1 files changed, 433 insertions, 0 deletions

diff --git a/kernel/mm/mprotect.c b/kernel/mm/mprotect.c
new file mode 100644
index 000000000..88584838e
--- /dev/null
+++ b/kernel/mm/mprotect.c
@@ -0,0 +1,433 @@
+/*
+ *  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/ksm.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.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;
+
+	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_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)) {
+			if (next - addr != HPAGE_PMD_SIZE)
+				split_huge_page_pmd(vma, addr, pmd);
+			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;
+}
+
+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;
+	dirty_accountable = vma_wants_writenotify(vma);
+	vma_set_page_prot(vma);
+
+	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(&current->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(&current->mm->mmap_sem);
+	return error;
+}