In order to reconstruct frame for MBSSID feature, per the description of
the Reduced Neighbor Report(RNR) element about MLD parameters subfield in
section 9.4.2.170 of Draft P802.11be_D2.0, the RNR element is modified:
1\ If the reported AP is affiliated with the same MLD of the reporting AP,
the TBTT information is skipped;
2\ If the reported AP is affiliated with the same MLD of the nontransmitted
BSSID, the TBTT information is copied and the MLD ID is changed to 0.
Signed-off-by: Paul Zhang <quic_paulz@xxxxxxxxxxx>
---
include/linux/ieee80211.h | 9 +++
net/wireless/scan.c | 159 ++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 162 insertions(+), 6 deletions(-)
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 559b6c6..0e547b5 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -3996,6 +3996,15 @@ static inline bool for_each_element_completed(const struct element *element,
#define IEEE80211_TBTT_INFO_OFFSET_BSSID_BSS_PARAM 9
#define IEEE80211_TBTT_INFO_OFFSET_BSSID_SSSID_BSS_PARAM 13
+/*
+ * TBTT Information field, based on Draft P802.11be_D2.0
+ * section 9.4.2.170.2
+ */
+#define IEEE80211_TBTT_INFO_BSSID_SSID_BSS_PARAM_PSD 13
+#define IEEE80211_TBTT_INFO_BSSID_SSID_BSS_PARAM_PSD_MLD_PARAM 16
+/* TBTT information header(2) + Operating class(1) + Channel number(1) */
+#define IEEE80211_NBR_AP_INFO_LEN 4
+
#define IEEE80211_RNR_TBTT_PARAMS_OCT_RECOMMENDED 0x01
#define IEEE80211_RNR_TBTT_PARAMS_SAME_SSID 0x02
#define IEEE80211_RNR_TBTT_PARAMS_MULTI_BSSID 0x04
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index b888522..e50011f 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -268,9 +268,151 @@ bool cfg80211_is_element_inherited(const struct element *elem,
}
EXPORT_SYMBOL(cfg80211_is_element_inherited);
+/**
+ * cfg80211_handle_rnr_ie_for_mbssid() - parse and modify RNR element for MBSSID
+ * feature
+ * @elem: The pointer to RNR element
+ * @bssid_index: BSSID index from MBSSID index element
+ * @pos: The buffer pointer to save the transformed RNR element, caller is
+ * expected to supply a buffer that is at least as big as @elem
+ *
+ * Per the description about Neighbor AP Information field about MLD
+ * parameters subfield in section 9.4.2.170.2 of Draft P802.11be_D2.0.
+ * If the reported AP is affiliated with the same MLD of the reporting AP,
+ * the TBTT information is skipped; If the reported AP is affiliated with
+ * the same MLD of the nontransmitted BSSID, the TBTT information is copied
+ * and the MLD ID is changed to 0.
+ *
+ * Return: Length of the element written to @pos
+ */
+static size_t cfg80211_handle_rnr_ie_for_mbssid(const struct element *elem,
+ u8 bssid_index, u8 *pos)
+{
+ size_t rnr_len;
+ const u8 *rnr, *data, *rnr_end;
+ u8 *rnr_new, *tbtt_info_field;
+ u8 tbtt_type, tbtt_len, tbtt_count;
+ u8 mld_pos, mld_id;
+ u32 i, copy_len;
+ /* The count of TBTT info field whose MLD ID equals to 0 in a neighbor
+ * AP information field.
+ */
+ u32 tbtt_info_field_count;
+ /* The total bytes of TBTT info fields whose MLD ID equals to 0 in
+ * current RNR element.
+ */
+ u32 tbtt_info_field_len = 0;
+
+ rnr_new = pos;
+ rnr = (u8 *)elem;
+ rnr_len = elem->datalen;
+ rnr_end = rnr + rnr_len + 2;
+
+ memcpy(pos, rnr, 2);
+ pos += 2;
+ data = elem->data;
+ while (data + IEEE80211_NBR_AP_INFO_LEN <= rnr_end) {
+ tbtt_type = u8_get_bits(data[0],
+ IEEE80211_AP_INFO_TBTT_HDR_TYPE);
+ tbtt_count = u8_get_bits(data[0],
+ IEEE80211_AP_INFO_TBTT_HDR_COUNT);
+ tbtt_len = data[1];
+
+ copy_len = tbtt_len * (tbtt_count + 1) +
+ IEEE80211_NBR_AP_INFO_LEN;
+ if (data + copy_len > rnr_end)
+ break;
+
+ if (tbtt_len >=
+ IEEE80211_TBTT_INFO_BSSID_SSID_BSS_PARAM_PSD_MLD_PARAM)
+ mld_pos =
+ IEEE80211_TBTT_INFO_BSSID_SSID_BSS_PARAM_PSD;
+ else
+ mld_pos = 0;
+ /* If MLD params do not exist, copy this neighbor AP
+ * information field.
+ * Draft P802.11be_D2.0, tbtt_type value 1, 2 and 3
+ * are reserved.
+ */
+ if (mld_pos == 0 || tbtt_type != 0) {
+ memcpy(pos, data, copy_len);
+ pos += copy_len;
+ data += copy_len;
+ continue;
+ }
+ /* If MLD params exists, copy the 4 bytes fixed field.
+ * tbtt_info_field is used to modify the tbtt_count field later.
+ */
+ memcpy(pos, data, IEEE80211_NBR_AP_INFO_LEN);
+ tbtt_info_field = pos;
+ pos += IEEE80211_NBR_AP_INFO_LEN;
+ data += IEEE80211_NBR_AP_INFO_LEN;
+
+ tbtt_info_field_count = 0;
+ for (i = 0; i < tbtt_count + 1; i++) {
+ mld_id = data[mld_pos];
+ /* Refer to Draft P802.11be_D2.0
+ * 9.4.2.170.2 Neighbor AP Information field about
+ * MLD parameters subfield
+ */
+ if (mld_id == 0) {
+ /* Skip this TBTT information since this
+ * reported AP is affiliated with the same MLD
+ * of the reporting AP who sending the frame
+ * carrying this element.
+ */
+ tbtt_info_field_len += tbtt_len;
+ data += tbtt_len;
+ tbtt_info_field_count++;
+ } else if (mld_id == bssid_index) {
+ /* Copy this TBTT information and change MLD
+ * to 0 as this reported AP is affiliated with
+ * the same MLD of the nontransmitted BSSID.
+ */
+ memcpy(pos, data, tbtt_len);
+ pos[mld_pos] = 0;
+ data += tbtt_len;
+ pos += tbtt_len;
+ } else {
+ /* Just copy this TBTT information */
+ memcpy(pos, data, tbtt_len);
+ data += tbtt_len;
+ pos += tbtt_len;
+ }
+ }
+ if (tbtt_info_field_count == (tbtt_count + 1)) {
+ /* If all the TBTT informations are skipped, then also
+ * revert the 4 bytes fixed field which has been copied.
+ */
+ pos -= IEEE80211_NBR_AP_INFO_LEN;
+ tbtt_info_field_len += IEEE80211_NBR_AP_INFO_LEN;
+ } else {
+ /* Modify the tbtt_count field if some TBTT informations
+ * are skipped.
+ */
+ u8p_replace_bits(&tbtt_info_field[0],
+ tbtt_count - tbtt_info_field_count,
+ IEEE80211_AP_INFO_TBTT_HDR_COUNT);
+ }
+ }
+
+ /* Sanity check if any parsing issue happens */
+ if (data != rnr_end)
+ return 0;
+
+ /* Count the new rnr length.
+ * tbtt_info_field_len saves the total skipped length.
+ */
+ rnr_new[1] = rnr_len - tbtt_info_field_len;
+ if (rnr_new[1] == 0)
+ pos = rnr_new;
+
+ return pos - rnr_new;
+}
+
static size_t cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
const u8 *subelement, size_t subie_len,
- u8 *new_ie, gfp_t gfp)
+ u8 *new_ie, u8 bssid_index, gfp_t gfp)
{
u8 *pos, *tmp;
const u8 *tmp_old, *tmp_new;
@@ -319,10 +461,13 @@ static size_t cfg80211_gen_new_ie(const u8 *ie, size_t ielen,
if (!tmp) {
const struct element *old_elem = (void *)tmp_old;
-
- /* ie in old ie but not in subelement */
- if (cfg80211_is_element_inherited(old_elem,
- non_inherit_elem)) {
+ if (tmp_old[0] == WLAN_EID_REDUCED_NEIGHBOR_REPORT) {
+ pos +=
+ cfg80211_handle_rnr_ie_for_mbssid(old_elem,
+ bssid_index,
+ pos);
+ } else if (cfg80211_is_element_inherited(old_elem,
+ non_inherit_elem)) {
memcpy(pos, tmp_old, tmp_old[1] + 2);
pos += tmp_old[1] + 2;
}
@@ -2112,6 +2257,7 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
u64 seen_indices = 0;
u16 capability;
struct cfg80211_bss *bss;
+ u8 bssid_index;
if (!non_tx_data)
return;
@@ -2178,6 +2324,7 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
non_tx_data->bssid_index = mbssid_index_ie[2];
non_tx_data->max_bssid_indicator = elem->data[0];
+ bssid_index = non_tx_data->bssid_index;
cfg80211_gen_new_bssid(bssid,
non_tx_data->max_bssid_indicator,
@@ -2187,7 +2334,7 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
new_ie_len = cfg80211_gen_new_ie(ie, ielen,
profile,
profile_len, new_ie,
- gfp);
+ bssid_index, gfp);
if (!new_ie_len)
continue;
--
2.7.4
