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![Johannes Berg](/assets/img/avatar_default.png)
This reworks the key operation in cfg80211, and now only allows, from userspace, configuring keys (via nl80211) after the connection has been established (in managed mode), the IBSS been joined (in IBSS mode), at any time (in AP[_VLAN] modes) or never for all the other modes. In order to do shared key authentication correctly, it is now possible to give a WEP key to the AUTH command. To configure static WEP keys, these are given to the CONNECT or IBSS_JOIN command directly, for a userspace SME it is assumed it will configure it properly after the connection has been established. Since mac80211 used to check the default key in IBSS mode to see whether or not the network is protected, it needs an update in that area, as well as an update to make use of the WEP key passed to auth() for shared key authentication. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: John W. Linville <linville@tuxdriver.com>
339 lines
8.8 KiB
C
339 lines
8.8 KiB
C
/*
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* Software WEP encryption implementation
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* Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
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* Copyright 2003, Instant802 Networks, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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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 <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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int 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, WEP_IV_LEN);
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local->wep_tx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
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CRYPTO_ALG_ASYNC);
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if (IS_ERR(local->wep_tx_tfm))
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return PTR_ERR(local->wep_tx_tfm);
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local->wep_rx_tfm = crypto_alloc_blkcipher("ecb(arc4)", 0,
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CRYPTO_ALG_ASYNC);
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if (IS_ERR(local->wep_rx_tfm)) {
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crypto_free_blkcipher(local->wep_tx_tfm);
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return PTR_ERR(local->wep_rx_tfm);
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}
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return 0;
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}
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void ieee80211_wep_free(struct ieee80211_local *local)
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{
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crypto_free_blkcipher(local->wep_tx_tfm);
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crypto_free_blkcipher(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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/*
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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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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_tailroom(skb) < WEP_ICV_LEN ||
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skb_headroom(skb) < 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, WEP_IV_LEN);
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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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}
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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 + WEP_IV_LEN, skb->data, hdrlen);
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skb_pull(skb, 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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void ieee80211_wep_encrypt_data(struct crypto_blkcipher *tfm, u8 *rc4key,
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size_t klen, u8 *data, size_t data_len)
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{
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struct blkcipher_desc desc = { .tfm = tfm };
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struct scatterlist sg;
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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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crypto_blkcipher_setkey(tfm, rc4key, klen);
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sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
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crypto_blkcipher_encrypt(&desc, &sg, &sg, sg.length);
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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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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 + 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, WEP_ICV_LEN);
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ieee80211_wep_encrypt_data(local->wep_tx_tfm, rc4key, keylen + 3,
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iv + WEP_IV_LEN, len);
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return 0;
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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 crypto_blkcipher *tfm, u8 *rc4key,
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size_t klen, u8 *data, size_t data_len)
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{
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struct blkcipher_desc desc = { .tfm = tfm };
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struct scatterlist sg;
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__le32 crc;
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crypto_blkcipher_setkey(tfm, rc4key, klen);
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sg_init_one(&sg, data, data_len + WEP_ICV_LEN);
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crypto_blkcipher_decrypt(&desc, &sg, &sg, sg.length);
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crc = cpu_to_le32(~crc32_le(~0, data, data_len));
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if (memcmp(&crc, data + data_len, 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;
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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 + 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 || key->conf.alg != ALG_WEP)
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return -1;
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klen = 3 + key->conf.keylen;
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rc4key = kmalloc(klen, GFP_ATOMIC);
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if (!rc4key)
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return -1;
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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_tfm, rc4key, klen,
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skb->data + hdrlen + WEP_IV_LEN,
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len))
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ret = -1;
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kfree(rc4key);
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/* Trim ICV */
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skb_trim(skb, skb->len - WEP_ICV_LEN);
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/* Remove IV */
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memmove(skb->data + WEP_IV_LEN, skb->data, hdrlen);
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skb_pull(skb, WEP_IV_LEN);
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return ret;
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}
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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;
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unsigned int hdrlen;
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u8 *ivpos;
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u32 iv;
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if (!ieee80211_has_protected(hdr->frame_control))
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return false;
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hdrlen = ieee80211_hdrlen(hdr->frame_control);
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ivpos = skb->data + hdrlen;
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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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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 ieee80211_hdr *hdr = (struct ieee80211_hdr *)rx->skb->data;
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if (!ieee80211_is_data(hdr->frame_control) &&
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!ieee80211_is_auth(hdr->frame_control))
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return RX_CONTINUE;
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if (!(rx->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 (!(rx->status->flag & RX_FLAG_IV_STRIPPED)) {
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ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
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/* 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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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 (!(tx->key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE)) {
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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 {
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info->control.hw_key = &tx->key->conf;
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if (tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) {
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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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}
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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 = tx->skb;
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do {
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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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} while ((skb = skb->next));
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return TX_CONTINUE;
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}
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