Merge tag 'docs-5.12-2' of git://git.lwn.net/linux
[sfrench/cifs-2.6.git] / security / integrity / digsig.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2011 Intel Corporation
4  *
5  * Author:
6  * Dmitry Kasatkin <dmitry.kasatkin@intel.com>
7  */
8
9 #include <linux/err.h>
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/cred.h>
13 #include <linux/kernel_read_file.h>
14 #include <linux/key-type.h>
15 #include <linux/digsig.h>
16 #include <linux/vmalloc.h>
17 #include <crypto/public_key.h>
18 #include <keys/system_keyring.h>
19
20 #include "integrity.h"
21
22 static struct key *keyring[INTEGRITY_KEYRING_MAX];
23
24 static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
25 #ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
26         "_evm",
27         "_ima",
28 #else
29         ".evm",
30         ".ima",
31 #endif
32         ".platform",
33 };
34
35 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
36 #define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
37 #else
38 #define restrict_link_to_ima restrict_link_by_builtin_trusted
39 #endif
40
41 static struct key *integrity_keyring_from_id(const unsigned int id)
42 {
43         if (id >= INTEGRITY_KEYRING_MAX)
44                 return ERR_PTR(-EINVAL);
45
46         if (!keyring[id]) {
47                 keyring[id] =
48                         request_key(&key_type_keyring, keyring_name[id], NULL);
49                 if (IS_ERR(keyring[id])) {
50                         int err = PTR_ERR(keyring[id]);
51                         pr_err("no %s keyring: %d\n", keyring_name[id], err);
52                         keyring[id] = NULL;
53                         return ERR_PTR(err);
54                 }
55         }
56
57         return keyring[id];
58 }
59
60 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
61                             const char *digest, int digestlen)
62 {
63         struct key *keyring;
64
65         if (siglen < 2)
66                 return -EINVAL;
67
68         keyring = integrity_keyring_from_id(id);
69         if (IS_ERR(keyring))
70                 return PTR_ERR(keyring);
71
72         switch (sig[1]) {
73         case 1:
74                 /* v1 API expect signature without xattr type */
75                 return digsig_verify(keyring, sig + 1, siglen - 1, digest,
76                                      digestlen);
77         case 2:
78                 return asymmetric_verify(keyring, sig, siglen, digest,
79                                          digestlen);
80         }
81
82         return -EOPNOTSUPP;
83 }
84
85 int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig)
86 {
87         struct key *keyring;
88
89         keyring = integrity_keyring_from_id(id);
90         if (IS_ERR(keyring))
91                 return PTR_ERR(keyring);
92
93         return ima_modsig_verify(keyring, modsig);
94 }
95
96 static int __init __integrity_init_keyring(const unsigned int id,
97                                            key_perm_t perm,
98                                            struct key_restriction *restriction)
99 {
100         const struct cred *cred = current_cred();
101         int err = 0;
102
103         keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
104                                     KGIDT_INIT(0), cred, perm,
105                                     KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL);
106         if (IS_ERR(keyring[id])) {
107                 err = PTR_ERR(keyring[id]);
108                 pr_info("Can't allocate %s keyring (%d)\n",
109                         keyring_name[id], err);
110                 keyring[id] = NULL;
111         } else {
112                 if (id == INTEGRITY_KEYRING_PLATFORM)
113                         set_platform_trusted_keys(keyring[id]);
114         }
115
116         return err;
117 }
118
119 int __init integrity_init_keyring(const unsigned int id)
120 {
121         struct key_restriction *restriction;
122         key_perm_t perm;
123
124         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
125                 | KEY_USR_READ | KEY_USR_SEARCH;
126
127         if (id == INTEGRITY_KEYRING_PLATFORM) {
128                 restriction = NULL;
129                 goto out;
130         }
131
132         if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING))
133                 return 0;
134
135         restriction = kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
136         if (!restriction)
137                 return -ENOMEM;
138
139         restriction->check = restrict_link_to_ima;
140         perm |= KEY_USR_WRITE;
141
142 out:
143         return __integrity_init_keyring(id, perm, restriction);
144 }
145
146 int __init integrity_add_key(const unsigned int id, const void *data,
147                              off_t size, key_perm_t perm)
148 {
149         key_ref_t key;
150         int rc = 0;
151
152         if (!keyring[id])
153                 return -EINVAL;
154
155         key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric",
156                                    NULL, data, size, perm,
157                                    KEY_ALLOC_NOT_IN_QUOTA);
158         if (IS_ERR(key)) {
159                 rc = PTR_ERR(key);
160                 pr_err("Problem loading X.509 certificate %d\n", rc);
161         } else {
162                 pr_notice("Loaded X.509 cert '%s'\n",
163                           key_ref_to_ptr(key)->description);
164                 key_ref_put(key);
165         }
166
167         return rc;
168
169 }
170
171 int __init integrity_load_x509(const unsigned int id, const char *path)
172 {
173         void *data = NULL;
174         size_t size;
175         int rc;
176         key_perm_t perm;
177
178         rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL,
179                                         READING_X509_CERTIFICATE);
180         if (rc < 0) {
181                 pr_err("Unable to open file: %s (%d)", path, rc);
182                 return rc;
183         }
184         size = rc;
185
186         perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ;
187
188         pr_info("Loading X.509 certificate: %s\n", path);
189         rc = integrity_add_key(id, (const void *)data, size, perm);
190
191         vfree(data);
192         return rc;
193 }
194
195 int __init integrity_load_cert(const unsigned int id, const char *source,
196                                const void *data, size_t len, key_perm_t perm)
197 {
198         if (!data)
199                 return -EINVAL;
200
201         pr_info("Loading X.509 certificate: %s\n", source);
202         return integrity_add_key(id, data, len, perm);
203 }