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c8d9f1b9c9
Since the CPU already does almost all necessary validation steps for us, we don't really need to attempt to do this. Doing it ourselves doesn't really work very reliably, because we'd have to account for other processors modifying virtual memory, and we'd have to account for e.g. pages not being able to be allocated due to insufficient resources. So change the copy_to/from_user (and associated helper functions) to use the new safe_memcpy, which will return whether it succeeded or not. The only manual validation step needed (which the CPU can't perform for us) is making sure the pointers provided by user mode aren't pointing to kernel mappings. To make it easier to read/write from/to either kernel or user mode data add the UserOrKernelBuffer helper class, which will internally either use copy_from/to_user or directly memcpy, or pass the data through directly using a temporary buffer on the stack. Last but not least we need to keep syscall params trivial as we need to copy them from/to user mode using copy_from/to_user.
123 lines
3.7 KiB
C++
123 lines
3.7 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/RefCounted.h>
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#include <AK/RefPtr.h>
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#include <AK/String.h>
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#include <AK/StringView.h>
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#include <Kernel/FileSystem/InodeIdentifier.h>
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#include <Kernel/KResult.h>
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#include <Kernel/Lock.h>
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#include <Kernel/UnixTypes.h>
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#include <Kernel/UserOrKernelBuffer.h>
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namespace Kernel {
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static const u32 mepoch = 476763780;
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class Inode;
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class FileDescription;
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class LocalSocket;
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class VMObject;
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class FS : public RefCounted<FS> {
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friend class Inode;
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public:
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virtual ~FS();
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unsigned fsid() const { return m_fsid; }
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static FS* from_fsid(u32);
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static void sync();
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static void lock_all();
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virtual bool initialize() = 0;
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virtual const char* class_name() const = 0;
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virtual NonnullRefPtr<Inode> root_inode() const = 0;
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virtual bool supports_watchers() const { return false; }
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bool is_readonly() const { return m_readonly; }
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virtual unsigned total_block_count() const { return 0; }
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virtual unsigned free_block_count() const { return 0; }
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virtual unsigned total_inode_count() const { return 0; }
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virtual unsigned free_inode_count() const { return 0; }
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virtual KResult prepare_to_unmount() const { return KSuccess; }
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struct DirectoryEntryView {
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DirectoryEntryView(const StringView& name, InodeIdentifier, u8 file_type);
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StringView name;
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InodeIdentifier inode;
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u8 file_type { 0 };
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};
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virtual void flush_writes() {}
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size_t block_size() const { return m_block_size; }
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virtual bool is_file_backed() const { return false; }
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// Converts file types that are used internally by the filesystem to DT_* types
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virtual u8 internal_file_type_to_directory_entry_type(const DirectoryEntryView& entry) const { return entry.file_type; }
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protected:
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FS();
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void set_block_size(size_t);
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mutable Lock m_lock { "FS" };
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private:
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unsigned m_fsid { 0 };
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size_t m_block_size { 0 };
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bool m_readonly { false };
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};
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inline FS* InodeIdentifier::fs()
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{
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return FS::from_fsid(m_fsid);
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}
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inline const FS* InodeIdentifier::fs() const
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{
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return FS::from_fsid(m_fsid);
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}
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}
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namespace AK {
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template<>
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struct Traits<Kernel::InodeIdentifier> : public GenericTraits<Kernel::InodeIdentifier> {
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static unsigned hash(const Kernel::InodeIdentifier& inode) { return pair_int_hash(inode.fsid(), inode.index()); }
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};
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}
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