588 lines
14 KiB
C
588 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* mm/mprotect.c
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*
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* (C) Copyright 1994 Linus Torvalds
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* (C) Copyright 2002 Christoph Hellwig
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*
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* Address space accounting code <alan@lxorguk.ukuu.org.uk>
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* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
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*/
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/shm.h>
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#include <linux/mman.h>
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#include <linux/fs.h>
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#include <linux/highmem.h>
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#include <linux/security.h>
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#include <linux/mempolicy.h>
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#include <linux/personality.h>
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#include <linux/syscalls.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/mmu_notifier.h>
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#include <linux/migrate.h>
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#include <linux/perf_event.h>
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#include <linux/pkeys.h>
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#include <linux/ksm.h>
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#include <linux/uaccess.h>
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#include <linux/mm_inline.h>
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#include <asm/pgtable.h>
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#include <asm/cacheflush.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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#include "internal.h"
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static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end, pgprot_t newprot,
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int dirty_accountable, int prot_numa)
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{
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struct mm_struct *mm = vma->vm_mm;
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pte_t *pte, oldpte;
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spinlock_t *ptl;
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unsigned long pages = 0;
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int target_node = NUMA_NO_NODE;
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/*
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* Can be called with only the mmap_sem for reading by
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* prot_numa so we must check the pmd isn't constantly
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* changing from under us from pmd_none to pmd_trans_huge
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* and/or the other way around.
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*/
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if (pmd_trans_unstable(pmd))
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return 0;
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/*
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* The pmd points to a regular pte so the pmd can't change
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* from under us even if the mmap_sem is only hold for
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* reading.
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*/
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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/* Get target node for single threaded private VMAs */
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if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
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atomic_read(&vma->vm_mm->mm_users) == 1)
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target_node = numa_node_id();
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flush_tlb_batched_pending(vma->vm_mm);
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arch_enter_lazy_mmu_mode();
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do {
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oldpte = *pte;
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if (pte_present(oldpte)) {
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pte_t ptent;
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bool preserve_write = prot_numa && pte_write(oldpte);
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/*
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* Avoid trapping faults against the zero or KSM
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* pages. See similar comment in change_huge_pmd.
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*/
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if (prot_numa) {
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struct page *page;
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page = vm_normal_page(vma, addr, oldpte);
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if (!page || PageKsm(page))
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continue;
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/* Also skip shared copy-on-write pages */
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if (is_cow_mapping(vma->vm_flags) &&
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page_mapcount(page) != 1)
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continue;
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/*
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* While migration can move some dirty pages,
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* it cannot move them all from MIGRATE_ASYNC
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* context.
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*/
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if (page_is_file_cache(page) && PageDirty(page))
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continue;
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/* Avoid TLB flush if possible */
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if (pte_protnone(oldpte))
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continue;
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/*
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* Don't mess with PTEs if page is already on the node
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* a single-threaded process is running on.
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*/
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if (target_node == page_to_nid(page))
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continue;
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}
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ptent = ptep_modify_prot_start(mm, addr, pte);
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ptent = pte_modify(ptent, newprot);
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if (preserve_write)
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ptent = pte_mk_savedwrite(ptent);
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/* Avoid taking write faults for known dirty pages */
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if (dirty_accountable && pte_dirty(ptent) &&
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(pte_soft_dirty(ptent) ||
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!(vma->vm_flags & VM_SOFTDIRTY))) {
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ptent = pte_mkwrite(ptent);
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}
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ptep_modify_prot_commit(mm, addr, pte, ptent);
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pages++;
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} else if (IS_ENABLED(CONFIG_MIGRATION)) {
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swp_entry_t entry = pte_to_swp_entry(oldpte);
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if (is_write_migration_entry(entry)) {
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pte_t newpte;
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/*
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* A protection check is difficult so
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* just be safe and disable write
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*/
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make_migration_entry_read(&entry);
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newpte = swp_entry_to_pte(entry);
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if (pte_swp_soft_dirty(oldpte))
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newpte = pte_swp_mksoft_dirty(newpte);
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set_pte_at(mm, addr, pte, newpte);
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pages++;
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}
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if (is_write_device_private_entry(entry)) {
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pte_t newpte;
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/*
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* We do not preserve soft-dirtiness. See
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* copy_one_pte() for explanation.
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*/
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make_device_private_entry_read(&entry);
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newpte = swp_entry_to_pte(entry);
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set_pte_at(mm, addr, pte, newpte);
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pages++;
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}
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}
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} while (pte++, addr += PAGE_SIZE, addr != end);
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arch_leave_lazy_mmu_mode();
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pte_unmap_unlock(pte - 1, ptl);
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return pages;
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}
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static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
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pud_t *pud, unsigned long addr, unsigned long end,
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pgprot_t newprot, int dirty_accountable, int prot_numa)
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{
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pmd_t *pmd;
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struct mm_struct *mm = vma->vm_mm;
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unsigned long next;
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unsigned long pages = 0;
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unsigned long nr_huge_updates = 0;
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unsigned long mni_start = 0;
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pmd = pmd_offset(pud, addr);
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do {
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unsigned long this_pages;
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next = pmd_addr_end(addr, end);
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if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
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&& pmd_none_or_clear_bad(pmd))
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goto next;
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/* invoke the mmu notifier if the pmd is populated */
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if (!mni_start) {
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mni_start = addr;
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mmu_notifier_invalidate_range_start(mm, mni_start, end);
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}
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if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
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if (next - addr != HPAGE_PMD_SIZE) {
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__split_huge_pmd(vma, pmd, addr, false, NULL);
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} else {
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int nr_ptes = change_huge_pmd(vma, pmd, addr,
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newprot, prot_numa);
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if (nr_ptes) {
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if (nr_ptes == HPAGE_PMD_NR) {
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pages += HPAGE_PMD_NR;
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nr_huge_updates++;
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}
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/* huge pmd was handled */
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goto next;
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}
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}
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/* fall through, the trans huge pmd just split */
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}
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this_pages = change_pte_range(vma, pmd, addr, next, newprot,
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dirty_accountable, prot_numa);
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pages += this_pages;
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next:
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cond_resched();
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} while (pmd++, addr = next, addr != end);
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if (mni_start)
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mmu_notifier_invalidate_range_end(mm, mni_start, end);
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if (nr_huge_updates)
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count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
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return pages;
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}
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static inline unsigned long change_pud_range(struct vm_area_struct *vma,
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p4d_t *p4d, unsigned long addr, unsigned long end,
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pgprot_t newprot, int dirty_accountable, int prot_numa)
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{
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pud_t *pud;
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unsigned long next;
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unsigned long pages = 0;
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pud = pud_offset(p4d, addr);
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do {
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next = pud_addr_end(addr, end);
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if (pud_none_or_clear_bad(pud))
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continue;
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pages += change_pmd_range(vma, pud, addr, next, newprot,
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dirty_accountable, prot_numa);
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} while (pud++, addr = next, addr != end);
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return pages;
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}
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static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
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pgd_t *pgd, unsigned long addr, unsigned long end,
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pgprot_t newprot, int dirty_accountable, int prot_numa)
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{
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p4d_t *p4d;
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unsigned long next;
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unsigned long pages = 0;
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p4d = p4d_offset(pgd, addr);
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do {
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next = p4d_addr_end(addr, end);
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if (p4d_none_or_clear_bad(p4d))
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continue;
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pages += change_pud_range(vma, p4d, addr, next, newprot,
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dirty_accountable, prot_numa);
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} while (p4d++, addr = next, addr != end);
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return pages;
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}
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static unsigned long change_protection_range(struct vm_area_struct *vma,
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unsigned long addr, unsigned long end, pgprot_t newprot,
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int dirty_accountable, int prot_numa)
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{
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struct mm_struct *mm = vma->vm_mm;
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pgd_t *pgd;
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unsigned long next;
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unsigned long start = addr;
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unsigned long pages = 0;
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BUG_ON(addr >= end);
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pgd = pgd_offset(mm, addr);
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flush_cache_range(vma, addr, end);
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inc_tlb_flush_pending(mm);
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do {
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next = pgd_addr_end(addr, end);
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if (pgd_none_or_clear_bad(pgd))
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continue;
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pages += change_p4d_range(vma, pgd, addr, next, newprot,
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dirty_accountable, prot_numa);
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} while (pgd++, addr = next, addr != end);
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/* Only flush the TLB if we actually modified any entries: */
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if (pages)
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flush_tlb_range(vma, start, end);
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dec_tlb_flush_pending(mm);
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return pages;
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}
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unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
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unsigned long end, pgprot_t newprot,
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int dirty_accountable, int prot_numa)
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{
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unsigned long pages;
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if (is_vm_hugetlb_page(vma))
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pages = hugetlb_change_protection(vma, start, end, newprot);
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else
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pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
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return pages;
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}
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int
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mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
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unsigned long start, unsigned long end, unsigned long newflags)
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{
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struct mm_struct *mm = vma->vm_mm;
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unsigned long oldflags = vma->vm_flags;
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long nrpages = (end - start) >> PAGE_SHIFT;
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unsigned long charged = 0;
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pgoff_t pgoff;
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int error;
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int dirty_accountable = 0;
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if (newflags == oldflags) {
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*pprev = vma;
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return 0;
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}
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/*
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* If we make a private mapping writable we increase our commit;
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* but (without finer accounting) cannot reduce our commit if we
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* make it unwritable again. hugetlb mapping were accounted for
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* even if read-only so there is no need to account for them here
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*/
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if (newflags & VM_WRITE) {
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/* Check space limits when area turns into data. */
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if (!may_expand_vm(mm, newflags, nrpages) &&
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may_expand_vm(mm, oldflags, nrpages))
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return -ENOMEM;
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if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
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VM_SHARED|VM_NORESERVE))) {
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charged = nrpages;
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if (security_vm_enough_memory_mm(mm, charged))
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return -ENOMEM;
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newflags |= VM_ACCOUNT;
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}
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}
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/*
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* First try to merge with previous and/or next vma.
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*/
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pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
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*pprev = vma_merge(mm, *pprev, start, end, newflags,
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vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
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vma->vm_userfaultfd_ctx);
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if (*pprev) {
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vma = *pprev;
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VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
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goto success;
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}
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*pprev = vma;
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if (start != vma->vm_start) {
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error = split_vma(mm, vma, start, 1);
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if (error)
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goto fail;
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}
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if (end != vma->vm_end) {
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error = split_vma(mm, vma, end, 0);
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if (error)
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goto fail;
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}
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success:
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/*
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* vm_flags and vm_page_prot are protected by the mmap_sem
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* held in write mode.
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*/
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vma->vm_flags = newflags;
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dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
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vma_set_page_prot(vma);
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change_protection(vma, start, end, vma->vm_page_prot,
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dirty_accountable, 0);
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/*
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* Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
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* fault on access.
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*/
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if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
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(newflags & VM_WRITE)) {
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populate_vma_page_range(vma, start, end, NULL);
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}
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vm_stat_account(mm, oldflags, -nrpages);
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vm_stat_account(mm, newflags, nrpages);
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perf_event_mmap(vma);
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return 0;
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fail:
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vm_unacct_memory(charged);
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return error;
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}
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/*
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* pkey==-1 when doing a legacy mprotect()
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*/
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static int do_mprotect_pkey(unsigned long start, size_t len,
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unsigned long prot, int pkey)
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{
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unsigned long nstart, end, tmp, reqprot;
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struct vm_area_struct *vma, *prev;
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int error = -EINVAL;
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const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
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const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
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(prot & PROT_READ);
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prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
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if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
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return -EINVAL;
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if (start & ~PAGE_MASK)
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return -EINVAL;
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if (!len)
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return 0;
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len = PAGE_ALIGN(len);
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end = start + len;
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if (end <= start)
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return -ENOMEM;
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if (!arch_validate_prot(prot, start))
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return -EINVAL;
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reqprot = prot;
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if (down_write_killable(¤t->mm->mmap_sem))
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return -EINTR;
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/*
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* If userspace did not allocate the pkey, do not let
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* them use it here.
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*/
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error = -EINVAL;
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if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
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goto out;
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vma = find_vma(current->mm, start);
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error = -ENOMEM;
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if (!vma)
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goto out;
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prev = vma->vm_prev;
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if (unlikely(grows & PROT_GROWSDOWN)) {
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if (vma->vm_start >= end)
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goto out;
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start = vma->vm_start;
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error = -EINVAL;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto out;
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} else {
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if (vma->vm_start > start)
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goto out;
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if (unlikely(grows & PROT_GROWSUP)) {
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end = vma->vm_end;
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error = -EINVAL;
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if (!(vma->vm_flags & VM_GROWSUP))
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goto out;
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}
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}
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if (start > vma->vm_start)
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prev = vma;
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for (nstart = start ; ; ) {
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unsigned long mask_off_old_flags;
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unsigned long newflags;
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int new_vma_pkey;
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/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
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/* Does the application expect PROT_READ to imply PROT_EXEC */
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if (rier && (vma->vm_flags & VM_MAYEXEC))
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prot |= PROT_EXEC;
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/*
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* Each mprotect() call explicitly passes r/w/x permissions.
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* If a permission is not passed to mprotect(), it must be
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* cleared from the VMA.
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*/
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mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
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VM_FLAGS_CLEAR;
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new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
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newflags = calc_vm_prot_bits(prot, new_vma_pkey);
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newflags |= (vma->vm_flags & ~mask_off_old_flags);
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/* newflags >> 4 shift VM_MAY% in place of VM_% */
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if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
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error = -EACCES;
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goto out;
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}
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error = security_file_mprotect(vma, reqprot, prot);
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if (error)
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goto out;
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tmp = vma->vm_end;
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if (tmp > end)
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tmp = end;
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error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
|
|
if (error)
|
|
goto out;
|
|
nstart = tmp;
|
|
|
|
if (nstart < prev->vm_end)
|
|
nstart = prev->vm_end;
|
|
if (nstart >= end)
|
|
goto out;
|
|
|
|
vma = prev->vm_next;
|
|
if (!vma || vma->vm_start != nstart) {
|
|
error = -ENOMEM;
|
|
goto out;
|
|
}
|
|
prot = reqprot;
|
|
}
|
|
out:
|
|
up_write(¤t->mm->mmap_sem);
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
|
|
unsigned long, prot)
|
|
{
|
|
return do_mprotect_pkey(start, len, prot, -1);
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_HAS_PKEYS
|
|
|
|
SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
|
|
unsigned long, prot, int, pkey)
|
|
{
|
|
return do_mprotect_pkey(start, len, prot, pkey);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
|
|
{
|
|
int pkey;
|
|
int ret;
|
|
|
|
/* No flags supported yet. */
|
|
if (flags)
|
|
return -EINVAL;
|
|
/* check for unsupported init values */
|
|
if (init_val & ~PKEY_ACCESS_MASK)
|
|
return -EINVAL;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
pkey = mm_pkey_alloc(current->mm);
|
|
|
|
ret = -ENOSPC;
|
|
if (pkey == -1)
|
|
goto out;
|
|
|
|
ret = arch_set_user_pkey_access(current, pkey, init_val);
|
|
if (ret) {
|
|
mm_pkey_free(current->mm, pkey);
|
|
goto out;
|
|
}
|
|
ret = pkey;
|
|
out:
|
|
up_write(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(pkey_free, int, pkey)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = mm_pkey_free(current->mm, pkey);
|
|
up_write(¤t->mm->mmap_sem);
|
|
|
|
/*
|
|
* We could provie warnings or errors if any VMA still
|
|
* has the pkey set here.
|
|
*/
|
|
return ret;
|
|
}
|
|
|
|
#endif /* CONFIG_ARCH_HAS_PKEYS */
|