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 #ifdef CONFIG_SLIRP 172 case QEMU_OPTION_smb: 173 error_report("The -smb option is deprecated. " 174 "Please use '-netdev user,smb=...' instead."); 175 if (net_slirp_smb(optarg) < 0) 176 exit(1); 177 break; 178 #endif 179 case QEMU_OPTION_runas: 180 user_pwd = getpwnam(optarg); 181 if (user_pwd) { 182 user_uid = -1; 183 user_gid = -1; 184 } else if (!os_parse_runas_uid_gid(optarg)) { 185 error_report("User \"%s\" doesn't exist" 186 " (and is not <uid>:<gid>)", 187 optarg); 188 exit(1); 189 } 190 break; 191 case QEMU_OPTION_chroot: 192 chroot_dir = optarg; 193 break; 194 case QEMU_OPTION_daemonize: 195 daemonize = 1; 196 break; 197 #if defined(CONFIG_LINUX) 198 case QEMU_OPTION_enablefips: 199 fips_set_state(true); 200 break; 201 #endif 202 default: 203 return -1; 204 } 205 206 return 0; 207 } 208 209 static void change_process_uid(void) 210 { 211 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 212 assert((user_uid == (uid_t)-1) == 213 (user_gid == (gid_t)-1)); 214 215 if (user_pwd || user_uid != (uid_t)-1) { 216 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 217 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 218 if (setgid(intended_gid) < 0) { 219 error_report("Failed to setgid(%d)", intended_gid); 220 exit(1); 221 } 222 if (user_pwd) { 223 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 224 error_report("Failed to initgroups(\"%s\", %d)", 225 user_pwd->pw_name, user_pwd->pw_gid); 226 exit(1); 227 } 228 } else { 229 if (setgroups(1, &user_gid) < 0) { 230 error_report("Failed to setgroups(1, [%d])", 231 user_gid); 232 exit(1); 233 } 234 } 235 if (setuid(intended_uid) < 0) { 236 error_report("Failed to setuid(%d)", intended_uid); 237 exit(1); 238 } 239 if (setuid(0) != -1) { 240 error_report("Dropping privileges failed"); 241 exit(1); 242 } 243 } 244 } 245 246 static void change_root(void) 247 { 248 if (chroot_dir) { 249 if (chroot(chroot_dir) < 0) { 250 error_report("chroot failed"); 251 exit(1); 252 } 253 if (chdir("/")) { 254 error_report("not able to chdir to /: %s", strerror(errno)); 255 exit(1); 256 } 257 } 258 259 } 260 261 void os_daemonize(void) 262 { 263 if (daemonize) { 264 pid_t pid; 265 int fds[2]; 266 267 if (pipe(fds) == -1) { 268 exit(1); 269 } 270 271 pid = fork(); 272 if (pid > 0) { 273 uint8_t status; 274 ssize_t len; 275 276 close(fds[1]); 277 278 do { 279 len = read(fds[0], &status, 1); 280 } while (len < 0 && errno == EINTR); 281 282 /* only exit successfully if our child actually wrote 283 * a one-byte zero to our pipe, upon successful init */ 284 exit(len == 1 && status == 0 ? 0 : 1); 285 286 } else if (pid < 0) { 287 exit(1); 288 } 289 290 close(fds[0]); 291 daemon_pipe = fds[1]; 292 qemu_set_cloexec(daemon_pipe); 293 294 setsid(); 295 296 pid = fork(); 297 if (pid > 0) { 298 exit(0); 299 } else if (pid < 0) { 300 exit(1); 301 } 302 umask(027); 303 304 signal(SIGTSTP, SIG_IGN); 305 signal(SIGTTOU, SIG_IGN); 306 signal(SIGTTIN, SIG_IGN); 307 } 308 } 309 310 void os_setup_post(void) 311 { 312 int fd = 0; 313 314 if (daemonize) { 315 if (chdir("/")) { 316 error_report("not able to chdir to /: %s", strerror(errno)); 317 exit(1); 318 } 319 TFR(fd = qemu_open("/dev/null", O_RDWR)); 320 if (fd == -1) { 321 exit(1); 322 } 323 } 324 325 change_root(); 326 change_process_uid(); 327 328 if (daemonize) { 329 uint8_t status = 0; 330 ssize_t len; 331 332 dup2(fd, 0); 333 dup2(fd, 1); 334 /* In case -D is given do not redirect stderr to /dev/null */ 335 if (!qemu_logfile) { 336 dup2(fd, 2); 337 } 338 339 close(fd); 340 341 do { 342 len = write(daemon_pipe, &status, 1); 343 } while (len < 0 && errno == EINTR); 344 if (len != 1) { 345 exit(1); 346 } 347 } 348 } 349 350 void os_set_line_buffering(void) 351 { 352 setvbuf(stdout, NULL, _IOLBF, 0); 353 } 354 355 int qemu_create_pidfile(const char *filename) 356 { 357 char buffer[128]; 358 int len; 359 int fd; 360 361 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 362 if (fd == -1) { 363 return -1; 364 } 365 if (lockf(fd, F_TLOCK, 0) == -1) { 366 close(fd); 367 return -1; 368 } 369 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid()); 370 if (write(fd, buffer, len) != len) { 371 close(fd); 372 return -1; 373 } 374 375 /* keep pidfile open & locked forever */ 376 return 0; 377 } 378 379 bool is_daemonized(void) 380 { 381 return daemonize; 382 } 383 384 int os_mlock(void) 385 { 386 int ret = 0; 387 388 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 389 if (ret < 0) { 390 error_report("mlockall: %s", strerror(errno)); 391 } 392 393 return ret; 394 } 395