[2/3] mac80211: refactor some key code

Commit Message

Johannes Berg May 19, 2022, 4:07 p.m. UTC

From: Johannes Berg <[e-mail]>

There's some pretty close code here, with the exception
of RCU dereference vs. protected dereference. Refactor
this to just return a pointer and then do the deref in
the caller later.

Signed-off-by: Johannes Berg <[e-mail]>
---
 net/mac80211/cfg.c | 70 +++++++++++++++++++++++-----------------------
 1 file changed, 35 insertions(+), 35 deletions(-)

Comments

Johannes Berg May 19, 2022, 4:11 p.m. UTC | #1

On Thu, 2022-05-19 at 18:07 +0200, Johannes Berg wrote:
> From: Johannes Berg <[e-mail]>
> 
> There's some pretty close code here, with the exception
> of RCU dereference vs. protected dereference. Refactor
> this to just return a pointer and then do the deref in
> the caller later.
> 

Or maybe I shouldn't do the double pointering but rather use RCU
accessors that can do both (with rcu_dereference_check()) ...

johannes

Patch

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index f3b10cee9299..fe49828ca5d6 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -533,34 +533,48 @@  static int ieee80211_add_key(struct wiphy *wiphy, struct net_device *dev,
 	return err;
 }
 
+static struct ieee80211_key **
+ieee80211_lookup_key(struct ieee80211_sub_if_data *sdata,
+		     u8 key_idx, bool pairwise, const u8 *mac_addr)
+{
+	struct sta_info *sta;
+
+	if (mac_addr) {
+		sta = sta_info_get_bss(sdata, mac_addr);
+		if (!sta)
+			return NULL;
+
+		if (pairwise && key_idx < NUM_DEFAULT_KEYS)
+			return &sta->ptk[key_idx];
+
+		if (!pairwise &&
+		    key_idx < NUM_DEFAULT_KEYS +
+			      NUM_DEFAULT_MGMT_KEYS +
+			      NUM_DEFAULT_BEACON_KEYS)
+			return &sta->deflink.gtk[key_idx];
+
+		return NULL;
+	}
+
+	if (key_idx < NUM_DEFAULT_KEYS)
+		return &sdata->keys[key_idx];
+
+	return NULL;
+}
+
 static int ieee80211_del_key(struct wiphy *wiphy, struct net_device *dev,
 			     u8 key_idx, bool pairwise, const u8 *mac_addr)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 	struct ieee80211_local *local = sdata->local;
-	struct sta_info *sta;
-	struct ieee80211_key *key = NULL;
+	struct ieee80211_key *key, **keyptr;
 	int ret;
 
 	mutex_lock(&local->sta_mtx);
 	mutex_lock(&local->key_mtx);
 
-	if (mac_addr) {
-		ret = -ENOENT;
-
-		sta = sta_info_get_bss(sdata, mac_addr);
-		if (!sta)
-			goto out_unlock;
-
-		if (pairwise)
-			key = key_mtx_dereference(local, sta->ptk[key_idx]);
-		else
-			key = key_mtx_dereference(local,
-						  sta->deflink.gtk[key_idx]);
-	} else
-		key = key_mtx_dereference(local, sdata->keys[key_idx]);
-
-	if (!key) {
+	keyptr = ieee80211_lookup_key(sdata, key_idx, pairwise, mac_addr);
+	if (!keyptr || !(key = key_mtx_dereference(local, *keyptr))) {
 		ret = -ENOENT;
 		goto out_unlock;
 	}
@@ -582,10 +596,9 @@  static int ieee80211_get_key(struct wiphy *wiphy, struct net_device *dev,
 					      struct key_params *params))
 {
 	struct ieee80211_sub_if_data *sdata;
-	struct sta_info *sta = NULL;
 	u8 seq[6] = {0};
 	struct key_params params;
-	struct ieee80211_key *key = NULL;
+	struct ieee80211_key *key, **keyptr;
 	u64 pn64;
 	u32 iv32;
 	u16 iv16;
@@ -596,21 +609,8 @@  static int ieee80211_get_key(struct wiphy *wiphy, struct net_device *dev,
 
 	rcu_read_lock();
 
-	if (mac_addr) {
-		sta = sta_info_get_bss(sdata, mac_addr);
-		if (!sta)
-			goto out;
-
-		if (pairwise && key_idx < NUM_DEFAULT_KEYS)
-			key = rcu_dereference(sta->ptk[key_idx]);
-		else if (!pairwise &&
-			 key_idx < NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS +
-			 NUM_DEFAULT_BEACON_KEYS)
-			key = rcu_dereference(sta->deflink.gtk[key_idx]);
-	} else
-		key = rcu_dereference(sdata->keys[key_idx]);
-
-	if (!key)
+	keyptr = ieee80211_lookup_key(sdata, key_idx, pairwise, mac_addr);
+	if (!keyptr || !(key = rcu_dereference(*keyptr)))
 		goto out;
 
 	memset(&params, 0, sizeof(params));