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 "ima.h" 23 24 static int init_desc(struct hash_desc *desc) 25 { 26 int rc; 27 28 desc->tfm = crypto_alloc_hash(ima_hash, 0, CRYPTO_ALG_ASYNC); 29 if (IS_ERR(desc->tfm)) { 30 pr_info("IMA: failed to load %s transform: %ld\n", 31 ima_hash, PTR_ERR(desc->tfm)); 32 rc = PTR_ERR(desc->tfm); 33 return rc; 34 } 35 desc->flags = 0; 36 rc = crypto_hash_init(desc); 37 if (rc) 38 crypto_free_hash(desc->tfm); 39 return rc; 40 } 41 42 /* 43 * Calculate the MD5/SHA1 file digest 44 */ 45 int ima_calc_hash(struct file *file, char *digest) 46 { 47 struct hash_desc desc; 48 struct scatterlist sg[1]; 49 loff_t i_size, offset = 0; 50 char *rbuf; 51 int rc, read = 0; 52 53 rc = init_desc(&desc); 54 if (rc != 0) 55 return rc; 56 57 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); 58 if (!rbuf) { 59 rc = -ENOMEM; 60 goto out; 61 } 62 if (!(file->f_mode & FMODE_READ)) { 63 file->f_mode |= FMODE_READ; 64 read = 1; 65 } 66 i_size = i_size_read(file->f_dentry->d_inode); 67 while (offset < i_size) { 68 int rbuf_len; 69 70 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE); 71 if (rbuf_len < 0) { 72 rc = rbuf_len; 73 break; 74 } 75 if (rbuf_len == 0) 76 break; 77 offset += rbuf_len; 78 sg_init_one(sg, rbuf, rbuf_len); 79 80 rc = crypto_hash_update(&desc, sg, rbuf_len); 81 if (rc) 82 break; 83 } 84 kfree(rbuf); 85 if (!rc) 86 rc = crypto_hash_final(&desc, digest); 87 if (read) 88 file->f_mode &= ~FMODE_READ; 89 out: 90 crypto_free_hash(desc.tfm); 91 return rc; 92 } 93 94 /* 95 * Calculate the hash of a given template 96 */ 97 int ima_calc_template_hash(int template_len, void *template, char *digest) 98 { 99 struct hash_desc desc; 100 struct scatterlist sg[1]; 101 int rc; 102 103 rc = init_desc(&desc); 104 if (rc != 0) 105 return rc; 106 107 sg_init_one(sg, template, template_len); 108 rc = crypto_hash_update(&desc, sg, template_len); 109 if (!rc) 110 rc = crypto_hash_final(&desc, digest); 111 crypto_free_hash(desc.tfm); 112 return rc; 113 } 114 115 static void __init ima_pcrread(int idx, u8 *pcr) 116 { 117 if (!ima_used_chip) 118 return; 119 120 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0) 121 pr_err("IMA: Error Communicating to TPM chip\n"); 122 } 123 124 /* 125 * Calculate the boot aggregate hash 126 */ 127 int __init ima_calc_boot_aggregate(char *digest) 128 { 129 struct hash_desc desc; 130 struct scatterlist sg; 131 u8 pcr_i[IMA_DIGEST_SIZE]; 132 int rc, i; 133 134 rc = init_desc(&desc); 135 if (rc != 0) 136 return rc; 137 138 /* cumulative sha1 over tpm registers 0-7 */ 139 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 140 ima_pcrread(i, pcr_i); 141 /* now accumulate with current aggregate */ 142 sg_init_one(&sg, pcr_i, IMA_DIGEST_SIZE); 143 rc = crypto_hash_update(&desc, &sg, IMA_DIGEST_SIZE); 144 } 145 if (!rc) 146 crypto_hash_final(&desc, digest); 147 crypto_free_hash(desc.tfm); 148 return rc; 149 } 150