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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 <linux/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 unsigned long cp_flags)
41{
42 pte_t *pte, oldpte;
43 spinlock_t *ptl;
44 unsigned long pages = 0;
45 int target_node = NUMA_NO_NODE;
46 bool dirty_accountable = cp_flags & MM_CP_DIRTY_ACCT;
47 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
48 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
49 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
50
51 /*
52 * Can be called with only the mmap_lock for reading by
53 * prot_numa so we must check the pmd isn't constantly
54 * changing from under us from pmd_none to pmd_trans_huge
55 * and/or the other way around.
56 */
57 if (pmd_trans_unstable(pmd))
58 return 0;
59
60 /*
61 * The pmd points to a regular pte so the pmd can't change
62 * from under us even if the mmap_lock is only hold for
63 * reading.
64 */
65 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
66
67 /* Get target node for single threaded private VMAs */
68 if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
69 atomic_read(&vma->vm_mm->mm_users) == 1)
70 target_node = numa_node_id();
71
72 flush_tlb_batched_pending(vma->vm_mm);
73 arch_enter_lazy_mmu_mode();
74 do {
75 oldpte = *pte;
76 if (pte_present(oldpte)) {
77 pte_t ptent;
78 bool preserve_write = prot_numa && pte_write(oldpte);
79
80 /*
81 * Avoid trapping faults against the zero or KSM
82 * pages. See similar comment in change_huge_pmd.
83 */
84 if (prot_numa) {
85 struct page *page;
86
87 /* Avoid TLB flush if possible */
88 if (pte_protnone(oldpte))
89 continue;
90
91 page = vm_normal_page(vma, addr, oldpte);
92 if (!page || PageKsm(page))
93 continue;
94
95 /* Also skip shared copy-on-write pages */
96 if (is_cow_mapping(vma->vm_flags) &&
97 page_mapcount(page) != 1)
98 continue;
99
100 /*
101 * While migration can move some dirty pages,
102 * it cannot move them all from MIGRATE_ASYNC
103 * context.
104 */
105 if (page_is_file_lru(page) && PageDirty(page))
106 continue;
107
108 /*
109 * Don't mess with PTEs if page is already on the node
110 * a single-threaded process is running on.
111 */
112 if (target_node == page_to_nid(page))
113 continue;
114 }
115
116 oldpte = ptep_modify_prot_start(vma, addr, pte);
117 ptent = pte_modify(oldpte, newprot);
118 if (preserve_write)
119 ptent = pte_mk_savedwrite(ptent);
120
121 if (uffd_wp) {
122 ptent = pte_wrprotect(ptent);
123 ptent = pte_mkuffd_wp(ptent);
124 } else if (uffd_wp_resolve) {
125 /*
126 * Leave the write bit to be handled
127 * by PF interrupt handler, then
128 * things like COW could be properly
129 * handled.
130 */
131 ptent = pte_clear_uffd_wp(ptent);
132 }
133
134 /* Avoid taking write faults for known dirty pages */
135 if (dirty_accountable && pte_dirty(ptent) &&
136 (pte_soft_dirty(ptent) ||
137 !(vma->vm_flags & VM_SOFTDIRTY))) {
138 ptent = pte_mkwrite(ptent);
139 }
140 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
141 pages++;
142 } else if (is_swap_pte(oldpte)) {
143 swp_entry_t entry = pte_to_swp_entry(oldpte);
144 pte_t newpte;
145
146 if (is_write_migration_entry(entry)) {
147 /*
148 * A protection check is difficult so
149 * just be safe and disable write
150 */
151 make_migration_entry_read(&entry);
152 newpte = swp_entry_to_pte(entry);
153 if (pte_swp_soft_dirty(oldpte))
154 newpte = pte_swp_mksoft_dirty(newpte);
155 if (pte_swp_uffd_wp(oldpte))
156 newpte = pte_swp_mkuffd_wp(newpte);
157 } else if (is_write_device_private_entry(entry)) {
158 /*
159 * We do not preserve soft-dirtiness. See
160 * copy_one_pte() for explanation.
161 */
162 make_device_private_entry_read(&entry);
163 newpte = swp_entry_to_pte(entry);
164 if (pte_swp_uffd_wp(oldpte))
165 newpte = pte_swp_mkuffd_wp(newpte);
166 } else {
167 newpte = oldpte;
168 }
169
170 if (uffd_wp)
171 newpte = pte_swp_mkuffd_wp(newpte);
172 else if (uffd_wp_resolve)
173 newpte = pte_swp_clear_uffd_wp(newpte);
174
175 if (!pte_same(oldpte, newpte)) {
176 set_pte_at(vma->vm_mm, addr, pte, newpte);
177 pages++;
178 }
179 }
180 } while (pte++, addr += PAGE_SIZE, addr != end);
181 arch_leave_lazy_mmu_mode();
182 pte_unmap_unlock(pte - 1, ptl);
183
184 return pages;
185}
186
187/*
188 * Used when setting automatic NUMA hinting protection where it is
189 * critical that a numa hinting PMD is not confused with a bad PMD.
190 */
191static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
192{
193 pmd_t pmdval = pmd_read_atomic(pmd);
194
195 /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
196#ifdef CONFIG_TRANSPARENT_HUGEPAGE
197 barrier();
198#endif
199
200 if (pmd_none(pmdval))
201 return 1;
202 if (pmd_trans_huge(pmdval))
203 return 0;
204 if (unlikely(pmd_bad(pmdval))) {
205 pmd_clear_bad(pmd);
206 return 1;
207 }
208
209 return 0;
210}
211
212static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
213 pud_t *pud, unsigned long addr, unsigned long end,
214 pgprot_t newprot, unsigned long cp_flags)
215{
216 pmd_t *pmd;
217 unsigned long next;
218 unsigned long pages = 0;
219 unsigned long nr_huge_updates = 0;
220 struct mmu_notifier_range range;
221
222 range.start = 0;
223
224 pmd = pmd_offset(pud, addr);
225 do {
226 unsigned long this_pages;
227
228 next = pmd_addr_end(addr, end);
229
230 /*
231 * Automatic NUMA balancing walks the tables with mmap_lock
232 * held for read. It's possible a parallel update to occur
233 * between pmd_trans_huge() and a pmd_none_or_clear_bad()
234 * check leading to a false positive and clearing.
235 * Hence, it's necessary to atomically read the PMD value
236 * for all the checks.
237 */
238 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
239 pmd_none_or_clear_bad_unless_trans_huge(pmd))
240 goto next;
241
242 /* invoke the mmu notifier if the pmd is populated */
243 if (!range.start) {
244 mmu_notifier_range_init(&range,
245 MMU_NOTIFY_PROTECTION_VMA, 0,
246 vma, vma->vm_mm, addr, end);
247 mmu_notifier_invalidate_range_start(&range);
248 }
249
250 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
251 if (next - addr != HPAGE_PMD_SIZE) {
252 __split_huge_pmd(vma, pmd, addr, false, NULL);
253 } else {
254 int nr_ptes = change_huge_pmd(vma, pmd, addr,
255 newprot, cp_flags);
256
257 if (nr_ptes) {
258 if (nr_ptes == HPAGE_PMD_NR) {
259 pages += HPAGE_PMD_NR;
260 nr_huge_updates++;
261 }
262
263 /* huge pmd was handled */
264 goto next;
265 }
266 }
267 /* fall through, the trans huge pmd just split */
268 }
269 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
270 cp_flags);
271 pages += this_pages;
272next:
273 cond_resched();
274 } while (pmd++, addr = next, addr != end);
275
276 if (range.start)
277 mmu_notifier_invalidate_range_end(&range);
278
279 if (nr_huge_updates)
280 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
281 return pages;
282}
283
284static inline unsigned long change_pud_range(struct vm_area_struct *vma,
285 p4d_t *p4d, unsigned long addr, unsigned long end,
286 pgprot_t newprot, unsigned long cp_flags)
287{
288 pud_t *pud;
289 unsigned long next;
290 unsigned long pages = 0;
291
292 pud = pud_offset(p4d, addr);
293 do {
294 next = pud_addr_end(addr, end);
295 if (pud_none_or_clear_bad(pud))
296 continue;
297 pages += change_pmd_range(vma, pud, addr, next, newprot,
298 cp_flags);
299 } while (pud++, addr = next, addr != end);
300
301 return pages;
302}
303
304static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
305 pgd_t *pgd, unsigned long addr, unsigned long end,
306 pgprot_t newprot, unsigned long cp_flags)
307{
308 p4d_t *p4d;
309 unsigned long next;
310 unsigned long pages = 0;
311
312 p4d = p4d_offset(pgd, addr);
313 do {
314 next = p4d_addr_end(addr, end);
315 if (p4d_none_or_clear_bad(p4d))
316 continue;
317 pages += change_pud_range(vma, p4d, addr, next, newprot,
318 cp_flags);
319 } while (p4d++, addr = next, addr != end);
320
321 return pages;
322}
323
324static unsigned long change_protection_range(struct vm_area_struct *vma,
325 unsigned long addr, unsigned long end, pgprot_t newprot,
326 unsigned long cp_flags)
327{
328 struct mm_struct *mm = vma->vm_mm;
329 pgd_t *pgd;
330 unsigned long next;
331 unsigned long start = addr;
332 unsigned long pages = 0;
333
334 BUG_ON(addr >= end);
335 pgd = pgd_offset(mm, addr);
336 flush_cache_range(vma, addr, end);
337 inc_tlb_flush_pending(mm);
338 do {
339 next = pgd_addr_end(addr, end);
340 if (pgd_none_or_clear_bad(pgd))
341 continue;
342 pages += change_p4d_range(vma, pgd, addr, next, newprot,
343 cp_flags);
344 } while (pgd++, addr = next, addr != end);
345
346 /* Only flush the TLB if we actually modified any entries: */
347 if (pages)
348 flush_tlb_range(vma, start, end);
349 dec_tlb_flush_pending(mm);
350
351 return pages;
352}
353
354unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
355 unsigned long end, pgprot_t newprot,
356 unsigned long cp_flags)
357{
358 unsigned long pages;
359
360 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
361
362 if (is_vm_hugetlb_page(vma))
363 pages = hugetlb_change_protection(vma, start, end, newprot);
364 else
365 pages = change_protection_range(vma, start, end, newprot,
366 cp_flags);
367
368 return pages;
369}
370
371static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
372 unsigned long next, struct mm_walk *walk)
373{
374 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
375 0 : -EACCES;
376}
377
378static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
379 unsigned long addr, unsigned long next,
380 struct mm_walk *walk)
381{
382 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
383 0 : -EACCES;
384}
385
386static int prot_none_test(unsigned long addr, unsigned long next,
387 struct mm_walk *walk)
388{
389 return 0;
390}
391
392static const struct mm_walk_ops prot_none_walk_ops = {
393 .pte_entry = prot_none_pte_entry,
394 .hugetlb_entry = prot_none_hugetlb_entry,
395 .test_walk = prot_none_test,
396};
397
398int
399mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
400 unsigned long start, unsigned long end, unsigned long newflags)
401{
402 struct mm_struct *mm = vma->vm_mm;
403 unsigned long oldflags = vma->vm_flags;
404 long nrpages = (end - start) >> PAGE_SHIFT;
405 unsigned long charged = 0;
406 pgoff_t pgoff;
407 int error;
408 int dirty_accountable = 0;
409
410 if (newflags == oldflags) {
411 *pprev = vma;
412 return 0;
413 }
414
415 /*
416 * Do PROT_NONE PFN permission checks here when we can still
417 * bail out without undoing a lot of state. This is a rather
418 * uncommon case, so doesn't need to be very optimized.
419 */
420 if (arch_has_pfn_modify_check() &&
421 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
422 (newflags & VM_ACCESS_FLAGS) == 0) {
423 pgprot_t new_pgprot = vm_get_page_prot(newflags);
424
425 error = walk_page_range(current->mm, start, end,
426 &prot_none_walk_ops, &new_pgprot);
427 if (error)
428 return error;
429 }
430
431 /*
432 * If we make a private mapping writable we increase our commit;
433 * but (without finer accounting) cannot reduce our commit if we
434 * make it unwritable again. hugetlb mapping were accounted for
435 * even if read-only so there is no need to account for them here
436 */
437 if (newflags & VM_WRITE) {
438 /* Check space limits when area turns into data. */
439 if (!may_expand_vm(mm, newflags, nrpages) &&
440 may_expand_vm(mm, oldflags, nrpages))
441 return -ENOMEM;
442 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
443 VM_SHARED|VM_NORESERVE))) {
444 charged = nrpages;
445 if (security_vm_enough_memory_mm(mm, charged))
446 return -ENOMEM;
447 newflags |= VM_ACCOUNT;
448 }
449 }
450
451 /*
452 * First try to merge with previous and/or next vma.
453 */
454 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
455 *pprev = vma_merge(mm, *pprev, start, end, newflags,
456 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
457 vma->vm_userfaultfd_ctx);
458 if (*pprev) {
459 vma = *pprev;
460 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
461 goto success;
462 }
463
464 *pprev = vma;
465
466 if (start != vma->vm_start) {
467 error = split_vma(mm, vma, start, 1);
468 if (error)
469 goto fail;
470 }
471
472 if (end != vma->vm_end) {
473 error = split_vma(mm, vma, end, 0);
474 if (error)
475 goto fail;
476 }
477
478success:
479 /*
480 * vm_flags and vm_page_prot are protected by the mmap_lock
481 * held in write mode.
482 */
483 vma->vm_flags = newflags;
484 dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
485 vma_set_page_prot(vma);
486
487 change_protection(vma, start, end, vma->vm_page_prot,
488 dirty_accountable ? MM_CP_DIRTY_ACCT : 0);
489
490 /*
491 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
492 * fault on access.
493 */
494 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
495 (newflags & VM_WRITE)) {
496 populate_vma_page_range(vma, start, end, NULL);
497 }
498
499 vm_stat_account(mm, oldflags, -nrpages);
500 vm_stat_account(mm, newflags, nrpages);
501 perf_event_mmap(vma);
502 return 0;
503
504fail:
505 vm_unacct_memory(charged);
506 return error;
507}
508
509/*
510 * pkey==-1 when doing a legacy mprotect()
511 */
512static int do_mprotect_pkey(unsigned long start, size_t len,
513 unsigned long prot, int pkey)
514{
515 unsigned long nstart, end, tmp, reqprot;
516 struct vm_area_struct *vma, *prev;
517 int error = -EINVAL;
518 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
519 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
520 (prot & PROT_READ);
521
522 start = untagged_addr(start);
523
524 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
525 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
526 return -EINVAL;
527
528 if (start & ~PAGE_MASK)
529 return -EINVAL;
530 if (!len)
531 return 0;
532 len = PAGE_ALIGN(len);
533 end = start + len;
534 if (end <= start)
535 return -ENOMEM;
536 if (!arch_validate_prot(prot, start))
537 return -EINVAL;
538
539 reqprot = prot;
540
541 if (mmap_write_lock_killable(current->mm))
542 return -EINTR;
543
544 /*
545 * If userspace did not allocate the pkey, do not let
546 * them use it here.
547 */
548 error = -EINVAL;
549 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
550 goto out;
551
552 vma = find_vma(current->mm, start);
553 error = -ENOMEM;
554 if (!vma)
555 goto out;
556 prev = vma->vm_prev;
557 if (unlikely(grows & PROT_GROWSDOWN)) {
558 if (vma->vm_start >= end)
559 goto out;
560 start = vma->vm_start;
561 error = -EINVAL;
562 if (!(vma->vm_flags & VM_GROWSDOWN))
563 goto out;
564 } else {
565 if (vma->vm_start > start)
566 goto out;
567 if (unlikely(grows & PROT_GROWSUP)) {
568 end = vma->vm_end;
569 error = -EINVAL;
570 if (!(vma->vm_flags & VM_GROWSUP))
571 goto out;
572 }
573 }
574 if (start > vma->vm_start)
575 prev = vma;
576
577 for (nstart = start ; ; ) {
578 unsigned long mask_off_old_flags;
579 unsigned long newflags;
580 int new_vma_pkey;
581
582 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
583
584 /* Does the application expect PROT_READ to imply PROT_EXEC */
585 if (rier && (vma->vm_flags & VM_MAYEXEC))
586 prot |= PROT_EXEC;
587
588 /*
589 * Each mprotect() call explicitly passes r/w/x permissions.
590 * If a permission is not passed to mprotect(), it must be
591 * cleared from the VMA.
592 */
593 mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
594 VM_FLAGS_CLEAR;
595
596 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
597 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
598 newflags |= (vma->vm_flags & ~mask_off_old_flags);
599
600 /* newflags >> 4 shift VM_MAY% in place of VM_% */
601 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
602 error = -EACCES;
603 goto out;
604 }
605
606 error = security_file_mprotect(vma, reqprot, prot);
607 if (error)
608 goto out;
609
610 tmp = vma->vm_end;
611 if (tmp > end)
612 tmp = end;
613 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
614 if (error)
615 goto out;
616 nstart = tmp;
617
618 if (nstart < prev->vm_end)
619 nstart = prev->vm_end;
620 if (nstart >= end)
621 goto out;
622
623 vma = prev->vm_next;
624 if (!vma || vma->vm_start != nstart) {
625 error = -ENOMEM;
626 goto out;
627 }
628 prot = reqprot;
629 }
630out:
631 mmap_write_unlock(current->mm);
632 return error;
633}
634
635SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
636 unsigned long, prot)
637{
638 return do_mprotect_pkey(start, len, prot, -1);
639}
640
641#ifdef CONFIG_ARCH_HAS_PKEYS
642
643SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
644 unsigned long, prot, int, pkey)
645{
646 return do_mprotect_pkey(start, len, prot, pkey);
647}
648
649SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
650{
651 int pkey;
652 int ret;
653
654 /* No flags supported yet. */
655 if (flags)
656 return -EINVAL;
657 /* check for unsupported init values */
658 if (init_val & ~PKEY_ACCESS_MASK)
659 return -EINVAL;
660
661 mmap_write_lock(current->mm);
662 pkey = mm_pkey_alloc(current->mm);
663
664 ret = -ENOSPC;
665 if (pkey == -1)
666 goto out;
667
668 ret = arch_set_user_pkey_access(current, pkey, init_val);
669 if (ret) {
670 mm_pkey_free(current->mm, pkey);
671 goto out;
672 }
673 ret = pkey;
674out:
675 mmap_write_unlock(current->mm);
676 return ret;
677}
678
679SYSCALL_DEFINE1(pkey_free, int, pkey)
680{
681 int ret;
682
683 mmap_write_lock(current->mm);
684 ret = mm_pkey_free(current->mm, pkey);
685 mmap_write_unlock(current->mm);
686
687 /*
688 * We could provie warnings or errors if any VMA still
689 * has the pkey set here.
690 */
691 return ret;
692}
693
694#endif /* CONFIG_ARCH_HAS_PKEYS */
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 <linux/pgtable.h>
32#include <linux/sched/sysctl.h>
33#include <linux/userfaultfd_k.h>
34#include <linux/memory-tiers.h>
35#include <uapi/linux/mman.h>
36#include <asm/cacheflush.h>
37#include <asm/mmu_context.h>
38#include <asm/tlbflush.h>
39#include <asm/tlb.h>
40
41#include "internal.h"
42
43bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
44 pte_t pte)
45{
46 struct page *page;
47
48 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
49 return false;
50
51 /* Don't touch entries that are not even readable. */
52 if (pte_protnone(pte))
53 return false;
54
55 /* Do we need write faults for softdirty tracking? */
56 if (pte_needs_soft_dirty_wp(vma, pte))
57 return false;
58
59 /* Do we need write faults for uffd-wp tracking? */
60 if (userfaultfd_pte_wp(vma, pte))
61 return false;
62
63 if (!(vma->vm_flags & VM_SHARED)) {
64 /*
65 * Writable MAP_PRIVATE mapping: We can only special-case on
66 * exclusive anonymous pages, because we know that our
67 * write-fault handler similarly would map them writable without
68 * any additional checks while holding the PT lock.
69 */
70 page = vm_normal_page(vma, addr, pte);
71 return page && PageAnon(page) && PageAnonExclusive(page);
72 }
73
74 VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte));
75
76 /*
77 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
78 * needs a real write-fault for writenotify
79 * (see vma_wants_writenotify()). If "dirty", the assumption is that the
80 * FS was already notified and we can simply mark the PTE writable
81 * just like the write-fault handler would do.
82 */
83 return pte_dirty(pte);
84}
85
86static long change_pte_range(struct mmu_gather *tlb,
87 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
88 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
89{
90 pte_t *pte, oldpte;
91 spinlock_t *ptl;
92 long pages = 0;
93 int target_node = NUMA_NO_NODE;
94 bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
95 bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
96 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
97
98 tlb_change_page_size(tlb, PAGE_SIZE);
99 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
100 if (!pte)
101 return -EAGAIN;
102
103 /* Get target node for single threaded private VMAs */
104 if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
105 atomic_read(&vma->vm_mm->mm_users) == 1)
106 target_node = numa_node_id();
107
108 flush_tlb_batched_pending(vma->vm_mm);
109 arch_enter_lazy_mmu_mode();
110 do {
111 oldpte = ptep_get(pte);
112 if (pte_present(oldpte)) {
113 pte_t ptent;
114
115 /*
116 * Avoid trapping faults against the zero or KSM
117 * pages. See similar comment in change_huge_pmd.
118 */
119 if (prot_numa) {
120 struct folio *folio;
121 int nid;
122 bool toptier;
123
124 /* Avoid TLB flush if possible */
125 if (pte_protnone(oldpte))
126 continue;
127
128 folio = vm_normal_folio(vma, addr, oldpte);
129 if (!folio || folio_is_zone_device(folio) ||
130 folio_test_ksm(folio))
131 continue;
132
133 /* Also skip shared copy-on-write pages */
134 if (is_cow_mapping(vma->vm_flags) &&
135 (folio_maybe_dma_pinned(folio) ||
136 folio_likely_mapped_shared(folio)))
137 continue;
138
139 /*
140 * While migration can move some dirty pages,
141 * it cannot move them all from MIGRATE_ASYNC
142 * context.
143 */
144 if (folio_is_file_lru(folio) &&
145 folio_test_dirty(folio))
146 continue;
147
148 /*
149 * Don't mess with PTEs if page is already on the node
150 * a single-threaded process is running on.
151 */
152 nid = folio_nid(folio);
153 if (target_node == nid)
154 continue;
155 toptier = node_is_toptier(nid);
156
157 /*
158 * Skip scanning top tier node if normal numa
159 * balancing is disabled
160 */
161 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
162 toptier)
163 continue;
164 if (folio_use_access_time(folio))
165 folio_xchg_access_time(folio,
166 jiffies_to_msecs(jiffies));
167 }
168
169 oldpte = ptep_modify_prot_start(vma, addr, pte);
170 ptent = pte_modify(oldpte, newprot);
171
172 if (uffd_wp)
173 ptent = pte_mkuffd_wp(ptent);
174 else if (uffd_wp_resolve)
175 ptent = pte_clear_uffd_wp(ptent);
176
177 /*
178 * In some writable, shared mappings, we might want
179 * to catch actual write access -- see
180 * vma_wants_writenotify().
181 *
182 * In all writable, private mappings, we have to
183 * properly handle COW.
184 *
185 * In both cases, we can sometimes still change PTEs
186 * writable and avoid the write-fault handler, for
187 * example, if a PTE is already dirty and no other
188 * COW or special handling is required.
189 */
190 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
191 !pte_write(ptent) &&
192 can_change_pte_writable(vma, addr, ptent))
193 ptent = pte_mkwrite(ptent, vma);
194
195 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
196 if (pte_needs_flush(oldpte, ptent))
197 tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
198 pages++;
199 } else if (is_swap_pte(oldpte)) {
200 swp_entry_t entry = pte_to_swp_entry(oldpte);
201 pte_t newpte;
202
203 if (is_writable_migration_entry(entry)) {
204 struct folio *folio = pfn_swap_entry_folio(entry);
205
206 /*
207 * A protection check is difficult so
208 * just be safe and disable write
209 */
210 if (folio_test_anon(folio))
211 entry = make_readable_exclusive_migration_entry(
212 swp_offset(entry));
213 else
214 entry = make_readable_migration_entry(swp_offset(entry));
215 newpte = swp_entry_to_pte(entry);
216 if (pte_swp_soft_dirty(oldpte))
217 newpte = pte_swp_mksoft_dirty(newpte);
218 } else if (is_writable_device_private_entry(entry)) {
219 /*
220 * We do not preserve soft-dirtiness. See
221 * copy_nonpresent_pte() for explanation.
222 */
223 entry = make_readable_device_private_entry(
224 swp_offset(entry));
225 newpte = swp_entry_to_pte(entry);
226 if (pte_swp_uffd_wp(oldpte))
227 newpte = pte_swp_mkuffd_wp(newpte);
228 } else if (is_writable_device_exclusive_entry(entry)) {
229 entry = make_readable_device_exclusive_entry(
230 swp_offset(entry));
231 newpte = swp_entry_to_pte(entry);
232 if (pte_swp_soft_dirty(oldpte))
233 newpte = pte_swp_mksoft_dirty(newpte);
234 if (pte_swp_uffd_wp(oldpte))
235 newpte = pte_swp_mkuffd_wp(newpte);
236 } else if (is_pte_marker_entry(entry)) {
237 /*
238 * Ignore error swap entries unconditionally,
239 * because any access should sigbus/sigsegv
240 * anyway.
241 */
242 if (is_poisoned_swp_entry(entry) ||
243 is_guard_swp_entry(entry))
244 continue;
245 /*
246 * If this is uffd-wp pte marker and we'd like
247 * to unprotect it, drop it; the next page
248 * fault will trigger without uffd trapping.
249 */
250 if (uffd_wp_resolve) {
251 pte_clear(vma->vm_mm, addr, pte);
252 pages++;
253 }
254 continue;
255 } else {
256 newpte = oldpte;
257 }
258
259 if (uffd_wp)
260 newpte = pte_swp_mkuffd_wp(newpte);
261 else if (uffd_wp_resolve)
262 newpte = pte_swp_clear_uffd_wp(newpte);
263
264 if (!pte_same(oldpte, newpte)) {
265 set_pte_at(vma->vm_mm, addr, pte, newpte);
266 pages++;
267 }
268 } else {
269 /* It must be an none page, or what else?.. */
270 WARN_ON_ONCE(!pte_none(oldpte));
271
272 /*
273 * Nobody plays with any none ptes besides
274 * userfaultfd when applying the protections.
275 */
276 if (likely(!uffd_wp))
277 continue;
278
279 if (userfaultfd_wp_use_markers(vma)) {
280 /*
281 * For file-backed mem, we need to be able to
282 * wr-protect a none pte, because even if the
283 * pte is none, the page/swap cache could
284 * exist. Doing that by install a marker.
285 */
286 set_pte_at(vma->vm_mm, addr, pte,
287 make_pte_marker(PTE_MARKER_UFFD_WP));
288 pages++;
289 }
290 }
291 } while (pte++, addr += PAGE_SIZE, addr != end);
292 arch_leave_lazy_mmu_mode();
293 pte_unmap_unlock(pte - 1, ptl);
294
295 return pages;
296}
297
298/*
299 * Return true if we want to split THPs into PTE mappings in change
300 * protection procedure, false otherwise.
301 */
302static inline bool
303pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
304{
305 /*
306 * pte markers only resides in pte level, if we need pte markers,
307 * we need to split. For example, we cannot wr-protect a file thp
308 * (e.g. 2M shmem) because file thp is handled differently when
309 * split by erasing the pmd so far.
310 */
311 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
312}
313
314/*
315 * Return true if we want to populate pgtables in change protection
316 * procedure, false otherwise
317 */
318static inline bool
319pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
320{
321 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
322 if (!(cp_flags & MM_CP_UFFD_WP))
323 return false;
324
325 /* Populate if the userfaultfd mode requires pte markers */
326 return userfaultfd_wp_use_markers(vma);
327}
328
329/*
330 * Populate the pgtable underneath for whatever reason if requested.
331 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
332 * allocation failures during page faults by kicking OOM and returning
333 * error.
334 */
335#define change_pmd_prepare(vma, pmd, cp_flags) \
336 ({ \
337 long err = 0; \
338 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
339 if (pte_alloc(vma->vm_mm, pmd)) \
340 err = -ENOMEM; \
341 } \
342 err; \
343 })
344
345/*
346 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
347 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
348 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
349 */
350#define change_prepare(vma, high, low, addr, cp_flags) \
351 ({ \
352 long err = 0; \
353 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
354 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
355 if (p == NULL) \
356 err = -ENOMEM; \
357 } \
358 err; \
359 })
360
361static inline long change_pmd_range(struct mmu_gather *tlb,
362 struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
363 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
364{
365 pmd_t *pmd;
366 unsigned long next;
367 long pages = 0;
368 unsigned long nr_huge_updates = 0;
369
370 pmd = pmd_offset(pud, addr);
371 do {
372 long ret;
373 pmd_t _pmd;
374again:
375 next = pmd_addr_end(addr, end);
376
377 ret = change_pmd_prepare(vma, pmd, cp_flags);
378 if (ret) {
379 pages = ret;
380 break;
381 }
382
383 if (pmd_none(*pmd))
384 goto next;
385
386 _pmd = pmdp_get_lockless(pmd);
387 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
388 if ((next - addr != HPAGE_PMD_SIZE) ||
389 pgtable_split_needed(vma, cp_flags)) {
390 __split_huge_pmd(vma, pmd, addr, false, NULL);
391 /*
392 * For file-backed, the pmd could have been
393 * cleared; make sure pmd populated if
394 * necessary, then fall-through to pte level.
395 */
396 ret = change_pmd_prepare(vma, pmd, cp_flags);
397 if (ret) {
398 pages = ret;
399 break;
400 }
401 } else {
402 ret = change_huge_pmd(tlb, vma, pmd,
403 addr, newprot, cp_flags);
404 if (ret) {
405 if (ret == HPAGE_PMD_NR) {
406 pages += HPAGE_PMD_NR;
407 nr_huge_updates++;
408 }
409
410 /* huge pmd was handled */
411 goto next;
412 }
413 }
414 /* fall through, the trans huge pmd just split */
415 }
416
417 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
418 cp_flags);
419 if (ret < 0)
420 goto again;
421 pages += ret;
422next:
423 cond_resched();
424 } while (pmd++, addr = next, addr != end);
425
426 if (nr_huge_updates)
427 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
428 return pages;
429}
430
431static inline long change_pud_range(struct mmu_gather *tlb,
432 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
433 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
434{
435 struct mmu_notifier_range range;
436 pud_t *pudp, pud;
437 unsigned long next;
438 long pages = 0, ret;
439
440 range.start = 0;
441
442 pudp = pud_offset(p4d, addr);
443 do {
444again:
445 next = pud_addr_end(addr, end);
446 ret = change_prepare(vma, pudp, pmd, addr, cp_flags);
447 if (ret) {
448 pages = ret;
449 break;
450 }
451
452 pud = READ_ONCE(*pudp);
453 if (pud_none(pud))
454 continue;
455
456 if (!range.start) {
457 mmu_notifier_range_init(&range,
458 MMU_NOTIFY_PROTECTION_VMA, 0,
459 vma->vm_mm, addr, end);
460 mmu_notifier_invalidate_range_start(&range);
461 }
462
463 if (pud_leaf(pud)) {
464 if ((next - addr != PUD_SIZE) ||
465 pgtable_split_needed(vma, cp_flags)) {
466 __split_huge_pud(vma, pudp, addr);
467 goto again;
468 } else {
469 ret = change_huge_pud(tlb, vma, pudp,
470 addr, newprot, cp_flags);
471 if (ret == 0)
472 goto again;
473 /* huge pud was handled */
474 if (ret == HPAGE_PUD_NR)
475 pages += HPAGE_PUD_NR;
476 continue;
477 }
478 }
479
480 pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot,
481 cp_flags);
482 } while (pudp++, addr = next, addr != end);
483
484 if (range.start)
485 mmu_notifier_invalidate_range_end(&range);
486
487 return pages;
488}
489
490static inline long change_p4d_range(struct mmu_gather *tlb,
491 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
492 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
493{
494 p4d_t *p4d;
495 unsigned long next;
496 long pages = 0, ret;
497
498 p4d = p4d_offset(pgd, addr);
499 do {
500 next = p4d_addr_end(addr, end);
501 ret = change_prepare(vma, p4d, pud, addr, cp_flags);
502 if (ret)
503 return ret;
504 if (p4d_none_or_clear_bad(p4d))
505 continue;
506 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
507 cp_flags);
508 } while (p4d++, addr = next, addr != end);
509
510 return pages;
511}
512
513static long change_protection_range(struct mmu_gather *tlb,
514 struct vm_area_struct *vma, unsigned long addr,
515 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
516{
517 struct mm_struct *mm = vma->vm_mm;
518 pgd_t *pgd;
519 unsigned long next;
520 long pages = 0, ret;
521
522 BUG_ON(addr >= end);
523 pgd = pgd_offset(mm, addr);
524 tlb_start_vma(tlb, vma);
525 do {
526 next = pgd_addr_end(addr, end);
527 ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
528 if (ret) {
529 pages = ret;
530 break;
531 }
532 if (pgd_none_or_clear_bad(pgd))
533 continue;
534 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
535 cp_flags);
536 } while (pgd++, addr = next, addr != end);
537
538 tlb_end_vma(tlb, vma);
539
540 return pages;
541}
542
543long change_protection(struct mmu_gather *tlb,
544 struct vm_area_struct *vma, unsigned long start,
545 unsigned long end, unsigned long cp_flags)
546{
547 pgprot_t newprot = vma->vm_page_prot;
548 long pages;
549
550 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
551
552#ifdef CONFIG_NUMA_BALANCING
553 /*
554 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
555 * are expected to reflect their requirements via VMA flags such that
556 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
557 */
558 if (cp_flags & MM_CP_PROT_NUMA)
559 newprot = PAGE_NONE;
560#else
561 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
562#endif
563
564 if (is_vm_hugetlb_page(vma))
565 pages = hugetlb_change_protection(vma, start, end, newprot,
566 cp_flags);
567 else
568 pages = change_protection_range(tlb, vma, start, end, newprot,
569 cp_flags);
570
571 return pages;
572}
573
574static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
575 unsigned long next, struct mm_walk *walk)
576{
577 return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
578 *(pgprot_t *)(walk->private)) ?
579 0 : -EACCES;
580}
581
582static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
583 unsigned long addr, unsigned long next,
584 struct mm_walk *walk)
585{
586 return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
587 *(pgprot_t *)(walk->private)) ?
588 0 : -EACCES;
589}
590
591static int prot_none_test(unsigned long addr, unsigned long next,
592 struct mm_walk *walk)
593{
594 return 0;
595}
596
597static const struct mm_walk_ops prot_none_walk_ops = {
598 .pte_entry = prot_none_pte_entry,
599 .hugetlb_entry = prot_none_hugetlb_entry,
600 .test_walk = prot_none_test,
601 .walk_lock = PGWALK_WRLOCK,
602};
603
604int
605mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
606 struct vm_area_struct *vma, struct vm_area_struct **pprev,
607 unsigned long start, unsigned long end, unsigned long newflags)
608{
609 struct mm_struct *mm = vma->vm_mm;
610 unsigned long oldflags = vma->vm_flags;
611 long nrpages = (end - start) >> PAGE_SHIFT;
612 unsigned int mm_cp_flags = 0;
613 unsigned long charged = 0;
614 int error;
615
616 if (!can_modify_vma(vma))
617 return -EPERM;
618
619 if (newflags == oldflags) {
620 *pprev = vma;
621 return 0;
622 }
623
624 /*
625 * Do PROT_NONE PFN permission checks here when we can still
626 * bail out without undoing a lot of state. This is a rather
627 * uncommon case, so doesn't need to be very optimized.
628 */
629 if (arch_has_pfn_modify_check() &&
630 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
631 (newflags & VM_ACCESS_FLAGS) == 0) {
632 pgprot_t new_pgprot = vm_get_page_prot(newflags);
633
634 error = walk_page_range(current->mm, start, end,
635 &prot_none_walk_ops, &new_pgprot);
636 if (error)
637 return error;
638 }
639
640 /*
641 * If we make a private mapping writable we increase our commit;
642 * but (without finer accounting) cannot reduce our commit if we
643 * make it unwritable again except in the anonymous case where no
644 * anon_vma has yet to be assigned.
645 *
646 * hugetlb mapping were accounted for even if read-only so there is
647 * no need to account for them here.
648 */
649 if (newflags & VM_WRITE) {
650 /* Check space limits when area turns into data. */
651 if (!may_expand_vm(mm, newflags, nrpages) &&
652 may_expand_vm(mm, oldflags, nrpages))
653 return -ENOMEM;
654 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
655 VM_SHARED|VM_NORESERVE))) {
656 charged = nrpages;
657 if (security_vm_enough_memory_mm(mm, charged))
658 return -ENOMEM;
659 newflags |= VM_ACCOUNT;
660 }
661 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) &&
662 !vma->anon_vma) {
663 newflags &= ~VM_ACCOUNT;
664 }
665
666 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags);
667 if (IS_ERR(vma)) {
668 error = PTR_ERR(vma);
669 goto fail;
670 }
671
672 *pprev = vma;
673
674 /*
675 * vm_flags and vm_page_prot are protected by the mmap_lock
676 * held in write mode.
677 */
678 vma_start_write(vma);
679 vm_flags_reset(vma, newflags);
680 if (vma_wants_manual_pte_write_upgrade(vma))
681 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
682 vma_set_page_prot(vma);
683
684 change_protection(tlb, vma, start, end, mm_cp_flags);
685
686 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT))
687 vm_unacct_memory(nrpages);
688
689 /*
690 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
691 * fault on access.
692 */
693 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
694 (newflags & VM_WRITE)) {
695 populate_vma_page_range(vma, start, end, NULL);
696 }
697
698 vm_stat_account(mm, oldflags, -nrpages);
699 vm_stat_account(mm, newflags, nrpages);
700 perf_event_mmap(vma);
701 return 0;
702
703fail:
704 vm_unacct_memory(charged);
705 return error;
706}
707
708/*
709 * pkey==-1 when doing a legacy mprotect()
710 */
711static int do_mprotect_pkey(unsigned long start, size_t len,
712 unsigned long prot, int pkey)
713{
714 unsigned long nstart, end, tmp, reqprot;
715 struct vm_area_struct *vma, *prev;
716 int error;
717 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
718 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
719 (prot & PROT_READ);
720 struct mmu_gather tlb;
721 struct vma_iterator vmi;
722
723 start = untagged_addr(start);
724
725 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
726 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
727 return -EINVAL;
728
729 if (start & ~PAGE_MASK)
730 return -EINVAL;
731 if (!len)
732 return 0;
733 len = PAGE_ALIGN(len);
734 end = start + len;
735 if (end <= start)
736 return -ENOMEM;
737 if (!arch_validate_prot(prot, start))
738 return -EINVAL;
739
740 reqprot = prot;
741
742 if (mmap_write_lock_killable(current->mm))
743 return -EINTR;
744
745 /*
746 * If userspace did not allocate the pkey, do not let
747 * them use it here.
748 */
749 error = -EINVAL;
750 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
751 goto out;
752
753 vma_iter_init(&vmi, current->mm, start);
754 vma = vma_find(&vmi, end);
755 error = -ENOMEM;
756 if (!vma)
757 goto out;
758
759 if (unlikely(grows & PROT_GROWSDOWN)) {
760 if (vma->vm_start >= end)
761 goto out;
762 start = vma->vm_start;
763 error = -EINVAL;
764 if (!(vma->vm_flags & VM_GROWSDOWN))
765 goto out;
766 } else {
767 if (vma->vm_start > start)
768 goto out;
769 if (unlikely(grows & PROT_GROWSUP)) {
770 end = vma->vm_end;
771 error = -EINVAL;
772 if (!(vma->vm_flags & VM_GROWSUP))
773 goto out;
774 }
775 }
776
777 prev = vma_prev(&vmi);
778 if (start > vma->vm_start)
779 prev = vma;
780
781 tlb_gather_mmu(&tlb, current->mm);
782 nstart = start;
783 tmp = vma->vm_start;
784 for_each_vma_range(vmi, vma, end) {
785 unsigned long mask_off_old_flags;
786 unsigned long newflags;
787 int new_vma_pkey;
788
789 if (vma->vm_start != tmp) {
790 error = -ENOMEM;
791 break;
792 }
793
794 /* Does the application expect PROT_READ to imply PROT_EXEC */
795 if (rier && (vma->vm_flags & VM_MAYEXEC))
796 prot |= PROT_EXEC;
797
798 /*
799 * Each mprotect() call explicitly passes r/w/x permissions.
800 * If a permission is not passed to mprotect(), it must be
801 * cleared from the VMA.
802 */
803 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
804
805 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
806 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
807 newflags |= (vma->vm_flags & ~mask_off_old_flags);
808
809 /* newflags >> 4 shift VM_MAY% in place of VM_% */
810 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
811 error = -EACCES;
812 break;
813 }
814
815 if (map_deny_write_exec(vma->vm_flags, newflags)) {
816 error = -EACCES;
817 break;
818 }
819
820 /* Allow architectures to sanity-check the new flags */
821 if (!arch_validate_flags(newflags)) {
822 error = -EINVAL;
823 break;
824 }
825
826 error = security_file_mprotect(vma, reqprot, prot);
827 if (error)
828 break;
829
830 tmp = vma->vm_end;
831 if (tmp > end)
832 tmp = end;
833
834 if (vma->vm_ops && vma->vm_ops->mprotect) {
835 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
836 if (error)
837 break;
838 }
839
840 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
841 if (error)
842 break;
843
844 tmp = vma_iter_end(&vmi);
845 nstart = tmp;
846 prot = reqprot;
847 }
848 tlb_finish_mmu(&tlb);
849
850 if (!error && tmp < end)
851 error = -ENOMEM;
852
853out:
854 mmap_write_unlock(current->mm);
855 return error;
856}
857
858SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
859 unsigned long, prot)
860{
861 return do_mprotect_pkey(start, len, prot, -1);
862}
863
864#ifdef CONFIG_ARCH_HAS_PKEYS
865
866SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
867 unsigned long, prot, int, pkey)
868{
869 return do_mprotect_pkey(start, len, prot, pkey);
870}
871
872SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
873{
874 int pkey;
875 int ret;
876
877 /* No flags supported yet. */
878 if (flags)
879 return -EINVAL;
880 /* check for unsupported init values */
881 if (init_val & ~PKEY_ACCESS_MASK)
882 return -EINVAL;
883
884 mmap_write_lock(current->mm);
885 pkey = mm_pkey_alloc(current->mm);
886
887 ret = -ENOSPC;
888 if (pkey == -1)
889 goto out;
890
891 ret = arch_set_user_pkey_access(current, pkey, init_val);
892 if (ret) {
893 mm_pkey_free(current->mm, pkey);
894 goto out;
895 }
896 ret = pkey;
897out:
898 mmap_write_unlock(current->mm);
899 return ret;
900}
901
902SYSCALL_DEFINE1(pkey_free, int, pkey)
903{
904 int ret;
905
906 mmap_write_lock(current->mm);
907 ret = mm_pkey_free(current->mm, pkey);
908 mmap_write_unlock(current->mm);
909
910 /*
911 * We could provide warnings or errors if any VMA still
912 * has the pkey set here.
913 */
914 return ret;
915}
916
917#endif /* CONFIG_ARCH_HAS_PKEYS */