mac80211: add generic cipher scheme support

This adds generic cipher scheme support to mac80211, such schemes
are fully under control by the driver. On hw registration drivers
may specify additional HW ciphers with a scheme how these ciphers
have to be handled by mac80211 TX/RR. A cipher scheme specifies a
cipher suite value, a size of the security header to be added to
or stripped from frames and how the PN is to be verified on RX.

Signed-off-by: Max Stepanov <Max.Stepanov@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index d65728220763..7313d379c0d3 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -545,6 +545,106 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
 	return RX_CONTINUE;
 }
 
+static ieee80211_tx_result
+ieee80211_crypto_cs_encrypt(struct ieee80211_tx_data *tx,
+			    struct sk_buff *skb)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+	struct ieee80211_key *key = tx->key;
+	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	const struct ieee80211_cipher_scheme *cs = key->sta->cipher_scheme;
+	int hdrlen;
+	u8 *pos;
+
+	if (info->control.hw_key &&
+	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
+		/* hwaccel has no need for preallocated head room */
+		return TX_CONTINUE;
+	}
+
+	if (unlikely(skb_headroom(skb) < cs->hdr_len &&
+		     pskb_expand_head(skb, cs->hdr_len, 0, GFP_ATOMIC)))
+		return TX_DROP;
+
+	hdrlen = ieee80211_hdrlen(hdr->frame_control);
+
+	pos = skb_push(skb, cs->hdr_len);
+	memmove(pos, pos + cs->hdr_len, hdrlen);
+	skb_set_network_header(skb, skb_network_offset(skb) + cs->hdr_len);
+
+	return TX_CONTINUE;
+}
+
+static inline int ieee80211_crypto_cs_pn_compare(u8 *pn1, u8 *pn2, int len)
+{
+	int i;
+
+	/* pn is little endian */
+	for (i = len - 1; i >= 0; i--) {
+		if (pn1[i] < pn2[i])
+			return -1;
+		else if (pn1[i] > pn2[i])
+			return 1;
+	}
+
+	return 0;
+}
+
+static ieee80211_rx_result
+ieee80211_crypto_cs_decrypt(struct ieee80211_rx_data *rx)
+{
+	struct ieee80211_key *key = rx->key;
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
+	const struct ieee80211_cipher_scheme *cs = NULL;
+	int hdrlen = ieee80211_hdrlen(hdr->frame_control);
+	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(rx->skb);
+	int data_len;
+	u8 *rx_pn;
+	u8 *skb_pn;
+	u8 qos_tid;
+
+	if (!rx->sta || !rx->sta->cipher_scheme ||
+	    !(status->flag & RX_FLAG_DECRYPTED))
+		return RX_DROP_UNUSABLE;
+
+	if (!ieee80211_is_data(hdr->frame_control))
+		return RX_CONTINUE;
+
+	cs = rx->sta->cipher_scheme;
+
+	data_len = rx->skb->len - hdrlen - cs->hdr_len;
+
+	if (data_len < 0)
+		return RX_DROP_UNUSABLE;
+
+	if (ieee80211_is_data_qos(hdr->frame_control))
+		qos_tid = *ieee80211_get_qos_ctl(hdr) &
+				IEEE80211_QOS_CTL_TID_MASK;
+	else
+		qos_tid = 0;
+
+	if (skb_linearize(rx->skb))
+		return RX_DROP_UNUSABLE;
+
+	hdr = (struct ieee80211_hdr *)rx->skb->data;
+
+	rx_pn = key->u.gen.rx_pn[qos_tid];
+	skb_pn = rx->skb->data + hdrlen + cs->pn_off;
+
+	if (ieee80211_crypto_cs_pn_compare(skb_pn, rx_pn, cs->pn_len) <= 0)
+		return RX_DROP_UNUSABLE;
+
+	memcpy(rx_pn, skb_pn, cs->pn_len);
+
+	/* remove security header and MIC */
+	if (pskb_trim(rx->skb, rx->skb->len - cs->mic_len))
+		return RX_DROP_UNUSABLE;
+
+	memmove(rx->skb->data + cs->hdr_len, rx->skb->data, hdrlen);
+	skb_pull(rx->skb, cs->hdr_len);
+
+	return RX_CONTINUE;
+}
 
 static void bip_aad(struct sk_buff *skb, u8 *aad)
 {
@@ -685,6 +785,7 @@ ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
 {
 	struct sk_buff *skb;
 	struct ieee80211_tx_info *info = NULL;
+	ieee80211_tx_result res;
 
 	skb_queue_walk(&tx->skbs, skb) {
 		info  = IEEE80211_SKB_CB(skb);
@@ -692,9 +793,24 @@ ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
 		/* handle hw-only algorithm */
 		if (!info->control.hw_key)
 			return TX_DROP;
+
+		if (tx->key->sta->cipher_scheme) {
+			res = ieee80211_crypto_cs_encrypt(tx, skb);
+			if (res != TX_CONTINUE)
+				return res;
+		}
 	}
 
 	ieee80211_tx_set_protected(tx);
 
 	return TX_CONTINUE;
 }
+
+ieee80211_rx_result
+ieee80211_crypto_hw_decrypt(struct ieee80211_rx_data *rx)
+{
+	if (rx->sta->cipher_scheme)
+		return ieee80211_crypto_cs_decrypt(rx);
+
+	return RX_DROP_UNUSABLE;
+}