Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * mm/mprotect.c
4 *
5 * (C) Copyright 1994 Linus Torvalds
6 * (C) Copyright 2002 Christoph Hellwig
7 *
8 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
10 */
11
12#include <linux/pagewalk.h>
13#include <linux/hugetlb.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>
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>
35
36#include "internal.h"
37
38static 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)
41{
42 pte_t *pte, oldpte;
43 spinlock_t *ptl;
44 unsigned long pages = 0;
45 int target_node = NUMA_NO_NODE;
46
47 /*
48 * Can be called with only the mmap_sem for reading by
49 * prot_numa so we must check the pmd isn't constantly
50 * changing from under us from pmd_none to pmd_trans_huge
51 * and/or the other way around.
52 */
53 if (pmd_trans_unstable(pmd))
54 return 0;
55
56 /*
57 * The pmd points to a regular pte so the pmd can't change
58 * from under us even if the mmap_sem is only hold for
59 * reading.
60 */
61 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
62
63 /* Get target node for single threaded private VMAs */
64 if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
65 atomic_read(&vma->vm_mm->mm_users) == 1)
66 target_node = numa_node_id();
67
68 flush_tlb_batched_pending(vma->vm_mm);
69 arch_enter_lazy_mmu_mode();
70 do {
71 oldpte = *pte;
72 if (pte_present(oldpte)) {
73 pte_t ptent;
74 bool preserve_write = prot_numa && pte_write(oldpte);
75
76 /*
77 * Avoid trapping faults against the zero or KSM
78 * pages. See similar comment in change_huge_pmd.
79 */
80 if (prot_numa) {
81 struct page *page;
82
83 page = vm_normal_page(vma, addr, oldpte);
84 if (!page || PageKsm(page))
85 continue;
86
87 /* Also skip shared copy-on-write pages */
88 if (is_cow_mapping(vma->vm_flags) &&
89 page_mapcount(page) != 1)
90 continue;
91
92 /*
93 * While migration can move some dirty pages,
94 * it cannot move them all from MIGRATE_ASYNC
95 * context.
96 */
97 if (page_is_file_cache(page) && PageDirty(page))
98 continue;
99
100 /* Avoid TLB flush if possible */
101 if (pte_protnone(oldpte))
102 continue;
103
104 /*
105 * Don't mess with PTEs if page is already on the node
106 * a single-threaded process is running on.
107 */
108 if (target_node == page_to_nid(page))
109 continue;
110 }
111
112 oldpte = ptep_modify_prot_start(vma, addr, pte);
113 ptent = pte_modify(oldpte, newprot);
114 if (preserve_write)
115 ptent = pte_mk_savedwrite(ptent);
116
117 /* Avoid taking write faults for known dirty pages */
118 if (dirty_accountable && pte_dirty(ptent) &&
119 (pte_soft_dirty(ptent) ||
120 !(vma->vm_flags & VM_SOFTDIRTY))) {
121 ptent = pte_mkwrite(ptent);
122 }
123 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
124 pages++;
125 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
126 swp_entry_t entry = pte_to_swp_entry(oldpte);
127
128 if (is_write_migration_entry(entry)) {
129 pte_t newpte;
130 /*
131 * A protection check is difficult so
132 * just be safe and disable write
133 */
134 make_migration_entry_read(&entry);
135 newpte = swp_entry_to_pte(entry);
136 if (pte_swp_soft_dirty(oldpte))
137 newpte = pte_swp_mksoft_dirty(newpte);
138 set_pte_at(vma->vm_mm, addr, pte, newpte);
139
140 pages++;
141 }
142
143 if (is_write_device_private_entry(entry)) {
144 pte_t newpte;
145
146 /*
147 * We do not preserve soft-dirtiness. See
148 * copy_one_pte() for explanation.
149 */
150 make_device_private_entry_read(&entry);
151 newpte = swp_entry_to_pte(entry);
152 set_pte_at(vma->vm_mm, addr, pte, newpte);
153
154 pages++;
155 }
156 }
157 } while (pte++, addr += PAGE_SIZE, addr != end);
158 arch_leave_lazy_mmu_mode();
159 pte_unmap_unlock(pte - 1, ptl);
160
161 return pages;
162}
163
164static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
165 pud_t *pud, unsigned long addr, unsigned long end,
166 pgprot_t newprot, int dirty_accountable, int prot_numa)
167{
168 pmd_t *pmd;
169 unsigned long next;
170 unsigned long pages = 0;
171 unsigned long nr_huge_updates = 0;
172 struct mmu_notifier_range range;
173
174 range.start = 0;
175
176 pmd = pmd_offset(pud, addr);
177 do {
178 unsigned long this_pages;
179
180 next = pmd_addr_end(addr, end);
181 if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
182 && pmd_none_or_clear_bad(pmd))
183 goto next;
184
185 /* invoke the mmu notifier if the pmd is populated */
186 if (!range.start) {
187 mmu_notifier_range_init(&range,
188 MMU_NOTIFY_PROTECTION_VMA, 0,
189 vma, vma->vm_mm, addr, end);
190 mmu_notifier_invalidate_range_start(&range);
191 }
192
193 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
194 if (next - addr != HPAGE_PMD_SIZE) {
195 __split_huge_pmd(vma, pmd, addr, false, NULL);
196 } else {
197 int nr_ptes = change_huge_pmd(vma, pmd, addr,
198 newprot, prot_numa);
199
200 if (nr_ptes) {
201 if (nr_ptes == HPAGE_PMD_NR) {
202 pages += HPAGE_PMD_NR;
203 nr_huge_updates++;
204 }
205
206 /* huge pmd was handled */
207 goto next;
208 }
209 }
210 /* fall through, the trans huge pmd just split */
211 }
212 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
213 dirty_accountable, prot_numa);
214 pages += this_pages;
215next:
216 cond_resched();
217 } while (pmd++, addr = next, addr != end);
218
219 if (range.start)
220 mmu_notifier_invalidate_range_end(&range);
221
222 if (nr_huge_updates)
223 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
224 return pages;
225}
226
227static inline unsigned long change_pud_range(struct vm_area_struct *vma,
228 p4d_t *p4d, unsigned long addr, unsigned long end,
229 pgprot_t newprot, int dirty_accountable, int prot_numa)
230{
231 pud_t *pud;
232 unsigned long next;
233 unsigned long pages = 0;
234
235 pud = pud_offset(p4d, addr);
236 do {
237 next = pud_addr_end(addr, end);
238 if (pud_none_or_clear_bad(pud))
239 continue;
240 pages += change_pmd_range(vma, pud, addr, next, newprot,
241 dirty_accountable, prot_numa);
242 } while (pud++, addr = next, addr != end);
243
244 return pages;
245}
246
247static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
248 pgd_t *pgd, unsigned long addr, unsigned long end,
249 pgprot_t newprot, int dirty_accountable, int prot_numa)
250{
251 p4d_t *p4d;
252 unsigned long next;
253 unsigned long pages = 0;
254
255 p4d = p4d_offset(pgd, addr);
256 do {
257 next = p4d_addr_end(addr, end);
258 if (p4d_none_or_clear_bad(p4d))
259 continue;
260 pages += change_pud_range(vma, p4d, addr, next, newprot,
261 dirty_accountable, prot_numa);
262 } while (p4d++, addr = next, addr != end);
263
264 return pages;
265}
266
267static unsigned long change_protection_range(struct vm_area_struct *vma,
268 unsigned long addr, unsigned long end, pgprot_t newprot,
269 int dirty_accountable, int prot_numa)
270{
271 struct mm_struct *mm = vma->vm_mm;
272 pgd_t *pgd;
273 unsigned long next;
274 unsigned long start = addr;
275 unsigned long pages = 0;
276
277 BUG_ON(addr >= end);
278 pgd = pgd_offset(mm, addr);
279 flush_cache_range(vma, addr, end);
280 inc_tlb_flush_pending(mm);
281 do {
282 next = pgd_addr_end(addr, end);
283 if (pgd_none_or_clear_bad(pgd))
284 continue;
285 pages += change_p4d_range(vma, pgd, addr, next, newprot,
286 dirty_accountable, prot_numa);
287 } while (pgd++, addr = next, addr != end);
288
289 /* Only flush the TLB if we actually modified any entries: */
290 if (pages)
291 flush_tlb_range(vma, start, end);
292 dec_tlb_flush_pending(mm);
293
294 return pages;
295}
296
297unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
298 unsigned long end, pgprot_t newprot,
299 int dirty_accountable, int prot_numa)
300{
301 unsigned long pages;
302
303 if (is_vm_hugetlb_page(vma))
304 pages = hugetlb_change_protection(vma, start, end, newprot);
305 else
306 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
307
308 return pages;
309}
310
311static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
312 unsigned long next, struct mm_walk *walk)
313{
314 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
315 0 : -EACCES;
316}
317
318static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
319 unsigned long addr, unsigned long next,
320 struct mm_walk *walk)
321{
322 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
323 0 : -EACCES;
324}
325
326static int prot_none_test(unsigned long addr, unsigned long next,
327 struct mm_walk *walk)
328{
329 return 0;
330}
331
332static const struct mm_walk_ops prot_none_walk_ops = {
333 .pte_entry = prot_none_pte_entry,
334 .hugetlb_entry = prot_none_hugetlb_entry,
335 .test_walk = prot_none_test,
336};
337
338int
339mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
340 unsigned long start, unsigned long end, unsigned long newflags)
341{
342 struct mm_struct *mm = vma->vm_mm;
343 unsigned long oldflags = vma->vm_flags;
344 long nrpages = (end - start) >> PAGE_SHIFT;
345 unsigned long charged = 0;
346 pgoff_t pgoff;
347 int error;
348 int dirty_accountable = 0;
349
350 if (newflags == oldflags) {
351 *pprev = vma;
352 return 0;
353 }
354
355 /*
356 * Do PROT_NONE PFN permission checks here when we can still
357 * bail out without undoing a lot of state. This is a rather
358 * uncommon case, so doesn't need to be very optimized.
359 */
360 if (arch_has_pfn_modify_check() &&
361 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
362 (newflags & (VM_READ|VM_WRITE|VM_EXEC)) == 0) {
363 pgprot_t new_pgprot = vm_get_page_prot(newflags);
364
365 error = walk_page_range(current->mm, start, end,
366 &prot_none_walk_ops, &new_pgprot);
367 if (error)
368 return error;
369 }
370
371 /*
372 * If we make a private mapping writable we increase our commit;
373 * but (without finer accounting) cannot reduce our commit if we
374 * make it unwritable again. hugetlb mapping were accounted for
375 * even if read-only so there is no need to account for them here
376 */
377 if (newflags & VM_WRITE) {
378 /* Check space limits when area turns into data. */
379 if (!may_expand_vm(mm, newflags, nrpages) &&
380 may_expand_vm(mm, oldflags, nrpages))
381 return -ENOMEM;
382 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
383 VM_SHARED|VM_NORESERVE))) {
384 charged = nrpages;
385 if (security_vm_enough_memory_mm(mm, charged))
386 return -ENOMEM;
387 newflags |= VM_ACCOUNT;
388 }
389 }
390
391 /*
392 * First try to merge with previous and/or next vma.
393 */
394 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
395 *pprev = vma_merge(mm, *pprev, start, end, newflags,
396 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
397 vma->vm_userfaultfd_ctx);
398 if (*pprev) {
399 vma = *pprev;
400 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
401 goto success;
402 }
403
404 *pprev = vma;
405
406 if (start != vma->vm_start) {
407 error = split_vma(mm, vma, start, 1);
408 if (error)
409 goto fail;
410 }
411
412 if (end != vma->vm_end) {
413 error = split_vma(mm, vma, end, 0);
414 if (error)
415 goto fail;
416 }
417
418success:
419 /*
420 * vm_flags and vm_page_prot are protected by the mmap_sem
421 * held in write mode.
422 */
423 vma->vm_flags = newflags;
424 dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
425 vma_set_page_prot(vma);
426
427 change_protection(vma, start, end, vma->vm_page_prot,
428 dirty_accountable, 0);
429
430 /*
431 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
432 * fault on access.
433 */
434 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
435 (newflags & VM_WRITE)) {
436 populate_vma_page_range(vma, start, end, NULL);
437 }
438
439 vm_stat_account(mm, oldflags, -nrpages);
440 vm_stat_account(mm, newflags, nrpages);
441 perf_event_mmap(vma);
442 return 0;
443
444fail:
445 vm_unacct_memory(charged);
446 return error;
447}
448
449/*
450 * pkey==-1 when doing a legacy mprotect()
451 */
452static int do_mprotect_pkey(unsigned long start, size_t len,
453 unsigned long prot, int pkey)
454{
455 unsigned long nstart, end, tmp, reqprot;
456 struct vm_area_struct *vma, *prev;
457 int error = -EINVAL;
458 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
459 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
460 (prot & PROT_READ);
461
462 start = untagged_addr(start);
463
464 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
465 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
466 return -EINVAL;
467
468 if (start & ~PAGE_MASK)
469 return -EINVAL;
470 if (!len)
471 return 0;
472 len = PAGE_ALIGN(len);
473 end = start + len;
474 if (end <= start)
475 return -ENOMEM;
476 if (!arch_validate_prot(prot, start))
477 return -EINVAL;
478
479 reqprot = prot;
480
481 if (down_write_killable(¤t->mm->mmap_sem))
482 return -EINTR;
483
484 /*
485 * If userspace did not allocate the pkey, do not let
486 * them use it here.
487 */
488 error = -EINVAL;
489 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
490 goto out;
491
492 vma = find_vma(current->mm, start);
493 error = -ENOMEM;
494 if (!vma)
495 goto out;
496 prev = vma->vm_prev;
497 if (unlikely(grows & PROT_GROWSDOWN)) {
498 if (vma->vm_start >= end)
499 goto out;
500 start = vma->vm_start;
501 error = -EINVAL;
502 if (!(vma->vm_flags & VM_GROWSDOWN))
503 goto out;
504 } else {
505 if (vma->vm_start > start)
506 goto out;
507 if (unlikely(grows & PROT_GROWSUP)) {
508 end = vma->vm_end;
509 error = -EINVAL;
510 if (!(vma->vm_flags & VM_GROWSUP))
511 goto out;
512 }
513 }
514 if (start > vma->vm_start)
515 prev = vma;
516
517 for (nstart = start ; ; ) {
518 unsigned long mask_off_old_flags;
519 unsigned long newflags;
520 int new_vma_pkey;
521
522 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
523
524 /* Does the application expect PROT_READ to imply PROT_EXEC */
525 if (rier && (vma->vm_flags & VM_MAYEXEC))
526 prot |= PROT_EXEC;
527
528 /*
529 * Each mprotect() call explicitly passes r/w/x permissions.
530 * If a permission is not passed to mprotect(), it must be
531 * cleared from the VMA.
532 */
533 mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
534 VM_FLAGS_CLEAR;
535
536 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
537 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
538 newflags |= (vma->vm_flags & ~mask_off_old_flags);
539
540 /* newflags >> 4 shift VM_MAY% in place of VM_% */
541 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
542 error = -EACCES;
543 goto out;
544 }
545
546 error = security_file_mprotect(vma, reqprot, prot);
547 if (error)
548 goto out;
549
550 tmp = vma->vm_end;
551 if (tmp > end)
552 tmp = end;
553 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
554 if (error)
555 goto out;
556 nstart = tmp;
557
558 if (nstart < prev->vm_end)
559 nstart = prev->vm_end;
560 if (nstart >= end)
561 goto out;
562
563 vma = prev->vm_next;
564 if (!vma || vma->vm_start != nstart) {
565 error = -ENOMEM;
566 goto out;
567 }
568 prot = reqprot;
569 }
570out:
571 up_write(¤t->mm->mmap_sem);
572 return error;
573}
574
575SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
576 unsigned long, prot)
577{
578 return do_mprotect_pkey(start, len, prot, -1);
579}
580
581#ifdef CONFIG_ARCH_HAS_PKEYS
582
583SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
584 unsigned long, prot, int, pkey)
585{
586 return do_mprotect_pkey(start, len, prot, pkey);
587}
588
589SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
590{
591 int pkey;
592 int ret;
593
594 /* No flags supported yet. */
595 if (flags)
596 return -EINVAL;
597 /* check for unsupported init values */
598 if (init_val & ~PKEY_ACCESS_MASK)
599 return -EINVAL;
600
601 down_write(¤t->mm->mmap_sem);
602 pkey = mm_pkey_alloc(current->mm);
603
604 ret = -ENOSPC;
605 if (pkey == -1)
606 goto out;
607
608 ret = arch_set_user_pkey_access(current, pkey, init_val);
609 if (ret) {
610 mm_pkey_free(current->mm, pkey);
611 goto out;
612 }
613 ret = pkey;
614out:
615 up_write(¤t->mm->mmap_sem);
616 return ret;
617}
618
619SYSCALL_DEFINE1(pkey_free, int, pkey)
620{
621 int ret;
622
623 down_write(¤t->mm->mmap_sem);
624 ret = mm_pkey_free(current->mm, pkey);
625 up_write(¤t->mm->mmap_sem);
626
627 /*
628 * We could provie warnings or errors if any VMA still
629 * has the pkey set here.
630 */
631 return ret;
632}
633
634#endif /* CONFIG_ARCH_HAS_PKEYS */
1/*
2 * mm/mprotect.c
3 *
4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
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/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>
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 <linux/ksm.h>
27#include <asm/uaccess.h>
28#include <asm/pgtable.h>
29#include <asm/cacheflush.h>
30#include <asm/tlbflush.h>
31
32#ifndef pgprot_modify
33static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
34{
35 return newprot;
36}
37#endif
38
39/*
40 * For a prot_numa update we only hold mmap_sem for read so there is a
41 * potential race with faulting where a pmd was temporarily none. This
42 * function checks for a transhuge pmd under the appropriate lock. It
43 * returns a pte if it was successfully locked or NULL if it raced with
44 * a transhuge insertion.
45 */
46static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
47 unsigned long addr, int prot_numa, spinlock_t **ptl)
48{
49 pte_t *pte;
50 spinlock_t *pmdl;
51
52 /* !prot_numa is protected by mmap_sem held for write */
53 if (!prot_numa)
54 return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
55
56 pmdl = pmd_lock(vma->vm_mm, pmd);
57 if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
58 spin_unlock(pmdl);
59 return NULL;
60 }
61
62 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
63 spin_unlock(pmdl);
64 return pte;
65}
66
67static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
68 unsigned long addr, unsigned long end, pgprot_t newprot,
69 int dirty_accountable, int prot_numa)
70{
71 struct mm_struct *mm = vma->vm_mm;
72 pte_t *pte, oldpte;
73 spinlock_t *ptl;
74 unsigned long pages = 0;
75
76 pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
77 if (!pte)
78 return 0;
79
80 arch_enter_lazy_mmu_mode();
81 do {
82 oldpte = *pte;
83 if (pte_present(oldpte)) {
84 pte_t ptent;
85 bool updated = false;
86
87 if (!prot_numa) {
88 ptent = ptep_modify_prot_start(mm, addr, pte);
89 if (pte_numa(ptent))
90 ptent = pte_mknonnuma(ptent);
91 ptent = pte_modify(ptent, newprot);
92 /*
93 * Avoid taking write faults for pages we
94 * know to be dirty.
95 */
96 if (dirty_accountable && pte_dirty(ptent))
97 ptent = pte_mkwrite(ptent);
98 ptep_modify_prot_commit(mm, addr, pte, ptent);
99 updated = true;
100 } else {
101 struct page *page;
102
103 page = vm_normal_page(vma, addr, oldpte);
104 if (page && !PageKsm(page)) {
105 if (!pte_numa(oldpte)) {
106 ptep_set_numa(mm, addr, pte);
107 updated = true;
108 }
109 }
110 }
111 if (updated)
112 pages++;
113 } else if (IS_ENABLED(CONFIG_MIGRATION) && !pte_file(oldpte)) {
114 swp_entry_t entry = pte_to_swp_entry(oldpte);
115
116 if (is_write_migration_entry(entry)) {
117 pte_t newpte;
118 /*
119 * A protection check is difficult so
120 * just be safe and disable write
121 */
122 make_migration_entry_read(&entry);
123 newpte = swp_entry_to_pte(entry);
124 if (pte_swp_soft_dirty(oldpte))
125 newpte = pte_swp_mksoft_dirty(newpte);
126 set_pte_at(mm, addr, pte, newpte);
127
128 pages++;
129 }
130 }
131 } while (pte++, addr += PAGE_SIZE, addr != end);
132 arch_leave_lazy_mmu_mode();
133 pte_unmap_unlock(pte - 1, ptl);
134
135 return pages;
136}
137
138static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
139 pud_t *pud, unsigned long addr, unsigned long end,
140 pgprot_t newprot, int dirty_accountable, int prot_numa)
141{
142 pmd_t *pmd;
143 struct mm_struct *mm = vma->vm_mm;
144 unsigned long next;
145 unsigned long pages = 0;
146 unsigned long nr_huge_updates = 0;
147 unsigned long mni_start = 0;
148
149 pmd = pmd_offset(pud, addr);
150 do {
151 unsigned long this_pages;
152
153 next = pmd_addr_end(addr, end);
154 if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
155 continue;
156
157 /* invoke the mmu notifier if the pmd is populated */
158 if (!mni_start) {
159 mni_start = addr;
160 mmu_notifier_invalidate_range_start(mm, mni_start, end);
161 }
162
163 if (pmd_trans_huge(*pmd)) {
164 if (next - addr != HPAGE_PMD_SIZE)
165 split_huge_page_pmd(vma, addr, pmd);
166 else {
167 int nr_ptes = change_huge_pmd(vma, pmd, addr,
168 newprot, prot_numa);
169
170 if (nr_ptes) {
171 if (nr_ptes == HPAGE_PMD_NR) {
172 pages += HPAGE_PMD_NR;
173 nr_huge_updates++;
174 }
175
176 /* huge pmd was handled */
177 continue;
178 }
179 }
180 /* fall through, the trans huge pmd just split */
181 }
182 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
183 dirty_accountable, prot_numa);
184 pages += this_pages;
185 } while (pmd++, addr = next, addr != end);
186
187 if (mni_start)
188 mmu_notifier_invalidate_range_end(mm, mni_start, end);
189
190 if (nr_huge_updates)
191 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
192 return pages;
193}
194
195static inline unsigned long change_pud_range(struct vm_area_struct *vma,
196 pgd_t *pgd, unsigned long addr, unsigned long end,
197 pgprot_t newprot, int dirty_accountable, int prot_numa)
198{
199 pud_t *pud;
200 unsigned long next;
201 unsigned long pages = 0;
202
203 pud = pud_offset(pgd, addr);
204 do {
205 next = pud_addr_end(addr, end);
206 if (pud_none_or_clear_bad(pud))
207 continue;
208 pages += change_pmd_range(vma, pud, addr, next, newprot,
209 dirty_accountable, prot_numa);
210 } while (pud++, addr = next, addr != end);
211
212 return pages;
213}
214
215static unsigned long change_protection_range(struct vm_area_struct *vma,
216 unsigned long addr, unsigned long end, pgprot_t newprot,
217 int dirty_accountable, int prot_numa)
218{
219 struct mm_struct *mm = vma->vm_mm;
220 pgd_t *pgd;
221 unsigned long next;
222 unsigned long start = addr;
223 unsigned long pages = 0;
224
225 BUG_ON(addr >= end);
226 pgd = pgd_offset(mm, addr);
227 flush_cache_range(vma, addr, end);
228 set_tlb_flush_pending(mm);
229 do {
230 next = pgd_addr_end(addr, end);
231 if (pgd_none_or_clear_bad(pgd))
232 continue;
233 pages += change_pud_range(vma, pgd, addr, next, newprot,
234 dirty_accountable, prot_numa);
235 } while (pgd++, addr = next, addr != end);
236
237 /* Only flush the TLB if we actually modified any entries: */
238 if (pages)
239 flush_tlb_range(vma, start, end);
240 clear_tlb_flush_pending(mm);
241
242 return pages;
243}
244
245unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
246 unsigned long end, pgprot_t newprot,
247 int dirty_accountable, int prot_numa)
248{
249 unsigned long pages;
250
251 if (is_vm_hugetlb_page(vma))
252 pages = hugetlb_change_protection(vma, start, end, newprot);
253 else
254 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
255
256 return pages;
257}
258
259int
260mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
261 unsigned long start, unsigned long end, unsigned long newflags)
262{
263 struct mm_struct *mm = vma->vm_mm;
264 unsigned long oldflags = vma->vm_flags;
265 long nrpages = (end - start) >> PAGE_SHIFT;
266 unsigned long charged = 0;
267 pgoff_t pgoff;
268 int error;
269 int dirty_accountable = 0;
270
271 if (newflags == oldflags) {
272 *pprev = vma;
273 return 0;
274 }
275
276 /*
277 * If we make a private mapping writable we increase our commit;
278 * but (without finer accounting) cannot reduce our commit if we
279 * make it unwritable again. hugetlb mapping were accounted for
280 * even if read-only so there is no need to account for them here
281 */
282 if (newflags & VM_WRITE) {
283 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
284 VM_SHARED|VM_NORESERVE))) {
285 charged = nrpages;
286 if (security_vm_enough_memory_mm(mm, charged))
287 return -ENOMEM;
288 newflags |= VM_ACCOUNT;
289 }
290 }
291
292 /*
293 * First try to merge with previous and/or next vma.
294 */
295 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
296 *pprev = vma_merge(mm, *pprev, start, end, newflags,
297 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
298 if (*pprev) {
299 vma = *pprev;
300 goto success;
301 }
302
303 *pprev = vma;
304
305 if (start != vma->vm_start) {
306 error = split_vma(mm, vma, start, 1);
307 if (error)
308 goto fail;
309 }
310
311 if (end != vma->vm_end) {
312 error = split_vma(mm, vma, end, 0);
313 if (error)
314 goto fail;
315 }
316
317success:
318 /*
319 * vm_flags and vm_page_prot are protected by the mmap_sem
320 * held in write mode.
321 */
322 vma->vm_flags = newflags;
323 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
324 vm_get_page_prot(newflags));
325
326 if (vma_wants_writenotify(vma)) {
327 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
328 dirty_accountable = 1;
329 }
330
331 change_protection(vma, start, end, vma->vm_page_prot,
332 dirty_accountable, 0);
333
334 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
335 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
336 perf_event_mmap(vma);
337 return 0;
338
339fail:
340 vm_unacct_memory(charged);
341 return error;
342}
343
344SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
345 unsigned long, prot)
346{
347 unsigned long vm_flags, nstart, end, tmp, reqprot;
348 struct vm_area_struct *vma, *prev;
349 int error = -EINVAL;
350 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
351 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
352 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
353 return -EINVAL;
354
355 if (start & ~PAGE_MASK)
356 return -EINVAL;
357 if (!len)
358 return 0;
359 len = PAGE_ALIGN(len);
360 end = start + len;
361 if (end <= start)
362 return -ENOMEM;
363 if (!arch_validate_prot(prot))
364 return -EINVAL;
365
366 reqprot = prot;
367 /*
368 * Does the application expect PROT_READ to imply PROT_EXEC:
369 */
370 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
371 prot |= PROT_EXEC;
372
373 vm_flags = calc_vm_prot_bits(prot);
374
375 down_write(¤t->mm->mmap_sem);
376
377 vma = find_vma(current->mm, start);
378 error = -ENOMEM;
379 if (!vma)
380 goto out;
381 prev = vma->vm_prev;
382 if (unlikely(grows & PROT_GROWSDOWN)) {
383 if (vma->vm_start >= end)
384 goto out;
385 start = vma->vm_start;
386 error = -EINVAL;
387 if (!(vma->vm_flags & VM_GROWSDOWN))
388 goto out;
389 } else {
390 if (vma->vm_start > start)
391 goto out;
392 if (unlikely(grows & PROT_GROWSUP)) {
393 end = vma->vm_end;
394 error = -EINVAL;
395 if (!(vma->vm_flags & VM_GROWSUP))
396 goto out;
397 }
398 }
399 if (start > vma->vm_start)
400 prev = vma;
401
402 for (nstart = start ; ; ) {
403 unsigned long newflags;
404
405 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
406
407 newflags = vm_flags;
408 newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
409
410 /* newflags >> 4 shift VM_MAY% in place of VM_% */
411 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
412 error = -EACCES;
413 goto out;
414 }
415
416 error = security_file_mprotect(vma, reqprot, prot);
417 if (error)
418 goto out;
419
420 tmp = vma->vm_end;
421 if (tmp > end)
422 tmp = end;
423 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
424 if (error)
425 goto out;
426 nstart = tmp;
427
428 if (nstart < prev->vm_end)
429 nstart = prev->vm_end;
430 if (nstart >= end)
431 goto out;
432
433 vma = prev->vm_next;
434 if (!vma || vma->vm_start != nstart) {
435 error = -ENOMEM;
436 goto out;
437 }
438 }
439out:
440 up_write(¤t->mm->mmap_sem);
441 return error;
442}