kernel: backport flow dissector batman-adv support

Improves performance on multicore systems handling batman-adv traffic

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 108 insertions, 0 deletions

diff --git a/target/linux/generic/backport-4.14/274-flow_dissector-Parse-batman-adv-unicast-headers.patch b/target/linux/generic/backport-4.14/274-flow_dissector-Parse-batman-adv-unicast-headers.patch
new file mode 100644
index 0000000000..b0b2823cc9
--- /dev/null
+++ b/target/linux/generic/backport-4.14/274-flow_dissector-Parse-batman-adv-unicast-headers.patch
@@ -0,0 +1,108 @@
+From: Sven Eckelmann <sven.eckelmann@openmesh.com>
+Date: Thu, 21 Dec 2017 10:17:42 +0100
+Subject: [PATCH] flow_dissector: Parse batman-adv unicast headers
+
+The batman-adv unicast packets contain a full layer 2 frame in encapsulated
+form. The flow dissector must therefore be able to parse the batman-adv
+unicast header to reach the layer 2+3 information.
+
+  +--------------------+
+  | ip(v6)hdr          |
+  +--------------------+
+  | inner ethhdr       |
+  +--------------------+
+  | batadv unicast hdr |
+  +--------------------+
+  | outer ethhdr       |
+  +--------------------+
+
+The obtained information from the upper layer can then be used by RPS to
+schedule the processing on separate cores. This allows better distribution
+of multiple flows from the same neighbor to different cores.
+
+Signed-off-by: Sven Eckelmann <sven.eckelmann@openmesh.com>
+Reviewed-by: Jiri Pirko <jiri@mellanox.com>
+Acked-by: Willem de Bruijn <willemb@google.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+
+--- a/net/core/flow_dissector.c
++++ b/net/core/flow_dissector.c
+@@ -22,6 +22,7 @@
+ #include <linux/tcp.h>
+ #include <net/flow_dissector.h>
+ #include <scsi/fc/fc_fcoe.h>
++#include <uapi/linux/batadv_packet.h>
+ 
+ static void dissector_set_key(struct flow_dissector *flow_dissector,
+ 			      enum flow_dissector_key_id key_id)
+@@ -338,6 +339,57 @@ __skb_flow_dissect_gre(const struct sk_b
+ 	return FLOW_DISSECT_RET_PROTO_AGAIN;
+ }
+ 
++/**
++ * __skb_flow_dissect_batadv() - dissect batman-adv header
++ * @skb: sk_buff to with the batman-adv header
++ * @key_control: flow dissectors control key
++ * @data: raw buffer pointer to the packet, if NULL use skb->data
++ * @p_proto: pointer used to update the protocol to process next
++ * @p_nhoff: pointer used to update inner network header offset
++ * @hlen: packet header length
++ * @flags: any combination of FLOW_DISSECTOR_F_*
++ *
++ * ETH_P_BATMAN packets are tried to be dissected. Only
++ * &struct batadv_unicast packets are actually processed because they contain an
++ * inner ethernet header and are usually followed by actual network header. This
++ * allows the flow dissector to continue processing the packet.
++ *
++ * Return: FLOW_DISSECT_RET_PROTO_AGAIN when &struct batadv_unicast was found,
++ *  FLOW_DISSECT_RET_OUT_GOOD when dissector should stop after encapsulation,
++ *  otherwise FLOW_DISSECT_RET_OUT_BAD
++ */
++static enum flow_dissect_ret
++__skb_flow_dissect_batadv(const struct sk_buff *skb,
++			  struct flow_dissector_key_control *key_control,
++			  void *data, __be16 *p_proto, int *p_nhoff, int hlen,
++			  unsigned int flags)
++{
++	struct {
++		struct batadv_unicast_packet batadv_unicast;
++		struct ethhdr eth;
++	} *hdr, _hdr;
++
++	hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr), data, hlen,
++				   &_hdr);
++	if (!hdr)
++		return FLOW_DISSECT_RET_OUT_BAD;
++
++	if (hdr->batadv_unicast.version != BATADV_COMPAT_VERSION)
++		return FLOW_DISSECT_RET_OUT_BAD;
++
++	if (hdr->batadv_unicast.packet_type != BATADV_UNICAST)
++		return FLOW_DISSECT_RET_OUT_BAD;
++
++	*p_proto = hdr->eth.h_proto;
++	*p_nhoff += sizeof(*hdr);
++
++	key_control->flags |= FLOW_DIS_ENCAPSULATION;
++	if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
++		return FLOW_DISSECT_RET_OUT_GOOD;
++
++	return FLOW_DISSECT_RET_PROTO_AGAIN;
++}
++
+ static void
+ __skb_flow_dissect_tcp(const struct sk_buff *skb,
+ 		       struct flow_dissector *flow_dissector,
+@@ -717,6 +769,11 @@ proto_again:
+ 					       nhoff, hlen);
+ 		break;
+ 
++	case htons(ETH_P_BATMAN):
++		fdret = __skb_flow_dissect_batadv(skb, key_control, data,
++						  &proto, &nhoff, hlen, flags);
++		break;
++
+ 	default:
+ 		fdret = FLOW_DISSECT_RET_OUT_BAD;
+ 		break;