drivers/crypto/vmx/aes_xts.c

   1 /**
   2  * AES XTS routines supporting VMX In-core instructions on Power 8
   3  *
   4  * Copyright (C) 2015 International Business Machines Inc.
   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 as published by
   8  * the Free Software Foundations; version 2 only.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY of FITNESS FOR A PARTICUPAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  *
  19  * Author: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
  20  */
  21
  22 #include <linux/types.h>
  23 #include <linux/err.h>
  24 #include <linux/crypto.h>
  25 #include <linux/delay.h>
  26 #include <linux/hardirq.h>
  27 #include <asm/switch_to.h>
  28 #include <crypto/aes.h>
  29 #include <crypto/scatterwalk.h>
  30 #include <crypto/xts.h>
  31 #include <crypto/skcipher.h>
  32
  33 #include "aesp8-ppc.h"
  34
  35 struct p8_aes_xts_ctx {
  36         struct crypto_skcipher *fallback;
  37         struct aes_key enc_key;
  38         struct aes_key dec_key;
  39         struct aes_key tweak_key;
  40 };
  41
  42 static int p8_aes_xts_init(struct crypto_tfm *tfm)
  43 {
  44         const char *alg;
  45         struct crypto_skcipher *fallback;
  46         struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
  47
  48         if (!(alg = crypto_tfm_alg_name(tfm))) {
  49                 printk(KERN_ERR "Failed to get algorithm name.\n");
  50                 return -ENOENT;
  51         }
  52
  53         fallback = crypto_alloc_skcipher(alg, 0,
  54                         CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);
  55         if (IS_ERR(fallback)) {
  56                 printk(KERN_ERR
  57                         "Failed to allocate transformation for '%s': %ld\n",
  58                         alg, PTR_ERR(fallback));
  59                 return PTR_ERR(fallback);
  60         }
  61         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
  62                 crypto_skcipher_driver_name(fallback));
  63
  64         crypto_skcipher_set_flags(
  65                 fallback,
  66                 crypto_skcipher_get_flags((struct crypto_skcipher *)tfm));
  67         ctx->fallback = fallback;
  68
  69         return 0;
  70 }
  71
  72 static void p8_aes_xts_exit(struct crypto_tfm *tfm)
  73 {
  74         struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
  75
  76         if (ctx->fallback) {
  77                 crypto_free_skcipher(ctx->fallback);
  78                 ctx->fallback = NULL;
  79         }
  80 }
  81
  82 static int p8_aes_xts_setkey(struct crypto_tfm *tfm, const u8 *key,
  83                              unsigned int keylen)
  84 {
  85         int ret;
  86         struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
  87
  88         ret = xts_check_key(tfm, key, keylen);
  89         if (ret)
  90                 return ret;
  91
  92         preempt_disable();
  93         pagefault_disable();
  94         enable_kernel_vsx();
  95         ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
  96         ret += aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
  97         ret += aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
  98         disable_kernel_vsx();
  99         pagefault_enable();
 100         preempt_enable();
 101
 102         ret += crypto_skcipher_setkey(ctx->fallback, key, keylen);
 103         return ret;
 104 }
 105
 106 static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
 107                             struct scatterlist *dst,
 108                             struct scatterlist *src,
 109                             unsigned int nbytes, int enc)
 110 {
 111         int ret;
 112         u8 tweak[AES_BLOCK_SIZE];
 113         u8 *iv;
 114         struct blkcipher_walk walk;
 115         struct p8_aes_xts_ctx *ctx =
 116                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 117
 118         if (in_interrupt()) {
 119                 SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
 120                 skcipher_request_set_tfm(req, ctx->fallback);
 121                 skcipher_request_set_callback(req, desc->flags, NULL, NULL);
 122                 skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
 123                 ret = enc? crypto_skcipher_encrypt(req) : crypto_skcipher_decrypt(req);
 124                 skcipher_request_zero(req);
 125         } else {
 126                 preempt_disable();
 127                 pagefault_disable();
 128                 enable_kernel_vsx();
 129
 130                 blkcipher_walk_init(&walk, dst, src, nbytes);
 131
 132                 ret = blkcipher_walk_virt(desc, &walk);
 133                 iv = walk.iv;
 134                 memset(tweak, 0, AES_BLOCK_SIZE);
 135                 aes_p8_encrypt(iv, tweak, &ctx->tweak_key);
 136
 137                 while ((nbytes = walk.nbytes)) {
 138                         if (enc)
 139                                 aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
 140                                                 nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak);
 141                         else
 142                                 aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
 143                                                 nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak);
 144
 145                         nbytes &= AES_BLOCK_SIZE - 1;
 146                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 147                 }
 148
 149                 disable_kernel_vsx();
 150                 pagefault_enable();
 151                 preempt_enable();
 152         }
 153         return ret;
 154 }
 155
 156 static int p8_aes_xts_encrypt(struct blkcipher_desc *desc,
 157                               struct scatterlist *dst,
 158                               struct scatterlist *src, unsigned int nbytes)
 159 {
 160         return p8_aes_xts_crypt(desc, dst, src, nbytes, 1);
 161 }
 162
 163 static int p8_aes_xts_decrypt(struct blkcipher_desc *desc,
 164                               struct scatterlist *dst,
 165                               struct scatterlist *src, unsigned int nbytes)
 166 {
 167         return p8_aes_xts_crypt(desc, dst, src, nbytes, 0);
 168 }
 169
 170 struct crypto_alg p8_aes_xts_alg = {
 171         .cra_name = "xts(aes)",
 172         .cra_driver_name = "p8_aes_xts",
 173         .cra_module = THIS_MODULE,
 174         .cra_priority = 2000,
 175         .cra_type = &crypto_blkcipher_type,
 176         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 177         .cra_alignmask = 0,
 178         .cra_blocksize = AES_BLOCK_SIZE,
 179         .cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
 180         .cra_init = p8_aes_xts_init,
 181         .cra_exit = p8_aes_xts_exit,
 182         .cra_blkcipher = {
 183                         .ivsize = AES_BLOCK_SIZE,
 184                         .min_keysize = 2 * AES_MIN_KEY_SIZE,
 185                         .max_keysize = 2 * AES_MAX_KEY_SIZE,
 186                         .setkey  = p8_aes_xts_setkey,
 187                         .encrypt = p8_aes_xts_encrypt,
 188                         .decrypt = p8_aes_xts_decrypt,
 189         }
 190 };