[PATCH v2 1/4] nl80211: Use only the requested STA from a station dump

[Andrei-Alexandru Bleortu]

Commit 97494e94ee2f ("nl80211: Consider all links for station inactive
time in an AP MLD") made i802_read_sta_data() and
nl80211_get_link_signal() request NL80211_CMD_GET_STATION as a dump with
NL80211_ATTR_MAC and NL80211_ATTR_STA_DUMP_LINK_STATS. A kernel that does
not support NL80211_ATTR_STA_DUMP_LINK_STATS ignores NL80211_ATTR_MAC on
a dump and returns every station of the interface, and get_sta_handler()
stored each of them in turn, so with more than one associated STA every
read returned the statistics of the last station in the dump: the
inactivity check, hostapd_cli STA and RADIUS accounting all saw another
STA's counters, and an idle STA was kept or an active one disconnected
depending on its neighbor.

Skip stations other than the requested one.

Assisted-by: LLM
Signed-off-by: Andrei-Alexandru Bleortu <me at andrei-z.com>
---
 src/drivers/driver_nl80211.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index c6578cb86..f88594e27 100644
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -8776,11 +8776,17 @@ static int get_link_sta_stats(struct hostap_sta_driver_data *data,
 }
 
 
+struct get_sta_arg {
+	const u8 *addr;
+	struct hostap_sta_driver_data *data;
+};
+
 static int get_sta_handler(struct nl_msg *msg, void *arg)
 {
 	struct nlattr *tb[NL80211_ATTR_MAX + 1];
 	struct genlmsghdr *gnlh = nlmsg_data(nlmsg_hdr(msg));
-	struct hostap_sta_driver_data *data = arg;
+	struct get_sta_arg *ctx = arg;
+	struct hostap_sta_driver_data *data = ctx->data;
 	struct nlattr *stats[NL80211_STA_INFO_MAX + 1];
 	static struct nla_policy stats_policy[NL80211_STA_INFO_MAX + 1] = {
 		[NL80211_STA_INFO_INACTIVE_TIME] = { .type = NLA_U32 },
@@ -8825,10 +8831,12 @@ static int get_sta_handler(struct nl_msg *msg, void *arg)
 		  genlmsg_attrlen(gnlh, 0), NULL);
 
 	/*
-	 * TODO: validate the interface and mac address!
-	 * Otherwise, there's a race condition as soon as
-	 * the kernel starts sending station notifications.
+	 * A kernel that does not filter a station dump by NL80211_ATTR_MAC
+	 * returns every station of the interface: use only the requested one.
 	 */
+	if (!tb[NL80211_ATTR_MAC] ||
+	    !ether_addr_equal(nla_data(tb[NL80211_ATTR_MAC]), ctx->addr))
+		return NL_SKIP;
 
 	if (!tb[NL80211_ATTR_STA_INFO] && !tb[NL80211_ATTR_MLO_LINKS]) {
 		wpa_printf(MSG_DEBUG, "sta stats missing!");
@@ -9074,6 +9082,7 @@ static int get_sta_handler(struct nl_msg *msg, void *arg)
 int nl80211_get_link_signal(struct i802_bss *bss, const u8 *bssid,
 			    struct hostap_sta_driver_data *data)
 {
+	struct get_sta_arg arg = { .addr = bssid, .data = data };
 	struct nl_msg *msg;
 
 	data->signal = -WPA_INVALID_NOISE;
@@ -9087,7 +9096,7 @@ int nl80211_get_link_signal(struct i802_bss *bss, const u8 *bssid,
 		return -ENOBUFS;
 	}
 
-	return send_and_recv_resp(bss->drv, msg, get_sta_handler, data);
+	return send_and_recv_resp(bss->drv, msg, get_sta_handler, &arg);
 }
 
 
@@ -9095,6 +9104,7 @@ static int i802_read_sta_data(struct i802_bss *bss,
 			      struct hostap_sta_driver_data *data,
 			      const u8 *addr)
 {
+	struct get_sta_arg arg = { .addr = addr, .data = data };
 	struct nl_msg *msg;
 
 	if (!(msg = nl80211_bss_msg(bss, NLM_F_DUMP,
@@ -9105,7 +9115,7 @@ static int i802_read_sta_data(struct i802_bss *bss,
 		return -ENOBUFS;
 	}
 
-	return send_and_recv_resp(bss->drv, msg, get_sta_handler, data);
+	return send_and_recv_resp(bss->drv, msg, get_sta_handler, &arg);
 }
 
 
-- 
2.47.3