[821] | 1 | /* vi: set sw=4 ts=4: */
|
---|
| 2 | /*
|
---|
| 3 | * Rexec program for system have fork() as vfork() with foreground option
|
---|
| 4 | *
|
---|
| 5 | * Copyright (C) Vladimir N. Oleynik <dzo@simtreas.ru>
|
---|
| 6 | * Copyright (C) 2003 Russ Dill <Russ.Dill@asu.edu>
|
---|
| 7 | *
|
---|
| 8 | * daemon() portion taken from uClibc:
|
---|
| 9 | *
|
---|
| 10 | * Copyright (c) 1991, 1993
|
---|
| 11 | * The Regents of the University of California. All rights reserved.
|
---|
| 12 | *
|
---|
| 13 | * Modified for uClibc by Erik Andersen <andersee@debian.org>
|
---|
| 14 | *
|
---|
[2725] | 15 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
|
---|
[821] | 16 | */
|
---|
| 17 |
|
---|
[2725] | 18 | #include "busybox.h" /* uses applet tables */
|
---|
[821] | 19 |
|
---|
[1765] | 20 | /* This does a fork/exec in one call, using vfork(). Returns PID of new child,
|
---|
| 21 | * -1 for failure. Runs argv[0], searching path if that has no / in it. */
|
---|
[2725] | 22 | pid_t FAST_FUNC spawn(char **argv)
|
---|
[1765] | 23 | {
|
---|
| 24 | /* Compiler should not optimize stores here */
|
---|
| 25 | volatile int failed;
|
---|
| 26 | pid_t pid;
|
---|
[821] | 27 |
|
---|
[2725] | 28 | fflush_all();
|
---|
[1765] | 29 |
|
---|
| 30 | /* Be nice to nommu machines. */
|
---|
| 31 | failed = 0;
|
---|
| 32 | pid = vfork();
|
---|
| 33 | if (pid < 0) /* error */
|
---|
| 34 | return pid;
|
---|
| 35 | if (!pid) { /* child */
|
---|
| 36 | /* This macro is ok - it doesn't do NOEXEC/NOFORK tricks */
|
---|
| 37 | BB_EXECVP(argv[0], argv);
|
---|
| 38 |
|
---|
| 39 | /* We are (maybe) sharing a stack with blocked parent,
|
---|
| 40 | * let parent know we failed and then exit to unblock parent
|
---|
| 41 | * (but don't run atexit() stuff, which would screw up parent.)
|
---|
| 42 | */
|
---|
| 43 | failed = errno;
|
---|
[2725] | 44 | /* mount, for example, does not want the message */
|
---|
| 45 | /*bb_perror_msg("can't execute '%s'", argv[0]);*/
|
---|
[1765] | 46 | _exit(111);
|
---|
| 47 | }
|
---|
| 48 | /* parent */
|
---|
| 49 | /* Unfortunately, this is not reliable: according to standards
|
---|
| 50 | * vfork() can be equivalent to fork() and we won't see value
|
---|
| 51 | * of 'failed'.
|
---|
| 52 | * Interested party can wait on pid and learn exit code.
|
---|
| 53 | * If 111 - then it (most probably) failed to exec */
|
---|
| 54 | if (failed) {
|
---|
[2725] | 55 | safe_waitpid(pid, NULL, 0); /* prevent zombie */
|
---|
[1765] | 56 | errno = failed;
|
---|
| 57 | return -1;
|
---|
| 58 | }
|
---|
| 59 | return pid;
|
---|
| 60 | }
|
---|
| 61 |
|
---|
| 62 | /* Die with an error message if we can't spawn a child process. */
|
---|
[2725] | 63 | pid_t FAST_FUNC xspawn(char **argv)
|
---|
[821] | 64 | {
|
---|
[1765] | 65 | pid_t pid = spawn(argv);
|
---|
| 66 | if (pid < 0)
|
---|
[2725] | 67 | bb_simple_perror_msg_and_die(*argv);
|
---|
[1765] | 68 | return pid;
|
---|
| 69 | }
|
---|
[821] | 70 |
|
---|
[1765] | 71 | #if ENABLE_FEATURE_PREFER_APPLETS
|
---|
[3232] | 72 | struct nofork_save_area {
|
---|
| 73 | jmp_buf die_jmp;
|
---|
| 74 | const char *applet_name;
|
---|
| 75 | uint32_t option_mask32;
|
---|
| 76 | int die_sleep;
|
---|
| 77 | uint8_t xfunc_error_retval;
|
---|
| 78 | };
|
---|
| 79 | static void save_nofork_data(struct nofork_save_area *save)
|
---|
[1765] | 80 | {
|
---|
| 81 | memcpy(&save->die_jmp, &die_jmp, sizeof(die_jmp));
|
---|
[2725] | 82 | save->applet_name = applet_name;
|
---|
[1765] | 83 | save->xfunc_error_retval = xfunc_error_retval;
|
---|
| 84 | save->option_mask32 = option_mask32;
|
---|
| 85 | save->die_sleep = die_sleep;
|
---|
| 86 | }
|
---|
[3232] | 87 | static void restore_nofork_data(struct nofork_save_area *save)
|
---|
[1765] | 88 | {
|
---|
| 89 | memcpy(&die_jmp, &save->die_jmp, sizeof(die_jmp));
|
---|
[2725] | 90 | applet_name = save->applet_name;
|
---|
[1765] | 91 | xfunc_error_retval = save->xfunc_error_retval;
|
---|
| 92 | option_mask32 = save->option_mask32;
|
---|
| 93 | die_sleep = save->die_sleep;
|
---|
| 94 | }
|
---|
| 95 |
|
---|
[3232] | 96 | int FAST_FUNC run_nofork_applet(int applet_no, char **argv)
|
---|
[1765] | 97 | {
|
---|
| 98 | int rc, argc;
|
---|
[3232] | 99 | struct nofork_save_area old;
|
---|
[1765] | 100 |
|
---|
[3232] | 101 | save_nofork_data(&old);
|
---|
| 102 |
|
---|
[2725] | 103 | applet_name = APPLET_NAME(applet_no);
|
---|
| 104 |
|
---|
[1765] | 105 | xfunc_error_retval = EXIT_FAILURE;
|
---|
[2725] | 106 |
|
---|
| 107 | /* In case getopt() or getopt32() was already called:
|
---|
| 108 | * reset the libc getopt() function, which keeps internal state.
|
---|
| 109 | *
|
---|
| 110 | * BSD-derived getopt() functions require that optind be set to 1 in
|
---|
| 111 | * order to reset getopt() state. This used to be generally accepted
|
---|
| 112 | * way of resetting getopt(). However, glibc's getopt()
|
---|
| 113 | * has additional getopt() state beyond optind, and requires that
|
---|
| 114 | * optind be set to zero to reset its state. So the unfortunate state of
|
---|
| 115 | * affairs is that BSD-derived versions of getopt() misbehave if
|
---|
| 116 | * optind is set to 0 in order to reset getopt(), and glibc's getopt()
|
---|
| 117 | * will core dump if optind is set 1 in order to reset getopt().
|
---|
| 118 | *
|
---|
| 119 | * More modern versions of BSD require that optreset be set to 1 in
|
---|
| 120 | * order to reset getopt(). Sigh. Standards, anyone?
|
---|
| 121 | */
|
---|
| 122 | #ifdef __GLIBC__
|
---|
| 123 | optind = 0;
|
---|
| 124 | #else /* BSD style */
|
---|
| 125 | optind = 1;
|
---|
| 126 | /* optreset = 1; */
|
---|
| 127 | #endif
|
---|
| 128 | /* optarg = NULL; opterr = 1; optopt = 63; - do we need this too? */
|
---|
| 129 | /* (values above are what they initialized to in glibc and uclibc) */
|
---|
| 130 | /* option_mask32 = 0; - not needed, no applet depends on it being 0 */
|
---|
| 131 |
|
---|
[1765] | 132 | argc = 1;
|
---|
| 133 | while (argv[argc])
|
---|
| 134 | argc++;
|
---|
| 135 |
|
---|
[3232] | 136 | /* Special flag for xfunc_die(). If xfunc will "die"
|
---|
| 137 | * in NOFORK applet, xfunc_die() sees negative
|
---|
| 138 | * die_sleep and longjmp here instead. */
|
---|
| 139 | die_sleep = -1;
|
---|
| 140 |
|
---|
[1765] | 141 | rc = setjmp(die_jmp);
|
---|
| 142 | if (!rc) {
|
---|
| 143 | /* Some callers (xargs)
|
---|
| 144 | * need argv untouched because they free argv[i]! */
|
---|
| 145 | char *tmp_argv[argc+1];
|
---|
| 146 | memcpy(tmp_argv, argv, (argc+1) * sizeof(tmp_argv[0]));
|
---|
| 147 | /* Finally we can call NOFORK applet's main() */
|
---|
[2725] | 148 | rc = applet_main[applet_no](argc, tmp_argv);
|
---|
[1765] | 149 | } else { /* xfunc died in NOFORK applet */
|
---|
| 150 | /* in case they meant to return 0... */
|
---|
| 151 | if (rc == -2222)
|
---|
| 152 | rc = 0;
|
---|
[821] | 153 | }
|
---|
| 154 |
|
---|
[2725] | 155 | /* Restoring some globals */
|
---|
[3232] | 156 | restore_nofork_data(&old);
|
---|
[2725] | 157 |
|
---|
| 158 | /* Other globals can be simply reset to defaults */
|
---|
| 159 | #ifdef __GLIBC__
|
---|
| 160 | optind = 0;
|
---|
| 161 | #else /* BSD style */
|
---|
| 162 | optind = 1;
|
---|
| 163 | #endif
|
---|
| 164 |
|
---|
| 165 | return rc & 0xff; /* don't confuse people with "exitcodes" >255 */
|
---|
[1765] | 166 | }
|
---|
| 167 | #endif /* FEATURE_PREFER_APPLETS */
|
---|
| 168 |
|
---|
[2725] | 169 | int FAST_FUNC spawn_and_wait(char **argv)
|
---|
[1765] | 170 | {
|
---|
| 171 | int rc;
|
---|
| 172 | #if ENABLE_FEATURE_PREFER_APPLETS
|
---|
[2725] | 173 | int a = find_applet_by_name(argv[0]);
|
---|
[1765] | 174 |
|
---|
[2725] | 175 | if (a >= 0 && (APPLET_IS_NOFORK(a)
|
---|
[3232] | 176 | # if BB_MMU
|
---|
[2725] | 177 | || APPLET_IS_NOEXEC(a) /* NOEXEC trick needs fork() */
|
---|
[3232] | 178 | # endif
|
---|
[1765] | 179 | )) {
|
---|
[3232] | 180 | # if BB_MMU
|
---|
[2725] | 181 | if (APPLET_IS_NOFORK(a))
|
---|
[3232] | 182 | # endif
|
---|
[1765] | 183 | {
|
---|
| 184 | return run_nofork_applet(a, argv);
|
---|
| 185 | }
|
---|
[3232] | 186 | # if BB_MMU
|
---|
[1765] | 187 | /* MMU only */
|
---|
| 188 | /* a->noexec is true */
|
---|
| 189 | rc = fork();
|
---|
| 190 | if (rc) /* parent or error */
|
---|
| 191 | return wait4pid(rc);
|
---|
| 192 | /* child */
|
---|
| 193 | xfunc_error_retval = EXIT_FAILURE;
|
---|
[2725] | 194 | run_applet_no_and_exit(a, argv);
|
---|
[3232] | 195 | # endif
|
---|
[821] | 196 | }
|
---|
[1765] | 197 | #endif /* FEATURE_PREFER_APPLETS */
|
---|
| 198 | rc = spawn(argv);
|
---|
| 199 | return wait4pid(rc);
|
---|
| 200 | }
|
---|
| 201 |
|
---|
| 202 | #if !BB_MMU
|
---|
[2725] | 203 | void FAST_FUNC re_exec(char **argv)
|
---|
[1765] | 204 | {
|
---|
| 205 | /* high-order bit of first char in argv[0] is a hidden
|
---|
| 206 | * "we have (already) re-execed, don't do it again" flag */
|
---|
| 207 | argv[0][0] |= 0x80;
|
---|
| 208 | execv(bb_busybox_exec_path, argv);
|
---|
[2725] | 209 | bb_perror_msg_and_die("can't execute '%s'", bb_busybox_exec_path);
|
---|
[1765] | 210 | }
|
---|
| 211 |
|
---|
[2725] | 212 | pid_t FAST_FUNC fork_or_rexec(char **argv)
|
---|
[1765] | 213 | {
|
---|
| 214 | pid_t pid;
|
---|
| 215 | /* Maybe we are already re-execed and come here again? */
|
---|
| 216 | if (re_execed)
|
---|
[2725] | 217 | return 0;
|
---|
| 218 | pid = xvfork();
|
---|
[1765] | 219 | if (pid) /* parent */
|
---|
[2725] | 220 | return pid;
|
---|
[1765] | 221 | /* child - re-exec ourself */
|
---|
| 222 | re_exec(argv);
|
---|
| 223 | }
|
---|
| 224 | #endif
|
---|
| 225 |
|
---|
| 226 | /* Due to a #define in libbb.h on MMU systems we actually have 1 argument -
|
---|
| 227 | * char **argv "vanishes" */
|
---|
[2725] | 228 | void FAST_FUNC bb_daemonize_or_rexec(int flags, char **argv)
|
---|
[1765] | 229 | {
|
---|
| 230 | int fd;
|
---|
| 231 |
|
---|
| 232 | if (flags & DAEMON_CHDIR_ROOT)
|
---|
| 233 | xchdir("/");
|
---|
| 234 |
|
---|
| 235 | if (flags & DAEMON_DEVNULL_STDIO) {
|
---|
| 236 | close(0);
|
---|
| 237 | close(1);
|
---|
| 238 | close(2);
|
---|
[821] | 239 | }
|
---|
[1765] | 240 |
|
---|
[2725] | 241 | fd = open(bb_dev_null, O_RDWR);
|
---|
| 242 | if (fd < 0) {
|
---|
| 243 | /* NB: we can be called as bb_sanitize_stdio() from init
|
---|
| 244 | * or mdev, and there /dev/null may legitimately not (yet) exist!
|
---|
| 245 | * Do not use xopen above, but obtain _ANY_ open descriptor,
|
---|
| 246 | * even bogus one as below. */
|
---|
| 247 | fd = xopen("/", O_RDONLY); /* don't believe this can fail */
|
---|
| 248 | }
|
---|
[1765] | 249 |
|
---|
| 250 | while ((unsigned)fd < 2)
|
---|
| 251 | fd = dup(fd); /* have 0,1,2 open at least to /dev/null */
|
---|
| 252 |
|
---|
| 253 | if (!(flags & DAEMON_ONLY_SANITIZE)) {
|
---|
[2725] | 254 | if (fork_or_rexec(argv))
|
---|
| 255 | exit(EXIT_SUCCESS); /* parent */
|
---|
[3232] | 256 | /* if daemonizing, detach from stdio & ctty */
|
---|
[1765] | 257 | setsid();
|
---|
| 258 | dup2(fd, 0);
|
---|
| 259 | dup2(fd, 1);
|
---|
| 260 | dup2(fd, 2);
|
---|
[3232] | 261 | if (flags & DAEMON_DOUBLE_FORK) {
|
---|
| 262 | /* On Linux, session leader can acquire ctty
|
---|
| 263 | * unknowingly, by opening a tty.
|
---|
| 264 | * Prevent this: stop being a session leader.
|
---|
| 265 | */
|
---|
| 266 | if (fork_or_rexec(argv))
|
---|
| 267 | exit(EXIT_SUCCESS); /* parent */
|
---|
| 268 | }
|
---|
[1765] | 269 | }
|
---|
| 270 | while (fd > 2) {
|
---|
| 271 | close(fd--);
|
---|
| 272 | if (!(flags & DAEMON_CLOSE_EXTRA_FDS))
|
---|
| 273 | return;
|
---|
| 274 | /* else close everything after fd#2 */
|
---|
| 275 | }
|
---|
[821] | 276 | }
|
---|
[1765] | 277 |
|
---|
[2725] | 278 | void FAST_FUNC bb_sanitize_stdio(void)
|
---|
[1765] | 279 | {
|
---|
| 280 | bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE, NULL);
|
---|
| 281 | }
|
---|