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>

7 files changed, 28 insertions, 1 deletions

diff --git a/drivers/net/wireless/at76c50x-usb.c b/drivers/net/wireless/at76c50x-usb.c
index 69248ded5102..55f947ac56d1 100644
--- a/drivers/net/wireless/at76c50x-usb.c
+++ b/drivers/net/wireless/at76c50x-usb.c
@@ -2250,6 +2250,7 @@ static int at76_init_new_device(struct at76_priv *priv,
 
         /* mac80211 initialisation */
         priv->hw->wiphy->max_scan_ssids = 1;
+        priv->hw->wiphy->max_scan_ie_len = 0;
         priv->hw->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION);
         priv->hw->wiphy->bands[IEEE80211_BAND_2GHZ] = &at76_supported_band;
         priv->hw->flags = IEEE80211_HW_RX_INCLUDES_FCS |
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.c b/drivers/net/wireless/iwlwifi/iwl-core.c
index 82abb1f9087f..ef55f91374a1 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.c
+++ b/drivers/net/wireless/iwlwifi/iwl-core.c
@@ -1306,6 +1306,7 @@ int iwl_setup_mac(struct iwl_priv *priv)
 
         hw->wiphy->custom_regulatory = true;
         hw->wiphy->max_scan_ssids = 1;
+        hw->wiphy->max_scan_ie_len = 0; /* XXX for now */
 
         /* Default value; 4 EDCA QOS priorities */
         hw->queues = 4;
diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 27f230f063b3..209cacee5285 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -390,6 +390,8 @@ enum nl80211_commands {
  *
  * @NL80211_ATTR_MAX_NUM_SCAN_SSIDS: number of SSIDs you can scan with
  *      a single scan request, a wiphy attribute.
+ * @NL80211_ATTR_MAX_SCAN_IE_LEN: maximum length of information elements
+ *      that can be added to a scan request
  *
  * @NL80211_ATTR_SCAN_FREQUENCIES: nested attribute with frequencies (in MHz)
  * @NL80211_ATTR_SCAN_SSIDS: nested attribute with SSIDs, leave out for passive
@@ -507,6 +509,8 @@ enum nl80211_attrs {
 
         NL80211_ATTR_KEY_TYPE,
 
+        NL80211_ATTR_MAX_SCAN_IE_LEN,
+
         /* add attributes here, update the policy in nl80211.c */
 
         __NL80211_ATTR_AFTER_LAST,
diff --git a/include/net/wireless.h b/include/net/wireless.h
index 64a76208580c..2bcdeda46d81 100644
--- a/include/net/wireless.h
+++ b/include/net/wireless.h
@@ -222,6 +222,7 @@ struct wiphy {
 
         int bss_priv_size;
         u8 max_scan_ssids;
+        u16 max_scan_ie_len;
 
         /* If multiple wiphys are registered and you're handed e.g.
          * a regular netdev with assigned ieee80211_ptr, you won't
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