[mirror_ubuntu-artful-kernel.git] / mm / mprotect.c

/*
 *  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>

#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;

	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_none(*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;
}

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) {
		/* 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);
	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);

	/*
	 * 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;
}

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, 0);

	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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* mm/mprotect.c
	3	*
	4	* (C) Copyright 1994 Linus Torvalds
	5	* (C) Copyright 2002 Christoph Hellwig
	6	*
046c6884	7	* Address space accounting code <alan@lxorguk.ukuu.org.uk>
1da177e4 LT	8	* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
	9	*/
	10
	11	#include <linux/mm.h>
	12	#include <linux/hugetlb.h>
1da177e4 LT	13	#include <linux/shm.h>
	14	#include <linux/mman.h>
	15	#include <linux/fs.h>
	16	#include <linux/highmem.h>
	17	#include <linux/security.h>
	18	#include <linux/mempolicy.h>
	19	#include <linux/personality.h>
	20	#include <linux/syscalls.h>
0697212a CL	21	#include <linux/swap.h>
0697212a CL	22	#include <linux/swapops.h>
cddb8a5c	23	#include <linux/mmu_notifier.h>
64cdd548	24	#include <linux/migrate.h>
cdd6c482	25	#include <linux/perf_event.h>
64a9a34e	26	#include <linux/ksm.h>
1da177e4 LT	27	#include <asm/uaccess.h>
	28	#include <asm/pgtable.h>
	29	#include <asm/cacheflush.h>
	30	#include <asm/tlbflush.h>
	31
36f88188 KS	32	#include "internal.h"
36f88188 KS	33
1ad9f620 MG	34	/*
	35	* For a prot_numa update we only hold mmap_sem for read so there is a
	36	* potential race with faulting where a pmd was temporarily none. This
	37	* function checks for a transhuge pmd under the appropriate lock. It
	38	* returns a pte if it was successfully locked or NULL if it raced with
	39	* a transhuge insertion.
	40	*/
	41	static pte_t lock_pte_protection(struct vm_area_struct vma, pmd_t *pmd,
	42	unsigned long addr, int prot_numa, spinlock_t **ptl)
	43	{
	44	pte_t *pte;
	45	spinlock_t *pmdl;
	46
	47	/* !prot_numa is protected by mmap_sem held for write */
	48	if (!prot_numa)
	49	return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	50
	51	pmdl = pmd_lock(vma->vm_mm, pmd);
	52	if (unlikely(pmd_trans_huge(pmd) \|\| pmd_none(pmd))) {
	53	spin_unlock(pmdl);
	54	return NULL;
	55	}
	56
	57	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
	58	spin_unlock(pmdl);
	59	return pte;
	60	}
	61
4b10e7d5	62	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	63	unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179	64	int dirty_accountable, int prot_numa)
1da177e4	65	{
4b10e7d5	66	struct mm_struct *mm = vma->vm_mm;
0697212a	67	pte_t *pte, oldpte;
705e87c0	68	spinlock_t *ptl;
7da4d641	69	unsigned long pages = 0;
1da177e4	70
1ad9f620 MG	71	pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
	72	if (!pte)
	73	return 0;
	74
6606c3e0	75	arch_enter_lazy_mmu_mode();
1da177e4	76	do {
0697212a CL	77	oldpte = *pte;
0697212a CL	78	if (pte_present(oldpte)) {
1da177e4	79	pte_t ptent;
b191f9b1	80	bool preserve_write = prot_numa && pte_write(oldpte);
1da177e4	81
e944fd67 MG	82	/*
	83	* Avoid trapping faults against the zero or KSM
	84	* pages. See similar comment in change_huge_pmd.
	85	*/
	86	if (prot_numa) {
	87	struct page *page;
	88
	89	page = vm_normal_page(vma, addr, oldpte);
	90	if (!page \|\| PageKsm(page))
	91	continue;
10c1045f MG	92
	93	/* Avoid TLB flush if possible */
	94	if (pte_protnone(oldpte))
	95	continue;
e944fd67 MG	96	}
e944fd67 MG	97
8a0516ed MG	98	ptent = ptep_modify_prot_start(mm, addr, pte);
8a0516ed MG	99	ptent = pte_modify(ptent, newprot);
b191f9b1 MG	100	if (preserve_write)
b191f9b1 MG	101	ptent = pte_mkwrite(ptent);
4b10e7d5	102
8a0516ed MG	103	/* Avoid taking write faults for known dirty pages */
	104	if (dirty_accountable && pte_dirty(ptent) &&
	105	(pte_soft_dirty(ptent) \|\|
	106	!(vma->vm_flags & VM_SOFTDIRTY))) {
	107	ptent = pte_mkwrite(ptent);
4b10e7d5	108	}
8a0516ed MG	109	ptep_modify_prot_commit(mm, addr, pte, ptent);
8a0516ed MG	110	pages++;
0661a336	111	} else if (IS_ENABLED(CONFIG_MIGRATION)) {
0697212a CL	112	swp_entry_t entry = pte_to_swp_entry(oldpte);
	113
	114	if (is_write_migration_entry(entry)) {
c3d16e16	115	pte_t newpte;
0697212a CL	116	/*
	117	* A protection check is difficult so
	118	* just be safe and disable write
	119	*/
	120	make_migration_entry_read(&entry);
c3d16e16 CG	121	newpte = swp_entry_to_pte(entry);
	122	if (pte_swp_soft_dirty(oldpte))
	123	newpte = pte_swp_mksoft_dirty(newpte);
	124	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	125
e920e14c MG	126	pages++;
0697212a	127	}
1da177e4 LT	128	}
1da177e4 LT	129	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	130	arch_leave_lazy_mmu_mode();
705e87c0	131	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	132
7da4d641 PZ	133	return pages;
1da177e4 LT	134	}
1da177e4 LT	135
7d12efae AM	136	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	137	pud_t *pud, unsigned long addr, unsigned long end,
	138	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	139	{
1da177e4 LT	140	pmd_t *pmd;
a5338093	141	struct mm_struct *mm = vma->vm_mm;
1da177e4	142	unsigned long next;
7da4d641	143	unsigned long pages = 0;
72403b4a	144	unsigned long nr_huge_updates = 0;
a5338093	145	unsigned long mni_start = 0;
1da177e4 LT	146
	147	pmd = pmd_offset(pud, addr);
	148	do {
25cbbef1 MG	149	unsigned long this_pages;
25cbbef1 MG	150
1da177e4	151	next = pmd_addr_end(addr, end);
5c7fb56e DW	152	if (!pmd_trans_huge(pmd) && !pmd_devmap(pmd)
5c7fb56e DW	153	&& pmd_none_or_clear_bad(pmd))
88a9ab6e	154	continue;
a5338093 RR	155
	156	/* invoke the mmu notifier if the pmd is populated */
	157	if (!mni_start) {
	158	mni_start = addr;
	159	mmu_notifier_invalidate_range_start(mm, mni_start, end);
	160	}
	161
5c7fb56e	162	if (pmd_trans_huge(pmd) \|\| pmd_devmap(pmd)) {
6b9116a6	163	if (next - addr != HPAGE_PMD_SIZE) {
78ddc534	164	split_huge_pmd(vma, pmd, addr);
6b9116a6 KS	165	if (pmd_none(*pmd))
	166	continue;
	167	} else {
f123d74a	168	int nr_ptes = change_huge_pmd(vma, pmd, addr,
e944fd67	169	newprot, prot_numa);
f123d74a MG	170
f123d74a MG	171	if (nr_ptes) {
72403b4a MG	172	if (nr_ptes == HPAGE_PMD_NR) {
	173	pages += HPAGE_PMD_NR;
	174	nr_huge_updates++;
	175	}
1ad9f620 MG	176
1ad9f620 MG	177	/* huge pmd was handled */
f123d74a MG	178	continue;
f123d74a MG	179	}
7da4d641	180	}
88a9ab6e	181	/* fall through, the trans huge pmd just split */
cd7548ab	182	}
25cbbef1	183	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	184	dirty_accountable, prot_numa);
25cbbef1	185	pages += this_pages;
1da177e4	186	} while (pmd++, addr = next, addr != end);
7da4d641	187
a5338093 RR	188	if (mni_start)
	189	mmu_notifier_invalidate_range_end(mm, mni_start, end);
	190
72403b4a MG	191	if (nr_huge_updates)
72403b4a MG	192	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	193	return pages;
1da177e4 LT	194	}
1da177e4 LT	195
7d12efae AM	196	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	197	pgd_t *pgd, unsigned long addr, unsigned long end,
	198	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	199	{
	200	pud_t *pud;
	201	unsigned long next;
7da4d641	202	unsigned long pages = 0;
1da177e4 LT	203
	204	pud = pud_offset(pgd, addr);
	205	do {
	206	next = pud_addr_end(addr, end);
	207	if (pud_none_or_clear_bad(pud))
	208	continue;
7da4d641	209	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	210	dirty_accountable, prot_numa);
1da177e4	211	} while (pud++, addr = next, addr != end);
7da4d641 PZ	212
7da4d641 PZ	213	return pages;
1da177e4 LT	214	}
1da177e4 LT	215
7da4d641	216	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	217	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	218	int dirty_accountable, int prot_numa)
1da177e4 LT	219	{
	220	struct mm_struct *mm = vma->vm_mm;
	221	pgd_t *pgd;
	222	unsigned long next;
	223	unsigned long start = addr;
7da4d641	224	unsigned long pages = 0;
1da177e4 LT	225
	226	BUG_ON(addr >= end);
	227	pgd = pgd_offset(mm, addr);
	228	flush_cache_range(vma, addr, end);
20841405	229	set_tlb_flush_pending(mm);
1da177e4 LT	230	do {
	231	next = pgd_addr_end(addr, end);
	232	if (pgd_none_or_clear_bad(pgd))
	233	continue;
7da4d641	234	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	235	dirty_accountable, prot_numa);
1da177e4	236	} while (pgd++, addr = next, addr != end);
7da4d641	237
1233d588 IM	238	/* Only flush the TLB if we actually modified any entries: */
	239	if (pages)
	240	flush_tlb_range(vma, start, end);
20841405	241	clear_tlb_flush_pending(mm);
7da4d641 PZ	242
	243	return pages;
	244	}
	245
	246	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	247	unsigned long end, pgprot_t newprot,
4b10e7d5	248	int dirty_accountable, int prot_numa)
7da4d641	249	{
7da4d641 PZ	250	unsigned long pages;
7da4d641 PZ	251
7da4d641 PZ	252	if (is_vm_hugetlb_page(vma))
	253	pages = hugetlb_change_protection(vma, start, end, newprot);
	254	else
4b10e7d5	255	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	256
7da4d641 PZ	257	return pages;
1da177e4 LT	258	}
1da177e4 LT	259
b6a2fea3	260	int
1da177e4 LT	261	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	262	unsigned long start, unsigned long end, unsigned long newflags)
	263	{
	264	struct mm_struct *mm = vma->vm_mm;
	265	unsigned long oldflags = vma->vm_flags;
	266	long nrpages = (end - start) >> PAGE_SHIFT;
	267	unsigned long charged = 0;
1da177e4 LT	268	pgoff_t pgoff;
1da177e4 LT	269	int error;
c1e6098b	270	int dirty_accountable = 0;
1da177e4 LT	271
	272	if (newflags == oldflags) {
	273	*pprev = vma;
	274	return 0;
	275	}
	276
	277	/*
	278	* If we make a private mapping writable we increase our commit;
	279	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	280	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	281	* even if read-only so there is no need to account for them here
1da177e4 LT	282	*/
1da177e4 LT	283	if (newflags & VM_WRITE) {
84638335 KK	284	/* Check space limits when area turns into data. */
	285	if (!may_expand_vm(mm, newflags, nrpages) &&
	286	may_expand_vm(mm, oldflags, nrpages))
	287	return -ENOMEM;
5a6fe125	288	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	289	VM_SHARED\|VM_NORESERVE))) {
1da177e4	290	charged = nrpages;
191c5424	291	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	292	return -ENOMEM;
	293	newflags \|= VM_ACCOUNT;
	294	}
	295	}
	296
1da177e4 LT	297	/*
	298	* First try to merge with previous and/or next vma.
	299	*/
	300	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	301	pprev = vma_merge(mm, pprev, start, end, newflags,
19a809af AA	302	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
19a809af AA	303	vma->vm_userfaultfd_ctx);
1da177e4 LT	304	if (*pprev) {
	305	vma = *pprev;
	306	goto success;
	307	}
	308
	309	*pprev = vma;
	310
	311	if (start != vma->vm_start) {
	312	error = split_vma(mm, vma, start, 1);
	313	if (error)
	314	goto fail;
	315	}
	316
	317	if (end != vma->vm_end) {
	318	error = split_vma(mm, vma, end, 0);
	319	if (error)
	320	goto fail;
	321	}
	322
	323	success:
	324	/*
	325	* vm_flags and vm_page_prot are protected by the mmap_sem
	326	* held in write mode.
	327	*/
	328	vma->vm_flags = newflags;
64e45507 PF	329	dirty_accountable = vma_wants_writenotify(vma);
64e45507 PF	330	vma_set_page_prot(vma);
d08b3851	331
7d12efae AM	332	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	333	dirty_accountable, 0);
7da4d641	334
36f88188 KS	335	/*
	336	* Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
	337	* fault on access.
	338	*/
	339	if ((oldflags & (VM_WRITE \| VM_SHARED \| VM_LOCKED)) == VM_LOCKED &&
	340	(newflags & VM_WRITE)) {
	341	populate_vma_page_range(vma, start, end, NULL);
	342	}
	343
84638335 KK	344	vm_stat_account(mm, oldflags, -nrpages);
84638335 KK	345	vm_stat_account(mm, newflags, nrpages);
63bfd738	346	perf_event_mmap(vma);
1da177e4 LT	347	return 0;
	348
	349	fail:
	350	vm_unacct_memory(charged);
	351	return error;
	352	}
	353
6a6160a7 HC	354	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	355	unsigned long, prot)
1da177e4 LT	356	{
	357	unsigned long vm_flags, nstart, end, tmp, reqprot;
	358	struct vm_area_struct vma, prev;
	359	int error = -EINVAL;
	360	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	361	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	362	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	363	return -EINVAL;
	364
	365	if (start & ~PAGE_MASK)
	366	return -EINVAL;
	367	if (!len)
	368	return 0;
	369	len = PAGE_ALIGN(len);
	370	end = start + len;
	371	if (end <= start)
	372	return -ENOMEM;
b845f313	373	if (!arch_validate_prot(prot))
1da177e4 LT	374	return -EINVAL;
	375
	376	reqprot = prot;
	377	/*
	378	* Does the application expect PROT_READ to imply PROT_EXEC:
	379	*/
b344e05c	380	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	381	prot \|= PROT_EXEC;
1da177e4 LT	382
e6bfb709	383	vm_flags = calc_vm_prot_bits(prot, 0);
1da177e4 LT	384
	385	down_write(&current->mm->mmap_sem);
	386
097d5910	387	vma = find_vma(current->mm, start);
1da177e4 LT	388	error = -ENOMEM;
	389	if (!vma)
	390	goto out;
097d5910	391	prev = vma->vm_prev;
1da177e4 LT	392	if (unlikely(grows & PROT_GROWSDOWN)) {
	393	if (vma->vm_start >= end)
	394	goto out;
	395	start = vma->vm_start;
	396	error = -EINVAL;
	397	if (!(vma->vm_flags & VM_GROWSDOWN))
	398	goto out;
7d12efae	399	} else {
1da177e4 LT	400	if (vma->vm_start > start)
	401	goto out;
	402	if (unlikely(grows & PROT_GROWSUP)) {
	403	end = vma->vm_end;
	404	error = -EINVAL;
	405	if (!(vma->vm_flags & VM_GROWSUP))
	406	goto out;
	407	}
	408	}
	409	if (start > vma->vm_start)
	410	prev = vma;
	411
	412	for (nstart = start ; ; ) {
	413	unsigned long newflags;
	414
7d12efae	415	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	416
7d12efae AM	417	newflags = vm_flags;
7d12efae AM	418	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	419
7e2cff42 PBG	420	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	421	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	422	error = -EACCES;
	423	goto out;
	424	}
	425
	426	error = security_file_mprotect(vma, reqprot, prot);
	427	if (error)
	428	goto out;
	429
	430	tmp = vma->vm_end;
	431	if (tmp > end)
	432	tmp = end;
	433	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	434	if (error)
	435	goto out;
	436	nstart = tmp;
	437
	438	if (nstart < prev->vm_end)
	439	nstart = prev->vm_end;
	440	if (nstart >= end)
	441	goto out;
	442
	443	vma = prev->vm_next;
	444	if (!vma \|\| vma->vm_start != nstart) {
	445	error = -ENOMEM;
	446	goto out;
	447	}
	448	}
	449	out:
	450	up_write(&current->mm->mmap_sem);
	451	return error;
	452	}