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
  59         crypto_blkcipher_set_flags(
  60                 fallback,
  61                 crypto_blkcipher_get_flags((struct crypto_blkcipher *)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_blkcipher(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_altivec();
  86         enable_kernel_vsx();
  87         ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
  88         ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
  89         pagefault_enable();
  90         preempt_enable();
  91
  92         ret += crypto_blkcipher_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         struct blkcipher_desc fallback_desc = {
 105                 .tfm = ctx->fallback,
 106                 .info = desc->info,
 107                 .flags = desc->flags
 108         };
 109
 110         if (in_interrupt()) {
 111                 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
 112                                                nbytes);
 113         } else {
 114                 blkcipher_walk_init(&walk, dst, src, nbytes);
 115                 ret = blkcipher_walk_virt(desc, &walk);
 116                 while ((nbytes = walk.nbytes)) {
 117                         preempt_disable();
 118                         pagefault_disable();
 119                         enable_kernel_vsx();
 120                         enable_kernel_altivec();
 121                         aes_p8_cbc_encrypt(walk.src.virt.addr,
 122                                            walk.dst.virt.addr,
 123                                            nbytes & AES_BLOCK_MASK,
 124                                            &ctx->enc_key, walk.iv, 1);
 125                         pagefault_enable();
 126                         preempt_enable();
 127
 128                         nbytes &= AES_BLOCK_SIZE - 1;
 129                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 130                 }
 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         struct blkcipher_desc fallback_desc = {
 145                 .tfm = ctx->fallback,
 146                 .info = desc->info,
 147                 .flags = desc->flags
 148         };
 149
 150         if (in_interrupt()) {
 151                 ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src,
 152                                                nbytes);
 153         } else {
 154                 blkcipher_walk_init(&walk, dst, src, nbytes);
 155                 ret = blkcipher_walk_virt(desc, &walk);
 156                 while ((nbytes = walk.nbytes)) {
 157                         preempt_disable();
 158                         pagefault_disable();
 159                         enable_kernel_vsx();
 160                         enable_kernel_altivec();
 161                         aes_p8_cbc_encrypt(walk.src.virt.addr,
 162                                            walk.dst.virt.addr,
 163                                            nbytes & AES_BLOCK_MASK,
 164                                            &ctx->dec_key, walk.iv, 0);
 165                         pagefault_enable();
 166                         preempt_enable();
 167
 168                         nbytes &= AES_BLOCK_SIZE - 1;
 169                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 170                 }
 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 };