[PATCH 4.4 35/38] mac80211: allow driver to prevent two stations w/ same address

From: Greg Kroah-Hartman
Date: Mon Nov 23 2020 - 07:24:03 EST


From: Johannes Berg <johannes.berg@xxxxxxxxx>

commit 3110489117581a980537b6d999a3724214ba772c upstream.

Some devices or drivers cannot deal with having the same station
address for different virtual interfaces, say as a client to two
virtual AP interfaces. Rather than requiring each driver with a
limitation like that to enforce it, add a hardware flag for it.

Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/net/mac80211.h | 6 ++++++
net/mac80211/debugfs.c | 1 +
net/mac80211/sta_info.c | 18 ++++++++++++++++--
3 files changed, 23 insertions(+), 2 deletions(-)

--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1915,6 +1915,11 @@ struct ieee80211_txq {
* @IEEE80211_HW_BEACON_TX_STATUS: The device/driver provides TX status
* for sent beacons.
*
+ * @IEEE80211_HW_NEEDS_UNIQUE_STA_ADDR: Hardware (or driver) requires that each
+ * station has a unique address, i.e. each station entry can be identified
+ * by just its MAC address; this prevents, for example, the same station
+ * from connecting to two virtual AP interfaces at the same time.
+ *
* @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
*/
enum ieee80211_hw_flags {
@@ -1950,6 +1955,7 @@ enum ieee80211_hw_flags {
IEEE80211_HW_TDLS_WIDER_BW,
IEEE80211_HW_SUPPORTS_AMSDU_IN_AMPDU,
IEEE80211_HW_BEACON_TX_STATUS,
+ IEEE80211_HW_NEEDS_UNIQUE_STA_ADDR,

/* keep last, obviously */
NUM_IEEE80211_HW_FLAGS
--- a/net/mac80211/debugfs.c
+++ b/net/mac80211/debugfs.c
@@ -125,6 +125,7 @@ static const char *hw_flag_names[] = {
FLAG(TDLS_WIDER_BW),
FLAG(SUPPORTS_AMSDU_IN_AMPDU),
FLAG(BEACON_TX_STATUS),
+ FLAG(NEEDS_UNIQUE_STA_ADDR),
#undef FLAG
};

--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -457,6 +457,19 @@ static int sta_info_insert_check(struct
is_multicast_ether_addr(sta->sta.addr)))
return -EINVAL;

+ /* Strictly speaking this isn't necessary as we hold the mutex, but
+ * the rhashtable code can't really deal with that distinction. We
+ * do require the mutex for correctness though.
+ */
+ rcu_read_lock();
+ lockdep_assert_held(&sdata->local->sta_mtx);
+ if (ieee80211_hw_check(&sdata->local->hw, NEEDS_UNIQUE_STA_ADDR) &&
+ ieee80211_find_sta_by_ifaddr(&sdata->local->hw, sta->addr, NULL)) {
+ rcu_read_unlock();
+ return -ENOTUNIQ;
+ }
+ rcu_read_unlock();
+
return 0;
}

@@ -585,14 +598,15 @@ int sta_info_insert_rcu(struct sta_info

might_sleep();

+ mutex_lock(&local->sta_mtx);
+
err = sta_info_insert_check(sta);
if (err) {
+ mutex_unlock(&local->sta_mtx);
rcu_read_lock();
goto out_free;
}

- mutex_lock(&local->sta_mtx);
-
err = sta_info_insert_finish(sta);
if (err)
goto out_free;