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
23 static unsigned int apparmor_hash_size;
24
25 static struct crypto_shash *apparmor_tfm;
26
aa_hash_size(void)27 unsigned int aa_hash_size(void)
28 {
29 return apparmor_hash_size;
30 }
31
aa_calc_hash(void * data,size_t len)32 char *aa_calc_hash(void *data, size_t len)
33 {
34 SHASH_DESC_ON_STACK(desc, apparmor_tfm);
35 char *hash = NULL;
36 int error = -ENOMEM;
37
38 if (!apparmor_tfm)
39 return NULL;
40
41 hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
42 if (!hash)
43 goto fail;
44
45 desc->tfm = apparmor_tfm;
46 desc->flags = 0;
47
48 error = crypto_shash_init(desc);
49 if (error)
50 goto fail;
51 error = crypto_shash_update(desc, (u8 *) data, len);
52 if (error)
53 goto fail;
54 error = crypto_shash_final(desc, hash);
55 if (error)
56 goto fail;
57
58 return hash;
59
60 fail:
61 kfree(hash);
62
63 return ERR_PTR(error);
64 }
65
aa_calc_profile_hash(struct aa_profile * profile,u32 version,void * start,size_t len)66 int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start,
67 size_t len)
68 {
69 SHASH_DESC_ON_STACK(desc, apparmor_tfm);
70 int error = -ENOMEM;
71 __le32 le32_version = cpu_to_le32(version);
72
73 if (!aa_g_hash_policy)
74 return 0;
75
76 if (!apparmor_tfm)
77 return 0;
78
79 profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL);
80 if (!profile->hash)
81 goto fail;
82
83 desc->tfm = apparmor_tfm;
84 desc->flags = 0;
85
86 error = crypto_shash_init(desc);
87 if (error)
88 goto fail;
89 error = crypto_shash_update(desc, (u8 *) &le32_version, 4);
90 if (error)
91 goto fail;
92 error = crypto_shash_update(desc, (u8 *) start, len);
93 if (error)
94 goto fail;
95 error = crypto_shash_final(desc, profile->hash);
96 if (error)
97 goto fail;
98
99 return 0;
100
101 fail:
102 kfree(profile->hash);
103 profile->hash = NULL;
104
105 return error;
106 }
107
init_profile_hash(void)108 static int __init init_profile_hash(void)
109 {
110 struct crypto_shash *tfm;
111
112 if (!apparmor_initialized)
113 return 0;
114
115 tfm = crypto_alloc_shash("sha1", 0, CRYPTO_ALG_ASYNC);
116 if (IS_ERR(tfm)) {
117 int error = PTR_ERR(tfm);
118 AA_ERROR("failed to setup profile sha1 hashing: %d\n", error);
119 return error;
120 }
121 apparmor_tfm = tfm;
122 apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm);
123
124 aa_info_message("AppArmor sha1 policy hashing enabled");
125
126 return 0;
127 }
128
129 late_initcall(init_profile_hash);
130