[linux.git] / mm / mprotect.c

/*
 *  mm/mprotect.c
 *
 *  (C) Copyright 1994 Linus Torvalds
 *  (C) Copyright 2002 Christoph Hellwig
 *
 *  Address space accounting code	<[email protected]>
 *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
 */

#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/slab.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 <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

static void 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;

	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
	arch_enter_lazy_mmu_mode();
	do {
		oldpte = *pte;
		if (pte_present(oldpte)) {
			pte_t ptent;

			/* Avoid an SMP race with hardware updated dirty/clean
			 * bits by wiping the pte and then setting the new pte
			 * into place.
			 */
			ptent = ptep_get_and_clear(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);
			set_pte_at(mm, addr, pte, ptent);
			lazy_mmu_prot_update(ptent);
#ifdef CONFIG_MIGRATION
		} else if (!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));
			}
#endif
		}

	} while (pte++, addr += PAGE_SIZE, addr != end);
	arch_leave_lazy_mmu_mode();
	pte_unmap_unlock(pte - 1, ptl);
}

static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
		unsigned long addr, unsigned long end, pgprot_t newprot,
		int dirty_accountable)
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
		change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
	} while (pmd++, addr = next, addr != end);
}

static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
		unsigned long addr, unsigned long end, pgprot_t newprot,
		int dirty_accountable)
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
		change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
	} while (pud++, addr = next, addr != end);
}

static void change_protection(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;

	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;
		change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
	} while (pgd++, addr = next, addr != end);
	flush_tlb_range(vma, start, end);
}

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.
	 *
	 * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
	 * a MAP_NORESERVE private mapping to writable will now reserve.
	 */
	if (newflags & VM_WRITE) {
		if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED))) {
			charged = nrpages;
			if (security_vm_enough_memory(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 = protection_map[newflags &
		(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
	if (vma_wants_writenotify(vma)) {
		vma->vm_page_prot = protection_map[newflags &
			(VM_READ|VM_WRITE|VM_EXEC)];
		dirty_accountable = 1;
	}

	if (is_vm_hugetlb_page(vma))
		hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
	else
		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);
	return 0;

fail:
	vm_unacct_memory(charged);
	return error;
}

asmlinkage long
sys_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 (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM))
		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_prev(current->mm, start, &prev);
	error = -ENOMEM;
	if (!vma)
		goto out;
	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	*
	7	* Address space accounting code <[email protected]>
	8	* (C) Copyright 2002 Red Hat Inc, All Rights Reserved
	9	*/
	10
	11	#include <linux/mm.h>
	12	#include <linux/hugetlb.h>
	13	#include <linux/slab.h>
	14	#include <linux/shm.h>
	15	#include <linux/mman.h>
	16	#include <linux/fs.h>
	17	#include <linux/highmem.h>
	18	#include <linux/security.h>
	19	#include <linux/mempolicy.h>
	20	#include <linux/personality.h>
	21	#include <linux/syscalls.h>
0697212a CL	22	#include <linux/swap.h>
0697212a CL	23	#include <linux/swapops.h>
1da177e4 LT	24	#include <asm/uaccess.h>
	25	#include <asm/pgtable.h>
	26	#include <asm/cacheflush.h>
	27	#include <asm/tlbflush.h>
	28
	29	static void change_pte_range(struct mm_struct mm, pmd_t pmd,
c1e6098b PZ	30	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	31	int dirty_accountable)
1da177e4	32	{
0697212a	33	pte_t *pte, oldpte;
705e87c0	34	spinlock_t *ptl;
1da177e4	35
705e87c0	36	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
6606c3e0	37	arch_enter_lazy_mmu_mode();
1da177e4	38	do {
0697212a CL	39	oldpte = *pte;
0697212a CL	40	if (pte_present(oldpte)) {
1da177e4 LT	41	pte_t ptent;
	42
	43	/* Avoid an SMP race with hardware updated dirty/clean
	44	* bits by wiping the pte and then setting the new pte
	45	* into place.
	46	*/
c1e6098b PZ	47	ptent = ptep_get_and_clear(mm, addr, pte);
	48	ptent = pte_modify(ptent, newprot);
	49	/*
	50	* Avoid taking write faults for pages we know to be
	51	* dirty.
	52	*/
	53	if (dirty_accountable && pte_dirty(ptent))
	54	ptent = pte_mkwrite(ptent);
1da177e4 LT	55	set_pte_at(mm, addr, pte, ptent);
1da177e4 LT	56	lazy_mmu_prot_update(ptent);
0697212a CL	57	#ifdef CONFIG_MIGRATION
	58	} else if (!pte_file(oldpte)) {
	59	swp_entry_t entry = pte_to_swp_entry(oldpte);
	60
	61	if (is_write_migration_entry(entry)) {
	62	/*
	63	* A protection check is difficult so
	64	* just be safe and disable write
	65	*/
	66	make_migration_entry_read(&entry);
	67	set_pte_at(mm, addr, pte,
	68	swp_entry_to_pte(entry));
	69	}
	70	#endif
1da177e4	71	}
0697212a	72
1da177e4	73	} while (pte++, addr += PAGE_SIZE, addr != end);
6606c3e0	74	arch_leave_lazy_mmu_mode();
705e87c0	75	pte_unmap_unlock(pte - 1, ptl);
1da177e4 LT	76	}
	77
	78	static inline void change_pmd_range(struct mm_struct mm, pud_t pud,
c1e6098b PZ	79	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	80	int dirty_accountable)
1da177e4 LT	81	{
	82	pmd_t *pmd;
	83	unsigned long next;
	84
	85	pmd = pmd_offset(pud, addr);
	86	do {
	87	next = pmd_addr_end(addr, end);
	88	if (pmd_none_or_clear_bad(pmd))
	89	continue;
c1e6098b	90	change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
1da177e4 LT	91	} while (pmd++, addr = next, addr != end);
	92	}
	93
	94	static inline void change_pud_range(struct mm_struct mm, pgd_t pgd,
c1e6098b PZ	95	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	96	int dirty_accountable)
1da177e4 LT	97	{
	98	pud_t *pud;
	99	unsigned long next;
	100
	101	pud = pud_offset(pgd, addr);
	102	do {
	103	next = pud_addr_end(addr, end);
	104	if (pud_none_or_clear_bad(pud))
	105	continue;
c1e6098b	106	change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
1da177e4 LT	107	} while (pud++, addr = next, addr != end);
	108	}
	109
	110	static void change_protection(struct vm_area_struct *vma,
c1e6098b PZ	111	unsigned long addr, unsigned long end, pgprot_t newprot,
c1e6098b PZ	112	int dirty_accountable)
1da177e4 LT	113	{
	114	struct mm_struct *mm = vma->vm_mm;
	115	pgd_t *pgd;
	116	unsigned long next;
	117	unsigned long start = addr;
	118
	119	BUG_ON(addr >= end);
	120	pgd = pgd_offset(mm, addr);
	121	flush_cache_range(vma, addr, end);
1da177e4 LT	122	do {
	123	next = pgd_addr_end(addr, end);
	124	if (pgd_none_or_clear_bad(pgd))
	125	continue;
c1e6098b	126	change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
1da177e4 LT	127	} while (pgd++, addr = next, addr != end);
1da177e4 LT	128	flush_tlb_range(vma, start, end);
1da177e4 LT	129	}
1da177e4 LT	130
b6a2fea3	131	int
1da177e4 LT	132	mprotect_fixup(struct vm_area_struct vma, struct vm_area_struct *pprev,
	133	unsigned long start, unsigned long end, unsigned long newflags)
	134	{
	135	struct mm_struct *mm = vma->vm_mm;
	136	unsigned long oldflags = vma->vm_flags;
	137	long nrpages = (end - start) >> PAGE_SHIFT;
	138	unsigned long charged = 0;
1da177e4 LT	139	pgoff_t pgoff;
1da177e4 LT	140	int error;
c1e6098b	141	int dirty_accountable = 0;
1da177e4 LT	142
	143	if (newflags == oldflags) {
	144	*pprev = vma;
	145	return 0;
	146	}
	147
	148	/*
	149	* If we make a private mapping writable we increase our commit;
	150	* but (without finer accounting) cannot reduce our commit if we
	151	* make it unwritable again.
	152	*
	153	* FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
	154	* a MAP_NORESERVE private mapping to writable will now reserve.
	155	*/
	156	if (newflags & VM_WRITE) {
8f860591	157	if (!(oldflags & (VM_ACCOUNT\|VM_WRITE\|VM_SHARED))) {
1da177e4 LT	158	charged = nrpages;
	159	if (security_vm_enough_memory(charged))
	160	return -ENOMEM;
	161	newflags \|= VM_ACCOUNT;
	162	}
	163	}
	164
1da177e4 LT	165	/*
	166	* First try to merge with previous and/or next vma.
	167	*/
	168	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
	169	pprev = vma_merge(mm, pprev, start, end, newflags,
	170	vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
	171	if (*pprev) {
	172	vma = *pprev;
	173	goto success;
	174	}
	175
	176	*pprev = vma;
	177
	178	if (start != vma->vm_start) {
	179	error = split_vma(mm, vma, start, 1);
	180	if (error)
	181	goto fail;
	182	}
	183
	184	if (end != vma->vm_end) {
	185	error = split_vma(mm, vma, end, 0);
	186	if (error)
	187	goto fail;
	188	}
	189
	190	success:
	191	/*
	192	* vm_flags and vm_page_prot are protected by the mmap_sem
	193	* held in write mode.
	194	*/
	195	vma->vm_flags = newflags;
d08b3851 PZ	196	vma->vm_page_prot = protection_map[newflags &
d08b3851 PZ	197	(VM_READ\|VM_WRITE\|VM_EXEC\|VM_SHARED)];
c1e6098b	198	if (vma_wants_writenotify(vma)) {
d08b3851 PZ	199	vma->vm_page_prot = protection_map[newflags &
d08b3851 PZ	200	(VM_READ\|VM_WRITE\|VM_EXEC)];
c1e6098b PZ	201	dirty_accountable = 1;
c1e6098b PZ	202	}
d08b3851	203
8f860591	204	if (is_vm_hugetlb_page(vma))
d08b3851	205	hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
8f860591	206	else
c1e6098b	207	change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
ab50b8ed HD	208	vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
ab50b8ed HD	209	vm_stat_account(mm, newflags, vma->vm_file, nrpages);
1da177e4 LT	210	return 0;
	211
	212	fail:
	213	vm_unacct_memory(charged);
	214	return error;
	215	}
	216
	217	asmlinkage long
	218	sys_mprotect(unsigned long start, size_t len, unsigned long prot)
	219	{
	220	unsigned long vm_flags, nstart, end, tmp, reqprot;
	221	struct vm_area_struct vma, prev;
	222	int error = -EINVAL;
	223	const int grows = prot & (PROT_GROWSDOWN\|PROT_GROWSUP);
	224	prot &= ~(PROT_GROWSDOWN\|PROT_GROWSUP);
	225	if (grows == (PROT_GROWSDOWN\|PROT_GROWSUP)) /* can't be both */
	226	return -EINVAL;
	227
	228	if (start & ~PAGE_MASK)
	229	return -EINVAL;
	230	if (!len)
	231	return 0;
	232	len = PAGE_ALIGN(len);
	233	end = start + len;
	234	if (end <= start)
	235	return -ENOMEM;
	236	if (prot & ~(PROT_READ \| PROT_WRITE \| PROT_EXEC \| PROT_SEM))
	237	return -EINVAL;
	238
	239	reqprot = prot;
	240	/*
	241	* Does the application expect PROT_READ to imply PROT_EXEC:
	242	*/
b344e05c	243	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1da177e4 LT	244	prot \|= PROT_EXEC;
	245
	246	vm_flags = calc_vm_prot_bits(prot);
	247
	248	down_write(&current->mm->mmap_sem);
	249
	250	vma = find_vma_prev(current->mm, start, &prev);
	251	error = -ENOMEM;
	252	if (!vma)
	253	goto out;
	254	if (unlikely(grows & PROT_GROWSDOWN)) {
	255	if (vma->vm_start >= end)
	256	goto out;
	257	start = vma->vm_start;
	258	error = -EINVAL;
	259	if (!(vma->vm_flags & VM_GROWSDOWN))
	260	goto out;
	261	}
	262	else {
	263	if (vma->vm_start > start)
	264	goto out;
	265	if (unlikely(grows & PROT_GROWSUP)) {
	266	end = vma->vm_end;
	267	error = -EINVAL;
	268	if (!(vma->vm_flags & VM_GROWSUP))
	269	goto out;
	270	}
	271	}
	272	if (start > vma->vm_start)
	273	prev = vma;
	274
	275	for (nstart = start ; ; ) {
	276	unsigned long newflags;
	277
	278	/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
	279
1da177e4 LT	280	newflags = vm_flags \| (vma->vm_flags & ~(VM_READ \| VM_WRITE \| VM_EXEC));
1da177e4 LT	281
7e2cff42 PBG	282	/* newflags >> 4 shift VM_MAY% in place of VM_% */
7e2cff42 PBG	283	if ((newflags & ~(newflags >> 4)) & (VM_READ \| VM_WRITE \| VM_EXEC)) {
1da177e4 LT	284	error = -EACCES;
	285	goto out;
	286	}
	287
	288	error = security_file_mprotect(vma, reqprot, prot);
	289	if (error)
	290	goto out;
	291
	292	tmp = vma->vm_end;
	293	if (tmp > end)
	294	tmp = end;
	295	error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
	296	if (error)
	297	goto out;
	298	nstart = tmp;
	299
	300	if (nstart < prev->vm_end)
	301	nstart = prev->vm_end;
	302	if (nstart >= end)
	303	goto out;
	304
	305	vma = prev->vm_next;
	306	if (!vma \|\| vma->vm_start != nstart) {
	307	error = -ENOMEM;
	308	goto out;
	309	}
	310	}
	311	out:
	312	up_write(&current->mm->mmap_sem);
	313	return error;
	314	}