From ab7c548e266a6324db0994cea58c35b3dc87bade Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 11 May 2016 16:39:38 -0600 Subject: [PATCH] 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: Eric Blake Reviewed-by: Alex Bligh Message-Id: <1463006384-7734-6-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini --- nbd/server.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/nbd/server.c b/nbd/server.c index 41388f5fe9..b0ca9d9771 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -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;