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 <crypto/skcipher.h>
  31
  32 #include "aesp8-ppc.h"
  33
  34 struct p8_aes_ctr_ctx {
  35         struct crypto_skcipher *fallback;
  36         struct aes_key enc_key;
  37 };
  38
  39 static int p8_aes_ctr_init(struct crypto_tfm *tfm)
  40 {
  41         const char *alg = crypto_tfm_alg_name(tfm);
  42         struct crypto_skcipher *fallback;
  43         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  44
  45         fallback = crypto_alloc_skcipher(alg, 0,
  46                         CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);
  47         if (IS_ERR(fallback)) {
  48                 printk(KERN_ERR
  49                        "Failed to allocate transformation for '%s': %ld\n",
  50                        alg, PTR_ERR(fallback));
  51                 return PTR_ERR(fallback);
  52         }
  53
  54         crypto_skcipher_set_flags(
  55                 fallback,
  56                 crypto_skcipher_get_flags((struct crypto_skcipher *)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_skcipher(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_skcipher_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
 121         if (in_interrupt()) {
 122                 SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
 123                 skcipher_request_set_tfm(req, ctx->fallback);
 124                 skcipher_request_set_callback(req, desc->flags, NULL, NULL);
 125                 skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
 126                 ret = crypto_skcipher_encrypt(req);
 127                 skcipher_request_zero(req);
 128         } else {
 129                 blkcipher_walk_init(&walk, dst, src, nbytes);
 130                 ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
 131                 while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
 132                         preempt_disable();
 133                         pagefault_disable();
 134                         enable_kernel_vsx();
 135                         aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
 136                                                     walk.dst.virt.addr,
 137                                                     (nbytes &
 138                                                      AES_BLOCK_MASK) /
 139                                                     AES_BLOCK_SIZE,
 140                                                     &ctx->enc_key,
 141                                                     walk.iv);
 142                         disable_kernel_vsx();
 143                         pagefault_enable();
 144                         preempt_enable();
 145
 146                         /* We need to update IV mostly for last bytes/round */
 147                         inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
 148                         if (inc > 0)
 149                                 while (inc--)
 150                                         crypto_inc(walk.iv, AES_BLOCK_SIZE);
 151
 152                         nbytes &= AES_BLOCK_SIZE - 1;
 153                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 154                 }
 155                 if (walk.nbytes) {
 156                         p8_aes_ctr_final(ctx, &walk);
 157                         ret = blkcipher_walk_done(desc, &walk, 0);
 158                 }
 159         }
 160
 161         return ret;
 162 }
 163
 164 struct crypto_alg p8_aes_ctr_alg = {
 165         .cra_name = "ctr(aes)",
 166         .cra_driver_name = "p8_aes_ctr",
 167         .cra_module = THIS_MODULE,
 168         .cra_priority = 2000,
 169         .cra_type = &crypto_blkcipher_type,
 170         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 171         .cra_alignmask = 0,
 172         .cra_blocksize = 1,
 173         .cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
 174         .cra_init = p8_aes_ctr_init,
 175         .cra_exit = p8_aes_ctr_exit,
 176         .cra_blkcipher = {
 177                           .ivsize = AES_BLOCK_SIZE,
 178                           .min_keysize = AES_MIN_KEY_SIZE,
 179                           .max_keysize = AES_MAX_KEY_SIZE,
 180                           .setkey = p8_aes_ctr_setkey,
 181                           .encrypt = p8_aes_ctr_crypt,
 182                           .decrypt = p8_aes_ctr_crypt,
 183         },
 184 };