diff options
author | Jiri Benc <jbenc@suse.cz> | 2007-05-05 20:45:53 +0200 |
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committer | David S. Miller <davem@davemloft.net> | 2007-05-05 20:45:53 +0200 |
commit | f0706e828e96d0fa4e80c0d25aa98523f6d589a0 (patch) | |
tree | a03c7f94939d74c1e1b82fcd9a215871590d8b35 /net/mac80211/wep.c | |
parent | [MAC80211]: Add generic include/linux/ieee80211.h (diff) | |
download | linux-f0706e828e96d0fa4e80c0d25aa98523f6d589a0.tar.xz linux-f0706e828e96d0fa4e80c0d25aa98523f6d589a0.zip |
[MAC80211]: Add mac80211 wireless stack.
Add mac80211, the IEEE 802.11 software MAC layer.
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'net/mac80211/wep.c')
-rw-r--r-- | net/mac80211/wep.c | 328 |
1 files changed, 328 insertions, 0 deletions
diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c new file mode 100644 index 000000000000..1ad3d75281cc --- /dev/null +++ b/net/mac80211/wep.c @@ -0,0 +1,328 @@ +/* + * 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 <asm/scatterlist.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, WEP_IV_LEN); + + local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(local->wep_tx_tfm)) + return -ENOMEM; + + local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0, + CRYPTO_ALG_ASYNC); + if (IS_ERR(local->wep_rx_tfm)) { + crypto_free_blkcipher(local->wep_tx_tfm); + return -ENOMEM; + } + + return 0; +} + +void ieee80211_wep_free(struct ieee80211_local *local) +{ + crypto_free_blkcipher(local->wep_tx_tfm); + crypto_free_blkcipher(local->wep_rx_tfm); +} + +static inline int 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 1; + } + return 0; +} + + +void ieee80211_wep_get_iv(struct ieee80211_local *local, + struct ieee80211_key *key, u8 *iv) +{ + local->wep_iv++; + if (ieee80211_wep_weak_iv(local->wep_iv, key->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++ = key->keyidx << 6; +} + + +u8 * ieee80211_wep_add_iv(struct ieee80211_local *local, + struct sk_buff *skb, + struct ieee80211_key *key) +{ + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; + u16 fc; + int hdrlen; + u8 *newhdr; + + fc = le16_to_cpu(hdr->frame_control); + fc |= IEEE80211_FCTL_PROTECTED; + hdr->frame_control = cpu_to_le16(fc); + + if ((skb_headroom(skb) < WEP_IV_LEN || + skb_tailroom(skb) < WEP_ICV_LEN)) { + I802_DEBUG_INC(local->tx_expand_skb_head); + if (unlikely(pskb_expand_head(skb, WEP_IV_LEN, WEP_ICV_LEN, + GFP_ATOMIC))) + return NULL; + } + + hdrlen = ieee80211_get_hdrlen(fc); + newhdr = skb_push(skb, WEP_IV_LEN); + memmove(newhdr, newhdr + WEP_IV_LEN, hdrlen); + ieee80211_wep_get_iv(local, key, newhdr + hdrlen); + return newhdr + hdrlen; +} + + +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; + u16 fc; + int hdrlen; + + fc = le16_to_cpu(hdr->frame_control); + hdrlen = ieee80211_get_hdrlen(fc); + 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)) */ +void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key, + size_t klen, u8 *data, size_t data_len) +{ + struct blkcipher_desc desc = { .tfm = tfm }; + struct scatterlist sg; + __le32 *icv; + + icv = (__le32 *)(data + data_len); + *icv = cpu_to_le32(~crc32_le(~0, data, data_len)); + + crypto_blkcipher_setkey(tfm, rc4key, klen); + sg.page = virt_to_page(data); + sg.offset = offset_in_page(data); + sg.length = data_len + WEP_ICV_LEN; + crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length); +} + + +/* 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, + struct ieee80211_key *key) +{ + u32 klen; + u8 *rc4key, *iv; + size_t len; + + if (!key || key->alg != ALG_WEP) + return -1; + + klen = 3 + key->keylen; + rc4key = kmalloc(klen, GFP_ATOMIC); + if (!rc4key) + return -1; + + iv = ieee80211_wep_add_iv(local, skb, key); + if (!iv) { + kfree(rc4key); + return -1; + } + + 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) */ + memcpy(rc4key + 3, key->key, key->keylen); + + /* Add room for ICV */ + skb_put(skb, WEP_ICV_LEN); + + ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, klen, + iv + WEP_IV_LEN, len); + + kfree(rc4key); + + return 0; +} + + +/* 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_blkcipher *tfm, u8 *rc4key, + size_t klen, u8 *data, size_t data_len) +{ + struct blkcipher_desc desc = { .tfm = tfm }; + struct scatterlist sg; + __le32 crc; + + crypto_blkcipher_setkey(tfm, rc4key, klen); + sg.page = virt_to_page(data); + sg.offset = offset_in_page(data); + sg.length = data_len + WEP_ICV_LEN; + crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length); + + 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. + */ +int ieee80211_wep_decrypt(struct ieee80211_local *local, struct sk_buff *skb, + struct ieee80211_key *key) +{ + u32 klen; + u8 *rc4key; + u8 keyidx; + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; + u16 fc; + int hdrlen; + size_t len; + int ret = 0; + + fc = le16_to_cpu(hdr->frame_control); + if (!(fc & IEEE80211_FCTL_PROTECTED)) + return -1; + + hdrlen = ieee80211_get_hdrlen(fc); + + if (skb->len < 8 + hdrlen) + return -1; + + len = skb->len - hdrlen - 8; + + keyidx = skb->data[hdrlen + 3] >> 6; + + if (!key || keyidx != key->keyidx || key->alg != ALG_WEP) + return -1; + + klen = 3 + key->keylen; + + rc4key = kmalloc(klen, GFP_ATOMIC); + if (!rc4key) + return -1; + + /* 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->key, key->keylen); + + if (ieee80211_wep_decrypt_data(local->wep_rx_tfm, rc4key, klen, + skb->data + hdrlen + WEP_IV_LEN, + len)) { + printk(KERN_DEBUG "WEP decrypt failed (ICV)\n"); + ret = -1; + } + + kfree(rc4key); + + /* 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; +} + + +int ieee80211_wep_get_keyidx(struct sk_buff *skb) +{ + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; + u16 fc; + int hdrlen; + + fc = le16_to_cpu(hdr->frame_control); + if (!(fc & IEEE80211_FCTL_PROTECTED)) + return -1; + + hdrlen = ieee80211_get_hdrlen(fc); + + if (skb->len < 8 + hdrlen) + return -1; + + return skb->data[hdrlen + 3] >> 6; +} + + +u8 * ieee80211_wep_is_weak_iv(struct sk_buff *skb, struct ieee80211_key *key) +{ + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; + u16 fc; + int hdrlen; + u8 *ivpos; + u32 iv; + + fc = le16_to_cpu(hdr->frame_control); + if (!(fc & IEEE80211_FCTL_PROTECTED)) + return NULL; + + hdrlen = ieee80211_get_hdrlen(fc); + ivpos = skb->data + hdrlen; + iv = (ivpos[0] << 16) | (ivpos[1] << 8) | ivpos[2]; + + if (ieee80211_wep_weak_iv(iv, key->keylen)) + return ivpos; + + return NULL; +} |