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Message-ID: <CAG=2xmPHcyLbuMCVR6ysKigboWg1E_xCHFMxEKUceerioO-OFg@mail.gmail.com>
Date: Tue, 18 Jun 2024 07:33:16 +0000
From: Adrián Moreno <amorenoz@...hat.com>
To: Ilya Maximets <i.maximets@....org>
Cc: netdev@...r.kernel.org, aconole@...hat.com, echaudro@...hat.com,
horms@...nel.org, dev@...nvswitch.org,
Donald Hunter <donald.hunter@...il.com>, Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Paolo Abeni <pabeni@...hat.com>, Pravin B Shelar <pshelar@....org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 5/9] net: openvswitch: add emit_sample action
On Mon, Jun 17, 2024 at 12:44:45PM GMT, Ilya Maximets wrote:
> On 6/3/24 20:56, Adrian Moreno wrote:
> > 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@...hat.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(-)
>
> Some nits below, beside ones already mentioned.
>
Thanks, Ilya.
> >
> > 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.
>
> s/16/OVS_EMIT_SAMPLE_COOKIE_MAX_SIZE/
>
> > + *
> > + * 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)) {
>
> Since the action is strictly validated, can use use nla_for_each_attr()
> or nla_for_each_nested() ?
>
Probably, yes.
> > + 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);
>
> We may need to check that we actually found the local port.
>
Sure. What can cause the local port not to exist?
> > +
> > + 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
>
> Maybe add a trailing comma here as well, since it's not a one-line definition.
> Just in case.
>
Sure.
> > + },
> > + };
> > + struct nlattr *a[OVS_EMIT_SAMPLE_ATTR_MAX + 1];
>
> One too many spaces ^^
>
Thanks.
> > + 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;
>
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