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