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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ivan Vecera <ivecera@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.15 063/122] net/sched: cls_u32: fix cls_u32 on filter replace
Date:   Wed,  7 Mar 2018 11:37:55 -0800
Message-Id: <20180307191738.432422321@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ivan Vecera <ivecera@redhat.com>


[ Upstream commit eb53f7af6f15285e2f6ada97285395343ce9f433 ]

The following sequence is currently broken:

 # tc qdisc add dev foo ingress
 # tc filter replace dev foo protocol all ingress \
   u32 match u8 0 0 action mirred egress mirror dev bar1
 # tc filter replace dev foo protocol all ingress \
   handle 800::800 pref 49152 \
   u32 match u8 0 0 action mirred egress mirror dev bar2
 Error: cls_u32: Key node flags do not match passed flags.
 We have an error talking to the kernel, -1

The error comes from u32_change() when comparing new and
existing flags. The existing ones always contains one of
TCA_CLS_FLAGS_{,NOT}_IN_HW flag depending on offloading state.
These flags cannot be passed from userspace so the condition
(n->flags != flags) in u32_change() always fails.

Fix the condition so the flags TCA_CLS_FLAGS_NOT_IN_HW and
TCA_CLS_FLAGS_IN_HW are not taken into account.

Fixes: 24d3dc6d27ea ("net/sched: cls_u32: Reflect HW offload status")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/cls_u32.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -928,7 +928,8 @@ static int u32_change(struct net *net, s
 		if (TC_U32_KEY(n->handle) == 0)
 			return -EINVAL;
 
-		if (n->flags != flags)
+		if ((n->flags ^ flags) &
+		    ~(TCA_CLS_FLAGS_IN_HW | TCA_CLS_FLAGS_NOT_IN_HW))
 			return -EINVAL;
 
 		new = u32_init_knode(tp, n);