drivers/crypto/vmx/aes_ctr.c

   1 /**
   2  * AES CTR 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 "aesp8-ppc.h"
  31
  32 struct p8_aes_ctr_ctx {
  33         struct crypto_blkcipher *fallback;
  34         struct aes_key enc_key;
  35 };
  36
  37 static int p8_aes_ctr_init(struct crypto_tfm *tfm)
  38 {
  39         const char *alg = crypto_tfm_alg_name(tfm);
  40         struct crypto_blkcipher *fallback;
  41         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  42
  43         fallback =
  44             crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
  45         if (IS_ERR(fallback)) {
  46                 printk(KERN_ERR
  47                        "Failed to allocate transformation for '%s': %ld\n",
  48                        alg, PTR_ERR(fallback));
  49                 return PTR_ERR(fallback);
  50         }
  51         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
  52                crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
  53
  54         crypto_blkcipher_set_flags(
  55                 fallback,
  56                 crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
  57         ctx->fallback = fallback;
  58
  59         return 0;
  60 }
  61
  62 static void p8_aes_ctr_exit(struct crypto_tfm *tfm)
  63 {
  64         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  65
  66         if (ctx->fallback) {
  67                 crypto_free_blkcipher(ctx->fallback);
  68                 ctx->fallback = NULL;
  69         }
  70 }
  71
  72 static int p8_aes_ctr_setkey(struct crypto_tfm *tfm, const u8 *key,
  73                              unsigned int keylen)
  74 {
  75         int ret;
  76         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  77
  78         preempt_disable();
  79         pagefault_disable();
  80         enable_kernel_vsx();
  81         ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
  82         disable_kernel_vsx();
  83         pagefault_enable();
  84         preempt_enable();
  85
  86         ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
  87         return ret;
  88 }
  89
  90 static void p8_aes_ctr_final(struct p8_aes_ctr_ctx *ctx,
  91                              struct blkcipher_walk *walk)
  92 {
  93         u8 *ctrblk = walk->iv;
  94         u8 keystream[AES_BLOCK_SIZE];
  95         u8 *src = walk->src.virt.addr;
  96         u8 *dst = walk->dst.virt.addr;
  97         unsigned int nbytes = walk->nbytes;
  98
  99         preempt_disable();
 100         pagefault_disable();
 101         enable_kernel_vsx();
 102         aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
 103         disable_kernel_vsx();
 104         pagefault_enable();
 105         preempt_enable();
 106
 107         crypto_xor_cpy(dst, keystream, src, nbytes);
 108         crypto_inc(ctrblk, AES_BLOCK_SIZE);
 109 }
 110
 111 static int p8_aes_ctr_crypt(struct blkcipher_desc *desc,
 112                             struct scatterlist *dst,
 113                             struct scatterlist *src, unsigned int nbytes)
 114 {
 115         int ret;
 116         u64 inc;
 117         struct blkcipher_walk walk;
 118         struct p8_aes_ctr_ctx *ctx =
 119                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 120         struct blkcipher_desc fallback_desc = {
 121                 .tfm = ctx->fallback,
 122                 .info = desc->info,
 123                 .flags = desc->flags
 124         };
 125
 126         if (in_interrupt()) {
 127                 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
 128                                                nbytes);
 129         } else {
 130                 blkcipher_walk_init(&walk, dst, src, nbytes);
 131                 ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
 132                 while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
 133                         preempt_disable();
 134                         pagefault_disable();
 135                         enable_kernel_vsx();
 136                         aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
 137                                                     walk.dst.virt.addr,
 138                                                     (nbytes &
 139                                                      AES_BLOCK_MASK) /
 140                                                     AES_BLOCK_SIZE,
 141                                                     &ctx->enc_key,
 142                                                     walk.iv);
 143                         disable_kernel_vsx();
 144                         pagefault_enable();
 145                         preempt_enable();
 146
 147                         /* We need to update IV mostly for last bytes/round */
 148                         inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
 149                         if (inc > 0)
 150                                 while (inc--)
 151                                         crypto_inc(walk.iv, AES_BLOCK_SIZE);
 152
 153                         nbytes &= AES_BLOCK_SIZE - 1;
 154                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 155                 }
 156                 if (walk.nbytes) {
 157                         p8_aes_ctr_final(ctx, &walk);
 158                         ret = blkcipher_walk_done(desc, &walk, 0);
 159                 }
 160         }
 161
 162         return ret;
 163 }
 164
 165 struct crypto_alg p8_aes_ctr_alg = {
 166         .cra_name = "ctr(aes)",
 167         .cra_driver_name = "p8_aes_ctr",
 168         .cra_module = THIS_MODULE,
 169         .cra_priority = 2000,
 170         .cra_type = &crypto_blkcipher_type,
 171         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 172         .cra_alignmask = 0,
 173         .cra_blocksize = 1,
 174         .cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
 175         .cra_init = p8_aes_ctr_init,
 176         .cra_exit = p8_aes_ctr_exit,
 177         .cra_blkcipher = {
 178                           .ivsize = AES_BLOCK_SIZE,
 179                           .min_keysize = AES_MIN_KEY_SIZE,
 180                           .max_keysize = AES_MAX_KEY_SIZE,
 181                           .setkey = p8_aes_ctr_setkey,
 182                           .encrypt = p8_aes_ctr_crypt,
 183                           .decrypt = p8_aes_ctr_crypt,
 184         },
 185 };