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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.
249 lines
8.6 KiB
C++
249 lines
8.6 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/HashTable.h>
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#include <AK/NonnullRefPtrVector.h>
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#include <AK/String.h>
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#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/Forward.h>
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#include <Kernel/SpinLock.h>
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#include <Kernel/VM/PhysicalPage.h>
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#include <Kernel/VM/Region.h>
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#include <Kernel/VM/VMObject.h>
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namespace Kernel {
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#define PAGE_ROUND_UP(x) ((((u32)(x)) + PAGE_SIZE - 1) & (~(PAGE_SIZE - 1)))
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template<typename T>
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inline T* low_physical_to_virtual(T* physical)
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{
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return (T*)(((u8*)physical) + 0xc0000000);
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}
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inline u32 low_physical_to_virtual(u32 physical)
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{
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return physical + 0xc0000000;
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}
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template<typename T>
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inline T* virtual_to_low_physical(T* physical)
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{
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return (T*)(((u8*)physical) - 0xc0000000);
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}
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inline u32 virtual_to_low_physical(u32 physical)
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{
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return physical - 0xc0000000;
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}
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class KBuffer;
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class SynthFSInode;
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#define MM Kernel::MemoryManager::the()
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struct MemoryManagerData {
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SpinLock<u8> m_quickmap_in_use;
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u32 m_quickmap_prev_flags;
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};
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extern RecursiveSpinLock s_mm_lock;
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class MemoryManager {
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AK_MAKE_ETERNAL
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friend class PageDirectory;
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friend class PhysicalPage;
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friend class PhysicalRegion;
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friend class Region;
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friend class VMObject;
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friend Optional<KBuffer> procfs$mm(InodeIdentifier);
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friend Optional<KBuffer> procfs$memstat(InodeIdentifier);
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public:
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static MemoryManager& the();
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static bool is_initialized();
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static void initialize(u32 cpu);
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static inline MemoryManagerData& get_data()
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{
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return Processor::current().get_mm_data();
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}
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PageFaultResponse handle_page_fault(const PageFault&);
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void enter_process_paging_scope(Process&);
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bool validate_user_stack(const Process&, VirtualAddress) const;
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enum class ShouldZeroFill {
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No,
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Yes
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};
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RefPtr<PhysicalPage> allocate_user_physical_page(ShouldZeroFill = ShouldZeroFill::Yes, bool* did_purge = nullptr);
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RefPtr<PhysicalPage> allocate_supervisor_physical_page();
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NonnullRefPtrVector<PhysicalPage> allocate_contiguous_supervisor_physical_pages(size_t size);
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void deallocate_user_physical_page(const PhysicalPage&);
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void deallocate_supervisor_physical_page(const PhysicalPage&);
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OwnPtr<Region> allocate_contiguous_kernel_region(size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
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OwnPtr<Region> allocate_kernel_region(size_t, const StringView& name, u8 access, bool user_accessible = false, bool should_commit = true, bool cacheable = true);
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OwnPtr<Region> allocate_kernel_region(PhysicalAddress, size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
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OwnPtr<Region> allocate_kernel_region_identity(PhysicalAddress, size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
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OwnPtr<Region> allocate_kernel_region_with_vmobject(VMObject&, size_t, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
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OwnPtr<Region> allocate_kernel_region_with_vmobject(const Range&, VMObject&, const StringView& name, u8 access, bool user_accessible = false, bool cacheable = true);
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OwnPtr<Region> allocate_user_accessible_kernel_region(size_t, const StringView& name, u8 access, bool cacheable = true);
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unsigned user_physical_pages() const { return m_user_physical_pages; }
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unsigned user_physical_pages_used() const { return m_user_physical_pages_used; }
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unsigned super_physical_pages() const { return m_super_physical_pages; }
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unsigned super_physical_pages_used() const { return m_super_physical_pages_used; }
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template<typename Callback>
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static void for_each_vmobject(Callback callback)
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{
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for (auto& vmobject : MM.m_vmobjects) {
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if (callback(vmobject) == IterationDecision::Break)
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break;
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}
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}
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template<typename T, typename Callback>
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static void for_each_vmobject_of_type(Callback callback)
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{
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for (auto& vmobject : MM.m_vmobjects) {
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if (!is<T>(vmobject))
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continue;
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if (callback(static_cast<T&>(vmobject)) == IterationDecision::Break)
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break;
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}
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}
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static Region* find_region_from_vaddr(Process&, VirtualAddress);
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static const Region* find_region_from_vaddr(const Process&, VirtualAddress);
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void dump_kernel_regions();
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PhysicalPage& shared_zero_page() { return *m_shared_zero_page; }
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PageDirectory& kernel_page_directory() { return *m_kernel_page_directory; }
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private:
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MemoryManager();
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~MemoryManager();
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enum class AccessSpace { Kernel,
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User };
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enum class AccessType { Read,
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Write };
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template<AccessSpace, AccessType>
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bool validate_range(const Process&, VirtualAddress, size_t) const;
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void register_vmobject(VMObject&);
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void unregister_vmobject(VMObject&);
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void register_region(Region&);
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void unregister_region(Region&);
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void detect_cpu_features();
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void protect_kernel_image();
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void parse_memory_map();
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static void flush_tlb_local(VirtualAddress, size_t page_count = 1);
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static void flush_tlb(VirtualAddress, size_t page_count = 1);
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static Region* user_region_from_vaddr(Process&, VirtualAddress);
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static Region* kernel_region_from_vaddr(VirtualAddress);
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static Region* find_region_from_vaddr(VirtualAddress);
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RefPtr<PhysicalPage> find_free_user_physical_page();
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u8* quickmap_page(PhysicalPage&);
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void unquickmap_page();
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PageDirectoryEntry* quickmap_pd(PageDirectory&, size_t pdpt_index);
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PageTableEntry* quickmap_pt(PhysicalAddress);
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PageTableEntry* pte(const PageDirectory&, VirtualAddress);
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PageTableEntry* ensure_pte(PageDirectory&, VirtualAddress);
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void release_pte(PageDirectory&, VirtualAddress, bool);
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RefPtr<PageDirectory> m_kernel_page_directory;
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RefPtr<PhysicalPage> m_low_page_table;
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RefPtr<PhysicalPage> m_shared_zero_page;
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unsigned m_user_physical_pages { 0 };
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unsigned m_user_physical_pages_used { 0 };
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unsigned m_super_physical_pages { 0 };
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unsigned m_super_physical_pages_used { 0 };
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NonnullRefPtrVector<PhysicalRegion> m_user_physical_regions;
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NonnullRefPtrVector<PhysicalRegion> m_super_physical_regions;
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InlineLinkedList<Region> m_user_regions;
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InlineLinkedList<Region> m_kernel_regions;
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InlineLinkedList<VMObject> m_vmobjects;
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RefPtr<PhysicalPage> m_low_pseudo_identity_mapping_pages[4];
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};
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template<typename Callback>
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void VMObject::for_each_region(Callback callback)
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{
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ScopedSpinLock lock(s_mm_lock);
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// FIXME: Figure out a better data structure so we don't have to walk every single region every time an inode changes.
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// Perhaps VMObject could have a Vector<Region*> with all of his mappers?
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for (auto& region : MM.m_user_regions) {
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if (®ion.vmobject() == this)
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callback(region);
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}
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for (auto& region : MM.m_kernel_regions) {
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if (®ion.vmobject() == this)
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callback(region);
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}
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}
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inline bool is_user_address(VirtualAddress vaddr)
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{
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return vaddr.get() < 0xc0000000;
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}
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inline bool is_user_range(VirtualAddress vaddr, size_t size)
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{
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if (vaddr.offset(size) < vaddr)
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return false;
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return is_user_address(vaddr) && is_user_address(vaddr.offset(size));
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}
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inline bool PhysicalPage::is_shared_zero_page() const
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{
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return this == &MM.shared_zero_page();
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}
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}
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