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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 © 2008-2018, 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, ENOENT, EINTR */
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#include <string.h> /* strerror(), strlen(), memcmp() */
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#include <error.h> /* error() */
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#include <stdlib.h> /* free(), getenv(), realloc(),
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EXIT_FAILURE, EXIT_SUCCESS,
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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 <stddef.h> /* size_t, NULL */
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#include <unistd.h> /* close(), ssize_t, write(),
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readlink(), read(), STDOUT_FILENO,
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sleep(), fork(), setuid(),
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geteuid(), setsid(), chdir(),
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_exit(), dup2(), STDERR_FILENO,
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execv(), TEMP_FAILURE_RETRY(),
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#include <dirent.h> /* DIR, opendir(), struct dirent,
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readdir(), closedir() */
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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 <sys/stat.h> /* struct stat, lstat(), S_ISLNK() */
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#include <sysexits.h> /* EX_OSERR, EX_UNAVAILABLE */
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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 <argz.h> /* argz_count(), argz_extract() */
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sig_atomic_t interrupted_by_signal = 0;
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const char usplash_name[] = "/sbin/usplash";
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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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static bool usplash_write(int *fifo_fd_r,
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const char *cmd, const char *arg){
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* usplash_write(&fd, "TIMEOUT", "15") will write "TIMEOUT 15\0"
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* usplash_write(&fd, "PULSATE", NULL) will write "PULSATE\0"
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if(*fifo_fd_r == -1){
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ret = open("/dev/.initramfs/usplash_fifo", O_WRONLY);
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const char *cmd_line;
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char *cmd_line_alloc = NULL;
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cmd_line_len = strlen(cmd) + 1;
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ret = asprintf(&cmd_line_alloc, "%s %s", cmd, arg);
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cmd_line = cmd_line_alloc;
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cmd_line_len = (size_t)ret + 1;
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while(written < cmd_line_len){
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sret = write(*fifo_fd_r, cmd_line + written,
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cmd_line_len - written);
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free(cmd_line_alloc);
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written += (size_t)sret;
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free(cmd_line_alloc);
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/* Create prompt string */
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char *makeprompt(void){
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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 prompt_start[] = "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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pid_t find_usplash(char **cmdline_r, size_t *cmdline_len_r){
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char *cmdline = NULL;
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size_t cmdline_len = 0;
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DIR *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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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(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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error_plus(0, errno, "asprintf");
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goto fail_find_usplash;
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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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goto fail_find_usplash;
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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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/* Compare executable name */
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if((sret != ((ssize_t)sizeof(exe_target)-1))
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or (memcmp(usplash_name, exe_target,
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sizeof(exe_target)-1) != 0)){
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/* Read and save the command line of usplash in "cmdline" */
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/* Open /proc/<pid>/cmdline */
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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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goto fail_find_usplash;
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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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goto fail_find_usplash;
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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 > cmdline_allocated){
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tmp = realloc(cmdline, cmdline_allocated + blocksize);
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error_plus(0, errno, "realloc");
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goto fail_find_usplash;
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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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goto fail_find_usplash;
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cmdline_len += (size_t)sret;
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error_plus(0, errno, "close");
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goto fail_find_usplash;
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/* Close directory */
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ret = closedir(proc_dir);
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error_plus(0, errno, "closedir");
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goto fail_find_usplash;
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*cmdline_r = cmdline;
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*cmdline_len_r = cmdline_len;
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if(proc_dir != NULL){
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int main(__attribute__((unused))int argc,
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__attribute__((unused))char **argv){
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pid_t usplash_pid = -1;
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bool usplash_accessed = false;
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int status = EXIT_FAILURE; /* Default failure exit status */
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char *prompt = makeprompt();
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/* Find usplash process */
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char *cmdline = NULL;
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size_t cmdline_len = 0;
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usplash_pid = find_usplash(&cmdline, &cmdline_len);
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if(usplash_pid == 0){
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status = 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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ret = sigaddset(&new_action.sa_mask, SIGHUP);
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error_plus(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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ret = sigaction(SIGINT, NULL, &old_action);
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error_plus(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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ret = sigaction(SIGHUP, NULL, &old_action);
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error_plus(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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ret = sigaction(SIGTERM, NULL, &old_action);
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error_plus(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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usplash_accessed = true;
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/* Write command to FIFO */
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if(not usplash_write(&fifo_fd, "TIMEOUT", "0")){
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error_plus(0, errno, "usplash_write");
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if(interrupted_by_signal){
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if(not usplash_write(&fifo_fd, "INPUTQUIET", prompt)){
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error_plus(0, errno, "usplash_write");
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if(interrupted_by_signal){
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/* Read reply from usplash */
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outfifo_fd = open("/dev/.initramfs/usplash_outfifo", O_RDONLY);
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if(outfifo_fd == -1){
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error_plus(0, errno, "open");
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if(interrupted_by_signal){
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size_t buf_allocated = 0;
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const size_t blocksize = 1024;
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/* Allocate more space */
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if(buf_len + blocksize > buf_allocated){
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char *tmp = realloc(buf, buf_allocated + blocksize);
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error_plus(0, errno, "realloc");
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buf_allocated += blocksize;
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sret = read(outfifo_fd, buf + buf_len,
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buf_allocated - buf_len);
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error_plus(0, errno, "read");
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if(interrupted_by_signal){
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buf_len += (size_t)sret;
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ret = close(outfifo_fd);
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error_plus(0, errno, "close");
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if(interrupted_by_signal){
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if(not usplash_write(&fifo_fd, "TIMEOUT", "15")){
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error_plus(0, errno, "usplash_write");
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if(interrupted_by_signal){
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ret = close(fifo_fd);
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error_plus(0, errno, "close");
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/* Print password to stdout */
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while(written < buf_len){
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sret = write(STDOUT_FILENO, buf + written, buf_len - written);
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error_plus(0, errno, "write");
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if(interrupted_by_signal){
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written += (size_t)sret;
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if(interrupted_by_signal){
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/* If usplash was never accessed, we can stop now */
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if(not usplash_accessed){
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ret = close(fifo_fd);
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if(ret == -1 and errno != EINTR){
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error_plus(0, errno, "close");
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/* Close output FIFO */
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if(outfifo_fd != -1){
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ret = close(outfifo_fd);
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error_plus(0, errno, "close");
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/* Create argv for new usplash*/
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char **cmdline_argv = malloc((argz_count(cmdline, cmdline_len) + 1)
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* sizeof(char *)); /* Count args */
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if(cmdline_argv == NULL){
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error_plus(0, errno, "malloc");
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argz_extract(cmdline, cmdline_len, cmdline_argv); /* Create argv */
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/* Kill old usplash */
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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);
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pid_t new_usplash_pid = fork();
621
if(new_usplash_pid == 0){
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/* Child; will become new usplash process */
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/* Make the effective user ID (root) the only user ID instead of
625
the real user ID (_mandos) */
626
ret = setuid(geteuid());
628
error_plus(0, errno, "setuid");
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error_plus(0, errno, "chdir");
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/* if(fork() != 0){ */
638
/* _exit(EXIT_SUCCESS); */
640
ret = dup2(STDERR_FILENO, STDOUT_FILENO); /* replace our stdout */
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error_plus(0, errno, "dup2");
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execv(usplash_name, cmdline_argv);
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if(not interrupted_by_signal){
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error_plus(0, errno, "execv");
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if(not usplash_write(&fifo_fd, "PULSATE", NULL)){
659
error_plus(0, errno, "usplash_write");
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/* Close FIFO (again) */
665
ret = close(fifo_fd);
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if(ret == -1 and errno != EINTR){
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error_plus(0, errno, "close");
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if(interrupted_by_signal){
673
struct sigaction signal_action = { .sa_handler = SIG_DFL };
674
sigemptyset(&signal_action.sa_mask);
675
ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
676
&signal_action, NULL));
678
error_plus(0, errno, "sigaction");
681
ret = raise(signal_received);
682
} while(ret != 0 and errno == EINTR);
684
error_plus(0, errno, "raise");
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TEMP_FAILURE_RETRY(pause());
added
removed
plugins.d/usplash.c
