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Message-ID: <3878c16b-d6be-4935-a1ca-7f37dc677c59@redhat.com>
Date: Thu, 25 Apr 2024 09:23:50 +0200
From: Adrian Moreno <amorenoz@...hat.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: netdev@...r.kernel.org, aconole@...hat.com, echaudro@...hat.com,
horms@...nel.org, i.maximets@....org, Yotam Gigi <yotam.gi@...il.com>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 2/8] net: psample: add multicast filtering on
group_id
On 4/24/24 16:54, Jiri Pirko wrote:
> Wed, Apr 24, 2024 at 03:50:49PM CEST, amorenoz@...hat.com wrote:
>> Packet samples can come from several places (e.g: different tc sample
>> actions), typically using the sample group (PSAMPLE_ATTR_SAMPLE_GROUP)
>> to differentiate them.
>>
>> Likewise, sample consumers that listen on the multicast group may only
>> be interested on a single group. However, they are currently forced to
>> receive all samples and discard the ones that are not relevant, causing
>> unnecessary overhead.
>>
>> Allow users to filter on the desired group_id by adding a new command
>> PSAMPLE_SET_FILTER that can be used to pass the desired group id.
>> Store this filter on the per-socket private pointer and use it for
>> filtering multicasted samples.
>>
>> Signed-off-by: Adrian Moreno <amorenoz@...hat.com>
>> ---
>> include/uapi/linux/psample.h | 1 +
>> net/psample/psample.c | 110 +++++++++++++++++++++++++++++++++--
>> 2 files changed, 105 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/uapi/linux/psample.h b/include/uapi/linux/psample.h
>> index e585db5bf2d2..9d62983af0a4 100644
>> --- a/include/uapi/linux/psample.h
>> +++ b/include/uapi/linux/psample.h
>> @@ -28,6 +28,7 @@ enum psample_command {
>> PSAMPLE_CMD_GET_GROUP,
>> PSAMPLE_CMD_NEW_GROUP,
>> PSAMPLE_CMD_DEL_GROUP,
>> + PSAMPLE_CMD_SET_FILTER,
>> };
>>
>> enum psample_tunnel_key_attr {
>> diff --git a/net/psample/psample.c b/net/psample/psample.c
>> index a5d9b8446f77..f5f77515b969 100644
>> --- a/net/psample/psample.c
>> +++ b/net/psample/psample.c
>> @@ -98,13 +98,77 @@ static int psample_nl_cmd_get_group_dumpit(struct sk_buff *msg,
>> return msg->len;
>> }
>>
>> -static const struct genl_small_ops psample_nl_ops[] = {
>> +struct psample_obj_desc {
>> + struct rcu_head rcu;
>> + u32 group_num;
>> +};
>> +
>> +struct psample_nl_sock_priv {
>> + struct psample_obj_desc __rcu *filter;
>> + spinlock_t filter_lock; /* Protects filter. */
>> +};
>> +
>> +static void psample_nl_sock_priv_init(void *priv)
>> +{
>> + struct psample_nl_sock_priv *sk_priv = priv;
>> +
>> + spin_lock_init(&sk_priv->filter_lock);
>> +}
>> +
>> +static void psample_nl_sock_priv_destroy(void *priv)
>> +{
>> + struct psample_nl_sock_priv *sk_priv = priv;
>> + struct psample_obj_desc *filter;
>> +
>> + filter = rcu_dereference_protected(sk_priv->filter, true);
>> + kfree_rcu(filter, rcu);
>> +}
>> +
>> +static int psample_nl_set_filter_doit(struct sk_buff *skb,
>> + struct genl_info *info)
>> +{
>> + struct psample_obj_desc *filter = NULL;
>> + struct psample_nl_sock_priv *sk_priv;
>> + struct nlattr **attrs = info->attrs;
>> +
>> + if (attrs[PSAMPLE_ATTR_SAMPLE_GROUP]) {
>> + filter = kzalloc(sizeof(*filter), GFP_KERNEL);
>> + filter->group_num =
>> + nla_get_u32(attrs[PSAMPLE_ATTR_SAMPLE_GROUP]);
>> + }
>> +
>> + sk_priv = genl_sk_priv_get(&psample_nl_family, NETLINK_CB(skb).sk);
>> + if (IS_ERR(sk_priv)) {
>> + kfree(filter);
>> + return PTR_ERR(sk_priv);
>> + }
>> +
>> + spin_lock(&sk_priv->filter_lock);
>> + filter = rcu_replace_pointer(sk_priv->filter, filter,
>> + lockdep_is_held(&sk_priv->filter_lock));
>> + spin_unlock(&sk_priv->filter_lock);
>> + kfree_rcu(filter, rcu);
>> + return 0;
>> +}
>> +
>> +static const struct nla_policy
>> +psample_set_filter_policy[PSAMPLE_ATTR_SAMPLE_GROUP + 1] = {
>> + [PSAMPLE_ATTR_SAMPLE_GROUP] = { .type = NLA_U32, },
>> +};
>> +
>> +static const struct genl_ops psample_nl_ops[] = {
>> {
>> .cmd = PSAMPLE_CMD_GET_GROUP,
>> .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
>> .dumpit = psample_nl_cmd_get_group_dumpit,
>> /* can be retrieved by unprivileged users */
>> - }
>> + },
>> + {
>> + .cmd = PSAMPLE_CMD_SET_FILTER,
>> + .doit = psample_nl_set_filter_doit,
>> + .policy = psample_set_filter_policy,
>> + .flags = 0,
>> + },
>
> Sidenote:
> Did you think about converting psample to split ops and to introcude
> ynl spec file for it?
>
If split opts are preferred then sure, I can do that.
Thanks.
>> };
>>
>> static struct genl_family psample_nl_family __ro_after_init = {
>> @@ -114,10 +178,13 @@ static struct genl_family psample_nl_family __ro_after_init = {
>> .netnsok = true,
>> .module = THIS_MODULE,
>> .mcgrps = psample_nl_mcgrps,
>> - .small_ops = psample_nl_ops,
>> - .n_small_ops = ARRAY_SIZE(psample_nl_ops),
>> + .ops = psample_nl_ops,
>> + .n_ops = ARRAY_SIZE(psample_nl_ops),
>> .resv_start_op = PSAMPLE_CMD_GET_GROUP + 1,
>> .n_mcgrps = ARRAY_SIZE(psample_nl_mcgrps),
>> + .sock_priv_size = sizeof(struct psample_nl_sock_priv),
>> + .sock_priv_init = psample_nl_sock_priv_init,
>> + .sock_priv_destroy = psample_nl_sock_priv_destroy,
>> };
>>
>> static void psample_group_notify(struct psample_group *group,
>> @@ -360,6 +427,32 @@ static int psample_tunnel_meta_len(struct ip_tunnel_info *tun_info)
>> }
>> #endif
>>
>> +static inline void psample_nl_obj_desc_init(struct psample_obj_desc *desc,
>> + u32 group_num)
>> +{
>> + memset(desc, 0, sizeof(*desc));
>> + desc->group_num = group_num;
>> +}
>> +
>> +static int psample_nl_sample_filter(struct sock *dsk, struct sk_buff *skb,
>> + void *data)
>> +{
>> + struct psample_obj_desc *desc = data;
>> + struct psample_nl_sock_priv *sk_priv;
>> + struct psample_obj_desc *filter;
>> + int ret = 0;
>> +
>> + rcu_read_lock();
>> + sk_priv = __genl_sk_priv_get(&psample_nl_family, dsk);
>> + if (!IS_ERR_OR_NULL(sk_priv)) {
>> + filter = rcu_dereference(sk_priv->filter);
>> + if (filter && desc)
>> + ret = (filter->group_num != desc->group_num);
>> + }
>> + rcu_read_unlock();
>> + return ret;
>> +}
>> +
>> void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
>> u32 sample_rate, const struct psample_metadata *md)
>> {
>> @@ -370,6 +463,7 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
>> #ifdef CONFIG_INET
>> struct ip_tunnel_info *tun_info;
>> #endif
>> + struct psample_obj_desc desc;
>> struct sk_buff *nl_skb;
>> int data_len;
>> int meta_len;
>> @@ -487,8 +581,12 @@ void psample_sample_packet(struct psample_group *group, struct sk_buff *skb,
>> #endif
>>
>> genlmsg_end(nl_skb, data);
>> - genlmsg_multicast_netns(&psample_nl_family, group->net, nl_skb, 0,
>> - PSAMPLE_NL_MCGRP_SAMPLE, GFP_ATOMIC);
>> + psample_nl_obj_desc_init(&desc, group->group_num);
>> + genlmsg_multicast_netns_filtered(&psample_nl_family,
>> + group->net, nl_skb, 0,
>> + PSAMPLE_NL_MCGRP_SAMPLE,
>> + GFP_ATOMIC, psample_nl_sample_filter,
>> + &desc);
>>
>> return;
>> error:
>> --
>> 2.44.0
>>
>>
>
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