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6a56ccbcf6
commitb191f9b106
("mm: numa: preserve PTE write permissions across a NUMA hinting fault") added remembering write permissions using ordinary pte_write() for PROT_NONE mapped pages to avoid write faults when remapping the page !PROT_NONE on NUMA hinting faults. That commit noted: The patch looks hacky but the alternatives looked worse. The tidest was to rewalk the page tables after a hinting fault but it was more complex than this approach and the performance was worse. It's not generally safe to just mark the page writable during the fault if it's a write fault as it may have been read-only for COW so that approach was discarded. Later, commit288bc54949
("mm/autonuma: let architecture override how the write bit should be stashed in a protnone pte.") introduced a family of savedwrite PTE functions that didn't necessarily improve the whole situation. One confusing thing is that nowadays, if a page is pte_protnone() and pte_savedwrite() then also pte_write() is true. Another source of confusion is that there is only a single pte_mk_savedwrite() call in the kernel. All other write-protection code seems to silently rely on pte_wrprotect(). Ever since PageAnonExclusive was introduced and we started using it in mprotect context via commit64fe24a3e0
("mm/mprotect: try avoiding write faults for exclusive anonymous pages when changing protection"), we do have machinery in place to avoid write faults when changing protection, which is exactly what we want to do here. Let's similarly do what ordinary mprotect() does nowadays when upgrading write permissions and reuse can_change_pte_writable() and can_change_pmd_writable() to detect if we can upgrade PTE permissions to be writable. For anonymous pages there should be absolutely no change: if an anonymous page is not exclusive, it could not have been mapped writable -- because only exclusive anonymous pages can be mapped writable. However, there *might* be a change for writable shared mappings that require writenotify: if they are not dirty, we cannot map them writable. While it might not matter in practice, we'd need a different way to identify whether writenotify is actually required -- and ordinary mprotect would benefit from that as well. Note that we don't optimize for the actual migration case: (1) When migration succeeds the new PTE will not be writable because the source PTE was not writable (protnone); in the future we might just optimize that case similarly by reusing can_change_pte_writable()/can_change_pmd_writable() when removing migration PTEs. (2) When migration fails, we'd have to recalculate the "writable" flag because we temporarily dropped the PT lock; for now keep it simple and set "writable=false". We'll remove all savedwrite leftovers next. Link: https://lkml.kernel.org/r/20221108174652.198904-6-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Hugh Dickins <hughd@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nadav Amit <namit@vmware.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
869 lines
22 KiB
C
869 lines
22 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 <linux/memory-tiers.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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bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
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pte_t pte)
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{
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struct page *page;
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if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
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return false;
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/* Don't touch entries that are not even readable. */
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if (pte_protnone(pte))
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return false;
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/* Do we need write faults for softdirty tracking? */
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if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
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return false;
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/* Do we need write faults for uffd-wp tracking? */
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if (userfaultfd_pte_wp(vma, pte))
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return false;
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if (!(vma->vm_flags & VM_SHARED)) {
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/*
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* Writable MAP_PRIVATE mapping: We can only special-case on
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* exclusive anonymous pages, because we know that our
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* write-fault handler similarly would map them writable without
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* any additional checks while holding the PT lock.
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*/
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page = vm_normal_page(vma, addr, pte);
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return page && PageAnon(page) && PageAnonExclusive(page);
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}
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/*
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* Writable MAP_SHARED mapping: "clean" might indicate that the FS still
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* needs a real write-fault for writenotify
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* (see vma_wants_writenotify()). If "dirty", the assumption is that the
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* FS was already notified and we can simply mark the PTE writable
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* just like the write-fault handler would do.
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*/
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return pte_dirty(pte);
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}
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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 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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/*
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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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bool toptier;
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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 || is_zone_device_page(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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toptier = node_is_toptier(nid);
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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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toptier)
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continue;
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if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
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!toptier)
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xchg_page_access_time(page,
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jiffies_to_msecs(jiffies));
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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 (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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ptent = pte_clear_uffd_wp(ptent);
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}
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/*
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* In some writable, shared mappings, we might want
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* to catch actual write access -- see
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* vma_wants_writenotify().
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*
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* In all writable, private mappings, we have to
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* properly handle COW.
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*
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* In both cases, we can sometimes still change PTEs
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* writable and avoid the write-fault handler, for
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* example, if a PTE is already dirty and no other
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* COW or special handling is required.
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*/
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if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
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!pte_write(ptent) &&
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can_change_pte_writable(vma, addr, ptent))
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ptent = pte_mkwrite(ptent);
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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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pte_t newpte;
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if (is_writable_migration_entry(entry)) {
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struct page *page = pfn_swap_entry_to_page(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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uffd_wp_protect_file(vma, cp_flags)) {
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__split_huge_pmd(vma, pmd, addr, false, NULL);
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/*
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* For file-backed, the pmd could have been
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* cleared; make sure pmd populated if
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* necessary, then fall-through to pte level.
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*/
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change_pmd_prepare(vma, pmd, cp_flags);
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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);
|
|
|
|
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;
|
|
next:
|
|
cond_resched();
|
|
} while (pmd++, addr = next, addr != end);
|
|
|
|
if (range.start)
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
if (nr_huge_updates)
|
|
count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
|
|
return pages;
|
|
}
|
|
|
|
static inline unsigned long change_pud_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
|
|
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
unsigned long pages = 0;
|
|
|
|
pud = pud_offset(p4d, addr);
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
change_prepare(vma, pud, pmd, addr, cp_flags);
|
|
if (pud_none_or_clear_bad(pud))
|
|
continue;
|
|
pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
|
|
cp_flags);
|
|
} while (pud++, addr = next, addr != end);
|
|
|
|
return pages;
|
|
}
|
|
|
|
static inline unsigned long change_p4d_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
|
|
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
|
|
{
|
|
p4d_t *p4d;
|
|
unsigned long next;
|
|
unsigned long pages = 0;
|
|
|
|
p4d = p4d_offset(pgd, addr);
|
|
do {
|
|
next = p4d_addr_end(addr, end);
|
|
change_prepare(vma, p4d, pud, addr, cp_flags);
|
|
if (p4d_none_or_clear_bad(p4d))
|
|
continue;
|
|
pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
|
|
cp_flags);
|
|
} while (p4d++, addr = next, addr != end);
|
|
|
|
return pages;
|
|
}
|
|
|
|
static unsigned long change_protection_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, unsigned long addr,
|
|
unsigned long end, pgprot_t newprot, unsigned long cp_flags)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgd_t *pgd;
|
|
unsigned long next;
|
|
unsigned long pages = 0;
|
|
|
|
BUG_ON(addr >= end);
|
|
pgd = pgd_offset(mm, addr);
|
|
tlb_start_vma(tlb, vma);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
change_prepare(vma, pgd, p4d, addr, cp_flags);
|
|
if (pgd_none_or_clear_bad(pgd))
|
|
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,
|
|
cp_flags);
|
|
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 int mm_cp_flags = 0;
|
|
unsigned long charged = 0;
|
|
pgoff_t pgoff;
|
|
int error;
|
|
|
|
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;
|
|
if (vma_wants_manual_pte_write_upgrade(vma))
|
|
mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
|
|
vma_set_page_prot(vma);
|
|
|
|
change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags);
|
|
|
|
/*
|
|
* 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;
|
|
const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
|
|
const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
|
|
(prot & PROT_READ);
|
|
struct mmu_gather tlb;
|
|
MA_STATE(mas, ¤t->mm->mm_mt, 0, 0);
|
|
|
|
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;
|
|
|
|
mas_set(&mas, start);
|
|
vma = mas_find(&mas, ULONG_MAX);
|
|
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 = mas_prev(&mas, 0);
|
|
|
|
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_ACCESS_FLAGS | 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 = find_vma(current->mm, prev->vm_end);
|
|
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 */
|