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 "sysemu/sysemu.h" 34 #include "net/slirp.h" 35 #include "qemu-options.h" 36 #include "qemu/error-report.h" 37 #include "qemu/log.h" 38 #include "qemu/cutils.h" 39 40 #ifdef CONFIG_LINUX 41 #include <sys/prctl.h> 42 #endif 43 44 /* 45 * Must set all three of these at once. 46 * Legal combinations are unset by name by uid 47 */ 48 static struct passwd *user_pwd; /* NULL non-NULL NULL */ 49 static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ 50 static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ 51 52 static const char *chroot_dir; 53 static int daemonize; 54 static int daemon_pipe; 55 56 void os_setup_early_signal_handling(void) 57 { 58 struct sigaction act; 59 sigfillset(&act.sa_mask); 60 act.sa_flags = 0; 61 act.sa_handler = SIG_IGN; 62 sigaction(SIGPIPE, &act, NULL); 63 } 64 65 static void termsig_handler(int signal, siginfo_t *info, void *c) 66 { 67 qemu_system_killed(info->si_signo, info->si_pid); 68 } 69 70 void os_setup_signal_handling(void) 71 { 72 struct sigaction act; 73 74 memset(&act, 0, sizeof(act)); 75 act.sa_sigaction = termsig_handler; 76 act.sa_flags = SA_SIGINFO; 77 sigaction(SIGINT, &act, NULL); 78 sigaction(SIGHUP, &act, NULL); 79 sigaction(SIGTERM, &act, NULL); 80 } 81 82 /* Find a likely location for support files using the location of the binary. 83 For installed binaries this will be "$bindir/../share/qemu". When 84 running from the build tree this will be "$bindir/../pc-bios". */ 85 #define SHARE_SUFFIX "/share/qemu" 86 #define BUILD_SUFFIX "/pc-bios" 87 char *os_find_datadir(void) 88 { 89 char *dir, *exec_dir; 90 char *res; 91 size_t max_len; 92 93 exec_dir = qemu_get_exec_dir(); 94 if (exec_dir == NULL) { 95 return NULL; 96 } 97 dir = g_path_get_dirname(exec_dir); 98 99 max_len = strlen(dir) + 100 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; 101 res = g_malloc0(max_len); 102 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); 103 if (access(res, R_OK)) { 104 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); 105 if (access(res, R_OK)) { 106 g_free(res); 107 res = NULL; 108 } 109 } 110 111 g_free(dir); 112 g_free(exec_dir); 113 return res; 114 } 115 #undef SHARE_SUFFIX 116 #undef BUILD_SUFFIX 117 118 void os_set_proc_name(const char *s) 119 { 120 #if defined(PR_SET_NAME) 121 char name[16]; 122 if (!s) 123 return; 124 pstrcpy(name, sizeof(name), s); 125 /* Could rewrite argv[0] too, but that's a bit more complicated. 126 This simple way is enough for `top'. */ 127 if (prctl(PR_SET_NAME, name)) { 128 error_report("unable to change process name: %s", strerror(errno)); 129 exit(1); 130 } 131 #else 132 error_report("Change of process name not supported by your OS"); 133 exit(1); 134 #endif 135 } 136 137 138 static bool os_parse_runas_uid_gid(const char *optarg) 139 { 140 unsigned long lv; 141 const char *ep; 142 uid_t got_uid; 143 gid_t got_gid; 144 int rc; 145 146 rc = qemu_strtoul(optarg, &ep, 0, &lv); 147 got_uid = lv; /* overflow here is ID in C99 */ 148 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { 149 return false; 150 } 151 152 rc = qemu_strtoul(ep + 1, 0, 0, &lv); 153 got_gid = lv; /* overflow here is ID in C99 */ 154 if (rc || got_gid != lv || got_gid == (gid_t)-1) { 155 return false; 156 } 157 158 user_pwd = NULL; 159 user_uid = got_uid; 160 user_gid = got_gid; 161 return true; 162 } 163 164 /* 165 * Parse OS specific command line options. 166 * return 0 if option handled, -1 otherwise 167 */ 168 int os_parse_cmd_args(int index, const char *optarg) 169 { 170 switch (index) { 171 case QEMU_OPTION_runas: 172 user_pwd = getpwnam(optarg); 173 if (user_pwd) { 174 user_uid = -1; 175 user_gid = -1; 176 } else if (!os_parse_runas_uid_gid(optarg)) { 177 error_report("User \"%s\" doesn't exist" 178 " (and is not <uid>:<gid>)", 179 optarg); 180 exit(1); 181 } 182 break; 183 case QEMU_OPTION_chroot: 184 chroot_dir = optarg; 185 break; 186 case QEMU_OPTION_daemonize: 187 daemonize = 1; 188 break; 189 #if defined(CONFIG_LINUX) 190 case QEMU_OPTION_enablefips: 191 fips_set_state(true); 192 break; 193 #endif 194 default: 195 return -1; 196 } 197 198 return 0; 199 } 200 201 static void change_process_uid(void) 202 { 203 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 204 assert((user_uid == (uid_t)-1) == 205 (user_gid == (gid_t)-1)); 206 207 if (user_pwd || user_uid != (uid_t)-1) { 208 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 209 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 210 if (setgid(intended_gid) < 0) { 211 error_report("Failed to setgid(%d)", intended_gid); 212 exit(1); 213 } 214 if (user_pwd) { 215 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 216 error_report("Failed to initgroups(\"%s\", %d)", 217 user_pwd->pw_name, user_pwd->pw_gid); 218 exit(1); 219 } 220 } else { 221 if (setgroups(1, &user_gid) < 0) { 222 error_report("Failed to setgroups(1, [%d])", 223 user_gid); 224 exit(1); 225 } 226 } 227 if (setuid(intended_uid) < 0) { 228 error_report("Failed to setuid(%d)", intended_uid); 229 exit(1); 230 } 231 if (setuid(0) != -1) { 232 error_report("Dropping privileges failed"); 233 exit(1); 234 } 235 } 236 } 237 238 static void change_root(void) 239 { 240 if (chroot_dir) { 241 if (chroot(chroot_dir) < 0) { 242 error_report("chroot failed"); 243 exit(1); 244 } 245 if (chdir("/")) { 246 error_report("not able to chdir to /: %s", strerror(errno)); 247 exit(1); 248 } 249 } 250 251 } 252 253 void os_daemonize(void) 254 { 255 if (daemonize) { 256 pid_t pid; 257 int fds[2]; 258 259 if (pipe(fds) == -1) { 260 exit(1); 261 } 262 263 pid = fork(); 264 if (pid > 0) { 265 uint8_t status; 266 ssize_t len; 267 268 close(fds[1]); 269 270 do { 271 len = read(fds[0], &status, 1); 272 } while (len < 0 && errno == EINTR); 273 274 /* only exit successfully if our child actually wrote 275 * a one-byte zero to our pipe, upon successful init */ 276 exit(len == 1 && status == 0 ? 0 : 1); 277 278 } else if (pid < 0) { 279 exit(1); 280 } 281 282 close(fds[0]); 283 daemon_pipe = fds[1]; 284 qemu_set_cloexec(daemon_pipe); 285 286 setsid(); 287 288 pid = fork(); 289 if (pid > 0) { 290 exit(0); 291 } else if (pid < 0) { 292 exit(1); 293 } 294 umask(027); 295 296 signal(SIGTSTP, SIG_IGN); 297 signal(SIGTTOU, SIG_IGN); 298 signal(SIGTTIN, SIG_IGN); 299 } 300 } 301 302 void os_setup_post(void) 303 { 304 int fd = 0; 305 306 if (daemonize) { 307 if (chdir("/")) { 308 error_report("not able to chdir to /: %s", strerror(errno)); 309 exit(1); 310 } 311 TFR(fd = qemu_open("/dev/null", O_RDWR)); 312 if (fd == -1) { 313 exit(1); 314 } 315 } 316 317 change_root(); 318 change_process_uid(); 319 320 if (daemonize) { 321 uint8_t status = 0; 322 ssize_t len; 323 324 dup2(fd, 0); 325 dup2(fd, 1); 326 /* In case -D is given do not redirect stderr to /dev/null */ 327 if (!qemu_logfile) { 328 dup2(fd, 2); 329 } 330 331 close(fd); 332 333 do { 334 len = write(daemon_pipe, &status, 1); 335 } while (len < 0 && errno == EINTR); 336 if (len != 1) { 337 exit(1); 338 } 339 } 340 } 341 342 void os_set_line_buffering(void) 343 { 344 setvbuf(stdout, NULL, _IOLBF, 0); 345 } 346 347 int qemu_create_pidfile(const char *filename) 348 { 349 char buffer[128]; 350 int len; 351 int fd; 352 353 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 354 if (fd == -1) { 355 return -1; 356 } 357 if (lockf(fd, F_TLOCK, 0) == -1) { 358 close(fd); 359 return -1; 360 } 361 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid()); 362 if (write(fd, buffer, len) != len) { 363 close(fd); 364 return -1; 365 } 366 367 /* keep pidfile open & locked forever */ 368 return 0; 369 } 370 371 bool is_daemonized(void) 372 { 373 return daemonize; 374 } 375 376 int os_mlock(void) 377 { 378 int ret = 0; 379 380 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 381 if (ret < 0) { 382 error_report("mlockall: %s", strerror(errno)); 383 } 384 385 return ret; 386 } 387