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 : if (pte_swp_uffd_wp(oldpte))
227 : newpte = pte_swp_mkuffd_wp(newpte);
228 0 : } else if (is_writable_device_private_entry(entry)) {
229 : /*
230 : * We do not preserve soft-dirtiness. See
231 : * copy_one_pte() for explanation.
232 : */
233 : entry = make_readable_device_private_entry(
234 : swp_offset(entry));
235 : newpte = swp_entry_to_pte(entry);
236 : if (pte_swp_uffd_wp(oldpte))
237 : newpte = pte_swp_mkuffd_wp(newpte);
238 0 : } else if (is_writable_device_exclusive_entry(entry)) {
239 : entry = make_readable_device_exclusive_entry(
240 : swp_offset(entry));
241 : newpte = swp_entry_to_pte(entry);
242 : if (pte_swp_soft_dirty(oldpte))
243 : newpte = pte_swp_mksoft_dirty(newpte);
244 : if (pte_swp_uffd_wp(oldpte))
245 : newpte = pte_swp_mkuffd_wp(newpte);
246 0 : } else if (is_pte_marker_entry(entry)) {
247 : /*
248 : * Ignore swapin errors unconditionally,
249 : * because any access should sigbus anyway.
250 : */
251 0 : if (is_swapin_error_entry(entry))
252 0 : continue;
253 : /*
254 : * If this is uffd-wp pte marker and we'd like
255 : * to unprotect it, drop it; the next page
256 : * fault will trigger without uffd trapping.
257 : */
258 0 : if (uffd_wp_resolve) {
259 0 : pte_clear(vma->vm_mm, addr, pte);
260 0 : pages++;
261 : }
262 0 : continue;
263 : } else {
264 : newpte = oldpte;
265 : }
266 :
267 : if (uffd_wp)
268 : newpte = pte_swp_mkuffd_wp(newpte);
269 : else if (uffd_wp_resolve)
270 : newpte = pte_swp_clear_uffd_wp(newpte);
271 :
272 0 : if (!pte_same(oldpte, newpte)) {
273 0 : set_pte_at(vma->vm_mm, addr, pte, newpte);
274 0 : pages++;
275 : }
276 : } else {
277 : /* It must be an none page, or what else?.. */
278 0 : WARN_ON_ONCE(!pte_none(oldpte));
279 0 : if (unlikely(uffd_wp && !vma_is_anonymous(vma))) {
280 : /*
281 : * For file-backed mem, we need to be able to
282 : * wr-protect a none pte, because even if the
283 : * pte is none, the page/swap cache could
284 : * exist. Doing that by install a marker.
285 : */
286 0 : set_pte_at(vma->vm_mm, addr, pte,
287 : make_pte_marker(PTE_MARKER_UFFD_WP));
288 0 : pages++;
289 : }
290 : }
291 0 : } while (pte++, addr += PAGE_SIZE, addr != end);
292 : arch_leave_lazy_mmu_mode();
293 0 : pte_unmap_unlock(pte - 1, ptl);
294 :
295 : return pages;
296 : }
297 :
298 : /*
299 : * Used when setting automatic NUMA hinting protection where it is
300 : * critical that a numa hinting PMD is not confused with a bad PMD.
301 : */
302 : static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
303 : {
304 0 : pmd_t pmdval = pmdp_get_lockless(pmd);
305 :
306 : /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
307 : #ifdef CONFIG_TRANSPARENT_HUGEPAGE
308 : barrier();
309 : #endif
310 :
311 0 : if (pmd_none(pmdval))
312 : return 1;
313 0 : if (pmd_trans_huge(pmdval))
314 : return 0;
315 0 : if (unlikely(pmd_bad(pmdval))) {
316 0 : pmd_clear_bad(pmd);
317 : return 1;
318 : }
319 :
320 : return 0;
321 : }
322 :
323 : /* Return true if we're uffd wr-protecting file-backed memory, or false */
324 : static inline bool
325 : uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags)
326 : {
327 0 : return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
328 : }
329 :
330 : /*
331 : * If wr-protecting the range for file-backed, populate pgtable for the case
332 : * when pgtable is empty but page cache exists. When {pte|pmd|...}_alloc()
333 : * failed we treat it the same way as pgtable allocation failures during
334 : * page faults by kicking OOM and returning error.
335 : */
336 : #define change_pmd_prepare(vma, pmd, cp_flags) \
337 : ({ \
338 : long err = 0; \
339 : if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
340 : if (pte_alloc(vma->vm_mm, pmd)) \
341 : err = -ENOMEM; \
342 : } \
343 : err; \
344 : })
345 :
346 : /*
347 : * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
348 : * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
349 : * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
350 : */
351 : #define change_prepare(vma, high, low, addr, cp_flags) \
352 : ({ \
353 : long err = 0; \
354 : if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
355 : low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
356 : if (p == NULL) \
357 : err = -ENOMEM; \
358 : } \
359 : err; \
360 : })
361 :
362 0 : static inline long change_pmd_range(struct mmu_gather *tlb,
363 : struct vm_area_struct *vma, pud_t *pud, unsigned long addr,
364 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
365 : {
366 : pmd_t *pmd;
367 : unsigned long next;
368 0 : long pages = 0;
369 0 : unsigned long nr_huge_updates = 0;
370 : struct mmu_notifier_range range;
371 :
372 0 : range.start = 0;
373 :
374 0 : pmd = pmd_offset(pud, addr);
375 : do {
376 : long ret;
377 :
378 0 : next = pmd_addr_end(addr, end);
379 :
380 0 : ret = change_pmd_prepare(vma, pmd, cp_flags);
381 0 : if (ret) {
382 : pages = ret;
383 : break;
384 : }
385 : /*
386 : * Automatic NUMA balancing walks the tables with mmap_lock
387 : * held for read. It's possible a parallel update to occur
388 : * between pmd_trans_huge() and a pmd_none_or_clear_bad()
389 : * check leading to a false positive and clearing.
390 : * Hence, it's necessary to atomically read the PMD value
391 : * for all the checks.
392 : */
393 0 : if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
394 0 : pmd_none_or_clear_bad_unless_trans_huge(pmd))
395 : goto next;
396 :
397 : /* invoke the mmu notifier if the pmd is populated */
398 : if (!range.start) {
399 : mmu_notifier_range_init(&range,
400 : MMU_NOTIFY_PROTECTION_VMA, 0,
401 : vma->vm_mm, addr, end);
402 : mmu_notifier_invalidate_range_start(&range);
403 : }
404 :
405 0 : if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
406 : if ((next - addr != HPAGE_PMD_SIZE) ||
407 : uffd_wp_protect_file(vma, cp_flags)) {
408 : __split_huge_pmd(vma, pmd, addr, false, NULL);
409 : /*
410 : * For file-backed, the pmd could have been
411 : * cleared; make sure pmd populated if
412 : * necessary, then fall-through to pte level.
413 : */
414 : ret = change_pmd_prepare(vma, pmd, cp_flags);
415 : if (ret) {
416 : pages = ret;
417 : break;
418 : }
419 : } else {
420 : /*
421 : * change_huge_pmd() does not defer TLB flushes,
422 : * so no need to propagate the tlb argument.
423 : */
424 : int nr_ptes = change_huge_pmd(tlb, vma, pmd,
425 : addr, newprot, cp_flags);
426 :
427 : if (nr_ptes) {
428 : if (nr_ptes == HPAGE_PMD_NR) {
429 : pages += HPAGE_PMD_NR;
430 : nr_huge_updates++;
431 : }
432 :
433 : /* huge pmd was handled */
434 : goto next;
435 : }
436 : }
437 : /* fall through, the trans huge pmd just split */
438 : }
439 0 : pages += change_pte_range(tlb, vma, pmd, addr, next,
440 : newprot, cp_flags);
441 : next:
442 0 : cond_resched();
443 0 : } while (pmd++, addr = next, addr != end);
444 :
445 : if (range.start)
446 : mmu_notifier_invalidate_range_end(&range);
447 :
448 : if (nr_huge_updates)
449 : count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
450 0 : return pages;
451 : }
452 :
453 0 : static inline long change_pud_range(struct mmu_gather *tlb,
454 : struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr,
455 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
456 : {
457 : pud_t *pud;
458 : unsigned long next;
459 0 : long pages = 0, ret;
460 :
461 0 : pud = pud_offset(p4d, addr);
462 : do {
463 0 : next = pud_addr_end(addr, end);
464 0 : ret = change_prepare(vma, pud, pmd, addr, cp_flags);
465 0 : if (ret)
466 : return ret;
467 0 : if (pud_none_or_clear_bad(pud))
468 0 : continue;
469 0 : pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
470 : cp_flags);
471 0 : } while (pud++, addr = next, addr != end);
472 :
473 0 : return pages;
474 : }
475 :
476 0 : static inline long change_p4d_range(struct mmu_gather *tlb,
477 : struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr,
478 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
479 : {
480 : p4d_t *p4d;
481 : unsigned long next;
482 0 : long pages = 0, ret;
483 :
484 0 : p4d = p4d_offset(pgd, addr);
485 : do {
486 0 : next = p4d_addr_end(addr, end);
487 0 : ret = change_prepare(vma, p4d, pud, addr, cp_flags);
488 0 : if (ret)
489 : return ret;
490 0 : if (p4d_none_or_clear_bad(p4d))
491 : continue;
492 0 : pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
493 : cp_flags);
494 0 : } while (p4d++, addr = next, addr != end);
495 :
496 : return pages;
497 : }
498 :
499 0 : static long change_protection_range(struct mmu_gather *tlb,
500 : struct vm_area_struct *vma, unsigned long addr,
501 : unsigned long end, pgprot_t newprot, unsigned long cp_flags)
502 : {
503 0 : struct mm_struct *mm = vma->vm_mm;
504 : pgd_t *pgd;
505 : unsigned long next;
506 0 : long pages = 0, ret;
507 :
508 0 : BUG_ON(addr >= end);
509 0 : pgd = pgd_offset(mm, addr);
510 : tlb_start_vma(tlb, vma);
511 : do {
512 0 : next = pgd_addr_end(addr, end);
513 0 : ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
514 0 : if (ret) {
515 : pages = ret;
516 : break;
517 : }
518 0 : if (pgd_none_or_clear_bad(pgd))
519 : continue;
520 0 : pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
521 : cp_flags);
522 0 : } while (pgd++, addr = next, addr != end);
523 :
524 0 : tlb_end_vma(tlb, vma);
525 :
526 0 : return pages;
527 : }
528 :
529 0 : long change_protection(struct mmu_gather *tlb,
530 : struct vm_area_struct *vma, unsigned long start,
531 : unsigned long end, unsigned long cp_flags)
532 : {
533 0 : pgprot_t newprot = vma->vm_page_prot;
534 : long pages;
535 :
536 0 : BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
537 :
538 : #ifdef CONFIG_NUMA_BALANCING
539 : /*
540 : * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
541 : * are expected to reflect their requirements via VMA flags such that
542 : * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
543 : */
544 : if (cp_flags & MM_CP_PROT_NUMA)
545 : newprot = PAGE_NONE;
546 : #else
547 0 : WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
548 : #endif
549 :
550 0 : if (is_vm_hugetlb_page(vma))
551 : pages = hugetlb_change_protection(vma, start, end, newprot,
552 : cp_flags);
553 : else
554 0 : pages = change_protection_range(tlb, vma, start, end, newprot,
555 : cp_flags);
556 :
557 0 : return pages;
558 : }
559 :
560 : static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
561 : unsigned long next, struct mm_walk *walk)
562 : {
563 : return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
564 : 0 : -EACCES;
565 : }
566 :
567 : static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
568 : unsigned long addr, unsigned long next,
569 : struct mm_walk *walk)
570 : {
571 : return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
572 : 0 : -EACCES;
573 : }
574 :
575 : static int prot_none_test(unsigned long addr, unsigned long next,
576 : struct mm_walk *walk)
577 : {
578 : return 0;
579 : }
580 :
581 : static const struct mm_walk_ops prot_none_walk_ops = {
582 : .pte_entry = prot_none_pte_entry,
583 : .hugetlb_entry = prot_none_hugetlb_entry,
584 : .test_walk = prot_none_test,
585 : };
586 :
587 : int
588 0 : mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
589 : struct vm_area_struct *vma, struct vm_area_struct **pprev,
590 : unsigned long start, unsigned long end, unsigned long newflags)
591 : {
592 0 : struct mm_struct *mm = vma->vm_mm;
593 0 : unsigned long oldflags = vma->vm_flags;
594 0 : long nrpages = (end - start) >> PAGE_SHIFT;
595 0 : unsigned int mm_cp_flags = 0;
596 0 : unsigned long charged = 0;
597 : pgoff_t pgoff;
598 : int error;
599 :
600 0 : if (newflags == oldflags) {
601 0 : *pprev = vma;
602 0 : return 0;
603 : }
604 :
605 : /*
606 : * Do PROT_NONE PFN permission checks here when we can still
607 : * bail out without undoing a lot of state. This is a rather
608 : * uncommon case, so doesn't need to be very optimized.
609 : */
610 : if (arch_has_pfn_modify_check() &&
611 : (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
612 : (newflags & VM_ACCESS_FLAGS) == 0) {
613 : pgprot_t new_pgprot = vm_get_page_prot(newflags);
614 :
615 : error = walk_page_range(current->mm, start, end,
616 : &prot_none_walk_ops, &new_pgprot);
617 : if (error)
618 : return error;
619 : }
620 :
621 : /*
622 : * If we make a private mapping writable we increase our commit;
623 : * but (without finer accounting) cannot reduce our commit if we
624 : * make it unwritable again. hugetlb mapping were accounted for
625 : * even if read-only so there is no need to account for them here
626 : */
627 0 : if (newflags & VM_WRITE) {
628 : /* Check space limits when area turns into data. */
629 0 : if (!may_expand_vm(mm, newflags, nrpages) &&
630 0 : may_expand_vm(mm, oldflags, nrpages))
631 : return -ENOMEM;
632 0 : if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
633 : VM_SHARED|VM_NORESERVE))) {
634 0 : charged = nrpages;
635 0 : if (security_vm_enough_memory_mm(mm, charged))
636 : return -ENOMEM;
637 0 : newflags |= VM_ACCOUNT;
638 : }
639 : }
640 :
641 : /*
642 : * First try to merge with previous and/or next vma.
643 : */
644 0 : pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
645 0 : *pprev = vma_merge(vmi, mm, *pprev, start, end, newflags,
646 : vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
647 : vma->vm_userfaultfd_ctx, anon_vma_name(vma));
648 0 : if (*pprev) {
649 : vma = *pprev;
650 : VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
651 : goto success;
652 : }
653 :
654 0 : *pprev = vma;
655 :
656 0 : if (start != vma->vm_start) {
657 0 : error = split_vma(vmi, vma, start, 1);
658 0 : if (error)
659 : goto fail;
660 : }
661 :
662 0 : if (end != vma->vm_end) {
663 0 : error = split_vma(vmi, vma, end, 0);
664 0 : if (error)
665 : goto fail;
666 : }
667 :
668 : success:
669 : /*
670 : * vm_flags and vm_page_prot are protected by the mmap_lock
671 : * held in write mode.
672 : */
673 0 : vm_flags_reset(vma, newflags);
674 0 : if (vma_wants_manual_pte_write_upgrade(vma))
675 0 : mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
676 0 : vma_set_page_prot(vma);
677 :
678 0 : change_protection(tlb, vma, start, end, mm_cp_flags);
679 :
680 : /*
681 : * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
682 : * fault on access.
683 : */
684 0 : if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
685 0 : (newflags & VM_WRITE)) {
686 0 : populate_vma_page_range(vma, start, end, NULL);
687 : }
688 :
689 0 : vm_stat_account(mm, oldflags, -nrpages);
690 0 : vm_stat_account(mm, newflags, nrpages);
691 0 : perf_event_mmap(vma);
692 0 : return 0;
693 :
694 : fail:
695 0 : vm_unacct_memory(charged);
696 0 : return error;
697 : }
698 :
699 : /*
700 : * pkey==-1 when doing a legacy mprotect()
701 : */
702 0 : static int do_mprotect_pkey(unsigned long start, size_t len,
703 : unsigned long prot, int pkey)
704 : {
705 : unsigned long nstart, end, tmp, reqprot;
706 : struct vm_area_struct *vma, *prev;
707 : int error;
708 0 : const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
709 0 : const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
710 0 : (prot & PROT_READ);
711 : struct mmu_gather tlb;
712 : struct vma_iterator vmi;
713 :
714 0 : start = untagged_addr(start);
715 :
716 0 : prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
717 0 : if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
718 : return -EINVAL;
719 :
720 0 : if (start & ~PAGE_MASK)
721 : return -EINVAL;
722 0 : if (!len)
723 : return 0;
724 0 : len = PAGE_ALIGN(len);
725 0 : end = start + len;
726 0 : if (end <= start)
727 : return -ENOMEM;
728 0 : if (!arch_validate_prot(prot, start))
729 : return -EINVAL;
730 :
731 0 : reqprot = prot;
732 :
733 0 : if (mmap_write_lock_killable(current->mm))
734 : return -EINTR;
735 :
736 : /*
737 : * If userspace did not allocate the pkey, do not let
738 : * them use it here.
739 : */
740 0 : error = -EINVAL;
741 0 : if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
742 : goto out;
743 :
744 0 : vma_iter_init(&vmi, current->mm, start);
745 0 : vma = vma_find(&vmi, end);
746 0 : error = -ENOMEM;
747 0 : if (!vma)
748 : goto out;
749 :
750 0 : if (unlikely(grows & PROT_GROWSDOWN)) {
751 0 : if (vma->vm_start >= end)
752 : goto out;
753 0 : start = vma->vm_start;
754 0 : error = -EINVAL;
755 0 : if (!(vma->vm_flags & VM_GROWSDOWN))
756 : goto out;
757 : } else {
758 0 : if (vma->vm_start > start)
759 : goto out;
760 0 : if (unlikely(grows & PROT_GROWSUP)) {
761 : end = vma->vm_end;
762 : error = -EINVAL;
763 : if (!(vma->vm_flags & VM_GROWSUP))
764 : goto out;
765 : }
766 : }
767 :
768 0 : prev = vma_prev(&vmi);
769 0 : if (start > vma->vm_start)
770 0 : prev = vma;
771 :
772 0 : tlb_gather_mmu(&tlb, current->mm);
773 0 : nstart = start;
774 0 : tmp = vma->vm_start;
775 0 : for_each_vma_range(vmi, vma, end) {
776 : unsigned long mask_off_old_flags;
777 : unsigned long newflags;
778 : int new_vma_pkey;
779 :
780 0 : if (vma->vm_start != tmp) {
781 : error = -ENOMEM;
782 : break;
783 : }
784 :
785 : /* Does the application expect PROT_READ to imply PROT_EXEC */
786 0 : if (rier && (vma->vm_flags & VM_MAYEXEC))
787 0 : prot |= PROT_EXEC;
788 :
789 : /*
790 : * Each mprotect() call explicitly passes r/w/x permissions.
791 : * If a permission is not passed to mprotect(), it must be
792 : * cleared from the VMA.
793 : */
794 0 : mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR;
795 :
796 0 : new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
797 0 : newflags = calc_vm_prot_bits(prot, new_vma_pkey);
798 0 : newflags |= (vma->vm_flags & ~mask_off_old_flags);
799 :
800 : /* newflags >> 4 shift VM_MAY% in place of VM_% */
801 0 : if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
802 : error = -EACCES;
803 : break;
804 : }
805 :
806 0 : if (map_deny_write_exec(vma, newflags)) {
807 : error = -EACCES;
808 : goto out;
809 : }
810 :
811 : /* Allow architectures to sanity-check the new flags */
812 0 : if (!arch_validate_flags(newflags)) {
813 : error = -EINVAL;
814 : break;
815 : }
816 :
817 0 : error = security_file_mprotect(vma, reqprot, prot);
818 : if (error)
819 : break;
820 :
821 0 : tmp = vma->vm_end;
822 0 : if (tmp > end)
823 0 : tmp = end;
824 :
825 0 : if (vma->vm_ops && vma->vm_ops->mprotect) {
826 0 : error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
827 0 : if (error)
828 : break;
829 : }
830 :
831 0 : error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
832 0 : if (error)
833 : break;
834 :
835 0 : tmp = vma_iter_end(&vmi);
836 0 : nstart = tmp;
837 0 : prot = reqprot;
838 : }
839 0 : tlb_finish_mmu(&tlb);
840 :
841 0 : if (vma_iter_end(&vmi) < end)
842 0 : error = -ENOMEM;
843 :
844 : out:
845 0 : mmap_write_unlock(current->mm);
846 0 : return error;
847 : }
848 :
849 0 : SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
850 : unsigned long, prot)
851 : {
852 0 : return do_mprotect_pkey(start, len, prot, -1);
853 : }
854 :
855 : #ifdef CONFIG_ARCH_HAS_PKEYS
856 :
857 : SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
858 : unsigned long, prot, int, pkey)
859 : {
860 : return do_mprotect_pkey(start, len, prot, pkey);
861 : }
862 :
863 : SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
864 : {
865 : int pkey;
866 : int ret;
867 :
868 : /* No flags supported yet. */
869 : if (flags)
870 : return -EINVAL;
871 : /* check for unsupported init values */
872 : if (init_val & ~PKEY_ACCESS_MASK)
873 : return -EINVAL;
874 :
875 : mmap_write_lock(current->mm);
876 : pkey = mm_pkey_alloc(current->mm);
877 :
878 : ret = -ENOSPC;
879 : if (pkey == -1)
880 : goto out;
881 :
882 : ret = arch_set_user_pkey_access(current, pkey, init_val);
883 : if (ret) {
884 : mm_pkey_free(current->mm, pkey);
885 : goto out;
886 : }
887 : ret = pkey;
888 : out:
889 : mmap_write_unlock(current->mm);
890 : return ret;
891 : }
892 :
893 : SYSCALL_DEFINE1(pkey_free, int, pkey)
894 : {
895 : int ret;
896 :
897 : mmap_write_lock(current->mm);
898 : ret = mm_pkey_free(current->mm, pkey);
899 : mmap_write_unlock(current->mm);
900 :
901 : /*
902 : * We could provide warnings or errors if any VMA still
903 : * has the pkey set here.
904 : */
905 : return ret;
906 : }
907 :
908 : #endif /* CONFIG_ARCH_HAS_PKEYS */
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