rt2x00: Implement HW encryption

Various rt2x00 devices support hardware encryption.

Most of them require the IV/EIV to be generated by mac80211,
but require it to be provided seperately instead of within
the frame itself. This means that rt2x00lib should extract
the data from the frame and place it in the frame descriptor.
During RX the IV/EIV is provided in the descriptor by the
hardware which means that it should be inserted into the
frame by rt2x00lib.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 215 insertions, 0 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00crypto.c b/drivers/net/wireless/rt2x00/rt2x00crypto.c
new file mode 100644
index 000000000000..e1448cfa9444
--- /dev/null
+++ b/drivers/net/wireless/rt2x00/rt2x00crypto.c
@@ -0,0 +1,215 @@
+/*
+        Copyright (C) 2004 - 2008 rt2x00 SourceForge Project
+        <http://rt2x00.serialmonkey.com>
+
+        This program is free software; you can redistribute it and/or modify
+        it under the terms of the GNU General Public License as published by
+        the Free Software Foundation; either version 2 of the License, or
+        (at your option) any later version.
+
+        This program is distributed in the hope that it will be useful,
+        but WITHOUT ANY WARRANTY; without even the implied warranty of
+        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+        GNU General Public License for more details.
+
+        You should have received a copy of the GNU General Public License
+        along with this program; if not, write to the
+        Free Software Foundation, Inc.,
+        59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+/*
+        Module: rt2x00lib
+        Abstract: rt2x00 crypto specific routines.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "rt2x00.h"
+#include "rt2x00lib.h"
+
+enum cipher rt2x00crypto_key_to_cipher(struct ieee80211_key_conf *key)
+{
+        switch (key->alg) {
+        case ALG_WEP:
+                if (key->keylen == LEN_WEP40)
+                        return CIPHER_WEP64;
+                else
+                        return CIPHER_WEP128;
+        case ALG_TKIP:
+                return CIPHER_TKIP;
+        case ALG_CCMP:
+                return CIPHER_AES;
+        default:
+                return CIPHER_NONE;
+        }
+}
+
+unsigned int rt2x00crypto_tx_overhead(struct ieee80211_tx_info *tx_info)
+{
+        struct ieee80211_key_conf *key = tx_info->control.hw_key;
+        unsigned int overhead = 0;
+
+        /*
+         * Extend frame length to include IV/EIV/ICV/MMIC,
+         * note that these lengths should only be added when
+         * mac80211 does not generate it.
+         */
+        overhead += tx_info->control.icv_len;
+
+        if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_IV))
+                overhead += tx_info->control.iv_len;
+
+        if (!(key->flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
+                if (key->alg == ALG_TKIP)
+                        overhead += 8;
+        }
+
+        return overhead;
+}
+
+void rt2x00crypto_tx_remove_iv(struct sk_buff *skb, unsigned int iv_len)
+{
+        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
+        unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
+
+        if (unlikely(!iv_len))
+                return;
+
+        /* Copy IV/EIV data */
+        if (iv_len >= 4)
+                memcpy(&skbdesc->iv, skb->data + header_length, 4);
+        if (iv_len >= 8)
+                memcpy(&skbdesc->eiv, skb->data + header_length + 4, 4);
+
+        /* Move ieee80211 header */
+        memmove(skb->data + iv_len, skb->data, header_length);
+
+        /* Pull buffer to correct size */
+        skb_pull(skb, iv_len);
+
+        /* IV/EIV data has officially be stripped */
+        skbdesc->flags |= FRAME_DESC_IV_STRIPPED;
+}
+
+void rt2x00crypto_tx_insert_iv(struct sk_buff *skb)
+{
+        struct skb_frame_desc *skbdesc = get_skb_frame_desc(skb);
+        unsigned int header_length = ieee80211_get_hdrlen_from_skb(skb);
+        const unsigned int iv_len =
+            ((!!(skbdesc->iv)) * 4) + ((!!(skbdesc->eiv)) * 4);
+
+        if (!(skbdesc->flags & FRAME_DESC_IV_STRIPPED))
+                return;
+
+        skb_push(skb, iv_len);
+
+        /* Move ieee80211 header */
+        memmove(skb->data, skb->data + iv_len, header_length);
+
+        /* Copy IV/EIV data */
+        if (iv_len >= 4)
+                memcpy(skb->data + header_length, &skbdesc->iv, 4);
+        if (iv_len >= 8)
+                memcpy(skb->data + header_length + 4, &skbdesc->eiv, 4);
+
+        /* IV/EIV data has returned into the frame */
+        skbdesc->flags &= ~FRAME_DESC_IV_STRIPPED;
+}
+
+void rt2x00crypto_rx_insert_iv(struct sk_buff *skb, unsigned int align,
+                               unsigned int header_length,
+                               struct rxdone_entry_desc *rxdesc)
+{
+        unsigned int payload_len = rxdesc->size - header_length;
+        unsigned int iv_len;
+        unsigned int icv_len;
+        unsigned int transfer = 0;
+
+        /*
+         * WEP64/WEP128: Provides IV & ICV
+         * TKIP: Provides IV/EIV & ICV
+         * AES: Provies IV/EIV & ICV
+         */
+        switch (rxdesc->cipher) {
+        case CIPHER_WEP64:
+        case CIPHER_WEP128:
+                iv_len = 4;
+                icv_len = 4;
+                break;
+        case CIPHER_TKIP:
+                iv_len = 8;
+                icv_len = 4;
+                break;
+        case CIPHER_AES:
+                iv_len = 8;
+                icv_len = 8;
+                break;
+        default:
+                /* Unsupport type */
+                return;
+        }
+
+        /*
+         * Make room for new data, note that we increase both
+         * headsize and tailsize when required. The tailsize is
+         * only needed when ICV data needs to be inserted and
+         * the padding is smaller then the ICV data.
+         * When alignment requirements is greater then the
+         * ICV data we must trim the skb to the correct size
+         * because we need to remove the extra bytes.
+         */
+        skb_push(skb, iv_len + align);
+        if (align < icv_len)
+                skb_put(skb, icv_len - align);
+        else if (align > icv_len)
+                skb_trim(skb, rxdesc->size + iv_len + icv_len);
+
+        /* Move ieee80211 header */
+        memmove(skb->data + transfer,
+                skb->data + transfer + iv_len + align,
+                header_length);
+        transfer += header_length;
+
+        /* Copy IV data */
+        if (iv_len >= 4) {
+                memcpy(skb->data + transfer, &rxdesc->iv, 4);
+                transfer += 4;
+        }
+
+        /* Copy EIV data */
+        if (iv_len >= 8) {
+                memcpy(skb->data + transfer, &rxdesc->eiv, 4);
+                transfer += 4;
+        }
+
+        /* Move payload */
+        if (align) {
+                memmove(skb->data + transfer,
+                        skb->data + transfer + align,
+                        payload_len);
+        }
+
+        /*
+         * NOTE: Always count the payload as transfered,
+         * even when alignment was set to zero. This is required
+         * for determining the correct offset for the ICV data.
+         */
+        transfer += payload_len;
+
+        /* Copy ICV data */
+        if (icv_len >= 4) {
+                memcpy(skb->data + transfer, &rxdesc->icv, 4);
+                /*
+                 * AES appends 8 bytes, we can't fill the upper
+                 * 4 bytes, but mac80211 doesn't care about what
+                 * we provide here anyway and strips it immediately.
+                 */
+                transfer += icv_len;
+        }
+
+        /* IV/EIV/ICV has been inserted into frame */
+        rxdesc->size = transfer;
+        rxdesc->flags &= ~RX_FLAG_IV_STRIPPED;
+}