Author: lstewart
Date: Tue Feb 1 13:32:27 2011
New Revision: 218167
URL: http://svn.freebsd.org/changeset/base/218167
Log:
Algorithm modules can define their own private congestion signal types in the
top 8 bits of the 32 bit signal bit field space for internal use. These
private
signals should not be leaked outside of a module.
Given that many algorithm modules use the NewReno hook functions to simplify
their implementation, the obvious place such a leak would show up is in the
NewReno cong_signal hook function.
- Show the full number of significant bits in the signal type definitions in
<netinet/cc.h>.
- Add a bitmask to simplify figuring out if a given signal is in the private
or
public bit range.
- Add a sanity check in newreno_cong_signal() to ensure private signals are
not
being leaked into the hook function.
Sponsored by: FreeBSD Foundation
Discussed with: David Hayes <dahayes at swin edu au>
MFC after: 1 week
X-MFC with: r215166
Modified:
head/sys/netinet/cc.h
head/sys/netinet/cc/cc_newreno.c
Modified: head/sys/netinet/cc.h
==============================================================================
--- head/sys/netinet/cc.h Tue Feb 1 10:28:05 2011 (r218166)
+++ head/sys/netinet/cc.h Tue Feb 1 13:32:27 2011 (r218167)
@@ -101,10 +101,12 @@ struct cc_var {
* bits (0x01000000 - 0x80000000) are reserved for CC algos to declare their
own
* congestion signal types.
*/
-#define CC_ECN 0x000001/* ECN marked packet received. */
-#define CC_RTO 0x000002/* RTO fired. */
-#define CC_RTO_ERR 0x000004/* RTO fired in error. */
-#define CC_NDUPACK 0x000008/* Threshold of dupack's reached. */
+#define CC_ECN 0x00000001 /* ECN marked packet received.
*/
+#define CC_RTO 0x00000002 /* RTO fired. */
+#define CC_RTO_ERR 0x00000004 /* RTO fired in error. */
+#define CC_NDUPACK 0x00000008 /* Threshold of dupack's
reached. */
+
+#define CC_SIGPRIVMASK 0xFF000000 /* Mask to check if sig is
private. */
/*
* Structure to hold data and function pointers that together represent a
Modified: head/sys/netinet/cc/cc_newreno.c
==============================================================================
--- head/sys/netinet/cc/cc_newreno.c Tue Feb 1 10:28:05 2011
(r218166)
+++ head/sys/netinet/cc/cc_newreno.c Tue Feb 1 13:32:27 2011
(r218167)
@@ -182,6 +182,10 @@ newreno_cong_signal(struct cc_var *ccv,
{
u_int win;
+ /* Catch algos which mistakenly leak private signal types. */
+ KASSERT((type & CC_SIGPRIVMASK) == 0,
+ ("%s: congestion signal type 0x%08x is private\n", __func__, type));
+
win = max(CCV(ccv, snd_cwnd) / 2 / CCV(ccv, t_maxseg), 2) *
CCV(ccv, t_maxseg);
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