Use a new flag instead of overloading AS_INACCESSIBLE (which is already
set by guest_memfd) because not all guest_memfd mappings will end up
being direct map removed (e.g. in pKVM setups, parts of guest_memfd that
can be mapped to userspace should also be GUP-able, and generally not
have restrictions on who can access it).
Acked-by: Mike Rapoport (Microsoft) <[email protected]>
Acked-by: David Hildenbrand (Red Hat)" <[email protected]>
Signed-off-by: Patrick Roy <[email protected]>
Signed-off-by: Nikita Kalyazin <[email protected]>
---
include/linux/pagemap.h | 16 ++++++++++++++++
include/linux/secretmem.h | 18 ------------------
lib/buildid.c | 4 ++--
mm/gup.c | 19 +++++--------------
mm/mlock.c | 2 +-
mm/secretmem.c | 8 ++------
6 files changed, 26 insertions(+), 41 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a17fabbc0269..d51e0c0404e2 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -213,6 +213,7 @@ enum mapping_flags {
AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM = 9,
AS_KERNEL_FILE = 10, /* mapping for a fake kernel file that shouldn't
account usage to user cgroups */
+ AS_NO_DIRECT_MAP = 11, /* Folios in the mapping are not in the direct
map */
/* Bits 16-25 are used for FOLIO_ORDER */
AS_FOLIO_ORDER_BITS = 5,
AS_FOLIO_ORDER_MIN = 16,
@@ -348,6 +349,21 @@ static inline bool
mapping_writeback_may_deadlock_on_reclaim(const struct addres
return test_bit(AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM, &mapping->flags);
}
+static inline void mapping_set_no_direct_map(struct address_space *mapping)
+{
+ set_bit(AS_NO_DIRECT_MAP, &mapping->flags);
+}
+
+static inline bool mapping_no_direct_map(const struct address_space *mapping)
+{
+ return test_bit(AS_NO_DIRECT_MAP, &mapping->flags);
+}
+
+static inline bool vma_has_no_direct_map(const struct vm_area_struct *vma)
+{
+ return vma->vm_file && mapping_no_direct_map(vma->vm_file->f_mapping);
+}
+
static inline gfp_t mapping_gfp_mask(const struct address_space *mapping)
{
return mapping->gfp_mask;
diff --git a/include/linux/secretmem.h b/include/linux/secretmem.h
index e918f96881f5..0ae1fb057b3d 100644
--- a/include/linux/secretmem.h
+++ b/include/linux/secretmem.h
@@ -4,28 +4,10 @@
#ifdef CONFIG_SECRETMEM
-extern const struct address_space_operations secretmem_aops;
-
-static inline bool secretmem_mapping(struct address_space *mapping)
-{
- return mapping->a_ops == &secretmem_aops;
-}
-
-bool vma_is_secretmem(struct vm_area_struct *vma);
bool secretmem_active(void);
#else
-static inline bool vma_is_secretmem(struct vm_area_struct *vma)
-{
- return false;
-}
-
-static inline bool secretmem_mapping(struct address_space *mapping)
-{
- return false;
-}
-
static inline bool secretmem_active(void)
{
return false;
diff --git a/lib/buildid.c b/lib/buildid.c
index c4b0f376fb34..89e567954284 100644
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -65,8 +65,8 @@ static int freader_get_folio(struct freader *r, loff_t
file_off)
freader_put_folio(r);
- /* reject secretmem folios created with memfd_secret() */
- if (secretmem_mapping(r->file->f_mapping))
+ /* reject folios without direct map entries (e.g. from memfd_secret()
or guest_memfd()) */
+ if (mapping_no_direct_map(r->file->f_mapping))
return -EFAULT;
r->folio = filemap_get_folio(r->file->f_mapping, file_off >> PAGE_SHIFT);
diff --git a/mm/gup.c b/mm/gup.c
index a8ba5112e4d0..719e4dbecc09 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -11,7 +11,6 @@
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/swapops.h>
-#include <linux/secretmem.h>
#include <linux/sched/signal.h>
#include <linux/rwsem.h>
@@ -1216,7 +1215,7 @@ static int check_vma_flags(struct vm_area_struct *vma,
unsigned long gup_flags)
if ((gup_flags & FOLL_SPLIT_PMD) && is_vm_hugetlb_page(vma))
return -EOPNOTSUPP;
- if (vma_is_secretmem(vma))
+ if (vma_has_no_direct_map(vma))
return -EFAULT;
if (write) {
@@ -2724,7 +2723,7 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
* This call assumes the caller has pinned the folio, that the lowest page
table
* level still points to this folio, and that interrupts have been disabled.
*
- * GUP-fast must reject all secretmem folios.
+ * GUP-fast must reject all folios without direct map entries (such as
secretmem).
*
* Writing to pinned file-backed dirty tracked folios is inherently
problematic
* (see comment describing the writable_file_mapping_allowed() function). We
@@ -2739,7 +2738,6 @@ static bool gup_fast_folio_allowed(struct folio *folio,
unsigned int flags)
{
bool reject_file_backed = false;
struct address_space *mapping;
- bool check_secretmem = false;
unsigned long mapping_flags;
/*
@@ -2751,18 +2749,10 @@ static bool gup_fast_folio_allowed(struct folio *folio,
unsigned int flags)
reject_file_backed = true;
/* We hold a folio reference, so we can safely access folio fields. */
-
- /* secretmem folios are always order-0 folios. */
- if (IS_ENABLED(CONFIG_SECRETMEM) && !folio_test_large(folio))
- check_secretmem = true;
-
- if (!reject_file_backed && !check_secretmem)
- return true;
-
if (WARN_ON_ONCE(folio_test_slab(folio)))
return false;
- /* hugetlb neither requires dirty-tracking nor can be secretmem. */
+ /* hugetlb neither requires dirty-tracking nor can be without direct
map. */
if (folio_test_hugetlb(folio))
return true;
@@ -2800,8 +2790,9 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags)
* At this point, we know the mapping is non-null and points to an
* address_space object.
*/
- if (check_secretmem && secretmem_mapping(mapping))
+ if (mapping_no_direct_map(mapping))
return false;
+
/* The only remaining allowed file system is shmem. */
return !reject_file_backed || shmem_mapping(mapping);
}
diff --git a/mm/mlock.c b/mm/mlock.c
index bb0776f5ef7c..506452ee8cad 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -474,7 +474,7 @@ static int mlock_fixup(struct vma_iterator *vmi, struct
vm_area_struct *vma,
if (newflags == oldflags || (oldflags & VM_SPECIAL) ||
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) ||
- vma_is_dax(vma) || vma_is_secretmem(vma) || (oldflags &
VM_DROPPABLE))
+ vma_is_dax(vma) || vma_has_no_direct_map(vma) || (oldflags &
VM_DROPPABLE))
/* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */
goto out;
diff --git a/mm/secretmem.c b/mm/secretmem.c
index b59350daffe3..c1eafe29c3e8 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -134,11 +134,6 @@ static int secretmem_mmap_prepare(struct vm_area_desc
*desc)
return 0;
}
-bool vma_is_secretmem(struct vm_area_struct *vma)
-{
- return vma->vm_ops == &secretmem_vm_ops;
-}
-
static const struct file_operations secretmem_fops = {
.release = secretmem_release,
.mmap_prepare = secretmem_mmap_prepare,
@@ -156,7 +151,7 @@ static void secretmem_free_folio(struct folio *folio)
folio_zero_segment(folio, 0, folio_size(folio));
}
-const struct address_space_operations secretmem_aops = {
+static const struct address_space_operations secretmem_aops = {
.dirty_folio = noop_dirty_folio,
.free_folio = secretmem_free_folio,
.migrate_folio = secretmem_migrate_folio,
@@ -205,6 +200,7 @@ static struct file *secretmem_file_create(unsigned long
flags)
mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
mapping_set_unevictable(inode->i_mapping);
+ mapping_set_no_direct_map(inode->i_mapping);
inode->i_op = &secretmem_iops;
inode->i_mapping->a_ops = &secretmem_aops;
