linux/mm/mprotect.c
<<
>>
Prefs
   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
  38static 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 */
 191static 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
 212static 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;
 272next:
 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
 284static 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
 304static 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
 324static 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
 354unsigned 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
 371static 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
 378static 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
 386static int prot_none_test(unsigned long addr, unsigned long next,
 387                          struct mm_walk *walk)
 388{
 389        return 0;
 390}
 391
 392static 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
 398int
 399mprotect_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
 478success:
 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
 504fail:
 505        vm_unacct_memory(charged);
 506        return error;
 507}
 508
 509/*
 510 * pkey==-1 when doing a legacy mprotect()
 511 */
 512static 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        }
 644out:
 645        mmap_write_unlock(current->mm);
 646        return error;
 647}
 648
 649SYSCALL_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
 657SYSCALL_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
 663SYSCALL_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;
 688out:
 689        mmap_write_unlock(current->mm);
 690        return ret;
 691}
 692
 693SYSCALL_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 */
 709