OSX/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
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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_utilities/debugging_internal.h>
  34 #include <Security/CodeSigning.h>
  35 #include "codedirectory.h"
  36 #include <map>
  37
  38 namespace Security {
  39 namespace CodeSigning {
  40
  41
  42 //
  43 // Single requirement.
  44 // This is a contiguous binary blob, starting with this header
  45 // and followed by binary expr-code. All links within the blob
  46 // are offset-relative to the start of the header.
  47 // This is designed to be a binary stable format. Note that we restrict
  48 // outselves to 4GB maximum size (4 byte size/offset), and we expect real
  49 // Requirement blobs to be fairly small (a few kilobytes at most).
  50 //
  51 // The "kind" field allows for adding different kinds of Requirements altogether
  52 // in the future. We expect to stay within the framework of "opExpr" requirements,
  53 // but it never hurts to have a way out.
  54 //
  55 class Requirement: public Blob<Requirement, 0xfade0c00> {
  56 public:
  57         class Maker;                            // makes Requirement blobs
  58         class Context;                          // evaluation context
  59         class Reader;                           // structured reader
  60         class Interpreter;                      // evaluation engine
  61
  62         // different forms of Requirements. Right now, we only support exprForm ("opExprs")
  63         enum Kind {
  64                 exprForm = 1                    // prefix expr form
  65         };
  66
  67         void kind(Kind k) { mKind = k; }
  68         Kind kind() const { return Kind(uint32_t(mKind)); }
  69
  70         // validate this requirement against a code context
  71         void validate(const Context &ctx, OSStatus failure = errSecCSReqFailed) const;  // throws on all failures
  72         bool validates(const Context &ctx, OSStatus failure = errSecCSReqFailed) const; // returns on clean miss
  73
  74         // certificate positions (within a standard certificate chain)
  75         static const int leafCert = 0;          // index for leaf (first in chain)
  76         static const int anchorCert = -1;       // index for anchor (last in chain)
  77
  78 #if defined(TEST_APPLE_ANCHOR)
  79         static const char testAppleAnchorEnv[];
  80         static const SHA1::Digest &testAppleAnchorHash();
  81 #endif //TEST_APPLE_ANCHOR
  82
  83         // common alignment rule for all requirement forms
  84         static const size_t baseAlignment = sizeof(uint32_t); // (we might as well say "four")
  85
  86     // canonical (source) names of Requirement types (matched to SecRequirementType in CSCommon.h)
  87     static const char *const typeNames[];
  88 #if TARGET_OS_OSX
  89         IFDUMP(void dump() const);
  90 #endif
  91
  92 private:
  93         Endian<uint32_t> mKind;                 // expression kind
  94 };
  95
  96
  97 //
  98 // An interpretation context
  99 //
 100 class Requirement::Context {
 101 protected:
 102         Context()
 103                 : certs(NULL), info(NULL), entitlements(NULL), identifier(""), directory(NULL) { }
 104
 105 public:
 106         Context(CFArrayRef certChain, CFDictionaryRef infoDict, CFDictionaryRef entitlementDict,
 107                         const std::string &ident, const CodeDirectory *dir)
 108                 : certs(certChain), info(infoDict), entitlements(entitlementDict), identifier(ident), directory(dir) { }
 109
 110         CFArrayRef certs;                                                               // certificate chain
 111         CFDictionaryRef info;                                                   // Info.plist
 112         CFDictionaryRef entitlements;                                   // entitlement plist
 113         std::string identifier;                                         // signing identifier
 114         const CodeDirectory *directory;                         // CodeDirectory
 115
 116         SecCertificateRef cert(int ix) const;                   // get a cert from the cert chain (NULL if not found)
 117         unsigned int certCount() const;                         // length of cert chain (including root)
 118 };
 119
 120
 121 //
 122 // exprForm opcodes.
 123 //
 124 // Opcodes are broken into flags in the (HBO) high byte, and an opcode value
 125 // in the remaining 24 bits. Note that opcodes will remain fairly small
 126 // (almost certainly <60000), so we have the third byte to play around with
 127 // in the future, if needed. For now, small opcodes effective reserve this byte
 128 // as zero.
 129 // The flag byte allows for limited understanding of unknown opcodes. It allows
 130 // the interpreter to use the known opcode parts of the program while semi-creatively
 131 // disregarding the parts it doesn't know about. An unrecognized opcode with zero
 132 // flag byte causes evaluation to categorically fail, since the semantics of such
 133 // an opcode cannot safely be predicted.
 134 //
 135 enum {
 136         // semantic bits or'ed into the opcode
 137         opFlagMask =     0xFF000000,    // high bit flags
 138         opGenericFalse = 0x80000000,    // has size field; okay to default to false
 139         opGenericSkip =  0x40000000,    // has size field; skip and continue
 140 };
 141
 142 enum ExprOp {
 143         opFalse,                                                // unconditionally false
 144         opTrue,                                                 // unconditionally true
 145         opIdent,                                                // match canonical code [string]
 146         opAppleAnchor,                                  // signed by Apple as Apple's product
 147         opAnchorHash,                                   // match anchor [cert hash]
 148         opInfoKeyValue,                                 // *legacy* - use opInfoKeyField [key; value]
 149         opAnd,                                                  // binary prefix expr AND expr [expr; expr]
 150         opOr,                                                   // binary prefix expr OR expr [expr; expr]
 151         opCDHash,                                               // match hash of CodeDirectory directly [cd hash]
 152         opNot,                                                  // logical inverse [expr]
 153         opInfoKeyField,                                 // Info.plist key field [string; match suffix]
 154         opCertField,                                    // Certificate field [cert index; field name; match suffix]
 155         opTrustedCert,                                  // require trust settings to approve one particular cert [cert index]
 156         opTrustedCerts,                                 // require trust settings to approve the cert chain
 157         opCertGeneric,                                  // Certificate component by OID [cert index; oid; match suffix]
 158         opAppleGenericAnchor,                   // signed by Apple in any capacity
 159         opEntitlementField,                             // entitlement dictionary field [string; match suffix]
 160         opCertPolicy,                                   // Certificate policy by OID [cert index; oid; match suffix]
 161         opNamedAnchor,                                  // named anchor type
 162         opNamedCode,                                    // named subroutine
 163         opPlatform,                                             // platform constraint [integer]
 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