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File-backed memory differs from anonymous memory in that even if the pte is missing, the data could still resides either in the file or in page/swap cache. So when wr-protect a pte, we need to consider none ptes too. We do that by installing the uffd-wp pte markers when necessary. So when there's a future write to the pte, the fault handler will go the special path to first fault-in the page as read-only, then report to userfaultfd server with the wr-protect message. On the other hand, when unprotecting a page, it's also possible that the pte got unmapped but replaced by the special uffd-wp marker. Then we'll need to be able to recover from a uffd-wp pte marker into a none pte, so that the next access to the page will fault in correctly as usual when accessed the next time. Special care needs to be taken throughout the change_protection_range() process. Since now we allow user to wr-protect a none pte, we need to be able to pre-populate the page table entries if we see (!anonymous && MM_CP_UFFD_WP) requests, otherwise change_protection_range() will always skip when the pgtable entry does not exist. For example, the pgtable can be missing for a whole chunk of 2M pmd, but the page cache can exist for the 2M range. When we want to wr-protect one 4K page within the 2M pmd range, we need to pre-populate the pgtable and install the pte marker showing that we want to get a message and block the thread when the page cache of that 4K page is written. Without pre-populating the pmd, change_protection() will simply skip that whole pmd. Note that this patch only covers the small pages (pte level) but not covering any of the transparent huge pages yet. That will be done later, and this patch will be a preparation for it too. Link: https://lkml.kernel.org/r/20220405014850.14352-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Nadav Amit <nadav.amit@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
809 lines
21 KiB
C
809 lines
21 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/pagewalk.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 <linux/pgtable.h>
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#include <linux/sched/sysctl.h>
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#include <linux/userfaultfd_k.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 <asm/tlb.h>
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#include "internal.h"
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static unsigned long change_pte_range(struct mmu_gather *tlb,
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struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
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unsigned long end, pgprot_t newprot, unsigned long cp_flags)
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{
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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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bool dirty_accountable = cp_flags & MM_CP_DIRTY_ACCT;
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bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
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bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
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bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
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tlb_change_page_size(tlb, PAGE_SIZE);
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/*
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* Can be called with only the mmap_lock 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_lock 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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int nid;
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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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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_count(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_lru(page) && PageDirty(page))
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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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nid = page_to_nid(page);
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if (target_node == nid)
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continue;
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/*
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* Skip scanning top tier node if normal numa
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* balancing is disabled
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*/
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if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
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node_is_toptier(nid))
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continue;
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}
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oldpte = ptep_modify_prot_start(vma, addr, pte);
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ptent = pte_modify(oldpte, newprot);
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if (preserve_write)
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ptent = pte_mk_savedwrite(ptent);
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if (uffd_wp) {
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ptent = pte_wrprotect(ptent);
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ptent = pte_mkuffd_wp(ptent);
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} else if (uffd_wp_resolve) {
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/*
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* Leave the write bit to be handled
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* by PF interrupt handler, then
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* things like COW could be properly
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* handled.
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*/
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ptent = pte_clear_uffd_wp(ptent);
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}
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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(vma, addr, pte, oldpte, ptent);
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if (pte_needs_flush(oldpte, ptent))
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tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
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pages++;
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} else if (is_swap_pte(oldpte)) {
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swp_entry_t entry = pte_to_swp_entry(oldpte);
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struct page *page = pfn_swap_entry_to_page(entry);
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pte_t newpte;
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if (is_writable_migration_entry(entry)) {
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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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if (PageAnon(page))
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entry = make_readable_exclusive_migration_entry(
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swp_offset(entry));
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else
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entry = make_readable_migration_entry(swp_offset(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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if (pte_swp_uffd_wp(oldpte))
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newpte = pte_swp_mkuffd_wp(newpte);
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} else if (is_writable_device_private_entry(entry)) {
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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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entry = make_readable_device_private_entry(
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swp_offset(entry));
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newpte = swp_entry_to_pte(entry);
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if (pte_swp_uffd_wp(oldpte))
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newpte = pte_swp_mkuffd_wp(newpte);
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} else if (is_writable_device_exclusive_entry(entry)) {
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entry = make_readable_device_exclusive_entry(
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swp_offset(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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if (pte_swp_uffd_wp(oldpte))
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newpte = pte_swp_mkuffd_wp(newpte);
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} else if (pte_marker_entry_uffd_wp(entry)) {
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/*
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* If this is uffd-wp pte marker and we'd like
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* to unprotect it, drop it; the next page
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* fault will trigger without uffd trapping.
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*/
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if (uffd_wp_resolve) {
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pte_clear(vma->vm_mm, addr, pte);
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pages++;
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}
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continue;
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} else {
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newpte = oldpte;
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}
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if (uffd_wp)
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newpte = pte_swp_mkuffd_wp(newpte);
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else if (uffd_wp_resolve)
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newpte = pte_swp_clear_uffd_wp(newpte);
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if (!pte_same(oldpte, newpte)) {
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set_pte_at(vma->vm_mm, addr, pte, newpte);
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pages++;
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}
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} else {
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/* It must be an none page, or what else?.. */
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WARN_ON_ONCE(!pte_none(oldpte));
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if (unlikely(uffd_wp && !vma_is_anonymous(vma))) {
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/*
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* For file-backed mem, we need to be able to
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* wr-protect a none pte, because even if the
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* pte is none, the page/swap cache could
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* exist. Doing that by install a marker.
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*/
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set_pte_at(vma->vm_mm, addr, pte,
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make_pte_marker(PTE_MARKER_UFFD_WP));
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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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/*
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* Used when setting automatic NUMA hinting protection where it is
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* critical that a numa hinting PMD is not confused with a bad PMD.
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*/
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static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
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{
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pmd_t pmdval = pmd_read_atomic(pmd);
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/* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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barrier();
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#endif
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if (pmd_none(pmdval))
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return 1;
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if (pmd_trans_huge(pmdval))
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return 0;
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if (unlikely(pmd_bad(pmdval))) {
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pmd_clear_bad(pmd);
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return 1;
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}
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return 0;
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}
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/* Return true if we're uffd wr-protecting file-backed memory, or false */
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static inline bool
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uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags)
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{
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return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
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}
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/*
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* If wr-protecting the range for file-backed, populate pgtable for the case
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* when pgtable is empty but page cache exists. When {pte|pmd|...}_alloc()
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* failed it means no memory, we don't have a better option but stop.
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*/
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#define change_pmd_prepare(vma, pmd, cp_flags) \
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do { \
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if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
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if (WARN_ON_ONCE(pte_alloc(vma->vm_mm, pmd))) \
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break; \
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} \
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} while (0)
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/*
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* This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
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* have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
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* while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
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*/
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#define change_prepare(vma, high, low, addr, cp_flags) \
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do { \
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if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
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low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
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if (WARN_ON_ONCE(p == NULL)) \
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break; \
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} \
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} while (0)
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static inline unsigned long change_pmd_range(struct mmu_gather *tlb,
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struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
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unsigned long end, pgprot_t newprot, unsigned long cp_flags)
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{
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pmd_t *pmd;
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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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struct mmu_notifier_range range;
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range.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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change_pmd_prepare(vma, pmd, cp_flags);
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/*
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* Automatic NUMA balancing walks the tables with mmap_lock
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* held for read. It's possible a parallel update to occur
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* between pmd_trans_huge() and a pmd_none_or_clear_bad()
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* check leading to a false positive and clearing.
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* Hence, it's necessary to atomically read the PMD value
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* for all the checks.
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*/
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if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
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pmd_none_or_clear_bad_unless_trans_huge(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 (!range.start) {
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mmu_notifier_range_init(&range,
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MMU_NOTIFY_PROTECTION_VMA, 0,
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vma, vma->vm_mm, addr, end);
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mmu_notifier_invalidate_range_start(&range);
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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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/*
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* change_huge_pmd() does not defer TLB flushes,
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* so no need to propagate the tlb argument.
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*/
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int nr_ptes = change_huge_pmd(tlb, vma, pmd,
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addr, newprot, cp_flags);
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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(tlb, vma, pmd, addr, next,
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newprot, cp_flags);
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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 (range.start)
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mmu_notifier_invalidate_range_end(&range);
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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 mmu_gather *tlb,
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struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
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unsigned long end, pgprot_t newprot, unsigned long cp_flags)
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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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change_prepare(vma, pud, pmd, addr, cp_flags);
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if (pud_none_or_clear_bad(pud))
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continue;
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pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
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cp_flags);
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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 mmu_gather *tlb,
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struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
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unsigned long end, pgprot_t newprot, unsigned long cp_flags)
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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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change_prepare(vma, p4d, pud, addr, cp_flags);
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if (p4d_none_or_clear_bad(p4d))
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continue;
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pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
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cp_flags);
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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 mmu_gather *tlb,
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struct vm_area_struct *vma, unsigned long addr,
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unsigned long end, pgprot_t newprot, unsigned long cp_flags)
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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 pages = 0;
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BUG_ON(addr >= end);
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pgd = pgd_offset(mm, addr);
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tlb_start_vma(tlb, vma);
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do {
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next = pgd_addr_end(addr, end);
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change_prepare(vma, pgd, p4d, addr, cp_flags);
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if (pgd_none_or_clear_bad(pgd))
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|
continue;
|
|
pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
|
|
cp_flags);
|
|
} while (pgd++, addr = next, addr != end);
|
|
|
|
tlb_end_vma(tlb, vma);
|
|
|
|
return pages;
|
|
}
|
|
|
|
unsigned long change_protection(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, unsigned long start,
|
|
unsigned long end, pgprot_t newprot,
|
|
unsigned long cp_flags)
|
|
{
|
|
unsigned long pages;
|
|
|
|
BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
|
|
|
|
if (is_vm_hugetlb_page(vma))
|
|
pages = hugetlb_change_protection(vma, start, end, newprot);
|
|
else
|
|
pages = change_protection_range(tlb, vma, start, end, newprot,
|
|
cp_flags);
|
|
|
|
return pages;
|
|
}
|
|
|
|
static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
|
|
unsigned long next, struct mm_walk *walk)
|
|
{
|
|
return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
|
|
0 : -EACCES;
|
|
}
|
|
|
|
static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
|
|
unsigned long addr, unsigned long next,
|
|
struct mm_walk *walk)
|
|
{
|
|
return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
|
|
0 : -EACCES;
|
|
}
|
|
|
|
static int prot_none_test(unsigned long addr, unsigned long next,
|
|
struct mm_walk *walk)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static const struct mm_walk_ops prot_none_walk_ops = {
|
|
.pte_entry = prot_none_pte_entry,
|
|
.hugetlb_entry = prot_none_hugetlb_entry,
|
|
.test_walk = prot_none_test,
|
|
};
|
|
|
|
int
|
|
mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
struct vm_area_struct **pprev, unsigned long start,
|
|
unsigned long end, unsigned long newflags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long oldflags = vma->vm_flags;
|
|
long nrpages = (end - start) >> PAGE_SHIFT;
|
|
unsigned long charged = 0;
|
|
pgoff_t pgoff;
|
|
int error;
|
|
int dirty_accountable = 0;
|
|
|
|
if (newflags == oldflags) {
|
|
*pprev = vma;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Do PROT_NONE PFN permission checks here when we can still
|
|
* bail out without undoing a lot of state. This is a rather
|
|
* uncommon case, so doesn't need to be very optimized.
|
|
*/
|
|
if (arch_has_pfn_modify_check() &&
|
|
(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
|
|
(newflags & VM_ACCESS_FLAGS) == 0) {
|
|
pgprot_t new_pgprot = vm_get_page_prot(newflags);
|
|
|
|
error = walk_page_range(current->mm, start, end,
|
|
&prot_none_walk_ops, &new_pgprot);
|
|
if (error)
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* If we make a private mapping writable we increase our commit;
|
|
* but (without finer accounting) cannot reduce our commit if we
|
|
* make it unwritable again. hugetlb mapping were accounted for
|
|
* even if read-only so there is no need to account for them here
|
|
*/
|
|
if (newflags & VM_WRITE) {
|
|
/* Check space limits when area turns into data. */
|
|
if (!may_expand_vm(mm, newflags, nrpages) &&
|
|
may_expand_vm(mm, oldflags, nrpages))
|
|
return -ENOMEM;
|
|
if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
|
|
VM_SHARED|VM_NORESERVE))) {
|
|
charged = nrpages;
|
|
if (security_vm_enough_memory_mm(mm, charged))
|
|
return -ENOMEM;
|
|
newflags |= VM_ACCOUNT;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* First try to merge with previous and/or next vma.
|
|
*/
|
|
pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
|
|
*pprev = vma_merge(mm, *pprev, start, end, newflags,
|
|
vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
|
|
vma->vm_userfaultfd_ctx, anon_vma_name(vma));
|
|
if (*pprev) {
|
|
vma = *pprev;
|
|
VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
|
|
goto success;
|
|
}
|
|
|
|
*pprev = vma;
|
|
|
|
if (start != vma->vm_start) {
|
|
error = split_vma(mm, vma, start, 1);
|
|
if (error)
|
|
goto fail;
|
|
}
|
|
|
|
if (end != vma->vm_end) {
|
|
error = split_vma(mm, vma, end, 0);
|
|
if (error)
|
|
goto fail;
|
|
}
|
|
|
|
success:
|
|
/*
|
|
* vm_flags and vm_page_prot are protected by the mmap_lock
|
|
* held in write mode.
|
|
*/
|
|
vma->vm_flags = newflags;
|
|
dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
|
|
vma_set_page_prot(vma);
|
|
|
|
change_protection(tlb, vma, start, end, vma->vm_page_prot,
|
|
dirty_accountable ? MM_CP_DIRTY_ACCT : 0);
|
|
|
|
/*
|
|
* Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
|
|
* fault on access.
|
|
*/
|
|
if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
|
|
(newflags & VM_WRITE)) {
|
|
populate_vma_page_range(vma, start, end, NULL);
|
|
}
|
|
|
|
vm_stat_account(mm, oldflags, -nrpages);
|
|
vm_stat_account(mm, newflags, nrpages);
|
|
perf_event_mmap(vma);
|
|
return 0;
|
|
|
|
fail:
|
|
vm_unacct_memory(charged);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* pkey==-1 when doing a legacy mprotect()
|
|
*/
|
|
static int do_mprotect_pkey(unsigned long start, size_t len,
|
|
unsigned long prot, int pkey)
|
|
{
|
|
unsigned long nstart, end, tmp, reqprot;
|
|
struct vm_area_struct *vma, *prev;
|
|
int error = -EINVAL;
|
|
const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
|
|
const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
|
|
(prot & PROT_READ);
|
|
struct mmu_gather tlb;
|
|
|
|
start = untagged_addr(start);
|
|
|
|
prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
|
|
if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
|
|
return -EINVAL;
|
|
|
|
if (start & ~PAGE_MASK)
|
|
return -EINVAL;
|
|
if (!len)
|
|
return 0;
|
|
len = PAGE_ALIGN(len);
|
|
end = start + len;
|
|
if (end <= start)
|
|
return -ENOMEM;
|
|
if (!arch_validate_prot(prot, start))
|
|
return -EINVAL;
|
|
|
|
reqprot = prot;
|
|
|
|
if (mmap_write_lock_killable(current->mm))
|
|
return -EINTR;
|
|
|
|
/*
|
|
* If userspace did not allocate the pkey, do not let
|
|
* them use it here.
|
|
*/
|
|
error = -EINVAL;
|
|
if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
|
|
goto out;
|
|
|
|
vma = find_vma(current->mm, start);
|
|
error = -ENOMEM;
|
|
if (!vma)
|
|
goto out;
|
|
|
|
if (unlikely(grows & PROT_GROWSDOWN)) {
|
|
if (vma->vm_start >= end)
|
|
goto out;
|
|
start = vma->vm_start;
|
|
error = -EINVAL;
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
goto out;
|
|
} else {
|
|
if (vma->vm_start > start)
|
|
goto out;
|
|
if (unlikely(grows & PROT_GROWSUP)) {
|
|
end = vma->vm_end;
|
|
error = -EINVAL;
|
|
if (!(vma->vm_flags & VM_GROWSUP))
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
if (start > vma->vm_start)
|
|
prev = vma;
|
|
else
|
|
prev = vma->vm_prev;
|
|
|
|
tlb_gather_mmu(&tlb, current->mm);
|
|
for (nstart = start ; ; ) {
|
|
unsigned long mask_off_old_flags;
|
|
unsigned long newflags;
|
|
int new_vma_pkey;
|
|
|
|
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
|
|
|
|
/* Does the application expect PROT_READ to imply PROT_EXEC */
|
|
if (rier && (vma->vm_flags & VM_MAYEXEC))
|
|
prot |= PROT_EXEC;
|
|
|
|
/*
|
|
* Each mprotect() call explicitly passes r/w/x permissions.
|
|
* If a permission is not passed to mprotect(), it must be
|
|
* cleared from the VMA.
|
|
*/
|
|
mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
|
|
VM_FLAGS_CLEAR;
|
|
|
|
new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
|
|
newflags = calc_vm_prot_bits(prot, new_vma_pkey);
|
|
newflags |= (vma->vm_flags & ~mask_off_old_flags);
|
|
|
|
/* newflags >> 4 shift VM_MAY% in place of VM_% */
|
|
if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
|
|
error = -EACCES;
|
|
break;
|
|
}
|
|
|
|
/* Allow architectures to sanity-check the new flags */
|
|
if (!arch_validate_flags(newflags)) {
|
|
error = -EINVAL;
|
|
break;
|
|
}
|
|
|
|
error = security_file_mprotect(vma, reqprot, prot);
|
|
if (error)
|
|
break;
|
|
|
|
tmp = vma->vm_end;
|
|
if (tmp > end)
|
|
tmp = end;
|
|
|
|
if (vma->vm_ops && vma->vm_ops->mprotect) {
|
|
error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
|
|
if (error)
|
|
break;
|
|
}
|
|
|
|
error = mprotect_fixup(&tlb, vma, &prev, nstart, tmp, newflags);
|
|
if (error)
|
|
break;
|
|
|
|
nstart = tmp;
|
|
|
|
if (nstart < prev->vm_end)
|
|
nstart = prev->vm_end;
|
|
if (nstart >= end)
|
|
break;
|
|
|
|
vma = prev->vm_next;
|
|
if (!vma || vma->vm_start != nstart) {
|
|
error = -ENOMEM;
|
|
break;
|
|
}
|
|
prot = reqprot;
|
|
}
|
|
tlb_finish_mmu(&tlb);
|
|
out:
|
|
mmap_write_unlock(current->mm);
|
|
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;
|
|
|
|
mmap_write_lock(current->mm);
|
|
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:
|
|
mmap_write_unlock(current->mm);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(pkey_free, int, pkey)
|
|
{
|
|
int ret;
|
|
|
|
mmap_write_lock(current->mm);
|
|
ret = mm_pkey_free(current->mm, pkey);
|
|
mmap_write_unlock(current->mm);
|
|
|
|
/*
|
|
* We could provide warnings or errors if any VMA still
|
|
* has the pkey set here.
|
|
*/
|
|
return ret;
|
|
}
|
|
|
|
#endif /* CONFIG_ARCH_HAS_PKEYS */
|