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 :
97 : /*
98 : * Can be called with only the mmap_lock for reading by
99 : * prot_numa so we must check the pmd isn't constantly
100 : * changing from under us from pmd_none to pmd_trans_huge
101 : * and/or the other way around.
102 : */
103 0 : if (pmd_trans_unstable(pmd))
104 : return 0;
105 :
106 : /*
107 : * The pmd points to a regular pte so the pmd can't change
108 : * from under us even if the mmap_lock is only hold for
109 : * reading.
110 : */
111 0 : pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
112 :
113 : /* Get target node for single threaded private VMAs */
114 0 : if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
115 0 : atomic_read(&vma->vm_mm->mm_users) == 1)
116 0 : target_node = numa_node_id();
117 :
118 0 : flush_tlb_batched_pending(vma->vm_mm);
119 : arch_enter_lazy_mmu_mode();
120 : do {
121 0 : oldpte = *pte;
122 0 : if (pte_present(oldpte)) {
123 : pte_t ptent;
124 :
125 : /*
126 : * Avoid trapping faults against the zero or KSM
127 : * pages. See similar comment in change_huge_pmd.
128 : */
129 0 : if (prot_numa) {
130 : struct page *page;
131 : int nid;
132 : bool toptier;
133 :
134 : /* Avoid TLB flush if possible */
135 0 : if (pte_protnone(oldpte))
136 : continue;
137 :
138 0 : page = vm_normal_page(vma, addr, oldpte);
139 0 : if (!page || is_zone_device_page(page) || PageKsm(page))
140 0 : continue;
141 :
142 : /* Also skip shared copy-on-write pages */
143 0 : if (is_cow_mapping(vma->vm_flags) &&
144 0 : page_count(page) != 1)
145 0 : continue;
146 :
147 : /*
148 : * While migration can move some dirty pages,
149 : * it cannot move them all from MIGRATE_ASYNC
150 : * context.
151 : */
152 0 : if (page_is_file_lru(page) && PageDirty(page))
153 0 : continue;
154 :
155 : /*
156 : * Don't mess with PTEs if page is already on the node
157 : * a single-threaded process is running on.
158 : */
159 0 : nid = page_to_nid(page);
160 0 : if (target_node == nid)
161 0 : continue;
162 0 : toptier = node_is_toptier(nid);
163 :
164 : /*
165 : * Skip scanning top tier node if normal numa
166 : * balancing is disabled
167 : */
168 : if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
169 : toptier)
170 0 : continue;
171 : if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
172 : !toptier)
173 : xchg_page_access_time(page,
174 : jiffies_to_msecs(jiffies));
175 : }
176 :
177 0 : oldpte = ptep_modify_prot_start(vma, addr, pte);
178 0 : ptent = pte_modify(oldpte, newprot);
179 :
180 : if (uffd_wp)
181 : ptent = pte_mkuffd_wp(ptent);
182 : else if (uffd_wp_resolve)
183 : ptent = pte_clear_uffd_wp(ptent);
184 :
185 : /*
186 : * In some writable, shared mappings, we might want
187 : * to catch actual write access -- see
188 : * vma_wants_writenotify().
189 : *
190 : * In all writable, private mappings, we have to
191 : * properly handle COW.
192 : *
193 : * In both cases, we can sometimes still change PTEs
194 : * writable and avoid the write-fault handler, for
195 : * example, if a PTE is already dirty and no other
196 : * COW or special handling is required.
197 : */
198 0 : if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
199 0 : !pte_write(ptent) &&
200 0 : can_change_pte_writable(vma, addr, ptent))
201 : ptent = pte_mkwrite(ptent);
202 :
203 0 : ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
204 0 : if (pte_needs_flush(oldpte, ptent))
205 : tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
206 0 : pages++;
207 0 : } else if (is_swap_pte(oldpte)) {
208 0 : swp_entry_t entry = pte_to_swp_entry(oldpte);
209 : pte_t newpte;
210 :
211 0 : if (is_writable_migration_entry(entry)) {
212 0 : struct page *page = pfn_swap_entry_to_page(entry);
213 :
214 : /*
215 : * A protection check is difficult so
216 : * just be safe and disable write
217 : */
218 0 : if (PageAnon(page))
219 0 : entry = make_readable_exclusive_migration_entry(
220 : swp_offset(entry));
221 : else
222 0 : entry = make_readable_migration_entry(swp_offset(entry));
223 0 : newpte = swp_entry_to_pte(entry);
224 0 : if (pte_swp_soft_dirty(oldpte))
225 : newpte = pte_swp_mksoft_dirty(newpte);
226 0 : } else if (is_writable_device_private_entry(entry)) {
227 : /*
228 : * We do not preserve soft-dirtiness. See
229 : * copy_one_pte() for explanation.
230 : */
231 : entry = make_readable_device_private_entry(
232 : swp_offset(entry));
233 : newpte = swp_entry_to_pte(entry);
234 : if (pte_swp_uffd_wp(oldpte))
235 : newpte = pte_swp_mkuffd_wp(newpte);
236 0 : } else if (is_writable_device_exclusive_entry(entry)) {
237 : entry = make_readable_device_exclusive_entry(
238 : swp_offset(entry));
239 : newpte = swp_entry_to_pte(entry);
240 : if (pte_swp_soft_dirty(oldpte))
241 : newpte = pte_swp_mksoft_dirty(newpte);
242 : if (pte_swp_uffd_wp(oldpte))
243 : newpte = pte_swp_mkuffd_wp(newpte);
244 0 : } else if (is_pte_marker_entry(entry)) {
245 : /*
246 : * Ignore swapin errors unconditionally,
247 : * because any access should sigbus anyway.
248 : */
249 0 : if (is_swapin_error_entry(entry))
250 0 : continue;
251 : /*
252 : * If this is uffd-wp pte marker and we'd like
253 : * to unprotect it, drop it; the next page
254 : * fault will trigger without uffd trapping.
255 : */
256 0 : if (uffd_wp_resolve) {
257 0 : pte_clear(vma->vm_mm, addr, pte);
258 0 : pages++;
259 : }
260 0 : continue;
261 : } else {
262 : newpte = oldpte;
263 : }
264 :
265 : if (uffd_wp)
266 : newpte = pte_swp_mkuffd_wp(newpte);
267 : else if (uffd_wp_resolve)
268 : newpte = pte_swp_clear_uffd_wp(newpte);
269 :
270 0 : if (!pte_same(oldpte, newpte)) {
271 0 : set_pte_at(vma->vm_mm, addr, pte, newpte);
272 0 : pages++;
273 : }
274 : } else {
275 : /* It must be an none page, or what else?.. */
276 0 : WARN_ON_ONCE(!pte_none(oldpte));
277 :
278 : /*
279 : * Nobody plays with any none ptes besides
280 : * userfaultfd when applying the protections.
281 : */
282 0 : if (likely(!uffd_wp))
283 0 : continue;
284 :
285 : if (userfaultfd_wp_use_markers(vma)) {
286 : /*
287 : * For file-backed mem, we need to be able to
288 : * wr-protect a none pte, because even if the
289 : * pte is none, the page/swap cache could
290 : * exist. Doing that by install a marker.
291 : */
292 : set_pte_at(vma->vm_mm, addr, pte,
293 : make_pte_marker(PTE_MARKER_UFFD_WP));
294 : pages++;
295 : }
296 : }
297 0 : } while (pte++, addr += PAGE_SIZE, addr != end);
298 : arch_leave_lazy_mmu_mode();
299 0 : pte_unmap_unlock(pte - 1, ptl);
300 :
301 : return pages;
302 : }
303 :
304 : /*
305 : * Used when setting automatic NUMA hinting protection where it is
306 : * critical that a numa hinting PMD is not confused with a bad PMD.
307 : */
308 : static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
309 : {
310 0 : pmd_t pmdval = pmdp_get_lockless(pmd);
311 :
312 : /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
313 : #ifdef CONFIG_TRANSPARENT_HUGEPAGE
314 : barrier();
315 : #endif
316 :
317 0 : if (pmd_none(pmdval))
318 : return 1;
319 0 : if (pmd_trans_huge(pmdval))
320 : return 0;
321 0 : if (unlikely(pmd_bad(pmdval))) {
322 0 : pmd_clear_bad(pmd);
323 : return 1;
324 : }
325 :
326 : return 0;
327 : }
328 :
329 : /*
330 : * Return true if we want to split THPs into PTE mappings in change
331 : * protection procedure, false otherwise.
332 : */
333 : static inline bool
334 : pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
335 : {
336 : /*
337 : * pte markers only resides in pte level, if we need pte markers,
338 : * we need to split. We cannot wr-protect shmem thp because file
339 : * thp is handled differently when split by erasing the pmd so far.
340 : */
341 : return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
342 : }
343 :
344 : /*
345 : * Return true if we want to populate pgtables in change protection
346 : * procedure, false otherwise
347 : */
348 : static inline bool
349 : pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
350 : {
351 : /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
352 : if (!(cp_flags & MM_CP_UFFD_WP))
353 : return false;
354 :
355 : /* Populate if the userfaultfd mode requires pte markers */
356 : return userfaultfd_wp_use_markers(vma);
357 : }
358 :
359 : /*
360 : * Populate the pgtable underneath for whatever reason if requested.
361 : * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
362 : * allocation failures during page faults by kicking OOM and returning
363 : * error.
364 : */
365 : #define change_pmd_prepare(vma, pmd, cp_flags) \
366 : ({ \
367 : long err = 0; \
368 : if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
369 : if (pte_alloc(vma->vm_mm, pmd)) \
370 : err = -ENOMEM; \
371 : } \
372 : err; \
373 : })
374 :
375 : /*
376 : * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
377 : * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
378 : * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
379 : */
380 : #define change_prepare(vma, high, low, addr, cp_flags) \
381 : ({ \
382 : long err = 0; \
383 : if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
384 : low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
385 : if (p == NULL) \
386 : err = -ENOMEM; \
387 : } \
388 : err; \
389 : })
390 :
391 0 : static inline long change_pmd_range(struct mmu_gather *tlb,
392 : struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
393 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
394 : {
395 : pmd_t *pmd;
396 : unsigned long next;
397 0 : long pages = 0;
398 0 : unsigned long nr_huge_updates = 0;
399 : struct mmu_notifier_range range;
400 :
401 0 : range.start = 0;
402 :
403 0 : pmd = pmd_offset(pud, addr);
404 : do {
405 : long ret;
406 :
407 0 : next = pmd_addr_end(addr, end);
408 :
409 0 : ret = change_pmd_prepare(vma, pmd, cp_flags);
410 : if (ret) {
411 : pages = ret;
412 : break;
413 : }
414 : /*
415 : * Automatic NUMA balancing walks the tables with mmap_lock
416 : * held for read. It's possible a parallel update to occur
417 : * between pmd_trans_huge() and a pmd_none_or_clear_bad()
418 : * check leading to a false positive and clearing.
419 : * Hence, it's necessary to atomically read the PMD value
420 : * for all the checks.
421 : */
422 0 : if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
423 0 : pmd_none_or_clear_bad_unless_trans_huge(pmd))
424 : goto next;
425 :
426 : /* invoke the mmu notifier if the pmd is populated */
427 : if (!range.start) {
428 : mmu_notifier_range_init(&range,
429 : MMU_NOTIFY_PROTECTION_VMA, 0,
430 : vma->vm_mm, addr, end);
431 : mmu_notifier_invalidate_range_start(&range);
432 : }
433 :
434 0 : if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
435 : if ((next - addr != HPAGE_PMD_SIZE) ||
436 : pgtable_split_needed(vma, cp_flags)) {
437 : __split_huge_pmd(vma, pmd, addr, false, NULL);
438 : /*
439 : * For file-backed, the pmd could have been
440 : * cleared; make sure pmd populated if
441 : * necessary, then fall-through to pte level.
442 : */
443 : ret = change_pmd_prepare(vma, pmd, cp_flags);
444 : if (ret) {
445 : pages = ret;
446 : break;
447 : }
448 : } else {
449 : /*
450 : * change_huge_pmd() does not defer TLB flushes,
451 : * so no need to propagate the tlb argument.
452 : */
453 : int nr_ptes = change_huge_pmd(tlb, vma, pmd,
454 : addr, newprot, cp_flags);
455 :
456 : if (nr_ptes) {
457 : if (nr_ptes == HPAGE_PMD_NR) {
458 : pages += HPAGE_PMD_NR;
459 : nr_huge_updates++;
460 : }
461 :
462 : /* huge pmd was handled */
463 : goto next;
464 : }
465 : }
466 : /* fall through, the trans huge pmd just split */
467 : }
468 0 : pages += change_pte_range(tlb, vma, pmd, addr, next,
469 : newprot, cp_flags);
470 : next:
471 0 : cond_resched();
472 0 : } while (pmd++, addr = next, addr != end);
473 :
474 : if (range.start)
475 : mmu_notifier_invalidate_range_end(&range);
476 :
477 : if (nr_huge_updates)
478 : count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
479 0 : return pages;
480 : }
481 :
482 0 : static inline long change_pud_range(struct mmu_gather *tlb,
483 : struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
484 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
485 : {
486 : pud_t *pud;
487 : unsigned long next;
488 0 : long pages = 0, ret;
489 :
490 0 : pud = pud_offset(p4d, addr);
491 : do {
492 0 : next = pud_addr_end(addr, end);
493 0 : ret = change_prepare(vma, pud, pmd, addr, cp_flags);
494 : if (ret)
495 : return ret;
496 0 : if (pud_none_or_clear_bad(pud))
497 0 : continue;
498 0 : pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
499 : cp_flags);
500 0 : } while (pud++, addr = next, addr != end);
501 :
502 : return pages;
503 : }
504 :
505 : static inline long change_p4d_range(struct mmu_gather *tlb,
506 : struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
507 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
508 : {
509 : p4d_t *p4d;
510 : unsigned long next;
511 0 : long pages = 0, ret;
512 :
513 0 : p4d = p4d_offset(pgd, addr);
514 : do {
515 0 : next = p4d_addr_end(addr, end);
516 0 : ret = change_prepare(vma, p4d, pud, addr, cp_flags);
517 : if (ret)
518 : return ret;
519 0 : if (p4d_none_or_clear_bad(p4d))
520 : continue;
521 0 : pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
522 : cp_flags);
523 0 : } while (p4d++, addr = next, addr != end);
524 :
525 : return pages;
526 : }
527 :
528 0 : static long change_protection_range(struct mmu_gather *tlb,
529 : struct vm_area_struct *vma, unsigned long addr,
530 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
531 : {
532 0 : struct mm_struct *mm = vma->vm_mm;
533 : pgd_t *pgd;
534 : unsigned long next;
535 0 : long pages = 0, ret;
536 :
537 0 : BUG_ON(addr >= end);
538 0 : pgd = pgd_offset(mm, addr);
539 : tlb_start_vma(tlb, vma);
540 : do {
541 0 : next = pgd_addr_end(addr, end);
542 0 : ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
543 : if (ret) {
544 : pages = ret;
545 : break;
546 : }
547 0 : if (pgd_none_or_clear_bad(pgd))
548 : continue;
549 0 : pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
550 : cp_flags);
551 0 : } while (pgd++, addr = next, addr != end);
552 :
553 0 : tlb_end_vma(tlb, vma);
554 :
555 0 : return pages;
556 : }
557 :
558 0 : long change_protection(struct mmu_gather *tlb,
559 : struct vm_area_struct *vma, unsigned long start,
560 : unsigned long end, unsigned long cp_flags)
561 : {
562 0 : pgprot_t newprot = vma->vm_page_prot;
563 : long pages;
564 :
565 0 : BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
566 :
567 : #ifdef CONFIG_NUMA_BALANCING
568 : /*
569 : * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
570 : * are expected to reflect their requirements via VMA flags such that
571 : * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
572 : */
573 : if (cp_flags & MM_CP_PROT_NUMA)
574 : newprot = PAGE_NONE;
575 : #else
576 0 : WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
577 : #endif
578 :
579 0 : if (is_vm_hugetlb_page(vma))
580 : pages = hugetlb_change_protection(vma, start, end, newprot,
581 : cp_flags);
582 : else
583 0 : pages = change_protection_range(tlb, vma, start, end, newprot,
584 : cp_flags);
585 :
586 0 : return pages;
587 : }
588 :
589 : static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
590 : unsigned long next, struct mm_walk *walk)
591 : {
592 : return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
593 : 0 : -EACCES;
594 : }
595 :
596 : static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
597 : unsigned long addr, unsigned long next,
598 : struct mm_walk *walk)
599 : {
600 : return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
601 : 0 : -EACCES;
602 : }
603 :
604 : static int prot_none_test(unsigned long addr, unsigned long next,
605 : struct mm_walk *walk)
606 : {
607 : return 0;
608 : }
609 :
610 : static const struct mm_walk_ops prot_none_walk_ops = {
611 : .pte_entry = prot_none_pte_entry,
612 : .hugetlb_entry = prot_none_hugetlb_entry,
613 : .test_walk = prot_none_test,
614 : };
615 :
616 : int
617 0 : mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
618 : struct vm_area_struct *vma, struct vm_area_struct **pprev,
619 : unsigned long start, unsigned long end, unsigned long newflags)
620 : {
621 0 : struct mm_struct *mm = vma->vm_mm;
622 0 : unsigned long oldflags = vma->vm_flags;
623 0 : long nrpages = (end - start) >> PAGE_SHIFT;
624 0 : unsigned int mm_cp_flags = 0;
625 0 : unsigned long charged = 0;
626 : pgoff_t pgoff;
627 : int error;
628 :
629 0 : if (newflags == oldflags) {
630 0 : *pprev = vma;
631 0 : return 0;
632 : }
633 :
634 : /*
635 : * Do PROT_NONE PFN permission checks here when we can still
636 : * bail out without undoing a lot of state. This is a rather
637 : * uncommon case, so doesn't need to be very optimized.
638 : */
639 : if (arch_has_pfn_modify_check() &&
640 : (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
641 : (newflags & VM_ACCESS_FLAGS) == 0) {
642 : pgprot_t new_pgprot = vm_get_page_prot(newflags);
643 :
644 : error = walk_page_range(current->mm, start, end,
645 : &prot_none_walk_ops, &new_pgprot);
646 : if (error)
647 : return error;
648 : }
649 :
650 : /*
651 : * If we make a private mapping writable we increase our commit;
652 : * but (without finer accounting) cannot reduce our commit if we
653 : * make it unwritable again. hugetlb mapping were accounted for
654 : * even if read-only so there is no need to account for them here
655 : */
656 0 : if (newflags & VM_WRITE) {
657 : /* Check space limits when area turns into data. */
658 0 : if (!may_expand_vm(mm, newflags, nrpages) &&
659 0 : may_expand_vm(mm, oldflags, nrpages))
660 : return -ENOMEM;
661 0 : if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
662 : VM_SHARED|VM_NORESERVE))) {
663 0 : charged = nrpages;
664 0 : if (security_vm_enough_memory_mm(mm, charged))
665 : return -ENOMEM;
666 0 : newflags |= VM_ACCOUNT;
667 : }
668 : }
669 :
670 : /*
671 : * First try to merge with previous and/or next vma.
672 : */
673 0 : pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
674 0 : *pprev = vma_merge(vmi, mm, *pprev, start, end, newflags,
675 : vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
676 : vma->vm_userfaultfd_ctx, anon_vma_name(vma));
677 0 : if (*pprev) {
678 : vma = *pprev;
679 : VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
680 : goto success;
681 : }
682 :
683 0 : *pprev = vma;
684 :
685 0 : if (start != vma->vm_start) {
686 0 : error = split_vma(vmi, vma, start, 1);
687 0 : if (error)
688 : goto fail;
689 : }
690 :
691 0 : if (end != vma->vm_end) {
692 0 : error = split_vma(vmi, vma, end, 0);
693 0 : if (error)
694 : goto fail;
695 : }
696 :
697 : success:
698 : /*
699 : * vm_flags and vm_page_prot are protected by the mmap_lock
700 : * held in write mode.
701 : */
702 0 : vm_flags_reset(vma, newflags);
703 0 : if (vma_wants_manual_pte_write_upgrade(vma))
704 0 : mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
705 0 : vma_set_page_prot(vma);
706 :
707 0 : change_protection(tlb, vma, start, end, mm_cp_flags);
708 :
709 : /*
710 : * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
711 : * fault on access.
712 : */
713 0 : if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
714 0 : (newflags & VM_WRITE)) {
715 0 : populate_vma_page_range(vma, start, end, NULL);
716 : }
717 :
718 0 : vm_stat_account(mm, oldflags, -nrpages);
719 0 : vm_stat_account(mm, newflags, nrpages);
720 0 : perf_event_mmap(vma);
721 0 : return 0;
722 :
723 : fail:
724 0 : vm_unacct_memory(charged);
725 0 : return error;
726 : }
727 :
728 : /*
729 : * pkey==-1 when doing a legacy mprotect()
730 : */
731 0 : static int do_mprotect_pkey(unsigned long start, size_t len,
732 : unsigned long prot, int pkey)
733 : {
734 : unsigned long nstart, end, tmp, reqprot;
735 : struct vm_area_struct *vma, *prev;
736 : int error;
737 0 : const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
738 0 : const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
739 0 : (prot & PROT_READ);
740 : struct mmu_gather tlb;
741 : struct vma_iterator vmi;
742 :
743 0 : start = untagged_addr(start);
744 :
745 0 : prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
746 0 : if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
747 : return -EINVAL;
748 :
749 0 : if (start & ~PAGE_MASK)
750 : return -EINVAL;
751 0 : if (!len)
752 : return 0;
753 0 : len = PAGE_ALIGN(len);
754 0 : end = start + len;
755 0 : if (end <= start)
756 : return -ENOMEM;
757 0 : if (!arch_validate_prot(prot, start))
758 : return -EINVAL;
759 :
760 0 : reqprot = prot;
761 :
762 0 : if (mmap_write_lock_killable(current->mm))
763 : return -EINTR;
764 :
765 : /*
766 : * If userspace did not allocate the pkey, do not let
767 : * them use it here.
768 : */
769 0 : error = -EINVAL;
770 0 : if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
771 : goto out;
772 :
773 0 : vma_iter_init(&vmi, current->mm, start);
774 0 : vma = vma_find(&vmi, end);
775 0 : error = -ENOMEM;
776 0 : if (!vma)
777 : goto out;
778 :
779 0 : if (unlikely(grows & PROT_GROWSDOWN)) {
780 0 : if (vma->vm_start >= end)
781 : goto out;
782 0 : start = vma->vm_start;
783 0 : error = -EINVAL;
784 0 : if (!(vma->vm_flags & VM_GROWSDOWN))
785 : goto out;
786 : } else {
787 0 : if (vma->vm_start > start)
788 : goto out;
789 0 : if (unlikely(grows & PROT_GROWSUP)) {
790 : end = vma->vm_end;
791 : error = -EINVAL;
792 : if (!(vma->vm_flags & VM_GROWSUP))
793 : goto out;
794 : }
795 : }
796 :
797 0 : prev = vma_prev(&vmi);
798 0 : if (start > vma->vm_start)
799 0 : prev = vma;
800 :
801 0 : tlb_gather_mmu(&tlb, current->mm);
802 0 : nstart = start;
803 0 : tmp = vma->vm_start;
804 0 : for_each_vma_range(vmi, vma, end) {
805 : unsigned long mask_off_old_flags;
806 : unsigned long newflags;
807 : int new_vma_pkey;
808 :
809 0 : if (vma->vm_start != tmp) {
810 : error = -ENOMEM;
811 : break;
812 : }
813 :
814 : /* Does the application expect PROT_READ to imply PROT_EXEC */
815 0 : if (rier && (vma->vm_flags & VM_MAYEXEC))
816 0 : prot |= PROT_EXEC;
817 :
818 : /*
819 : * Each mprotect() call explicitly passes r/w/x permissions.
820 : * If a permission is not passed to mprotect(), it must be
821 : * cleared from the VMA.
822 : */
823 0 : mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
824 :
825 0 : new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
826 0 : newflags = calc_vm_prot_bits(prot, new_vma_pkey);
827 0 : newflags |= (vma->vm_flags & ~mask_off_old_flags);
828 :
829 : /* newflags >> 4 shift VM_MAY% in place of VM_% */
830 0 : if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
831 : error = -EACCES;
832 : break;
833 : }
834 :
835 0 : if (map_deny_write_exec(vma, newflags)) {
836 : error = -EACCES;
837 : break;
838 : }
839 :
840 : /* Allow architectures to sanity-check the new flags */
841 0 : if (!arch_validate_flags(newflags)) {
842 : error = -EINVAL;
843 : break;
844 : }
845 :
846 0 : error = security_file_mprotect(vma, reqprot, prot);
847 : if (error)
848 : break;
849 :
850 0 : tmp = vma->vm_end;
851 0 : if (tmp > end)
852 0 : tmp = end;
853 :
854 0 : if (vma->vm_ops && vma->vm_ops->mprotect) {
855 0 : error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
856 0 : if (error)
857 : break;
858 : }
859 :
860 0 : error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
861 0 : if (error)
862 : break;
863 :
864 0 : tmp = vma_iter_end(&vmi);
865 0 : nstart = tmp;
866 0 : prot = reqprot;
867 : }
868 0 : tlb_finish_mmu(&tlb);
869 :
870 0 : if (!error && vma_iter_end(&vmi) < end)
871 0 : error = -ENOMEM;
872 :
873 : out:
874 0 : mmap_write_unlock(current->mm);
875 0 : return error;
876 : }
877 :
878 0 : SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
879 : unsigned long, prot)
880 : {
881 0 : return do_mprotect_pkey(start, len, prot, -1);
882 : }
883 :
884 : #ifdef CONFIG_ARCH_HAS_PKEYS
885 :
886 : SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
887 : unsigned long, prot, int, pkey)
888 : {
889 : return do_mprotect_pkey(start, len, prot, pkey);
890 : }
891 :
892 : SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
893 : {
894 : int pkey;
895 : int ret;
896 :
897 : /* No flags supported yet. */
898 : if (flags)
899 : return -EINVAL;
900 : /* check for unsupported init values */
901 : if (init_val & ~PKEY_ACCESS_MASK)
902 : return -EINVAL;
903 :
904 : mmap_write_lock(current->mm);
905 : pkey = mm_pkey_alloc(current->mm);
906 :
907 : ret = -ENOSPC;
908 : if (pkey == -1)
909 : goto out;
910 :
911 : ret = arch_set_user_pkey_access(current, pkey, init_val);
912 : if (ret) {
913 : mm_pkey_free(current->mm, pkey);
914 : goto out;
915 : }
916 : ret = pkey;
917 : out:
918 : mmap_write_unlock(current->mm);
919 : return ret;
920 : }
921 :
922 : SYSCALL_DEFINE1(pkey_free, int, pkey)
923 : {
924 : int ret;
925 :
926 : mmap_write_lock(current->mm);
927 : ret = mm_pkey_free(current->mm, pkey);
928 : mmap_write_unlock(current->mm);
929 :
930 : /*
931 : * We could provide warnings or errors if any VMA still
932 : * has the pkey set here.
933 : */
934 : return ret;
935 : }
936 :
937 : #endif /* CONFIG_ARCH_HAS_PKEYS */
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