The quilt patch titled
Subject: mm: update memfd seal write check to include F_SEAL_WRITE
has been removed from the -mm tree. Its filename was
mm-update-memfd-seal-write-check-to-include-f_seal_write.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Subject: mm: update memfd seal write check to include F_SEAL_WRITE
Date: Thu, 12 Oct 2023 18:04:29 +0100
The seal_check_future_write() function is called by shmem_mmap() or
hugetlbfs_file_mmap() to disallow any future writable mappings of an memfd
sealed this way.
The F_SEAL_WRITE flag is not checked here, as that is handled via the
mapping->i_mmap_writable mechanism and so any attempt at a mapping would
fail before this could be run.
However we intend to change this, meaning this check can be performed for
F_SEAL_WRITE mappings also.
The logic here is equally applicable to both flags, so update this
function to accommodate both and rename it accordingly.
Link: https://lkml.kernel.org/r/913628168ce6cce77df7d13a63970bae06a526e0.1697116581.git.lstoakes@xxxxxxxxx
Signed-off-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/hugetlbfs/inode.c | 2 +-
include/linux/mm.h | 15 ++++++++-------
mm/shmem.c | 2 +-
3 files changed, 10 insertions(+), 9 deletions(-)
--- a/fs/hugetlbfs/inode.c~mm-update-memfd-seal-write-check-to-include-f_seal_write
+++ a/fs/hugetlbfs/inode.c
@@ -135,7 +135,7 @@ static int hugetlbfs_file_mmap(struct fi
vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND);
vma->vm_ops = &hugetlb_vm_ops;
- ret = seal_check_future_write(info->seals, vma);
+ ret = seal_check_write(info->seals, vma);
if (ret)
return ret;
--- a/include/linux/mm.h~mm-update-memfd-seal-write-check-to-include-f_seal_write
+++ a/include/linux/mm.h
@@ -4076,25 +4076,26 @@ static inline void mem_dump_obj(void *ob
#endif
/**
- * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle it
+ * seal_check_write - Check for F_SEAL_WRITE or F_SEAL_FUTURE_WRITE flags and
+ * handle them.
* @seals: the seals to check
* @vma: the vma to operate on
*
- * Check whether F_SEAL_FUTURE_WRITE is set; if so, do proper check/handling on
- * the vma flags. Return 0 if check pass, or <0 for errors.
+ * Check whether F_SEAL_WRITE or F_SEAL_FUTURE_WRITE are set; if so, do proper
+ * check/handling on the vma flags. Return 0 if check pass, or <0 for errors.
*/
-static inline int seal_check_future_write(int seals, struct vm_area_struct *vma)
+static inline int seal_check_write(int seals, struct vm_area_struct *vma)
{
- if (seals & F_SEAL_FUTURE_WRITE) {
+ if (seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
/*
* New PROT_WRITE and MAP_SHARED mmaps are not allowed when
- * "future write" seal active.
+ * write seals are active.
*/
if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
return -EPERM;
/*
- * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as
+ * Since an F_SEAL_[FUTURE_]WRITE sealed memfd can be mapped as
* MAP_SHARED and read-only, take care to not allow mprotect to
* revert protections on such mappings. Do this only for shared
* mappings. For private mappings, don't need to mask
--- a/mm/shmem.c~mm-update-memfd-seal-write-check-to-include-f_seal_write
+++ a/mm/shmem.c
@@ -2378,7 +2378,7 @@ static int shmem_mmap(struct file *file,
struct shmem_inode_info *info = SHMEM_I(inode);
int ret;
- ret = seal_check_future_write(info->seals, vma);
+ ret = seal_check_write(info->seals, vma);
if (ret)
return ret;
_
Patches currently in -mm which might be from lstoakes@xxxxxxxxx are
