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/* -*- coding: utf-8 -*- */
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* Splashy - Read a password from splashy and output it
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* Copyright © 2008-2018, 2021 Teddy Hogeborn
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* Copyright © 2008-2018, 2021 Björn Påhlsson
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* This file is part of Mandos.
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* Mandos is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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* Mandos 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 Mandos. If not, see <http://www.gnu.org/licenses/>.
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* Contact the authors at <mandos@recompile.se>.
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#define _GNU_SOURCE /* vasprintf(),
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program_invocation_short_name,
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asprintf(), TEMP_FAILURE_RETRY() */
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#include <sys/types.h> /* sig_atomic_t, pid_t, setuid(),
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geteuid(), setsid() */
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#include <stdarg.h> /* va_list, va_start(), vfprintf() */
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#include <stdio.h> /* vasprintf(), fprintf(), stderr,
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vfprintf(), asprintf() */
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#include <errno.h> /* program_invocation_short_name,
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errno, EACCES, ENOTDIR, ELOOP,
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ENOENT, ENAMETOOLONG, EMFILE,
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ENFILE, ENOMEM, ENOEXEC, EINVAL,
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E2BIG, EFAULT, EIO, ETXTBSY,
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EISDIR, ELIBBAD, EPERM, EINTR,
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#include <string.h> /* strerror(), memcmp() */
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#include <error.h> /* error() */
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#include <stdlib.h> /* free(), EXIT_FAILURE, getenv(),
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EXIT_SUCCESS, abort() */
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#include <stddef.h> /* NULL */
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#include <dirent.h> /* DIR, opendir(), struct dirent,
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readdir(), closedir() */
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#include <sysexits.h> /* EX_OSERR, EX_OSFILE,
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#include <inttypes.h> /* intmax_t, strtoimax() */
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#include <iso646.h> /* or, not, and */
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#include <unistd.h> /* ssize_t, readlink(), fork(),
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TEMP_FAILURE_RETRY(), sleep(),
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setuid(), geteuid(), setsid(),
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chdir(), dup2(), STDERR_FILENO,
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STDOUT_FILENO, pause() */
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#include <sys/stat.h> /* struct stat, lstat(), S_ISLNK() */
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#include <signal.h> /* struct sigaction, sigemptyset(),
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sigaddset(), SIGINT, SIGHUP,
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SIGTERM, SIG_IGN, kill(), SIGKILL,
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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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/* 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, ": ");
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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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static void termination_handler(int signum){
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if(interrupted_by_signal){
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interrupted_by_signal = 1;
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signal_received = signum;
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int main(__attribute__((unused))int argc,
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__attribute__((unused))char **argv){
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DIR *proc_dir = NULL;
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pid_t splashy_pid = 0;
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pid_t splashy_command_pid = 0;
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int exitstatus = EXIT_FAILURE;
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/* Create prompt string */
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const char *const cryptsource = getenv("cryptsource");
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const char *const crypttarget = getenv("crypttarget");
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const char *const prompt_start = "getpass "
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"Enter passphrase to unlock the disk";
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if(cryptsource == NULL){
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if(crypttarget == NULL){
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ret = asprintf(&prompt, "%s: ", prompt_start);
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ret = asprintf(&prompt, "%s (%s): ", prompt_start,
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if(crypttarget == NULL){
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ret = asprintf(&prompt, "%s %s: ", prompt_start, cryptsource);
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ret = asprintf(&prompt, "%s %s (%s): ", prompt_start,
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cryptsource, crypttarget);
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exitstatus = EX_OSERR;
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/* Find splashy process */
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const char splashy_name[] = "/sbin/splashy";
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proc_dir = opendir("/proc");
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if(proc_dir == NULL){
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error_plus(0, errno, "opendir");
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exitstatus = EX_OSFILE;
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exitstatus = EX_OSERR;
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for(struct dirent *proc_ent = readdir(proc_dir);
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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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/* 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(splashy_name)];
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ret = asprintf(&exe_link, "/proc/%s/exe", proc_ent->d_name);
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error_plus(0, errno, "asprintf");
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exitstatus = EX_OSERR;
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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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error_plus(0, errno, "lstat");
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exitstatus = EX_OSFILE;
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exitstatus = EX_OSERR;
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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(splashy_name, exe_target,
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sizeof(exe_target)-1) == 0)){
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if(splashy_pid == 0){
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exitstatus = EX_UNAVAILABLE;
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/* Set up the signal handler */
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struct sigaction old_action,
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new_action = { .sa_handler = termination_handler,
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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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exitstatus = EX_OSERR;
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ret = sigaddset(&new_action.sa_mask, SIGHUP);
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error_plus(0, errno, "sigaddset");
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exitstatus = EX_OSERR;
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ret = sigaddset(&new_action.sa_mask, SIGTERM);
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error_plus(0, errno, "sigaddset");
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exitstatus = EX_OSERR;
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ret = sigaction(SIGINT, NULL, &old_action);
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error_plus(0, errno, "sigaction");
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exitstatus = EX_OSERR;
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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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exitstatus = EX_OSERR;
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ret = sigaction(SIGHUP, NULL, &old_action);
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error_plus(0, errno, "sigaction");
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exitstatus = EX_OSERR;
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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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exitstatus = EX_OSERR;
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ret = sigaction(SIGTERM, NULL, &old_action);
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error_plus(0, errno, "sigaction");
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exitstatus = EX_OSERR;
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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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exitstatus = EX_OSERR;
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if(interrupted_by_signal){
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/* Fork off the splashy command to prompt for password */
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splashy_command_pid = fork();
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if(splashy_command_pid != 0 and interrupted_by_signal){
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if(splashy_command_pid == -1){
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error_plus(0, errno, "fork");
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exitstatus = EX_OSERR;
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if(splashy_command_pid == 0){
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if(not interrupted_by_signal){
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const char splashy_command[] = "/sbin/splashy_update";
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execl(splashy_command, splashy_command, prompt, (char *)NULL);
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error_plus(0, errno, "execl");
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_exit(EX_UNAVAILABLE);
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case ELIBBAD: /* Linux only */
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if(interrupted_by_signal){
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/* Wait for command to complete */
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ret = waitpid(splashy_command_pid, &status, 0);
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} while(ret == -1 and errno == EINTR
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and not interrupted_by_signal);
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if(interrupted_by_signal){
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error_plus(0, errno, "waitpid");
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splashy_command_pid = 0;
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/* The child process has exited */
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splashy_command_pid = 0;
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if(WIFEXITED(status) and WEXITSTATUS(status) == 0){
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if(proc_dir != NULL){
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TEMP_FAILURE_RETRY(closedir(proc_dir));
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if(splashy_command_pid != 0){
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TEMP_FAILURE_RETRY(kill(splashy_command_pid, SIGTERM));
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TEMP_FAILURE_RETRY(kill(splashy_pid, SIGTERM));
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while(TEMP_FAILURE_RETRY(kill(splashy_pid, 0)) == 0){
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TEMP_FAILURE_RETRY(kill(splashy_pid, SIGKILL));
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pid_t new_splashy_pid = (pid_t)TEMP_FAILURE_RETRY(fork());
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if(new_splashy_pid == 0){
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/* Child; will become new splashy process */
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/* Make the effective user ID (root) the only user ID instead of
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the real user ID (_mandos) */
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ret = setuid(geteuid());
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error_plus(0, errno, "setuid");
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error_plus(0, errno, "chdir");
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/* if(fork() != 0){ */
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/* _exit(EXIT_SUCCESS); */
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ret = dup2(STDERR_FILENO, STDOUT_FILENO); /* replace stdout */
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error_plus(0, errno, "dup2");
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execl("/sbin/splashy", "/sbin/splashy", "boot", (char *)NULL);
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error_plus(0, errno, "execl");
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_exit(EX_UNAVAILABLE);
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if(interrupted_by_signal){
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struct sigaction signal_action;
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sigemptyset(&signal_action.sa_mask);
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signal_action.sa_handler = SIG_DFL;
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ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
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&signal_action, NULL));
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error_plus(0, errno, "sigaction");
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ret = raise(signal_received);
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} while(ret != 0 and errno == EINTR);
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error_plus(0, errno, "raise");
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TEMP_FAILURE_RETRY(pause());
added
removed
plugins.d/splashy.c
