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