1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AES-128-CMAC with TLen 16 for IEEE 802.11w BIP 4 * Copyright 2008, Jouni Malinen <j@w1.fi> 5 * Copyright (C) 2020 Intel Corporation 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/types.h> 10 #include <linux/crypto.h> 11 #include <linux/export.h> 12 #include <linux/err.h> 13 #include <crypto/aes.h> 14 15 #include <net/mac80211.h> 16 #include "key.h" 17 #include "aes_cmac.h" 18 19 #define CMAC_TLEN 8 /* CMAC TLen = 64 bits (8 octets) */ 20 #define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */ 21 #define AAD_LEN 20 22 23 static const u8 zero[CMAC_TLEN_256]; 24 25 void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad, 26 const u8 *data, size_t data_len, u8 *mic) 27 { 28 SHASH_DESC_ON_STACK(desc, tfm); 29 u8 out[AES_BLOCK_SIZE]; 30 const __le16 *fc; 31 32 desc->tfm = tfm; 33 34 crypto_shash_init(desc); 35 crypto_shash_update(desc, aad, AAD_LEN); 36 fc = (const __le16 *)aad; 37 if (ieee80211_is_beacon(*fc)) { 38 /* mask Timestamp field to zero */ 39 crypto_shash_update(desc, zero, 8); 40 crypto_shash_update(desc, data + 8, data_len - 8 - CMAC_TLEN); 41 } else { 42 crypto_shash_update(desc, data, data_len - CMAC_TLEN); 43 } 44 crypto_shash_finup(desc, zero, CMAC_TLEN, out); 45 46 memcpy(mic, out, CMAC_TLEN); 47 } 48 49 void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad, 50 const u8 *data, size_t data_len, u8 *mic) 51 { 52 SHASH_DESC_ON_STACK(desc, tfm); 53 const __le16 *fc; 54 55 desc->tfm = tfm; 56 57 crypto_shash_init(desc); 58 crypto_shash_update(desc, aad, AAD_LEN); 59 fc = (const __le16 *)aad; 60 if (ieee80211_is_beacon(*fc)) { 61 /* mask Timestamp field to zero */ 62 crypto_shash_update(desc, zero, 8); 63 crypto_shash_update(desc, data + 8, 64 data_len - 8 - CMAC_TLEN_256); 65 } else { 66 crypto_shash_update(desc, data, data_len - CMAC_TLEN_256); 67 } 68 crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic); 69 } 70 71 struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[], 72 size_t key_len) 73 { 74 struct crypto_shash *tfm; 75 76 tfm = crypto_alloc_shash("cmac(aes)", 0, 0); 77 if (!IS_ERR(tfm)) { 78 int err = crypto_shash_setkey(tfm, key, key_len); 79 80 if (err) { 81 crypto_free_shash(tfm); 82 return ERR_PTR(err); 83 } 84 } 85 86 return tfm; 87 } 88 89 void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm) 90 { 91 crypto_free_shash(tfm); 92 } 93