drivers/crypto/vmx/aes_cbc.c

   1 /**
   2  * AES CBC routines supporting VMX instructions on the 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 Foundation; 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 or FITNESS FOR A PARTICULAR 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: Marcelo Henrique Cerri <mhcerri@br.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
  31 #include "aesp8-ppc.h"
  32
  33 struct p8_aes_cbc_ctx {
  34         struct crypto_blkcipher *fallback;
  35         struct aes_key enc_key;
  36         struct aes_key dec_key;
  37 };
  38
  39 static int p8_aes_cbc_init(struct crypto_tfm *tfm)
  40 {
  41         const char *alg;
  42         struct crypto_blkcipher *fallback;
  43         struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  44
  45         if (!(alg = crypto_tfm_alg_name(tfm))) {
  46                 printk(KERN_ERR "Failed to get algorithm name.\n");
  47                 return -ENOENT;
  48         }
  49
  50         fallback =
  51             crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
  52         if (IS_ERR(fallback)) {
  53                 printk(KERN_ERR
  54                        "Failed to allocate transformation for '%s': %ld\n",
  55                        alg, PTR_ERR(fallback));
  56                 return PTR_ERR(fallback);
  57         }
  58         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
  59                crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
  60
  61         crypto_blkcipher_set_flags(
  62                 fallback,
  63                 crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
  64         ctx->fallback = fallback;
  65
  66         return 0;
  67 }
  68
  69 static void p8_aes_cbc_exit(struct crypto_tfm *tfm)
  70 {
  71         struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  72
  73         if (ctx->fallback) {
  74                 crypto_free_blkcipher(ctx->fallback);
  75                 ctx->fallback = NULL;
  76         }
  77 }
  78
  79 static int p8_aes_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,
  80                              unsigned int keylen)
  81 {
  82         int ret;
  83         struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  84
  85         preempt_disable();
  86         pagefault_disable();
  87         enable_kernel_vsx();
  88         ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
  89         ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
  90         disable_kernel_vsx();
  91         pagefault_enable();
  92         preempt_enable();
  93
  94         ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
  95         return ret;
  96 }
  97
  98 static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
  99                               struct scatterlist *dst,
 100                               struct scatterlist *src, unsigned int nbytes)
 101 {
 102         int ret;
 103         struct blkcipher_walk walk;
 104         struct p8_aes_cbc_ctx *ctx =
 105                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 106         struct blkcipher_desc fallback_desc = {
 107                 .tfm = ctx->fallback,
 108                 .info = desc->info,
 109                 .flags = desc->flags
 110         };
 111
 112         if (in_interrupt()) {
 113                 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
 114                                                nbytes);
 115         } else {
 116                 preempt_disable();
 117                 pagefault_disable();
 118                 enable_kernel_vsx();
 119
 120                 blkcipher_walk_init(&walk, dst, src, nbytes);
 121                 ret = blkcipher_walk_virt(desc, &walk);
 122                 while ((nbytes = walk.nbytes)) {
 123                         aes_p8_cbc_encrypt(walk.src.virt.addr,
 124                                            walk.dst.virt.addr,
 125                                            nbytes & AES_BLOCK_MASK,
 126                                            &ctx->enc_key, walk.iv, 1);
 127                         nbytes &= AES_BLOCK_SIZE - 1;
 128                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 129                 }
 130
 131                 disable_kernel_vsx();
 132                 pagefault_enable();
 133                 preempt_enable();
 134         }
 135
 136         return ret;
 137 }
 138
 139 static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
 140                               struct scatterlist *dst,
 141                               struct scatterlist *src, unsigned int nbytes)
 142 {
 143         int ret;
 144         struct blkcipher_walk walk;
 145         struct p8_aes_cbc_ctx *ctx =
 146                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 147         struct blkcipher_desc fallback_desc = {
 148                 .tfm = ctx->fallback,
 149                 .info = desc->info,
 150                 .flags = desc->flags
 151         };
 152
 153         if (in_interrupt()) {
 154                 ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src,
 155                                                nbytes);
 156         } else {
 157                 preempt_disable();
 158                 pagefault_disable();
 159                 enable_kernel_vsx();
 160
 161                 blkcipher_walk_init(&walk, dst, src, nbytes);
 162                 ret = blkcipher_walk_virt(desc, &walk);
 163                 while ((nbytes = walk.nbytes)) {
 164                         aes_p8_cbc_encrypt(walk.src.virt.addr,
 165                                            walk.dst.virt.addr,
 166                                            nbytes & AES_BLOCK_MASK,
 167                                            &ctx->dec_key, walk.iv, 0);
 168                         nbytes &= AES_BLOCK_SIZE - 1;
 169                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 170                 }
 171
 172                 disable_kernel_vsx();
 173                 pagefault_enable();
 174                 preempt_enable();
 175         }
 176
 177         return ret;
 178 }
 179
 180
 181 struct crypto_alg p8_aes_cbc_alg = {
 182         .cra_name = "cbc(aes)",
 183         .cra_driver_name = "p8_aes_cbc",
 184         .cra_module = THIS_MODULE,
 185         .cra_priority = 2000,
 186         .cra_type = &crypto_blkcipher_type,
 187         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 188         .cra_alignmask = 0,
 189         .cra_blocksize = AES_BLOCK_SIZE,
 190         .cra_ctxsize = sizeof(struct p8_aes_cbc_ctx),
 191         .cra_init = p8_aes_cbc_init,
 192         .cra_exit = p8_aes_cbc_exit,
 193         .cra_blkcipher = {
 194                           .ivsize = AES_BLOCK_SIZE,
 195                           .min_keysize = AES_MIN_KEY_SIZE,
 196                           .max_keysize = AES_MAX_KEY_SIZE,
 197                           .setkey = p8_aes_cbc_setkey,
 198                           .encrypt = p8_aes_cbc_encrypt,
 199                           .decrypt = p8_aes_cbc_decrypt,
 200         },
 201 };