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