1 /*
2 * PSA ITS simulator over stdio files.
3 */
4 /*
5 * Copyright The Mbed TLS Contributors
6 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
7 */
8
9 #include "common.h"
10
11 #if defined(MBEDTLS_PSA_ITS_FILE_C)
12
13 #include "mbedtls/platform.h"
14
15 #if defined(_WIN32)
16 #include <windows.h>
17 #endif
18
19 #include "psa_crypto_its.h"
20
21 #include <limits.h>
22 #include <stdint.h>
23 #include <stdio.h>
24 #include <string.h>
25
26 #if !defined(PSA_ITS_STORAGE_PREFIX)
27 #define PSA_ITS_STORAGE_PREFIX ""
28 #endif
29
30 #define PSA_ITS_STORAGE_FILENAME_PATTERN "%08x%08x"
31 #define PSA_ITS_STORAGE_SUFFIX ".psa_its"
32 #define PSA_ITS_STORAGE_FILENAME_LENGTH \
33 (sizeof(PSA_ITS_STORAGE_PREFIX) - 1 + /*prefix without terminating 0*/ \
34 16 + /*UID (64-bit number in hex)*/ \
35 sizeof(PSA_ITS_STORAGE_SUFFIX) - 1 + /*suffix without terminating 0*/ \
36 1 /*terminating null byte*/)
37 #define PSA_ITS_STORAGE_TEMP \
38 PSA_ITS_STORAGE_PREFIX "tempfile" PSA_ITS_STORAGE_SUFFIX
39
40 /* The maximum value of psa_storage_info_t.size */
41 #define PSA_ITS_MAX_SIZE 0xffffffff
42
43 #define PSA_ITS_MAGIC_STRING "PSA\0ITS\0"
44 #define PSA_ITS_MAGIC_LENGTH 8
45
46 /* As rename fails on Windows if the new filepath already exists,
47 * use MoveFileExA with the MOVEFILE_REPLACE_EXISTING flag instead.
48 * Returns 0 on success, nonzero on failure. */
49 #if defined(_WIN32)
50 #define rename_replace_existing(oldpath, newpath) \
51 (!MoveFileExA(oldpath, newpath, MOVEFILE_REPLACE_EXISTING))
52 #else
53 #define rename_replace_existing(oldpath, newpath) rename(oldpath, newpath)
54 #endif
55
56 typedef struct {
57 uint8_t magic[PSA_ITS_MAGIC_LENGTH];
58 uint8_t size[sizeof(uint32_t)];
59 uint8_t flags[sizeof(psa_storage_create_flags_t)];
60 } psa_its_file_header_t;
61
psa_its_fill_filename(psa_storage_uid_t uid,char * filename)62 static void psa_its_fill_filename(psa_storage_uid_t uid, char *filename)
63 {
64 /* Break up the UID into two 32-bit pieces so as not to rely on
65 * long long support in snprintf. */
66 mbedtls_snprintf(filename, PSA_ITS_STORAGE_FILENAME_LENGTH,
67 "%s" PSA_ITS_STORAGE_FILENAME_PATTERN "%s",
68 PSA_ITS_STORAGE_PREFIX,
69 (unsigned) (uid >> 32),
70 (unsigned) (uid & 0xffffffff),
71 PSA_ITS_STORAGE_SUFFIX);
72 }
73
psa_its_read_file(psa_storage_uid_t uid,struct psa_storage_info_t * p_info,FILE ** p_stream)74 static psa_status_t psa_its_read_file(psa_storage_uid_t uid,
75 struct psa_storage_info_t *p_info,
76 FILE **p_stream)
77 {
78 char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
79 psa_its_file_header_t header;
80 size_t n;
81
82 *p_stream = NULL;
83 psa_its_fill_filename(uid, filename);
84 *p_stream = fopen(filename, "rb");
85 if (*p_stream == NULL) {
86 return PSA_ERROR_DOES_NOT_EXIST;
87 }
88
89 /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
90 mbedtls_setbuf(*p_stream, NULL);
91
92 n = fread(&header, 1, sizeof(header), *p_stream);
93 if (n != sizeof(header)) {
94 return PSA_ERROR_DATA_CORRUPT;
95 }
96 if (memcmp(header.magic, PSA_ITS_MAGIC_STRING,
97 PSA_ITS_MAGIC_LENGTH) != 0) {
98 return PSA_ERROR_DATA_CORRUPT;
99 }
100
101 p_info->size = MBEDTLS_GET_UINT32_LE(header.size, 0);
102 p_info->flags = MBEDTLS_GET_UINT32_LE(header.flags, 0);
103
104 return PSA_SUCCESS;
105 }
106
psa_its_get_info(psa_storage_uid_t uid,struct psa_storage_info_t * p_info)107 psa_status_t psa_its_get_info(psa_storage_uid_t uid,
108 struct psa_storage_info_t *p_info)
109 {
110 psa_status_t status;
111 FILE *stream = NULL;
112 status = psa_its_read_file(uid, p_info, &stream);
113 if (stream != NULL) {
114 fclose(stream);
115 }
116 return status;
117 }
118
psa_its_get(psa_storage_uid_t uid,uint32_t data_offset,uint32_t data_length,void * p_data,size_t * p_data_length)119 psa_status_t psa_its_get(psa_storage_uid_t uid,
120 uint32_t data_offset,
121 uint32_t data_length,
122 void *p_data,
123 size_t *p_data_length)
124 {
125 psa_status_t status;
126 FILE *stream = NULL;
127 size_t n;
128 struct psa_storage_info_t info;
129
130 status = psa_its_read_file(uid, &info, &stream);
131 if (status != PSA_SUCCESS) {
132 goto exit;
133 }
134 status = PSA_ERROR_INVALID_ARGUMENT;
135 if (data_offset + data_length < data_offset) {
136 goto exit;
137 }
138 #if SIZE_MAX < 0xffffffff
139 if (data_offset + data_length > SIZE_MAX) {
140 goto exit;
141 }
142 #endif
143 if (data_offset + data_length > info.size) {
144 goto exit;
145 }
146
147 status = PSA_ERROR_STORAGE_FAILURE;
148 #if LONG_MAX < 0xffffffff
149 while (data_offset > LONG_MAX) {
150 if (fseek(stream, LONG_MAX, SEEK_CUR) != 0) {
151 goto exit;
152 }
153 data_offset -= LONG_MAX;
154 }
155 #endif
156 if (fseek(stream, data_offset, SEEK_CUR) != 0) {
157 goto exit;
158 }
159 n = fread(p_data, 1, data_length, stream);
160 if (n != data_length) {
161 goto exit;
162 }
163 status = PSA_SUCCESS;
164 if (p_data_length != NULL) {
165 *p_data_length = n;
166 }
167
168 exit:
169 if (stream != NULL) {
170 fclose(stream);
171 }
172 return status;
173 }
174
psa_its_set(psa_storage_uid_t uid,uint32_t data_length,const void * p_data,psa_storage_create_flags_t create_flags)175 psa_status_t psa_its_set(psa_storage_uid_t uid,
176 uint32_t data_length,
177 const void *p_data,
178 psa_storage_create_flags_t create_flags)
179 {
180 if (uid == 0) {
181 return PSA_ERROR_INVALID_HANDLE;
182 }
183
184 psa_status_t status = PSA_ERROR_STORAGE_FAILURE;
185 char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
186 FILE *stream = NULL;
187 psa_its_file_header_t header;
188 size_t n;
189
190 memcpy(header.magic, PSA_ITS_MAGIC_STRING, PSA_ITS_MAGIC_LENGTH);
191 MBEDTLS_PUT_UINT32_LE(data_length, header.size, 0);
192 MBEDTLS_PUT_UINT32_LE(create_flags, header.flags, 0);
193
194 psa_its_fill_filename(uid, filename);
195 stream = fopen(PSA_ITS_STORAGE_TEMP, "wb");
196
197 if (stream == NULL) {
198 goto exit;
199 }
200
201 /* Ensure no stdio buffering of secrets, as such buffers cannot be wiped. */
202 mbedtls_setbuf(stream, NULL);
203
204 status = PSA_ERROR_INSUFFICIENT_STORAGE;
205 n = fwrite(&header, 1, sizeof(header), stream);
206 if (n != sizeof(header)) {
207 goto exit;
208 }
209 if (data_length != 0) {
210 n = fwrite(p_data, 1, data_length, stream);
211 if (n != data_length) {
212 goto exit;
213 }
214 }
215 status = PSA_SUCCESS;
216
217 exit:
218 if (stream != NULL) {
219 int ret = fclose(stream);
220 if (status == PSA_SUCCESS && ret != 0) {
221 status = PSA_ERROR_INSUFFICIENT_STORAGE;
222 }
223 }
224 if (status == PSA_SUCCESS) {
225 if (rename_replace_existing(PSA_ITS_STORAGE_TEMP, filename) != 0) {
226 status = PSA_ERROR_STORAGE_FAILURE;
227 }
228 }
229 /* The temporary file may still exist, but only in failure cases where
230 * we're already reporting an error. So there's nothing we can do on
231 * failure. If the function succeeded, and in some error cases, the
232 * temporary file doesn't exist and so remove() is expected to fail.
233 * Thus we just ignore the return status of remove(). */
234 (void) remove(PSA_ITS_STORAGE_TEMP);
235 return status;
236 }
237
psa_its_remove(psa_storage_uid_t uid)238 psa_status_t psa_its_remove(psa_storage_uid_t uid)
239 {
240 char filename[PSA_ITS_STORAGE_FILENAME_LENGTH];
241 FILE *stream;
242 psa_its_fill_filename(uid, filename);
243 stream = fopen(filename, "rb");
244 if (stream == NULL) {
245 return PSA_ERROR_DOES_NOT_EXIST;
246 }
247 fclose(stream);
248 if (remove(filename) != 0) {
249 return PSA_ERROR_STORAGE_FAILURE;
250 }
251 return PSA_SUCCESS;
252 }
253
254 #endif /* MBEDTLS_PSA_ITS_FILE_C */
255
