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 bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, 43 pte_t pte) 44 { 45 struct page *page; 46 47 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) 48 return false; 49 50 /* Don't touch entries that are not even readable. */ 51 if (pte_protnone(pte)) 52 return false; 53 54 /* Do we need write faults for softdirty tracking? */ 55 if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte)) 56 return false; 57 58 /* Do we need write faults for uffd-wp tracking? */ 59 if (userfaultfd_pte_wp(vma, pte)) 60 return false; 61 62 if (!(vma->vm_flags & VM_SHARED)) { 63 /* 64 * Writable MAP_PRIVATE mapping: We can only special-case on 65 * exclusive anonymous pages, because we know that our 66 * write-fault handler similarly would map them writable without 67 * any additional checks while holding the PT lock. 68 */ 69 page = vm_normal_page(vma, addr, pte); 70 return page && PageAnon(page) && PageAnonExclusive(page); 71 } 72 73 /* 74 * Writable MAP_SHARED mapping: "clean" might indicate that the FS still 75 * needs a real write-fault for writenotify 76 * (see vma_wants_writenotify()). If "dirty", the assumption is that the 77 * FS was already notified and we can simply mark the PTE writable 78 * just like the write-fault handler would do. 79 */ 80 return pte_dirty(pte); 81 } 82 83 static unsigned long change_pte_range(struct mmu_gather *tlb, 84 struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, 85 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 86 { 87 pte_t *pte, oldpte; 88 spinlock_t *ptl; 89 unsigned long pages = 0; 90 int target_node = NUMA_NO_NODE; 91 bool prot_numa = cp_flags & MM_CP_PROT_NUMA; 92 bool uffd_wp = cp_flags & MM_CP_UFFD_WP; 93 bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; 94 95 tlb_change_page_size(tlb, PAGE_SIZE); 96 97 /* 98 * Can be called with only the mmap_lock for reading by 99 * prot_numa so we must check the pmd isn't constantly 100 * changing from under us from pmd_none to pmd_trans_huge 101 * and/or the other way around. 102 */ 103 if (pmd_trans_unstable(pmd)) 104 return 0; 105 106 /* 107 * The pmd points to a regular pte so the pmd can't change 108 * from under us even if the mmap_lock is only hold for 109 * reading. 110 */ 111 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 112 113 /* Get target node for single threaded private VMAs */ 114 if (prot_numa && !(vma->vm_flags & VM_SHARED) && 115 atomic_read(&vma->vm_mm->mm_users) == 1) 116 target_node = numa_node_id(); 117 118 flush_tlb_batched_pending(vma->vm_mm); 119 arch_enter_lazy_mmu_mode(); 120 do { 121 oldpte = *pte; 122 if (pte_present(oldpte)) { 123 pte_t ptent; 124 125 /* 126 * Avoid trapping faults against the zero or KSM 127 * pages. See similar comment in change_huge_pmd. 128 */ 129 if (prot_numa) { 130 struct page *page; 131 int nid; 132 bool toptier; 133 134 /* Avoid TLB flush if possible */ 135 if (pte_protnone(oldpte)) 136 continue; 137 138 page = vm_normal_page(vma, addr, oldpte); 139 if (!page || is_zone_device_page(page) || PageKsm(page)) 140 continue; 141 142 /* Also skip shared copy-on-write pages */ 143 if (is_cow_mapping(vma->vm_flags) && 144 page_count(page) != 1) 145 continue; 146 147 /* 148 * While migration can move some dirty pages, 149 * it cannot move them all from MIGRATE_ASYNC 150 * context. 151 */ 152 if (page_is_file_lru(page) && PageDirty(page)) 153 continue; 154 155 /* 156 * Don't mess with PTEs if page is already on the node 157 * a single-threaded process is running on. 158 */ 159 nid = page_to_nid(page); 160 if (target_node == nid) 161 continue; 162 toptier = node_is_toptier(nid); 163 164 /* 165 * Skip scanning top tier node if normal numa 166 * balancing is disabled 167 */ 168 if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && 169 toptier) 170 continue; 171 if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING && 172 !toptier) 173 xchg_page_access_time(page, 174 jiffies_to_msecs(jiffies)); 175 } 176 177 oldpte = ptep_modify_prot_start(vma, addr, pte); 178 ptent = pte_modify(oldpte, newprot); 179 180 if (uffd_wp) { 181 ptent = pte_wrprotect(ptent); 182 ptent = pte_mkuffd_wp(ptent); 183 } else if (uffd_wp_resolve) { 184 ptent = pte_clear_uffd_wp(ptent); 185 } 186 187 /* 188 * In some writable, shared mappings, we might want 189 * to catch actual write access -- see 190 * vma_wants_writenotify(). 191 * 192 * In all writable, private mappings, we have to 193 * properly handle COW. 194 * 195 * In both cases, we can sometimes still change PTEs 196 * writable and avoid the write-fault handler, for 197 * example, if a PTE is already dirty and no other 198 * COW or special handling is required. 199 */ 200 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && 201 !pte_write(ptent) && 202 can_change_pte_writable(vma, addr, ptent)) 203 ptent = pte_mkwrite(ptent); 204 205 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); 206 if (pte_needs_flush(oldpte, ptent)) 207 tlb_flush_pte_range(tlb, addr, PAGE_SIZE); 208 pages++; 209 } else if (is_swap_pte(oldpte)) { 210 swp_entry_t entry = pte_to_swp_entry(oldpte); 211 pte_t newpte; 212 213 if (is_writable_migration_entry(entry)) { 214 struct page *page = pfn_swap_entry_to_page(entry); 215 216 /* 217 * A protection check is difficult so 218 * just be safe and disable write 219 */ 220 if (PageAnon(page)) 221 entry = make_readable_exclusive_migration_entry( 222 swp_offset(entry)); 223 else 224 entry = make_readable_migration_entry(swp_offset(entry)); 225 newpte = swp_entry_to_pte(entry); 226 if (pte_swp_soft_dirty(oldpte)) 227 newpte = pte_swp_mksoft_dirty(newpte); 228 if (pte_swp_uffd_wp(oldpte)) 229 newpte = pte_swp_mkuffd_wp(newpte); 230 } else if (is_writable_device_private_entry(entry)) { 231 /* 232 * We do not preserve soft-dirtiness. See 233 * copy_one_pte() for explanation. 234 */ 235 entry = make_readable_device_private_entry( 236 swp_offset(entry)); 237 newpte = swp_entry_to_pte(entry); 238 if (pte_swp_uffd_wp(oldpte)) 239 newpte = pte_swp_mkuffd_wp(newpte); 240 } else if (is_writable_device_exclusive_entry(entry)) { 241 entry = make_readable_device_exclusive_entry( 242 swp_offset(entry)); 243 newpte = swp_entry_to_pte(entry); 244 if (pte_swp_soft_dirty(oldpte)) 245 newpte = pte_swp_mksoft_dirty(newpte); 246 if (pte_swp_uffd_wp(oldpte)) 247 newpte = pte_swp_mkuffd_wp(newpte); 248 } else if (pte_marker_entry_uffd_wp(entry)) { 249 /* 250 * If this is uffd-wp pte marker and we'd like 251 * to unprotect it, drop it; the next page 252 * fault will trigger without uffd trapping. 253 */ 254 if (uffd_wp_resolve) { 255 pte_clear(vma->vm_mm, addr, pte); 256 pages++; 257 } 258 continue; 259 } else { 260 newpte = oldpte; 261 } 262 263 if (uffd_wp) 264 newpte = pte_swp_mkuffd_wp(newpte); 265 else if (uffd_wp_resolve) 266 newpte = pte_swp_clear_uffd_wp(newpte); 267 268 if (!pte_same(oldpte, newpte)) { 269 set_pte_at(vma->vm_mm, addr, pte, newpte); 270 pages++; 271 } 272 } else { 273 /* It must be an none page, or what else?.. */ 274 WARN_ON_ONCE(!pte_none(oldpte)); 275 if (unlikely(uffd_wp && !vma_is_anonymous(vma))) { 276 /* 277 * For file-backed mem, we need to be able to 278 * wr-protect a none pte, because even if the 279 * pte is none, the page/swap cache could 280 * exist. Doing that by install a marker. 281 */ 282 set_pte_at(vma->vm_mm, addr, pte, 283 make_pte_marker(PTE_MARKER_UFFD_WP)); 284 pages++; 285 } 286 } 287 } while (pte++, addr += PAGE_SIZE, addr != end); 288 arch_leave_lazy_mmu_mode(); 289 pte_unmap_unlock(pte - 1, ptl); 290 291 return pages; 292 } 293 294 /* 295 * Used when setting automatic NUMA hinting protection where it is 296 * critical that a numa hinting PMD is not confused with a bad PMD. 297 */ 298 static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd) 299 { 300 pmd_t pmdval = pmdp_get_lockless(pmd); 301 302 /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */ 303 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 304 barrier(); 305 #endif 306 307 if (pmd_none(pmdval)) 308 return 1; 309 if (pmd_trans_huge(pmdval)) 310 return 0; 311 if (unlikely(pmd_bad(pmdval))) { 312 pmd_clear_bad(pmd); 313 return 1; 314 } 315 316 return 0; 317 } 318 319 /* Return true if we're uffd wr-protecting file-backed memory, or false */ 320 static inline bool 321 uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags) 322 { 323 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma); 324 } 325 326 /* 327 * If wr-protecting the range for file-backed, populate pgtable for the case 328 * when pgtable is empty but page cache exists. When {pte|pmd|...}_alloc() 329 * failed it means no memory, we don't have a better option but stop. 330 */ 331 #define change_pmd_prepare(vma, pmd, cp_flags) \ 332 do { \ 333 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \ 334 if (WARN_ON_ONCE(pte_alloc(vma->vm_mm, pmd))) \ 335 break; \ 336 } \ 337 } while (0) 338 /* 339 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to 340 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, 341 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. 342 */ 343 #define change_prepare(vma, high, low, addr, cp_flags) \ 344 do { \ 345 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \ 346 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ 347 if (WARN_ON_ONCE(p == NULL)) \ 348 break; \ 349 } \ 350 } while (0) 351 352 static inline unsigned long change_pmd_range(struct mmu_gather *tlb, 353 struct vm_area_struct *vma, pud_t *pud, unsigned long addr, 354 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 355 { 356 pmd_t *pmd; 357 unsigned long next; 358 unsigned long pages = 0; 359 unsigned long nr_huge_updates = 0; 360 struct mmu_notifier_range range; 361 362 range.start = 0; 363 364 pmd = pmd_offset(pud, addr); 365 do { 366 unsigned long this_pages; 367 368 next = pmd_addr_end(addr, end); 369 370 change_pmd_prepare(vma, pmd, cp_flags); 371 /* 372 * Automatic NUMA balancing walks the tables with mmap_lock 373 * held for read. It's possible a parallel update to occur 374 * between pmd_trans_huge() and a pmd_none_or_clear_bad() 375 * check leading to a false positive and clearing. 376 * Hence, it's necessary to atomically read the PMD value 377 * for all the checks. 378 */ 379 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) && 380 pmd_none_or_clear_bad_unless_trans_huge(pmd)) 381 goto next; 382 383 /* invoke the mmu notifier if the pmd is populated */ 384 if (!range.start) { 385 mmu_notifier_range_init(&range, 386 MMU_NOTIFY_PROTECTION_VMA, 0, 387 vma, vma->vm_mm, addr, end); 388 mmu_notifier_invalidate_range_start(&range); 389 } 390 391 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { 392 if ((next - addr != HPAGE_PMD_SIZE) || 393 uffd_wp_protect_file(vma, cp_flags)) { 394 __split_huge_pmd(vma, pmd, addr, false, NULL); 395 /* 396 * For file-backed, the pmd could have been 397 * cleared; make sure pmd populated if 398 * necessary, then fall-through to pte level. 399 */ 400 change_pmd_prepare(vma, pmd, cp_flags); 401 } else { 402 /* 403 * change_huge_pmd() does not defer TLB flushes, 404 * so no need to propagate the tlb argument. 405 */ 406 int nr_ptes = change_huge_pmd(tlb, vma, pmd, 407 addr, newprot, cp_flags); 408 409 if (nr_ptes) { 410 if (nr_ptes == HPAGE_PMD_NR) { 411 pages += HPAGE_PMD_NR; 412 nr_huge_updates++; 413 } 414 415 /* huge pmd was handled */ 416 goto next; 417 } 418 } 419 /* fall through, the trans huge pmd just split */ 420 } 421 this_pages = change_pte_range(tlb, vma, pmd, addr, next, 422 newprot, cp_flags); 423 pages += this_pages; 424 next: 425 cond_resched(); 426 } while (pmd++, addr = next, addr != end); 427 428 if (range.start) 429 mmu_notifier_invalidate_range_end(&range); 430 431 if (nr_huge_updates) 432 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 433 return pages; 434 } 435 436 static inline unsigned long change_pud_range(struct mmu_gather *tlb, 437 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 438 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 439 { 440 pud_t *pud; 441 unsigned long next; 442 unsigned long pages = 0; 443 444 pud = pud_offset(p4d, addr); 445 do { 446 next = pud_addr_end(addr, end); 447 change_prepare(vma, pud, pmd, addr, cp_flags); 448 if (pud_none_or_clear_bad(pud)) 449 continue; 450 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot, 451 cp_flags); 452 } while (pud++, addr = next, addr != end); 453 454 return pages; 455 } 456 457 static inline unsigned long change_p4d_range(struct mmu_gather *tlb, 458 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 459 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 460 { 461 p4d_t *p4d; 462 unsigned long next; 463 unsigned long pages = 0; 464 465 p4d = p4d_offset(pgd, addr); 466 do { 467 next = p4d_addr_end(addr, end); 468 change_prepare(vma, p4d, pud, addr, cp_flags); 469 if (p4d_none_or_clear_bad(p4d)) 470 continue; 471 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 472 cp_flags); 473 } while (p4d++, addr = next, addr != end); 474 475 return pages; 476 } 477 478 static unsigned long change_protection_range(struct mmu_gather *tlb, 479 struct vm_area_struct *vma, unsigned long addr, 480 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 481 { 482 struct mm_struct *mm = vma->vm_mm; 483 pgd_t *pgd; 484 unsigned long next; 485 unsigned long pages = 0; 486 487 BUG_ON(addr >= end); 488 pgd = pgd_offset(mm, addr); 489 tlb_start_vma(tlb, vma); 490 do { 491 next = pgd_addr_end(addr, end); 492 change_prepare(vma, pgd, p4d, addr, cp_flags); 493 if (pgd_none_or_clear_bad(pgd)) 494 continue; 495 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 496 cp_flags); 497 } while (pgd++, addr = next, addr != end); 498 499 tlb_end_vma(tlb, vma); 500 501 return pages; 502 } 503 504 unsigned long change_protection(struct mmu_gather *tlb, 505 struct vm_area_struct *vma, unsigned long start, 506 unsigned long end, pgprot_t newprot, 507 unsigned long cp_flags) 508 { 509 unsigned long pages; 510 511 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 512 513 if (is_vm_hugetlb_page(vma)) 514 pages = hugetlb_change_protection(vma, start, end, newprot, 515 cp_flags); 516 else 517 pages = change_protection_range(tlb, vma, start, end, newprot, 518 cp_flags); 519 520 return pages; 521 } 522 523 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 524 unsigned long next, struct mm_walk *walk) 525 { 526 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ? 527 0 : -EACCES; 528 } 529 530 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 531 unsigned long addr, unsigned long next, 532 struct mm_walk *walk) 533 { 534 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ? 535 0 : -EACCES; 536 } 537 538 static int prot_none_test(unsigned long addr, unsigned long next, 539 struct mm_walk *walk) 540 { 541 return 0; 542 } 543 544 static const struct mm_walk_ops prot_none_walk_ops = { 545 .pte_entry = prot_none_pte_entry, 546 .hugetlb_entry = prot_none_hugetlb_entry, 547 .test_walk = prot_none_test, 548 }; 549 550 int 551 mprotect_fixup(struct mmu_gather *tlb, struct vm_area_struct *vma, 552 struct vm_area_struct **pprev, unsigned long start, 553 unsigned long end, unsigned long newflags) 554 { 555 struct mm_struct *mm = vma->vm_mm; 556 unsigned long oldflags = vma->vm_flags; 557 long nrpages = (end - start) >> PAGE_SHIFT; 558 unsigned int mm_cp_flags = 0; 559 unsigned long charged = 0; 560 pgoff_t pgoff; 561 int error; 562 563 if (newflags == oldflags) { 564 *pprev = vma; 565 return 0; 566 } 567 568 /* 569 * Do PROT_NONE PFN permission checks here when we can still 570 * bail out without undoing a lot of state. This is a rather 571 * uncommon case, so doesn't need to be very optimized. 572 */ 573 if (arch_has_pfn_modify_check() && 574 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 575 (newflags & VM_ACCESS_FLAGS) == 0) { 576 pgprot_t new_pgprot = vm_get_page_prot(newflags); 577 578 error = walk_page_range(current->mm, start, end, 579 &prot_none_walk_ops, &new_pgprot); 580 if (error) 581 return error; 582 } 583 584 /* 585 * If we make a private mapping writable we increase our commit; 586 * but (without finer accounting) cannot reduce our commit if we 587 * make it unwritable again. hugetlb mapping were accounted for 588 * even if read-only so there is no need to account for them here 589 */ 590 if (newflags & VM_WRITE) { 591 /* Check space limits when area turns into data. */ 592 if (!may_expand_vm(mm, newflags, nrpages) && 593 may_expand_vm(mm, oldflags, nrpages)) 594 return -ENOMEM; 595 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 596 VM_SHARED|VM_NORESERVE))) { 597 charged = nrpages; 598 if (security_vm_enough_memory_mm(mm, charged)) 599 return -ENOMEM; 600 newflags |= VM_ACCOUNT; 601 } 602 } 603 604 /* 605 * First try to merge with previous and/or next vma. 606 */ 607 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); 608 *pprev = vma_merge(mm, *pprev, start, end, newflags, 609 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), 610 vma->vm_userfaultfd_ctx, anon_vma_name(vma)); 611 if (*pprev) { 612 vma = *pprev; 613 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY); 614 goto success; 615 } 616 617 *pprev = vma; 618 619 if (start != vma->vm_start) { 620 error = split_vma(mm, vma, start, 1); 621 if (error) 622 goto fail; 623 } 624 625 if (end != vma->vm_end) { 626 error = split_vma(mm, vma, end, 0); 627 if (error) 628 goto fail; 629 } 630 631 success: 632 /* 633 * vm_flags and vm_page_prot are protected by the mmap_lock 634 * held in write mode. 635 */ 636 vma->vm_flags = newflags; 637 if (vma_wants_manual_pte_write_upgrade(vma)) 638 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 639 vma_set_page_prot(vma); 640 641 change_protection(tlb, vma, start, end, vma->vm_page_prot, mm_cp_flags); 642 643 /* 644 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 645 * fault on access. 646 */ 647 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 648 (newflags & VM_WRITE)) { 649 populate_vma_page_range(vma, start, end, NULL); 650 } 651 652 vm_stat_account(mm, oldflags, -nrpages); 653 vm_stat_account(mm, newflags, nrpages); 654 perf_event_mmap(vma); 655 return 0; 656 657 fail: 658 vm_unacct_memory(charged); 659 return error; 660 } 661 662 /* 663 * pkey==-1 when doing a legacy mprotect() 664 */ 665 static int do_mprotect_pkey(unsigned long start, size_t len, 666 unsigned long prot, int pkey) 667 { 668 unsigned long nstart, end, tmp, reqprot; 669 struct vm_area_struct *vma, *prev; 670 int error; 671 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 672 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 673 (prot & PROT_READ); 674 struct mmu_gather tlb; 675 MA_STATE(mas, ¤t->mm->mm_mt, 0, 0); 676 677 start = untagged_addr(start); 678 679 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 680 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 681 return -EINVAL; 682 683 if (start & ~PAGE_MASK) 684 return -EINVAL; 685 if (!len) 686 return 0; 687 len = PAGE_ALIGN(len); 688 end = start + len; 689 if (end <= start) 690 return -ENOMEM; 691 if (!arch_validate_prot(prot, start)) 692 return -EINVAL; 693 694 reqprot = prot; 695 696 if (mmap_write_lock_killable(current->mm)) 697 return -EINTR; 698 699 /* 700 * If userspace did not allocate the pkey, do not let 701 * them use it here. 702 */ 703 error = -EINVAL; 704 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 705 goto out; 706 707 mas_set(&mas, start); 708 vma = mas_find(&mas, ULONG_MAX); 709 error = -ENOMEM; 710 if (!vma) 711 goto out; 712 713 if (unlikely(grows & PROT_GROWSDOWN)) { 714 if (vma->vm_start >= end) 715 goto out; 716 start = vma->vm_start; 717 error = -EINVAL; 718 if (!(vma->vm_flags & VM_GROWSDOWN)) 719 goto out; 720 } else { 721 if (vma->vm_start > start) 722 goto out; 723 if (unlikely(grows & PROT_GROWSUP)) { 724 end = vma->vm_end; 725 error = -EINVAL; 726 if (!(vma->vm_flags & VM_GROWSUP)) 727 goto out; 728 } 729 } 730 731 if (start > vma->vm_start) 732 prev = vma; 733 else 734 prev = mas_prev(&mas, 0); 735 736 tlb_gather_mmu(&tlb, current->mm); 737 for (nstart = start ; ; ) { 738 unsigned long mask_off_old_flags; 739 unsigned long newflags; 740 int new_vma_pkey; 741 742 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ 743 744 /* Does the application expect PROT_READ to imply PROT_EXEC */ 745 if (rier && (vma->vm_flags & VM_MAYEXEC)) 746 prot |= PROT_EXEC; 747 748 /* 749 * Each mprotect() call explicitly passes r/w/x permissions. 750 * If a permission is not passed to mprotect(), it must be 751 * cleared from the VMA. 752 */ 753 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 754 755 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 756 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 757 newflags |= (vma->vm_flags & ~mask_off_old_flags); 758 759 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 760 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 761 error = -EACCES; 762 break; 763 } 764 765 /* Allow architectures to sanity-check the new flags */ 766 if (!arch_validate_flags(newflags)) { 767 error = -EINVAL; 768 break; 769 } 770 771 error = security_file_mprotect(vma, reqprot, prot); 772 if (error) 773 break; 774 775 tmp = vma->vm_end; 776 if (tmp > end) 777 tmp = end; 778 779 if (vma->vm_ops && vma->vm_ops->mprotect) { 780 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 781 if (error) 782 break; 783 } 784 785 error = mprotect_fixup(&tlb, vma, &prev, nstart, tmp, newflags); 786 if (error) 787 break; 788 789 nstart = tmp; 790 791 if (nstart < prev->vm_end) 792 nstart = prev->vm_end; 793 if (nstart >= end) 794 break; 795 796 vma = find_vma(current->mm, prev->vm_end); 797 if (!vma || vma->vm_start != nstart) { 798 error = -ENOMEM; 799 break; 800 } 801 prot = reqprot; 802 } 803 tlb_finish_mmu(&tlb); 804 out: 805 mmap_write_unlock(current->mm); 806 return error; 807 } 808 809 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 810 unsigned long, prot) 811 { 812 return do_mprotect_pkey(start, len, prot, -1); 813 } 814 815 #ifdef CONFIG_ARCH_HAS_PKEYS 816 817 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 818 unsigned long, prot, int, pkey) 819 { 820 return do_mprotect_pkey(start, len, prot, pkey); 821 } 822 823 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 824 { 825 int pkey; 826 int ret; 827 828 /* No flags supported yet. */ 829 if (flags) 830 return -EINVAL; 831 /* check for unsupported init values */ 832 if (init_val & ~PKEY_ACCESS_MASK) 833 return -EINVAL; 834 835 mmap_write_lock(current->mm); 836 pkey = mm_pkey_alloc(current->mm); 837 838 ret = -ENOSPC; 839 if (pkey == -1) 840 goto out; 841 842 ret = arch_set_user_pkey_access(current, pkey, init_val); 843 if (ret) { 844 mm_pkey_free(current->mm, pkey); 845 goto out; 846 } 847 ret = pkey; 848 out: 849 mmap_write_unlock(current->mm); 850 return ret; 851 } 852 853 SYSCALL_DEFINE1(pkey_free, int, pkey) 854 { 855 int ret; 856 857 mmap_write_lock(current->mm); 858 ret = mm_pkey_free(current->mm, pkey); 859 mmap_write_unlock(current->mm); 860 861 /* 862 * We could provide warnings or errors if any VMA still 863 * has the pkey set here. 864 */ 865 return ret; 866 } 867 868 #endif /* CONFIG_ARCH_HAS_PKEYS */ 869