ladybird/Kernel/StdLib.cpp

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/MemMem.h>
#include <AK/Types.h>
#include <Kernel/Arch/SafeMem.h>
#include <Kernel/Arch/SmapDisabler.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/StdLib.h>
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ErrorOr<NonnullOwnPtr<Kernel::KString>> try_copy_kstring_from_user(Userspace<char const*> user_str, size_t user_str_size)
{
bool is_user = Kernel::Memory::is_user_range(user_str.vaddr(), user_str_size);
if (!is_user)
return EFAULT;
Kernel::SmapDisabler disabler;
void* fault_at;
ssize_t length = Kernel::safe_strnlen(user_str.unsafe_userspace_ptr(), user_str_size, fault_at);
if (length < 0) {
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dbgln("copy_kstring_from_user({:p}, {}) failed at {} (strnlen)", static_cast<void const*>(user_str.unsafe_userspace_ptr()), user_str_size, VirtualAddress { fault_at });
return EFAULT;
}
char* buffer;
auto new_string = TRY(Kernel::KString::try_create_uninitialized(length, buffer));
buffer[length] = '\0';
if (length == 0)
return new_string;
if (!Kernel::safe_memcpy(buffer, user_str.unsafe_userspace_ptr(), (size_t)length, fault_at)) {
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dbgln("copy_kstring_from_user({:p}, {}) failed at {} (memcpy)", static_cast<void const*>(user_str.unsafe_userspace_ptr()), user_str_size, VirtualAddress { fault_at });
return EFAULT;
}
return new_string;
}
ErrorOr<Time> copy_time_from_user(timespec const* ts_user)
{
timespec ts {};
TRY(copy_from_user(&ts, ts_user, sizeof(timespec)));
return Time::from_timespec(ts);
}
ErrorOr<Time> copy_time_from_user(timeval const* tv_user)
{
timeval tv {};
TRY(copy_from_user(&tv, tv_user, sizeof(timeval)));
return Time::from_timeval(tv);
}
template<>
ErrorOr<Time> copy_time_from_user<const timeval>(Userspace<timeval const*> src) { return copy_time_from_user(src.unsafe_userspace_ptr()); }
template<>
ErrorOr<Time> copy_time_from_user<timeval>(Userspace<timeval*> src) { return copy_time_from_user(src.unsafe_userspace_ptr()); }
template<>
ErrorOr<Time> copy_time_from_user<const timespec>(Userspace<timespec const*> src) { return copy_time_from_user(src.unsafe_userspace_ptr()); }
template<>
ErrorOr<Time> copy_time_from_user<timespec>(Userspace<timespec*> src) { return copy_time_from_user(src.unsafe_userspace_ptr()); }
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Optional<u32> user_atomic_fetch_add_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_fetch_add_relaxed(var, val);
}
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Optional<u32> user_atomic_exchange_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_exchange_relaxed(var, val);
}
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Optional<u32> user_atomic_load_relaxed(u32 volatile* var)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_load_relaxed(var);
}
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bool user_atomic_store_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return false; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return false;
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_store_relaxed(var, val);
}
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Optional<bool> user_atomic_compare_exchange_relaxed(u32 volatile* var, u32& expected, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
VERIFY(!Kernel::Memory::is_user_range(VirtualAddress(&expected), sizeof(expected)));
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_compare_exchange_relaxed(var, expected, val);
}
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Optional<u32> user_atomic_fetch_and_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_fetch_and_relaxed(var, val);
}
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Optional<u32> user_atomic_fetch_and_not_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_fetch_and_not_relaxed(var, val);
}
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Optional<u32> user_atomic_fetch_or_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_fetch_or_relaxed(var, val);
}
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Optional<u32> user_atomic_fetch_xor_relaxed(u32 volatile* var, u32 val)
{
if (FlatPtr(var) & 3)
return {}; // not aligned!
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(FlatPtr(var)), sizeof(*var));
if (!is_user)
return {};
Kernel::SmapDisabler disabler;
return Kernel::safe_atomic_fetch_xor_relaxed(var, val);
}
ErrorOr<void> copy_to_user(void* dest_ptr, void const* src_ptr, size_t n)
{
if (!Kernel::Memory::is_user_range(VirtualAddress(dest_ptr), n))
return EFAULT;
VERIFY(!Kernel::Memory::is_user_range(VirtualAddress(src_ptr), n));
Kernel::SmapDisabler disabler;
void* fault_at;
if (!Kernel::safe_memcpy(dest_ptr, src_ptr, n, fault_at)) {
VERIFY(VirtualAddress(fault_at) >= VirtualAddress(dest_ptr) && VirtualAddress(fault_at) <= VirtualAddress((FlatPtr)dest_ptr + n));
dbgln("copy_to_user({:p}, {:p}, {}) failed at {}", dest_ptr, src_ptr, n, VirtualAddress { fault_at });
return EFAULT;
}
return {};
}
ErrorOr<void> copy_from_user(void* dest_ptr, void const* src_ptr, size_t n)
{
if (!Kernel::Memory::is_user_range(VirtualAddress(src_ptr), n))
return EFAULT;
VERIFY(!Kernel::Memory::is_user_range(VirtualAddress(dest_ptr), n));
Kernel::SmapDisabler disabler;
void* fault_at;
if (!Kernel::safe_memcpy(dest_ptr, src_ptr, n, fault_at)) {
VERIFY(VirtualAddress(fault_at) >= VirtualAddress(src_ptr) && VirtualAddress(fault_at) <= VirtualAddress((FlatPtr)src_ptr + n));
dbgln("copy_from_user({:p}, {:p}, {}) failed at {}", dest_ptr, src_ptr, n, VirtualAddress { fault_at });
return EFAULT;
}
return {};
}
ErrorOr<void> memset_user(void* dest_ptr, int c, size_t n)
{
bool is_user = Kernel::Memory::is_user_range(VirtualAddress(dest_ptr), n);
if (!is_user)
return EFAULT;
Kernel::SmapDisabler disabler;
void* fault_at;
if (!Kernel::safe_memset(dest_ptr, c, n, fault_at)) {
dbgln("memset_user({:p}, {}, {}) failed at {}", dest_ptr, c, n, VirtualAddress { fault_at });
return EFAULT;
}
return {};
}
#if defined(__clang__) && defined(ENABLE_KERNEL_LTO)
// Due to a chicken-and-egg situation, certain linker-defined symbols that are added on-demand (like the GOT)
// need to be present before LTO bitcode files are compiled. And since we don't link to any native object files,
// the linker does not know that _GLOBAL_OFFSET_TABLE_ is needed, so it doesn't define it, so linking as a PIE fails.
// See https://bugs.llvm.org/show_bug.cgi?id=39634
FlatPtr missing_got_workaround()
{
extern volatile FlatPtr _GLOBAL_OFFSET_TABLE_;
return _GLOBAL_OFFSET_TABLE_;
}
#endif
extern "C" {
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void const* memmem(void const* haystack, size_t haystack_length, void const* needle, size_t needle_length)
{
return AK::memmem(haystack, haystack_length, needle, needle_length);
}
// Functions that are automatically called by the C++ compiler.
// Declare them first, to tell the silly compiler that they are indeed being used.
[[noreturn]] void __stack_chk_fail() __attribute__((used));
[[noreturn]] void __stack_chk_fail_local() __attribute__((used));
extern "C" int __cxa_atexit(void (*)(void*), void*, void*);
[[noreturn]] void __cxa_pure_virtual();
[[noreturn]] void __stack_chk_fail()
{
VERIFY_NOT_REACHED();
}
[[noreturn]] void __stack_chk_fail_local()
{
VERIFY_NOT_REACHED();
}
extern "C" int __cxa_atexit(void (*)(void*), void*, void*)
{
VERIFY_NOT_REACHED();
return 0;
}
[[noreturn]] void __cxa_pure_virtual()
{
VERIFY_NOT_REACHED();
}
}