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 <uapi/linux/mman.h> 36 #include <asm/cacheflush.h> 37 #include <asm/mmu_context.h> 38 #include <asm/tlbflush.h> 39 #include <asm/tlb.h> 40 41 #include "internal.h" 42 43 bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, 44 pte_t pte) 45 { 46 struct page *page; 47 48 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 49 return false; 50 51 /* Don't touch entries that are not even readable. */ 52 if (pte_protnone(pte)) 53 return false; 54 55 /* Do we need write faults for softdirty tracking? */ 56 if (pte_needs_soft_dirty_wp(vma, pte)) 57 return false; 58 59 /* Do we need write faults for uffd-wp tracking? */ 60 if (userfaultfd_pte_wp(vma, pte)) 61 return false; 62 63 if (!(vma->vm_flags & VM_SHARED)) { 64 /* 65 * Writable MAP_PRIVATE mapping: We can only special-case on 66 * exclusive anonymous pages, because we know that our 67 * write-fault handler similarly would map them writable without 68 * any additional checks while holding the PT lock. 69 */ 70 page = vm_normal_page(vma, addr, pte); 71 return page && PageAnon(page) && PageAnonExclusive(page); 72 } 73 74 VM_WARN_ON_ONCE(is_zero_pfn(pte_pfn(pte)) && pte_dirty(pte)); 75 76 /* 77 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still 78 * needs a real write-fault for writenotify 79 * (see vma_wants_writenotify()). If "dirty", the assumption is that the 80 * FS was already notified and we can simply mark the PTE writable 81 * just like the write-fault handler would do. 82 */ 83 return pte_dirty(pte); 84 } 85 86 static long change_pte_range(struct mmu_gather *tlb, 87 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, 88 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 89 { 90 pte_t *pte, oldpte; 91 spinlock_t *ptl; 92 long pages = 0; 93 int target_node = NUMA_NO_NODE; 94 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 95 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 96 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 97 98 tlb_change_page_size(tlb, PAGE_SIZE); 99 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 100 if (!pte) 101 return -EAGAIN; 102 103 /* Get target node for single threaded private VMAs */ 104 if (prot_numa && !(vma->vm_flags & VM_SHARED) && 105 atomic_read(&vma->vm_mm->mm_users) == 1) 106 target_node = numa_node_id(); 107 108 flush_tlb_batched_pending(vma->vm_mm); 109 arch_enter_lazy_mmu_mode(); 110 do { 111 oldpte = ptep_get(pte); 112 if (pte_present(oldpte)) { 113 pte_t ptent; 114 115 /* 116 * Avoid trapping faults against the zero or KSM 117 * pages. See similar comment in change_huge_pmd. 118 */ 119 if (prot_numa) { 120 struct folio *folio; 121 int nid; 122 bool toptier; 123 124 /* Avoid TLB flush if possible */ 125 if (pte_protnone(oldpte)) 126 continue; 127 128 folio = vm_normal_folio(vma, addr, oldpte); 129 if (!folio || folio_is_zone_device(folio) || 130 folio_test_ksm(folio)) 131 continue; 132 133 /* Also skip shared copy-on-write pages */ 134 if (is_cow_mapping(vma->vm_flags) && 135 (folio_maybe_dma_pinned(folio) || 136 folio_likely_mapped_shared(folio))) 137 continue; 138 139 /* 140 * While migration can move some dirty pages, 141 * it cannot move them all from MIGRATE_ASYNC 142 * context. 143 */ 144 if (folio_is_file_lru(folio) && 145 folio_test_dirty(folio)) 146 continue; 147 148 /* 149 * Don't mess with PTEs if page is already on the node 150 * a single-threaded process is running on. 151 */ 152 nid = folio_nid(folio); 153 if (target_node == nid) 154 continue; 155 toptier = node_is_toptier(nid); 156 157 /* 158 * Skip scanning top tier node if normal numa 159 * balancing is disabled 160 */ 161 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 162 toptier) 163 continue; 164 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 165 !toptier) 166 folio_xchg_access_time(folio, 167 jiffies_to_msecs(jiffies)); 168 } 169 170 oldpte = ptep_modify_prot_start(vma, addr, pte); 171 ptent = pte_modify(oldpte, newprot); 172 173 if (uffd_wp) 174 ptent = pte_mkuffd_wp(ptent); 175 else if (uffd_wp_resolve) 176 ptent = pte_clear_uffd_wp(ptent); 177 178 /* 179 * In some writable, shared mappings, we might want 180 * to catch actual write access -- see 181 * vma_wants_writenotify(). 182 * 183 * In all writable, private mappings, we have to 184 * properly handle COW. 185 * 186 * In both cases, we can sometimes still change PTEs 187 * writable and avoid the write-fault handler, for 188 * example, if a PTE is already dirty and no other 189 * COW or special handling is required. 190 */ 191 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && 192 !pte_write(ptent) && 193 can_change_pte_writable(vma, addr, ptent)) 194 ptent = pte_mkwrite(ptent, vma); 195 196 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); 197 if (pte_needs_flush(oldpte, ptent)) 198 tlb_flush_pte_range(tlb, addr, PAGE_SIZE); 199 pages++; 200 } else if (is_swap_pte(oldpte)) { 201 swp_entry_t entry = pte_to_swp_entry(oldpte); 202 pte_t newpte; 203 204 if (is_writable_migration_entry(entry)) { 205 struct folio *folio = pfn_swap_entry_folio(entry); 206 207 /* 208 * A protection check is difficult so 209 * just be safe and disable write 210 */ 211 if (folio_test_anon(folio)) 212 entry = make_readable_exclusive_migration_entry( 213 swp_offset(entry)); 214 else 215 entry = make_readable_migration_entry(swp_offset(entry)); 216 newpte = swp_entry_to_pte(entry); 217 if (pte_swp_soft_dirty(oldpte)) 218 newpte = pte_swp_mksoft_dirty(newpte); 219 } else if (is_writable_device_private_entry(entry)) { 220 /* 221 * We do not preserve soft-dirtiness. See 222 * copy_nonpresent_pte() for explanation. 223 */ 224 entry = make_readable_device_private_entry( 225 swp_offset(entry)); 226 newpte = swp_entry_to_pte(entry); 227 if (pte_swp_uffd_wp(oldpte)) 228 newpte = pte_swp_mkuffd_wp(newpte); 229 } else if (is_writable_device_exclusive_entry(entry)) { 230 entry = make_readable_device_exclusive_entry( 231 swp_offset(entry)); 232 newpte = swp_entry_to_pte(entry); 233 if (pte_swp_soft_dirty(oldpte)) 234 newpte = pte_swp_mksoft_dirty(newpte); 235 if (pte_swp_uffd_wp(oldpte)) 236 newpte = pte_swp_mkuffd_wp(newpte); 237 } else if (is_pte_marker_entry(entry)) { 238 /* 239 * Ignore error swap entries unconditionally, 240 * because any access should sigbus anyway. 241 */ 242 if (is_poisoned_swp_entry(entry)) 243 continue; 244 /* 245 * If this is uffd-wp pte marker and we'd like 246 * to unprotect it, drop it; the next page 247 * fault will trigger without uffd trapping. 248 */ 249 if (uffd_wp_resolve) { 250 pte_clear(vma->vm_mm, addr, pte); 251 pages++; 252 } 253 continue; 254 } else { 255 newpte = oldpte; 256 } 257 258 if (uffd_wp) 259 newpte = pte_swp_mkuffd_wp(newpte); 260 else if (uffd_wp_resolve) 261 newpte = pte_swp_clear_uffd_wp(newpte); 262 263 if (!pte_same(oldpte, newpte)) { 264 set_pte_at(vma->vm_mm, addr, pte, newpte); 265 pages++; 266 } 267 } else { 268 /* It must be an none page, or what else?.. */ 269 WARN_ON_ONCE(!pte_none(oldpte)); 270 271 /* 272 * Nobody plays with any none ptes besides 273 * userfaultfd when applying the protections. 274 */ 275 if (likely(!uffd_wp)) 276 continue; 277 278 if (userfaultfd_wp_use_markers(vma)) { 279 /* 280 * For file-backed mem, we need to be able to 281 * wr-protect a none pte, because even if the 282 * pte is none, the page/swap cache could 283 * exist. Doing that by install a marker. 284 */ 285 set_pte_at(vma->vm_mm, addr, pte, 286 make_pte_marker(PTE_MARKER_UFFD_WP)); 287 pages++; 288 } 289 } 290 } while (pte++, addr += PAGE_SIZE, addr != end); 291 arch_leave_lazy_mmu_mode(); 292 pte_unmap_unlock(pte - 1, ptl); 293 294 return pages; 295 } 296 297 /* 298 * Return true if we want to split THPs into PTE mappings in change 299 * protection procedure, false otherwise. 300 */ 301 static inline bool 302 pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags) 303 { 304 /* 305 * pte markers only resides in pte level, if we need pte markers, 306 * we need to split. We cannot wr-protect shmem thp because file 307 * thp is handled differently when split by erasing the pmd so far. 308 */ 309 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma); 310 } 311 312 /* 313 * Return true if we want to populate pgtables in change protection 314 * procedure, false otherwise 315 */ 316 static inline bool 317 pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags) 318 { 319 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */ 320 if (!(cp_flags & MM_CP_UFFD_WP)) 321 return false; 322 323 /* Populate if the userfaultfd mode requires pte markers */ 324 return userfaultfd_wp_use_markers(vma); 325 } 326 327 /* 328 * Populate the pgtable underneath for whatever reason if requested. 329 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable 330 * allocation failures during page faults by kicking OOM and returning 331 * error. 332 */ 333 #define change_pmd_prepare(vma, pmd, cp_flags) \ 334 ({ \ 335 long err = 0; \ 336 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 337 if (pte_alloc(vma->vm_mm, pmd)) \ 338 err = -ENOMEM; \ 339 } \ 340 err; \ 341 }) 342 343 /* 344 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to 345 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, 346 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. 347 */ 348 #define change_prepare(vma, high, low, addr, cp_flags) \ 349 ({ \ 350 long err = 0; \ 351 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 352 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ 353 if (p == NULL) \ 354 err = -ENOMEM; \ 355 } \ 356 err; \ 357 }) 358 359 static inline long change_pmd_range(struct mmu_gather *tlb, 360 struct vm_area_struct *vma, pud_t *pud, unsigned long addr, 361 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 362 { 363 pmd_t *pmd; 364 unsigned long next; 365 long pages = 0; 366 unsigned long nr_huge_updates = 0; 367 struct mmu_notifier_range range; 368 369 range.start = 0; 370 371 pmd = pmd_offset(pud, addr); 372 do { 373 long ret; 374 pmd_t _pmd; 375 again: 376 next = pmd_addr_end(addr, end); 377 378 ret = change_pmd_prepare(vma, pmd, cp_flags); 379 if (ret) { 380 pages = ret; 381 break; 382 } 383 384 if (pmd_none(*pmd)) 385 goto next; 386 387 /* invoke the mmu notifier if the pmd is populated */ 388 if (!range.start) { 389 mmu_notifier_range_init(&range, 390 MMU_NOTIFY_PROTECTION_VMA, 0, 391 vma->vm_mm, addr, end); 392 mmu_notifier_invalidate_range_start(&range); 393 } 394 395 _pmd = pmdp_get_lockless(pmd); 396 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) { 397 if ((next - addr != HPAGE_PMD_SIZE) || 398 pgtable_split_needed(vma, cp_flags)) { 399 __split_huge_pmd(vma, pmd, addr, false, NULL); 400 /* 401 * For file-backed, the pmd could have been 402 * cleared; make sure pmd populated if 403 * necessary, then fall-through to pte level. 404 */ 405 ret = change_pmd_prepare(vma, pmd, cp_flags); 406 if (ret) { 407 pages = ret; 408 break; 409 } 410 } else { 411 ret = change_huge_pmd(tlb, vma, pmd, 412 addr, newprot, cp_flags); 413 if (ret) { 414 if (ret == HPAGE_PMD_NR) { 415 pages += HPAGE_PMD_NR; 416 nr_huge_updates++; 417 } 418 419 /* huge pmd was handled */ 420 goto next; 421 } 422 } 423 /* fall through, the trans huge pmd just split */ 424 } 425 426 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, 427 cp_flags); 428 if (ret < 0) 429 goto again; 430 pages += ret; 431 next: 432 cond_resched(); 433 } while (pmd++, addr = next, addr != end); 434 435 if (range.start) 436 mmu_notifier_invalidate_range_end(&range); 437 438 if (nr_huge_updates) 439 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 440 return pages; 441 } 442 443 static inline long change_pud_range(struct mmu_gather *tlb, 444 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 445 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 446 { 447 pud_t *pud; 448 unsigned long next; 449 long pages = 0, ret; 450 451 pud = pud_offset(p4d, addr); 452 do { 453 next = pud_addr_end(addr, end); 454 ret = change_prepare(vma, pud, pmd, addr, cp_flags); 455 if (ret) 456 return ret; 457 if (pud_none_or_clear_bad(pud)) 458 continue; 459 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot, 460 cp_flags); 461 } while (pud++, addr = next, addr != end); 462 463 return pages; 464 } 465 466 static inline long change_p4d_range(struct mmu_gather *tlb, 467 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 468 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 469 { 470 p4d_t *p4d; 471 unsigned long next; 472 long pages = 0, ret; 473 474 p4d = p4d_offset(pgd, addr); 475 do { 476 next = p4d_addr_end(addr, end); 477 ret = change_prepare(vma, p4d, pud, addr, cp_flags); 478 if (ret) 479 return ret; 480 if (p4d_none_or_clear_bad(p4d)) 481 continue; 482 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 483 cp_flags); 484 } while (p4d++, addr = next, addr != end); 485 486 return pages; 487 } 488 489 static long change_protection_range(struct mmu_gather *tlb, 490 struct vm_area_struct *vma, unsigned long addr, 491 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 492 { 493 struct mm_struct *mm = vma->vm_mm; 494 pgd_t *pgd; 495 unsigned long next; 496 long pages = 0, ret; 497 498 BUG_ON(addr >= end); 499 pgd = pgd_offset(mm, addr); 500 tlb_start_vma(tlb, vma); 501 do { 502 next = pgd_addr_end(addr, end); 503 ret = change_prepare(vma, pgd, p4d, addr, cp_flags); 504 if (ret) { 505 pages = ret; 506 break; 507 } 508 if (pgd_none_or_clear_bad(pgd)) 509 continue; 510 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 511 cp_flags); 512 } while (pgd++, addr = next, addr != end); 513 514 tlb_end_vma(tlb, vma); 515 516 return pages; 517 } 518 519 long change_protection(struct mmu_gather *tlb, 520 struct vm_area_struct *vma, unsigned long start, 521 unsigned long end, unsigned long cp_flags) 522 { 523 pgprot_t newprot = vma->vm_page_prot; 524 long pages; 525 526 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 527 528 #ifdef CONFIG_NUMA_BALANCING 529 /* 530 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) 531 * are expected to reflect their requirements via VMA flags such that 532 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. 533 */ 534 if (cp_flags & MM_CP_PROT_NUMA) 535 newprot = PAGE_NONE; 536 #else 537 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); 538 #endif 539 540 if (is_vm_hugetlb_page(vma)) 541 pages = hugetlb_change_protection(vma, start, end, newprot, 542 cp_flags); 543 else 544 pages = change_protection_range(tlb, vma, start, end, newprot, 545 cp_flags); 546 547 return pages; 548 } 549 550 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 551 unsigned long next, struct mm_walk *walk) 552 { 553 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 554 *(pgprot_t *)(walk->private)) ? 555 0 : -EACCES; 556 } 557 558 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 559 unsigned long addr, unsigned long next, 560 struct mm_walk *walk) 561 { 562 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 563 *(pgprot_t *)(walk->private)) ? 564 0 : -EACCES; 565 } 566 567 static int prot_none_test(unsigned long addr, unsigned long next, 568 struct mm_walk *walk) 569 { 570 return 0; 571 } 572 573 static const struct mm_walk_ops prot_none_walk_ops = { 574 .pte_entry = prot_none_pte_entry, 575 .hugetlb_entry = prot_none_hugetlb_entry, 576 .test_walk = prot_none_test, 577 .walk_lock = PGWALK_WRLOCK, 578 }; 579 580 int 581 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, 582 struct vm_area_struct *vma, struct vm_area_struct **pprev, 583 unsigned long start, unsigned long end, unsigned long newflags) 584 { 585 struct mm_struct *mm = vma->vm_mm; 586 unsigned long oldflags = vma->vm_flags; 587 long nrpages = (end - start) >> PAGE_SHIFT; 588 unsigned int mm_cp_flags = 0; 589 unsigned long charged = 0; 590 int error; 591 592 if (newflags == oldflags) { 593 *pprev = vma; 594 return 0; 595 } 596 597 /* 598 * Do PROT_NONE PFN permission checks here when we can still 599 * bail out without undoing a lot of state. This is a rather 600 * uncommon case, so doesn't need to be very optimized. 601 */ 602 if (arch_has_pfn_modify_check() && 603 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 604 (newflags & VM_ACCESS_FLAGS) == 0) { 605 pgprot_t new_pgprot = vm_get_page_prot(newflags); 606 607 error = walk_page_range(current->mm, start, end, 608 &prot_none_walk_ops, &new_pgprot); 609 if (error) 610 return error; 611 } 612 613 /* 614 * If we make a private mapping writable we increase our commit; 615 * but (without finer accounting) cannot reduce our commit if we 616 * make it unwritable again except in the anonymous case where no 617 * anon_vma has yet to be assigned. 618 * 619 * hugetlb mapping were accounted for even if read-only so there is 620 * no need to account for them here. 621 */ 622 if (newflags & VM_WRITE) { 623 /* Check space limits when area turns into data. */ 624 if (!may_expand_vm(mm, newflags, nrpages) && 625 may_expand_vm(mm, oldflags, nrpages)) 626 return -ENOMEM; 627 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 628 VM_SHARED|VM_NORESERVE))) { 629 charged = nrpages; 630 if (security_vm_enough_memory_mm(mm, charged)) 631 return -ENOMEM; 632 newflags |= VM_ACCOUNT; 633 } 634 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) && 635 !vma->anon_vma) { 636 newflags &= ~VM_ACCOUNT; 637 } 638 639 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags); 640 if (IS_ERR(vma)) { 641 error = PTR_ERR(vma); 642 goto fail; 643 } 644 645 *pprev = vma; 646 647 /* 648 * vm_flags and vm_page_prot are protected by the mmap_lock 649 * held in write mode. 650 */ 651 vma_start_write(vma); 652 vm_flags_reset(vma, newflags); 653 if (vma_wants_manual_pte_write_upgrade(vma)) 654 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 655 vma_set_page_prot(vma); 656 657 change_protection(tlb, vma, start, end, mm_cp_flags); 658 659 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT)) 660 vm_unacct_memory(nrpages); 661 662 /* 663 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 664 * fault on access. 665 */ 666 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 667 (newflags & VM_WRITE)) { 668 populate_vma_page_range(vma, start, end, NULL); 669 } 670 671 vm_stat_account(mm, oldflags, -nrpages); 672 vm_stat_account(mm, newflags, nrpages); 673 perf_event_mmap(vma); 674 return 0; 675 676 fail: 677 vm_unacct_memory(charged); 678 return error; 679 } 680 681 /* 682 * pkey==-1 when doing a legacy mprotect() 683 */ 684 static int do_mprotect_pkey(unsigned long start, size_t len, 685 unsigned long prot, int pkey) 686 { 687 unsigned long nstart, end, tmp, reqprot; 688 struct vm_area_struct *vma, *prev; 689 int error; 690 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 691 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 692 (prot & PROT_READ); 693 struct mmu_gather tlb; 694 struct vma_iterator vmi; 695 696 start = untagged_addr(start); 697 698 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 699 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 700 return -EINVAL; 701 702 if (start & ~PAGE_MASK) 703 return -EINVAL; 704 if (!len) 705 return 0; 706 len = PAGE_ALIGN(len); 707 end = start + len; 708 if (end <= start) 709 return -ENOMEM; 710 if (!arch_validate_prot(prot, start)) 711 return -EINVAL; 712 713 reqprot = prot; 714 715 if (mmap_write_lock_killable(current->mm)) 716 return -EINTR; 717 718 /* 719 * If userspace did not allocate the pkey, do not let 720 * them use it here. 721 */ 722 error = -EINVAL; 723 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 724 goto out; 725 726 vma_iter_init(&vmi, current->mm, start); 727 vma = vma_find(&vmi, end); 728 error = -ENOMEM; 729 if (!vma) 730 goto out; 731 732 if (unlikely(grows & PROT_GROWSDOWN)) { 733 if (vma->vm_start >= end) 734 goto out; 735 start = vma->vm_start; 736 error = -EINVAL; 737 if (!(vma->vm_flags & VM_GROWSDOWN)) 738 goto out; 739 } else { 740 if (vma->vm_start > start) 741 goto out; 742 if (unlikely(grows & PROT_GROWSUP)) { 743 end = vma->vm_end; 744 error = -EINVAL; 745 if (!(vma->vm_flags & VM_GROWSUP)) 746 goto out; 747 } 748 } 749 750 /* 751 * checking if memory is sealed. 752 * can_modify_mm assumes we have acquired the lock on MM. 753 */ 754 if (unlikely(!can_modify_mm(current->mm, start, end))) { 755 error = -EPERM; 756 goto out; 757 } 758 759 prev = vma_prev(&vmi); 760 if (start > vma->vm_start) 761 prev = vma; 762 763 tlb_gather_mmu(&tlb, current->mm); 764 nstart = start; 765 tmp = vma->vm_start; 766 for_each_vma_range(vmi, vma, end) { 767 unsigned long mask_off_old_flags; 768 unsigned long newflags; 769 int new_vma_pkey; 770 771 if (vma->vm_start != tmp) { 772 error = -ENOMEM; 773 break; 774 } 775 776 /* Does the application expect PROT_READ to imply PROT_EXEC */ 777 if (rier && (vma->vm_flags & VM_MAYEXEC)) 778 prot |= PROT_EXEC; 779 780 /* 781 * Each mprotect() call explicitly passes r/w/x permissions. 782 * If a permission is not passed to mprotect(), it must be 783 * cleared from the VMA. 784 */ 785 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 786 787 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 788 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 789 newflags |= (vma->vm_flags & ~mask_off_old_flags); 790 791 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 792 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 793 error = -EACCES; 794 break; 795 } 796 797 if (map_deny_write_exec(vma, newflags)) { 798 error = -EACCES; 799 break; 800 } 801 802 /* Allow architectures to sanity-check the new flags */ 803 if (!arch_validate_flags(newflags)) { 804 error = -EINVAL; 805 break; 806 } 807 808 error = security_file_mprotect(vma, reqprot, prot); 809 if (error) 810 break; 811 812 tmp = vma->vm_end; 813 if (tmp > end) 814 tmp = end; 815 816 if (vma->vm_ops && vma->vm_ops->mprotect) { 817 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 818 if (error) 819 break; 820 } 821 822 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); 823 if (error) 824 break; 825 826 tmp = vma_iter_end(&vmi); 827 nstart = tmp; 828 prot = reqprot; 829 } 830 tlb_finish_mmu(&tlb); 831 832 if (!error && tmp < end) 833 error = -ENOMEM; 834 835 out: 836 mmap_write_unlock(current->mm); 837 return error; 838 } 839 840 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 841 unsigned long, prot) 842 { 843 return do_mprotect_pkey(start, len, prot, -1); 844 } 845 846 #ifdef CONFIG_ARCH_HAS_PKEYS 847 848 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 849 unsigned long, prot, int, pkey) 850 { 851 return do_mprotect_pkey(start, len, prot, pkey); 852 } 853 854 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 855 { 856 int pkey; 857 int ret; 858 859 /* No flags supported yet. */ 860 if (flags) 861 return -EINVAL; 862 /* check for unsupported init values */ 863 if (init_val & ~PKEY_ACCESS_MASK) 864 return -EINVAL; 865 866 mmap_write_lock(current->mm); 867 pkey = mm_pkey_alloc(current->mm); 868 869 ret = -ENOSPC; 870 if (pkey == -1) 871 goto out; 872 873 ret = arch_set_user_pkey_access(current, pkey, init_val); 874 if (ret) { 875 mm_pkey_free(current->mm, pkey); 876 goto out; 877 } 878 ret = pkey; 879 out: 880 mmap_write_unlock(current->mm); 881 return ret; 882 } 883 884 SYSCALL_DEFINE1(pkey_free, int, pkey) 885 { 886 int ret; 887 888 mmap_write_lock(current->mm); 889 ret = mm_pkey_free(current->mm, pkey); 890 mmap_write_unlock(current->mm); 891 892 /* 893 * We could provide warnings or errors if any VMA still 894 * has the pkey set here. 895 */ 896 return ret; 897 } 898 899 #endif /* CONFIG_ARCH_HAS_PKEYS */ 900