linux-kernel - Re: [PATCH net-next 1/7] net: ethtool: netlink: Allow per-netdevice DUMP operations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250307122119.GE3666230@kernel.org>
Date: Fri, 7 Mar 2025 12:21:19 +0000
From: Simon Horman <horms@...nel.org>
To: Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc: davem@...emloft.net, Andrew Lunn <andrew@...n.ch>,
	Jakub Kicinski <kuba@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	Heiner Kallweit <hkallweit1@...il.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, thomas.petazzoni@...tlin.com,
	linux-arm-kernel@...ts.infradead.org,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Herve Codina <herve.codina@...tlin.com>,
	Florian Fainelli <f.fainelli@...il.com>,
	Russell King <linux@...linux.org.uk>,
	Vladimir Oltean <vladimir.oltean@....com>,
	Köry Maincent <kory.maincent@...tlin.com>,
	Oleksij Rempel <o.rempel@...gutronix.de>,
	Romain Gantois <romain.gantois@...tlin.com>,
	Piergiorgio Beruto <piergiorgio.beruto@...il.com>
Subject: Re: [PATCH net-next 1/7] net: ethtool: netlink: Allow per-netdevice
 DUMP operations

On Wed, Mar 05, 2025 at 03:19:31PM +0100, Maxime Chevallier wrote:
> We have a number of netlink commands in the ethnl family that may have
> multiple objects to dump even for a single net_device, including :
> 
>  - PLCA, PSE-PD, phy: one message per PHY device
>  - tsinfo: one message per timestamp source (netdev + phys)
>  - rss: One per RSS context
> 
> To get this behaviour, these netlink commands need to roll a custom
> ->dumpit().
> 
> To prepare making per-netdev DUMP more generic in ethnl, introduce a
> member in the ethnl ops to indicate if a given command may allow
> pernetdev DUMPs (also referred to as filtered DUMPs).
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
> ---
>  net/ethtool/netlink.c | 45 ++++++++++++++++++++++++++++---------------
>  net/ethtool/netlink.h |  1 +
>  2 files changed, 30 insertions(+), 16 deletions(-)
> 
> diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
> index 734849a57369..0815b28ba32f 100644
> --- a/net/ethtool/netlink.c
> +++ b/net/ethtool/netlink.c
> @@ -578,21 +578,34 @@ static int ethnl_default_dumpit(struct sk_buff *skb,
>  	int ret = 0;
>  
>  	rcu_read_lock();
> -	for_each_netdev_dump(net, dev, ctx->pos_ifindex) {
> -		dev_hold(dev);
> +	if (ctx->req_info->dev) {
> +		dev = ctx->req_info->dev;
>  		rcu_read_unlock();
> -
> -		ret = ethnl_default_dump_one(skb, dev, ctx, genl_info_dump(cb));
> -
> +		/* Filtered DUMP request targeted to a single netdev. We already
> +		 * hold a ref to the netdev from ->start()
> +		 */
> +		ret = ethnl_default_dump_one_dev(skb, dev, ctx,
> +						 genl_info_dump(cb));

Hi Maxime,

ethnl_default_dump_one_dev() is called here but it doesn't exist
until the following patch is applied, which breaks bisection.

>  		rcu_read_lock();
> -		dev_put(dev);
> -
> -		if (ret < 0 && ret != -EOPNOTSUPP) {
> -			if (likely(skb->len))
> -				ret = skb->len;
> -			break;
> +		netdev_put(ctx->req_info->dev, &ctx->req_info->dev_tracker);
> +	} else {
> +		for_each_netdev_dump(net, dev, ctx->pos_ifindex) {
> +			dev_hold(dev);
> +			rcu_read_unlock();
> +
> +			ret = ethnl_default_dump_one(skb, dev, ctx,
> +						     genl_info_dump(cb));
> +
> +			rcu_read_lock();
> +			dev_put(dev);
> +
> +			if (ret < 0 && ret != -EOPNOTSUPP) {
> +				if (likely(skb->len))
> +					ret = skb->len;
> +				break;
> +			}
> +			ret = 0;
>  		}
> -		ret = 0;
>  	}
>  	rcu_read_unlock();
>  

...

> diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
> index ec6ab5443a6f..4db27182741f 100644
> --- a/net/ethtool/netlink.h
> +++ b/net/ethtool/netlink.h
> @@ -388,6 +388,7 @@ struct ethnl_request_ops {
>  	unsigned int		req_info_size;
>  	unsigned int		reply_data_size;
>  	bool			allow_nodev_do;
> +	bool			allow_pernetdev_dump;

nit: allow_pernetdev_dump should also be added to the Kernel doc for
     struct ethnl_request_ops

     Flagged by ./scripts/kernel-doc -none

     There also appear to be similar minor issues with subsequent
     patches in this series.

>  	u8			set_ntf_cmd;
>  
>  	int (*parse_request)(struct ethnl_req_info *req_info,
> -- 
> 2.48.1
>