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net/mac80211/wep.c
8.82 KB
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/* * 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> |
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#include <linux/scatterlist.h> |
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#include <linux/slab.h> |
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#include <asm/unaligned.h> |
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#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, WEP_IV_LEN); |
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local->wep_tx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC); |
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if (IS_ERR(local->wep_tx_tfm)) { local->wep_rx_tfm = ERR_PTR(-EINVAL); |
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return PTR_ERR(local->wep_tx_tfm); |
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} |
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|
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local->wep_rx_tfm = crypto_alloc_cipher("arc4", 0, CRYPTO_ALG_ASYNC); |
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if (IS_ERR(local->wep_rx_tfm)) { |
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crypto_free_cipher(local->wep_tx_tfm); |
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local->wep_tx_tfm = ERR_PTR(-EINVAL); |
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return PTR_ERR(local->wep_rx_tfm); |
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} return 0; } void ieee80211_wep_free(struct ieee80211_local *local) { |
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if (!IS_ERR(local->wep_tx_tfm)) |
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crypto_free_cipher(local->wep_tx_tfm); |
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if (!IS_ERR(local->wep_rx_tfm)) |
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crypto_free_cipher(local->wep_rx_tfm); |
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} |
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static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen) |
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{ |
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/* * Fluhrer, Mantin, and Shamir have reported weaknesses in the |
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* key scheduling algorithm of RC4. At least IVs (KeyByte + 3, |
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* 0xff, N) can be used to speedup attacks, so avoid using them. */ |
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if ((iv & 0xff00) == 0xff00) { u8 B = (iv >> 16) & 0xff; if (B >= 3 && B < 3 + keylen) |
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return true; |
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} |
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return false; |
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} |
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static void ieee80211_wep_get_iv(struct ieee80211_local *local, |
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int keylen, int keyidx, u8 *iv) |
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{ local->wep_iv++; |
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if (ieee80211_wep_weak_iv(local->wep_iv, keylen)) |
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local->wep_iv += 0x0100; if (!iv) return; *iv++ = (local->wep_iv >> 16) & 0xff; *iv++ = (local->wep_iv >> 8) & 0xff; *iv++ = local->wep_iv & 0xff; |
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*iv++ = keyidx << 6; |
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} |
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static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local, struct sk_buff *skb, |
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int keylen, int keyidx) |
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{ |
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; unsigned int hdrlen; |
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u8 *newhdr; |
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hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED); |
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|
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if (WARN_ON(skb_tailroom(skb) < WEP_ICV_LEN || skb_headroom(skb) < WEP_IV_LEN)) return NULL; |
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|
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hdrlen = ieee80211_hdrlen(hdr->frame_control); |
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newhdr = skb_push(skb, WEP_IV_LEN); memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); |
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ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen); |
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return newhdr + hdrlen; } |
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static void ieee80211_wep_remove_iv(struct ieee80211_local *local, struct sk_buff *skb, struct ieee80211_key *key) |
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{ |
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; unsigned int hdrlen; |
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|
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hdrlen = ieee80211_hdrlen(hdr->frame_control); |
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memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); skb_pull(skb, 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)) */ |
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int ieee80211_wep_encrypt_data(struct crypto_cipher *tfm, u8 *rc4key, |
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size_t klen, u8 *data, size_t data_len) |
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{ |
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__le32 icv; |
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int i; |
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|
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if (IS_ERR(tfm)) return -1; |
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icv = cpu_to_le32(~crc32_le(~0, data, data_len)); put_unaligned(icv, (__le32 *)(data + data_len)); |
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|
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crypto_cipher_setkey(tfm, rc4key, klen); for (i = 0; i < data_len + WEP_ICV_LEN; i++) crypto_cipher_encrypt_one(tfm, data + i, data + i); |
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return 0; |
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} /* 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)) */ |
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int ieee80211_wep_encrypt(struct ieee80211_local *local, struct sk_buff *skb, const u8 *key, int keylen, int keyidx) |
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{ |
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u8 *iv; |
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size_t len; |
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u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
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|
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iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx); if (!iv) |
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return -1; |
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len = skb->len - (iv + 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) */ |
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memcpy(rc4key + 3, key, keylen); |
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/* Add room for ICV */ skb_put(skb, WEP_ICV_LEN); |
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return ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3, iv + WEP_IV_LEN, len); |
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} /* 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. */ |
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int ieee80211_wep_decrypt_data(struct crypto_cipher *tfm, u8 *rc4key, |
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size_t klen, u8 *data, size_t data_len) { |
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__le32 crc; |
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int i; |
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|
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if (IS_ERR(tfm)) return -1; |
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crypto_cipher_setkey(tfm, rc4key, klen); for (i = 0; i < data_len + WEP_ICV_LEN; i++) crypto_cipher_decrypt_one(tfm, data + i, data + i); |
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crc = cpu_to_le32(~crc32_le(~0, data, data_len)); if (memcmp(&crc, data + data_len, 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. */ |
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static int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb, struct ieee80211_key *key) |
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{ u32 klen; |
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u8 rc4key[3 + WLAN_KEY_LEN_WEP104]; |
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u8 keyidx; |
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; unsigned int hdrlen; |
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size_t len; int ret = 0; |
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if (!ieee80211_has_protected(hdr->frame_control)) |
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return -1; |
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hdrlen = ieee80211_hdrlen(hdr->frame_control); |
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if (skb->len < hdrlen + WEP_IV_LEN + WEP_ICV_LEN) |
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return -1; |
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len = skb->len - hdrlen - WEP_IV_LEN - WEP_ICV_LEN; |
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keyidx = skb->data[hdrlen + 3] >> 6; |
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if (!key || keyidx != key->conf.keyidx) |
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return -1; |
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klen = 3 + key->conf.keylen; |
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|
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/* Prepend 24-bit IV to RC4 key */ memcpy(rc4key, skb->data + hdrlen, 3); /* Copy rest of the WEP key (the secret part) */ |
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memcpy(rc4key + 3, key->conf.key, key->conf.keylen); |
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if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, skb->data + hdrlen + WEP_IV_LEN, |
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len)) |
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ret = -1; |
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|
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/* Trim ICV */ skb_trim(skb, skb->len - WEP_ICV_LEN); /* Remove IV */ memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen); skb_pull(skb, WEP_IV_LEN); return ret; } |
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bool ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) |
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{ |
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; unsigned int hdrlen; |
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u8 *ivpos; u32 iv; |
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if (!ieee80211_has_protected(hdr->frame_control)) |
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return false; |
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|
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hdrlen = ieee80211_hdrlen(hdr->frame_control); |
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ivpos = skb->data + hdrlen; iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; |
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return ieee80211_wep_weak_iv(iv, key->conf.keylen); |
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} |
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|
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ieee80211_rx_result |
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ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx) |
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{ |
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struct sk_buff *skb = rx->skb; struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
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if (!ieee80211_is_data(hdr->frame_control) && !ieee80211_is_auth(hdr->frame_control)) |
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return RX_CONTINUE; |
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|
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if (!(status->flag & RX_FLAG_DECRYPTED)) { |
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if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key)) |
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return RX_DROP_UNUSABLE; |
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} else if (!(status->flag & RX_FLAG_IV_STRIPPED)) { |
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ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); /* remove ICV */ |
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skb_trim(rx->skb, rx->skb->len - WEP_ICV_LEN); |
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} |
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return RX_CONTINUE; |
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} |
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|
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static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb) |
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{ |
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struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
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if (!info->control.hw_key) { |
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if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key, tx->key->conf.keylen, tx->key->conf.keyidx)) |
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return -1; |
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} else if (info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) { |
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if (!ieee80211_wep_add_iv(tx->local, skb, tx->key->conf.keylen, tx->key->conf.keyidx)) return -1; } |
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return 0; } |
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ieee80211_tx_result |
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ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx) |
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{ |
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struct sk_buff *skb; |
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|
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ieee80211_tx_set_protected(tx); |
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|
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skb = tx->skb; do { if (wep_encrypt_skb(tx, skb) < 0) { I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); return TX_DROP; |
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} |
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} while ((skb = skb->next)); |
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|
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return TX_CONTINUE; |
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} |