Re: [ovs-dev] [PATCH v3] userspace: Allow UDP zero checksum with IPv6 tunnels.
On 2/21/24 19:06, Mike Pattrick wrote:
> This patch adopts the proposed RFC 6935 by allowing null UDP checksums
> even if the tunnel protocol is IPv6. This is already supported by Linux
> through the udp6zerocsumtx tunnel option. It is disabled by default and
> IPv6 tunnels are flagged as requiring a checksum, but this patch enables
> the user to set csum=false on IPv6 tunnels.
Hi, Mike. That's an interesting feature. Thanks!
Though the patch subject states 'userspace: ' the code seem to affect
tunnels in general, since it modifies tunnel flags for all tunnels.
More on that below.
>
> Signed-off-by: Mike Pattrick
> ---
> v2: Changed documentation, and added a NEWS item
> v3: NEWS file merge conflict
> ---
> NEWS| 3 +++
> lib/netdev-native-tnl.c | 2 +-
> lib/netdev-vport.c | 13 +++--
> lib/netdev.h| 9 -
> ofproto/tunnel.c| 11 +--
> tests/tunnel.at | 6 +++---
> vswitchd/vswitch.xml| 11 ---
> 7 files changed, 43 insertions(+), 12 deletions(-)
>
> diff --git a/NEWS b/NEWS
> index c9e4064e6..3a75d3850 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -4,6 +4,9 @@ Post-v3.3.0
> * Conntrack now supports 'random' flag for selecting ports in a range
> while natting and 'persistent' flag for selection of the IP address
> from a range.
> + * IPv6 UDP tunnels will now honour the csum option. Configuring the
All IPv6 UDP tunnels?
Also, double spaces between sentences.
> + interface with "options:csum=false" now has the same effect in OVS
s/in OVS//
> + as the udp6zerocsumtx option has with kernel UDP tunnels.
s/kernel/Linux kenrel/
>
>
> v3.3.0 - 16 Feb 2024
> diff --git a/lib/netdev-native-tnl.c b/lib/netdev-native-tnl.c
> index dee9ab344..e8258bc4e 100644
> --- a/lib/netdev-native-tnl.c
> +++ b/lib/netdev-native-tnl.c
> @@ -424,7 +424,7 @@ udp_build_header(const struct netdev_tunnel_config
> *tnl_cfg,
> udp = netdev_tnl_ip_build_header(data, params, IPPROTO_UDP, 0);
> udp->udp_dst = tnl_cfg->dst_port;
>
> -if (params->is_ipv6 || params->flow->tunnel.flags & FLOW_TNL_F_CSUM) {
> +if (params->flow->tunnel.flags & FLOW_TNL_F_CSUM) {
Please add a tunnel-push-pop test that verifies that cehcksums
are skipped.
> /* Write a value in now to mark that we should compute the checksum
> * later. 0x is handy because it is transparent to the
> * calculation. */
> diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
> index 60caa02fb..f9a778988 100644
> --- a/lib/netdev-vport.c
> +++ b/lib/netdev-vport.c
> @@ -702,7 +702,9 @@ set_tunnel_config(struct netdev *dev_, const struct smap
> *args, char **errp)
> tnl_cfg.dst_port = htons(atoi(node->value));
> } else if (!strcmp(node->key, "csum") && has_csum) {
> if (!strcmp(node->value, "true")) {
> -tnl_cfg.csum = true;
> +tnl_cfg.csum = NETDEV_TNL_CSUM_ENABLED;
> +} else if (!strcmp(node->value, "false")) {
> +tnl_cfg.csum = NETDEV_TNL_CSUM_DISABLED;
> }
> } else if (!strcmp(node->key, "seq") && has_seq) {
> if (!strcmp(node->value, "true")) {
> @@ -850,6 +852,11 @@ set_tunnel_config(struct netdev *dev_, const struct smap
> *args, char **errp)
> }
> }
>
> +/* The default csum state for GRE is special. */
Please explain what does it mean in the comment. And in the enum comment.
> +if (tnl_cfg.csum == NETDEV_TNL_CSUM_DEFAULT && strstr(type, "gre")) {
The tnl_cfg is initialized with memset, but the enum is not guaranteed
to start with a zero value.
> +tnl_cfg.csum = NETDEV_TNL_CSUM_DEFAULT_GRE;
> +}
> +
> enum tunnel_layers layers = tunnel_supported_layers(type, _cfg);
> const char *full_type = (strcmp(type, "vxlan") ? type
> : (tnl_cfg.exts & (1 << OVS_VXLAN_EXT_GPE)
> @@ -1026,8 +1033,10 @@ get_tunnel_config(const struct netdev *dev, struct
> smap *args)
> }
> }
>
> -if (tnl_cfg->csum) {
> +if (tnl_cfg->csum == NETDEV_TNL_CSUM_ENABLED) {
> smap_add(args, "csum", "true");
> +} else if (tnl_cfg->csum == NETDEV_TNL_CSUM_DISABLED) {
> +smap_add(args, "csum", "false");
> }
>
> if (tnl_cfg->set_seq) {
> diff --git a/lib/netdev.h b/lib/netdev.h
> index 67a8486bd..a79531e6d 100644
> --- a/lib/netdev.h
> +++ b/lib/netdev.h
> @@ -111,6 +111,13 @@ enum netdev_srv6_flowlabel {
> SRV6_FLOWLABEL_COMPUTE,
> };
>
> +enum netdev_tnl_csum {
> +NETDEV_TNL_CSUM_DEFAULT,
> +NETDEV_TNL_CSUM_ENABLED,
> +NETDEV_TNL_CSUM_DISABLED,
> +NETDEV_TNL_CSUM_DEFAULT_GRE,
> +};
Some comments for the values would be nice to have.
> +
> /* Configuration specific to tunnels. */
> struct netdev_tunnel_config {
> ovs_be64 in_key;
> @@ -139,7 +146,7 @@ struct netdev_tunnel_config {
> uint8_t tos;
> bool tos_inherit;
>
[ovs-dev] [PATCH v3] userspace: Allow UDP zero checksum with IPv6 tunnels.
This patch adopts the proposed RFC 6935 by allowing null UDP checksums
even if the tunnel protocol is IPv6. This is already supported by Linux
through the udp6zerocsumtx tunnel option. It is disabled by default and
IPv6 tunnels are flagged as requiring a checksum, but this patch enables
the user to set csum=false on IPv6 tunnels.
Signed-off-by: Mike Pattrick
---
v2: Changed documentation, and added a NEWS item
v3: NEWS file merge conflict
---
NEWS| 3 +++
lib/netdev-native-tnl.c | 2 +-
lib/netdev-vport.c | 13 +++--
lib/netdev.h| 9 -
ofproto/tunnel.c| 11 +--
tests/tunnel.at | 6 +++---
vswitchd/vswitch.xml| 11 ---
7 files changed, 43 insertions(+), 12 deletions(-)
diff --git a/NEWS b/NEWS
index c9e4064e6..3a75d3850 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,9 @@ Post-v3.3.0
* Conntrack now supports 'random' flag for selecting ports in a range
while natting and 'persistent' flag for selection of the IP address
from a range.
+ * IPv6 UDP tunnels will now honour the csum option. Configuring the
+ interface with "options:csum=false" now has the same effect in OVS
+ as the udp6zerocsumtx option has with kernel UDP tunnels.
v3.3.0 - 16 Feb 2024
diff --git a/lib/netdev-native-tnl.c b/lib/netdev-native-tnl.c
index dee9ab344..e8258bc4e 100644
--- a/lib/netdev-native-tnl.c
+++ b/lib/netdev-native-tnl.c
@@ -424,7 +424,7 @@ udp_build_header(const struct netdev_tunnel_config *tnl_cfg,
udp = netdev_tnl_ip_build_header(data, params, IPPROTO_UDP, 0);
udp->udp_dst = tnl_cfg->dst_port;
-if (params->is_ipv6 || params->flow->tunnel.flags & FLOW_TNL_F_CSUM) {
+if (params->flow->tunnel.flags & FLOW_TNL_F_CSUM) {
/* Write a value in now to mark that we should compute the checksum
* later. 0x is handy because it is transparent to the
* calculation. */
diff --git a/lib/netdev-vport.c b/lib/netdev-vport.c
index 60caa02fb..f9a778988 100644
--- a/lib/netdev-vport.c
+++ b/lib/netdev-vport.c
@@ -702,7 +702,9 @@ set_tunnel_config(struct netdev *dev_, const struct smap
*args, char **errp)
tnl_cfg.dst_port = htons(atoi(node->value));
} else if (!strcmp(node->key, "csum") && has_csum) {
if (!strcmp(node->value, "true")) {
-tnl_cfg.csum = true;
+tnl_cfg.csum = NETDEV_TNL_CSUM_ENABLED;
+} else if (!strcmp(node->value, "false")) {
+tnl_cfg.csum = NETDEV_TNL_CSUM_DISABLED;
}
} else if (!strcmp(node->key, "seq") && has_seq) {
if (!strcmp(node->value, "true")) {
@@ -850,6 +852,11 @@ set_tunnel_config(struct netdev *dev_, const struct smap
*args, char **errp)
}
}
+/* The default csum state for GRE is special. */
+if (tnl_cfg.csum == NETDEV_TNL_CSUM_DEFAULT && strstr(type, "gre")) {
+tnl_cfg.csum = NETDEV_TNL_CSUM_DEFAULT_GRE;
+}
+
enum tunnel_layers layers = tunnel_supported_layers(type, _cfg);
const char *full_type = (strcmp(type, "vxlan") ? type
: (tnl_cfg.exts & (1 << OVS_VXLAN_EXT_GPE)
@@ -1026,8 +1033,10 @@ get_tunnel_config(const struct netdev *dev, struct smap
*args)
}
}
-if (tnl_cfg->csum) {
+if (tnl_cfg->csum == NETDEV_TNL_CSUM_ENABLED) {
smap_add(args, "csum", "true");
+} else if (tnl_cfg->csum == NETDEV_TNL_CSUM_DISABLED) {
+smap_add(args, "csum", "false");
}
if (tnl_cfg->set_seq) {
diff --git a/lib/netdev.h b/lib/netdev.h
index 67a8486bd..a79531e6d 100644
--- a/lib/netdev.h
+++ b/lib/netdev.h
@@ -111,6 +111,13 @@ enum netdev_srv6_flowlabel {
SRV6_FLOWLABEL_COMPUTE,
};
+enum netdev_tnl_csum {
+NETDEV_TNL_CSUM_DEFAULT,
+NETDEV_TNL_CSUM_ENABLED,
+NETDEV_TNL_CSUM_DISABLED,
+NETDEV_TNL_CSUM_DEFAULT_GRE,
+};
+
/* Configuration specific to tunnels. */
struct netdev_tunnel_config {
ovs_be64 in_key;
@@ -139,7 +146,7 @@ struct netdev_tunnel_config {
uint8_t tos;
bool tos_inherit;
-bool csum;
+enum netdev_tnl_csum csum;
bool dont_fragment;
enum netdev_pt_mode pt_mode;
diff --git a/ofproto/tunnel.c b/ofproto/tunnel.c
index 80ddee78a..6f462874e 100644
--- a/ofproto/tunnel.c
+++ b/ofproto/tunnel.c
@@ -465,9 +465,14 @@ tnl_port_send(const struct ofport_dpif *ofport, struct
flow *flow,
flow->tunnel.flags &= ~(FLOW_TNL_F_MASK & ~FLOW_TNL_PUB_F_MASK);
flow->tunnel.flags |= (cfg->dont_fragment ? FLOW_TNL_F_DONT_FRAGMENT : 0)
-| (cfg->csum ? FLOW_TNL_F_CSUM : 0)
| (cfg->out_key_present ? FLOW_TNL_F_KEY : 0);
+if (cfg->csum == NETDEV_TNL_CSUM_ENABLED) {
+flow->tunnel.flags |= FLOW_TNL_F_CSUM;
+} else if (cfg->csum == NETDEV_TNL_CSUM_DEFAULT && !flow->tunnel.ip_dst) {
+flow->tunnel.flags |= FLOW_TNL_F_CSUM;
+}
+
if (cfg->set_egress_pkt_mark) {
flow->pkt_mark =
