1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Cryptographic API 4 * 5 * Michael MIC (IEEE 802.11i/TKIP) keyed digest 6 * 7 * Copyright (c) 2004 Jouni Malinen <j@w1.fi> 8 */ 9 #include <crypto/internal/hash.h> 10 #include <asm/byteorder.h> 11 #include <linux/init.h> 12 #include <linux/module.h> 13 #include <linux/string.h> 14 #include <linux/types.h> 15 16 17 struct michael_mic_ctx { 18 u32 l, r; 19 }; 20 21 struct michael_mic_desc_ctx { 22 u8 pending[4]; 23 size_t pending_len; 24 25 u32 l, r; 26 }; 27 28 static inline u32 xswap(u32 val) 29 { 30 return ((val & 0x00ff00ff) << 8) | ((val & 0xff00ff00) >> 8); 31 } 32 33 34 #define michael_block(l, r) \ 35 do { \ 36 r ^= rol32(l, 17); \ 37 l += r; \ 38 r ^= xswap(l); \ 39 l += r; \ 40 r ^= rol32(l, 3); \ 41 l += r; \ 42 r ^= ror32(l, 2); \ 43 l += r; \ 44 } while (0) 45 46 47 static int michael_init(struct shash_desc *desc) 48 { 49 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 50 struct michael_mic_ctx *ctx = crypto_shash_ctx(desc->tfm); 51 mctx->pending_len = 0; 52 mctx->l = ctx->l; 53 mctx->r = ctx->r; 54 55 return 0; 56 } 57 58 59 static int michael_update(struct shash_desc *desc, const u8 *data, 60 unsigned int len) 61 { 62 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 63 const __le32 *src; 64 65 if (mctx->pending_len) { 66 int flen = 4 - mctx->pending_len; 67 if (flen > len) 68 flen = len; 69 memcpy(&mctx->pending[mctx->pending_len], data, flen); 70 mctx->pending_len += flen; 71 data += flen; 72 len -= flen; 73 74 if (mctx->pending_len < 4) 75 return 0; 76 77 src = (const __le32 *)mctx->pending; 78 mctx->l ^= le32_to_cpup(src); 79 michael_block(mctx->l, mctx->r); 80 mctx->pending_len = 0; 81 } 82 83 src = (const __le32 *)data; 84 85 while (len >= 4) { 86 mctx->l ^= le32_to_cpup(src++); 87 michael_block(mctx->l, mctx->r); 88 len -= 4; 89 } 90 91 if (len > 0) { 92 mctx->pending_len = len; 93 memcpy(mctx->pending, src, len); 94 } 95 96 return 0; 97 } 98 99 100 static int michael_final(struct shash_desc *desc, u8 *out) 101 { 102 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 103 u8 *data = mctx->pending; 104 __le32 *dst = (__le32 *)out; 105 106 /* Last block and padding (0x5a, 4..7 x 0) */ 107 switch (mctx->pending_len) { 108 case 0: 109 mctx->l ^= 0x5a; 110 break; 111 case 1: 112 mctx->l ^= data[0] | 0x5a00; 113 break; 114 case 2: 115 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; 116 break; 117 case 3: 118 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 119 0x5a000000; 120 break; 121 } 122 michael_block(mctx->l, mctx->r); 123 /* l ^= 0; */ 124 michael_block(mctx->l, mctx->r); 125 126 dst[0] = cpu_to_le32(mctx->l); 127 dst[1] = cpu_to_le32(mctx->r); 128 129 return 0; 130 } 131 132 133 static int michael_setkey(struct crypto_shash *tfm, const u8 *key, 134 unsigned int keylen) 135 { 136 struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm); 137 138 const __le32 *data = (const __le32 *)key; 139 140 if (keylen != 8) { 141 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); 142 return -EINVAL; 143 } 144 145 mctx->l = le32_to_cpu(data[0]); 146 mctx->r = le32_to_cpu(data[1]); 147 return 0; 148 } 149 150 static struct shash_alg alg = { 151 .digestsize = 8, 152 .setkey = michael_setkey, 153 .init = michael_init, 154 .update = michael_update, 155 .final = michael_final, 156 .descsize = sizeof(struct michael_mic_desc_ctx), 157 .base = { 158 .cra_name = "michael_mic", 159 .cra_blocksize = 8, 160 .cra_alignmask = 3, 161 .cra_ctxsize = sizeof(struct michael_mic_ctx), 162 .cra_module = THIS_MODULE, 163 } 164 }; 165 166 static int __init michael_mic_init(void) 167 { 168 return crypto_register_shash(&alg); 169 } 170 171 172 static void __exit michael_mic_exit(void) 173 { 174 crypto_unregister_shash(&alg); 175 } 176 177 178 subsys_initcall(michael_mic_init); 179 module_exit(michael_mic_exit); 180 181 MODULE_LICENSE("GPL v2"); 182 MODULE_DESCRIPTION("Michael MIC"); 183 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>"); 184 MODULE_ALIAS_CRYPTO("michael_mic"); 185