This flag causes GUP to assert that all VMAs within the input range possess
the same vma->vm_file. If not, the operation fails.
This is part of a patch series which eliminates the vmas parameter from the
GUP API, implementing the one remaining assertion within the entire kernel
that requires access to the VMAs associated with a GUP range.
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
---
include/linux/mm_types.h | 2 ++
mm/gup.c | 16 ++++++++++++----
2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3fc9e680f174..84d1aec9dbab 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1185,6 +1185,8 @@ enum {
FOLL_PCI_P2PDMA = 1 << 10,
/* allow interrupts from generic signals */
FOLL_INTERRUPTIBLE = 1 << 11,
+ /* assert that the range spans VMAs with the same vma->vm_file */
+ FOLL_SAME_FILE = 1 << 12,
/* See also internal only FOLL flags in mm/internal.h */
};
diff --git a/mm/gup.c b/mm/gup.c
index 9440aa54c741..3954ce499a4a 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -959,7 +959,8 @@ static int faultin_page(struct vm_area_struct *vma,
return 0;
}
-static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
+static int check_vma_flags(struct vm_area_struct *vma, struct file *file,
+ unsigned long gup_flags)
{
vm_flags_t vm_flags = vma->vm_flags;
int write = (gup_flags & FOLL_WRITE);
@@ -968,7 +969,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
if (vm_flags & (VM_IO | VM_PFNMAP))
return -EFAULT;
- if (gup_flags & FOLL_ANON && !vma_is_anonymous(vma))
+ if ((gup_flags & FOLL_ANON) && !vma_is_anonymous(vma))
return -EFAULT;
if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma))
@@ -977,6 +978,9 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
if (vma_is_secretmem(vma))
return -EFAULT;
+ if ((gup_flags & FOLL_SAME_FILE) && vma->vm_file != file)
+ return -EFAULT;
+
if (write) {
if (!(vm_flags & VM_WRITE)) {
if (!(gup_flags & FOLL_FORCE))
@@ -1081,6 +1085,7 @@ static long __get_user_pages(struct mm_struct *mm,
long ret = 0, i = 0;
struct vm_area_struct *vma = NULL;
struct follow_page_context ctx = { NULL };
+ struct file *file = NULL;
if (!nr_pages)
return 0;
@@ -1111,10 +1116,13 @@ static long __get_user_pages(struct mm_struct *mm,
ret = -EFAULT;
goto out;
}
- ret = check_vma_flags(vma, gup_flags);
+ ret = check_vma_flags(vma, i == 0 ? vma->vm_file : file,
+ gup_flags);
if (ret)
goto out;
+ file = vma->vm_file;
+
if (is_vm_hugetlb_page(vma)) {
i = follow_hugetlb_page(mm, vma, pages, vmas,
&start, &nr_pages, i,
@@ -1595,7 +1603,7 @@ long faultin_vma_page_range(struct vm_area_struct *vma, unsigned long start,
* We want to report -EINVAL instead of -EFAULT for any permission
* problems or incompatible mappings.
*/
- if (check_vma_flags(vma, gup_flags))
+ if (check_vma_flags(vma, vma->vm_file, gup_flags))
return -EINVAL;
ret = __get_user_pages(mm, start, nr_pages, gup_flags,
--
2.40.0
