cfg80211: merge in beacon ies of hidden bss.
The problem with PSM when a hidden SSID was used was originally reported by Juuso Oikarinen. - When generally scanning, the AP is getting a bss entry with a zero SSID. - When associating, a probe-req is sent to the AP with the SSID, and as a result a probe-response is received with the hidden SSID in place. As a consequence, a second bss entry is created for the AP, now with the real SSID. - After association, mac80211 executes ieee80211_recalc_ps(), but does not switch to powersave because the beacon-ies are missing. As result, the STA does not ever enter PSM. The patch merges in beacon ies of hidden bss from beacon to the probe response, creating a consistent set of ies in place. Patch is depended on "cfg80211: fix cmp_ies" made by Johannes. Signed-off-by: Dmitry Tarnyagin <dmitry.tarnyagin@stericsson.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
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@ -355,8 +355,8 @@ static bool is_mesh(struct cfg80211_bss *a,
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sizeof(struct ieee80211_meshconf_ie) - 2) == 0;
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}
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static int cmp_bss(struct cfg80211_bss *a,
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struct cfg80211_bss *b)
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static int cmp_bss_core(struct cfg80211_bss *a,
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struct cfg80211_bss *b)
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{
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int r;
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@ -378,7 +378,15 @@ static int cmp_bss(struct cfg80211_bss *a,
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b->len_information_elements);
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}
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r = memcmp(a->bssid, b->bssid, ETH_ALEN);
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return memcmp(a->bssid, b->bssid, ETH_ALEN);
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}
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static int cmp_bss(struct cfg80211_bss *a,
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struct cfg80211_bss *b)
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{
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int r;
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r = cmp_bss_core(a, b);
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if (r)
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return r;
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@ -389,6 +397,52 @@ static int cmp_bss(struct cfg80211_bss *a,
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b->len_information_elements);
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}
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static int cmp_hidden_bss(struct cfg80211_bss *a,
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struct cfg80211_bss *b)
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{
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const u8 *ie1;
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const u8 *ie2;
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int i;
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int r;
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r = cmp_bss_core(a, b);
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if (r)
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return r;
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ie1 = cfg80211_find_ie(WLAN_EID_SSID,
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a->information_elements,
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a->len_information_elements);
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ie2 = cfg80211_find_ie(WLAN_EID_SSID,
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b->information_elements,
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b->len_information_elements);
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/* Key comparator must use same algorithm in any rb-tree
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* search function (order is important), otherwise ordering
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* of items in the tree is broken and search gives incorrect
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* results. This code uses same order as cmp_ies() does. */
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/* sort missing IE before (left of) present IE */
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if (!ie1)
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return -1;
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if (!ie2)
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return 1;
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/* zero-size SSID is used as an indication of the hidden bss */
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if (!ie2[1])
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return 0;
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/* sort by length first, then by contents */
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if (ie1[1] != ie2[1])
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return ie2[1] - ie1[1];
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/* zeroed SSID ie is another indication of a hidden bss */
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for (i = 0; i < ie2[1]; i++)
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if (ie2[i + 2])
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return -1;
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return 0;
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}
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struct cfg80211_bss *cfg80211_get_bss(struct wiphy *wiphy,
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struct ieee80211_channel *channel,
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const u8 *bssid,
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@ -504,6 +558,48 @@ rb_find_bss(struct cfg80211_registered_device *dev,
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return NULL;
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}
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static struct cfg80211_internal_bss *
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rb_find_hidden_bss(struct cfg80211_registered_device *dev,
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struct cfg80211_internal_bss *res)
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{
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struct rb_node *n = dev->bss_tree.rb_node;
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struct cfg80211_internal_bss *bss;
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int r;
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while (n) {
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bss = rb_entry(n, struct cfg80211_internal_bss, rbn);
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r = cmp_hidden_bss(&res->pub, &bss->pub);
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if (r == 0)
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return bss;
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else if (r < 0)
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n = n->rb_left;
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else
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n = n->rb_right;
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}
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return NULL;
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}
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static void
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copy_hidden_ies(struct cfg80211_internal_bss *res,
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struct cfg80211_internal_bss *hidden)
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{
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if (unlikely(res->pub.beacon_ies))
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return;
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if (WARN_ON(!hidden->pub.beacon_ies))
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return;
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res->pub.beacon_ies = kmalloc(hidden->pub.len_beacon_ies, GFP_ATOMIC);
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if (unlikely(!res->pub.beacon_ies))
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return;
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res->beacon_ies_allocated = true;
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res->pub.len_beacon_ies = hidden->pub.len_beacon_ies;
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memcpy(res->pub.beacon_ies, hidden->pub.beacon_ies,
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res->pub.len_beacon_ies);
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}
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static struct cfg80211_internal_bss *
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cfg80211_bss_update(struct cfg80211_registered_device *dev,
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struct cfg80211_internal_bss *res)
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@ -607,6 +703,21 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
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kref_put(&res->ref, bss_release);
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} else {
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struct cfg80211_internal_bss *hidden;
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/* First check if the beacon is a probe response from
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* a hidden bss. If so, copy beacon ies (with nullified
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* ssid) into the probe response bss entry (with real ssid).
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* It is required basically for PSM implementation
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* (probe responses do not contain tim ie) */
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/* TODO: The code is not trying to update existing probe
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* response bss entries when beacon ies are
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* getting changed. */
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hidden = rb_find_hidden_bss(dev, res);
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if (hidden)
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copy_hidden_ies(res, hidden);
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/* this "consumes" the reference */
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list_add_tail(&res->list, &dev->bss_list);
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rb_insert_bss(dev, res);
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