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