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-rw-r--r--mm/mprotect.c433
1 files changed, 433 insertions, 0 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
new file mode 100644
index 000000000..88584838e
--- /dev/null
+++ b/mm/mprotect.c
@@ -0,0 +1,433 @@
+/*
+ * 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/ksm.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+
+/*
+ * For a prot_numa update we only hold mmap_sem for read so there is a
+ * potential race with faulting where a pmd was temporarily none. This
+ * function checks for a transhuge pmd under the appropriate lock. It
+ * returns a pte if it was successfully locked or NULL if it raced with
+ * a transhuge insertion.
+ */
+static pte_t *lock_pte_protection(struct vm_area_struct *vma, pmd_t *pmd,
+ unsigned long addr, int prot_numa, spinlock_t **ptl)
+{
+ pte_t *pte;
+ spinlock_t *pmdl;
+
+ /* !prot_numa is protected by mmap_sem held for write */
+ if (!prot_numa)
+ return pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
+
+ pmdl = pmd_lock(vma->vm_mm, pmd);
+ if (unlikely(pmd_trans_huge(*pmd) || pmd_none(*pmd))) {
+ spin_unlock(pmdl);
+ return NULL;
+ }
+
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, ptl);
+ spin_unlock(pmdl);
+ return pte;
+}
+
+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;
+
+ pte = lock_pte_protection(vma, pmd, addr, prot_numa, &ptl);
+ if (!pte)
+ return 0;
+
+ 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;
+
+ /* Avoid TLB flush if possible */
+ if (pte_protnone(oldpte))
+ continue;
+ }
+
+ ptent = ptep_modify_prot_start(mm, addr, pte);
+ ptent = pte_modify(ptent, newprot);
+ if (preserve_write)
+ ptent = pte_mkwrite(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++;
+ }
+ }
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ arch_leave_lazy_mmu_mode();
+ pte_unmap_unlock(pte - 1, ptl);
+
+ return pages;
+}
+
+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);
+ if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
+ continue;
+
+ /* 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 (pmd_trans_huge(*pmd)) {
+ if (next - addr != HPAGE_PMD_SIZE)
+ split_huge_page_pmd(vma, addr, pmd);
+ 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 */
+ continue;
+ }
+ }
+ /* 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;
+ } 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,
+ pgd_t *pgd, 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(pgd, 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 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);
+ set_tlb_flush_pending(mm);
+ do {
+ next = pgd_addr_end(addr, end);
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ pages += change_pud_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);
+ clear_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;
+}
+
+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;
+ }
+
+ /*
+ * 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) {
+ 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));
+ if (*pprev) {
+ vma = *pprev;
+ 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_set_page_prot(vma);
+
+ change_protection(vma, start, end, vma->vm_page_prot,
+ dirty_accountable, 0);
+
+ vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
+ vm_stat_account(mm, newflags, vma->vm_file, nrpages);
+ perf_event_mmap(vma);
+ return 0;
+
+fail:
+ vm_unacct_memory(charged);
+ return error;
+}
+
+SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len,
+ unsigned long, prot)
+{
+ unsigned long vm_flags, nstart, end, tmp, reqprot;
+ struct vm_area_struct *vma, *prev;
+ int error = -EINVAL;
+ const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
+ 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))
+ return -EINVAL;
+
+ reqprot = prot;
+ /*
+ * Does the application expect PROT_READ to imply PROT_EXEC:
+ */
+ if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+ prot |= PROT_EXEC;
+
+ vm_flags = calc_vm_prot_bits(prot);
+
+ down_write(&current->mm->mmap_sem);
+
+ 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 newflags;
+
+ /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
+
+ newflags = vm_flags;
+ newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC));
+
+ /* 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;
+ }
+ }
+out:
+ up_write(&current->mm->mmap_sem);
+ return error;
+}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-22 08:06:36 +0000