On Sun, Jul 20, 2025 at 11:32:48PM +0300, Ahmet Eray Karadag wrote:

From: Steve French stfrench@microsoft.com

Some servers (including Samba), support the SMB3.1.1 POSIX Extensions (which use reparse points for handling special files) but do not properly advertise file system attribute FILE_SUPPORTS_REPARSE_POINTS. Although we don't check for this attribute flag when querying special file information, we do check it when creating special files which causes them to fail unnecessarily. If we have negotiated SMB3.1.1 POSIX Extensions with the server we can expect the server to support creating special files via reparse points, and even if the server fails the operation due to really forbidding creating special files, then it should be no problem and is more likely to return a more accurate rc in any case (e.g. EACCES instead of EOPNOTSUPP).

Allow creating special files as long as the server supports either reparse points or the SMB3.1.1 POSIX Extensions (note that if the "sfu" mount option is specified it uses a different way of storing special files that does not rely on reparse points).

Cc: stable@vger.kernel.org Fixes: 6c06be908ca19 ("cifs: Check if server supports reparse points before using them") Acked-by: Ralph Boehme slow@samba.org Acked-by: Paulo Alcantara (Red Hat) pc@manguebit.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Ahmet Eray Karadag eraykrdg1@gmail.com

---

fs/smb/client/smb2inode.c | 3 ++- fs/smb/client/smb2ops.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c index 2a3e46b8e15a..a11a2a693c51 100644 --- a/fs/smb/client/smb2inode.c +++ b/fs/smb/client/smb2inode.c @@ -1346,7 +1346,8 @@ struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data, * empty object on the server. */ if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS))

• return ERR_PTR(-EOPNOTSUPP);
  

• if (!tcon->posix_extensions)
  

• 	return ERR_PTR(-EOPNOTSUPP);
  

oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, SYNCHRONIZE | DELETE | diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index cb659256d219..938a8a7c5d21 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -5260,7 +5260,8 @@ static int smb2_make_node(unsigned int xid, struct inode *inode, if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) { rc = cifs_sfu_make_node(xid, inode, dentry, tcon, full_path, mode, dev);

• } else if (le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) {

• } else if ((le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS)

• || (tcon->posix_extensions)) {
  

  rc = smb2_mknod_reparse(xid, inode, dentry, tcon, full_path, mode, dev); }

-- 2.34.1

<formletter>

This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.

</formletter>