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. For example, we cannot wr-protect a file thp 306 * (e.g. 2M shmem) because file thp is handled differently when 307 * 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; 367 368 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 _pmd = pmdp_get_lockless(pmd); 385 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) { 386 if ((next - addr != HPAGE_PMD_SIZE) || 387 pgtable_split_needed(vma, cp_flags)) { 388 __split_huge_pmd(vma, pmd, addr, false, NULL); 389 /* 390 * For file-backed, the pmd could have been 391 * cleared; make sure pmd populated if 392 * necessary, then fall-through to pte level. 393 */ 394 ret = change_pmd_prepare(vma, pmd, cp_flags); 395 if (ret) { 396 pages = ret; 397 break; 398 } 399 } else { 400 ret = change_huge_pmd(tlb, vma, pmd, 401 addr, newprot, cp_flags); 402 if (ret) { 403 if (ret == HPAGE_PMD_NR) { 404 pages += HPAGE_PMD_NR; 405 nr_huge_updates++; 406 } 407 408 /* huge pmd was handled */ 409 goto next; 410 } 411 } 412 /* fall through, the trans huge pmd just split */ 413 } 414 415 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, 416 cp_flags); 417 if (ret < 0) 418 goto again; 419 pages += ret; 420 next: 421 cond_resched(); 422 } while (pmd++, addr = next, addr != end); 423 424 if (nr_huge_updates) 425 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 426 return pages; 427 } 428 429 static inline long change_pud_range(struct mmu_gather *tlb, 430 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 431 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 432 { 433 struct mmu_notifier_range range; 434 pud_t *pudp, pud; 435 unsigned long next; 436 long pages = 0, ret; 437 438 range.start = 0; 439 440 pudp = pud_offset(p4d, addr); 441 do { 442 again: 443 next = pud_addr_end(addr, end); 444 ret = change_prepare(vma, pudp, pmd, addr, cp_flags); 445 if (ret) { 446 pages = ret; 447 break; 448 } 449 450 pud = READ_ONCE(*pudp); 451 if (pud_none(pud)) 452 continue; 453 454 if (!range.start) { 455 mmu_notifier_range_init(&range, 456 MMU_NOTIFY_PROTECTION_VMA, 0, 457 vma->vm_mm, addr, end); 458 mmu_notifier_invalidate_range_start(&range); 459 } 460 461 if (pud_leaf(pud)) { 462 if ((next - addr != PUD_SIZE) || 463 pgtable_split_needed(vma, cp_flags)) { 464 __split_huge_pud(vma, pudp, addr); 465 goto again; 466 } else { 467 ret = change_huge_pud(tlb, vma, pudp, 468 addr, newprot, cp_flags); 469 if (ret == 0) 470 goto again; 471 /* huge pud was handled */ 472 if (ret == HPAGE_PUD_NR) 473 pages += HPAGE_PUD_NR; 474 continue; 475 } 476 } 477 478 pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot, 479 cp_flags); 480 } while (pudp++, addr = next, addr != end); 481 482 if (range.start) 483 mmu_notifier_invalidate_range_end(&range); 484 485 return pages; 486 } 487 488 static inline long change_p4d_range(struct mmu_gather *tlb, 489 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 490 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 491 { 492 p4d_t *p4d; 493 unsigned long next; 494 long pages = 0, ret; 495 496 p4d = p4d_offset(pgd, addr); 497 do { 498 next = p4d_addr_end(addr, end); 499 ret = change_prepare(vma, p4d, pud, addr, cp_flags); 500 if (ret) 501 return ret; 502 if (p4d_none_or_clear_bad(p4d)) 503 continue; 504 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 505 cp_flags); 506 } while (p4d++, addr = next, addr != end); 507 508 return pages; 509 } 510 511 static long change_protection_range(struct mmu_gather *tlb, 512 struct vm_area_struct *vma, unsigned long addr, 513 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 514 { 515 struct mm_struct *mm = vma->vm_mm; 516 pgd_t *pgd; 517 unsigned long next; 518 long pages = 0, ret; 519 520 BUG_ON(addr >= end); 521 pgd = pgd_offset(mm, addr); 522 tlb_start_vma(tlb, vma); 523 do { 524 next = pgd_addr_end(addr, end); 525 ret = change_prepare(vma, pgd, p4d, addr, cp_flags); 526 if (ret) { 527 pages = ret; 528 break; 529 } 530 if (pgd_none_or_clear_bad(pgd)) 531 continue; 532 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 533 cp_flags); 534 } while (pgd++, addr = next, addr != end); 535 536 tlb_end_vma(tlb, vma); 537 538 return pages; 539 } 540 541 long change_protection(struct mmu_gather *tlb, 542 struct vm_area_struct *vma, unsigned long start, 543 unsigned long end, unsigned long cp_flags) 544 { 545 pgprot_t newprot = vma->vm_page_prot; 546 long pages; 547 548 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 549 550 #ifdef CONFIG_NUMA_BALANCING 551 /* 552 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) 553 * are expected to reflect their requirements via VMA flags such that 554 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. 555 */ 556 if (cp_flags & MM_CP_PROT_NUMA) 557 newprot = PAGE_NONE; 558 #else 559 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); 560 #endif 561 562 if (is_vm_hugetlb_page(vma)) 563 pages = hugetlb_change_protection(vma, start, end, newprot, 564 cp_flags); 565 else 566 pages = change_protection_range(tlb, vma, start, end, newprot, 567 cp_flags); 568 569 return pages; 570 } 571 572 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 573 unsigned long next, struct mm_walk *walk) 574 { 575 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 576 *(pgprot_t *)(walk->private)) ? 577 0 : -EACCES; 578 } 579 580 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 581 unsigned long addr, unsigned long next, 582 struct mm_walk *walk) 583 { 584 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 585 *(pgprot_t *)(walk->private)) ? 586 0 : -EACCES; 587 } 588 589 static int prot_none_test(unsigned long addr, unsigned long next, 590 struct mm_walk *walk) 591 { 592 return 0; 593 } 594 595 static const struct mm_walk_ops prot_none_walk_ops = { 596 .pte_entry = prot_none_pte_entry, 597 .hugetlb_entry = prot_none_hugetlb_entry, 598 .test_walk = prot_none_test, 599 .walk_lock = PGWALK_WRLOCK, 600 }; 601 602 int 603 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, 604 struct vm_area_struct *vma, struct vm_area_struct **pprev, 605 unsigned long start, unsigned long end, unsigned long newflags) 606 { 607 struct mm_struct *mm = vma->vm_mm; 608 unsigned long oldflags = vma->vm_flags; 609 long nrpages = (end - start) >> PAGE_SHIFT; 610 unsigned int mm_cp_flags = 0; 611 unsigned long charged = 0; 612 int error; 613 614 if (!can_modify_vma(vma)) 615 return -EPERM; 616 617 if (newflags == oldflags) { 618 *pprev = vma; 619 return 0; 620 } 621 622 /* 623 * Do PROT_NONE PFN permission checks here when we can still 624 * bail out without undoing a lot of state. This is a rather 625 * uncommon case, so doesn't need to be very optimized. 626 */ 627 if (arch_has_pfn_modify_check() && 628 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 629 (newflags & VM_ACCESS_FLAGS) == 0) { 630 pgprot_t new_pgprot = vm_get_page_prot(newflags); 631 632 error = walk_page_range(current->mm, start, end, 633 &prot_none_walk_ops, &new_pgprot); 634 if (error) 635 return error; 636 } 637 638 /* 639 * If we make a private mapping writable we increase our commit; 640 * but (without finer accounting) cannot reduce our commit if we 641 * make it unwritable again except in the anonymous case where no 642 * anon_vma has yet to be assigned. 643 * 644 * hugetlb mapping were accounted for even if read-only so there is 645 * no need to account for them here. 646 */ 647 if (newflags & VM_WRITE) { 648 /* Check space limits when area turns into data. */ 649 if (!may_expand_vm(mm, newflags, nrpages) && 650 may_expand_vm(mm, oldflags, nrpages)) 651 return -ENOMEM; 652 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 653 VM_SHARED|VM_NORESERVE))) { 654 charged = nrpages; 655 if (security_vm_enough_memory_mm(mm, charged)) 656 return -ENOMEM; 657 newflags |= VM_ACCOUNT; 658 } 659 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) && 660 !vma->anon_vma) { 661 newflags &= ~VM_ACCOUNT; 662 } 663 664 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags); 665 if (IS_ERR(vma)) { 666 error = PTR_ERR(vma); 667 goto fail; 668 } 669 670 *pprev = vma; 671 672 /* 673 * vm_flags and vm_page_prot are protected by the mmap_lock 674 * held in write mode. 675 */ 676 vma_start_write(vma); 677 vm_flags_reset(vma, newflags); 678 if (vma_wants_manual_pte_write_upgrade(vma)) 679 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 680 vma_set_page_prot(vma); 681 682 change_protection(tlb, vma, start, end, mm_cp_flags); 683 684 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT)) 685 vm_unacct_memory(nrpages); 686 687 /* 688 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 689 * fault on access. 690 */ 691 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 692 (newflags & VM_WRITE)) { 693 populate_vma_page_range(vma, start, end, NULL); 694 } 695 696 vm_stat_account(mm, oldflags, -nrpages); 697 vm_stat_account(mm, newflags, nrpages); 698 perf_event_mmap(vma); 699 return 0; 700 701 fail: 702 vm_unacct_memory(charged); 703 return error; 704 } 705 706 /* 707 * pkey==-1 when doing a legacy mprotect() 708 */ 709 static int do_mprotect_pkey(unsigned long start, size_t len, 710 unsigned long prot, int pkey) 711 { 712 unsigned long nstart, end, tmp, reqprot; 713 struct vm_area_struct *vma, *prev; 714 int error; 715 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 716 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 717 (prot & PROT_READ); 718 struct mmu_gather tlb; 719 struct vma_iterator vmi; 720 721 start = untagged_addr(start); 722 723 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 724 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 725 return -EINVAL; 726 727 if (start & ~PAGE_MASK) 728 return -EINVAL; 729 if (!len) 730 return 0; 731 len = PAGE_ALIGN(len); 732 end = start + len; 733 if (end <= start) 734 return -ENOMEM; 735 if (!arch_validate_prot(prot, start)) 736 return -EINVAL; 737 738 reqprot = prot; 739 740 if (mmap_write_lock_killable(current->mm)) 741 return -EINTR; 742 743 /* 744 * If userspace did not allocate the pkey, do not let 745 * them use it here. 746 */ 747 error = -EINVAL; 748 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 749 goto out; 750 751 vma_iter_init(&vmi, current->mm, start); 752 vma = vma_find(&vmi, end); 753 error = -ENOMEM; 754 if (!vma) 755 goto out; 756 757 if (unlikely(grows & PROT_GROWSDOWN)) { 758 if (vma->vm_start >= end) 759 goto out; 760 start = vma->vm_start; 761 error = -EINVAL; 762 if (!(vma->vm_flags & VM_GROWSDOWN)) 763 goto out; 764 } else { 765 if (vma->vm_start > start) 766 goto out; 767 if (unlikely(grows & PROT_GROWSUP)) { 768 end = vma->vm_end; 769 error = -EINVAL; 770 if (!(vma->vm_flags & VM_GROWSUP)) 771 goto out; 772 } 773 } 774 775 prev = vma_prev(&vmi); 776 if (start > vma->vm_start) 777 prev = vma; 778 779 tlb_gather_mmu(&tlb, current->mm); 780 nstart = start; 781 tmp = vma->vm_start; 782 for_each_vma_range(vmi, vma, end) { 783 unsigned long mask_off_old_flags; 784 unsigned long newflags; 785 int new_vma_pkey; 786 787 if (vma->vm_start != tmp) { 788 error = -ENOMEM; 789 break; 790 } 791 792 /* Does the application expect PROT_READ to imply PROT_EXEC */ 793 if (rier && (vma->vm_flags & VM_MAYEXEC)) 794 prot |= PROT_EXEC; 795 796 /* 797 * Each mprotect() call explicitly passes r/w/x permissions. 798 * If a permission is not passed to mprotect(), it must be 799 * cleared from the VMA. 800 */ 801 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 802 803 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 804 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 805 newflags |= (vma->vm_flags & ~mask_off_old_flags); 806 807 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 808 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 809 error = -EACCES; 810 break; 811 } 812 813 if (map_deny_write_exec(vma, newflags)) { 814 error = -EACCES; 815 break; 816 } 817 818 /* Allow architectures to sanity-check the new flags */ 819 if (!arch_validate_flags(newflags)) { 820 error = -EINVAL; 821 break; 822 } 823 824 error = security_file_mprotect(vma, reqprot, prot); 825 if (error) 826 break; 827 828 tmp = vma->vm_end; 829 if (tmp > end) 830 tmp = end; 831 832 if (vma->vm_ops && vma->vm_ops->mprotect) { 833 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 834 if (error) 835 break; 836 } 837 838 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); 839 if (error) 840 break; 841 842 tmp = vma_iter_end(&vmi); 843 nstart = tmp; 844 prot = reqprot; 845 } 846 tlb_finish_mmu(&tlb); 847 848 if (!error && tmp < end) 849 error = -ENOMEM; 850 851 out: 852 mmap_write_unlock(current->mm); 853 return error; 854 } 855 856 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 857 unsigned long, prot) 858 { 859 return do_mprotect_pkey(start, len, prot, -1); 860 } 861 862 #ifdef CONFIG_ARCH_HAS_PKEYS 863 864 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 865 unsigned long, prot, int, pkey) 866 { 867 return do_mprotect_pkey(start, len, prot, pkey); 868 } 869 870 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 871 { 872 int pkey; 873 int ret; 874 875 /* No flags supported yet. */ 876 if (flags) 877 return -EINVAL; 878 /* check for unsupported init values */ 879 if (init_val & ~PKEY_ACCESS_MASK) 880 return -EINVAL; 881 882 mmap_write_lock(current->mm); 883 pkey = mm_pkey_alloc(current->mm); 884 885 ret = -ENOSPC; 886 if (pkey == -1) 887 goto out; 888 889 ret = arch_set_user_pkey_access(current, pkey, init_val); 890 if (ret) { 891 mm_pkey_free(current->mm, pkey); 892 goto out; 893 } 894 ret = pkey; 895 out: 896 mmap_write_unlock(current->mm); 897 return ret; 898 } 899 900 SYSCALL_DEFINE1(pkey_free, int, pkey) 901 { 902 int ret; 903 904 mmap_write_lock(current->mm); 905 ret = mm_pkey_free(current->mm, pkey); 906 mmap_write_unlock(current->mm); 907 908 /* 909 * We could provide warnings or errors if any VMA still 910 * has the pkey set here. 911 */ 912 return ret; 913 } 914 915 #endif /* CONFIG_ARCH_HAS_PKEYS */ 916