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authorLorenzo Stoakes <lstoakes@gmail.com>2023-10-12 18:04:29 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-10-18 14:34:19 -0700
commit28464bbb2ddc199433383994bcb9600c8034afa1 (patch)
tree842756d4566e617a828b773eb385fd746e6ae997
parente8e17ee90eaf650c855adb0a3e5e965fd6692ff1 (diff)
mm: update memfd seal write check to include F_SEAL_WRITE
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@gmail.com Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andy Lutomirski <luto@kernel.org> Cc: Christian Brauner <brauner@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--fs/hugetlbfs/inode.c2
-rw-r--r--include/linux/mm.h15
-rw-r--r--mm/shmem.c2
3 files changed, 10 insertions, 9 deletions
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 926d01c493fb..85cd418d2340 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -135,7 +135,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
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;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c3b5749ede9d..86e040e886e4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4076,25 +4076,26 @@ static inline void mem_dump_obj(void *object) {}
#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
diff --git a/mm/shmem.c b/mm/shmem.c
index 61b170324e5c..bcbe9dbb9f5f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2378,7 +2378,7 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
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;