From: Samuel Ortiz <samuel.ortiz@xxxxxxxxx>
In very dense environment, the scan result buffer can get really large, mostly
due to the addition of proprietary IEs. iwlist fails, typically warning about:
"print_scanning_info: Allocation failed". wpa_supplicant fails as well, after
reallocating the scan result buffer several times, up to 132 Kbytes:
[snip]
Scan results did not fit - trying larger buffer (131072 bytes)
ioctl[SIOCGIWSCAN]: Argument list too long
By adding a mac80211 module parameter, we can filter the scan results and keep
only the ones userspace currently worries about, i.e. WPA1, WPA2, WMM and WPS.
To activate this feature, 1 has to be written to
/sys/module/mac80211/parameters/ieee80211_scan_ie_filter
Signed-off-by: Samuel Ortiz <samuel.ortiz@xxxxxxxxx>
---
net/mac80211/ieee80211_i.h | 1
net/mac80211/scan.c | 65 ++++++++++++++++++++++++++++++---------------
net/mac80211/util.c | 40 +++++++++++++++++++++++++++
3 files changed, 85 insertions(+), 21 deletions(-)
Index: wireless-testing/net/mac80211/scan.c
===================================================================
--- wireless-testing.orig/net/mac80211/scan.c 2009-01-28 11:37:55.000000000 +0100
+++ wireless-testing/net/mac80211/scan.c 2009-01-28 17:32:48.000000000 +0100
@@ -31,6 +31,11 @@
#define IEEE80211_CHANNEL_TIME (HZ / 33)
#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)
+static int ieee80211_scan_ie_filter;
+module_param(ieee80211_scan_ie_filter, bool, 0644);
+MODULE_PARM_DESC(ieee80211_scan_ie_filter,
+ "Filter IEs from scan results");
+
void ieee80211_rx_bss_list_init(struct ieee80211_local *local)
{
spin_lock_init(&local->bss_lock);
@@ -725,33 +730,51 @@ static void ieee80211_scan_add_ies(struc
if (bss == NULL || bss->ies == NULL)
return;
- /*
- * If needed, fragment the IEs buffer (at IE boundaries) into short
- * enough fragments to fit into IW_GENERIC_IE_MAX octet messages.
- */
pos = bss->ies;
end = pos + bss->ies_len;
- while (end - pos > IW_GENERIC_IE_MAX) {
- next = pos + 2 + pos[1];
- while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
- next = next + 2 + next[1];
+ if (ieee80211_scan_ie_filter) {
+ while (pos - end) {
+ next = pos + 2 + pos[1];
+ if (ieee80211_filter_ie(pos)) {
+ memset(&iwe, 0, sizeof(iwe));
+ iwe.cmd = IWEVGENIE;
+ iwe.u.data.length = next - pos;
+ *current_ev =
+ iwe_stream_add_point(info, *current_ev,
+ end_buf, &iwe,
+ pos);
+ }
+ pos = next;
+ }
+ } else {
+ /*
+ * If needed, fragment the IEs buffer (at IE boundaries) into
+ * short enough fragments to fit into IW_GENERIC_IE_MAX octet
+ * messages.
+ */
+
+ while (end - pos > IW_GENERIC_IE_MAX) {
+ next = pos + 2 + pos[1];
+ while (next + 2 + next[1] - pos < IW_GENERIC_IE_MAX)
+ next = next + 2 + next[1];
- memset(&iwe, 0, sizeof(iwe));
- iwe.cmd = IWEVGENIE;
- iwe.u.data.length = next - pos;
- *current_ev = iwe_stream_add_point(info, *current_ev,
- end_buf, &iwe, pos);
+ memset(&iwe, 0, sizeof(iwe));
+ iwe.cmd = IWEVGENIE;
+ iwe.u.data.length = next - pos;
+ *current_ev = iwe_stream_add_point(info, *current_ev,
+ end_buf, &iwe, pos);
- pos = next;
- }
+ pos = next;
+ }
- if (end > pos) {
- memset(&iwe, 0, sizeof(iwe));
- iwe.cmd = IWEVGENIE;
- iwe.u.data.length = end - pos;
- *current_ev = iwe_stream_add_point(info, *current_ev,
- end_buf, &iwe, pos);
+ if (end > pos) {
+ memset(&iwe, 0, sizeof(iwe));
+ iwe.cmd = IWEVGENIE;
+ iwe.u.data.length = end - pos;
+ *current_ev = iwe_stream_add_point(info, *current_ev,
+ end_buf, &iwe, pos);
+ }
}
}
Index: wireless-testing/net/mac80211/util.c
===================================================================
--- wireless-testing.orig/net/mac80211/util.c 2009-01-28 11:37:41.000000000 +0100
+++ wireless-testing/net/mac80211/util.c 2009-01-28 15:57:03.000000000 +0100
@@ -675,6 +675,46 @@ void ieee802_11_parse_elems(u8 *start, s
}
}
+/*
+ * ieee80211_filter_ie() tries to keep only the relevant IEs for
+ * userspace (mostly hostap code).
+ */
+int ieee80211_filter_ie(u8 *ie)
+{
+ u8 id, ie_len, *pos;
+ u8 microsoft_oui[4] = {0x00, 0x50, 0xf2};
+ u8 wpa2_oui[3] = {0x00, 0x0f, 0xac};
+
+ pos = ie;
+ id = *pos++;
+ ie_len = *pos++;
+
+ switch (id) {
+ case WLAN_EID_RSN:
+ /* WPA2 */
+ if (ie_len >= 3 &&
+ !memcmp(pos, wpa2_oui, 3))
+ return 1;
+
+ return 0;
+
+ case WLAN_EID_VENDOR_SPECIFIC:
+ /* We're trying to catch WPA1, WMM and WPS IEs. */
+ if (ie_len >= 3 &&
+ !memcmp(pos, microsoft_oui, 3)) {
+ if ((pos[3] == 1) || /* WPA1 */
+ (pos[3] == 2) || /* WMM */
+ (pos[3] == 4)) /* WPS */
+ return 1;
+ }
+
+ return 0;
+
+ default:
+ return 0;
+ }
+}
+
void ieee80211_set_wmm_default(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_local *local = sdata->local;
Index: wireless-testing/net/mac80211/ieee80211_i.h
===================================================================
--- wireless-testing.orig/net/mac80211/ieee80211_i.h 2009-01-28 11:37:41.000000000 +0100
+++ wireless-testing/net/mac80211/ieee80211_i.h 2009-01-28 13:49:17.000000000 +0100
@@ -1028,6 +1028,7 @@ void ieee80211_tx_skb(struct ieee80211_s
int encrypt);
void ieee802_11_parse_elems(u8 *start, size_t len,
struct ieee802_11_elems *elems);
+int ieee80211_filter_ie(u8 *ie);
int ieee80211_set_freq(struct ieee80211_sub_if_data *sdata, int freq);
u32 ieee80211_mandatory_rates(struct ieee80211_local *local,
enum ieee80211_band band);
--
Intel Open Source Technology Centre
http://oss.intel.com/
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