1 /* 2 * os-posix.c 3 * 4 * Copyright (c) 2003-2008 Fabrice Bellard 5 * Copyright (c) 2010 Red Hat, Inc. 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 */ 25 26 #include "qemu/osdep.h" 27 #include <sys/wait.h> 28 #include <pwd.h> 29 #include <grp.h> 30 #include <libgen.h> 31 32 /* Needed early for CONFIG_BSD etc. */ 33 #include "net/slirp.h" 34 #include "qemu/qemu-options.h" 35 #include "qemu/error-report.h" 36 #include "qemu/log.h" 37 #include "sysemu/runstate.h" 38 #include "qemu/cutils.h" 39 #include "qemu/config-file.h" 40 #include "qemu/option.h" 41 #include "qemu/module.h" 42 43 #ifdef CONFIG_LINUX 44 #include <sys/prctl.h> 45 #include "qemu/async-teardown.h" 46 #endif 47 48 /* 49 * Must set all three of these at once. 50 * Legal combinations are unset by name by uid 51 */ 52 static struct passwd *user_pwd; /* NULL non-NULL NULL */ 53 static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ 54 static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ 55 56 static const char *chroot_dir; 57 static int daemonize; 58 static int daemon_pipe; 59 60 void os_setup_early_signal_handling(void) 61 { 62 struct sigaction act; 63 sigfillset(&act.sa_mask); 64 act.sa_flags = 0; 65 act.sa_handler = SIG_IGN; 66 sigaction(SIGPIPE, &act, NULL); 67 } 68 69 static void termsig_handler(int signal, siginfo_t *info, void *c) 70 { 71 qemu_system_killed(info->si_signo, info->si_pid); 72 } 73 74 void os_setup_signal_handling(void) 75 { 76 struct sigaction act; 77 78 memset(&act, 0, sizeof(act)); 79 act.sa_sigaction = termsig_handler; 80 act.sa_flags = SA_SIGINFO; 81 sigaction(SIGINT, &act, NULL); 82 sigaction(SIGHUP, &act, NULL); 83 sigaction(SIGTERM, &act, NULL); 84 } 85 86 void os_set_proc_name(const char *s) 87 { 88 #if defined(PR_SET_NAME) 89 char name[16]; 90 if (!s) 91 return; 92 pstrcpy(name, sizeof(name), s); 93 /* Could rewrite argv[0] too, but that's a bit more complicated. 94 This simple way is enough for `top'. */ 95 if (prctl(PR_SET_NAME, name)) { 96 error_report("unable to change process name: %s", strerror(errno)); 97 exit(1); 98 } 99 #else 100 error_report("Change of process name not supported by your OS"); 101 exit(1); 102 #endif 103 } 104 105 106 static bool os_parse_runas_uid_gid(const char *optarg) 107 { 108 unsigned long lv; 109 const char *ep; 110 uid_t got_uid; 111 gid_t got_gid; 112 int rc; 113 114 rc = qemu_strtoul(optarg, &ep, 0, &lv); 115 got_uid = lv; /* overflow here is ID in C99 */ 116 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { 117 return false; 118 } 119 120 rc = qemu_strtoul(ep + 1, 0, 0, &lv); 121 got_gid = lv; /* overflow here is ID in C99 */ 122 if (rc || got_gid != lv || got_gid == (gid_t)-1) { 123 return false; 124 } 125 126 user_pwd = NULL; 127 user_uid = got_uid; 128 user_gid = got_gid; 129 return true; 130 } 131 132 /* 133 * Parse OS specific command line options. 134 * return 0 if option handled, -1 otherwise 135 */ 136 int os_parse_cmd_args(int index, const char *optarg) 137 { 138 switch (index) { 139 case QEMU_OPTION_runas: 140 user_pwd = getpwnam(optarg); 141 if (user_pwd) { 142 user_uid = -1; 143 user_gid = -1; 144 } else if (!os_parse_runas_uid_gid(optarg)) { 145 error_report("User \"%s\" doesn't exist" 146 " (and is not <uid>:<gid>)", 147 optarg); 148 exit(1); 149 } 150 break; 151 case QEMU_OPTION_chroot: 152 warn_report("option is deprecated, use '-run-with chroot=...' instead"); 153 chroot_dir = optarg; 154 break; 155 case QEMU_OPTION_daemonize: 156 daemonize = 1; 157 break; 158 #if defined(CONFIG_LINUX) 159 /* deprecated */ 160 case QEMU_OPTION_asyncteardown: 161 init_async_teardown(); 162 break; 163 #endif 164 case QEMU_OPTION_run_with: { 165 const char *str; 166 QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"), 167 optarg, false); 168 if (!opts) { 169 exit(1); 170 } 171 #if defined(CONFIG_LINUX) 172 if (qemu_opt_get_bool(opts, "async-teardown", false)) { 173 init_async_teardown(); 174 } 175 #endif 176 str = qemu_opt_get(opts, "chroot"); 177 if (str) { 178 chroot_dir = str; 179 } 180 break; 181 } 182 default: 183 return -1; 184 } 185 186 return 0; 187 } 188 189 static void change_process_uid(void) 190 { 191 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 192 assert((user_uid == (uid_t)-1) == 193 (user_gid == (gid_t)-1)); 194 195 if (user_pwd || user_uid != (uid_t)-1) { 196 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 197 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 198 if (setgid(intended_gid) < 0) { 199 error_report("Failed to setgid(%d)", intended_gid); 200 exit(1); 201 } 202 if (user_pwd) { 203 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 204 error_report("Failed to initgroups(\"%s\", %d)", 205 user_pwd->pw_name, user_pwd->pw_gid); 206 exit(1); 207 } 208 } else { 209 if (setgroups(1, &user_gid) < 0) { 210 error_report("Failed to setgroups(1, [%d])", 211 user_gid); 212 exit(1); 213 } 214 } 215 if (setuid(intended_uid) < 0) { 216 error_report("Failed to setuid(%d)", intended_uid); 217 exit(1); 218 } 219 if (setuid(0) != -1) { 220 error_report("Dropping privileges failed"); 221 exit(1); 222 } 223 } 224 } 225 226 static void change_root(void) 227 { 228 if (chroot_dir) { 229 if (chroot(chroot_dir) < 0) { 230 error_report("chroot failed"); 231 exit(1); 232 } 233 if (chdir("/")) { 234 error_report("not able to chdir to /: %s", strerror(errno)); 235 exit(1); 236 } 237 } 238 239 } 240 241 void os_daemonize(void) 242 { 243 if (daemonize) { 244 pid_t pid; 245 int fds[2]; 246 247 if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { 248 exit(1); 249 } 250 251 pid = fork(); 252 if (pid > 0) { 253 uint8_t status; 254 ssize_t len; 255 256 close(fds[1]); 257 258 do { 259 len = read(fds[0], &status, 1); 260 } while (len < 0 && errno == EINTR); 261 262 /* only exit successfully if our child actually wrote 263 * a one-byte zero to our pipe, upon successful init */ 264 exit(len == 1 && status == 0 ? 0 : 1); 265 266 } else if (pid < 0) { 267 exit(1); 268 } 269 270 close(fds[0]); 271 daemon_pipe = fds[1]; 272 273 setsid(); 274 275 pid = fork(); 276 if (pid > 0) { 277 exit(0); 278 } else if (pid < 0) { 279 exit(1); 280 } 281 umask(027); 282 283 signal(SIGTSTP, SIG_IGN); 284 signal(SIGTTOU, SIG_IGN); 285 signal(SIGTTIN, SIG_IGN); 286 } 287 } 288 289 void os_setup_post(void) 290 { 291 int fd = 0; 292 293 if (daemonize) { 294 if (chdir("/")) { 295 error_report("not able to chdir to /: %s", strerror(errno)); 296 exit(1); 297 } 298 fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR)); 299 if (fd == -1) { 300 exit(1); 301 } 302 } 303 304 change_root(); 305 change_process_uid(); 306 307 if (daemonize) { 308 uint8_t status = 0; 309 ssize_t len; 310 311 dup2(fd, 0); 312 dup2(fd, 1); 313 /* In case -D is given do not redirect stderr to /dev/null */ 314 if (!qemu_log_enabled()) { 315 dup2(fd, 2); 316 } 317 318 close(fd); 319 320 do { 321 len = write(daemon_pipe, &status, 1); 322 } while (len < 0 && errno == EINTR); 323 if (len != 1) { 324 exit(1); 325 } 326 } 327 } 328 329 void os_set_line_buffering(void) 330 { 331 setvbuf(stdout, NULL, _IOLBF, 0); 332 } 333 334 bool is_daemonized(void) 335 { 336 return daemonize; 337 } 338 339 int os_set_daemonize(bool d) 340 { 341 daemonize = d; 342 return 0; 343 } 344 345 int os_mlock(void) 346 { 347 #ifdef HAVE_MLOCKALL 348 int ret = 0; 349 350 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 351 if (ret < 0) { 352 error_report("mlockall: %s", strerror(errno)); 353 } 354 355 return ret; 356 #else 357 return -ENOSYS; 358 #endif 359 } 360 361 static QemuOptsList qemu_run_with_opts = { 362 .name = "run-with", 363 .head = QTAILQ_HEAD_INITIALIZER(qemu_run_with_opts.head), 364 .desc = { 365 #if defined(CONFIG_LINUX) 366 { 367 .name = "async-teardown", 368 .type = QEMU_OPT_BOOL, 369 }, 370 #endif 371 { 372 .name = "chroot", 373 .type = QEMU_OPT_STRING, 374 }, 375 { /* end of list */ } 376 }, 377 }; 378 379 static void register_runwith(void) 380 { 381 qemu_add_opts(&qemu_run_with_opts); 382 } 383 opts_init(register_runwith); 384