arch/arm64/crypto/aes-ce-cipher.c

   1 /*
   2  * aes-ce-cipher.c - core AES cipher using ARMv8 Crypto Extensions
   3  *
   4  * Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <asm/neon.h>
  12 #include <crypto/aes.h>
  13 #include <linux/cpufeature.h>
  14 #include <linux/crypto.h>
  15 #include <linux/module.h>
  16
  17 #include "aes-ce-setkey.h"
  18
  19 MODULE_DESCRIPTION("Synchronous AES cipher using ARMv8 Crypto Extensions");
  20 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
  21 MODULE_LICENSE("GPL v2");
  22
  23 struct aes_block {
  24         u8 b[AES_BLOCK_SIZE];
  25 };
  26
  27 static int num_rounds(struct crypto_aes_ctx *ctx)
  28 {
  29         /*
  30          * # of rounds specified by AES:
  31          * 128 bit key          10 rounds
  32          * 192 bit key          12 rounds
  33          * 256 bit key          14 rounds
  34          * => n byte key        => 6 + (n/4) rounds
  35          */
  36         return 6 + ctx->key_length / 4;
  37 }
  38
  39 static void aes_cipher_encrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
  40 {
  41         struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  42         struct aes_block *out = (struct aes_block *)dst;
  43         struct aes_block const *in = (struct aes_block *)src;
  44         void *dummy0;
  45         int dummy1;
  46
  47         kernel_neon_begin_partial(4);
  48
  49         __asm__("       ld1     {v0.16b}, %[in]                 ;"
  50                 "       ld1     {v1.2d}, [%[key]], #16          ;"
  51                 "       cmp     %w[rounds], #10                 ;"
  52                 "       bmi     0f                              ;"
  53                 "       bne     3f                              ;"
  54                 "       mov     v3.16b, v1.16b                  ;"
  55                 "       b       2f                              ;"
  56                 "0:     mov     v2.16b, v1.16b                  ;"
  57                 "       ld1     {v3.2d}, [%[key]], #16          ;"
  58                 "1:     aese    v0.16b, v2.16b                  ;"
  59                 "       aesmc   v0.16b, v0.16b                  ;"
  60                 "2:     ld1     {v1.2d}, [%[key]], #16          ;"
  61                 "       aese    v0.16b, v3.16b                  ;"
  62                 "       aesmc   v0.16b, v0.16b                  ;"
  63                 "3:     ld1     {v2.2d}, [%[key]], #16          ;"
  64                 "       subs    %w[rounds], %w[rounds], #3      ;"
  65                 "       aese    v0.16b, v1.16b                  ;"
  66                 "       aesmc   v0.16b, v0.16b                  ;"
  67                 "       ld1     {v3.2d}, [%[key]], #16          ;"
  68                 "       bpl     1b                              ;"
  69                 "       aese    v0.16b, v2.16b                  ;"
  70                 "       eor     v0.16b, v0.16b, v3.16b          ;"
  71                 "       st1     {v0.16b}, %[out]                ;"
  72
  73         :       [out]           "=Q"(*out),
  74                 [key]           "=r"(dummy0),
  75                 [rounds]        "=r"(dummy1)
  76         :       [in]            "Q"(*in),
  77                                 "1"(ctx->key_enc),
  78                                 "2"(num_rounds(ctx) - 2)
  79         :       "cc");
  80
  81         kernel_neon_end();
  82 }
  83
  84 static void aes_cipher_decrypt(struct crypto_tfm *tfm, u8 dst[], u8 const src[])
  85 {
  86         struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
  87         struct aes_block *out = (struct aes_block *)dst;
  88         struct aes_block const *in = (struct aes_block *)src;
  89         void *dummy0;
  90         int dummy1;
  91
  92         kernel_neon_begin_partial(4);
  93
  94         __asm__("       ld1     {v0.16b}, %[in]                 ;"
  95                 "       ld1     {v1.2d}, [%[key]], #16          ;"
  96                 "       cmp     %w[rounds], #10                 ;"
  97                 "       bmi     0f                              ;"
  98                 "       bne     3f                              ;"
  99                 "       mov     v3.16b, v1.16b                  ;"
 100                 "       b       2f                              ;"
 101                 "0:     mov     v2.16b, v1.16b                  ;"
 102                 "       ld1     {v3.2d}, [%[key]], #16          ;"
 103                 "1:     aesd    v0.16b, v2.16b                  ;"
 104                 "       aesimc  v0.16b, v0.16b                  ;"
 105                 "2:     ld1     {v1.2d}, [%[key]], #16          ;"
 106                 "       aesd    v0.16b, v3.16b                  ;"
 107                 "       aesimc  v0.16b, v0.16b                  ;"
 108                 "3:     ld1     {v2.2d}, [%[key]], #16          ;"
 109                 "       subs    %w[rounds], %w[rounds], #3      ;"
 110                 "       aesd    v0.16b, v1.16b                  ;"
 111                 "       aesimc  v0.16b, v0.16b                  ;"
 112                 "       ld1     {v3.2d}, [%[key]], #16          ;"
 113                 "       bpl     1b                              ;"
 114                 "       aesd    v0.16b, v2.16b                  ;"
 115                 "       eor     v0.16b, v0.16b, v3.16b          ;"
 116                 "       st1     {v0.16b}, %[out]                ;"
 117
 118         :       [out]           "=Q"(*out),
 119                 [key]           "=r"(dummy0),
 120                 [rounds]        "=r"(dummy1)
 121         :       [in]            "Q"(*in),
 122                                 "1"(ctx->key_dec),
 123                                 "2"(num_rounds(ctx) - 2)
 124         :       "cc");
 125
 126         kernel_neon_end();
 127 }
 128
 129 /*
 130  * aes_sub() - use the aese instruction to perform the AES sbox substitution
 131  *             on each byte in 'input'
 132  */
 133 static u32 aes_sub(u32 input)
 134 {
 135         u32 ret;
 136
 137         __asm__("dup    v1.4s, %w[in]           ;"
 138                 "movi   v0.16b, #0              ;"
 139                 "aese   v0.16b, v1.16b          ;"
 140                 "umov   %w[out], v0.4s[0]       ;"
 141
 142         :       [out]   "=r"(ret)
 143         :       [in]    "r"(input)
 144         :               "v0","v1");
 145
 146         return ret;
 147 }
 148
 149 int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
 150                      unsigned int key_len)
 151 {
 152         /*
 153          * The AES key schedule round constants
 154          */
 155         static u8 const rcon[] = {
 156                 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
 157         };
 158
 159         u32 kwords = key_len / sizeof(u32);
 160         struct aes_block *key_enc, *key_dec;
 161         int i, j;
 162
 163         if (key_len != AES_KEYSIZE_128 &&
 164             key_len != AES_KEYSIZE_192 &&
 165             key_len != AES_KEYSIZE_256)
 166                 return -EINVAL;
 167
 168         memcpy(ctx->key_enc, in_key, key_len);
 169         ctx->key_length = key_len;
 170
 171         kernel_neon_begin_partial(2);
 172         for (i = 0; i < sizeof(rcon); i++) {
 173                 u32 *rki = ctx->key_enc + (i * kwords);
 174                 u32 *rko = rki + kwords;
 175
 176                 rko[0] = ror32(aes_sub(rki[kwords - 1]), 8) ^ rcon[i] ^ rki[0];
 177                 rko[1] = rko[0] ^ rki[1];
 178                 rko[2] = rko[1] ^ rki[2];
 179                 rko[3] = rko[2] ^ rki[3];
 180
 181                 if (key_len == AES_KEYSIZE_192) {
 182                         if (i >= 7)
 183                                 break;
 184                         rko[4] = rko[3] ^ rki[4];
 185                         rko[5] = rko[4] ^ rki[5];
 186                 } else if (key_len == AES_KEYSIZE_256) {
 187                         if (i >= 6)
 188                                 break;
 189                         rko[4] = aes_sub(rko[3]) ^ rki[4];
 190                         rko[5] = rko[4] ^ rki[5];
 191                         rko[6] = rko[5] ^ rki[6];
 192                         rko[7] = rko[6] ^ rki[7];
 193                 }
 194         }
 195
 196         /*
 197          * Generate the decryption keys for the Equivalent Inverse Cipher.
 198          * This involves reversing the order of the round keys, and applying
 199          * the Inverse Mix Columns transformation on all but the first and
 200          * the last one.
 201          */
 202         key_enc = (struct aes_block *)ctx->key_enc;
 203         key_dec = (struct aes_block *)ctx->key_dec;
 204         j = num_rounds(ctx);
 205
 206         key_dec[0] = key_enc[j];
 207         for (i = 1, j--; j > 0; i++, j--)
 208                 __asm__("ld1    {v0.16b}, %[in]         ;"
 209                         "aesimc v1.16b, v0.16b          ;"
 210                         "st1    {v1.16b}, %[out]        ;"
 211
 212                 :       [out]   "=Q"(key_dec[i])
 213                 :       [in]    "Q"(key_enc[j])
 214                 :               "v0","v1");
 215         key_dec[i] = key_enc[0];
 216
 217         kernel_neon_end();
 218         return 0;
 219 }
 220 EXPORT_SYMBOL(ce_aes_expandkey);
 221
 222 int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
 223                   unsigned int key_len)
 224 {
 225         struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
 226         int ret;
 227
 228         ret = ce_aes_expandkey(ctx, in_key, key_len);
 229         if (!ret)
 230                 return 0;
 231
 232         tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 233         return -EINVAL;
 234 }
 235 EXPORT_SYMBOL(ce_aes_setkey);
 236
 237 static struct crypto_alg aes_alg = {
 238         .cra_name               = "aes",
 239         .cra_driver_name        = "aes-ce",
 240         .cra_priority           = 250,
 241         .cra_flags              = CRYPTO_ALG_TYPE_CIPHER,
 242         .cra_blocksize          = AES_BLOCK_SIZE,
 243         .cra_ctxsize            = sizeof(struct crypto_aes_ctx),
 244         .cra_module             = THIS_MODULE,
 245         .cra_cipher = {
 246                 .cia_min_keysize        = AES_MIN_KEY_SIZE,
 247                 .cia_max_keysize        = AES_MAX_KEY_SIZE,
 248                 .cia_setkey             = ce_aes_setkey,
 249                 .cia_encrypt            = aes_cipher_encrypt,
 250                 .cia_decrypt            = aes_cipher_decrypt
 251         }
 252 };
 253
 254 static int __init aes_mod_init(void)
 255 {
 256         return crypto_register_alg(&aes_alg);
 257 }
 258
 259 static void __exit aes_mod_exit(void)
 260 {
 261         crypto_unregister_alg(&aes_alg);
 262 }
 263
 264 module_cpu_feature_match(AES, aes_mod_init);
 265 module_exit(aes_mod_exit);