From 49200cf2e80f7d23d2a2717130486316a9e12698 Mon Sep 17 00:00:00 2001 From: Christian Hesse Date: Wed, 4 May 2016 15:37:53 +0200 Subject: support reading second factor from terminal This increases security by not displaying on display and not writing to shell history. --- bin/ykfde.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 70 insertions(+), 17 deletions(-) (limited to 'bin') diff --git a/bin/ykfde.c b/bin/ykfde.c index 402ecb7..198a842 100644 --- a/bin/ykfde.c +++ b/bin/ykfde.c @@ -15,6 +15,8 @@ #include #include #include +#include +#include #include @@ -45,12 +47,14 @@ #define PASSPHRASELEN SHA1_DIGEST_SIZE * 2 #define MAX2FLEN CHALLENGELEN / 2 -const static char optstring[] = "hn:s:V"; +const static char optstring[] = "hn:Ns:SV"; const static struct option options_long[] = { /* name has_arg flag val */ { "help", no_argument, NULL, 'h' }, { "2nd-factor", required_argument, NULL, 's' }, + { "ask-2nd-factor", no_argument, NULL, 'S' }, { "new-2nd-factor", required_argument, NULL, 'n' }, + { "ask-new-2nd-factor", no_argument, NULL, 'N' }, { "version", no_argument, NULL, 'V' }, { 0, 0, 0, 0 } }; @@ -68,7 +72,11 @@ int main(int argc, char **argv) { challengefiletmpname[sizeof(CHALLENGEDIR) + 11 /* "/challenge-" */ + 10 /* unsigned int in char */ + 7 /* -XXXXXX */ + 1]; int challengefile = 0, challengefiletmp = 0; struct timeval tv; + struct termios tp, tp_save; + uint8_t have_term = 1; int i; + size_t len; + ssize_t readlen; int8_t rc = EXIT_FAILURE; /* cryptsetup */ const char * device_name; @@ -79,8 +87,7 @@ int main(int argc, char **argv) { /* keyutils */ key_serial_t key; void * payload = NULL; - char * new_2nd_factor = NULL; - size_t plen = 0; + char * second_factor = NULL, * new_2nd_factor = NULL; /* yubikey */ YK_KEY * yk; uint8_t yk_slot = SLOT_CHAL_HMAC2; @@ -90,6 +97,20 @@ int main(int argc, char **argv) { char section_ykslot[10 /* unsigned int in char */ + 1 + sizeof(CONFYKSLOT) + 1]; char section_luksslot[10 + 1 + sizeof(CONFLUKSSLOT) + 1]; + /* get terminal properties */ + if (tcgetattr(STDIN_FILENO, &tp) < 0) + have_term = 0; + tp_save = tp; + + /* disable echo on terminal */ + tp.c_lflag &= ~ECHO; + if (have_term) + if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &tp) < 0) { + fprintf(stderr, "Failed setting terminal attributes.\n"); + rc = EXIT_FAILURE; + goto out0; + } + /* get command line options */ while ((i = getopt_long(argc, argv, optstring, options_long, NULL)) != -1) switch (i) { @@ -97,30 +118,60 @@ int main(int argc, char **argv) { help++; break; case 'n': + case 'N': if (new_2nd_factor != NULL) { fprintf(stderr, "We already have a new second factor. Did you specify it twice?\n"); rc = EXIT_FAILURE; goto out10; } - new_2nd_factor = strdup(optarg); - memset(optarg, '*', strlen(optarg)); + if (optarg == NULL) { /* N */ + if (have_term == 0) + fprintf(stderr, "Warning: Could not disable echo, input will be visible!\n"); + printf("Please give new second factor:"); + readlen = getline(&new_2nd_factor, &len, stdin); + new_2nd_factor[readlen - 1] = '\0'; + putchar('\n'); + } else { /* n */ + new_2nd_factor = strdup(optarg); + memset(optarg, '*', strlen(optarg)); + } + break; case 's': - if (payload != NULL) { + case 'S': + if (second_factor != NULL) { fprintf(stderr, "We already have a second factor. Did you specify it twice?\n"); rc = EXIT_FAILURE; goto out10; } - payload = strdup(optarg); - memset(optarg, '*', strlen(optarg)); + if (optarg == NULL) { /* S */ + if (have_term == 0) + fprintf(stderr, "Warning: Could not disable echo, input will be visible!\n"); + printf("Please give second factor:"); + readlen = getline(&second_factor, &len, stdin); + second_factor[readlen - 1] = '\0'; + putchar('\n'); + } else { /* s */ + second_factor = strdup(optarg); + memset(optarg, '*', strlen(optarg)); + } + break; case 'V': version++; break; } + /* restore terminal */ + if (have_term) + if (tcsetattr(STDIN_FILENO, TCSANOW, &tp_save) < 0) { + fprintf(stderr, "Failed setting terminal attributes.\n"); + rc = EXIT_FAILURE; + goto out10; + } + if (version > 0) printf("%s: %s v%s (compiled: " __DATE__ ", " __TIME__ ")\n", argv[0], PROGNAME, VERSION); @@ -204,7 +255,7 @@ int main(int argc, char **argv) { goto out40; } - if (payload == NULL) { + if (second_factor == NULL) { /* get second factor from key store */ if ((key = request_key("user", "ykfde-2f", NULL, 0)) < 0) fprintf(stderr, "Failed requesting key. That's ok if you do not use\n" @@ -216,12 +267,13 @@ int main(int argc, char **argv) { perror("Failed reading payload from key"); goto out40; } + second_factor = payload; } else - payload = strdup(""); + second_factor = strdup(""); } /* warn when second factor is not enabled in config */ - if ((*(char*)payload != 0 || new_2nd_factor != NULL) && + if ((*second_factor != 0 || new_2nd_factor != NULL) && iniparser_getboolean(ini, "general:" CONF2NDFACTOR, 0) == 0) fprintf(stderr, "Warning: Processing second factor, but not enabled in config!\n"); @@ -247,9 +299,9 @@ int main(int argc, char **argv) { /* now that the new challenge has been written to file... * add second factor to new challenge */ - tmp = new_2nd_factor ? new_2nd_factor : payload; - plen = strlen(tmp); - memcpy(challenge_new, tmp, plen < MAX2FLEN ? plen : MAX2FLEN); + tmp = new_2nd_factor ? new_2nd_factor : second_factor; + len = strlen(tmp); + memcpy(challenge_new, tmp, len < MAX2FLEN ? len : MAX2FLEN); /* do challenge/response and encode to hex */ if (yk_challenge_response(yk, yk_slot, true, @@ -298,8 +350,8 @@ int main(int argc, char **argv) { /* finished reading challenge */ /* copy the second factor */ - plen = strlen(payload); - memcpy(challenge_old, payload, plen < MAX2FLEN ? plen : MAX2FLEN); + len = strlen(second_factor); + memcpy(challenge_old, second_factor, len < MAX2FLEN ? len : MAX2FLEN); /* do challenge/response and encode to hex */ if (yk_challenge_response(yk, yk_slot, true, @@ -375,8 +427,9 @@ out10: memset(passphrase_new, 0, PASSPHRASELEN + 1); free(new_2nd_factor); - free(payload); + free(second_factor); +out0: return rc; } -- cgit v1.2.3-70-g09d2