635 lines
16 KiB
C
635 lines
16 KiB
C
// 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 <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)
|
|
{
|
|
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;
|
|
|
|
/* 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_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;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/* 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_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(vma->vm_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(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;
|
|
}
|
|
|
|
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;
|
|
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);
|
|
if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
|
|
&& pmd_none_or_clear_bad(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, 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 (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, 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 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_READ|VM_WRITE|VM_EXEC)) == 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_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);
|
|
|
|
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 (down_write_killable(¤t->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(¤t->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(¤t->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(¤t->mm->mmap_sem);
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(pkey_free, int, pkey)
|
|
{
|
|
int ret;
|
|
|
|
down_write(¤t->mm->mmap_sem);
|
|
ret = mm_pkey_free(current->mm, pkey);
|
|
up_write(¤t->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 */
|