[PATCH 4.15 063/122] net/sched: cls_u32: fix cls_u32 on filter replace

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

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

From: Ivan Vecera <ivecera@xxxxxxxxxx>


[ 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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 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);