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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/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 */
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}