| From 5c04a1c8f4da7661eb294b8800266537bcf9f359 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 19 Jul 2021 16:41:24 -0700 |
| Subject: net/sched: act_skbmod: Skip non-Ethernet packets |
| |
| From: Peilin Ye <peilin.ye@bytedance.com> |
| |
| [ Upstream commit 727d6a8b7ef3d25080fad228b2c4a1d4da5999c6 ] |
| |
| Currently tcf_skbmod_act() assumes that packets use Ethernet as their L2 |
| protocol, which is not always the case. As an example, for CAN devices: |
| |
| $ ip link add dev vcan0 type vcan |
| $ ip link set up vcan0 |
| $ tc qdisc add dev vcan0 root handle 1: htb |
| $ tc filter add dev vcan0 parent 1: protocol ip prio 10 \ |
| matchall action skbmod swap mac |
| |
| Doing the above silently corrupts all the packets. Do not perform skbmod |
| actions for non-Ethernet packets. |
| |
| Fixes: 86da71b57383 ("net_sched: Introduce skbmod action") |
| Reviewed-by: Cong Wang <cong.wang@bytedance.com> |
| Signed-off-by: Peilin Ye <peilin.ye@bytedance.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| net/sched/act_skbmod.c | 12 ++++++++---- |
| 1 file changed, 8 insertions(+), 4 deletions(-) |
| |
| diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c |
| index 81a1c67335be..8d17a543cc9f 100644 |
| --- a/net/sched/act_skbmod.c |
| +++ b/net/sched/act_skbmod.c |
| @@ -6,6 +6,7 @@ |
| */ |
| |
| #include <linux/module.h> |
| +#include <linux/if_arp.h> |
| #include <linux/init.h> |
| #include <linux/kernel.h> |
| #include <linux/skbuff.h> |
| @@ -33,6 +34,13 @@ static int tcf_skbmod_act(struct sk_buff *skb, const struct tc_action *a, |
| tcf_lastuse_update(&d->tcf_tm); |
| bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb); |
| |
| + action = READ_ONCE(d->tcf_action); |
| + if (unlikely(action == TC_ACT_SHOT)) |
| + goto drop; |
| + |
| + if (!skb->dev || skb->dev->type != ARPHRD_ETHER) |
| + return action; |
| + |
| /* XXX: if you are going to edit more fields beyond ethernet header |
| * (example when you add IP header replacement or vlan swap) |
| * then MAX_EDIT_LEN needs to change appropriately |
| @@ -41,10 +49,6 @@ static int tcf_skbmod_act(struct sk_buff *skb, const struct tc_action *a, |
| if (unlikely(err)) /* best policy is to drop on the floor */ |
| goto drop; |
| |
| - action = READ_ONCE(d->tcf_action); |
| - if (unlikely(action == TC_ACT_SHOT)) |
| - goto drop; |
| - |
| p = rcu_dereference_bh(d->skbmod_p); |
| flags = p->flags; |
| if (flags & SKBMOD_F_DMAC) |
| -- |
| 2.30.2 |
| |