mm/mprotect.c

   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/mm.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 <asm/pgtable.h>
  31 #include <asm/cacheflush.h>
  32 #include <asm/mmu_context.h>
  33 #include <asm/tlbflush.h>
  34
  35 #include "internal.h"
  36
  37 static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
  38                 unsigned long addr, unsigned long end, pgprot_t newprot,
  39                 int dirty_accountable, int prot_numa)
  40 {
  41         struct mm_struct *mm = vma->vm_mm;
  42         pte_t *pte, oldpte;
  43         spinlock_t *ptl;
  44         unsigned long pages = 0;
  45         int target_node = NUMA_NO_NODE;
  46
  47         /*
  48          * Can be called with only the mmap_sem for reading by
  49          * prot_numa so we must check the pmd isn't constantly
  50          * changing from under us from pmd_none to pmd_trans_huge
  51          * and/or the other way around.
  52          */
  53         if (pmd_trans_unstable(pmd))
  54                 return 0;
  55
  56         /*
  57          * The pmd points to a regular pte so the pmd can't change
  58          * from under us even if the mmap_sem is only hold for
  59          * reading.
  60          */
  61         pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
  62
  63         /* Get target node for single threaded private VMAs */
  64         if (prot_numa && !(vma->vm_flags & VM_SHARED) &&
  65             atomic_read(&vma->vm_mm->mm_users) == 1)
  66                 target_node = numa_node_id();
  67
  68         flush_tlb_batched_pending(vma->vm_mm);
  69         arch_enter_lazy_mmu_mode();
  70         do {
  71                 oldpte = *pte;
  72                 if (pte_present(oldpte)) {
  73                         pte_t ptent;
  74                         bool preserve_write = prot_numa && pte_write(oldpte);
  75
  76                         /*
  77                          * Avoid trapping faults against the zero or KSM
  78                          * pages. See similar comment in change_huge_pmd.
  79                          */
  80                         if (prot_numa) {
  81                                 struct page *page;
  82
  83                                 page = vm_normal_page(vma, addr, oldpte);
  84                                 if (!page || PageKsm(page))
  85                                         continue;
  86
  87                                 /* Avoid TLB flush if possible */
  88                                 if (pte_protnone(oldpte))
  89                                         continue;
  90
  91                                 /*
  92                                  * Don't mess with PTEs if page is already on the node
  93                                  * a single-threaded process is running on.
  94                                  */
  95                                 if (target_node == page_to_nid(page))
  96                                         continue;
  97                         }
  98
  99                         ptent = ptep_modify_prot_start(mm, addr, pte);
 100                         ptent = pte_modify(ptent, newprot);
 101                         if (preserve_write)
 102                                 ptent = pte_mk_savedwrite(ptent);
 103
 104                         /* Avoid taking write faults for known dirty pages */
 105                         if (dirty_accountable && pte_dirty(ptent) &&
 106                                         (pte_soft_dirty(ptent) ||
 107                                          !(vma->vm_flags & VM_SOFTDIRTY))) {
 108                                 ptent = pte_mkwrite(ptent);
 109                         }
 110                         ptep_modify_prot_commit(mm, addr, pte, ptent);
 111                         pages++;
 112                 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
 113                         swp_entry_t entry = pte_to_swp_entry(oldpte);
 114
 115                         if (is_write_migration_entry(entry)) {
 116                                 pte_t newpte;
 117                                 /*
 118                                  * A protection check is difficult so
 119                                  * just be safe and disable write
 120                                  */
 121                                 make_migration_entry_read(&entry);
 122                                 newpte = swp_entry_to_pte(entry);
 123                                 if (pte_swp_soft_dirty(oldpte))
 124                                         newpte = pte_swp_mksoft_dirty(newpte);
 125                                 set_pte_at(mm, addr, pte, newpte);
 126
 127                                 pages++;
 128                         }
 129
 130                         if (is_write_device_private_entry(entry)) {
 131                                 pte_t newpte;
 132
 133                                 /*
 134                                  * We do not preserve soft-dirtiness. See
 135                                  * copy_one_pte() for explanation.
 136                                  */
 137                                 make_device_private_entry_read(&entry);
 138                                 newpte = swp_entry_to_pte(entry);
 139                                 set_pte_at(mm, addr, pte, newpte);
 140
 141                                 pages++;
 142                         }
 143                 }
 144         } while (pte++, addr += PAGE_SIZE, addr != end);
 145         arch_leave_lazy_mmu_mode();
 146         pte_unmap_unlock(pte - 1, ptl);
 147
 148         return pages;
 149 }
 150
 151 /*
 152  * Used when setting automatic NUMA hinting protection where it is
 153  * critical that a numa hinting PMD is not confused with a bad PMD.
 154  */
 155 static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd)
 156 {
 157         pmd_t pmdval = pmd_read_atomic(pmd);
 158
 159         /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */
 160 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 161         barrier();
 162 #endif
 163
 164         if (pmd_none(pmdval))
 165                 return 1;
 166         if (pmd_trans_huge(pmdval))
 167                 return 0;
 168         if (unlikely(pmd_bad(pmdval))) {
 169                 pmd_clear_bad(pmd);
 170                 return 1;
 171         }
 172
 173         return 0;
 174 }
 175
 176 static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 177                 pud_t *pud, unsigned long addr, unsigned long end,
 178                 pgprot_t newprot, int dirty_accountable, int prot_numa)
 179 {
 180         pmd_t *pmd;
 181         struct mm_struct *mm = vma->vm_mm;
 182         unsigned long next;
 183         unsigned long pages = 0;
 184         unsigned long nr_huge_updates = 0;
 185         unsigned long mni_start = 0;
 186
 187         pmd = pmd_offset(pud, addr);
 188         do {
 189                 unsigned long this_pages;
 190
 191                 next = pmd_addr_end(addr, end);
 192
 193                 /*
 194                  * Automatic NUMA balancing walks the tables with mmap_sem
 195                  * held for read. It's possible a parallel update to occur
 196                  * between pmd_trans_huge() and a pmd_none_or_clear_bad()
 197                  * check leading to a false positive and clearing.
 198                  * Hence, it's necessary to atomically read the PMD value
 199                  * for all the checks.
 200                  */
 201                 if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) &&
 202                      pmd_none_or_clear_bad_unless_trans_huge(pmd))
 203                         goto next;
 204
 205                 /* invoke the mmu notifier if the pmd is populated */
 206                 if (!mni_start) {
 207                         mni_start = addr;
 208                         mmu_notifier_invalidate_range_start(mm, mni_start, end);
 209                 }
 210
 211                 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
 212                         if (next - addr != HPAGE_PMD_SIZE) {
 213                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
 214                         } else {
 215                                 int nr_ptes = change_huge_pmd(vma, pmd, addr,
 216                                                 newprot, prot_numa);
 217
 218                                 if (nr_ptes) {
 219                                         if (nr_ptes == HPAGE_PMD_NR) {
 220                                                 pages += HPAGE_PMD_NR;
 221                                                 nr_huge_updates++;
 222                                         }
 223
 224                                         /* huge pmd was handled */
 225                                         goto next;
 226                                 }
 227                         }
 228                         /* fall through, the trans huge pmd just split */
 229                 }
 230                 this_pages = change_pte_range(vma, pmd, addr, next, newprot,
 231                                  dirty_accountable, prot_numa);
 232                 pages += this_pages;
 233 next:
 234                 cond_resched();
 235         } while (pmd++, addr = next, addr != end);
 236
 237         if (mni_start)
 238                 mmu_notifier_invalidate_range_end(mm, mni_start, end);
 239
 240         if (nr_huge_updates)
 241                 count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates);
 242         return pages;
 243 }
 244
 245 static inline unsigned long change_pud_range(struct vm_area_struct *vma,
 246                 p4d_t *p4d, unsigned long addr, unsigned long end,
 247                 pgprot_t newprot, int dirty_accountable, int prot_numa)
 248 {
 249         pud_t *pud;
 250         unsigned long next;
 251         unsigned long pages = 0;
 252
 253         pud = pud_offset(p4d, addr);
 254         do {
 255                 next = pud_addr_end(addr, end);
 256                 if (pud_none_or_clear_bad(pud))
 257                         continue;
 258                 pages += change_pmd_range(vma, pud, addr, next, newprot,
 259                                  dirty_accountable, prot_numa);
 260         } while (pud++, addr = next, addr != end);
 261
 262         return pages;
 263 }
 264
 265 static inline unsigned long change_p4d_range(struct vm_area_struct *vma,
 266                 pgd_t *pgd, unsigned long addr, unsigned long end,
 267                 pgprot_t newprot, int dirty_accountable, int prot_numa)
 268 {
 269         p4d_t *p4d;
 270         unsigned long next;
 271         unsigned long pages = 0;
 272
 273         p4d = p4d_offset(pgd, addr);
 274         do {
 275                 next = p4d_addr_end(addr, end);
 276                 if (p4d_none_or_clear_bad(p4d))
 277                         continue;
 278                 pages += change_pud_range(vma, p4d, addr, next, newprot,
 279                                  dirty_accountable, prot_numa);
 280         } while (p4d++, addr = next, addr != end);
 281
 282         return pages;
 283 }
 284
 285 static unsigned long change_protection_range(struct vm_area_struct *vma,
 286                 unsigned long addr, unsigned long end, pgprot_t newprot,
 287                 int dirty_accountable, int prot_numa)
 288 {
 289         struct mm_struct *mm = vma->vm_mm;
 290         pgd_t *pgd;
 291         unsigned long next;
 292         unsigned long start = addr;
 293         unsigned long pages = 0;
 294
 295         BUG_ON(addr >= end);
 296         pgd = pgd_offset(mm, addr);
 297         flush_cache_range(vma, addr, end);
 298         inc_tlb_flush_pending(mm);
 299         do {
 300                 next = pgd_addr_end(addr, end);
 301                 if (pgd_none_or_clear_bad(pgd))
 302                         continue;
 303                 pages += change_p4d_range(vma, pgd, addr, next, newprot,
 304                                  dirty_accountable, prot_numa);
 305         } while (pgd++, addr = next, addr != end);
 306
 307         /* Only flush the TLB if we actually modified any entries: */
 308         if (pages)
 309                 flush_tlb_range(vma, start, end);
 310         dec_tlb_flush_pending(mm);
 311
 312         return pages;
 313 }
 314
 315 unsigned long change_protection(struct vm_area_struct *vma, unsigned long start,
 316                        unsigned long end, pgprot_t newprot,
 317                        int dirty_accountable, int prot_numa)
 318 {
 319         unsigned long pages;
 320
 321         if (is_vm_hugetlb_page(vma))
 322                 pages = hugetlb_change_protection(vma, start, end, newprot);
 323         else
 324                 pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
 325
 326         return pages;
 327 }
 328
 329 static int prot_none_pte_entry(pte_t *pte, unsigned long addr,
 330                                unsigned long next, struct mm_walk *walk)
 331 {
 332         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
 333                 0 : -EACCES;
 334 }
 335
 336 static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask,
 337                                    unsigned long addr, unsigned long next,
 338                                    struct mm_walk *walk)
 339 {
 340         return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ?
 341                 0 : -EACCES;
 342 }
 343
 344 static int prot_none_test(unsigned long addr, unsigned long next,
 345                           struct mm_walk *walk)
 346 {
 347         return 0;
 348 }
 349
 350 static int prot_none_walk(struct vm_area_struct *vma, unsigned long start,
 351                            unsigned long end, unsigned long newflags)
 352 {
 353         pgprot_t new_pgprot = vm_get_page_prot(newflags);
 354         struct mm_walk prot_none_walk = {
 355                 .pte_entry = prot_none_pte_entry,
 356                 .hugetlb_entry = prot_none_hugetlb_entry,
 357                 .test_walk = prot_none_test,
 358                 .mm = current->mm,
 359                 .private = &new_pgprot,
 360         };
 361
 362         return walk_page_range(start, end, &prot_none_walk);
 363 }
 364
 365 int
 366 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 367         unsigned long start, unsigned long end, unsigned long newflags)
 368 {
 369         struct mm_struct *mm = vma->vm_mm;
 370         unsigned long oldflags = vma->vm_flags;
 371         long nrpages = (end - start) >> PAGE_SHIFT;
 372         unsigned long charged = 0;
 373         pgoff_t pgoff;
 374         int error;
 375         int dirty_accountable = 0;
 376
 377         if (newflags == oldflags) {
 378                 *pprev = vma;
 379                 return 0;
 380         }
 381
 382         /*
 383          * Do PROT_NONE PFN permission checks here when we can still
 384          * bail out without undoing a lot of state. This is a rather
 385          * uncommon case, so doesn't need to be very optimized.
 386          */
 387         if (arch_has_pfn_modify_check() &&
 388             (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
 389             (newflags & (VM_READ|VM_WRITE|VM_EXEC)) == 0) {
 390                 error = prot_none_walk(vma, start, end, newflags);
 391                 if (error)
 392                         return error;
 393         }
 394
 395         /*
 396          * If we make a private mapping writable we increase our commit;
 397          * but (without finer accounting) cannot reduce our commit if we
 398          * make it unwritable again. hugetlb mapping were accounted for
 399          * even if read-only so there is no need to account for them here
 400          */
 401         if (newflags & VM_WRITE) {
 402                 /* Check space limits when area turns into data. */
 403                 if (!may_expand_vm(mm, newflags, nrpages) &&
 404                                 may_expand_vm(mm, oldflags, nrpages))
 405                         return -ENOMEM;
 406                 if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB|
 407                                                 VM_SHARED|VM_NORESERVE))) {
 408                         charged = nrpages;
 409                         if (security_vm_enough_memory_mm(mm, charged))
 410                                 return -ENOMEM;
 411                         newflags |= VM_ACCOUNT;
 412                 }
 413         }
 414
 415         /*
 416          * First try to merge with previous and/or next vma.
 417          */
 418         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 419         *pprev = vma_merge(mm, *pprev, start, end, newflags,
 420                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
 421                            vma->vm_userfaultfd_ctx);
 422         if (*pprev) {
 423                 vma = *pprev;
 424                 VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY);
 425                 goto success;
 426         }
 427
 428         *pprev = vma;
 429
 430         if (start != vma->vm_start) {
 431                 error = split_vma(mm, vma, start, 1);
 432                 if (error)
 433                         goto fail;
 434         }
 435
 436         if (end != vma->vm_end) {
 437                 error = split_vma(mm, vma, end, 0);
 438                 if (error)
 439                         goto fail;
 440         }
 441
 442 success:
 443         /*
 444          * vm_flags and vm_page_prot are protected by the mmap_sem
 445          * held in write mode.
 446          */
 447         vma->vm_flags = newflags;
 448         dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot);
 449         vma_set_page_prot(vma);
 450
 451         change_protection(vma, start, end, vma->vm_page_prot,
 452                           dirty_accountable, 0);
 453
 454         /*
 455          * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
 456          * fault on access.
 457          */
 458         if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
 459                         (newflags & VM_WRITE)) {
 460                 populate_vma_page_range(vma, start, end, NULL);
 461         }
 462
 463         vm_stat_account(mm, oldflags, -nrpages);
 464         vm_stat_account(mm, newflags, nrpages);
 465         perf_event_mmap(vma);
 466         return 0;
 467
 468 fail:
 469         vm_unacct_memory(charged);
 470         return error;
 471 }
 472
 473 /*
 474  * pkey==-1 when doing a legacy mprotect()
 475  */
 476 static int do_mprotect_pkey(unsigned long start, size_t len,
 477                 unsigned long prot, int pkey)
 478 {
 479         unsigned long nstart, end, tmp, reqprot;
 480         struct vm_area_struct *vma, *prev;
 481         int error = -EINVAL;
 482         const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
 483         const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
 484                                 (prot & PROT_READ);
 485
 486         prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
 487         if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
 488                 return -EINVAL;
 489
 490         if (start & ~PAGE_MASK)
 491                 return -EINVAL;
 492         if (!len)
 493                 return 0;
 494         len = PAGE_ALIGN(len);
 495         end = start + len;
 496         if (end <= start)
 497                 return -ENOMEM;
 498         if (!arch_validate_prot(prot))
 499                 return -EINVAL;
 500
 501         reqprot = prot;
 502
 503         if (down_write_killable(&current->mm->mmap_sem))
 504                 return -EINTR;
 505
 506         /*
 507          * If userspace did not allocate the pkey, do not let
 508          * them use it here.
 509          */
 510         error = -EINVAL;
 511         if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
 512                 goto out;
 513
 514         vma = find_vma(current->mm, start);
 515         error = -ENOMEM;
 516         if (!vma)
 517                 goto out;
 518         prev = vma->vm_prev;
 519         if (unlikely(grows & PROT_GROWSDOWN)) {
 520                 if (vma->vm_start >= end)
 521                         goto out;
 522                 start = vma->vm_start;
 523                 error = -EINVAL;
 524                 if (!(vma->vm_flags & VM_GROWSDOWN))
 525                         goto out;
 526         } else {
 527                 if (vma->vm_start > start)
 528                         goto out;
 529                 if (unlikely(grows & PROT_GROWSUP)) {
 530                         end = vma->vm_end;
 531                         error = -EINVAL;
 532                         if (!(vma->vm_flags & VM_GROWSUP))
 533                                 goto out;
 534                 }
 535         }
 536         if (start > vma->vm_start)
 537                 prev = vma;
 538
 539         for (nstart = start ; ; ) {
 540                 unsigned long mask_off_old_flags;
 541                 unsigned long newflags;
 542                 int new_vma_pkey;
 543
 544                 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
 545
 546                 /* Does the application expect PROT_READ to imply PROT_EXEC */
 547                 if (rier && (vma->vm_flags & VM_MAYEXEC))
 548                         prot |= PROT_EXEC;
 549
 550                 /*
 551                  * Each mprotect() call explicitly passes r/w/x permissions.
 552                  * If a permission is not passed to mprotect(), it must be
 553                  * cleared from the VMA.
 554                  */
 555                 mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC |
 556                                         ARCH_VM_PKEY_FLAGS;
 557
 558                 new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey);
 559                 newflags = calc_vm_prot_bits(prot, new_vma_pkey);
 560                 newflags |= (vma->vm_flags & ~mask_off_old_flags);
 561
 562                 /* newflags >> 4 shift VM_MAY% in place of VM_% */
 563                 if ((newflags & ~(newflags >> 4)) & (VM_READ | VM_WRITE | VM_EXEC)) {
 564                         error = -EACCES;
 565                         goto out;
 566                 }
 567
 568                 error = security_file_mprotect(vma, reqprot, prot);
 569                 if (error)
 570                         goto out;
 571
 572                 tmp = vma->vm_end;
 573                 if (tmp > end)
 574                         tmp = end;
 575                 error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
 576                 if (error)
 577                         goto out;
 578                 nstart = tmp;
 579
 580                 if (nstart < prev->vm_end)
 581                         nstart = prev->vm_end;
 582                 if (nstart >= end)
 583                         goto out;
 584
 585                 vma = prev->vm_next;
 586                 if (!vma || vma->vm_start != nstart) {
 587                         error = -ENOMEM;
 588                         goto out;
 589                 }
 590                 prot = reqprot;
 591         }
 592 out:
 593         up_write(&current->mm->mmap_sem);
 594         return error;
 595 }
 596
 597 SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
 598                 unsigned long, prot)
 599 {
 600         return do_mprotect_pkey(start, len, prot, -1);
 601 }
 602
 603 #ifdef CONFIG_ARCH_HAS_PKEYS
 604
 605 SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len,
 606                 unsigned long, prot, int, pkey)
 607 {
 608         return do_mprotect_pkey(start, len, prot, pkey);
 609 }
 610
 611 SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val)
 612 {
 613         int pkey;
 614         int ret;
 615
 616         /* No flags supported yet. */
 617         if (flags)
 618                 return -EINVAL;
 619         /* check for unsupported init values */
 620         if (init_val & ~PKEY_ACCESS_MASK)
 621                 return -EINVAL;
 622
 623         down_write(&current->mm->mmap_sem);
 624         pkey = mm_pkey_alloc(current->mm);
 625
 626         ret = -ENOSPC;
 627         if (pkey == -1)
 628                 goto out;
 629
 630         ret = arch_set_user_pkey_access(current, pkey, init_val);
 631         if (ret) {
 632                 mm_pkey_free(current->mm, pkey);
 633                 goto out;
 634         }
 635         ret = pkey;
 636 out:
 637         up_write(&current->mm->mmap_sem);
 638         return ret;
 639 }
 640
 641 SYSCALL_DEFINE1(pkey_free, int, pkey)
 642 {
 643         int ret;
 644
 645         down_write(&current->mm->mmap_sem);
 646         ret = mm_pkey_free(current->mm, pkey);
 647         up_write(&current->mm->mmap_sem);
 648
 649         /*
 650          * We could provie warnings or errors if any VMA still
 651          * has the pkey set here.
 652          */
 653         return ret;
 654 }
 655
 656 #endif /* CONFIG_ARCH_HAS_PKEYS */