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 }; 187