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