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;
  43         struct crypto_skcipher *fallback;
  44         struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  45
  46         if (!(alg = crypto_tfm_alg_name(tfm))) {
  47                 printk(KERN_ERR "Failed to get algorithm name.\n");
  48                 return -ENOENT;
  49         }
  50
  51         fallback = crypto_alloc_skcipher(alg, 0,
  52                         CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);
  53
  54         if (IS_ERR(fallback)) {
  55                 printk(KERN_ERR
  56                        "Failed to allocate transformation for '%s': %ld\n",
  57                        alg, PTR_ERR(fallback));
  58                 return PTR_ERR(fallback);
  59         }
  60         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
  61                 crypto_skcipher_driver_name(fallback));
  62
  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_cbc_exit(struct crypto_tfm *tfm)
  73 {
  74         struct p8_aes_cbc_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_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,
  83                              unsigned int keylen)
  84 {
  85         int ret;
  86         struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  87
  88         preempt_disable();
  89         pagefault_disable();
  90         enable_kernel_vsx();
  91         ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
  92         ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
  93         disable_kernel_vsx();
  94         pagefault_enable();
  95         preempt_enable();
  96
  97         ret += crypto_skcipher_setkey(ctx->fallback, key, keylen);
  98         return ret;
  99 }
 100
 101 static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
 102                               struct scatterlist *dst,
 103                               struct scatterlist *src, unsigned int nbytes)
 104 {
 105         int ret;
 106         struct blkcipher_walk walk;
 107         struct p8_aes_cbc_ctx *ctx =
 108                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 109
 110         if (in_interrupt()) {
 111                 SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
 112                 skcipher_request_set_tfm(req, ctx->fallback);
 113                 skcipher_request_set_callback(req, desc->flags, NULL, NULL);
 114                 skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
 115                 ret = crypto_skcipher_encrypt(req);
 116                 skcipher_request_zero(req);
 117         } else {
 118                 preempt_disable();
 119                 pagefault_disable();
 120                 enable_kernel_vsx();
 121
 122                 blkcipher_walk_init(&walk, dst, src, nbytes);
 123                 ret = blkcipher_walk_virt(desc, &walk);
 124                 while ((nbytes = walk.nbytes)) {
 125                         aes_p8_cbc_encrypt(walk.src.virt.addr,
 126                                            walk.dst.virt.addr,
 127                                            nbytes & AES_BLOCK_MASK,
 128                                            &ctx->enc_key, walk.iv, 1);
 129                         nbytes &= AES_BLOCK_SIZE - 1;
 130                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 131                 }
 132
 133                 disable_kernel_vsx();
 134                 pagefault_enable();
 135                 preempt_enable();
 136         }
 137
 138         return ret;
 139 }
 140
 141 static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
 142                               struct scatterlist *dst,
 143                               struct scatterlist *src, unsigned int nbytes)
 144 {
 145         int ret;
 146         struct blkcipher_walk walk;
 147         struct p8_aes_cbc_ctx *ctx =
 148                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 149
 150         if (in_interrupt()) {
 151                 SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
 152                 skcipher_request_set_tfm(req, ctx->fallback);
 153                 skcipher_request_set_callback(req, desc->flags, NULL, NULL);
 154                 skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
 155                 ret = crypto_skcipher_decrypt(req);
 156                 skcipher_request_zero(req);
 157         } else {
 158                 preempt_disable();
 159                 pagefault_disable();
 160                 enable_kernel_vsx();
 161
 162                 blkcipher_walk_init(&walk, dst, src, nbytes);
 163                 ret = blkcipher_walk_virt(desc, &walk);
 164                 while ((nbytes = walk.nbytes)) {
 165                         aes_p8_cbc_encrypt(walk.src.virt.addr,
 166                                            walk.dst.virt.addr,
 167                                            nbytes & AES_BLOCK_MASK,
 168                                            &ctx->dec_key, walk.iv, 0);
 169                         nbytes &= AES_BLOCK_SIZE - 1;
 170                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 171                 }
 172
 173                 disable_kernel_vsx();
 174                 pagefault_enable();
 175                 preempt_enable();
 176         }
 177
 178         return ret;
 179 }
 180
 181
 182 struct crypto_alg p8_aes_cbc_alg = {
 183         .cra_name = "cbc(aes)",
 184         .cra_driver_name = "p8_aes_cbc",
 185         .cra_module = THIS_MODULE,
 186         .cra_priority = 2000,
 187         .cra_type = &crypto_blkcipher_type,
 188         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 189         .cra_alignmask = 0,
 190         .cra_blocksize = AES_BLOCK_SIZE,
 191         .cra_ctxsize = sizeof(struct p8_aes_cbc_ctx),
 192         .cra_init = p8_aes_cbc_init,
 193         .cra_exit = p8_aes_cbc_exit,
 194         .cra_blkcipher = {
 195                           .ivsize = AES_BLOCK_SIZE,
 196                           .min_keysize = AES_MIN_KEY_SIZE,
 197                           .max_keysize = AES_MAX_KEY_SIZE,
 198                           .setkey = p8_aes_cbc_setkey,
 199                           .encrypt = p8_aes_cbc_encrypt,
 200                           .decrypt = p8_aes_cbc_decrypt,
 201         },
 202 };