![Joe Perches](/assets/img/avatar_default.png)
This is nicer than the MAC_FMT stuff. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: David S. Miller <davem@davemloft.net>
495 lines
12 KiB
C
495 lines
12 KiB
C
/*
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* Host AP crypt: host-based CCMP encryption implementation for Host AP driver
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*
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* Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi>
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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. See README and COPYING for
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* more details.
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*/
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/random.h>
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/if_ether.h>
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#include <linux/if_arp.h>
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#include <asm/string.h>
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#include <linux/wireless.h>
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#include <net/ieee80211.h>
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#include <linux/crypto.h>
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#include <asm/scatterlist.h>
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MODULE_AUTHOR("Jouni Malinen");
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MODULE_DESCRIPTION("Host AP crypt: CCMP");
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MODULE_LICENSE("GPL");
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#define AES_BLOCK_LEN 16
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#define CCMP_HDR_LEN 8
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#define CCMP_MIC_LEN 8
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#define CCMP_TK_LEN 16
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#define CCMP_PN_LEN 6
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struct ieee80211_ccmp_data {
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u8 key[CCMP_TK_LEN];
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int key_set;
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u8 tx_pn[CCMP_PN_LEN];
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u8 rx_pn[CCMP_PN_LEN];
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u32 dot11RSNAStatsCCMPFormatErrors;
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u32 dot11RSNAStatsCCMPReplays;
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u32 dot11RSNAStatsCCMPDecryptErrors;
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int key_idx;
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struct crypto_cipher *tfm;
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/* scratch buffers for virt_to_page() (crypto API) */
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u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
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tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
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u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
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};
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static inline void ieee80211_ccmp_aes_encrypt(struct crypto_cipher *tfm,
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const u8 pt[16], u8 ct[16])
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{
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crypto_cipher_encrypt_one(tfm, ct, pt);
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}
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static void *ieee80211_ccmp_init(int key_idx)
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{
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struct ieee80211_ccmp_data *priv;
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priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
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if (priv == NULL)
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goto fail;
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priv->key_idx = key_idx;
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priv->tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
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if (IS_ERR(priv->tfm)) {
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printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate "
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"crypto API aes\n");
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priv->tfm = NULL;
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goto fail;
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}
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return priv;
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fail:
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if (priv) {
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if (priv->tfm)
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crypto_free_cipher(priv->tfm);
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kfree(priv);
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}
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return NULL;
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}
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static void ieee80211_ccmp_deinit(void *priv)
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{
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struct ieee80211_ccmp_data *_priv = priv;
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if (_priv && _priv->tfm)
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crypto_free_cipher(_priv->tfm);
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kfree(priv);
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}
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static inline void xor_block(u8 * b, u8 * a, size_t len)
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{
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int i;
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for (i = 0; i < len; i++)
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b[i] ^= a[i];
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}
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static void ccmp_init_blocks(struct crypto_cipher *tfm,
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struct ieee80211_hdr_4addr *hdr,
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u8 * pn, size_t dlen, u8 * b0, u8 * auth, u8 * s0)
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{
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u8 *pos, qc = 0;
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size_t aad_len;
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u16 fc;
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int a4_included, qc_included;
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u8 aad[2 * AES_BLOCK_LEN];
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fc = le16_to_cpu(hdr->frame_ctl);
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a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
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(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
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qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
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(WLAN_FC_GET_STYPE(fc) & IEEE80211_STYPE_QOS_DATA));
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aad_len = 22;
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if (a4_included)
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aad_len += 6;
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if (qc_included) {
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pos = (u8 *) & hdr->addr4;
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if (a4_included)
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pos += 6;
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qc = *pos & 0x0f;
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aad_len += 2;
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}
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/* CCM Initial Block:
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* Flag (Include authentication header, M=3 (8-octet MIC),
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* L=1 (2-octet Dlen))
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* Nonce: 0x00 | A2 | PN
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* Dlen */
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b0[0] = 0x59;
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b0[1] = qc;
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memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
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memcpy(b0 + 8, pn, CCMP_PN_LEN);
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b0[14] = (dlen >> 8) & 0xff;
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b0[15] = dlen & 0xff;
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/* AAD:
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* FC with bits 4..6 and 11..13 masked to zero; 14 is always one
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* A1 | A2 | A3
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* SC with bits 4..15 (seq#) masked to zero
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* A4 (if present)
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* QC (if present)
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*/
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pos = (u8 *) hdr;
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aad[0] = 0; /* aad_len >> 8 */
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aad[1] = aad_len & 0xff;
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aad[2] = pos[0] & 0x8f;
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aad[3] = pos[1] & 0xc7;
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memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
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pos = (u8 *) & hdr->seq_ctl;
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aad[22] = pos[0] & 0x0f;
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aad[23] = 0; /* all bits masked */
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memset(aad + 24, 0, 8);
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if (a4_included)
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memcpy(aad + 24, hdr->addr4, ETH_ALEN);
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if (qc_included) {
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aad[a4_included ? 30 : 24] = qc;
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/* rest of QC masked */
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}
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/* Start with the first block and AAD */
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ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
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xor_block(auth, aad, AES_BLOCK_LEN);
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ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
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xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
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ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
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b0[0] &= 0x07;
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b0[14] = b0[15] = 0;
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ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
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}
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static int ieee80211_ccmp_hdr(struct sk_buff *skb, int hdr_len,
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u8 *aeskey, int keylen, void *priv)
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{
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struct ieee80211_ccmp_data *key = priv;
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int i;
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u8 *pos;
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if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
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return -1;
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if (aeskey != NULL && keylen >= CCMP_TK_LEN)
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memcpy(aeskey, key->key, CCMP_TK_LEN);
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pos = skb_push(skb, CCMP_HDR_LEN);
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memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
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pos += hdr_len;
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i = CCMP_PN_LEN - 1;
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while (i >= 0) {
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key->tx_pn[i]++;
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if (key->tx_pn[i] != 0)
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break;
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i--;
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}
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*pos++ = key->tx_pn[5];
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*pos++ = key->tx_pn[4];
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*pos++ = 0;
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*pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
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*pos++ = key->tx_pn[3];
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*pos++ = key->tx_pn[2];
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*pos++ = key->tx_pn[1];
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*pos++ = key->tx_pn[0];
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return CCMP_HDR_LEN;
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}
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static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
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{
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struct ieee80211_ccmp_data *key = priv;
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int data_len, i, blocks, last, len;
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u8 *pos, *mic;
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struct ieee80211_hdr_4addr *hdr;
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u8 *b0 = key->tx_b0;
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u8 *b = key->tx_b;
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u8 *e = key->tx_e;
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u8 *s0 = key->tx_s0;
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if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
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return -1;
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data_len = skb->len - hdr_len;
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len = ieee80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
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if (len < 0)
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return -1;
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pos = skb->data + hdr_len + CCMP_HDR_LEN;
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mic = skb_put(skb, CCMP_MIC_LEN);
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hdr = (struct ieee80211_hdr_4addr *)skb->data;
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ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
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blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
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last = data_len % AES_BLOCK_LEN;
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for (i = 1; i <= blocks; i++) {
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len = (i == blocks && last) ? last : AES_BLOCK_LEN;
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/* Authentication */
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xor_block(b, pos, len);
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ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
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/* Encryption, with counter */
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b0[14] = (i >> 8) & 0xff;
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b0[15] = i & 0xff;
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ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
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xor_block(pos, e, len);
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pos += len;
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}
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for (i = 0; i < CCMP_MIC_LEN; i++)
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mic[i] = b[i] ^ s0[i];
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return 0;
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}
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/*
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* deal with seq counter wrapping correctly.
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* refer to timer_after() for jiffies wrapping handling
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*/
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static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
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{
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u32 iv32_n, iv16_n;
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u32 iv32_o, iv16_o;
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iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
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iv16_n = (pn_n[4] << 8) | pn_n[5];
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iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
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iv16_o = (pn_o[4] << 8) | pn_o[5];
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if ((s32)iv32_n - (s32)iv32_o < 0 ||
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(iv32_n == iv32_o && iv16_n <= iv16_o))
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return 1;
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return 0;
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}
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static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
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{
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struct ieee80211_ccmp_data *key = priv;
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u8 keyidx, *pos;
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struct ieee80211_hdr_4addr *hdr;
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u8 *b0 = key->rx_b0;
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u8 *b = key->rx_b;
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u8 *a = key->rx_a;
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u8 pn[6];
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int i, blocks, last, len;
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size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
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u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
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DECLARE_MAC_BUF(mac);
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if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
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key->dot11RSNAStatsCCMPFormatErrors++;
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return -1;
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}
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hdr = (struct ieee80211_hdr_4addr *)skb->data;
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pos = skb->data + hdr_len;
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keyidx = pos[3];
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if (!(keyidx & (1 << 5))) {
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if (net_ratelimit()) {
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printk(KERN_DEBUG "CCMP: received packet without ExtIV"
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" flag from %s\n", print_mac(mac, hdr->addr2));
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}
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key->dot11RSNAStatsCCMPFormatErrors++;
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return -2;
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}
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keyidx >>= 6;
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if (key->key_idx != keyidx) {
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printk(KERN_DEBUG "CCMP: RX tkey->key_idx=%d frame "
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"keyidx=%d priv=%p\n", key->key_idx, keyidx, priv);
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return -6;
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}
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if (!key->key_set) {
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if (net_ratelimit()) {
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printk(KERN_DEBUG "CCMP: received packet from %s"
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" with keyid=%d that does not have a configured"
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" key\n", print_mac(mac, hdr->addr2), keyidx);
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}
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return -3;
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}
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pn[0] = pos[7];
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pn[1] = pos[6];
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pn[2] = pos[5];
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pn[3] = pos[4];
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pn[4] = pos[1];
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pn[5] = pos[0];
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pos += 8;
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if (ccmp_replay_check(pn, key->rx_pn)) {
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if (net_ratelimit()) {
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IEEE80211_DEBUG_DROP("CCMP: replay detected: STA=%s "
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"previous PN %02x%02x%02x%02x%02x%02x "
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"received PN %02x%02x%02x%02x%02x%02x\n",
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print_mac(mac, hdr->addr2),
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key->rx_pn[0], key->rx_pn[1], key->rx_pn[2],
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key->rx_pn[3], key->rx_pn[4], key->rx_pn[5],
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pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]);
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}
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key->dot11RSNAStatsCCMPReplays++;
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return -4;
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}
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ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
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xor_block(mic, b, CCMP_MIC_LEN);
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blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
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last = data_len % AES_BLOCK_LEN;
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for (i = 1; i <= blocks; i++) {
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len = (i == blocks && last) ? last : AES_BLOCK_LEN;
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/* Decrypt, with counter */
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b0[14] = (i >> 8) & 0xff;
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b0[15] = i & 0xff;
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ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
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xor_block(pos, b, len);
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/* Authentication */
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xor_block(a, pos, len);
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ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
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pos += len;
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}
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if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
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if (net_ratelimit()) {
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printk(KERN_DEBUG "CCMP: decrypt failed: STA="
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"%s\n", print_mac(mac, hdr->addr2));
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}
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key->dot11RSNAStatsCCMPDecryptErrors++;
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return -5;
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}
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memcpy(key->rx_pn, pn, CCMP_PN_LEN);
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/* Remove hdr and MIC */
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memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
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skb_pull(skb, CCMP_HDR_LEN);
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skb_trim(skb, skb->len - CCMP_MIC_LEN);
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return keyidx;
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}
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static int ieee80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
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{
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struct ieee80211_ccmp_data *data = priv;
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int keyidx;
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struct crypto_cipher *tfm = data->tfm;
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keyidx = data->key_idx;
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memset(data, 0, sizeof(*data));
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data->key_idx = keyidx;
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data->tfm = tfm;
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if (len == CCMP_TK_LEN) {
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memcpy(data->key, key, CCMP_TK_LEN);
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data->key_set = 1;
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if (seq) {
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data->rx_pn[0] = seq[5];
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data->rx_pn[1] = seq[4];
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data->rx_pn[2] = seq[3];
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data->rx_pn[3] = seq[2];
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data->rx_pn[4] = seq[1];
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data->rx_pn[5] = seq[0];
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}
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crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN);
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} else if (len == 0)
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data->key_set = 0;
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else
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return -1;
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return 0;
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}
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static int ieee80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
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{
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struct ieee80211_ccmp_data *data = priv;
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if (len < CCMP_TK_LEN)
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return -1;
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if (!data->key_set)
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return 0;
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memcpy(key, data->key, CCMP_TK_LEN);
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if (seq) {
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seq[0] = data->tx_pn[5];
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seq[1] = data->tx_pn[4];
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seq[2] = data->tx_pn[3];
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seq[3] = data->tx_pn[2];
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seq[4] = data->tx_pn[1];
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seq[5] = data->tx_pn[0];
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}
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return CCMP_TK_LEN;
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}
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static char *ieee80211_ccmp_print_stats(char *p, void *priv)
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{
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struct ieee80211_ccmp_data *ccmp = priv;
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p += sprintf(p, "key[%d] alg=CCMP key_set=%d "
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"tx_pn=%02x%02x%02x%02x%02x%02x "
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"rx_pn=%02x%02x%02x%02x%02x%02x "
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"format_errors=%d replays=%d decrypt_errors=%d\n",
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ccmp->key_idx, ccmp->key_set,
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ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2],
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ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5],
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ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2],
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ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5],
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ccmp->dot11RSNAStatsCCMPFormatErrors,
|
|
ccmp->dot11RSNAStatsCCMPReplays,
|
|
ccmp->dot11RSNAStatsCCMPDecryptErrors);
|
|
|
|
return p;
|
|
}
|
|
|
|
static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
|
|
.name = "CCMP",
|
|
.init = ieee80211_ccmp_init,
|
|
.deinit = ieee80211_ccmp_deinit,
|
|
.build_iv = ieee80211_ccmp_hdr,
|
|
.encrypt_mpdu = ieee80211_ccmp_encrypt,
|
|
.decrypt_mpdu = ieee80211_ccmp_decrypt,
|
|
.encrypt_msdu = NULL,
|
|
.decrypt_msdu = NULL,
|
|
.set_key = ieee80211_ccmp_set_key,
|
|
.get_key = ieee80211_ccmp_get_key,
|
|
.print_stats = ieee80211_ccmp_print_stats,
|
|
.extra_mpdu_prefix_len = CCMP_HDR_LEN,
|
|
.extra_mpdu_postfix_len = CCMP_MIC_LEN,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init ieee80211_crypto_ccmp_init(void)
|
|
{
|
|
return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
|
|
}
|
|
|
|
static void __exit ieee80211_crypto_ccmp_exit(void)
|
|
{
|
|
ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
|
|
}
|
|
|
|
module_init(ieee80211_crypto_ccmp_init);
|
|
module_exit(ieee80211_crypto_ccmp_exit);
|