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65b420f996
These instances were detected by searching for files that include AK/Memory.h, but don't match the regex: \\b(fast_u32_copy|fast_u32_fill|secure_zero|timing_safe_compare)\\b This regex is pessimistic, so there might be more files that don't actually use any memory function. In theory, one might use LibCPP to detect things like this automatically, but let's do this one step after another.
66 lines
2.6 KiB
C++
66 lines
2.6 KiB
C++
/*
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* Copyright (c) 2021, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Devices/DeviceManagement.h>
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#include <Kernel/Devices/MemoryDevice.h>
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#include <Kernel/Memory/AnonymousVMObject.h>
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#include <Kernel/Memory/TypedMapping.h>
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#include <Kernel/Sections.h>
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namespace Kernel {
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UNMAP_AFTER_INIT NonnullLockRefPtr<MemoryDevice> MemoryDevice::must_create()
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{
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auto memory_device_or_error = DeviceManagement::try_create_device<MemoryDevice>();
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// FIXME: Find a way to propagate errors
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VERIFY(!memory_device_or_error.is_error());
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return memory_device_or_error.release_value();
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}
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UNMAP_AFTER_INIT MemoryDevice::MemoryDevice()
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: CharacterDevice(1, 1)
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{
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}
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UNMAP_AFTER_INIT MemoryDevice::~MemoryDevice() = default;
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ErrorOr<size_t> MemoryDevice::read(OpenFileDescription&, u64 offset, UserOrKernelBuffer& buffer, size_t length)
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{
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if (!MM.is_allowed_to_read_physical_memory_for_userspace(PhysicalAddress(offset), length)) {
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dbgln_if(MEMORY_DEVICE_DEBUG, "MemoryDevice: Trying to read physical memory at {} for range of {} bytes failed due to violation of access", PhysicalAddress(offset), length);
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return EINVAL;
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}
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auto mapping = TRY(Memory::map_typed<u8>(PhysicalAddress(offset), length));
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auto bytes = ReadonlyBytes { mapping.ptr(), length };
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TRY(buffer.write(bytes));
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return length;
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}
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ErrorOr<NonnullLockRefPtr<Memory::VMObject>> MemoryDevice::vmobject_for_mmap(Process&, Memory::VirtualRange const& range, u64& offset, bool)
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{
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auto viewed_address = PhysicalAddress(offset);
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// Note: This check happens to guard against possible memory leak.
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// For example, if we try to mmap physical memory from 0x1000 to 0x2000 and you
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// can actually mmap only from 0x1001, then we would fail as usual.
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// However, in such case if we mmap from 0x1002, we are technically not violating
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// any rules, besides the fact that we mapped an entire page with two bytes which we
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// were not supposed to see. To prevent that, if we use mmap(2) syscall, we should
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// always consider the start page to be aligned on PAGE_SIZE, or to be more precise
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// is to be set to the page base of that start address.
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VERIFY(viewed_address == viewed_address.page_base());
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if (!MM.is_allowed_to_read_physical_memory_for_userspace(viewed_address, range.size())) {
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dbgln_if(MEMORY_DEVICE_DEBUG, "MemoryDevice: Trying to mmap physical memory at {} for range of {} bytes failed due to violation of access", viewed_address, range.size());
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return EINVAL;
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}
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offset = 0;
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return TRY(Memory::AnonymousVMObject::try_create_for_physical_range(viewed_address, range.size()));
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}
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}
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