1/*
 2 * AppArmor security module
 3 *
 4 * This file contains AppArmor policy loading interface function definitions.
 5 *
 6 * Copyright 2013 Canonical Ltd.
 7 *
 8 * This program is free software; you can redistribute it and/or
 9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation, version 2 of the
11 * License.
12 *
13 * Fns to provide a checksum of policy that has been loaded this can be
14 * compared to userspace policy compiles to check loaded policy is what
15 * it should be.
16 */
17
18#include <crypto/hash.h>
19
20#include "include/apparmor.h"
21#include "include/crypto.h"
22
23static unsigned int apparmor_hash_size;
24
25static struct crypto_shash *apparmor_tfm;
26
27unsigned int aa_hash_size(void)
28{
29	return apparmor_hash_size;
30}
31
32int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
33			 size_t len)
34{
35	struct {
36		struct shash_desc shash;
37		char ctx[crypto_shash_descsize(apparmor_tfm)];
38	} desc;
39	int error = -ENOMEM;
40	u32 le32_version = cpu_to_le32(version);
41
42	if (!aa_g_hash_policy)
43		return 0;
44
45	if (!apparmor_tfm)
46		return 0;
47
48	profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
49	if (!profile->hash)
50		goto fail;
51
52	desc.shash.tfm = apparmor_tfm;
53	desc.shash.flags = 0;
54
55	error = crypto_shash_init(&desc.shash);
56	if (error)
57		goto fail;
58	error = crypto_shash_update(&desc.shash, (u8 *) &le32_version, 4);
59	if (error)
60		goto fail;
61	error = crypto_shash_update(&desc.shash, (u8 *) start, len);
62	if (error)
63		goto fail;
64	error = crypto_shash_final(&desc.shash, profile->hash);
65	if (error)
66		goto fail;
67
68	return 0;
69
70fail:
71	kfree(profile->hash);
72	profile->hash = NULL;
73
74	return error;
75}
76
77static int __init init_profile_hash(void)
78{
79	struct crypto_shash *tfm;
80
81	if (!apparmor_initialized)
82		return 0;
83
84	tfm = crypto_alloc_shash("sha1", 0, CRYPTO_ALG_ASYNC);
85	if (IS_ERR(tfm)) {
86		int error = PTR_ERR(tfm);
87		AA_ERROR("failed to setup profile sha1 hashing: %d\n", error);
88		return error;
89	}
90	apparmor_tfm = tfm;
91	apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
92
93	aa_info_message("AppArmor sha1 policy hashing enabled");
94
95	return 0;
96}
97
98late_initcall(init_profile_hash);