hostapd: Basic channel check for CHAN_SWITCH parameters

Implement channel sanity check for the CHAN_SWITCH command. Verify
provided values for bandwidth, frequencies, and secondary channel
offset. Reject requested channel switch operation if basic constraints
on frequencies and bandwidth are not fulfilled.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>

diff --git a/hostapd/ctrl_iface.c b/hostapd/ctrl_iface.c
index aaf00c2db301f29835aa8ec07f4432f0bd52124a..f35f87edc25c9d4e2837d276a951c07b4ddb0f5f 100644 (file)
--- a/hostapd/ctrl_iface.c
+++ b/hostapd/ctrl_iface.c
@@ -2432,6 +2432,96 @@ static int hostapd_ctrl_get_pmk(struct hostapd_data *hapd, const char *cmd,
 #endif /* CONFIG_TESTING_OPTIONS */
 
 
+static int hostapd_ctrl_check_freq_params(struct hostapd_freq_params *params)
+{
+       switch (params->bandwidth) {
+       case 0:
+               /* bandwidth not specified: use 20 MHz by default */
+               /* fall-through */
+       case 20:
+               if (params->center_freq1 &&
+                   params->center_freq1 != params->freq)
+                       return -1;
+
+               if (params->center_freq2 || params->sec_channel_offset)
+                       return -1;
+               break;
+       case 40:
+               if (params->center_freq2 || !params->sec_channel_offset)
+                       return -1;
+
+               if (!params->center_freq1)
+                       break;
+               switch (params->sec_channel_offset) {
+               case 1:
+                       if (params->freq + 10 != params->center_freq1)
+                               return -1;
+                       break;
+               case -1:
+                       if (params->freq - 10 != params->center_freq1)
+                               return -1;
+                       break;
+               default:
+                       return -1;
+               }
+               break;
+       case 80:
+               if (!params->center_freq1 || !params->sec_channel_offset)
+                       return 1;
+
+               switch (params->sec_channel_offset) {
+               case 1:
+                       if (params->freq - 10 != params->center_freq1 &&
+                           params->freq + 30 != params->center_freq1)
+                               return 1;
+                       break;
+               case -1:
+                       if (params->freq + 10 != params->center_freq1 &&
+                           params->freq - 30 != params->center_freq1)
+                               return -1;
+                       break;
+               default:
+                       return -1;
+               }
+
+               /* Adjacent and overlapped are not allowed for 80+80 */
+               if (params->center_freq2 &&
+                   params->center_freq1 - params->center_freq2 <= 80 &&
+                   params->center_freq2 - params->center_freq1 <= 80)
+                       return 1;
+               break;
+       case 160:
+               if (!params->center_freq1 || params->center_freq2 ||
+                   !params->sec_channel_offset)
+                       return -1;
+
+               switch (params->sec_channel_offset) {
+               case 1:
+                       if (params->freq + 70 != params->center_freq1 &&
+                           params->freq + 30 != params->center_freq1 &&
+                           params->freq - 10 != params->center_freq1 &&
+                           params->freq - 50 != params->center_freq1)
+                               return -1;
+                       break;
+               case -1:
+                       if (params->freq + 50 != params->center_freq1 &&
+                           params->freq + 10 != params->center_freq1 &&
+                           params->freq - 30 != params->center_freq1 &&
+                           params->freq - 70 != params->center_freq1)
+                               return -1;
+                       break;
+               default:
+                       return -1;
+               }
+               break;
+       default:
+               return -1;
+       }
+
+       return 0;
+}
+
+
 static int hostapd_ctrl_iface_chan_switch(struct hostapd_iface *iface,
                                          char *pos)
 {
@@ -2444,6 +2534,13 @@ static int hostapd_ctrl_iface_chan_switch(struct hostapd_iface *iface,
        if (ret)
                return ret;
 
+       ret = hostapd_ctrl_check_freq_params(&settings.freq_params);
+       if (ret) {
+               wpa_printf(MSG_INFO,
+                          "chanswitch: invalid frequency settings provided");
+               return ret;
+       }
+
        for (i = 0; i < iface->num_bss; i++) {
 
                /* Save CHAN_SWITCH VHT config */