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_count(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_writable_migration_entry(entry)) {
 147                                 /*
 148                                  * A protection check is difficult so
 149                                  * just be safe and disable write
 150                                  */
 151                                 entry = make_readable_migration_entry(
 152                                                         swp_offset(entry));
 153                                 newpte = swp_entry_to_pte(entry);
 154                                 if (pte_swp_soft_dirty(oldpte))
 155                                         newpte = pte_swp_mksoft_dirty(newpte);
 156                                 if (pte_swp_uffd_wp(oldpte))
 157                                         newpte = pte_swp_mkuffd_wp(newpte);
 158                         } else if (is_writable_device_private_entry(entry)) {
 159                                 /*
 160                                  * We do not preserve soft-dirtiness. See
 161                                  * copy_one_pte() for explanation.
 162                                  */
 163                                 entry = make_readable_device_private_entry(
 164                                                         swp_offset(entry));
 165                                 newpte = swp_entry_to_pte(entry);
 166                                 if (pte_swp_uffd_wp(oldpte))
 167                                         newpte = pte_swp_mkuffd_wp(newpte);
 168                         } else if (is_writable_device_exclusive_entry(entry)) {
 169                                 entry = make_readable_device_exclusive_entry(
 170                                                         swp_offset(entry));
 171                                 newpte = swp_entry_to_pte(entry);
 172                                 if (pte_swp_soft_dirty(oldpte))
 173                                         newpte = pte_swp_mksoft_dirty(newpte);
 174                                 if (pte_swp_uffd_wp(oldpte))
 175                                         newpte = pte_swp_mkuffd_wp(newpte);
 176                         } else {
 177                                 newpte = oldpte;
 178                         }
 179
 180                         if (uffd_wp)
 181                                 newpte = pte_swp_mkuffd_wp(newpte);
 182                         else if (uffd_wp_resolve)
 183                                 newpte = pte_swp_clear_uffd_wp(newpte);
 184
 185                         if (!pte_same(oldpte, newpte)) {
 186                                 set_pte_at(vma->vm_mm, addr, pte, newpte);
 187                                 pages++;
 188                         }
 189                 }
 190         } while (pte++, addr += PAGE_SIZE, addr != end);
 191         arch_leave_lazy_mmu_mode();
 192         pte_unmap_unlock(pte - 1, ptl);
 193
 194         return pages;
 195 }
 196
 197 /*
 198  * Used when setting automatic NUMA hinting protection where it is
 199  * critical that a numa hinting PMD is not confused with a bad PMD.
 200  */
 201 static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
 202 {
 203         pmd_t pmdval = pmd_read_atomic(pmd);
 204
 205         /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
 206 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 207         barrier();
 208 #endif
 209
 210         if (pmd_none(pmdval))
 211                 return 1;
 212         if (pmd_trans_huge(pmdval))
 213                 return 0;
 214         if (unlikely(pmd_bad(pmdval))) {
 215                 pmd_clear_bad(pmd);
 216                 return 1;
 217         }
 218
 219         return 0;
 220 }
 221
 222 static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 223                 pud_t *pud, unsigned long addr, unsigned long end,
 224                 pgprot_t newprot, unsigned long cp_flags)
 225 {
 226         pmd_t *pmd;
 227         unsigned long next;
 228         unsigned long pages = 0;
 229         unsigned long nr_huge_updates = 0;
 230         struct mmu_notifier_range range;
 231
 232         range.start = 0;
 233
 234         pmd = pmd_offset(pud, addr);
 235         do {
 236                 unsigned long this_pages;
 237
 238                 next = pmd_addr_end(addr, end);
 239
 240                 /*
 241                  * Automatic NUMA balancing walks the tables with mmap_lock
 242                  * held for read. It's possible a parallel update to occur
 243                  * between pmd_trans_huge() and a pmd_none_or_clear_bad()
 244                  * check leading to a false positive and clearing.
 245                  * Hence, it's necessary to atomically read the PMD value
 246                  * for all the checks.
 247                  */
 248                 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
 249                      pmd_none_or_clear_bad_unless_trans_huge(pmd))
 250                         goto next;
 251
 252                 /* invoke the mmu notifier if the pmd is populated */
 253                 if (!range.start) {
 254                         mmu_notifier_range_init(&range,
 255                                 MMU_NOTIFY_PROTECTION_VMA, 0,
 256                                 vma, vma->vm_mm, addr, end);
 257                         mmu_notifier_invalidate_range_start(&range);
 258                 }
 259
 260                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
 261                         if (next - addr != HPAGE_PMD_SIZE) {
 262                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
 263                         } else {
 264                                 int nr_ptes = change_huge_pmd(vma, pmd, addr,
 265                                                               newprot, cp_flags);
 266
 267                                 if (nr_ptes) {
 268                                         if (nr_ptes == HPAGE_PMD_NR) {
 269                                                 pages += HPAGE_PMD_NR;
 270                                                 nr_huge_updates++;
 271                                         }
 272
 273                                         /* huge pmd was handled */
 274                                         goto next;
 275                                 }
 276                         }
 277                         /* fall through, the trans huge pmd just split */
 278                 }
 279                 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
 280                                               cp_flags);
 281                 pages += this_pages;
 282 next:
 283                 cond_resched();
 284         } while (pmd++, addr = next, addr != end);
 285
 286         if (range.start)
 287                 mmu_notifier_invalidate_range_end(&range);
 288
 289         if (nr_huge_updates)
 290                 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
 291         return pages;
 292 }
 293
 294 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
 295                 p4d_t *p4d, unsigned long addr, unsigned long end,
 296                 pgprot_t newprot, unsigned long cp_flags)
 297 {
 298         pud_t *pud;
 299         unsigned long next;
 300         unsigned long pages = 0;
 301
 302         pud = pud_offset(p4d, addr);
 303         do {
 304                 next = pud_addr_end(addr, end);
 305                 if (pud_none_or_clear_bad(pud))
 306                         continue;
 307                 pages += change_pmd_range(vma, pud, addr, next, newprot,
 308                                           cp_flags);
 309         } while (pud++, addr = next, addr != end);
 310
 311         return pages;
 312 }
 313
 314 static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
 315                 pgd_t *pgd, unsigned long addr, unsigned long end,
 316                 pgprot_t newprot, unsigned long cp_flags)
 317 {
 318         p4d_t *p4d;
 319         unsigned long next;
 320         unsigned long pages = 0;
 321
 322         p4d = p4d_offset(pgd, addr);
 323         do {
 324                 next = p4d_addr_end(addr, end);
 325                 if (p4d_none_or_clear_bad(p4d))
 326                         continue;
 327                 pages += change_pud_range(vma, p4d, addr, next, newprot,
 328                                           cp_flags);
 329         } while (p4d++, addr = next, addr != end);
 330
 331         return pages;
 332 }
 333
 334 static unsigned long change_protection_range(struct vm_area_struct *vma,
 335                 unsigned long addr, unsigned long end, pgprot_t newprot,
 336                 unsigned long cp_flags)
 337 {
 338         struct mm_struct *mm = vma->vm_mm;
 339         pgd_t *pgd;
 340         unsigned long next;
 341         unsigned long start = addr;
 342         unsigned long pages = 0;
 343
 344         BUG_ON(addr >= end);
 345         pgd = pgd_offset(mm, addr);
 346         flush_cache_range(vma, addr, end);
 347         inc_tlb_flush_pending(mm);
 348         do {
 349                 next = pgd_addr_end(addr, end);
 350                 if (pgd_none_or_clear_bad(pgd))
 351                         continue;
 352                 pages += change_p4d_range(vma, pgd, addr, next, newprot,
 353                                           cp_flags);
 354         } while (pgd++, addr = next, addr != end);
 355
 356         /* Only flush the TLB if we actually modified any entries: */
 357         if (pages)
 358                 flush_tlb_range(vma, start, end);
 359         dec_tlb_flush_pending(mm);
 360
 361         return pages;
 362 }
 363
 364 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
 365                        unsigned long end, pgprot_t newprot,
 366                        unsigned long cp_flags)
 367 {
 368         unsigned long pages;
 369
 370         BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
 371
 372         if (is_vm_hugetlb_page(vma))
 373                 pages = hugetlb_change_protection(vma, start, end, newprot);
 374         else
 375                 pages = change_protection_range(vma, start, end, newprot,
 376                                                 cp_flags);
 377
 378         return pages;
 379 }
 380
 381 static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
 382                                unsigned long next, struct mm_walk *walk)
 383 {
 384         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
 385                 0 : -EACCES;
 386 }
 387
 388 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
 389                                    unsigned long addr, unsigned long next,
 390                                    struct mm_walk *walk)
 391 {
 392         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
 393                 0 : -EACCES;
 394 }
 395
 396 static int prot_none_test(unsigned long addr, unsigned long next,
 397                           struct mm_walk *walk)
 398 {
 399         return 0;
 400 }
 401
 402 static const struct mm_walk_ops prot_none_walk_ops = {
 403         .pte_entry              = prot_none_pte_entry,
 404         .hugetlb_entry          = prot_none_hugetlb_entry,
 405         .test_walk              = prot_none_test,
 406 };
 407
 408 int
 409 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 410         unsigned long start, unsigned long end, unsigned long newflags)
 411 {
 412         struct mm_struct *mm = vma->vm_mm;
 413         unsigned long oldflags = vma->vm_flags;
 414         long nrpages = (end - start) >> PAGE_SHIFT;
 415         unsigned long charged = 0;
 416         pgoff_t pgoff;
 417         int error;
 418         int dirty_accountable = 0;
 419
 420         if (newflags == oldflags) {
 421                 *pprev = vma;
 422                 return 0;
 423         }
 424
 425         /*
 426          * Do PROT_NONE PFN permission checks here when we can still
 427          * bail out without undoing a lot of state. This is a rather
 428          * uncommon case, so doesn't need to be very optimized.
 429          */
 430         if (arch_has_pfn_modify_check() &&
 431             (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
 432             (newflags & VM_ACCESS_FLAGS) == 0) {
 433                 pgprot_t new_pgprot = vm_get_page_prot(newflags);
 434
 435                 error = walk_page_range(current->mm, start, end,
 436                                 &prot_none_walk_ops, &new_pgprot);
 437                 if (error)
 438                         return error;
 439         }
 440
 441         /*
 442          * If we make a private mapping writable we increase our commit;
 443          * but (without finer accounting) cannot reduce our commit if we
 444          * make it unwritable again. hugetlb mapping were accounted for
 445          * even if read-only so there is no need to account for them here
 446          */
 447         if (newflags & VM_WRITE) {
 448                 /* Check space limits when area turns into data. */
 449                 if (!may_expand_vm(mm, newflags, nrpages) &&
 450                                 may_expand_vm(mm, oldflags, nrpages))
 451                         return -ENOMEM;
 452                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
 453                                                 VM_SHARED|VM_NORESERVE))) {
 454                         charged = nrpages;
 455                         if (security_vm_enough_memory_mm(mm, charged))
 456                                 return -ENOMEM;
 457                         newflags |= VM_ACCOUNT;
 458                 }
 459         }
 460
 461         /*
 462          * First try to merge with previous and/or next vma.
 463          */
 464         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 465         *pprev = vma_merge(mm, *pprev, start, end, newflags,
 466                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
 467                            vma->vm_userfaultfd_ctx);
 468         if (*pprev) {
 469                 vma = *pprev;
 470                 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
 471                 goto success;
 472         }
 473
 474         *pprev = vma;
 475
 476         if (start != vma->vm_start) {
 477                 error = split_vma(mm, vma, start, 1);
 478                 if (error)
 479                         goto fail;
 480         }
 481
 482         if (end != vma->vm_end) {
 483                 error = split_vma(mm, vma, end, 0);
 484                 if (error)
 485                         goto fail;
 486         }
 487
 488 success:
 489         /*
 490          * vm_flags and vm_page_prot are protected by the mmap_lock
 491          * held in write mode.
 492          */
 493         vma->vm_flags = newflags;
 494         dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
 495         vma_set_page_prot(vma);
 496
 497         change_protection(vma, start, end, vma->vm_page_prot,
 498                           dirty_accountable ? MM_CP_DIRTY_ACCT : 0);
 499
 500         /*
 501          * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
 502          * fault on access.
 503          */
 504         if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
 505                         (newflags & VM_WRITE)) {
 506                 populate_vma_page_range(vma, start, end, NULL);
 507         }
 508
 509         vm_stat_account(mm, oldflags, -nrpages);
 510         vm_stat_account(mm, newflags, nrpages);
 511         perf_event_mmap(vma);
 512         return 0;
 513
 514 fail:
 515         vm_unacct_memory(charged);
 516         return error;
 517 }
 518
 519 /*
 520  * pkey==-1 when doing a legacy mprotect()
 521  */
 522 static int do_mprotect_pkey(unsigned long start, size_t len,
 523                 unsigned long prot, int pkey)
 524 {
 525         unsigned long nstart, end, tmp, reqprot;
 526         struct vm_area_struct *vma, *prev;
 527         int error = -EINVAL;
 528         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
 529         const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
 530                                 (prot & PROT_READ);
 531
 532         start = untagged_addr(start);
 533
 534         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
 535         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
 536                 return -EINVAL;
 537
 538         if (start & ~PAGE_MASK)
 539                 return -EINVAL;
 540         if (!len)
 541                 return 0;
 542         len = PAGE_ALIGN(len);
 543         end = start + len;
 544         if (end <= start)
 545                 return -ENOMEM;
 546         if (!arch_validate_prot(prot, start))
 547                 return -EINVAL;
 548
 549         reqprot = prot;
 550
 551         if (mmap_write_lock_killable(current->mm))
 552                 return -EINTR;
 553
 554         /*
 555          * If userspace did not allocate the pkey, do not let
 556          * them use it here.
 557          */
 558         error = -EINVAL;
 559         if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
 560                 goto out;
 561
 562         vma = find_vma(current->mm, start);
 563         error = -ENOMEM;
 564         if (!vma)
 565                 goto out;
 566         prev = vma->vm_prev;
 567         if (unlikely(grows & PROT_GROWSDOWN)) {
 568                 if (vma->vm_start >= end)
 569                         goto out;
 570                 start = vma->vm_start;
 571                 error = -EINVAL;
 572                 if (!(vma->vm_flags & VM_GROWSDOWN))
 573                         goto out;
 574         } else {
 575                 if (vma->vm_start > start)
 576                         goto out;
 577                 if (unlikely(grows & PROT_GROWSUP)) {
 578                         end = vma->vm_end;
 579                         error = -EINVAL;
 580                         if (!(vma->vm_flags & VM_GROWSUP))
 581                                 goto out;
 582                 }
 583         }
 584         if (start > vma->vm_start)
 585                 prev = vma;
 586
 587         for (nstart = start ; ; ) {
 588                 unsigned long mask_off_old_flags;
 589                 unsigned long newflags;
 590                 int new_vma_pkey;
 591
 592                 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
 593
 594                 /* Does the application expect PROT_READ to imply PROT_EXEC */
 595                 if (rier && (vma->vm_flags & VM_MAYEXEC))
 596                         prot |= PROT_EXEC;
 597
 598                 /*
 599                  * Each mprotect() call explicitly passes r/w/x permissions.
 600                  * If a permission is not passed to mprotect(), it must be
 601                  * cleared from the VMA.
 602                  */
 603                 mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
 604                                         VM_FLAGS_CLEAR;
 605
 606                 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
 607                 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
 608                 newflags |= (vma->vm_flags & ~mask_off_old_flags);
 609
 610                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
 611                 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
 612                         error = -EACCES;
 613                         goto out;
 614                 }
 615
 616                 /* Allow architectures to sanity-check the new flags */
 617                 if (!arch_validate_flags(newflags)) {
 618                         error = -EINVAL;
 619                         goto out;
 620                 }
 621
 622                 error = security_file_mprotect(vma, reqprot, prot);
 623                 if (error)
 624                         goto out;
 625
 626                 tmp = vma->vm_end;
 627                 if (tmp > end)
 628                         tmp = end;
 629
 630                 if (vma->vm_ops && vma->vm_ops->mprotect) {
 631                         error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
 632                         if (error)
 633                                 goto out;
 634                 }
 635
 636                 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
 637                 if (error)
 638                         goto out;
 639
 640                 nstart = tmp;
 641
 642                 if (nstart < prev->vm_end)
 643                         nstart = prev->vm_end;
 644                 if (nstart >= end)
 645                         goto out;
 646
 647                 vma = prev->vm_next;
 648                 if (!vma || vma->vm_start != nstart) {
 649                         error = -ENOMEM;
 650                         goto out;
 651                 }
 652                 prot = reqprot;
 653         }
 654 out:
 655         mmap_write_unlock(current->mm);
 656         return error;
 657 }
 658
 659 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
 660                 unsigned long, prot)
 661 {
 662         return do_mprotect_pkey(start, len, prot, -1);
 663 }
 664
 665 #ifdef CONFIG_ARCH_HAS_PKEYS
 666
 667 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
 668                 unsigned long, prot, int, pkey)
 669 {
 670         return do_mprotect_pkey(start, len, prot, pkey);
 671 }
 672
 673 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
 674 {
 675         int pkey;
 676         int ret;
 677
 678         /* No flags supported yet. */
 679         if (flags)
 680                 return -EINVAL;
 681         /* check for unsupported init values */
 682         if (init_val & ~PKEY_ACCESS_MASK)
 683                 return -EINVAL;
 684
 685         mmap_write_lock(current->mm);
 686         pkey = mm_pkey_alloc(current->mm);
 687
 688         ret = -ENOSPC;
 689         if (pkey == -1)
 690                 goto out;
 691
 692         ret = arch_set_user_pkey_access(current, pkey, init_val);
 693         if (ret) {
 694                 mm_pkey_free(current->mm, pkey);
 695                 goto out;
 696         }
 697         ret = pkey;
 698 out:
 699         mmap_write_unlock(current->mm);
 700         return ret;
 701 }
 702
 703 SYSCALL_DEFINE1(pkey_free, int, pkey)
 704 {
 705         int ret;
 706
 707         mmap_write_lock(current->mm);
 708         ret = mm_pkey_free(current->mm, pkey);
 709         mmap_write_unlock(current->mm);
 710
 711         /*
 712          * We could provide warnings or errors if any VMA still
 713          * has the pkey set here.
 714          */
 715         return ret;
 716 }
 717
 718 #endif /* CONFIG_ARCH_HAS_PKEYS */