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 #include "qemu-common.h" 33 /* Needed early for CONFIG_BSD etc. */ 34 #include "net/slirp.h" 35 #include "qemu-options.h" 36 #include "qemu/error-report.h" 37 #include "qemu/log.h" 38 #include "sysemu/runstate.h" 39 #include "qemu/cutils.h" 40 41 #ifdef CONFIG_LINUX 42 #include <sys/prctl.h> 43 #endif 44 45 /* 46 * Must set all three of these at once. 47 * Legal combinations are unset by name by uid 48 */ 49 static struct passwd *user_pwd; /* NULL non-NULL NULL */ 50 static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */ 51 static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */ 52 53 static const char *chroot_dir; 54 static int daemonize; 55 static int daemon_pipe; 56 57 void os_setup_early_signal_handling(void) 58 { 59 struct sigaction act; 60 sigfillset(&act.sa_mask); 61 act.sa_flags = 0; 62 act.sa_handler = SIG_IGN; 63 sigaction(SIGPIPE, &act, NULL); 64 } 65 66 static void termsig_handler(int signal, siginfo_t *info, void *c) 67 { 68 qemu_system_killed(info->si_signo, info->si_pid); 69 } 70 71 void os_setup_signal_handling(void) 72 { 73 struct sigaction act; 74 75 memset(&act, 0, sizeof(act)); 76 act.sa_sigaction = termsig_handler; 77 act.sa_flags = SA_SIGINFO; 78 sigaction(SIGINT, &act, NULL); 79 sigaction(SIGHUP, &act, NULL); 80 sigaction(SIGTERM, &act, NULL); 81 } 82 83 /* 84 * Find a likely location for support files using the location of the binary. 85 * When running from the build tree this will be "$bindir/../pc-bios". 86 * Otherwise, this is CONFIG_QEMU_DATADIR. 87 */ 88 char *os_find_datadir(void) 89 { 90 g_autofree char *exec_dir = NULL; 91 g_autofree char *dir = NULL; 92 93 exec_dir = qemu_get_exec_dir(); 94 g_return_val_if_fail(exec_dir != NULL, NULL); 95 96 dir = g_build_filename(exec_dir, "..", "pc-bios", NULL); 97 if (g_file_test(dir, G_FILE_TEST_IS_DIR)) { 98 return g_steal_pointer(&dir); 99 } 100 101 return g_strdup(CONFIG_QEMU_DATADIR); 102 } 103 104 void os_set_proc_name(const char *s) 105 { 106 #if defined(PR_SET_NAME) 107 char name[16]; 108 if (!s) 109 return; 110 pstrcpy(name, sizeof(name), s); 111 /* Could rewrite argv[0] too, but that's a bit more complicated. 112 This simple way is enough for `top'. */ 113 if (prctl(PR_SET_NAME, name)) { 114 error_report("unable to change process name: %s", strerror(errno)); 115 exit(1); 116 } 117 #else 118 error_report("Change of process name not supported by your OS"); 119 exit(1); 120 #endif 121 } 122 123 124 static bool os_parse_runas_uid_gid(const char *optarg) 125 { 126 unsigned long lv; 127 const char *ep; 128 uid_t got_uid; 129 gid_t got_gid; 130 int rc; 131 132 rc = qemu_strtoul(optarg, &ep, 0, &lv); 133 got_uid = lv; /* overflow here is ID in C99 */ 134 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { 135 return false; 136 } 137 138 rc = qemu_strtoul(ep + 1, 0, 0, &lv); 139 got_gid = lv; /* overflow here is ID in C99 */ 140 if (rc || got_gid != lv || got_gid == (gid_t)-1) { 141 return false; 142 } 143 144 user_pwd = NULL; 145 user_uid = got_uid; 146 user_gid = got_gid; 147 return true; 148 } 149 150 /* 151 * Parse OS specific command line options. 152 * return 0 if option handled, -1 otherwise 153 */ 154 int os_parse_cmd_args(int index, const char *optarg) 155 { 156 switch (index) { 157 case QEMU_OPTION_runas: 158 user_pwd = getpwnam(optarg); 159 if (user_pwd) { 160 user_uid = -1; 161 user_gid = -1; 162 } else if (!os_parse_runas_uid_gid(optarg)) { 163 error_report("User \"%s\" doesn't exist" 164 " (and is not <uid>:<gid>)", 165 optarg); 166 exit(1); 167 } 168 break; 169 case QEMU_OPTION_chroot: 170 chroot_dir = optarg; 171 break; 172 case QEMU_OPTION_daemonize: 173 daemonize = 1; 174 break; 175 #if defined(CONFIG_LINUX) 176 case QEMU_OPTION_enablefips: 177 fips_set_state(true); 178 break; 179 #endif 180 default: 181 return -1; 182 } 183 184 return 0; 185 } 186 187 static void change_process_uid(void) 188 { 189 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 190 assert((user_uid == (uid_t)-1) == 191 (user_gid == (gid_t)-1)); 192 193 if (user_pwd || user_uid != (uid_t)-1) { 194 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 195 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 196 if (setgid(intended_gid) < 0) { 197 error_report("Failed to setgid(%d)", intended_gid); 198 exit(1); 199 } 200 if (user_pwd) { 201 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 202 error_report("Failed to initgroups(\"%s\", %d)", 203 user_pwd->pw_name, user_pwd->pw_gid); 204 exit(1); 205 } 206 } else { 207 if (setgroups(1, &user_gid) < 0) { 208 error_report("Failed to setgroups(1, [%d])", 209 user_gid); 210 exit(1); 211 } 212 } 213 if (setuid(intended_uid) < 0) { 214 error_report("Failed to setuid(%d)", intended_uid); 215 exit(1); 216 } 217 if (setuid(0) != -1) { 218 error_report("Dropping privileges failed"); 219 exit(1); 220 } 221 } 222 } 223 224 static void change_root(void) 225 { 226 if (chroot_dir) { 227 if (chroot(chroot_dir) < 0) { 228 error_report("chroot failed"); 229 exit(1); 230 } 231 if (chdir("/")) { 232 error_report("not able to chdir to /: %s", strerror(errno)); 233 exit(1); 234 } 235 } 236 237 } 238 239 void os_daemonize(void) 240 { 241 if (daemonize) { 242 pid_t pid; 243 int fds[2]; 244 245 if (pipe(fds) == -1) { 246 exit(1); 247 } 248 249 pid = fork(); 250 if (pid > 0) { 251 uint8_t status; 252 ssize_t len; 253 254 close(fds[1]); 255 256 do { 257 len = read(fds[0], &status, 1); 258 } while (len < 0 && errno == EINTR); 259 260 /* only exit successfully if our child actually wrote 261 * a one-byte zero to our pipe, upon successful init */ 262 exit(len == 1 && status == 0 ? 0 : 1); 263 264 } else if (pid < 0) { 265 exit(1); 266 } 267 268 close(fds[0]); 269 daemon_pipe = fds[1]; 270 qemu_set_cloexec(daemon_pipe); 271 272 setsid(); 273 274 pid = fork(); 275 if (pid > 0) { 276 exit(0); 277 } else if (pid < 0) { 278 exit(1); 279 } 280 umask(027); 281 282 signal(SIGTSTP, SIG_IGN); 283 signal(SIGTTOU, SIG_IGN); 284 signal(SIGTTIN, SIG_IGN); 285 } 286 } 287 288 void os_setup_post(void) 289 { 290 int fd = 0; 291 292 if (daemonize) { 293 if (chdir("/")) { 294 error_report("not able to chdir to /: %s", strerror(errno)); 295 exit(1); 296 } 297 TFR(fd = qemu_open("/dev/null", O_RDWR)); 298 if (fd == -1) { 299 exit(1); 300 } 301 } 302 303 change_root(); 304 change_process_uid(); 305 306 if (daemonize) { 307 uint8_t status = 0; 308 ssize_t len; 309 310 dup2(fd, 0); 311 dup2(fd, 1); 312 /* In case -D is given do not redirect stderr to /dev/null */ 313 if (!qemu_logfile) { 314 dup2(fd, 2); 315 } 316 317 close(fd); 318 319 do { 320 len = write(daemon_pipe, &status, 1); 321 } while (len < 0 && errno == EINTR); 322 if (len != 1) { 323 exit(1); 324 } 325 } 326 } 327 328 void os_set_line_buffering(void) 329 { 330 setvbuf(stdout, NULL, _IOLBF, 0); 331 } 332 333 bool is_daemonized(void) 334 { 335 return daemonize; 336 } 337 338 int os_mlock(void) 339 { 340 #ifdef HAVE_MLOCKALL 341 int ret = 0; 342 343 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 344 if (ret < 0) { 345 error_report("mlockall: %s", strerror(errno)); 346 } 347 348 return ret; 349 #else 350 return -ENOSYS; 351 #endif 352 } 353