@@ -603,6 +603,7 @@ enum {
TCA_NETEM_JITTER64,
TCA_NETEM_SLOT,
TCA_NETEM_SLOT_DIST,
+ TCA_NETEM_BURSTING,
__TCA_NETEM_MAX,
};
@@ -615,6 +616,7 @@ struct tc_netem_qopt {
__u32 gap; /* re-ordering gap (0 for none) */
__u32 duplicate; /* random packet dup (0=none ~0=100%) */
__u32 jitter; /* random jitter in latency (us) */
+ __u32 bursting; /* send packets in bursts (us) */
};
struct tc_netem_corr {
@@ -85,6 +85,7 @@ struct netem_sched_data {
s64 latency;
s64 jitter;
+ u32 bursting;
u32 loss;
u32 ecn;
u32 limit;
@@ -467,7 +468,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
/* If a delay is expected, orphan the skb. (orphaning usually takes
* place at TX completion time, so _before_ the link transit delay)
*/
- if (q->latency || q->jitter || q->rate)
+ if (q->latency || q->jitter || q->rate || q->bursting)
skb_orphan_partial(skb);
/*
@@ -527,8 +528,17 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
qdisc_qstats_backlog_inc(sch, skb);
cb = netem_skb_cb(skb);
- if (q->gap == 0 || /* not doing reordering */
- q->counter < q->gap - 1 || /* inside last reordering gap */
+ if (q->bursting > 0) {
+ u64 now;
+
+ now = ktime_get_ns();
+
+ cb->time_to_send = now - (now % q->bursting) + q->bursting;
+
+ ++q->counter;
+ tfifo_enqueue(skb, sch);
+ } else if (q->gap == 0 || /* not doing reordering */
+ q->counter < q->gap - 1 || /* inside last reordering gap */
q->reorder < get_crandom(&q->reorder_cor)) {
u64 now;
s64 delay;
@@ -927,6 +937,7 @@ static const struct nla_policy netem_policy[TCA_NETEM_MAX + 1] = {
[TCA_NETEM_ECN] = { .type = NLA_U32 },
[TCA_NETEM_RATE64] = { .type = NLA_U64 },
[TCA_NETEM_LATENCY64] = { .type = NLA_S64 },
+ [TCA_NETEM_BURSTING] = { .type = NLA_U64 },
[TCA_NETEM_JITTER64] = { .type = NLA_S64 },
[TCA_NETEM_SLOT] = { .len = sizeof(struct tc_netem_slot) },
};
@@ -1001,6 +1012,7 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt,
q->latency = PSCHED_TICKS2NS(qopt->latency);
q->jitter = PSCHED_TICKS2NS(qopt->jitter);
+ q->bursting = PSCHED_TICKS2NS(qopt->bursting);
q->limit = qopt->limit;
q->gap = qopt->gap;
q->counter = 0;
@@ -1032,6 +1044,9 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt,
if (tb[TCA_NETEM_LATENCY64])
q->latency = nla_get_s64(tb[TCA_NETEM_LATENCY64]);
+ if (tb[TCA_NETEM_BURSTING])
+ q->bursting = nla_get_u64(tb[TCA_NETEM_BURSTING]);
+
if (tb[TCA_NETEM_JITTER64])
q->jitter = nla_get_s64(tb[TCA_NETEM_JITTER64]);
@@ -1150,6 +1165,9 @@ static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
UINT_MAX);
qopt.jitter = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->jitter),
UINT_MAX);
+ qopt.bursting = min_t(psched_tdiff_t, PSCHED_NS2TICKS(q->bursting),
+ UINT_MAX);
+
qopt.limit = q->limit;
qopt.loss = q->loss;
qopt.gap = q->gap;
This commit implements packet bursting in the NetEm scheduler. This allows system administrators to hold back outgoing packets and release them at a multiple of a time quantum. This feature can be used to prevent timing attacks caused by network latency. Signed-off-by: Niclas Hedam <niclas@hed.am> --- v2: add enum at end of list (Cong Wang) v3: fixed formatting of commit diff (Toke Høiland-Jørgensen) include/uapi/linux/pkt_sched.h | 2 ++ net/sched/sch_netem.c | 24 +++++++++++++++++++++--- 2 files changed, 23 insertions(+), 3 deletions(-) -- 2.25.1