1 /** 2 * AES XTS routines supporting VMX In-core instructions on 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 Foundations; 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 of FITNESS FOR A PARTICUPAR 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: Leonidas S. Barbosa <leosilva@linux.vnet.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/xts.h> 31 32 #include "aesp8-ppc.h" 33 34 struct p8_aes_xts_ctx { 35 struct crypto_blkcipher *fallback; 36 struct aes_key enc_key; 37 struct aes_key dec_key; 38 struct aes_key tweak_key; 39 }; 40 41 static int p8_aes_xts_init(struct crypto_tfm *tfm) 42 { 43 const char *alg; 44 struct crypto_blkcipher *fallback; 45 struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm); 46 47 if (!(alg = crypto_tfm_alg_name(tfm))) { 48 printk(KERN_ERR "Failed to get algorithm name.\n"); 49 return -ENOENT; 50 } 51 52 fallback = 53 crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK); 54 if (IS_ERR(fallback)) { 55 printk(KERN_ERR 56 "Failed to allocate transformation for '%s': %ld\n", 57 alg, PTR_ERR(fallback)); 58 return PTR_ERR(fallback); 59 } 60 printk(KERN_INFO "Using '%s' as fallback implementation.\n", 61 crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback)); 62 63 crypto_blkcipher_set_flags( 64 fallback, 65 crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm)); 66 ctx->fallback = fallback; 67 68 return 0; 69 } 70 71 static void p8_aes_xts_exit(struct crypto_tfm *tfm) 72 { 73 struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm); 74 75 if (ctx->fallback) { 76 crypto_free_blkcipher(ctx->fallback); 77 ctx->fallback = NULL; 78 } 79 } 80 81 static int p8_aes_xts_setkey(struct crypto_tfm *tfm, const u8 *key, 82 unsigned int keylen) 83 { 84 int ret; 85 struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm); 86 87 ret = xts_check_key(tfm, key, keylen); 88 if (ret) 89 return ret; 90 91 preempt_disable(); 92 pagefault_disable(); 93 enable_kernel_vsx(); 94 ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key); 95 ret += aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key); 96 ret += aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key); 97 disable_kernel_vsx(); 98 pagefault_enable(); 99 preempt_enable(); 100 101 ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen); 102 return ret; 103 } 104 105 static int p8_aes_xts_crypt(struct blkcipher_desc *desc, 106 struct scatterlist *dst, 107 struct scatterlist *src, 108 unsigned int nbytes, int enc) 109 { 110 int ret; 111 u8 tweak[AES_BLOCK_SIZE]; 112 u8 *iv; 113 struct blkcipher_walk walk; 114 struct p8_aes_xts_ctx *ctx = 115 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm)); 116 struct blkcipher_desc fallback_desc = { 117 .tfm = ctx->fallback, 118 .info = desc->info, 119 .flags = desc->flags 120 }; 121 122 if (in_interrupt()) { 123 ret = enc ? crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes) : 124 crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes); 125 } else { 126 preempt_disable(); 127 pagefault_disable(); 128 enable_kernel_vsx(); 129 130 blkcipher_walk_init(&walk, dst, src, nbytes); 131 132 ret = blkcipher_walk_virt(desc, &walk); 133 iv = walk.iv; 134 memset(tweak, 0, AES_BLOCK_SIZE); 135 aes_p8_encrypt(iv, tweak, &ctx->tweak_key); 136 137 while ((nbytes = walk.nbytes)) { 138 if (enc) 139 aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr, 140 nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak); 141 else 142 aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr, 143 nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak); 144 145 nbytes &= AES_BLOCK_SIZE - 1; 146 ret = blkcipher_walk_done(desc, &walk, nbytes); 147 } 148 149 disable_kernel_vsx(); 150 pagefault_enable(); 151 preempt_enable(); 152 } 153 return ret; 154 } 155 156 static int p8_aes_xts_encrypt(struct blkcipher_desc *desc, 157 struct scatterlist *dst, 158 struct scatterlist *src, unsigned int nbytes) 159 { 160 return p8_aes_xts_crypt(desc, dst, src, nbytes, 1); 161 } 162 163 static int p8_aes_xts_decrypt(struct blkcipher_desc *desc, 164 struct scatterlist *dst, 165 struct scatterlist *src, unsigned int nbytes) 166 { 167 return p8_aes_xts_crypt(desc, dst, src, nbytes, 0); 168 } 169 170 struct crypto_alg p8_aes_xts_alg = { 171 .cra_name = "xts(aes)", 172 .cra_driver_name = "p8_aes_xts", 173 .cra_module = THIS_MODULE, 174 .cra_priority = 2000, 175 .cra_type = &crypto_blkcipher_type, 176 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK, 177 .cra_alignmask = 0, 178 .cra_blocksize = AES_BLOCK_SIZE, 179 .cra_ctxsize = sizeof(struct p8_aes_xts_ctx), 180 .cra_init = p8_aes_xts_init, 181 .cra_exit = p8_aes_xts_exit, 182 .cra_blkcipher = { 183 .ivsize = AES_BLOCK_SIZE, 184 .min_keysize = 2 * AES_MIN_KEY_SIZE, 185 .max_keysize = 2 * AES_MAX_KEY_SIZE, 186 .setkey = p8_aes_xts_setkey, 187 .encrypt = p8_aes_xts_encrypt, 188 .decrypt = p8_aes_xts_decrypt, 189 } 190 }; 191