g_eli_key.c revision 220922
1/*- 2 * Copyright (c) 2005-2011 Pawel Jakub Dawidek <pawel@dawidek.net> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/sys/geom/eli/g_eli_key.c 220922 2011-04-21 13:31:43Z pjd $"); 29 30#include <sys/param.h> 31#ifdef _KERNEL 32#include <sys/malloc.h> 33#include <sys/systm.h> 34#include <geom/geom.h> 35#else 36#include <stdio.h> 37#include <stdint.h> 38#include <stdlib.h> 39#include <string.h> 40#include <strings.h> 41#include <errno.h> 42#endif 43 44#include <geom/eli/g_eli.h> 45 46#ifdef _KERNEL 47MALLOC_DECLARE(M_ELI); 48#endif 49 50/* 51 * Verify if the given 'key' is correct. 52 * Return 1 if it is correct and 0 otherwise. 53 */ 54static int 55g_eli_mkey_verify(const unsigned char *mkey, const unsigned char *key) 56{ 57 const unsigned char *odhmac; /* On-disk HMAC. */ 58 unsigned char chmac[SHA512_MDLEN]; /* Calculated HMAC. */ 59 unsigned char hmkey[SHA512_MDLEN]; /* Key for HMAC. */ 60 61 /* 62 * The key for HMAC calculations is: hmkey = HMAC_SHA512(Derived-Key, 0) 63 */ 64 g_eli_crypto_hmac(key, G_ELI_USERKEYLEN, "\x00", 1, hmkey, 0); 65 66 odhmac = mkey + G_ELI_DATAIVKEYLEN; 67 68 /* Calculate HMAC from Data-Key and IV-Key. */ 69 g_eli_crypto_hmac(hmkey, sizeof(hmkey), mkey, G_ELI_DATAIVKEYLEN, 70 chmac, 0); 71 72 bzero(hmkey, sizeof(hmkey)); 73 74 /* 75 * Compare calculated HMAC with HMAC from metadata. 76 * If two HMACs are equal, 'key' is correct. 77 */ 78 return (!bcmp(odhmac, chmac, SHA512_MDLEN)); 79} 80 81/* 82 * Calculate HMAC from Data-Key and IV-Key. 83 */ 84void 85g_eli_mkey_hmac(unsigned char *mkey, const unsigned char *key) 86{ 87 unsigned char hmkey[SHA512_MDLEN]; /* Key for HMAC. */ 88 unsigned char *odhmac; /* On-disk HMAC. */ 89 90 /* 91 * The key for HMAC calculations is: hmkey = HMAC_SHA512(Derived-Key, 0) 92 */ 93 g_eli_crypto_hmac(key, G_ELI_USERKEYLEN, "\x00", 1, hmkey, 0); 94 95 odhmac = mkey + G_ELI_DATAIVKEYLEN; 96 /* Calculate HMAC from Data-Key and IV-Key. */ 97 g_eli_crypto_hmac(hmkey, sizeof(hmkey), mkey, G_ELI_DATAIVKEYLEN, 98 odhmac, 0); 99 100 bzero(hmkey, sizeof(hmkey)); 101} 102 103/* 104 * Find and decrypt Master Key encrypted with 'key'. 105 * Return decrypted Master Key number in 'nkeyp' if not NULL. 106 * Return 0 on success, > 0 on failure, -1 on bad key. 107 */ 108int 109g_eli_mkey_decrypt(const struct g_eli_metadata *md, const unsigned char *key, 110 unsigned char *mkey, unsigned *nkeyp) 111{ 112 unsigned char tmpmkey[G_ELI_MKEYLEN]; 113 unsigned char enckey[SHA512_MDLEN]; /* Key for encryption. */ 114 const unsigned char *mmkey; 115 int bit, error, nkey; 116 117 if (nkeyp != NULL) 118 *nkeyp = -1; 119 120 /* 121 * The key for encryption is: enckey = HMAC_SHA512(Derived-Key, 1) 122 */ 123 g_eli_crypto_hmac(key, G_ELI_USERKEYLEN, "\x01", 1, enckey, 0); 124 125 mmkey = md->md_mkeys; 126 for (nkey = 0; nkey < G_ELI_MAXMKEYS; nkey++, mmkey += G_ELI_MKEYLEN) { 127 bit = (1 << nkey); 128 if (!(md->md_keys & bit)) 129 continue; 130 bcopy(mmkey, tmpmkey, G_ELI_MKEYLEN); 131 error = g_eli_crypto_decrypt(md->md_ealgo, tmpmkey, 132 G_ELI_MKEYLEN, enckey, md->md_keylen); 133 if (error != 0) { 134 bzero(tmpmkey, sizeof(tmpmkey)); 135 bzero(enckey, sizeof(enckey)); 136 return (error); 137 } 138 if (g_eli_mkey_verify(tmpmkey, key)) { 139 bcopy(tmpmkey, mkey, G_ELI_DATAIVKEYLEN); 140 bzero(tmpmkey, sizeof(tmpmkey)); 141 bzero(enckey, sizeof(enckey)); 142 if (nkeyp != NULL) 143 *nkeyp = nkey; 144 return (0); 145 } 146 } 147 bzero(enckey, sizeof(enckey)); 148 bzero(tmpmkey, sizeof(tmpmkey)); 149 return (-1); 150} 151 152/* 153 * Encrypt the Master-Key and calculate HMAC to be able to verify it in the 154 * future. 155 */ 156int 157g_eli_mkey_encrypt(unsigned algo, const unsigned char *key, unsigned keylen, 158 unsigned char *mkey) 159{ 160 unsigned char enckey[SHA512_MDLEN]; /* Key for encryption. */ 161 int error; 162 163 /* 164 * To calculate HMAC, the whole key (G_ELI_USERKEYLEN bytes long) will 165 * be used. 166 */ 167 g_eli_mkey_hmac(mkey, key); 168 /* 169 * The key for encryption is: enckey = HMAC_SHA512(Derived-Key, 1) 170 */ 171 g_eli_crypto_hmac(key, G_ELI_USERKEYLEN, "\x01", 1, enckey, 0); 172 /* 173 * Encrypt the Master-Key and HMAC() result with the given key (this 174 * time only 'keylen' bits from the key are used). 175 */ 176 error = g_eli_crypto_encrypt(algo, mkey, G_ELI_MKEYLEN, enckey, keylen); 177 178 bzero(enckey, sizeof(enckey)); 179 180 return (error); 181} 182 183#ifdef _KERNEL 184/* 185 * When doing encryption only, copy IV key and encryption key. 186 * When doing encryption and authentication, copy IV key, generate encryption 187 * key and generate authentication key. 188 */ 189void 190g_eli_mkey_propagate(struct g_eli_softc *sc, const unsigned char *mkey) 191{ 192 193 /* Remember the Master Key. */ 194 bcopy(mkey, sc->sc_mkey, sizeof(sc->sc_mkey)); 195 196 bcopy(mkey, sc->sc_ivkey, sizeof(sc->sc_ivkey)); 197 mkey += sizeof(sc->sc_ivkey); 198 199 /* 200 * The authentication key is: akey = HMAC_SHA512(Master-Key, 0x11) 201 */ 202 if ((sc->sc_flags & G_ELI_FLAG_AUTH) != 0) { 203 g_eli_crypto_hmac(mkey, G_ELI_MAXKEYLEN, "\x11", 1, 204 sc->sc_akey, 0); 205 } else { 206 arc4rand(sc->sc_akey, sizeof(sc->sc_akey), 0); 207 } 208 209 /* Initialize encryption keys. */ 210 g_eli_key_init(sc); 211 212 if (sc->sc_flags & G_ELI_FLAG_AUTH) { 213 /* 214 * Precalculate SHA256 for HMAC key generation. 215 * This is expensive operation and we can do it only once now or 216 * for every access to sector, so now will be much better. 217 */ 218 SHA256_Init(&sc->sc_akeyctx); 219 SHA256_Update(&sc->sc_akeyctx, sc->sc_akey, 220 sizeof(sc->sc_akey)); 221 } 222 /* 223 * Precalculate SHA256 for IV generation. 224 * This is expensive operation and we can do it only once now or for 225 * every access to sector, so now will be much better. 226 */ 227 switch (sc->sc_ealgo) { 228 case CRYPTO_AES_XTS: 229 break; 230 default: 231 SHA256_Init(&sc->sc_ivctx); 232 SHA256_Update(&sc->sc_ivctx, sc->sc_ivkey, 233 sizeof(sc->sc_ivkey)); 234 break; 235 } 236} 237#endif 238