diff options
Diffstat (limited to 'kernel/net/mac80211/wep.c')
| -rw-r--r-- | kernel/net/mac80211/wep.c | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/kernel/net/mac80211/wep.c b/kernel/net/mac80211/wep.c new file mode 100644 index 000000000..efa3f48f1 --- /dev/null +++ b/kernel/net/mac80211/wep.c @@ -0,0 +1,339 @@ +/* + * Software WEP encryption implementation + * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi> + * Copyright 2003, Instant802 Networks, Inc. + * + * 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. + */ + +#include <linux/netdevice.h> +#include <linux/types.h> +#include <linux/random.h> +#include <linux/compiler.h> +#include <linux/crc32.h> +#include <linux/crypto.h> +#include <linux/err.h> +#include <linux/mm.h> +#include <linux/scatterlist.h> +#include <linux/slab.h> +#include <asm/unaligned.h> + +#include <net/mac80211.h> +#include "ieee80211_i.h" +#include "wep.h" + + +int ieee80211_wep_init(struct ieee80211_local *local) +{ + /* start WEP IV from a random value */ + get_random_bytes(&local->wep_iv, IEEE80211_WEP_IV_LEN); + + local->wep_tx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(local->wep_tx_tfm)) { + local->wep_rx_tfm = ERR_PTR(-EINVAL); + return PTR_ERR(local->wep_tx_tfm); + } + + local->wep_rx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC); + if (IS_ERR(local->wep_rx_tfm)) { + crypto_free_cipher(local->wep_tx_tfm); + local->wep_tx_tfm = ERR_PTR(-EINVAL); + return PTR_ERR(local->wep_rx_tfm); + } + + return 0; +} + +void ieee80211_wep_free(struct ieee80211_local *local) +{ + if (!IS_ERR(local->wep_tx_tfm)) + crypto_free_cipher(local->wep_tx_tfm); + if (!IS_ERR(local->wep_rx_tfm)) + crypto_free_cipher(local->wep_rx_tfm); +} + +static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen) +{ + /* + * 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 ((iv & 0xff00) == 0xff00) { + u8 B = (iv >> 16) & 0xff; + if (B >= 3 && B < 3 + keylen) + return true; + } + return false; +} + + +static void ieee80211_wep_get_iv(struct ieee80211_local *local, + int keylen, int keyidx, u8 *iv) +{ + local->wep_iv++; + if (ieee80211_wep_weak_iv(local->wep_iv, keylen)) + local->wep_iv += 0x0100; + + if (!iv) + return; + + *iv++ = (local->wep_iv >> 16) & 0xff; + *iv++ = (local->wep_iv >> 8) & 0xff; + *iv++ = local->wep_iv & 0xff; + *iv++ = keyidx << 6; +} + + +static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, + struct sk_buff *skb, + int keylen, int keyidx) +{ + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); + unsigned int hdrlen; + u8 *newhdr; + + hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); + + if (WARN_ON(skb_headroom(skb) < IEEE80211_WEP_IV_LEN)) + return NULL; + + hdrlen = ieee80211_hdrlen(hdr->frame_control); + newhdr = skb_push(skb, IEEE80211_WEP_IV_LEN); + memmove(newhdr, newhdr + IEEE80211_WEP_IV_LEN, hdrlen); + + /* the HW only needs room for the IV, but not the actual IV */ + if (info->control.hw_key && + (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) + return newhdr + hdrlen; + + ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen); + return newhdr + hdrlen; +} + + +static void ieee80211_wep_remove_iv(struct ieee80211_local *local, + struct sk_buff *skb, + struct ieee80211_key *key) +{ + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; + unsigned int hdrlen; + + hdrlen = ieee80211_hdrlen(hdr->frame_control); + memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen); + skb_pull(skb, IEEE80211_WEP_IV_LEN); +} + + +/* Perform WEP encryption using given key. data buffer must have tailroom + * for 4-byte ICV. data_len must not include this ICV. Note: this function + * does _not_ add IV. data = RC4(data | CRC32(data)) */ +int ieee80211_wep_encrypt_data(struct crypto_cipher *tfm, u8 *rc4key, + size_t klen, u8 *data, size_t data_len) +{ + __le32 icv; + int i; + + if (IS_ERR(tfm)) + return -1; + + icv = cpu_to_le32(~crc32_le(~0, data, data_len)); + put_unaligned(icv, (__le32 *)(data + data_len)); + + crypto_cipher_setkey(tfm, rc4key, klen); + for (i = 0; i < data_len + IEEE80211_WEP_ICV_LEN; i++) + crypto_cipher_encrypt_one(tfm, data + i, data + i); + + return 0; +} + + +/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the + * beginning of the buffer 4 bytes of extra space (ICV) in the end of the + * buffer will be added. 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)) + */ +int ieee80211_wep_encrypt(struct ieee80211_local *local, + struct sk_buff *skb, + const u8 *key, int keylen, int keyidx) +{ + u8 *iv; + size_t len; + u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; + + if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN)) + return -1; + + iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx); + if (!iv) + return -1; + + len = skb->len - (iv + IEEE80211_WEP_IV_LEN - skb->data); + + /* Prepend 24-bit IV to RC4 key */ + memcpy(rc4key, iv, 3); + + /* Copy rest of the WEP key (the secret part) */ + memcpy(rc4key + 3, key, keylen); + + /* Add room for ICV */ + skb_put(skb, IEEE80211_WEP_ICV_LEN); + + return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3, + iv + IEEE80211_WEP_IV_LEN, len); +} + + +/* Perform WEP decryption using given key. data buffer includes encrypted + * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. + * Return 0 on success and -1 on ICV mismatch. */ +int ieee80211_wep_decrypt_data(struct crypto_cipher *tfm, u8 *rc4key, + size_t klen, u8 *data, size_t data_len) +{ + __le32 crc; + int i; + + if (IS_ERR(tfm)) + return -1; + + crypto_cipher_setkey(tfm, rc4key, klen); + for (i = 0; i < data_len + IEEE80211_WEP_ICV_LEN; i++) + crypto_cipher_decrypt_one(tfm, data + i, data + i); + + crc = cpu_to_le32(~crc32_le(~0, data, data_len)); + if (memcmp(&crc, data + data_len, IEEE80211_WEP_ICV_LEN) != 0) + /* ICV mismatch */ + return -1; + + return 0; +} + + +/* Perform WEP decryption on given skb. Buffer includes whole WEP part of + * the frame: IV (4 bytes), encrypted payload (including SNAP header), + * ICV (4 bytes). skb->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, i.e., decrypted payload + * is moved to the beginning of the skb and skb length will be reduced. + */ +static int ieee80211_wep_decrypt(struct ieee80211_local *local, + struct sk_buff *skb, + struct ieee80211_key *key) +{ + u32 klen; + u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; + u8 keyidx; + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; + unsigned int hdrlen; + size_t len; + int ret = 0; + + if (!ieee80211_has_protected(hdr->frame_control)) + return -1; + + hdrlen = ieee80211_hdrlen(hdr->frame_control); + if (skb->len < hdrlen + IEEE80211_WEP_IV_LEN + IEEE80211_WEP_ICV_LEN) + return -1; + + len = skb->len - hdrlen - IEEE80211_WEP_IV_LEN - IEEE80211_WEP_ICV_LEN; + + keyidx = skb->data[hdrlen + 3] >> 6; + + if (!key || keyidx != key->conf.keyidx) + return -1; + + klen = 3 + key->conf.keylen; + + /* Prepend 24-bit IV to RC4 key */ + memcpy(rc4key, skb->data + hdrlen, 3); + + /* Copy rest of the WEP key (the secret part) */ + memcpy(rc4key + 3, key->conf.key, key->conf.keylen); + + if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, + skb->data + hdrlen + + IEEE80211_WEP_IV_LEN, len)) + ret = -1; + + /* Trim ICV */ + skb_trim(skb, skb->len - IEEE80211_WEP_ICV_LEN); + + /* Remove IV */ + memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen); + skb_pull(skb, IEEE80211_WEP_IV_LEN); + + return ret; +} + +ieee80211_rx_result +ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) +{ + struct sk_buff *skb = rx->skb; + struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; + __le16 fc = hdr->frame_control; + + if (!ieee80211_is_data(fc) && !ieee80211_is_auth(fc)) + return RX_CONTINUE; + + if (!(status->flag & RX_FLAG_DECRYPTED)) { + if (skb_linearize(rx->skb)) + return RX_DROP_UNUSABLE; + if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) + return RX_DROP_UNUSABLE; + } else if (!(status->flag & RX_FLAG_IV_STRIPPED)) { + if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) + + IEEE80211_WEP_IV_LEN)) + return RX_DROP_UNUSABLE; + ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); + /* remove ICV */ + if (pskb_trim(rx->skb, rx->skb->len - IEEE80211_WEP_ICV_LEN)) + return RX_DROP_UNUSABLE; + } + + return RX_CONTINUE; +} + +static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) +{ + struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); + struct ieee80211_key_conf *hw_key = info->control.hw_key; + + if (!hw_key) { + if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key, + tx->key->conf.keylen, + tx->key->conf.keyidx)) + return -1; + } else if ((hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) || + (hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) { + if (!ieee80211_wep_add_iv(tx->local, skb, + tx->key->conf.keylen, + tx->key->conf.keyidx)) + return -1; + } + + return 0; +} + +ieee80211_tx_result +ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) +{ + struct sk_buff *skb; + + ieee80211_tx_set_protected(tx); + + skb_queue_walk(&tx->skbs, skb) { + if (wep_encrypt_skb(tx, skb) < 0) { + I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); + return TX_DROP; + } + } + + return TX_CONTINUE; +} |