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-rw-r--r--mm/mprotect.c896
1 files changed, 896 insertions, 0 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c
new file mode 100644
index 000000000..b94fbb45d
--- /dev/null
+++ b/mm/mprotect.c
@@ -0,0 +1,896 @@
+// 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/pagewalk.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 <linux/pgtable.h>
+#include <linux/sched/sysctl.h>
+#include <linux/userfaultfd_k.h>
+#include <linux/memory-tiers.h>
+#include <asm/cacheflush.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#include <asm/tlb.h>
+
+#include "internal.h"
+
+bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
+ pte_t pte)
+{
+ struct page *page;
+
+ if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE)))
+ return false;
+
+ /* Don't touch entries that are not even readable. */
+ if (pte_protnone(pte))
+ return false;
+
+ /* Do we need write faults for softdirty tracking? */
+ if (vma_soft_dirty_enabled(vma) && !pte_soft_dirty(pte))
+ return false;
+
+ /* Do we need write faults for uffd-wp tracking? */
+ if (userfaultfd_pte_wp(vma, pte))
+ return false;
+
+ if (!(vma->vm_flags & VM_SHARED)) {
+ /*
+ * Writable MAP_PRIVATE mapping: We can only special-case on
+ * exclusive anonymous pages, because we know that our
+ * write-fault handler similarly would map them writable without
+ * any additional checks while holding the PT lock.
+ */
+ page = vm_normal_page(vma, addr, pte);
+ return page && PageAnon(page) && PageAnonExclusive(page);
+ }
+
+ /*
+ * Writable MAP_SHARED mapping: "clean" might indicate that the FS still
+ * needs a real write-fault for writenotify
+ * (see vma_wants_writenotify()). If "dirty", the assumption is that the
+ * FS was already notified and we can simply mark the PTE writable
+ * just like the write-fault handler would do.
+ */
+ return pte_dirty(pte);
+}
+
+static long change_pte_range(struct mmu_gather *tlb,
+ 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;
+ long pages = 0;
+ int target_node = NUMA_NO_NODE;
+ 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;
+
+ tlb_change_page_size(tlb, PAGE_SIZE);
+ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+ if (!pte)
+ return -EAGAIN;
+
+ /* 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 = ptep_get(pte);
+ if (pte_present(oldpte)) {
+ pte_t ptent;
+
+ /*
+ * Avoid trapping faults against the zero or KSM
+ * pages. See similar comment in change_huge_pmd.
+ */
+ if (prot_numa) {
+ struct page *page;
+ int nid;
+ bool toptier;
+
+ /* Avoid TLB flush if possible */
+ if (pte_protnone(oldpte))
+ continue;
+
+ page = vm_normal_page(vma, addr, oldpte);
+ if (!page || is_zone_device_page(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.
+ */
+ nid = page_to_nid(page);
+ if (target_node == nid)
+ continue;
+ toptier = node_is_toptier(nid);
+
+ /*
+ * Skip scanning top tier node if normal numa
+ * balancing is disabled
+ */
+ if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
+ toptier)
+ continue;
+ if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
+ !toptier)
+ xchg_page_access_time(page,
+ jiffies_to_msecs(jiffies));
+ }
+
+ oldpte = ptep_modify_prot_start(vma, addr, pte);
+ ptent = pte_modify(oldpte, newprot);
+
+ if (uffd_wp)
+ ptent = pte_mkuffd_wp(ptent);
+ else if (uffd_wp_resolve)
+ ptent = pte_clear_uffd_wp(ptent);
+
+ /*
+ * In some writable, shared mappings, we might want
+ * to catch actual write access -- see
+ * vma_wants_writenotify().
+ *
+ * In all writable, private mappings, we have to
+ * properly handle COW.
+ *
+ * In both cases, we can sometimes still change PTEs
+ * writable and avoid the write-fault handler, for
+ * example, if a PTE is already dirty and no other
+ * COW or special handling is required.
+ */
+ if ((cp_flags & MM_CP_TRY_CHANGE_WRITABLE) &&
+ !pte_write(ptent) &&
+ can_change_pte_writable(vma, addr, ptent))
+ ptent = pte_mkwrite(ptent, vma);
+
+ ptep_modify_prot_commit(vma, addr, pte, oldpte, ptent);
+ if (pte_needs_flush(oldpte, ptent))
+ tlb_flush_pte_range(tlb, addr, PAGE_SIZE);
+ pages++;
+ } else if (is_swap_pte(oldpte)) {
+ swp_entry_t entry = pte_to_swp_entry(oldpte);
+ pte_t newpte;
+
+ if (is_writable_migration_entry(entry)) {
+ struct page *page = pfn_swap_entry_to_page(entry);
+
+ /*
+ * A protection check is difficult so
+ * just be safe and disable write
+ */
+ if (PageAnon(page))
+ entry = make_readable_exclusive_migration_entry(
+ swp_offset(entry));
+ else
+ entry = make_readable_migration_entry(swp_offset(entry));
+ newpte = swp_entry_to_pte(entry);
+ if (pte_swp_soft_dirty(oldpte))
+ newpte = pte_swp_mksoft_dirty(newpte);
+ } else if (is_writable_device_private_entry(entry)) {
+ /*
+ * We do not preserve soft-dirtiness. See
+ * copy_nonpresent_pte() for explanation.
+ */
+ entry = make_readable_device_private_entry(
+ swp_offset(entry));
+ newpte = swp_entry_to_pte(entry);
+ if (pte_swp_uffd_wp(oldpte))
+ newpte = pte_swp_mkuffd_wp(newpte);
+ } else if (is_writable_device_exclusive_entry(entry)) {
+ entry = make_readable_device_exclusive_entry(
+ swp_offset(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_pte_marker_entry(entry)) {
+ /*
+ * Ignore error swap entries unconditionally,
+ * because any access should sigbus anyway.
+ */
+ if (is_poisoned_swp_entry(entry))
+ continue;
+ /*
+ * If this is uffd-wp pte marker and we'd like
+ * to unprotect it, drop it; the next page
+ * fault will trigger without uffd trapping.
+ */
+ if (uffd_wp_resolve) {
+ pte_clear(vma->vm_mm, addr, pte);
+ pages++;
+ }
+ continue;
+ } 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++;
+ }
+ } else {
+ /* It must be an none page, or what else?.. */
+ WARN_ON_ONCE(!pte_none(oldpte));
+
+ /*
+ * Nobody plays with any none ptes besides
+ * userfaultfd when applying the protections.
+ */
+ if (likely(!uffd_wp))
+ continue;
+
+ if (userfaultfd_wp_use_markers(vma)) {
+ /*
+ * For file-backed mem, we need to be able to
+ * wr-protect a none pte, because even if the
+ * pte is none, the page/swap cache could
+ * exist. Doing that by install a marker.
+ */
+ set_pte_at(vma->vm_mm, addr, pte,
+ make_pte_marker(PTE_MARKER_UFFD_WP));
+ pages++;
+ }
+ }
+ } while (pte++, addr += PAGE_SIZE, addr != end);
+ arch_leave_lazy_mmu_mode();
+ pte_unmap_unlock(pte - 1, ptl);
+
+ return pages;
+}
+
+/*
+ * Return true if we want to split THPs into PTE mappings in change
+ * protection procedure, false otherwise.
+ */
+static inline bool
+pgtable_split_needed(struct vm_area_struct *vma, unsigned long cp_flags)
+{
+ /*
+ * pte markers only resides in pte level, if we need pte markers,
+ * we need to split. We cannot wr-protect shmem thp because file
+ * thp is handled differently when split by erasing the pmd so far.
+ */
+ return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
+}
+
+/*
+ * Return true if we want to populate pgtables in change protection
+ * procedure, false otherwise
+ */
+static inline bool
+pgtable_populate_needed(struct vm_area_struct *vma, unsigned long cp_flags)
+{
+ /* If not within ioctl(UFFDIO_WRITEPROTECT), then don't bother */
+ if (!(cp_flags & MM_CP_UFFD_WP))
+ return false;
+
+ /* Populate if the userfaultfd mode requires pte markers */
+ return userfaultfd_wp_use_markers(vma);
+}
+
+/*
+ * Populate the pgtable underneath for whatever reason if requested.
+ * When {pte|pmd|...}_alloc() failed we treat it the same way as pgtable
+ * allocation failures during page faults by kicking OOM and returning
+ * error.
+ */
+#define change_pmd_prepare(vma, pmd, cp_flags) \
+ ({ \
+ long err = 0; \
+ if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
+ if (pte_alloc(vma->vm_mm, pmd)) \
+ err = -ENOMEM; \
+ } \
+ err; \
+ })
+
+/*
+ * This is the general pud/p4d/pgd version of change_pmd_prepare(). We need to
+ * have separate change_pmd_prepare() because pte_alloc() returns 0 on success,
+ * while {pmd|pud|p4d}_alloc() returns the valid pointer on success.
+ */
+#define change_prepare(vma, high, low, addr, cp_flags) \
+ ({ \
+ long err = 0; \
+ if (unlikely(pgtable_populate_needed(vma, cp_flags))) { \
+ low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
+ if (p == NULL) \
+ err = -ENOMEM; \
+ } \
+ err; \
+ })
+
+static inline long change_pmd_range(struct mmu_gather *tlb,
+ 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;
+ long pages = 0;
+ unsigned long nr_huge_updates = 0;
+ struct mmu_notifier_range range;
+
+ range.start = 0;
+
+ pmd = pmd_offset(pud, addr);
+ do {
+ long ret;
+ pmd_t _pmd;
+again:
+ next = pmd_addr_end(addr, end);
+
+ ret = change_pmd_prepare(vma, pmd, cp_flags);
+ if (ret) {
+ pages = ret;
+ break;
+ }
+
+ if (pmd_none(*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->vm_mm, addr, end);
+ mmu_notifier_invalidate_range_start(&range);
+ }
+
+ _pmd = pmdp_get_lockless(pmd);
+ if (is_swap_pmd(_pmd) || pmd_trans_huge(_pmd) || pmd_devmap(_pmd)) {
+ if ((next - addr != HPAGE_PMD_SIZE) ||
+ pgtable_split_needed(vma, cp_flags)) {
+ __split_huge_pmd(vma, pmd, addr, false, NULL);
+ /*
+ * For file-backed, the pmd could have been
+ * cleared; make sure pmd populated if
+ * necessary, then fall-through to pte level.
+ */
+ ret = change_pmd_prepare(vma, pmd, cp_flags);
+ if (ret) {
+ pages = ret;
+ break;
+ }
+ } else {
+ ret = change_huge_pmd(tlb, vma, pmd,
+ addr, newprot, cp_flags);
+ if (ret) {
+ if (ret == HPAGE_PMD_NR) {
+ pages += HPAGE_PMD_NR;
+ nr_huge_updates++;
+ }
+
+ /* huge pmd was handled */
+ goto next;
+ }
+ }
+ /* fall through, the trans huge pmd just split */
+ }
+
+ ret = change_pte_range(tlb, vma, pmd, addr, next, newprot,
+ cp_flags);
+ if (ret < 0)
+ goto again;
+ pages += ret;
+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 long change_pud_range(struct mmu_gather *tlb,
+ 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;
+ long pages = 0, ret;
+
+ pud = pud_offset(p4d, addr);
+ do {
+ next = pud_addr_end(addr, end);
+ ret = change_prepare(vma, pud, pmd, addr, cp_flags);
+ if (ret)
+ return ret;
+ if (pud_none_or_clear_bad(pud))
+ continue;
+ pages += change_pmd_range(tlb, vma, pud, addr, next, newprot,
+ cp_flags);
+ } while (pud++, addr = next, addr != end);
+
+ return pages;
+}
+
+static inline long change_p4d_range(struct mmu_gather *tlb,
+ 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;
+ long pages = 0, ret;
+
+ p4d = p4d_offset(pgd, addr);
+ do {
+ next = p4d_addr_end(addr, end);
+ ret = change_prepare(vma, p4d, pud, addr, cp_flags);
+ if (ret)
+ return ret;
+ if (p4d_none_or_clear_bad(p4d))
+ continue;
+ pages += change_pud_range(tlb, vma, p4d, addr, next, newprot,
+ cp_flags);
+ } while (p4d++, addr = next, addr != end);
+
+ return pages;
+}
+
+static long change_protection_range(struct mmu_gather *tlb,
+ 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;
+ long pages = 0, ret;
+
+ BUG_ON(addr >= end);
+ pgd = pgd_offset(mm, addr);
+ tlb_start_vma(tlb, vma);
+ do {
+ next = pgd_addr_end(addr, end);
+ ret = change_prepare(vma, pgd, p4d, addr, cp_flags);
+ if (ret) {
+ pages = ret;
+ break;
+ }
+ if (pgd_none_or_clear_bad(pgd))
+ continue;
+ pages += change_p4d_range(tlb, vma, pgd, addr, next, newprot,
+ cp_flags);
+ } while (pgd++, addr = next, addr != end);
+
+ tlb_end_vma(tlb, vma);
+
+ return pages;
+}
+
+long change_protection(struct mmu_gather *tlb,
+ struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, unsigned long cp_flags)
+{
+ pgprot_t newprot = vma->vm_page_prot;
+ long pages;
+
+ BUG_ON((cp_flags & MM_CP_UFFD_WP_ALL) == MM_CP_UFFD_WP_ALL);
+
+#ifdef CONFIG_NUMA_BALANCING
+ /*
+ * Ordinary protection updates (mprotect, uffd-wp, softdirty tracking)
+ * are expected to reflect their requirements via VMA flags such that
+ * vma_set_page_prot() will adjust vma->vm_page_prot accordingly.
+ */
+ if (cp_flags & MM_CP_PROT_NUMA)
+ newprot = PAGE_NONE;
+#else
+ WARN_ON_ONCE(cp_flags & MM_CP_PROT_NUMA);
+#endif
+
+ if (is_vm_hugetlb_page(vma))
+ pages = hugetlb_change_protection(vma, start, end, newprot,
+ cp_flags);
+ else
+ pages = change_protection_range(tlb, 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(ptep_get(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(ptep_get(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,
+ .walk_lock = PGWALK_WRLOCK,
+};
+
+int
+mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
+ 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 int mm_cp_flags = 0;
+ unsigned long charged = 0;
+ pgoff_t pgoff;
+ int error;
+
+ 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(vmi, mm, *pprev, start, end, newflags,
+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+ vma->vm_userfaultfd_ctx, anon_vma_name(vma));
+ 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(vmi, vma, start, 1);
+ if (error)
+ goto fail;
+ }
+
+ if (end != vma->vm_end) {
+ error = split_vma(vmi, 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_start_write(vma);
+ vm_flags_reset(vma, newflags);
+ if (vma_wants_manual_pte_write_upgrade(vma))
+ mm_cp_flags |= MM_CP_TRY_CHANGE_WRITABLE;
+ vma_set_page_prot(vma);
+
+ change_protection(tlb, vma, start, end, mm_cp_flags);
+
+ /*
+ * 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;
+ const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
+ const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
+ (prot & PROT_READ);
+ struct mmu_gather tlb;
+ struct vma_iterator vmi;
+
+ 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_iter_init(&vmi, current->mm, start);
+ vma = vma_find(&vmi, end);
+ error = -ENOMEM;
+ if (!vma)
+ goto out;
+
+ 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;
+ }
+ }
+
+ prev = vma_prev(&vmi);
+ if (start > vma->vm_start)
+ prev = vma;
+
+ tlb_gather_mmu(&tlb, current->mm);
+ nstart = start;
+ tmp = vma->vm_start;
+ for_each_vma_range(vmi, vma, end) {
+ unsigned long mask_off_old_flags;
+ unsigned long newflags;
+ int new_vma_pkey;
+
+ if (vma->vm_start != tmp) {
+ error = -ENOMEM;
+ break;
+ }
+
+ /* 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_ACCESS_FLAGS | 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;
+ break;
+ }
+
+ if (map_deny_write_exec(vma, newflags)) {
+ error = -EACCES;
+ break;
+ }
+
+ /* Allow architectures to sanity-check the new flags */
+ if (!arch_validate_flags(newflags)) {
+ error = -EINVAL;
+ break;
+ }
+
+ error = security_file_mprotect(vma, reqprot, prot);
+ if (error)
+ break;
+
+ tmp = vma->vm_end;
+ if (tmp > end)
+ tmp = end;
+
+ if (vma->vm_ops && vma->vm_ops->mprotect) {
+ error = vma->vm_ops->mprotect(vma, nstart, tmp, newflags);
+ if (error)
+ break;
+ }
+
+ error = mprotect_fixup(&vmi, &tlb, vma, &prev, nstart, tmp, newflags);
+ if (error)
+ break;
+
+ tmp = vma_iter_end(&vmi);
+ nstart = tmp;
+ prot = reqprot;
+ }
+ tlb_finish_mmu(&tlb);
+
+ if (!error && tmp < end)
+ error = -ENOMEM;
+
+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 provide warnings or errors if any VMA still
+ * has the pkey set here.
+ */
+ return ret;
+}
+
+#endif /* CONFIG_ARCH_HAS_PKEYS */
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-22 16:16:29 +0000