Re: [PATCH] flow_dissector: Fix vlan header offset in __skb_flow_dissect
From: Stanislav Fomichev <sdf@fomichev.me>
Date: 2019-06-19 18:39:42
Also in:
lkml
On 06/20, YueHaibing wrote:
quoted hunk ↗ jump to hunk
We build vlan on top of bonding interface, which vlan offload is off, bond mode is 802.3ad (LACP) and xmit_hash_policy is BOND_XMIT_POLICY_ENCAP34. __skb_flow_dissect() fails to get information from protocol headers encapsulated within vlan, because 'nhoff' is points to IP header, so bond hashing is based on layer 2 info, which fails to distribute packets across slaves. Fixes: d5709f7ab776 ("flow_dissector: For stripped vlan, get vlan info from skb->vlan_tci") Signed-off-by: YueHaibing <redacted> --- net/core/flow_dissector.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 415b95f..2a52abb 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c@@ -785,6 +785,9 @@ bool __skb_flow_dissect(const struct sk_buff *skb, skb && skb_vlan_tag_present(skb)) { proto = skb->protocol; } else { + if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX) + nhoff -= sizeof(*vlan); +
Should we instead fix the place where the skb is allocated to properly pull vlan (skb_vlan_untag)? I'm not sure this particular place is supposed to work with an skb. Having an skb with nhoff pointing to IP header but missing skb_vlan_tag_present() when with proto==ETH_P_8021xx seems weird.
vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan),
data, hlen, &_vlan);
if (!vlan) {
--
2.7.0