cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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wep.c (8497B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Software WEP encryption implementation
      4 * Copyright 2002, Jouni Malinen <jkmaline@cc.hut.fi>
      5 * Copyright 2003, Instant802 Networks, Inc.
      6 */
      7
      8#include <linux/netdevice.h>
      9#include <linux/types.h>
     10#include <linux/random.h>
     11#include <linux/compiler.h>
     12#include <linux/crc32.h>
     13#include <linux/crypto.h>
     14#include <linux/err.h>
     15#include <linux/mm.h>
     16#include <linux/scatterlist.h>
     17#include <linux/slab.h>
     18#include <asm/unaligned.h>
     19
     20#include <net/mac80211.h>
     21#include "ieee80211_i.h"
     22#include "wep.h"
     23
     24
     25void ieee80211_wep_init(struct ieee80211_local *local)
     26{
     27	/* start WEP IV from a random value */
     28	get_random_bytes(&local->wep_iv, IEEE80211_WEP_IV_LEN);
     29}
     30
     31static inline bool ieee80211_wep_weak_iv(u32 iv, int keylen)
     32{
     33	/*
     34	 * Fluhrer, Mantin, and Shamir have reported weaknesses in the
     35	 * key scheduling algorithm of RC4. At least IVs (KeyByte + 3,
     36	 * 0xff, N) can be used to speedup attacks, so avoid using them.
     37	 */
     38	if ((iv & 0xff00) == 0xff00) {
     39		u8 B = (iv >> 16) & 0xff;
     40		if (B >= 3 && B < 3 + keylen)
     41			return true;
     42	}
     43	return false;
     44}
     45
     46
     47static void ieee80211_wep_get_iv(struct ieee80211_local *local,
     48				 int keylen, int keyidx, u8 *iv)
     49{
     50	local->wep_iv++;
     51	if (ieee80211_wep_weak_iv(local->wep_iv, keylen))
     52		local->wep_iv += 0x0100;
     53
     54	if (!iv)
     55		return;
     56
     57	*iv++ = (local->wep_iv >> 16) & 0xff;
     58	*iv++ = (local->wep_iv >> 8) & 0xff;
     59	*iv++ = local->wep_iv & 0xff;
     60	*iv++ = keyidx << 6;
     61}
     62
     63
     64static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
     65				struct sk_buff *skb,
     66				int keylen, int keyidx)
     67{
     68	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
     69	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
     70	unsigned int hdrlen;
     71	u8 *newhdr;
     72
     73	hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
     74
     75	if (WARN_ON(skb_headroom(skb) < IEEE80211_WEP_IV_LEN))
     76		return NULL;
     77
     78	hdrlen = ieee80211_hdrlen(hdr->frame_control);
     79	newhdr = skb_push(skb, IEEE80211_WEP_IV_LEN);
     80	memmove(newhdr, newhdr + IEEE80211_WEP_IV_LEN, hdrlen);
     81
     82	/* the HW only needs room for the IV, but not the actual IV */
     83	if (info->control.hw_key &&
     84	    (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE))
     85		return newhdr + hdrlen;
     86
     87	ieee80211_wep_get_iv(local, keylen, keyidx, newhdr + hdrlen);
     88	return newhdr + hdrlen;
     89}
     90
     91
     92static void ieee80211_wep_remove_iv(struct ieee80211_local *local,
     93				    struct sk_buff *skb,
     94				    struct ieee80211_key *key)
     95{
     96	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
     97	unsigned int hdrlen;
     98
     99	hdrlen = ieee80211_hdrlen(hdr->frame_control);
    100	memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen);
    101	skb_pull(skb, IEEE80211_WEP_IV_LEN);
    102}
    103
    104
    105/* Perform WEP encryption using given key. data buffer must have tailroom
    106 * for 4-byte ICV. data_len must not include this ICV. Note: this function
    107 * does _not_ add IV. data = RC4(data | CRC32(data)) */
    108int ieee80211_wep_encrypt_data(struct arc4_ctx *ctx, u8 *rc4key,
    109			       size_t klen, u8 *data, size_t data_len)
    110{
    111	__le32 icv;
    112
    113	icv = cpu_to_le32(~crc32_le(~0, data, data_len));
    114	put_unaligned(icv, (__le32 *)(data + data_len));
    115
    116	arc4_setkey(ctx, rc4key, klen);
    117	arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN);
    118	memzero_explicit(ctx, sizeof(*ctx));
    119
    120	return 0;
    121}
    122
    123
    124/* Perform WEP encryption on given skb. 4 bytes of extra space (IV) in the
    125 * beginning of the buffer 4 bytes of extra space (ICV) in the end of the
    126 * buffer will be added. Both IV and ICV will be transmitted, so the
    127 * payload length increases with 8 bytes.
    128 *
    129 * WEP frame payload: IV + TX key idx, RC4(data), ICV = RC4(CRC32(data))
    130 */
    131int ieee80211_wep_encrypt(struct ieee80211_local *local,
    132			  struct sk_buff *skb,
    133			  const u8 *key, int keylen, int keyidx)
    134{
    135	u8 *iv;
    136	size_t len;
    137	u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
    138
    139	if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN))
    140		return -1;
    141
    142	iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
    143	if (!iv)
    144		return -1;
    145
    146	len = skb->len - (iv + IEEE80211_WEP_IV_LEN - skb->data);
    147
    148	/* Prepend 24-bit IV to RC4 key */
    149	memcpy(rc4key, iv, 3);
    150
    151	/* Copy rest of the WEP key (the secret part) */
    152	memcpy(rc4key + 3, key, keylen);
    153
    154	/* Add room for ICV */
    155	skb_put(skb, IEEE80211_WEP_ICV_LEN);
    156
    157	return ieee80211_wep_encrypt_data(&local->wep_tx_ctx, rc4key, keylen + 3,
    158					  iv + IEEE80211_WEP_IV_LEN, len);
    159}
    160
    161
    162/* Perform WEP decryption using given key. data buffer includes encrypted
    163 * payload, including 4-byte ICV, but _not_ IV. data_len must not include ICV.
    164 * Return 0 on success and -1 on ICV mismatch. */
    165int ieee80211_wep_decrypt_data(struct arc4_ctx *ctx, u8 *rc4key,
    166			       size_t klen, u8 *data, size_t data_len)
    167{
    168	__le32 crc;
    169
    170	arc4_setkey(ctx, rc4key, klen);
    171	arc4_crypt(ctx, data, data, data_len + IEEE80211_WEP_ICV_LEN);
    172	memzero_explicit(ctx, sizeof(*ctx));
    173
    174	crc = cpu_to_le32(~crc32_le(~0, data, data_len));
    175	if (memcmp(&crc, data + data_len, IEEE80211_WEP_ICV_LEN) != 0)
    176		/* ICV mismatch */
    177		return -1;
    178
    179	return 0;
    180}
    181
    182
    183/* Perform WEP decryption on given skb. Buffer includes whole WEP part of
    184 * the frame: IV (4 bytes), encrypted payload (including SNAP header),
    185 * ICV (4 bytes). skb->len includes both IV and ICV.
    186 *
    187 * Returns 0 if frame was decrypted successfully and ICV was correct and -1 on
    188 * failure. If frame is OK, IV and ICV will be removed, i.e., decrypted payload
    189 * is moved to the beginning of the skb and skb length will be reduced.
    190 */
    191static int ieee80211_wep_decrypt(struct ieee80211_local *local,
    192				 struct sk_buff *skb,
    193				 struct ieee80211_key *key)
    194{
    195	u32 klen;
    196	u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
    197	u8 keyidx;
    198	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
    199	unsigned int hdrlen;
    200	size_t len;
    201	int ret = 0;
    202
    203	if (!ieee80211_has_protected(hdr->frame_control))
    204		return -1;
    205
    206	hdrlen = ieee80211_hdrlen(hdr->frame_control);
    207	if (skb->len < hdrlen + IEEE80211_WEP_IV_LEN + IEEE80211_WEP_ICV_LEN)
    208		return -1;
    209
    210	len = skb->len - hdrlen - IEEE80211_WEP_IV_LEN - IEEE80211_WEP_ICV_LEN;
    211
    212	keyidx = skb->data[hdrlen + 3] >> 6;
    213
    214	if (!key || keyidx != key->conf.keyidx)
    215		return -1;
    216
    217	klen = 3 + key->conf.keylen;
    218
    219	/* Prepend 24-bit IV to RC4 key */
    220	memcpy(rc4key, skb->data + hdrlen, 3);
    221
    222	/* Copy rest of the WEP key (the secret part) */
    223	memcpy(rc4key + 3, key->conf.key, key->conf.keylen);
    224
    225	if (ieee80211_wep_decrypt_data(&local->wep_rx_ctx, rc4key, klen,
    226				       skb->data + hdrlen +
    227				       IEEE80211_WEP_IV_LEN, len))
    228		ret = -1;
    229
    230	/* Trim ICV */
    231	skb_trim(skb, skb->len - IEEE80211_WEP_ICV_LEN);
    232
    233	/* Remove IV */
    234	memmove(skb->data + IEEE80211_WEP_IV_LEN, skb->data, hdrlen);
    235	skb_pull(skb, IEEE80211_WEP_IV_LEN);
    236
    237	return ret;
    238}
    239
    240ieee80211_rx_result
    241ieee80211_crypto_wep_decrypt(struct ieee80211_rx_data *rx)
    242{
    243	struct sk_buff *skb = rx->skb;
    244	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
    245	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
    246	__le16 fc = hdr->frame_control;
    247
    248	if (!ieee80211_is_data(fc) && !ieee80211_is_auth(fc))
    249		return RX_CONTINUE;
    250
    251	if (!(status->flag & RX_FLAG_DECRYPTED)) {
    252		if (skb_linearize(rx->skb))
    253			return RX_DROP_UNUSABLE;
    254		if (ieee80211_wep_decrypt(rx->local, rx->skb, rx->key))
    255			return RX_DROP_UNUSABLE;
    256	} else if (!(status->flag & RX_FLAG_IV_STRIPPED)) {
    257		if (!pskb_may_pull(rx->skb, ieee80211_hdrlen(fc) +
    258					    IEEE80211_WEP_IV_LEN))
    259			return RX_DROP_UNUSABLE;
    260		ieee80211_wep_remove_iv(rx->local, rx->skb, rx->key);
    261		/* remove ICV */
    262		if (!(status->flag & RX_FLAG_ICV_STRIPPED) &&
    263		    pskb_trim(rx->skb, rx->skb->len - IEEE80211_WEP_ICV_LEN))
    264			return RX_DROP_UNUSABLE;
    265	}
    266
    267	return RX_CONTINUE;
    268}
    269
    270static int wep_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
    271{
    272	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
    273	struct ieee80211_key_conf *hw_key = info->control.hw_key;
    274
    275	if (!hw_key) {
    276		if (ieee80211_wep_encrypt(tx->local, skb, tx->key->conf.key,
    277					  tx->key->conf.keylen,
    278					  tx->key->conf.keyidx))
    279			return -1;
    280	} else if ((hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
    281		   (hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
    282		if (!ieee80211_wep_add_iv(tx->local, skb,
    283					  tx->key->conf.keylen,
    284					  tx->key->conf.keyidx))
    285			return -1;
    286	}
    287
    288	return 0;
    289}
    290
    291ieee80211_tx_result
    292ieee80211_crypto_wep_encrypt(struct ieee80211_tx_data *tx)
    293{
    294	struct sk_buff *skb;
    295
    296	ieee80211_tx_set_protected(tx);
    297
    298	skb_queue_walk(&tx->skbs, skb) {
    299		if (wep_encrypt_skb(tx, skb) < 0) {
    300			I802_DEBUG_INC(tx->local->tx_handlers_drop_wep);
    301			return TX_DROP;
    302		}
    303	}
    304
    305	return TX_CONTINUE;
    306}