Merge tag 'trace-v5.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...
[platform/kernel/linux-starfive.git] / mm / mprotect.c
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 <asm/pgtable.h>
32 #include <asm/cacheflush.h>
33 #include <asm/mmu_context.h>
34 #include <asm/tlbflush.h>
35
36 #include "internal.h"
37
38 static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
39                 unsigned long addr, unsigned long end, pgprot_t newprot,
40                 int dirty_accountable, int prot_numa)
41 {
42         pte_t *pte, oldpte;
43         spinlock_t *ptl;
44         unsigned long pages = 0;
45         int target_node = NUMA_NO_NODE;
46
47         /*
48          * Can be called with only the mmap_sem for reading by
49          * prot_numa so we must check the pmd isn't constantly
50          * changing from under us from pmd_none to pmd_trans_huge
51          * and/or the other way around.
52          */
53         if (pmd_trans_unstable(pmd))
54                 return 0;
55
56         /*
57          * The pmd points to a regular pte so the pmd can't change
58          * from under us even if the mmap_sem is only hold for
59          * reading.
60          */
61         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
62
63         /* Get target node for single threaded private VMAs */
64         if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
65             atomic_read(&vma->vm_mm->mm_users) == 1)
66                 target_node = numa_node_id();
67
68         flush_tlb_batched_pending(vma->vm_mm);
69         arch_enter_lazy_mmu_mode();
70         do {
71                 oldpte = *pte;
72                 if (pte_present(oldpte)) {
73                         pte_t ptent;
74                         bool preserve_write = prot_numa && pte_write(oldpte);
75
76                         /*
77                          * Avoid trapping faults against the zero or KSM
78                          * pages. See similar comment in change_huge_pmd.
79                          */
80                         if (prot_numa) {
81                                 struct page *page;
82
83                                 /* Avoid TLB flush if possible */
84                                 if (pte_protnone(oldpte))
85                                         continue;
86
87                                 page = vm_normal_page(vma, addr, oldpte);
88                                 if (!page || PageKsm(page))
89                                         continue;
90
91                                 /* Also skip shared copy-on-write pages */
92                                 if (is_cow_mapping(vma->vm_flags) &&
93                                     page_mapcount(page) != 1)
94                                         continue;
95
96                                 /*
97                                  * While migration can move some dirty pages,
98                                  * it cannot move them all from MIGRATE_ASYNC
99                                  * context.
100                                  */
101                                 if (page_is_file_cache(page) && PageDirty(page))
102                                         continue;
103
104                                 /*
105                                  * Don't mess with PTEs if page is already on the node
106                                  * a single-threaded process is running on.
107                                  */
108                                 if (target_node == page_to_nid(page))
109                                         continue;
110                         }
111
112                         oldpte = ptep_modify_prot_start(vma, addr, pte);
113                         ptent = pte_modify(oldpte, newprot);
114                         if (preserve_write)
115                                 ptent = pte_mk_savedwrite(ptent);
116
117                         /* Avoid taking write faults for known dirty pages */
118                         if (dirty_accountable && pte_dirty(ptent) &&
119                                         (pte_soft_dirty(ptent) ||
120                                          !(vma->vm_flags & VM_SOFTDIRTY))) {
121                                 ptent = pte_mkwrite(ptent);
122                         }
123                         ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
124                         pages++;
125                 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
126                         swp_entry_t entry = pte_to_swp_entry(oldpte);
127
128                         if (is_write_migration_entry(entry)) {
129                                 pte_t newpte;
130                                 /*
131                                  * A protection check is difficult so
132                                  * just be safe and disable write
133                                  */
134                                 make_migration_entry_read(&entry);
135                                 newpte = swp_entry_to_pte(entry);
136                                 if (pte_swp_soft_dirty(oldpte))
137                                         newpte = pte_swp_mksoft_dirty(newpte);
138                                 set_pte_at(vma->vm_mm, addr, pte, newpte);
139
140                                 pages++;
141                         }
142
143                         if (is_write_device_private_entry(entry)) {
144                                 pte_t newpte;
145
146                                 /*
147                                  * We do not preserve soft-dirtiness. See
148                                  * copy_one_pte() for explanation.
149                                  */
150                                 make_device_private_entry_read(&entry);
151                                 newpte = swp_entry_to_pte(entry);
152                                 set_pte_at(vma->vm_mm, addr, pte, newpte);
153
154                                 pages++;
155                         }
156                 }
157         } while (pte++, addr += PAGE_SIZE, addr != end);
158         arch_leave_lazy_mmu_mode();
159         pte_unmap_unlock(pte - 1, ptl);
160
161         return pages;
162 }
163
164 static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
165                 pud_t *pud, unsigned long addr, unsigned long end,
166                 pgprot_t newprot, int dirty_accountable, int prot_numa)
167 {
168         pmd_t *pmd;
169         unsigned long next;
170         unsigned long pages = 0;
171         unsigned long nr_huge_updates = 0;
172         struct mmu_notifier_range range;
173
174         range.start = 0;
175
176         pmd = pmd_offset(pud, addr);
177         do {
178                 unsigned long this_pages;
179
180                 next = pmd_addr_end(addr, end);
181                 if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
182                                 && pmd_none_or_clear_bad(pmd))
183                         goto next;
184
185                 /* invoke the mmu notifier if the pmd is populated */
186                 if (!range.start) {
187                         mmu_notifier_range_init(&range,
188                                 MMU_NOTIFY_PROTECTION_VMA, 0,
189                                 vma, vma->vm_mm, addr, end);
190                         mmu_notifier_invalidate_range_start(&range);
191                 }
192
193                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
194                         if (next - addr != HPAGE_PMD_SIZE) {
195                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
196                         } else {
197                                 int nr_ptes = change_huge_pmd(vma, pmd, addr,
198                                                 newprot, prot_numa);
199
200                                 if (nr_ptes) {
201                                         if (nr_ptes == HPAGE_PMD_NR) {
202                                                 pages += HPAGE_PMD_NR;
203                                                 nr_huge_updates++;
204                                         }
205
206                                         /* huge pmd was handled */
207                                         goto next;
208                                 }
209                         }
210                         /* fall through, the trans huge pmd just split */
211                 }
212                 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
213                                  dirty_accountable, prot_numa);
214                 pages += this_pages;
215 next:
216                 cond_resched();
217         } while (pmd++, addr = next, addr != end);
218
219         if (range.start)
220                 mmu_notifier_invalidate_range_end(&range);
221
222         if (nr_huge_updates)
223                 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
224         return pages;
225 }
226
227 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
228                 p4d_t *p4d, unsigned long addr, unsigned long end,
229                 pgprot_t newprot, int dirty_accountable, int prot_numa)
230 {
231         pud_t *pud;
232         unsigned long next;
233         unsigned long pages = 0;
234
235         pud = pud_offset(p4d, addr);
236         do {
237                 next = pud_addr_end(addr, end);
238                 if (pud_none_or_clear_bad(pud))
239                         continue;
240                 pages += change_pmd_range(vma, pud, addr, next, newprot,
241                                  dirty_accountable, prot_numa);
242         } while (pud++, addr = next, addr != end);
243
244         return pages;
245 }
246
247 static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
248                 pgd_t *pgd, unsigned long addr, unsigned long end,
249                 pgprot_t newprot, int dirty_accountable, int prot_numa)
250 {
251         p4d_t *p4d;
252         unsigned long next;
253         unsigned long pages = 0;
254
255         p4d = p4d_offset(pgd, addr);
256         do {
257                 next = p4d_addr_end(addr, end);
258                 if (p4d_none_or_clear_bad(p4d))
259                         continue;
260                 pages += change_pud_range(vma, p4d, addr, next, newprot,
261                                  dirty_accountable, prot_numa);
262         } while (p4d++, addr = next, addr != end);
263
264         return pages;
265 }
266
267 static unsigned long change_protection_range(struct vm_area_struct *vma,
268                 unsigned long addr, unsigned long end, pgprot_t newprot,
269                 int dirty_accountable, int prot_numa)
270 {
271         struct mm_struct *mm = vma->vm_mm;
272         pgd_t *pgd;
273         unsigned long next;
274         unsigned long start = addr;
275         unsigned long pages = 0;
276
277         BUG_ON(addr >= end);
278         pgd = pgd_offset(mm, addr);
279         flush_cache_range(vma, addr, end);
280         inc_tlb_flush_pending(mm);
281         do {
282                 next = pgd_addr_end(addr, end);
283                 if (pgd_none_or_clear_bad(pgd))
284                         continue;
285                 pages += change_p4d_range(vma, pgd, addr, next, newprot,
286                                  dirty_accountable, prot_numa);
287         } while (pgd++, addr = next, addr != end);
288
289         /* Only flush the TLB if we actually modified any entries: */
290         if (pages)
291                 flush_tlb_range(vma, start, end);
292         dec_tlb_flush_pending(mm);
293
294         return pages;
295 }
296
297 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
298                        unsigned long end, pgprot_t newprot,
299                        int dirty_accountable, int prot_numa)
300 {
301         unsigned long pages;
302
303         if (is_vm_hugetlb_page(vma))
304                 pages = hugetlb_change_protection(vma, start, end, newprot);
305         else
306                 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
307
308         return pages;
309 }
310
311 static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
312                                unsigned long next, struct mm_walk *walk)
313 {
314         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
315                 0 : -EACCES;
316 }
317
318 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
319                                    unsigned long addr, unsigned long next,
320                                    struct mm_walk *walk)
321 {
322         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
323                 0 : -EACCES;
324 }
325
326 static int prot_none_test(unsigned long addr, unsigned long next,
327                           struct mm_walk *walk)
328 {
329         return 0;
330 }
331
332 static const struct mm_walk_ops prot_none_walk_ops = {
333         .pte_entry              = prot_none_pte_entry,
334         .hugetlb_entry          = prot_none_hugetlb_entry,
335         .test_walk              = prot_none_test,
336 };
337
338 int
339 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
340         unsigned long start, unsigned long end, unsigned long newflags)
341 {
342         struct mm_struct *mm = vma->vm_mm;
343         unsigned long oldflags = vma->vm_flags;
344         long nrpages = (end - start) >> PAGE_SHIFT;
345         unsigned long charged = 0;
346         pgoff_t pgoff;
347         int error;
348         int dirty_accountable = 0;
349
350         if (newflags == oldflags) {
351                 *pprev = vma;
352                 return 0;
353         }
354
355         /*
356          * Do PROT_NONE PFN permission checks here when we can still
357          * bail out without undoing a lot of state. This is a rather
358          * uncommon case, so doesn't need to be very optimized.
359          */
360         if (arch_has_pfn_modify_check() &&
361             (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
362             (newflags & (VM_READ|VM_WRITE|VM_EXEC)) == 0) {
363                 pgprot_t new_pgprot = vm_get_page_prot(newflags);
364
365                 error = walk_page_range(current->mm, start, end,
366                                 &prot_none_walk_ops, &new_pgprot);
367                 if (error)
368                         return error;
369         }
370
371         /*
372          * If we make a private mapping writable we increase our commit;
373          * but (without finer accounting) cannot reduce our commit if we
374          * make it unwritable again. hugetlb mapping were accounted for
375          * even if read-only so there is no need to account for them here
376          */
377         if (newflags & VM_WRITE) {
378                 /* Check space limits when area turns into data. */
379                 if (!may_expand_vm(mm, newflags, nrpages) &&
380                                 may_expand_vm(mm, oldflags, nrpages))
381                         return -ENOMEM;
382                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
383                                                 VM_SHARED|VM_NORESERVE))) {
384                         charged = nrpages;
385                         if (security_vm_enough_memory_mm(mm, charged))
386                                 return -ENOMEM;
387                         newflags |= VM_ACCOUNT;
388                 }
389         }
390
391         /*
392          * First try to merge with previous and/or next vma.
393          */
394         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
395         *pprev = vma_merge(mm, *pprev, start, end, newflags,
396                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
397                            vma->vm_userfaultfd_ctx);
398         if (*pprev) {
399                 vma = *pprev;
400                 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
401                 goto success;
402         }
403
404         *pprev = vma;
405
406         if (start != vma->vm_start) {
407                 error = split_vma(mm, vma, start, 1);
408                 if (error)
409                         goto fail;
410         }
411
412         if (end != vma->vm_end) {
413                 error = split_vma(mm, vma, end, 0);
414                 if (error)
415                         goto fail;
416         }
417
418 success:
419         /*
420          * vm_flags and vm_page_prot are protected by the mmap_sem
421          * held in write mode.
422          */
423         vma->vm_flags = newflags;
424         dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
425         vma_set_page_prot(vma);
426
427         change_protection(vma, start, end, vma->vm_page_prot,
428                           dirty_accountable, 0);
429
430         /*
431          * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
432          * fault on access.
433          */
434         if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
435                         (newflags & VM_WRITE)) {
436                 populate_vma_page_range(vma, start, end, NULL);
437         }
438
439         vm_stat_account(mm, oldflags, -nrpages);
440         vm_stat_account(mm, newflags, nrpages);
441         perf_event_mmap(vma);
442         return 0;
443
444 fail:
445         vm_unacct_memory(charged);
446         return error;
447 }
448
449 /*
450  * pkey==-1 when doing a legacy mprotect()
451  */
452 static int do_mprotect_pkey(unsigned long start, size_t len,
453                 unsigned long prot, int pkey)
454 {
455         unsigned long nstart, end, tmp, reqprot;
456         struct vm_area_struct *vma, *prev;
457         int error = -EINVAL;
458         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
459         const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
460                                 (prot & PROT_READ);
461
462         start = untagged_addr(start);
463
464         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
465         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
466                 return -EINVAL;
467
468         if (start & ~PAGE_MASK)
469                 return -EINVAL;
470         if (!len)
471                 return 0;
472         len = PAGE_ALIGN(len);
473         end = start + len;
474         if (end <= start)
475                 return -ENOMEM;
476         if (!arch_validate_prot(prot, start))
477                 return -EINVAL;
478
479         reqprot = prot;
480
481         if (down_write_killable(&current->mm->mmap_sem))
482                 return -EINTR;
483
484         /*
485          * If userspace did not allocate the pkey, do not let
486          * them use it here.
487          */
488         error = -EINVAL;
489         if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
490                 goto out;
491
492         vma = find_vma(current->mm, start);
493         error = -ENOMEM;
494         if (!vma)
495                 goto out;
496         prev = vma->vm_prev;
497         if (unlikely(grows & PROT_GROWSDOWN)) {
498                 if (vma->vm_start >= end)
499                         goto out;
500                 start = vma->vm_start;
501                 error = -EINVAL;
502                 if (!(vma->vm_flags & VM_GROWSDOWN))
503                         goto out;
504         } else {
505                 if (vma->vm_start > start)
506                         goto out;
507                 if (unlikely(grows & PROT_GROWSUP)) {
508                         end = vma->vm_end;
509                         error = -EINVAL;
510                         if (!(vma->vm_flags & VM_GROWSUP))
511                                 goto out;
512                 }
513         }
514         if (start > vma->vm_start)
515                 prev = vma;
516
517         for (nstart = start ; ; ) {
518                 unsigned long mask_off_old_flags;
519                 unsigned long newflags;
520                 int new_vma_pkey;
521
522                 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
523
524                 /* Does the application expect PROT_READ to imply PROT_EXEC */
525                 if (rier && (vma->vm_flags & VM_MAYEXEC))
526                         prot |= PROT_EXEC;
527
528                 /*
529                  * Each mprotect() call explicitly passes r/w/x permissions.
530                  * If a permission is not passed to mprotect(), it must be
531                  * cleared from the VMA.
532                  */
533                 mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
534                                         VM_FLAGS_CLEAR;
535
536                 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
537                 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
538                 newflags |= (vma->vm_flags & ~mask_off_old_flags);
539
540                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
541                 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
542                         error = -EACCES;
543                         goto out;
544                 }
545
546                 error = security_file_mprotect(vma, reqprot, prot);
547                 if (error)
548                         goto out;
549
550                 tmp = vma->vm_end;
551                 if (tmp > end)
552                         tmp = end;
553                 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
554                 if (error)
555                         goto out;
556                 nstart = tmp;
557
558                 if (nstart < prev->vm_end)
559                         nstart = prev->vm_end;
560                 if (nstart >= end)
561                         goto out;
562
563                 vma = prev->vm_next;
564                 if (!vma || vma->vm_start != nstart) {
565                         error = -ENOMEM;
566                         goto out;
567                 }
568                 prot = reqprot;
569         }
570 out:
571         up_write(&current->mm->mmap_sem);
572         return error;
573 }
574
575 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
576                 unsigned long, prot)
577 {
578         return do_mprotect_pkey(start, len, prot, -1);
579 }
580
581 #ifdef CONFIG_ARCH_HAS_PKEYS
582
583 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
584                 unsigned long, prot, int, pkey)
585 {
586         return do_mprotect_pkey(start, len, prot, pkey);
587 }
588
589 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
590 {
591         int pkey;
592         int ret;
593
594         /* No flags supported yet. */
595         if (flags)
596                 return -EINVAL;
597         /* check for unsupported init values */
598         if (init_val & ~PKEY_ACCESS_MASK)
599                 return -EINVAL;
600
601         down_write(&current->mm->mmap_sem);
602         pkey = mm_pkey_alloc(current->mm);
603
604         ret = -ENOSPC;
605         if (pkey == -1)
606                 goto out;
607
608         ret = arch_set_user_pkey_access(current, pkey, init_val);
609         if (ret) {
610                 mm_pkey_free(current->mm, pkey);
611                 goto out;
612         }
613         ret = pkey;
614 out:
615         up_write(&current->mm->mmap_sem);
616         return ret;
617 }
618
619 SYSCALL_DEFINE1(pkey_free, int, pkey)
620 {
621         int ret;
622
623         down_write(&current->mm->mmap_sem);
624         ret = mm_pkey_free(current->mm, pkey);
625         up_write(&current->mm->mmap_sem);
626
627         /*
628          * We could provie warnings or errors if any VMA still
629          * has the pkey set here.
630          */
631         return ret;
632 }
633
634 #endif /* CONFIG_ARCH_HAS_PKEYS */