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306 lines
8.3 KiB
306 lines
8.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Software WEP encryption implementation |
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* Copyright 2002, Jouni Malinen <[email protected]> |
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* Copyright 2003, Instant802 Networks, Inc. |
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*/ |
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#include <linux/netdevice.h> |
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#include <linux/types.h> |
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#include <linux/random.h> |
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#include <linux/compiler.h> |
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#include <linux/crc32.h> |
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#include <linux/crypto.h> |
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#include <linux/err.h> |
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#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> |
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#include "ieee80211_i.h" |
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#include "wep.h" |
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void ieee80211_wep_init(struct ieee80211_local *local) |
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{ |
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/* start WEP IV from a random value */ |
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get_random_bytes(&local->wep_iv, IEEE80211_WEP_IV_LEN); |
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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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/* |
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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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*/ |
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if ((iv & 0xff00) == 0xff00) { |
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u8 B = (iv >> 16) & 0xff; |
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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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{ |
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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; |
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if (!iv) |
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return; |
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*iv++ = (local->wep_iv >> 16) & 0xff; |
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*iv++ = (local->wep_iv >> 8) & 0xff; |
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*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, |
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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; |
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struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb); |
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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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if (WARN_ON(skb_headroom(skb) < IEEE80211_WEP_IV_LEN)) |
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return NULL; |
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hdrlen = ieee80211_hdrlen(hdr->frame_control); |
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newhdr = skb_push(skb, IEEE80211_WEP_IV_LEN); |
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memmove(newhdr, newhdr + IEEE80211_WEP_IV_LEN, hdrlen); |
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/* the HW only needs room for the IV, but not the actual IV */ |
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if (info->control.hw_key && |
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(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) |
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return newhdr + 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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} |
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static void ieee80211_wep_remove_iv(struct ieee80211_local *local, |
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struct sk_buff *skb, |
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struct ieee80211_key *key) |
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{ |
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
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unsigned int hdrlen; |
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hdrlen = ieee80211_hdrlen(hdr->frame_control); |
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memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen); |
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skb_pull(skb, IEEE80211_WEP_IV_LEN); |
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} |
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/* Perform WEP encryption using given key. data buffer must have tailroom |
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* for 4-byte ICV. data_len must not include this ICV. Note: this function |
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* does _not_ add IV. data = RC4(data | CRC32(data)) */ |
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int ieee80211_wep_encrypt_data(struct arc4_ctx *ctx, 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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icv = cpu_to_le32(~crc32_le(~0, data, data_len)); |
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put_unaligned(icv, (__le32 *)(data + data_len)); |
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arc4_setkey(ctx, rc4key, klen); |
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arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN); |
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memzero_explicit(ctx, sizeof(*ctx)); |
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return 0; |
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} |
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/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the |
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* beginning of the buffer 4 bytes of extra space (ICV) in the end of the |
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* buffer will be added. Both IV and ICV will be transmitted, so the |
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* payload length increases with 8 bytes. |
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* |
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* WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data)) |
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*/ |
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int ieee80211_wep_encrypt(struct ieee80211_local *local, |
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struct sk_buff *skb, |
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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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if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN)) |
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return -1; |
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iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx); |
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if (!iv) |
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return -1; |
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len = skb->len - (iv + IEEE80211_WEP_IV_LEN - skb->data); |
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/* Prepend 24-bit IV to RC4 key */ |
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memcpy(rc4key, iv, 3); |
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/* 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 */ |
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skb_put(skb, IEEE80211_WEP_ICV_LEN); |
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return ieee80211_wep_encrypt_data(&local->wep_tx_ctx, rc4key, keylen + 3, |
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iv + IEEE80211_WEP_IV_LEN, len); |
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} |
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/* Perform WEP decryption using given key. data buffer includes encrypted |
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* payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV. |
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* Return 0 on success and -1 on ICV mismatch. */ |
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int ieee80211_wep_decrypt_data(struct arc4_ctx *ctx, u8 *rc4key, |
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size_t klen, u8 *data, size_t data_len) |
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{ |
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__le32 crc; |
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arc4_setkey(ctx, rc4key, klen); |
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arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN); |
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memzero_explicit(ctx, sizeof(*ctx)); |
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crc = cpu_to_le32(~crc32_le(~0, data, data_len)); |
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if (memcmp(&crc, data + data_len, IEEE80211_WEP_ICV_LEN) != 0) |
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/* ICV mismatch */ |
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return -1; |
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return 0; |
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} |
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/* Perform WEP decryption on given skb. Buffer includes whole WEP part of |
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* the frame: IV (4 bytes), encrypted payload (including SNAP header), |
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* ICV (4 bytes). skb->len includes both IV and ICV. |
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* |
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* Returns 0 if frame was decrypted successfully and ICV was correct and -1 on |
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* failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload |
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* is moved to the beginning of the skb and skb length will be reduced. |
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*/ |
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static int ieee80211_wep_decrypt(struct ieee80211_local *local, |
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struct sk_buff *skb, |
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struct ieee80211_key *key) |
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{ |
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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; |
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unsigned int hdrlen; |
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size_t len; |
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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 + IEEE80211_WEP_IV_LEN + IEEE80211_WEP_ICV_LEN) |
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return -1; |
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len = skb->len - hdrlen - IEEE80211_WEP_IV_LEN - IEEE80211_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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/* Prepend 24-bit IV to RC4 key */ |
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memcpy(rc4key, skb->data + hdrlen, 3); |
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/* 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_ctx, rc4key, klen, |
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skb->data + hdrlen + |
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IEEE80211_WEP_IV_LEN, len)) |
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ret = -1; |
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/* Trim ICV */ |
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skb_trim(skb, skb->len - IEEE80211_WEP_ICV_LEN); |
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/* Remove IV */ |
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memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen); |
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skb_pull(skb, IEEE80211_WEP_IV_LEN); |
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return ret; |
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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; |
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struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); |
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struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; |
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__le16 fc = hdr->frame_control; |
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if (!ieee80211_is_data(fc) && !ieee80211_is_auth(fc)) |
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return RX_CONTINUE; |
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if (!(status->flag & RX_FLAG_DECRYPTED)) { |
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if (skb_linearize(rx->skb)) |
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return RX_DROP_UNUSABLE; |
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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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if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) + |
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IEEE80211_WEP_IV_LEN)) |
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return RX_DROP_UNUSABLE; |
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ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key); |
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/* remove ICV */ |
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if (!(status->flag & RX_FLAG_ICV_STRIPPED) && |
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pskb_trim(rx->skb, rx->skb->len - IEEE80211_WEP_ICV_LEN)) |
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return RX_DROP_UNUSABLE; |
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} |
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return RX_CONTINUE; |
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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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struct ieee80211_key_conf *hw_key = info->control.hw_key; |
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if (!hw_key) { |
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if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key, |
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tx->key->conf.keylen, |
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tx->key->conf.keyidx)) |
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return -1; |
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} else if ((hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) || |
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(hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) { |
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if (!ieee80211_wep_add_iv(tx->local, skb, |
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tx->key->conf.keylen, |
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tx->key->conf.keyidx)) |
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return -1; |
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} |
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return 0; |
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} |
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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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ieee80211_tx_set_protected(tx); |
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skb_queue_walk(&tx->skbs, skb) { |
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if (wep_encrypt_skb(tx, skb) < 0) { |
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I802_DEBUG_INC(tx->local->tx_handlers_drop_wep); |
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return TX_DROP; |
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} |
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} |
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return TX_CONTINUE; |
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}
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