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
  31 #include "aesp8-ppc.h"
  32
  33 struct p8_aes_cbc_ctx {
  34     struct crypto_blkcipher *fallback;
  35     struct aes_key enc_key;
  36     struct aes_key dec_key;
  37 };
  38
  39 static int p8_aes_cbc_init(struct crypto_tfm *tfm)
  40 {
  41     const char *alg;
  42     struct crypto_blkcipher *fallback;
  43     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  44
  45     if (!(alg = crypto_tfm_alg_name(tfm))) {
  46         printk(KERN_ERR "Failed to get algorithm name.\n");
  47         return -ENOENT;
  48     }
  49
  50     fallback = crypto_alloc_blkcipher(alg, 0 ,CRYPTO_ALG_NEED_FALLBACK);
  51     if (IS_ERR(fallback)) {
  52         printk(KERN_ERR "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(fallback,
  60             crypto_blkcipher_get_flags((struct crypto_blkcipher *) tfm));
  61     ctx->fallback = fallback;
  62
  63     return 0;
  64 }
  65
  66 static void p8_aes_cbc_exit(struct crypto_tfm *tfm)
  67 {
  68     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  69
  70     if (ctx->fallback) {
  71         crypto_free_blkcipher(ctx->fallback);
  72         ctx->fallback = NULL;
  73     }
  74 }
  75
  76 static int p8_aes_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,
  77     unsigned int keylen)
  78 {
  79     int ret;
  80     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
  81
  82     pagefault_disable();
  83     enable_kernel_altivec();
  84     ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
  85     ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
  86     pagefault_enable();
  87
  88     ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
  89     return ret;
  90 }
  91
  92 static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
  93     struct scatterlist *dst, struct scatterlist *src,
  94     unsigned int nbytes)
  95 {
  96     int ret;
  97     struct blkcipher_walk walk;
  98     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(
  99             crypto_blkcipher_tfm(desc->tfm));
 100     struct blkcipher_desc fallback_desc = {
 101         .tfm = ctx->fallback,
 102         .info = desc->info,
 103         .flags = desc->flags
 104     };
 105
 106     if (in_interrupt()) {
 107         ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes);
 108     } else {
 109         pagefault_disable();
 110         enable_kernel_altivec();
 111
 112         blkcipher_walk_init(&walk, dst, src, nbytes);
 113         ret = blkcipher_walk_virt(desc, &walk);
 114         while ((nbytes = walk.nbytes)) {
 115                         aes_p8_cbc_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
 116                                 nbytes & AES_BLOCK_MASK, &ctx->enc_key, walk.iv, 1);
 117                         nbytes &= AES_BLOCK_SIZE - 1;
 118                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 119         }
 120
 121         pagefault_enable();
 122     }
 123
 124     return ret;
 125 }
 126
 127 static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
 128     struct scatterlist *dst, struct scatterlist *src,
 129     unsigned int nbytes)
 130 {
 131     int ret;
 132     struct blkcipher_walk walk;
 133     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(
 134             crypto_blkcipher_tfm(desc->tfm));
 135     struct blkcipher_desc fallback_desc = {
 136         .tfm = ctx->fallback,
 137         .info = desc->info,
 138         .flags = desc->flags
 139     };
 140
 141     if (in_interrupt()) {
 142         ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes);
 143     } else {
 144         pagefault_disable();
 145         enable_kernel_altivec();
 146
 147         blkcipher_walk_init(&walk, dst, src, nbytes);
 148         ret = blkcipher_walk_virt(desc, &walk);
 149         while ((nbytes = walk.nbytes)) {
 150                         aes_p8_cbc_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
 151                                 nbytes & AES_BLOCK_MASK, &ctx->dec_key, walk.iv, 0);
 152                         nbytes &= AES_BLOCK_SIZE - 1;
 153                         ret = blkcipher_walk_done(desc, &walk, nbytes);
 154                 }
 155
 156         pagefault_enable();
 157     }
 158
 159     return ret;
 160 }
 161
 162
 163 struct crypto_alg p8_aes_cbc_alg = {
 164     .cra_name = "cbc(aes)",
 165     .cra_driver_name = "p8_aes_cbc",
 166     .cra_module = THIS_MODULE,
 167     .cra_priority = 1000,
 168     .cra_type = &crypto_blkcipher_type,
 169     .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
 170     .cra_alignmask = 0,
 171     .cra_blocksize = AES_BLOCK_SIZE,
 172     .cra_ctxsize = sizeof(struct p8_aes_cbc_ctx),
 173     .cra_init = p8_aes_cbc_init,
 174     .cra_exit = p8_aes_cbc_exit,
 175     .cra_blkcipher = {
 176         .ivsize = 0,
 177         .min_keysize = AES_MIN_KEY_SIZE,
 178         .max_keysize = AES_MAX_KEY_SIZE,
 179         .setkey = p8_aes_cbc_setkey,
 180         .encrypt = p8_aes_cbc_encrypt,
 181         .decrypt = p8_aes_cbc_decrypt,
 182     },
 183 };
 184