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 <linux/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                 unsigned long cp_flags)
  41 {
  42         pte_t *pte, oldpte;
  43         spinlock_t *ptl;
  44         unsigned long pages = 0;
  45         int target_node = NUMA_NO_NODE;
  46         bool dirty_accountable = cp_flags & MM_CP_DIRTY_ACCT;
  47         bool prot_numa = cp_flags & MM_CP_PROT_NUMA;
  48         bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
  49         bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
  50
  51         /*
  52          * Can be called with only the mmap_lock for reading by
  53          * prot_numa so we must check the pmd isn't constantly
  54          * changing from under us from pmd_none to pmd_trans_huge
  55          * and/or the other way around.
  56          */
  57         if (pmd_trans_unstable(pmd))
  58                 return 0;
  59
  60         /*
  61          * The pmd points to a regular pte so the pmd can't change
  62          * from under us even if the mmap_lock is only hold for
  63          * reading.
  64          */
  65         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
  66
  67         /* Get target node for single threaded private VMAs */
  68         if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
  69             atomic_read(&vma->vm_mm->mm_users) == 1)
  70                 target_node = numa_node_id();
  71
  72         flush_tlb_batched_pending(vma->vm_mm);
  73         arch_enter_lazy_mmu_mode();
  74         do {
  75                 oldpte = *pte;
  76                 if (pte_present(oldpte)) {
  77                         pte_t ptent;
  78                         bool preserve_write = prot_numa && pte_write(oldpte);
  79
  80                         /*
  81                          * Avoid trapping faults against the zero or KSM
  82                          * pages. See similar comment in change_huge_pmd.
  83                          */
  84                         if (prot_numa) {
  85                                 struct page *page;
  86
  87                                 /* Avoid TLB flush if possible */
  88                                 if (pte_protnone(oldpte))
  89                                         continue;
  90
  91                                 page = vm_normal_page(vma, addr, oldpte);
  92                                 if (!page || PageKsm(page))
  93                                         continue;
  94
  95                                 /* Also skip shared copy-on-write pages */
  96                                 if (is_cow_mapping(vma->vm_flags) &&
  97                                     page_mapcount(page) != 1)
  98                                         continue;
  99
 100                                 /*
 101                                  * While migration can move some dirty pages,
 102                                  * it cannot move them all from MIGRATE_ASYNC
 103                                  * context.
 104                                  */
 105                                 if (page_is_file_lru(page) && PageDirty(page))
 106                                         continue;
 107
 108                                 /*
 109                                  * Don't mess with PTEs if page is already on the node
 110                                  * a single-threaded process is running on.
 111                                  */
 112                                 if (target_node == page_to_nid(page))
 113                                         continue;
 114                         }
 115
 116                         oldpte = ptep_modify_prot_start(vma, addr, pte);
 117                         ptent = pte_modify(oldpte, newprot);
 118                         if (preserve_write)
 119                                 ptent = pte_mk_savedwrite(ptent);
 120
 121                         if (uffd_wp) {
 122                                 ptent = pte_wrprotect(ptent);
 123                                 ptent = pte_mkuffd_wp(ptent);
 124                         } else if (uffd_wp_resolve) {
 125                                 /*
 126                                  * Leave the write bit to be handled
 127                                  * by PF interrupt handler, then
 128                                  * things like COW could be properly
 129                                  * handled.
 130                                  */
 131                                 ptent = pte_clear_uffd_wp(ptent);
 132                         }
 133
 134                         /* Avoid taking write faults for known dirty pages */
 135                         if (dirty_accountable && pte_dirty(ptent) &&
 136                                         (pte_soft_dirty(ptent) ||
 137                                          !(vma->vm_flags & VM_SOFTDIRTY))) {
 138                                 ptent = pte_mkwrite(ptent);
 139                         }
 140                         ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
 141                         pages++;
 142                 } else if (is_swap_pte(oldpte)) {
 143                         swp_entry_t entry = pte_to_swp_entry(oldpte);
 144                         pte_t newpte;
 145
 146                         if (is_write_migration_entry(entry)) {
 147                                 /*
 148                                  * A protection check is difficult so
 149                                  * just be safe and disable write
 150                                  */
 151                                 make_migration_entry_read(&entry);
 152                                 newpte = swp_entry_to_pte(entry);
 153                                 if (pte_swp_soft_dirty(oldpte))
 154                                         newpte = pte_swp_mksoft_dirty(newpte);
 155                                 if (pte_swp_uffd_wp(oldpte))
 156                                         newpte = pte_swp_mkuffd_wp(newpte);
 157                         } else if (is_write_device_private_entry(entry)) {
 158                                 /*
 159                                  * We do not preserve soft-dirtiness. See
 160                                  * copy_one_pte() for explanation.
 161                                  */
 162                                 make_device_private_entry_read(&entry);
 163                                 newpte = swp_entry_to_pte(entry);
 164                                 if (pte_swp_uffd_wp(oldpte))
 165                                         newpte = pte_swp_mkuffd_wp(newpte);
 166                         } else {
 167                                 newpte = oldpte;
 168                         }
 169
 170                         if (uffd_wp)
 171                                 newpte = pte_swp_mkuffd_wp(newpte);
 172                         else if (uffd_wp_resolve)
 173                                 newpte = pte_swp_clear_uffd_wp(newpte);
 174
 175                         if (!pte_same(oldpte, newpte)) {
 176                                 set_pte_at(vma->vm_mm, addr, pte, newpte);
 177                                 pages++;
 178                         }
 179                 }
 180         } while (pte++, addr += PAGE_SIZE, addr != end);
 181         arch_leave_lazy_mmu_mode();
 182         pte_unmap_unlock(pte - 1, ptl);
 183
 184         return pages;
 185 }
 186
 187 /*
 188  * Used when setting automatic NUMA hinting protection where it is
 189  * critical that a numa hinting PMD is not confused with a bad PMD.
 190  */
 191 static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
 192 {
 193         pmd_t pmdval = pmd_read_atomic(pmd);
 194
 195         /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
 196 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 197         barrier();
 198 #endif
 199
 200         if (pmd_none(pmdval))
 201                 return 1;
 202         if (pmd_trans_huge(pmdval))
 203                 return 0;
 204         if (unlikely(pmd_bad(pmdval))) {
 205                 pmd_clear_bad(pmd);
 206                 return 1;
 207         }
 208
 209         return 0;
 210 }
 211
 212 static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 213                 pud_t *pud, unsigned long addr, unsigned long end,
 214                 pgprot_t newprot, unsigned long cp_flags)
 215 {
 216         pmd_t *pmd;
 217         unsigned long next;
 218         unsigned long pages = 0;
 219         unsigned long nr_huge_updates = 0;
 220         struct mmu_notifier_range range;
 221
 222         range.start = 0;
 223
 224         pmd = pmd_offset(pud, addr);
 225         do {
 226                 unsigned long this_pages;
 227
 228                 next = pmd_addr_end(addr, end);
 229
 230                 /*
 231                  * Automatic NUMA balancing walks the tables with mmap_lock
 232                  * held for read. It's possible a parallel update to occur
 233                  * between pmd_trans_huge() and a pmd_none_or_clear_bad()
 234                  * check leading to a false positive and clearing.
 235                  * Hence, it's necessary to atomically read the PMD value
 236                  * for all the checks.
 237                  */
 238                 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
 239                      pmd_none_or_clear_bad_unless_trans_huge(pmd))
 240                         goto next;
 241
 242                 /* invoke the mmu notifier if the pmd is populated */
 243                 if (!range.start) {
 244                         mmu_notifier_range_init(&range,
 245                                 MMU_NOTIFY_PROTECTION_VMA, 0,
 246                                 vma, vma->vm_mm, addr, end);
 247                         mmu_notifier_invalidate_range_start(&range);
 248                 }
 249
 250                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
 251                         if (next - addr != HPAGE_PMD_SIZE) {
 252                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
 253                         } else {
 254                                 int nr_ptes = change_huge_pmd(vma, pmd, addr,
 255                                                               newprot, cp_flags);
 256
 257                                 if (nr_ptes) {
 258                                         if (nr_ptes == HPAGE_PMD_NR) {
 259                                                 pages += HPAGE_PMD_NR;
 260                                                 nr_huge_updates++;
 261                                         }
 262
 263                                         /* huge pmd was handled */
 264                                         goto next;
 265                                 }
 266                         }
 267                         /* fall through, the trans huge pmd just split */
 268                 }
 269                 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
 270                                               cp_flags);
 271                 pages += this_pages;
 272 next:
 273                 cond_resched();
 274         } while (pmd++, addr = next, addr != end);
 275
 276         if (range.start)
 277                 mmu_notifier_invalidate_range_end(&range);
 278
 279         if (nr_huge_updates)
 280                 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
 281         return pages;
 282 }
 283
 284 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
 285                 p4d_t *p4d, unsigned long addr, unsigned long end,
 286                 pgprot_t newprot, unsigned long cp_flags)
 287 {
 288         pud_t *pud;
 289         unsigned long next;
 290         unsigned long pages = 0;
 291
 292         pud = pud_offset(p4d, addr);
 293         do {
 294                 next = pud_addr_end(addr, end);
 295                 if (pud_none_or_clear_bad(pud))
 296                         continue;
 297                 pages += change_pmd_range(vma, pud, addr, next, newprot,
 298                                           cp_flags);
 299         } while (pud++, addr = next, addr != end);
 300
 301         return pages;
 302 }
 303
 304 static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
 305                 pgd_t *pgd, unsigned long addr, unsigned long end,
 306                 pgprot_t newprot, unsigned long cp_flags)
 307 {
 308         p4d_t *p4d;
 309         unsigned long next;
 310         unsigned long pages = 0;
 311
 312         p4d = p4d_offset(pgd, addr);
 313         do {
 314                 next = p4d_addr_end(addr, end);
 315                 if (p4d_none_or_clear_bad(p4d))
 316                         continue;
 317                 pages += change_pud_range(vma, p4d, addr, next, newprot,
 318                                           cp_flags);
 319         } while (p4d++, addr = next, addr != end);
 320
 321         return pages;
 322 }
 323
 324 static unsigned long change_protection_range(struct vm_area_struct *vma,
 325                 unsigned long addr, unsigned long end, pgprot_t newprot,
 326                 unsigned long cp_flags)
 327 {
 328         struct mm_struct *mm = vma->vm_mm;
 329         pgd_t *pgd;
 330         unsigned long next;
 331         unsigned long start = addr;
 332         unsigned long pages = 0;
 333
 334         BUG_ON(addr >= end);
 335         pgd = pgd_offset(mm, addr);
 336         flush_cache_range(vma, addr, end);
 337         inc_tlb_flush_pending(mm);
 338         do {
 339                 next = pgd_addr_end(addr, end);
 340                 if (pgd_none_or_clear_bad(pgd))
 341                         continue;
 342                 pages += change_p4d_range(vma, pgd, addr, next, newprot,
 343                                           cp_flags);
 344         } while (pgd++, addr = next, addr != end);
 345
 346         /* Only flush the TLB if we actually modified any entries: */
 347         if (pages)
 348                 flush_tlb_range(vma, start, end);
 349         dec_tlb_flush_pending(mm);
 350
 351         return pages;
 352 }
 353
 354 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
 355                        unsigned long end, pgprot_t newprot,
 356                        unsigned long cp_flags)
 357 {
 358         unsigned long pages;
 359
 360         BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
 361
 362         if (is_vm_hugetlb_page(vma))
 363                 pages = hugetlb_change_protection(vma, start, end, newprot);
 364         else
 365                 pages = change_protection_range(vma, start, end, newprot,
 366                                                 cp_flags);
 367
 368         return pages;
 369 }
 370
 371 static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
 372                                unsigned long next, struct mm_walk *walk)
 373 {
 374         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
 375                 0 : -EACCES;
 376 }
 377
 378 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
 379                                    unsigned long addr, unsigned long next,
 380                                    struct mm_walk *walk)
 381 {
 382         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
 383                 0 : -EACCES;
 384 }
 385
 386 static int prot_none_test(unsigned long addr, unsigned long next,
 387                           struct mm_walk *walk)
 388 {
 389         return 0;
 390 }
 391
 392 static const struct mm_walk_ops prot_none_walk_ops = {
 393         .pte_entry              = prot_none_pte_entry,
 394         .hugetlb_entry          = prot_none_hugetlb_entry,
 395         .test_walk              = prot_none_test,
 396 };
 397
 398 int
 399 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 400         unsigned long start, unsigned long end, unsigned long newflags)
 401 {
 402         struct mm_struct *mm = vma->vm_mm;
 403         unsigned long oldflags = vma->vm_flags;
 404         long nrpages = (end - start) >> PAGE_SHIFT;
 405         unsigned long charged = 0;
 406         pgoff_t pgoff;
 407         int error;
 408         int dirty_accountable = 0;
 409
 410         if (newflags == oldflags) {
 411                 *pprev = vma;
 412                 return 0;
 413         }
 414
 415         /*
 416          * Do PROT_NONE PFN permission checks here when we can still
 417          * bail out without undoing a lot of state. This is a rather
 418          * uncommon case, so doesn't need to be very optimized.
 419          */
 420         if (arch_has_pfn_modify_check() &&
 421             (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
 422             (newflags & VM_ACCESS_FLAGS) == 0) {
 423                 pgprot_t new_pgprot = vm_get_page_prot(newflags);
 424
 425                 error = walk_page_range(current->mm, start, end,
 426                                 &prot_none_walk_ops, &new_pgprot);
 427                 if (error)
 428                         return error;
 429         }
 430
 431         /*
 432          * If we make a private mapping writable we increase our commit;
 433          * but (without finer accounting) cannot reduce our commit if we
 434          * make it unwritable again. hugetlb mapping were accounted for
 435          * even if read-only so there is no need to account for them here
 436          */
 437         if (newflags & VM_WRITE) {
 438                 /* Check space limits when area turns into data. */
 439                 if (!may_expand_vm(mm, newflags, nrpages) &&
 440                                 may_expand_vm(mm, oldflags, nrpages))
 441                         return -ENOMEM;
 442                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
 443                                                 VM_SHARED|VM_NORESERVE))) {
 444                         charged = nrpages;
 445                         if (security_vm_enough_memory_mm(mm, charged))
 446                                 return -ENOMEM;
 447                         newflags |= VM_ACCOUNT;
 448                 }
 449         }
 450
 451         /*
 452          * First try to merge with previous and/or next vma.
 453          */
 454         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 455         *pprev = vma_merge(mm, *pprev, start, end, newflags,
 456                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
 457                            vma->vm_userfaultfd_ctx);
 458         if (*pprev) {
 459                 vma = *pprev;
 460                 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
 461                 goto success;
 462         }
 463
 464         *pprev = vma;
 465
 466         if (start != vma->vm_start) {
 467                 error = split_vma(mm, vma, start, 1);
 468                 if (error)
 469                         goto fail;
 470         }
 471
 472         if (end != vma->vm_end) {
 473                 error = split_vma(mm, vma, end, 0);
 474                 if (error)
 475                         goto fail;
 476         }
 477
 478 success:
 479         /*
 480          * vm_flags and vm_page_prot are protected by the mmap_lock
 481          * held in write mode.
 482          */
 483         vma->vm_flags = newflags;
 484         dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
 485         vma_set_page_prot(vma);
 486
 487         change_protection(vma, start, end, vma->vm_page_prot,
 488                           dirty_accountable ? MM_CP_DIRTY_ACCT : 0);
 489
 490         /*
 491          * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
 492          * fault on access.
 493          */
 494         if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
 495                         (newflags & VM_WRITE)) {
 496                 populate_vma_page_range(vma, start, end, NULL);
 497         }
 498
 499         vm_stat_account(mm, oldflags, -nrpages);
 500         vm_stat_account(mm, newflags, nrpages);
 501         perf_event_mmap(vma);
 502         return 0;
 503
 504 fail:
 505         vm_unacct_memory(charged);
 506         return error;
 507 }
 508
 509 /*
 510  * pkey==-1 when doing a legacy mprotect()
 511  */
 512 static int do_mprotect_pkey(unsigned long start, size_t len,
 513                 unsigned long prot, int pkey)
 514 {
 515         unsigned long nstart, end, tmp, reqprot;
 516         struct vm_area_struct *vma, *prev;
 517         int error = -EINVAL;
 518         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
 519         const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
 520                                 (prot & PROT_READ);
 521
 522         start = untagged_addr(start);
 523
 524         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
 525         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
 526                 return -EINVAL;
 527
 528         if (start & ~PAGE_MASK)
 529                 return -EINVAL;
 530         if (!len)
 531                 return 0;
 532         len = PAGE_ALIGN(len);
 533         end = start + len;
 534         if (end <= start)
 535                 return -ENOMEM;
 536         if (!arch_validate_prot(prot, start))
 537                 return -EINVAL;
 538
 539         reqprot = prot;
 540
 541         if (mmap_write_lock_killable(current->mm))
 542                 return -EINTR;
 543
 544         /*
 545          * If userspace did not allocate the pkey, do not let
 546          * them use it here.
 547          */
 548         error = -EINVAL;
 549         if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
 550                 goto out;
 551
 552         vma = find_vma(current->mm, start);
 553         error = -ENOMEM;
 554         if (!vma)
 555                 goto out;
 556         prev = vma->vm_prev;
 557         if (unlikely(grows & PROT_GROWSDOWN)) {
 558                 if (vma->vm_start >= end)
 559                         goto out;
 560                 start = vma->vm_start;
 561                 error = -EINVAL;
 562                 if (!(vma->vm_flags & VM_GROWSDOWN))
 563                         goto out;
 564         } else {
 565                 if (vma->vm_start > start)
 566                         goto out;
 567                 if (unlikely(grows & PROT_GROWSUP)) {
 568                         end = vma->vm_end;
 569                         error = -EINVAL;
 570                         if (!(vma->vm_flags & VM_GROWSUP))
 571                                 goto out;
 572                 }
 573         }
 574         if (start > vma->vm_start)
 575                 prev = vma;
 576
 577         for (nstart = start ; ; ) {
 578                 unsigned long mask_off_old_flags;
 579                 unsigned long newflags;
 580                 int new_vma_pkey;
 581
 582                 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
 583
 584                 /* Does the application expect PROT_READ to imply PROT_EXEC */
 585                 if (rier && (vma->vm_flags & VM_MAYEXEC))
 586                         prot |= PROT_EXEC;
 587
 588                 /*
 589                  * Each mprotect() call explicitly passes r/w/x permissions.
 590                  * If a permission is not passed to mprotect(), it must be
 591                  * cleared from the VMA.
 592                  */
 593                 mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
 594                                         VM_FLAGS_CLEAR;
 595
 596                 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
 597                 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
 598                 newflags |= (vma->vm_flags & ~mask_off_old_flags);
 599
 600                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
 601                 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
 602                         error = -EACCES;
 603                         goto out;
 604                 }
 605
 606                 /* Allow architectures to sanity-check the new flags */
 607                 if (!arch_validate_flags(newflags)) {
 608                         error = -EINVAL;
 609                         goto out;
 610                 }
 611
 612                 error = security_file_mprotect(vma, reqprot, prot);
 613                 if (error)
 614                         goto out;
 615
 616                 tmp = vma->vm_end;
 617                 if (tmp > end)
 618                         tmp = end;
 619
 620                 if (vma->vm_ops && vma->vm_ops->mprotect) {
 621                         error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
 622                         if (error)
 623                                 goto out;
 624                 }
 625
 626                 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
 627                 if (error)
 628                         goto out;
 629
 630                 nstart = tmp;
 631
 632                 if (nstart < prev->vm_end)
 633                         nstart = prev->vm_end;
 634                 if (nstart >= end)
 635                         goto out;
 636
 637                 vma = prev->vm_next;
 638                 if (!vma || vma->vm_start != nstart) {
 639                         error = -ENOMEM;
 640                         goto out;
 641                 }
 642                 prot = reqprot;
 643         }
 644 out:
 645         mmap_write_unlock(current->mm);
 646         return error;
 647 }
 648
 649 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
 650                 unsigned long, prot)
 651 {
 652         return do_mprotect_pkey(start, len, prot, -1);
 653 }
 654
 655 #ifdef CONFIG_ARCH_HAS_PKEYS
 656
 657 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
 658                 unsigned long, prot, int, pkey)
 659 {
 660         return do_mprotect_pkey(start, len, prot, pkey);
 661 }
 662
 663 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
 664 {
 665         int pkey;
 666         int ret;
 667
 668         /* No flags supported yet. */
 669         if (flags)
 670                 return -EINVAL;
 671         /* check for unsupported init values */
 672         if (init_val & ~PKEY_ACCESS_MASK)
 673                 return -EINVAL;
 674
 675         mmap_write_lock(current->mm);
 676         pkey = mm_pkey_alloc(current->mm);
 677
 678         ret = -ENOSPC;
 679         if (pkey == -1)
 680                 goto out;
 681
 682         ret = arch_set_user_pkey_access(current, pkey, init_val);
 683         if (ret) {
 684                 mm_pkey_free(current->mm, pkey);
 685                 goto out;
 686         }
 687         ret = pkey;
 688 out:
 689         mmap_write_unlock(current->mm);
 690         return ret;
 691 }
 692
 693 SYSCALL_DEFINE1(pkey_free, int, pkey)
 694 {
 695         int ret;
 696
 697         mmap_write_lock(current->mm);
 698         ret = mm_pkey_free(current->mm, pkey);
 699         mmap_write_unlock(current->mm);
 700
 701         /*
 702          * We could provide warnings or errors if any VMA still
 703          * has the pkey set here.
 704          */
 705         return ret;
 706 }
 707
 708 #endif /* CONFIG_ARCH_HAS_PKEYS */