Commit 27594ec4 authored by Al Viro's avatar Al Viro Committed by David S. Miller

net: sched: cls_u32: disallow linking to root hnode

Operation makes no sense.  Nothing will actually break if we do so
(depth limit in u32_classify() will prevent infinite loops), but
according to maintainers it's best prohibited outright.

NOTE: doing so guarantees that u32_destroy() will trigger the call
of u32_destroy_hnode(); we might want to make that unconditional.

Test:
tc qdisc add dev eth0 ingress
tc filter add dev eth0 parent ffff: protocol ip prio 100 u32 \
link 800: offset at 0 mask 0f00 shift 6 plus 0 eat match ip protocol 6 ff
should fail with
Error: cls_u32: Not linking to root node
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b44ef845
......@@ -797,6 +797,10 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp,
NL_SET_ERR_MSG_MOD(extack, "Link hash table not found");
return -EINVAL;
}
if (ht_down->is_root) {
NL_SET_ERR_MSG_MOD(extack, "Not linking to root node");
return -EINVAL;
}
ht_down->refcnt++;
}
......
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