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* Password-prompt - Read a password from the terminal and print it
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* Copyright © 2008-2017 Teddy Hogeborn
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* Copyright © 2008-2017 Björn Påhlsson
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* Copyright © 2008,2009 Teddy Hogeborn
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* Copyright © 2008,2009 Björn Påhlsson
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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* Contact the authors at <mandos@recompile.se>.
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* Contact the authors at <mandos@fukt.bsnet.se>.
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#define _GNU_SOURCE /* getline(), asprintf() */
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#define _GNU_SOURCE /* getline() */
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#include <termios.h> /* struct termios, tcsetattr(),
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#include <termios.h> /* struct termios, tcsetattr(),
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TCSAFLUSH, tcgetattr(), ECHO */
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#include <unistd.h> /* struct termios, tcsetattr(),
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STDIN_FILENO, TCSAFLUSH,
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tcgetattr(), ECHO, readlink() */
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#include <signal.h> /* sig_atomic_t, raise(), struct
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sigaction, sigemptyset(),
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sigaction(), sigaddset(), SIGINT,
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SIGQUIT, SIGHUP, SIGTERM,
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#include <stddef.h> /* NULL, size_t, ssize_t */
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#include <sys/types.h> /* ssize_t, struct dirent, pid_t,
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#include <sys/types.h> /* ssize_t */
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#include <stdlib.h> /* EXIT_SUCCESS, EXIT_FAILURE,
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#include <dirent.h> /* scandir(), alphasort() */
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#include <stdio.h> /* fprintf(), stderr, getline(),
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stdin, feof(), fputc(), vfprintf(),
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stdin, feof(), fputc()
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#include <errno.h> /* errno, EBADF, ENOTTY, EINVAL,
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EFAULT, EFBIG, EIO, ENOSPC, EINTR
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#include <error.h> /* error() */
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#include <iso646.h> /* or, not */
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#include <stdbool.h> /* bool, false, true */
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#include <inttypes.h> /* strtoumax() */
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#include <sys/stat.h> /* struct stat, lstat(), open() */
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#include <string.h> /* strlen, rindex, memcmp, strerror()
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#include <string.h> /* strlen, rindex */
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#include <argp.h> /* struct argp_option, struct
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argp_state, struct argp,
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argp_parse(), error_t,
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ARGP_ERR_UNKNOWN */
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#include <sysexits.h> /* EX_SOFTWARE, EX_OSERR,
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EX_UNAVAILABLE, EX_IOERR, EX_OK */
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#include <fcntl.h> /* open() */
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#include <stdarg.h> /* va_list, va_start(), ... */
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volatile sig_atomic_t quit_now = 0;
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int signal_received;
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bool debug = false;
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const char *argp_program_version = "password-prompt " VERSION;
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const char *argp_program_bug_address = "<mandos@recompile.se>";
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/* Needed for conflict resolution */
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const char plymouth_name[] = "plymouthd";
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/* Function to use when printing errors */
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__attribute__((format (gnu_printf, 3, 4)))
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void error_plus(int status, int errnum, const char *formatstring,
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va_start(ap, formatstring);
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ret = vasprintf(&text, formatstring, ap);
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fprintf(stderr, "Mandos plugin %s: ",
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program_invocation_short_name);
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vfprintf(stderr, formatstring, ap);
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fprintf(stderr, ": %s\n", strerror(errnum));
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error(status, errno, "vasprintf while printing error");
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fprintf(stderr, "Mandos plugin ");
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error(status, errnum, "%s", text);
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const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";
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static void termination_handler(int signum){
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signal_received = signum;
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bool conflict_detection(void){
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/* plymouth conflicts with password-prompt since both want to read
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from the terminal. Password-prompt will exit if it detects
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plymouth since plymouth performs the same functionality.
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__attribute__((nonnull))
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int is_plymouth(const struct dirent *proc_entry){
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proc_id = strtoumax(proc_entry->d_name, &tmp, 10);
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if(errno != 0 or *tmp != '\0'
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or proc_id != (uintmax_t)((pid_t)proc_id)){
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char *cmdline_filename;
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ret = asprintf(&cmdline_filename, "/proc/%s/cmdline",
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error_plus(0, errno, "asprintf");
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/* Open /proc/<pid>/cmdline */
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cl_fd = open(cmdline_filename, O_RDONLY);
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free(cmdline_filename);
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error_plus(0, errno, "open");
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char *cmdline = NULL;
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size_t cmdline_len = 0;
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size_t cmdline_allocated = 0;
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const size_t blocksize = 1024;
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/* Allocate more space? */
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if(cmdline_len + blocksize + 1 > cmdline_allocated){
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tmp = realloc(cmdline, cmdline_allocated + blocksize + 1);
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error_plus(0, errno, "realloc");
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cmdline_allocated += blocksize;
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sret = read(cl_fd, cmdline + cmdline_len,
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cmdline_allocated - cmdline_len);
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error_plus(0, errno, "read");
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cmdline_len += (size_t)sret;
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error_plus(0, errno, "close");
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cmdline[cmdline_len] = '\0'; /* Make sure it is terminated */
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/* we now have cmdline */
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char *cmdline_base = strrchr(cmdline, '/');
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if(cmdline_base != NULL){
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cmdline_base += 1; /* skip the slash */
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cmdline_base = cmdline;
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if(strcmp(cmdline_base, plymouth_name) != 0){
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fprintf(stderr, "\"%s\" is not \"%s\"\n", cmdline_base,
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fprintf(stderr, "\"%s\" equals \"%s\"\n", cmdline_base,
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struct dirent **direntries = NULL;
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ret = scandir("/proc", &direntries, is_plymouth, alphasort);
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error_plus(1, errno, "scandir");
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int main(int argc, char **argv){
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fprintf(stderr, "Starting %s\n", argv[0]);
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if(conflict_detection()){
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fprintf(stderr, "Stopping %s because of conflict\n", argv[0]);
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fprintf(stderr, "Storing current terminal attributes\n");
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if(tcgetattr(STDIN_FILENO, &t_old) != 0){
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error_plus(0, errno, "tcgetattr");
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error(0, errno, "tcgetattr");
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sigemptyset(&new_action.sa_mask);
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ret = sigaddset(&new_action.sa_mask, SIGINT);
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error_plus(0, errno, "sigaddset");
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error(0, errno, "sigaddset");
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ret = sigaddset(&new_action.sa_mask, SIGHUP);
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error_plus(0, errno, "sigaddset");
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error(0, errno, "sigaddset");
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ret = sigaddset(&new_action.sa_mask, SIGTERM);
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error_plus(0, errno, "sigaddset");
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error(0, errno, "sigaddset");
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/* Need to check if the handler is SIG_IGN before handling:
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ret = sigaction(SIGINT, NULL, &old_action);
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error_plus(0, errno, "sigaction");
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error(0, errno, "sigaction");
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if(old_action.sa_handler != SIG_IGN){
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ret = sigaction(SIGINT, &new_action, NULL);
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error_plus(0, errno, "sigaction");
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error(0, errno, "sigaction");
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ret = sigaction(SIGHUP, NULL, &old_action);
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error_plus(0, errno, "sigaction");
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error(0, errno, "sigaction");
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if(old_action.sa_handler != SIG_IGN){
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ret = sigaction(SIGHUP, &new_action, NULL);
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error_plus(0, errno, "sigaction");
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error(0, errno, "sigaction");
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ret = sigaction(SIGTERM, NULL, &old_action);
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error_plus(0, errno, "sigaction");
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error(0, errno, "sigaction");
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if(old_action.sa_handler != SIG_IGN){
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ret = sigaction(SIGTERM, &new_action, NULL);
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error_plus(0, errno, "sigaction");
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error(0, errno, "sigaction");