wil6210: replay attack detection

Check PN for encrypted frames.
Maintain PN data for Rx keys, pairwise per TID and group.
Print PN's in the debugfs "stations" entry, like:

[0] 04:ce:14:0a:3c:3d connected
  [ 0] ([32]   0 TU) 0x0fe [____________________________|___] total 252 drop 0 (dup 0 + old 0) last 0x000
  [ 0] PN [0+]000000000000 [1-]000000000000 [2-]000000000000 [3-]000000000000
  [GR] PN [0-]000000000000 [1+]000000000000 [2+]000000000000 [3-]000000000000
Rx invalid frame: non-data 0, short 0, large 0, replay 0
Rx/MCS: 0 110 65 65 65 0 12 0 0 0 0 0 0
[1] 00:00:00:00:00:00 unused
[2] 00:00:00:00:00:00 unused
[3] 00:00:00:00:00:00 unused
[4] 00:00:00:00:00:00 unused
[5] 00:00:00:00:00:00 unused
[6] 00:00:00:00:00:00 unused
[7] 00:00:00:00:00:00 unused

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Hamad Kadmany <qca_hkadmany@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

1 files changed, 63 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/wil6210/txrx.c b/drivers/net/wireless/ath/wil6210/txrx.c
index 6af20903cf89..f383001b86aa 100644
--- a/drivers/net/wireless/ath/wil6210/txrx.c
+++ b/drivers/net/wireless/ath/wil6210/txrx.c
@@ -549,6 +549,60 @@ static int wil_rx_refill(struct wil6210_priv *wil, int count)
 	return rc;
 }
 
+/**
+ * reverse_memcmp - Compare two areas of memory, in reverse order
+ * @cs: One area of memory
+ * @ct: Another area of memory
+ * @count: The size of the area.
+ *
+ * Cut'n'paste from original memcmp (see lib/string.c)
+ * with minimal modifications
+ */
+static int reverse_memcmp(const void *cs, const void *ct, size_t count)
+{
+	const unsigned char *su1, *su2;
+	int res = 0;
+
+	for (su1 = cs + count - 1, su2 = ct + count - 1; count > 0;
+	     --su1, --su2, count--) {
+		res = *su1 - *su2;
+		if (res)
+			break;
+	}
+	return res;
+}
+
+static int wil_rx_crypto_check(struct wil6210_priv *wil, struct sk_buff *skb)
+{
+	struct vring_rx_desc *d = wil_skb_rxdesc(skb);
+	int cid = wil_rxdesc_cid(d);
+	int tid = wil_rxdesc_tid(d);
+	int key_id = wil_rxdesc_key_id(d);
+	int mc = wil_rxdesc_mcast(d);
+	struct wil_sta_info *s = &wil->sta[cid];
+	struct wil_tid_crypto_rx *c = mc ? &s->group_crypto_rx :
+				      &s->tid_crypto_rx[tid];
+	struct wil_tid_crypto_rx_single *cc = &c->key_id[key_id];
+	const u8 *pn = (u8 *)&d->mac.pn_15_0;
+
+	if (!cc->key_set) {
+		wil_err_ratelimited(wil,
+				    "Key missing. CID %d TID %d MCast %d KEY_ID %d\n",
+				    cid, tid, mc, key_id);
+		return -EINVAL;
+	}
+
+	if (reverse_memcmp(pn, cc->pn, IEEE80211_GCMP_PN_LEN) <= 0) {
+		wil_err_ratelimited(wil,
+				    "Replay attack. CID %d TID %d MCast %d KEY_ID %d PN %6phN last %6phN\n",
+				    cid, tid, mc, key_id, pn, cc->pn);
+		return -EINVAL;
+	}
+	memcpy(cc->pn, pn, IEEE80211_GCMP_PN_LEN);
+
+	return 0;
+}
+
 /*
  * Pass Rx packet to the netif. Update statistics.
  * Called in softirq context (NAPI poll).
@@ -561,6 +615,7 @@ void wil_netif_rx_any(struct sk_buff *skb, struct net_device *ndev)
 	unsigned int len = skb->len;
 	struct vring_rx_desc *d = wil_skb_rxdesc(skb);
 	int cid = wil_rxdesc_cid(d); /* always 0..7, no need to check */
+	int security = wil_rxdesc_security(d);
 	struct ethhdr *eth = (void *)skb->data;
 	/* here looking for DA, not A1, thus Rxdesc's 'mcast' indication
 	 * is not suitable, need to look at data
@@ -586,6 +641,13 @@ void wil_netif_rx_any(struct sk_buff *skb, struct net_device *ndev)
 
 	skb_orphan(skb);
 
+	if (security && (wil_rx_crypto_check(wil, skb) != 0)) {
+		rc = GRO_DROP;
+		dev_kfree_skb(skb);
+		stats->rx_replay++;
+		goto stats;
+	}
+
 	if (wdev->iftype == NL80211_IFTYPE_AP && !wil->ap_isolate) {
 		if (mcast) {
 			/* send multicast frames both to higher layers in
@@ -627,6 +689,7 @@ void wil_netif_rx_any(struct sk_buff *skb, struct net_device *ndev)
 		wil_dbg_txrx(wil, "Rx complete %d bytes => %s\n",
 			     len, gro_res_str[rc]);
 	}
+stats:
 	/* statistics. rc set to GRO_NORMAL for AP bridging */
 	if (unlikely(rc == GRO_DROP)) {
 		ndev->stats.rx_dropped++;