[linux-2.6-block.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 <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)
{
	struct mm_struct *mm = vma->vm_mm;
	pte_t *pte, oldpte;
	spinlock_t *ptl;
	unsigned long pages = 0;

	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) {
					if (!pte_numa(oldpte)) {
						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)) {
				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;
	unsigned long next;
	unsigned long pages = 0;
	unsigned long nr_huge_updates = 0;

	pmd = pmd_offset(pud, addr);
	do {
		unsigned long this_pages;

		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 {
				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++;
					}
					continue;
				}
			}
			/* fall through */
		}
		if (pmd_none_or_clear_bad(pmd))
			continue;
		this_pages = change_pte_range(vma, pmd, addr, next, newprot,
				 dirty_accountable, prot_numa);
		pages += this_pages;
	} 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);
	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);

	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(&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>
1da177e4 LT	26	#include <asm/uaccess.h>
	27	#include <asm/pgtable.h>
	28	#include <asm/cacheflush.h>
	29	#include <asm/tlbflush.h>
	30
1c12c4cf VP	31	#ifndef pgprot_modify
	32	static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
	33	{
	34	return newprot;
	35	}
	36	#endif
	37
4b10e7d5	38	static unsigned long change_pte_range(struct vm_area_struct vma, pmd_t pmd,
c1e6098b	39	unsigned long addr, unsigned long end, pgprot_t newprot,
0f19c179	40	int dirty_accountable, int prot_numa)
1da177e4	41	{
4b10e7d5	42	struct mm_struct *mm = vma->vm_mm;
0697212a	43	pte_t *pte, oldpte;
705e87c0	44	spinlock_t *ptl;
7da4d641	45	unsigned long pages = 0;
1da177e4	46
705e87c0	47	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	48	arch_enter_lazy_mmu_mode();
1da177e4	49	do {
0697212a CL	50	oldpte = *pte;
0697212a CL	51	if (pte_present(oldpte)) {
1da177e4	52	pte_t ptent;
4b10e7d5	53	bool updated = false;
1da177e4	54
1ea0704e	55	ptent = ptep_modify_prot_start(mm, addr, pte);
4b10e7d5 MG	56	if (!prot_numa) {
	57	ptent = pte_modify(ptent, newprot);
	58	updated = true;
	59	} else {
	60	struct page *page;
	61
	62	page = vm_normal_page(vma, addr, oldpte);
	63	if (page) {
1bc115d8	64	if (!pte_numa(oldpte)) {
4b10e7d5 MG	65	ptent = pte_mknuma(ptent);
	66	updated = true;
	67	}
	68	}
	69	}
1ea0704e	70
c1e6098b PZ	71	/*
	72	* Avoid taking write faults for pages we know to be
	73	* dirty.
	74	*/
4b10e7d5	75	if (dirty_accountable && pte_dirty(ptent)) {
c1e6098b	76	ptent = pte_mkwrite(ptent);
4b10e7d5 MG	77	updated = true;
4b10e7d5 MG	78	}
1ea0704e	79
4b10e7d5 MG	80	if (updated)
4b10e7d5 MG	81	pages++;
1ea0704e	82	ptep_modify_prot_commit(mm, addr, pte, ptent);
ce1744f4	83	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	84	swp_entry_t entry = pte_to_swp_entry(oldpte);
	85
	86	if (is_write_migration_entry(entry)) {
c3d16e16	87	pte_t newpte;
0697212a CL	88	/*
	89	* A protection check is difficult so
	90	* just be safe and disable write
	91	*/
	92	make_migration_entry_read(&entry);
c3d16e16 CG	93	newpte = swp_entry_to_pte(entry);
	94	if (pte_swp_soft_dirty(oldpte))
	95	newpte = pte_swp_mksoft_dirty(newpte);
	96	set_pte_at(mm, addr, pte, newpte);
e920e14c MG	97
e920e14c MG	98	pages++;
0697212a	99	}
1da177e4 LT	100	}
1da177e4 LT	101	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	102	arch_leave_lazy_mmu_mode();
705e87c0	103	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	104
7da4d641 PZ	105	return pages;
1da177e4 LT	106	}
1da177e4 LT	107
7d12efae AM	108	static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
	109	pud_t *pud, unsigned long addr, unsigned long end,
	110	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	111	{
	112	pmd_t *pmd;
	113	unsigned long next;
7da4d641	114	unsigned long pages = 0;
72403b4a	115	unsigned long nr_huge_updates = 0;
1da177e4 LT	116
	117	pmd = pmd_offset(pud, addr);
	118	do {
25cbbef1 MG	119	unsigned long this_pages;
25cbbef1 MG	120
1da177e4	121	next = pmd_addr_end(addr, end);
cd7548ab JW	122	if (pmd_trans_huge(*pmd)) {
cd7548ab JW	123	if (next - addr != HPAGE_PMD_SIZE)
e180377f	124	split_huge_page_pmd(vma, addr, pmd);
f123d74a MG	125	else {
	126	int nr_ptes = change_huge_pmd(vma, pmd, addr,
	127	newprot, prot_numa);
	128
	129	if (nr_ptes) {
72403b4a MG	130	if (nr_ptes == HPAGE_PMD_NR) {
	131	pages += HPAGE_PMD_NR;
	132	nr_huge_updates++;
	133	}
f123d74a MG	134	continue;
f123d74a MG	135	}
7da4d641	136	}
cd7548ab JW	137	/* fall through */
cd7548ab JW	138	}
1da177e4 LT	139	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	140	continue;
25cbbef1	141	this_pages = change_pte_range(vma, pmd, addr, next, newprot,
0f19c179	142	dirty_accountable, prot_numa);
25cbbef1	143	pages += this_pages;
1da177e4	144	} while (pmd++, addr = next, addr != end);
7da4d641	145
72403b4a MG	146	if (nr_huge_updates)
72403b4a MG	147	count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
7da4d641	148	return pages;
1da177e4 LT	149	}
1da177e4 LT	150
7d12efae AM	151	static inline unsigned long change_pud_range(struct vm_area_struct *vma,
	152	pgd_t *pgd, unsigned long addr, unsigned long end,
	153	pgprot_t newprot, int dirty_accountable, int prot_numa)
1da177e4 LT	154	{
	155	pud_t *pud;
	156	unsigned long next;
7da4d641	157	unsigned long pages = 0;
1da177e4 LT	158
	159	pud = pud_offset(pgd, addr);
	160	do {
	161	next = pud_addr_end(addr, end);
	162	if (pud_none_or_clear_bad(pud))
	163	continue;
7da4d641	164	pages += change_pmd_range(vma, pud, addr, next, newprot,
4b10e7d5	165	dirty_accountable, prot_numa);
1da177e4	166	} while (pud++, addr = next, addr != end);
7da4d641 PZ	167
7da4d641 PZ	168	return pages;
1da177e4 LT	169	}
1da177e4 LT	170
7da4d641	171	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b	172	unsigned long addr, unsigned long end, pgprot_t newprot,
4b10e7d5	173	int dirty_accountable, int prot_numa)
1da177e4 LT	174	{
	175	struct mm_struct *mm = vma->vm_mm;
	176	pgd_t *pgd;
	177	unsigned long next;
	178	unsigned long start = addr;
7da4d641	179	unsigned long pages = 0;
1da177e4 LT	180
	181	BUG_ON(addr >= end);
	182	pgd = pgd_offset(mm, addr);
	183	flush_cache_range(vma, addr, end);
1da177e4 LT	184	do {
	185	next = pgd_addr_end(addr, end);
	186	if (pgd_none_or_clear_bad(pgd))
	187	continue;
7da4d641	188	pages += change_pud_range(vma, pgd, addr, next, newprot,
4b10e7d5	189	dirty_accountable, prot_numa);
1da177e4	190	} while (pgd++, addr = next, addr != end);
7da4d641	191
1233d588 IM	192	/* Only flush the TLB if we actually modified any entries: */
	193	if (pages)
	194	flush_tlb_range(vma, start, end);
7da4d641 PZ	195
	196	return pages;
	197	}
	198
	199	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	200	unsigned long end, pgprot_t newprot,
4b10e7d5	201	int dirty_accountable, int prot_numa)
7da4d641 PZ	202	{
	203	struct mm_struct *mm = vma->vm_mm;
	204	unsigned long pages;
	205
	206	mmu_notifier_invalidate_range_start(mm, start, end);
	207	if (is_vm_hugetlb_page(vma))
	208	pages = hugetlb_change_protection(vma, start, end, newprot);
	209	else
4b10e7d5	210	pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
7da4d641 PZ	211	mmu_notifier_invalidate_range_end(mm, start, end);
	212
	213	return pages;
1da177e4 LT	214	}
1da177e4 LT	215
b6a2fea3	216	int
1da177e4 LT	217	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	218	unsigned long start, unsigned long end, unsigned long newflags)
	219	{
	220	struct mm_struct *mm = vma->vm_mm;
	221	unsigned long oldflags = vma->vm_flags;
	222	long nrpages = (end - start) >> PAGE_SHIFT;
	223	unsigned long charged = 0;
1da177e4 LT	224	pgoff_t pgoff;
1da177e4 LT	225	int error;
c1e6098b	226	int dirty_accountable = 0;
1da177e4 LT	227
	228	if (newflags == oldflags) {
	229	*pprev = vma;
	230	return 0;
	231	}
	232
	233	/*
	234	* If we make a private mapping writable we increase our commit;
	235	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	236	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	237	* even if read-only so there is no need to account for them here
1da177e4 LT	238	*/
1da177e4 LT	239	if (newflags & VM_WRITE) {
5a6fe125	240	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	241	VM_SHARED\|VM_NORESERVE))) {
1da177e4	242	charged = nrpages;
191c5424	243	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	244	return -ENOMEM;
	245	newflags \|= VM_ACCOUNT;
	246	}
	247	}
	248
1da177e4 LT	249	/*
	250	* First try to merge with previous and/or next vma.
	251	*/
	252	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	253	pprev = vma_merge(mm, pprev, start, end, newflags,
	254	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	255	if (*pprev) {
	256	vma = *pprev;
	257	goto success;
	258	}
	259
	260	*pprev = vma;
	261
	262	if (start != vma->vm_start) {
	263	error = split_vma(mm, vma, start, 1);
	264	if (error)
	265	goto fail;
	266	}
	267
	268	if (end != vma->vm_end) {
	269	error = split_vma(mm, vma, end, 0);
	270	if (error)
	271	goto fail;
	272	}
	273
	274	success:
	275	/*
	276	* vm_flags and vm_page_prot are protected by the mmap_sem
	277	* held in write mode.
	278	*/
	279	vma->vm_flags = newflags;
1c12c4cf VP	280	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	281	vm_get_page_prot(newflags));
	282
c1e6098b	283	if (vma_wants_writenotify(vma)) {
1ddd439e	284	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	285	dirty_accountable = 1;
c1e6098b PZ	286	}
d08b3851	287
7d12efae AM	288	change_protection(vma, start, end, vma->vm_page_prot,
7d12efae AM	289	dirty_accountable, 0);
7da4d641	290
ab50b8ed HD	291	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	292	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	293	perf_event_mmap(vma);
1da177e4 LT	294	return 0;
	295
	296	fail:
	297	vm_unacct_memory(charged);
	298	return error;
	299	}
	300
6a6160a7 HC	301	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	302	unsigned long, prot)
1da177e4 LT	303	{
	304	unsigned long vm_flags, nstart, end, tmp, reqprot;
	305	struct vm_area_struct vma, prev;
	306	int error = -EINVAL;
	307	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	308	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	309	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	310	return -EINVAL;
	311
	312	if (start & ~PAGE_MASK)
	313	return -EINVAL;
	314	if (!len)
	315	return 0;
	316	len = PAGE_ALIGN(len);
	317	end = start + len;
	318	if (end <= start)
	319	return -ENOMEM;
b845f313	320	if (!arch_validate_prot(prot))
1da177e4 LT	321	return -EINVAL;
	322
	323	reqprot = prot;
	324	/*
	325	* Does the application expect PROT_READ to imply PROT_EXEC:
	326	*/
b344e05c	327	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	328	prot \|= PROT_EXEC;
	329
	330	vm_flags = calc_vm_prot_bits(prot);
	331
	332	down_write(&current->mm->mmap_sem);
	333
097d5910	334	vma = find_vma(current->mm, start);
1da177e4 LT	335	error = -ENOMEM;
	336	if (!vma)
	337	goto out;
097d5910	338	prev = vma->vm_prev;
1da177e4 LT	339	if (unlikely(grows & PROT_GROWSDOWN)) {
	340	if (vma->vm_start >= end)
	341	goto out;
	342	start = vma->vm_start;
	343	error = -EINVAL;
	344	if (!(vma->vm_flags & VM_GROWSDOWN))
	345	goto out;
7d12efae	346	} else {
1da177e4 LT	347	if (vma->vm_start > start)
	348	goto out;
	349	if (unlikely(grows & PROT_GROWSUP)) {
	350	end = vma->vm_end;
	351	error = -EINVAL;
	352	if (!(vma->vm_flags & VM_GROWSUP))
	353	goto out;
	354	}
	355	}
	356	if (start > vma->vm_start)
	357	prev = vma;
	358
	359	for (nstart = start ; ; ) {
	360	unsigned long newflags;
	361
7d12efae	362	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
1da177e4	363
7d12efae AM	364	newflags = vm_flags;
7d12efae AM	365	newflags \|= (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4	366
7e2cff42 PBG	367	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	368	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	369	error = -EACCES;
	370	goto out;
	371	}
	372
	373	error = security_file_mprotect(vma, reqprot, prot);
	374	if (error)
	375	goto out;
	376
	377	tmp = vma->vm_end;
	378	if (tmp > end)
	379	tmp = end;
	380	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	381	if (error)
	382	goto out;
	383	nstart = tmp;
	384
	385	if (nstart < prev->vm_end)
	386	nstart = prev->vm_end;
	387	if (nstart >= end)
	388	goto out;
	389
	390	vma = prev->vm_next;
	391	if (!vma \|\| vma->vm_start != nstart) {
	392	error = -ENOMEM;
	393	goto out;
	394	}
	395	}
	396	out:
	397	up_write(&current->mm->mmap_sem);
	398	return error;
	399	}