[PATCH net] ethtool:add netlink attr in rss get reply only if value is not null

[PATCH net] ethtool:add netlink attr in rss get reply only if value is not null

[Sudheer Mogilappagari]

Current code for RSS_GET ethtool command includes netlink attributes
in reply message to user space even if they are null. Added checks
to include netlink attribute in reply message only if a value is
received from driver. Drivers might return null for RSS indirection
table or hash key. Instead of including attributes with empty value
in the reply message, add netlink attribute only if there is content.

Fixes: 7112a04664bf ("ethtool: add netlink based get rss support")
Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>
---
 net/ethtool/rss.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
index ebe6145aed3f..be260ab34e58 100644
--- a/net/ethtool/rss.c
+++ b/net/ethtool/rss.c
@@ -122,10 +122,13 @@ rss_fill_reply(struct sk_buff *skb, const struct ethnl_req_info *req_base,
 {
 	const struct rss_reply_data *data = RSS_REPDATA(reply_base);
 
-	if (nla_put_u32(skb, ETHTOOL_A_RSS_HFUNC, data->hfunc) ||
-	    nla_put(skb, ETHTOOL_A_RSS_INDIR,
-		    sizeof(u32) * data->indir_size, data->indir_table) ||
-	    nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey))
+	if ((data->hfunc &&
+	     nla_put_u32(skb, ETHTOOL_A_RSS_HFUNC, data->hfunc)) ||
+	    (data->indir_size &&
+	     nla_put(skb, ETHTOOL_A_RSS_INDIR,
+		     sizeof(u32) * data->indir_size, data->indir_table)) ||
+	    (data->hkey_size &&
+	     nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey)))
 		return -EMSGSIZE;
 
 	return 0;
-- 
2.31.1

Re: [PATCH net] ethtool:add netlink attr in rss get reply only if value is not null

[Michal Kubecek]

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On Wed, Jan 11, 2023 at 03:56:07PM -0800, Sudheer Mogilappagari wrote:
> Current code for RSS_GET ethtool command includes netlink attributes
> in reply message to user space even if they are null. Added checks
> to include netlink attribute in reply message only if a value is
> received from driver. Drivers might return null for RSS indirection
> table or hash key. Instead of including attributes with empty value
> in the reply message, add netlink attribute only if there is content.
> 
> Fixes: 7112a04664bf ("ethtool: add netlink based get rss support")
> Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>

Reviewed-by: Michal Kubecek <mkubecek@suse.cz>

Note: the code was added in 6.2-rc1 merge window so that it is still
safe to change the output before 6.2 final without risk of "breaking the
userspace".

Michal

> ---
>  net/ethtool/rss.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
> index ebe6145aed3f..be260ab34e58 100644
> --- a/net/ethtool/rss.c
> +++ b/net/ethtool/rss.c
> @@ -122,10 +122,13 @@ rss_fill_reply(struct sk_buff *skb, const struct ethnl_req_info *req_base,
>  {
>  	const struct rss_reply_data *data = RSS_REPDATA(reply_base);
>  
> -	if (nla_put_u32(skb, ETHTOOL_A_RSS_HFUNC, data->hfunc) ||
> -	    nla_put(skb, ETHTOOL_A_RSS_INDIR,
> -		    sizeof(u32) * data->indir_size, data->indir_table) ||
> -	    nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey))
> +	if ((data->hfunc &&
> +	     nla_put_u32(skb, ETHTOOL_A_RSS_HFUNC, data->hfunc)) ||
> +	    (data->indir_size &&
> +	     nla_put(skb, ETHTOOL_A_RSS_INDIR,
> +		     sizeof(u32) * data->indir_size, data->indir_table)) ||
> +	    (data->hkey_size &&
> +	     nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey)))
>  		return -EMSGSIZE;
>  
>  	return 0;
> -- 
> 2.31.1
> 

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Re: [PATCH net] ethtool:add netlink attr in rss get reply only if value is not null

[Jakub Kicinski]

On Wed, 11 Jan 2023 15:56:07 -0800 Sudheer Mogilappagari wrote:
> Current code for RSS_GET ethtool command includes netlink attributes
> in reply message to user space even if they are null. Added checks
> to include netlink attribute in reply message only if a value is
> received from driver. Drivers might return null for RSS indirection
> table or hash key. Instead of including attributes with empty value
> in the reply message, add netlink attribute only if there is content.
> 
> Fixes: 7112a04664bf ("ethtool: add netlink based get rss support")
> Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>

Applied, thanks!