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
43 bool 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
86 static 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 (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
165 !toptier)
166 folio_xchg_access_time(folio,
167 jiffies_to_msecs(jiffies));
168 }
169
170 oldpte = ptep_modify_prot_start(vma, addr, pte);
171 ptent = pte_modify(oldpte, newprot);
172
173 if (uffd_wp)
174 ptent = pte_mkuffd_wp(ptent);
175 else if (uffd_wp_resolve)
176 ptent = pte_clear_uffd_wp(ptent);
177
178 /*
179 * In some writable, shared mappings, we might want
180 * to catch actual write access -- see
181 * vma_wants_writenotify().
182 *
183 * In all writable, private mappings, we have to
184 * properly handle COW.
185 *
186 * In both cases, we can sometimes still change PTEs
187 * writable and avoid the write-fault handler, for
188 * example, if a PTE is already dirty and no other
189 * COW or special handling is required.
190 */
191 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
192 !pte_write(ptent) &&
193 can_change_pte_writable(vma, addr, ptent))
194 ptent = pte_mkwrite(ptent, vma);
195
196 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
197 if (pte_needs_flush(oldpte, ptent))
198 tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
199 pages++;
200 } else if (is_swap_pte(oldpte)) {
201 swp_entry_t entry = pte_to_swp_entry(oldpte);
202 pte_t newpte;
203
204 if (is_writable_migration_entry(entry)) {
205 struct folio *folio = pfn_swap_entry_folio(entry);
206
207 /*
208 * A protection check is difficult so
209 * just be safe and disable write
210 */
211 if (folio_test_anon(folio))
212 entry = make_readable_exclusive_migration_entry(
213 swp_offset(entry));
214 else
215 entry = make_readable_migration_entry(swp_offset(entry));
216 newpte = swp_entry_to_pte(entry);
217 if (pte_swp_soft_dirty(oldpte))
218 newpte = pte_swp_mksoft_dirty(newpte);
219 } else if (is_writable_device_private_entry(entry)) {
220 /*
221 * We do not preserve soft-dirtiness. See
222 * copy_nonpresent_pte() for explanation.
223 */
224 entry = make_readable_device_private_entry(
225 swp_offset(entry));
226 newpte = swp_entry_to_pte(entry);
227 if (pte_swp_uffd_wp(oldpte))
228 newpte = pte_swp_mkuffd_wp(newpte);
229 } else if (is_writable_device_exclusive_entry(entry)) {
230 entry = make_readable_device_exclusive_entry(
231 swp_offset(entry));
232 newpte = swp_entry_to_pte(entry);
233 if (pte_swp_soft_dirty(oldpte))
234 newpte = pte_swp_mksoft_dirty(newpte);
235 if (pte_swp_uffd_wp(oldpte))
236 newpte = pte_swp_mkuffd_wp(newpte);
237 } else if (is_pte_marker_entry(entry)) {
238 /*
239 * Ignore error swap entries unconditionally,
240 * because any access should sigbus anyway.
241 */
242 if (is_poisoned_swp_entry(entry))
243 continue;
244 /*
245 * If this is uffd-wp pte marker and we'd like
246 * to unprotect it, drop it; the next page
247 * fault will trigger without uffd trapping.
248 */
249 if (uffd_wp_resolve) {
250 pte_clear(vma->vm_mm, addr, pte);
251 pages++;
252 }
253 continue;
254 } else {
255 newpte = oldpte;
256 }
257
258 if (uffd_wp)
259 newpte = pte_swp_mkuffd_wp(newpte);
260 else if (uffd_wp_resolve)
261 newpte = pte_swp_clear_uffd_wp(newpte);
262
263 if (!pte_same(oldpte, newpte)) {
264 set_pte_at(vma->vm_mm, addr, pte, newpte);
265 pages++;
266 }
267 } else {
268 /* It must be an none page, or what else?.. */
269 WARN_ON_ONCE(!pte_none(oldpte));
270
271 /*
272 * Nobody plays with any none ptes besides
273 * userfaultfd when applying the protections.
274 */
275 if (likely(!uffd_wp))
276 continue;
277
278 if (userfaultfd_wp_use_markers(vma)) {
279 /*
280 * For file-backed mem, we need to be able to
281 * wr-protect a none pte, because even if the
282 * pte is none, the page/swap cache could
283 * exist. Doing that by install a marker.
284 */
285 set_pte_at(vma->vm_mm, addr, pte,
286 make_pte_marker(PTE_MARKER_UFFD_WP));
287 pages++;
288 }
289 }
290 } while (pte++, addr += PAGE_SIZE, addr != end);
291 arch_leave_lazy_mmu_mode();
292 pte_unmap_unlock(pte - 1, ptl);
293
294 return pages;
295 }
296
297 /*
298 * Return true if we want to split THPs into PTE mappings in change
299 * protection procedure, false otherwise.
300 */
301 static inline bool
302 pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
303 {
304 /*
305 * pte markers only resides in pte level, if we need pte markers,
306 * we need to split. We cannot wr-protect shmem thp because file
307 * thp is handled differently when split by erasing the pmd so far.
308 */
309 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
310 }
311
312 /*
313 * Return true if we want to populate pgtables in change protection
314 * procedure, false otherwise
315 */
316 static inline bool
317 pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
318 {
319 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
320 if (!(cp_flags & MM_CP_UFFD_WP))
321 return false;
322
323 /* Populate if the userfaultfd mode requires pte markers */
324 return userfaultfd_wp_use_markers(vma);
325 }
326
327 /*
328 * Populate the pgtable underneath for whatever reason if requested.
329 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
330 * allocation failures during page faults by kicking OOM and returning
331 * error.
332 */
333 #define change_pmd_prepare(vma, pmd, cp_flags) \
334 ({ \
335 long err = 0; \
336 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
337 if (pte_alloc(vma->vm_mm, pmd)) \
338 err = -ENOMEM; \
339 } \
340 err; \
341 })
342
343 /*
344 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
345 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
346 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
347 */
348 #define change_prepare(vma, high, low, addr, cp_flags) \
349 ({ \
350 long err = 0; \
351 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
352 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
353 if (p == NULL) \
354 err = -ENOMEM; \
355 } \
356 err; \
357 })
358
359 static inline long change_pmd_range(struct mmu_gather *tlb,
360 struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
361 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
362 {
363 pmd_t *pmd;
364 unsigned long next;
365 long pages = 0;
366 unsigned long nr_huge_updates = 0;
367 struct mmu_notifier_range range;
368
369 range.start = 0;
370
371 pmd = pmd_offset(pud, addr);
372 do {
373 long ret;
374 pmd_t _pmd;
375 again:
376 next = pmd_addr_end(addr, end);
377
378 ret = change_pmd_prepare(vma, pmd, cp_flags);
379 if (ret) {
380 pages = ret;
381 break;
382 }
383
384 if (pmd_none(*pmd))
385 goto next;
386
387 /* invoke the mmu notifier if the pmd is populated */
388 if (!range.start) {
389 mmu_notifier_range_init(&range,
390 MMU_NOTIFY_PROTECTION_VMA, 0,
391 vma->vm_mm, addr, end);
392 mmu_notifier_invalidate_range_start(&range);
393 }
394
395 _pmd = pmdp_get_lockless(pmd);
396 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
397 if ((next - addr != HPAGE_PMD_SIZE) ||
398 pgtable_split_needed(vma, cp_flags)) {
399 __split_huge_pmd(vma, pmd, addr, false, NULL);
400 /*
401 * For file-backed, the pmd could have been
402 * cleared; make sure pmd populated if
403 * necessary, then fall-through to pte level.
404 */
405 ret = change_pmd_prepare(vma, pmd, cp_flags);
406 if (ret) {
407 pages = ret;
408 break;
409 }
410 } else {
411 ret = change_huge_pmd(tlb, vma, pmd,
412 addr, newprot, cp_flags);
413 if (ret) {
414 if (ret == HPAGE_PMD_NR) {
415 pages += HPAGE_PMD_NR;
416 nr_huge_updates++;
417 }
418
419 /* huge pmd was handled */
420 goto next;
421 }
422 }
423 /* fall through, the trans huge pmd just split */
424 }
425
426 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
427 cp_flags);
428 if (ret < 0)
429 goto again;
430 pages += ret;
431 next:
432 cond_resched();
433 } while (pmd++, addr = next, addr != end);
434
435 if (range.start)
436 mmu_notifier_invalidate_range_end(&range);
437
438 if (nr_huge_updates)
439 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
440 return pages;
441 }
442
443 static inline long change_pud_range(struct mmu_gather *tlb,
444 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
445 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
446 {
447 pud_t *pud;
448 unsigned long next;
449 long pages = 0, ret;
450
451 pud = pud_offset(p4d, addr);
452 do {
453 next = pud_addr_end(addr, end);
454 ret = change_prepare(vma, pud, pmd, addr, cp_flags);
455 if (ret)
456 return ret;
457 if (pud_none_or_clear_bad(pud))
458 continue;
459 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
460 cp_flags);
461 } while (pud++, addr = next, addr != end);
462
463 return pages;
464 }
465
466 static inline long change_p4d_range(struct mmu_gather *tlb,
467 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
468 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
469 {
470 p4d_t *p4d;
471 unsigned long next;
472 long pages = 0, ret;
473
474 p4d = p4d_offset(pgd, addr);
475 do {
476 next = p4d_addr_end(addr, end);
477 ret = change_prepare(vma, p4d, pud, addr, cp_flags);
478 if (ret)
479 return ret;
480 if (p4d_none_or_clear_bad(p4d))
481 continue;
482 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
483 cp_flags);
484 } while (p4d++, addr = next, addr != end);
485
486 return pages;
487 }
488
489 static long change_protection_range(struct mmu_gather *tlb,
490 struct vm_area_struct *vma, unsigned long addr,
491 unsigned long end, pgprot_t newprot, unsigned long cp_flags)
492 {
493 struct mm_struct *mm = vma->vm_mm;
494 pgd_t *pgd;
495 unsigned long next;
496 long pages = 0, ret;
497
498 BUG_ON(addr >= end);
499 pgd = pgd_offset(mm, addr);
500 tlb_start_vma(tlb, vma);
501 do {
502 next = pgd_addr_end(addr, end);
503 ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
504 if (ret) {
505 pages = ret;
506 break;
507 }
508 if (pgd_none_or_clear_bad(pgd))
509 continue;
510 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
511 cp_flags);
512 } while (pgd++, addr = next, addr != end);
513
514 tlb_end_vma(tlb, vma);
515
516 return pages;
517 }
518
519 long change_protection(struct mmu_gather *tlb,
520 struct vm_area_struct *vma, unsigned long start,
521 unsigned long end, unsigned long cp_flags)
522 {
523 pgprot_t newprot = vma->vm_page_prot;
524 long pages;
525
526 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
527
528 #ifdef CONFIG_NUMA_BALANCING
529 /*
530 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
531 * are expected to reflect their requirements via VMA flags such that
532 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
533 */
534 if (cp_flags & MM_CP_PROT_NUMA)
535 newprot = PAGE_NONE;
536 #else
537 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
538 #endif
539
540 if (is_vm_hugetlb_page(vma))
541 pages = hugetlb_change_protection(vma, start, end, newprot,
542 cp_flags);
543 else
544 pages = change_protection_range(tlb, vma, start, end, newprot,
545 cp_flags);
546
547 return pages;
548 }
549
550 static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
551 unsigned long next, struct mm_walk *walk)
552 {
553 return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
554 *(pgprot_t *)(walk->private)) ?
555 0 : -EACCES;
556 }
557
558 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
559 unsigned long addr, unsigned long next,
560 struct mm_walk *walk)
561 {
562 return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
563 *(pgprot_t *)(walk->private)) ?
564 0 : -EACCES;
565 }
566
567 static int prot_none_test(unsigned long addr, unsigned long next,
568 struct mm_walk *walk)
569 {
570 return 0;
571 }
572
573 static const struct mm_walk_ops prot_none_walk_ops = {
574 .pte_entry = prot_none_pte_entry,
575 .hugetlb_entry = prot_none_hugetlb_entry,
576 .test_walk = prot_none_test,
577 .walk_lock = PGWALK_WRLOCK,
578 };
579
580 int
581 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
582 struct vm_area_struct *vma, struct vm_area_struct **pprev,
583 unsigned long start, unsigned long end, unsigned long newflags)
584 {
585 struct mm_struct *mm = vma->vm_mm;
586 unsigned long oldflags = vma->vm_flags;
587 long nrpages = (end - start) >> PAGE_SHIFT;
588 unsigned int mm_cp_flags = 0;
589 unsigned long charged = 0;
590 int error;
591
592 if (newflags == oldflags) {
593 *pprev = vma;
594 return 0;
595 }
596
597 /*
598 * Do PROT_NONE PFN permission checks here when we can still
599 * bail out without undoing a lot of state. This is a rather
600 * uncommon case, so doesn't need to be very optimized.
601 */
602 if (arch_has_pfn_modify_check() &&
603 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
604 (newflags & VM_ACCESS_FLAGS) == 0) {
605 pgprot_t new_pgprot = vm_get_page_prot(newflags);
606
607 error = walk_page_range(current->mm, start, end,
608 &prot_none_walk_ops, &new_pgprot);
609 if (error)
610 return error;
611 }
612
613 /*
614 * If we make a private mapping writable we increase our commit;
615 * but (without finer accounting) cannot reduce our commit if we
616 * make it unwritable again except in the anonymous case where no
617 * anon_vma has yet to be assigned.
618 *
619 * hugetlb mapping were accounted for even if read-only so there is
620 * no need to account for them here.
621 */
622 if (newflags & VM_WRITE) {
623 /* Check space limits when area turns into data. */
624 if (!may_expand_vm(mm, newflags, nrpages) &&
625 may_expand_vm(mm, oldflags, nrpages))
626 return -ENOMEM;
627 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
628 VM_SHARED|VM_NORESERVE))) {
629 charged = nrpages;
630 if (security_vm_enough_memory_mm(mm, charged))
631 return -ENOMEM;
632 newflags |= VM_ACCOUNT;
633 }
634 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) &&
635 !vma->anon_vma) {
636 newflags &= ~VM_ACCOUNT;
637 }
638
639 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags);
640 if (IS_ERR(vma)) {
641 error = PTR_ERR(vma);
642 goto fail;
643 }
644
645 *pprev = vma;
646
647 /*
648 * vm_flags and vm_page_prot are protected by the mmap_lock
649 * held in write mode.
650 */
651 vma_start_write(vma);
652 vm_flags_reset(vma, newflags);
653 if (vma_wants_manual_pte_write_upgrade(vma))
654 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
655 vma_set_page_prot(vma);
656
657 change_protection(tlb, vma, start, end, mm_cp_flags);
658
659 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT))
660 vm_unacct_memory(nrpages);
661
662 /*
663 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
664 * fault on access.
665 */
666 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
667 (newflags & VM_WRITE)) {
668 populate_vma_page_range(vma, start, end, NULL);
669 }
670
671 vm_stat_account(mm, oldflags, -nrpages);
672 vm_stat_account(mm, newflags, nrpages);
673 perf_event_mmap(vma);
674 return 0;
675
676 fail:
677 vm_unacct_memory(charged);
678 return error;
679 }
680
681 /*
682 * pkey==-1 when doing a legacy mprotect()
683 */
684 static int do_mprotect_pkey(unsigned long start, size_t len,
685 unsigned long prot, int pkey)
686 {
687 unsigned long nstart, end, tmp, reqprot;
688 struct vm_area_struct *vma, *prev;
689 int error;
690 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
691 const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
692 (prot & PROT_READ);
693 struct mmu_gather tlb;
694 struct vma_iterator vmi;
695
696 start = untagged_addr(start);
697
698 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
699 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
700 return -EINVAL;
701
702 if (start & ~PAGE_MASK)
703 return -EINVAL;
704 if (!len)
705 return 0;
706 len = PAGE_ALIGN(len);
707 end = start + len;
708 if (end <= start)
709 return -ENOMEM;
710 if (!arch_validate_prot(prot, start))
711 return -EINVAL;
712
713 reqprot = prot;
714
715 if (mmap_write_lock_killable(current->mm))
716 return -EINTR;
717
718 /*
719 * If userspace did not allocate the pkey, do not let
720 * them use it here.
721 */
722 error = -EINVAL;
723 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
724 goto out;
725
726 vma_iter_init(&vmi, current->mm, start);
727 vma = vma_find(&vmi, end);
728 error = -ENOMEM;
729 if (!vma)
730 goto out;
731
732 if (unlikely(grows & PROT_GROWSDOWN)) {
733 if (vma->vm_start >= end)
734 goto out;
735 start = vma->vm_start;
736 error = -EINVAL;
737 if (!(vma->vm_flags & VM_GROWSDOWN))
738 goto out;
739 } else {
740 if (vma->vm_start > start)
741 goto out;
742 if (unlikely(grows & PROT_GROWSUP)) {
743 end = vma->vm_end;
744 error = -EINVAL;
745 if (!(vma->vm_flags & VM_GROWSUP))
746 goto out;
747 }
748 }
749
750 /*
751 * checking if memory is sealed.
752 * can_modify_mm assumes we have acquired the lock on MM.
753 */
754 if (unlikely(!can_modify_mm(current->mm, start, end))) {
755 error = -EPERM;
756 goto out;
757 }
758
759 prev = vma_prev(&vmi);
760 if (start > vma->vm_start)
761 prev = vma;
762
763 tlb_gather_mmu(&tlb, current->mm);
764 nstart = start;
765 tmp = vma->vm_start;
766 for_each_vma_range(vmi, vma, end) {
767 unsigned long mask_off_old_flags;
768 unsigned long newflags;
769 int new_vma_pkey;
770
771 if (vma->vm_start != tmp) {
772 error = -ENOMEM;
773 break;
774 }
775
776 /* Does the application expect PROT_READ to imply PROT_EXEC */
777 if (rier && (vma->vm_flags & VM_MAYEXEC))
778 prot |= PROT_EXEC;
779
780 /*
781 * Each mprotect() call explicitly passes r/w/x permissions.
782 * If a permission is not passed to mprotect(), it must be
783 * cleared from the VMA.
784 */
785 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
786
787 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
788 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
789 newflags |= (vma->vm_flags & ~mask_off_old_flags);
790
791 /* newflags >> 4 shift VM_MAY% in place of VM_% */
792 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
793 error = -EACCES;
794 break;
795 }
796
797 if (map_deny_write_exec(vma, newflags)) {
798 error = -EACCES;
799 break;
800 }
801
802 /* Allow architectures to sanity-check the new flags */
803 if (!arch_validate_flags(newflags)) {
804 error = -EINVAL;
805 break;
806 }
807
808 error = security_file_mprotect(vma, reqprot, prot);
809 if (error)
810 break;
811
812 tmp = vma->vm_end;
813 if (tmp > end)
814 tmp = end;
815
816 if (vma->vm_ops && vma->vm_ops->mprotect) {
817 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
818 if (error)
819 break;
820 }
821
822 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
823 if (error)
824 break;
825
826 tmp = vma_iter_end(&vmi);
827 nstart = tmp;
828 prot = reqprot;
829 }
830 tlb_finish_mmu(&tlb);
831
832 if (!error && tmp < end)
833 error = -ENOMEM;
834
835 out:
836 mmap_write_unlock(current->mm);
837 return error;
838 }
839
840 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
841 unsigned long, prot)
842 {
843 return do_mprotect_pkey(start, len, prot, -1);
844 }
845
846 #ifdef CONFIG_ARCH_HAS_PKEYS
847
848 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
849 unsigned long, prot, int, pkey)
850 {
851 return do_mprotect_pkey(start, len, prot, pkey);
852 }
853
854 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
855 {
856 int pkey;
857 int ret;
858
859 /* No flags supported yet. */
860 if (flags)
861 return -EINVAL;
862 /* check for unsupported init values */
863 if (init_val & ~PKEY_ACCESS_MASK)
864 return -EINVAL;
865
866 mmap_write_lock(current->mm);
867 pkey = mm_pkey_alloc(current->mm);
868
869 ret = -ENOSPC;
870 if (pkey == -1)
871 goto out;
872
873 ret = arch_set_user_pkey_access(current, pkey, init_val);
874 if (ret) {
875 mm_pkey_free(current->mm, pkey);
876 goto out;
877 }
878 ret = pkey;
879 out:
880 mmap_write_unlock(current->mm);
881 return ret;
882 }
883
884 SYSCALL_DEFINE1(pkey_free, int, pkey)
885 {
886 int ret;
887
888 mmap_write_lock(current->mm);
889 ret = mm_pkey_free(current->mm, pkey);
890 mmap_write_unlock(current->mm);
891
892 /*
893 * We could provide warnings or errors if any VMA still
894 * has the pkey set here.
895 */
896 return ret;
897 }
898
899 #endif /* CONFIG_ARCH_HAS_PKEYS */
900
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.