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 /* 43 * Calculate the MD5/SHA1 file digest 44 */ 45 static int ima_calc_file_hash_tfm(struct file *file, 46 struct ima_digest_data *hash, 47 struct crypto_shash *tfm) 48 { 49 loff_t i_size, offset = 0; 50 char *rbuf; 51 int rc, read = 0; 52 struct { 53 struct shash_desc shash; 54 char ctx[crypto_shash_descsize(tfm)]; 55 } desc; 56 57 desc.shash.tfm = tfm; 58 desc.shash.flags = 0; 59 60 rc = crypto_shash_init(&desc.shash); 61 if (rc != 0) 62 return rc; 63 64 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); 65 if (!rbuf) { 66 rc = -ENOMEM; 67 goto out; 68 } 69 if (!(file->f_mode & FMODE_READ)) { 70 file->f_mode |= FMODE_READ; 71 read = 1; 72 } 73 i_size = i_size_read(file_inode(file)); 74 while (offset < i_size) { 75 int rbuf_len; 76 77 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE); 78 if (rbuf_len < 0) { 79 rc = rbuf_len; 80 break; 81 } 82 if (rbuf_len == 0) 83 break; 84 offset += rbuf_len; 85 86 rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len); 87 if (rc) 88 break; 89 } 90 kfree(rbuf); 91 if (!rc) 92 rc = crypto_shash_final(&desc.shash, hash->digest); 93 if (read) 94 file->f_mode &= ~FMODE_READ; 95 out: 96 return rc; 97 } 98 99 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) 100 { 101 struct crypto_shash *tfm = ima_shash_tfm; 102 int rc; 103 104 if (hash->algo != ima_hash_algo && hash->algo < HASH_ALGO__LAST) { 105 tfm = crypto_alloc_shash(hash_algo_name[hash->algo], 0, 0); 106 if (IS_ERR(tfm)) { 107 rc = PTR_ERR(tfm); 108 pr_err("Can not allocate %s (reason: %d)\n", 109 hash_algo_name[hash->algo], rc); 110 return rc; 111 } 112 } 113 114 hash->length = crypto_shash_digestsize(tfm); 115 116 rc = ima_calc_file_hash_tfm(file, hash, tfm); 117 118 if (tfm != ima_shash_tfm) 119 crypto_free_shash(tfm); 120 121 return rc; 122 } 123 124 /* 125 * Calculate the hash of a given buffer 126 */ 127 int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash) 128 { 129 struct { 130 struct shash_desc shash; 131 char ctx[crypto_shash_descsize(ima_shash_tfm)]; 132 } desc; 133 134 desc.shash.tfm = ima_shash_tfm; 135 desc.shash.flags = 0; 136 137 /* this function uses default algo */ 138 hash->algo = ima_hash_algo; 139 hash->length = crypto_shash_digestsize(ima_shash_tfm); 140 141 return crypto_shash_digest(&desc.shash, buf, len, hash->digest); 142 } 143 144 static void __init ima_pcrread(int idx, u8 *pcr) 145 { 146 if (!ima_used_chip) 147 return; 148 149 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0) 150 pr_err("IMA: Error Communicating to TPM chip\n"); 151 } 152 153 /* 154 * Calculate the boot aggregate hash 155 */ 156 int __init ima_calc_boot_aggregate(char *digest) 157 { 158 u8 pcr_i[IMA_DIGEST_SIZE]; 159 int rc, i; 160 struct { 161 struct shash_desc shash; 162 char ctx[crypto_shash_descsize(ima_shash_tfm)]; 163 } desc; 164 165 desc.shash.tfm = ima_shash_tfm; 166 desc.shash.flags = 0; 167 168 rc = crypto_shash_init(&desc.shash); 169 if (rc != 0) 170 return rc; 171 172 /* cumulative sha1 over tpm registers 0-7 */ 173 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 174 ima_pcrread(i, pcr_i); 175 /* now accumulate with current aggregate */ 176 rc = crypto_shash_update(&desc.shash, pcr_i, IMA_DIGEST_SIZE); 177 } 178 if (!rc) 179 crypto_shash_final(&desc.shash, digest); 180 return rc; 181 } 182