Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * mm/mprotect.c
4 : *
5 : * (C) Copyright 1994 Linus Torvalds
6 : * (C) Copyright 2002 Christoph Hellwig
7 : *
8 : * Address space accounting code <alan@lxorguk.ukuu.org.uk>
9 : * (C) Copyright 2002 Red Hat Inc, All Rights Reserved
10 : */
11 :
12 : #include <linux/pagewalk.h>
13 : #include <linux/hugetlb.h>
14 : #include <linux/shm.h>
15 : #include <linux/mman.h>
16 : #include <linux/fs.h>
17 : #include <linux/highmem.h>
18 : #include <linux/security.h>
19 : #include <linux/mempolicy.h>
20 : #include <linux/personality.h>
21 : #include <linux/syscalls.h>
22 : #include <linux/swap.h>
23 : #include <linux/swapops.h>
24 : #include <linux/mmu_notifier.h>
25 : #include <linux/migrate.h>
26 : #include <linux/perf_event.h>
27 : #include <linux/pkeys.h>
28 : #include <linux/ksm.h>
29 : #include <linux/uaccess.h>
30 : #include <linux/mm_inline.h>
31 : #include <linux/pgtable.h>
32 : #include <linux/sched/sysctl.h>
33 : #include <linux/userfaultfd_k.h>
34 : #include <linux/memory-tiers.h>
35 : #include <asm/cacheflush.h>
36 : #include <asm/mmu_context.h>
37 : #include <asm/tlbflush.h>
38 : #include <asm/tlb.h>
39 :
40 : #include "internal.h"
41 :
42 0 : bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
43 : pte_t pte)
44 : {
45 : struct page *page;
46 :
47 0 : if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
48 : return false;
49 :
50 : /* Don't touch entries that are not even readable. */
51 0 : if (pte_protnone(pte))
52 : return false;
53 :
54 : /* Do we need write faults for softdirty tracking? */
55 0 : if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
56 : return false;
57 :
58 : /* Do we need write faults for uffd-wp tracking? */
59 0 : if (userfaultfd_pte_wp(vma, pte))
60 : return false;
61 :
62 0 : if (!(vma->vm_flags & VM_SHARED)) {
63 : /*
64 : * Writable MAP_PRIVATE mapping: We can only special-case on
65 : * exclusive anonymous pages, because we know that our
66 : * write-fault handler similarly would map them writable without
67 : * any additional checks while holding the PT lock.
68 : */
69 0 : page = vm_normal_page(vma, addr, pte);
70 0 : return page && PageAnon(page) && PageAnonExclusive(page);
71 : }
72 :
73 : /*
74 : * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
75 : * needs a real write-fault for writenotify
76 : * (see vma_wants_writenotify()). If "dirty", the assumption is that the
77 : * FS was already notified and we can simply mark the PTE writable
78 : * just like the write-fault handler would do.
79 : */
80 0 : return pte_dirty(pte);
81 : }
82 :
83 0 : static long change_pte_range(struct mmu_gather *tlb,
84 : struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr,
85 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
86 : {
87 : pte_t *pte, oldpte;
88 : spinlock_t *ptl;
89 0 : long pages = 0;
90 0 : int target_node = NUMA_NO_NODE;
91 0 : bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
92 0 : bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
93 0 : bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
94 :
95 0 : tlb_change_page_size(tlb, PAGE_SIZE);
96 0 : pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
97 0 : if (!pte)
98 : return -EAGAIN;
99 :
100 : /* Get target node for single threaded private VMAs */
101 0 : if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
102 0 : atomic_read(&vma->vm_mm->mm_users) == 1)
103 0 : target_node = numa_node_id();
104 :
105 0 : flush_tlb_batched_pending(vma->vm_mm);
106 : arch_enter_lazy_mmu_mode();
107 : do {
108 0 : oldpte = ptep_get(pte);
109 0 : if (pte_present(oldpte)) {
110 : pte_t ptent;
111 :
112 : /*
113 : * Avoid trapping faults against the zero or KSM
114 : * pages. See similar comment in change_huge_pmd.
115 : */
116 0 : if (prot_numa) {
117 : struct page *page;
118 : int nid;
119 : bool toptier;
120 :
121 : /* Avoid TLB flush if possible */
122 0 : if (pte_protnone(oldpte))
123 : continue;
124 :
125 0 : page = vm_normal_page(vma, addr, oldpte);
126 0 : if (!page || is_zone_device_page(page) || PageKsm(page))
127 0 : continue;
128 :
129 : /* Also skip shared copy-on-write pages */
130 0 : if (is_cow_mapping(vma->vm_flags) &&
131 0 : page_count(page) != 1)
132 0 : continue;
133 :
134 : /*
135 : * While migration can move some dirty pages,
136 : * it cannot move them all from MIGRATE_ASYNC
137 : * context.
138 : */
139 0 : if (page_is_file_lru(page) && PageDirty(page))
140 0 : continue;
141 :
142 : /*
143 : * Don't mess with PTEs if page is already on the node
144 : * a single-threaded process is running on.
145 : */
146 0 : nid = page_to_nid(page);
147 0 : if (target_node == nid)
148 0 : continue;
149 0 : toptier = node_is_toptier(nid);
150 :
151 : /*
152 : * Skip scanning top tier node if normal numa
153 : * balancing is disabled
154 : */
155 : if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
156 : toptier)
157 0 : continue;
158 : if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
159 : !toptier)
160 : xchg_page_access_time(page,
161 : jiffies_to_msecs(jiffies));
162 : }
163 :
164 0 : oldpte = ptep_modify_prot_start(vma, addr, pte);
165 0 : ptent = pte_modify(oldpte, newprot);
166 :
167 : if (uffd_wp)
168 : ptent = pte_mkuffd_wp(ptent);
169 : else if (uffd_wp_resolve)
170 : ptent = pte_clear_uffd_wp(ptent);
171 :
172 : /*
173 : * In some writable, shared mappings, we might want
174 : * to catch actual write access -- see
175 : * vma_wants_writenotify().
176 : *
177 : * In all writable, private mappings, we have to
178 : * properly handle COW.
179 : *
180 : * In both cases, we can sometimes still change PTEs
181 : * writable and avoid the write-fault handler, for
182 : * example, if a PTE is already dirty and no other
183 : * COW or special handling is required.
184 : */
185 0 : if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
186 0 : !pte_write(ptent) &&
187 0 : can_change_pte_writable(vma, addr, ptent))
188 : ptent = pte_mkwrite(ptent);
189 :
190 0 : ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
191 0 : if (pte_needs_flush(oldpte, ptent))
192 : tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
193 0 : pages++;
194 0 : } else if (is_swap_pte(oldpte)) {
195 0 : swp_entry_t entry = pte_to_swp_entry(oldpte);
196 : pte_t newpte;
197 :
198 0 : if (is_writable_migration_entry(entry)) {
199 0 : struct page *page = pfn_swap_entry_to_page(entry);
200 :
201 : /*
202 : * A protection check is difficult so
203 : * just be safe and disable write
204 : */
205 0 : if (PageAnon(page))
206 0 : entry = make_readable_exclusive_migration_entry(
207 : swp_offset(entry));
208 : else
209 0 : entry = make_readable_migration_entry(swp_offset(entry));
210 0 : newpte = swp_entry_to_pte(entry);
211 0 : if (pte_swp_soft_dirty(oldpte))
212 : newpte = pte_swp_mksoft_dirty(newpte);
213 0 : } else if (is_writable_device_private_entry(entry)) {
214 : /*
215 : * We do not preserve soft-dirtiness. See
216 : * copy_one_pte() for explanation.
217 : */
218 : entry = make_readable_device_private_entry(
219 : swp_offset(entry));
220 : newpte = swp_entry_to_pte(entry);
221 : if (pte_swp_uffd_wp(oldpte))
222 : newpte = pte_swp_mkuffd_wp(newpte);
223 0 : } else if (is_writable_device_exclusive_entry(entry)) {
224 : entry = make_readable_device_exclusive_entry(
225 : swp_offset(entry));
226 : newpte = swp_entry_to_pte(entry);
227 : if (pte_swp_soft_dirty(oldpte))
228 : newpte = pte_swp_mksoft_dirty(newpte);
229 : if (pte_swp_uffd_wp(oldpte))
230 : newpte = pte_swp_mkuffd_wp(newpte);
231 0 : } else if (is_pte_marker_entry(entry)) {
232 : /*
233 : * Ignore swapin errors unconditionally,
234 : * because any access should sigbus anyway.
235 : */
236 0 : if (is_swapin_error_entry(entry))
237 0 : continue;
238 : /*
239 : * If this is uffd-wp pte marker and we'd like
240 : * to unprotect it, drop it; the next page
241 : * fault will trigger without uffd trapping.
242 : */
243 0 : if (uffd_wp_resolve) {
244 0 : pte_clear(vma->vm_mm, addr, pte);
245 0 : pages++;
246 : }
247 0 : continue;
248 : } else {
249 : newpte = oldpte;
250 : }
251 :
252 : if (uffd_wp)
253 : newpte = pte_swp_mkuffd_wp(newpte);
254 : else if (uffd_wp_resolve)
255 : newpte = pte_swp_clear_uffd_wp(newpte);
256 :
257 0 : if (!pte_same(oldpte, newpte)) {
258 0 : set_pte_at(vma->vm_mm, addr, pte, newpte);
259 0 : pages++;
260 : }
261 : } else {
262 : /* It must be an none page, or what else?.. */
263 0 : WARN_ON_ONCE(!pte_none(oldpte));
264 :
265 : /*
266 : * Nobody plays with any none ptes besides
267 : * userfaultfd when applying the protections.
268 : */
269 0 : if (likely(!uffd_wp))
270 0 : continue;
271 :
272 : if (userfaultfd_wp_use_markers(vma)) {
273 : /*
274 : * For file-backed mem, we need to be able to
275 : * wr-protect a none pte, because even if the
276 : * pte is none, the page/swap cache could
277 : * exist. Doing that by install a marker.
278 : */
279 : set_pte_at(vma->vm_mm, addr, pte,
280 : make_pte_marker(PTE_MARKER_UFFD_WP));
281 : pages++;
282 : }
283 : }
284 0 : } while (pte++, addr += PAGE_SIZE, addr != end);
285 : arch_leave_lazy_mmu_mode();
286 0 : pte_unmap_unlock(pte - 1, ptl);
287 :
288 0 : return pages;
289 : }
290 :
291 : /*
292 : * Return true if we want to split THPs into PTE mappings in change
293 : * protection procedure, false otherwise.
294 : */
295 : static inline bool
296 : pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
297 : {
298 : /*
299 : * pte markers only resides in pte level, if we need pte markers,
300 : * we need to split. We cannot wr-protect shmem thp because file
301 : * thp is handled differently when split by erasing the pmd so far.
302 : */
303 : return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
304 : }
305 :
306 : /*
307 : * Return true if we want to populate pgtables in change protection
308 : * procedure, false otherwise
309 : */
310 : static inline bool
311 : pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
312 : {
313 : /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
314 : if (!(cp_flags & MM_CP_UFFD_WP))
315 : return false;
316 :
317 : /* Populate if the userfaultfd mode requires pte markers */
318 : return userfaultfd_wp_use_markers(vma);
319 : }
320 :
321 : /*
322 : * Populate the pgtable underneath for whatever reason if requested.
323 : * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
324 : * allocation failures during page faults by kicking OOM and returning
325 : * error.
326 : */
327 : #define change_pmd_prepare(vma, pmd, cp_flags) \
328 : ({ \
329 : long err = 0; \
330 : if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
331 : if (pte_alloc(vma->vm_mm, pmd)) \
332 : err = -ENOMEM; \
333 : } \
334 : err; \
335 : })
336 :
337 : /*
338 : * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
339 : * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
340 : * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
341 : */
342 : #define change_prepare(vma, high, low, addr, cp_flags) \
343 : ({ \
344 : long err = 0; \
345 : if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
346 : low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
347 : if (p == NULL) \
348 : err = -ENOMEM; \
349 : } \
350 : err; \
351 : })
352 :
353 0 : static inline long change_pmd_range(struct mmu_gather *tlb,
354 : struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
355 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
356 : {
357 : pmd_t *pmd;
358 : unsigned long next;
359 0 : long pages = 0;
360 0 : unsigned long nr_huge_updates = 0;
361 : struct mmu_notifier_range range;
362 :
363 0 : range.start = 0;
364 :
365 0 : pmd = pmd_offset(pud, addr);
366 : do {
367 : long ret;
368 : pmd_t _pmd;
369 : again:
370 0 : next = pmd_addr_end(addr, end);
371 :
372 0 : ret = change_pmd_prepare(vma, pmd, cp_flags);
373 : if (ret) {
374 : pages = ret;
375 : break;
376 : }
377 :
378 0 : if (pmd_none(*pmd))
379 : goto next;
380 :
381 : /* invoke the mmu notifier if the pmd is populated */
382 : if (!range.start) {
383 : mmu_notifier_range_init(&range,
384 : MMU_NOTIFY_PROTECTION_VMA, 0,
385 : vma->vm_mm, addr, end);
386 : mmu_notifier_invalidate_range_start(&range);
387 : }
388 :
389 0 : _pmd = pmdp_get_lockless(pmd);
390 0 : if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
391 : if ((next - addr != HPAGE_PMD_SIZE) ||
392 : pgtable_split_needed(vma, cp_flags)) {
393 : __split_huge_pmd(vma, pmd, addr, false, NULL);
394 : /*
395 : * For file-backed, the pmd could have been
396 : * cleared; make sure pmd populated if
397 : * necessary, then fall-through to pte level.
398 : */
399 : ret = change_pmd_prepare(vma, pmd, cp_flags);
400 : if (ret) {
401 : pages = ret;
402 : break;
403 : }
404 : } else {
405 : ret = change_huge_pmd(tlb, vma, pmd,
406 : addr, newprot, cp_flags);
407 : if (ret) {
408 : if (ret == HPAGE_PMD_NR) {
409 : pages += HPAGE_PMD_NR;
410 : nr_huge_updates++;
411 : }
412 :
413 : /* huge pmd was handled */
414 : goto next;
415 : }
416 : }
417 : /* fall through, the trans huge pmd just split */
418 : }
419 :
420 0 : ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
421 : cp_flags);
422 0 : if (ret < 0)
423 : goto again;
424 0 : pages += ret;
425 : next:
426 0 : cond_resched();
427 0 : } while (pmd++, addr = next, addr != end);
428 :
429 : if (range.start)
430 : mmu_notifier_invalidate_range_end(&range);
431 :
432 : if (nr_huge_updates)
433 : count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
434 0 : return pages;
435 : }
436 :
437 0 : static inline long change_pud_range(struct mmu_gather *tlb,
438 : struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
439 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
440 : {
441 : pud_t *pud;
442 : unsigned long next;
443 0 : long pages = 0, ret;
444 :
445 0 : pud = pud_offset(p4d, addr);
446 : do {
447 0 : next = pud_addr_end(addr, end);
448 0 : ret = change_prepare(vma, pud, pmd, addr, cp_flags);
449 : if (ret)
450 : return ret;
451 0 : if (pud_none_or_clear_bad(pud))
452 0 : continue;
453 0 : pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
454 : cp_flags);
455 0 : } while (pud++, addr = next, addr != end);
456 :
457 : return pages;
458 : }
459 :
460 : static inline long change_p4d_range(struct mmu_gather *tlb,
461 : struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
462 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
463 : {
464 : p4d_t *p4d;
465 : unsigned long next;
466 0 : long pages = 0, ret;
467 :
468 0 : p4d = p4d_offset(pgd, addr);
469 : do {
470 0 : next = p4d_addr_end(addr, end);
471 0 : ret = change_prepare(vma, p4d, pud, addr, cp_flags);
472 : if (ret)
473 : return ret;
474 0 : if (p4d_none_or_clear_bad(p4d))
475 : continue;
476 0 : pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
477 : cp_flags);
478 0 : } while (p4d++, addr = next, addr != end);
479 :
480 : return pages;
481 : }
482 :
483 0 : static long change_protection_range(struct mmu_gather *tlb,
484 : struct vm_area_struct *vma, unsigned long addr,
485 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
486 : {
487 0 : struct mm_struct *mm = vma->vm_mm;
488 : pgd_t *pgd;
489 : unsigned long next;
490 0 : long pages = 0, ret;
491 :
492 0 : BUG_ON(addr >= end);
493 0 : pgd = pgd_offset(mm, addr);
494 : tlb_start_vma(tlb, vma);
495 : do {
496 0 : next = pgd_addr_end(addr, end);
497 0 : ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
498 : if (ret) {
499 : pages = ret;
500 : break;
501 : }
502 0 : if (pgd_none_or_clear_bad(pgd))
503 : continue;
504 0 : pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
505 : cp_flags);
506 0 : } while (pgd++, addr = next, addr != end);
507 :
508 0 : tlb_end_vma(tlb, vma);
509 :
510 0 : return pages;
511 : }
512 :
513 0 : long change_protection(struct mmu_gather *tlb,
514 : struct vm_area_struct *vma, unsigned long start,
515 : unsigned long end, unsigned long cp_flags)
516 : {
517 0 : pgprot_t newprot = vma->vm_page_prot;
518 : long pages;
519 :
520 0 : BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
521 :
522 : #ifdef CONFIG_NUMA_BALANCING
523 : /*
524 : * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
525 : * are expected to reflect their requirements via VMA flags such that
526 : * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
527 : */
528 : if (cp_flags & MM_CP_PROT_NUMA)
529 : newprot = PAGE_NONE;
530 : #else
531 0 : WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
532 : #endif
533 :
534 0 : if (is_vm_hugetlb_page(vma))
535 : pages = hugetlb_change_protection(vma, start, end, newprot,
536 : cp_flags);
537 : else
538 0 : pages = change_protection_range(tlb, vma, start, end, newprot,
539 : cp_flags);
540 :
541 0 : return pages;
542 : }
543 :
544 : static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
545 : unsigned long next, struct mm_walk *walk)
546 : {
547 : return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
548 : *(pgprot_t *)(walk->private)) ?
549 : 0 : -EACCES;
550 : }
551 :
552 : static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
553 : unsigned long addr, unsigned long next,
554 : struct mm_walk *walk)
555 : {
556 : return pfn_modify_allowed(pte_pfn(ptep_get(pte)),
557 : *(pgprot_t *)(walk->private)) ?
558 : 0 : -EACCES;
559 : }
560 :
561 : static int prot_none_test(unsigned long addr, unsigned long next,
562 : struct mm_walk *walk)
563 : {
564 : return 0;
565 : }
566 :
567 : static const struct mm_walk_ops prot_none_walk_ops = {
568 : .pte_entry = prot_none_pte_entry,
569 : .hugetlb_entry = prot_none_hugetlb_entry,
570 : .test_walk = prot_none_test,
571 : };
572 :
573 : int
574 0 : mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
575 : struct vm_area_struct *vma, struct vm_area_struct **pprev,
576 : unsigned long start, unsigned long end, unsigned long newflags)
577 : {
578 0 : struct mm_struct *mm = vma->vm_mm;
579 0 : unsigned long oldflags = vma->vm_flags;
580 0 : long nrpages = (end - start) >> PAGE_SHIFT;
581 0 : unsigned int mm_cp_flags = 0;
582 0 : unsigned long charged = 0;
583 : pgoff_t pgoff;
584 : int error;
585 :
586 0 : if (newflags == oldflags) {
587 0 : *pprev = vma;
588 0 : return 0;
589 : }
590 :
591 : /*
592 : * Do PROT_NONE PFN permission checks here when we can still
593 : * bail out without undoing a lot of state. This is a rather
594 : * uncommon case, so doesn't need to be very optimized.
595 : */
596 : if (arch_has_pfn_modify_check() &&
597 : (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
598 : (newflags & VM_ACCESS_FLAGS) == 0) {
599 : pgprot_t new_pgprot = vm_get_page_prot(newflags);
600 :
601 : error = walk_page_range(current->mm, start, end,
602 : &prot_none_walk_ops, &new_pgprot);
603 : if (error)
604 : return error;
605 : }
606 :
607 : /*
608 : * If we make a private mapping writable we increase our commit;
609 : * but (without finer accounting) cannot reduce our commit if we
610 : * make it unwritable again. hugetlb mapping were accounted for
611 : * even if read-only so there is no need to account for them here
612 : */
613 0 : if (newflags & VM_WRITE) {
614 : /* Check space limits when area turns into data. */
615 0 : if (!may_expand_vm(mm, newflags, nrpages) &&
616 0 : may_expand_vm(mm, oldflags, nrpages))
617 : return -ENOMEM;
618 0 : if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
619 : VM_SHARED|VM_NORESERVE))) {
620 0 : charged = nrpages;
621 0 : if (security_vm_enough_memory_mm(mm, charged))
622 : return -ENOMEM;
623 0 : newflags |= VM_ACCOUNT;
624 : }
625 : }
626 :
627 : /*
628 : * First try to merge with previous and/or next vma.
629 : */
630 0 : pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
631 0 : *pprev = vma_merge(vmi, mm, *pprev, start, end, newflags,
632 : vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
633 : vma->vm_userfaultfd_ctx, anon_vma_name(vma));
634 0 : if (*pprev) {
635 : vma = *pprev;
636 : VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
637 : goto success;
638 : }
639 :
640 0 : *pprev = vma;
641 :
642 0 : if (start != vma->vm_start) {
643 0 : error = split_vma(vmi, vma, start, 1);
644 0 : if (error)
645 : goto fail;
646 : }
647 :
648 0 : if (end != vma->vm_end) {
649 0 : error = split_vma(vmi, vma, end, 0);
650 0 : if (error)
651 : goto fail;
652 : }
653 :
654 : success:
655 : /*
656 : * vm_flags and vm_page_prot are protected by the mmap_lock
657 : * held in write mode.
658 : */
659 0 : vm_flags_reset(vma, newflags);
660 0 : if (vma_wants_manual_pte_write_upgrade(vma))
661 0 : mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
662 0 : vma_set_page_prot(vma);
663 :
664 0 : change_protection(tlb, vma, start, end, mm_cp_flags);
665 :
666 : /*
667 : * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
668 : * fault on access.
669 : */
670 0 : if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
671 0 : (newflags & VM_WRITE)) {
672 0 : populate_vma_page_range(vma, start, end, NULL);
673 : }
674 :
675 0 : vm_stat_account(mm, oldflags, -nrpages);
676 0 : vm_stat_account(mm, newflags, nrpages);
677 0 : perf_event_mmap(vma);
678 0 : return 0;
679 :
680 : fail:
681 0 : vm_unacct_memory(charged);
682 0 : return error;
683 : }
684 :
685 : /*
686 : * pkey==-1 when doing a legacy mprotect()
687 : */
688 0 : static int do_mprotect_pkey(unsigned long start, size_t len,
689 : unsigned long prot, int pkey)
690 : {
691 : unsigned long nstart, end, tmp, reqprot;
692 : struct vm_area_struct *vma, *prev;
693 : int error;
694 0 : const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
695 0 : const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
696 0 : (prot & PROT_READ);
697 : struct mmu_gather tlb;
698 : struct vma_iterator vmi;
699 :
700 0 : start = untagged_addr(start);
701 :
702 0 : prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
703 0 : if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
704 : return -EINVAL;
705 :
706 0 : if (start & ~PAGE_MASK)
707 : return -EINVAL;
708 0 : if (!len)
709 : return 0;
710 0 : len = PAGE_ALIGN(len);
711 0 : end = start + len;
712 0 : if (end <= start)
713 : return -ENOMEM;
714 0 : if (!arch_validate_prot(prot, start))
715 : return -EINVAL;
716 :
717 0 : reqprot = prot;
718 :
719 0 : if (mmap_write_lock_killable(current->mm))
720 : return -EINTR;
721 :
722 : /*
723 : * If userspace did not allocate the pkey, do not let
724 : * them use it here.
725 : */
726 0 : error = -EINVAL;
727 0 : if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
728 : goto out;
729 :
730 0 : vma_iter_init(&vmi, current->mm, start);
731 0 : vma = vma_find(&vmi, end);
732 0 : error = -ENOMEM;
733 0 : if (!vma)
734 : goto out;
735 :
736 0 : if (unlikely(grows & PROT_GROWSDOWN)) {
737 0 : if (vma->vm_start >= end)
738 : goto out;
739 0 : start = vma->vm_start;
740 0 : error = -EINVAL;
741 0 : if (!(vma->vm_flags & VM_GROWSDOWN))
742 : goto out;
743 : } else {
744 0 : if (vma->vm_start > start)
745 : goto out;
746 0 : if (unlikely(grows & PROT_GROWSUP)) {
747 : end = vma->vm_end;
748 : error = -EINVAL;
749 : if (!(vma->vm_flags & VM_GROWSUP))
750 : goto out;
751 : }
752 : }
753 :
754 0 : prev = vma_prev(&vmi);
755 0 : if (start > vma->vm_start)
756 0 : prev = vma;
757 :
758 0 : tlb_gather_mmu(&tlb, current->mm);
759 0 : nstart = start;
760 0 : tmp = vma->vm_start;
761 0 : for_each_vma_range(vmi, vma, end) {
762 : unsigned long mask_off_old_flags;
763 : unsigned long newflags;
764 : int new_vma_pkey;
765 :
766 0 : if (vma->vm_start != tmp) {
767 : error = -ENOMEM;
768 : break;
769 : }
770 :
771 : /* Does the application expect PROT_READ to imply PROT_EXEC */
772 0 : if (rier && (vma->vm_flags & VM_MAYEXEC))
773 0 : prot |= PROT_EXEC;
774 :
775 : /*
776 : * Each mprotect() call explicitly passes r/w/x permissions.
777 : * If a permission is not passed to mprotect(), it must be
778 : * cleared from the VMA.
779 : */
780 0 : mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
781 :
782 0 : new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
783 0 : newflags = calc_vm_prot_bits(prot, new_vma_pkey);
784 0 : newflags |= (vma->vm_flags & ~mask_off_old_flags);
785 :
786 : /* newflags >> 4 shift VM_MAY% in place of VM_% */
787 0 : if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
788 : error = -EACCES;
789 : break;
790 : }
791 :
792 0 : if (map_deny_write_exec(vma, newflags)) {
793 : error = -EACCES;
794 : break;
795 : }
796 :
797 : /* Allow architectures to sanity-check the new flags */
798 0 : if (!arch_validate_flags(newflags)) {
799 : error = -EINVAL;
800 : break;
801 : }
802 :
803 0 : error = security_file_mprotect(vma, reqprot, prot);
804 : if (error)
805 : break;
806 :
807 0 : tmp = vma->vm_end;
808 0 : if (tmp > end)
809 0 : tmp = end;
810 :
811 0 : if (vma->vm_ops && vma->vm_ops->mprotect) {
812 0 : error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
813 0 : if (error)
814 : break;
815 : }
816 :
817 0 : error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
818 0 : if (error)
819 : break;
820 :
821 0 : tmp = vma_iter_end(&vmi);
822 0 : nstart = tmp;
823 0 : prot = reqprot;
824 : }
825 0 : tlb_finish_mmu(&tlb);
826 :
827 0 : if (!error && tmp < end)
828 0 : error = -ENOMEM;
829 :
830 : out:
831 0 : mmap_write_unlock(current->mm);
832 0 : return error;
833 : }
834 :
835 0 : SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
836 : unsigned long, prot)
837 : {
838 0 : return do_mprotect_pkey(start, len, prot, -1);
839 : }
840 :
841 : #ifdef CONFIG_ARCH_HAS_PKEYS
842 :
843 : SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
844 : unsigned long, prot, int, pkey)
845 : {
846 : return do_mprotect_pkey(start, len, prot, pkey);
847 : }
848 :
849 : SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
850 : {
851 : int pkey;
852 : int ret;
853 :
854 : /* No flags supported yet. */
855 : if (flags)
856 : return -EINVAL;
857 : /* check for unsupported init values */
858 : if (init_val & ~PKEY_ACCESS_MASK)
859 : return -EINVAL;
860 :
861 : mmap_write_lock(current->mm);
862 : pkey = mm_pkey_alloc(current->mm);
863 :
864 : ret = -ENOSPC;
865 : if (pkey == -1)
866 : goto out;
867 :
868 : ret = arch_set_user_pkey_access(current, pkey, init_val);
869 : if (ret) {
870 : mm_pkey_free(current->mm, pkey);
871 : goto out;
872 : }
873 : ret = pkey;
874 : out:
875 : mmap_write_unlock(current->mm);
876 : return ret;
877 : }
878 :
879 : SYSCALL_DEFINE1(pkey_free, int, pkey)
880 : {
881 : int ret;
882 :
883 : mmap_write_lock(current->mm);
884 : ret = mm_pkey_free(current->mm, pkey);
885 : mmap_write_unlock(current->mm);
886 :
887 : /*
888 : * We could provide warnings or errors if any VMA still
889 : * has the pkey set here.
890 : */
891 : return ret;
892 : }
893 :
894 : #endif /* CONFIG_ARCH_HAS_PKEYS */
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