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mm/vma: convert __mmap_region() to use vma_flags_t

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Update the mmap() implementation logic implemented in __mmap_region() and
functions invoked by it.  The mmap_region() function converts its input
vm_flags_t parameter to a vma_flags_t value which it then passes to
__mmap_region() which uses the vma_flags_t value consistently from then
on.

As part of the change, we convert map_deny_write_exec() to using
vma_flags_t (it was incorrectly using unsigned long before), and place it
in vma.h, as it is only used internal to mm.

With this change, we eliminate the legacy is_shared_maywrite_vm_flags()
helper function which is now no longer required.

We are also able to update the MMAP_STATE() and VMG_MMAP_STATE() macros to
use the vma_flags_t value.

Finally, we update the VMA tests to reflect the change.

Link: https://lkml.kernel.org/r/1fc33a404c962f02da778da100387cc19bd62153.1774034900.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ondrej Mosnacek <omosnace@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes (Oracle)
2026-03-20 19:38:41 +00:00
committed by Andrew Morton
parent a06eb2f827
commit 90cb921c4d
7 changed files with 92 additions and 107 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
include/linux/mm.h
View File

@@ -1522,12 +1522,6 @@ static inline bool vma_is_accessible(const struct vm_area_struct *vma)
return vma->vm_flags & VM_ACCESS_FLAGS;
}
static inline bool is_shared_maywrite_vm_flags(vm_flags_t vm_flags)
{
return (vm_flags & (VM_SHARED | VM_MAYWRITE)) ==
(VM_SHARED | VM_MAYWRITE);
}
static inline bool is_shared_maywrite(const vma_flags_t *flags)
{
return vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT);
@@ -4335,12 +4329,24 @@ static inline bool range_in_vma(const struct vm_area_struct *vma,
#ifdef CONFIG_MMU
pgprot_t vm_get_page_prot(vm_flags_t vm_flags);
static inline pgprot_t vma_get_page_prot(vma_flags_t vma_flags)
{
const vm_flags_t vm_flags = vma_flags_to_legacy(vma_flags);
return vm_get_page_prot(vm_flags);
}
void vma_set_page_prot(struct vm_area_struct *vma);
#else
static inline pgprot_t vm_get_page_prot(vm_flags_t vm_flags)
{
return __pgprot(0);
}
static inline pgprot_t vma_get_page_prot(vma_flags_t vma_flags)
{
return __pgprot(0);
}
static inline void vma_set_page_prot(struct vm_area_struct *vma)
{
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);

49
include/linux/mman.h
View File

@@ -170,53 +170,4 @@ static inline bool arch_memory_deny_write_exec_supported(void)
}
#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
#endif
/*
* Denies creating a writable executable mapping or gaining executable permissions.
*
* This denies the following:
*
* a) mmap(PROT_WRITE | PROT_EXEC)
*
* b) mmap(PROT_WRITE)
* mprotect(PROT_EXEC)
*
* c) mmap(PROT_WRITE)
* mprotect(PROT_READ)
* mprotect(PROT_EXEC)
*
* But allows the following:
*
* d) mmap(PROT_READ | PROT_EXEC)
* mmap(PROT_READ | PROT_EXEC | PROT_BTI)
*
* This is only applicable if the user has set the Memory-Deny-Write-Execute
* (MDWE) protection mask for the current process.
*
* @old specifies the VMA flags the VMA originally possessed, and @new the ones
* we propose to set.
*
* Return: false if proposed change is OK, true if not ok and should be denied.
*/
static inline bool map_deny_write_exec(unsigned long old, unsigned long new)
{
/* If MDWE is disabled, we have nothing to deny. */
if (!mm_flags_test(MMF_HAS_MDWE, current->mm))
return false;
/* If the new VMA is not executable, we have nothing to deny. */
if (!(new & VM_EXEC))
return false;
/* Under MDWE we do not accept newly writably executable VMAs... */
if (new & VM_WRITE)
return true;
/* ...nor previously non-executable VMAs becoming executable. */
if (!(old & VM_EXEC))
return true;
return false;
}
#endif /* _LINUX_MMAN_H */

4
mm/mprotect.c
View File

@@ -882,6 +882,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
tmp = vma->vm_start;
for_each_vma_range(vmi, vma, end) {
vm_flags_t mask_off_old_flags;
vma_flags_t new_vma_flags;
vm_flags_t newflags;
int new_vma_pkey;
@@ -904,6 +905,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
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);
new_vma_flags = legacy_to_vma_flags(newflags);
/* newflags >> 4 shift VM_MAY% in place of VM_% */
if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) {
@@ -911,7 +913,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
break;
}
if (map_deny_write_exec(vma->vm_flags, newflags)) {
if (map_deny_write_exec(&vma->flags, &new_vma_flags)) {
error = -EACCES;
break;
}

25
mm/vma.c
View File

@@ -44,7 +44,7 @@ struct mmap_state {
bool file_doesnt_need_get :1;
};
#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, vm_flags_, file_) \
#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, vma_flags_, file_) \
struct mmap_state name = { \
.mm = mm_, \
.vmi = vmi_, \
@@ -52,9 +52,9 @@ struct mmap_state {
.end = (addr_) + (len_), \
.pgoff = pgoff_, \
.pglen = PHYS_PFN(len_), \
.vm_flags = vm_flags_, \
.vma_flags = vma_flags_, \
.file = file_, \
.page_prot = vm_get_page_prot(vm_flags_), \
.page_prot = vma_get_page_prot(vma_flags_), \
}
#define VMG_MMAP_STATE(name, map_, vma_) \
@@ -63,7 +63,7 @@ struct mmap_state {
.vmi = (map_)->vmi, \
.start = (map_)->addr, \
.end = (map_)->end, \
.vm_flags = (map_)->vm_flags, \
.vma_flags = (map_)->vma_flags, \
.pgoff = (map_)->pgoff, \
.file = (map_)->file, \
.prev = (map_)->prev, \
@@ -2746,14 +2746,14 @@ static int call_action_complete(struct mmap_state *map,
}
static unsigned long __mmap_region(struct file *file, unsigned long addr,
unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
struct list_head *uf)
unsigned long len, vma_flags_t vma_flags,
unsigned long pgoff, struct list_head *uf)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma = NULL;
bool have_mmap_prepare = file && file->f_op->mmap_prepare;
VMA_ITERATOR(vmi, mm, addr);
MMAP_STATE(map, mm, &vmi, addr, len, pgoff, vm_flags, file);
MMAP_STATE(map, mm, &vmi, addr, len, pgoff, vma_flags, file);
struct vm_area_desc desc = {
.mm = mm,
.file = file,
@@ -2837,16 +2837,17 @@ abort_munmap:
* been performed.
*/
unsigned long mmap_region(struct file *file, unsigned long addr,
unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
struct list_head *uf)
unsigned long len, vm_flags_t vm_flags,
unsigned long pgoff, struct list_head *uf)
{
unsigned long ret;
bool writable_file_mapping = false;
const vma_flags_t vma_flags = legacy_to_vma_flags(vm_flags);
mmap_assert_write_locked(current->mm);
/* Check to see if MDWE is applicable. */
if (map_deny_write_exec(vm_flags, vm_flags))
if (map_deny_write_exec(&vma_flags, &vma_flags))
return -EACCES;
/* Allow architectures to sanity-check the vm_flags. */
@@ -2854,7 +2855,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
return -EINVAL;
/* Map writable and ensure this isn't a sealed memfd. */
if (file && is_shared_maywrite_vm_flags(vm_flags)) {
if (file && is_shared_maywrite(&vma_flags)) {
int error = mapping_map_writable(file->f_mapping);
if (error)
@@ -2862,7 +2863,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
writable_file_mapping = true;
}
ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf);
ret = __mmap_region(file, addr, len, vma_flags, pgoff, uf);
/* Clear our write mapping regardless of error. */
if (writable_file_mapping)

51
mm/vma.h
View File

@@ -704,4 +704,55 @@ int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap,
int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift);
#endif
#ifdef CONFIG_MMU
/*
* Denies creating a writable executable mapping or gaining executable permissions.
*
* This denies the following:
*
* a) mmap(PROT_WRITE | PROT_EXEC)
*
* b) mmap(PROT_WRITE)
* mprotect(PROT_EXEC)
*
* c) mmap(PROT_WRITE)
* mprotect(PROT_READ)
* mprotect(PROT_EXEC)
*
* But allows the following:
*
* d) mmap(PROT_READ | PROT_EXEC)
* mmap(PROT_READ | PROT_EXEC | PROT_BTI)
*
* This is only applicable if the user has set the Memory-Deny-Write-Execute
* (MDWE) protection mask for the current process.
*
* @old specifies the VMA flags the VMA originally possessed, and @new the ones
* we propose to set.
*
* Return: false if proposed change is OK, true if not ok and should be denied.
*/
static inline bool map_deny_write_exec(const vma_flags_t *old,
const vma_flags_t *new)
{
/* If MDWE is disabled, we have nothing to deny. */
if (!mm_flags_test(MMF_HAS_MDWE, current->mm))
return false;
/* If the new VMA is not executable, we have nothing to deny. */
if (!vma_flags_test(new, VMA_EXEC_BIT))
return false;
/* Under MDWE we do not accept newly writably executable VMAs... */
if (vma_flags_test(new, VMA_WRITE_BIT))
return true;
/* ...nor previously non-executable VMAs becoming executable. */
if (!vma_flags_test(old, VMA_EXEC_BIT))
return true;
return false;
}
#endif
#endif /* __MM_VMA_H */

34
tools/testing/vma/include/dup.h
View File

@@ -1124,12 +1124,6 @@ static __always_inline void vma_desc_clear_flags_mask(struct vm_area_desc *desc,
#define vma_desc_clear_flags(desc, ...) \
vma_desc_clear_flags_mask(desc, mk_vma_flags(__VA_ARGS__))
static inline bool is_shared_maywrite_vm_flags(vm_flags_t vm_flags)
{
return (vm_flags & (VM_SHARED | VM_MAYWRITE)) ==
(VM_SHARED | VM_MAYWRITE);
}
static inline bool is_shared_maywrite(const vma_flags_t *flags)
{
return vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT);
@@ -1446,27 +1440,6 @@ static inline bool mlock_future_ok(const struct mm_struct *mm,
return locked_pages <= limit_pages;
}
static inline bool map_deny_write_exec(unsigned long old, unsigned long new)
{
/* If MDWE is disabled, we have nothing to deny. */
if (mm_flags_test(MMF_HAS_MDWE, current->mm))
return false;
/* If the new VMA is not executable, we have nothing to deny. */
if (!(new & VM_EXEC))
return false;
/* Under MDWE we do not accept newly writably executable VMAs... */
if (new & VM_WRITE)
return true;
/* ...nor previously non-executable VMAs becoming executable. */
if (!(old & VM_EXEC))
return true;
return false;
}
static inline int mapping_map_writable(struct address_space *mapping)
{
return atomic_inc_unless_negative(&mapping->i_mmap_writable) ?
@@ -1518,3 +1491,10 @@ static inline int get_sysctl_max_map_count(void)
#ifndef pgtable_supports_soft_dirty
#define pgtable_supports_soft_dirty() IS_ENABLED(CONFIG_MEM_SOFT_DIRTY)
#endif
static inline pgprot_t vma_get_page_prot(vma_flags_t vma_flags)
{
const vm_flags_t vm_flags = vma_flags_to_legacy(vma_flags);
return vm_get_page_prot(vm_flags);
}

18
tools/testing/vma/tests/mmap.c
View File

@@ -2,6 +2,8 @@
static bool test_mmap_region_basic(void)
{
const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT,
VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT);
struct mm_struct mm = {};
unsigned long addr;
struct vm_area_struct *vma;
@@ -10,27 +12,19 @@ static bool test_mmap_region_basic(void)
current->mm = &mm;
/* Map at 0x300000, length 0x3000. */
addr = __mmap_region(NULL, 0x300000, 0x3000,
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
0x300, NULL);
addr = __mmap_region(NULL, 0x300000, 0x3000, vma_flags, 0x300, NULL);
ASSERT_EQ(addr, 0x300000);
/* Map at 0x250000, length 0x3000. */
addr = __mmap_region(NULL, 0x250000, 0x3000,
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
0x250, NULL);
addr = __mmap_region(NULL, 0x250000, 0x3000, vma_flags, 0x250, NULL);
ASSERT_EQ(addr, 0x250000);
/* Map at 0x303000, merging to 0x300000 of length 0x6000. */
addr = __mmap_region(NULL, 0x303000, 0x3000,
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
0x303, NULL);
addr = __mmap_region(NULL, 0x303000, 0x3000, vma_flags, 0x303, NULL);
ASSERT_EQ(addr, 0x303000);
/* Map at 0x24d000, merging to 0x250000 of length 0x6000. */
addr = __mmap_region(NULL, 0x24d000, 0x3000,
VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE,
0x24d, NULL);
addr = __mmap_region(NULL, 0x24d000, 0x3000, vma_flags, 0x24d, NULL);
ASSERT_EQ(addr, 0x24d000);
ASSERT_EQ(mm.map_count, 2);