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