1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*
* Copyright (C) 2005,2006,2007,2008 IBM Corporation
*
* Authors:
* Mimi Zohar <zohar@us.ibm.com>
* Kylene Hall <kjhall@us.ibm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2 of the License.
*
* File: ima_crypto.c
* Calculates md5/sha1 file hash, template hash, boot-aggreate hash
*/
#include <linux/kernel.h>
#include <linux/file.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <linux/err.h>
#include <linux/slab.h>
#include "ima.h"
static int init_desc(struct hash_desc *desc)
{
int rc;
desc->tfm = crypto_alloc_hash(ima_hash, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(desc->tfm)) {
pr_info("failed to load %s transform: %ld\n",
ima_hash, PTR_ERR(desc->tfm));
rc = PTR_ERR(desc->tfm);
return rc;
}
desc->flags = 0;
rc = crypto_hash_init(desc);
if (rc)
crypto_free_hash(desc->tfm);
return rc;
}
/*
* Calculate the MD5/SHA1 file digest
*/
int ima_calc_hash(struct file *file, char *digest)
{
struct hash_desc desc;
struct scatterlist sg[1];
loff_t i_size, offset = 0;
char *rbuf;
int rc;
rc = init_desc(&desc);
if (rc != 0)
return rc;
rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!rbuf) {
rc = -ENOMEM;
goto out;
}
i_size = i_size_read(file->f_dentry->d_inode);
while (offset < i_size) {
int rbuf_len;
rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
if (rbuf_len < 0) {
rc = rbuf_len;
break;
}
if (rbuf_len == 0)
break;
offset += rbuf_len;
sg_init_one(sg, rbuf, rbuf_len);
rc = crypto_hash_update(&desc, sg, rbuf_len);
if (rc)
break;
}
kfree(rbuf);
if (!rc)
rc = crypto_hash_final(&desc, digest);
out:
crypto_free_hash(desc.tfm);
return rc;
}
/*
* Calculate the hash of a given template
*/
int ima_calc_template_hash(int template_len, void *template, char *digest)
{
struct hash_desc desc;
struct scatterlist sg[1];
int rc;
rc = init_desc(&desc);
if (rc != 0)
return rc;
sg_init_one(sg, template, template_len);
rc = crypto_hash_update(&desc, sg, template_len);
if (!rc)
rc = crypto_hash_final(&desc, digest);
crypto_free_hash(desc.tfm);
return rc;
}
static void __init ima_pcrread(int idx, u8 *pcr)
{
if (!ima_used_chip)
return;
if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
pr_err("Error Communicating to TPM chip\n");
}
/*
* Calculate the boot aggregate hash
*/
int __init ima_calc_boot_aggregate(char *digest)
{
struct hash_desc desc;
struct scatterlist sg;
u8 pcr_i[IMA_DIGEST_SIZE];
int rc, i;
rc = init_desc(&desc);
if (rc != 0)
return rc;
/* cumulative sha1 over tpm registers 0-7 */
for (i = TPM_PCR0; i < TPM_PCR8; i++) {
ima_pcrread(i, pcr_i);
/* now accumulate with current aggregate */
sg_init_one(&sg, pcr_i, IMA_DIGEST_SIZE);
rc = crypto_hash_update(&desc, &sg, IMA_DIGEST_SIZE);
}
if (!rc)
crypto_hash_final(&desc, digest);
crypto_free_hash(desc.tfm);
return rc;
}
|
