The current code allows to inherit the TOS, TTL, DF from the payload
when skb->protocol is ETH_P_IP or ETH_P_IPV6.
However when the payload is VLAN encapsulated (e.g because the tunnel
is of type GRETAP), then this inheriting does not work, because the
visible skb->protocol is of type ETH_P_8021Q.
Add a check on ETH_P_8021Q and subsequently check the payload protocol.
Signed-off-by: Matthias May <[email protected]>
---
v1 -> v2:
- Add support for ETH_P_8021AD as suggested by Jakub Kicinski.
---
net/ipv4/ip_tunnel.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 94017a8c3994..bdcc0f1e83c8 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -648,6 +648,13 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
u8 tos, ttl;
__be32 dst;
__be16 df;
+ __be16 *payload_protocol;
+
+ if (skb->protocol == htons(ETH_P_8021Q) ||
+ skb->protocol == htons(ETH_P_8021AD))
+ payload_protocol = (__be16 *)(skb->head + skb->network_header - 2);
+ else
+ payload_protocol = &skb->protocol;
inner_iph = (const struct iphdr *)skb_inner_network_header(skb);
connected = (tunnel->parms.iph.daddr != 0);
@@ -670,13 +677,12 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
dst = tun_info->key.u.ipv4.dst;
md = true;
connected = true;
- }
- else if (skb->protocol == htons(ETH_P_IP)) {
+ } else if (*payload_protocol == htons(ETH_P_IP)) {
rt = skb_rtable(skb);
dst = rt_nexthop(rt, inner_iph->daddr);
}
#if IS_ENABLED(CONFIG_IPV6)
- else if (skb->protocol == htons(ETH_P_IPV6)) {
+ else if (*payload_protocol == htons(ETH_P_IPV6)) {
const struct in6_addr *addr6;
struct neighbour *neigh;
bool do_tx_error_icmp;
@@ -716,10 +722,10 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
tos = tnl_params->tos;
if (tos & 0x1) {
tos &= ~0x1;
- if (skb->protocol == htons(ETH_P_IP)) {
+ if (*payload_protocol == htons(ETH_P_IP)) {
tos = inner_iph->tos;
connected = false;
- } else if (skb->protocol == htons(ETH_P_IPV6)) {
+ } else if (*payload_protocol == htons(ETH_P_IPV6)) {
tos = ipv6_get_dsfield((const struct ipv6hdr *)inner_iph);
connected = false;
}
@@ -765,7 +771,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
}
df = tnl_params->frag_off;
- if (skb->protocol == htons(ETH_P_IP) && !tunnel->ignore_df)
+ if (*payload_protocol == htons(ETH_P_IP) && !tunnel->ignore_df)
df |= (inner_iph->frag_off & htons(IP_DF));
if (tnl_update_pmtu(dev, skb, rt, df, inner_iph, 0, 0, false)) {
@@ -786,10 +792,10 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
tos = ip_tunnel_ecn_encap(tos, inner_iph, skb);
ttl = tnl_params->ttl;
if (ttl == 0) {
- if (skb->protocol == htons(ETH_P_IP))
+ if (*payload_protocol == htons(ETH_P_IP))
ttl = inner_iph->ttl;
#if IS_ENABLED(CONFIG_IPV6)
- else if (skb->protocol == htons(ETH_P_IPV6))
+ else if (*payload_protocol == htons(ETH_P_IPV6))
ttl = ((const struct ipv6hdr *)inner_iph)->hop_limit;
#endif
else
--
2.35.1
Hi,
On Wed, Jul 6, 2022 at 7:54 PM Matthias May <[email protected]> wrote:
>
> The current code allows to inherit the TOS, TTL, DF from the payload
> when skb->protocol is ETH_P_IP or ETH_P_IPV6.
> However when the payload is VLAN encapsulated (e.g because the tunnel
> is of type GRETAP), then this inheriting does not work, because the
> visible skb->protocol is of type ETH_P_8021Q.
>
> Add a check on ETH_P_8021Q and subsequently check the payload protocol.
>
> Signed-off-by: Matthias May <[email protected]>
> ---
> v1 -> v2:
> - Add support for ETH_P_8021AD as suggested by Jakub Kicinski.
> ---
> net/ipv4/ip_tunnel.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> index 94017a8c3994..bdcc0f1e83c8 100644
> --- a/net/ipv4/ip_tunnel.c
> +++ b/net/ipv4/ip_tunnel.c
> @@ -648,6 +648,13 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
> u8 tos, ttl;
> __be32 dst;
> __be16 df;
> + __be16 *payload_protocol;
> +
> + if (skb->protocol == htons(ETH_P_8021Q) ||
> + skb->protocol == htons(ETH_P_8021AD))
> + payload_protocol = (__be16 *)(skb->head + skb->network_header - 2);
> + else
> + payload_protocol = &skb->protocol;
Maybe it's better to use skb_protocol(skb, true) here instead of open
coding the vlan parsing?
Eyal
On 7/6/22 19:24, Eyal Birger wrote:
>
> Hi,
>
> On Wed, Jul 6, 2022 at 7:54 PM Matthias May <[email protected] <mailto:[email protected]>> wrote:
>
> The current code allows to inherit the TOS, TTL, DF from the payload
> when skb->protocol is ETH_P_IP or ETH_P_IPV6.
> However when the payload is VLAN encapsulated (e.g because the tunnel
> is of type GRETAP), then this inheriting does not work, because the
> visible skb->protocol is of type ETH_P_8021Q.
>
> Add a check on ETH_P_8021Q and subsequently check the payload protocol.
>
> Signed-off-by: Matthias May <[email protected] <mailto:[email protected]>>
> ---
> v1 -> v2:
> - Add support for ETH_P_8021AD as suggested by Jakub Kicinski.
> ---
> net/ipv4/ip_tunnel.c | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> index 94017a8c3994..bdcc0f1e83c8 100644
> --- a/net/ipv4/ip_tunnel.c
> +++ b/net/ipv4/ip_tunnel.c
> @@ -648,6 +648,13 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
> u8 tos, ttl;
> __be32 dst;
> __be16 df;
> + __be16 *payload_protocol;
> +
> + if (skb->protocol == htons(ETH_P_8021Q) ||
> + skb->protocol == htons(ETH_P_8021AD))
> + payload_protocol = (__be16 *)(skb->head + skb->network_header - 2);
> + else
> + payload_protocol = &skb->protocol;
>
>
> Maybe it's better to use skb_protocol(skb, true) here instead of open
> coding the vlan parsing?
>
> Eyal
Hi Eyal
I've looked into using skb_protocol(skb, true).
If skip_vlan is set to true, wouldn't it make sense to use vlan_get_protocol(skb) directly?
BR
Matthias
On Thu, Jul 7, 2022 at 10:44 AM Matthias May <[email protected]> wrote:
>
> On 7/6/22 19:24, Eyal Birger wrote:
> >
> > Hi,
> >
> > On Wed, Jul 6, 2022 at 7:54 PM Matthias May <[email protected] <mailto:[email protected]>> wrote:
> >
> > The current code allows to inherit the TOS, TTL, DF from the payload
> > when skb->protocol is ETH_P_IP or ETH_P_IPV6.
> > However when the payload is VLAN encapsulated (e.g because the tunnel
> > is of type GRETAP), then this inheriting does not work, because the
> > visible skb->protocol is of type ETH_P_8021Q.
> >
> > Add a check on ETH_P_8021Q and subsequently check the payload protocol.
> >
> > Signed-off-by: Matthias May <[email protected] <mailto:[email protected]>>
> > ---
> > v1 -> v2:
> > - Add support for ETH_P_8021AD as suggested by Jakub Kicinski.
> > ---
> > net/ipv4/ip_tunnel.c | 22 ++++++++++++++--------
> > 1 file changed, 14 insertions(+), 8 deletions(-)
> >
> > diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
> > index 94017a8c3994..bdcc0f1e83c8 100644
> > --- a/net/ipv4/ip_tunnel.c
> > +++ b/net/ipv4/ip_tunnel.c
> > @@ -648,6 +648,13 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
> > u8 tos, ttl;
> > __be32 dst;
> > __be16 df;
> > + __be16 *payload_protocol;
> > +
> > + if (skb->protocol == htons(ETH_P_8021Q) ||
> > + skb->protocol == htons(ETH_P_8021AD))
> > + payload_protocol = (__be16 *)(skb->head + skb->network_header - 2);
> > + else
> > + payload_protocol = &skb->protocol;
> >
> >
> > Maybe it's better to use skb_protocol(skb, true) here instead of open
> > coding the vlan parsing?
> >
> > Eyal
>
> Hi Eyal
> I've looked into using skb_protocol(skb, true).
> If skip_vlan is set to true, wouldn't it make sense to use vlan_get_protocol(skb) directly?
Since it's inlined i don't think it makes a practical difference.
Personally I'd find it more readable to use skb_protocol() here because
VLANs are the less expected path, and the change is basically to ignore
them.
Eyal.