[PATCH net-next v8 05/10] net: openvswitch: add psample action

Adrian Moreno
2024-07-02T09:54:19Z

Add support for a new action: psample.

This action accepts a u32 group id and a variable-length cookie and uses
the psample multicast group to make the packet available for
observability.

The maximum length of the user-defined cookie is set to 16, same as
tc_cookie, to discourage using cookies that will not be offloadable.

Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
---
Documentation/netlink/specs/ovs_flow.yaml | 17 ++++++++
include/uapi/linux/openvswitch.h | 28 +++++++++++++
net/openvswitch/Kconfig | 1 +
net/openvswitch/actions.c | 48 +++++++++++++++++++++++
net/openvswitch/flow_netlink.c | 32 ++++++++++++++-
5 files changed, 125 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/ovs_flow.yaml b/Documentation/netlink/specs/ovs_flow.yaml
index 4fdfc6b5cae9..46f5d1cd8a5f 100644
--- a/Documentation/netlink/specs/ovs_flow.yaml
+++ b/Documentation/netlink/specs/ovs_flow.yaml
@@ -727,6 +727,12 @@ attribute-sets:
name: dec-ttl
type: nest
nested-attributes: dec-ttl-attrs
+ -
+ name: psample
+ type: nest
+ nested-attributes: psample-attrs
+ doc: |
+ Sends a packet sample to psample for external observation.
-
name: tunnel-key-attrs
enum-name: ovs-tunnel-key-attr
@@ -938,6 +944,17 @@ attribute-sets:
-
name: gbp
type: u32
+ -
+ name: psample-attrs
+ enum-name: ovs-psample-attr
+ name-prefix: ovs-psample-attr-
+ attributes:
+ -
+ name: group
+ type: u32
+ -
+ name: cookie
+ type: binary

operations:
name-prefix: ovs-flow-cmd-
diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index efc82c318fa2..3dd653748725 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -914,6 +914,31 @@ struct check_pkt_len_arg {
};
#endif

+#define OVS_PSAMPLE_COOKIE_MAX_SIZE 16
+/**
+ * enum ovs_psample_attr - Attributes for %OVS_ACTION_ATTR_PSAMPLE
+ * action.
+ *
+ * @OVS_PSAMPLE_ATTR_GROUP: 32-bit number to identify the source of the
+ * sample.
+ * @OVS_PSAMPLE_ATTR_COOKIE: An optional variable-length binary cookie that
+ * contains user-defined metadata. The maximum length is
+ * OVS_PSAMPLE_COOKIE_MAX_SIZE bytes.
+ *
+ * Sends the packet to the psample multicast group with the specified group and
+ * cookie. It is possible to combine this action with the
+ * %OVS_ACTION_ATTR_TRUNC action to limit the size of the sample.
+ */
+enum ovs_psample_attr {
+ OVS_PSAMPLE_ATTR_GROUP = 1, /* u32 number. */
+ OVS_PSAMPLE_ATTR_COOKIE, /* Optional, user specified cookie. */
+
+ /* private: */
+ __OVS_PSAMPLE_ATTR_MAX
+};
+
+#define OVS_PSAMPLE_ATTR_MAX (__OVS_PSAMPLE_ATTR_MAX - 1)
+
/**
* enum ovs_action_attr - Action types.
*
@@ -966,6 +991,8 @@ struct check_pkt_len_arg {
* of l3 tunnel flag in the tun_flags field of OVS_ACTION_ATTR_ADD_MPLS
* argument.
* @OVS_ACTION_ATTR_DROP: Explicit drop action.
+ * @OVS_ACTION_ATTR_PSAMPLE: Send a sample of the packet to external observers
+ * via psample.
*
* Only a single header can be set with a single %OVS_ACTION_ATTR_SET. Not all
* fields within a header are modifiable, e.g. the IPv4 protocol and fragment
@@ -1004,6 +1031,7 @@ enum ovs_action_attr {
OVS_ACTION_ATTR_ADD_MPLS, /* struct ovs_action_add_mpls. */
OVS_ACTION_ATTR_DEC_TTL, /* Nested OVS_DEC_TTL_ATTR_*. */
OVS_ACTION_ATTR_DROP, /* u32 error code. */
+ OVS_ACTION_ATTR_PSAMPLE, /* Nested OVS_PSAMPLE_ATTR_*. */

__OVS_ACTION_ATTR_MAX, /* Nothing past this will be accepted
* from userspace. */
diff --git a/net/openvswitch/Kconfig b/net/openvswitch/Kconfig
index 29a7081858cd..2535f3f9f462 100644
--- a/net/openvswitch/Kconfig
+++ b/net/openvswitch/Kconfig
@@ -10,6 +10,7 @@ config OPENVSWITCH
(NF_CONNTRACK && ((!NF_DEFRAG_IPV6 || NF_DEFRAG_IPV6) && \
(!NF_NAT || NF_NAT) && \
(!NETFILTER_CONNCOUNT || NETFILTER_CONNCOUNT)))
+ depends on PSAMPLE || !PSAMPLE
select LIBCRC32C
select MPLS
select NET_MPLS_GSO
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 964225580824..892d7e48fc5b 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -24,6 +24,11 @@
#include <net/checksum.h>
#include <net/dsfield.h>
#include <net/mpls.h>
+
+#if IS_ENABLED(CONFIG_PSAMPLE)
+#include <net/psample.h>
+#endif
+
#include <net/sctp/checksum.h>

#include "datapath.h"
@@ -1299,6 +1304,40 @@ static int execute_dec_ttl(struct sk_buff *skb, struct sw_flow_key *key)
return 0;
}

+#if IS_ENABLED(CONFIG_PSAMPLE)
+static void execute_psample(struct datapath *dp, struct sk_buff *skb,
+ const struct nlattr *attr)
+{
+ struct psample_group psample_group = {};
+ struct psample_metadata md = {};
+ const struct nlattr *a;
+ int rem;
+
+ nla_for_each_attr(a, nla_data(attr), nla_len(attr), rem) {
+ switch (nla_type(a)) {
+ case OVS_PSAMPLE_ATTR_GROUP:
+ psample_group.group_num = nla_get_u32(a);
+ break;
+
+ case OVS_PSAMPLE_ATTR_COOKIE:
+ md.user_cookie = nla_data(a);
+ md.user_cookie_len = nla_len(a);
+ break;
+ }
+ }
+
+ psample_group.net = ovs_dp_get_net(dp);
+ md.in_ifindex = OVS_CB(skb)->input_vport->dev->ifindex;
+ md.trunc_size = skb->len - OVS_CB(skb)->cutlen;
+
+ psample_sample_packet(&psample_group, skb, 0, &md);
+}
+#else
+static void execute_psample(struct datapath *dp, struct sk_buff *skb,
+ const struct nlattr *attr)
+{}
+#endif
+
/* Execute a list of actions against 'skb'. */
static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
struct sw_flow_key *key,
@@ -1502,6 +1541,15 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
ovs_kfree_skb_reason(skb, reason);
return 0;
}
+
+ case OVS_ACTION_ATTR_PSAMPLE:
+ execute_psample(dp, skb, a);
+ OVS_CB(skb)->cutlen = 0;
+ if (nla_is_last(a, rem)) {
+ consume_skb(skb);
+ return 0;
+ }
+ break;
}

if (unlikely(err)) {
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index f224d9bcea5e..c92bdc4dfe19 100644
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -64,6 +64,7 @@ static bool actions_may_change_flow(const struct nlattr *actions)
case OVS_ACTION_ATTR_TRUNC:
case OVS_ACTION_ATTR_USERSPACE:
case OVS_ACTION_ATTR_DROP:
+ case OVS_ACTION_ATTR_PSAMPLE:
break;

case OVS_ACTION_ATTR_CT:
@@ -2409,7 +2410,7 @@ static void ovs_nla_free_nested_actions(const struct nlattr *actions, int len)
/* Whenever new actions are added, the need to update this
* function should be considered.
*/
- BUILD_BUG_ON(OVS_ACTION_ATTR_MAX != 24);
+ BUILD_BUG_ON(OVS_ACTION_ATTR_MAX != 25);

if (!actions)
return;
@@ -3157,6 +3158,28 @@ static int validate_and_copy_check_pkt_len(struct net *net,
return 0;
}

+static int validate_psample(const struct nlattr *attr)
+{
+ static const struct nla_policy policy[OVS_PSAMPLE_ATTR_MAX + 1] = {
+ [OVS_PSAMPLE_ATTR_GROUP] = { .type = NLA_U32 },
+ [OVS_PSAMPLE_ATTR_COOKIE] = {
+ .type = NLA_BINARY,
+ .len = OVS_PSAMPLE_COOKIE_MAX_SIZE,
+ },
+ };
+ struct nlattr *a[OVS_PSAMPLE_ATTR_MAX + 1];
+ int err;
+
+ if (!IS_ENABLED(CONFIG_PSAMPLE))
+ return -EOPNOTSUPP;
+
+ err = nla_parse_nested(a, OVS_PSAMPLE_ATTR_MAX, attr, policy, NULL);
+ if (err)
+ return err;
+
+ return a[OVS_PSAMPLE_ATTR_GROUP] ? 0 : -EINVAL;
+}
+
static int copy_action(const struct nlattr *from,
struct sw_flow_actions **sfa, bool log)
{
@@ -3212,6 +3235,7 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
[OVS_ACTION_ATTR_ADD_MPLS] = sizeof(struct ovs_action_add_mpls),
[OVS_ACTION_ATTR_DEC_TTL] = (u32)-1,
[OVS_ACTION_ATTR_DROP] = sizeof(u32),
+ [OVS_ACTION_ATTR_PSAMPLE] = (u32)-1,
};
const struct ovs_action_push_vlan *vlan;
int type = nla_type(a);
@@ -3490,6 +3514,12 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
return -EINVAL;
break;

+ case OVS_ACTION_ATTR_PSAMPLE:
+ err = validate_psample(a);
+ if (err)
+ return err;
+ break;
+
default:
OVS_NLERR(log, "Unknown Action type %d", type);
return -EINVAL;
--
2.45.2