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
19 static unsigned int apparmor_hash_size;
20
21 static struct crypto_shash *apparmor_tfm;
22
23 unsigned int aa_hash_size(void)
24 {
25 return apparmor_hash_size;
26 }
27
28 char *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
55 fail:
56 kfree(hash);
57
58 return ERR_PTR(error);
59 }
60
61 int 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
95 fail:
96 kfree(profile->hash);
97 profile->hash = NULL;
98
99 return error;
100 }
101
102 static 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
123 late_initcall(init_profile_hash);
124
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