On Sun, Nov 07, 2021 at 01:49:47PM -0800, Jeremy Allison wrote:
behavior. From 'man 2 fsync': NOTES On some UNIX systems (but not Linux), fd must be a writable file descriptor.If this is actually what is happening, Samba is implementing the Windows semantics, and not the Linux ones (as we should). From the Microsoft MS-SMB2 spec: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/026984f6-38af-4408-8200-50557eb0a286 -------------------------------------------------------------------------- 3.3.5.11 Receiving an SMB2 FLUSH Request 10/04/2021 When the server receives a request with an SMB2 header with a Command value equal to SMB2 FLUSH, message handling proceeds as follows: The server MUST locate the session, as specified in section 3.3.5.2.9. The server MUST locate the tree connection, as specified in section 3.3.5.2.11. Next the server MUST locate the open being flushed by performing a lookup in the Session.OpenTable, using the FileId.Volatile of the request as the lookup key. If no open is found, or if Open.DurableFileId is not equal to FileId.Persistent, the server MUST fail the request with STATUS_FILE_CLOSED. Otherwise, the server MUST locate the Request in Connection.RequestList for which Request.MessageId matches the MessageId value in the SMB2 header, and set Request.Open to the Open. If the Open is on a file and Open.GrantedAccess includes neither FILE_WRITE_DATA nor FILE_APPEND_DATA, the server MUST fail the request with STATUS_ACCESS_DENIED. If the Open is on a directory and Open.GrantedAccess includes neither FILE_ADD_FILE nor FILE_ADD_SUBDIRECTORY, the server MUST fail the request with STATUS_ACCESS_DENIED. --------------------------------------------------------------------------
Steve, I just took a look inside cifsfs and it looks like the smb2_flush() function is being called on a file descriptor without a check that the fd is open for writing as far as I can tell. Am I missing such a check ? Can you investigate to see if this is the case ? This would also fail against a Windows server too I think. Jeremy.
