// SPDX-License-Identifier: GPL-2.0-only
/*
* lib80211 crypt: host-based CCMP encryption implementation for lib80211
*
* Copyright (c) 2003-2004, Jouni Malinen <[email protected]>
* Copyright (c) 2008, John W. Linville <[email protected]>
*/
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <asm/string.h>
#include <linux/wireless.h>
#include <linux/ieee80211.h>
#include <linux/crypto.h>
#include <crypto/aead.h>
#include <net/lib80211.h>
MODULE_AUTHOR("Jouni Malinen");
MODULE_DESCRIPTION("Host AP crypt: CCMP");
MODULE_LICENSE("GPL");
#define AES_BLOCK_LEN 16
#define CCMP_HDR_LEN 8
#define CCMP_MIC_LEN 8
#define CCMP_TK_LEN 16
#define CCMP_PN_LEN 6
struct lib80211_ccmp_data {
u8 key[CCMP_TK_LEN];
int key_set;
u8 tx_pn[CCMP_PN_LEN];
u8 rx_pn[CCMP_PN_LEN];
u32 dot11RSNAStatsCCMPFormatErrors;
u32 dot11RSNAStatsCCMPReplays;
u32 dot11RSNAStatsCCMPDecryptErrors;
int key_idx;
struct crypto_aead *tfm;
/* scratch buffers for virt_to_page() (crypto API) */
u8 tx_aad[2 * AES_BLOCK_LEN];
u8 rx_aad[2 * AES_BLOCK_LEN];
};
static void *lib80211_ccmp_init(int key_idx)
{
struct lib80211_ccmp_data *priv;
priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
if (priv == NULL)
goto fail;
priv->key_idx = key_idx;
priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(priv->tfm)) {
priv->tfm = NULL;
goto fail;
}
return priv;
fail:
if (priv) {
if (priv->tfm)
crypto_free_aead(priv->tfm);
kfree(priv);
}
return NULL;
}
static void lib80211_ccmp_deinit(void *priv)
{
struct lib80211_ccmp_data *_priv = priv;
if (_priv && _priv->tfm)
crypto_free_aead(_priv->tfm);
kfree(priv);
}
static int ccmp_init_iv_and_aad(const struct ieee80211_hdr *hdr,
const u8 *pn, u8 *iv, u8 *aad)
{
u8 *pos, qc = 0;
size_t aad_len;
int a4_included, qc_included;
a4_included = ieee80211_has_a4(hdr->frame_control);
qc_included = ieee80211_is_data_qos(hdr->frame_control);
aad_len = 22;
if (a4_included)
aad_len += 6;
if (qc_included) {
pos = (u8 *) & hdr->addr4;
if (a4_included)
pos += 6;
qc = *pos & 0x0f;
aad_len += 2;
}
/* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
* mode authentication are not allowed to collide, yet both are derived
* from the same vector. We only set L := 1 here to indicate that the
* data size can be represented in (L+1) bytes. The CCM layer will take
* care of storing the data length in the top (L+1) bytes and setting
* and clearing the other bits as is required to derive the two IVs.
*/
iv[0] = 0x1;
/* Nonce: QC | A2 | PN */
iv[1] = qc;
memcpy(iv + 2, hdr->addr2, ETH_ALEN);
memcpy(iv + 8, pn, CCMP_PN_LEN);
/* AAD:
* FC with bits 4..6 and 11..13 masked to zero; 14 is always one
* A1 | A2 | A3
* SC with bits 4..15 (seq#) masked to zero
* A4 (if present)
* QC (if present)
*/
pos = (u8 *) hdr;
aad[0] = pos[0] & 0x8f;
aad[1] = pos[1] & 0xc7;
memcpy(aad + 2, &hdr->addrs, 3 * ETH_ALEN);
pos = (u8 *) & hdr->seq_ctrl;
aad[20] = pos[0] & 0x0f;
aad[21] = 0; /* all bits masked */
memset(aad + 22, 0, 8);
if (a4_included)
memcpy(aad + 22, hdr->addr4, ETH_ALEN);
if (qc_included) {
aad[a4_included ? 28 : 22] = qc;
/* rest of QC masked */
}
return aad_len;
}
static int lib80211_ccmp_hdr(struct sk_buff *skb, int hdr_len,
u8 *aeskey, int keylen, void *priv)
{
struct lib80211_ccmp_data *key = priv;
int i;
u8 *pos;
if (skb_headroom(skb) < CCMP_HDR_LEN || skb->len < hdr_len)
return -1;
if (aeskey != NULL && keylen >= CCMP_TK_LEN)
memcpy(aeskey, key->key, CCMP_TK_LEN);
pos = skb_push(skb, CCMP_HDR_LEN);
memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
pos += hdr_len;
i = CCMP_PN_LEN - 1;
while (i >= 0) {
key->tx_pn[i]++;
if (key->tx_pn[i] != 0)
break;
i--;
}
*pos++ = key->tx_pn[5];
*pos++ = key->tx_pn[4];
*pos++ = 0;
*pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */ ;
*pos++ = key->tx_pn[3];
*pos++ = key->tx_pn[2];
*pos++ = key->tx_pn[1];
*pos++ = key->tx_pn[0];
return CCMP_HDR_LEN;
}
static int lib80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
struct lib80211_ccmp_data *key = priv;
struct ieee80211_hdr *hdr;
struct aead_request *req;
struct scatterlist sg[2];
u8 *aad = key->tx_aad;
u8 iv[AES_BLOCK_LEN];
int len, data_len, aad_len;
int ret;
if (skb_tailroom(skb) < CCMP_MIC_LEN || skb->len < hdr_len)
return -1;
data_len = skb->len - hdr_len;
len = lib80211_ccmp_hdr(skb, hdr_len, NULL, 0, priv);
if (len < 0)
return -1;
req = aead_request_alloc(key->tfm, GFP_ATOMIC);
if (!req)
return -ENOMEM;
hdr = (struct ieee80211_hdr *)skb->data;
aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);
skb_put(skb, CCMP_MIC_LEN);
sg_init_table(sg, 2);
sg_set_buf(&sg[0], aad, aad_len);
sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
data_len + CCMP_MIC_LEN);
aead_request_set_callback(req, 0, NULL, NULL);
aead_request_set_ad(req, aad_len);
aead_request_set_crypt(req, sg, sg, data_len, iv);
ret = crypto_aead_encrypt(req);
aead_request_free(req);
return ret;
}
/*
* deal with seq counter wrapping correctly.
* refer to timer_after() for jiffies wrapping handling
*/
static inline int ccmp_replay_check(u8 *pn_n, u8 *pn_o)
{
u32 iv32_n, iv16_n;
u32 iv32_o, iv16_o;
iv32_n = (pn_n[0] << 24) | (pn_n[1] << 16) | (pn_n[2] << 8) | pn_n[3];
iv16_n = (pn_n[4] << 8) | pn_n[5];
iv32_o = (pn_o[0] << 24) | (pn_o[1] << 16) | (pn_o[2] << 8) | pn_o[3];
iv16_o = (pn_o[4] << 8) | pn_o[5];
if ((s32)iv32_n - (s32)iv32_o < 0 ||
(iv32_n == iv32_o && iv16_n <= iv16_o))
return 1;
return 0;
}
static int lib80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
{
struct lib80211_ccmp_data *key = priv;
u8 keyidx, *pos;
struct ieee80211_hdr *hdr;
struct aead_request *req;
struct scatterlist sg[2];
u8 *aad = key->rx_aad;
u8 iv[AES_BLOCK_LEN];
u8 pn[6];
int aad_len, ret;
size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
key->dot11RSNAStatsCCMPFormatErrors++;
return -1;
}
hdr = (struct ieee80211_hdr *)skb->data;
pos = skb->data + hdr_len;
keyidx = pos[3];
if (!(keyidx & (1 << 5))) {
net_dbg_ratelimited("CCMP: received packet without ExtIV flag from %pM\n",
hdr->addr2);
key->dot11RSNAStatsCCMPFormatErrors++;
return -2;
}
keyidx >>= 6;
if (key->key_idx != keyidx) {
net_dbg_ratelimited("CCMP: RX tkey->key_idx=%d frame keyidx=%d\n",
key->key_idx, keyidx);
return -6;
}
if (!key->key_set) {
net_dbg_ratelimited("CCMP: received packet from %pM with keyid=%d that does not have a configured key\n",
hdr->addr2, keyidx);
return -3;
}
pn[0] = pos[7];
pn[1] = pos[6];
pn[2] = pos[5];
pn[3] = pos[4];
pn[4] = pos[1];
pn[5] = pos[0];
pos += 8;
if (ccmp_replay_check(pn, key->rx_pn)) {
#ifdef CONFIG_LIB80211_DEBUG
net_dbg_ratelimited("CCMP: replay detected: STA=%pM previous PN %02x%02x%02x%02x%02x%02x received PN %02x%02x%02x%02x%02x%02x\n",
hdr->addr2,
key->rx_pn[0], key->rx_pn[1], key->rx_pn[2],
key->rx_pn[3], key->rx_pn[4], key->rx_pn[5],
pn[0], pn[1], pn[2], pn[3], pn[4], pn[5]);
#endif
key->dot11RSNAStatsCCMPReplays++;
return -4;
}
req = aead_request_alloc(key->tfm, GFP_ATOMIC);
if (!req)
return -ENOMEM;
aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);
sg_init_table(sg, 2);
sg_set_buf(&sg[0], aad, aad_len);
sg_set_buf(&sg[1], pos, data_len);
aead_request_set_callback(req, 0, NULL, NULL);
aead_request_set_ad(req, aad_len);
aead_request_set_crypt(req, sg, sg, data_len, iv);
ret = crypto_aead_decrypt(req);
aead_request_free(req);
if (ret) {
net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM (%d)\n",
hdr->addr2, ret);
key->dot11RSNAStatsCCMPDecryptErrors++;
return -5;
}
memcpy(key->rx_pn, pn, CCMP_PN_LEN);
/* Remove hdr and MIC */
memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
skb_pull(skb, CCMP_HDR_LEN);
skb_trim(skb, skb->len - CCMP_MIC_LEN);
return keyidx;
}
static int lib80211_ccmp_set_key(void *key, int len, u8 * seq, void *priv)
{
struct lib80211_ccmp_data *data = priv;
int keyidx;
struct crypto_aead *tfm = data->tfm;
keyidx = data->key_idx;
memset(data, 0, sizeof(*data));
data->key_idx = keyidx;
data->tfm = tfm;
if (len == CCMP_TK_LEN) {
memcpy(data->key, key, CCMP_TK_LEN);
data->key_set = 1;
if (seq) {
data->rx_pn[0] = seq[5];
data->rx_pn[1] = seq[4];
data->rx_pn[2] = seq[3];
data->rx_pn[3] = seq[2];
data->rx_pn[4] = seq[1];
data->rx_pn[5] = seq[0];
}
if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
return -1;
} else if (len == 0)
data->key_set = 0;
else
return -1;
return 0;
}
static int lib80211_ccmp_get_key(void *key, int len, u8 * seq, void *priv)
{
struct lib80211_ccmp_data *data = priv;
if (len < CCMP_TK_LEN)
return -1;
if (!data->key_set)
return 0;
memcpy(key, data->key, CCMP_TK_LEN);
if (seq) {
seq[0] = data->tx_pn[5];
seq[1] = data->tx_pn[4];
seq[2] = data->tx_pn[3];
seq[3] = data->tx_pn[2];
seq[4] = data->tx_pn[1];
seq[5] = data->tx_pn[0];
}
return CCMP_TK_LEN;
}
static void lib80211_ccmp_print_stats(struct seq_file *m, void *priv)
{
struct lib80211_ccmp_data *ccmp = priv;
seq_printf(m,
"key[%d] alg=CCMP key_set=%d "
"tx_pn=%02x%02x%02x%02x%02x%02x "
"rx_pn=%02x%02x%02x%02x%02x%02x "
"format_errors=%d replays=%d decrypt_errors=%d\n",
ccmp->key_idx, ccmp->key_set,
ccmp->tx_pn[0], ccmp->tx_pn[1], ccmp->tx_pn[2],
ccmp->tx_pn[3], ccmp->tx_pn[4], ccmp->tx_pn[5],
ccmp->rx_pn[0], ccmp->rx_pn[1], ccmp->rx_pn[2],
ccmp->rx_pn[3], ccmp->rx_pn[4], ccmp->rx_pn[5],
ccmp->dot11RSNAStatsCCMPFormatErrors,
ccmp->dot11RSNAStatsCCMPReplays,
ccmp->dot11RSNAStatsCCMPDecryptErrors);
}
static const struct lib80211_crypto_ops lib80211_crypt_ccmp = {
.name = "CCMP",
.init = lib80211_ccmp_init,
.deinit = lib80211_ccmp_deinit,
.encrypt_mpdu = lib80211_ccmp_encrypt,
.decrypt_mpdu = lib80211_ccmp_decrypt,
.encrypt_msdu = NULL,
.decrypt_msdu = NULL,
.set_key = lib80211_ccmp_set_key,
.get_key = lib80211_ccmp_get_key,
.print_stats = lib80211_ccmp_print_stats,
.extra_mpdu_prefix_len = CCMP_HDR_LEN,
.extra_mpdu_postfix_len = CCMP_MIC_LEN,
.owner = THIS_MODULE,
};
static int __init lib80211_crypto_ccmp_init(void)
{
return lib80211_register_crypto_ops(&lib80211_crypt_ccmp);
}
static void __exit lib80211_crypto_ccmp_exit(void)
{
lib80211_unregister_crypto_ops(&lib80211_crypt_ccmp);
}
module_init(lib80211_crypto_ccmp_init);
module_exit(lib80211_crypto_ccmp_exit);
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