| /* |
| * lib80211 crypt: host-based CCMP encryption implementation for lib80211 |
| * |
| * Copyright (c) 2003-2004, Jouni Malinen <j@w1.fi> |
| * Copyright (c) 2008, John W. Linville <linville@tuxdriver.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. See README and COPYING for |
| * more details. |
| */ |
| |
| #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 <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_cipher *tfm; |
| |
| /* scratch buffers for virt_to_page() (crypto API) */ |
| u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN], |
| tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN]; |
| u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN]; |
| }; |
| |
| static inline void lib80211_ccmp_aes_encrypt(struct crypto_cipher *tfm, |
| const u8 pt[16], u8 ct[16]) |
| { |
| crypto_cipher_encrypt_one(tfm, ct, pt); |
| } |
| |
| 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_cipher("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_cipher(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_cipher(_priv->tfm); |
| kfree(priv); |
| } |
| |
| static inline void xor_block(u8 * b, u8 * a, size_t len) |
| { |
| int i; |
| for (i = 0; i < len; i++) |
| b[i] ^= a[i]; |
| } |
| |
| static void ccmp_init_blocks(struct crypto_cipher *tfm, |
| struct ieee80211_hdr *hdr, |
| u8 * pn, size_t dlen, u8 * b0, u8 * auth, u8 * s0) |
| { |
| u8 *pos, qc = 0; |
| size_t aad_len; |
| int a4_included, qc_included; |
| u8 aad[2 * AES_BLOCK_LEN]; |
| |
| 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; |
| } |
| |
| /* CCM Initial Block: |
| * Flag (Include authentication header, M=3 (8-octet MIC), |
| * L=1 (2-octet Dlen)) |
| * Nonce: 0x00 | A2 | PN |
| * Dlen */ |
| b0[0] = 0x59; |
| b0[1] = qc; |
| memcpy(b0 + 2, hdr->addr2, ETH_ALEN); |
| memcpy(b0 + 8, pn, CCMP_PN_LEN); |
| b0[14] = (dlen >> 8) & 0xff; |
| b0[15] = dlen & 0xff; |
| |
| /* 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] = 0; /* aad_len >> 8 */ |
| aad[1] = aad_len & 0xff; |
| aad[2] = pos[0] & 0x8f; |
| aad[3] = pos[1] & 0xc7; |
| memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN); |
| pos = (u8 *) & hdr->seq_ctrl; |
| aad[22] = pos[0] & 0x0f; |
| aad[23] = 0; /* all bits masked */ |
| memset(aad + 24, 0, 8); |
| if (a4_included) |
| memcpy(aad + 24, hdr->addr4, ETH_ALEN); |
| if (qc_included) { |
| aad[a4_included ? 30 : 24] = qc; |
| /* rest of QC masked */ |
| } |
| |
| /* Start with the first block and AAD */ |
| lib80211_ccmp_aes_encrypt(tfm, b0, auth); |
| xor_block(auth, aad, AES_BLOCK_LEN); |
| lib80211_ccmp_aes_encrypt(tfm, auth, auth); |
| xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN); |
| lib80211_ccmp_aes_encrypt(tfm, auth, auth); |
| b0[0] &= 0x07; |
| b0[14] = b0[15] = 0; |
| lib80211_ccmp_aes_encrypt(tfm, b0, s0); |
| } |
| |
| 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; |
| int data_len, i, blocks, last, len; |
| u8 *pos, *mic; |
| struct ieee80211_hdr *hdr; |
| u8 *b0 = key->tx_b0; |
| u8 *b = key->tx_b; |
| u8 *e = key->tx_e; |
| u8 *s0 = key->tx_s0; |
| |
| 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; |
| |
| pos = skb->data + hdr_len + CCMP_HDR_LEN; |
| hdr = (struct ieee80211_hdr *)skb->data; |
| ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0); |
| |
| blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); |
| last = data_len % AES_BLOCK_LEN; |
| |
| for (i = 1; i <= blocks; i++) { |
| len = (i == blocks && last) ? last : AES_BLOCK_LEN; |
| /* Authentication */ |
| xor_block(b, pos, len); |
| lib80211_ccmp_aes_encrypt(key->tfm, b, b); |
| /* Encryption, with counter */ |
| b0[14] = (i >> 8) & 0xff; |
| b0[15] = i & 0xff; |
| lib80211_ccmp_aes_encrypt(key->tfm, b0, e); |
| xor_block(pos, e, len); |
| pos += len; |
| } |
| |
| mic = skb_put(skb, CCMP_MIC_LEN); |
| for (i = 0; i < CCMP_MIC_LEN; i++) |
| mic[i] = b[i] ^ s0[i]; |
| |
| return 0; |
| } |
| |
| /* |
| * 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; |
| u8 *b0 = key->rx_b0; |
| u8 *b = key->rx_b; |
| u8 *a = key->rx_a; |
| u8 pn[6]; |
| int i, blocks, last, len; |
| size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN; |
| u8 *mic = skb->data + skb->len - CCMP_MIC_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 CPTCFG_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; |
| } |
| |
| ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b); |
| xor_block(mic, b, CCMP_MIC_LEN); |
| |
| blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN); |
| last = data_len % AES_BLOCK_LEN; |
| |
| for (i = 1; i <= blocks; i++) { |
| len = (i == blocks && last) ? last : AES_BLOCK_LEN; |
| /* Decrypt, with counter */ |
| b0[14] = (i >> 8) & 0xff; |
| b0[15] = i & 0xff; |
| lib80211_ccmp_aes_encrypt(key->tfm, b0, b); |
| xor_block(pos, b, len); |
| /* Authentication */ |
| xor_block(a, pos, len); |
| lib80211_ccmp_aes_encrypt(key->tfm, a, a); |
| pos += len; |
| } |
| |
| if (memcmp(mic, a, CCMP_MIC_LEN) != 0) { |
| net_dbg_ratelimited("CCMP: decrypt failed: STA=%pM\n", |
| hdr->addr2); |
| 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_cipher *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]; |
| } |
| crypto_cipher_setkey(data->tfm, data->key, CCMP_TK_LEN); |
| } 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 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); |