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Commit fac8e0f5 authored by Jesse Gross's avatar Jesse Gross Committed by David S. Miller
Browse files

tunnels: Don't apply GRO to multiple layers of encapsulation. 



When drivers express support for TSO of encapsulated packets, they
only mean that they can do it for one layer of encapsulation.
Supporting additional levels would mean updating, at a minimum,
more IP length fields and they are unaware of this.

No encapsulation device expresses support for handling offloaded
encapsulated packets, so we won't generate these types of frames
in the transmit path. However, GRO doesn't have a check for
multiple levels of encapsulation and will attempt to build them.

UDP tunnel GRO actually does prevent this situation but it only
handles multiple UDP tunnels stacked on top of each other. This
generalizes that solution to prevent any kind of tunnel stacking
that would cause problems.

Fixes: bf5a755f ("net-gre-gro: Add GRE support to the GRO stack")
Signed-off-by: default avatarJesse Gross <jesse@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b8cba75b

include/linux/netdevice.h

+2 −2
Original line number Diff line number Diff line
@@ -2096,8 +2096,8 @@ struct napi_gro_cb { 
	/* This is non-zero if the packet may be of the same flow. */

	u8	same_flow:1;



	/* Used in udp_gro_receive */

	u8	udp_mark:1;

	/* Used in tunnel GRO receive */

	u8	encap_mark:1;



	/* GRO checksum is valid */

	u8	csum_valid:1;

net/core/dev.c

+1 −1
Original line number Diff line number Diff line
@@ -4438,7 +4438,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff 
		NAPI_GRO_CB(skb)->same_flow = 0;

		NAPI_GRO_CB(skb)->flush = 0;

		NAPI_GRO_CB(skb)->free = 0;

		NAPI_GRO_CB(skb)->udp_mark = 0;

		NAPI_GRO_CB(skb)->encap_mark = 0;

		NAPI_GRO_CB(skb)->gro_remcsum_start = 0;



		/* Setup for GRO checksum validation */

net/ipv4/af_inet.c

+14 −1
Original line number Diff line number Diff line
@@ -1380,6 +1380,19 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head, 
	return pp;

}



static struct sk_buff **ipip_gro_receive(struct sk_buff **head,

					 struct sk_buff *skb)

{

	if (NAPI_GRO_CB(skb)->encap_mark) {

		NAPI_GRO_CB(skb)->flush = 1;

		return NULL;

	}



	NAPI_GRO_CB(skb)->encap_mark = 1;



	return inet_gro_receive(head, skb);

}



#define SECONDS_PER_DAY	86400



/* inet_current_timestamp - Return IP network timestamp
@@ -1682,7 +1695,7 @@ static struct packet_offload ip_packet_offload __read_mostly = { 
static const struct net_offload ipip_offload = {

	.callbacks = {

		.gso_segment	= inet_gso_segment,

		.gro_receive	= inet_gro_receive,

		.gro_receive	= ipip_gro_receive,

		.gro_complete	= ipip_gro_complete,

	},

};

net/ipv4/gre_offload.c

+5 −0
Original line number Diff line number Diff line
@@ -126,6 +126,11 @@ static struct sk_buff **gre_gro_receive(struct sk_buff **head, 
	struct packet_offload *ptype;

	__be16 type;



	if (NAPI_GRO_CB(skb)->encap_mark)

		goto out;



	NAPI_GRO_CB(skb)->encap_mark = 1;



	off = skb_gro_offset(skb);

	hlen = off + sizeof(*greh);

	greh = skb_gro_header_fast(skb, off);

net/ipv4/udp_offload.c

+3 −3
Original line number Diff line number Diff line
@@ -311,14 +311,14 @@ struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb, 
	unsigned int off = skb_gro_offset(skb);

	int flush = 1;



	if (NAPI_GRO_CB(skb)->udp_mark ||

	if (NAPI_GRO_CB(skb)->encap_mark ||

	    (skb->ip_summed != CHECKSUM_PARTIAL &&

	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&

	     !NAPI_GRO_CB(skb)->csum_valid))

		goto out;



	/* mark that this skb passed once through the udp gro layer */

	NAPI_GRO_CB(skb)->udp_mark = 1;

	/* mark that this skb passed once through the tunnel gro layer */

	NAPI_GRO_CB(skb)->encap_mark = 1;



	rcu_read_lock();

	uo_priv = rcu_dereference(udp_offload_base);