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/sigsegv 240 * anyway. 241 */ 242 if (is_poisoned_swp_entry(entry) || 243 is_guard_swp_entry(entry)) 244 continue; 245 /* 246 * If this is uffd-wp pte marker and we'd like 247 * to unprotect it, drop it; the next page 248 * fault will trigger without uffd trapping. 249 */ 250 if (uffd_wp_resolve) { 251 pte_clear(vma->vm_mm, addr, pte); 252 pages++; 253 } 254 continue; 255 } else { 256 newpte = oldpte; 257 } 258 259 if (uffd_wp) 260 newpte = pte_swp_mkuffd_wp(newpte); 261 else if (uffd_wp_resolve) 262 newpte = pte_swp_clear_uffd_wp(newpte); 263 264 if (!pte_same(oldpte, newpte)) { 265 set_pte_at(vma->vm_mm, addr, pte, newpte); 266 pages++; 267 } 268 } else { 269 /* It must be an none page, or what else?.. */ 270 WARN_ON_ONCE(!pte_none(oldpte)); 271 272 /* 273 * Nobody plays with any none ptes besides 274 * userfaultfd when applying the protections. 275 */ 276 if (likely(!uffd_wp)) 277 continue; 278 279 if (userfaultfd_wp_use_markers(vma)) { 280 /* 281 * For file-backed mem, we need to be able to 282 * wr-protect a none pte, because even if the 283 * pte is none, the page/swap cache could 284 * exist. Doing that by install a marker. 285 */ 286 set_pte_at(vma->vm_mm, addr, pte, 287 make_pte_marker(PTE_MARKER_UFFD_WP)); 288 pages++; 289 } 290 } 291 } while (pte++, addr += PAGE_SIZE, addr != end); 292 arch_leave_lazy_mmu_mode(); 293 pte_unmap_unlock(pte - 1, ptl); 294 295 return pages; 296 } 297 298 /* 299 * Return true if we want to split THPs into PTE mappings in change 300 * protection procedure, false otherwise. 301 */ 302 static inline bool 303 pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags) 304 { 305 /* 306 * pte markers only resides in pte level, if we need pte markers, 307 * we need to split. For example, we cannot wr-protect a file thp 308 * (e.g. 2M shmem) because file thp is handled differently when 309 * split by erasing the pmd so far. 310 */ 311 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma); 312 } 313 314 /* 315 * Return true if we want to populate pgtables in change protection 316 * procedure, false otherwise 317 */ 318 static inline bool 319 pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags) 320 { 321 /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */ 322 if (!(cp_flags & MM_CP_UFFD_WP)) 323 return false; 324 325 /* Populate if the userfaultfd mode requires pte markers */ 326 return userfaultfd_wp_use_markers(vma); 327 } 328 329 /* 330 * Populate the pgtable underneath for whatever reason if requested. 331 * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable 332 * allocation failures during page faults by kicking OOM and returning 333 * error. 334 */ 335 #define change_pmd_prepare(vma, pmd, cp_flags) \ 336 ({ \ 337 long err = 0; \ 338 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 339 if (pte_alloc(vma->vm_mm, pmd)) \ 340 err = -ENOMEM; \ 341 } \ 342 err; \ 343 }) 344 345 /* 346 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to 347 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, 348 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. 349 */ 350 #define change_prepare(vma, high, low, addr, cp_flags) \ 351 ({ \ 352 long err = 0; \ 353 if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \ 354 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ 355 if (p == NULL) \ 356 err = -ENOMEM; \ 357 } \ 358 err; \ 359 }) 360 361 static inline long change_pmd_range(struct mmu_gather *tlb, 362 struct vm_area_struct *vma, pud_t *pud, unsigned long addr, 363 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 364 { 365 pmd_t *pmd; 366 unsigned long next; 367 long pages = 0; 368 unsigned long nr_huge_updates = 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 _pmd = pmdp_get_lockless(pmd); 387 if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) { 388 if ((next - addr != HPAGE_PMD_SIZE) || 389 pgtable_split_needed(vma, cp_flags)) { 390 __split_huge_pmd(vma, pmd, addr, false, NULL); 391 /* 392 * For file-backed, the pmd could have been 393 * cleared; make sure pmd populated if 394 * necessary, then fall-through to pte level. 395 */ 396 ret = change_pmd_prepare(vma, pmd, cp_flags); 397 if (ret) { 398 pages = ret; 399 break; 400 } 401 } else { 402 ret = change_huge_pmd(tlb, vma, pmd, 403 addr, newprot, cp_flags); 404 if (ret) { 405 if (ret == HPAGE_PMD_NR) { 406 pages += HPAGE_PMD_NR; 407 nr_huge_updates++; 408 } 409 410 /* huge pmd was handled */ 411 goto next; 412 } 413 } 414 /* fall through, the trans huge pmd just split */ 415 } 416 417 ret = change_pte_range(tlb, vma, pmd, addr, next, newprot, 418 cp_flags); 419 if (ret < 0) 420 goto again; 421 pages += ret; 422 next: 423 cond_resched(); 424 } while (pmd++, addr = next, addr != end); 425 426 if (nr_huge_updates) 427 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 428 return pages; 429 } 430 431 static inline long change_pud_range(struct mmu_gather *tlb, 432 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 433 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 434 { 435 struct mmu_notifier_range range; 436 pud_t *pudp, pud; 437 unsigned long next; 438 long pages = 0, ret; 439 440 range.start = 0; 441 442 pudp = pud_offset(p4d, addr); 443 do { 444 again: 445 next = pud_addr_end(addr, end); 446 ret = change_prepare(vma, pudp, pmd, addr, cp_flags); 447 if (ret) { 448 pages = ret; 449 break; 450 } 451 452 pud = READ_ONCE(*pudp); 453 if (pud_none(pud)) 454 continue; 455 456 if (!range.start) { 457 mmu_notifier_range_init(&range, 458 MMU_NOTIFY_PROTECTION_VMA, 0, 459 vma->vm_mm, addr, end); 460 mmu_notifier_invalidate_range_start(&range); 461 } 462 463 if (pud_leaf(pud)) { 464 if ((next - addr != PUD_SIZE) || 465 pgtable_split_needed(vma, cp_flags)) { 466 __split_huge_pud(vma, pudp, addr); 467 goto again; 468 } else { 469 ret = change_huge_pud(tlb, vma, pudp, 470 addr, newprot, cp_flags); 471 if (ret == 0) 472 goto again; 473 /* huge pud was handled */ 474 if (ret == HPAGE_PUD_NR) 475 pages += HPAGE_PUD_NR; 476 continue; 477 } 478 } 479 480 pages += change_pmd_range(tlb, vma, pudp, addr, next, newprot, 481 cp_flags); 482 } while (pudp++, addr = next, addr != end); 483 484 if (range.start) 485 mmu_notifier_invalidate_range_end(&range); 486 487 return pages; 488 } 489 490 static inline long change_p4d_range(struct mmu_gather *tlb, 491 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 492 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 493 { 494 p4d_t *p4d; 495 unsigned long next; 496 long pages = 0, ret; 497 498 p4d = p4d_offset(pgd, addr); 499 do { 500 next = p4d_addr_end(addr, end); 501 ret = change_prepare(vma, p4d, pud, addr, cp_flags); 502 if (ret) 503 return ret; 504 if (p4d_none_or_clear_bad(p4d)) 505 continue; 506 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 507 cp_flags); 508 } while (p4d++, addr = next, addr != end); 509 510 return pages; 511 } 512 513 static long change_protection_range(struct mmu_gather *tlb, 514 struct vm_area_struct *vma, unsigned long addr, 515 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 516 { 517 struct mm_struct *mm = vma->vm_mm; 518 pgd_t *pgd; 519 unsigned long next; 520 long pages = 0, ret; 521 522 BUG_ON(addr >= end); 523 pgd = pgd_offset(mm, addr); 524 tlb_start_vma(tlb, vma); 525 do { 526 next = pgd_addr_end(addr, end); 527 ret = change_prepare(vma, pgd, p4d, addr, cp_flags); 528 if (ret) { 529 pages = ret; 530 break; 531 } 532 if (pgd_none_or_clear_bad(pgd)) 533 continue; 534 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 535 cp_flags); 536 } while (pgd++, addr = next, addr != end); 537 538 tlb_end_vma(tlb, vma); 539 540 return pages; 541 } 542 543 long change_protection(struct mmu_gather *tlb, 544 struct vm_area_struct *vma, unsigned long start, 545 unsigned long end, unsigned long cp_flags) 546 { 547 pgprot_t newprot = vma->vm_page_prot; 548 long pages; 549 550 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 551 552 #ifdef CONFIG_NUMA_BALANCING 553 /* 554 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) 555 * are expected to reflect their requirements via VMA flags such that 556 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. 557 */ 558 if (cp_flags & MM_CP_PROT_NUMA) 559 newprot = PAGE_NONE; 560 #else 561 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); 562 #endif 563 564 if (is_vm_hugetlb_page(vma)) 565 pages = hugetlb_change_protection(vma, start, end, newprot, 566 cp_flags); 567 else 568 pages = change_protection_range(tlb, vma, start, end, newprot, 569 cp_flags); 570 571 return pages; 572 } 573 574 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 575 unsigned long next, struct mm_walk *walk) 576 { 577 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 578 *(pgprot_t *)(walk->private)) ? 579 0 : -EACCES; 580 } 581 582 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 583 unsigned long addr, unsigned long next, 584 struct mm_walk *walk) 585 { 586 return pfn_modify_allowed(pte_pfn(ptep_get(pte)), 587 *(pgprot_t *)(walk->private)) ? 588 0 : -EACCES; 589 } 590 591 static int prot_none_test(unsigned long addr, unsigned long next, 592 struct mm_walk *walk) 593 { 594 return 0; 595 } 596 597 static const struct mm_walk_ops prot_none_walk_ops = { 598 .pte_entry = prot_none_pte_entry, 599 .hugetlb_entry = prot_none_hugetlb_entry, 600 .test_walk = prot_none_test, 601 .walk_lock = PGWALK_WRLOCK, 602 }; 603 604 int 605 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, 606 struct vm_area_struct *vma, struct vm_area_struct **pprev, 607 unsigned long start, unsigned long end, unsigned long newflags) 608 { 609 struct mm_struct *mm = vma->vm_mm; 610 unsigned long oldflags = vma->vm_flags; 611 long nrpages = (end - start) >> PAGE_SHIFT; 612 unsigned int mm_cp_flags = 0; 613 unsigned long charged = 0; 614 int error; 615 616 if (!can_modify_vma(vma)) 617 return -EPERM; 618 619 if (newflags == oldflags) { 620 *pprev = vma; 621 return 0; 622 } 623 624 /* 625 * Do PROT_NONE PFN permission checks here when we can still 626 * bail out without undoing a lot of state. This is a rather 627 * uncommon case, so doesn't need to be very optimized. 628 */ 629 if (arch_has_pfn_modify_check() && 630 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 631 (newflags & VM_ACCESS_FLAGS) == 0) { 632 pgprot_t new_pgprot = vm_get_page_prot(newflags); 633 634 error = walk_page_range(current->mm, start, end, 635 &prot_none_walk_ops, &new_pgprot); 636 if (error) 637 return error; 638 } 639 640 /* 641 * If we make a private mapping writable we increase our commit; 642 * but (without finer accounting) cannot reduce our commit if we 643 * make it unwritable again except in the anonymous case where no 644 * anon_vma has yet to be assigned. 645 * 646 * hugetlb mapping were accounted for even if read-only so there is 647 * no need to account for them here. 648 */ 649 if (newflags & VM_WRITE) { 650 /* Check space limits when area turns into data. */ 651 if (!may_expand_vm(mm, newflags, nrpages) && 652 may_expand_vm(mm, oldflags, nrpages)) 653 return -ENOMEM; 654 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 655 VM_SHARED|VM_NORESERVE))) { 656 charged = nrpages; 657 if (security_vm_enough_memory_mm(mm, charged)) 658 return -ENOMEM; 659 newflags |= VM_ACCOUNT; 660 } 661 } else if ((oldflags & VM_ACCOUNT) && vma_is_anonymous(vma) && 662 !vma->anon_vma) { 663 newflags &= ~VM_ACCOUNT; 664 } 665 666 vma = vma_modify_flags(vmi, *pprev, vma, start, end, newflags); 667 if (IS_ERR(vma)) { 668 error = PTR_ERR(vma); 669 goto fail; 670 } 671 672 *pprev = vma; 673 674 /* 675 * vm_flags and vm_page_prot are protected by the mmap_lock 676 * held in write mode. 677 */ 678 vma_start_write(vma); 679 vm_flags_reset(vma, newflags); 680 if (vma_wants_manual_pte_write_upgrade(vma)) 681 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 682 vma_set_page_prot(vma); 683 684 change_protection(tlb, vma, start, end, mm_cp_flags); 685 686 if ((oldflags & VM_ACCOUNT) && !(newflags & VM_ACCOUNT)) 687 vm_unacct_memory(nrpages); 688 689 /* 690 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 691 * fault on access. 692 */ 693 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 694 (newflags & VM_WRITE)) { 695 populate_vma_page_range(vma, start, end, NULL); 696 } 697 698 vm_stat_account(mm, oldflags, -nrpages); 699 vm_stat_account(mm, newflags, nrpages); 700 perf_event_mmap(vma); 701 return 0; 702 703 fail: 704 vm_unacct_memory(charged); 705 return error; 706 } 707 708 /* 709 * pkey==-1 when doing a legacy mprotect() 710 */ 711 static int do_mprotect_pkey(unsigned long start, size_t len, 712 unsigned long prot, int pkey) 713 { 714 unsigned long nstart, end, tmp, reqprot; 715 struct vm_area_struct *vma, *prev; 716 int error; 717 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 718 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 719 (prot & PROT_READ); 720 struct mmu_gather tlb; 721 struct vma_iterator vmi; 722 723 start = untagged_addr(start); 724 725 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 726 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 727 return -EINVAL; 728 729 if (start & ~PAGE_MASK) 730 return -EINVAL; 731 if (!len) 732 return 0; 733 len = PAGE_ALIGN(len); 734 end = start + len; 735 if (end <= start) 736 return -ENOMEM; 737 if (!arch_validate_prot(prot, start)) 738 return -EINVAL; 739 740 reqprot = prot; 741 742 if (mmap_write_lock_killable(current->mm)) 743 return -EINTR; 744 745 /* 746 * If userspace did not allocate the pkey, do not let 747 * them use it here. 748 */ 749 error = -EINVAL; 750 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 751 goto out; 752 753 vma_iter_init(&vmi, current->mm, start); 754 vma = vma_find(&vmi, end); 755 error = -ENOMEM; 756 if (!vma) 757 goto out; 758 759 if (unlikely(grows & PROT_GROWSDOWN)) { 760 if (vma->vm_start >= end) 761 goto out; 762 start = vma->vm_start; 763 error = -EINVAL; 764 if (!(vma->vm_flags & VM_GROWSDOWN)) 765 goto out; 766 } else { 767 if (vma->vm_start > start) 768 goto out; 769 if (unlikely(grows & PROT_GROWSUP)) { 770 end = vma->vm_end; 771 error = -EINVAL; 772 if (!(vma->vm_flags & VM_GROWSUP)) 773 goto out; 774 } 775 } 776 777 prev = vma_prev(&vmi); 778 if (start > vma->vm_start) 779 prev = vma; 780 781 tlb_gather_mmu(&tlb, current->mm); 782 nstart = start; 783 tmp = vma->vm_start; 784 for_each_vma_range(vmi, vma, end) { 785 unsigned long mask_off_old_flags; 786 unsigned long newflags; 787 int new_vma_pkey; 788 789 if (vma->vm_start != tmp) { 790 error = -ENOMEM; 791 break; 792 } 793 794 /* Does the application expect PROT_READ to imply PROT_EXEC */ 795 if (rier && (vma->vm_flags & VM_MAYEXEC)) 796 prot |= PROT_EXEC; 797 798 /* 799 * Each mprotect() call explicitly passes r/w/x permissions. 800 * If a permission is not passed to mprotect(), it must be 801 * cleared from the VMA. 802 */ 803 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 804 805 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 806 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 807 newflags |= (vma->vm_flags & ~mask_off_old_flags); 808 809 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 810 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 811 error = -EACCES; 812 break; 813 } 814 815 if (map_deny_write_exec(vma->vm_flags, newflags)) { 816 error = -EACCES; 817 break; 818 } 819 820 /* Allow architectures to sanity-check the new flags */ 821 if (!arch_validate_flags(newflags)) { 822 error = -EINVAL; 823 break; 824 } 825 826 error = security_file_mprotect(vma, reqprot, prot); 827 if (error) 828 break; 829 830 tmp = vma->vm_end; 831 if (tmp > end) 832 tmp = end; 833 834 if (vma->vm_ops && vma->vm_ops->mprotect) { 835 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 836 if (error) 837 break; 838 } 839 840 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); 841 if (error) 842 break; 843 844 tmp = vma_iter_end(&vmi); 845 nstart = tmp; 846 prot = reqprot; 847 } 848 tlb_finish_mmu(&tlb); 849 850 if (!error && tmp < end) 851 error = -ENOMEM; 852 853 out: 854 mmap_write_unlock(current->mm); 855 return error; 856 } 857 858 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 859 unsigned long, prot) 860 { 861 return do_mprotect_pkey(start, len, prot, -1); 862 } 863 864 #ifdef CONFIG_ARCH_HAS_PKEYS 865 866 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 867 unsigned long, prot, int, pkey) 868 { 869 return do_mprotect_pkey(start, len, prot, pkey); 870 } 871 872 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 873 { 874 int pkey; 875 int ret; 876 877 /* No flags supported yet. */ 878 if (flags) 879 return -EINVAL; 880 /* check for unsupported init values */ 881 if (init_val & ~PKEY_ACCESS_MASK) 882 return -EINVAL; 883 884 mmap_write_lock(current->mm); 885 pkey = mm_pkey_alloc(current->mm); 886 887 ret = -ENOSPC; 888 if (pkey == -1) 889 goto out; 890 891 ret = arch_set_user_pkey_access(current, pkey, init_val); 892 if (ret) { 893 mm_pkey_free(current->mm, pkey); 894 goto out; 895 } 896 ret = pkey; 897 out: 898 mmap_write_unlock(current->mm); 899 return ret; 900 } 901 902 SYSCALL_DEFINE1(pkey_free, int, pkey) 903 { 904 int ret; 905 906 mmap_write_lock(current->mm); 907 ret = mm_pkey_free(current->mm, pkey); 908 mmap_write_unlock(current->mm); 909 910 /* 911 * We could provide warnings or errors if any VMA still 912 * has the pkey set here. 913 */ 914 return ret; 915 } 916 917 #endif /* CONFIG_ARCH_HAS_PKEYS */ 918