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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - mm/mprotect.c
4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
12 #include <linux/hugetlb.h>
13 #include <linux/shm.h>
14 #include <linux/mman.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>
21 #include <linux/swap.h>
22 #include <linux/swapops.h>
23 #include <linux/mmu_notifier.h>
24 #include <linux/migrate.h>
25 #include <linux/perf_event.h>
26 #include <asm/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/cacheflush.h>
29 #include <asm/tlbflush.h>
32 static inline pgprot_t
pgprot_modify(pgprot_t oldprot
, pgprot_t newprot
)
38 static void change_pte_range(struct mm_struct
*mm
, pmd_t
*pmd
,
39 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
40 int dirty_accountable
)
45 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
46 arch_enter_lazy_mmu_mode();
49 if (pte_present(oldpte
)) {
52 ptent
= ptep_modify_prot_start(mm
, addr
, pte
);
53 ptent
= pte_modify(ptent
, newprot
);
56 * Avoid taking write faults for pages we know to be
59 if (dirty_accountable
&& pte_dirty(ptent
))
60 ptent
= pte_mkwrite(ptent
);
62 ptep_modify_prot_commit(mm
, addr
, pte
, ptent
);
63 } else if (IS_ENABLED(CONFIG_MIGRATION
) && !pte_file(oldpte
)) {
64 swp_entry_t entry
= pte_to_swp_entry(oldpte
);
66 if (is_write_migration_entry(entry
)) {
68 * A protection check is difficult so
69 * just be safe and disable write
71 make_migration_entry_read(&entry
);
72 set_pte_at(mm
, addr
, pte
,
73 swp_entry_to_pte(entry
));
76 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
77 arch_leave_lazy_mmu_mode();
78 pte_unmap_unlock(pte
- 1, ptl
);
81 static inline void change_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
82 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
83 int dirty_accountable
)
88 pmd
= pmd_offset(pud
, addr
);
90 next
= pmd_addr_end(addr
, end
);
91 if (pmd_trans_huge(*pmd
)) {
92 if (next
- addr
!= HPAGE_PMD_SIZE
)
93 split_huge_page_pmd(vma
, addr
, pmd
);
94 else if (change_huge_pmd(vma
, pmd
, addr
, newprot
))
98 if (pmd_none_or_clear_bad(pmd
))
100 change_pte_range(vma
->vm_mm
, pmd
, addr
, next
, newprot
,
102 } while (pmd
++, addr
= next
, addr
!= end
);
105 static inline void change_pud_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
106 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
107 int dirty_accountable
)
112 pud
= pud_offset(pgd
, addr
);
114 next
= pud_addr_end(addr
, end
);
115 if (pud_none_or_clear_bad(pud
))
117 change_pmd_range(vma
, pud
, addr
, next
, newprot
,
119 } while (pud
++, addr
= next
, addr
!= end
);
122 static void change_protection(struct vm_area_struct
*vma
,
123 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
124 int dirty_accountable
)
126 struct mm_struct
*mm
= vma
->vm_mm
;
129 unsigned long start
= addr
;
132 pgd
= pgd_offset(mm
, addr
);
133 flush_cache_range(vma
, addr
, end
);
135 next
= pgd_addr_end(addr
, end
);
136 if (pgd_none_or_clear_bad(pgd
))
138 change_pud_range(vma
, pgd
, addr
, next
, newprot
,
140 } while (pgd
++, addr
= next
, addr
!= end
);
141 flush_tlb_range(vma
, start
, end
);
145 mprotect_fixup(struct vm_area_struct
*vma
, struct vm_area_struct
**pprev
,
146 unsigned long start
, unsigned long end
, unsigned long newflags
)
148 struct mm_struct
*mm
= vma
->vm_mm
;
149 unsigned long oldflags
= vma
->vm_flags
;
150 long nrpages
= (end
- start
) >> PAGE_SHIFT
;
151 unsigned long charged
= 0;
154 int dirty_accountable
= 0;
156 if (newflags
== oldflags
) {
162 * If we make a private mapping writable we increase our commit;
163 * but (without finer accounting) cannot reduce our commit if we
164 * make it unwritable again. hugetlb mapping were accounted for
165 * even if read-only so there is no need to account for them here
167 if (newflags
& VM_WRITE
) {
168 if (!(oldflags
& (VM_ACCOUNT
|VM_WRITE
|VM_HUGETLB
|
169 VM_SHARED
|VM_NORESERVE
))) {
171 if (security_vm_enough_memory_mm(mm
, charged
))
173 newflags
|= VM_ACCOUNT
;
178 * First try to merge with previous and/or next vma.
180 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
181 *pprev
= vma_merge(mm
, *pprev
, start
, end
, newflags
,
182 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
));
190 if (start
!= vma
->vm_start
) {
191 error
= split_vma(mm
, vma
, start
, 1);
196 if (end
!= vma
->vm_end
) {
197 error
= split_vma(mm
, vma
, end
, 0);
204 * vm_flags and vm_page_prot are protected by the mmap_sem
205 * held in write mode.
207 vma
->vm_flags
= newflags
;
208 vma
->vm_page_prot
= pgprot_modify(vma
->vm_page_prot
,
209 vm_get_page_prot(newflags
));
211 if (vma_wants_writenotify(vma
)) {
212 vma
->vm_page_prot
= vm_get_page_prot(newflags
& ~VM_SHARED
);
213 dirty_accountable
= 1;
216 mmu_notifier_invalidate_range_start(mm
, start
, end
);
217 if (is_vm_hugetlb_page(vma
))
218 hugetlb_change_protection(vma
, start
, end
, vma
->vm_page_prot
);
220 change_protection(vma
, start
, end
, vma
->vm_page_prot
, dirty_accountable
);
221 mmu_notifier_invalidate_range_end(mm
, start
, end
);
222 vm_stat_account(mm
, oldflags
, vma
->vm_file
, -nrpages
);
223 vm_stat_account(mm
, newflags
, vma
->vm_file
, nrpages
);
224 perf_event_mmap(vma
);
228 vm_unacct_memory(charged
);
232 SYSCALL_DEFINE3(mprotect
, unsigned long, start
, size_t, len
,
235 unsigned long vm_flags
, nstart
, end
, tmp
, reqprot
;
236 struct vm_area_struct
*vma
, *prev
;
238 const int grows
= prot
& (PROT_GROWSDOWN
|PROT_GROWSUP
);
239 prot
&= ~(PROT_GROWSDOWN
|PROT_GROWSUP
);
240 if (grows
== (PROT_GROWSDOWN
|PROT_GROWSUP
)) /* can't be both */
243 if (start
& ~PAGE_MASK
)
247 len
= PAGE_ALIGN(len
);
251 if (!arch_validate_prot(prot
))
256 * Does the application expect PROT_READ to imply PROT_EXEC:
258 if ((prot
& PROT_READ
) && (current
->personality
& READ_IMPLIES_EXEC
))
261 vm_flags
= calc_vm_prot_bits(prot
);
263 down_write(¤t
->mm
->mmap_sem
);
265 vma
= find_vma(current
->mm
, start
);
270 if (unlikely(grows
& PROT_GROWSDOWN
)) {
271 if (vma
->vm_start
>= end
)
273 start
= vma
->vm_start
;
275 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
279 if (vma
->vm_start
> start
)
281 if (unlikely(grows
& PROT_GROWSUP
)) {
284 if (!(vma
->vm_flags
& VM_GROWSUP
))
288 if (start
> vma
->vm_start
)
291 for (nstart
= start
; ; ) {
292 unsigned long newflags
;
294 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
296 newflags
= vm_flags
| (vma
->vm_flags
& ~(VM_READ
| VM_WRITE
| VM_EXEC
));
298 /* newflags >> 4 shift VM_MAY% in place of VM_% */
299 if ((newflags
& ~(newflags
>> 4)) & (VM_READ
| VM_WRITE
| VM_EXEC
)) {
304 error
= security_file_mprotect(vma
, reqprot
, prot
);
311 error
= mprotect_fixup(vma
, &prev
, nstart
, tmp
, newflags
);
316 if (nstart
< prev
->vm_end
)
317 nstart
= prev
->vm_end
;
322 if (!vma
|| vma
->vm_start
!= nstart
) {
328 up_write(¤t
->mm
->mmap_sem
);