From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: [PATCH net 03/13] net: sched: cls_u32: disallow linking to root hnode Date: Sun, 9 Sep 2018 02:31:22 +0100 Message-ID: <20180909013132.3222-4-viro@ZenIV.linux.org.uk> References: <20180909013132.3222-1-viro@ZenIV.linux.org.uk> Cc: Jamal Hadi Salim , Cong Wang , Jiri Pirko To: netdev@vger.kernel.org Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:40852 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726152AbeIIGVW (ORCPT ); Sun, 9 Sep 2018 02:21:22 -0400 In-Reply-To: <20180909013132.3222-1-viro@ZenIV.linux.org.uk> Sender: netdev-owner@vger.kernel.org List-ID: From: Al Viro 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: Al Viro --- net/sched/cls_u32.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index c4782aa808c7..72459b09d910 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -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++; } -- 2.11.0