mac80211: split ieee80211_key_alloc/free

In order to RCU-ify sta_info, we need to be able to allocate
a key without linking it to an sdata/sta structure (because
allocation cannot be done in an rcu critical section). This
patch splits up ieee80211_key_alloc() and updates all users
appropriately.

While at it, this patch fixes a number of race conditions
such as finally making key replacement atomic, unfortunately
at the expense of more complex code.

Note that this patch documents /existing/ bugs with sta info
and key interaction, there is currently a race condition
when a sta info is freed without holding the RTNL. This will
finally be fixed by a followup patch.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 22 insertions, 4 deletions

diff --git a/net/mac80211/ieee80211_key.h b/net/mac80211/ieee80211_key.h
index fc770e98d47b..d670e6dbfa39 100644
--- a/net/mac80211/ieee80211_key.h
+++ b/net/mac80211/ieee80211_key.h
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/crypto.h>
+#include <linux/rcupdate.h>
 #include <net/mac80211.h>
 
 /* ALG_TKIP
@@ -45,7 +46,19 @@ struct ieee80211_local;
 struct ieee80211_sub_if_data;
 struct sta_info;
 
-#define KEY_FLAG_UPLOADED_TO_HARDWARE   (1<<0)
+/**
+ * enum ieee80211_internal_key_flags - internal key flags
+ *
+ * @KEY_FLAG_UPLOADED_TO_HARDWARE: Indicates that this key is present
+ *      in the hardware for TX crypto hardware acceleration.
+ * @KEY_FLAG_REMOVE_FROM_HARDWARE: Indicates to the key code that this
+ *      key is present in the hardware (but it cannot be used for
+ *      hardware acceleration any more!)
+ */
+enum ieee80211_internal_key_flags {
+        KEY_FLAG_UPLOADED_TO_HARDWARE   = BIT(0),
+        KEY_FLAG_REMOVE_FROM_HARDWARE   = BIT(1),
+};
 
 struct ieee80211_key {
         struct ieee80211_local *local;
@@ -112,12 +125,17 @@ struct ieee80211_key {
         struct ieee80211_key_conf conf;
 };
 
-struct ieee80211_key *ieee80211_key_alloc(struct ieee80211_sub_if_data *sdata,
-                                          struct sta_info *sta,
-                                          enum ieee80211_key_alg alg,
+struct ieee80211_key *ieee80211_key_alloc(enum ieee80211_key_alg alg,
                                           int idx,
                                           size_t key_len,
                                           const u8 *key_data);
+/*
+ * Insert a key into data structures (sdata, sta if necessary)
+ * to make it used, free old key.
+ */
+void ieee80211_key_link(struct ieee80211_key *key,
+                        struct ieee80211_sub_if_data *sdata,
+                        struct sta_info *sta);
 void ieee80211_key_free(struct ieee80211_key *key);
 void ieee80211_set_default_key(struct ieee80211_sub_if_data *sdata, int idx);
 void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata);