Re: [PATCH net-next 2/8] net: psample: add multicast filtering on group_id
From: Adrian Moreno
Date: Thu Apr 25 2024 - 03:24:27 EST
On 4/24/24 16:54, Jiri Pirko wrote:
Wed, Apr 24, 2024 at 03:50:49PM CEST, amorenoz@xxxxxxxxxx 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@xxxxxxxxxx>
---
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