[RFC] nl80211: Allow GET_INTERFACE dumps to be filtered

[RFC] nl80211: Allow GET_INTERFACE dumps to be filtered

[Denis Kenzior]

This patch allows GET_INTERFACE dumps to be filtered based on
NL80211_ATTR_WIPHY or NL80211_ATTR_WDEV.  The documentation for
GET_INTERFACE mentions that this is possible:
"Request an interface's configuration; either a dump request on
a %NL80211_ATTR_WIPHY or ..."

However, this behavior has not been implemented until now.
---
 net/wireless/nl80211.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 244d552..24cb4d9 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2515,15 +2515,47 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag
 	return -EMSGSIZE;
 }
 
+static int nl80211_dump_interface_parse(struct sk_buff *skb,
+				    struct netlink_callback *cb,
+				    int *filter_wiphy)
+{
+	struct nlattr **tb = nl80211_fam.attrbuf;
+	int ret = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
+			      tb, nl80211_fam.maxattr, nl80211_policy);
+	/* ignore parse errors for backward compatibility */
+	if (ret)
+		return 0;
+
+	if (tb[NL80211_ATTR_WIPHY])
+		*filter_wiphy = nla_get_u32(tb[NL80211_ATTR_WIPHY]);
+	if (tb[NL80211_ATTR_WDEV])
+		*filter_wiphy = nla_get_u64(tb[NL80211_ATTR_WDEV]) >> 32;
+
+	return 0;
+}
+
 static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	int wp_idx = 0;
 	int if_idx = 0;
 	int wp_start = cb->args[0];
 	int if_start = cb->args[1];
+	int filter_wiphy = cb->args[2];
 	struct cfg80211_registered_device *rdev;
 	struct wireless_dev *wdev;
 
+	if (!wp_start && !if_start && !filter_wiphy) {
+		int ret;
+
+		filter_wiphy = -1;
+
+		ret = nl80211_dump_interface_parse(skb, cb, &filter_wiphy);
+		if (ret)
+			return ret;
+
+		cb->args[2] = filter_wiphy;
+	}
+
 	rtnl_lock();
 	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
 		if (!net_eq(wiphy_net(&rdev->wiphy), sock_net(skb->sk)))
@@ -2532,6 +2564,10 @@ static int nl80211_dump_interface(struct sk_buff *skb, struct netlink_callback *
 			wp_idx++;
 			continue;
 		}
+
+		if (filter_wiphy != -1 && filter_wiphy != rdev->wiphy_idx)
+			continue;
+
 		if_idx = 0;
 
 		list_for_each_entry(wdev, &rdev->wiphy.wdev_list, list) {
-- 
2.7.3

Re: [RFC] nl80211: Allow GET_INTERFACE dumps to be filtered

[Johannes Berg]

On Thu, 2016-06-30 at 19:51 -0500, Denis Kenzior wrote:
> This patch allows GET_INTERFACE dumps to be filtered based on
> NL80211_ATTR_WIPHY or NL80211_ATTR_WDEV.  The documentation for
> GET_INTERFACE mentions that this is possible:
> "Request an interface's configuration; either a dump request on
> a %NL80211_ATTR_WIPHY or ..."
> 
> However, this behavior has not been implemented until now.
> ---
>  net/wireless/nl80211.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
> index 244d552..24cb4d9 100644
> --- a/net/wireless/nl80211.c
> +++ b/net/wireless/nl80211.c
> @@ -2515,15 +2515,47 @@ static int nl80211_send_iface(struct sk_buff
> *msg, u32 portid, u32 seq, int flag
>  	return -EMSGSIZE;
>  }
>  
> +static int nl80211_dump_interface_parse(struct sk_buff *skb,
> +				    struct netlink_callback *cb,
> +				    int *filter_wiphy)
> +{
> +	struct nlattr **tb = nl80211_fam.attrbuf;
> +	int ret = nlmsg_parse(cb->nlh, GENL_HDRLEN +
> nl80211_fam.hdrsize,
> +			      tb, nl80211_fam.maxattr,
> nl80211_policy);
> +	/* ignore parse errors for backward compatibility */
> +	if (ret)
> +		return 0;
> +
> +	if (tb[NL80211_ATTR_WIPHY])
> +		*filter_wiphy = nla_get_u32(tb[NL80211_ATTR_WIPHY]);
> +	if (tb[NL80211_ATTR_WDEV])
> +		*filter_wiphy = nla_get_u64(tb[NL80211_ATTR_WDEV])
> >> 32;

The whole ret thing seems a bit pointless since you check the tb[], but
I guess it's better to be explicit.

Looks fine.

johannes

Re: [RFC] nl80211: Allow GET_INTERFACE dumps to be filtered

[Denis Kenzior]

Hi Johannes,

 >
> Looks fine.
>

Thanks for the review.  I rebased & resent this patch as a non-RFC.

Regards,
-Denis