linux/mm/mprotect.c
David Hildenbrand 1ef488edd6 mm/mprotect: drop pgprot_t parameter from change_protection()
Being able to provide a custom protection opens the door for
inconsistencies and BUGs: for example, accidentally allowing for more
permissions than desired by other mechanisms (e.g., softdirty tracking). 
vma->vm_page_prot should be the single source of truth.

Only PROT_NUMA is special: there is no way we can erroneously allow
for more permissions when removing all permissions. Special-case using
the MM_CP_PROT_NUMA flag.

[david@redhat.com: PAGE_NONE might not be defined without CONFIG_NUMA_BALANCING]  
  Link: https://lkml.kernel.org/r/5084ff1c-ebb3-f918-6a60-bacabf550a88@redhat.com
Link: https://lkml.kernel.org/r/20221223155616.297723-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-18 17:12:50 -08:00

885 lines
23 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 <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 unsigned 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;
unsigned 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);
/*
* 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;
/*
* 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);
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);
if (pte_swp_uffd_wp(oldpte))
newpte = pte_swp_mkuffd_wp(newpte);
} else if (is_writable_device_private_entry(entry)) {
/*
* We do not preserve soft-dirtiness. See
* copy_one_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 swapin errors unconditionally,
* because any access should sigbus anyway.
*/
if (is_swapin_error_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));
if (unlikely(uffd_wp && !vma_is_anonymous(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;
}
/*
* 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 = pmdp_get_lockless(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;
}
/* Return true if we're uffd wr-protecting file-backed memory, or false */
static inline bool
uffd_wp_protect_file(struct vm_area_struct *vma, unsigned long cp_flags)
{
return (cp_flags & MM_CP_UFFD_WP) && !vma_is_anonymous(vma);
}
/*
* If wr-protecting the range for file-backed, populate pgtable for the case
* when pgtable is empty but page cache exists. When {pte|pmd|...}_alloc()
* failed it means no memory, we don't have a better option but stop.
*/
#define change_pmd_prepare(vma, pmd, cp_flags) \
do { \
if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
if (WARN_ON_ONCE(pte_alloc(vma->vm_mm, pmd))) \
break; \
} \
} while (0)
/*
* 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) \
do { \
if (unlikely(uffd_wp_protect_file(vma, cp_flags))) { \
low##_t *p = low##_alloc(vma->vm_mm, high, addr); \
if (WARN_ON_ONCE(p == NULL)) \
break; \
} \
} while (0)
static inline unsigned 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;
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);
change_pmd_prepare(vma, pmd, cp_flags);
/*
* 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) ||
uffd_wp_protect_file(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.
*/
change_pmd_prepare(vma, pmd, cp_flags);
} else {
/*
* change_huge_pmd() does not defer TLB flushes,
* so no need to propagate the tlb argument.
*/
int nr_ptes = change_huge_pmd(tlb, 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(tlb, 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 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;
unsigned long pages = 0;
pud = pud_offset(p4d, addr);
do {
next = pud_addr_end(addr, end);
change_prepare(vma, pud, pmd, addr, cp_flags);
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 unsigned 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;
unsigned long pages = 0;
p4d = p4d_offset(pgd, addr);
do {
next = p4d_addr_end(addr, end);
change_prepare(vma, p4d, pud, addr, cp_flags);
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 unsigned 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;
unsigned long pages = 0;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
tlb_start_vma(tlb, vma);
do {
next = pgd_addr_end(addr, end);
change_prepare(vma, pgd, p4d, addr, cp_flags);
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;
}
unsigned 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;
unsigned 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(*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 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(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(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;
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;
MA_STATE(mas, &current->mm->mm_mt, 0, 0);
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;
mas_set(&mas, start);
vma = mas_find(&mas, ULONG_MAX);
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;
}
}
if (start > vma->vm_start)
prev = vma;
else
prev = mas_prev(&mas, 0);
tlb_gather_mmu(&tlb, current->mm);
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_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;
}
/* 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(&tlb, vma, &prev, nstart, tmp, newflags);
if (error)
break;
nstart = tmp;
if (nstart < prev->vm_end)
nstart = prev->vm_end;
if (nstart >= end)
break;
vma = find_vma(current->mm, prev->vm_end);
if (!vma || vma->vm_start != nstart) {
error = -ENOMEM;
break;
}
prot = reqprot;
}
tlb_finish_mmu(&tlb);
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 */