staging: wfx: introduce "secure link"

Chip support encryption of the link between host and chip. This feature
is called "secure link". Driver code on github[1] support it. However,
it relies on mbedtls for cryptographic functions. So, I decided to not
import this feature in current patch. However, in order to keep code
synchronized between github and kernel, I imported all code related to
this feature, even if most of it is just no-op.

[1]: https://github.com/SiliconLabs/wfx-linux-driver/

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20190919142527.31797-14-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 29 insertions, 2 deletions

diff --git a/drivers/staging/wfx/bh.c b/drivers/staging/wfx/bh.c
index c94c9c401a69..d321fd312d55 100644
--- a/drivers/staging/wfx/bh.c
+++ b/drivers/staging/wfx/bh.c
@@ -12,6 +12,7 @@
 #include "wfx.h"
 #include "hwio.h"
 #include "traces.h"
+#include "secure_link.h"
 #include "hif_rx.h"
 #include "hif_api_cmd.h"
 
@@ -74,7 +75,18 @@ static int rx_helper(struct wfx_dev *wdev, size_t read_len, int *is_cnf)
 	hif = (struct hif_msg *) skb->data;
 	WARN(hif->encrypted & 0x1, "unsupported encryption type");
 	if (hif->encrypted == 0x2) {
-		BUG(); // Not yet implemented
+		if (wfx_sl_decode(wdev, (void *) hif)) {
+			dev_kfree_skb(skb);
+			// If frame was a confirmation, expect trouble in next
+			// exchange. However, it is harmless to fail to decode
+			// an indication frame, so try to continue. Anyway,
+			// piggyback is probably correct.
+			return piggyback;
+		}
+		le16_to_cpus(hif->len);
+		computed_len = round_up(hif->len - sizeof(hif->len), 16)
+			       + sizeof(struct hif_sl_msg)
+			       + sizeof(struct hif_sl_tag);
 	} else {
 		le16_to_cpus(hif->len);
 		computed_len = round_up(hif->len, 2);
@@ -166,7 +178,22 @@ static void tx_helper(struct wfx_dev *wdev, struct hif_msg *hif)
 	hif->seqnum = wdev->hif.tx_seqnum;
 	wdev->hif.tx_seqnum = (wdev->hif.tx_seqnum + 1) % (HIF_COUNTER_MAX + 1);
 
-	data = hif;
+	if (wfx_is_secure_command(wdev, hif->id)) {
+		len = round_up(len - sizeof(hif->len), 16) + sizeof(hif->len)
+		      + sizeof(struct hif_sl_msg_hdr) + sizeof(struct hif_sl_tag);
+		// AES support encryption in-place. However, mac80211 access to
+		// 802.11 header after frame was sent (to get MAC addresses).
+		// So, keep origin buffer clear.
+		data = kmalloc(len, GFP_KERNEL);
+		if (!data)
+			goto end;
+		is_encrypted = true;
+		ret = wfx_sl_encode(wdev, hif, data);
+		if (ret)
+			goto end;
+	} else {
+		data = hif;
+	}
 	WARN(len > wdev->hw_caps.size_inp_ch_buf,
 	     "%s: request exceed WFx capability: %zu > %d\n", __func__,
 	     len, wdev->hw_caps.size_inp_ch_buf);