mac80211: allow drivers to access key sequence counter

In order to implement GTK rekeying, the device needs
to be able to encrypt frames with the right PN/IV and
check the PN/IV in RX frames. To be able to tell it
about all those counters, we need to be able to get
them from mac80211, this adds the required API.

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

3 files changed, 137 insertions, 2 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 0aae7bc1eeae..84770cedae2d 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -2592,6 +2592,66 @@ void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
                             struct sk_buff *skb, u8 *p2k);
 
 /**
+ * struct ieee80211_key_seq - key sequence counter
+ *
+ * @tkip: TKIP data, containing IV32 and IV16 in host byte order
+ * @ccmp: PN data, most significant byte first (big endian,
+ *      reverse order than in packet)
+ * @aes_cmac: PN data, most significant byte first (big endian,
+ *      reverse order than in packet)
+ */
+struct ieee80211_key_seq {
+        union {
+                struct {
+                        u32 iv32;
+                        u16 iv16;
+                } tkip;
+                struct {
+                        u8 pn[6];
+                } ccmp;
+                struct {
+                        u8 pn[6];
+                } aes_cmac;
+        };
+};
+
+/**
+ * ieee80211_get_key_tx_seq - get key TX sequence counter
+ *
+ * @keyconf: the parameter passed with the set key
+ * @seq: buffer to receive the sequence data
+ *
+ * This function allows a driver to retrieve the current TX IV/PN
+ * for the given key. It must not be called if IV generation is
+ * offloaded to the device.
+ *
+ * Note that this function may only be called when no TX processing
+ * can be done concurrently, for example when queues are stopped
+ * and the stop has been synchronized.
+ */
+void ieee80211_get_key_tx_seq(struct ieee80211_key_conf *keyconf,
+                              struct ieee80211_key_seq *seq);
+
+/**
+ * ieee80211_get_key_rx_seq - get key RX sequence counter
+ *
+ * @keyconf: the parameter passed with the set key
+ * @tid: The TID, or -1 for the management frame value (CCMP only);
+ *      the value on TID 0 is also used for non-QoS frames. For
+ *      CMAC, only TID 0 is valid.
+ * @seq: buffer to receive the sequence data
+ *
+ * This function allows a driver to retrieve the current RX IV/PNs
+ * for the given key. It must not be called if IV checking is done
+ * by the device and not by mac80211.
+ *
+ * Note that this function may only be called when no RX processing
+ * can be done concurrently.
+ */
+void ieee80211_get_key_rx_seq(struct ieee80211_key_conf *keyconf,
+                              int tid, struct ieee80211_key_seq *seq);
+
+/**
  * ieee80211_gtk_rekey_notify - notify userspace supplicant of rekeying
  * @vif: virtual interface the rekeying was done on
  * @bssid: The BSSID of the AP, for checking association
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index d930d4d4876d..739bee13e813 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -626,3 +626,77 @@ void ieee80211_gtk_rekey_notify(struct ieee80211_vif *vif, const u8 *bssid,
         cfg80211_gtk_rekey_notify(sdata->dev, bssid, replay_ctr, gfp);
 }
 EXPORT_SYMBOL_GPL(ieee80211_gtk_rekey_notify);
+
+void ieee80211_get_key_tx_seq(struct ieee80211_key_conf *keyconf,
+                              struct ieee80211_key_seq *seq)
+{
+        struct ieee80211_key *key;
+        u64 pn64;
+
+        if (WARN_ON(!(keyconf->flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
+                return;
+
+        key = container_of(keyconf, struct ieee80211_key, conf);
+
+        switch (key->conf.cipher) {
+        case WLAN_CIPHER_SUITE_TKIP:
+                seq->tkip.iv32 = key->u.tkip.tx.iv32;
+                seq->tkip.iv16 = key->u.tkip.tx.iv16;
+                break;
+        case WLAN_CIPHER_SUITE_CCMP:
+                pn64 = atomic64_read(&key->u.ccmp.tx_pn);
+                seq->ccmp.pn[5] = pn64;
+                seq->ccmp.pn[4] = pn64 >> 8;
+                seq->ccmp.pn[3] = pn64 >> 16;
+                seq->ccmp.pn[2] = pn64 >> 24;
+                seq->ccmp.pn[1] = pn64 >> 32;
+                seq->ccmp.pn[0] = pn64 >> 40;
+                break;
+        case WLAN_CIPHER_SUITE_AES_CMAC:
+                pn64 = atomic64_read(&key->u.aes_cmac.tx_pn);
+                seq->ccmp.pn[5] = pn64;
+                seq->ccmp.pn[4] = pn64 >> 8;
+                seq->ccmp.pn[3] = pn64 >> 16;
+                seq->ccmp.pn[2] = pn64 >> 24;
+                seq->ccmp.pn[1] = pn64 >> 32;
+                seq->ccmp.pn[0] = pn64 >> 40;
+                break;
+        default:
+                WARN_ON(1);
+        }
+}
+EXPORT_SYMBOL(ieee80211_get_key_tx_seq);
+
+void ieee80211_get_key_rx_seq(struct ieee80211_key_conf *keyconf,
+                              int tid, struct ieee80211_key_seq *seq)
+{
+        struct ieee80211_key *key;
+        const u8 *pn;
+
+        key = container_of(keyconf, struct ieee80211_key, conf);
+
+        switch (key->conf.cipher) {
+        case WLAN_CIPHER_SUITE_TKIP:
+                if (WARN_ON(tid < 0 || tid >= NUM_RX_DATA_QUEUES))
+                        return;
+                seq->tkip.iv32 = key->u.tkip.rx[tid].iv32;
+                seq->tkip.iv16 = key->u.tkip.rx[tid].iv16;
+                break;
+        case WLAN_CIPHER_SUITE_CCMP:
+                if (WARN_ON(tid < -1 || tid >= NUM_RX_DATA_QUEUES))
+                        return;
+                if (tid < 0)
+                        pn = key->u.ccmp.rx_pn[NUM_RX_DATA_QUEUES];
+                else
+                        pn = key->u.ccmp.rx_pn[tid];
+                memcpy(seq->ccmp.pn, pn, CCMP_PN_LEN);
+                break;
+        case WLAN_CIPHER_SUITE_AES_CMAC:
+                if (WARN_ON(tid != 0))
+                        return;
+                pn = key->u.aes_cmac.rx_pn;
+                memcpy(seq->aes_cmac.pn, pn, CMAC_PN_LEN);
+                break;
+        }
+}
+EXPORT_SYMBOL(ieee80211_get_key_rx_seq);
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index beb9c20ff48c..86b216b01415 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -28,6 +28,7 @@
 #define CCMP_PN_LEN             6
 #define TKIP_IV_LEN             8
 #define TKIP_ICV_LEN            4
+#define CMAC_PN_LEN             6
 
 #define NUM_RX_DATA_QUEUES      16
 
@@ -89,13 +90,13 @@ struct ieee80211_key {
                          * frames and the last counter is used with Robust
                          * Management frames.
                          */
-                        u8 rx_pn[NUM_RX_DATA_QUEUES + 1][6];
+                        u8 rx_pn[NUM_RX_DATA_QUEUES + 1][CCMP_PN_LEN];
                         struct crypto_cipher *tfm;
                         u32 replays; /* dot11RSNAStatsCCMPReplays */
                 } ccmp;
                 struct {
                         atomic64_t tx_pn;
-                        u8 rx_pn[6];
+                        u8 rx_pn[CMAC_PN_LEN];
                         struct crypto_cipher *tfm;
                         u32 replays; /* dot11RSNAStatsCMACReplays */
                         u32 icverrors; /* dot11RSNAStatsCMACICVErrors */