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net_sched: fix tcm_parent in tc filter dump 

When we tell kernel to dump filters from root (ffff:ffff),
those filters on ingress (ffff:0000) are matched, but their
true parents must be dumped as they are. However, kernel
dumps just whatever we tell it, that is either ffff:ffff
or ffff:0000:

 $ nl-cls-list --dev=dummy0 --parent=root
 cls basic dev dummy0 id none parent root prio 49152 protocol ip match-all
 cls basic dev dummy0 id :1 parent root prio 49152 protocol ip match-all
 $ nl-cls-list --dev=dummy0 --parent=ffff:
 cls basic dev dummy0 id none parent ffff: prio 49152 protocol ip match-all
 cls basic dev dummy0 id :1 parent ffff: prio 49152 protocol ip match-all

This is confusing and misleading, more importantly this is
a regression since 4.15, so the old behavior must be restored.

And, when tc filters are installed on a tc class, the parent
should be the classid, rather than the qdisc handle. Commit
edf6711c98 ("net: sched: remove classid and q fields from tcf_proto")
removed the classid we save for filters, we can just restore
this classid in tcf_block.

Steps to reproduce this:
 ip li set dev dummy0 up
 tc qd add dev dummy0 ingress
 tc filter add dev dummy0 parent ffff: protocol arp basic action pass
 tc filter show dev dummy0 root

Before this patch:
 filter protocol arp pref 49152 basic
 filter protocol arp pref 49152 basic handle 0x1
	action order 1: gact action pass
	 random type none pass val 0
	 index 1 ref 1 bind 1

After this patch:
 filter parent ffff: protocol arp pref 49152 basic
 filter parent ffff: protocol arp pref 49152 basic handle 0x1
 	action order 1: gact action pass
 	 random type none pass val 0
	 index 1 ref 1 bind 1

Fixes: a10fa20101 ("net: sched: propagate q and parent from caller down to tcf_fill_node")
Fixes: edf6711c98 ("net: sched: remove classid and q fields from tcf_proto")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2020-04-30 20:53:49 -07:00 committed by David S. Miller
parent 071a43e660
commit a7df4870d7
2 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/sch_generic.h
View File

@ -407,6 +407,7 @@ struct tcf_block {
struct mutex lock;
struct list_head chain_list;
u32 index; /* block index for shared blocks */
u32 classid; /* which class this block belongs to */
refcount_t refcnt;
struct net *net;
struct Qdisc *q;

8
net/sched/cls_api.c
View File

@ -2070,6 +2070,7 @@ replay:
err = PTR_ERR(block);
goto errout;
}
block->classid = parent;
chain_index = tca[TCA_CHAIN] ? nla_get_u32(tca[TCA_CHAIN]) : 0;
if (chain_index > TC_ACT_EXT_VAL_MASK) {
@ -2612,12 +2613,10 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
return skb->len;
parent = tcm->tcm_parent;
if (!parent) {
if (!parent)
q = dev->qdisc;
parent = q->handle;
} else {
else
q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
}
if (!q)
goto out;
cops = q->ops->cl_ops;
@ -2633,6 +2632,7 @@ static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
block = cops->tcf_block(q, cl, NULL);
if (!block)
goto out;
parent = block->classid;
if (tcf_block_shared(block))
q = NULL;
}