| /* |
| * 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 <crypto/skcipher.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/slab.h> |
| #include <linux/random.h> |
| #include <linux/skbuff.h> |
| #include <linux/string.h> |
| #include "rtllib.h" |
| |
| #include <linux/scatterlist.h> |
| #include <linux/crc32.h> |
| |
| 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_skcipher *tx_tfm; |
| struct crypto_skcipher *rx_tfm; |
| }; |
| |
| |
| static void *prism2_wep_init(int keyidx) |
| { |
| struct prism2_wep_data *priv; |
| |
| priv = kzalloc(sizeof(*priv), GFP_ATOMIC); |
| if (priv == NULL) |
| goto fail; |
| priv->key_idx = keyidx; |
| |
| priv->tx_tfm = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); |
| if (IS_ERR(priv->tx_tfm)) { |
| pr_debug("rtllib_crypt_wep: could not allocate crypto API arc4\n"); |
| priv->tx_tfm = NULL; |
| goto fail; |
| } |
| priv->rx_tfm = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); |
| if (IS_ERR(priv->rx_tfm)) { |
| pr_debug("rtllib_crypt_wep: could not allocate crypto API arc4\n"); |
| priv->rx_tfm = NULL; |
| goto fail; |
| } |
| |
| /* start WEP IV from a random value */ |
| get_random_bytes(&priv->iv, 4); |
| |
| return priv; |
| |
| fail: |
| if (priv) { |
| crypto_free_skcipher(priv->tx_tfm); |
| crypto_free_skcipher(priv->rx_tfm); |
| kfree(priv); |
| } |
| return NULL; |
| } |
| |
| |
| static void prism2_wep_deinit(void *priv) |
| { |
| struct prism2_wep_data *_priv = priv; |
| |
| if (_priv) { |
| crypto_free_skcipher(_priv->tx_tfm); |
| crypto_free_skcipher(_priv->rx_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 klen, len; |
| u8 key[WEP_KEY_LEN + 3]; |
| u8 *pos; |
| struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + |
| MAX_DEV_ADDR_SIZE); |
| u32 crc; |
| u8 *icv; |
| struct scatterlist sg; |
| int err; |
| |
| if (skb_headroom(skb) < 4 || skb_tailroom(skb) < 4 || |
| skb->len < hdr_len){ |
| pr_err("Error!!! headroom=%d tailroom=%d skblen=%d hdr_len=%d\n", |
| skb_headroom(skb), skb_tailroom(skb), 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); |
| |
| if (!tcb_desc->bHwSec) { |
| SKCIPHER_REQUEST_ON_STACK(req, wep->tx_tfm); |
| |
| /* 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; |
| |
| sg_init_one(&sg, pos, len+4); |
| crypto_skcipher_setkey(wep->tx_tfm, key, klen); |
| skcipher_request_set_tfm(req, wep->tx_tfm); |
| skcipher_request_set_callback(req, 0, NULL, NULL); |
| skcipher_request_set_crypt(req, &sg, &sg, len + 4, NULL); |
| err = crypto_skcipher_encrypt(req); |
| skcipher_request_zero(req); |
| return err; |
| } |
| |
| return 0; |
| } |
| |
| |
| /* Perform WEP decryption on given struct 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 klen, plen; |
| u8 key[WEP_KEY_LEN + 3]; |
| u8 keyidx, *pos; |
| struct cb_desc *tcb_desc = (struct cb_desc *)(skb->cb + |
| MAX_DEV_ADDR_SIZE); |
| u32 crc; |
| u8 icv[4]; |
| struct scatterlist sg; |
| int err; |
| |
| 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; |
| |
| if (!tcb_desc->bHwSec) { |
| SKCIPHER_REQUEST_ON_STACK(req, wep->rx_tfm); |
| |
| sg_init_one(&sg, pos, plen+4); |
| crypto_skcipher_setkey(wep->rx_tfm, key, klen); |
| skcipher_request_set_tfm(req, wep->rx_tfm); |
| skcipher_request_set_callback(req, 0, NULL, NULL); |
| skcipher_request_set_crypt(req, &sg, &sg, plen + 4, NULL); |
| err = crypto_skcipher_decrypt(req); |
| skcipher_request_zero(req); |
| if (err) |
| return -7; |
| 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 void prism2_wep_print_stats(struct seq_file *m, void *priv) |
| { |
| struct prism2_wep_data *wep = priv; |
| |
| seq_printf(m, "key[%d] alg=WEP len=%d\n", wep->key_idx, wep->key_len); |
| } |
| |
| static struct lib80211_crypto_ops rtllib_crypt_wep = { |
| .name = "R-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_mpdu_prefix_len = 4, /* IV */ |
| .extra_mpdu_postfix_len = 4, /* ICV */ |
| .owner = THIS_MODULE, |
| }; |
| |
| |
| static int __init rtllib_crypto_wep_init(void) |
| { |
| return lib80211_register_crypto_ops(&rtllib_crypt_wep); |
| } |
| |
| |
| static void __exit rtllib_crypto_wep_exit(void) |
| { |
| lib80211_unregister_crypto_ops(&rtllib_crypt_wep); |
| } |
| |
| module_init(rtllib_crypto_wep_init); |
| module_exit(rtllib_crypto_wep_exit); |
| |
| MODULE_LICENSE("GPL"); |