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 <crypto/hash_info.h>
24#include "ima.h"
25
26static struct crypto_shash *ima_shash_tfm;
27
28int ima_init_crypto(void)
29{
30 long rc;
31
32 ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
33 if (IS_ERR(ima_shash_tfm)) {
34 rc = PTR_ERR(ima_shash_tfm);
35 pr_err("Can not allocate %s (reason: %ld)\n",
36 hash_algo_name[ima_hash_algo], rc);
37 return rc;
38 }
39 return 0;
40}
41
42static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
43{
44 struct crypto_shash *tfm = ima_shash_tfm;
45 int rc;
46
47 if (algo != ima_hash_algo && algo < HASH_ALGO__LAST) {
48 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
49 if (IS_ERR(tfm)) {
50 rc = PTR_ERR(tfm);
51 pr_err("Can not allocate %s (reason: %d)\n",
52 hash_algo_name[algo], rc);
53 }
54 }
55 return tfm;
56}
57
58static void ima_free_tfm(struct crypto_shash *tfm)
59{
60 if (tfm != ima_shash_tfm)
61 crypto_free_shash(tfm);
62}
63
64/*
65 * Calculate the MD5/SHA1 file digest
66 */
67static int ima_calc_file_hash_tfm(struct file *file,
68 struct ima_digest_data *hash,
69 struct crypto_shash *tfm)
70{
71 loff_t i_size, offset = 0;
72 char *rbuf;
73 int rc, read = 0;
74 struct {
75 struct shash_desc shash;
76 char ctx[crypto_shash_descsize(tfm)];
77 } desc;
78
79 desc.shash.tfm = tfm;
80 desc.shash.flags = 0;
81
82 hash->length = crypto_shash_digestsize(tfm);
83
84 rc = crypto_shash_init(&desc.shash);
85 if (rc != 0)
86 return rc;
87
88 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
89 if (!rbuf) {
90 rc = -ENOMEM;
91 goto out;
92 }
93 if (!(file->f_mode & FMODE_READ)) {
94 file->f_mode |= FMODE_READ;
95 read = 1;
96 }
97 i_size = i_size_read(file_inode(file));
98 while (offset < i_size) {
99 int rbuf_len;
100
101 rbuf_len = kernel_read(file, offset, rbuf, PAGE_SIZE);
102 if (rbuf_len < 0) {
103 rc = rbuf_len;
104 break;
105 }
106 if (rbuf_len == 0)
107 break;
108 offset += rbuf_len;
109
110 rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len);
111 if (rc)
112 break;
113 }
114 kfree(rbuf);
115 if (!rc)
116 rc = crypto_shash_final(&desc.shash, hash->digest);
117 if (read)
118 file->f_mode &= ~FMODE_READ;
119out:
120 return rc;
121}
122
123int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
124{
125 struct crypto_shash *tfm;
126 int rc;
127
128 tfm = ima_alloc_tfm(hash->algo);
129 if (IS_ERR(tfm))
130 return PTR_ERR(tfm);
131
132 rc = ima_calc_file_hash_tfm(file, hash, tfm);
133
134 ima_free_tfm(tfm);
135
136 return rc;
137}
138
139/*
140 * Calculate the hash of template data
141 */
142static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
143 struct ima_template_desc *td,
144 int num_fields,
145 struct ima_digest_data *hash,
146 struct crypto_shash *tfm)
147{
148 struct {
149 struct shash_desc shash;
150 char ctx[crypto_shash_descsize(tfm)];
151 } desc;
152 int rc, i;
153
154 desc.shash.tfm = tfm;
155 desc.shash.flags = 0;
156
157 hash->length = crypto_shash_digestsize(tfm);
158
159 rc = crypto_shash_init(&desc.shash);
160 if (rc != 0)
161 return rc;
162
163 for (i = 0; i < num_fields; i++) {
164 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
165 rc = crypto_shash_update(&desc.shash,
166 (const u8 *) &field_data[i].len,
167 sizeof(field_data[i].len));
168 if (rc)
169 break;
170 }
171 rc = crypto_shash_update(&desc.shash, field_data[i].data,
172 field_data[i].len);
173 if (rc)
174 break;
175 }
176
177 if (!rc)
178 rc = crypto_shash_final(&desc.shash, hash->digest);
179
180 return rc;
181}
182
183int ima_calc_field_array_hash(struct ima_field_data *field_data,
184 struct ima_template_desc *desc, int num_fields,
185 struct ima_digest_data *hash)
186{
187 struct crypto_shash *tfm;
188 int rc;
189
190 tfm = ima_alloc_tfm(hash->algo);
191 if (IS_ERR(tfm))
192 return PTR_ERR(tfm);
193
194 rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
195 hash, tfm);
196
197 ima_free_tfm(tfm);
198
199 return rc;
200}
201
202static void __init ima_pcrread(int idx, u8 *pcr)
203{
204 if (!ima_used_chip)
205 return;
206
207 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
208 pr_err("IMA: Error Communicating to TPM chip\n");
209}
210
211/*
212 * Calculate the boot aggregate hash
213 */
214static int __init ima_calc_boot_aggregate_tfm(char *digest,
215 struct crypto_shash *tfm)
216{
217 u8 pcr_i[TPM_DIGEST_SIZE];
218 int rc, i;
219 struct {
220 struct shash_desc shash;
221 char ctx[crypto_shash_descsize(tfm)];
222 } desc;
223
224 desc.shash.tfm = tfm;
225 desc.shash.flags = 0;
226
227 rc = crypto_shash_init(&desc.shash);
228 if (rc != 0)
229 return rc;
230
231 /* cumulative sha1 over tpm registers 0-7 */
232 for (i = TPM_PCR0; i < TPM_PCR8; i++) {
233 ima_pcrread(i, pcr_i);
234 /* now accumulate with current aggregate */
235 rc = crypto_shash_update(&desc.shash, pcr_i, TPM_DIGEST_SIZE);
236 }
237 if (!rc)
238 crypto_shash_final(&desc.shash, digest);
239 return rc;
240}
241
242int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
243{
244 struct crypto_shash *tfm;
245 int rc;
246
247 tfm = ima_alloc_tfm(hash->algo);
248 if (IS_ERR(tfm))
249 return PTR_ERR(tfm);
250
251 hash->length = crypto_shash_digestsize(tfm);
252 rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
253
254 ima_free_tfm(tfm);
255
256 return rc;
257}