Commit 02a9098e authored Jan 04, 2012 by Eric Dumazet Committed by David S. Miller Jan 04, 2012

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>

parent bd16a6cc

net/sched/sch_sfq.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -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 {

		if (opt) {
		int err = sfq_change(sch, opt);
		if (err)
		return err;

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