1
/* -*- coding: utf-8 -*- */
3
* Splashy - Read a password from splashy and output it
5
* Copyright © 2008-2018, 2021-2022 Teddy Hogeborn
6
* Copyright © 2008-2018, 2021-2022 Björn Påhlsson
8
* This file is part of Mandos.
10
* Mandos is free software: you can redistribute it and/or modify it
11
* under the terms of the GNU General Public License as published by
12
* the Free Software Foundation, either version 3 of the License, or
13
* (at your option) any later version.
15
* Mandos is distributed in the hope that it will be useful, but
16
* WITHOUT ANY WARRANTY; without even the implied warranty of
17
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18
* General Public License for more details.
20
* You should have received a copy of the GNU General Public License
21
* along with Mandos. If not, see <http://www.gnu.org/licenses/>.
23
* Contact the authors at <mandos@recompile.se>.
26
#define _GNU_SOURCE /* vasprintf(),
27
program_invocation_short_name,
28
asprintf(), TEMP_FAILURE_RETRY() */
29
#include <sys/types.h> /* sig_atomic_t, pid_t, setuid(),
30
geteuid(), setsid() */
31
#include <stdarg.h> /* va_list, va_start(), vfprintf() */
32
#include <stdio.h> /* vasprintf(), fprintf(), stderr,
33
vfprintf(), asprintf() */
34
#include <errno.h> /* program_invocation_short_name,
35
errno, EACCES, ENOTDIR, ELOOP,
36
ENOENT, ENAMETOOLONG, EMFILE,
37
ENFILE, ENOMEM, ENOEXEC, EINVAL,
38
E2BIG, EFAULT, EIO, ETXTBSY,
39
EISDIR, ELIBBAD, EPERM, EINTR,
41
#include <string.h> /* strerror(), memcmp() */
42
#include <error.h> /* error() */
43
#include <stdlib.h> /* free(), EXIT_FAILURE, getenv(),
44
EXIT_SUCCESS, abort() */
45
#include <stddef.h> /* NULL */
46
#include <dirent.h> /* DIR, opendir(), struct dirent,
47
readdir(), closedir() */
48
#include <sysexits.h> /* EX_OSERR, EX_OSFILE,
50
#include <inttypes.h> /* intmax_t, strtoimax() */
51
#include <iso646.h> /* or, not, and */
52
#include <unistd.h> /* ssize_t, readlink(), fork(),
54
TEMP_FAILURE_RETRY(), sleep(),
55
setuid(), geteuid(), setsid(),
56
chdir(), dup2(), STDERR_FILENO,
57
STDOUT_FILENO, pause() */
58
#include <sys/stat.h> /* struct stat, lstat(), S_ISLNK() */
59
#include <signal.h> /* struct sigaction, sigemptyset(),
60
sigaddset(), SIGINT, SIGHUP,
61
SIGTERM, SIG_IGN, kill(), SIGKILL,
63
#include <sys/wait.h> /* waitpid(), WIFEXITED(),
66
sig_atomic_t interrupted_by_signal = 0;
69
/* Function to use when printing errors */
70
__attribute__((format (gnu_printf, 3, 4)))
71
void error_plus(int status, int errnum, const char *formatstring,
77
va_start(ap, formatstring);
78
ret = vasprintf(&text, formatstring, ap);
80
fprintf(stderr, "Mandos plugin %s: ",
81
program_invocation_short_name);
82
vfprintf(stderr, formatstring, ap);
83
fprintf(stderr, ": ");
84
fprintf(stderr, "%s\n", strerror(errnum));
85
error(status, errno, "vasprintf while printing error");
88
fprintf(stderr, "Mandos plugin ");
89
error(status, errnum, "%s", text);
94
static void termination_handler(int signum){
95
if(interrupted_by_signal){
98
interrupted_by_signal = 1;
99
signal_received = signum;
102
int main(__attribute__((unused))int argc,
103
__attribute__((unused))char **argv){
106
DIR *proc_dir = NULL;
107
pid_t splashy_pid = 0;
108
pid_t splashy_command_pid = 0;
109
int exitstatus = EXIT_FAILURE;
111
/* Create prompt string */
113
const char *const cryptsource = getenv("cryptsource");
114
const char *const crypttarget = getenv("crypttarget");
115
const char *const prompt_start = "getpass "
116
"Enter passphrase to unlock the disk";
118
if(cryptsource == NULL){
119
if(crypttarget == NULL){
120
ret = asprintf(&prompt, "%s: ", prompt_start);
122
ret = asprintf(&prompt, "%s (%s): ", prompt_start,
126
if(crypttarget == NULL){
127
ret = asprintf(&prompt, "%s %s: ", prompt_start, cryptsource);
129
ret = asprintf(&prompt, "%s %s (%s): ", prompt_start,
130
cryptsource, crypttarget);
135
exitstatus = EX_OSERR;
140
/* Find splashy process */
142
const char splashy_name[] = "/sbin/splashy";
143
proc_dir = opendir("/proc");
144
if(proc_dir == NULL){
146
error_plus(0, errno, "opendir");
153
exitstatus = EX_OSFILE;
159
exitstatus = EX_OSERR;
164
for(struct dirent *proc_ent = readdir(proc_dir);
166
proc_ent = readdir(proc_dir)){
172
tmpmax = strtoimax(proc_ent->d_name, &tmp, 10);
173
if(errno != 0 or tmp == proc_ent->d_name or *tmp != '\0'
174
or tmpmax != (pid_t)tmpmax){
180
/* Find the executable name by doing readlink() on the
181
/proc/<pid>/exe link */
182
char exe_target[sizeof(splashy_name)];
186
ret = asprintf(&exe_link, "/proc/%s/exe", proc_ent->d_name);
188
error_plus(0, errno, "asprintf");
189
exitstatus = EX_OSERR;
193
/* Check that it refers to a symlink owned by root:root */
194
struct stat exe_stat;
195
ret = lstat(exe_link, &exe_stat);
202
error_plus(0, errno, "lstat");
209
exitstatus = EX_OSFILE;
212
exitstatus = EX_OSERR;
217
if(not S_ISLNK(exe_stat.st_mode)
218
or exe_stat.st_uid != 0
219
or exe_stat.st_gid != 0){
224
sret = readlink(exe_link, exe_target, sizeof(exe_target));
227
if((sret == ((ssize_t)sizeof(exe_target)-1))
228
and (memcmp(splashy_name, exe_target,
229
sizeof(exe_target)-1) == 0)){
237
if(splashy_pid == 0){
238
exitstatus = EX_UNAVAILABLE;
242
/* Set up the signal handler */
244
struct sigaction old_action,
245
new_action = { .sa_handler = termination_handler,
247
sigemptyset(&new_action.sa_mask);
248
ret = sigaddset(&new_action.sa_mask, SIGINT);
250
error_plus(0, errno, "sigaddset");
251
exitstatus = EX_OSERR;
254
ret = sigaddset(&new_action.sa_mask, SIGHUP);
256
error_plus(0, errno, "sigaddset");
257
exitstatus = EX_OSERR;
260
ret = sigaddset(&new_action.sa_mask, SIGTERM);
262
error_plus(0, errno, "sigaddset");
263
exitstatus = EX_OSERR;
266
ret = sigaction(SIGINT, NULL, &old_action);
268
error_plus(0, errno, "sigaction");
269
exitstatus = EX_OSERR;
272
if(old_action.sa_handler != SIG_IGN){
273
ret = sigaction(SIGINT, &new_action, NULL);
275
error_plus(0, errno, "sigaction");
276
exitstatus = EX_OSERR;
280
ret = sigaction(SIGHUP, NULL, &old_action);
282
error_plus(0, errno, "sigaction");
283
exitstatus = EX_OSERR;
286
if(old_action.sa_handler != SIG_IGN){
287
ret = sigaction(SIGHUP, &new_action, NULL);
289
error_plus(0, errno, "sigaction");
290
exitstatus = EX_OSERR;
294
ret = sigaction(SIGTERM, NULL, &old_action);
296
error_plus(0, errno, "sigaction");
297
exitstatus = EX_OSERR;
300
if(old_action.sa_handler != SIG_IGN){
301
ret = sigaction(SIGTERM, &new_action, NULL);
303
error_plus(0, errno, "sigaction");
304
exitstatus = EX_OSERR;
310
if(interrupted_by_signal){
314
/* Fork off the splashy command to prompt for password */
315
splashy_command_pid = fork();
316
if(splashy_command_pid != 0 and interrupted_by_signal){
319
if(splashy_command_pid == -1){
320
error_plus(0, errno, "fork");
321
exitstatus = EX_OSERR;
325
if(splashy_command_pid == 0){
326
if(not interrupted_by_signal){
327
const char splashy_command[] = "/sbin/splashy_update";
328
execl(splashy_command, splashy_command, prompt, (char *)NULL);
330
error_plus(0, errno, "execl");
336
_exit(EX_UNAVAILABLE);
351
case ELIBBAD: /* Linux only */
365
if(interrupted_by_signal){
369
/* Wait for command to complete */
373
ret = waitpid(splashy_command_pid, &status, 0);
374
} while(ret == -1 and errno == EINTR
375
and not interrupted_by_signal);
376
if(interrupted_by_signal){
380
error_plus(0, errno, "waitpid");
382
splashy_command_pid = 0;
385
/* The child process has exited */
386
splashy_command_pid = 0;
387
if(WIFEXITED(status) and WEXITSTATUS(status) == 0){
397
if(proc_dir != NULL){
398
TEMP_FAILURE_RETRY(closedir(proc_dir));
401
if(splashy_command_pid != 0){
402
TEMP_FAILURE_RETRY(kill(splashy_command_pid, SIGTERM));
404
TEMP_FAILURE_RETRY(kill(splashy_pid, SIGTERM));
406
while(TEMP_FAILURE_RETRY(kill(splashy_pid, 0)) == 0){
407
TEMP_FAILURE_RETRY(kill(splashy_pid, SIGKILL));
410
pid_t new_splashy_pid = (pid_t)TEMP_FAILURE_RETRY(fork());
411
if(new_splashy_pid == 0){
412
/* Child; will become new splashy process */
414
/* Make the effective user ID (root) the only user ID instead of
415
the real user ID (_mandos) */
416
ret = setuid(geteuid());
418
error_plus(0, errno, "setuid");
424
error_plus(0, errno, "chdir");
426
/* if(fork() != 0){ */
427
/* _exit(EXIT_SUCCESS); */
429
ret = dup2(STDERR_FILENO, STDOUT_FILENO); /* replace stdout */
431
error_plus(0, errno, "dup2");
435
execl("/sbin/splashy", "/sbin/splashy", "boot", (char *)NULL);
438
error_plus(0, errno, "execl");
444
_exit(EX_UNAVAILABLE);
457
if(interrupted_by_signal){
458
struct sigaction signal_action;
459
sigemptyset(&signal_action.sa_mask);
460
signal_action.sa_handler = SIG_DFL;
461
ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,
462
&signal_action, NULL));
464
error_plus(0, errno, "sigaction");
467
ret = raise(signal_received);
468
} while(ret != 0 and errno == EINTR);
470
error_plus(0, errno, "raise");
473
TEMP_FAILURE_RETRY(pause());
added
removed
plugins.d/splashy.c
