Avoid passing stream fsps to the VFS, fixes a problem deleting streams
When using vfs_streams_xattr, for a pathref handle of a stream the system fd will be a fake fd created by pipe() in vfs_fake_fd().
For the following callchain we wrongly pass a stream fsp to SMB_VFS_FGET_NT_ACL():
SMB_VFS_CREATE_FILE(..., "file:stream", ...)
=> open_file():
if (open_fd):
-> taking the else branch:
-> smbd_check_access_rights_fsp(stream_fsp)
-> SMB_VFS_FGET_NT_ACL(stream_fsp)This is obviously wrong and can lead to strange permission errors when using vfs_acl_xattr:
in vfs_acl_xattr we will try to read the stored ACL by calling fgetxattr(fake-fd) which of course faild with EBADF. Now unfortunately the vfs_acl_xattr code ignores the specific error and handles this as if there was no ACL stored and subsequently runs the code to synthesize a default ACL according to the setting of "acl:default acl style".
As the correct access check for streams has already been carried out by calling check_base_file_access() from create_file_unixpath(), the above problem is not a security issue: it can only lead to "decreased" permissions resulting in unexpected ACCESS_DENIED errors.