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
init_desc(struct hash_desc * desc)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 */
ima_calc_hash(struct file * file,char * digest)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;
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);
83 out:
84 crypto_free_hash(desc.tfm);
85 return rc;
86 }
87
88 /*
89 * Calculate the hash of a given template
90 */
ima_calc_template_hash(int template_len,void * template,char * digest)91 int 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
ima_pcrread(int idx,u8 * pcr)109 static 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 */
ima_calc_boot_aggregate(char * digest)121 int __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