netdev - Re: [PATCH net-next 1/8] bridge: mcast: Centralize netlink attribute parsing

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Message-ID: <06490c08-bf5e-1714-f56c-1a6068fb2ec9@blackwall.org>
Date:   Mon, 5 Dec 2022 13:34:08 +0200
From:   Nikolay Aleksandrov <razor@...ckwall.org>
To:     Ido Schimmel <idosch@...dia.com>, netdev@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Cc:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com, roopa@...dia.com, mlxsw@...dia.com
Subject: Re: [PATCH net-next 1/8] bridge: mcast: Centralize netlink attribute
 parsing

On 05/12/2022 09:42, Ido Schimmel wrote:
> Netlink attributes are currently passed deep in the MDB creation call
> chain, making it difficult to add new attributes. In addition, some
> validity checks are performed under the multicast lock although they can
> be performed before it is ever acquired.
> 
> As a first step towards solving these issues, parse the RTM_{NEW,DEL}MDB
> messages into a configuration structure, relieving other functions from
> the need to handle raw netlink attributes.
> 
> Subsequent patches will convert the MDB code to use this configuration
> structure.
> 
> This is consistent with how other rtnetlink objects are handled, such as
> routes and nexthops.
> 
> Signed-off-by: Ido Schimmel <idosch@...dia.com>
> ---
>  net/bridge/br_mdb.c     | 120 ++++++++++++++++++++++++++++++++++++++++
>  net/bridge/br_private.h |   7 +++
>  2 files changed, 127 insertions(+)
> 
> diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
> index 321be94c445a..c53050e47a0f 100644
> --- a/net/bridge/br_mdb.c
> +++ b/net/bridge/br_mdb.c
> @@ -974,6 +974,116 @@ static int __br_mdb_add(struct net *net, struct net_bridge *br,
>  	return ret;
>  }
>  
> +static int br_mdb_config_attrs_init(struct nlattr *set_attrs,
> +				    struct br_mdb_config *cfg,
> +				    struct netlink_ext_ack *extack)
> +{
> +	struct nlattr *mdb_attrs[MDBE_ATTR_MAX + 1];
> +	int err;
> +
> +	err = nla_parse_nested(mdb_attrs, MDBE_ATTR_MAX, set_attrs,
> +			       br_mdbe_attrs_pol, extack);
> +	if (err)
> +		return err;
> +
> +	if (mdb_attrs[MDBE_ATTR_SOURCE] &&
> +	    !is_valid_mdb_source(mdb_attrs[MDBE_ATTR_SOURCE],
> +				 cfg->entry->addr.proto, extack))
> +		return -EINVAL;
> +
> +	__mdb_entry_to_br_ip(cfg->entry, &cfg->group, mdb_attrs);
> +
> +	return 0;
> +}
> +
> +static int br_mdb_config_init(struct net *net, struct sk_buff *skb,
> +			      struct nlmsghdr *nlh, struct br_mdb_config *cfg,
> +			      struct netlink_ext_ack *extack)
> +{

I just noticed the skb argument is unused. Does it get used in a future change?
Also a minor nit - I think nlh can be a const, nlmsg_parse_deprecated already uses a const nlh.