From 20c21f314fb6a6e049109e1245168957e4cf710a Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sun, 31 Jan 2021 15:40:25 +0100 Subject: Check password MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- asroot.c | 358 ++++++++++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 285 insertions(+), 73 deletions(-) (limited to 'asroot.c') diff --git a/asroot.c b/asroot.c index 5f03b42..13e2904 100644 --- a/asroot.c +++ b/asroot.c @@ -1,13 +1,33 @@ #include +#include #include +#include #include #include #include +#include #include +#ifdef WITH_LIBPASSPHRASE +# include +#endif + #include "arg.h" +#define EXIT_ERROR 125 +#define EXIT_EXEC 126 +#define EXIT_NOENT 127 + +#ifndef ERROR_SLEEP +# define ERROR_SLEEP 1 +#endif + +#ifndef PROMPT +# define PROMPT "%s (%s@%s) password: ", argv0, pwd->pw_name, hostname +#endif + + char *argv0; extern char **environ; @@ -74,7 +94,264 @@ static void usage(void) { fprintf(stderr, "usage: %s [-e] command [argument] ...\n", argv0); - exit(125); + exit(EXIT_ERROR); +} + + +static char ** +set_environ(void) +{ + char **new_environ; + size_t i, j, n, len; + struct passwd *pw; + + new_environ = calloc(sizeof(env_whitelist) / sizeof(*env_whitelist) + 5, sizeof(*env_whitelist)); + if (!new_environ) { + fprintf(stderr, "%s: calloc %zu %zu: %s\n", + argv0, sizeof(env_whitelist) / sizeof(*env_whitelist) + 5, sizeof(*env_whitelist), strerror(errno)); + exit(errno == ENOENT ? 127 : 126); + } + for (i = 0, n = 0; env_whitelist[i]; i++) { + len = strlen(env_whitelist[i]); + for (j = 0; environ[j]; j++) { + if (!strncmp(environ[j], env_whitelist[i], len)) { + new_environ[n++] = environ[j]; + break; + } + } + } + + errno = 0; + pw = getpwuid(0); + if (!pw) { + if (errno) + fprintf(stderr, "%s: getpwuid 0: %s\n", argv0, strerror(errno)); + else + fprintf(stderr, "%s: cannot find root user\n", argv0); + exit(EXIT_ERROR); + } + + if (pw->pw_dir && *pw->pw_dir) { + len = strlen(pw->pw_dir); + len += sizeof("HOME="); + new_environ[n] = malloc(len); + if (!new_environ[n]) + fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); + stpcpy(stpcpy(new_environ[n++], "HOME="), pw->pw_dir); + } + if (pw->pw_name && *pw->pw_name) { + len = strlen(pw->pw_name); + len += sizeof("LOGNAME="); + new_environ[n] = malloc(len); + if (!new_environ[n]) + fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); + stpcpy(stpcpy(new_environ[n++], "LOGNAME="), pw->pw_name); + + len -= sizeof("LOGNAME="); + len += sizeof("USER="); + new_environ[n] = malloc(len); + if (!new_environ[n]) + fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); + stpcpy(stpcpy(new_environ[n++], "USER="), pw->pw_name); + + len -= sizeof("USER="); + len += sizeof("MAIL=/var/spool/mail/"); + new_environ[n] = malloc(len); + if (!new_environ[n]) + fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); + stpcpy(stpcpy(new_environ[n++], "MAIL=/var/spool/mail/"), pw->pw_name); + } + if (pw->pw_shell && *pw->pw_shell) { + len = strlen(pw->pw_dir); + len += sizeof("SHELL="); + new_environ[n] = malloc(len); + if (!new_environ[n]) + fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); + stpcpy(stpcpy(new_environ[n++], "SHELL="), pw->pw_dir); + } + new_environ[n] = NULL; + + return new_environ; +} + + +#ifndef WITH_LIBPASSPHRASE +static char * +read_passphrase(int fd) +{ + char *passphrase = NULL, *new; + size_t size = 0, len = 0; + ssize_t r; + + for (;;) { + if (len == size) { + new = realloc(passphrase, size += 32); + if (!new) { + fprintf(stderr, "\n%s: realloc %zu: %s\n", argv0, size, strerror(errno)); + if (passphrase) { + memset(passphrase, 0, len); + free(passphrase); + } + return NULL; + } + passphrase = new; + } + r = read(fd, &passphrase[len], 1); + if (r < 0) { + fprintf(stderr, "\n%s: read /dev/tty 1: %s\n", argv0, strerror(errno)); + memset(passphrase, 0, len); + free(passphrase); + return NULL; + } else if (!r || passphrase[len] == '\n') { + break; + } else { + len += 1; + } + } + + fprintf(stderr, "\n"); + passphrase[len] = 0; + return passphrase; +} +#endif + + +static void +check_password(void) +{ + struct passwd *pwd; + struct spwd *shdw; + const char *expected, *got; + char *hostname = NULL; + char *passphrase; + size_t size = 8; +#ifndef WITH_LIBPASSPHRASE + struct termios stty_original; +#endif + struct termios stty_enter, stty_sleep; + int fd; + + errno = 0; + for (;;) { + hostname = realloc(hostname, size *= 2); + if (!hostname) { + fprintf(stderr, "%s: realloc %zu: %s\n", argv0, size, strerror(errno)); + } + *hostname = 0; + if (!gethostname(hostname, size)) { + break; + } else if (errno != ENAMETOOLONG) { + fprintf(stderr, "%s: gethostname %zu: %s\n", argv0, size, strerror(errno)); + exit(EXIT_ERROR); + } + } + + errno = 0; + pwd = getpwuid(getuid()); + if (!pwd || !pwd->pw_name || !*pwd->pw_name) { + if (errno) + fprintf(stderr, "%s: getpwuid: %s\n", argv0, strerror(errno)); + else + fprintf(stderr, "%s: your user does not exist\n", argv0); + exit(EXIT_ERROR); + } + + shdw = getspnam(pwd->pw_name); + if (!shdw || !shdw->sp_pwdp) { + if (errno) + fprintf(stderr, "%s: getspnam: %s\n", argv0, strerror(errno)); + else + fprintf(stderr, "%s: your user does not have a shadow entry\n", argv0); + exit(EXIT_ERROR); + } + + expected = shdw->sp_pwdp; + + if (!*expected) { + fprintf(stderr, "%s: your user does not have a password\n", argv0); + exit(EXIT_ERROR); + } else if (expected[expected[0] == '!'] == '*' || expected[expected[0] == '!'] == 'x') { + fprintf(stderr, "%s: login to your account is disabled\n", argv0); + exit(EXIT_ERROR); + } else if (expected[0] == '!') { + fprintf(stderr, "%s: your account is currently locked\n", argv0); + exit(EXIT_ERROR); + } + + fd = open("/dev/tty", O_RDWR); + if (fd < 0) { + fprintf(stderr, "%s: open /dev/tty O_RDWR: %s\n", argv0, strerror(errno)); + exit(EXIT_ERROR); + } + +#ifdef WITH_LIBPASSPHRASE + passphrase_disable_echo1(fd); + + memset(&stty_enter, 0, sizeof(stty_enter)); + if (tcgetattr(fd, &stty_enter)) { + fprintf(stderr, "%s: tcgetattr /dev/tty: %s\n", argv0, strerror(errno)); + passphrase_reenable_echo1(fd); + close(fd); + exit(EXIT_ERROR); + } +#else + memset(&stty_original, 0, sizeof(stty_original)); + if (tcgetattr(fd, &stty_original)) { + fprintf(stderr, "%s: tcgetattr /dev/tty: %s\n", argv0, strerror(errno)); + close(fd); + exit(EXIT_ERROR); + } + memcpy(&stty_enter, &stty_original, sizeof(stty_original)); + stty_enter.c_lflag &= (tcflag_t)~ECHO; + tcsetattr(fd, TCSAFLUSH, &stty_enter); +#endif + + memcpy(&stty_sleep, &stty_enter, sizeof(stty_enter)); + stty_sleep.c_lflag = 0; + +again: + fprintf(stderr, PROMPT); + fflush(stderr); + +#ifdef WITH_LIBPASSPHRASE + passphrase = passphrase_read2(fd, PASSPHRASE_READ_EXISTING); + if (!passphrase) { + fprintf(stderr, "%s: passphrase_read2 /dev/tty PASSPHRASE_READ_EXISTING: %s\n", argv0, strerror(errno)); + passphrase_reenable_echo1(fd); + close(fd); + exit(EXIT_ERROR); + } +#else + passphrase = read_passphrase(fd); + if (!passphrase) { + tcsetattr(fd, TCSAFLUSH, &stty_original); + close(fd); + exit(EXIT_ERROR); + } +#endif + + got = crypt(passphrase, expected); +#ifdef WITH_LIBPASSPHRASE + passphrase_wipe1(passphrase); +#else + memset(passphrase, 0, strlen(passphrase)); +#endif + free(passphrase); + + if (strcmp(got, expected)) { + fprintf(stderr, "%s: incorrect password, please try again\n", argv0); + tcsetattr(fd, TCSAFLUSH, &stty_sleep); + sleep(ERROR_SLEEP); + tcsetattr(fd, TCSAFLUSH, &stty_enter); + goto again; + } + +#ifdef WITH_LIBPASSPHRASE + passphrase_reenable_echo1(fd); +#else + tcsetattr(fd, TCSAFLUSH, &stty_original); +#endif + close(fd); } @@ -83,8 +360,6 @@ main(int argc, char *argv[]) { int keep_env = 0; char **new_environ = NULL; - size_t i, j, n, len; - struct passwd *pw; ARGBEGIN { case 'e': @@ -97,84 +372,21 @@ main(int argc, char *argv[]) if (!argc) usage(); - /* TODO check password */ + check_password(); + + if (!keep_env) + new_environ = set_environ(); if (setgid(0)) { fprintf(stderr, "%s: setgid 0: %s\n", argv0, strerror(errno)); - return 125; + exit(EXIT_ERROR); } if (setuid(0)) { fprintf(stderr, "%s: setuid 0: %s\n", argv0, strerror(errno)); - return 125; - } - - if (!keep_env) { - new_environ = calloc(sizeof(env_whitelist) / sizeof(*env_whitelist) + 5, sizeof(*env_whitelist)); - if (!new_environ) { - fprintf(stderr, "%s: calloc %zu %zu: %s\n", - argv0, sizeof(env_whitelist) / sizeof(*env_whitelist) + 5, sizeof(*env_whitelist), strerror(errno)); - return errno == ENOENT ? 127 : 126; - } - for (i = 0, n = 0; env_whitelist[i]; i++) { - len = strlen(env_whitelist[i]); - for (j = 0; environ[j]; j++) { - if (!strncmp(environ[j], env_whitelist[i], len)) { - new_environ[n++] = environ[j]; - break; - } - } - } - errno = 0; - pw = getpwuid(0); - if (!pw) { - if (errno) - fprintf(stderr, "%s: getpwuid 0: %s\n", argv0, strerror(errno)); - else - fprintf(stderr, "%s: cannot find root user\n", argv0); - exit(125); - } - if (pw->pw_dir && *pw->pw_dir) { - len = strlen(pw->pw_dir); - len += sizeof("HOME="); - new_environ[n] = malloc(len); - if (!new_environ[n]) - fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); - stpcpy(stpcpy(new_environ[n++], "HOME="), pw->pw_dir); - } - if (pw->pw_name && *pw->pw_name) { - len = strlen(pw->pw_name); - len += sizeof("LOGNAME="); - new_environ[n] = malloc(len); - if (!new_environ[n]) - fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); - stpcpy(stpcpy(new_environ[n++], "LOGNAME="), pw->pw_name); - - len -= sizeof("LOGNAME="); - len += sizeof("USER="); - new_environ[n] = malloc(len); - if (!new_environ[n]) - fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); - stpcpy(stpcpy(new_environ[n++], "USER="), pw->pw_name); - - len -= sizeof("USER="); - len += sizeof("MAIL=/var/spool/mail/"); - new_environ[n] = malloc(len); - if (!new_environ[n]) - fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); - stpcpy(stpcpy(new_environ[n++], "MAIL=/var/spool/mail/"), pw->pw_name); - } - if (pw->pw_shell && *pw->pw_shell) { - len = strlen(pw->pw_dir); - len += sizeof("SHELL="); - new_environ[n] = malloc(len); - if (!new_environ[n]) - fprintf(stderr, "%s: malloc %zu: %s\n", argv0, len, strerror(errno)); - stpcpy(stpcpy(new_environ[n++], "SHELL="), pw->pw_dir); - } - new_environ[n] = NULL; + exit(EXIT_ERROR); } execvpe(argv[0], argv, new_environ ? new_environ : environ); fprintf(stderr, "%s: execvpe %s: %s\n", argv0, argv[0], strerror(errno)); - return errno == ENOENT ? 127 : 126; + return errno == ENOENT ? EXIT_NOENT : EXIT_EXEC; } -- cgit v1.2.3-70-g09d2