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