Use 64-bit TX/RX byte counters for statistics

If the driver supports 64-bit TX/RX byte counters, use them directly.
The old 32-bit counter extension is maintained for backwards
compatibility with older drivers.

For nl80211 driver interface, the newer NL80211_STA_INFO_RX_BYTES64 and
NL80211_STA_INFO_TX_BYTES64 attributes are used when available. This
resolves the race vulnerable 32-bit value wrap/overflow. Rework RADIUS
accounting to use these for Acct-Input-Octets, Acct-Input-Gigawords,
Acct-Output-Octets, and Acct-Output-Gigawords, these values are often
used for billing purposes.

Signed-off-by: Nick Lowe <nick.lowe@lugatech.com>

src/ap/accounting.c

@@ -167,19 +167,25 @@ static int accounting_sta_update_stats(struct hostapd_data *hapd,
 	if (hostapd_drv_read_sta_data(hapd, data, sta->addr))
 		return -1;
 
-	if (sta->last_rx_bytes > data->rx_bytes)
-		sta->acct_input_gigawords++;
-	if (sta->last_tx_bytes > data->tx_bytes)
-		sta->acct_output_gigawords++;
-	sta->last_rx_bytes = data->rx_bytes;
-	sta->last_tx_bytes = data->tx_bytes;
+	if (!data->bytes_64bit) {
+		/* Extend 32-bit counters from the driver to 64-bit counters */
+		if (sta->last_rx_bytes_lo > data->rx_bytes)
+			sta->last_rx_bytes_hi++;
+		sta->last_rx_bytes_lo = data->rx_bytes;
+
+		if (sta->last_tx_bytes_lo > data->tx_bytes)
+			sta->last_tx_bytes_hi++;
+		sta->last_tx_bytes_lo = data->tx_bytes;
+	}
 
 	hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_RADIUS,
-		       HOSTAPD_LEVEL_DEBUG, "updated TX/RX stats: "
-		       "Acct-Input-Octets=%lu Acct-Input-Gigawords=%u "
-		       "Acct-Output-Octets=%lu Acct-Output-Gigawords=%u",
-		       sta->last_rx_bytes, sta->acct_input_gigawords,
-		       sta->last_tx_bytes, sta->acct_output_gigawords);
+		       HOSTAPD_LEVEL_DEBUG,
+		       "updated TX/RX stats: rx_bytes=%llu [%u:%u] tx_bytes=%llu [%u:%u] bytes_64bit=%d",
+		       data->rx_bytes, sta->last_rx_bytes_hi,
+		       sta->last_rx_bytes_lo,
+		       data->tx_bytes, sta->last_tx_bytes_hi,
+		       sta->last_tx_bytes_lo,
+		       data->bytes_64bit);
 
 	return 0;
 }
@@ -224,8 +230,10 @@ void accounting_sta_start(struct hostapd_data *hapd, struct sta_info *sta)
 		       (unsigned long long) sta->acct_session_id);
 
 	os_get_reltime(&sta->acct_session_start);
-	sta->last_rx_bytes = sta->last_tx_bytes = 0;
-	sta->acct_input_gigawords = sta->acct_output_gigawords = 0;
+	sta->last_rx_bytes_hi = 0;
+	sta->last_rx_bytes_lo = 0;
+	sta->last_tx_bytes_hi = 0;
+	sta->last_tx_bytes_lo = 0;
 	hostapd_drv_sta_clear_stats(hapd, sta->addr);
 
 	if (!hapd->conf->radius->acct_server)
@@ -254,7 +262,7 @@ static void accounting_sta_report(struct hostapd_data *hapd,
 	int cause = sta->acct_terminate_cause;
 	struct hostap_sta_driver_data data;
 	struct os_reltime now_r, diff;
-	u32 gigawords;
+	u64 bytes;
 
 	if (!hapd->conf->radius->acct_server)
 		return;
@@ -288,37 +296,37 @@ static void accounting_sta_report(struct hostapd_data *hapd,
 			wpa_printf(MSG_INFO, "Could not add Acct-Output-Packets");
 			goto fail;
 		}
+		if (data.bytes_64bit)
+			bytes = data.rx_bytes;
+		else
+			bytes = ((u64) sta->last_rx_bytes_hi << 32) |
+				sta->last_rx_bytes_lo;
 		if (!radius_msg_add_attr_int32(msg,
 					       RADIUS_ATTR_ACCT_INPUT_OCTETS,
-					       data.rx_bytes)) {
+					       (u32) bytes)) {
 			wpa_printf(MSG_INFO, "Could not add Acct-Input-Octets");
 			goto fail;
 		}
-		gigawords = sta->acct_input_gigawords;
-#if __WORDSIZE == 64
-		gigawords += data.rx_bytes >> 32;
-#endif
-		if (gigawords &&
-		    !radius_msg_add_attr_int32(
-			    msg, RADIUS_ATTR_ACCT_INPUT_GIGAWORDS,
-			    gigawords)) {
+		if (!radius_msg_add_attr_int32(msg,
+					       RADIUS_ATTR_ACCT_INPUT_GIGAWORDS,
+					       (u32) (bytes >> 32))) {
 			wpa_printf(MSG_INFO, "Could not add Acct-Input-Gigawords");
 			goto fail;
 		}
+		if (data.bytes_64bit)
+			bytes = data.tx_bytes;
+		else
+			bytes = ((u64) sta->last_tx_bytes_hi << 32) |
+				sta->last_tx_bytes_lo;
 		if (!radius_msg_add_attr_int32(msg,
 					       RADIUS_ATTR_ACCT_OUTPUT_OCTETS,
-					       data.tx_bytes)) {
+					       (u32) bytes)) {
 			wpa_printf(MSG_INFO, "Could not add Acct-Output-Octets");
 			goto fail;
 		}
-		gigawords = sta->acct_output_gigawords;
-#if __WORDSIZE == 64
-		gigawords += data.tx_bytes >> 32;
-#endif
-		if (gigawords &&
-		    !radius_msg_add_attr_int32(
-			    msg, RADIUS_ATTR_ACCT_OUTPUT_GIGAWORDS,
-			    gigawords)) {
+		if (!radius_msg_add_attr_int32(msg,
+					       RADIUS_ATTR_ACCT_OUTPUT_GIGAWORDS,
+					       (u32) (bytes >> 32))) {
 			wpa_printf(MSG_INFO, "Could not add Acct-Output-Gigawords");
 			goto fail;
 		}

src/ap/ctrl_iface_ap.c

@@ -35,7 +35,7 @@ static int hostapd_get_sta_tx_rx(struct hostapd_data *hapd,
 		return 0;
 
 	ret = os_snprintf(buf, buflen, "rx_packets=%lu\ntx_packets=%lu\n"
-			  "rx_bytes=%lu\ntx_bytes=%lu\n",
+			  "rx_bytes=%llu\ntx_bytes=%llu\n",
 			  data.rx_packets, data.tx_packets,
 			  data.rx_bytes, data.tx_bytes);
 	if (os_snprintf_error(buflen, ret))

src/ap/sta_info.h

@@ -109,10 +109,11 @@ struct sta_info {
 	int acct_terminate_cause; /* Acct-Terminate-Cause */
 	int acct_interim_interval; /* Acct-Interim-Interval */
 
-	unsigned long last_rx_bytes;
-	unsigned long last_tx_bytes;
-	u32 acct_input_gigawords; /* Acct-Input-Gigawords */
-	u32 acct_output_gigawords; /* Acct-Output-Gigawords */
+	/* For extending 32-bit driver counters to 64-bit counters */
+	u32 last_rx_bytes_hi;
+	u32 last_rx_bytes_lo;
+	u32 last_tx_bytes_hi;
+	u32 last_tx_bytes_lo;
 
 	u8 *challenge; /* IEEE 802.11 Shared Key Authentication Challenge */
 

src/drivers/driver.h

@@ -1373,7 +1373,9 @@ struct wpa_driver_capa {
 struct hostapd_data;
 
 struct hostap_sta_driver_data {
-	unsigned long rx_packets, tx_packets, rx_bytes, tx_bytes;
+	unsigned long rx_packets, tx_packets;
+	unsigned long long rx_bytes, tx_bytes;
+	int bytes_64bit; /* whether 64-bit byte counters are supported */
 	unsigned long current_tx_rate;
 	unsigned long inactive_msec;
 	unsigned long flags;

src/drivers/driver_nl80211.c

@@ -5381,6 +5381,8 @@ static int get_sta_handler(struct nl_msg *msg, void *arg)
 		[NL80211_STA_INFO_RX_PACKETS] = { .type = NLA_U32 },
 		[NL80211_STA_INFO_TX_PACKETS] = { .type = NLA_U32 },
 		[NL80211_STA_INFO_TX_FAILED] = { .type = NLA_U32 },
+		[NL80211_STA_INFO_RX_BYTES64] = { .type = NLA_U64 },
+		[NL80211_STA_INFO_TX_BYTES64] = { .type = NLA_U64 },
 	};
 
 	nla_parse(tb, NL80211_ATTR_MAX, genlmsg_attrdata(gnlh, 0),
@@ -5406,10 +5408,23 @@ static int get_sta_handler(struct nl_msg *msg, void *arg)
 	if (stats[NL80211_STA_INFO_INACTIVE_TIME])
 		data->inactive_msec =
 			nla_get_u32(stats[NL80211_STA_INFO_INACTIVE_TIME]);
+	/* For backwards compatibility, fetch the 32-bit counters first. */
 	if (stats[NL80211_STA_INFO_RX_BYTES])
 		data->rx_bytes = nla_get_u32(stats[NL80211_STA_INFO_RX_BYTES]);
 	if (stats[NL80211_STA_INFO_TX_BYTES])
 		data->tx_bytes = nla_get_u32(stats[NL80211_STA_INFO_TX_BYTES]);
+	if (stats[NL80211_STA_INFO_RX_BYTES64] &&
+	    stats[NL80211_STA_INFO_TX_BYTES64]) {
+		/*
+		 * The driver supports 64-bit counters, so use them to override
+		 * the 32-bit values.
+		 */
+		data->rx_bytes =
+			nla_get_u64(stats[NL80211_STA_INFO_RX_BYTES64]);
+		data->tx_bytes =
+			nla_get_u64(stats[NL80211_STA_INFO_TX_BYTES64]);
+		data->bytes_64bit = 1;
+	}
 	if (stats[NL80211_STA_INFO_RX_PACKETS])
 		data->rx_packets =
 			nla_get_u32(stats[NL80211_STA_INFO_RX_PACKETS]);