1 /*
2  * Zeroize application for debugger-driven testing
3  *
4  * This is a simple test application used for debugger-driven testing to check
5  * whether calls to mbedtls_platform_zeroize() are being eliminated by compiler
6  * optimizations. This application is used by the GDB script at
7  * tests/scripts/test_zeroize.gdb: the script sets a breakpoint at the last
8  * return statement in the main() function of this program. The debugger
9  * facilities are then used to manually inspect the memory and verify that the
10  * call to mbedtls_platform_zeroize() was not eliminated.
11  *
12  *  Copyright The Mbed TLS Contributors
13  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
14  */
15 
16 #include "mbedtls/build_info.h"
17 
18 #include <stdio.h>
19 
20 #include "mbedtls/platform.h"
21 
22 #include "mbedtls/platform_util.h"
23 
24 #define BUFFER_LEN 1024
25 
usage(void)26 void usage(void)
27 {
28     mbedtls_printf("Zeroize is a simple program to assist with testing\n");
29     mbedtls_printf("the mbedtls_platform_zeroize() function by using the\n");
30     mbedtls_printf("debugger. This program takes a file as input and\n");
31     mbedtls_printf("prints the first %d characters. Usage:\n\n", BUFFER_LEN);
32     mbedtls_printf("       zeroize <FILE>\n");
33 }
34 
main(int argc,char ** argv)35 int main(int argc, char **argv)
36 {
37     int exit_code = MBEDTLS_EXIT_FAILURE;
38     FILE *fp;
39     char buf[BUFFER_LEN];
40     char *p = buf;
41     char *end = p + BUFFER_LEN;
42     int c;
43 
44     if (argc != 2) {
45         mbedtls_printf("This program takes exactly 1 argument\n");
46         usage();
47         mbedtls_exit(exit_code);
48     }
49 
50     fp = fopen(argv[1], "r");
51     if (fp == NULL) {
52         mbedtls_printf("Could not open file '%s'\n", argv[1]);
53         mbedtls_exit(exit_code);
54     }
55 
56     while ((c = fgetc(fp)) != EOF && p < end - 1) {
57         *p++ = (char) c;
58     }
59     *p = '\0';
60 
61     if (p - buf != 0) {
62         mbedtls_printf("%s\n", buf);
63         exit_code = MBEDTLS_EXIT_SUCCESS;
64     } else {
65         mbedtls_printf("The file is empty!\n");
66     }
67 
68     fclose(fp);
69     mbedtls_platform_zeroize(buf, sizeof(buf));
70 
71     mbedtls_exit(exit_code);   // GDB_BREAK_HERE -- don't remove this comment!
72 }
73