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fragattacks/src/ap/ieee802_11_ht.c
Jouni Malinen 0acc2c809d HT: More robust 20/40 coex Action frame parsing 
Commit 587d60d2b7 ('Add AP mode support
for HT 20/40 co-ex Action frame') added processing of co-ex report, but
did not include proper bounds checking or IE type checking for the
payload. Furthermore, this was not ready for the possible extensibility
of the 20/40 BSS Coexistence element.

Fix these by checking IE ids for both elements and doing more
apprioriate bounds checking for the element lengths to avoid potentially
reading beyond the frame buffer. Though, the event receive buffer in
both libnl and driver_nl80211_monitor.c is sufficiently large to make it
very unlikely that the maximum read of about 260 bytes beyond the end of
the Action frame would really have any chances of hitting the end of the
memory buffer, so the practical effect of missing bounds checking would
have been possibly accepting an invalid report frame and moving to 20
MHz channel unnecessarily.

Signed-off-by: Jouni Malinen <j@w1.fi>
2014-12-22 21:54:11 +02:00

487 lines
14 KiB
C
Raw Blame History

/*
* hostapd / IEEE 802.11n HT
* Copyright (c) 2002-2009, Jouni Malinen <j@w1.fi>
* Copyright (c) 2007-2008, Intel Corporation
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
*/
#include "utils/includes.h"
#include "utils/common.h"
#include "utils/eloop.h"
#include "common/ieee802_11_defs.h"
#include "hostapd.h"
#include "ap_config.h"
#include "sta_info.h"
#include "beacon.h"
#include "ieee802_11.h"
#include "hw_features.h"
#include "ap_drv_ops.h"
u8 * hostapd_eid_ht_capabilities(struct hostapd_data *hapd, u8 *eid)
{
struct ieee80211_ht_capabilities *cap;
u8 *pos = eid;
if (!hapd->iconf->ieee80211n || !hapd->iface->current_mode ||
hapd->conf->disable_11n)
return eid;
*pos++ = WLAN_EID_HT_CAP;
*pos++ = sizeof(*cap);
cap = (struct ieee80211_ht_capabilities *) pos;
os_memset(cap, 0, sizeof(*cap));
cap->ht_capabilities_info = host_to_le16(hapd->iconf->ht_capab);
cap->a_mpdu_params = hapd->iface->current_mode->a_mpdu_params;
os_memcpy(cap->supported_mcs_set, hapd->iface->current_mode->mcs_set,
16);
/* TODO: ht_extended_capabilities (now fully disabled) */
/* TODO: tx_bf_capability_info (now fully disabled) */
/* TODO: asel_capabilities (now fully disabled) */
pos += sizeof(*cap);
if (hapd->iconf->obss_interval) {
struct ieee80211_obss_scan_parameters *scan_params;
*pos++ = WLAN_EID_OVERLAPPING_BSS_SCAN_PARAMS;
*pos++ = sizeof(*scan_params);
scan_params = (struct ieee80211_obss_scan_parameters *) pos;
os_memset(scan_params, 0, sizeof(*scan_params));
scan_params->width_trigger_scan_interval =
host_to_le16(hapd->iconf->obss_interval);
/* Fill in default values for remaining parameters
* (IEEE Std 802.11-2012, 8.4.2.61 and MIB defval) */
scan_params->scan_passive_dwell =
host_to_le16(20);
scan_params->scan_active_dwell =
host_to_le16(10);
scan_params->scan_passive_total_per_channel =
host_to_le16(200);
scan_params->scan_active_total_per_channel =
host_to_le16(20);
scan_params->channel_transition_delay_factor =
host_to_le16(5);
scan_params->scan_activity_threshold =
host_to_le16(25);
pos += sizeof(*scan_params);
}
return pos;
}
u8 * hostapd_eid_ht_operation(struct hostapd_data *hapd, u8 *eid)
{
struct ieee80211_ht_operation *oper;
u8 *pos = eid;
if (!hapd->iconf->ieee80211n || hapd->conf->disable_11n)
return eid;
*pos++ = WLAN_EID_HT_OPERATION;
*pos++ = sizeof(*oper);
oper = (struct ieee80211_ht_operation *) pos;
os_memset(oper, 0, sizeof(*oper));
oper->primary_chan = hapd->iconf->channel;
oper->operation_mode = host_to_le16(hapd->iface->ht_op_mode);
if (hapd->iconf->secondary_channel == 1)
oper->ht_param |= HT_INFO_HT_PARAM_SECONDARY_CHNL_ABOVE |
HT_INFO_HT_PARAM_STA_CHNL_WIDTH;
if (hapd->iconf->secondary_channel == -1)
oper->ht_param |= HT_INFO_HT_PARAM_SECONDARY_CHNL_BELOW |
HT_INFO_HT_PARAM_STA_CHNL_WIDTH;
pos += sizeof(*oper);
return pos;
}
/*
op_mode
Set to 0 (HT pure) under the followign conditions
- all STAs in the BSS are 20/40 MHz HT in 20/40 MHz BSS or
- all STAs in the BSS are 20 MHz HT in 20 MHz BSS
Set to 1 (HT non-member protection) if there may be non-HT STAs
in both the primary and the secondary channel
Set to 2 if only HT STAs are associated in BSS,
however and at least one 20 MHz HT STA is associated
Set to 3 (HT mixed mode) when one or more non-HT STAs are associated
*/
int hostapd_ht_operation_update(struct hostapd_iface *iface)
{
u16 cur_op_mode, new_op_mode;
int op_mode_changes = 0;
if (!iface->conf->ieee80211n || iface->conf->ht_op_mode_fixed)
return 0;
wpa_printf(MSG_DEBUG, "%s current operation mode=0x%X",
__func__, iface->ht_op_mode);
if (!(iface->ht_op_mode & HT_OPER_OP_MODE_NON_GF_HT_STAS_PRESENT)
&& iface->num_sta_ht_no_gf) {
iface->ht_op_mode |= HT_OPER_OP_MODE_NON_GF_HT_STAS_PRESENT;
op_mode_changes++;
} else if ((iface->ht_op_mode &
HT_OPER_OP_MODE_NON_GF_HT_STAS_PRESENT) &&
iface->num_sta_ht_no_gf == 0) {
iface->ht_op_mode &= ~HT_OPER_OP_MODE_NON_GF_HT_STAS_PRESENT;
op_mode_changes++;
}
if (!(iface->ht_op_mode & HT_OPER_OP_MODE_OBSS_NON_HT_STAS_PRESENT) &&
(iface->num_sta_no_ht || iface->olbc_ht)) {
iface->ht_op_mode |= HT_OPER_OP_MODE_OBSS_NON_HT_STAS_PRESENT;
op_mode_changes++;
} else if ((iface->ht_op_mode &
HT_OPER_OP_MODE_OBSS_NON_HT_STAS_PRESENT) &&
(iface->num_sta_no_ht == 0 && !iface->olbc_ht)) {
iface->ht_op_mode &= ~HT_OPER_OP_MODE_OBSS_NON_HT_STAS_PRESENT;
op_mode_changes++;
}
if (iface->num_sta_no_ht)
new_op_mode = HT_PROT_NON_HT_MIXED;
else if (iface->conf->secondary_channel && iface->num_sta_ht_20mhz)
new_op_mode = HT_PROT_20MHZ_PROTECTION;
else if (iface->olbc_ht)
new_op_mode = HT_PROT_NONMEMBER_PROTECTION;
else
new_op_mode = HT_PROT_NO_PROTECTION;
cur_op_mode = iface->ht_op_mode & HT_OPER_OP_MODE_HT_PROT_MASK;
if (cur_op_mode != new_op_mode) {
iface->ht_op_mode &= ~HT_OPER_OP_MODE_HT_PROT_MASK;
iface->ht_op_mode |= new_op_mode;
op_mode_changes++;
}
wpa_printf(MSG_DEBUG, "%s new operation mode=0x%X changes=%d",
__func__, iface->ht_op_mode, op_mode_changes);
return op_mode_changes;
}
static int is_40_allowed(struct hostapd_iface *iface, int channel)
{
int pri_freq, sec_freq;
int affected_start, affected_end;
int pri = 2407 + 5 * channel;
if (iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
return 1;
pri_freq = hostapd_hw_get_freq(iface->bss[0], iface->conf->channel);
if (iface->conf->secondary_channel > 0)
sec_freq = pri_freq + 20;
else
sec_freq = pri_freq - 20;
affected_start = (pri_freq + sec_freq) / 2 - 25;
affected_end = (pri_freq + sec_freq) / 2 + 25;
if ((pri < affected_start || pri > affected_end))
return 1; /* not within affected channel range */
wpa_printf(MSG_ERROR, "40 MHz affected channel range: [%d,%d] MHz",
affected_start, affected_end);
wpa_printf(MSG_ERROR, "Neighboring BSS: freq=%d", pri);
return 0;
}
void hostapd_2040_coex_action(struct hostapd_data *hapd,
const struct ieee80211_mgmt *mgmt, size_t len)
{
struct hostapd_iface *iface = hapd->iface;
struct ieee80211_2040_bss_coex_ie *bc_ie;
struct ieee80211_2040_intol_chan_report *ic_report;
int is_ht_allowed = 1;
int i;
const u8 *start = (const u8 *) mgmt;
const u8 *data = start + IEEE80211_HDRLEN + 2;
hostapd_logger(hapd, mgmt->sa, HOSTAPD_MODULE_IEEE80211,
HOSTAPD_LEVEL_DEBUG, "hostapd_public_action - action=%d",
mgmt->u.action.u.public_action.action);
if (!(iface->conf->ht_capab & HT_CAP_INFO_SUPP_CHANNEL_WIDTH_SET))
return;
if (len < IEEE80211_HDRLEN + 2 + sizeof(*bc_ie))
return;
bc_ie = (struct ieee80211_2040_bss_coex_ie *) data;
if (bc_ie->element_id != WLAN_EID_20_40_BSS_COEXISTENCE ||
bc_ie->length < 1) {
wpa_printf(MSG_DEBUG, "Unexpected IE (%u,%u) in coex report",
bc_ie->element_id, bc_ie->length);
return;
}
if (len < IEEE80211_HDRLEN + 2 + 2 + bc_ie->length)
return;
data += 2 + bc_ie->length;
wpa_printf(MSG_DEBUG, "20/40 BSS Coexistence Information field: 0x%x",
bc_ie->coex_param);
if (bc_ie->coex_param & WLAN_20_40_BSS_COEX_20MHZ_WIDTH_REQ) {
hostapd_logger(hapd, mgmt->sa,
HOSTAPD_MODULE_IEEE80211,
HOSTAPD_LEVEL_DEBUG,
"20 MHz BSS width request bit is set in BSS coexistence information field");
is_ht_allowed = 0;
}
if (bc_ie->coex_param & WLAN_20_40_BSS_COEX_40MHZ_INTOL) {
hostapd_logger(hapd, mgmt->sa,
HOSTAPD_MODULE_IEEE80211,
HOSTAPD_LEVEL_DEBUG,
"40 MHz intolerant bit is set in BSS coexistence information field");
is_ht_allowed = 0;
}
if (start + len - data >= 3 &&
data[0] == WLAN_EID_20_40_BSS_INTOLERANT && data[1] >= 1) {
u8 ielen = data[1];
if (ielen > start + len - data - 2)
return;
ic_report = (struct ieee80211_2040_intol_chan_report *) data;
wpa_printf(MSG_DEBUG,
"20/40 BSS Intolerant Channel Report: Operating Class %u",
ic_report->op_class);
/* Go through the channel report to find any BSS there in the
* affected channel range */
for (i = 0; i < ielen - 1; i++) {
u8 chan = ic_report->variable[i];
if (is_40_allowed(iface, chan))
continue;
hostapd_logger(hapd, mgmt->sa,
HOSTAPD_MODULE_IEEE80211,
HOSTAPD_LEVEL_DEBUG,
"20_40_INTOLERANT channel %d reported",
chan);
is_ht_allowed = 0;
}
}
wpa_printf(MSG_DEBUG, "is_ht_allowed=%d num_sta_ht40_intolerant=%d",
is_ht_allowed, iface->num_sta_ht40_intolerant);
if (!is_ht_allowed &&
(iface->drv_flags & WPA_DRIVER_FLAGS_HT_2040_COEX)) {
if (iface->conf->secondary_channel) {
hostapd_logger(hapd, mgmt->sa,
HOSTAPD_MODULE_IEEE80211,
HOSTAPD_LEVEL_INFO,
"Switching to 20 MHz operation");
iface->conf->secondary_channel = 0;
ieee802_11_set_beacons(iface);
}
if (!iface->num_sta_ht40_intolerant) {
unsigned int delay_time;
delay_time = OVERLAPPING_BSS_TRANS_DELAY_FACTOR *
iface->conf->obss_interval;
eloop_cancel_timeout(ap_ht2040_timeout, hapd->iface,
NULL);
eloop_register_timeout(delay_time, 0, ap_ht2040_timeout,
hapd->iface, NULL);
wpa_printf(MSG_DEBUG,
"Reschedule HT 20/40 timeout to occur in %u seconds",
delay_time);
}
}
}
u16 copy_sta_ht_capab(struct hostapd_data *hapd, struct sta_info *sta,
const u8 *ht_capab, size_t ht_capab_len)
{
/* Disable HT caps for STAs associated to no-HT BSSes. */
if (!ht_capab ||
ht_capab_len < sizeof(struct ieee80211_ht_capabilities) ||
hapd->conf->disable_11n) {
sta->flags &= ~WLAN_STA_HT;
os_free(sta->ht_capabilities);
sta->ht_capabilities = NULL;
return WLAN_STATUS_SUCCESS;
}
if (sta->ht_capabilities == NULL) {
sta->ht_capabilities =
os_zalloc(sizeof(struct ieee80211_ht_capabilities));
if (sta->ht_capabilities == NULL)
return WLAN_STATUS_UNSPECIFIED_FAILURE;
}
sta->flags |= WLAN_STA_HT;
os_memcpy(sta->ht_capabilities, ht_capab,
sizeof(struct ieee80211_ht_capabilities));
return WLAN_STATUS_SUCCESS;
}
void ht40_intolerant_add(struct hostapd_iface *iface, struct sta_info *sta)
{
if (iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G)
return;
wpa_printf(MSG_INFO, "HT: Forty MHz Intolerant is set by STA " MACSTR
" in Association Request", MAC2STR(sta->addr));
if (sta->ht40_intolerant_set)
return;
sta->ht40_intolerant_set = 1;
iface->num_sta_ht40_intolerant++;
eloop_cancel_timeout(ap_ht2040_timeout, iface, NULL);
if (iface->conf->secondary_channel &&
(iface->drv_flags & WPA_DRIVER_FLAGS_HT_2040_COEX)) {
iface->conf->secondary_channel = 0;
ieee802_11_set_beacons(iface);
}
}
void ht40_intolerant_remove(struct hostapd_iface *iface, struct sta_info *sta)
{
if (!sta->ht40_intolerant_set)
return;
sta->ht40_intolerant_set = 0;
iface->num_sta_ht40_intolerant--;
if (iface->num_sta_ht40_intolerant == 0 &&
(iface->conf->ht_capab & HT_CAP_INFO_SUPP_CHANNEL_WIDTH_SET) &&
(iface->drv_flags & WPA_DRIVER_FLAGS_HT_2040_COEX)) {
unsigned int delay_time = OVERLAPPING_BSS_TRANS_DELAY_FACTOR *
iface->conf->obss_interval;
wpa_printf(MSG_DEBUG,
"HT: Start 20->40 MHz transition timer (%d seconds)",
delay_time);
eloop_cancel_timeout(ap_ht2040_timeout, iface, NULL);
eloop_register_timeout(delay_time, 0, ap_ht2040_timeout,
iface, NULL);
}
}
static void update_sta_ht(struct hostapd_data *hapd, struct sta_info *sta)
{
u16 ht_capab;
ht_capab = le_to_host16(sta->ht_capabilities->ht_capabilities_info);
wpa_printf(MSG_DEBUG, "HT: STA " MACSTR " HT Capabilities Info: "
"0x%04x", MAC2STR(sta->addr), ht_capab);
if ((ht_capab & HT_CAP_INFO_GREEN_FIELD) == 0) {
if (!sta->no_ht_gf_set) {
sta->no_ht_gf_set = 1;
hapd->iface->num_sta_ht_no_gf++;
}
wpa_printf(MSG_DEBUG, "%s STA " MACSTR " - no greenfield, num "
"of non-gf stations %d",
__func__, MAC2STR(sta->addr),
hapd->iface->num_sta_ht_no_gf);
}
if ((ht_capab & HT_CAP_INFO_SUPP_CHANNEL_WIDTH_SET) == 0) {
if (!sta->ht_20mhz_set) {
sta->ht_20mhz_set = 1;
hapd->iface->num_sta_ht_20mhz++;
}
wpa_printf(MSG_DEBUG, "%s STA " MACSTR " - 20 MHz HT, num of "
"20MHz HT STAs %d",
__func__, MAC2STR(sta->addr),
hapd->iface->num_sta_ht_20mhz);
}
if (ht_capab & HT_CAP_INFO_40MHZ_INTOLERANT)
ht40_intolerant_add(hapd->iface, sta);
}
static void update_sta_no_ht(struct hostapd_data *hapd, struct sta_info *sta)
{
if (!sta->no_ht_set) {
sta->no_ht_set = 1;
hapd->iface->num_sta_no_ht++;
}
if (hapd->iconf->ieee80211n) {
wpa_printf(MSG_DEBUG, "%s STA " MACSTR " - no HT, num of "
"non-HT stations %d",
__func__, MAC2STR(sta->addr),
hapd->iface->num_sta_no_ht);
}
}
void update_ht_state(struct hostapd_data *hapd, struct sta_info *sta)
{
if ((sta->flags & WLAN_STA_HT) && sta->ht_capabilities)
update_sta_ht(hapd, sta);
else
update_sta_no_ht(hapd, sta);
if (hostapd_ht_operation_update(hapd->iface) > 0)
ieee802_11_set_beacons(hapd->iface);
}
void hostapd_get_ht_capab(struct hostapd_data *hapd,
struct ieee80211_ht_capabilities *ht_cap,
struct ieee80211_ht_capabilities *neg_ht_cap)
{
u16 cap;
if (ht_cap == NULL)
return;
os_memcpy(neg_ht_cap, ht_cap, sizeof(*neg_ht_cap));
cap = le_to_host16(neg_ht_cap->ht_capabilities_info);
/*
* Mask out HT features we don't support, but don't overwrite
* non-symmetric features like STBC and SMPS. Just because
* we're not in dynamic SMPS mode the STA might still be.
*/
cap &= (hapd->iconf->ht_capab | HT_CAP_INFO_RX_STBC_MASK |
HT_CAP_INFO_TX_STBC | HT_CAP_INFO_SMPS_MASK);
/*
* STBC needs to be handled specially
* if we don't support RX STBC, mask out TX STBC in the STA's HT caps
* if we don't support TX STBC, mask out RX STBC in the STA's HT caps
*/
if (!(hapd->iconf->ht_capab & HT_CAP_INFO_RX_STBC_MASK))
cap &= ~HT_CAP_INFO_TX_STBC;
if (!(hapd->iconf->ht_capab & HT_CAP_INFO_TX_STBC))
cap &= ~HT_CAP_INFO_RX_STBC_MASK;
neg_ht_cap->ht_capabilities_info = host_to_le16(cap);
}
void ap_ht2040_timeout(void *eloop_data, void *user_data)
{
struct hostapd_iface *iface = eloop_data;
wpa_printf(MSG_INFO, "Switching to 40 MHz operation");
iface->conf->secondary_channel = iface->secondary_ch;
ieee802_11_set_beacons(iface);
}
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