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
edf6711c9840 ("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: a10fa20101ae ("net: sched: propagate q and parent from caller down to tcf_fill_node")
Fixes: edf6711c9840 ("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>

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 25d2ec4c8f00495cb8b25b0e7a24d1f808e50c90..8428aa6142655666715743e60bc74855f9f8d008 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -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;

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index 55bd1429678f996a328f2be6fdb0b7e0de771168..c0e5b64b3caf287d0ff73b6d26ef284e44123d4f 100644 (file)
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -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;
        }