linux-kernel - [PATCH 3.16 100/136] nl80211: don't expose wdev->ssid for most interfaces

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Message-ID: <lsq.1518323471.830922146@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:31:11 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Johannes Berg" <johannes.berg@...el.com>
Subject: [PATCH 3.16 100/136] nl80211: don't expose wdev->ssid for most
 interfaces

3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@...el.com>

commit 44905265bc155e0237c76c25bf5ddf740d85a8f2 upstream.

For mesh, this is simply wrong - there's no SSID, only the
mesh ID, so don't expose it at all.
For (P2P) client, it's wrong, because it exposes an internal
value that's only used when certain APIs are used.
For AP, it's actually the only correct case, so leave that.
All other interface types shouldn't be setting this anyway,
so there it won't change anything.

Fixes: b84e7a05f619 ("nl80211: send the NL80211_ATTR_SSID in nl80211_send_iface()")
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/wireless/nl80211.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2341,10 +2341,32 @@ static int nl80211_send_iface(struct sk_
 		}
 	}
 
-	if (wdev->ssid_len) {
-		if (nla_put(msg, NL80211_ATTR_SSID, wdev->ssid_len, wdev->ssid))
+	wdev_lock(wdev);
+	switch (wdev->iftype) {
+	case NL80211_IFTYPE_AP:
+		if (wdev->ssid_len &&
+		    nla_put(msg, NL80211_ATTR_SSID, wdev->ssid_len, wdev->ssid))
 			goto nla_put_failure;
+		break;
+	case NL80211_IFTYPE_STATION:
+	case NL80211_IFTYPE_P2P_CLIENT:
+	case NL80211_IFTYPE_ADHOC: {
+		const u8 *ssid_ie;
+		if (!wdev->current_bss)
+			break;
+		ssid_ie = ieee80211_bss_get_ie(&wdev->current_bss->pub,
+					       WLAN_EID_SSID);
+		if (!ssid_ie)
+			break;
+		if (nla_put(msg, NL80211_ATTR_SSID, ssid_ie[1], ssid_ie + 2))
+			goto nla_put_failure;
+		break;
+		}
+	default:
+		/* nothing */
+		break;
 	}
+	wdev_unlock(wdev);
 
 	return genlmsg_end(msg, hdr);