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