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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - mm/mprotect.c
4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
7 * Address space accounting code <alan@redhat.com>
8 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
12 #include <linux/hugetlb.h>
13 #include <linux/slab.h>
14 #include <linux/shm.h>
15 #include <linux/mman.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>
22 #include <linux/swap.h>
23 #include <linux/swapops.h>
24 #include <asm/uaccess.h>
25 #include <asm/pgtable.h>
26 #include <asm/cacheflush.h>
27 #include <asm/tlbflush.h>
30 static inline pgprot_t
pgprot_modify(pgprot_t oldprot
, pgprot_t newprot
)
36 static void change_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
37 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
38 int dirty_accountable
)
43 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
44 arch_enter_lazy_mmu_mode();
47 if (pte_present(oldpte
)) {
50 ptent
= ptep_modify_prot_start(mm
, addr
, pte
);
51 ptent
= pte_modify(ptent
, newprot
);
54 * Avoid taking write faults for pages we know to be
57 if (dirty_accountable
&& pte_dirty(ptent
))
58 ptent
= pte_mkwrite(ptent
);
60 ptep_modify_prot_commit(mm
, addr
, pte
, ptent
);
61 #ifdef CONFIG_MIGRATION
62 } else if (!pte_file(oldpte
)) {
63 swp_entry_t entry
= pte_to_swp_entry(oldpte
);
65 if (is_write_migration_entry(entry
)) {
67 * A protection check is difficult so
68 * just be safe and disable write
70 make_migration_entry_read(&entry
);
71 set_pte_at(mm
, addr
, pte
,
72 swp_entry_to_pte(entry
));
77 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
78 arch_leave_lazy_mmu_mode();
79 pte_unmap_unlock(pte
- 1, ptl
);
82 static inline void change_pmd_range(struct mm_struct
*mm
, pud_t
*pud
,
83 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
84 int dirty_accountable
)
89 pmd
= pmd_offset(pud
, addr
);
91 next
= pmd_addr_end(addr
, end
);
92 if (pmd_none_or_clear_bad(pmd
))
94 change_pte_range(mm
, pmd
, addr
, next
, newprot
, dirty_accountable
);
95 } while (pmd
++, addr
= next
, addr
!= end
);
98 static inline void change_pud_range(struct mm_struct
*mm
, pgd_t
*pgd
,
99 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
100 int dirty_accountable
)
105 pud
= pud_offset(pgd
, addr
);
107 next
= pud_addr_end(addr
, end
);
108 if (pud_none_or_clear_bad(pud
))
110 change_pmd_range(mm
, pud
, addr
, next
, newprot
, dirty_accountable
);
111 } while (pud
++, addr
= next
, addr
!= end
);
114 static void change_protection(struct vm_area_struct
*vma
,
115 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
116 int dirty_accountable
)
118 struct mm_struct
*mm
= vma
->vm_mm
;
121 unsigned long start
= addr
;
124 pgd
= pgd_offset(mm
, addr
);
125 flush_cache_range(vma
, addr
, end
);
127 next
= pgd_addr_end(addr
, end
);
128 if (pgd_none_or_clear_bad(pgd
))
130 change_pud_range(mm
, pgd
, addr
, next
, newprot
, dirty_accountable
);
131 } while (pgd
++, addr
= next
, addr
!= end
);
132 flush_tlb_range(vma
, start
, end
);
136 mprotect_fixup(struct vm_area_struct
*vma
, struct vm_area_struct
**pprev
,
137 unsigned long start
, unsigned long end
, unsigned long newflags
)
139 struct mm_struct
*mm
= vma
->vm_mm
;
140 unsigned long oldflags
= vma
->vm_flags
;
141 long nrpages
= (end
- start
) >> PAGE_SHIFT
;
142 unsigned long charged
= 0;
145 int dirty_accountable
= 0;
147 if (newflags
== oldflags
) {
153 * If we make a private mapping writable we increase our commit;
154 * but (without finer accounting) cannot reduce our commit if we
155 * make it unwritable again.
157 * FIXME? We haven't defined a VM_NORESERVE flag, so mprotecting
158 * a MAP_NORESERVE private mapping to writable will now reserve.
160 if (newflags
& VM_WRITE
) {
161 if (!(oldflags
& (VM_ACCOUNT
|VM_WRITE
|VM_SHARED
))) {
163 if (security_vm_enough_memory(charged
))
165 newflags
|= VM_ACCOUNT
;
170 * First try to merge with previous and/or next vma.
172 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
173 *pprev
= vma_merge(mm
, *pprev
, start
, end
, newflags
,
174 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
));
182 if (start
!= vma
->vm_start
) {
183 error
= split_vma(mm
, vma
, start
, 1);
188 if (end
!= vma
->vm_end
) {
189 error
= split_vma(mm
, vma
, end
, 0);
196 * vm_flags and vm_page_prot are protected by the mmap_sem
197 * held in write mode.
199 vma
->vm_flags
= newflags
;
200 vma
->vm_page_prot
= pgprot_modify(vma
->vm_page_prot
,
201 vm_get_page_prot(newflags
));
203 if (vma_wants_writenotify(vma
)) {
204 vma
->vm_page_prot
= vm_get_page_prot(newflags
& ~VM_SHARED
);
205 dirty_accountable
= 1;
208 if (is_vm_hugetlb_page(vma
))
209 hugetlb_change_protection(vma
, start
, end
, vma
->vm_page_prot
);
211 change_protection(vma
, start
, end
, vma
->vm_page_prot
, dirty_accountable
);
212 vm_stat_account(mm
, oldflags
, vma
->vm_file
, -nrpages
);
213 vm_stat_account(mm
, newflags
, vma
->vm_file
, nrpages
);
217 vm_unacct_memory(charged
);
222 sys_mprotect(unsigned long start
, size_t len
, unsigned long prot
)
224 unsigned long vm_flags
, nstart
, end
, tmp
, reqprot
;
225 struct vm_area_struct
*vma
, *prev
;
227 const int grows
= prot
& (PROT_GROWSDOWN
|PROT_GROWSUP
);
228 prot
&= ~(PROT_GROWSDOWN
|PROT_GROWSUP
);
229 if (grows
== (PROT_GROWSDOWN
|PROT_GROWSUP
)) /* can't be both */
232 if (start
& ~PAGE_MASK
)
236 len
= PAGE_ALIGN(len
);
240 if (!arch_validate_prot(prot
))
245 * Does the application expect PROT_READ to imply PROT_EXEC:
247 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
250 vm_flags
= calc_vm_prot_bits(prot
);
252 down_write(¤t
->mm
->mmap_sem
);
254 vma
= find_vma_prev(current
->mm
, start
, &prev
);
258 if (unlikely(grows
& PROT_GROWSDOWN
)) {
259 if (vma
->vm_start
>= end
)
261 start
= vma
->vm_start
;
263 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
267 if (vma
->vm_start
> start
)
269 if (unlikely(grows
& PROT_GROWSUP
)) {
272 if (!(vma
->vm_flags
& VM_GROWSUP
))
276 if (start
> vma
->vm_start
)
279 for (nstart
= start
; ; ) {
280 unsigned long newflags
;
282 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
284 newflags
= vm_flags
| (vma
->vm_flags
& ~(VM_READ
| VM_WRITE
| VM_EXEC
));
286 /* newflags >> 4 shift VM_MAY% in place of VM_% */
287 if ((newflags
& ~(newflags
>> 4)) & (VM_READ
| VM_WRITE
| VM_EXEC
)) {
292 error
= security_file_mprotect(vma
, reqprot
, prot
);
299 error
= mprotect_fixup(vma
, &prev
, nstart
, tmp
, newflags
);
304 if (nstart
< prev
->vm_end
)
305 nstart
= prev
->vm_end
;
310 if (!vma
|| vma
->vm_start
!= nstart
) {
316 up_write(¤t
->mm
->mmap_sem
);