mirror of
https://github.com/RGBCube/serenity
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1ca0ac5207
By default, disallow reading of values in that directory. Later on, we will enable sparingly read access to specific files. The idea that led to this mechanism was suggested by Jean-Baptiste Boric (also known as boricj in GitHub), to prevent access to sensitive information in the SysFS if someone adds a new file in the /sys/kernel directory.
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
/*
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* Copyright (c) 2022, 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/FileSystem/SysFS/Subsystems/Kernel/GlobalInformation.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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ErrorOr<size_t> SysFSGlobalInformation::read_bytes(off_t offset, size_t count, UserOrKernelBuffer& buffer, OpenFileDescription* description) const
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{
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dbgln_if(SYSFS_DEBUG, "SysFSGlobalInformation @ {}: read_bytes offset: {} count: {}", name(), offset, count);
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VERIFY(offset >= 0);
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VERIFY(buffer.user_or_kernel_ptr());
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if (!description)
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return Error::from_errno(EIO);
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MutexLocker locker(m_refresh_lock);
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if (!description->data()) {
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dbgln("SysFSGlobalInformation: Do not have cached data!");
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return Error::from_errno(EIO);
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}
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auto& typed_cached_data = static_cast<SysFSInodeData&>(*description->data());
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auto& data_buffer = typed_cached_data.buffer;
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if (!data_buffer || (size_t)offset >= data_buffer->size())
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return 0;
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ssize_t nread = min(static_cast<off_t>(data_buffer->size() - offset), static_cast<off_t>(count));
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TRY(buffer.write(data_buffer->data() + offset, nread));
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return nread;
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}
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SysFSGlobalInformation::SysFSGlobalInformation(SysFSDirectory const& parent_directory)
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: SysFSComponent(parent_directory)
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{
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}
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ErrorOr<void> SysFSGlobalInformation::refresh_data(OpenFileDescription& description) const
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{
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MutexLocker lock(m_refresh_lock);
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auto& cached_data = description.data();
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if (!cached_data) {
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cached_data = adopt_own_if_nonnull(new (nothrow) SysFSInodeData);
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if (!cached_data)
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return ENOMEM;
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}
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auto builder = TRY(KBufferBuilder::try_create());
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TRY(Process::current().jail().with([&](auto& my_jail) -> ErrorOr<void> {
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if (my_jail && !is_readable_by_jailed_processes())
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return Error::from_errno(EPERM);
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TRY(const_cast<SysFSGlobalInformation&>(*this).try_generate(builder));
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return {};
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}));
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auto& typed_cached_data = static_cast<SysFSInodeData&>(*cached_data);
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typed_cached_data.buffer = builder.build();
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if (!typed_cached_data.buffer)
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return ENOMEM;
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return {};
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}
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}
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