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flow_dissector: Do not count vlan tags inside tunnel payload 

We've met the problem that when there is a vlan tag inside
GRE encapsulation, the match of num_of_vlans fails.
It is caused by the vlan tag inside GRE payload has been
counted into num_of_vlans, which is not expected.

One example packet is like this:
Ethernet II, Src: Broadcom_68:56:07 (00:10:18:68:56:07)
                   Dst: Broadcom_68:56:08 (00:10:18:68:56:08)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 100
Internet Protocol Version 4, Src: 192.168.1.4, Dst: 192.168.1.200
Generic Routing Encapsulation (Transparent Ethernet bridging)
Ethernet II, Src: Broadcom_68:58:07 (00:10:18:68:58:07)
                   Dst: Broadcom_68:58:08 (00:10:18:68:58:08)
802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 200
...
It should match the (num_of_vlans 1) rule, but it matches
the (num_of_vlans 2) rule.

The vlan tags inside the GRE or other tunnel encapsulated payload
should not be taken into num_of_vlans.
The fix is to stop counting the vlan number when the encapsulation
bit is set.

Fixes: 34951fcf26 ("flow_dissector: Add number of vlan tags dissector")
Signed-off-by: Qingqing Yang <qingqing.yang@broadcom.com>
Reviewed-by: Boris Sukholitko <boris.sukholitko@broadcom.com>
Link: https://lore.kernel.org/r/20220919074808.136640-1-qingqing.yang@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Qingqing Yang 2022-09-19 15:48:08 +08:00 committed by Jakub Kicinski
parent 1d14b30b5a
commit 9f87eb4246
1 changed files with 2 additions and 2 deletions
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4
net/core/flow_dissector.c
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@ -1201,8 +1201,8 @@ proto_again:
nhoff += sizeof(*vlan);
}
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_NUM_OF_VLANS)) {
if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_NUM_OF_VLANS) &&
!(key_control->flags & FLOW_DIS_ENCAPSULATION)) {
struct flow_dissector_key_num_of_vlans *key_nvs;
key_nvs = skb_flow_dissector_target(flow_dissector,