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From: Adrian Moreno <amorenoz@redhat.com>
To: netdev@vger.kernel.org
Cc: aconole@redhat.com,
	echaudro@redhat.com,
	horms@kernel.org,
	i.maximets@ovn.org,
	dev@openvswitch.org,
	Adrian Moreno <amorenoz@redhat.com>,
	Donald Hunter <donald.hunter@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Pravin B Shelar <pshelar@ovn.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH net-next v2 5/9] net: openvswitch: add emit_sample action
Date: Mon,  3 Jun 2024 20:56:39 +0200
Message-ID: <20240603185647.2310748-6-amorenoz@redhat.com>
In-Reply-To: <20240603185647.2310748-1-amorenoz@redhat.com>
References: <20240603185647.2310748-1-amorenoz@redhat.com>
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Add support for a new action: emit_sample.

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.

Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
---
 Documentation/netlink/specs/ovs_flow.yaml | 17 ++++++++
 include/uapi/linux/openvswitch.h          | 25 ++++++++++++
 net/openvswitch/actions.c                 | 50 +++++++++++++++++++++++
 net/openvswitch/flow_netlink.c            | 33 ++++++++++++++-
 4 files changed, 124 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/ovs_flow.yaml b/Documentation/netlink/specs/ovs_flow.yaml
index 4fdfc6b5cae9..a7ab5593a24f 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: emit-sample
+        type: nest
+        nested-attributes: emit-sample-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: emit-sample-attrs
+    enum-name: ovs-emit-sample-attr
+    name-prefix: ovs-emit-sample-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..a0e9dde0584a 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -914,6 +914,30 @@ struct check_pkt_len_arg {
 };
 #endif
 
+#define OVS_EMIT_SAMPLE_COOKIE_MAX_SIZE 16
+/**
+ * enum ovs_emit_sample_attr - Attributes for %OVS_ACTION_ATTR_EMIT_SAMPLE
+ * action.
+ *
+ * @OVS_EMIT_SAMPLE_ATTR_GROUP: 32-bit number to identify the source of the
+ * sample.
+ * @OVS_EMIT_SAMPLE_ATTR_COOKIE: A variable-length binary cookie that contains
+ * user-defined metadata. The maximum length is 16 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 packet being emitted.
+ */
+enum ovs_emit_sample_attr {
+	OVS_EMIT_SAMPLE_ATTR_UNPSEC,
+	OVS_EMIT_SAMPLE_ATTR_GROUP,	/* u32 number. */
+	OVS_EMIT_SAMPLE_ATTR_COOKIE,	/* Optional, user specified cookie. */
+	__OVS_EMIT_SAMPLE_ATTR_MAX
+};
+
+#define OVS_EMIT_SAMPLE_ATTR_MAX (__OVS_EMIT_SAMPLE_ATTR_MAX - 1)
+
+
 /**
  * enum ovs_action_attr - Action types.
  *
@@ -1004,6 +1028,7 @@ 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_EMIT_SAMPLE,  /* Nested OVS_EMIT_SAMPLE_ATTR_*. */
 
 	__OVS_ACTION_ATTR_MAX,	      /* Nothing past this will be accepted
 				       * from userspace. */
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 964225580824..3b4dba0ded59 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 +1304,46 @@ static int execute_dec_ttl(struct sk_buff *skb, struct sw_flow_key *key)
 	return 0;
 }
 
+static int execute_emit_sample(struct datapath *dp, struct sk_buff *skb,
+			       const struct sw_flow_key *key,
+			       const struct nlattr *attr)
+{
+#if IS_ENABLED(CONFIG_PSAMPLE)
+	struct psample_group psample_group = {};
+	struct psample_metadata md = {};
+	struct vport *input_vport;
+	const struct nlattr *a;
+	int rem;
+
+	for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
+	     a = nla_next(a, &rem)) {
+		switch (nla_type(a)) {
+		case OVS_EMIT_SAMPLE_ATTR_GROUP:
+			psample_group.group_num = nla_get_u32(a);
+			break;
+
+		case OVS_EMIT_SAMPLE_ATTR_COOKIE:
+			md.user_cookie = nla_data(a);
+			md.user_cookie_len = nla_len(a);
+			break;
+		}
+	}
+
+	psample_group.net = ovs_dp_get_net(dp);
+
+	input_vport = ovs_vport_rcu(dp, key->phy.in_port);
+	if (!input_vport)
+		input_vport = ovs_vport_rcu(dp, OVSP_LOCAL);
+
+	md.in_ifindex = input_vport->dev->ifindex;
+	md.trunc_size = skb->len - OVS_CB(skb)->cutlen;
+
+	psample_sample_packet(&psample_group, skb, 0, &md);
+#endif
+
+	return 0;
+}
+
 /* 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 +1547,11 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
 			ovs_kfree_skb_reason(skb, reason);
 			return 0;
 		}
+
+		case OVS_ACTION_ATTR_EMIT_SAMPLE:
+			err = execute_emit_sample(dp, skb, key, a);
+			OVS_CB(skb)->cutlen = 0;
+			break;
 		}
 
 		if (unlikely(err)) {
diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index f224d9bcea5e..eb59ff9c8154 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_EMIT_SAMPLE:
 			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 +3158,29 @@ static int validate_and_copy_check_pkt_len(struct net *net,
 	return 0;
 }
 
+static int validate_emit_sample(const struct nlattr *attr)
+{
+	static const struct nla_policy policy[OVS_EMIT_SAMPLE_ATTR_MAX + 1] = {
+		[OVS_EMIT_SAMPLE_ATTR_GROUP] = { .type = NLA_U32 },
+		[OVS_EMIT_SAMPLE_ATTR_COOKIE] = {
+			.type = NLA_BINARY,
+			.len = OVS_EMIT_SAMPLE_COOKIE_MAX_SIZE
+		},
+	};
+	struct nlattr *a[OVS_EMIT_SAMPLE_ATTR_MAX  + 1];
+	int err;
+
+	if (!IS_ENABLED(CONFIG_PSAMPLE))
+		return -EOPNOTSUPP;
+
+	err = nla_parse_nested(a, OVS_EMIT_SAMPLE_ATTR_MAX, attr, policy,
+			       NULL);
+	if (err)
+		return err;
+
+	return a[OVS_EMIT_SAMPLE_ATTR_GROUP] ? 0 : -EINVAL;
+}
+
 static int copy_action(const struct nlattr *from,
 		       struct sw_flow_actions **sfa, bool log)
 {
@@ -3212,6 +3236,7 @@ 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_EMIT_SAMPLE] = (u32)-1,
 		};
 		const struct ovs_action_push_vlan *vlan;
 		int type = nla_type(a);
@@ -3490,6 +3515,12 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
 				return -EINVAL;
 			break;
 
+		case OVS_ACTION_ATTR_EMIT_SAMPLE:
+			err = validate_emit_sample(a);
+			if (err)
+				return err;
+			break;
+
 		default:
 			OVS_NLERR(log, "Unknown Action type %d", type);
 			return -EINVAL;
-- 
2.45.1