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         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
  54                 crypto_skcipher_driver_name(fallback));
  55
  56         crypto_skcipher_set_flags(
  57                 fallback,
  58                 crypto_skcipher_get_flags((struct crypto_skcipher *)tfm));
  59         ctx->fallback = fallback;
  60
  61         return 0;
  62 }
  63
  64 static void p8_aes_ctr_exit(struct crypto_tfm *tfm)
  65 {
  66         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  67
  68         if (ctx->fallback) {
  69                 crypto_free_skcipher(ctx->fallback);
  70                 ctx->fallback = NULL;
  71         }
  72 }
  73
  74 static int p8_aes_ctr_setkey(struct crypto_tfm *tfm, const u8 *key,
  75                              unsigned int keylen)
  76 {
  77         int ret;
  78         struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
  79
  80         preempt_disable();
  81         pagefault_disable();
  82         enable_kernel_vsx();
  83         ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
  84         disable_kernel_vsx();
  85         pagefault_enable();
  86         preempt_enable();
  87
  88         ret += crypto_skcipher_setkey(ctx->fallback, key, keylen);
  89         return ret;
  90 }
  91
  92 static void p8_aes_ctr_final(struct p8_aes_ctr_ctx *ctx,
  93                              struct blkcipher_walk *walk)
  94 {
  95         u8 *ctrblk = walk->iv;
  96         u8 keystream[AES_BLOCK_SIZE];
  97         u8 *src = walk->src.virt.addr;
  98         u8 *dst = walk->dst.virt.addr;
  99         unsigned int nbytes = walk->nbytes;
 100
 101         preempt_disable();
 102         pagefault_disable();
 103         enable_kernel_vsx();
 104         aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
 105         disable_kernel_vsx();
 106         pagefault_enable();
 107         preempt_enable();
 108
 109         crypto_xor_cpy(dst, keystream, src, nbytes);
 110         crypto_inc(ctrblk, AES_BLOCK_SIZE);
 111 }
 112
 113 static int p8_aes_ctr_crypt(struct blkcipher_desc *desc,
 114                             struct scatterlist *dst,
 115                             struct scatterlist *src, unsigned int nbytes)
 116 {
 117         int ret;
 118         u64 inc;
 119         struct blkcipher_walk walk;
 120         struct p8_aes_ctr_ctx *ctx =
 121                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
 122
 123         if (in_interrupt()) {
 124                 SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
 125                 skcipher_request_set_tfm(req, ctx->fallback);
 126                 skcipher_request_set_callback(req, desc->flags, NULL, NULL);
 127                 skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
 128                 ret = crypto_skcipher_encrypt(req);
 129                 skcipher_request_zero(req);
 130         } else {
 131                 blkcipher_walk_init(&walk, dst, src, nbytes);
 132                 ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
 133                 while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
 134                         preempt_disable();
 135                         pagefault_disable();
 136                         enable_kernel_vsx();
 137                         aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
 138                                                     walk.dst.virt.addr,
 139                                                     (nbytes &
 140                                                      AES_BLOCK_MASK) /
 141                                                     AES_BLOCK_SIZE,
 142                                                     &ctx->enc_key,
 143                                                     walk.iv);
 144                         disable_kernel_vsx();
 145                         pagefault_enable();
 146                         preempt_enable();
 147
 148                         /* We need to update IV mostly for last bytes/round */
 149                         inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
 150                         if (inc > 0)
 151                                 while (inc--)
 152                                         crypto_inc(walk.iv, AES_BLOCK_SIZE);
 153
 154                         nbytes &= AES_BLOCK_SIZE - 1;
 155                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 156                 }
 157                 if (walk.nbytes) {
 158                         p8_aes_ctr_final(ctx, &walk);
 159                         ret = blkcipher_walk_done(desc, &walk, 0);
 160                 }
 161         }
 162
 163         return ret;
 164 }
 165
 166 struct crypto_alg p8_aes_ctr_alg = {
 167         .cra_name = "ctr(aes)",
 168         .cra_driver_name = "p8_aes_ctr",
 169         .cra_module = THIS_MODULE,
 170         .cra_priority = 2000,
 171         .cra_type = &crypto_blkcipher_type,
 172         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 173         .cra_alignmask = 0,
 174         .cra_blocksize = 1,
 175         .cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
 176         .cra_init = p8_aes_ctr_init,
 177         .cra_exit = p8_aes_ctr_exit,
 178         .cra_blkcipher = {
 179                           .ivsize = AES_BLOCK_SIZE,
 180                           .min_keysize = AES_MIN_KEY_SIZE,
 181                           .max_keysize = AES_MAX_KEY_SIZE,
 182                           .setkey = p8_aes_ctr_setkey,
 183                           .encrypt = p8_aes_ctr_crypt,
 184                           .decrypt = p8_aes_ctr_crypt,
 185         },
 186 };