linux-kernel - Re: [PATCH 01/13] filelock: push the S_ISREG check down to ->setlease handlers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-id: <176042024558.1793333.16859845484527356211@noble.neil.brown.name>
Date: Tue, 14 Oct 2025 16:37:25 +1100
From: NeilBrown <neilb@...mail.net>
To: "Jeff Layton" <jlayton@...nel.org>
Cc: "Miklos Szeredi" <miklos@...redi.hu>,
 "Alexander Viro" <viro@...iv.linux.org.uk>,
 "Christian Brauner" <brauner@...nel.org>, "Jan Kara" <jack@...e.cz>,
 "Chuck Lever" <chuck.lever@...cle.com>,
 "Alexander Aring" <alex.aring@...il.com>,
 "Trond Myklebust" <trondmy@...nel.org>,
 "Anna Schumaker" <anna@...nel.org>, "Steve French" <sfrench@...ba.org>,
 "Paulo Alcantara" <pc@...guebit.org>,
 "Ronnie Sahlberg" <ronniesahlberg@...il.com>,
 "Shyam Prasad N" <sprasad@...rosoft.com>, "Tom Talpey" <tom@...pey.com>,
 "Bharath SM" <bharathsm@...rosoft.com>,
 "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>,
 "Danilo Krummrich" <dakr@...nel.org>,
 "David Howells" <dhowells@...hat.com>, "Tyler Hicks" <code@...icks.com>,
 "Olga Kornievskaia" <okorniev@...hat.com>,
 "Dai Ngo" <Dai.Ngo@...cle.com>, "Amir Goldstein" <amir73il@...il.com>,
 "Namjae Jeon" <linkinjeon@...nel.org>,
 "Steve French" <smfrench@...il.com>,
 "Sergey Senozhatsky" <senozhatsky@...omium.org>,
 "Carlos Maiolino" <cem@...nel.org>,
 "Kuniyuki Iwashima" <kuniyu@...gle.com>,
 "David S. Miller" <davem@...emloft.net>,
 "Eric Dumazet" <edumazet@...gle.com>, "Jakub Kicinski" <kuba@...nel.org>,
 "Paolo Abeni" <pabeni@...hat.com>, "Simon Horman" <horms@...nel.org>,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-nfs@...r.kernel.org, linux-cifs@...r.kernel.org,
 samba-technical@...ts.samba.org, netfs@...ts.linux.dev,
 ecryptfs@...r.kernel.org, linux-unionfs@...r.kernel.org,
 linux-xfs@...r.kernel.org, netdev@...r.kernel.org,
 "Jeff Layton" <jlayton@...nel.org>
Subject: Re: [PATCH 01/13] filelock: push the S_ISREG check down to ->setlease
 handlers

On Tue, 14 Oct 2025, Jeff Layton wrote:
> 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. Ensure that we don't allow directory
> leases by default going forward by explicitly disabling them there.

What is special about atomic_open w.r.t leases?

Thanks,
NeilBrown

> 
> Signed-off-by: Jeff Layton <jlayton@...nel.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 04a3f0e2072461b6e2d3d1cd12f2b089d69a7db3..0b16921fb52e602ea2e0c3de39d9d772af98ba7d 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -1929,6 +1929,9 @@ 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);
> @@ -2018,8 +2021,6 @@ 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))) ||
> 
> -- 
> 2.51.0
> 
>