From 02a9098ede0dc7e28c16a03fa7fba86a05219478 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 4 Jan 2012 06:23:01 +0000
Subject: net_sched: sfq: always randomize hash perturbation

SFQ q->perturbation is used in sfq_hash() as an input to Jenkins hash.

We currently randomize this 32bit value only if a perturbation timer is
setup.

Its much better to always initialize it to defeat attackers, or else
they can predict very well what kind of packets they have to forge to
hit a particular flow.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/sched/sch_sfq.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

(limited to 'net')

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 16feb88503a..843018154a5 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -591,12 +591,12 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
 	q->cur_depth = 0;
 	q->tail = NULL;
 	q->divisor = SFQ_DEFAULT_HASH_DIVISOR;
-	if (opt == NULL) {
-		q->quantum = psched_mtu(qdisc_dev(sch));
-		q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
-		q->perturb_period = 0;
-		q->perturbation = net_random();
-	} else {
+	q->quantum = psched_mtu(qdisc_dev(sch));
+	q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);
+	q->perturb_period = 0;
+	q->perturbation = net_random();
+
+	if (opt) {
 		int err = sfq_change(sch, opt);
 		if (err)
 			return err;
-- 
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