| /* |
| * mm/mprotect.c |
| * |
| * (C) Copyright 1994 Linus Torvalds |
| * (C) Copyright 2002 Christoph Hellwig |
| * |
| * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
| * (C) Copyright 2002 Red Hat Inc, All Rights Reserved |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/hugetlb.h> |
| #include <linux/shm.h> |
| #include <linux/mman.h> |
| #include <linux/fs.h> |
| #include <linux/highmem.h> |
| #include <linux/security.h> |
| #include <linux/mempolicy.h> |
| #include <linux/personality.h> |
| #include <linux/syscalls.h> |
| #include <linux/swap.h> |
| #include <linux/swapops.h> |
| #include <linux/mmu_notifier.h> |
| #include <linux/migrate.h> |
| #include <linux/perf_event.h> |
| #include <linux/pkeys.h> |
| #include <linux/ksm.h> |
| #include <asm/uaccess.h> |
| #include <asm/pgtable.h> |
| #include <asm/cacheflush.h> |
| #include <asm/mmu_context.h> |
| #include <asm/tlbflush.h> |
| |
| #include "internal.h" |
| |
| /* |
| * For a prot_numa update we only hold mmap_sem for read so there is a |
| * potential race with faulting where a pmd was temporarily none. This |
| * function checks for a transhuge pmd under the appropriate lock. It |
| * returns a pte if it was successfully locked or NULL if it raced with |
| * a transhuge insertion. |
| */ |
| static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, int prot_numa, spinlock_t **ptl) |
| { |
| pte_t *pte; |
| spinlock_t *pmdl; |
| |
| /* !prot_numa is protected by mmap_sem held for write */ |
| if (!prot_numa) |
| return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl); |
| |
| pmdl = pmd_lock(vma->vm_mm, pmd); |
| if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) { |
| spin_unlock(pmdl); |
| return NULL; |
| } |
| |
| pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl); |
| spin_unlock(pmdl); |
| return pte; |
| } |
| |
| static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, pgprot_t newprot, |
| int dirty_accountable, int prot_numa) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pte_t *pte, oldpte; |
| spinlock_t *ptl; |
| unsigned long pages = 0; |
| |
| pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl); |
| if (!pte) |
| return 0; |
| |
| flush_tlb_batched_pending(vma->vm_mm); |
| arch_enter_lazy_mmu_mode(); |
| do { |
| oldpte = *pte; |
| if (pte_present(oldpte)) { |
| pte_t ptent; |
| bool preserve_write = prot_numa && pte_write(oldpte); |
| |
| /* |
| * Avoid trapping faults against the zero or KSM |
| * pages. See similar comment in change_huge_pmd. |
| */ |
| if (prot_numa) { |
| struct page *page; |
| |
| page = vm_normal_page(vma, addr, oldpte); |
| if (!page || PageKsm(page)) |
| continue; |
| |
| /* Avoid TLB flush if possible */ |
| if (pte_protnone(oldpte)) |
| continue; |
| } |
| |
| ptent = ptep_modify_prot_start(mm, addr, pte); |
| ptent = pte_modify(ptent, newprot); |
| if (preserve_write) |
| ptent = pte_mkwrite(ptent); |
| |
| /* Avoid taking write faults for known dirty pages */ |
| if (dirty_accountable && pte_dirty(ptent) && |
| (pte_soft_dirty(ptent) || |
| !(vma->vm_flags & VM_SOFTDIRTY))) { |
| ptent = pte_mkwrite(ptent); |
| } |
| ptep_modify_prot_commit(mm, addr, pte, ptent); |
| pages++; |
| } else if (IS_ENABLED(CONFIG_MIGRATION)) { |
| swp_entry_t entry = pte_to_swp_entry(oldpte); |
| |
| if (is_write_migration_entry(entry)) { |
| pte_t newpte; |
| /* |
| * A protection check is difficult so |
| * just be safe and disable write |
| */ |
| make_migration_entry_read(&entry); |
| newpte = swp_entry_to_pte(entry); |
| if (pte_swp_soft_dirty(oldpte)) |
| newpte = pte_swp_mksoft_dirty(newpte); |
| set_pte_at(mm, addr, pte, newpte); |
| |
| pages++; |
| } |
| } |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(pte - 1, ptl); |
| |
| return pages; |
| } |
| |
| static inline unsigned long change_pmd_range(struct vm_area_struct *vma, |
| pud_t *pud, unsigned long addr, unsigned long end, |
| pgprot_t newprot, int dirty_accountable, int prot_numa) |
| { |
| pmd_t *pmd; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long next; |
| unsigned long pages = 0; |
| unsigned long nr_huge_updates = 0; |
| unsigned long mni_start = 0; |
| |
| pmd = pmd_offset(pud, addr); |
| do { |
| unsigned long this_pages; |
| |
| next = pmd_addr_end(addr, end); |
| if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd) |
| && pmd_none_or_clear_bad(pmd)) |
| continue; |
| |
| /* invoke the mmu notifier if the pmd is populated */ |
| if (!mni_start) { |
| mni_start = addr; |
| mmu_notifier_invalidate_range_start(mm, mni_start, end); |
| } |
| |
| if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { |
| if (next - addr != HPAGE_PMD_SIZE) { |
| split_huge_pmd(vma, pmd, addr); |
| if (pmd_trans_unstable(pmd)) |
| continue; |
| } else { |
| int nr_ptes = change_huge_pmd(vma, pmd, addr, |
| newprot, prot_numa); |
| |
| if (nr_ptes) { |
| if (nr_ptes == HPAGE_PMD_NR) { |
| pages += HPAGE_PMD_NR; |
| nr_huge_updates++; |
| } |
| |
| /* huge pmd was handled */ |
| continue; |
| } |
| } |
| /* fall through, the trans huge pmd just split */ |
| } |
| this_pages = change_pte_range(vma, pmd, addr, next, newprot, |
| dirty_accountable, prot_numa); |
| pages += this_pages; |
| } while (pmd++, addr = next, addr != end); |
| |
| if (mni_start) |
| mmu_notifier_invalidate_range_end(mm, mni_start, end); |
| |
| 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 vm_area_struct *vma, |
| pgd_t *pgd, unsigned long addr, unsigned long end, |
| pgprot_t newprot, int dirty_accountable, int prot_numa) |
| { |
| pud_t *pud; |
| unsigned long next; |
| unsigned long pages = 0; |
| |
| pud = pud_offset(pgd, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| pages += change_pmd_range(vma, pud, addr, next, newprot, |
| dirty_accountable, prot_numa); |
| } while (pud++, addr = next, addr != end); |
| |
| return pages; |
| } |
| |
| static unsigned long change_protection_range(struct vm_area_struct *vma, |
| unsigned long addr, unsigned long end, pgprot_t newprot, |
| int dirty_accountable, int prot_numa) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pgd_t *pgd; |
| unsigned long next; |
| unsigned long start = addr; |
| unsigned long pages = 0; |
| |
| BUG_ON(addr >= end); |
| pgd = pgd_offset(mm, addr); |
| flush_cache_range(vma, addr, end); |
| set_tlb_flush_pending(mm); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| pages += change_pud_range(vma, pgd, addr, next, newprot, |
| dirty_accountable, prot_numa); |
| } while (pgd++, addr = next, addr != end); |
| |
| /* Only flush the TLB if we actually modified any entries: */ |
| if (pages) |
| flush_tlb_range(vma, start, end); |
| clear_tlb_flush_pending(mm); |
| |
| return pages; |
| } |
| |
| unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, pgprot_t newprot, |
| int dirty_accountable, int prot_numa) |
| { |
| unsigned long pages; |
| |
| if (is_vm_hugetlb_page(vma)) |
| pages = hugetlb_change_protection(vma, start, end, newprot); |
| else |
| pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa); |
| |
| 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 int prot_none_walk(struct vm_area_struct *vma, unsigned long start, |
| unsigned long end, unsigned long newflags) |
| { |
| pgprot_t new_pgprot = vm_get_page_prot(newflags); |
| struct mm_walk prot_none_walk = { |
| .pte_entry = prot_none_pte_entry, |
| .hugetlb_entry = prot_none_hugetlb_entry, |
| .test_walk = prot_none_test, |
| .mm = current->mm, |
| .private = &new_pgprot, |
| }; |
| |
| return walk_page_range(start, end, &prot_none_walk); |
| } |
| |
| int |
| mprotect_fixup(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_READ|VM_WRITE|VM_EXEC)) == 0) { |
| error = prot_none_walk(vma, start, end, newflags); |
| 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, vma_get_anon_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_sem |
| * 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(vma, start, end, vma->vm_page_prot, |
| dirty_accountable, 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); |
| |
| 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)) |
| return -EINVAL; |
| |
| reqprot = prot; |
| |
| if (down_write_killable(¤t->mm->mmap_sem)) |
| 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; |
| prev = vma->vm_prev; |
| 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; |
| |
| 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 | |
| ARCH_VM_PKEY_FLAGS; |
| |
| 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_READ | VM_WRITE | VM_EXEC)) { |
| error = -EACCES; |
| goto out; |
| } |
| |
| error = security_file_mprotect(vma, reqprot, prot); |
| if (error) |
| goto out; |
| |
| tmp = vma->vm_end; |
| if (tmp > end) |
| tmp = end; |
| 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); |
| } |
| |
| 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; |
| } |