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