[PATCH 5.13 065/127] sch_cake: fix srchost/dsthost hashing mode

Sasha Levin
2021-08-24T17:01:20Z

From: Toke Høiland-Jørgensen <toke@redhat.com>

[ Upstream commit 86b9bbd332d0510679c7fedcee3e3bd278be5756 ]

When adding support for using the skb->hash value as the flow hash in CAKE,
I accidentally introduced a logic error that broke the host-only isolation
modes of CAKE (srchost and dsthost keywords). Specifically, the flow_hash
variable should stay initialised to 0 in cake_hash() in pure host-based
hashing mode. Add a check for this before using the skb->hash value as
flow_hash.

Fixes: b0c19ed6088a ("sch_cake: Take advantage of skb->hash where appropriate")
Reported-by: Pete Heist <pete@heistp.net>
Tested-by: Pete Heist <pete@heistp.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/sch_cake.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index 951542843cab..28af8b1e1bb1 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -720,7 +720,7 @@ static u32 cake_hash(struct cake_tin_data *q, const struct sk_buff *skb,
skip_hash:
if (flow_override)
flow_hash = flow_override - 1;
- else if (use_skbhash)
+ else if (use_skbhash && (flow_mode & CAKE_FLOW_FLOWS))
flow_hash = skb->hash;
if (host_override) {
dsthost_hash = host_override - 1;
--
2.30.2