Re: [PATCH v2 net] inet_diag: add cgroup id attribute

[Konstantin Khlebnikov <khlebnikov@yandex-team.ru>]

On 30/03/2020 14.38, Dmitry Yakunin wrote:
> This patch adds cgroup v2 id to common inet diag message attributes.
> This allows investigate sockets on per cgroup basis when
> net_cls/net_prio cgroup not used.

After second thought:
Option CONFIG_SOCK_CGROUP_DATA are not directly enabled in config.
It's selected by CONFIG_CGROUP_BPF or legacy CGROUP_NET_CLASSID/PRIO.

So, it would be more clear to put this code under ifdef CONFIG_CGROUP_BPF.
Because it exposes cgroup2 id and has nothing to do with legacy cgroups.

+CC cgroups@vger.kernel.org and bpf@vger.kernel.org

> 
> Signed-off-by: Dmitry Yakunin <zeil@yandex-team.ru>
> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> ---
>   include/linux/inet_diag.h      | 6 +++++-
>   include/uapi/linux/inet_diag.h | 1 +
>   net/ipv4/inet_diag.c           | 7 +++++++
>   3 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/inet_diag.h b/include/linux/inet_diag.h
> index c91cf2d..8bc5e7d 100644
> --- a/include/linux/inet_diag.h
> +++ b/include/linux/inet_diag.h
> @@ -66,7 +66,11 @@ static inline size_t inet_diag_msg_attrs_size(void)
>   		+ nla_total_size(1)  /* INET_DIAG_SKV6ONLY */
>   #endif
>   		+ nla_total_size(4)  /* INET_DIAG_MARK */
> -		+ nla_total_size(4); /* INET_DIAG_CLASS_ID */
> +		+ nla_total_size(4)  /* INET_DIAG_CLASS_ID */
> +#ifdef CONFIG_SOCK_CGROUP_DATA
> +		+ nla_total_size(8)  /* INET_DIAG_CGROUP_ID */
> +#endif
> +		;
>   }
>   int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
>   			     struct inet_diag_msg *r, int ext,
> diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
> index a1ff345..dc87ad6 100644
> --- a/include/uapi/linux/inet_diag.h
> +++ b/include/uapi/linux/inet_diag.h
> @@ -154,6 +154,7 @@ enum {
>   	INET_DIAG_CLASS_ID,	/* request as INET_DIAG_TCLASS */
>   	INET_DIAG_MD5SIG,
>   	INET_DIAG_ULP_INFO,
> +	INET_DIAG_CGROUP_ID,
>   	__INET_DIAG_MAX,
>   };
>   
> diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
> index 8c83775..ba0bb14 100644
> --- a/net/ipv4/inet_diag.c
> +++ b/net/ipv4/inet_diag.c
> @@ -161,6 +161,13 @@ int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
>   			goto errout;
>   	}
>   
> +#ifdef CONFIG_SOCK_CGROUP_DATA
> +	if (nla_put_u64_64bit(skb, INET_DIAG_CGROUP_ID,
> +			      cgroup_id(sock_cgroup_ptr(&sk->sk_cgrp_data)),
> +			      INET_DIAG_PAD))
> +		goto errout;
> +#endif
> +
>   	r->idiag_uid = from_kuid_munged(user_ns, sock_i_uid(sk));
>   	r->idiag_inode = sock_i_ino(sk);
>   
>