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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/*
2 * mm/mprotect.c
3 *
4 * (C) Copyright 1994 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
9 */
10
11#include <linux/mm.h>
12#include <linux/hugetlb.h>
13#include <linux/shm.h>
14#include <linux/mman.h>
15#include <linux/fs.h>
16#include <linux/highmem.h>
17#include <linux/security.h>
18#include <linux/mempolicy.h>
19#include <linux/personality.h>
20#include <linux/syscalls.h>
21#include <linux/swap.h>
22#include <linux/swapops.h>
23#include <linux/mmu_notifier.h>
24#include <linux/migrate.h>
25#include <linux/perf_event.h>
26#include <asm/uaccess.h>
27#include <asm/pgtable.h>
28#include <asm/cacheflush.h>
29#include <asm/tlbflush.h>
30
31#ifndef pgprot_modify
32static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
33{
34 return newprot;
35}
36#endif
37
38static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
39 unsigned long addr, unsigned long end, pgprot_t newprot,
40 int dirty_accountable)
41{
42 pte_t *pte, oldpte;
43 spinlock_t *ptl;
44
45 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
46 arch_enter_lazy_mmu_mode();
47 do {
48 oldpte = *pte;
49 if (pte_present(oldpte)) {
50 pte_t ptent;
51
52 ptent = ptep_modify_prot_start(mm, addr, pte);
53 ptent = pte_modify(ptent, newprot);
54
55 /*
56 * Avoid taking write faults for pages we know to be
57 * dirty.
58 */
59 if (dirty_accountable && pte_dirty(ptent))
60 ptent = pte_mkwrite(ptent);
61
62 ptep_modify_prot_commit(mm, addr, pte, ptent);
63 } else if (PAGE_MIGRATION && !pte_file(oldpte)) {
64 swp_entry_t entry = pte_to_swp_entry(oldpte);
65
66 if (is_write_migration_entry(entry)) {
67 /*
68 * A protection check is difficult so
69 * just be safe and disable write
70 */
71 make_migration_entry_read(&entry);
72 set_pte_at(mm, addr, pte,
73 swp_entry_to_pte(entry));
74 }
75 }
76 } while (pte++, addr += PAGE_SIZE, addr != end);
77 arch_leave_lazy_mmu_mode();
78 pte_unmap_unlock(pte - 1, ptl);
79}
80
81static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
82 unsigned long addr, unsigned long end, pgprot_t newprot,
83 int dirty_accountable)
84{
85 pmd_t *pmd;
86 unsigned long next;
87
88 pmd = pmd_offset(pud, addr);
89 do {
90 next = pmd_addr_end(addr, end);
91 if (pmd_trans_huge(*pmd)) {
92 if (next - addr != HPAGE_PMD_SIZE)
93 split_huge_page_pmd(vma->vm_mm, pmd);
94 else if (change_huge_pmd(vma, pmd, addr, newprot))
95 continue;
96 /* fall through */
97 }
98 if (pmd_none_or_clear_bad(pmd))
99 continue;
100 change_pte_range(vma->vm_mm, pmd, addr, next, newprot,
101 dirty_accountable);
102 } while (pmd++, addr = next, addr != end);
103}
104
105static inline void change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
106 unsigned long addr, unsigned long end, pgprot_t newprot,
107 int dirty_accountable)
108{
109 pud_t *pud;
110 unsigned long next;
111
112 pud = pud_offset(pgd, addr);
113 do {
114 next = pud_addr_end(addr, end);
115 if (pud_none_or_clear_bad(pud))
116 continue;
117 change_pmd_range(vma, pud, addr, next, newprot,
118 dirty_accountable);
119 } while (pud++, addr = next, addr != end);
120}
121
122static void change_protection(struct vm_area_struct *vma,
123 unsigned long addr, unsigned long end, pgprot_t newprot,
124 int dirty_accountable)
125{
126 struct mm_struct *mm = vma->vm_mm;
127 pgd_t *pgd;
128 unsigned long next;
129 unsigned long start = addr;
130
131 BUG_ON(addr >= end);
132 pgd = pgd_offset(mm, addr);
133 flush_cache_range(vma, addr, end);
134 do {
135 next = pgd_addr_end(addr, end);
136 if (pgd_none_or_clear_bad(pgd))
137 continue;
138 change_pud_range(vma, pgd, addr, next, newprot,
139 dirty_accountable);
140 } while (pgd++, addr = next, addr != end);
141 flush_tlb_range(vma, start, end);
142}
143
144int
145mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
146 unsigned long start, unsigned long end, unsigned long newflags)
147{
148 struct mm_struct *mm = vma->vm_mm;
149 unsigned long oldflags = vma->vm_flags;
150 long nrpages = (end - start) >> PAGE_SHIFT;
151 unsigned long charged = 0;
152 pgoff_t pgoff;
153 int error;
154 int dirty_accountable = 0;
155
156 if (newflags == oldflags) {
157 *pprev = vma;
158 return 0;
159 }
160
161 /*
162 * If we make a private mapping writable we increase our commit;
163 * but (without finer accounting) cannot reduce our commit if we
164 * make it unwritable again. hugetlb mapping were accounted for
165 * even if read-only so there is no need to account for them here
166 */
167 if (newflags & VM_WRITE) {
168 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
169 VM_SHARED|VM_NORESERVE))) {
170 charged = nrpages;
171 if (security_vm_enough_memory(charged))
172 return -ENOMEM;
173 newflags |= VM_ACCOUNT;
174 }
175 }
176
177 /*
178 * First try to merge with previous and/or next vma.
179 */
180 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
181 *pprev = vma_merge(mm, *pprev, start, end, newflags,
182 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
183 if (*pprev) {
184 vma = *pprev;
185 goto success;
186 }
187
188 *pprev = vma;
189
190 if (start != vma->vm_start) {
191 error = split_vma(mm, vma, start, 1);
192 if (error)
193 goto fail;
194 }
195
196 if (end != vma->vm_end) {
197 error = split_vma(mm, vma, end, 0);
198 if (error)
199 goto fail;
200 }
201
202success:
203 /*
204 * vm_flags and vm_page_prot are protected by the mmap_sem
205 * held in write mode.
206 */
207 vma->vm_flags = newflags;
208 vma->vm_page_prot = pgprot_modify(vma->vm_page_prot,
209 vm_get_page_prot(newflags));
210
211 if (vma_wants_writenotify(vma)) {
212 vma->vm_page_prot = vm_get_page_prot(newflags & ~VM_SHARED);
213 dirty_accountable = 1;
214 }
215
216 mmu_notifier_invalidate_range_start(mm, start, end);
217 if (is_vm_hugetlb_page(vma))
218 hugetlb_change_protection(vma, start, end, vma->vm_page_prot);
219 else
220 change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable);
221 mmu_notifier_invalidate_range_end(mm, start, end);
222 vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
223 vm_stat_account(mm, newflags, vma->vm_file, nrpages);
224 perf_event_mmap(vma);
225 return 0;
226
227fail:
228 vm_unacct_memory(charged);
229 return error;
230}
231
232SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
233 unsigned long, prot)
234{
235 unsigned long vm_flags, nstart, end, tmp, reqprot;
236 struct vm_area_struct *vma, *prev;
237 int error = -EINVAL;
238 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
239 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
240 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
241 return -EINVAL;
242
243 if (start & ~PAGE_MASK)
244 return -EINVAL;
245 if (!len)
246 return 0;
247 len = PAGE_ALIGN(len);
248 end = start + len;
249 if (end <= start)
250 return -ENOMEM;
251 if (!arch_validate_prot(prot))
252 return -EINVAL;
253
254 reqprot = prot;
255 /*
256 * Does the application expect PROT_READ to imply PROT_EXEC:
257 */
258 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
259 prot |= PROT_EXEC;
260
261 vm_flags = calc_vm_prot_bits(prot);
262
263 down_write(¤t->mm->mmap_sem);
264
265 vma = find_vma_prev(current->mm, start, &prev);
266 error = -ENOMEM;
267 if (!vma)
268 goto out;
269 if (unlikely(grows & PROT_GROWSDOWN)) {
270 if (vma->vm_start >= end)
271 goto out;
272 start = vma->vm_start;
273 error = -EINVAL;
274 if (!(vma->vm_flags & VM_GROWSDOWN))
275 goto out;
276 }
277 else {
278 if (vma->vm_start > start)
279 goto out;
280 if (unlikely(grows & PROT_GROWSUP)) {
281 end = vma->vm_end;
282 error = -EINVAL;
283 if (!(vma->vm_flags & VM_GROWSUP))
284 goto out;
285 }
286 }
287 if (start > vma->vm_start)
288 prev = vma;
289
290 for (nstart = start ; ; ) {
291 unsigned long newflags;
292
293 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
294
295 newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
296
297 /* newflags >> 4 shift VM_MAY% in place of VM_% */
298 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
299 error = -EACCES;
300 goto out;
301 }
302
303 error = security_file_mprotect(vma, reqprot, prot);
304 if (error)
305 goto out;
306
307 tmp = vma->vm_end;
308 if (tmp > end)
309 tmp = end;
310 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
311 if (error)
312 goto out;
313 nstart = tmp;
314
315 if (nstart < prev->vm_end)
316 nstart = prev->vm_end;
317 if (nstart >= end)
318 goto out;
319
320 vma = prev->vm_next;
321 if (!vma || vma->vm_start != nstart) {
322 error = -ENOMEM;
323 goto out;
324 }
325 }
326out:
327 up_write(¤t->mm->mmap_sem);
328 return error;
329}