Re: [PATCH net-next v5 02/10] net: sched: act_sample: add action cookie to sample

From: Eelco Chaudron
Date: Wed Jun 26 2024 - 10:29:22 EST




On 25 Jun 2024, at 22:51, Adrian Moreno wrote:

> If the action has a user_cookie, pass it along to the sample so it can
> be easily identified.
>
> Signed-off-by: Adrian Moreno <amorenoz@xxxxxxxxxx>
> ---
> net/sched/act_sample.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/net/sched/act_sample.c b/net/sched/act_sample.c
> index a69b53d54039..2ceb4d141b71 100644
> --- a/net/sched/act_sample.c
> +++ b/net/sched/act_sample.c
> @@ -167,7 +167,9 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb,
> {
> struct tcf_sample *s = to_sample(a);
> struct psample_group *psample_group;
> + u8 cookie_data[TC_COOKIE_MAX_SIZE];
> struct psample_metadata md = {};
> + struct tc_cookie *user_cookie;
> int retval;
>
> tcf_lastuse_update(&s->tcf_tm);
> @@ -189,6 +191,16 @@ TC_INDIRECT_SCOPE int tcf_sample_act(struct sk_buff *skb,
> if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
> skb_push(skb, skb->mac_len);
>
> + rcu_read_lock();
> + user_cookie = rcu_dereference(a->user_cookie);
> + if (user_cookie) {
> + memcpy(cookie_data, user_cookie->data,
> + user_cookie->len);

Maybe I’m over paranoid, but can we assume user_cookie->len, will not be larger than TC_COOKIE_MAX_SIZE?
Or should we do something like min(user_cookie->len, sizeof(cookie_data))

> + md.user_cookie = cookie_data;
> + md.user_cookie_len = user_cookie->len;
> + }
> + rcu_read_unlock();
> +
> md.trunc_size = s->truncate ? s->trunc_size : skb->len;
> psample_sample_packet(psample_group, skb, s->rate, &md);
>
> --
> 2.45.1