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sch_tbf: handle too small burst

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If a too small burst is inadvertently set on TBF, we might trigger
a bug in tbf_segment(), as 'skb' instead of 'segs' was used in a
qdisc_reshape_fail() call.

tc qdisc add dev eth0 root handle 1: tbf latency 50ms burst 1KB rate
50mbit

Fix the bug, and add a warning, as such configuration is not
going to work anyway for non GSO packets.

(For some reason, one has to use a burst >= 1520 to get a working
configuration, even with old kernels. This is a probable iproute2/tc
bug)

Based on a report and initial patch from Yang Yingliang

Fixes: e43ac79a4b ("sch_tbf: segment too big GSO packets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-11-23 12:59:20 -08:00 committed by David S. Miller
parent 1fa4c710b6
commit 4d0820cf6a
1 changed files with 25 additions and 7 deletions
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32
net/sched/sch_tbf.c
View File

@ -21,6 +21,7 @@
#include <net/netlink.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/tcp.h>
/* Simple Token Bucket Filter.
@ -117,6 +118,22 @@ struct tbf_sched_data {
};
/*
* Return length of individual segments of a gso packet,
* including all headers (MAC, IP, TCP/UDP)
*/
static unsigned int skb_gso_seglen(const struct sk_buff *skb)
{
unsigned int hdr_len = skb_transport_header(skb) - skb_mac_header(skb);
const struct skb_shared_info *shinfo = skb_shinfo(skb);
if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
hdr_len += tcp_hdrlen(skb);
else
hdr_len += sizeof(struct udphdr);
return hdr_len + shinfo->gso_size;
}
/* GSO packet is too big, segment it so that tbf can transmit
* each segment in time
*/
@ -136,12 +153,8 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch)
while (segs) {
nskb = segs->next;
segs->next = NULL;
if (likely(segs->len <= q->max_size)) {
qdisc_skb_cb(segs)->pkt_len = segs->len;
ret = qdisc_enqueue(segs, q->qdisc);
} else {
ret = qdisc_reshape_fail(skb, sch);
}
qdisc_skb_cb(segs)->pkt_len = segs->len;
ret = qdisc_enqueue(segs, q->qdisc);
if (ret != NET_XMIT_SUCCESS) {
if (net_xmit_drop_count(ret))
sch->qstats.drops++;
@ -163,7 +176,7 @@ static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch)
int ret;
if (qdisc_pkt_len(skb) > q->max_size) {
if (skb_is_gso(skb))
if (skb_is_gso(skb) && skb_gso_seglen(skb) <= q->max_size)
return tbf_segment(skb, sch);
return qdisc_reshape_fail(skb, sch);
}
@ -319,6 +332,11 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
if (max_size < 0)
goto done;
if (max_size < psched_mtu(qdisc_dev(sch)))
pr_warn_ratelimited("sch_tbf: burst %u is lower than device %s mtu (%u) !\n",
max_size, qdisc_dev(sch)->name,
psched_mtu(qdisc_dev(sch)));
if (q->qdisc != &noop_qdisc) {
err = fifo_set_limit(q->qdisc, qopt->limit);
if (err)