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Diffstat (limited to 'security/sandbox/chromium/base/numerics')
4 files changed, 1273 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/numerics/safe_conversions.h b/security/sandbox/chromium/base/numerics/safe_conversions.h new file mode 100644 index 000000000..baac188fd --- /dev/null +++ b/security/sandbox/chromium/base/numerics/safe_conversions.h @@ -0,0 +1,165 @@ +// Copyright 2014 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef BASE_NUMERICS_SAFE_CONVERSIONS_H_ +#define BASE_NUMERICS_SAFE_CONVERSIONS_H_ + +#include <stddef.h> + +#include <limits> +#include <type_traits> + +#include "base/logging.h" +#include "base/numerics/safe_conversions_impl.h" + +namespace base { + +// Convenience function that returns true if the supplied value is in range +// for the destination type. +template <typename Dst, typename Src> +inline bool IsValueInRangeForNumericType(Src value) { + return internal::DstRangeRelationToSrcRange<Dst>(value) == + internal::RANGE_VALID; +} + +// Convenience function for determining if a numeric value is negative without +// throwing compiler warnings on: unsigned(value) < 0. +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_signed, bool>::type +IsValueNegative(T value) { + static_assert(std::numeric_limits<T>::is_specialized, + "Argument must be numeric."); + return value < 0; +} + +template <typename T> +typename std::enable_if<!std::numeric_limits<T>::is_signed, bool>::type + IsValueNegative(T) { + static_assert(std::numeric_limits<T>::is_specialized, + "Argument must be numeric."); + return false; +} + +// checked_cast<> is analogous to static_cast<> for numeric types, +// except that it CHECKs that the specified numeric conversion will not +// overflow or underflow. NaN source will always trigger a CHECK. +template <typename Dst, typename Src> +inline Dst checked_cast(Src value) { + CHECK(IsValueInRangeForNumericType<Dst>(value)); + return static_cast<Dst>(value); +} + +// HandleNaN will cause this class to CHECK(false). +struct SaturatedCastNaNBehaviorCheck { + template <typename T> + static T HandleNaN() { + CHECK(false); + return T(); + } +}; + +// HandleNaN will return 0 in this case. +struct SaturatedCastNaNBehaviorReturnZero { + template <typename T> + static T HandleNaN() { + return T(); + } +}; + +// saturated_cast<> is analogous to static_cast<> for numeric types, except +// that the specified numeric conversion will saturate rather than overflow or +// underflow. NaN assignment to an integral will defer the behavior to a +// specified class. By default, it will return 0. +template <typename Dst, + class NaNHandler = SaturatedCastNaNBehaviorReturnZero, + typename Src> +inline Dst saturated_cast(Src value) { + // Optimization for floating point values, which already saturate. + if (std::numeric_limits<Dst>::is_iec559) + return static_cast<Dst>(value); + + switch (internal::DstRangeRelationToSrcRange<Dst>(value)) { + case internal::RANGE_VALID: + return static_cast<Dst>(value); + + case internal::RANGE_UNDERFLOW: + return std::numeric_limits<Dst>::min(); + + case internal::RANGE_OVERFLOW: + return std::numeric_limits<Dst>::max(); + + // Should fail only on attempting to assign NaN to a saturated integer. + case internal::RANGE_INVALID: + return NaNHandler::template HandleNaN<Dst>(); + } + + NOTREACHED(); + return static_cast<Dst>(value); +} + +// strict_cast<> is analogous to static_cast<> for numeric types, except that +// it will cause a compile failure if the destination type is not large enough +// to contain any value in the source type. It performs no runtime checking. +template <typename Dst, typename Src> +inline Dst strict_cast(Src value) { + static_assert(std::numeric_limits<Src>::is_specialized, + "Argument must be numeric."); + static_assert(std::numeric_limits<Dst>::is_specialized, + "Result must be numeric."); + static_assert((internal::StaticDstRangeRelationToSrcRange<Dst, Src>::value == + internal::NUMERIC_RANGE_CONTAINED), + "The numeric conversion is out of range for this type. You " + "should probably use one of the following conversion " + "mechanisms on the value you want to pass:\n" + "- base::checked_cast\n" + "- base::saturated_cast\n" + "- base::CheckedNumeric"); + + return static_cast<Dst>(value); +} + +// StrictNumeric implements compile time range checking between numeric types by +// wrapping assignment operations in a strict_cast. This class is intended to be +// used for function arguments and return types, to ensure the destination type +// can always contain the source type. This is essentially the same as enforcing +// -Wconversion in gcc and C4302 warnings on MSVC, but it can be applied +// incrementally at API boundaries, making it easier to convert code so that it +// compiles cleanly with truncation warnings enabled. +// This template should introduce no runtime overhead, but it also provides no +// runtime checking of any of the associated mathematical operations. Use +// CheckedNumeric for runtime range checks of tha actual value being assigned. +template <typename T> +class StrictNumeric { + public: + typedef T type; + + StrictNumeric() : value_(0) {} + + // Copy constructor. + template <typename Src> + StrictNumeric(const StrictNumeric<Src>& rhs) + : value_(strict_cast<T>(rhs.value_)) {} + + // This is not an explicit constructor because we implicitly upgrade regular + // numerics to StrictNumerics to make them easier to use. + template <typename Src> + StrictNumeric(Src value) + : value_(strict_cast<T>(value)) {} + + // The numeric cast operator basically handles all the magic. + template <typename Dst> + operator Dst() const { + return strict_cast<Dst>(value_); + } + + private: + T value_; +}; + +// Explicitly make a shorter size_t typedef for convenience. +typedef StrictNumeric<size_t> SizeT; + +} // namespace base + +#endif // BASE_NUMERICS_SAFE_CONVERSIONS_H_ diff --git a/security/sandbox/chromium/base/numerics/safe_conversions_impl.h b/security/sandbox/chromium/base/numerics/safe_conversions_impl.h new file mode 100644 index 000000000..02e68e25d --- /dev/null +++ b/security/sandbox/chromium/base/numerics/safe_conversions_impl.h @@ -0,0 +1,264 @@ +// Copyright 2014 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_ +#define BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_ + +#include <limits.h> +#include <stdint.h> + +#include <limits> + +#include "base/template_util.h" + +namespace base { +namespace internal { + +// The std library doesn't provide a binary max_exponent for integers, however +// we can compute one by adding one to the number of non-sign bits. This allows +// for accurate range comparisons between floating point and integer types. +template <typename NumericType> +struct MaxExponent { + static const int value = std::numeric_limits<NumericType>::is_iec559 + ? std::numeric_limits<NumericType>::max_exponent + : (sizeof(NumericType) * 8 + 1 - + std::numeric_limits<NumericType>::is_signed); +}; + +enum IntegerRepresentation { + INTEGER_REPRESENTATION_UNSIGNED, + INTEGER_REPRESENTATION_SIGNED +}; + +// A range for a given nunmeric Src type is contained for a given numeric Dst +// type if both numeric_limits<Src>::max() <= numeric_limits<Dst>::max() and +// numeric_limits<Src>::min() >= numeric_limits<Dst>::min() are true. +// We implement this as template specializations rather than simple static +// comparisons to ensure type correctness in our comparisons. +enum NumericRangeRepresentation { + NUMERIC_RANGE_NOT_CONTAINED, + NUMERIC_RANGE_CONTAINED +}; + +// Helper templates to statically determine if our destination type can contain +// maximum and minimum values represented by the source type. + +template < + typename Dst, + typename Src, + IntegerRepresentation DstSign = std::numeric_limits<Dst>::is_signed + ? INTEGER_REPRESENTATION_SIGNED + : INTEGER_REPRESENTATION_UNSIGNED, + IntegerRepresentation SrcSign = + std::numeric_limits<Src>::is_signed + ? INTEGER_REPRESENTATION_SIGNED + : INTEGER_REPRESENTATION_UNSIGNED > +struct StaticDstRangeRelationToSrcRange; + +// Same sign: Dst is guaranteed to contain Src only if its range is equal or +// larger. +template <typename Dst, typename Src, IntegerRepresentation Sign> +struct StaticDstRangeRelationToSrcRange<Dst, Src, Sign, Sign> { + static const NumericRangeRepresentation value = + MaxExponent<Dst>::value >= MaxExponent<Src>::value + ? NUMERIC_RANGE_CONTAINED + : NUMERIC_RANGE_NOT_CONTAINED; +}; + +// Unsigned to signed: Dst is guaranteed to contain source only if its range is +// larger. +template <typename Dst, typename Src> +struct StaticDstRangeRelationToSrcRange<Dst, + Src, + INTEGER_REPRESENTATION_SIGNED, + INTEGER_REPRESENTATION_UNSIGNED> { + static const NumericRangeRepresentation value = + MaxExponent<Dst>::value > MaxExponent<Src>::value + ? NUMERIC_RANGE_CONTAINED + : NUMERIC_RANGE_NOT_CONTAINED; +}; + +// Signed to unsigned: Dst cannot be statically determined to contain Src. +template <typename Dst, typename Src> +struct StaticDstRangeRelationToSrcRange<Dst, + Src, + INTEGER_REPRESENTATION_UNSIGNED, + INTEGER_REPRESENTATION_SIGNED> { + static const NumericRangeRepresentation value = NUMERIC_RANGE_NOT_CONTAINED; +}; + +enum RangeConstraint { + RANGE_VALID = 0x0, // Value can be represented by the destination type. + RANGE_UNDERFLOW = 0x1, // Value would overflow. + RANGE_OVERFLOW = 0x2, // Value would underflow. + RANGE_INVALID = RANGE_UNDERFLOW | RANGE_OVERFLOW // Invalid (i.e. NaN). +}; + +// Helper function for coercing an int back to a RangeContraint. +inline RangeConstraint GetRangeConstraint(int integer_range_constraint) { + DCHECK(integer_range_constraint >= RANGE_VALID && + integer_range_constraint <= RANGE_INVALID); + return static_cast<RangeConstraint>(integer_range_constraint); +} + +// This function creates a RangeConstraint from an upper and lower bound +// check by taking advantage of the fact that only NaN can be out of range in +// both directions at once. +inline RangeConstraint GetRangeConstraint(bool is_in_upper_bound, + bool is_in_lower_bound) { + return GetRangeConstraint((is_in_upper_bound ? 0 : RANGE_OVERFLOW) | + (is_in_lower_bound ? 0 : RANGE_UNDERFLOW)); +} + +// The following helper template addresses a corner case in range checks for +// conversion from a floating-point type to an integral type of smaller range +// but larger precision (e.g. float -> unsigned). The problem is as follows: +// 1. Integral maximum is always one less than a power of two, so it must be +// truncated to fit the mantissa of the floating point. The direction of +// rounding is implementation defined, but by default it's always IEEE +// floats, which round to nearest and thus result in a value of larger +// magnitude than the integral value. +// Example: float f = UINT_MAX; // f is 4294967296f but UINT_MAX +// // is 4294967295u. +// 2. If the floating point value is equal to the promoted integral maximum +// value, a range check will erroneously pass. +// Example: (4294967296f <= 4294967295u) // This is true due to a precision +// // loss in rounding up to float. +// 3. When the floating point value is then converted to an integral, the +// resulting value is out of range for the target integral type and +// thus is implementation defined. +// Example: unsigned u = (float)INT_MAX; // u will typically overflow to 0. +// To fix this bug we manually truncate the maximum value when the destination +// type is an integral of larger precision than the source floating-point type, +// such that the resulting maximum is represented exactly as a floating point. +template <typename Dst, typename Src> +struct NarrowingRange { + typedef typename std::numeric_limits<Src> SrcLimits; + typedef typename std::numeric_limits<Dst> DstLimits; + + static Dst max() { + // The following logic avoids warnings where the max function is + // instantiated with invalid values for a bit shift (even though + // such a function can never be called). + static const int shift = + (MaxExponent<Src>::value > MaxExponent<Dst>::value && + SrcLimits::digits < DstLimits::digits && SrcLimits::is_iec559 && + DstLimits::is_integer) + ? (DstLimits::digits - SrcLimits::digits) + : 0; + + // We use UINTMAX_C below to avoid compiler warnings about shifting floating + // points. Since it's a compile time calculation, it shouldn't have any + // performance impact. + return DstLimits::max() - static_cast<Dst>((UINTMAX_C(1) << shift) - 1); + } + + static Dst min() { + return std::numeric_limits<Dst>::is_iec559 ? -DstLimits::max() + : DstLimits::min(); + } +}; + +template < + typename Dst, + typename Src, + IntegerRepresentation DstSign = std::numeric_limits<Dst>::is_signed + ? INTEGER_REPRESENTATION_SIGNED + : INTEGER_REPRESENTATION_UNSIGNED, + IntegerRepresentation SrcSign = std::numeric_limits<Src>::is_signed + ? INTEGER_REPRESENTATION_SIGNED + : INTEGER_REPRESENTATION_UNSIGNED, + NumericRangeRepresentation DstRange = + StaticDstRangeRelationToSrcRange<Dst, Src>::value > +struct DstRangeRelationToSrcRangeImpl; + +// The following templates are for ranges that must be verified at runtime. We +// split it into checks based on signedness to avoid confusing casts and +// compiler warnings on signed an unsigned comparisons. + +// Dst range is statically determined to contain Src: Nothing to check. +template <typename Dst, + typename Src, + IntegerRepresentation DstSign, + IntegerRepresentation SrcSign> +struct DstRangeRelationToSrcRangeImpl<Dst, + Src, + DstSign, + SrcSign, + NUMERIC_RANGE_CONTAINED> { + static RangeConstraint Check(Src value) { return RANGE_VALID; } +}; + +// Signed to signed narrowing: Both the upper and lower boundaries may be +// exceeded. +template <typename Dst, typename Src> +struct DstRangeRelationToSrcRangeImpl<Dst, + Src, + INTEGER_REPRESENTATION_SIGNED, + INTEGER_REPRESENTATION_SIGNED, + NUMERIC_RANGE_NOT_CONTAINED> { + static RangeConstraint Check(Src value) { + return GetRangeConstraint((value <= NarrowingRange<Dst, Src>::max()), + (value >= NarrowingRange<Dst, Src>::min())); + } +}; + +// Unsigned to unsigned narrowing: Only the upper boundary can be exceeded. +template <typename Dst, typename Src> +struct DstRangeRelationToSrcRangeImpl<Dst, + Src, + INTEGER_REPRESENTATION_UNSIGNED, + INTEGER_REPRESENTATION_UNSIGNED, + NUMERIC_RANGE_NOT_CONTAINED> { + static RangeConstraint Check(Src value) { + return GetRangeConstraint(value <= NarrowingRange<Dst, Src>::max(), true); + } +}; + +// Unsigned to signed: The upper boundary may be exceeded. +template <typename Dst, typename Src> +struct DstRangeRelationToSrcRangeImpl<Dst, + Src, + INTEGER_REPRESENTATION_SIGNED, + INTEGER_REPRESENTATION_UNSIGNED, + NUMERIC_RANGE_NOT_CONTAINED> { + static RangeConstraint Check(Src value) { + return sizeof(Dst) > sizeof(Src) + ? RANGE_VALID + : GetRangeConstraint( + value <= static_cast<Src>(NarrowingRange<Dst, Src>::max()), + true); + } +}; + +// Signed to unsigned: The upper boundary may be exceeded for a narrower Dst, +// and any negative value exceeds the lower boundary. +template <typename Dst, typename Src> +struct DstRangeRelationToSrcRangeImpl<Dst, + Src, + INTEGER_REPRESENTATION_UNSIGNED, + INTEGER_REPRESENTATION_SIGNED, + NUMERIC_RANGE_NOT_CONTAINED> { + static RangeConstraint Check(Src value) { + return (MaxExponent<Dst>::value >= MaxExponent<Src>::value) + ? GetRangeConstraint(true, value >= static_cast<Src>(0)) + : GetRangeConstraint( + value <= static_cast<Src>(NarrowingRange<Dst, Src>::max()), + value >= static_cast<Src>(0)); + } +}; + +template <typename Dst, typename Src> +inline RangeConstraint DstRangeRelationToSrcRange(Src value) { + static_assert(std::numeric_limits<Src>::is_specialized, + "Argument must be numeric."); + static_assert(std::numeric_limits<Dst>::is_specialized, + "Result must be numeric."); + return DstRangeRelationToSrcRangeImpl<Dst, Src>::Check(value); +} + +} // namespace internal +} // namespace base + +#endif // BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_ diff --git a/security/sandbox/chromium/base/numerics/safe_math.h b/security/sandbox/chromium/base/numerics/safe_math.h new file mode 100644 index 000000000..d169690a8 --- /dev/null +++ b/security/sandbox/chromium/base/numerics/safe_math.h @@ -0,0 +1,299 @@ +// Copyright 2014 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef BASE_NUMERICS_SAFE_MATH_H_ +#define BASE_NUMERICS_SAFE_MATH_H_ + +#include <stddef.h> + +#include "base/numerics/safe_math_impl.h" + +namespace base { + +namespace internal { + +// CheckedNumeric implements all the logic and operators for detecting integer +// boundary conditions such as overflow, underflow, and invalid conversions. +// The CheckedNumeric type implicitly converts from floating point and integer +// data types, and contains overloads for basic arithmetic operations (i.e.: +, +// -, *, /, %). +// +// The following methods convert from CheckedNumeric to standard numeric values: +// IsValid() - Returns true if the underlying numeric value is valid (i.e. has +// has not wrapped and is not the result of an invalid conversion). +// ValueOrDie() - Returns the underlying value. If the state is not valid this +// call will crash on a CHECK. +// ValueOrDefault() - Returns the current value, or the supplied default if the +// state is not valid. +// ValueFloating() - Returns the underlying floating point value (valid only +// only for floating point CheckedNumeric types). +// +// Bitwise operations are explicitly not supported, because correct +// handling of some cases (e.g. sign manipulation) is ambiguous. Comparison +// operations are explicitly not supported because they could result in a crash +// on a CHECK condition. You should use patterns like the following for these +// operations: +// Bitwise operation: +// CheckedNumeric<int> checked_int = untrusted_input_value; +// int x = checked_int.ValueOrDefault(0) | kFlagValues; +// Comparison: +// CheckedNumeric<size_t> checked_size = untrusted_input_value; +// checked_size += HEADER LENGTH; +// if (checked_size.IsValid() && checked_size.ValueOrDie() < buffer_size) +// Do stuff... +template <typename T> +class CheckedNumeric { + public: + typedef T type; + + CheckedNumeric() {} + + // Copy constructor. + template <typename Src> + CheckedNumeric(const CheckedNumeric<Src>& rhs) + : state_(rhs.ValueUnsafe(), rhs.validity()) {} + + template <typename Src> + CheckedNumeric(Src value, RangeConstraint validity) + : state_(value, validity) {} + + // This is not an explicit constructor because we implicitly upgrade regular + // numerics to CheckedNumerics to make them easier to use. + template <typename Src> + CheckedNumeric(Src value) + : state_(value) { + static_assert(std::numeric_limits<Src>::is_specialized, + "Argument must be numeric."); + } + + // This is not an explicit constructor because we want a seamless conversion + // from StrictNumeric types. + template <typename Src> + CheckedNumeric(StrictNumeric<Src> value) + : state_(static_cast<Src>(value)) { + } + + // IsValid() is the public API to test if a CheckedNumeric is currently valid. + bool IsValid() const { return validity() == RANGE_VALID; } + + // ValueOrDie() The primary accessor for the underlying value. If the current + // state is not valid it will CHECK and crash. + T ValueOrDie() const { + CHECK(IsValid()); + return state_.value(); + } + + // ValueOrDefault(T default_value) A convenience method that returns the + // current value if the state is valid, and the supplied default_value for + // any other state. + T ValueOrDefault(T default_value) const { + return IsValid() ? state_.value() : default_value; + } + + // ValueFloating() - Since floating point values include their validity state, + // we provide an easy method for extracting them directly, without a risk of + // crashing on a CHECK. + T ValueFloating() const { + static_assert(std::numeric_limits<T>::is_iec559, "Argument must be float."); + return CheckedNumeric<T>::cast(*this).ValueUnsafe(); + } + + // validity() - DO NOT USE THIS IN EXTERNAL CODE - It is public right now for + // tests and to avoid a big matrix of friend operator overloads. But the + // values it returns are likely to change in the future. + // Returns: current validity state (i.e. valid, overflow, underflow, nan). + // TODO(jschuh): crbug.com/332611 Figure out and implement semantics for + // saturation/wrapping so we can expose this state consistently and implement + // saturated arithmetic. + RangeConstraint validity() const { return state_.validity(); } + + // ValueUnsafe() - DO NOT USE THIS IN EXTERNAL CODE - It is public right now + // for tests and to avoid a big matrix of friend operator overloads. But the + // values it returns are likely to change in the future. + // Returns: the raw numeric value, regardless of the current state. + // TODO(jschuh): crbug.com/332611 Figure out and implement semantics for + // saturation/wrapping so we can expose this state consistently and implement + // saturated arithmetic. + T ValueUnsafe() const { return state_.value(); } + + // Prototypes for the supported arithmetic operator overloads. + template <typename Src> CheckedNumeric& operator+=(Src rhs); + template <typename Src> CheckedNumeric& operator-=(Src rhs); + template <typename Src> CheckedNumeric& operator*=(Src rhs); + template <typename Src> CheckedNumeric& operator/=(Src rhs); + template <typename Src> CheckedNumeric& operator%=(Src rhs); + + CheckedNumeric operator-() const { + RangeConstraint validity; + T value = CheckedNeg(state_.value(), &validity); + // Negation is always valid for floating point. + if (std::numeric_limits<T>::is_iec559) + return CheckedNumeric<T>(value); + + validity = GetRangeConstraint(state_.validity() | validity); + return CheckedNumeric<T>(value, validity); + } + + CheckedNumeric Abs() const { + RangeConstraint validity; + T value = CheckedAbs(state_.value(), &validity); + // Absolute value is always valid for floating point. + if (std::numeric_limits<T>::is_iec559) + return CheckedNumeric<T>(value); + + validity = GetRangeConstraint(state_.validity() | validity); + return CheckedNumeric<T>(value, validity); + } + + // This function is available only for integral types. It returns an unsigned + // integer of the same width as the source type, containing the absolute value + // of the source, and properly handling signed min. + CheckedNumeric<typename UnsignedOrFloatForSize<T>::type> UnsignedAbs() const { + return CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>( + CheckedUnsignedAbs(state_.value()), state_.validity()); + } + + CheckedNumeric& operator++() { + *this += 1; + return *this; + } + + CheckedNumeric operator++(int) { + CheckedNumeric value = *this; + *this += 1; + return value; + } + + CheckedNumeric& operator--() { + *this -= 1; + return *this; + } + + CheckedNumeric operator--(int) { + CheckedNumeric value = *this; + *this -= 1; + return value; + } + + // These static methods behave like a convenience cast operator targeting + // the desired CheckedNumeric type. As an optimization, a reference is + // returned when Src is the same type as T. + template <typename Src> + static CheckedNumeric<T> cast( + Src u, + typename std::enable_if<std::numeric_limits<Src>::is_specialized, + int>::type = 0) { + return u; + } + + template <typename Src> + static CheckedNumeric<T> cast( + const CheckedNumeric<Src>& u, + typename std::enable_if<!is_same<Src, T>::value, int>::type = 0) { + return u; + } + + static const CheckedNumeric<T>& cast(const CheckedNumeric<T>& u) { return u; } + + private: + template <typename NumericType> + struct UnderlyingType { + using type = NumericType; + }; + + template <typename NumericType> + struct UnderlyingType<CheckedNumeric<NumericType>> { + using type = NumericType; + }; + + CheckedNumericState<T> state_; +}; + +// This is the boilerplate for the standard arithmetic operator overloads. A +// macro isn't the prettiest solution, but it beats rewriting these five times. +// Some details worth noting are: +// * We apply the standard arithmetic promotions. +// * We skip range checks for floating points. +// * We skip range checks for destination integers with sufficient range. +// TODO(jschuh): extract these out into templates. +#define BASE_NUMERIC_ARITHMETIC_OPERATORS(NAME, OP, COMPOUND_OP) \ + /* Binary arithmetic operator for CheckedNumerics of the same type. */ \ + template <typename T> \ + CheckedNumeric<typename ArithmeticPromotion<T>::type> operator OP( \ + const CheckedNumeric<T>& lhs, const CheckedNumeric<T>& rhs) { \ + typedef typename ArithmeticPromotion<T>::type Promotion; \ + /* Floating point always takes the fast path */ \ + if (std::numeric_limits<T>::is_iec559) \ + return CheckedNumeric<T>(lhs.ValueUnsafe() OP rhs.ValueUnsafe()); \ + if (IsIntegerArithmeticSafe<Promotion, T, T>::value) \ + return CheckedNumeric<Promotion>( \ + lhs.ValueUnsafe() OP rhs.ValueUnsafe(), \ + GetRangeConstraint(rhs.validity() | lhs.validity())); \ + RangeConstraint validity = RANGE_VALID; \ + T result = static_cast<T>(Checked##NAME( \ + static_cast<Promotion>(lhs.ValueUnsafe()), \ + static_cast<Promotion>(rhs.ValueUnsafe()), \ + &validity)); \ + return CheckedNumeric<Promotion>( \ + result, \ + GetRangeConstraint(validity | lhs.validity() | rhs.validity())); \ + } \ + /* Assignment arithmetic operator implementation from CheckedNumeric. */ \ + template <typename T> \ + template <typename Src> \ + CheckedNumeric<T>& CheckedNumeric<T>::operator COMPOUND_OP(Src rhs) { \ + *this = CheckedNumeric<T>::cast(*this) \ + OP CheckedNumeric<typename UnderlyingType<Src>::type>::cast(rhs); \ + return *this; \ + } \ + /* Binary arithmetic operator for CheckedNumeric of different type. */ \ + template <typename T, typename Src> \ + CheckedNumeric<typename ArithmeticPromotion<T, Src>::type> operator OP( \ + const CheckedNumeric<Src>& lhs, const CheckedNumeric<T>& rhs) { \ + typedef typename ArithmeticPromotion<T, Src>::type Promotion; \ + if (IsIntegerArithmeticSafe<Promotion, T, Src>::value) \ + return CheckedNumeric<Promotion>( \ + lhs.ValueUnsafe() OP rhs.ValueUnsafe(), \ + GetRangeConstraint(rhs.validity() | lhs.validity())); \ + return CheckedNumeric<Promotion>::cast(lhs) \ + OP CheckedNumeric<Promotion>::cast(rhs); \ + } \ + /* Binary arithmetic operator for left CheckedNumeric and right numeric. */ \ + template <typename T, typename Src> \ + CheckedNumeric<typename ArithmeticPromotion<T, Src>::type> operator OP( \ + const CheckedNumeric<T>& lhs, Src rhs) { \ + typedef typename ArithmeticPromotion<T, Src>::type Promotion; \ + if (IsIntegerArithmeticSafe<Promotion, T, Src>::value) \ + return CheckedNumeric<Promotion>(lhs.ValueUnsafe() OP rhs, \ + lhs.validity()); \ + return CheckedNumeric<Promotion>::cast(lhs) \ + OP CheckedNumeric<Promotion>::cast(rhs); \ + } \ + /* Binary arithmetic operator for right numeric and left CheckedNumeric. */ \ + template <typename T, typename Src> \ + CheckedNumeric<typename ArithmeticPromotion<T, Src>::type> operator OP( \ + Src lhs, const CheckedNumeric<T>& rhs) { \ + typedef typename ArithmeticPromotion<T, Src>::type Promotion; \ + if (IsIntegerArithmeticSafe<Promotion, T, Src>::value) \ + return CheckedNumeric<Promotion>(lhs OP rhs.ValueUnsafe(), \ + rhs.validity()); \ + return CheckedNumeric<Promotion>::cast(lhs) \ + OP CheckedNumeric<Promotion>::cast(rhs); \ + } + +BASE_NUMERIC_ARITHMETIC_OPERATORS(Add, +, += ) +BASE_NUMERIC_ARITHMETIC_OPERATORS(Sub, -, -= ) +BASE_NUMERIC_ARITHMETIC_OPERATORS(Mul, *, *= ) +BASE_NUMERIC_ARITHMETIC_OPERATORS(Div, /, /= ) +BASE_NUMERIC_ARITHMETIC_OPERATORS(Mod, %, %= ) + +#undef BASE_NUMERIC_ARITHMETIC_OPERATORS + +} // namespace internal + +using internal::CheckedNumeric; + +} // namespace base + +#endif // BASE_NUMERICS_SAFE_MATH_H_ diff --git a/security/sandbox/chromium/base/numerics/safe_math_impl.h b/security/sandbox/chromium/base/numerics/safe_math_impl.h new file mode 100644 index 000000000..4fbcc045b --- /dev/null +++ b/security/sandbox/chromium/base/numerics/safe_math_impl.h @@ -0,0 +1,545 @@ +// Copyright 2014 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef BASE_NUMERICS_SAFE_MATH_IMPL_H_ +#define BASE_NUMERICS_SAFE_MATH_IMPL_H_ + +#include <stddef.h> +#include <stdint.h> + +#include <cmath> +#include <cstdlib> +#include <limits> +#include <type_traits> + +#include "base/numerics/safe_conversions.h" +#include "base/template_util.h" + +namespace base { +namespace internal { + +// Everything from here up to the floating point operations is portable C++, +// but it may not be fast. This code could be split based on +// platform/architecture and replaced with potentially faster implementations. + +// Integer promotion templates used by the portable checked integer arithmetic. +template <size_t Size, bool IsSigned> +struct IntegerForSizeAndSign; +template <> +struct IntegerForSizeAndSign<1, true> { + typedef int8_t type; +}; +template <> +struct IntegerForSizeAndSign<1, false> { + typedef uint8_t type; +}; +template <> +struct IntegerForSizeAndSign<2, true> { + typedef int16_t type; +}; +template <> +struct IntegerForSizeAndSign<2, false> { + typedef uint16_t type; +}; +template <> +struct IntegerForSizeAndSign<4, true> { + typedef int32_t type; +}; +template <> +struct IntegerForSizeAndSign<4, false> { + typedef uint32_t type; +}; +template <> +struct IntegerForSizeAndSign<8, true> { + typedef int64_t type; +}; +template <> +struct IntegerForSizeAndSign<8, false> { + typedef uint64_t type; +}; + +// WARNING: We have no IntegerForSizeAndSign<16, *>. If we ever add one to +// support 128-bit math, then the ArithmeticPromotion template below will need +// to be updated (or more likely replaced with a decltype expression). + +template <typename Integer> +struct UnsignedIntegerForSize { + typedef typename std::enable_if< + std::numeric_limits<Integer>::is_integer, + typename IntegerForSizeAndSign<sizeof(Integer), false>::type>::type type; +}; + +template <typename Integer> +struct SignedIntegerForSize { + typedef typename std::enable_if< + std::numeric_limits<Integer>::is_integer, + typename IntegerForSizeAndSign<sizeof(Integer), true>::type>::type type; +}; + +template <typename Integer> +struct TwiceWiderInteger { + typedef typename std::enable_if< + std::numeric_limits<Integer>::is_integer, + typename IntegerForSizeAndSign< + sizeof(Integer) * 2, + std::numeric_limits<Integer>::is_signed>::type>::type type; +}; + +template <typename Integer> +struct PositionOfSignBit { + static const typename std::enable_if<std::numeric_limits<Integer>::is_integer, + size_t>::type value = + 8 * sizeof(Integer) - 1; +}; + +// This is used for UnsignedAbs, where we need to support floating-point +// template instantiations even though we don't actually support the operations. +// However, there is no corresponding implementation of e.g. CheckedUnsignedAbs, +// so the float versions will not compile. +template <typename Numeric, + bool IsInteger = std::numeric_limits<Numeric>::is_integer, + bool IsFloat = std::numeric_limits<Numeric>::is_iec559> +struct UnsignedOrFloatForSize; + +template <typename Numeric> +struct UnsignedOrFloatForSize<Numeric, true, false> { + typedef typename UnsignedIntegerForSize<Numeric>::type type; +}; + +template <typename Numeric> +struct UnsignedOrFloatForSize<Numeric, false, true> { + typedef Numeric type; +}; + +// Helper templates for integer manipulations. + +template <typename T> +bool HasSignBit(T x) { + // Cast to unsigned since right shift on signed is undefined. + return !!(static_cast<typename UnsignedIntegerForSize<T>::type>(x) >> + PositionOfSignBit<T>::value); +} + +// This wrapper undoes the standard integer promotions. +template <typename T> +T BinaryComplement(T x) { + return ~x; +} + +// Here are the actual portable checked integer math implementations. +// TODO(jschuh): Break this code out from the enable_if pattern and find a clean +// way to coalesce things into the CheckedNumericState specializations below. + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer, T>::type +CheckedAdd(T x, T y, RangeConstraint* validity) { + // Since the value of x+y is undefined if we have a signed type, we compute + // it using the unsigned type of the same size. + typedef typename UnsignedIntegerForSize<T>::type UnsignedDst; + UnsignedDst ux = static_cast<UnsignedDst>(x); + UnsignedDst uy = static_cast<UnsignedDst>(y); + UnsignedDst uresult = ux + uy; + // Addition is valid if the sign of (x + y) is equal to either that of x or + // that of y. + if (std::numeric_limits<T>::is_signed) { + if (HasSignBit(BinaryComplement((uresult ^ ux) & (uresult ^ uy)))) + *validity = RANGE_VALID; + else // Direction of wrap is inverse of result sign. + *validity = HasSignBit(uresult) ? RANGE_OVERFLOW : RANGE_UNDERFLOW; + + } else { // Unsigned is either valid or overflow. + *validity = BinaryComplement(x) >= y ? RANGE_VALID : RANGE_OVERFLOW; + } + return static_cast<T>(uresult); +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer, T>::type +CheckedSub(T x, T y, RangeConstraint* validity) { + // Since the value of x+y is undefined if we have a signed type, we compute + // it using the unsigned type of the same size. + typedef typename UnsignedIntegerForSize<T>::type UnsignedDst; + UnsignedDst ux = static_cast<UnsignedDst>(x); + UnsignedDst uy = static_cast<UnsignedDst>(y); + UnsignedDst uresult = ux - uy; + // Subtraction is valid if either x and y have same sign, or (x-y) and x have + // the same sign. + if (std::numeric_limits<T>::is_signed) { + if (HasSignBit(BinaryComplement((uresult ^ ux) & (ux ^ uy)))) + *validity = RANGE_VALID; + else // Direction of wrap is inverse of result sign. + *validity = HasSignBit(uresult) ? RANGE_OVERFLOW : RANGE_UNDERFLOW; + + } else { // Unsigned is either valid or underflow. + *validity = x >= y ? RANGE_VALID : RANGE_UNDERFLOW; + } + return static_cast<T>(uresult); +} + +// Integer multiplication is a bit complicated. In the fast case we just +// we just promote to a twice wider type, and range check the result. In the +// slow case we need to manually check that the result won't be truncated by +// checking with division against the appropriate bound. +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + sizeof(T) * 2 <= sizeof(uintmax_t), + T>::type +CheckedMul(T x, T y, RangeConstraint* validity) { + typedef typename TwiceWiderInteger<T>::type IntermediateType; + IntermediateType tmp = + static_cast<IntermediateType>(x) * static_cast<IntermediateType>(y); + *validity = DstRangeRelationToSrcRange<T>(tmp); + return static_cast<T>(tmp); +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + std::numeric_limits<T>::is_signed && + (sizeof(T) * 2 > sizeof(uintmax_t)), + T>::type +CheckedMul(T x, T y, RangeConstraint* validity) { + // If either side is zero then the result will be zero. + if (!x || !y) { + return RANGE_VALID; + + } else if (x > 0) { + if (y > 0) + *validity = + x <= std::numeric_limits<T>::max() / y ? RANGE_VALID : RANGE_OVERFLOW; + else + *validity = y >= std::numeric_limits<T>::min() / x ? RANGE_VALID + : RANGE_UNDERFLOW; + + } else { + if (y > 0) + *validity = x >= std::numeric_limits<T>::min() / y ? RANGE_VALID + : RANGE_UNDERFLOW; + else + *validity = + y >= std::numeric_limits<T>::max() / x ? RANGE_VALID : RANGE_OVERFLOW; + } + + return x * y; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + !std::numeric_limits<T>::is_signed && + (sizeof(T) * 2 > sizeof(uintmax_t)), + T>::type +CheckedMul(T x, T y, RangeConstraint* validity) { + *validity = (y == 0 || x <= std::numeric_limits<T>::max() / y) + ? RANGE_VALID + : RANGE_OVERFLOW; + return x * y; +} + +// Division just requires a check for an invalid negation on signed min/-1. +template <typename T> +T CheckedDiv(T x, + T y, + RangeConstraint* validity, + typename std::enable_if<std::numeric_limits<T>::is_integer, + int>::type = 0) { + if (std::numeric_limits<T>::is_signed && x == std::numeric_limits<T>::min() && + y == static_cast<T>(-1)) { + *validity = RANGE_OVERFLOW; + return std::numeric_limits<T>::min(); + } + + *validity = RANGE_VALID; + return x / y; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + std::numeric_limits<T>::is_signed, + T>::type +CheckedMod(T x, T y, RangeConstraint* validity) { + *validity = y > 0 ? RANGE_VALID : RANGE_INVALID; + return x % y; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + !std::numeric_limits<T>::is_signed, + T>::type +CheckedMod(T x, T y, RangeConstraint* validity) { + *validity = RANGE_VALID; + return x % y; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + std::numeric_limits<T>::is_signed, + T>::type +CheckedNeg(T value, RangeConstraint* validity) { + *validity = + value != std::numeric_limits<T>::min() ? RANGE_VALID : RANGE_OVERFLOW; + // The negation of signed min is min, so catch that one. + return -value; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + !std::numeric_limits<T>::is_signed, + T>::type +CheckedNeg(T value, RangeConstraint* validity) { + // The only legal unsigned negation is zero. + *validity = value ? RANGE_UNDERFLOW : RANGE_VALID; + return static_cast<T>( + -static_cast<typename SignedIntegerForSize<T>::type>(value)); +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + std::numeric_limits<T>::is_signed, + T>::type +CheckedAbs(T value, RangeConstraint* validity) { + *validity = + value != std::numeric_limits<T>::min() ? RANGE_VALID : RANGE_OVERFLOW; + return static_cast<T>(std::abs(value)); +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + !std::numeric_limits<T>::is_signed, + T>::type +CheckedAbs(T value, RangeConstraint* validity) { + // T is unsigned, so |value| must already be positive. + *validity = RANGE_VALID; + return value; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + std::numeric_limits<T>::is_signed, + typename UnsignedIntegerForSize<T>::type>::type +CheckedUnsignedAbs(T value) { + typedef typename UnsignedIntegerForSize<T>::type UnsignedT; + return value == std::numeric_limits<T>::min() + ? static_cast<UnsignedT>(std::numeric_limits<T>::max()) + 1 + : static_cast<UnsignedT>(std::abs(value)); +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_integer && + !std::numeric_limits<T>::is_signed, + T>::type +CheckedUnsignedAbs(T value) { + // T is unsigned, so |value| must already be positive. + return value; +} + +// These are the floating point stubs that the compiler needs to see. Only the +// negation operation is ever called. +#define BASE_FLOAT_ARITHMETIC_STUBS(NAME) \ + template <typename T> \ + typename std::enable_if<std::numeric_limits<T>::is_iec559, T>::type \ + Checked##NAME(T, T, RangeConstraint*) { \ + NOTREACHED(); \ + return 0; \ + } + +BASE_FLOAT_ARITHMETIC_STUBS(Add) +BASE_FLOAT_ARITHMETIC_STUBS(Sub) +BASE_FLOAT_ARITHMETIC_STUBS(Mul) +BASE_FLOAT_ARITHMETIC_STUBS(Div) +BASE_FLOAT_ARITHMETIC_STUBS(Mod) + +#undef BASE_FLOAT_ARITHMETIC_STUBS + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_iec559, T>::type CheckedNeg( + T value, + RangeConstraint*) { + return -value; +} + +template <typename T> +typename std::enable_if<std::numeric_limits<T>::is_iec559, T>::type CheckedAbs( + T value, + RangeConstraint*) { + return std::abs(value); +} + +// Floats carry around their validity state with them, but integers do not. So, +// we wrap the underlying value in a specialization in order to hide that detail +// and expose an interface via accessors. +enum NumericRepresentation { + NUMERIC_INTEGER, + NUMERIC_FLOATING, + NUMERIC_UNKNOWN +}; + +template <typename NumericType> +struct GetNumericRepresentation { + static const NumericRepresentation value = + std::numeric_limits<NumericType>::is_integer + ? NUMERIC_INTEGER + : (std::numeric_limits<NumericType>::is_iec559 ? NUMERIC_FLOATING + : NUMERIC_UNKNOWN); +}; + +template <typename T, NumericRepresentation type = + GetNumericRepresentation<T>::value> +class CheckedNumericState {}; + +// Integrals require quite a bit of additional housekeeping to manage state. +template <typename T> +class CheckedNumericState<T, NUMERIC_INTEGER> { + private: + T value_; + RangeConstraint validity_; + + public: + template <typename Src, NumericRepresentation type> + friend class CheckedNumericState; + + CheckedNumericState() : value_(0), validity_(RANGE_VALID) {} + + template <typename Src> + CheckedNumericState(Src value, RangeConstraint validity) + : value_(static_cast<T>(value)), + validity_(GetRangeConstraint(validity | + DstRangeRelationToSrcRange<T>(value))) { + static_assert(std::numeric_limits<Src>::is_specialized, + "Argument must be numeric."); + } + + // Copy constructor. + template <typename Src> + CheckedNumericState(const CheckedNumericState<Src>& rhs) + : value_(static_cast<T>(rhs.value())), + validity_(GetRangeConstraint( + rhs.validity() | DstRangeRelationToSrcRange<T>(rhs.value()))) {} + + template <typename Src> + explicit CheckedNumericState( + Src value, + typename std::enable_if<std::numeric_limits<Src>::is_specialized, + int>::type = 0) + : value_(static_cast<T>(value)), + validity_(DstRangeRelationToSrcRange<T>(value)) {} + + RangeConstraint validity() const { return validity_; } + T value() const { return value_; } +}; + +// Floating points maintain their own validity, but need translation wrappers. +template <typename T> +class CheckedNumericState<T, NUMERIC_FLOATING> { + private: + T value_; + + public: + template <typename Src, NumericRepresentation type> + friend class CheckedNumericState; + + CheckedNumericState() : value_(0.0) {} + + template <typename Src> + CheckedNumericState( + Src value, + RangeConstraint validity, + typename std::enable_if<std::numeric_limits<Src>::is_integer, int>::type = + 0) { + switch (DstRangeRelationToSrcRange<T>(value)) { + case RANGE_VALID: + value_ = static_cast<T>(value); + break; + + case RANGE_UNDERFLOW: + value_ = -std::numeric_limits<T>::infinity(); + break; + + case RANGE_OVERFLOW: + value_ = std::numeric_limits<T>::infinity(); + break; + + case RANGE_INVALID: + value_ = std::numeric_limits<T>::quiet_NaN(); + break; + + default: + NOTREACHED(); + } + } + + template <typename Src> + explicit CheckedNumericState( + Src value, + typename std::enable_if<std::numeric_limits<Src>::is_specialized, + int>::type = 0) + : value_(static_cast<T>(value)) {} + + // Copy constructor. + template <typename Src> + CheckedNumericState(const CheckedNumericState<Src>& rhs) + : value_(static_cast<T>(rhs.value())) {} + + RangeConstraint validity() const { + return GetRangeConstraint(value_ <= std::numeric_limits<T>::max(), + value_ >= -std::numeric_limits<T>::max()); + } + T value() const { return value_; } +}; + +// For integers less than 128-bit and floats 32-bit or larger, we can distil +// C/C++ arithmetic promotions down to two simple rules: +// 1. The type with the larger maximum exponent always takes precedence. +// 2. The resulting type must be promoted to at least an int. +// The following template specializations implement that promotion logic. +enum ArithmeticPromotionCategory { + LEFT_PROMOTION, + RIGHT_PROMOTION, + DEFAULT_PROMOTION +}; + +template <typename Lhs, + typename Rhs = Lhs, + ArithmeticPromotionCategory Promotion = + (MaxExponent<Lhs>::value > MaxExponent<Rhs>::value) + ? (MaxExponent<Lhs>::value > MaxExponent<int>::value + ? LEFT_PROMOTION + : DEFAULT_PROMOTION) + : (MaxExponent<Rhs>::value > MaxExponent<int>::value + ? RIGHT_PROMOTION + : DEFAULT_PROMOTION) > +struct ArithmeticPromotion; + +template <typename Lhs, typename Rhs> +struct ArithmeticPromotion<Lhs, Rhs, LEFT_PROMOTION> { + typedef Lhs type; +}; + +template <typename Lhs, typename Rhs> +struct ArithmeticPromotion<Lhs, Rhs, RIGHT_PROMOTION> { + typedef Rhs type; +}; + +template <typename Lhs, typename Rhs> +struct ArithmeticPromotion<Lhs, Rhs, DEFAULT_PROMOTION> { + typedef int type; +}; + +// We can statically check if operations on the provided types can wrap, so we +// can skip the checked operations if they're not needed. So, for an integer we +// care if the destination type preserves the sign and is twice the width of +// the source. +template <typename T, typename Lhs, typename Rhs> +struct IsIntegerArithmeticSafe { + static const bool value = !std::numeric_limits<T>::is_iec559 && + StaticDstRangeRelationToSrcRange<T, Lhs>::value == + NUMERIC_RANGE_CONTAINED && + sizeof(T) >= (2 * sizeof(Lhs)) && + StaticDstRangeRelationToSrcRange<T, Rhs>::value != + NUMERIC_RANGE_CONTAINED && + sizeof(T) >= (2 * sizeof(Rhs)); +}; + +} // namespace internal +} // namespace base + +#endif // BASE_NUMERICS_SAFE_MATH_IMPL_H_ |