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      1 /*
      2  * Operating Channel Validation (OCV)
      3  * Copyright (c) 2018, Mathy Vanhoef
      4  *
      5  * This software may be distributed under the terms of the BSD license.
      6  * See README for more details.
      7  */
      8 
      9 #include "utils/includes.h"
     10 #include "utils/common.h"
     11 #include "drivers/driver.h"
     12 #include "common/ieee802_11_common.h"
     13 #include "ocv.h"
     14 
     15 /**
     16  * Caller of OCV functionality may use various debug output functions, so store
     17  * the error here and let the caller use an appropriate debug output function.
     18  */
     19 char ocv_errorstr[256];
     20 
     21 
     22 int ocv_derive_all_parameters(struct oci_info *oci)
     23 {
     24 	const struct oper_class_map *op_class_map;
     25 
     26 	oci->freq = ieee80211_chan_to_freq(NULL, oci->op_class, oci->channel);
     27 	if (oci->freq < 0) {
     28 		wpa_printf(MSG_INFO,
     29 			   "Error interpreting OCI: unrecognized opclass/channel pair (%d/%d)",
     30 			   oci->op_class, oci->channel);
     31 		return -1;
     32 	}
     33 
     34 	op_class_map = get_oper_class(NULL, oci->op_class);
     35 	if (!op_class_map) {
     36 		wpa_printf(MSG_INFO,
     37 			   "Error interpreting OCI: Unrecognized opclass (%d)",
     38 			   oci->op_class);
     39 		return -1;
     40 	}
     41 
     42 	oci->chanwidth = oper_class_bw_to_int(op_class_map);
     43 	oci->sec_channel = 0;
     44 	if (op_class_map->bw == BW40PLUS)
     45 		oci->sec_channel = 1;
     46 	else if (op_class_map->bw == BW40MINUS)
     47 		oci->sec_channel = -1;
     48 	else if (op_class_map->bw == BW40)
     49 		oci->sec_channel = (((oci->channel - 1) / 4) % 2) ? -1 : 1;
     50 
     51 	return 0;
     52 }
     53 
     54 
     55 int ocv_insert_oci(struct wpa_channel_info *ci, u8 **argpos)
     56 {
     57 	u8 op_class, channel;
     58 	u8 *pos = *argpos;
     59 
     60 	if (ieee80211_chaninfo_to_channel(ci->frequency, ci->chanwidth,
     61 					  ci->sec_channel,
     62 					  &op_class, &channel) < 0) {
     63 		wpa_printf(MSG_WARNING,
     64 			   "Cannot determine operating class and channel for OCI element");
     65 		return -1;
     66 	}
     67 
     68 	*pos++ = op_class;
     69 	*pos++ = channel;
     70 	*pos++ = ci->seg1_idx;
     71 
     72 	*argpos = pos;
     73 	return 0;
     74 }
     75 
     76 
     77 int ocv_insert_oci_kde(struct wpa_channel_info *ci, u8 **argpos)
     78 {
     79 	u8 *pos = *argpos;
     80 
     81 	*pos++ = WLAN_EID_VENDOR_SPECIFIC;
     82 	*pos++ = RSN_SELECTOR_LEN + 3;
     83 	RSN_SELECTOR_PUT(pos, RSN_KEY_DATA_OCI);
     84 	pos += RSN_SELECTOR_LEN;
     85 
     86 	*argpos = pos;
     87 	return ocv_insert_oci(ci, argpos);
     88 }
     89 
     90 
     91 int ocv_insert_extended_oci(struct wpa_channel_info *ci, u8 *pos)
     92 {
     93 	*pos++ = WLAN_EID_EXTENSION;
     94 	*pos++ = 1 + OCV_OCI_LEN;
     95 	*pos++ = WLAN_EID_EXT_OCV_OCI;
     96 	return ocv_insert_oci(ci, &pos);
     97 }
     98 
     99 
    100 enum oci_verify_result
    101 ocv_verify_tx_params(const u8 *oci_ie, size_t oci_ie_len,
    102 		     struct wpa_channel_info *ci, int tx_chanwidth,
    103 		     int tx_seg1_idx)
    104 {
    105 	struct oci_info oci;
    106 
    107 	if (!oci_ie) {
    108 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    109 			    "did not receive mandatory OCI");
    110 		return OCI_NOT_FOUND;
    111 	}
    112 
    113 	if (oci_ie_len != 3) {
    114 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    115 			    "received OCI of unexpected length (%d)",
    116 			    (int) oci_ie_len);
    117 		return OCI_INVALID_LENGTH;
    118 	}
    119 
    120 	os_memset(&oci, 0, sizeof(oci));
    121 	oci.op_class = oci_ie[0];
    122 	oci.channel = oci_ie[1];
    123 	oci.seg1_idx = oci_ie[2];
    124 	if (ocv_derive_all_parameters(&oci) != 0) {
    125 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    126 			    "unable to interpret received OCI");
    127 		return OCI_PARSE_ERROR;
    128 	}
    129 
    130 	/* Primary frequency used to send frames to STA must match the STA's */
    131 	if ((int) ci->frequency != oci.freq) {
    132 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    133 			    "primary channel mismatch in received OCI (we use %d but receiver is using %d)",
    134 			    ci->frequency, oci.freq);
    135 		return OCI_PRIMARY_FREQ_MISMATCH;
    136 	}
    137 
    138 	/* We shouldn't transmit with a higher bandwidth than the STA supports
    139 	 */
    140 	if (tx_chanwidth > oci.chanwidth) {
    141 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    142 			    "channel bandwidth mismatch in received OCI (we use %d but receiver only supports %d)",
    143 			    tx_chanwidth, oci.chanwidth);
    144 		return OCI_CHANNEL_WIDTH_MISMATCH;
    145 	}
    146 
    147 	/*
    148 	 * Secondary channel only needs be checked for 40 MHz in the 2.4 GHz
    149 	 * band. In the 5 GHz band it's verified through the primary frequency.
    150 	 * Note that the field ci->sec_channel is only filled in when we use
    151 	 * 40 MHz.
    152 	 */
    153 	if (tx_chanwidth == 40 && ci->frequency < 2500 &&
    154 	    ci->sec_channel != oci.sec_channel) {
    155 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    156 			    "secondary channel mismatch in received OCI (we use %d but receiver is using %d)",
    157 			    ci->sec_channel, oci.sec_channel);
    158 		return OCI_SECONDARY_FREQ_MISMATCH;
    159 	}
    160 
    161 	/*
    162 	 * When using an 80+80 MHz channel to transmit, verify that we use
    163 	 * the same segments as the receiver by comparing frequency segment 1.
    164 	 */
    165 	if (ci->chanwidth == CHAN_WIDTH_80P80 &&
    166 	    tx_seg1_idx != oci.seg1_idx) {
    167 		os_snprintf(ocv_errorstr, sizeof(ocv_errorstr),
    168 			    "frequency segment 1 mismatch in received OCI (we use %d but receiver is using %d)",
    169 			    tx_seg1_idx, oci.seg1_idx);
    170 		return OCI_SEG_1_INDEX_MISMATCH;
    171 	}
    172 
    173 	return OCI_SUCCESS;
    174 }
    175