From 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 12:05:51 +0200 Subject: Adding upstream version 5.10.209. Signed-off-by: Daniel Baumann --- mm/mprotect.c | 700 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 700 insertions(+) create mode 100644 mm/mprotect.c (limited to 'mm/mprotect.c') diff --git a/mm/mprotect.c b/mm/mprotect.c new file mode 100644 index 000000000..7ea0aee0c --- /dev/null +++ b/mm/mprotect.c @@ -0,0 +1,700 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * mm/mprotect.c + * + * (C) Copyright 1994 Linus Torvalds + * (C) Copyright 2002 Christoph Hellwig + * + * Address space accounting code + * (C) Copyright 2002 Red Hat Inc, All Rights Reserved + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "internal.h" + +static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, + unsigned long addr, unsigned long end, pgprot_t newprot, + unsigned long cp_flags) +{ + pte_t *pte, oldpte; + spinlock_t *ptl; + unsigned long pages = 0; + int target_node = NUMA_NO_NODE; + bool dirty_accountable = cp_flags & MM_CP_DIRTY_ACCT; + bool prot_numa = cp_flags & MM_CP_PROT_NUMA; + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + + /* + * Can be called with only the mmap_lock for reading by + * prot_numa so we must check the pmd isn't constantly + * changing from under us from pmd_none to pmd_trans_huge + * and/or the other way around. + */ + if (pmd_trans_unstable(pmd)) + return 0; + + /* + * The pmd points to a regular pte so the pmd can't change + * from under us even if the mmap_lock is only hold for + * reading. + */ + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + + /* Get target node for single threaded private VMAs */ + if (prot_numa && !(vma->vm_flags & VM_SHARED) && + atomic_read(&vma->vm_mm->mm_users) == 1) + target_node = numa_node_id(); + + flush_tlb_batched_pending(vma->vm_mm); + arch_enter_lazy_mmu_mode(); + do { + oldpte = *pte; + if (pte_present(oldpte)) { + pte_t ptent; + bool preserve_write = prot_numa && pte_write(oldpte); + + /* + * Avoid trapping faults against the zero or KSM + * pages. See similar comment in change_huge_pmd. + */ + if (prot_numa) { + struct page *page; + + /* Avoid TLB flush if possible */ + if (pte_protnone(oldpte)) + continue; + + page = vm_normal_page(vma, addr, oldpte); + if (!page || PageKsm(page)) + continue; + + /* Also skip shared copy-on-write pages */ + if (is_cow_mapping(vma->vm_flags) && + page_count(page) != 1) + continue; + + /* + * While migration can move some dirty pages, + * it cannot move them all from MIGRATE_ASYNC + * context. + */ + if (page_is_file_lru(page) && PageDirty(page)) + continue; + + /* + * Don't mess with PTEs if page is already on the node + * a single-threaded process is running on. + */ + if (target_node == page_to_nid(page)) + continue; + } + + oldpte = ptep_modify_prot_start(vma, addr, pte); + ptent = pte_modify(oldpte, newprot); + if (preserve_write) + ptent = pte_mk_savedwrite(ptent); + + if (uffd_wp) { + ptent = pte_wrprotect(ptent); + ptent = pte_mkuffd_wp(ptent); + } else if (uffd_wp_resolve) { + /* + * Leave the write bit to be handled + * by PF interrupt handler, then + * things like COW could be properly + * handled. + */ + ptent = pte_clear_uffd_wp(ptent); + } + + /* Avoid taking write faults for known dirty pages */ + if (dirty_accountable && pte_dirty(ptent) && + (pte_soft_dirty(ptent) || + !(vma->vm_flags & VM_SOFTDIRTY))) { + ptent = pte_mkwrite(ptent); + } + ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent); + pages++; + } else if (is_swap_pte(oldpte)) { + swp_entry_t entry = pte_to_swp_entry(oldpte); + pte_t newpte; + + if (is_write_migration_entry(entry)) { + /* + * A protection check is difficult so + * just be safe and disable write + */ + make_migration_entry_read(&entry); + newpte = swp_entry_to_pte(entry); + if (pte_swp_soft_dirty(oldpte)) + newpte = pte_swp_mksoft_dirty(newpte); + if (pte_swp_uffd_wp(oldpte)) + newpte = pte_swp_mkuffd_wp(newpte); + } else if (is_write_device_private_entry(entry)) { + /* + * We do not preserve soft-dirtiness. See + * copy_one_pte() for explanation. + */ + make_device_private_entry_read(&entry); + newpte = swp_entry_to_pte(entry); + if (pte_swp_uffd_wp(oldpte)) + newpte = pte_swp_mkuffd_wp(newpte); + } else { + newpte = oldpte; + } + + if (uffd_wp) + newpte = pte_swp_mkuffd_wp(newpte); + else if (uffd_wp_resolve) + newpte = pte_swp_clear_uffd_wp(newpte); + + if (!pte_same(oldpte, newpte)) { + set_pte_at(vma->vm_mm, addr, pte, newpte); + pages++; + } + } + } while (pte++, addr += PAGE_SIZE, addr != end); + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(pte - 1, ptl); + + return pages; +} + +/* + * Used when setting automatic NUMA hinting protection where it is + * critical that a numa hinting PMD is not confused with a bad PMD. + */ +static inline int pmd_none_or_clear_bad_unless_trans_huge(pmd_t *pmd) +{ + pmd_t pmdval = pmd_read_atomic(pmd); + + /* See pmd_none_or_trans_huge_or_clear_bad for info on barrier */ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + barrier(); +#endif + + if (pmd_none(pmdval)) + return 1; + if (pmd_trans_huge(pmdval)) + return 0; + if (unlikely(pmd_bad(pmdval))) { + pmd_clear_bad(pmd); + return 1; + } + + return 0; +} + +static inline unsigned long change_pmd_range(struct vm_area_struct *vma, + pud_t *pud, unsigned long addr, unsigned long end, + pgprot_t newprot, unsigned long cp_flags) +{ + pmd_t *pmd; + unsigned long next; + unsigned long pages = 0; + unsigned long nr_huge_updates = 0; + struct mmu_notifier_range range; + + range.start = 0; + + pmd = pmd_offset(pud, addr); + do { + unsigned long this_pages; + + next = pmd_addr_end(addr, end); + + /* + * Automatic NUMA balancing walks the tables with mmap_lock + * held for read. It's possible a parallel update to occur + * between pmd_trans_huge() and a pmd_none_or_clear_bad() + * check leading to a false positive and clearing. + * Hence, it's necessary to atomically read the PMD value + * for all the checks. + */ + if (!is_swap_pmd(*pmd) && !pmd_devmap(*pmd) && + pmd_none_or_clear_bad_unless_trans_huge(pmd)) + goto next; + + /* invoke the mmu notifier if the pmd is populated */ + if (!range.start) { + mmu_notifier_range_init(&range, + MMU_NOTIFY_PROTECTION_VMA, 0, + vma, vma->vm_mm, addr, end); + mmu_notifier_invalidate_range_start(&range); + } + + if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { + if (next - addr != HPAGE_PMD_SIZE) { + __split_huge_pmd(vma, pmd, addr, false, NULL); + } else { + int nr_ptes = change_huge_pmd(vma, pmd, addr, + newprot, cp_flags); + + if (nr_ptes) { + if (nr_ptes == HPAGE_PMD_NR) { + pages += HPAGE_PMD_NR; + nr_huge_updates++; + } + + /* huge pmd was handled */ + goto next; + } + } + /* fall through, the trans huge pmd just split */ + } + this_pages = change_pte_range(vma, pmd, addr, next, newprot, + cp_flags); + pages += this_pages; +next: + cond_resched(); + } while (pmd++, addr = next, addr != end); + + if (range.start) + mmu_notifier_invalidate_range_end(&range); + + if (nr_huge_updates) + count_vm_numa_events(NUMA_HUGE_PTE_UPDATES, nr_huge_updates); + return pages; +} + +static inline unsigned long change_pud_range(struct vm_area_struct *vma, + p4d_t *p4d, unsigned long addr, unsigned long end, + pgprot_t newprot, unsigned long cp_flags) +{ + pud_t *pud; + unsigned long next; + unsigned long pages = 0; + + pud = pud_offset(p4d, addr); + do { + next = pud_addr_end(addr, end); + if (pud_none_or_clear_bad(pud)) + continue; + pages += change_pmd_range(vma, pud, addr, next, newprot, + cp_flags); + } while (pud++, addr = next, addr != end); + + return pages; +} + +static inline unsigned long change_p4d_range(struct vm_area_struct *vma, + pgd_t *pgd, unsigned long addr, unsigned long end, + pgprot_t newprot, unsigned long cp_flags) +{ + p4d_t *p4d; + unsigned long next; + unsigned long pages = 0; + + p4d = p4d_offset(pgd, addr); + do { + next = p4d_addr_end(addr, end); + if (p4d_none_or_clear_bad(p4d)) + continue; + pages += change_pud_range(vma, p4d, addr, next, newprot, + cp_flags); + } while (p4d++, addr = next, addr != end); + + return pages; +} + +static unsigned long change_protection_range(struct vm_area_struct *vma, + unsigned long addr, unsigned long end, pgprot_t newprot, + unsigned long cp_flags) +{ + struct mm_struct *mm = vma->vm_mm; + pgd_t *pgd; + unsigned long next; + unsigned long start = addr; + unsigned long pages = 0; + + BUG_ON(addr >= end); + pgd = pgd_offset(mm, addr); + flush_cache_range(vma, addr, end); + inc_tlb_flush_pending(mm); + do { + next = pgd_addr_end(addr, end); + if (pgd_none_or_clear_bad(pgd)) + continue; + pages += change_p4d_range(vma, pgd, addr, next, newprot, + cp_flags); + } while (pgd++, addr = next, addr != end); + + /* Only flush the TLB if we actually modified any entries: */ + if (pages) + flush_tlb_range(vma, start, end); + dec_tlb_flush_pending(mm); + + return pages; +} + +unsigned long change_protection(struct vm_area_struct *vma, unsigned long start, + unsigned long end, pgprot_t newprot, + unsigned long cp_flags) +{ + unsigned long pages; + + BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL); + + if (is_vm_hugetlb_page(vma)) + pages = hugetlb_change_protection(vma, start, end, newprot); + else + pages = change_protection_range(vma, start, end, newprot, + cp_flags); + + return pages; +} + +static int prot_none_pte_entry(pte_t *pte, unsigned long addr, + unsigned long next, struct mm_walk *walk) +{ + return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ? + 0 : -EACCES; +} + +static int prot_none_hugetlb_entry(pte_t *pte, unsigned long hmask, + unsigned long addr, unsigned long next, + struct mm_walk *walk) +{ + return pfn_modify_allowed(pte_pfn(*pte), *(pgprot_t *)(walk->private)) ? + 0 : -EACCES; +} + +static int prot_none_test(unsigned long addr, unsigned long next, + struct mm_walk *walk) +{ + return 0; +} + +static const struct mm_walk_ops prot_none_walk_ops = { + .pte_entry = prot_none_pte_entry, + .hugetlb_entry = prot_none_hugetlb_entry, + .test_walk = prot_none_test, +}; + +int +mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, + unsigned long start, unsigned long end, unsigned long newflags) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long oldflags = vma->vm_flags; + long nrpages = (end - start) >> PAGE_SHIFT; + unsigned long charged = 0; + pgoff_t pgoff; + int error; + int dirty_accountable = 0; + + if (newflags == oldflags) { + *pprev = vma; + return 0; + } + + /* + * Do PROT_NONE PFN permission checks here when we can still + * bail out without undoing a lot of state. This is a rather + * uncommon case, so doesn't need to be very optimized. + */ + if (arch_has_pfn_modify_check() && + (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) && + (newflags & VM_ACCESS_FLAGS) == 0) { + pgprot_t new_pgprot = vm_get_page_prot(newflags); + + error = walk_page_range(current->mm, start, end, + &prot_none_walk_ops, &new_pgprot); + if (error) + return error; + } + + /* + * If we make a private mapping writable we increase our commit; + * but (without finer accounting) cannot reduce our commit if we + * make it unwritable again. hugetlb mapping were accounted for + * even if read-only so there is no need to account for them here + */ + if (newflags & VM_WRITE) { + /* Check space limits when area turns into data. */ + if (!may_expand_vm(mm, newflags, nrpages) && + may_expand_vm(mm, oldflags, nrpages)) + return -ENOMEM; + if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_HUGETLB| + VM_SHARED|VM_NORESERVE))) { + charged = nrpages; + if (security_vm_enough_memory_mm(mm, charged)) + return -ENOMEM; + newflags |= VM_ACCOUNT; + } + } + + /* + * First try to merge with previous and/or next vma. + */ + pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); + *pprev = vma_merge(mm, *pprev, start, end, newflags, + vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), + vma->vm_userfaultfd_ctx); + if (*pprev) { + vma = *pprev; + VM_WARN_ON((vma->vm_flags ^ newflags) & ~VM_SOFTDIRTY); + goto success; + } + + *pprev = vma; + + if (start != vma->vm_start) { + error = split_vma(mm, vma, start, 1); + if (error) + goto fail; + } + + if (end != vma->vm_end) { + error = split_vma(mm, vma, end, 0); + if (error) + goto fail; + } + +success: + /* + * vm_flags and vm_page_prot are protected by the mmap_lock + * held in write mode. + */ + vma->vm_flags = newflags; + dirty_accountable = vma_wants_writenotify(vma, vma->vm_page_prot); + vma_set_page_prot(vma); + + change_protection(vma, start, end, vma->vm_page_prot, + dirty_accountable ? MM_CP_DIRTY_ACCT : 0); + + /* + * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major + * fault on access. + */ + if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && + (newflags & VM_WRITE)) { + populate_vma_page_range(vma, start, end, NULL); + } + + vm_stat_account(mm, oldflags, -nrpages); + vm_stat_account(mm, newflags, nrpages); + perf_event_mmap(vma); + return 0; + +fail: + vm_unacct_memory(charged); + return error; +} + +/* + * pkey==-1 when doing a legacy mprotect() + */ +static int do_mprotect_pkey(unsigned long start, size_t len, + unsigned long prot, int pkey) +{ + unsigned long nstart, end, tmp, reqprot; + struct vm_area_struct *vma, *prev; + int error = -EINVAL; + const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP); + const bool rier = (current->personality & READ_IMPLIES_EXEC) && + (prot & PROT_READ); + + start = untagged_addr(start); + + prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP); + if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */ + return -EINVAL; + + if (start & ~PAGE_MASK) + return -EINVAL; + if (!len) + return 0; + len = PAGE_ALIGN(len); + end = start + len; + if (end <= start) + return -ENOMEM; + if (!arch_validate_prot(prot, start)) + return -EINVAL; + + reqprot = prot; + + if (mmap_write_lock_killable(current->mm)) + return -EINTR; + + /* + * If userspace did not allocate the pkey, do not let + * them use it here. + */ + error = -EINVAL; + if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey)) + goto out; + + vma = find_vma(current->mm, start); + error = -ENOMEM; + if (!vma) + goto out; + prev = vma->vm_prev; + if (unlikely(grows & PROT_GROWSDOWN)) { + if (vma->vm_start >= end) + goto out; + start = vma->vm_start; + error = -EINVAL; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto out; + } else { + if (vma->vm_start > start) + goto out; + if (unlikely(grows & PROT_GROWSUP)) { + end = vma->vm_end; + error = -EINVAL; + if (!(vma->vm_flags & VM_GROWSUP)) + goto out; + } + } + if (start > vma->vm_start) + prev = vma; + + for (nstart = start ; ; ) { + unsigned long mask_off_old_flags; + unsigned long newflags; + int new_vma_pkey; + + /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ + + /* Does the application expect PROT_READ to imply PROT_EXEC */ + if (rier && (vma->vm_flags & VM_MAYEXEC)) + prot |= PROT_EXEC; + + /* + * Each mprotect() call explicitly passes r/w/x permissions. + * If a permission is not passed to mprotect(), it must be + * cleared from the VMA. + */ + mask_off_old_flags = VM_READ | VM_WRITE | VM_EXEC | + VM_FLAGS_CLEAR; + + new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); + newflags = calc_vm_prot_bits(prot, new_vma_pkey); + newflags |= (vma->vm_flags & ~mask_off_old_flags); + + /* newflags >> 4 shift VM_MAY% in place of VM_% */ + if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { + error = -EACCES; + goto out; + } + + /* Allow architectures to sanity-check the new flags */ + if (!arch_validate_flags(newflags)) { + error = -EINVAL; + goto out; + } + + error = security_file_mprotect(vma, reqprot, prot); + if (error) + goto out; + + tmp = vma->vm_end; + if (tmp > end) + tmp = end; + error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); + if (error) + goto out; + nstart = tmp; + + if (nstart < prev->vm_end) + nstart = prev->vm_end; + if (nstart >= end) + goto out; + + vma = prev->vm_next; + if (!vma || vma->vm_start != nstart) { + error = -ENOMEM; + goto out; + } + prot = reqprot; + } +out: + mmap_write_unlock(current->mm); + return error; +} + +SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, + unsigned long, prot) +{ + return do_mprotect_pkey(start, len, prot, -1); +} + +#ifdef CONFIG_ARCH_HAS_PKEYS + +SYSCALL_DEFINE4(pkey_mprotect, unsigned long, start, size_t, len, + unsigned long, prot, int, pkey) +{ + return do_mprotect_pkey(start, len, prot, pkey); +} + +SYSCALL_DEFINE2(pkey_alloc, unsigned long, flags, unsigned long, init_val) +{ + int pkey; + int ret; + + /* No flags supported yet. */ + if (flags) + return -EINVAL; + /* check for unsupported init values */ + if (init_val & ~PKEY_ACCESS_MASK) + return -EINVAL; + + mmap_write_lock(current->mm); + pkey = mm_pkey_alloc(current->mm); + + ret = -ENOSPC; + if (pkey == -1) + goto out; + + ret = arch_set_user_pkey_access(current, pkey, init_val); + if (ret) { + mm_pkey_free(current->mm, pkey); + goto out; + } + ret = pkey; +out: + mmap_write_unlock(current->mm); + return ret; +} + +SYSCALL_DEFINE1(pkey_free, int, pkey) +{ + int ret; + + mmap_write_lock(current->mm); + ret = mm_pkey_free(current->mm, pkey); + mmap_write_unlock(current->mm); + + /* + * We could provie warnings or errors if any VMA still + * has the pkey set here. + */ + return ret; +} + +#endif /* CONFIG_ARCH_HAS_PKEYS */ -- cgit v1.2.3