1 /* 2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 3 * 4 * Authors: 5 * Mimi Zohar <zohar@us.ibm.com> 6 * Kylene Hall <kjhall@us.ibm.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation, version 2 of the License. 11 * 12 * File: ima_crypto.c 13 * Calculates md5/sha1 file hash, template hash, boot-aggreate hash 14 */ 15 16 #include <linux/kernel.h> 17 #include <linux/file.h> 18 #include <linux/crypto.h> 19 #include <linux/scatterlist.h> 20 #include <linux/err.h> 21 #include <linux/slab.h> 22 #include <crypto/hash.h> 23 #include <crypto/hash_info.h> 24 #include "ima.h" 25 26 static struct crypto_shash *ima_shash_tfm; 27 28 int ima_init_crypto(void) 29 { 30 long rc; 31 32 ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0); 33 if (IS_ERR(ima_shash_tfm)) { 34 rc = PTR_ERR(ima_shash_tfm); 35 pr_err("Can not allocate %s (reason: %ld)\n", 36 hash_algo_name[ima_hash_algo], rc); 37 return rc; 38 } 39 return 0; 40 } 41 42 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo) 43 { 44 struct crypto_shash *tfm = ima_shash_tfm; 45 int rc; 46 47 if (algo != ima_hash_algo && algo < HASH_ALGO__LAST) { 48 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0); 49 if (IS_ERR(tfm)) { 50 rc = PTR_ERR(tfm); 51 pr_err("Can not allocate %s (reason: %d)\n", 52 hash_algo_name[algo], rc); 53 } 54 } 55 return tfm; 56 } 57 58 static void ima_free_tfm(struct crypto_shash *tfm) 59 { 60 if (tfm != ima_shash_tfm) 61 crypto_free_shash(tfm); 62 } 63 64 /* 65 * Calculate the MD5/SHA1 file digest 66 */ 67 static int ima_calc_file_hash_tfm(struct file *file, 68 struct ima_digest_data *hash, 69 struct crypto_shash *tfm) 70 { 71 loff_t i_size, offset = 0; 72 char *rbuf; 73 int rc, read = 0; 74 struct { 75 struct shash_desc shash; 76 char ctx[crypto_shash_descsize(tfm)]; 77 } desc; 78 79 desc.shash.tfm = tfm; 80 desc.shash.flags = 0; 81 82 hash->length = crypto_shash_digestsize(tfm); 83 84 rc = crypto_shash_init(&desc.shash); 85 if (rc != 0) 86 return rc; 87 88 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); 89 if (!rbuf) { 90 rc = -ENOMEM; 91 goto out; 92 } 93 if (!(file->f_mode & FMODE_READ)) { 94 file->f_mode |= FMODE_READ; 95 read = 1; 96 } 97 i_size = i_size_read(file_inode(file)); 98 while (offset < i_size) { 99 int rbuf_len; 100 101 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE); 102 if (rbuf_len < 0) { 103 rc = rbuf_len; 104 break; 105 } 106 if (rbuf_len == 0) 107 break; 108 offset += rbuf_len; 109 110 rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len); 111 if (rc) 112 break; 113 } 114 kfree(rbuf); 115 if (!rc) 116 rc = crypto_shash_final(&desc.shash, hash->digest); 117 if (read) 118 file->f_mode &= ~FMODE_READ; 119 out: 120 return rc; 121 } 122 123 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) 124 { 125 struct crypto_shash *tfm; 126 int rc; 127 128 tfm = ima_alloc_tfm(hash->algo); 129 if (IS_ERR(tfm)) 130 return PTR_ERR(tfm); 131 132 rc = ima_calc_file_hash_tfm(file, hash, tfm); 133 134 ima_free_tfm(tfm); 135 136 return rc; 137 } 138 139 /* 140 * Calculate the hash of template data 141 */ 142 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data, 143 int num_fields, 144 struct ima_digest_data *hash, 145 struct crypto_shash *tfm) 146 { 147 struct { 148 struct shash_desc shash; 149 char ctx[crypto_shash_descsize(tfm)]; 150 } desc; 151 int rc, i; 152 153 desc.shash.tfm = tfm; 154 desc.shash.flags = 0; 155 156 hash->length = crypto_shash_digestsize(tfm); 157 158 rc = crypto_shash_init(&desc.shash); 159 if (rc != 0) 160 return rc; 161 162 for (i = 0; i < num_fields; i++) { 163 rc = crypto_shash_update(&desc.shash, 164 (const u8 *) &field_data[i].len, 165 sizeof(field_data[i].len)); 166 rc = crypto_shash_update(&desc.shash, field_data[i].data, 167 field_data[i].len); 168 if (rc) 169 break; 170 } 171 172 if (!rc) 173 rc = crypto_shash_final(&desc.shash, hash->digest); 174 175 return rc; 176 } 177 178 int ima_calc_field_array_hash(struct ima_field_data *field_data, int num_fields, 179 struct ima_digest_data *hash) 180 { 181 struct crypto_shash *tfm; 182 int rc; 183 184 tfm = ima_alloc_tfm(hash->algo); 185 if (IS_ERR(tfm)) 186 return PTR_ERR(tfm); 187 188 rc = ima_calc_field_array_hash_tfm(field_data, num_fields, hash, tfm); 189 190 ima_free_tfm(tfm); 191 192 return rc; 193 } 194 195 static void __init ima_pcrread(int idx, u8 *pcr) 196 { 197 if (!ima_used_chip) 198 return; 199 200 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0) 201 pr_err("IMA: Error Communicating to TPM chip\n"); 202 } 203 204 /* 205 * Calculate the boot aggregate hash 206 */ 207 static int __init ima_calc_boot_aggregate_tfm(char *digest, 208 struct crypto_shash *tfm) 209 { 210 u8 pcr_i[TPM_DIGEST_SIZE]; 211 int rc, i; 212 struct { 213 struct shash_desc shash; 214 char ctx[crypto_shash_descsize(tfm)]; 215 } desc; 216 217 desc.shash.tfm = tfm; 218 desc.shash.flags = 0; 219 220 rc = crypto_shash_init(&desc.shash); 221 if (rc != 0) 222 return rc; 223 224 /* cumulative sha1 over tpm registers 0-7 */ 225 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 226 ima_pcrread(i, pcr_i); 227 /* now accumulate with current aggregate */ 228 rc = crypto_shash_update(&desc.shash, pcr_i, TPM_DIGEST_SIZE); 229 } 230 if (!rc) 231 crypto_shash_final(&desc.shash, digest); 232 return rc; 233 } 234 235 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash) 236 { 237 struct crypto_shash *tfm; 238 int rc; 239 240 tfm = ima_alloc_tfm(hash->algo); 241 if (IS_ERR(tfm)) 242 return PTR_ERR(tfm); 243 244 hash->length = crypto_shash_digestsize(tfm); 245 rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm); 246 247 ima_free_tfm(tfm); 248 249 return rc; 250 } 251