[NET] ieee80211 subsystem

Contributors:
Host AP contributors
James Ketrenos <jketreno@linux.intel.com>
Francois Romieu <romieu@fr.zoreil.com>
Adrian Bunk <bunk@stusta.de>
Matthew Galgoci <mgalgoci@parcelfarce.linux.th
eplanet.co.uk>

1 files changed, 272 insertions, 0 deletions

diff --git a/net/ieee80211/ieee80211_crypt_wep.c b/net/ieee80211/ieee80211_crypt_wep.c
new file mode 100644
index 000000000000..bec1d3470d39
--- /dev/null
+++ b/net/ieee80211/ieee80211_crypt_wep.c
@@ -0,0 +1,272 @@
+/*
+ * Host AP crypt: host-based WEP encryption implementation for Host AP driver
+ *
+ * Copyright (c) 2002-2004, Jouni Malinen <jkmaline@cc.hut.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation. See README and COPYING for
+ * more details.
+ */
+
+#include <linux/config.h>
+#include <linux/version.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/skbuff.h>
+#include <asm/string.h>
+
+#include <net/ieee80211.h>
+
+
+#include <linux/crypto.h>
+#include <asm/scatterlist.h>
+#include <linux/crc32.h>
+
+MODULE_AUTHOR("Jouni Malinen");
+MODULE_DESCRIPTION("Host AP crypt: WEP");
+MODULE_LICENSE("GPL");
+
+
+struct prism2_wep_data {
+        u32 iv;
+#define WEP_KEY_LEN 13
+        u8 key[WEP_KEY_LEN + 1];
+        u8 key_len;
+        u8 key_idx;
+        struct crypto_tfm *tfm;
+};
+
+
+static void * prism2_wep_init(int keyidx)
+{
+        struct prism2_wep_data *priv;
+
+        priv = kmalloc(sizeof(*priv), GFP_ATOMIC);
+        if (priv == NULL)
+                goto fail;
+        memset(priv, 0, sizeof(*priv));
+        priv->key_idx = keyidx;
+
+        priv->tfm = crypto_alloc_tfm("arc4", 0);
+        if (priv->tfm == NULL) {
+                printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
+                       "crypto API arc4\n");
+                goto fail;
+        }
+
+        /* start WEP IV from a random value */
+        get_random_bytes(&priv->iv, 4);
+
+        return priv;
+
+fail:
+        if (priv) {
+                if (priv->tfm)
+                        crypto_free_tfm(priv->tfm);
+                kfree(priv);
+        }
+        return NULL;
+}
+
+
+static void prism2_wep_deinit(void *priv)
+{
+        struct prism2_wep_data *_priv = priv;
+        if (_priv && _priv->tfm)
+                crypto_free_tfm(_priv->tfm);
+        kfree(priv);
+}
+
+
+/* Perform WEP encryption on given skb that has at least 4 bytes of headroom
+ * for IV and 4 bytes of tailroom for ICV. Both IV and ICV will be transmitted,
+ * so the payload length increases with 8 bytes.
+ *
+ * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
+ */
+static int prism2_wep_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
+{
+        struct prism2_wep_data *wep = priv;
+        u32 crc, klen, len;
+        u8 key[WEP_KEY_LEN + 3];
+        u8 *pos, *icv;
+        struct scatterlist sg;
+
+        if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 ||
+            skb->len < hdr_len)
+                return -1;
+
+        len = skb->len - hdr_len;
+        pos = skb_push(skb, 4);
+        memmove(pos, pos + 4, hdr_len);
+        pos += hdr_len;
+
+        klen = 3 + wep->key_len;
+
+        wep->iv++;
+
+        /* Fluhrer, Mantin, and Shamir have reported weaknesses in the key
+         * scheduling algorithm of RC4. At least IVs (KeyByte + 3, 0xff, N)
+         * can be used to speedup attacks, so avoid using them. */
+        if ((wep->iv & 0xff00) == 0xff00) {
+                u8 B = (wep->iv >> 16) & 0xff;
+                if (B >= 3 && B < klen)
+                        wep->iv += 0x0100;
+        }
+
+        /* Prepend 24-bit IV to RC4 key and TX frame */
+        *pos++ = key[0] = (wep->iv >> 16) & 0xff;
+        *pos++ = key[1] = (wep->iv >> 8) & 0xff;
+        *pos++ = key[2] = wep->iv & 0xff;
+        *pos++ = wep->key_idx << 6;
+
+        /* Copy rest of the WEP key (the secret part) */
+        memcpy(key + 3, wep->key, wep->key_len);
+
+        /* Append little-endian CRC32 and encrypt it to produce ICV */
+        crc = ~crc32_le(~0, pos, len);
+        icv = skb_put(skb, 4);
+        icv[0] = crc;
+        icv[1] = crc >> 8;
+        icv[2] = crc >> 16;
+        icv[3] = crc >> 24;
+
+        crypto_cipher_setkey(wep->tfm, key, klen);
+        sg.page = virt_to_page(pos);
+        sg.offset = offset_in_page(pos);
+        sg.length = len + 4;
+        crypto_cipher_encrypt(wep->tfm, &sg, &sg, len + 4);
+
+        return 0;
+}
+
+
+/* Perform WEP decryption on given buffer. Buffer includes whole WEP part of
+ * the frame: IV (4 bytes), encrypted payload (including SNAP header),
+ * ICV (4 bytes). len includes both IV and ICV.
+ *
+ * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
+ * failure. If frame is OK, IV and ICV will be removed.
+ */
+static int prism2_wep_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
+{
+        struct prism2_wep_data *wep = priv;
+        u32 crc, klen, plen;
+        u8 key[WEP_KEY_LEN + 3];
+        u8 keyidx, *pos, icv[4];
+        struct scatterlist sg;
+
+        if (skb->len < hdr_len + 8)
+                return -1;
+
+        pos = skb->data + hdr_len;
+        key[0] = *pos++;
+        key[1] = *pos++;
+        key[2] = *pos++;
+        keyidx = *pos++ >> 6;
+        if (keyidx != wep->key_idx)
+                return -1;
+
+        klen = 3 + wep->key_len;
+
+        /* Copy rest of the WEP key (the secret part) */
+        memcpy(key + 3, wep->key, wep->key_len);
+
+        /* Apply RC4 to data and compute CRC32 over decrypted data */
+        plen = skb->len - hdr_len - 8;
+
+        crypto_cipher_setkey(wep->tfm, key, klen);
+        sg.page = virt_to_page(pos);
+        sg.offset = offset_in_page(pos);
+        sg.length = plen + 4;
+        crypto_cipher_decrypt(wep->tfm, &sg, &sg, plen + 4);
+
+        crc = ~crc32_le(~0, pos, plen);
+        icv[0] = crc;
+        icv[1] = crc >> 8;
+        icv[2] = crc >> 16;
+        icv[3] = crc >> 24;
+        if (memcmp(icv, pos + plen, 4) != 0) {
+                /* ICV mismatch - drop frame */
+                return -2;
+        }
+
+        /* Remove IV and ICV */
+        memmove(skb->data + 4, skb->data, hdr_len);
+        skb_pull(skb, 4);
+        skb_trim(skb, skb->len - 4);
+
+        return 0;
+}
+
+
+static int prism2_wep_set_key(void *key, int len, u8 *seq, void *priv)
+{
+        struct prism2_wep_data *wep = priv;
+
+        if (len < 0 || len > WEP_KEY_LEN)
+                return -1;
+
+        memcpy(wep->key, key, len);
+        wep->key_len = len;
+
+        return 0;
+}
+
+
+static int prism2_wep_get_key(void *key, int len, u8 *seq, void *priv)
+{
+        struct prism2_wep_data *wep = priv;
+
+        if (len < wep->key_len)
+                return -1;
+
+        memcpy(key, wep->key, wep->key_len);
+
+        return wep->key_len;
+}
+
+
+static char * prism2_wep_print_stats(char *p, void *priv)
+{
+        struct prism2_wep_data *wep = priv;
+        p += sprintf(p, "key[%d] alg=WEP len=%d\n",
+                     wep->key_idx, wep->key_len);
+        return p;
+}
+
+
+static struct ieee80211_crypto_ops ieee80211_crypt_wep = {
+        .name                   = "WEP",
+        .init                   = prism2_wep_init,
+        .deinit                 = prism2_wep_deinit,
+        .encrypt_mpdu           = prism2_wep_encrypt,
+        .decrypt_mpdu           = prism2_wep_decrypt,
+        .encrypt_msdu           = NULL,
+        .decrypt_msdu           = NULL,
+        .set_key                = prism2_wep_set_key,
+        .get_key                = prism2_wep_get_key,
+        .print_stats            = prism2_wep_print_stats,
+        .extra_prefix_len       = 4, /* IV */
+        .extra_postfix_len      = 4, /* ICV */
+        .owner                  = THIS_MODULE,
+};
+
+
+static int __init ieee80211_crypto_wep_init(void)
+{
+        return ieee80211_register_crypto_ops(&ieee80211_crypt_wep);
+}
+
+
+static void __exit ieee80211_crypto_wep_exit(void)
+{
+        ieee80211_unregister_crypto_ops(&ieee80211_crypt_wep);
+}
+
+
+module_init(ieee80211_crypto_wep_init);
+module_exit(ieee80211_crypto_wep_exit);