Commit ab7c548e authored by Eric Blake's avatar Eric Blake Committed by Paolo Bonzini
Browse files

nbd: Reject unknown request flags 



The NBD protocol says that clients should not send a command flag
that has not been negotiated (whether by the client requesting an
option during a handshake, or because we advertise support for the
flag in response to NBD_OPT_EXPORT_NAME), and that servers should
reject invalid flags with EINVAL.  We were silently ignoring the
flags instead.  The client can't rely on our behavior, since it is
their fault for passing the bad flag in the first place, but it's
better to be robust up front than to possibly behave differently
than the client was expecting with the attempted flag.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarAlex Bligh <alex@alex.org.uk>
Message-Id: <1463006384-7734-6-git-send-email-eblake@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 29b6c3b3

nbd/server.c

+5 −0
Original line number Diff line number Diff line
@@ -1072,6 +1072,11 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, 
        rc = command == NBD_CMD_WRITE ? -ENOSPC : -EINVAL;

        goto out;

    }

    if (request->type & ~NBD_CMD_MASK_COMMAND & ~NBD_CMD_FLAG_FUA) {

        LOG("unsupported flags (got 0x%x)",

            request->type & ~NBD_CMD_MASK_COMMAND);

        return -EINVAL;

    }



    rc = 0;