[mirror_ubuntu-bionic-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 <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 mm_struct *mm, pmd_t *pmd,
		unsigned long addr, unsigned long end, pgprot_t newprot,
		int dirty_accountable)
{
	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;

			ptent = ptep_modify_prot_start(mm, addr, pte);
			ptent = pte_modify(ptent, newprot);

			/*
			 * Avoid taking write faults for pages we know to be
			 * dirty.
			 */
			if (dirty_accountable && pte_dirty(ptent))
				ptent = pte_mkwrite(ptent);

			ptep_modify_prot_commit(mm, addr, pte, ptent);
			pages++;
		} 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);

	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)
{
	pmd_t *pmd;
	unsigned long next;
	unsigned long pages = 0;

	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->vm_mm, pmd);
			else if (change_huge_pmd(vma, pmd, addr, newprot)) {
				pages += HPAGE_PMD_NR;
				continue;
			}
			/* fall through */
		}
		if (pmd_none_or_clear_bad(pmd))
			continue;
		pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
				 dirty_accountable);
	} while (pmd++, addr = next, addr != end);

	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)
{
	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);
	} 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)
{
	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);
	} while (pgd++, addr = next, addr != end);

	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)
{
	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);
	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);

	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 | (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
7da4d641	38	static unsigned long change_pte_range(struct mm_struct mm, pmd_t pmd,
c1e6098b PZ	39	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	40	int dirty_accountable)
1da177e4	41	{
0697212a	42	pte_t *pte, oldpte;
705e87c0	43	spinlock_t *ptl;
7da4d641	44	unsigned long pages = 0;
1da177e4	45
705e87c0	46	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	47	arch_enter_lazy_mmu_mode();
1da177e4	48	do {
0697212a CL	49	oldpte = *pte;
0697212a CL	50	if (pte_present(oldpte)) {
1da177e4 LT	51	pte_t ptent;
1da177e4 LT	52
1ea0704e	53	ptent = ptep_modify_prot_start(mm, addr, pte);
c1e6098b	54	ptent = pte_modify(ptent, newprot);
1ea0704e	55
c1e6098b PZ	56	/*
	57	* Avoid taking write faults for pages we know to be
	58	* dirty.
	59	*/
	60	if (dirty_accountable && pte_dirty(ptent))
	61	ptent = pte_mkwrite(ptent);
1ea0704e JF	62
1ea0704e JF	63	ptep_modify_prot_commit(mm, addr, pte, ptent);
7da4d641	64	pages++;
ce1744f4	65	} else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
0697212a CL	66	swp_entry_t entry = pte_to_swp_entry(oldpte);
	67
	68	if (is_write_migration_entry(entry)) {
	69	/*
	70	* A protection check is difficult so
	71	* just be safe and disable write
	72	*/
	73	make_migration_entry_read(&entry);
	74	set_pte_at(mm, addr, pte,
	75	swp_entry_to_pte(entry));
	76	}
7da4d641	77	pages++;
1da177e4 LT	78	}
1da177e4 LT	79	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	80	arch_leave_lazy_mmu_mode();
705e87c0	81	pte_unmap_unlock(pte - 1, ptl);
7da4d641 PZ	82
7da4d641 PZ	83	return pages;
1da177e4 LT	84	}
1da177e4 LT	85
7da4d641	86	static inline unsigned long change_pmd_range(struct vm_area_struct vma, pud_t pud,
c1e6098b PZ	87	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	88	int dirty_accountable)
1da177e4 LT	89	{
	90	pmd_t *pmd;
	91	unsigned long next;
7da4d641	92	unsigned long pages = 0;
1da177e4 LT	93
	94	pmd = pmd_offset(pud, addr);
	95	do {
	96	next = pmd_addr_end(addr, end);
cd7548ab JW	97	if (pmd_trans_huge(*pmd)) {
	98	if (next - addr != HPAGE_PMD_SIZE)
	99	split_huge_page_pmd(vma->vm_mm, pmd);
7da4d641 PZ	100	else if (change_huge_pmd(vma, pmd, addr, newprot)) {
7da4d641 PZ	101	pages += HPAGE_PMD_NR;
cd7548ab	102	continue;
7da4d641	103	}
cd7548ab JW	104	/* fall through */
cd7548ab JW	105	}
1da177e4 LT	106	if (pmd_none_or_clear_bad(pmd))
1da177e4 LT	107	continue;
7da4d641	108	pages += change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
b36f5b07	109	dirty_accountable);
1da177e4	110	} while (pmd++, addr = next, addr != end);
7da4d641 PZ	111
7da4d641 PZ	112	return pages;
1da177e4 LT	113	}
1da177e4 LT	114
7da4d641	115	static inline unsigned long change_pud_range(struct vm_area_struct vma, pgd_t pgd,
c1e6098b PZ	116	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	117	int dirty_accountable)
1da177e4 LT	118	{
	119	pud_t *pud;
	120	unsigned long next;
7da4d641	121	unsigned long pages = 0;
1da177e4 LT	122
	123	pud = pud_offset(pgd, addr);
	124	do {
	125	next = pud_addr_end(addr, end);
	126	if (pud_none_or_clear_bad(pud))
	127	continue;
7da4d641	128	pages += change_pmd_range(vma, pud, addr, next, newprot,
b36f5b07	129	dirty_accountable);
1da177e4	130	} while (pud++, addr = next, addr != end);
7da4d641 PZ	131
7da4d641 PZ	132	return pages;
1da177e4 LT	133	}
1da177e4 LT	134
7da4d641	135	static unsigned long change_protection_range(struct vm_area_struct *vma,
c1e6098b PZ	136	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	137	int dirty_accountable)
1da177e4 LT	138	{
	139	struct mm_struct *mm = vma->vm_mm;
	140	pgd_t *pgd;
	141	unsigned long next;
	142	unsigned long start = addr;
7da4d641	143	unsigned long pages = 0;
1da177e4 LT	144
	145	BUG_ON(addr >= end);
	146	pgd = pgd_offset(mm, addr);
	147	flush_cache_range(vma, addr, end);
1da177e4 LT	148	do {
	149	next = pgd_addr_end(addr, end);
	150	if (pgd_none_or_clear_bad(pgd))
	151	continue;
7da4d641	152	pages += change_pud_range(vma, pgd, addr, next, newprot,
b36f5b07	153	dirty_accountable);
1da177e4	154	} while (pgd++, addr = next, addr != end);
7da4d641	155
1da177e4	156	flush_tlb_range(vma, start, end);
7da4d641 PZ	157
	158	return pages;
	159	}
	160
	161	unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
	162	unsigned long end, pgprot_t newprot,
	163	int dirty_accountable)
	164	{
	165	struct mm_struct *mm = vma->vm_mm;
	166	unsigned long pages;
	167
	168	mmu_notifier_invalidate_range_start(mm, start, end);
	169	if (is_vm_hugetlb_page(vma))
	170	pages = hugetlb_change_protection(vma, start, end, newprot);
	171	else
	172	pages = change_protection_range(vma, start, end, newprot, dirty_accountable);
	173	mmu_notifier_invalidate_range_end(mm, start, end);
	174
	175	return pages;
1da177e4 LT	176	}
1da177e4 LT	177
b6a2fea3	178	int
1da177e4 LT	179	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	180	unsigned long start, unsigned long end, unsigned long newflags)
	181	{
	182	struct mm_struct *mm = vma->vm_mm;
	183	unsigned long oldflags = vma->vm_flags;
	184	long nrpages = (end - start) >> PAGE_SHIFT;
	185	unsigned long charged = 0;
1da177e4 LT	186	pgoff_t pgoff;
1da177e4 LT	187	int error;
c1e6098b	188	int dirty_accountable = 0;
1da177e4 LT	189
	190	if (newflags == oldflags) {
	191	*pprev = vma;
	192	return 0;
	193	}
	194
	195	/*
	196	* If we make a private mapping writable we increase our commit;
	197	* but (without finer accounting) cannot reduce our commit if we
5a6fe125 MG	198	* make it unwritable again. hugetlb mapping were accounted for
5a6fe125 MG	199	* even if read-only so there is no need to account for them here
1da177e4 LT	200	*/
1da177e4 LT	201	if (newflags & VM_WRITE) {
5a6fe125	202	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_HUGETLB\|
cdfd4325	203	VM_SHARED\|VM_NORESERVE))) {
1da177e4	204	charged = nrpages;
191c5424	205	if (security_vm_enough_memory_mm(mm, charged))
1da177e4 LT	206	return -ENOMEM;
	207	newflags \|= VM_ACCOUNT;
	208	}
	209	}
	210
1da177e4 LT	211	/*
	212	* First try to merge with previous and/or next vma.
	213	*/
	214	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	215	pprev = vma_merge(mm, pprev, start, end, newflags,
	216	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	217	if (*pprev) {
	218	vma = *pprev;
	219	goto success;
	220	}
	221
	222	*pprev = vma;
	223
	224	if (start != vma->vm_start) {
	225	error = split_vma(mm, vma, start, 1);
	226	if (error)
	227	goto fail;
	228	}
	229
	230	if (end != vma->vm_end) {
	231	error = split_vma(mm, vma, end, 0);
	232	if (error)
	233	goto fail;
	234	}
	235
	236	success:
	237	/*
	238	* vm_flags and vm_page_prot are protected by the mmap_sem
	239	* held in write mode.
	240	*/
	241	vma->vm_flags = newflags;
1c12c4cf VP	242	vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
	243	vm_get_page_prot(newflags));
	244
c1e6098b	245	if (vma_wants_writenotify(vma)) {
1ddd439e	246	vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
c1e6098b PZ	247	dirty_accountable = 1;
c1e6098b PZ	248	}
d08b3851	249
7da4d641 PZ	250	change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
7da4d641 PZ	251
ab50b8ed HD	252	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	253	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
63bfd738	254	perf_event_mmap(vma);
1da177e4 LT	255	return 0;
	256
	257	fail:
	258	vm_unacct_memory(charged);
	259	return error;
	260	}
	261
6a6160a7 HC	262	SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
6a6160a7 HC	263	unsigned long, prot)
1da177e4 LT	264	{
	265	unsigned long vm_flags, nstart, end, tmp, reqprot;
	266	struct vm_area_struct vma, prev;
	267	int error = -EINVAL;
	268	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	269	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	270	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	271	return -EINVAL;
	272
	273	if (start & ~PAGE_MASK)
	274	return -EINVAL;
	275	if (!len)
	276	return 0;
	277	len = PAGE_ALIGN(len);
	278	end = start + len;
	279	if (end <= start)
	280	return -ENOMEM;
b845f313	281	if (!arch_validate_prot(prot))
1da177e4 LT	282	return -EINVAL;
	283
	284	reqprot = prot;
	285	/*
	286	* Does the application expect PROT_READ to imply PROT_EXEC:
	287	*/
b344e05c	288	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	289	prot \|= PROT_EXEC;
	290
	291	vm_flags = calc_vm_prot_bits(prot);
	292
	293	down_write(&current->mm->mmap_sem);
	294
097d5910	295	vma = find_vma(current->mm, start);
1da177e4 LT	296	error = -ENOMEM;
	297	if (!vma)
	298	goto out;
097d5910	299	prev = vma->vm_prev;
1da177e4 LT	300	if (unlikely(grows & PROT_GROWSDOWN)) {
	301	if (vma->vm_start >= end)
	302	goto out;
	303	start = vma->vm_start;
	304	error = -EINVAL;
	305	if (!(vma->vm_flags & VM_GROWSDOWN))
	306	goto out;
	307	}
	308	else {
	309	if (vma->vm_start > start)
	310	goto out;
	311	if (unlikely(grows & PROT_GROWSUP)) {
	312	end = vma->vm_end;
	313	error = -EINVAL;
	314	if (!(vma->vm_flags & VM_GROWSUP))
	315	goto out;
	316	}
	317	}
	318	if (start > vma->vm_start)
	319	prev = vma;
	320
	321	for (nstart = start ; ; ) {
	322	unsigned long newflags;
	323
	324	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
	325
1da177e4 LT	326	newflags = vm_flags \| (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4 LT	327
7e2cff42 PBG	328	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	329	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	330	error = -EACCES;
	331	goto out;
	332	}
	333
	334	error = security_file_mprotect(vma, reqprot, prot);
	335	if (error)
	336	goto out;
	337
	338	tmp = vma->vm_end;
	339	if (tmp > end)
	340	tmp = end;
	341	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	342	if (error)
	343	goto out;
	344	nstart = tmp;
	345
	346	if (nstart < prev->vm_end)
	347	nstart = prev->vm_end;
	348	if (nstart >= end)
	349	goto out;
	350
	351	vma = prev->vm_next;
	352	if (!vma \|\| vma->vm_start != nstart) {
	353	error = -ENOMEM;
	354	goto out;
	355	}
	356	}
	357	out:
	358	up_write(&current->mm->mmap_sem);
	359	return error;
	360	}