;                                   // entitlement plist
 111         std::string identifier;                                         // signing identifier
 112         const CodeDirectory *directory;                         // CodeDirectory
 113
 114         SecCertificateRef cert(int ix) const;                   // get a cert from the cert chain (NULL if not found)
 115         unsigned int certCount() const;                         // length of cert chain (including root)
 116 };
 117
 118
 119 //
 120 // exprForm opcodes.
 121 //
 122 // Opcodes are broken into flags in the (HBO) high byte, and an opcode value
 123 // in the remaining 24 bits. Note that opcodes will remain fairly small
 124 // (almost certainly <60000), so we have the third byte to play around with
 125 // in the future, if needed. For now, small opcodes effective reserve this byte
 126 // as zero.
 127 // The flag byte allows for limited understanding of unknown opcodes. It allows
 128 // the interpreter to use the known opcode parts of the program while semi-creatively
 129 // disregarding the parts it doesn't know about. An unrecognized opcode with zero
 130 // flag byte causes evaluation to categorically fail, since the semantics of such
 131 // an opcode cannot safely be predicted.
 132 //
 133 enum {
 134         // semantic bits or'ed into the opcode
 135         opFlagMask =     0xFF000000,    // high bit flags
 136         opGenericFalse = 0x80000000,    // has size field; okay to default to false
 137         opGenericSkip =  0x40000000,    // has size field; skip and continue
 138 };
 139
 140 enum ExprOp {
 141         opFalse,                                                // unconditionally false
 142         opTrue,                                                 // unconditionally true
 143         opIdent,                                                // match canonical code [string]
 144         opAppleAnchor,                                  // signed by Apple as Apple's product
 145         opAnchorHash,                                   // match anchor [cert hash]
 146         opInfoKeyValue,                                 // *legacy* - use opInfoKeyField [key; value]
 147         opAnd,                                                  // binary prefix expr AND expr [expr; expr]
 148         opOr,                                                   // binary prefix expr OR expr [expr; expr]
 149         opCDHash,                                               // match hash of CodeDirectory directly [cd hash]
 150         opNot,                                                  // logical inverse [expr]
 151         opInfoKeyField,                                 // Info.plist key field [string; match suffix]
 152         opCertField,                                    // Certificate field [cert index; field name; match suffix]
 153         opTrustedCert,                                  // require trust settings to approve one particular cert [cert index]
 154         opTrustedCerts,                                 // require trust settings to approve the cert chain
 155         opCertGeneric,                                  // Certificate component by OID [cert index; oid; match suffix]
 156         opAppleGenericAnchor,                   // signed by Apple in any capacity
 157         opEntitlementField,                             // entitlement dictionary field [string; match suffix]
 158         opCertPolicy,                                   // Certificate policy by OID [cert index; oid; match suffix]
 159         opNamedAnchor,                                  // named anchor type
 160         opNamedCode,                                    // named subroutine
 161         opPlatform,                                             // platform constraint [integer]
 162         exprOpCount                                             // (total opcode count in use)
 163 };
 164
 165 // match suffix opcodes
 166 enum MatchOperation {
 167         matchExists,                                    // anything but explicit "false" - no value stored
 168         matchEqual,                                             // equal (CFEqual)
 169         matchContains,                                  // partial match (substring)
 170         matchBeginsWith,                                // partial match (initial substring)
 171         matchEndsWith,                                  // partial match (terminal substring)
 172         matchLessThan,                                  // less than (string with numeric comparison)
 173         matchGreaterThan,                               // greater than (string with numeric comparison)
 174         matchLessEqual,                                 // less or equal (string with numeric comparison)
 175         matchGreaterEqual,                              // greater or equal (string with numeric comparison)
 176 };
 177
 178
 179 //
 180 // We keep Requirement groups in SuperBlobs, indexed by SecRequirementType
 181 //
 182 typedef SuperBlob<0xfade0c01> Requirements;
 183
 184
 185 //
 186 // Byte order flippers
 187 //
 188 inline CodeSigning::ExprOp h2n(CodeSigning::ExprOp op)
 189 {
 190         uint32_t intOp = (uint32_t) op;
 191         return (CodeSigning::ExprOp) ::h2n(intOp);
 192 }
 193
 194 inline CodeSigning::ExprOp n2h(CodeSigning::ExprOp op)
 195 {
 196         uint32_t intOp = (uint32_t) op;
 197         return (CodeSigning::ExprOp) ::n2h(intOp);
 198 }
 199
 200
 201 inline CodeSigning::MatchOperation h2n(CodeSigning::MatchOperation op)
 202 {
 203         return CodeSigning::MatchOperation(::h2n((uint32_t) op));
 204 }
 205
 206 inline CodeSigning::MatchOperation n2h(CodeSigning::MatchOperation op)
 207 {
 208         return CodeSigning::MatchOperation(::n2h((uint32_t) op));
 209 }
 210
 211
 212 }       // CodeSigning
 213 }       // Security
 214
 215 #endif //_H_REQUIREMENT