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/* -*- coding: utf-8 -*- */
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* Usplash - Read a password from usplash and output it
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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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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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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 <https://www.fukt.bsnet.se/~belorn/> and
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* <https://www.fukt.bsnet.se/~teddy/>.
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#define _GNU_SOURCE /* asprintf() */
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#include <signal.h> /* sig_atomic_t, struct sigaction,
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sigemptyset(), sigaddset(), SIGINT,
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SIG_IGN, kill(), SIGKILL */
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#include <stdbool.h> /* bool, false, true */
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#include <fcntl.h> /* open(), O_WRONLY, O_RDONLY */
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#include <iso646.h> /* and, or, not*/
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#include <errno.h> /* errno, EINTR */
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#include <sys/types.h> /* size_t, ssize_t, pid_t, DIR, struct
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#include <sys/types.h> /* size_t, ssize_t, pid_t, DIR,
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#include <stddef.h> /* NULL */
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#include <string.h> /* strlen(), memcmp() */
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#include <stdio.h> /* asprintf(), perror() */
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fork(), setuid(), geteuid(),
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setsid(), chdir(), dup2(),
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STDERR_FILENO, execv() */
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#include <stdlib.h> /* free(), EXIT_FAILURE, realloc(),
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EXIT_SUCCESS, malloc(), _exit() */
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#include <stdlib.h> /* free(), EXIT_FAILURE, strtoul(),
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realloc(), EXIT_SUCCESS, malloc(),
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#include <stdlib.h> /* getenv() */
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#include <dirent.h> /* opendir(), readdir(), closedir() */
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#include <inttypes.h> /* intmax_t, strtoimax() */
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#include <sys/stat.h> /* struct stat, lstat(), S_ISLNK */
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#include <iso646.h> /* and */
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#include <sys/wait.h> /* waitpid(), WIFEXITED(),
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sig_atomic_t interrupted_by_signal = 0;
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static bool usplash_write(const char *cmd, const char *arg){
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* usplash_write("TIMEOUT", "15") will write "TIMEOUT 15\0"
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* usplash_write("PULSATE", NULL) will write "PULSATE\0"
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* usplash_write("TIMEOUT", "15"); -> "TIMEOUT 15\0"
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* usplash_write("PULSATE", NULL); -> "PULSATE\0"
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size_t written = 0;
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while(not interrupted_by_signal and written < cmd_line_len){
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sret = write(fifo_fd, cmd_line + written,
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cmd_line_len - written);
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ret = write(fifo_fd, cmd_line + written,
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cmd_line_len - written);
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if(errno != EINTR or interrupted_by_signal){
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for(struct dirent *proc_ent = readdir(proc_dir);
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proc_ent != NULL;
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proc_ent = readdir(proc_dir)){
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tmpmax = strtoimax(proc_ent->d_name, &tmp, 10);
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if(errno != 0 or tmp == proc_ent->d_name or *tmp != '\0'
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or tmpmax != (pid_t)tmpmax){
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pid_t pid = (pid_t) strtoul(proc_ent->d_name, NULL, 10);
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/* Find the executable name by doing readlink() on the
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/proc/<pid>/exe link */
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char exe_target[sizeof(usplash_name)];
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/* create file name string */
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ret = asprintf(&exe_link, "/proc/%s/exe", proc_ent->d_name);
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closedir(proc_dir);
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return EXIT_FAILURE;
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/* Check that it refers to a symlink owned by root:root */
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struct stat exe_stat;
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ret = lstat(exe_link, &exe_stat);
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if(not S_ISLNK(exe_stat.st_mode)
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or exe_stat.st_uid != 0
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or exe_stat.st_gid != 0){
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sret = readlink(exe_link, exe_target, sizeof(exe_target));
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if((sret == ((ssize_t)sizeof(exe_target)-1))
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and (memcmp(usplash_name, exe_target,
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return EXIT_SUCCESS;
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} /* end of non-loop while() */
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/* If we got here, an error or interrupt must have happened */
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/* Create argc and argv for new usplash*/
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int cmdline_argc = 0;
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char **cmdline_argv = malloc(sizeof(char *));
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/* Create argv and argc for new usplash*/
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size_t position = 0;
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while(position < cmdline_len){
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cmdline_argv[cmdline_argc] = NULL;
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/* Kill old usplash */
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kill(usplash_pid, SIGTERM);
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kill(usplash_pid, SIGTERM);
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while(kill(usplash_pid, 0) == 0){
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kill(usplash_pid, SIGKILL);