On 8 Apr 2016, at 23:05, Eric Blake <ebl...@redhat.com> wrote:
> 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: Eric Blake <ebl...@redhat.com>
Reviewed-by: Alex Bligh <a...@alex.org.uk>
> ---
> nbd/server.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/nbd/server.c b/nbd/server.c
> index 81afae2..a10294e 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
> @@ -984,6 +984,11 @@ static ssize_t nbd_co_receive_request(NBDRequest *req,
> struct nbd_request *reque
> 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;
> + }
> if ((request->from + request->len) < request->from) {
> LOG("integer overflow detected! "
> "you're probably being attacked");
> --
> 2.5.5
>
>
--
Alex Bligh
