Hi Johannes,
On Wed, Jan 18, 2023 at 05:26:19PM +0100, Johannes Berg wrote:
> On Fri, 2022-12-09 at 16:28 +0100, Alvin Šipraga wrote:
> >
> > This is problematic because it is possible that the network
> > configuration that should be applied is a function of the AP's
> > properties such as SSID (cf. SSID= in systemd.network(5)). As
> > illustrated in the above diagram, it may be that the AP with SSID "bar"
> > ends up being configured as though it had SSID "foo".
> >
>
> You might not care if you want the SSID, but it still seems wrong:
>
> > +static void nl80211_send_ap_started(struct wireless_dev *wdev)
> > +{
> > + struct wiphy *wiphy = wdev->wiphy;
> > + struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
> > + struct sk_buff *msg;
> > + void *hdr;
> > +
> > + msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> > + if (!msg)
> > + return;
> > +
> > + hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_START_AP);
> > + if (!hdr)
> > + goto out;
> > +
> > + if (nla_put_u32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx) ||
> > + nla_put_u32(msg, NL80211_ATTR_IFINDEX, wdev->netdev->ifindex) ||
> > + nla_put_u64_64bit(msg, NL80211_ATTR_WDEV, wdev_id(wdev),
> > + NL80211_ATTR_PAD) ||
> > + (wdev->u.ap.ssid_len &&
> > + nla_put(msg, NL80211_ATTR_SSID, wdev->u.ap.ssid_len,
> > + wdev->u.ap.ssid)))
> > + goto out;
> > +
> > + genlmsg_end(msg, hdr);
> > +
> > + genlmsg_multicast_netns(&nl80211_fam, wiphy_net(wiphy), msg, 0,
> > + NL80211_MCGRP_MLME, GFP_KERNEL);
> > + return;
> > +out:
> > + nlmsg_free(msg);
> > +}
>
> This has no indication of the link, but with multi-link you could
> actually be sending this event multiple times to userspace on the same
> netdev.
>
> > static int nl80211_start_ap(struct sk_buff *skb, struct genl_info *info)
> > {
> > struct cfg80211_registered_device *rdev = info->user_ptr[0];
> > @@ -6050,6 +6083,8 @@ static int nl80211_start_ap(struct sk_buff *skb, struct genl_info *info)
> >
> > if (info->attrs[NL80211_ATTR_SOCKET_OWNER])
> > wdev->conn_owner_nlportid = info->snd_portid;
> > +
> > + nl80211_send_ap_started(wdev);
> > }
>
> because this can be called multiple times, once for each link.
>
> Seems like you should include the link ID or something?
Thanks for your review, you are quite right. I didn't give much thought
to MLO as I am not too familiar with it. Is something like the below
what you are looking for?
Speaking of which: I drew inspiration from nl80211_send_ap_stopped()
which see also doesn't include the link ID. Would you like me to include
a second patch in v2 which adds the link ID to that function along the
same lines?
Kind regards,
Alvin
-------------->8----------------------------------
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index ba4965f035b2..5720ffcbecc4 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5770,7 +5770,7 @@ static bool nl80211_valid_auth_type(struct cfg80211_registered_device *rdev,
}
}
-static void nl80211_send_ap_started(struct wireless_dev *wdev)
+static void nl80211_send_ap_started(struct wireless_dev *wdev, unsigned int link_id)
{
struct wiphy *wiphy = wdev->wiphy;
struct cfg80211_registered_device *rdev = wiphy_to_rdev(wiphy);
@@ -5791,7 +5791,9 @@ static void nl80211_send_ap_started(struct wireless_dev *wdev)
NL80211_ATTR_PAD) ||
(wdev->u.ap.ssid_len &&
nla_put(msg, NL80211_ATTR_SSID, wdev->u.ap.ssid_len,
- wdev->u.ap.ssid)))
+ wdev->u.ap.ssid)) ||
+ (wdev->valid_links &&
+ nla_put_u8(msg, NL80211_ATTR_MLO_LINK_ID, link_id)))
goto out;
genlmsg_end(msg, hdr);
@@ -6084,7 +6086,7 @@ static int nl80211_start_ap(struct sk_buff *skb, struct genl_info *info)
if (info->attrs[NL80211_ATTR_SOCKET_OWNER])
wdev->conn_owner_nlportid = info->snd_portid;
- nl80211_send_ap_started(wdev);
+ nl80211_send_ap_started(wdev, link_id);
}
out_unlock:
wdev_unlock(wdev);
