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1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef SANDBOX_SRC_POLICY_ENGINE_PARAMS_H__ | |
6 #define SANDBOX_SRC_POLICY_ENGINE_PARAMS_H__ | |
7 | |
8 #include "base/basictypes.h" | |
9 #include "sandbox/src/internal_types.h" | |
10 #include "sandbox/src/nt_internals.h" | |
11 #include "sandbox/src/sandbox_nt_util.h" | |
12 | |
13 // This header defines the classes that allow the low level policy to select | |
14 // the input parameters. In order to better make sense of this header is | |
15 // recommended that you check policy_engine_opcodes.h first. | |
16 | |
17 namespace sandbox { | |
18 | |
19 // Models the set of interesting parameters of an intercepted system call | |
20 // normally you don't create objects of this class directly, instead you | |
21 // use the POLPARAMS_XXX macros. | |
22 // For example, if an intercepted function has the following signature: | |
23 // | |
24 // NTSTATUS NtOpenFileFunction (PHANDLE FileHandle, | |
25 // ACCESS_MASK DesiredAccess, | |
26 // POBJECT_ATTRIBUTES ObjectAttributes, | |
27 // PIO_STATUS_BLOCK IoStatusBlock, | |
28 // ULONG ShareAccess, | |
29 // ULONG OpenOptions); | |
30 // | |
31 // You could say that the following parameters are of interest to policy: | |
32 // | |
33 // POLPARAMS_BEGIN(open_params) | |
34 // POLPARAM(DESIRED_ACCESS) | |
35 // POLPARAM(OBJECT_NAME) | |
36 // POLPARAM(SECURITY_DESCRIPTOR) | |
37 // POLPARAM(IO_STATUS) | |
38 // POLPARAM(OPEN_OPTIONS) | |
39 // POLPARAMS_END; | |
40 // | |
41 // and the actual code will use this for defining the parameters: | |
42 // | |
43 // CountedParameterSet<open_params> p; | |
44 // p[open_params::DESIRED_ACCESS] = ParamPickerMake(DesiredAccess); | |
45 // p[open_params::OBJECT_NAME] = | |
46 // ParamPickerMake(ObjectAttributes->ObjectName); | |
47 // p[open_params::SECURITY_DESCRIPTOR] = | |
48 // ParamPickerMake(ObjectAttributes->SecurityDescriptor); | |
49 // p[open_params::IO_STATUS] = ParamPickerMake(IoStatusBlock); | |
50 // p[open_params::OPEN_OPTIONS] = ParamPickerMake(OpenOptions); | |
51 // | |
52 // These will create an stack-allocated array of ParameterSet objects which | |
53 // have each 1) the address of the parameter 2) a numeric id that encodes the | |
54 // original C++ type. This allows the policy to treat any set of supported | |
55 // argument types uniformily and with some type safety. | |
56 // | |
57 // TODO(cpu): support not fully implemented yet for unicode string and will | |
58 // probably add other types as well. | |
59 class ParameterSet { | |
60 public: | |
61 ParameterSet() : real_type_(INVALID_TYPE), address_(NULL) {} | |
62 | |
63 // Retrieve the stored parameter. If the type does not match ulong fail. | |
64 bool Get(unsigned long* destination) const { | |
65 if (ULONG_TYPE != real_type_) { | |
66 return false; | |
67 } | |
68 *destination = Void2TypePointerCopy<unsigned long>(); | |
69 return true; | |
70 } | |
71 | |
72 // Retrieve the stored parameter. If the type does not match void* fail. | |
73 bool Get(const void** destination) const { | |
74 if (VOIDPTR_TYPE != real_type_) { | |
75 return false; | |
76 } | |
77 *destination = Void2TypePointerCopy<void*>(); | |
78 return true; | |
79 } | |
80 | |
81 // Retrieve the stored parameter. If the type does not match wchar_t* fail. | |
82 bool Get(const wchar_t** destination) const { | |
83 if (WCHAR_TYPE != real_type_) { | |
84 return false; | |
85 } | |
86 *destination = Void2TypePointerCopy<const wchar_t*>(); | |
87 return true; | |
88 } | |
89 | |
90 // False if the parameter is not properly initialized. | |
91 bool IsValid() const { | |
92 return INVALID_TYPE != real_type_; | |
93 } | |
94 | |
95 protected: | |
96 // The constructor can only be called by derived types, which should | |
97 // safely provide the real_type and the address of the argument. | |
98 ParameterSet(ArgType real_type, const void* address) | |
99 : real_type_(real_type), address_(address) { | |
100 } | |
101 | |
102 private: | |
103 // This template provides the same functionality as bits_cast but | |
104 // it works with pointer while the former works only with references. | |
105 template <typename T> | |
106 T Void2TypePointerCopy() const { | |
107 return *(reinterpret_cast<const T*>(address_)); | |
108 } | |
109 | |
110 ArgType real_type_; | |
111 const void* address_; | |
112 }; | |
113 | |
114 // To safely infer the type, we use a set of template specializations | |
115 // in ParameterSetEx with a template function ParamPickerMake to do the | |
116 // parameter type deduction. | |
117 | |
118 // Base template class. Not implemented so using unsupported types should | |
119 // fail to compile. | |
120 template <typename T> | |
121 class ParameterSetEx : public ParameterSet { | |
122 public: | |
123 ParameterSetEx(const void* address); | |
124 }; | |
125 | |
126 template<> | |
127 class ParameterSetEx<void const*> : public ParameterSet { | |
128 public: | |
129 ParameterSetEx(const void* address) | |
130 : ParameterSet(VOIDPTR_TYPE, address) {} | |
131 }; | |
132 | |
133 template<> | |
134 class ParameterSetEx<void*> : public ParameterSet { | |
135 public: | |
136 ParameterSetEx(const void* address) | |
137 : ParameterSet(VOIDPTR_TYPE, address) {} | |
138 }; | |
139 | |
140 | |
141 template<> | |
142 class ParameterSetEx<wchar_t*> : public ParameterSet { | |
143 public: | |
144 ParameterSetEx(const void* address) | |
145 : ParameterSet(WCHAR_TYPE, address) {} | |
146 }; | |
147 | |
148 template<> | |
149 class ParameterSetEx<wchar_t const*> : public ParameterSet { | |
150 public: | |
151 ParameterSetEx(const void* address) | |
152 : ParameterSet(WCHAR_TYPE, address) {} | |
153 }; | |
154 | |
155 | |
156 template<> | |
157 class ParameterSetEx<unsigned long> : public ParameterSet { | |
158 public: | |
159 ParameterSetEx(const void* address) | |
160 : ParameterSet(ULONG_TYPE, address) {} | |
161 }; | |
162 | |
163 template<> | |
164 class ParameterSetEx<UNICODE_STRING> : public ParameterSet { | |
165 public: | |
166 ParameterSetEx(const void* address) | |
167 : ParameterSet(UNISTR_TYPE, address) {} | |
168 }; | |
169 | |
170 template <typename T> | |
171 ParameterSet ParamPickerMake(T& parameter) { | |
172 return ParameterSetEx<T>(¶meter); | |
173 }; | |
174 | |
175 struct CountedParameterSetBase { | |
176 int count; | |
177 ParameterSet parameters[1]; | |
178 }; | |
179 | |
180 // This template defines the actual list of policy parameters for a given | |
181 // interception. | |
182 // Warning: This template stores the address to the actual variables, in | |
183 // other words, the values are not copied. | |
184 template <typename T> | |
185 struct CountedParameterSet { | |
186 CountedParameterSet() : count(T::PolParamLast) {} | |
187 | |
188 ParameterSet& operator[](typename T::Args n) { | |
189 return parameters[n]; | |
190 } | |
191 | |
192 CountedParameterSetBase* GetBase() { | |
193 return reinterpret_cast<CountedParameterSetBase*>(this); | |
194 } | |
195 | |
196 int count; | |
197 ParameterSet parameters[T::PolParamLast]; | |
198 }; | |
199 | |
200 } // namespace sandbox | |
201 | |
202 #endif // SANDBOX_SRC_POLICY_ENGINE_PARAMS_H__ | |
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