]>
git.ipfire.org Git - thirdparty/kernel/stable.git/blob - mm/mprotect.c
1 // SPDX-License-Identifier: GPL-2.0
5 * (C) Copyright 1994 Linus Torvalds
6 * (C) Copyright 2002 Christoph Hellwig
8 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
13 #include <linux/hugetlb.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 <linux/mmu_notifier.h>
25 #include <linux/migrate.h>
26 #include <linux/perf_event.h>
27 #include <linux/pkeys.h>
28 #include <linux/ksm.h>
29 #include <linux/uaccess.h>
30 #include <linux/mm_inline.h>
31 #include <asm/pgtable.h>
32 #include <asm/cacheflush.h>
33 #include <asm/mmu_context.h>
34 #include <asm/tlbflush.h>
38 static unsigned long change_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
39 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
40 int dirty_accountable
, int prot_numa
)
42 struct mm_struct
*mm
= vma
->vm_mm
;
45 unsigned long pages
= 0;
46 int target_node
= NUMA_NO_NODE
;
49 * Can be called with only the mmap_sem for reading by
50 * prot_numa so we must check the pmd isn't constantly
51 * changing from under us from pmd_none to pmd_trans_huge
52 * and/or the other way around.
54 if (pmd_trans_unstable(pmd
))
58 * The pmd points to a regular pte so the pmd can't change
59 * from under us even if the mmap_sem is only hold for
62 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
64 /* Get target node for single threaded private VMAs */
65 if (prot_numa
&& !(vma
->vm_flags
& VM_SHARED
) &&
66 atomic_read(&vma
->vm_mm
->mm_users
) == 1)
67 target_node
= numa_node_id();
69 flush_tlb_batched_pending(vma
->vm_mm
);
70 arch_enter_lazy_mmu_mode();
73 if (pte_present(oldpte
)) {
75 bool preserve_write
= prot_numa
&& pte_write(oldpte
);
78 * Avoid trapping faults against the zero or KSM
79 * pages. See similar comment in change_huge_pmd.
84 page
= vm_normal_page(vma
, addr
, oldpte
);
85 if (!page
|| PageKsm(page
))
88 /* Also skip shared copy-on-write pages */
89 if (is_cow_mapping(vma
->vm_flags
) &&
90 page_mapcount(page
) != 1)
94 * While migration can move some dirty pages,
95 * it cannot move them all from MIGRATE_ASYNC
98 if (page_is_file_cache(page
) && PageDirty(page
))
101 /* Avoid TLB flush if possible */
102 if (pte_protnone(oldpte
))
106 * Don't mess with PTEs if page is already on the node
107 * a single-threaded process is running on.
109 if (target_node
== page_to_nid(page
))
113 ptent
= ptep_modify_prot_start(mm
, addr
, pte
);
114 ptent
= pte_modify(ptent
, newprot
);
116 ptent
= pte_mk_savedwrite(ptent
);
118 /* Avoid taking write faults for known dirty pages */
119 if (dirty_accountable
&& pte_dirty(ptent
) &&
120 (pte_soft_dirty(ptent
) ||
121 !(vma
->vm_flags
& VM_SOFTDIRTY
))) {
122 ptent
= pte_mkwrite(ptent
);
124 ptep_modify_prot_commit(mm
, addr
, pte
, ptent
);
126 } else if (IS_ENABLED(CONFIG_MIGRATION
)) {
127 swp_entry_t entry
= pte_to_swp_entry(oldpte
);
129 if (is_write_migration_entry(entry
)) {
132 * A protection check is difficult so
133 * just be safe and disable write
135 make_migration_entry_read(&entry
);
136 newpte
= swp_entry_to_pte(entry
);
137 if (pte_swp_soft_dirty(oldpte
))
138 newpte
= pte_swp_mksoft_dirty(newpte
);
139 set_pte_at(mm
, addr
, pte
, newpte
);
144 if (is_write_device_private_entry(entry
)) {
148 * We do not preserve soft-dirtiness. See
149 * copy_one_pte() for explanation.
151 make_device_private_entry_read(&entry
);
152 newpte
= swp_entry_to_pte(entry
);
153 set_pte_at(mm
, addr
, pte
, newpte
);
158 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
159 arch_leave_lazy_mmu_mode();
160 pte_unmap_unlock(pte
- 1, ptl
);
165 static inline unsigned long change_pmd_range(struct vm_area_struct
*vma
,
166 pud_t
*pud
, unsigned long addr
, unsigned long end
,
167 pgprot_t newprot
, int dirty_accountable
, int prot_numa
)
171 unsigned long pages
= 0;
172 unsigned long nr_huge_updates
= 0;
173 struct mmu_notifier_range range
;
177 pmd
= pmd_offset(pud
, addr
);
179 unsigned long this_pages
;
181 next
= pmd_addr_end(addr
, end
);
182 if (!is_swap_pmd(*pmd
) && !pmd_trans_huge(*pmd
) && !pmd_devmap(*pmd
)
183 && pmd_none_or_clear_bad(pmd
))
186 /* invoke the mmu notifier if the pmd is populated */
188 mmu_notifier_range_init(&range
, vma
->vm_mm
, addr
, end
);
189 mmu_notifier_invalidate_range_start(&range
);
192 if (is_swap_pmd(*pmd
) || pmd_trans_huge(*pmd
) || pmd_devmap(*pmd
)) {
193 if (next
- addr
!= HPAGE_PMD_SIZE
) {
194 __split_huge_pmd(vma
, pmd
, addr
, false, NULL
);
196 int nr_ptes
= change_huge_pmd(vma
, pmd
, addr
,
200 if (nr_ptes
== HPAGE_PMD_NR
) {
201 pages
+= HPAGE_PMD_NR
;
205 /* huge pmd was handled */
209 /* fall through, the trans huge pmd just split */
211 this_pages
= change_pte_range(vma
, pmd
, addr
, next
, newprot
,
212 dirty_accountable
, prot_numa
);
216 } while (pmd
++, addr
= next
, addr
!= end
);
219 mmu_notifier_invalidate_range_end(&range
);
222 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES
, nr_huge_updates
);
226 static inline unsigned long change_pud_range(struct vm_area_struct
*vma
,
227 p4d_t
*p4d
, unsigned long addr
, unsigned long end
,
228 pgprot_t newprot
, int dirty_accountable
, int prot_numa
)
232 unsigned long pages
= 0;
234 pud
= pud_offset(p4d
, addr
);
236 next
= pud_addr_end(addr
, end
);
237 if (pud_none_or_clear_bad(pud
))
239 pages
+= change_pmd_range(vma
, pud
, addr
, next
, newprot
,
240 dirty_accountable
, prot_numa
);
241 } while (pud
++, addr
= next
, addr
!= end
);
246 static inline unsigned long change_p4d_range(struct vm_area_struct
*vma
,
247 pgd_t
*pgd
, unsigned long addr
, unsigned long end
,
248 pgprot_t newprot
, int dirty_accountable
, int prot_numa
)
252 unsigned long pages
= 0;
254 p4d
= p4d_offset(pgd
, addr
);
256 next
= p4d_addr_end(addr
, end
);
257 if (p4d_none_or_clear_bad(p4d
))
259 pages
+= change_pud_range(vma
, p4d
, addr
, next
, newprot
,
260 dirty_accountable
, prot_numa
);
261 } while (p4d
++, addr
= next
, addr
!= end
);
266 static unsigned long change_protection_range(struct vm_area_struct
*vma
,
267 unsigned long addr
, unsigned long end
, pgprot_t newprot
,
268 int dirty_accountable
, int prot_numa
)
270 struct mm_struct
*mm
= vma
->vm_mm
;
273 unsigned long start
= addr
;
274 unsigned long pages
= 0;
277 pgd
= pgd_offset(mm
, addr
);
278 flush_cache_range(vma
, addr
, end
);
279 inc_tlb_flush_pending(mm
);
281 next
= pgd_addr_end(addr
, end
);
282 if (pgd_none_or_clear_bad(pgd
))
284 pages
+= change_p4d_range(vma
, pgd
, addr
, next
, newprot
,
285 dirty_accountable
, prot_numa
);
286 } while (pgd
++, addr
= next
, addr
!= end
);
288 /* Only flush the TLB if we actually modified any entries: */
290 flush_tlb_range(vma
, start
, end
);
291 dec_tlb_flush_pending(mm
);
296 unsigned long change_protection(struct vm_area_struct
*vma
, unsigned long start
,
297 unsigned long end
, pgprot_t newprot
,
298 int dirty_accountable
, int prot_numa
)
302 if (is_vm_hugetlb_page(vma
))
303 pages
= hugetlb_change_protection(vma
, start
, end
, newprot
);
305 pages
= change_protection_range(vma
, start
, end
, newprot
, dirty_accountable
, prot_numa
);
310 static int prot_none_pte_entry(pte_t
*pte
, unsigned long addr
,
311 unsigned long next
, struct mm_walk
*walk
)
313 return pfn_modify_allowed(pte_pfn(*pte
), *(pgprot_t
*)(walk
->private)) ?
317 static int prot_none_hugetlb_entry(pte_t
*pte
, unsigned long hmask
,
318 unsigned long addr
, unsigned long next
,
319 struct mm_walk
*walk
)
321 return pfn_modify_allowed(pte_pfn(*pte
), *(pgprot_t
*)(walk
->private)) ?
325 static int prot_none_test(unsigned long addr
, unsigned long next
,
326 struct mm_walk
*walk
)
331 static int prot_none_walk(struct vm_area_struct
*vma
, unsigned long start
,
332 unsigned long end
, unsigned long newflags
)
334 pgprot_t new_pgprot
= vm_get_page_prot(newflags
);
335 struct mm_walk prot_none_walk
= {
336 .pte_entry
= prot_none_pte_entry
,
337 .hugetlb_entry
= prot_none_hugetlb_entry
,
338 .test_walk
= prot_none_test
,
340 .private = &new_pgprot
,
343 return walk_page_range(start
, end
, &prot_none_walk
);
347 mprotect_fixup(struct vm_area_struct
*vma
, struct vm_area_struct
**pprev
,
348 unsigned long start
, unsigned long end
, unsigned long newflags
)
350 struct mm_struct
*mm
= vma
->vm_mm
;
351 unsigned long oldflags
= vma
->vm_flags
;
352 long nrpages
= (end
- start
) >> PAGE_SHIFT
;
353 unsigned long charged
= 0;
356 int dirty_accountable
= 0;
358 if (newflags
== oldflags
) {
364 * Do PROT_NONE PFN permission checks here when we can still
365 * bail out without undoing a lot of state. This is a rather
366 * uncommon case, so doesn't need to be very optimized.
368 if (arch_has_pfn_modify_check() &&
369 (vma
->vm_flags
& (VM_PFNMAP
|VM_MIXEDMAP
)) &&
370 (newflags
& (VM_READ
|VM_WRITE
|VM_EXEC
)) == 0) {
371 error
= prot_none_walk(vma
, start
, end
, newflags
);
377 * If we make a private mapping writable we increase our commit;
378 * but (without finer accounting) cannot reduce our commit if we
379 * make it unwritable again. hugetlb mapping were accounted for
380 * even if read-only so there is no need to account for them here
382 if (newflags
& VM_WRITE
) {
383 /* Check space limits when area turns into data. */
384 if (!may_expand_vm(mm
, newflags
, nrpages
) &&
385 may_expand_vm(mm
, oldflags
, nrpages
))
387 if (!(oldflags
& (VM_ACCOUNT
|VM_WRITE
|VM_HUGETLB
|
388 VM_SHARED
|VM_NORESERVE
))) {
390 if (security_vm_enough_memory_mm(mm
, charged
))
392 newflags
|= VM_ACCOUNT
;
397 * First try to merge with previous and/or next vma.
399 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
400 *pprev
= vma_merge(mm
, *pprev
, start
, end
, newflags
,
401 vma
->anon_vma
, vma
->vm_file
, pgoff
, vma_policy(vma
),
402 vma
->vm_userfaultfd_ctx
);
405 VM_WARN_ON((vma
->vm_flags
^ newflags
) & ~VM_SOFTDIRTY
);
411 if (start
!= vma
->vm_start
) {
412 error
= split_vma(mm
, vma
, start
, 1);
417 if (end
!= vma
->vm_end
) {
418 error
= split_vma(mm
, vma
, end
, 0);
425 * vm_flags and vm_page_prot are protected by the mmap_sem
426 * held in write mode.
428 vma
->vm_flags
= newflags
;
429 dirty_accountable
= vma_wants_writenotify(vma
, vma
->vm_page_prot
);
430 vma_set_page_prot(vma
);
432 change_protection(vma
, start
, end
, vma
->vm_page_prot
,
433 dirty_accountable
, 0);
436 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
439 if ((oldflags
& (VM_WRITE
| VM_SHARED
| VM_LOCKED
)) == VM_LOCKED
&&
440 (newflags
& VM_WRITE
)) {
441 populate_vma_page_range(vma
, start
, end
, NULL
);
444 vm_stat_account(mm
, oldflags
, -nrpages
);
445 vm_stat_account(mm
, newflags
, nrpages
);
446 perf_event_mmap(vma
);
450 vm_unacct_memory(charged
);
455 * pkey==-1 when doing a legacy mprotect()
457 static int do_mprotect_pkey(unsigned long start
, size_t len
,
458 unsigned long prot
, int pkey
)
460 unsigned long nstart
, end
, tmp
, reqprot
;
461 struct vm_area_struct
*vma
, *prev
;
463 const int grows
= prot
& (PROT_GROWSDOWN
|PROT_GROWSUP
);
464 const bool rier
= (current
->personality
& READ_IMPLIES_EXEC
) &&
467 prot
&= ~(PROT_GROWSDOWN
|PROT_GROWSUP
);
468 if (grows
== (PROT_GROWSDOWN
|PROT_GROWSUP
)) /* can't be both */
471 if (start
& ~PAGE_MASK
)
475 len
= PAGE_ALIGN(len
);
479 if (!arch_validate_prot(prot
, start
))
484 if (down_write_killable(¤t
->mm
->mmap_sem
))
488 * If userspace did not allocate the pkey, do not let
492 if ((pkey
!= -1) && !mm_pkey_is_allocated(current
->mm
, pkey
))
495 vma
= find_vma(current
->mm
, start
);
500 if (unlikely(grows
& PROT_GROWSDOWN
)) {
501 if (vma
->vm_start
>= end
)
503 start
= vma
->vm_start
;
505 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
508 if (vma
->vm_start
> start
)
510 if (unlikely(grows
& PROT_GROWSUP
)) {
513 if (!(vma
->vm_flags
& VM_GROWSUP
))
517 if (start
> vma
->vm_start
)
520 for (nstart
= start
; ; ) {
521 unsigned long mask_off_old_flags
;
522 unsigned long newflags
;
525 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
527 /* Does the application expect PROT_READ to imply PROT_EXEC */
528 if (rier
&& (vma
->vm_flags
& VM_MAYEXEC
))
532 * Each mprotect() call explicitly passes r/w/x permissions.
533 * If a permission is not passed to mprotect(), it must be
534 * cleared from the VMA.
536 mask_off_old_flags
= VM_READ
| VM_WRITE
| VM_EXEC
|
539 new_vma_pkey
= arch_override_mprotect_pkey(vma
, prot
, pkey
);
540 newflags
= calc_vm_prot_bits(prot
, new_vma_pkey
);
541 newflags
|= (vma
->vm_flags
& ~mask_off_old_flags
);
543 /* newflags >> 4 shift VM_MAY% in place of VM_% */
544 if ((newflags
& ~(newflags
>> 4)) & (VM_READ
| VM_WRITE
| VM_EXEC
)) {
549 error
= security_file_mprotect(vma
, reqprot
, prot
);
556 error
= mprotect_fixup(vma
, &prev
, nstart
, tmp
, newflags
);
561 if (nstart
< prev
->vm_end
)
562 nstart
= prev
->vm_end
;
567 if (!vma
|| vma
->vm_start
!= nstart
) {
574 up_write(¤t
->mm
->mmap_sem
);
578 SYSCALL_DEFINE3(mprotect
, unsigned long, start
, size_t, len
,
581 return do_mprotect_pkey(start
, len
, prot
, -1);
584 #ifdef CONFIG_ARCH_HAS_PKEYS
586 SYSCALL_DEFINE4(pkey_mprotect
, unsigned long, start
, size_t, len
,
587 unsigned long, prot
, int, pkey
)
589 return do_mprotect_pkey(start
, len
, prot
, pkey
);
592 SYSCALL_DEFINE2(pkey_alloc
, unsigned long, flags
, unsigned long, init_val
)
597 /* No flags supported yet. */
600 /* check for unsupported init values */
601 if (init_val
& ~PKEY_ACCESS_MASK
)
604 down_write(¤t
->mm
->mmap_sem
);
605 pkey
= mm_pkey_alloc(current
->mm
);
611 ret
= arch_set_user_pkey_access(current
, pkey
, init_val
);
613 mm_pkey_free(current
->mm
, pkey
);
618 up_write(¤t
->mm
->mmap_sem
);
622 SYSCALL_DEFINE1(pkey_free
, int, pkey
)
626 down_write(¤t
->mm
->mmap_sem
);
627 ret
= mm_pkey_free(current
->mm
, pkey
);
628 up_write(¤t
->mm
->mmap_sem
);
631 * We could provie warnings or errors if any VMA still
632 * has the pkey set here.
637 #endif /* CONFIG_ARCH_HAS_PKEYS */