[PATCH v6 04/17] filelock: push the S_ISREG check down to ->setlease handlers

Jeff Layton
2025-11-11T14:13:16Z

When nfsd starts requesting directory delegations, setlease handlers may
see requests for leases on directories. Push the !S_ISREG check down
into the non-trivial setlease handlers, so we can selectively enable
them where they're supported.

FUSE is special: It's the only filesystem that supports atomic_open and
allows kernel-internal leases. atomic_open is issued when the VFS
doesn't know the state of the dentry being opened. If the file doesn't
exist, it may be created, in which case the dir lease should be broken.

The existing kernel-internal lease implementation has no provision for
this. Ensure that we don't allow directory leases by default going
forward by explicitly disabling them there.

Reviewed-by: NeilBrown <neil@brown.name>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/fuse/dir.c | 1 +
fs/locks.c | 5 +++--
fs/nfs/nfs4file.c | 2 ++
fs/smb/client/cifsfs.c | 3 +++
4 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index ecaec0fea3a132e7cbb88121e7db7fb504d57d3c..667774cc72a1d49796f531fcb342d2e4878beb85 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -2230,6 +2230,7 @@ static const struct file_operations fuse_dir_operations = {
.fsync = fuse_dir_fsync,
.unlocked_ioctl = fuse_dir_ioctl,
.compat_ioctl = fuse_dir_compat_ioctl,
+ .setlease = simple_nosetlease,
};

static const struct inode_operations fuse_common_inode_operations = {
diff --git a/fs/locks.c b/fs/locks.c
index 3cdd84a0fbedc9bd1b47725a9cf963342aafbce9..f5b210a2dc34c70ac36e972436c62482bbe32ca6 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1935,6 +1935,9 @@ static int generic_delete_lease(struct file *filp, void *owner)
int generic_setlease(struct file *filp, int arg, struct file_lease **flp,
void **priv)
{
+ if (!S_ISREG(file_inode(filp)->i_mode))
+ return -EINVAL;
+
switch (arg) {
case F_UNLCK:
return generic_delete_lease(filp, *priv);
@@ -2024,8 +2027,6 @@ vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)

if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE))
return -EACCES;
- if (!S_ISREG(inode->i_mode))
- return -EINVAL;
error = security_file_lock(filp, arg);
if (error)
return error;
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index 7f43e890d3564a000dab9365048a3e17dc96395c..7317f26892c5782a39660cae87ec1afea24e36c0 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -431,6 +431,8 @@ void nfs42_ssc_unregister_ops(void)
static int nfs4_setlease(struct file *file, int arg, struct file_lease **lease,
void **priv)
{
+ if (!S_ISREG(file_inode(file)->i_mode))
+ return -EINVAL;
return nfs4_proc_setlease(file, arg, lease, priv);
}

diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index 05b1fa76e8ccf1e86f0c174593cd6e1acb84608d..03c44c1d9bb631b87a8b67aa16e481d6bb3c7d14 100644
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -1149,6 +1149,9 @@ cifs_setlease(struct file *file, int arg, struct file_lease **lease, void **priv
struct inode *inode = file_inode(file);
struct cifsFileInfo *cfile = file->private_data;

+ if (!S_ISREG(inode->i_mode))
+ return -EINVAL;
+
/* Check if file is oplocked if this is request for new lease */
if (arg == F_UNLCK ||
((arg == F_RDLCK) && CIFS_CACHE_READ(CIFS_I(inode))) ||

--
2.51.1