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gecko-dev/third_party/rlbox/include/rlbox.hpp

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#pragma once
#include <array>
#include <cstring>
#include <memory>
#include <type_traits>
#include <utility>
#include "rlbox_app_pointer.hpp"
#include "rlbox_conversion.hpp"
#include "rlbox_helpers.hpp"
#include "rlbox_policy_types.hpp"
#include "rlbox_range.hpp"
#include "rlbox_sandbox.hpp"
#include "rlbox_stdlib.hpp"
#include "rlbox_struct_support.hpp"
#include "rlbox_type_traits.hpp"
#include "rlbox_types.hpp"
#include "rlbox_unwrap.hpp"
#include "rlbox_wrapper_traits.hpp"
namespace rlbox {
template<template<typename, typename> typename T_Wrap,
typename T,
typename T_Sbx>
class tainted_base_impl
{
KEEP_CLASSES_FRIENDLY
KEEP_CAST_FRIENDLY
public:
inline auto& impl() { return *static_cast<T_Wrap<T, T_Sbx>*>(this); }
inline auto& impl() const
{
return *static_cast<const T_Wrap<T, T_Sbx>*>(this);
}
/**
* @brief Unwrap a tainted value without verification. This is an unsafe
* operation and should be used with care.
*/
inline auto UNSAFE_unverified() const { return impl().get_raw_value(); }
/**
* @brief Like UNSAFE_unverified, but get the underlying sandbox
* representation.
*
* @param sandbox Reference to sandbox.
*
* For the Wasm-based sandbox, this function additionally validates the
* unwrapped value against the machine model of the sandbox (LP32).
*/
inline auto UNSAFE_sandboxed(rlbox_sandbox<T_Sbx>& sandbox) const
{
return impl().get_raw_sandbox_value(sandbox);
}
/**
* @brief Unwrap a tainted value without verification. This function should
* be used when unwrapping is safe.
*
* @param reason An explanation why the unverified unwrapping is safe.
*/
template<size_t N>
inline auto unverified_safe_because(const char (&reason)[N]) const
{
RLBOX_UNUSED(reason);
static_assert(!std::is_pointer_v<T>,
"unverified_safe_because does not support pointers. Use "
"unverified_safe_pointer_because.");
return UNSAFE_unverified();
}
template<size_t N>
inline auto unverified_safe_pointer_because(size_t count,
const char (&reason)[N]) const
{
RLBOX_UNUSED(reason);
static_assert(std::is_pointer_v<T>, "Expected pointer type");
using T_Pointed = std::remove_pointer_t<T>;
if_constexpr_named(cond1, std::is_pointer_v<T_Pointed>)
{
rlbox_detail_static_fail_because(
cond1,
"There is no way to use unverified_safe_pointer_because for "
"'pointers to pointers' safely. Use copy_and_verify instead.");
return nullptr;
}
auto ret = UNSAFE_unverified();
if (ret != nullptr) {
size_t bytes = sizeof(T) * count;
detail::check_range_doesnt_cross_app_sbx_boundary<T_Sbx>(ret, bytes);
}
return ret;
}
inline auto INTERNAL_unverified_safe() const { return UNSAFE_unverified(); }
#define BinaryOpValAndPtr(opSymbol) \
template<typename T_Rhs> \
inline constexpr auto operator opSymbol(const T_Rhs& rhs) \
const->tainted<decltype(std::declval<T>() opSymbol std::declval< \
detail::rlbox_remove_wrapper_t<T_Rhs>>()), \
T_Sbx> \
{ \
static_assert(detail::is_basic_type_v<T>, \
"Operator " #opSymbol \
" only supported for primitive and pointer types"); \
\
auto raw_rhs = detail::unwrap_value(rhs); \
\
if constexpr (std::is_pointer_v<T>) { \
static_assert(std::is_integral_v<decltype(raw_rhs)>, \
"Can only operate on numeric types"); \
auto ptr = impl().get_raw_value(); \
detail::dynamic_check(ptr != nullptr, \
"Pointer arithmetic on a null pointer"); \
/* increment the target by size of the data structure */ \
auto target = \
reinterpret_cast<uintptr_t>(ptr) opSymbol raw_rhs * sizeof(*impl()); \
auto no_overflow = rlbox_sandbox<T_Sbx>::is_in_same_sandbox( \
reinterpret_cast<const void*>(ptr), \
reinterpret_cast<const void*>(target)); \
detail::dynamic_check( \
no_overflow, \
"Pointer arithmetic overflowed a pointer beyond sandbox memory"); \
\
return tainted<T, T_Sbx>::internal_factory(reinterpret_cast<T>(target)); \
} else { \
auto raw = impl().get_raw_value(); \
auto ret = raw opSymbol raw_rhs; \
using T_Ret = decltype(ret); \
return tainted<T_Ret, T_Sbx>::internal_factory(ret); \
} \
} \
RLBOX_REQUIRE_SEMI_COLON
BinaryOpValAndPtr(+);
BinaryOpValAndPtr(-);
#undef BinaryOpValAndPtr
#define BinaryOp(opSymbol) \
template<typename T_Rhs> \
inline constexpr auto operator opSymbol(const T_Rhs& rhs) \
const->tainted<decltype(std::declval<T>() opSymbol std::declval< \
detail::rlbox_remove_wrapper_t<T_Rhs>>()), \
T_Sbx> \
{ \
static_assert(detail::is_fundamental_or_enum_v<T>, \
"Operator " #opSymbol \
" only supported for primitive types"); \
\
auto raw = impl().get_raw_value(); \
auto raw_rhs = detail::unwrap_value(rhs); \
static_assert(std::is_integral_v<decltype(raw_rhs)> || \
std::is_floating_point_v<decltype(raw_rhs)>, \
"Can only operate on numeric types"); \
\
auto ret = raw opSymbol raw_rhs; \
using T_Ret = decltype(ret); \
return tainted<T_Ret, T_Sbx>::internal_factory(ret); \
} \
RLBOX_REQUIRE_SEMI_COLON
BinaryOp(*);
BinaryOp(/);
BinaryOp(%);
BinaryOp(^);
BinaryOp(&);
BinaryOp(|);
BinaryOp(<<);
BinaryOp(>>);
#undef BinaryOp
#define CompoundAssignmentOp(opSymbol) \
template<typename T_Rhs> \
inline constexpr T_Wrap<T, T_Sbx>& operator opSymbol##=(const T_Rhs& rhs) \
{ \
auto& this_ref = impl(); \
this_ref = this_ref opSymbol rhs; \
return this_ref; \
} \
RLBOX_REQUIRE_SEMI_COLON
CompoundAssignmentOp(+);
CompoundAssignmentOp(-);
CompoundAssignmentOp(*);
CompoundAssignmentOp(/);
CompoundAssignmentOp(%);
CompoundAssignmentOp(^);
CompoundAssignmentOp(&);
CompoundAssignmentOp(|);
CompoundAssignmentOp(<<);
CompoundAssignmentOp(>>);
#undef CompoundAssignmentOp
#define PreIncDecOps(opSymbol) \
inline constexpr T_Wrap<T, T_Sbx>& operator opSymbol##opSymbol() \
{ \
auto& this_ref = impl(); \
this_ref = this_ref opSymbol 1; \
return this_ref; \
} \
RLBOX_REQUIRE_SEMI_COLON
PreIncDecOps(+);
PreIncDecOps(-);
#undef PreIncDecOps
#define PostIncDecOps(opSymbol) \
inline constexpr T_Wrap<T, T_Sbx> operator opSymbol##opSymbol(int) \
{ \
tainted<T, T_Sbx> ret = impl(); \
operator++(); \
return ret; \
} \
RLBOX_REQUIRE_SEMI_COLON
PostIncDecOps(+);
PostIncDecOps(-);
#undef PostIncDecOps
#define BooleanBinaryOp(opSymbol) \
template<typename T_Rhs> \
inline constexpr auto operator opSymbol(const T_Rhs& rhs) \
const->tainted<decltype(std::declval<T>() opSymbol std::declval< \
detail::rlbox_remove_wrapper_t<T_Rhs>>()), \
T_Sbx> \
{ \
static_assert(detail::is_fundamental_or_enum_v<T>, \
"Operator " #opSymbol \
" only supported for primitive types"); \
\
auto raw = impl().get_raw_value(); \
auto raw_rhs = detail::unwrap_value(rhs); \
static_assert(std::is_integral_v<decltype(raw_rhs)>, \
"Can only operate on numeric types"); \
\
auto ret = raw opSymbol raw_rhs; \
using T_Ret = decltype(ret); \
return tainted<T_Ret, T_Sbx>::internal_factory(ret); \
} \
\
template<typename T_Rhs> \
inline constexpr auto operator opSymbol(const T_Rhs&&) \
const->tainted<decltype(std::declval<T>() opSymbol std::declval< \
detail::rlbox_remove_wrapper_t<T_Rhs>>()), \
T_Sbx> \
{ \
rlbox_detail_static_fail_because( \
detail::true_v<T_Rhs>, \
"C++ does not permit safe overloading of && and || operations as this " \
"affects the short circuiting behaviour of these operations. RLBox " \
"does let you use && and || with tainted in limited situations - when " \
"all arguments starting from the second are local variables. It does " \
"not allow it if arguments starting from the second are expressions.\n" \
"For example the following is not allowed\n" \
"\n" \
"tainted<bool, T_Sbx> a = true;\n" \
"auto r = a && true && sandbox.invoke_sandbox_function(getBool);\n" \
"\n" \
"However the following would be allowed\n" \
"tainted<bool, T_Sbx> a = true;\n" \
"auto b = true\n" \
"auto c = sandbox.invoke_sandbox_function(getBool);\n" \
"auto r = a && b && c;\n" \
"\n" \
"Note that these 2 programs are not identical. The first program may " \
"or may not call getBool, while second program always calls getBool"); \
return tainted<bool, T_Sbx>(false); \
} \
RLBOX_REQUIRE_SEMI_COLON
BooleanBinaryOp(&&);
BooleanBinaryOp(||);
#undef BooleanBinaryOp
#define UnaryOp(opSymbol) \
inline auto operator opSymbol() \
{ \
static_assert(detail::is_fundamental_or_enum_v<T>, \
"Operator " #opSymbol " only supported for primitive"); \
\
auto raw = impl().get_raw_value(); \
auto ret = opSymbol raw; \
using T_Ret = decltype(ret); \
return tainted<T_Ret, T_Sbx>::internal_factory(ret); \
} \
RLBOX_REQUIRE_SEMI_COLON
UnaryOp(-);
UnaryOp(~);
#undef UnaryOp
/**
* @brief Comparison operators. Comparisons to values in sandbox memory can
* only return a "tainted_boolean_hint" as the values in memory can be
* incorrect or malicously change in the future.
*
* @tparam T_Rhs
* @param rhs
* @return One of either a bool, tainted<bool>, or a tainted_boolean_hint
* depending on the arguments to the binary expression.
*/
#define CompareOp(opSymbol, permit_pointers) \
template<typename T_Rhs> \
inline constexpr auto operator opSymbol(const T_Rhs& rhs) const \
{ \
using T_RhsNoQ = detail::remove_cv_ref_t<T_Rhs>; \
constexpr bool check_rhs_hint = \
detail::rlbox_is_tainted_volatile_v<T_RhsNoQ> || \
detail::rlbox_is_tainted_boolean_hint_v<T_RhsNoQ>; \
constexpr bool check_lhs_hint = \
detail::rlbox_is_tainted_volatile_v<T_Wrap<T, T_Sbx>>; \
constexpr bool is_hint = check_lhs_hint || check_rhs_hint; \
\
constexpr bool is_unwrapped = \
detail::rlbox_is_tainted_v<T_Wrap<T, T_Sbx>> && \
std::is_null_pointer_v<T_RhsNoQ>; \
\
/* Sanity check - can't be a hint and unwrapped */ \
static_assert(is_hint ? !is_unwrapped : true, \
"Internal error: Could not deduce type for comparison. " \
"Please file a bug."); \
\
if constexpr (!permit_pointers && std::is_pointer_v<T>) { \
rlbox_detail_static_fail_because( \
std::is_pointer_v<T>, \
"Only == and != comparisons are allowed for pointers"); \
} \
\
bool ret = (impl().get_raw_value() opSymbol detail::unwrap_value(rhs)); \
\
if constexpr (is_hint) { \
return tainted_boolean_hint(ret); \
} else if constexpr (is_unwrapped) { \
return ret; \
} else { \
return tainted<bool, T_Sbx>(ret); \
} \
} \
RLBOX_REQUIRE_SEMI_COLON
CompareOp(==, true /* permit_pointers */);
CompareOp(!=, true /* permit_pointers */);
CompareOp(<, false /* permit_pointers */);
CompareOp(<=, false /* permit_pointers */);
CompareOp(>, false /* permit_pointers */);
CompareOp(>=, false /* permit_pointers */);
#undef CompareOp
private:
using T_OpSubscriptArrRet = std::conditional_t<
std::is_pointer_v<T>,
tainted_volatile<detail::dereference_result_t<T>, T_Sbx>, // is_pointer
T_Wrap<detail::dereference_result_t<T>, T_Sbx> // is_array
>;
public:
template<typename T_Rhs>
inline const T_OpSubscriptArrRet& operator[](T_Rhs&& rhs) const
{
static_assert(std::is_pointer_v<T> || detail::is_c_or_std_array_v<T>,
"Operator [] supports pointers and arrays only");
auto raw_rhs = detail::unwrap_value(rhs);
static_assert(std::is_integral_v<decltype(raw_rhs)>,
"Can only index with numeric types");
if constexpr (std::is_pointer_v<T>) {
auto ptr = this->impl().get_raw_value();
// increment the target by size of the data structure
auto target =
reinterpret_cast<uintptr_t>(ptr) + raw_rhs * sizeof(*this->impl());
auto no_overflow = rlbox_sandbox<T_Sbx>::is_in_same_sandbox(
ptr, reinterpret_cast<const void*>(target));
detail::dynamic_check(
no_overflow,
"Pointer arithmetic overflowed a pointer beyond sandbox memory");
auto target_wrap = tainted<const T, T_Sbx>::internal_factory(
reinterpret_cast<const T>(target));
return *target_wrap;
} else {
using T_Rhs_Unsigned = std::make_unsigned_t<decltype(raw_rhs)>;
detail::dynamic_check(
raw_rhs >= 0 && static_cast<T_Rhs_Unsigned>(raw_rhs) <
std::extent_v<detail::std_array_to_c_arr_t<T>, 0>,
"Static array indexing overflow");
const void* target_ptr;
if constexpr (detail::rlbox_is_tainted_v<T_Wrap<T, T_Sbx>>) {
auto& data_ref = impl().get_raw_value_ref();
target_ptr = &(data_ref[raw_rhs]);
} else {
auto& data_ref = impl().get_sandbox_value_ref();
auto target_ptr_vol = &(data_ref[raw_rhs]);
// target_ptr is a volatile... remove this.
// Safe as we will return a tainted_volatile if this is the case
target_ptr = detail::remove_volatile_from_ptr_cast(target_ptr_vol);
}
using T_Target = const T_Wrap<detail::dereference_result_t<T>, T_Sbx>;
auto wrapped_target_ptr = reinterpret_cast<T_Target*>(target_ptr);
return *wrapped_target_ptr;
}
}
template<typename T_Rhs>
inline T_OpSubscriptArrRet& operator[](T_Rhs&& rhs)
{
return const_cast<T_OpSubscriptArrRet&>(std::as_const(*this)[rhs]);
}
private:
using T_OpDerefRet = tainted_volatile<std::remove_pointer_t<T>, T_Sbx>;
public:
inline T_OpDerefRet& operator*() const
{
static_assert(std::is_pointer_v<T>, "Operator * only allowed on pointers");
auto ret_ptr_const =
reinterpret_cast<const T_OpDerefRet*>(impl().get_raw_value());
// Safe - If T_OpDerefRet is not a const ptr, this is trivially safe
// If T_OpDerefRet is a const ptr, then the const is captured
// inside the wrapper
auto ret_ptr = const_cast<T_OpDerefRet*>(ret_ptr_const);
return *ret_ptr;
}
// We need to implement the -> operator even if T is not a struct
// So that we can support code patterns such as the below
// tainted<T*> a;
// a->UNSAFE_unverified();
inline const T_OpDerefRet* operator->() const
{
static_assert(std::is_pointer_v<T>,
"Operator -> only supported for pointer types");
return reinterpret_cast<const T_OpDerefRet*>(impl().get_raw_value());
}
inline T_OpDerefRet* operator->()
{
return const_cast<T_OpDerefRet*>(std::as_const(*this).operator->());
}
inline auto operator!()
{
if_constexpr_named(cond1, std::is_pointer_v<T>)
{
return impl() == nullptr;
}
else if_constexpr_named(cond2, std::is_same_v<std::remove_cv_t<T>, bool>)
{
return impl() == false;
}
else
{
auto unknownCase = !(cond1 || cond2);
rlbox_detail_static_fail_because(
unknownCase,
"Operator ! only permitted for pointer or boolean types. For other"
"types, unwrap the tainted value with the copy_and_verify API and then"
"use operator !");
}
}
/**
* @brief Copy tainted value from sandbox and verify it.
*
* @param verifier Function used to verify the copied value.
* @tparam T_Func the type of the verifier.
* @return Whatever the verifier function returns.
*/
template<typename T_Func>
inline auto copy_and_verify(T_Func verifier) const
{
using T_Deref = std::remove_cv_t<std::remove_pointer_t<T>>;
if_constexpr_named(cond1, detail::is_fundamental_or_enum_v<T>)
{
auto val = impl().get_raw_value();
return verifier(val);
}
else if_constexpr_named(
cond2, detail::is_one_level_ptr_v<T> && !std::is_class_v<T_Deref>)
{
// Some paths don't use the verifier
RLBOX_UNUSED(verifier);
if_constexpr_named(subcond1, std::is_void_v<T_Deref>)
{
rlbox_detail_static_fail_because(
subcond1,
"copy_and_verify not recommended for void* as it could lead to some "
"anti-patterns in verifiers. Cast it to a different tainted pointer "
"with sandbox_reinterpret_cast and then call copy_and_verify. "
"Alternately, you can use the UNSAFE_unverified API to do this "
"without casting.");
return nullptr;
}
// Test with detail::is_func_ptr_v to check for member funcs also
else if_constexpr_named(subcond2, detail::is_func_ptr_v<T>)
{
rlbox_detail_static_fail_because(
subcond2,
"copy_and_verify cannot be applied to function pointers as this "
"makes a deep copy. This is not possible for function pointers. "
"Consider copy_and_verify_address instead.");
return nullptr;
}
else
{
auto val = impl().get_raw_value();
if (val == nullptr) {
return verifier(nullptr);
} else {
// Important to assign to a local variable (i.e. make a copy)
// Else, for tainted_volatile, this will allow a
// time-of-check-time-of-use attack
auto val_copy = std::make_unique<T_Deref>();
*val_copy = *val;
return verifier(std::move(val_copy));
}
}
}
else if_constexpr_named(
cond3, detail::is_one_level_ptr_v<T> && std::is_class_v<T_Deref>)
{
auto val_copy = std::make_unique<tainted<T_Deref, T_Sbx>>(*impl());
return verifier(std::move(val_copy));
}
else if_constexpr_named(cond4, std::is_array_v<T>)
{
static_assert(
detail::is_fundamental_or_enum_v<std::remove_all_extents_t<T>>,
"copy_and_verify on arrays is only safe for fundamental or enum types. "
"For arrays of other types, apply copy_and_verify on each element "
"individually --- a[i].copy_and_verify(...)");
auto copy = impl().get_raw_value();
return verifier(copy);
}
else
{
auto unknownCase = !(cond1 || cond2 || cond3 || cond4);
rlbox_detail_static_fail_because(
unknownCase,
"copy_and_verify not supported for this type as it may be unsafe");
}
}
private:
using T_CopyAndVerifyRangeEl =
detail::valid_array_el_t<std::remove_cv_t<std::remove_pointer_t<T>>>;
// Template needed to ensure that function isn't instantiated for unsupported
// types like function pointers which causes compile errors...
template<typename T2 = T>
inline const void* verify_range_helper(std::size_t count) const
{
static_assert(std::is_pointer_v<T>);
static_assert(detail::is_fundamental_or_enum_v<T_CopyAndVerifyRangeEl>);
detail::dynamic_check(
count != 0,
"Called copy_and_verify_range/copy_and_verify_string with count 0");
auto start = reinterpret_cast<const void*>(impl().get_raw_value());
if (start == nullptr) {
return nullptr;
}
detail::check_range_doesnt_cross_app_sbx_boundary<T_Sbx>(
start, count * sizeof(T_CopyAndVerifyRangeEl));
return start;
}
template<typename T2 = T>
inline std::unique_ptr<T_CopyAndVerifyRangeEl[]> copy_and_verify_range_helper(
std::size_t count) const
{
const void* start = verify_range_helper(count);
if (start == nullptr) {
return nullptr;
}
auto target = std::make_unique<T_CopyAndVerifyRangeEl[]>(count);
for (size_t i = 0; i < count; i++) {
auto p_src_i_tainted = &(impl()[i]);
auto p_src_i = p_src_i_tainted.get_raw_value();
detail::convert_type_fundamental_or_array(target[i], *p_src_i);
}
return target;
}
public:
/**
* @brief Copy a range of tainted values from sandbox and verify them.
*
* @param verifier Function used to verify the copied value.
* @param count Number of elements to copy.
* @tparam T_Func the type of the verifier. If the tainted type is ``int*``
* then ``T_Func = T_Ret(*)(unique_ptr<int[]>)``.
* @return Whatever the verifier function returns.
*/
template<typename T_Func>
inline auto copy_and_verify_range(T_Func verifier, std::size_t count) const
{
static_assert(std::is_pointer_v<T>,
"Can only call copy_and_verify_range on pointers");
static_assert(
detail::is_fundamental_or_enum_v<T_CopyAndVerifyRangeEl>,
"copy_and_verify_range is only safe for ranges of "
"fundamental or enum types. For other types, call "
"copy_and_verify on each element --- a[i].copy_and_verify(...)");
std::unique_ptr<T_CopyAndVerifyRangeEl[]> target =
copy_and_verify_range_helper(count);
return verifier(std::move(target));
}
/**
* @brief Copy a tainted string from sandbox and verify it.
*
* @param verifier Function used to verify the copied value.
* @tparam T_Func the type of the verifier either
* ``T_Ret(*)(unique_ptr<char[]>)`` or ``T_Ret(*)(std::string)``
* @return Whatever the verifier function returns.
*/
template<typename T_Func>
inline auto copy_and_verify_string(T_Func verifier) const
{
static_assert(std::is_pointer_v<T>,
"Can only call copy_and_verify_string on pointers");
static_assert(std::is_same_v<char, T_CopyAndVerifyRangeEl>,
"copy_and_verify_string only allows char*");
using T_VerifParam = detail::func_first_arg_t<T_Func>;
auto start = impl().get_raw_value();
if_constexpr_named(
cond1,
std::is_same_v<T_VerifParam, std::unique_ptr<char[]>> ||
std::is_same_v<T_VerifParam, std::unique_ptr<const char[]>>)
{
if (start == nullptr) {
return verifier(nullptr);
}
// it is safe to run strlen on a tainted<string> as worst case, the string
// does not have a null and we try to copy all the memory out of the
// sandbox however, copy_and_verify_range ensures that we never copy
// memory outsider the range
auto str_len = std::strlen(start) + 1;
std::unique_ptr<T_CopyAndVerifyRangeEl[]> target =
copy_and_verify_range_helper(str_len);
// ensure the string has a trailing null
target[str_len - 1] = '\0';
return verifier(std::move(target));
}
else if_constexpr_named(cond2, std::is_same_v<T_VerifParam, std::string>)
{
if (start == nullptr) {
std::string param = "";
return verifier(param);
}
// it is safe to run strlen on a tainted<string> as worst case, the string
// does not have a null and we try to copy all the memory out of the
// sandbox however, copy_and_verify_range ensures that we never copy
// memory outsider the range
auto str_len = std::strlen(start) + 1;
const char* checked_start = (const char*)verify_range_helper(str_len);
if (checked_start == nullptr) {
std::string param = "";
return verifier(param);
}
std::string copy(checked_start, str_len - 1);
return verifier(std::move(copy));
}
else
{
constexpr bool unknownCase = !(cond1 || cond2);
rlbox_detail_static_fail_because(
unknownCase,
"copy_and_verify_string verifier parameter should either be "
"unique_ptr<char[]>, unique_ptr<const char[]> or std::string");
}
}
/**
* @brief Copy a tainted pointer from sandbox and verify the address.
*
* This function is useful if you need to verify physical bits representing
* the address of a pointer. Other APIs such as copy_and_verify performs a
* deep copy and changes the address bits.
*
* @param verifier Function used to verify the copied value.
* @tparam T_Func the type of the verifier ``T_Ret(*)(uintptr_t)``
* @return Whatever the verifier function returns.
*/
template<typename T_Func>
inline auto copy_and_verify_address(T_Func verifier) const
{
static_assert(std::is_pointer_v<T>,
"copy_and_verify_address must be used on pointers");
auto val = reinterpret_cast<uintptr_t>(impl().get_raw_value());
return verifier(val);
}
/**
* @brief Copy a tainted pointer to a buffer from sandbox and verify the
* address.
*
* This function is useful if you need to verify physical bits representing
* the address of a buffer. Other APIs such as copy_and_verify performs a
* deep copy and changes the address bits.
*
* @param verifier Function used to verify the copied value.
* @param size Size of the buffer. Buffer with length size is expected to fit
* inside sandbox memory.
* @tparam T_Func the type of the verifier ``T_Ret(*)(uintptr_t)``
* @return Whatever the verifier function returns.
*/
template<typename T_Func>
inline auto copy_and_verify_buffer_address(T_Func verifier,
std::size_t size) const
{
static_assert(std::is_pointer_v<T>,
"copy_and_verify_address must be used on pointers");
auto val = reinterpret_cast<uintptr_t>(verify_range_helper(size));
return verifier(val);
}
};
#define BinaryOpWrappedRhs(opSymbol) \
template<template<typename, typename> typename T_Wrap, \
typename T, \
typename T_Sbx, \
typename T_Lhs, \
RLBOX_ENABLE_IF(!detail::rlbox_is_wrapper_v<T_Lhs> && \
!detail::rlbox_is_tainted_boolean_hint_v<T_Lhs>)> \
inline constexpr auto operator opSymbol( \
const T_Lhs& lhs, const tainted_base_impl<T_Wrap, T, T_Sbx>& rhs) \
{ \
/* Handles the case for "3 + tainted", where + is a binary op */ \
/* Technically pointer arithmetic can be performed as 3 + tainted_ptr */ \
/* as well. However, this is unusual and to keep the code simple we do */ \
/* not support this. */ \
static_assert( \
std::is_arithmetic_v<T_Lhs>, \
"Binary expressions between an non tainted type and tainted" \
"type is only permitted if the first value is the tainted type. Try " \
"changing the order of the binary expression accordingly"); \
auto ret = tainted<T_Lhs, T_Sbx>(lhs) opSymbol rhs.impl(); \
return ret; \
} \
RLBOX_REQUIRE_SEMI_COLON
BinaryOpWrappedRhs(+);
BinaryOpWrappedRhs(-);
BinaryOpWrappedRhs(*);
BinaryOpWrappedRhs(/);
BinaryOpWrappedRhs(%);
BinaryOpWrappedRhs(^);
BinaryOpWrappedRhs(&);
BinaryOpWrappedRhs(|);
BinaryOpWrappedRhs(<<);
BinaryOpWrappedRhs(>>);
BinaryOpWrappedRhs(==);
BinaryOpWrappedRhs(!=);
BinaryOpWrappedRhs(<);
BinaryOpWrappedRhs(<=);
BinaryOpWrappedRhs(>);
BinaryOpWrappedRhs(>=);
#undef BinaryOpWrappedRhs
#define BooleanBinaryOpWrappedRhs(opSymbol) \
template<template<typename, typename> typename T_Wrap, \
typename T, \
typename T_Sbx, \
typename T_Lhs, \
RLBOX_ENABLE_IF(!detail::rlbox_is_wrapper_v<T_Lhs> && \
!detail::rlbox_is_tainted_boolean_hint_v<T_Lhs>)> \
inline constexpr auto operator opSymbol( \
const T_Lhs& lhs, const tainted_base_impl<T_Wrap, T, T_Sbx>& rhs) \
{ \
static_assert( \
std::is_arithmetic_v<T_Lhs>, \
"Binary expressions between an non tainted type and tainted" \
"type is only permitted if the first value is the tainted type. Try " \
"changing the order of the binary expression accordingly"); \
auto ret = tainted<T_Lhs, T_Sbx>(lhs) opSymbol rhs.impl(); \
return ret; \
} \
\
template<template<typename, typename> typename T_Wrap, \
typename T, \
typename T_Sbx, \
typename T_Lhs, \
RLBOX_ENABLE_IF(!detail::rlbox_is_wrapper_v<T_Lhs> && \
!detail::rlbox_is_tainted_boolean_hint_v<T_Lhs>)> \
inline constexpr auto operator opSymbol( \
const T_Lhs&, const tainted_base_impl<T_Wrap, T, T_Sbx>&&) \
{ \
rlbox_detail_static_fail_because( \
detail::true_v<T_Lhs>, \
"C++ does not permit safe overloading of && and || operations as this " \
"affects the short circuiting behaviour of these operations. RLBox " \
"does let you use && and || with tainted in limited situations - when " \
"all arguments starting from the second are local variables. It does " \
"not allow it if arguments starting from the second are expressions.\n" \
"For example the following is not allowed\n" \
"\n" \
"tainted<bool, T_Sbx> a = true;\n" \
"auto r = a && true && sandbox.invoke_sandbox_function(getBool);\n" \
"\n" \
"However the following would be allowed\n" \
"tainted<bool, T_Sbx> a = true;\n" \
"auto b = true\n" \
"auto c = sandbox.invoke_sandbox_function(getBool);\n" \
"auto r = a && b && c;\n" \
"\n" \
"Note that these 2 programs are not identical. The first program may " \
"or may not call getBool, while second program always calls getBool"); \
return tainted<bool, T_Sbx>(false); \
} \
RLBOX_REQUIRE_SEMI_COLON
BooleanBinaryOpWrappedRhs(&&);
BooleanBinaryOpWrappedRhs(||);
#undef BooleanBinaryOpWrappedRhs
namespace tainted_detail {
template<typename T, typename T_Sbx>
using tainted_repr_t = detail::c_to_std_array_t<T>;
template<typename T, typename T_Sbx>
using tainted_vol_repr_t =
detail::c_to_std_array_t<std::add_volatile_t<typename rlbox_sandbox<
T_Sbx>::template convert_to_sandbox_equivalent_nonclass_t<T>>>;
}
/**
* @brief Tainted values represent untrusted values that originate from the
* sandbox.
*/
template<typename T, typename T_Sbx>
class tainted : public tainted_base_impl<tainted, T, T_Sbx>
{
KEEP_CLASSES_FRIENDLY
KEEP_CAST_FRIENDLY
// Classes recieve their own specialization
static_assert(
!std::is_class_v<T>,
"Missing definition for class T. This error occurs for one "
"of 2 reasons.\n"
" 1) Make sure you have include a call rlbox_load_structs_from_library "
"for this library with this class included.\n"
" 2) Make sure you run (re-run) the struct-dump tool to list "
"all structs in use by your program.\n");
static_assert(
detail::is_basic_type_v<T> || std::is_array_v<T>,
"Tainted types only support fundamental, enum, pointer, array and struct "
"types. Please file a bug if more support is needed.");
private:
using T_ClassBase = tainted_base_impl<tainted, T, T_Sbx>;
using T_AppType = tainted_detail::tainted_repr_t<T, T_Sbx>;
using T_SandboxedType = tainted_detail::tainted_vol_repr_t<T, T_Sbx>;
T_AppType data;
inline auto& get_raw_value_ref() noexcept { return data; }
inline auto& get_raw_value_ref() const noexcept { return data; }
inline std::remove_cv_t<T_AppType> get_raw_value() const noexcept
{
return data;
}
inline std::remove_cv_t<T_SandboxedType> get_raw_sandbox_value(
rlbox_sandbox<T_Sbx>& sandbox) const
{
std::remove_cv_t<T_SandboxedType> ret;
using namespace detail;
convert_type_non_class<T_Sbx,
adjust_type_direction::TO_SANDBOX,
adjust_type_context::SANDBOX>(
ret, data, nullptr /* example_unsandboxed_ptr */, &sandbox);
return ret;
};
inline const void* find_example_pointer_or_null() const noexcept
{
if constexpr (std::is_array_v<T>) {
auto& data_ref = get_raw_value_ref();
for (size_t i = 0; i < std::extent_v<T>; i++) {
const void* ret = data[i].find_example_pointer_or_null();
if (ret != nullptr) {
return ret;
}
}
} else if constexpr (std::is_pointer_v<T> && !detail::is_func_ptr_v<T>) {
auto data = get_raw_value();
return data;
}
return nullptr;
}
// Initializing with a pointer is dangerous and permitted only internally
template<typename T2 = T, RLBOX_ENABLE_IF(std::is_pointer_v<T2>)>
tainted(T2 val, const void* /* internal_tag */)
: data(val)
{
// Sanity check
static_assert(std::is_pointer_v<T>);
}
template<typename T_Rhs>
static inline tainted<T, T_Sbx> internal_factory(T_Rhs&& rhs)
{
if constexpr (std::is_pointer_v<std::remove_reference_t<T_Rhs>>) {
const void* internal_tag = nullptr;
return tainted(std::forward<T_Rhs>(rhs), internal_tag);
} else {
return tainted(std::forward<T_Rhs>(rhs));
}
}
public:
tainted() = default;
tainted(const tainted<T, T_Sbx>& p) = default;
tainted(const tainted_volatile<T, T_Sbx>& p)
{
// Need to construct an example_unsandboxed_ptr for pointers or arrays of
// pointers. Since tainted_volatile is the type of data in sandbox memory,
// the address of data (&data) refers to a location in sandbox memory and
// can thus be the example_unsandboxed_ptr
const volatile void* p_data_ref = &p.get_sandbox_value_ref();
const void* example_unsandboxed_ptr = const_cast<const void*>(p_data_ref);
using namespace detail;
convert_type_non_class<T_Sbx,
adjust_type_direction::TO_APPLICATION,
adjust_type_context::EXAMPLE>(
get_raw_value_ref(),
p.get_sandbox_value_ref(),
example_unsandboxed_ptr,
nullptr /* sandbox_ptr */);
}
// Initializing with a pointer is dangerous and permitted only internally
template<typename T2 = T, RLBOX_ENABLE_IF(std::is_pointer_v<T2>)>
tainted(T2 val)
: data(val)
{
rlbox_detail_static_fail_because(
std::is_pointer_v<T2>,
"Assignment of pointers is not safe as it could\n "
"1) Leak pointers from the appliction to the sandbox which may break "
"ASLR\n "
"2) Pass inaccessible pointers to the sandbox leading to crash\n "
"3) Break sandboxes that require pointers to be swizzled first\n "
"\n "
"Instead, if you want to pass in a pointer, do one of the following\n "
"1) Allocate with malloc_in_sandbox, and pass in a tainted pointer\n "
"2) For pointers that point to functions in the application, register "
"with sandbox.register_callback(\"foo\"), and pass in the registered "
"value\n "
"3) For pointers that point to functions in the sandbox, get the "
"address with get_sandbox_function_address(sandbox, foo), and pass in "
"the "
"address\n "
"4) For raw pointers, use assign_raw_pointer which performs required "
"safety checks\n ");
}
tainted(
const sandbox_callback<
detail::function_ptr_t<T> // Need to ensure we never generate code that
// creates a sandbox_callback of a non function
,
T_Sbx>&)
{
rlbox_detail_static_fail_because(
detail::true_v<T>,
"RLBox does not support assigning sandbox_callback values to tainted "
"types (i.e. types that live in application memory).\n"
"If you still want to do this, consider changing your code to store the "
"value in sandbox memory as follows. Convert\n\n"
"sandbox_callback<T_Func, Sbx> cb = ...;\n"
"tainted<T_Func, Sbx> foo = cb;\n\n"
"to\n\n"
"tainted<T_Func*, Sbx> foo_ptr = sandbox.malloc_in_sandbox<T_Func*>();\n"
"*foo_ptr = cb;\n\n"
"This would keep the assignment in sandbox memory");
}
tainted(const std::nullptr_t& arg)
: data(arg)
{
static_assert(std::is_pointer_v<T>);
}
// We explicitly disable this constructor if it has one of the signatures
// above, so that we give the above constructors a higher priority. We only
// allow this for fundamental types as this is potentially unsafe for pointers
// and structs
template<typename T_Arg,
RLBOX_ENABLE_IF(
!detail::rlbox_is_wrapper_v<std::remove_reference_t<T_Arg>> &&
detail::is_fundamental_or_enum_v<T> &&
detail::is_fundamental_or_enum_v<std::remove_reference_t<T_Arg>>)>
tainted(T_Arg&& arg)
: data(std::forward<T_Arg>(arg))
{}
template<typename T_Rhs>
void assign_raw_pointer(rlbox_sandbox<T_Sbx>& sandbox, T_Rhs val)
{
static_assert(std::is_pointer_v<T_Rhs>, "Must be a pointer");
static_assert(std::is_assignable_v<T&, T_Rhs>,
"Should assign pointers of compatible types.");
// Maybe a function pointer, so we need to cast
const void* cast_val = reinterpret_cast<const void*>(val);
bool safe = sandbox.is_pointer_in_sandbox_memory(cast_val);
detail::dynamic_check(
safe,
"Tried to assign a pointer that is not in the sandbox.\n "
"This is not safe as it could\n "
"1) Leak pointers from the appliction to the sandbox which may break "
"ASLR\n "
"2) Pass inaccessible pointers to the sandbox leading to crash\n "
"3) Break sandboxes that require pointers to be swizzled first\n "
"\n "
"Instead, if you want to pass in a pointer, do one of the following\n "
"1) Allocate with malloc_in_sandbox, and pass in a tainted pointer\n "
"2) For pointers that point to functions in the application, register "
"with sandbox.register_callback(\"foo\"), and pass in the registered "
"value\n "
"3) For pointers that point to functions in the sandbox, get the "
"address with get_sandbox_function_address(sandbox, foo), and pass in "
"the "
"address\n ");
data = val;
}
inline tainted_opaque<T, T_Sbx> to_opaque()
{
return *reinterpret_cast<tainted_opaque<T, T_Sbx>*>(this);
}
template<typename T_Dummy = void>
operator bool() const
{
if_constexpr_named(cond1, std::is_pointer_v<T>)
{
// We return this without the tainted wrapper as the checking for null
// doesn't really "induce" tainting in the application If the
// application is checking this pointer for null, then it is robust to
// this pointer being null or not null
return get_raw_value() != nullptr;
}
else
{
auto unknownCase = !(cond1);
rlbox_detail_static_fail_because(
unknownCase,
"Implicit conversion to bool is only permitted for pointer types. For "
"other types, unwrap the tainted value with the copy_and_verify API "
"and then perform the required checks");
}
}
};
template<typename T, typename T_Sbx>
inline tainted<T, T_Sbx> from_opaque(tainted_opaque<T, T_Sbx> val)
{
return *reinterpret_cast<tainted<T, T_Sbx>*>(&val);
}
/**
* @brief Tainted volatile values are like tainted values but still point to
* sandbox memory. Dereferencing a tainted pointer produces a tainted_volatile.
*/
template<typename T, typename T_Sbx>
class tainted_volatile : public tainted_base_impl<tainted_volatile, T, T_Sbx>
{
KEEP_CLASSES_FRIENDLY
KEEP_CAST_FRIENDLY
// Classes recieve their own specialization
static_assert(
!std::is_class_v<T>,
"Missing definition for class T. This error occurs for one "
"of 2 reasons.\n"
" 1) Make sure you have include a call rlbox_load_structs_from_library "
"for this library with this class included.\n"
" 2) Make sure you run (re-run) the struct-dump tool to list "
"all structs in use by your program.\n");
static_assert(
detail::is_basic_type_v<T> || std::is_array_v<T>,
"Tainted types only support fundamental, enum, pointer, array and struct "
"types. Please file a bug if more support is needed.");
private:
using T_ClassBase = tainted_base_impl<tainted_volatile, T, T_Sbx>;
using T_AppType = tainted_detail::tainted_repr_t<T, T_Sbx>;
using T_SandboxedType = tainted_detail::tainted_vol_repr_t<T, T_Sbx>;
T_SandboxedType data;
inline auto& get_sandbox_value_ref() noexcept { return data; }
inline auto& get_sandbox_value_ref() const noexcept { return data; }
inline std::remove_cv_t<T_AppType> get_raw_value() const
{
std::remove_cv_t<T_AppType> ret;
// Need to construct an example_unsandboxed_ptr for pointers or arrays of
// pointers. Since tainted_volatile is the type of data in sandbox memory,
// the address of data (&data) refers to a location in sandbox memory and
// can thus be the example_unsandboxed_ptr
const volatile void* data_ref = &data;
const void* example_unsandboxed_ptr = const_cast<const void*>(data_ref);
using namespace detail;
convert_type_non_class<T_Sbx,
adjust_type_direction::TO_APPLICATION,
adjust_type_context::EXAMPLE>(
ret, data, example_unsandboxed_ptr, nullptr /* sandbox_ptr */);
return ret;
}
inline std::remove_cv_t<T_SandboxedType> get_raw_sandbox_value()
const noexcept
{
return data;
};
inline std::remove_cv_t<T_SandboxedType> get_raw_sandbox_value(
rlbox_sandbox<T_Sbx>& sandbox) const noexcept
{
RLBOX_UNUSED(sandbox);
return data;
};
tainted_volatile() = default;
tainted_volatile(const tainted_volatile<T, T_Sbx>& p) = default;
public:
inline tainted<const T*, T_Sbx> operator&() const noexcept
{
auto ref =
detail::remove_volatile_from_ptr_cast(&this->get_sandbox_value_ref());
auto ref_cast = reinterpret_cast<const T*>(ref);
return tainted<const T*, T_Sbx>::internal_factory(ref_cast);
}
inline tainted<T*, T_Sbx> operator&() noexcept
{
return sandbox_const_cast<T*>(&std::as_const(*this));
}
// Needed as the definition of unary & above shadows the base's binary &
rlbox_detail_forward_binop_to_base(&, T_ClassBase);
template<typename T_RhsRef>
inline tainted_volatile<T, T_Sbx>& operator=(T_RhsRef&& val)
{
using T_Rhs = std::remove_reference_t<T_RhsRef>;
using T_Rhs_El = std::remove_all_extents_t<T_Rhs>;
// Need to construct an example_unsandboxed_ptr for pointers or arrays of
// pointers. Since tainted_volatile is the type of data in sandbox memory,
// the address of data (&data) refers to a location in sandbox memory and
// can thus be the example_unsandboxed_ptr
const volatile void* data_ref = &get_sandbox_value_ref();
const void* example_unsandboxed_ptr = const_cast<const void*>(data_ref);
// Some branches don't use this
RLBOX_UNUSED(example_unsandboxed_ptr);
if_constexpr_named(
cond1, std::is_same_v<std::remove_const_t<T_Rhs>, std::nullptr_t>)
{
static_assert(std::is_pointer_v<T>,
"Null pointer can only be assigned to pointers");
// assign using an integer instead of nullptr, as the pointer field may be
// represented as integer
data = 0;
}
else if_constexpr_named(cond2, detail::rlbox_is_tainted_v<T_Rhs>)
{
using namespace detail;
convert_type_non_class<T_Sbx,
adjust_type_direction::TO_SANDBOX,
adjust_type_context::EXAMPLE>(
get_sandbox_value_ref(),
val.get_raw_value_ref(),
example_unsandboxed_ptr,
nullptr /* sandbox_ptr */);
}
else if_constexpr_named(cond3, detail::rlbox_is_tainted_volatile_v<T_Rhs>)
{
using namespace detail;
convert_type_non_class<T_Sbx,
adjust_type_direction::NO_CHANGE,
adjust_type_context::EXAMPLE>(
get_sandbox_value_ref(),
val.get_sandbox_value_ref(),
example_unsandboxed_ptr,
nullptr /* sandbox_ptr */);
}
else if_constexpr_named(cond4, detail::rlbox_is_sandbox_callback_v<T_Rhs>)
{
using T_RhsFunc = detail::rlbox_remove_wrapper_t<T_Rhs>;
// need to perform some typechecking to ensure we are assigning compatible
// function pointer types only
if_constexpr_named(subcond1, !std::is_assignable_v<T&, T_RhsFunc>)
{
rlbox_detail_static_fail_because(
subcond1,
"Trying to assign function pointer to field of incompatible types");
}
else
{
// Need to reinterpret_cast as the representation of the signature of a
// callback uses the machine model of the sandbox, while the field uses
// that of the application. But we have already checked above that this
// is safe.
auto func = val.get_raw_sandbox_value();
using T_Cast = std::remove_volatile_t<T_SandboxedType>;
get_sandbox_value_ref() = (T_Cast)func;
}
}
else if_constexpr_named(
cond5,
detail::is_fundamental_or_enum_v<T> ||
(std::is_array_v<T> && !std::is_pointer_v<T_Rhs_El>))
{
detail::convert_type_fundamental_or_array(get_sandbox_value_ref(), val);
}
else if_constexpr_named(
cond6, std::is_pointer_v<T_Rhs> || std::is_pointer_v<T_Rhs_El>)
{
rlbox_detail_static_fail_because(
cond6,
"Assignment of pointers is not safe as it could\n "
"1) Leak pointers from the appliction to the sandbox which may break "
"ASLR\n "
"2) Pass inaccessible pointers to the sandbox leading to crash\n "
"3) Break sandboxes that require pointers to be swizzled first\n "
"\n "
"Instead, if you want to pass in a pointer, do one of the following\n "
"1) Allocate with malloc_in_sandbox, and pass in a tainted pointer\n "
"2) For pointers that point to functions in the application, register "
"with sandbox.register_callback(\"foo\"), and pass in the registered "
"value\n "
"3) For pointers that point to functions in the sandbox, get the "
"address with get_sandbox_function_address(sandbox, foo), and pass in "
"the "
"address\n "
"4) For raw pointers, use assign_raw_pointer which performs required "
"safety checks\n ");
}
else
{
auto unknownCase =
!(cond1 || cond2 || cond3 || cond4 || cond5 /* || cond6 */);
rlbox_detail_static_fail_because(
unknownCase, "Assignment of the given type of value is not supported");
}
return *this;
}
template<typename T_Rhs>
void assign_raw_pointer(rlbox_sandbox<T_Sbx>& sandbox, T_Rhs val)
{
static_assert(std::is_pointer_v<T_Rhs>, "Must be a pointer");
static_assert(std::is_assignable_v<T&, T_Rhs>,
"Should assign pointers of compatible types.");
// Maybe a function pointer, so we need to cast
const void* cast_val = reinterpret_cast<const void*>(val);
bool safe = sandbox.is_pointer_in_sandbox_memory(cast_val);
detail::dynamic_check(
safe,
"Tried to assign a pointer that is not in the sandbox.\n "
"This is not safe as it could\n "
"1) Leak pointers from the appliction to the sandbox which may break "
"ASLR\n "
"2) Pass inaccessible pointers to the sandbox leading to crash\n "
"3) Break sandboxes that require pointers to be swizzled first\n "
"\n "
"Instead, if you want to pass in a pointer, do one of the following\n "
"1) Allocate with malloc_in_sandbox, and pass in a tainted pointer\n "
"2) For pointers that point to functions in the application, register "
"with sandbox.register_callback(\"foo\"), and pass in the registered "
"value\n "
"3) For pointers that point to functions in the sandbox, get the "
"address with get_sandbox_function_address(sandbox, foo), and pass in "
"the "
"address\n ");
get_sandbox_value_ref() =
sandbox.template get_sandboxed_pointer<T_Rhs>(cast_val);
}
template<typename T_Dummy = void>
operator bool() const
{
rlbox_detail_static_fail_because(
detail::true_v<T_Dummy>,
"Cannot apply implicit conversion to bool on values that are located in "
"sandbox memory. This error occurs if you compare a dereferenced value "
"such as the code shown below\n\n"
"tainted<int**> a = ...;\n"
"assert(*a);\n\n"
"Instead you can write this code as \n"
"tainted<int*> temp = *a;\n"
"assert(temp);\n");
return false;
}
};
}
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