| 1 | //===-- ubsan_type_hash.h ---------------------------------------*- C++ -*-===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // Hashing of types for Clang's undefined behavior checker. |
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| 10 | // |
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| 11 | //===----------------------------------------------------------------------===// |
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| 12 | #ifndef UBSAN_TYPE_HASH_H |
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| 13 | #define UBSAN_TYPE_HASH_H |
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| 14 | |
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| 15 | #include "sanitizer_common/sanitizer_common.h" |
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| 16 | |
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| 17 | namespace __ubsan { |
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| 18 | |
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| 19 | typedef uptr HashValue; |
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| 20 | |
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| 21 | /// \brief Information about the dynamic type of an object (extracted from its |
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| 22 | /// vptr). |
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| 23 | class DynamicTypeInfo { |
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| 24 | const char *MostDerivedTypeName; |
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| 25 | sptr Offset; |
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| 26 | const char *SubobjectTypeName; |
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| 27 | |
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| 28 | public: |
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| 29 | DynamicTypeInfo(const char *MDTN, sptr Offset, const char *STN) |
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| 30 | : MostDerivedTypeName(MDTN), Offset(Offset), SubobjectTypeName(STN) {} |
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| 31 | |
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| 32 | /// Determine whether the object had a valid dynamic type. |
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| 33 | bool isValid() const { return MostDerivedTypeName; } |
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| 34 | /// Get the name of the most-derived type of the object. |
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| 35 | const char *getMostDerivedTypeName() const { return MostDerivedTypeName; } |
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| 36 | /// Get the offset from the most-derived type to this base class. |
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| 37 | sptr getOffset() const { return Offset; } |
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| 38 | /// Get the name of the most-derived type at the specified offset. |
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| 39 | const char *getSubobjectTypeName() const { return SubobjectTypeName; } |
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| 40 | }; |
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| 41 | |
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| 42 | /// \brief Get information about the dynamic type of an object. |
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| 43 | DynamicTypeInfo getDynamicTypeInfoFromObject(void *Object); |
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| 44 | |
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| 45 | /// \brief Get information about the dynamic type of an object from its vtable. |
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| 46 | DynamicTypeInfo getDynamicTypeInfoFromVtable(void *Vtable); |
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| 47 | |
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| 48 | /// \brief Check whether the dynamic type of \p Object has a \p Type subobject |
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| 49 | /// at offset 0. |
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| 50 | /// \return \c true if the type matches, \c false if not. |
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| 51 | bool checkDynamicType(void *Object, void *Type, HashValue Hash); |
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| 52 | |
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| 53 | const unsigned VptrTypeCacheSize = 128; |
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| 54 | |
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| 55 | /// A sanity check for Vtable. Offsets to top must be reasonably small |
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| 56 | /// numbers (by absolute value). It's a weak check for Vtable corruption. |
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| 57 | const int VptrMaxOffsetToTop = 1<<20; |
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| 58 | |
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| 59 | /// \brief A cache of the results of checkDynamicType. \c checkDynamicType would |
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| 60 | /// return \c true (modulo hash collisions) if |
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| 61 | /// \code |
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| 62 | /// __ubsan_vptr_type_cache[Hash % VptrTypeCacheSize] == Hash |
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| 63 | /// \endcode |
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| 64 | extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
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| 65 | HashValue __ubsan_vptr_type_cache[VptrTypeCacheSize]; |
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| 66 | |
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| 67 | /// \brief Do whatever is required by the ABI to check for std::type_info |
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| 68 | /// equivalence beyond simple pointer comparison. |
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| 69 | bool checkTypeInfoEquality(const void *TypeInfo1, const void *TypeInfo2); |
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| 70 | |
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| 71 | } // namespace __ubsan |
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| 72 | |
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| 73 | #endif // UBSAN_TYPE_HASH_H |
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| 74 | |
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