1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * mm/mprotect.c 4 * 5 * (C) Copyright 1994 Linus Torvalds 6 * (C) Copyright 2002 Christoph Hellwig 7 * 8 * Address space accounting code <alan@lxorguk.ukuu.org.uk> 9 * (C) Copyright 2002 Red Hat Inc, All Rights Reserved 10 */ 11 12 #include <linux/pagewalk.h> 13 #include <linux/hugetlb.h> 14 #include <linux/shm.h> 15 #include <linux/mman.h> 16 #include <linux/fs.h> 17 #include <linux/highmem.h> 18 #include <linux/security.h> 19 #include <linux/mempolicy.h> 20 #include <linux/personality.h> 21 #include <linux/syscalls.h> 22 #include <linux/swap.h> 23 #include <linux/swapops.h> 24 #include <linux/mmu_notifier.h> 25 #include <linux/migrate.h> 26 #include <linux/perf_event.h> 27 #include <linux/pkeys.h> 28 #include <linux/ksm.h> 29 #include <linux/uaccess.h> 30 #include <linux/mm_inline.h> 31 #include <linux/pgtable.h> 32 #include <linux/sched/sysctl.h> 33 #include <linux/userfaultfd_k.h> 34 #include <linux/memory-tiers.h> 35 #include <asm/cacheflush.h> 36 #include <asm/mmu_context.h> 37 #include <asm/tlbflush.h> 38 #include <asm/tlb.h> 39 40 #include "internal.h" 41 42 bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, 43 pte_t pte) 44 { 45 struct page *page; 46 47 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 48 return false; 49 50 /* Don't touch entries that are not even readable. */ 51 if (pte_protnone(pte)) 52 return false; 53 54 /* Do we need write faults for softdirty tracking? */ 55 if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte)) 56 return false; 57 58 /* Do we need write faults for uffd-wp tracking? */ 59 if (userfaultfd_pte_wp(vma, pte)) 60 return false; 61 62 if (!(vma->vm_flags & VM_SHARED)) { 63 /* 64 * Writable MAP_PRIVATE mapping: We can only special-case on 65 * exclusive anonymous pages, because we know that our 66 * write-fault handler similarly would map them writable without 67 * any additional checks while holding the PT lock. 68 */ 69 page = vm_normal_page(vma, addr, pte); 70 return page && PageAnon(page) && PageAnonExclusive(page); 71 } 72 73 /* 74 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still 75 * needs a real write-fault for writenotify 76 * (see vma_wants_writenotify()). If "dirty", the assumption is that the 77 * FS was already notified and we can simply mark the PTE writable 78 * just like the write-fault handler would do. 79 */ 80 return pte_dirty(pte); 81 } 82 83 static long change_pte_range(struct mmu_gather *tlb, 84 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, 85 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 86 { 87 pte_t *pte, oldpte; 88 spinlock_t *ptl; 89 long pages = 0; 90 int target_node = NUMA_NO_NODE; 91 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 92 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 93 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 94 95 tlb_change_page_size(tlb, PAGE_SIZE); 96 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 97 if (!pte) 98 return -EAGAIN; 99 100 /* Get target node for single threaded private VMAs */ 101 if (prot_numa && !(vma->vm_flags & VM_SHARED) && 102 atomic_read(&vma->vm_mm->mm_users) == 1) 103 target_node = numa_node_id(); 104 105 flush_tlb_batched_pending(vma->vm_mm); 106 arch_enter_lazy_mmu_mode(); 107 do { 108 oldpte = ptep_get(pte); 109 if (pte_present(oldpte)) { 110 pte_t ptent; 111 112 /* 113 * Avoid trapping faults against the zero or KSM 114 * pages. See similar comment in change_huge_pmd. 115 */ 116 if (prot_numa) { 117 struct folio *folio; 118 int nid; 119 bool toptier; 120 121 /* Avoid TLB flush if possible */ 122 if (pte_protnone(oldpte)) 123 continue; 124 125 folio = vm_normal_folio(vma, addr, oldpte); 126 if (!folio || folio_is_zone_device(folio) || 127 folio_test_ksm(folio)) 128 continue; 129 130 /* Also skip shared copy-on-write pages */ 131 if (is_cow_mapping(vma->vm_flags) && 132 folio_ref_count(folio) != 1) 133 continue; 134 135 /* 136 * While migration can move some dirty pages, 137 * it cannot move them all from MIGRATE_ASYNC 138 * context. 139 */ 140 if (folio_is_file_lru(folio) && 141 folio_test_dirty(folio)) 142 continue; 143 144 /* 145 * Don't mess with PTEs if page is already on the node 146 * a single-threaded process is running on. 147 */ 148 nid = folio_nid(folio); 149 if (target_node == nid) 150 continue; 151 toptier = node_is_toptier(nid); 152 153 /* 154 * Skip scanning top tier node if normal numa 155 * balancing is disabled 156 */ 157 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 158 toptier) 159 continue; 160 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 161 !toptier) 162 folio_xchg_access_time(folio, 163 jiffies_to_msecs(jiffies)); 164 } 165 166 oldpte = ptep_modify_prot_start(vma, addr, pte); 167 ptent = pte_modify(oldpte, newprot); 168 169 if (uffd_wp) 170 ptent = pte_mkuffd_wp(ptent); 171 else if (uffd_wp_resolve) 172 ptent = pte_clear_uffd_wp(ptent); 173 174 /* 175 * In some writable, shared mappings, we might want 176 * to catch actual write access -- see 177 * vma_wants_writenotify(). 178 * 179 * In all writable, private mappings, we have to 180 * properly handle COW. 181 * 182 * In both cases, we can sometimes still change PTEs 183 * writable and avoid the write-fault handler, for 184 * example, if a PTE is already dirty and no other 185 * COW or special handling is required. 186 */ 187 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && 188 !pte_write(ptent) && 189 can_change_pte_writable(vma, addr, ptent)) 190 ptent = pte_mkwrite(ptent, vma); 191 192 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); 193 if (pte_needs_flush(oldpte, ptent)) 194 tlb_flush_pte_range(tlb, addr, PAGE_SIZE); 195 pages++; 196 } else if (is_swap_pte(oldpte)) { 197 swp_entry_t entry = pte_to_swp_entry(oldpte); 198 pte_t newpte; 199 200 if (is_writable_migration_entry(entry)) { 201 struct page *page = pfn_swap_entry_to_page(entry); 202 203 /* 204 * A protection check is difficult so 205 * just be safe and disable write 206 */ 207 if (PageAnon(page)) 208 entry = make_readable_exclusive_migration_entry( 209 swp_offset(entry)); 210 else 211 entry = make_readable_migration_entry(swp_offset(entry)); 212 newpte = swp_entry_to_pte(entry); 213 if (pte_swp_soft_dirty(oldpte)) 214 newpte = pte_swp_mksoft_dirty(newpte); 215 } else if (is_writable_device_private_entry(entry)) { 216 /* 217 * We do not preserve soft-dirtiness. See 218 * copy_nonpresent_pte() for explanation. 219 */ 220 entry = make_readable_device_private_entry( 221 swp_offset(entry)); 222 newpte = swp_entry_to_pte(entry); 223 if (pte_swp_uffd_wp(oldpte)) 224 newpte = pte_swp_mkuffd_wp(newpte); 225 } else if (is_writable_device_exclusive_entry(entry)) { 226 entry = make_readable_device_exclusive_entry( 227 swp_offset(entry)); 228 newpte = swp_entry_to_pte(entry); 229 if (pte_swp_soft_dirty(oldpte)) 230 newpte = pte_swp_mksoft_dirty(newpte); 231 if (pte_swp_uffd_wp(oldpte)) 232 newpte = pte_swp_mkuffd_wp(newpte); 233 } else if (is_pte_marker_entry(entry)) { 234 /* 235 * Ignore error swap entries unconditionally, 236 * because any access should sigbus anyway. 237 */ 238 if (is_poisoned_swp_entry(entry)) 239 continue; 240 /* 241 * If this is uffd-wp pte marker and we'd like 242 * to unprotect it, drop it; the next page 243 * fault will trigger without uffd trapping. 244 */ 245 if (uffd_wp_resolve) { 246 pte_clear(vma->vm_mm, addr, pte); 247 pages++; 248 } 249 continue; 250 } else { 251 newpte = oldpte; 252 } 253 254 if (uffd_wp) 255 newpte = pte_swp_mkuffd_wp(newpte); 256 else if (uffd_wp_resolve) 257 newpte = pte_swp_clear_uffd_wp(newpte); 258 259 if (!pte_same(oldpte, newpte)) { 260 set_pte_at(vma->vm_mm, addr, pte, newpte); 261 pages++; 262 } 263 } else { 264 /* It must be an none page, or what else?.. */ 265 WARN_ON_ONCE(!pte_none(oldpte)); 266 267 /* 268 * Nobody plays with any none ptes besides 269 * userfaultfd when applying the protections. 270 */ 271 if (likely(!uffd_wp)) 272 continue; 273 274 if (userfaultfd_wp_use_markers(vma)) { 275 /* 276 * For file-backed mem, we need to be able to 277 * wr-protect a none pte, because even if the 278 * pte is none, the page/swap cache could 279 * exist. Doing that by install a marker. 280 */ 281 set_pte_at(vma->vm_mm, addr, pte, 282 make_pte_marker(PTE_MARKER_UFFD_WP)); 283 pages++; 284 } 285 } 286 } while (pte++, addr += PAGE_SIZE, addr != end); 287 arch_leave_lazy_mmu_mode(); 288 pte_unmap_unlock(pte - 1, ptl); 289 290 return pages; 291 } 292 293 /* 294 * Return true if we want to split THPs into PTE mappings in change 295 * protection procedure, false otherwise. 296 */ 297 static inline bool 298 pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags) 299 { 300 /* 301 * pte markers only resides in pte level, if we need pte markers, 302 * we need to split. We cannot wr-protect shmem thp because file 303 * thp is handled differently when split by erasing the pmd so far. 304 */ 305 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma); 306 } 307 308 /* 309 * Return true if we want to populate pgtables in change protection 310 * procedure, false otherwise 311 */ 312 static inline bool 313 pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags) 314 { 315 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */ 316 if (!(cp_flags & MM_CP_UFFD_WP)) 317 return false; 318 319 /* Populate if the userfaultfd mode requires pte markers */ 320 return userfaultfd_wp_use_markers(vma); 321 } 322 323 /* 324 * Populate the pgtable underneath for whatever reason if requested. 325 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable 326 * allocation failures during page faults by kicking OOM and returning 327 * error. 328 */ 329 #define change_pmd_prepare(vma, pmd, cp_flags) \ 330 ({ \ 331 long err = 0; \ 332 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 333 if (pte_alloc(vma->vm_mm, pmd)) \ 334 err = -ENOMEM; \ 335 } \ 336 err; \ 337 }) 338 339 /* 340 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to 341 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, 342 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. 343 */ 344 #define change_prepare(vma, high, low, addr, cp_flags) \ 345 ({ \ 346 long err = 0; \ 347 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 348 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ 349 if (p == NULL) \ 350 err = -ENOMEM; \ 351 } \ 352 err; \ 353 }) 354 355 static inline long change_pmd_range(struct mmu_gather *tlb, 356 struct vm_area_struct *vma, pud_t *pud, unsigned long addr, 357 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 358 { 359 pmd_t *pmd; 360 unsigned long next; 361 long pages = 0; 362 unsigned long nr_huge_updates = 0; 363 struct mmu_notifier_range range; 364 365 range.start = 0; 366 367 pmd = pmd_offset(pud, addr); 368 do { 369 long ret; 370 pmd_t _pmd; 371 again: 372 next = pmd_addr_end(addr, end); 373 374 ret = change_pmd_prepare(vma, pmd, cp_flags); 375 if (ret) { 376 pages = ret; 377 break; 378 } 379 380 if (pmd_none(*pmd)) 381 goto next; 382 383 /* invoke the mmu notifier if the pmd is populated */ 384 if (!range.start) { 385 mmu_notifier_range_init(&range, 386 MMU_NOTIFY_PROTECTION_VMA, 0, 387 vma->vm_mm, addr, end); 388 mmu_notifier_invalidate_range_start(&range); 389 } 390 391 _pmd = pmdp_get_lockless(pmd); 392 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) { 393 if ((next - addr != HPAGE_PMD_SIZE) || 394 pgtable_split_needed(vma, cp_flags)) { 395 __split_huge_pmd(vma, pmd, addr, false, NULL); 396 /* 397 * For file-backed, the pmd could have been 398 * cleared; make sure pmd populated if 399 * necessary, then fall-through to pte level. 400 */ 401 ret = change_pmd_prepare(vma, pmd, cp_flags); 402 if (ret) { 403 pages = ret; 404 break; 405 } 406 } else { 407 ret = change_huge_pmd(tlb, vma, pmd, 408 addr, newprot, cp_flags); 409 if (ret) { 410 if (ret == HPAGE_PMD_NR) { 411 pages += HPAGE_PMD_NR; 412 nr_huge_updates++; 413 } 414 415 /* huge pmd was handled */ 416 goto next; 417 } 418 } 419 /* fall through, the trans huge pmd just split */ 420 } 421 422 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, 423 cp_flags); 424 if (ret < 0) 425 goto again; 426 pages += ret; 427 next: 428 cond_resched(); 429 } while (pmd++, addr = next, addr != end); 430 431 if (range.start) 432 mmu_notifier_invalidate_range_end(&range); 433 434 if (nr_huge_updates) 435 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 436 return pages; 437 } 438 439 static inline long change_pud_range(struct mmu_gather *tlb, 440 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 441 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 442 { 443 pud_t *pud; 444 unsigned long next; 445 long pages = 0, ret; 446 447 pud = pud_offset(p4d, addr); 448 do { 449 next = pud_addr_end(addr, end); 450 ret = change_prepare(vma, pud, pmd, addr, cp_flags); 451 if (ret) 452 return ret; 453 if (pud_none_or_clear_bad(pud)) 454 continue; 455 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot, 456 cp_flags); 457 } while (pud++, addr = next, addr != end); 458 459 return pages; 460 } 461 462 static inline long change_p4d_range(struct mmu_gather *tlb, 463 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 464 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 465 { 466 p4d_t *p4d; 467 unsigned long next; 468 long pages = 0, ret; 469 470 p4d = p4d_offset(pgd, addr); 471 do { 472 next = p4d_addr_end(addr, end); 473 ret = change_prepare(vma, p4d, pud, addr, cp_flags); 474 if (ret) 475 return ret; 476 if (p4d_none_or_clear_bad(p4d)) 477 continue; 478 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 479 cp_flags); 480 } while (p4d++, addr = next, addr != end); 481 482 return pages; 483 } 484 485 static long change_protection_range(struct mmu_gather *tlb, 486 struct vm_area_struct *vma, unsigned long addr, 487 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 488 { 489 struct mm_struct *mm = vma->vm_mm; 490 pgd_t *pgd; 491 unsigned long next; 492 long pages = 0, ret; 493 494 BUG_ON(addr >= end); 495 pgd = pgd_offset(mm, addr); 496 tlb_start_vma(tlb, vma); 497 do { 498 next = pgd_addr_end(addr, end); 499 ret = change_prepare(vma, pgd, p4d, addr, cp_flags); 500 if (ret) { 501 pages = ret; 502 break; 503 } 504 if (pgd_none_or_clear_bad(pgd)) 505 continue; 506 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 507 cp_flags); 508 } while (pgd++, addr = next, addr != end); 509 510 tlb_end_vma(tlb, vma); 511 512 return pages; 513 } 514 515 long change_protection(struct mmu_gather *tlb, 516 struct vm_area_struct *vma, unsigned long start, 517 unsigned long end, unsigned long cp_flags) 518 { 519 pgprot_t newprot = vma->vm_page_prot; 520 long pages; 521 522 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 523 524 #ifdef CONFIG_NUMA_BALANCING 525 /* 526 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) 527 * are expected to reflect their requirements via VMA flags such that 528 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. 529 */ 530 if (cp_flags & MM_CP_PROT_NUMA) 531 newprot = PAGE_NONE; 532 #else 533 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); 534 #endif 535 536 if (is_vm_hugetlb_page(vma)) 537 pages = hugetlb_change_protection(vma, start, end, newprot, 538 cp_flags); 539 else 540 pages = change_protection_range(tlb, vma, start, end, newprot, 541 cp_flags); 542 543 return pages; 544 } 545 546 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 547 unsigned long next, struct mm_walk *walk) 548 { 549 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 550 *(pgprot_t *)(walk->private)) ? 551 0 : -EACCES; 552 } 553 554 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 555 unsigned long addr, unsigned long next, 556 struct mm_walk *walk) 557 { 558 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 559 *(pgprot_t *)(walk->private)) ? 560 0 : -EACCES; 561 } 562 563 static int prot_none_test(unsigned long addr, unsigned long next, 564 struct mm_walk *walk) 565 { 566 return 0; 567 } 568 569 static const struct mm_walk_ops prot_none_walk_ops = { 570 .pte_entry = prot_none_pte_entry, 571 .hugetlb_entry = prot_none_hugetlb_entry, 572 .test_walk = prot_none_test, 573 .walk_lock = PGWALK_WRLOCK, 574 }; 575 576 int 577 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, 578 struct vm_area_struct *vma, struct vm_area_struct **pprev, 579 unsigned long start, unsigned long end, unsigned long newflags) 580 { 581 struct mm_struct *mm = vma->vm_mm; 582 unsigned long oldflags = vma->vm_flags; 583 long nrpages = (end - start) >> PAGE_SHIFT; 584 unsigned int mm_cp_flags = 0; 585 unsigned long charged = 0; 586 int error; 587 588 if (newflags == oldflags) { 589 *pprev = vma; 590 return 0; 591 } 592 593 /* 594 * Do PROT_NONE PFN permission checks here when we can still 595 * bail out without undoing a lot of state. This is a rather 596 * uncommon case, so doesn't need to be very optimized. 597 */ 598 if (arch_has_pfn_modify_check() && 599 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 600 (newflags & VM_ACCESS_FLAGS) == 0) { 601 pgprot_t new_pgprot = vm_get_page_prot(newflags); 602 603 error = walk_page_range(current->mm, start, end, 604 &prot_none_walk_ops, &new_pgprot); 605 if (error) 606 return error; 607 } 608 609 /* 610 * If we make a private mapping writable we increase our commit; 611 * but (without finer accounting) cannot reduce our commit if we 612 * make it unwritable again except in the anonymous case where no 613 * anon_vma has yet to be assigned. 614 * 615 * hugetlb mapping were accounted for even if read-only so there is 616 * no need to account for them here. 617 */ 618 if (newflags & VM_WRITE) { 619 /* Check space limits when area turns into data. */ 620 if (!may_expand_vm(mm, newflags, nrpages) && 621 may_expand_vm(mm, oldflags, nrpages)) 622 return -ENOMEM; 623 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 624 VM_SHARED|VM_NORESERVE))) { 625 charged = nrpages; 626 if (security_vm_enough_memory_mm(mm, charged)) 627 return -ENOMEM; 628 newflags |= VM_ACCOUNT; 629 } 630 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) && 631 !vma->anon_vma) { 632 newflags &= ~VM_ACCOUNT; 633 } 634 635 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags); 636 if (IS_ERR(vma)) { 637 error = PTR_ERR(vma); 638 goto fail; 639 } 640 641 *pprev = vma; 642 643 /* 644 * vm_flags and vm_page_prot are protected by the mmap_lock 645 * held in write mode. 646 */ 647 vma_start_write(vma); 648 vm_flags_reset(vma, newflags); 649 if (vma_wants_manual_pte_write_upgrade(vma)) 650 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 651 vma_set_page_prot(vma); 652 653 change_protection(tlb, vma, start, end, mm_cp_flags); 654 655 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT)) 656 vm_unacct_memory(nrpages); 657 658 /* 659 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 660 * fault on access. 661 */ 662 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 663 (newflags & VM_WRITE)) { 664 populate_vma_page_range(vma, start, end, NULL); 665 } 666 667 vm_stat_account(mm, oldflags, -nrpages); 668 vm_stat_account(mm, newflags, nrpages); 669 perf_event_mmap(vma); 670 return 0; 671 672 fail: 673 vm_unacct_memory(charged); 674 return error; 675 } 676 677 /* 678 * pkey==-1 when doing a legacy mprotect() 679 */ 680 static int do_mprotect_pkey(unsigned long start, size_t len, 681 unsigned long prot, int pkey) 682 { 683 unsigned long nstart, end, tmp, reqprot; 684 struct vm_area_struct *vma, *prev; 685 int error; 686 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 687 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 688 (prot & PROT_READ); 689 struct mmu_gather tlb; 690 struct vma_iterator vmi; 691 692 start = untagged_addr(start); 693 694 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 695 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 696 return -EINVAL; 697 698 if (start & ~PAGE_MASK) 699 return -EINVAL; 700 if (!len) 701 return 0; 702 len = PAGE_ALIGN(len); 703 end = start + len; 704 if (end <= start) 705 return -ENOMEM; 706 if (!arch_validate_prot(prot, start)) 707 return -EINVAL; 708 709 reqprot = prot; 710 711 if (mmap_write_lock_killable(current->mm)) 712 return -EINTR; 713 714 /* 715 * If userspace did not allocate the pkey, do not let 716 * them use it here. 717 */ 718 error = -EINVAL; 719 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 720 goto out; 721 722 vma_iter_init(&vmi, current->mm, start); 723 vma = vma_find(&vmi, end); 724 error = -ENOMEM; 725 if (!vma) 726 goto out; 727 728 if (unlikely(grows & PROT_GROWSDOWN)) { 729 if (vma->vm_start >= end) 730 goto out; 731 start = vma->vm_start; 732 error = -EINVAL; 733 if (!(vma->vm_flags & VM_GROWSDOWN)) 734 goto out; 735 } else { 736 if (vma->vm_start > start) 737 goto out; 738 if (unlikely(grows & PROT_GROWSUP)) { 739 end = vma->vm_end; 740 error = -EINVAL; 741 if (!(vma->vm_flags & VM_GROWSUP)) 742 goto out; 743 } 744 } 745 746 prev = vma_prev(&vmi); 747 if (start > vma->vm_start) 748 prev = vma; 749 750 tlb_gather_mmu(&tlb, current->mm); 751 nstart = start; 752 tmp = vma->vm_start; 753 for_each_vma_range(vmi, vma, end) { 754 unsigned long mask_off_old_flags; 755 unsigned long newflags; 756 int new_vma_pkey; 757 758 if (vma->vm_start != tmp) { 759 error = -ENOMEM; 760 break; 761 } 762 763 /* Does the application expect PROT_READ to imply PROT_EXEC */ 764 if (rier && (vma->vm_flags & VM_MAYEXEC)) 765 prot |= PROT_EXEC; 766 767 /* 768 * Each mprotect() call explicitly passes r/w/x permissions. 769 * If a permission is not passed to mprotect(), it must be 770 * cleared from the VMA. 771 */ 772 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 773 774 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 775 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 776 newflags |= (vma->vm_flags & ~mask_off_old_flags); 777 778 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 779 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 780 error = -EACCES; 781 break; 782 } 783 784 if (map_deny_write_exec(vma, newflags)) { 785 error = -EACCES; 786 break; 787 } 788 789 /* Allow architectures to sanity-check the new flags */ 790 if (!arch_validate_flags(newflags)) { 791 error = -EINVAL; 792 break; 793 } 794 795 error = security_file_mprotect(vma, reqprot, prot); 796 if (error) 797 break; 798 799 tmp = vma->vm_end; 800 if (tmp > end) 801 tmp = end; 802 803 if (vma->vm_ops && vma->vm_ops->mprotect) { 804 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 805 if (error) 806 break; 807 } 808 809 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); 810 if (error) 811 break; 812 813 tmp = vma_iter_end(&vmi); 814 nstart = tmp; 815 prot = reqprot; 816 } 817 tlb_finish_mmu(&tlb); 818 819 if (!error && tmp < end) 820 error = -ENOMEM; 821 822 out: 823 mmap_write_unlock(current->mm); 824 return error; 825 } 826 827 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 828 unsigned long, prot) 829 { 830 return do_mprotect_pkey(start, len, prot, -1); 831 } 832 833 #ifdef CONFIG_ARCH_HAS_PKEYS 834 835 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 836 unsigned long, prot, int, pkey) 837 { 838 return do_mprotect_pkey(start, len, prot, pkey); 839 } 840 841 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 842 { 843 int pkey; 844 int ret; 845 846 /* No flags supported yet. */ 847 if (flags) 848 return -EINVAL; 849 /* check for unsupported init values */ 850 if (init_val & ~PKEY_ACCESS_MASK) 851 return -EINVAL; 852 853 mmap_write_lock(current->mm); 854 pkey = mm_pkey_alloc(current->mm); 855 856 ret = -ENOSPC; 857 if (pkey == -1) 858 goto out; 859 860 ret = arch_set_user_pkey_access(current, pkey, init_val); 861 if (ret) { 862 mm_pkey_free(current->mm, pkey); 863 goto out; 864 } 865 ret = pkey; 866 out: 867 mmap_write_unlock(current->mm); 868 return ret; 869 } 870 871 SYSCALL_DEFINE1(pkey_free, int, pkey) 872 { 873 int ret; 874 875 mmap_write_lock(current->mm); 876 ret = mm_pkey_free(current->mm, pkey); 877 mmap_write_unlock(current->mm); 878 879 /* 880 * We could provide warnings or errors if any VMA still 881 * has the pkey set here. 882 */ 883 return ret; 884 } 885 886 #endif /* CONFIG_ARCH_HAS_PKEYS */ 887