| /* |
| * 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 <asm/uaccess.h> |
| #include <asm/pgtable.h> |
| #include <asm/cacheflush.h> |
| #include <asm/tlbflush.h> |
| |
| #ifndef pgprot_modify |
| static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot) |
| { |
| return newprot; |
| } |
| #endif |
| |
| 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, bool *ret_all_same_node) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| pte_t *pte, oldpte; |
| spinlock_t *ptl; |
| unsigned long pages = 0; |
| bool all_same_node = true; |
| int last_nid = -1; |
| |
| pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| arch_enter_lazy_mmu_mode(); |
| do { |
| oldpte = *pte; |
| if (pte_present(oldpte)) { |
| pte_t ptent; |
| bool updated = false; |
| |
| ptent = ptep_modify_prot_start(mm, addr, pte); |
| if (!prot_numa) { |
| ptent = pte_modify(ptent, newprot); |
| updated = true; |
| } else { |
| struct page *page; |
| |
| page = vm_normal_page(vma, addr, oldpte); |
| if (page) { |
| int this_nid = page_to_nid(page); |
| if (last_nid == -1) |
| last_nid = this_nid; |
| if (last_nid != this_nid) |
| all_same_node = false; |
| |
| /* only check non-shared pages */ |
| if (!pte_numa(oldpte) && |
| page_mapcount(page) == 1) { |
| ptent = pte_mknuma(ptent); |
| updated = true; |
| } |
| } |
| } |
| |
| /* |
| * Avoid taking write faults for pages we know to be |
| * dirty. |
| */ |
| if (dirty_accountable && pte_dirty(ptent)) { |
| ptent = pte_mkwrite(ptent); |
| updated = true; |
| } |
| |
| if (updated) |
| pages++; |
| ptep_modify_prot_commit(mm, addr, pte, ptent); |
| } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) { |
| swp_entry_t entry = pte_to_swp_entry(oldpte); |
| |
| if (is_write_migration_entry(entry)) { |
| /* |
| * A protection check is difficult so |
| * just be safe and disable write |
| */ |
| make_migration_entry_read(&entry); |
| set_pte_at(mm, addr, pte, |
| swp_entry_to_pte(entry)); |
| } |
| pages++; |
| } |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(pte - 1, ptl); |
| |
| *ret_all_same_node = all_same_node; |
| return pages; |
| } |
| |
| #ifdef CONFIG_NUMA_BALANCING |
| static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr, |
| pmd_t *pmd) |
| { |
| spin_lock(&mm->page_table_lock); |
| set_pmd_at(mm, addr & PMD_MASK, pmd, pmd_mknuma(*pmd)); |
| spin_unlock(&mm->page_table_lock); |
| } |
| #else |
| static inline void change_pmd_protnuma(struct mm_struct *mm, unsigned long addr, |
| pmd_t *pmd) |
| { |
| BUG(); |
| } |
| #endif /* CONFIG_NUMA_BALANCING */ |
| |
| 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; |
| unsigned long next; |
| unsigned long pages = 0; |
| unsigned long nr_huge_updates = 0; |
| bool all_same_node; |
| |
| pmd = pmd_offset(pud, addr); |
| do { |
| next = pmd_addr_end(addr, end); |
| if (pmd_trans_huge(*pmd)) { |
| if (next - addr != HPAGE_PMD_SIZE) |
| split_huge_page_pmd(vma, addr, pmd); |
| else if (change_huge_pmd(vma, pmd, addr, newprot, |
| prot_numa)) { |
| pages += HPAGE_PMD_NR; |
| nr_huge_updates++; |
| continue; |
| } |
| /* fall through */ |
| } |
| if (pmd_none_or_clear_bad(pmd)) |
| continue; |
| pages += change_pte_range(vma, pmd, addr, next, newprot, |
| dirty_accountable, prot_numa, &all_same_node); |
| |
| /* |
| * If we are changing protections for NUMA hinting faults then |
| * set pmd_numa if the examined pages were all on the same |
| * node. This allows a regular PMD to be handled as one fault |
| * and effectively batches the taking of the PTL |
| */ |
| if (prot_numa && all_same_node) |
| change_pmd_protnuma(vma->vm_mm, addr, pmd); |
| } while (pmd++, addr = next, addr != 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) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long pages; |
| |
| mmu_notifier_invalidate_range_start(mm, start, end); |
| 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); |
| mmu_notifier_invalidate_range_end(mm, start, end); |
| |
| return pages; |
| } |
| |
| 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; |
| } |
| |
| /* |
| * 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) { |
| 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)); |
| if (*pprev) { |
| vma = *pprev; |
| 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; |
| vma->vm_page_prot = pgprot_modify(vma->vm_page_prot, |
| vm_get_page_prot(newflags)); |
| |
| if (vma_wants_writenotify(vma)) { |
| vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED); |
| dirty_accountable = 1; |
| } |
| |
| change_protection(vma, start, end, vma->vm_page_prot, |
| dirty_accountable, 0); |
| |
| vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); |
| vm_stat_account(mm, newflags, vma->vm_file, nrpages); |
| perf_event_mmap(vma); |
| return 0; |
| |
| fail: |
| vm_unacct_memory(charged); |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, |
| unsigned long, prot) |
| { |
| unsigned long vm_flags, nstart, end, tmp, reqprot; |
| struct vm_area_struct *vma, *prev; |
| int error = -EINVAL; |
| const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); |
| 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; |
| /* |
| * Does the application expect PROT_READ to imply PROT_EXEC: |
| */ |
| if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) |
| prot |= PROT_EXEC; |
| |
| vm_flags = calc_vm_prot_bits(prot); |
| |
| down_write(¤t->mm->mmap_sem); |
| |
| 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 newflags; |
| |
| /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ |
| |
| newflags = vm_flags; |
| newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); |
| |
| /* 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; |
| } |
| } |
| out: |
| up_write(¤t->mm->mmap_sem); |
| return error; |
| } |