cfg80211: introduce scan IE limit attribute

This patch introduces a new attribute for a wiphy that tells
userspace how long the information elements added to a probe
request frame can be at most. It also updates the at76 to
advertise that it cannot support that, and, for now until I
can fix that, iwlwifi too.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 21 insertions, 1 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index fbcbed6cad01..ee58a7873699 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -728,7 +728,18 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
                 return NULL;
 
         wiphy->privid = mac80211_wiphy_privid;
-        wiphy->max_scan_ssids = 4;
+
+        if (!ops->hw_scan) {
+                /* For hw_scan, driver needs to set these up. */
+                wiphy->max_scan_ssids = 4;
+
+                /* we support a maximum of 32 rates in cfg80211 */
+                wiphy->max_scan_ie_len = IEEE80211_MAX_DATA_LEN
+                                         - 2 - 32 /* SSID */
+                                         - 4 - 32 /* (ext) supp rates */;
+
+        }
+
         /* Yes, putting cfg80211_bss into ieee80211_bss is a hack */
         wiphy->bss_priv_size = sizeof(struct ieee80211_bss) -
                                sizeof(struct cfg80211_bss);
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index fdf432f14554..05caf34f31da 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -890,6 +890,8 @@ void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
                 *pos = rate->bitrate / 5;
         }
 
+        /* if adding more here, adjust max_scan_ie_len */
+
         if (ie)
                 memcpy(skb_put(skb, ie_len), ie, ie_len);
 
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 1394115cde95..447fa1790b4e 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -181,6 +181,8 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
         NLA_PUT_STRING(msg, NL80211_ATTR_WIPHY_NAME, wiphy_name(&dev->wiphy));
         NLA_PUT_U8(msg, NL80211_ATTR_MAX_NUM_SCAN_SSIDS,
                    dev->wiphy.max_scan_ssids);
+        NLA_PUT_U16(msg, NL80211_ATTR_MAX_SCAN_IE_LEN,
+                    dev->wiphy.max_scan_ie_len);
 
         nl_modes = nla_nest_start(msg, NL80211_ATTR_SUPPORTED_IFTYPES);
         if (!nl_modes)
@@ -2528,6 +2530,11 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
         else
                 ie_len = 0;
 
+        if (ie_len > wiphy->max_scan_ie_len) {
+                err = -EINVAL;
+                goto out;
+        }
+
         request = kzalloc(sizeof(*request)
                         + sizeof(*ssid) * n_ssids
                         + sizeof(channel) * n_channels