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 42 #ifdef CONFIG_LINUX 43 #include <sys/prctl.h> 44 #include "qemu/async-teardown.h" 45 #endif 46 47 /* 48 * Must set all three of these at once. 49 * Legal combinations are unset by name by uid 50 */ 51 static struct passwd *user_pwd; /* NULL non-NULL NULL */ 52 static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ 53 static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ 54 55 static const char *chroot_dir; 56 static int daemonize; 57 static int daemon_pipe; 58 59 void os_setup_early_signal_handling(void) 60 { 61 struct sigaction act; 62 sigfillset(&act.sa_mask); 63 act.sa_flags = 0; 64 act.sa_handler = SIG_IGN; 65 sigaction(SIGPIPE, &act, NULL); 66 } 67 68 static void termsig_handler(int signal, siginfo_t *info, void *c) 69 { 70 qemu_system_killed(info->si_signo, info->si_pid); 71 } 72 73 void os_setup_signal_handling(void) 74 { 75 struct sigaction act; 76 77 memset(&act, 0, sizeof(act)); 78 act.sa_sigaction = termsig_handler; 79 act.sa_flags = SA_SIGINFO; 80 sigaction(SIGINT, &act, NULL); 81 sigaction(SIGHUP, &act, NULL); 82 sigaction(SIGTERM, &act, NULL); 83 } 84 85 void os_set_proc_name(const char *s) 86 { 87 #if defined(PR_SET_NAME) 88 char name[16]; 89 if (!s) 90 return; 91 pstrcpy(name, sizeof(name), s); 92 /* Could rewrite argv[0] too, but that's a bit more complicated. 93 This simple way is enough for `top'. */ 94 if (prctl(PR_SET_NAME, name)) { 95 error_report("unable to change process name: %s", strerror(errno)); 96 exit(1); 97 } 98 #else 99 error_report("Change of process name not supported by your OS"); 100 exit(1); 101 #endif 102 } 103 104 105 static bool os_parse_runas_uid_gid(const char *optarg) 106 { 107 unsigned long lv; 108 const char *ep; 109 uid_t got_uid; 110 gid_t got_gid; 111 int rc; 112 113 rc = qemu_strtoul(optarg, &ep, 0, &lv); 114 got_uid = lv; /* overflow here is ID in C99 */ 115 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { 116 return false; 117 } 118 119 rc = qemu_strtoul(ep + 1, 0, 0, &lv); 120 got_gid = lv; /* overflow here is ID in C99 */ 121 if (rc || got_gid != lv || got_gid == (gid_t)-1) { 122 return false; 123 } 124 125 user_pwd = NULL; 126 user_uid = got_uid; 127 user_gid = got_gid; 128 return true; 129 } 130 131 /* 132 * Parse OS specific command line options. 133 * return 0 if option handled, -1 otherwise 134 */ 135 int os_parse_cmd_args(int index, const char *optarg) 136 { 137 switch (index) { 138 case QEMU_OPTION_runas: 139 user_pwd = getpwnam(optarg); 140 if (user_pwd) { 141 user_uid = -1; 142 user_gid = -1; 143 } else if (!os_parse_runas_uid_gid(optarg)) { 144 error_report("User \"%s\" doesn't exist" 145 " (and is not <uid>:<gid>)", 146 optarg); 147 exit(1); 148 } 149 break; 150 case QEMU_OPTION_chroot: 151 chroot_dir = optarg; 152 break; 153 case QEMU_OPTION_daemonize: 154 daemonize = 1; 155 break; 156 #if defined(CONFIG_LINUX) 157 /* deprecated */ 158 case QEMU_OPTION_asyncteardown: 159 init_async_teardown(); 160 break; 161 case QEMU_OPTION_run_with: { 162 QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("run-with"), 163 optarg, false); 164 if (!opts) { 165 exit(1); 166 } 167 if (qemu_opt_get_bool(opts, "async-teardown", false)) { 168 init_async_teardown(); 169 } 170 break; 171 } 172 #endif 173 default: 174 return -1; 175 } 176 177 return 0; 178 } 179 180 static void change_process_uid(void) 181 { 182 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 183 assert((user_uid == (uid_t)-1) == 184 (user_gid == (gid_t)-1)); 185 186 if (user_pwd || user_uid != (uid_t)-1) { 187 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 188 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 189 if (setgid(intended_gid) < 0) { 190 error_report("Failed to setgid(%d)", intended_gid); 191 exit(1); 192 } 193 if (user_pwd) { 194 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 195 error_report("Failed to initgroups(\"%s\", %d)", 196 user_pwd->pw_name, user_pwd->pw_gid); 197 exit(1); 198 } 199 } else { 200 if (setgroups(1, &user_gid) < 0) { 201 error_report("Failed to setgroups(1, [%d])", 202 user_gid); 203 exit(1); 204 } 205 } 206 if (setuid(intended_uid) < 0) { 207 error_report("Failed to setuid(%d)", intended_uid); 208 exit(1); 209 } 210 if (setuid(0) != -1) { 211 error_report("Dropping privileges failed"); 212 exit(1); 213 } 214 } 215 } 216 217 static void change_root(void) 218 { 219 if (chroot_dir) { 220 if (chroot(chroot_dir) < 0) { 221 error_report("chroot failed"); 222 exit(1); 223 } 224 if (chdir("/")) { 225 error_report("not able to chdir to /: %s", strerror(errno)); 226 exit(1); 227 } 228 } 229 230 } 231 232 void os_daemonize(void) 233 { 234 if (daemonize) { 235 pid_t pid; 236 int fds[2]; 237 238 if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { 239 exit(1); 240 } 241 242 pid = fork(); 243 if (pid > 0) { 244 uint8_t status; 245 ssize_t len; 246 247 close(fds[1]); 248 249 do { 250 len = read(fds[0], &status, 1); 251 } while (len < 0 && errno == EINTR); 252 253 /* only exit successfully if our child actually wrote 254 * a one-byte zero to our pipe, upon successful init */ 255 exit(len == 1 && status == 0 ? 0 : 1); 256 257 } else if (pid < 0) { 258 exit(1); 259 } 260 261 close(fds[0]); 262 daemon_pipe = fds[1]; 263 264 setsid(); 265 266 pid = fork(); 267 if (pid > 0) { 268 exit(0); 269 } else if (pid < 0) { 270 exit(1); 271 } 272 umask(027); 273 274 signal(SIGTSTP, SIG_IGN); 275 signal(SIGTTOU, SIG_IGN); 276 signal(SIGTTIN, SIG_IGN); 277 } 278 } 279 280 void os_setup_post(void) 281 { 282 int fd = 0; 283 284 if (daemonize) { 285 if (chdir("/")) { 286 error_report("not able to chdir to /: %s", strerror(errno)); 287 exit(1); 288 } 289 fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR)); 290 if (fd == -1) { 291 exit(1); 292 } 293 } 294 295 change_root(); 296 change_process_uid(); 297 298 if (daemonize) { 299 uint8_t status = 0; 300 ssize_t len; 301 302 dup2(fd, 0); 303 dup2(fd, 1); 304 /* In case -D is given do not redirect stderr to /dev/null */ 305 if (!qemu_log_enabled()) { 306 dup2(fd, 2); 307 } 308 309 close(fd); 310 311 do { 312 len = write(daemon_pipe, &status, 1); 313 } while (len < 0 && errno == EINTR); 314 if (len != 1) { 315 exit(1); 316 } 317 } 318 } 319 320 void os_set_line_buffering(void) 321 { 322 setvbuf(stdout, NULL, _IOLBF, 0); 323 } 324 325 bool is_daemonized(void) 326 { 327 return daemonize; 328 } 329 330 int os_set_daemonize(bool d) 331 { 332 daemonize = d; 333 return 0; 334 } 335 336 int os_mlock(void) 337 { 338 #ifdef HAVE_MLOCKALL 339 int ret = 0; 340 341 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 342 if (ret < 0) { 343 error_report("mlockall: %s", strerror(errno)); 344 } 345 346 return ret; 347 #else 348 return -ENOSYS; 349 #endif 350 } 351