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/unaligned.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 __le32 pending; 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 64 if (mctx->pending_len) { 65 int flen = 4 - mctx->pending_len; 66 if (flen > len) 67 flen = len; 68 memcpy((u8 *)&mctx->pending + mctx->pending_len, data, flen); 69 mctx->pending_len += flen; 70 data += flen; 71 len -= flen; 72 73 if (mctx->pending_len < 4) 74 return 0; 75 76 mctx->l ^= le32_to_cpu(mctx->pending); 77 michael_block(mctx->l, mctx->r); 78 mctx->pending_len = 0; 79 } 80 81 while (len >= 4) { 82 mctx->l ^= get_unaligned_le32(data); 83 michael_block(mctx->l, mctx->r); 84 data += 4; 85 len -= 4; 86 } 87 88 if (len > 0) { 89 mctx->pending_len = len; 90 memcpy(&mctx->pending, data, len); 91 } 92 93 return 0; 94 } 95 96 97 static int michael_final(struct shash_desc *desc, u8 *out) 98 { 99 struct michael_mic_desc_ctx *mctx = shash_desc_ctx(desc); 100 u8 *data = (u8 *)&mctx->pending; 101 102 /* Last block and padding (0x5a, 4..7 x 0) */ 103 switch (mctx->pending_len) { 104 case 0: 105 mctx->l ^= 0x5a; 106 break; 107 case 1: 108 mctx->l ^= data[0] | 0x5a00; 109 break; 110 case 2: 111 mctx->l ^= data[0] | (data[1] << 8) | 0x5a0000; 112 break; 113 case 3: 114 mctx->l ^= data[0] | (data[1] << 8) | (data[2] << 16) | 115 0x5a000000; 116 break; 117 } 118 michael_block(mctx->l, mctx->r); 119 /* l ^= 0; */ 120 michael_block(mctx->l, mctx->r); 121 122 put_unaligned_le32(mctx->l, out); 123 put_unaligned_le32(mctx->r, out + 4); 124 125 return 0; 126 } 127 128 129 static int michael_setkey(struct crypto_shash *tfm, const u8 *key, 130 unsigned int keylen) 131 { 132 struct michael_mic_ctx *mctx = crypto_shash_ctx(tfm); 133 134 if (keylen != 8) 135 return -EINVAL; 136 137 mctx->l = get_unaligned_le32(key); 138 mctx->r = get_unaligned_le32(key + 4); 139 return 0; 140 } 141 142 static struct shash_alg alg = { 143 .digestsize = 8, 144 .setkey = michael_setkey, 145 .init = michael_init, 146 .update = michael_update, 147 .final = michael_final, 148 .descsize = sizeof(struct michael_mic_desc_ctx), 149 .base = { 150 .cra_name = "michael_mic", 151 .cra_driver_name = "michael_mic-generic", 152 .cra_blocksize = 8, 153 .cra_ctxsize = sizeof(struct michael_mic_ctx), 154 .cra_module = THIS_MODULE, 155 } 156 }; 157 158 static int __init michael_mic_init(void) 159 { 160 return crypto_register_shash(&alg); 161 } 162 163 164 static void __exit michael_mic_exit(void) 165 { 166 crypto_unregister_shash(&alg); 167 } 168 169 170 subsys_initcall(michael_mic_init); 171 module_exit(michael_mic_exit); 172 173 MODULE_LICENSE("GPL v2"); 174 MODULE_DESCRIPTION("Michael MIC"); 175 MODULE_AUTHOR("Jouni Malinen <j@w1.fi>"); 176 MODULE_ALIAS_CRYPTO("michael_mic"); 177