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