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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2010-10-11 20:35:40 +0200
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2010-10-12 06:57:40 +0200
commit0b53d4604ac2b4f2faa9a62a04ea9b383ad2efe0 (patch)
tree70ed0d136ef719f33655f78b31650d1c88cd3e00 /net/dccp/minisocks.c
parent0ed8ddf4045fcfcac36bad753dc4046118c603ec (diff)
downloadop-kernel-dev-0b53d4604ac2b4f2faa9a62a04ea9b383ad2efe0.zip
op-kernel-dev-0b53d4604ac2b4f2faa9a62a04ea9b383ad2efe0.tar.gz
dccp: fix the adjustments to AWL and SWL
This fixes a problem and a potential loophole with regard to seqno/ackno validity: currently the initial adjustments to AWL/SWL are only performed once at the begin of the connection, during the handshake. Since the Sequence Window feature is always greater than Wmin=32 (7.5.2), it is however necessary to perform these adjustments at least for the first W/W' (variables as per 7.5.1) packets in the lifetime of a connection. This requirement is complicated by the fact that W/W' can change at any time during the lifetime of a connection. Therefore it is better to perform that safety check each time SWL/AWL are updated, as implemented by the patch. A second problem solved by this patch is that the remote/local Sequence Window feature values (which set the bounds for AWL/SWL/SWH) are undefined until the feature negotiation has completed. During the initial handshake we have more stringent sequence number protection; the changes added by this patch effect that {A,S}W{L,H} are within the correct bounds at the instant that feature negotiation completes (since the SeqWin feature activation handlers call dccp_update_gsr/gss()). Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Diffstat (limited to 'net/dccp/minisocks.c')
-rw-r--r--net/dccp/minisocks.c30
1 files changed, 9 insertions, 21 deletions
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 128b089..d7041a0 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -121,30 +121,18 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
*
* Choose S.ISS (initial seqno) or set from Init Cookies
* Initialize S.GAR := S.ISS
- * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
- */
- newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
- dccp_update_gss(newsk, dreq->dreq_iss);
-
- newdp->dccps_isr = dreq->dreq_isr;
- dccp_update_gsr(newsk, dreq->dreq_isr);
-
- /*
- * SWL and AWL are initially adjusted so that they are not less than
- * the initial Sequence Numbers received and sent, respectively:
- * SWL := max(GSR + 1 - floor(W/4), ISR),
- * AWL := max(GSS - W' + 1, ISS).
- * These adjustments MUST be applied only at the beginning of the
- * connection.
+ * Set S.ISR, S.GSR from packet (or Init Cookies)
+ *
+ * Setting AWL/AWH and SWL/SWH happens as part of the feature
+ * activation below, as these windows all depend on the local
+ * and remote Sequence Window feature values (7.5.2).
*/
- dccp_set_seqno(&newdp->dccps_swl,
- max48(newdp->dccps_swl, newdp->dccps_isr));
- dccp_set_seqno(&newdp->dccps_awl,
- max48(newdp->dccps_awl, newdp->dccps_iss));
+ newdp->dccps_gss = newdp->dccps_iss = dreq->dreq_iss;
+ newdp->dccps_gar = newdp->dccps_iss;
+ newdp->dccps_gsr = newdp->dccps_isr = dreq->dreq_isr;
/*
- * Activate features after initialising the sequence numbers,
- * since CCID initialisation may depend on GSS, ISR, ISS etc.
+ * Activate features: initialise CCIDs, sequence windows etc.
*/
if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
/* It is still raw copy of parent, so invalidate
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