cfg80211: support profile split between elements

Since an element is limited to 255 octets, a profile may be split
split to several elements. Support the split as defined in the 11ax
draft 3. Detect legacy split and print a net-rate limited warning,
since there is no ROI in supporting this probably non-existent
split.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 103 insertions, 6 deletions

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index bda9114ded77..878c867f3f7d 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1456,6 +1456,78 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
         return &res->pub;
 }
 
+static const struct element
+*cfg80211_get_profile_continuation(const u8 *ie, size_t ielen,
+                                   const struct element *mbssid_elem,
+                                   const struct element *sub_elem)
+{
+        const u8 *mbssid_end = mbssid_elem->data + mbssid_elem->datalen;
+        const struct element *next_mbssid;
+        const struct element *next_sub;
+
+        next_mbssid = cfg80211_find_elem(WLAN_EID_MULTIPLE_BSSID,
+                                         mbssid_end,
+                                         ielen - (mbssid_end - ie));
+
+        /*
+         * If is is not the last subelement in current MBSSID IE or there isn't
+         * a next MBSSID IE - profile is complete.
+        */
+        if ((sub_elem->data + sub_elem->datalen < mbssid_end - 1) ||
+            !next_mbssid)
+                return NULL;
+
+        /* For any length error, just return NULL */
+
+        if (next_mbssid->datalen < 4)
+                return NULL;
+
+        next_sub = (void *)&next_mbssid->data[1];
+
+        if (next_mbssid->data + next_mbssid->datalen <
+            next_sub->data + next_sub->datalen)
+                return NULL;
+
+        if (next_sub->id != 0 || next_sub->datalen < 2)
+                return NULL;
+
+        /*
+         * Check if the first element in the next sub element is a start
+         * of a new profile
+         */
+        return next_sub->data[0] == WLAN_EID_NON_TX_BSSID_CAP ?
+               NULL : next_mbssid;
+}
+
+size_t cfg80211_merge_profile(const u8 *ie, size_t ielen,
+                              const struct element *mbssid_elem,
+                              const struct element *sub_elem,
+                              u8 **merged_ie, size_t max_copy_len)
+{
+        size_t copied_len = sub_elem->datalen;
+        const struct element *next_mbssid;
+
+        if (sub_elem->datalen > max_copy_len)
+                return 0;
+
+        memcpy(*merged_ie, sub_elem->data, sub_elem->datalen);
+
+        while ((next_mbssid = cfg80211_get_profile_continuation(ie, ielen,
+                                                                mbssid_elem,
+                                                                sub_elem))) {
+                const struct element *next_sub = (void *)&next_mbssid->data[1];
+
+                if (copied_len + next_sub->datalen > max_copy_len)
+                        break;
+                memcpy(*merged_ie + copied_len, next_sub->data,
+                       next_sub->datalen);
+                copied_len += next_sub->datalen;
+        }
+
+        return copied_len;
+}
+EXPORT_SYMBOL(cfg80211_merge_profile);
+
 static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
                                        struct cfg80211_inform_bss *data,
                                        enum cfg80211_bss_frame_type ftype,
@@ -1469,7 +1541,8 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
         const struct element *elem, *sub;
         size_t new_ie_len;
         u8 new_bssid[ETH_ALEN];
-        u8 *new_ie;
+        u8 *new_ie, *profile;
+        u64 seen_indices = 0;
         u16 capability;
         struct cfg80211_bss *bss;
 
@@ -1487,10 +1560,16 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
         if (!new_ie)
                 return;
 
+        profile = kmalloc(ielen, gfp);
+        if (!profile)
+                goto out;
+
         for_each_element_id(elem, WLAN_EID_MULTIPLE_BSSID, ie, ielen) {
                 if (elem->datalen < 4)
                         continue;
                 for_each_element(sub, elem->data + 1, elem->datalen - 1) {
+                        u8 profile_len;
+
                         if (sub->id != 0 || sub->datalen < 4) {
                                 /* not a valid BSS profile */
                                 continue;
@@ -1505,16 +1584,31 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
                                 continue;
                         }
 
+                        memset(profile, 0, ielen);
+                        profile_len = cfg80211_merge_profile(ie, ielen,
+                                                             elem,
+                                                             sub,
+                                                             &profile,
+                                                             ielen);
+
                         /* found a Nontransmitted BSSID Profile */
                         mbssid_index_ie = cfg80211_find_ie
                                 (WLAN_EID_MULTI_BSSID_IDX,
-                                 sub->data, sub->datalen);
+                                 profile, profile_len);
                         if (!mbssid_index_ie || mbssid_index_ie[1] < 1 ||
-                            mbssid_index_ie[2] == 0) {
+                            mbssid_index_ie[2] == 0 ||
+                            mbssid_index_ie[2] > 46) {
                                 /* No valid Multiple BSSID-Index element */
                                 continue;
                         }
 
+                        if (seen_indices & BIT(mbssid_index_ie[2]))
+                                /* We don't support legacy split of a profile */
+                                net_dbg_ratelimited("Partial info for BSSID index %d\n",
+                                                    mbssid_index_ie[2]);
+
+                        seen_indices |= BIT(mbssid_index_ie[2]);
+
                         non_tx_data->bssid_index = mbssid_index_ie[2];
                         non_tx_data->max_bssid_indicator = elem->data[0];
 
@@ -1523,13 +1617,14 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
                                                non_tx_data->bssid_index,
                                                new_bssid);
                         memset(new_ie, 0, IEEE80211_MAX_DATA_LEN);
-                        new_ie_len = cfg80211_gen_new_ie(ie, ielen, sub->data,
-                                                         sub->datalen, new_ie,
+                        new_ie_len = cfg80211_gen_new_ie(ie, ielen,
+                                                         profile,
+                                                         profile_len, new_ie,
                                                          gfp);
                         if (!new_ie_len)
                                 continue;
 
-                        capability = get_unaligned_le16(sub->data + 2);
+                        capability = get_unaligned_le16(profile + 2);
                         bss = cfg80211_inform_single_bss_data(wiphy, data,
                                                               ftype,
                                                               new_bssid, tsf,
@@ -1545,7 +1640,9 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
                 }
         }
 
+out:
         kfree(new_ie);
+        kfree(profile);
 }
 
 struct cfg80211_bss *