[PATCH 1/2] memfd: export memfd_{add,get}_seals()

Pratyush Yadav
2026-01-23T09:59:15Z

From: "Pratyush Yadav (Google)" <pratyush@kernel.org>

Support for preserving file seals will be added to memfd preservation
using the Live Update Orchestrator (LUO). Export
memfd_{add,get}_seals)() so memfd_luo can use them to manipulate the
seals.

Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
---
include/linux/memfd.h | 12 ++++++++++++
mm/memfd.c | 4 ++--
2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/linux/memfd.h b/include/linux/memfd.h
index c328a7b356d0..b4fda09dab9f 100644
--- a/include/linux/memfd.h
+++ b/include/linux/memfd.h
@@ -18,6 +18,8 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx);
*/
int memfd_check_seals_mmap(struct file *file, vm_flags_t *vm_flags_ptr);
struct file *memfd_alloc_file(const char *name, unsigned int flags);
+int memfd_get_seals(struct file *file);
+int memfd_add_seals(struct file *file, unsigned int seals);
#else
static inline long memfd_fcntl(struct file *f, unsigned int c, unsigned int a)
{
@@ -37,6 +39,16 @@ static inline struct file *memfd_alloc_file(const char *name, unsigned int flags
{
return ERR_PTR(-EINVAL);
}
+
+static inline int memfd_get_seals(struct file *file)
+{
+ return -EINVAL;
+}
+
+static inline int memfd_add_seals(struct file *file, unsigned int seals)
+{
+ return -EINVAL;
+}
#endif

#endif /* __LINUX_MEMFD_H */
diff --git a/mm/memfd.c b/mm/memfd.c
index f032c6052926..46c5508beea4 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -228,7 +228,7 @@ static unsigned int *memfd_file_seals_ptr(struct file *file)
F_SEAL_WRITE | \
F_SEAL_FUTURE_WRITE)

-static int memfd_add_seals(struct file *file, unsigned int seals)
+int memfd_add_seals(struct file *file, unsigned int seals)
{
struct inode *inode = file_inode(file);
unsigned int *file_seals;
@@ -310,7 +310,7 @@ static int memfd_add_seals(struct file *file, unsigned int seals)
return error;
}

-static int memfd_get_seals(struct file *file)
+int memfd_get_seals(struct file *file)
{
unsigned int *seals = memfd_file_seals_ptr(file);

--
2.52.0.457.g6b5491de43-goog