net/sched: cls_u32: fix cls_u32 on filter replace

Web:        https://git.kernel.org/torvalds/c/eb53f7af6f15285e2f6ada97285395343ce9f433
Commit:     eb53f7af6f15285e2f6ada97285395343ce9f433
Parent:     3968523f855050b8195134da951b87c20bd66130
Refname:    refs/heads/master
Author:     Ivan Vecera <[email protected]>
AuthorDate: Thu Feb 8 16:10:39 2018 +0100
Committer:  David S. Miller <[email protected]>
CommitDate: Thu Feb 8 15:27:58 2018 -0500

    net/sched: cls_u32: fix cls_u32 on filter replace
    
    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 <[email protected]>
    Signed-off-by: David S. Miller <[email protected]>
---
 net/sched/cls_u32.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c
index 6311a548046b..c75e68e839c7 100644
--- a/net/sched/cls_u32.c
+++ b/net/sched/cls_u32.c
@@ -955,7 +955,8 @@ static int u32_change(struct net *net, struct sk_buff *in_skb,
 			return -EINVAL;
 		}
 
-		if (n->flags != flags) {
+		if ((n->flags ^ flags) &
+		    ~(TCA_CLS_FLAGS_IN_HW | TCA_CLS_FLAGS_NOT_IN_HW)) {
 			NL_SET_ERR_MSG_MOD(extack, "Key node flags do not match passed flags");
 			return -EINVAL;
 		}
--
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