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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 17 18 #include <linux/kernel.h> 19 #include <linux/file.h> 20 #include <linux/crypto.h> 21 #include <linux/scatterlist.h> 22 #include <linux/err.h> 23 #include <linux/slab.h> 24 #include <crypto/hash.h> 25 #include <crypto/hash_info.h> 26 #include "ima.h" 27 28 static struct crypto_shash *ima_shash_tfm; 29 30 int ima_init_crypto(void) 31 { 32 long rc; 33 34 ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0); 35 if (IS_ERR(ima_shash_tfm)) { 36 rc = PTR_ERR(ima_shash_tfm); 37 pr_err("Can not allocate %s (reason: %ld)\n", 38 hash_algo_name[ima_hash_algo], rc); 39 return rc; 40 } 41 return 0; 42 } 43 44 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo) 45 { 46 struct crypto_shash *tfm = ima_shash_tfm; 47 int rc; 48 49 if (algo != ima_hash_algo && algo < HASH_ALGO__LAST) { 50 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0); 51 if (IS_ERR(tfm)) { 52 rc = PTR_ERR(tfm); 53 pr_err("Can not allocate %s (reason: %d)\n", 54 hash_algo_name[algo], rc); 55 } 56 } 57 return tfm; 58 } 59 60 static void ima_free_tfm(struct crypto_shash *tfm) 61 { 62 if (tfm != ima_shash_tfm) 63 crypto_free_shash(tfm); 64 } 65 66 /* 67 * Calculate the MD5/SHA1 file digest 68 */ 69 static int ima_calc_file_hash_tfm(struct file *file, 70 struct ima_digest_data *hash, 71 struct crypto_shash *tfm) 72 { 73 loff_t i_size, offset = 0; 74 char *rbuf; 75 int rc, read = 0; 76 struct { 77 struct shash_desc shash; 78 char ctx[crypto_shash_descsize(tfm)]; 79 } desc; 80 81 desc.shash.tfm = tfm; 82 desc.shash.flags = 0; 83 84 hash->length = crypto_shash_digestsize(tfm); 85 86 rc = crypto_shash_init(&desc.shash); 87 if (rc != 0) 88 return rc; 89 90 i_size = i_size_read(file_inode(file)); 91 92 if (i_size == 0) 93 goto out; 94 95 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); 96 if (!rbuf) 97 return -ENOMEM; 98 99 if (!(file->f_mode & FMODE_READ)) { 100 file->f_mode |= FMODE_READ; 101 read = 1; 102 } 103 104 while (offset < i_size) { 105 int rbuf_len; 106 107 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE); 108 if (rbuf_len < 0) { 109 rc = rbuf_len; 110 break; 111 } 112 if (rbuf_len == 0) 113 break; 114 offset += rbuf_len; 115 116 rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len); 117 if (rc) 118 break; 119 } 120 if (read) 121 file->f_mode &= ~FMODE_READ; 122 kfree(rbuf); 123 out: 124 if (!rc) 125 rc = crypto_shash_final(&desc.shash, hash->digest); 126 return rc; 127 } 128 129 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) 130 { 131 struct crypto_shash *tfm; 132 int rc; 133 134 tfm = ima_alloc_tfm(hash->algo); 135 if (IS_ERR(tfm)) 136 return PTR_ERR(tfm); 137 138 rc = ima_calc_file_hash_tfm(file, hash, tfm); 139 140 ima_free_tfm(tfm); 141 142 return rc; 143 } 144 145 /* 146 * Calculate the hash of template data 147 */ 148 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data, 149 struct ima_template_desc *td, 150 int num_fields, 151 struct ima_digest_data *hash, 152 struct crypto_shash *tfm) 153 { 154 struct { 155 struct shash_desc shash; 156 char ctx[crypto_shash_descsize(tfm)]; 157 } desc; 158 int rc, i; 159 160 desc.shash.tfm = tfm; 161 desc.shash.flags = 0; 162 163 hash->length = crypto_shash_digestsize(tfm); 164 165 rc = crypto_shash_init(&desc.shash); 166 if (rc != 0) 167 return rc; 168 169 for (i = 0; i < num_fields; i++) { 170 u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 }; 171 u8 *data_to_hash = field_data[i].data; 172 u32 datalen = field_data[i].len; 173 174 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) { 175 rc = crypto_shash_update(&desc.shash, 176 (const u8 *) &field_data[i].len, 177 sizeof(field_data[i].len)); 178 if (rc) 179 break; 180 } else if (strcmp(td->fields[i]->field_id, "n") == 0) { 181 memcpy(buffer, data_to_hash, datalen); 182 data_to_hash = buffer; 183 datalen = IMA_EVENT_NAME_LEN_MAX + 1; 184 } 185 rc = crypto_shash_update(&desc.shash, data_to_hash, datalen); 186 if (rc) 187 break; 188 } 189 190 if (!rc) 191 rc = crypto_shash_final(&desc.shash, hash->digest); 192 193 return rc; 194 } 195 196 int ima_calc_field_array_hash(struct ima_field_data *field_data, 197 struct ima_template_desc *desc, int num_fields, 198 struct ima_digest_data *hash) 199 { 200 struct crypto_shash *tfm; 201 int rc; 202 203 tfm = ima_alloc_tfm(hash->algo); 204 if (IS_ERR(tfm)) 205 return PTR_ERR(tfm); 206 207 rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields, 208 hash, tfm); 209 210 ima_free_tfm(tfm); 211 212 return rc; 213 } 214 215 static void __init ima_pcrread(int idx, u8 *pcr) 216 { 217 if (!ima_used_chip) 218 return; 219 220 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0) 221 pr_err("Error Communicating to TPM chip\n"); 222 } 223 224 /* 225 * Calculate the boot aggregate hash 226 */ 227 static int __init ima_calc_boot_aggregate_tfm(char *digest, 228 struct crypto_shash *tfm) 229 { 230 u8 pcr_i[TPM_DIGEST_SIZE]; 231 int rc, i; 232 struct { 233 struct shash_desc shash; 234 char ctx[crypto_shash_descsize(tfm)]; 235 } desc; 236 237 desc.shash.tfm = tfm; 238 desc.shash.flags = 0; 239 240 rc = crypto_shash_init(&desc.shash); 241 if (rc != 0) 242 return rc; 243 244 /* cumulative sha1 over tpm registers 0-7 */ 245 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 246 ima_pcrread(i, pcr_i); 247 /* now accumulate with current aggregate */ 248 rc = crypto_shash_update(&desc.shash, pcr_i, TPM_DIGEST_SIZE); 249 } 250 if (!rc) 251 crypto_shash_final(&desc.shash, digest); 252 return rc; 253 } 254 255 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash) 256 { 257 struct crypto_shash *tfm; 258 int rc; 259 260 tfm = ima_alloc_tfm(hash->algo); 261 if (IS_ERR(tfm)) 262 return PTR_ERR(tfm); 263 264 hash->length = crypto_shash_digestsize(tfm); 265 rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm); 266 267 ima_free_tfm(tfm); 268 269 return rc; 270 } 271