blob: 952e51373f5810ac43aef5615c0e6ee166e4eb04 [file] [log] [blame]
Mimi Zohar3323eec92009-02-04 09:06:58 -05001/*
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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090021#include <linux/slab.h>
Mimi Zohar3323eec92009-02-04 09:06:58 -050022#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("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];
Mimi Zohar16bfa382009-08-21 14:32:49 -040049 loff_t i_size, offset = 0;
Mimi Zohar3323eec92009-02-04 09:06:58 -050050 char *rbuf;
Mimi Zohar16bfa382009-08-21 14:32:49 -040051 int rc;
Mimi Zohar3323eec92009-02-04 09:06:58 -050052
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 }
Mimi Zohar16bfa382009-08-21 14:32:49 -040071 if (rbuf_len == 0)
72 break;
Mimi Zohar3323eec92009-02-04 09:06:58 -050073 offset += rbuf_len;
Mimi Zohar0da0a422009-02-19 21:23:50 -050074 sg_init_one(sg, rbuf, rbuf_len);
Mimi Zohar3323eec92009-02-04 09:06:58 -050075
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
Mimi Zohar0da0a422009-02-19 21:23:50 -0500101 sg_init_one(sg, template, template_len);
Mimi Zohar3323eec92009-02-04 09:06:58 -0500102 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
Eric Paris932995f2009-05-21 15:43:32 -0400109static void __init ima_pcrread(int idx, u8 *pcr)
Mimi Zohar3323eec92009-02-04 09:06:58 -0500110{
111 if (!ima_used_chip)
112 return;
113
114 if (tpm_pcr_read(TPM_ANY_NUM, idx, pcr) != 0)
115 pr_err("Error Communicating to TPM chip\n");
116}
117
118/*
119 * Calculate the boot aggregate hash
120 */
Eric Paris932995f2009-05-21 15:43:32 -0400121int __init ima_calc_boot_aggregate(char *digest)
Mimi Zohar3323eec92009-02-04 09:06:58 -0500122{
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}