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_maybe_dma_pinned(folio) || 133 folio_likely_mapped_shared(folio))) 134 continue; 135 136 /* 137 * While migration can move some dirty pages, 138 * it cannot move them all from MIGRATE_ASYNC 139 * context. 140 */ 141 if (folio_is_file_lru(folio) && 142 folio_test_dirty(folio)) 143 continue; 144 145 /* 146 * Don't mess with PTEs if page is already on the node 147 * a single-threaded process is running on. 148 */ 149 nid = folio_nid(folio); 150 if (target_node == nid) 151 continue; 152 toptier = node_is_toptier(nid); 153 154 /* 155 * Skip scanning top tier node if normal numa 156 * balancing is disabled 157 */ 158 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 159 toptier) 160 continue; 161 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 162 !toptier) 163 folio_xchg_access_time(folio, 164 jiffies_to_msecs(jiffies)); 165 } 166 167 oldpte = ptep_modify_prot_start(vma, addr, pte); 168 ptent = pte_modify(oldpte, newprot); 169 170 if (uffd_wp) 171 ptent = pte_mkuffd_wp(ptent); 172 else if (uffd_wp_resolve) 173 ptent = pte_clear_uffd_wp(ptent); 174 175 /* 176 * In some writable, shared mappings, we might want 177 * to catch actual write access -- see 178 * vma_wants_writenotify(). 179 * 180 * In all writable, private mappings, we have to 181 * properly handle COW. 182 * 183 * In both cases, we can sometimes still change PTEs 184 * writable and avoid the write-fault handler, for 185 * example, if a PTE is already dirty and no other 186 * COW or special handling is required. 187 */ 188 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && 189 !pte_write(ptent) && 190 can_change_pte_writable(vma, addr, ptent)) 191 ptent = pte_mkwrite(ptent, vma); 192 193 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); 194 if (pte_needs_flush(oldpte, ptent)) 195 tlb_flush_pte_range(tlb, addr, PAGE_SIZE); 196 pages++; 197 } else if (is_swap_pte(oldpte)) { 198 swp_entry_t entry = pte_to_swp_entry(oldpte); 199 pte_t newpte; 200 201 if (is_writable_migration_entry(entry)) { 202 struct folio *folio = pfn_swap_entry_folio(entry); 203 204 /* 205 * A protection check is difficult so 206 * just be safe and disable write 207 */ 208 if (folio_test_anon(folio)) 209 entry = make_readable_exclusive_migration_entry( 210 swp_offset(entry)); 211 else 212 entry = make_readable_migration_entry(swp_offset(entry)); 213 newpte = swp_entry_to_pte(entry); 214 if (pte_swp_soft_dirty(oldpte)) 215 newpte = pte_swp_mksoft_dirty(newpte); 216 } else if (is_writable_device_private_entry(entry)) { 217 /* 218 * We do not preserve soft-dirtiness. See 219 * copy_nonpresent_pte() for explanation. 220 */ 221 entry = make_readable_device_private_entry( 222 swp_offset(entry)); 223 newpte = swp_entry_to_pte(entry); 224 if (pte_swp_uffd_wp(oldpte)) 225 newpte = pte_swp_mkuffd_wp(newpte); 226 } else if (is_writable_device_exclusive_entry(entry)) { 227 entry = make_readable_device_exclusive_entry( 228 swp_offset(entry)); 229 newpte = swp_entry_to_pte(entry); 230 if (pte_swp_soft_dirty(oldpte)) 231 newpte = pte_swp_mksoft_dirty(newpte); 232 if (pte_swp_uffd_wp(oldpte)) 233 newpte = pte_swp_mkuffd_wp(newpte); 234 } else if (is_pte_marker_entry(entry)) { 235 /* 236 * Ignore error swap entries unconditionally, 237 * because any access should sigbus anyway. 238 */ 239 if (is_poisoned_swp_entry(entry)) 240 continue; 241 /* 242 * If this is uffd-wp pte marker and we'd like 243 * to unprotect it, drop it; the next page 244 * fault will trigger without uffd trapping. 245 */ 246 if (uffd_wp_resolve) { 247 pte_clear(vma->vm_mm, addr, pte); 248 pages++; 249 } 250 continue; 251 } else { 252 newpte = oldpte; 253 } 254 255 if (uffd_wp) 256 newpte = pte_swp_mkuffd_wp(newpte); 257 else if (uffd_wp_resolve) 258 newpte = pte_swp_clear_uffd_wp(newpte); 259 260 if (!pte_same(oldpte, newpte)) { 261 set_pte_at(vma->vm_mm, addr, pte, newpte); 262 pages++; 263 } 264 } else { 265 /* It must be an none page, or what else?.. */ 266 WARN_ON_ONCE(!pte_none(oldpte)); 267 268 /* 269 * Nobody plays with any none ptes besides 270 * userfaultfd when applying the protections. 271 */ 272 if (likely(!uffd_wp)) 273 continue; 274 275 if (userfaultfd_wp_use_markers(vma)) { 276 /* 277 * For file-backed mem, we need to be able to 278 * wr-protect a none pte, because even if the 279 * pte is none, the page/swap cache could 280 * exist. Doing that by install a marker. 281 */ 282 set_pte_at(vma->vm_mm, addr, pte, 283 make_pte_marker(PTE_MARKER_UFFD_WP)); 284 pages++; 285 } 286 } 287 } while (pte++, addr += PAGE_SIZE, addr != end); 288 arch_leave_lazy_mmu_mode(); 289 pte_unmap_unlock(pte - 1, ptl); 290 291 return pages; 292 } 293 294 /* 295 * Return true if we want to split THPs into PTE mappings in change 296 * protection procedure, false otherwise. 297 */ 298 static inline bool 299 pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags) 300 { 301 /* 302 * pte markers only resides in pte level, if we need pte markers, 303 * we need to split. We cannot wr-protect shmem thp because file 304 * thp is handled differently when split by erasing the pmd so far. 305 */ 306 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma); 307 } 308 309 /* 310 * Return true if we want to populate pgtables in change protection 311 * procedure, false otherwise 312 */ 313 static inline bool 314 pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags) 315 { 316 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */ 317 if (!(cp_flags & MM_CP_UFFD_WP)) 318 return false; 319 320 /* Populate if the userfaultfd mode requires pte markers */ 321 return userfaultfd_wp_use_markers(vma); 322 } 323 324 /* 325 * Populate the pgtable underneath for whatever reason if requested. 326 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable 327 * allocation failures during page faults by kicking OOM and returning 328 * error. 329 */ 330 #define change_pmd_prepare(vma, pmd, cp_flags) \ 331 ({ \ 332 long err = 0; \ 333 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 334 if (pte_alloc(vma->vm_mm, pmd)) \ 335 err = -ENOMEM; \ 336 } \ 337 err; \ 338 }) 339 340 /* 341 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to 342 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, 343 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. 344 */ 345 #define change_prepare(vma, high, low, addr, cp_flags) \ 346 ({ \ 347 long err = 0; \ 348 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 349 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ 350 if (p == NULL) \ 351 err = -ENOMEM; \ 352 } \ 353 err; \ 354 }) 355 356 static inline long change_pmd_range(struct mmu_gather *tlb, 357 struct vm_area_struct *vma, pud_t *pud, unsigned long addr, 358 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 359 { 360 pmd_t *pmd; 361 unsigned long next; 362 long pages = 0; 363 unsigned long nr_huge_updates = 0; 364 struct mmu_notifier_range range; 365 366 range.start = 0; 367 368 pmd = pmd_offset(pud, addr); 369 do { 370 long ret; 371 pmd_t _pmd; 372 again: 373 next = pmd_addr_end(addr, end); 374 375 ret = change_pmd_prepare(vma, pmd, cp_flags); 376 if (ret) { 377 pages = ret; 378 break; 379 } 380 381 if (pmd_none(*pmd)) 382 goto next; 383 384 /* invoke the mmu notifier if the pmd is populated */ 385 if (!range.start) { 386 mmu_notifier_range_init(&range, 387 MMU_NOTIFY_PROTECTION_VMA, 0, 388 vma->vm_mm, addr, end); 389 mmu_notifier_invalidate_range_start(&range); 390 } 391 392 _pmd = pmdp_get_lockless(pmd); 393 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) { 394 if ((next - addr != HPAGE_PMD_SIZE) || 395 pgtable_split_needed(vma, cp_flags)) { 396 __split_huge_pmd(vma, pmd, addr, false, NULL); 397 /* 398 * For file-backed, the pmd could have been 399 * cleared; make sure pmd populated if 400 * necessary, then fall-through to pte level. 401 */ 402 ret = change_pmd_prepare(vma, pmd, cp_flags); 403 if (ret) { 404 pages = ret; 405 break; 406 } 407 } else { 408 ret = change_huge_pmd(tlb, vma, pmd, 409 addr, newprot, cp_flags); 410 if (ret) { 411 if (ret == HPAGE_PMD_NR) { 412 pages += HPAGE_PMD_NR; 413 nr_huge_updates++; 414 } 415 416 /* huge pmd was handled */ 417 goto next; 418 } 419 } 420 /* fall through, the trans huge pmd just split */ 421 } 422 423 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, 424 cp_flags); 425 if (ret < 0) 426 goto again; 427 pages += ret; 428 next: 429 cond_resched(); 430 } while (pmd++, addr = next, addr != end); 431 432 if (range.start) 433 mmu_notifier_invalidate_range_end(&range); 434 435 if (nr_huge_updates) 436 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 437 return pages; 438 } 439 440 static inline long change_pud_range(struct mmu_gather *tlb, 441 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 442 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 443 { 444 pud_t *pud; 445 unsigned long next; 446 long pages = 0, ret; 447 448 pud = pud_offset(p4d, addr); 449 do { 450 next = pud_addr_end(addr, end); 451 ret = change_prepare(vma, pud, pmd, addr, cp_flags); 452 if (ret) 453 return ret; 454 if (pud_none_or_clear_bad(pud)) 455 continue; 456 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot, 457 cp_flags); 458 } while (pud++, addr = next, addr != end); 459 460 return pages; 461 } 462 463 static inline long change_p4d_range(struct mmu_gather *tlb, 464 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 465 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 466 { 467 p4d_t *p4d; 468 unsigned long next; 469 long pages = 0, ret; 470 471 p4d = p4d_offset(pgd, addr); 472 do { 473 next = p4d_addr_end(addr, end); 474 ret = change_prepare(vma, p4d, pud, addr, cp_flags); 475 if (ret) 476 return ret; 477 if (p4d_none_or_clear_bad(p4d)) 478 continue; 479 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 480 cp_flags); 481 } while (p4d++, addr = next, addr != end); 482 483 return pages; 484 } 485 486 static long change_protection_range(struct mmu_gather *tlb, 487 struct vm_area_struct *vma, unsigned long addr, 488 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 489 { 490 struct mm_struct *mm = vma->vm_mm; 491 pgd_t *pgd; 492 unsigned long next; 493 long pages = 0, ret; 494 495 BUG_ON(addr >= end); 496 pgd = pgd_offset(mm, addr); 497 tlb_start_vma(tlb, vma); 498 do { 499 next = pgd_addr_end(addr, end); 500 ret = change_prepare(vma, pgd, p4d, addr, cp_flags); 501 if (ret) { 502 pages = ret; 503 break; 504 } 505 if (pgd_none_or_clear_bad(pgd)) 506 continue; 507 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 508 cp_flags); 509 } while (pgd++, addr = next, addr != end); 510 511 tlb_end_vma(tlb, vma); 512 513 return pages; 514 } 515 516 long change_protection(struct mmu_gather *tlb, 517 struct vm_area_struct *vma, unsigned long start, 518 unsigned long end, unsigned long cp_flags) 519 { 520 pgprot_t newprot = vma->vm_page_prot; 521 long pages; 522 523 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 524 525 #ifdef CONFIG_NUMA_BALANCING 526 /* 527 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) 528 * are expected to reflect their requirements via VMA flags such that 529 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. 530 */ 531 if (cp_flags & MM_CP_PROT_NUMA) 532 newprot = PAGE_NONE; 533 #else 534 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); 535 #endif 536 537 if (is_vm_hugetlb_page(vma)) 538 pages = hugetlb_change_protection(vma, start, end, newprot, 539 cp_flags); 540 else 541 pages = change_protection_range(tlb, vma, start, end, newprot, 542 cp_flags); 543 544 return pages; 545 } 546 547 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 548 unsigned long next, struct mm_walk *walk) 549 { 550 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 551 *(pgprot_t *)(walk->private)) ? 552 0 : -EACCES; 553 } 554 555 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 556 unsigned long addr, unsigned long next, 557 struct mm_walk *walk) 558 { 559 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 560 *(pgprot_t *)(walk->private)) ? 561 0 : -EACCES; 562 } 563 564 static int prot_none_test(unsigned long addr, unsigned long next, 565 struct mm_walk *walk) 566 { 567 return 0; 568 } 569 570 static const struct mm_walk_ops prot_none_walk_ops = { 571 .pte_entry = prot_none_pte_entry, 572 .hugetlb_entry = prot_none_hugetlb_entry, 573 .test_walk = prot_none_test, 574 .walk_lock = PGWALK_WRLOCK, 575 }; 576 577 int 578 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, 579 struct vm_area_struct *vma, struct vm_area_struct **pprev, 580 unsigned long start, unsigned long end, unsigned long newflags) 581 { 582 struct mm_struct *mm = vma->vm_mm; 583 unsigned long oldflags = vma->vm_flags; 584 long nrpages = (end - start) >> PAGE_SHIFT; 585 unsigned int mm_cp_flags = 0; 586 unsigned long charged = 0; 587 int error; 588 589 if (newflags == oldflags) { 590 *pprev = vma; 591 return 0; 592 } 593 594 /* 595 * Do PROT_NONE PFN permission checks here when we can still 596 * bail out without undoing a lot of state. This is a rather 597 * uncommon case, so doesn't need to be very optimized. 598 */ 599 if (arch_has_pfn_modify_check() && 600 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 601 (newflags & VM_ACCESS_FLAGS) == 0) { 602 pgprot_t new_pgprot = vm_get_page_prot(newflags); 603 604 error = walk_page_range(current->mm, start, end, 605 &prot_none_walk_ops, &new_pgprot); 606 if (error) 607 return error; 608 } 609 610 /* 611 * If we make a private mapping writable we increase our commit; 612 * but (without finer accounting) cannot reduce our commit if we 613 * make it unwritable again except in the anonymous case where no 614 * anon_vma has yet to be assigned. 615 * 616 * hugetlb mapping were accounted for even if read-only so there is 617 * no need to account for them here. 618 */ 619 if (newflags & VM_WRITE) { 620 /* Check space limits when area turns into data. */ 621 if (!may_expand_vm(mm, newflags, nrpages) && 622 may_expand_vm(mm, oldflags, nrpages)) 623 return -ENOMEM; 624 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 625 VM_SHARED|VM_NORESERVE))) { 626 charged = nrpages; 627 if (security_vm_enough_memory_mm(mm, charged)) 628 return -ENOMEM; 629 newflags |= VM_ACCOUNT; 630 } 631 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) && 632 !vma->anon_vma) { 633 newflags &= ~VM_ACCOUNT; 634 } 635 636 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags); 637 if (IS_ERR(vma)) { 638 error = PTR_ERR(vma); 639 goto fail; 640 } 641 642 *pprev = vma; 643 644 /* 645 * vm_flags and vm_page_prot are protected by the mmap_lock 646 * held in write mode. 647 */ 648 vma_start_write(vma); 649 vm_flags_reset(vma, newflags); 650 if (vma_wants_manual_pte_write_upgrade(vma)) 651 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 652 vma_set_page_prot(vma); 653 654 change_protection(tlb, vma, start, end, mm_cp_flags); 655 656 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT)) 657 vm_unacct_memory(nrpages); 658 659 /* 660 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 661 * fault on access. 662 */ 663 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 664 (newflags & VM_WRITE)) { 665 populate_vma_page_range(vma, start, end, NULL); 666 } 667 668 vm_stat_account(mm, oldflags, -nrpages); 669 vm_stat_account(mm, newflags, nrpages); 670 perf_event_mmap(vma); 671 return 0; 672 673 fail: 674 vm_unacct_memory(charged); 675 return error; 676 } 677 678 /* 679 * pkey==-1 when doing a legacy mprotect() 680 */ 681 static int do_mprotect_pkey(unsigned long start, size_t len, 682 unsigned long prot, int pkey) 683 { 684 unsigned long nstart, end, tmp, reqprot; 685 struct vm_area_struct *vma, *prev; 686 int error; 687 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 688 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 689 (prot & PROT_READ); 690 struct mmu_gather tlb; 691 struct vma_iterator vmi; 692 693 start = untagged_addr(start); 694 695 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 696 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 697 return -EINVAL; 698 699 if (start & ~PAGE_MASK) 700 return -EINVAL; 701 if (!len) 702 return 0; 703 len = PAGE_ALIGN(len); 704 end = start + len; 705 if (end <= start) 706 return -ENOMEM; 707 if (!arch_validate_prot(prot, start)) 708 return -EINVAL; 709 710 reqprot = prot; 711 712 if (mmap_write_lock_killable(current->mm)) 713 return -EINTR; 714 715 /* 716 * If userspace did not allocate the pkey, do not let 717 * them use it here. 718 */ 719 error = -EINVAL; 720 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 721 goto out; 722 723 vma_iter_init(&vmi, current->mm, start); 724 vma = vma_find(&vmi, end); 725 error = -ENOMEM; 726 if (!vma) 727 goto out; 728 729 if (unlikely(grows & PROT_GROWSDOWN)) { 730 if (vma->vm_start >= end) 731 goto out; 732 start = vma->vm_start; 733 error = -EINVAL; 734 if (!(vma->vm_flags & VM_GROWSDOWN)) 735 goto out; 736 } else { 737 if (vma->vm_start > start) 738 goto out; 739 if (unlikely(grows & PROT_GROWSUP)) { 740 end = vma->vm_end; 741 error = -EINVAL; 742 if (!(vma->vm_flags & VM_GROWSUP)) 743 goto out; 744 } 745 } 746 747 prev = vma_prev(&vmi); 748 if (start > vma->vm_start) 749 prev = vma; 750 751 tlb_gather_mmu(&tlb, current->mm); 752 nstart = start; 753 tmp = vma->vm_start; 754 for_each_vma_range(vmi, vma, end) { 755 unsigned long mask_off_old_flags; 756 unsigned long newflags; 757 int new_vma_pkey; 758 759 if (vma->vm_start != tmp) { 760 error = -ENOMEM; 761 break; 762 } 763 764 /* Does the application expect PROT_READ to imply PROT_EXEC */ 765 if (rier && (vma->vm_flags & VM_MAYEXEC)) 766 prot |= PROT_EXEC; 767 768 /* 769 * Each mprotect() call explicitly passes r/w/x permissions. 770 * If a permission is not passed to mprotect(), it must be 771 * cleared from the VMA. 772 */ 773 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 774 775 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 776 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 777 newflags |= (vma->vm_flags & ~mask_off_old_flags); 778 779 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 780 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 781 error = -EACCES; 782 break; 783 } 784 785 if (map_deny_write_exec(vma, newflags)) { 786 error = -EACCES; 787 break; 788 } 789 790 /* Allow architectures to sanity-check the new flags */ 791 if (!arch_validate_flags(newflags)) { 792 error = -EINVAL; 793 break; 794 } 795 796 error = security_file_mprotect(vma, reqprot, prot); 797 if (error) 798 break; 799 800 tmp = vma->vm_end; 801 if (tmp > end) 802 tmp = end; 803 804 if (vma->vm_ops && vma->vm_ops->mprotect) { 805 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 806 if (error) 807 break; 808 } 809 810 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); 811 if (error) 812 break; 813 814 tmp = vma_iter_end(&vmi); 815 nstart = tmp; 816 prot = reqprot; 817 } 818 tlb_finish_mmu(&tlb); 819 820 if (!error && tmp < end) 821 error = -ENOMEM; 822 823 out: 824 mmap_write_unlock(current->mm); 825 return error; 826 } 827 828 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 829 unsigned long, prot) 830 { 831 return do_mprotect_pkey(start, len, prot, -1); 832 } 833 834 #ifdef CONFIG_ARCH_HAS_PKEYS 835 836 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 837 unsigned long, prot, int, pkey) 838 { 839 return do_mprotect_pkey(start, len, prot, pkey); 840 } 841 842 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 843 { 844 int pkey; 845 int ret; 846 847 /* No flags supported yet. */ 848 if (flags) 849 return -EINVAL; 850 /* check for unsupported init values */ 851 if (init_val & ~PKEY_ACCESS_MASK) 852 return -EINVAL; 853 854 mmap_write_lock(current->mm); 855 pkey = mm_pkey_alloc(current->mm); 856 857 ret = -ENOSPC; 858 if (pkey == -1) 859 goto out; 860 861 ret = arch_set_user_pkey_access(current, pkey, init_val); 862 if (ret) { 863 mm_pkey_free(current->mm, pkey); 864 goto out; 865 } 866 ret = pkey; 867 out: 868 mmap_write_unlock(current->mm); 869 return ret; 870 } 871 872 SYSCALL_DEFINE1(pkey_free, int, pkey) 873 { 874 int ret; 875 876 mmap_write_lock(current->mm); 877 ret = mm_pkey_free(current->mm, pkey); 878 mmap_write_unlock(current->mm); 879 880 /* 881 * We could provide warnings or errors if any VMA still 882 * has the pkey set here. 883 */ 884 return ret; 885 } 886 887 #endif /* CONFIG_ARCH_HAS_PKEYS */ 888