Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 670 insertions, 0 deletions

diff --git a/mm/mprotect.c b/mm/mprotect.c
new file mode 100644
index 000000000..86837f250
--- /dev/null
+++ b/mm/mprotect.c
@@ -0,0 +1,670 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  mm/mprotect.c
+ *
+ *  (C) Copyright 1994 Linus Torvalds
+ *  (C) Copyright 2002 Christoph Hellwig
+ *
+ *  Address space accounting code	<alan@lxorguk.ukuu.org.uk>
+ *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
+ */
+
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/shm.h>
+#include <linux/mman.h>
+#include <linux/fs.h>
+#include <linux/highmem.h>
+#include <linux/security.h>
+#include <linux/mempolicy.h>
+#include <linux/personality.h>
+#include <linux/syscalls.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
+#include <linux/migrate.h>
+#include <linux/perf_event.h>
+#include <linux/pkeys.h>
+#include <linux/ksm.h>
+#include <linux/uaccess.h>
+#include <linux/mm_inline.h>
+#include <asm/pgtable.h>
+#include <asm/cacheflush.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+
+#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,
+		int dirty_accountable, int prot_numa)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pte_t *pte, oldpte;
+	spinlock_t *ptl;
+	unsigned long pages = 0;
+	int target_node = NUMA_NO_NODE;
+
+	/*
+	 * Can be called with only the mmap_sem 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_sem 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;
+
+				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_mapcount(page) != 1)
+					continue;
+
+				/*
+				 * While migration can move some dirty pages,
+				 * it cannot move them all from MIGRATE_ASYNC
+				 * context.
+				 */
+				if (page_is_file_cache(page) && PageDirty(page))
+					continue;
+
+				/* Avoid TLB flush if possible */
+				if (pte_protnone(oldpte))
+					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;
+			}
+
+			ptent = ptep_modify_prot_start(mm, addr, pte);
+			ptent = pte_modify(ptent, newprot);
+			if (preserve_write)
+				ptent = pte_mk_savedwrite(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(mm, addr, pte, ptent);
+			pages++;
+		} else if (IS_ENABLED(CONFIG_MIGRATION)) {
+			swp_entry_t entry = pte_to_swp_entry(oldpte);
+
+			if (is_write_migration_entry(entry)) {
+				pte_t newpte;
+				/*
+				 * 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);
+				set_pte_at(mm, addr, pte, newpte);
+
+				pages++;
+			}
+
+			if (is_write_device_private_entry(entry)) {
+				pte_t newpte;
+
+				/*
+				 * We do not preserve soft-dirtiness. See
+				 * copy_one_pte() for explanation.
+				 */
+				make_device_private_entry_read(&entry);
+				newpte = swp_entry_to_pte(entry);
+				set_pte_at(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, int dirty_accountable, int prot_numa)
+{
+	pmd_t *pmd;
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long next;
+	unsigned long pages = 0;
+	unsigned long nr_huge_updates = 0;
+	unsigned long mni_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_sem
+		 * 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 (!mni_start) {
+			mni_start = addr;
+			mmu_notifier_invalidate_range_start(mm, mni_start, end);
+		}
+
+		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, prot_numa);
+
+				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,
+				 dirty_accountable, prot_numa);
+		pages += this_pages;
+next:
+		cond_resched();
+	} while (pmd++, addr = next, addr != end);
+
+	if (mni_start)
+		mmu_notifier_invalidate_range_end(mm, mni_start, end);
+
+	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, int dirty_accountable, int prot_numa)
+{
+	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,
+				 dirty_accountable, prot_numa);
+	} 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, int dirty_accountable, int prot_numa)
+{
+	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,
+				 dirty_accountable, prot_numa);
+	} 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,
+		int dirty_accountable, int prot_numa)
+{
+	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,
+				 dirty_accountable, prot_numa);
+	} 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,
+		       int dirty_accountable, int prot_numa)
+{
+	unsigned long pages;
+
+	if (is_vm_hugetlb_page(vma))
+		pages = hugetlb_change_protection(vma, start, end, newprot);
+	else
+		pages = change_protection_range(vma, start, end, newprot, dirty_accountable, prot_numa);
+
+	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 int prot_none_walk(struct vm_area_struct *vma, unsigned long start,
+			   unsigned long end, unsigned long newflags)
+{
+	pgprot_t new_pgprot = vm_get_page_prot(newflags);
+	struct mm_walk prot_none_walk = {
+		.pte_entry = prot_none_pte_entry,
+		.hugetlb_entry = prot_none_hugetlb_entry,
+		.test_walk = prot_none_test,
+		.mm = current->mm,
+		.private = &new_pgprot,
+	};
+
+	return walk_page_range(start, end, &prot_none_walk);
+}
+
+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_READ|VM_WRITE|VM_EXEC)) == 0) {
+		error = prot_none_walk(vma, start, end, newflags);
+		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_sem
+	 * 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, 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);
+
+	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 (down_write_killable(&current->mm->mmap_sem))
+		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_READ | VM_WRITE | VM_EXEC)) {
+			error = -EACCES;
+			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:
+	up_write(&current->mm->mmap_sem);
+	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;
+
+	down_write(&current->mm->mmap_sem);
+	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:
+	up_write(&current->mm->mmap_sem);
+	return ret;
+}
+
+SYSCALL_DEFINE1(pkey_free, int, pkey)
+{
+	int ret;
+
+	down_write(&current->mm->mmap_sem);
+	ret = mm_pkey_free(current->mm, pkey);
+	up_write(&current->mm->mmap_sem);
+
+	/*
+	 * We could provie warnings or errors if any VMA still
+	 * has the pkey set here.
+	 */
+	return ret;
+}
+
+#endif /* CONFIG_ARCH_HAS_PKEYS */