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 24static 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 */ 45int 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; 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 i_size = i_size_read(file->f_dentry->d_inode); 63 while (offset < i_size) { 64 int rbuf_len; 65 66 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE); 67 if (rbuf_len < 0) { 68 rc = rbuf_len; 69 break; 70 } 71 if (rbuf_len == 0) 72 break; 73 offset += rbuf_len; 74 sg_init_one(sg, rbuf, rbuf_len); 75 76 rc = crypto_hash_update(&desc, sg, rbuf_len); 77 if (rc) 78 break; 79 } 80 kfree(rbuf); 81 if (!rc) 82 rc = crypto_hash_final(&desc, digest); 83out: 84 crypto_free_hash(desc.tfm); 85 return rc; 86} 87 88/* 89 * Calculate the hash of a given template 90 */ 91int ima_calc_template_hash(int template_len, void *template, char *digest) 92{ 93 struct hash_desc desc; 94 struct scatterlist sg[1]; 95 int rc; 96 97 rc = init_desc(&desc); 98 if (rc != 0) 99 return rc; 100 101 sg_init_one(sg, template, template_len); 102 rc = crypto_hash_update(&desc, sg, template_len); 103 if (!rc) 104 rc = crypto_hash_final(&desc, digest); 105 crypto_free_hash(desc.tfm); 106 return rc; 107} 108 109static void __init ima_pcrread(int idx, u8 *pcr) 110{ 111 if (!ima_used_chip) 112 return; 113 114 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0) 115 pr_err("IMA: Error Communicating to TPM chip\n"); 116} 117 118/* 119 * Calculate the boot aggregate hash 120 */ 121int __init ima_calc_boot_aggregate(char *digest) 122{ 123 struct hash_desc desc; 124 struct scatterlist sg; 125 u8 pcr_i[IMA_DIGEST_SIZE]; 126 int rc, i; 127 128 rc = init_desc(&desc); 129 if (rc != 0) 130 return rc; 131 132 /* cumulative sha1 over tpm registers 0-7 */ 133 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 134 ima_pcrread(i, pcr_i); 135 /* now accumulate with current aggregate */ 136 sg_init_one(&sg, pcr_i, IMA_DIGEST_SIZE); 137 rc = crypto_hash_update(&desc, &sg, IMA_DIGEST_SIZE); 138 } 139 if (!rc) 140 crypto_hash_final(&desc, digest); 141 crypto_free_hash(desc.tfm); 142 return rc; 143} 144