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