Security-57031.1.35.tar.gz

[apple/security.git] / Security / libsecurity_cdsa_utilities / lib / acl_threshold.h

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+/*
+ * Copyright (c) 2000-2004,2006,2011,2014 Apple Inc. All Rights Reserved.
+ * 
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+
+//
+// acl_threshold - Threshold-based group ACL subjects.
+//
+// This subject type implements threshold (k of n) subjects as per CSSM standard.
+// Subsubjects are stored and evaluated in the order received. Any subsubject
+// is presented with all subsamples of the corresponding threshold sample, but
+// not any other samples possibly present in the credentials. Subsubject evaluation
+// stops as soon as the threshold is satisfied, or as soon as it becomes numerically
+// impossible to satisfy the threshold with future matches.
+// Note that this subject will reject out of hand any threshold sample that
+// contains more than <n> subsamples. This defeats "sample stuffing" attacks
+// where the attacker provides thousands of samples in the hope that some may
+// match by accident. It will however accept threshold samples with fewer than
+// <n> subsamples, as long as there are at least <k> subsamples.
+//
+#ifndef _ACL_THRESHOLD
+#define _ACL_THRESHOLD
+
+#include <security_cdsa_utilities/cssmacl.h>
+#include <vector>
+
+
+namespace Security {
+
+class ThresholdAclSubject : public SimpleAclSubject {
+    typedef ObjectAcl::AclSubjectPointer AclSubjectPointer;
+    typedef vector<AclSubjectPointer> AclSubjectVector;
+public:
+    bool validate(const AclValidationContext &baseCtx, const TypedList &sample) const;
+    CssmList toList(Allocator &alloc) const;
+    
+    ThresholdAclSubject(uint32 n, uint32 k, const AclSubjectVector &subSubjects);
+    
+    void exportBlob(Writer::Counter &pub, Writer::Counter &priv);
+    void exportBlob(Writer &pub, Writer &priv);
+       
+       unsigned count() const { return totalSubjects; }
+       AclSubject *subject(unsigned n) const { return elements[n]; }
+       void add(AclSubject *subject, unsigned beforePosition);
+       
+       IFDUMP(void debugDump() const);
+    
+    class Maker : public AclSubject::Maker {
+    public:
+       Maker() : AclSubject::Maker(CSSM_ACL_SUBJECT_TYPE_THRESHOLD) { }
+       ThresholdAclSubject *make(const TypedList &list) const;
+       ThresholdAclSubject *make(Version, Reader &pub, Reader &priv) const;
+    };
+    
+private:
+    uint32 minimumNeeded;                              // number of matches needed
+    uint32 totalSubjects;                              // number of subSubjects
+    AclSubjectVector elements;                 // sub-subject vector
+
+    template <class Action>
+    void exportBlobForm(Action &pub, Action &priv);
+};
+
+} // namespace Security
+
+
+#endif //_ACL_THRESHOLD