| /* |
| * FILS AEAD for (Re)Association Request/Response frames |
| * Copyright 2016, Qualcomm Atheros, Inc. |
| * |
| * 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. |
| */ |
| |
| #include <crypto/aes.h> |
| #include <crypto/algapi.h> |
| #include <crypto/hash.h> |
| #include <crypto/skcipher.h> |
| |
| #include "ieee80211_i.h" |
| #include "aes_cmac.h" |
| #include "fils_aead.h" |
| |
| static void gf_mulx(u8 *pad) |
| { |
| u64 a = get_unaligned_be64(pad); |
| u64 b = get_unaligned_be64(pad + 8); |
| |
| put_unaligned_be64((a << 1) | (b >> 63), pad); |
| put_unaligned_be64((b << 1) ^ ((a >> 63) ? 0x87 : 0), pad + 8); |
| } |
| |
| static int aes_s2v(struct crypto_shash *tfm, |
| size_t num_elem, const u8 *addr[], size_t len[], u8 *v) |
| { |
| u8 d[AES_BLOCK_SIZE], tmp[AES_BLOCK_SIZE] = {}; |
| SHASH_DESC_ON_STACK(desc, tfm); |
| size_t i; |
| |
| desc->tfm = tfm; |
| |
| /* D = AES-CMAC(K, <zero>) */ |
| crypto_shash_digest(desc, tmp, AES_BLOCK_SIZE, d); |
| |
| for (i = 0; i < num_elem - 1; i++) { |
| /* D = dbl(D) xor AES_CMAC(K, Si) */ |
| gf_mulx(d); /* dbl */ |
| crypto_shash_digest(desc, addr[i], len[i], tmp); |
| crypto_xor(d, tmp, AES_BLOCK_SIZE); |
| } |
| |
| crypto_shash_init(desc); |
| |
| if (len[i] >= AES_BLOCK_SIZE) { |
| /* len(Sn) >= 128 */ |
| /* T = Sn xorend D */ |
| crypto_shash_update(desc, addr[i], len[i] - AES_BLOCK_SIZE); |
| crypto_xor(d, addr[i] + len[i] - AES_BLOCK_SIZE, |
| AES_BLOCK_SIZE); |
| } else { |
| /* len(Sn) < 128 */ |
| /* T = dbl(D) xor pad(Sn) */ |
| gf_mulx(d); /* dbl */ |
| crypto_xor(d, addr[i], len[i]); |
| d[len[i]] ^= 0x80; |
| } |
| /* V = AES-CMAC(K, T) */ |
| crypto_shash_finup(desc, d, AES_BLOCK_SIZE, v); |
| |
| return 0; |
| } |
| |
| /* Note: addr[] and len[] needs to have one extra slot at the end. */ |
| static int aes_siv_encrypt(const u8 *key, size_t key_len, |
| const u8 *plain, size_t plain_len, |
| size_t num_elem, const u8 *addr[], |
| size_t len[], u8 *out) |
| { |
| u8 v[AES_BLOCK_SIZE]; |
| struct crypto_shash *tfm; |
| struct crypto_skcipher *tfm2; |
| struct skcipher_request *req; |
| int res; |
| struct scatterlist src[1], dst[1]; |
| u8 *tmp; |
| |
| key_len /= 2; /* S2V key || CTR key */ |
| |
| addr[num_elem] = plain; |
| len[num_elem] = plain_len; |
| num_elem++; |
| |
| /* S2V */ |
| |
| tfm = crypto_alloc_shash("cmac(aes)", 0, 0); |
| if (IS_ERR(tfm)) |
| return PTR_ERR(tfm); |
| /* K1 for S2V */ |
| res = crypto_shash_setkey(tfm, key, key_len); |
| if (!res) |
| res = aes_s2v(tfm, num_elem, addr, len, v); |
| crypto_free_shash(tfm); |
| if (res) |
| return res; |
| |
| /* Use a temporary buffer of the plaintext to handle need for |
| * overwriting this during AES-CTR. |
| */ |
| tmp = kmemdup(plain, plain_len, GFP_KERNEL); |
| if (!tmp) |
| return -ENOMEM; |
| |
| /* IV for CTR before encrypted data */ |
| memcpy(out, v, AES_BLOCK_SIZE); |
| |
| /* Synthetic IV to be used as the initial counter in CTR: |
| * Q = V bitand (1^64 || 0^1 || 1^31 || 0^1 || 1^31) |
| */ |
| v[8] &= 0x7f; |
| v[12] &= 0x7f; |
| |
| /* CTR */ |
| |
| tfm2 = crypto_alloc_skcipher("ctr(aes)", 0, CRYPTO_ALG_ASYNC); |
| if (IS_ERR(tfm2)) { |
| kfree(tmp); |
| return PTR_ERR(tfm2); |
| } |
| /* K2 for CTR */ |
| res = crypto_skcipher_setkey(tfm2, key + key_len, key_len); |
| if (res) |
| goto fail; |
| |
| req = skcipher_request_alloc(tfm2, GFP_KERNEL); |
| if (!req) { |
| res = -ENOMEM; |
| goto fail; |
| } |
| |
| sg_init_one(src, tmp, plain_len); |
| sg_init_one(dst, out + AES_BLOCK_SIZE, plain_len); |
| skcipher_request_set_crypt(req, src, dst, plain_len, v); |
| res = crypto_skcipher_encrypt(req); |
| skcipher_request_free(req); |
| fail: |
| kfree(tmp); |
| crypto_free_skcipher(tfm2); |
| return res; |
| } |
| |
| /* Note: addr[] and len[] needs to have one extra slot at the end. */ |
| static int aes_siv_decrypt(const u8 *key, size_t key_len, |
| const u8 *iv_crypt, size_t iv_c_len, |
| size_t num_elem, const u8 *addr[], size_t len[], |
| u8 *out) |
| { |
| struct crypto_shash *tfm; |
| struct crypto_skcipher *tfm2; |
| struct skcipher_request *req; |
| struct scatterlist src[1], dst[1]; |
| size_t crypt_len; |
| int res; |
| u8 frame_iv[AES_BLOCK_SIZE], iv[AES_BLOCK_SIZE]; |
| u8 check[AES_BLOCK_SIZE]; |
| |
| crypt_len = iv_c_len - AES_BLOCK_SIZE; |
| key_len /= 2; /* S2V key || CTR key */ |
| addr[num_elem] = out; |
| len[num_elem] = crypt_len; |
| num_elem++; |
| |
| memcpy(iv, iv_crypt, AES_BLOCK_SIZE); |
| memcpy(frame_iv, iv_crypt, AES_BLOCK_SIZE); |
| |
| /* Synthetic IV to be used as the initial counter in CTR: |
| * Q = V bitand (1^64 || 0^1 || 1^31 || 0^1 || 1^31) |
| */ |
| iv[8] &= 0x7f; |
| iv[12] &= 0x7f; |
| |
| /* CTR */ |
| |
| tfm2 = crypto_alloc_skcipher("ctr(aes)", 0, CRYPTO_ALG_ASYNC); |
| if (IS_ERR(tfm2)) |
| return PTR_ERR(tfm2); |
| /* K2 for CTR */ |
| res = crypto_skcipher_setkey(tfm2, key + key_len, key_len); |
| if (res) { |
| crypto_free_skcipher(tfm2); |
| return res; |
| } |
| |
| req = skcipher_request_alloc(tfm2, GFP_KERNEL); |
| if (!req) { |
| crypto_free_skcipher(tfm2); |
| return -ENOMEM; |
| } |
| |
| sg_init_one(src, iv_crypt + AES_BLOCK_SIZE, crypt_len); |
| sg_init_one(dst, out, crypt_len); |
| skcipher_request_set_crypt(req, src, dst, crypt_len, iv); |
| res = crypto_skcipher_decrypt(req); |
| skcipher_request_free(req); |
| crypto_free_skcipher(tfm2); |
| if (res) |
| return res; |
| |
| /* S2V */ |
| |
| tfm = crypto_alloc_shash("cmac(aes)", 0, 0); |
| if (IS_ERR(tfm)) |
| return PTR_ERR(tfm); |
| /* K1 for S2V */ |
| res = crypto_shash_setkey(tfm, key, key_len); |
| if (!res) |
| res = aes_s2v(tfm, num_elem, addr, len, check); |
| crypto_free_shash(tfm); |
| if (res) |
| return res; |
| if (memcmp(check, frame_iv, AES_BLOCK_SIZE) != 0) |
| return -EINVAL; |
| return 0; |
| } |
| |
| int fils_encrypt_assoc_req(struct sk_buff *skb, |
| struct ieee80211_mgd_assoc_data *assoc_data) |
| { |
| struct ieee80211_mgmt *mgmt = (void *)skb->data; |
| u8 *capab, *ies, *encr; |
| const u8 *addr[5 + 1], *session; |
| size_t len[5 + 1]; |
| size_t crypt_len; |
| |
| if (ieee80211_is_reassoc_req(mgmt->frame_control)) { |
| capab = (u8 *)&mgmt->u.reassoc_req.capab_info; |
| ies = mgmt->u.reassoc_req.variable; |
| } else { |
| capab = (u8 *)&mgmt->u.assoc_req.capab_info; |
| ies = mgmt->u.assoc_req.variable; |
| } |
| |
| session = cfg80211_find_ext_ie(WLAN_EID_EXT_FILS_SESSION, |
| ies, skb->data + skb->len - ies); |
| if (!session || session[1] != 1 + 8) |
| return -EINVAL; |
| /* encrypt after FILS Session element */ |
| encr = (u8 *)session + 2 + 1 + 8; |
| |
| /* AES-SIV AAD vectors */ |
| |
| /* The STA's MAC address */ |
| addr[0] = mgmt->sa; |
| len[0] = ETH_ALEN; |
| /* The AP's BSSID */ |
| addr[1] = mgmt->da; |
| len[1] = ETH_ALEN; |
| /* The STA's nonce */ |
| addr[2] = assoc_data->fils_nonces; |
| len[2] = FILS_NONCE_LEN; |
| /* The AP's nonce */ |
| addr[3] = &assoc_data->fils_nonces[FILS_NONCE_LEN]; |
| len[3] = FILS_NONCE_LEN; |
| /* The (Re)Association Request frame from the Capability Information |
| * field to the FILS Session element (both inclusive). |
| */ |
| addr[4] = capab; |
| len[4] = encr - capab; |
| |
| crypt_len = skb->data + skb->len - encr; |
| skb_put(skb, AES_BLOCK_SIZE); |
| return aes_siv_encrypt(assoc_data->fils_kek, assoc_data->fils_kek_len, |
| encr, crypt_len, 5, addr, len, encr); |
| } |
| |
| int fils_decrypt_assoc_resp(struct ieee80211_sub_if_data *sdata, |
| u8 *frame, size_t *frame_len, |
| struct ieee80211_mgd_assoc_data *assoc_data) |
| { |
| struct ieee80211_mgmt *mgmt = (void *)frame; |
| u8 *capab, *ies, *encr; |
| const u8 *addr[5 + 1], *session; |
| size_t len[5 + 1]; |
| int res; |
| size_t crypt_len; |
| |
| if (*frame_len < 24 + 6) |
| return -EINVAL; |
| |
| capab = (u8 *)&mgmt->u.assoc_resp.capab_info; |
| ies = mgmt->u.assoc_resp.variable; |
| session = cfg80211_find_ext_ie(WLAN_EID_EXT_FILS_SESSION, |
| ies, frame + *frame_len - ies); |
| if (!session || session[1] != 1 + 8) { |
| mlme_dbg(sdata, |
| "No (valid) FILS Session element in (Re)Association Response frame from %pM", |
| mgmt->sa); |
| return -EINVAL; |
| } |
| /* decrypt after FILS Session element */ |
| encr = (u8 *)session + 2 + 1 + 8; |
| |
| /* AES-SIV AAD vectors */ |
| |
| /* The AP's BSSID */ |
| addr[0] = mgmt->sa; |
| len[0] = ETH_ALEN; |
| /* The STA's MAC address */ |
| addr[1] = mgmt->da; |
| len[1] = ETH_ALEN; |
| /* The AP's nonce */ |
| addr[2] = &assoc_data->fils_nonces[FILS_NONCE_LEN]; |
| len[2] = FILS_NONCE_LEN; |
| /* The STA's nonce */ |
| addr[3] = assoc_data->fils_nonces; |
| len[3] = FILS_NONCE_LEN; |
| /* The (Re)Association Response frame from the Capability Information |
| * field to the FILS Session element (both inclusive). |
| */ |
| addr[4] = capab; |
| len[4] = encr - capab; |
| |
| crypt_len = frame + *frame_len - encr; |
| if (crypt_len < AES_BLOCK_SIZE) { |
| mlme_dbg(sdata, |
| "Not enough room for AES-SIV data after FILS Session element in (Re)Association Response frame from %pM", |
| mgmt->sa); |
| return -EINVAL; |
| } |
| res = aes_siv_decrypt(assoc_data->fils_kek, assoc_data->fils_kek_len, |
| encr, crypt_len, 5, addr, len, encr); |
| if (res != 0) { |
| mlme_dbg(sdata, |
| "AES-SIV decryption of (Re)Association Response frame from %pM failed", |
| mgmt->sa); |
| return res; |
| } |
| *frame_len -= AES_BLOCK_SIZE; |
| return 0; |
| } |