tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 "ima.h"
24
25static struct crypto_shash *ima_shash_tfm;
26
27int ima_init_crypto(void)
28{
29 long rc;
30
31 ima_shash_tfm = crypto_alloc_shash(ima_hash, 0, 0);
32 if (IS_ERR(ima_shash_tfm)) {
33 rc = PTR_ERR(ima_shash_tfm);
34 pr_err("Can not allocate %s (reason: %ld)\n", ima_hash, rc);
35 return rc;
36 }
37 return 0;
38}
39
40/*
41 * Calculate the MD5/SHA1 file digest
42 */
43int ima_calc_file_hash(struct file *file, char *digest)
44{
45 loff_t i_size, offset = 0;
46 char *rbuf;
47 int rc, read = 0;
48 struct {
49 struct shash_desc shash;
50 char ctx[crypto_shash_descsize(ima_shash_tfm)];
51 } desc;
52
53 desc.shash.tfm = ima_shash_tfm;
54 desc.shash.flags = 0;
55
56 rc = crypto_shash_init(&desc.shash);
57 if (rc != 0)
58 return rc;
59
60 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
61 if (!rbuf) {
62 rc = -ENOMEM;
63 goto out;
64 }
65 if (!(file->f_mode & FMODE_READ)) {
66 file->f_mode |= FMODE_READ;
67 read = 1;
68 }
69 i_size = i_size_read(file_inode(file));
70 while (offset < i_size) {
71 int rbuf_len;
72
73 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
74 if (rbuf_len < 0) {
75 rc = rbuf_len;
76 break;
77 }
78 if (rbuf_len == 0)
79 break;
80 offset += rbuf_len;
81
82 rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len);
83 if (rc)
84 break;
85 }
86 kfree(rbuf);
87 if (!rc)
88 rc = crypto_shash_final(&desc.shash, digest);
89 if (read)
90 file->f_mode &= ~FMODE_READ;
91out:
92 return rc;
93}
94
95/*
96 * Calculate the hash of a given buffer
97 */
98int ima_calc_buffer_hash(const void *data, int len, char *digest)
99{
100 struct {
101 struct shash_desc shash;
102 char ctx[crypto_shash_descsize(ima_shash_tfm)];
103 } desc;
104
105 desc.shash.tfm = ima_shash_tfm;
106 desc.shash.flags = 0;
107
108 return crypto_shash_digest(&desc.shash, data, len, digest);
109}
110
111static void __init ima_pcrread(int idx, u8 *pcr)
112{
113 if (!ima_used_chip)
114 return;
115
116 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
117 pr_err("IMA: Error Communicating to TPM chip\n");
118}
119
120/*
121 * Calculate the boot aggregate hash
122 */
123int __init ima_calc_boot_aggregate(char *digest)
124{
125 u8 pcr_i[IMA_DIGEST_SIZE];
126 int rc, i;
127 struct {
128 struct shash_desc shash;
129 char ctx[crypto_shash_descsize(ima_shash_tfm)];
130 } desc;
131
132 desc.shash.tfm = ima_shash_tfm;
133 desc.shash.flags = 0;
134
135 rc = crypto_shash_init(&desc.shash);
136 if (rc != 0)
137 return rc;
138
139 /* cumulative sha1 over tpm registers 0-7 */
140 for (i = TPM_PCR0; i < TPM_PCR8; i++) {
141 ima_pcrread(i, pcr_i);
142 /* now accumulate with current aggregate */
143 rc = crypto_shash_update(&desc.shash, pcr_i, IMA_DIGEST_SIZE);
144 }
145 if (!rc)
146 crypto_shash_final(&desc.shash, digest);
147 return rc;
148}