[PATCH net-next] erspan: auto detect truncated ipv6 packets.

[William Tu]

Currently the truncated bit is set only when 1) the mirrored packet
is larger than mtu and 2) the ipv4 packet tot_len is larger than
the actual skb->len.  This patch adds another case for detecting
whether ipv6 packet is truncated or not, by checking the ipv6 header
payload_len and the skb->len.

Reported-by: Xiaoyan Jin <xiaoy...@vmware.com>
Signed-off-by: William Tu <u9012...@gmail.com>
---
 net/ipv4/ip_gre.c  | 6 ++++++
 net/ipv6/ip6_gre.c | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index dfe5b22f6ed4..2409e648454d 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -579,6 +579,7 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct 
net_device *dev,
        int version;
        __be16 df;
        int nhoff;
+       int thoff;
 
        tun_info = skb_tunnel_info(skb);
        if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
@@ -611,6 +612,11 @@ static void erspan_fb_xmit(struct sk_buff *skb, struct 
net_device *dev,
            (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
                truncate = true;
 
+       thoff = skb_transport_header(skb) - skb_mac_header(skb);
+       if (skb->protocol == htons(ETH_P_IPV6) &&
+           (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff))
+               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 b511818b268c..bede77f24784 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -897,6 +897,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff 
*skb,
        int err = -EINVAL;
        __u32 mtu;
        int nhoff;
+       int thoff;
 
        if (!ip6_tnl_xmit_ctl(t, &t->parms.laddr, &t->parms.raddr))
                goto tx_err;
@@ -914,6 +915,11 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff 
*skb,
            (ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
                truncate = true;
 
+       thoff = skb_transport_header(skb) - skb_mac_header(skb);
+       if (skb->protocol == htons(ETH_P_IPV6) &&
+           (ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff))
+               truncate = true;
+
        if (skb_cow_head(skb, dev->needed_headroom))
                goto tx_err;
 
-- 
2.7.4