1 /*
2 * PSA ITS simulator over stdio files.
3 */
4 /*
5 * Copyright The Mbed TLS Contributors
6 * SPDX-License-Identifier: Apache-2.0
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License"); you may
9 * not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
16 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20
21 #include "common.h"
22
23 #if defined(MBEDTLS_PSA_ITS_FILE_C)
24
25 #include "mbedtls/platform.h"
26
27 #if defined(_WIN32)
28 #include <windows.h>
29 #endif
30
31 #include "psa_crypto_its.h"
32
33 #include <limits.h>
34 #include <stdint.h>
35 #include <stdio.h>
36 #include <string.h>
37
38 #if !defined(PSA_ITS_STORAGE_PREFIX)
39 #define PSA_ITS_STORAGE_PREFIX ""
40 #endif
41
42 #define PSA_ITS_STORAGE_FILENAME_PATTERN "%08x%08x"
43 #define PSA_ITS_STORAGE_SUFFIX ".psa_its"
44 #define PSA_ITS_STORAGE_FILENAME_LENGTH \
45 (sizeof(PSA_ITS_STORAGE_PREFIX) - 1 + /*prefix without terminating 0*/ \
46 16 + /*UID (64-bit number in hex)*/ \
47 sizeof(PSA_ITS_STORAGE_SUFFIX) - 1 + /*suffix without terminating 0*/ \
48 1 /*terminating null byte*/)
49 #define PSA_ITS_STORAGE_TEMP \
50 PSA_ITS_STORAGE_PREFIX "tempfile" PSA_ITS_STORAGE_SUFFIX
51
52 /* The maximum value of psa_storage_info_t.size */
53 #define PSA_ITS_MAX_SIZE 0xffffffff
54
55 #define PSA_ITS_MAGIC_STRING "PSA\0ITS\0"
56 #define PSA_ITS_MAGIC_LENGTH 8
57
58 /* As rename fails on Windows if the new filepath already exists,
59 * use MoveFileExA with the MOVEFILE_REPLACE_EXISTING flag instead.
60 * Returns 0 on success, nonzero on failure. */
61 #if defined(_WIN32)
62 #define rename_replace_existing(oldpath, newpath) \
63 (!MoveFileExA(oldpath, newpath, MOVEFILE_REPLACE_EXISTING))
64 #else
65 #define rename_replace_existing(oldpath, newpath) rename(oldpath, newpath)
66 #endif
67
68 typedef struct {
69 uint8_t magic[PSA_ITS_MAGIC_LENGTH];
70 uint8_t size[sizeof(uint32_t)];
71 uint8_t flags[sizeof(psa_storage_create_flags_t)];
72 } psa_its_file_header_t;
73
psa_its_fill_filename(psa_storage_uid_t uid,char * filename)74 static void psa_its_fill_filename(psa_storage_uid_t uid, char *filename)
75 {
76 /* Break up the UID into two 32-bit pieces so as not to rely on
77 * long long support in snprintf. */
78 mbedtls_snprintf(filename, PSA_ITS_STORAGE_FILENAME_LENGTH,
79 "%s" PSA_ITS_STORAGE_FILENAME_PATTERN "%s",
80 PSA_ITS_STORAGE_PREFIX,
81 (unsigned) (uid >> 32),
82 (unsigned) (uid & 0xffffffff),
83 PSA_ITS_STORAGE_SUFFIX);
84 }
85
psa_its_read_file(psa_storage_uid_t uid,struct psa_storage_info_t * p_info,FILE ** p_stream)86 static psa_status_t psa_its_read_file(psa_storage_uid_t uid,
87 struct psa_storage_info_t *p_info,
88 FILE **p_stream)
89 {
90 char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
91 psa_its_file_header_t header;
92 size_t n;
93
94 *p_stream = NULL;
95 psa_its_fill_filename(uid, filename);
96 *p_stream = fopen(filename, "rb");
97 if (*p_stream == NULL) {
98 return PSA_ERROR_DOES_NOT_EXIST;
99 }
100
101 /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
102 mbedtls_setbuf(*p_stream, NULL);
103
104 n = fread(&header, 1, sizeof(header), *p_stream);
105 if (n != sizeof(header)) {
106 return PSA_ERROR_DATA_CORRUPT;
107 }
108 if (memcmp(header.magic, PSA_ITS_MAGIC_STRING,
109 PSA_ITS_MAGIC_LENGTH) != 0) {
110 return PSA_ERROR_DATA_CORRUPT;
111 }
112
113 p_info->size = (header.size[0] |
114 header.size[1] << 8 |
115 header.size[2] << 16 |
116 header.size[3] << 24);
117 p_info->flags = (header.flags[0] |
118 header.flags[1] << 8 |
119 header.flags[2] << 16 |
120 header.flags[3] << 24);
121 return PSA_SUCCESS;
122 }
123
psa_its_get_info(psa_storage_uid_t uid,struct psa_storage_info_t * p_info)124 psa_status_t psa_its_get_info(psa_storage_uid_t uid,
125 struct psa_storage_info_t *p_info)
126 {
127 psa_status_t status;
128 FILE *stream = NULL;
129 status = psa_its_read_file(uid, p_info, &stream);
130 if (stream != NULL) {
131 fclose(stream);
132 }
133 return status;
134 }
135
psa_its_get(psa_storage_uid_t uid,uint32_t data_offset,uint32_t data_length,void * p_data,size_t * p_data_length)136 psa_status_t psa_its_get(psa_storage_uid_t uid,
137 uint32_t data_offset,
138 uint32_t data_length,
139 void *p_data,
140 size_t *p_data_length)
141 {
142 psa_status_t status;
143 FILE *stream = NULL;
144 size_t n;
145 struct psa_storage_info_t info;
146
147 status = psa_its_read_file(uid, &info, &stream);
148 if (status != PSA_SUCCESS) {
149 goto exit;
150 }
151 status = PSA_ERROR_INVALID_ARGUMENT;
152 if (data_offset + data_length < data_offset) {
153 goto exit;
154 }
155 #if SIZE_MAX < 0xffffffff
156 if (data_offset + data_length > SIZE_MAX) {
157 goto exit;
158 }
159 #endif
160 if (data_offset + data_length > info.size) {
161 goto exit;
162 }
163
164 status = PSA_ERROR_STORAGE_FAILURE;
165 #if LONG_MAX < 0xffffffff
166 while (data_offset > LONG_MAX) {
167 if (fseek(stream, LONG_MAX, SEEK_CUR) != 0) {
168 goto exit;
169 }
170 data_offset -= LONG_MAX;
171 }
172 #endif
173 if (fseek(stream, data_offset, SEEK_CUR) != 0) {
174 goto exit;
175 }
176 n = fread(p_data, 1, data_length, stream);
177 if (n != data_length) {
178 goto exit;
179 }
180 status = PSA_SUCCESS;
181 if (p_data_length != NULL) {
182 *p_data_length = n;
183 }
184
185 exit:
186 if (stream != NULL) {
187 fclose(stream);
188 }
189 return status;
190 }
191
psa_its_set(psa_storage_uid_t uid,uint32_t data_length,const void * p_data,psa_storage_create_flags_t create_flags)192 psa_status_t psa_its_set(psa_storage_uid_t uid,
193 uint32_t data_length,
194 const void *p_data,
195 psa_storage_create_flags_t create_flags)
196 {
197 if (uid == 0) {
198 return PSA_ERROR_INVALID_HANDLE;
199 }
200
201 psa_status_t status = PSA_ERROR_STORAGE_FAILURE;
202 char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
203 FILE *stream = NULL;
204 psa_its_file_header_t header;
205 size_t n;
206
207 memcpy(header.magic, PSA_ITS_MAGIC_STRING, PSA_ITS_MAGIC_LENGTH);
208 MBEDTLS_PUT_UINT32_LE(data_length, header.size, 0);
209 MBEDTLS_PUT_UINT32_LE(create_flags, header.flags, 0);
210
211 psa_its_fill_filename(uid, filename);
212 stream = fopen(PSA_ITS_STORAGE_TEMP, "wb");
213
214 if (stream == NULL) {
215 goto exit;
216 }
217
218 /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
219 mbedtls_setbuf(stream, NULL);
220
221 status = PSA_ERROR_INSUFFICIENT_STORAGE;
222 n = fwrite(&header, 1, sizeof(header), stream);
223 if (n != sizeof(header)) {
224 goto exit;
225 }
226 if (data_length != 0) {
227 n = fwrite(p_data, 1, data_length, stream);
228 if (n != data_length) {
229 goto exit;
230 }
231 }
232 status = PSA_SUCCESS;
233
234 exit:
235 if (stream != NULL) {
236 int ret = fclose(stream);
237 if (status == PSA_SUCCESS && ret != 0) {
238 status = PSA_ERROR_INSUFFICIENT_STORAGE;
239 }
240 }
241 if (status == PSA_SUCCESS) {
242 if (rename_replace_existing(PSA_ITS_STORAGE_TEMP, filename) != 0) {
243 status = PSA_ERROR_STORAGE_FAILURE;
244 }
245 }
246 /* The temporary file may still exist, but only in failure cases where
247 * we're already reporting an error. So there's nothing we can do on
248 * failure. If the function succeeded, and in some error cases, the
249 * temporary file doesn't exist and so remove() is expected to fail.
250 * Thus we just ignore the return status of remove(). */
251 (void) remove(PSA_ITS_STORAGE_TEMP);
252 return status;
253 }
254
psa_its_remove(psa_storage_uid_t uid)255 psa_status_t psa_its_remove(psa_storage_uid_t uid)
256 {
257 char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
258 FILE *stream;
259 psa_its_fill_filename(uid, filename);
260 stream = fopen(filename, "rb");
261 if (stream == NULL) {
262 return PSA_ERROR_DOES_NOT_EXIST;
263 }
264 fclose(stream);
265 if (remove(filename) != 0) {
266 return PSA_ERROR_STORAGE_FAILURE;
267 }
268 return PSA_SUCCESS;
269 }
270
271 #endif /* MBEDTLS_PSA_ITS_FILE_C */
272
