diff mbox series

[net-next] erspan: auto detect truncated packets.

Message ID 1524863792-66068-1-git-send-email-u9012063@gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show
Series [net-next] erspan: auto detect truncated packets. | expand

Commit Message

William Tu April 27, 2018, 9:16 p.m. UTC 
Currently the truncated bit is set only when the mirrored packet
is larger than mtu.  For certain cases, the packet might already
been truncated before sending to the erspan tunnel.  In this case,
the patch detect whether the IP header's total length is larger
than the actual skb->len.  If true, this indicated that the
mirrored packet is truncated and set the erspan truncate bit.

I tested the patch using bpf_skb_change_tail helper function to
shrink the packet size and send to erspan tunnel.

Reported-by: Xiaoyan Jin <xiaoyanj@vmware.com>
Signed-off-by: William Tu <u9012063@gmail.com>
---
 net/ipv4/ip_gre.c  | 6 ++++++
 net/ipv6/ip6_gre.c | 6 ++++++
 2 files changed, 12 insertions(+)

Comments

David Miller April 30, 2018, 3:44 p.m. UTC | #1 
From: William Tu <u9012063@gmail.com>
Date: Fri, 27 Apr 2018 14:16:32 -0700

> Currently the truncated bit is set only when the mirrored packet
> is larger than mtu.  For certain cases, the packet might already
> been truncated before sending to the erspan tunnel.  In this case,
> the patch detect whether the IP header's total length is larger
> than the actual skb->len.  If true, this indicated that the
> mirrored packet is truncated and set the erspan truncate bit.
> 
> I tested the patch using bpf_skb_change_tail helper function to
> shrink the packet size and send to erspan tunnel.
> 
> Reported-by: Xiaoyan Jin <xiaoyanj@vmware.com>
> Signed-off-by: William Tu <u9012063@gmail.com>

Applied, thanks.
diff mbox series

Patch

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 9c169bb2444d..dfe5b22f6ed4 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -578,6 +578,7 @@  static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev,
 	int tunnel_hlen;
 	int version;
 	__be16 df;
+	int nhoff;
 
 	tun_info = skb_tunnel_info(skb);
 	if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
@@ -605,6 +606,11 @@  static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev,
 		truncate = true;
 	}
 
+	nhoff = skb_network_header(skb) - skb_mac_header(skb);
+	if (skb->protocol == htons(ETH_P_IP) &&
+	    (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
+		truncate = true;
+
 	if (version == 1) {
 		erspan_build_header(skb, ntohl(tunnel_id_to_key32(key->tun_id)),
 				    ntohl(md->u.index), truncate, true);
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 69727bc168cb..ac7ce85df667 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -896,6 +896,7 @@  static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 	struct flowi6 fl6;
 	int err = -EINVAL;
 	__u32 mtu;
+	int nhoff;
 
 	if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
 		goto tx_err;
@@ -908,6 +909,11 @@  static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 		truncate = true;
 	}
 
+	nhoff = skb_network_header(skb) - skb_mac_header(skb);
+	if (skb->protocol == htons(ETH_P_IP) &&
+	    (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
+		truncate = true;
+
 	if (skb_cow_head(skb, dev->needed_headroom))
 		goto tx_err;