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;
  40         struct crypto_blkcipher *fallback;
  41         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  42
  43         if (!(alg = crypto_tfm_alg_name(tfm))) {
  44                 printk(KERN_ERR "Failed to get algorithm name.\n");
  45                 return -ENOENT;
  46         }
  47
  48         fallback =
  49             crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
  50         if (IS_ERR(fallback)) {
  51                 printk(KERN_ERR
  52                        "Failed to allocate transformation for '%s': %ld\n",
  53                        alg, PTR_ERR(fallback));
  54                 return PTR_ERR(fallback);
  55         }
  56         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
  57                crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
  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_ctr_exit(struct crypto_tfm *tfm)
  68 {
  69         struct p8_aes_ctr_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_ctr_setkey(struct crypto_tfm *tfm, const u8 *key,
  78                              unsigned int keylen)
  79 {
  80         int ret;
  81         struct p8_aes_ctr_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         disable_kernel_vsx();
  88         pagefault_enable();
  89         preempt_enable();
  90
  91         ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
  92         return ret;
  93 }
  94
  95 static void p8_aes_ctr_final(struct p8_aes_ctr_ctx *ctx,
  96                              struct blkcipher_walk *walk)
  97 {
  98         u8 *ctrblk = walk->iv;
  99         u8 keystream[AES_BLOCK_SIZE];
 100         u8 *src = walk->src.virt.addr;
 101         u8 *dst = walk->dst.virt.addr;
 102         unsigned int nbytes = walk->nbytes;
 103
 104         preempt_disable();
 105         pagefault_disable();
 106         enable_kernel_vsx();
 107         aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
 108         disable_kernel_vsx();
 109         pagefault_enable();
 110         preempt_enable();
 111
 112         crypto_xor(keystream, src, nbytes);
 113         memcpy(dst, keystream, nbytes);
 114         crypto_inc(ctrblk, AES_BLOCK_SIZE);
 115 }
 116
 117 static int p8_aes_ctr_crypt(struct blkcipher_desc *desc,
 118                             struct scatterlist *dst,
 119                             struct scatterlist *src, unsigned int nbytes)
 120 {
 121         int ret;
 122         u64 inc;
 123         struct blkcipher_walk walk;
 124         struct p8_aes_ctr_ctx *ctx =
 125                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 126         struct blkcipher_desc fallback_desc = {
 127                 .tfm = ctx->fallback,
 128                 .info = desc->info,
 129                 .flags = desc->flags
 130         };
 131
 132         if (in_interrupt()) {
 133                 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
 134                                                nbytes);
 135         } else {
 136                 blkcipher_walk_init(&walk, dst, src, nbytes);
 137                 ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
 138                 while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
 139                         preempt_disable();
 140                         pagefault_disable();
 141                         enable_kernel_vsx();
 142                         aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
 143                                                     walk.dst.virt.addr,
 144                                                     (nbytes &
 145                                                      AES_BLOCK_MASK) /
 146                                                     AES_BLOCK_SIZE,
 147                                                     &ctx->enc_key,
 148                                                     walk.iv);
 149                         disable_kernel_vsx();
 150                         pagefault_enable();
 151                         preempt_enable();
 152
 153                         /* We need to update IV mostly for last bytes/round */
 154                         inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
 155                         if (inc > 0)
 156                                 while (inc--)
 157                                         crypto_inc(walk.iv, AES_BLOCK_SIZE);
 158
 159                         nbytes &= AES_BLOCK_SIZE - 1;
 160                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 161                 }
 162                 if (walk.nbytes) {
 163                         p8_aes_ctr_final(ctx, &walk);
 164                         ret = blkcipher_walk_done(desc, &walk, 0);
 165                 }
 166         }
 167
 168         return ret;
 169 }
 170
 171 struct crypto_alg p8_aes_ctr_alg = {
 172         .cra_name = "ctr(aes)",
 173         .cra_driver_name = "p8_aes_ctr",
 174         .cra_module = THIS_MODULE,
 175         .cra_priority = 2000,
 176         .cra_type = &crypto_blkcipher_type,
 177         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 178         .cra_alignmask = 0,
 179         .cra_blocksize = 1,
 180         .cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
 181         .cra_init = p8_aes_ctr_init,
 182         .cra_exit = p8_aes_ctr_exit,
 183         .cra_blkcipher = {
 184                           .ivsize = AES_BLOCK_SIZE,
 185                           .min_keysize = AES_MIN_KEY_SIZE,
 186                           .max_keysize = AES_MAX_KEY_SIZE,
 187                           .setkey = p8_aes_ctr_setkey,
 188                           .encrypt = p8_aes_ctr_crypt,
 189                           .decrypt = p8_aes_ctr_crypt,
 190         },
 191 };