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 * The caller must use g_free() to free the returned data when it is 89 * no longer required. 90 */ 91 char *os_find_datadir(void) 92 { 93 g_autofree char *exec_dir = NULL; 94 g_autofree char *dir = NULL; 95 96 exec_dir = qemu_get_exec_dir(); 97 g_return_val_if_fail(exec_dir != NULL, NULL); 98 99 dir = g_build_filename(exec_dir, "pc-bios", NULL); 100 if (g_file_test(dir, G_FILE_TEST_IS_DIR)) { 101 return g_steal_pointer(&dir); 102 } 103 104 return g_strdup(CONFIG_QEMU_DATADIR); 105 } 106 107 void os_set_proc_name(const char *s) 108 { 109 #if defined(PR_SET_NAME) 110 char name[16]; 111 if (!s) 112 return; 113 pstrcpy(name, sizeof(name), s); 114 /* Could rewrite argv[0] too, but that's a bit more complicated. 115 This simple way is enough for `top'. */ 116 if (prctl(PR_SET_NAME, name)) { 117 error_report("unable to change process name: %s", strerror(errno)); 118 exit(1); 119 } 120 #else 121 error_report("Change of process name not supported by your OS"); 122 exit(1); 123 #endif 124 } 125 126 127 static bool os_parse_runas_uid_gid(const char *optarg) 128 { 129 unsigned long lv; 130 const char *ep; 131 uid_t got_uid; 132 gid_t got_gid; 133 int rc; 134 135 rc = qemu_strtoul(optarg, &ep, 0, &lv); 136 got_uid = lv; /* overflow here is ID in C99 */ 137 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { 138 return false; 139 } 140 141 rc = qemu_strtoul(ep + 1, 0, 0, &lv); 142 got_gid = lv; /* overflow here is ID in C99 */ 143 if (rc || got_gid != lv || got_gid == (gid_t)-1) { 144 return false; 145 } 146 147 user_pwd = NULL; 148 user_uid = got_uid; 149 user_gid = got_gid; 150 return true; 151 } 152 153 /* 154 * Parse OS specific command line options. 155 * return 0 if option handled, -1 otherwise 156 */ 157 int os_parse_cmd_args(int index, const char *optarg) 158 { 159 switch (index) { 160 case QEMU_OPTION_runas: 161 user_pwd = getpwnam(optarg); 162 if (user_pwd) { 163 user_uid = -1; 164 user_gid = -1; 165 } else if (!os_parse_runas_uid_gid(optarg)) { 166 error_report("User \"%s\" doesn't exist" 167 " (and is not <uid>:<gid>)", 168 optarg); 169 exit(1); 170 } 171 break; 172 case QEMU_OPTION_chroot: 173 chroot_dir = optarg; 174 break; 175 case QEMU_OPTION_daemonize: 176 daemonize = 1; 177 break; 178 #if defined(CONFIG_LINUX) 179 case QEMU_OPTION_enablefips: 180 fips_set_state(true); 181 break; 182 #endif 183 default: 184 return -1; 185 } 186 187 return 0; 188 } 189 190 static void change_process_uid(void) 191 { 192 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 193 assert((user_uid == (uid_t)-1) == 194 (user_gid == (gid_t)-1)); 195 196 if (user_pwd || user_uid != (uid_t)-1) { 197 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 198 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 199 if (setgid(intended_gid) < 0) { 200 error_report("Failed to setgid(%d)", intended_gid); 201 exit(1); 202 } 203 if (user_pwd) { 204 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 205 error_report("Failed to initgroups(\"%s\", %d)", 206 user_pwd->pw_name, user_pwd->pw_gid); 207 exit(1); 208 } 209 } else { 210 if (setgroups(1, &user_gid) < 0) { 211 error_report("Failed to setgroups(1, [%d])", 212 user_gid); 213 exit(1); 214 } 215 } 216 if (setuid(intended_uid) < 0) { 217 error_report("Failed to setuid(%d)", intended_uid); 218 exit(1); 219 } 220 if (setuid(0) != -1) { 221 error_report("Dropping privileges failed"); 222 exit(1); 223 } 224 } 225 } 226 227 static void change_root(void) 228 { 229 if (chroot_dir) { 230 if (chroot(chroot_dir) < 0) { 231 error_report("chroot failed"); 232 exit(1); 233 } 234 if (chdir("/")) { 235 error_report("not able to chdir to /: %s", strerror(errno)); 236 exit(1); 237 } 238 } 239 240 } 241 242 void os_daemonize(void) 243 { 244 if (daemonize) { 245 pid_t pid; 246 int fds[2]; 247 248 if (pipe(fds) == -1) { 249 exit(1); 250 } 251 252 pid = fork(); 253 if (pid > 0) { 254 uint8_t status; 255 ssize_t len; 256 257 close(fds[1]); 258 259 do { 260 len = read(fds[0], &status, 1); 261 } while (len < 0 && errno == EINTR); 262 263 /* only exit successfully if our child actually wrote 264 * a one-byte zero to our pipe, upon successful init */ 265 exit(len == 1 && status == 0 ? 0 : 1); 266 267 } else if (pid < 0) { 268 exit(1); 269 } 270 271 close(fds[0]); 272 daemon_pipe = fds[1]; 273 qemu_set_cloexec(daemon_pipe); 274 275 setsid(); 276 277 pid = fork(); 278 if (pid > 0) { 279 exit(0); 280 } else if (pid < 0) { 281 exit(1); 282 } 283 umask(027); 284 285 signal(SIGTSTP, SIG_IGN); 286 signal(SIGTTOU, SIG_IGN); 287 signal(SIGTTIN, SIG_IGN); 288 } 289 } 290 291 void os_setup_post(void) 292 { 293 int fd = 0; 294 295 if (daemonize) { 296 if (chdir("/")) { 297 error_report("not able to chdir to /: %s", strerror(errno)); 298 exit(1); 299 } 300 TFR(fd = qemu_open("/dev/null", O_RDWR)); 301 if (fd == -1) { 302 exit(1); 303 } 304 } 305 306 change_root(); 307 change_process_uid(); 308 309 if (daemonize) { 310 uint8_t status = 0; 311 ssize_t len; 312 313 dup2(fd, 0); 314 dup2(fd, 1); 315 /* In case -D is given do not redirect stderr to /dev/null */ 316 if (!qemu_logfile) { 317 dup2(fd, 2); 318 } 319 320 close(fd); 321 322 do { 323 len = write(daemon_pipe, &status, 1); 324 } while (len < 0 && errno == EINTR); 325 if (len != 1) { 326 exit(1); 327 } 328 } 329 } 330 331 void os_set_line_buffering(void) 332 { 333 setvbuf(stdout, NULL, _IOLBF, 0); 334 } 335 336 bool is_daemonized(void) 337 { 338 return daemonize; 339 } 340 341 int os_mlock(void) 342 { 343 #ifdef HAVE_MLOCKALL 344 int ret = 0; 345 346 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 347 if (ret < 0) { 348 error_report("mlockall: %s", strerror(errno)); 349 } 350 351 return ret; 352 #else 353 return -ENOSYS; 354 #endif 355 } 356