1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor policy loading interface function definitions.
6 *
7 * Copyright 2013 Canonical Ltd.
8 *
9 * Fns to provide a checksum of policy that has been loaded this can be
10 * compared to userspace policy compiles to check loaded policy is what
11 * it should be.
12 */
13
14#include <crypto/hash.h>
15
16#include "include/apparmor.h"
17#include "include/crypto.h"
18
19static unsigned int apparmor_hash_size;
20
21static struct crypto_shash *apparmor_tfm;
22
23unsigned int aa_hash_size(void)
24{
25	return apparmor_hash_size;
26}
27
28char *aa_calc_hash(void *data, size_t len)
29{
30	SHASH_DESC_ON_STACK(desc, apparmor_tfm);
31	char *hash;
32	int error;
33
34	if (!apparmor_tfm)
35		return NULL;
36
37	hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
38	if (!hash)
39		return ERR_PTR(-ENOMEM);
40
41	desc->tfm = apparmor_tfm;
42
43	error = crypto_shash_init(desc);
44	if (error)
45		goto fail;
46	error = crypto_shash_update(desc, (u8 *) data, len);
47	if (error)
48		goto fail;
49	error = crypto_shash_final(desc, hash);
50	if (error)
51		goto fail;
52
53	return hash;
54
55fail:
56	kfree(hash);
57
58	return ERR_PTR(error);
59}
60
61int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
62			 size_t len)
63{
64	SHASH_DESC_ON_STACK(desc, apparmor_tfm);
65	int error;
66	__le32 le32_version = cpu_to_le32(version);
67
68	if (!aa_g_hash_policy)
69		return 0;
70
71	if (!apparmor_tfm)
72		return 0;
73
74	profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
75	if (!profile->hash)
76		return -ENOMEM;
77
78	desc->tfm = apparmor_tfm;
79
80	error = crypto_shash_init(desc);
81	if (error)
82		goto fail;
83	error = crypto_shash_update(desc, (u8 *) &le32_version, 4);
84	if (error)
85		goto fail;
86	error = crypto_shash_update(desc, (u8 *) start, len);
87	if (error)
88		goto fail;
89	error = crypto_shash_final(desc, profile->hash);
90	if (error)
91		goto fail;
92
93	return 0;
94
95fail:
96	kfree(profile->hash);
97	profile->hash = NULL;
98
99	return error;
100}
101
102static int __init init_profile_hash(void)
103{
104	struct crypto_shash *tfm;
105
106	if (!apparmor_initialized)
107		return 0;
108
109	tfm = crypto_alloc_shash("sha256", 0, 0);
110	if (IS_ERR(tfm)) {
111		int error = PTR_ERR(tfm);
112		AA_ERROR("failed to setup profile sha256 hashing: %d\n", error);
113		return error;
114	}
115	apparmor_tfm = tfm;
116	apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
117
118	aa_info_message("AppArmor sha256 policy hashing enabled");
119
120	return 0;
121}
122
123late_initcall(init_profile_hash);
124