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 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_mkuffd_wp(ptent); 182 else if (uffd_wp_resolve) 183 ptent = pte_clear_uffd_wp(ptent); 184 185 /* 186 * In some writable, shared mappings, we might want 187 * to catch actual write access -- see 188 * vma_wants_writenotify(). 189 * 190 * In all writable, private mappings, we have to 191 * properly handle COW. 192 * 193 * In both cases, we can sometimes still change PTEs 194 * writable and avoid the write-fault handler, for 195 * example, if a PTE is already dirty and no other 196 * COW or special handling is required. 197 */ 198 if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) && 199 !pte_write(ptent) && 200 can_change_pte_writable(vma, addr, ptent)) 201 ptent = pte_mkwrite(ptent); 202 203 ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); 204 if (pte_needs_flush(oldpte, ptent)) 205 tlb_flush_pte_range(tlb, addr, PAGE_SIZE); 206 pages++; 207 } else if (is_swap_pte(oldpte)) { 208 swp_entry_t entry = pte_to_swp_entry(oldpte); 209 pte_t newpte; 210 211 if (is_writable_migration_entry(entry)) { 212 struct page *page = pfn_swap_entry_to_page(entry); 213 214 /* 215 * A protection check is difficult so 216 * just be safe and disable write 217 */ 218 if (PageAnon(page)) 219 entry = make_readable_exclusive_migration_entry( 220 swp_offset(entry)); 221 else 222 entry = make_readable_migration_entry(swp_offset(entry)); 223 newpte = swp_entry_to_pte(entry); 224 if (pte_swp_soft_dirty(oldpte)) 225 newpte = pte_swp_mksoft_dirty(newpte); 226 if (pte_swp_uffd_wp(oldpte)) 227 newpte = pte_swp_mkuffd_wp(newpte); 228 } else if (is_writable_device_private_entry(entry)) { 229 /* 230 * We do not preserve soft-dirtiness. See 231 * copy_one_pte() for explanation. 232 */ 233 entry = make_readable_device_private_entry( 234 swp_offset(entry)); 235 newpte = swp_entry_to_pte(entry); 236 if (pte_swp_uffd_wp(oldpte)) 237 newpte = pte_swp_mkuffd_wp(newpte); 238 } else if (is_writable_device_exclusive_entry(entry)) { 239 entry = make_readable_device_exclusive_entry( 240 swp_offset(entry)); 241 newpte = swp_entry_to_pte(entry); 242 if (pte_swp_soft_dirty(oldpte)) 243 newpte = pte_swp_mksoft_dirty(newpte); 244 if (pte_swp_uffd_wp(oldpte)) 245 newpte = pte_swp_mkuffd_wp(newpte); 246 } else if (is_pte_marker_entry(entry)) { 247 /* 248 * Ignore swapin errors unconditionally, 249 * because any access should sigbus anyway. 250 */ 251 if (is_swapin_error_entry(entry)) 252 continue; 253 /* 254 * If this is uffd-wp pte marker and we'd like 255 * to unprotect it, drop it; the next page 256 * fault will trigger without uffd trapping. 257 */ 258 if (uffd_wp_resolve) { 259 pte_clear(vma->vm_mm, addr, pte); 260 pages++; 261 } 262 continue; 263 } else { 264 newpte = oldpte; 265 } 266 267 if (uffd_wp) 268 newpte = pte_swp_mkuffd_wp(newpte); 269 else if (uffd_wp_resolve) 270 newpte = pte_swp_clear_uffd_wp(newpte); 271 272 if (!pte_same(oldpte, newpte)) { 273 set_pte_at(vma->vm_mm, addr, pte, newpte); 274 pages++; 275 } 276 } else { 277 /* It must be an none page, or what else?.. */ 278 WARN_ON_ONCE(!pte_none(oldpte)); 279 if (unlikely(uffd_wp && !vma_is_anonymous(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 * Used when setting automatic NUMA hinting protection where it is 300 * critical that a numa hinting PMD is not confused with a bad PMD. 301 */ 302 static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd) 303 { 304 pmd_t pmdval = pmdp_get_lockless(pmd); 305 306 /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */ 307 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 308 barrier(); 309 #endif 310 311 if (pmd_none(pmdval)) 312 return 1; 313 if (pmd_trans_huge(pmdval)) 314 return 0; 315 if (unlikely(pmd_bad(pmdval))) { 316 pmd_clear_bad(pmd); 317 return 1; 318 } 319 320 return 0; 321 } 322 323 /* Return true if we're uffd wr-protecting file-backed memory, or false */ 324 static inline bool 325 uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags) 326 { 327 return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma); 328 } 329 330 /* 331 * If wr-protecting the range for file-backed, populate pgtable for the case 332 * when pgtable is empty but page cache exists. When {pte|pmd|...}_alloc() 333 * failed we treat it the same way as pgtable allocation failures during 334 * page faults by kicking OOM and returning error. 335 */ 336 #define change_pmd_prepare(vma, pmd, cp_flags) \ 337 ({ \ 338 long err = 0; \ 339 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \ 340 if (pte_alloc(vma->vm_mm, pmd)) \ 341 err = -ENOMEM; \ 342 } \ 343 err; \ 344 }) 345 346 /* 347 * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to 348 * have separate change_pmd_prepare() because pte_alloc() returns 0 on success, 349 * while {pmd|pud|p4d}_alloc() returns the valid pointer on success. 350 */ 351 #define change_prepare(vma, high, low, addr, cp_flags) \ 352 ({ \ 353 long err = 0; \ 354 if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \ 355 low##_t *p = low##_alloc(vma->vm_mm, high, addr); \ 356 if (p == NULL) \ 357 err = -ENOMEM; \ 358 } \ 359 err; \ 360 }) 361 362 static inline long change_pmd_range(struct mmu_gather *tlb, 363 struct vm_area_struct *vma, pud_t *pud, unsigned long addr, 364 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 365 { 366 pmd_t *pmd; 367 unsigned long next; 368 long pages = 0; 369 unsigned long nr_huge_updates = 0; 370 struct mmu_notifier_range range; 371 372 range.start = 0; 373 374 pmd = pmd_offset(pud, addr); 375 do { 376 long ret; 377 378 next = pmd_addr_end(addr, end); 379 380 ret = change_pmd_prepare(vma, pmd, cp_flags); 381 if (ret) { 382 pages = ret; 383 break; 384 } 385 /* 386 * Automatic NUMA balancing walks the tables with mmap_lock 387 * held for read. It's possible a parallel update to occur 388 * between pmd_trans_huge() and a pmd_none_or_clear_bad() 389 * check leading to a false positive and clearing. 390 * Hence, it's necessary to atomically read the PMD value 391 * for all the checks. 392 */ 393 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) && 394 pmd_none_or_clear_bad_unless_trans_huge(pmd)) 395 goto next; 396 397 /* invoke the mmu notifier if the pmd is populated */ 398 if (!range.start) { 399 mmu_notifier_range_init(&range, 400 MMU_NOTIFY_PROTECTION_VMA, 0, 401 vma->vm_mm, addr, end); 402 mmu_notifier_invalidate_range_start(&range); 403 } 404 405 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { 406 if ((next - addr != HPAGE_PMD_SIZE) || 407 uffd_wp_protect_file(vma, cp_flags)) { 408 __split_huge_pmd(vma, pmd, addr, false, NULL); 409 /* 410 * For file-backed, the pmd could have been 411 * cleared; make sure pmd populated if 412 * necessary, then fall-through to pte level. 413 */ 414 ret = change_pmd_prepare(vma, pmd, cp_flags); 415 if (ret) { 416 pages = ret; 417 break; 418 } 419 } else { 420 /* 421 * change_huge_pmd() does not defer TLB flushes, 422 * so no need to propagate the tlb argument. 423 */ 424 int nr_ptes = change_huge_pmd(tlb, vma, pmd, 425 addr, newprot, cp_flags); 426 427 if (nr_ptes) { 428 if (nr_ptes == HPAGE_PMD_NR) { 429 pages += HPAGE_PMD_NR; 430 nr_huge_updates++; 431 } 432 433 /* huge pmd was handled */ 434 goto next; 435 } 436 } 437 /* fall through, the trans huge pmd just split */ 438 } 439 pages += change_pte_range(tlb, vma, pmd, addr, next, 440 newprot, cp_flags); 441 next: 442 cond_resched(); 443 } while (pmd++, addr = next, addr != end); 444 445 if (range.start) 446 mmu_notifier_invalidate_range_end(&range); 447 448 if (nr_huge_updates) 449 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); 450 return pages; 451 } 452 453 static inline long change_pud_range(struct mmu_gather *tlb, 454 struct vm_area_struct *vma, p4d_t *p4d, unsigned long addr, 455 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 456 { 457 pud_t *pud; 458 unsigned long next; 459 long pages = 0, ret; 460 461 pud = pud_offset(p4d, addr); 462 do { 463 next = pud_addr_end(addr, end); 464 ret = change_prepare(vma, pud, pmd, addr, cp_flags); 465 if (ret) 466 return ret; 467 if (pud_none_or_clear_bad(pud)) 468 continue; 469 pages += change_pmd_range(tlb, vma, pud, addr, next, newprot, 470 cp_flags); 471 } while (pud++, addr = next, addr != end); 472 473 return pages; 474 } 475 476 static inline long change_p4d_range(struct mmu_gather *tlb, 477 struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, 478 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 479 { 480 p4d_t *p4d; 481 unsigned long next; 482 long pages = 0, ret; 483 484 p4d = p4d_offset(pgd, addr); 485 do { 486 next = p4d_addr_end(addr, end); 487 ret = change_prepare(vma, p4d, pud, addr, cp_flags); 488 if (ret) 489 return ret; 490 if (p4d_none_or_clear_bad(p4d)) 491 continue; 492 pages += change_pud_range(tlb, vma, p4d, addr, next, newprot, 493 cp_flags); 494 } while (p4d++, addr = next, addr != end); 495 496 return pages; 497 } 498 499 static long change_protection_range(struct mmu_gather *tlb, 500 struct vm_area_struct *vma, unsigned long addr, 501 unsigned long end, pgprot_t newprot, unsigned long cp_flags) 502 { 503 struct mm_struct *mm = vma->vm_mm; 504 pgd_t *pgd; 505 unsigned long next; 506 long pages = 0, ret; 507 508 BUG_ON(addr >= end); 509 pgd = pgd_offset(mm, addr); 510 tlb_start_vma(tlb, vma); 511 do { 512 next = pgd_addr_end(addr, end); 513 ret = change_prepare(vma, pgd, p4d, addr, cp_flags); 514 if (ret) { 515 pages = ret; 516 break; 517 } 518 if (pgd_none_or_clear_bad(pgd)) 519 continue; 520 pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot, 521 cp_flags); 522 } while (pgd++, addr = next, addr != end); 523 524 tlb_end_vma(tlb, vma); 525 526 return pages; 527 } 528 529 long change_protection(struct mmu_gather *tlb, 530 struct vm_area_struct *vma, unsigned long start, 531 unsigned long end, unsigned long cp_flags) 532 { 533 pgprot_t newprot = vma->vm_page_prot; 534 long pages; 535 536 BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); 537 538 #ifdef CONFIG_NUMA_BALANCING 539 /* 540 * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking) 541 * are expected to reflect their requirements via VMA flags such that 542 * vma_set_page_prot() will adjust vma->vm_page_prot accordingly. 543 */ 544 if (cp_flags & MM_CP_PROT_NUMA) 545 newprot = PAGE_NONE; 546 #else 547 WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA); 548 #endif 549 550 if (is_vm_hugetlb_page(vma)) 551 pages = hugetlb_change_protection(vma, start, end, newprot, 552 cp_flags); 553 else 554 pages = change_protection_range(tlb, vma, start, end, newprot, 555 cp_flags); 556 557 return pages; 558 } 559 560 static int prot_none_pte_entry(pte_t *pte, unsigned long addr, 561 unsigned long next, struct mm_walk *walk) 562 { 563 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ? 564 0 : -EACCES; 565 } 566 567 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, 568 unsigned long addr, unsigned long next, 569 struct mm_walk *walk) 570 { 571 return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ? 572 0 : -EACCES; 573 } 574 575 static int prot_none_test(unsigned long addr, unsigned long next, 576 struct mm_walk *walk) 577 { 578 return 0; 579 } 580 581 static const struct mm_walk_ops prot_none_walk_ops = { 582 .pte_entry = prot_none_pte_entry, 583 .hugetlb_entry = prot_none_hugetlb_entry, 584 .test_walk = prot_none_test, 585 }; 586 587 int 588 mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, 589 struct vm_area_struct *vma, struct vm_area_struct **pprev, 590 unsigned long start, unsigned long end, unsigned long newflags) 591 { 592 struct mm_struct *mm = vma->vm_mm; 593 unsigned long oldflags = vma->vm_flags; 594 long nrpages = (end - start) >> PAGE_SHIFT; 595 unsigned int mm_cp_flags = 0; 596 unsigned long charged = 0; 597 pgoff_t pgoff; 598 int error; 599 600 if (newflags == oldflags) { 601 *pprev = vma; 602 return 0; 603 } 604 605 /* 606 * Do PROT_NONE PFN permission checks here when we can still 607 * bail out without undoing a lot of state. This is a rather 608 * uncommon case, so doesn't need to be very optimized. 609 */ 610 if (arch_has_pfn_modify_check() && 611 (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && 612 (newflags & VM_ACCESS_FLAGS) == 0) { 613 pgprot_t new_pgprot = vm_get_page_prot(newflags); 614 615 error = walk_page_range(current->mm, start, end, 616 &prot_none_walk_ops, &new_pgprot); 617 if (error) 618 return error; 619 } 620 621 /* 622 * If we make a private mapping writable we increase our commit; 623 * but (without finer accounting) cannot reduce our commit if we 624 * make it unwritable again. hugetlb mapping were accounted for 625 * even if read-only so there is no need to account for them here 626 */ 627 if (newflags & VM_WRITE) { 628 /* Check space limits when area turns into data. */ 629 if (!may_expand_vm(mm, newflags, nrpages) && 630 may_expand_vm(mm, oldflags, nrpages)) 631 return -ENOMEM; 632 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| 633 VM_SHARED|VM_NORESERVE))) { 634 charged = nrpages; 635 if (security_vm_enough_memory_mm(mm, charged)) 636 return -ENOMEM; 637 newflags |= VM_ACCOUNT; 638 } 639 } 640 641 /* 642 * First try to merge with previous and/or next vma. 643 */ 644 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); 645 *pprev = vma_merge(vmi, mm, *pprev, start, end, newflags, 646 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), 647 vma->vm_userfaultfd_ctx, anon_vma_name(vma)); 648 if (*pprev) { 649 vma = *pprev; 650 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY); 651 goto success; 652 } 653 654 *pprev = vma; 655 656 if (start != vma->vm_start) { 657 error = split_vma(vmi, vma, start, 1); 658 if (error) 659 goto fail; 660 } 661 662 if (end != vma->vm_end) { 663 error = split_vma(vmi, vma, end, 0); 664 if (error) 665 goto fail; 666 } 667 668 success: 669 /* 670 * vm_flags and vm_page_prot are protected by the mmap_lock 671 * held in write mode. 672 */ 673 vm_flags_reset(vma, newflags); 674 if (vma_wants_manual_pte_write_upgrade(vma)) 675 mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; 676 vma_set_page_prot(vma); 677 678 change_protection(tlb, vma, start, end, mm_cp_flags); 679 680 /* 681 * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major 682 * fault on access. 683 */ 684 if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && 685 (newflags & VM_WRITE)) { 686 populate_vma_page_range(vma, start, end, NULL); 687 } 688 689 vm_stat_account(mm, oldflags, -nrpages); 690 vm_stat_account(mm, newflags, nrpages); 691 perf_event_mmap(vma); 692 return 0; 693 694 fail: 695 vm_unacct_memory(charged); 696 return error; 697 } 698 699 /* 700 * pkey==-1 when doing a legacy mprotect() 701 */ 702 static int do_mprotect_pkey(unsigned long start, size_t len, 703 unsigned long prot, int pkey) 704 { 705 unsigned long nstart, end, tmp, reqprot; 706 struct vm_area_struct *vma, *prev; 707 int error; 708 const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); 709 const bool rier = (current->personality & READ_IMPLIES_EXEC) && 710 (prot & PROT_READ); 711 struct mmu_gather tlb; 712 struct vma_iterator vmi; 713 714 start = untagged_addr(start); 715 716 prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); 717 if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ 718 return -EINVAL; 719 720 if (start & ~PAGE_MASK) 721 return -EINVAL; 722 if (!len) 723 return 0; 724 len = PAGE_ALIGN(len); 725 end = start + len; 726 if (end <= start) 727 return -ENOMEM; 728 if (!arch_validate_prot(prot, start)) 729 return -EINVAL; 730 731 reqprot = prot; 732 733 if (mmap_write_lock_killable(current->mm)) 734 return -EINTR; 735 736 /* 737 * If userspace did not allocate the pkey, do not let 738 * them use it here. 739 */ 740 error = -EINVAL; 741 if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) 742 goto out; 743 744 vma_iter_init(&vmi, current->mm, start); 745 vma = vma_find(&vmi, end); 746 error = -ENOMEM; 747 if (!vma) 748 goto out; 749 750 if (unlikely(grows & PROT_GROWSDOWN)) { 751 if (vma->vm_start >= end) 752 goto out; 753 start = vma->vm_start; 754 error = -EINVAL; 755 if (!(vma->vm_flags & VM_GROWSDOWN)) 756 goto out; 757 } else { 758 if (vma->vm_start > start) 759 goto out; 760 if (unlikely(grows & PROT_GROWSUP)) { 761 end = vma->vm_end; 762 error = -EINVAL; 763 if (!(vma->vm_flags & VM_GROWSUP)) 764 goto out; 765 } 766 } 767 768 prev = vma_prev(&vmi); 769 if (start > vma->vm_start) 770 prev = vma; 771 772 tlb_gather_mmu(&tlb, current->mm); 773 nstart = start; 774 tmp = vma->vm_start; 775 for_each_vma_range(vmi, vma, end) { 776 unsigned long mask_off_old_flags; 777 unsigned long newflags; 778 int new_vma_pkey; 779 780 if (vma->vm_start != tmp) { 781 error = -ENOMEM; 782 break; 783 } 784 785 /* Does the application expect PROT_READ to imply PROT_EXEC */ 786 if (rier && (vma->vm_flags & VM_MAYEXEC)) 787 prot |= PROT_EXEC; 788 789 /* 790 * Each mprotect() call explicitly passes r/w/x permissions. 791 * If a permission is not passed to mprotect(), it must be 792 * cleared from the VMA. 793 */ 794 mask_off_old_flags = VM_ACCESS_FLAGS | VM_FLAGS_CLEAR; 795 796 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); 797 newflags = calc_vm_prot_bits(prot, new_vma_pkey); 798 newflags |= (vma->vm_flags & ~mask_off_old_flags); 799 800 /* newflags >> 4 shift VM_MAY% in place of VM_% */ 801 if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { 802 error = -EACCES; 803 break; 804 } 805 806 if (map_deny_write_exec(vma, newflags)) { 807 error = -EACCES; 808 break; 809 } 810 811 /* Allow architectures to sanity-check the new flags */ 812 if (!arch_validate_flags(newflags)) { 813 error = -EINVAL; 814 break; 815 } 816 817 error = security_file_mprotect(vma, reqprot, prot); 818 if (error) 819 break; 820 821 tmp = vma->vm_end; 822 if (tmp > end) 823 tmp = end; 824 825 if (vma->vm_ops && vma->vm_ops->mprotect) { 826 error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags); 827 if (error) 828 break; 829 } 830 831 error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags); 832 if (error) 833 break; 834 835 tmp = vma_iter_end(&vmi); 836 nstart = tmp; 837 prot = reqprot; 838 } 839 tlb_finish_mmu(&tlb); 840 841 if (!error && vma_iter_end(&vmi) < end) 842 error = -ENOMEM; 843 844 out: 845 mmap_write_unlock(current->mm); 846 return error; 847 } 848 849 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, 850 unsigned long, prot) 851 { 852 return do_mprotect_pkey(start, len, prot, -1); 853 } 854 855 #ifdef CONFIG_ARCH_HAS_PKEYS 856 857 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, 858 unsigned long, prot, int, pkey) 859 { 860 return do_mprotect_pkey(start, len, prot, pkey); 861 } 862 863 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) 864 { 865 int pkey; 866 int ret; 867 868 /* No flags supported yet. */ 869 if (flags) 870 return -EINVAL; 871 /* check for unsupported init values */ 872 if (init_val & ~PKEY_ACCESS_MASK) 873 return -EINVAL; 874 875 mmap_write_lock(current->mm); 876 pkey = mm_pkey_alloc(current->mm); 877 878 ret = -ENOSPC; 879 if (pkey == -1) 880 goto out; 881 882 ret = arch_set_user_pkey_access(current, pkey, init_val); 883 if (ret) { 884 mm_pkey_free(current->mm, pkey); 885 goto out; 886 } 887 ret = pkey; 888 out: 889 mmap_write_unlock(current->mm); 890 return ret; 891 } 892 893 SYSCALL_DEFINE1(pkey_free, int, pkey) 894 { 895 int ret; 896 897 mmap_write_lock(current->mm); 898 ret = mm_pkey_free(current->mm, pkey); 899 mmap_write_unlock(current->mm); 900 901 /* 902 * We could provide warnings or errors if any VMA still 903 * has the pkey set here. 904 */ 905 return ret; 906 } 907 908 #endif /* CONFIG_ARCH_HAS_PKEYS */ 909