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