mirror of
git://projects.qi-hardware.com/openwrt-xburst.git
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dc0b369ea1
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@2791 3c298f89-4303-0410-b956-a3cf2f4a3e73
424 lines
12 KiB
C
424 lines
12 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/config.h>
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#include <linux/version.h>
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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 <net/ieee80211.h>
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#include "ieee80211_i.h"
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#include "wep.h"
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static const __u32 crc32_table[256] = {
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0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
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0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
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0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
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0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
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0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
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0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
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0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
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0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
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0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
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0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
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0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
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0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
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0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
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0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
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0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
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0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
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0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
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0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
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0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
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0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
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0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
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0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
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0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
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0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
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0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
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0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
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0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
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0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
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0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
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0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
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0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
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0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
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0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
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0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
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0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
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0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
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0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
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0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
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0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
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0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
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0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
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0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
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0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
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0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
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0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
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0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
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0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
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0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
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0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
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0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
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0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
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0x2d02ef8dL
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};
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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, WEP_IV_LEN);
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}
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static inline int 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) {
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u8 B = (iv >> 16) & 0xff;
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if (B >= 3 && B < 3 + keylen)
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return 1;
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}
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return 0;
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}
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void ieee80211_wep_get_iv(struct ieee80211_local *local,
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struct ieee80211_key *key, 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, key->keylen))
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local->wep_iv += 0x0100;
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if (iv == NULL)
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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++ = key->keyidx << 6;
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}
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u8 * ieee80211_wep_add_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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u16 fc;
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int hdrlen;
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u8 *newhdr;
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fc = le16_to_cpu(hdr->frame_control);
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fc |= WLAN_FC_ISWEP;
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hdr->frame_control = cpu_to_le16(fc);
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if ((skb_headroom(skb) < WEP_IV_LEN ||
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skb_tailroom(skb) < WEP_ICV_LEN)) {
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I802_DEBUG_INC(local->tx_expand_skb_head);
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if (unlikely(pskb_expand_head(skb, WEP_IV_LEN, WEP_ICV_LEN,
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GFP_ATOMIC)))
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return NULL;
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}
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hdrlen = ieee80211_get_hdrlen(fc);
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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, key, newhdr + hdrlen);
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return newhdr + hdrlen;
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}
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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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u16 fc;
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int hdrlen;
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fc = le16_to_cpu(hdr->frame_control);
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hdrlen = ieee80211_get_hdrlen(fc);
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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(u8 *rc4key, size_t klen, u8 *data,
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size_t data_len)
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{
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u32 i, j, k, crc;
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u8 S[256];
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u8 kpos, *pos;
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#define S_SWAP(a,b) do { u8 t = S[a]; S[a] = S[b]; S[b] = t; } while(0)
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/* Setup RC4 state */
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for (i = 0; i < 256; i++)
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S[i] = i;
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j = 0;
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kpos = 0;
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for (i = 0; i < 256; i++) {
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j = (j + S[i] + rc4key[kpos]) & 0xff;
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kpos++;
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if (kpos >= klen)
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kpos = 0;
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S_SWAP(i, j);
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}
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/* Compute CRC32 over unencrypted data and apply RC4 to data */
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pos = data;
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crc = ~0;
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i = j = 0;
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for (k = 0; k < data_len; k++) {
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crc = crc32_table[(crc ^ *pos) & 0xff] ^ (crc >> 8);
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i = (i + 1) & 0xff;
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j = (j + S[i]) & 0xff;
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S_SWAP(i, j);
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*pos++ ^= S[(S[i] + S[j]) & 0xff];
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}
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crc = ~crc;
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/* Append little-endian CRC32 and encrypt it to produce ICV */
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pos[0] = crc;
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pos[1] = crc >> 8;
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pos[2] = crc >> 16;
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pos[3] = crc >> 24;
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for (k = 0; k < 4; k++) {
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i = (i + 1) & 0xff;
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j = (j + S[i]) & 0xff;
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S_SWAP(i, j);
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*pos++ ^= S[(S[i] + S[j]) & 0xff];
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}
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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, 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, *iv;
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size_t len;
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if (key == NULL || key->alg != ALG_WEP)
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return -1;
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klen = 3 + key->keylen;
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rc4key = kmalloc(klen, GFP_ATOMIC);
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if (rc4key == NULL)
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return -1;
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iv = ieee80211_wep_add_iv(local, skb, key);
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if (iv == NULL) {
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kfree(rc4key);
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return -1;
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}
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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->key, 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(rc4key, klen, iv + WEP_IV_LEN, len);
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kfree(rc4key);
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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(u8 *rc4key, size_t klen, u8 *data,
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size_t data_len)
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{
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u32 i, j, k, crc;
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u8 S[256];
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u8 kpos, *pos, crcbuf[WEP_ICV_LEN], *cpos;
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/* Setup RC4 state */
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for (i = 0; i < 256; i++)
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S[i] = i;
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j = 0;
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kpos = 0;
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for (i = 0; i < 256; i++) {
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j = (j + S[i] + rc4key[kpos]) & 0xff;
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kpos++;
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if (kpos >= klen)
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kpos = 0;
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S_SWAP(i, j);
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}
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/* Apply RC4 to data and compute CRC32 over decrypted data */
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pos = data;
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crc = ~0;
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i = j = 0;
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for (k = 0; k < data_len; k++) {
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i = (i + 1) & 0xff;
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j = (j + S[i]) & 0xff;
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S_SWAP(i, j);
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*pos ^= S[(S[i] + S[j]) & 0xff];
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crc = crc32_table[(crc ^ *pos++) & 0xff] ^ (crc >> 8);
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}
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crc = ~crc;
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/* Decrypt little-endian CRC32 and verify that it matches with the
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* received ICV */
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cpos = crcbuf;
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crcbuf[0] = crc;
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crcbuf[1] = crc >> 8;
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crcbuf[2] = crc >> 16;
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crcbuf[3] = crc >> 24;
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for (k = 0; k < WEP_ICV_LEN; k++) {
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i = (i + 1) & 0xff;
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j = (j + S[i]) & 0xff;
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S_SWAP(i, j);
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if (*cpos++ != (*pos++ ^ S[(S[i] + S[j]) & 0xff])) {
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/* ICV mismatch */
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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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/* 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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int ieee80211_wep_decrypt(struct ieee80211_local *local, 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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u16 fc;
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int hdrlen;
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size_t len;
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int ret = 0;
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fc = le16_to_cpu(hdr->frame_control);
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if (!(fc & WLAN_FC_ISWEP))
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return -1;
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hdrlen = ieee80211_get_hdrlen(fc);
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if (skb->len < 8 + hdrlen)
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return -1;
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len = skb->len - hdrlen - 8;
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keyidx = skb->data[hdrlen + 3] >> 6;
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if (key == NULL || keyidx != key->keyidx || key->alg != ALG_WEP)
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return -1;
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klen = 3 + key->keylen;
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rc4key = kmalloc(klen, GFP_ATOMIC);
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if (rc4key == NULL)
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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->key, key->keylen);
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if (ieee80211_wep_decrypt_data(rc4key, klen,
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skb->data + hdrlen + WEP_IV_LEN,
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len)) {
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printk(KERN_DEBUG "WEP decrypt failed (ICV)\n");
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ret = -1;
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}
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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);
|
|
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 & WLAN_FC_ISWEP))
|
|
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 & WLAN_FC_ISWEP))
|
|
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;
|
|
}
|