1 /* 2 * Accelerated GHASH implementation with ARMv8 PMULL instructions. 3 * 4 * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 as published 8 * by the Free Software Foundation. 9 */ 10 11 #include <asm/neon.h> 12 #include <asm/unaligned.h> 13 #include <crypto/internal/hash.h> 14 #include <linux/cpufeature.h> 15 #include <linux/crypto.h> 16 #include <linux/module.h> 17 18 MODULE_DESCRIPTION("GHASH secure hash using ARMv8 Crypto Extensions"); 19 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 20 MODULE_LICENSE("GPL v2"); 21 22 #define GHASH_BLOCK_SIZE 16 23 #define GHASH_DIGEST_SIZE 16 24 25 struct ghash_key { 26 u64 a; 27 u64 b; 28 }; 29 30 struct ghash_desc_ctx { 31 u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)]; 32 u8 buf[GHASH_BLOCK_SIZE]; 33 u32 count; 34 }; 35 36 asmlinkage void pmull_ghash_update(int blocks, u64 dg[], const char *src, 37 struct ghash_key const *k, const char *head); 38 39 static int ghash_init(struct shash_desc *desc) 40 { 41 struct ghash_desc_ctx *ctx = shash_desc_ctx(desc); 42 43 *ctx = (struct ghash_desc_ctx){}; 44 return 0; 45 } 46 47 static int ghash_update(struct shash_desc *desc, const u8 *src, 48 unsigned int len) 49 { 50 struct ghash_desc_ctx *ctx = shash_desc_ctx(desc); 51 unsigned int partial = ctx->count % GHASH_BLOCK_SIZE; 52 53 ctx->count += len; 54 55 if ((partial + len) >= GHASH_BLOCK_SIZE) { 56 struct ghash_key *key = crypto_shash_ctx(desc->tfm); 57 int blocks; 58 59 if (partial) { 60 int p = GHASH_BLOCK_SIZE - partial; 61 62 memcpy(ctx->buf + partial, src, p); 63 src += p; 64 len -= p; 65 } 66 67 blocks = len / GHASH_BLOCK_SIZE; 68 len %= GHASH_BLOCK_SIZE; 69 70 kernel_neon_begin_partial(8); 71 pmull_ghash_update(blocks, ctx->digest, src, key, 72 partial ? ctx->buf : NULL); 73 kernel_neon_end(); 74 src += blocks * GHASH_BLOCK_SIZE; 75 partial = 0; 76 } 77 if (len) 78 memcpy(ctx->buf + partial, src, len); 79 return 0; 80 } 81 82 static int ghash_final(struct shash_desc *desc, u8 *dst) 83 { 84 struct ghash_desc_ctx *ctx = shash_desc_ctx(desc); 85 unsigned int partial = ctx->count % GHASH_BLOCK_SIZE; 86 87 if (partial) { 88 struct ghash_key *key = crypto_shash_ctx(desc->tfm); 89 90 memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial); 91 92 kernel_neon_begin_partial(8); 93 pmull_ghash_update(1, ctx->digest, ctx->buf, key, NULL); 94 kernel_neon_end(); 95 } 96 put_unaligned_be64(ctx->digest[1], dst); 97 put_unaligned_be64(ctx->digest[0], dst + 8); 98 99 *ctx = (struct ghash_desc_ctx){}; 100 return 0; 101 } 102 103 static int ghash_setkey(struct crypto_shash *tfm, 104 const u8 *inkey, unsigned int keylen) 105 { 106 struct ghash_key *key = crypto_shash_ctx(tfm); 107 u64 a, b; 108 109 if (keylen != GHASH_BLOCK_SIZE) { 110 crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); 111 return -EINVAL; 112 } 113 114 /* perform multiplication by 'x' in GF(2^128) */ 115 b = get_unaligned_be64(inkey); 116 a = get_unaligned_be64(inkey + 8); 117 118 key->a = (a << 1) | (b >> 63); 119 key->b = (b << 1) | (a >> 63); 120 121 if (b >> 63) 122 key->b ^= 0xc200000000000000UL; 123 124 return 0; 125 } 126 127 static struct shash_alg ghash_alg = { 128 .digestsize = GHASH_DIGEST_SIZE, 129 .init = ghash_init, 130 .update = ghash_update, 131 .final = ghash_final, 132 .setkey = ghash_setkey, 133 .descsize = sizeof(struct ghash_desc_ctx), 134 .base = { 135 .cra_name = "ghash", 136 .cra_driver_name = "ghash-ce", 137 .cra_priority = 200, 138 .cra_flags = CRYPTO_ALG_TYPE_SHASH, 139 .cra_blocksize = GHASH_BLOCK_SIZE, 140 .cra_ctxsize = sizeof(struct ghash_key), 141 .cra_module = THIS_MODULE, 142 }, 143 }; 144 145 static int __init ghash_ce_mod_init(void) 146 { 147 return crypto_register_shash(&ghash_alg); 148 } 149 150 static void __exit ghash_ce_mod_exit(void) 151 { 152 crypto_unregister_shash(&ghash_alg); 153 } 154 155 module_cpu_feature_match(PMULL, ghash_ce_mod_init); 156 module_exit(ghash_ce_mod_exit); 157