From 65907a433ac0ca450c4408080f24c6e4743386b2 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Wed, 11 Jun 2008 11:19:09 +0100 Subject: [PATCH] dccp ccid-2: Bug-Fix - Ack Vectors need to be ignored on request sockets This fixes an oversight from an earlier patch, ensuring that Ack Vectors are not processed on request sockets. The issue is that Ack Vectors must not be parsed on request sockets, since the Ack Vector feature depends on the selection of the (TX) CCID. During the initial handshake the CCIDs are undefined, and so RFC 4340, 10.3 applies: "Using CCID-specific options and feature options during a negotiation for the corresponding CCID feature is NOT RECOMMENDED [...]" And it is not even possible: when the server receives the Request from the client, the CCID and Ack vector features are undefined; when the Ack finalising the 3-way hanshake arrives, the request socket has not been cloned yet into a full socket. (This order is necessary, since otherwise the newly created socket would have to be destroyed whenever an option error occurred - a malicious hacker could simply send garbage options and exploit this.) Signed-off-by: Gerrit Renker --- net/dccp/options.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/dccp/options.c b/net/dccp/options.c index d2a84a2fecee..43bc24e761d0 100644 --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -107,9 +107,11 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, * * CCID-specific options are ignored during connection setup, as * negotiation may still be in progress (see RFC 4340, 10.3). + * The same applies to Ack Vectors, as these depend on the CCID. * */ - if (dreq != NULL && opt >= 128) + if (dreq != NULL && (opt >= 128 || + opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1)) goto ignore_option; switch (opt) { -- 2.20.1