1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 #include <openssl/pem.h>
4
5 #include "fd-util.h"
6 #include "user-record-sign.h"
7 #include "fileio.h"
8
user_record_signable_json(UserRecord * ur,char ** ret)9 static int user_record_signable_json(UserRecord *ur, char **ret) {
10 _cleanup_(user_record_unrefp) UserRecord *reduced = NULL;
11 _cleanup_(json_variant_unrefp) JsonVariant *j = NULL;
12 int r;
13
14 assert(ur);
15 assert(ret);
16
17 r = user_record_clone(ur, USER_RECORD_REQUIRE_REGULAR|USER_RECORD_ALLOW_PRIVILEGED|USER_RECORD_ALLOW_PER_MACHINE|USER_RECORD_STRIP_SECRET|USER_RECORD_STRIP_BINDING|USER_RECORD_STRIP_STATUS|USER_RECORD_STRIP_SIGNATURE|USER_RECORD_PERMISSIVE, &reduced);
18 if (r < 0)
19 return r;
20
21 j = json_variant_ref(reduced->json);
22
23 r = json_variant_normalize(&j);
24 if (r < 0)
25 return r;
26
27 return json_variant_format(j, 0, ret);
28 }
29
30 DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(EVP_MD_CTX*, EVP_MD_CTX_free, NULL);
31
user_record_sign(UserRecord * ur,EVP_PKEY * private_key,UserRecord ** ret)32 int user_record_sign(UserRecord *ur, EVP_PKEY *private_key, UserRecord **ret) {
33 _cleanup_(json_variant_unrefp) JsonVariant *encoded = NULL, *v = NULL;
34 _cleanup_(user_record_unrefp) UserRecord *signed_ur = NULL;
35 _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *md_ctx = NULL;
36 _cleanup_free_ char *text = NULL, *key = NULL;
37 size_t signature_size = 0, key_size = 0;
38 _cleanup_free_ void *signature = NULL;
39 _cleanup_fclose_ FILE *mf = NULL;
40 int r;
41
42 assert(ur);
43 assert(private_key);
44 assert(ret);
45
46 r = user_record_signable_json(ur, &text);
47 if (r < 0)
48 return r;
49
50 md_ctx = EVP_MD_CTX_new();
51 if (!md_ctx)
52 return -ENOMEM;
53
54 if (EVP_DigestSignInit(md_ctx, NULL, NULL, NULL, private_key) <= 0)
55 return -EIO;
56
57 /* Request signature size */
58 if (EVP_DigestSign(md_ctx, NULL, &signature_size, (uint8_t*) text, strlen(text)) <= 0)
59 return -EIO;
60
61 signature = malloc(signature_size);
62 if (!signature)
63 return -ENOMEM;
64
65 if (EVP_DigestSign(md_ctx, signature, &signature_size, (uint8_t*) text, strlen(text)) <= 0)
66 return -EIO;
67
68 mf = open_memstream_unlocked(&key, &key_size);
69 if (!mf)
70 return -ENOMEM;
71
72 if (PEM_write_PUBKEY(mf, private_key) <= 0)
73 return -EIO;
74
75 r = fflush_and_check(mf);
76 if (r < 0)
77 return r;
78
79 r = json_build(&encoded, JSON_BUILD_ARRAY(
80 JSON_BUILD_OBJECT(JSON_BUILD_PAIR("data", JSON_BUILD_BASE64(signature, signature_size)),
81 JSON_BUILD_PAIR("key", JSON_BUILD_STRING(key)))));
82 if (r < 0)
83 return r;
84
85 v = json_variant_ref(ur->json);
86
87 r = json_variant_set_field(&v, "signature", encoded);
88 if (r < 0)
89 return r;
90
91 if (DEBUG_LOGGING)
92 json_variant_dump(v, JSON_FORMAT_PRETTY|JSON_FORMAT_COLOR_AUTO, NULL, NULL);
93
94 signed_ur = user_record_new();
95 if (!signed_ur)
96 return log_oom();
97
98 r = user_record_load(signed_ur, v, USER_RECORD_LOAD_FULL|USER_RECORD_PERMISSIVE);
99 if (r < 0)
100 return r;
101
102 *ret = TAKE_PTR(signed_ur);
103 return 0;
104 }
105
user_record_verify(UserRecord * ur,EVP_PKEY * public_key)106 int user_record_verify(UserRecord *ur, EVP_PKEY *public_key) {
107 _cleanup_free_ char *text = NULL;
108 unsigned n_good = 0, n_bad = 0;
109 JsonVariant *array, *e;
110 int r;
111
112 assert(ur);
113 assert(public_key);
114
115 array = json_variant_by_key(ur->json, "signature");
116 if (!array)
117 return USER_RECORD_UNSIGNED;
118
119 if (!json_variant_is_array(array))
120 return -EINVAL;
121
122 if (json_variant_elements(array) == 0)
123 return USER_RECORD_UNSIGNED;
124
125 r = user_record_signable_json(ur, &text);
126 if (r < 0)
127 return r;
128
129 JSON_VARIANT_ARRAY_FOREACH(e, array) {
130 _cleanup_(EVP_MD_CTX_freep) EVP_MD_CTX *md_ctx = NULL;
131 _cleanup_free_ void *signature = NULL;
132 size_t signature_size = 0;
133 JsonVariant *data;
134
135 if (!json_variant_is_object(e))
136 return -EINVAL;
137
138 data = json_variant_by_key(e, "data");
139 if (!data)
140 return -EINVAL;
141
142 r = json_variant_unbase64(data, &signature, &signature_size);
143 if (r < 0)
144 return r;
145
146 md_ctx = EVP_MD_CTX_new();
147 if (!md_ctx)
148 return -ENOMEM;
149
150 if (EVP_DigestVerifyInit(md_ctx, NULL, NULL, NULL, public_key) <= 0)
151 return -EIO;
152
153 if (EVP_DigestVerify(md_ctx, signature, signature_size, (uint8_t*) text, strlen(text)) <= 0) {
154 n_bad ++;
155 continue;
156 }
157
158 n_good ++;
159 }
160
161 return n_good > 0 ? (n_bad == 0 ? USER_RECORD_SIGNED_EXCLUSIVE : USER_RECORD_SIGNED) :
162 (n_bad == 0 ? USER_RECORD_UNSIGNED : USER_RECORD_FOREIGN);
163 }
164
user_record_has_signature(UserRecord * ur)165 int user_record_has_signature(UserRecord *ur) {
166 JsonVariant *array;
167
168 array = json_variant_by_key(ur->json, "signature");
169 if (!array)
170 return false;
171
172 if (!json_variant_is_array(array))
173 return -EINVAL;
174
175 return json_variant_elements(array) > 0;
176 }
177