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 "net/slirp.h" 34 #include "qemu/qemu-options.h" 35 #include "qemu/error-report.h" 36 #include "qemu/log.h" 37 #include "sysemu/runstate.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 void os_set_proc_name(const char *s) 83 { 84 #if defined(PR_SET_NAME) 85 char name[16]; 86 if (!s) 87 return; 88 pstrcpy(name, sizeof(name), s); 89 /* Could rewrite argv[0] too, but that's a bit more complicated. 90 This simple way is enough for `top'. */ 91 if (prctl(PR_SET_NAME, name)) { 92 error_report("unable to change process name: %s", strerror(errno)); 93 exit(1); 94 } 95 #else 96 error_report("Change of process name not supported by your OS"); 97 exit(1); 98 #endif 99 } 100 101 102 static bool os_parse_runas_uid_gid(const char *optarg) 103 { 104 unsigned long lv; 105 const char *ep; 106 uid_t got_uid; 107 gid_t got_gid; 108 int rc; 109 110 rc = qemu_strtoul(optarg, &ep, 0, &lv); 111 got_uid = lv; /* overflow here is ID in C99 */ 112 if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) { 113 return false; 114 } 115 116 rc = qemu_strtoul(ep + 1, 0, 0, &lv); 117 got_gid = lv; /* overflow here is ID in C99 */ 118 if (rc || got_gid != lv || got_gid == (gid_t)-1) { 119 return false; 120 } 121 122 user_pwd = NULL; 123 user_uid = got_uid; 124 user_gid = got_gid; 125 return true; 126 } 127 128 /* 129 * Parse OS specific command line options. 130 * return 0 if option handled, -1 otherwise 131 */ 132 int os_parse_cmd_args(int index, const char *optarg) 133 { 134 switch (index) { 135 case QEMU_OPTION_runas: 136 user_pwd = getpwnam(optarg); 137 if (user_pwd) { 138 user_uid = -1; 139 user_gid = -1; 140 } else if (!os_parse_runas_uid_gid(optarg)) { 141 error_report("User \"%s\" doesn't exist" 142 " (and is not <uid>:<gid>)", 143 optarg); 144 exit(1); 145 } 146 break; 147 case QEMU_OPTION_chroot: 148 chroot_dir = optarg; 149 break; 150 case QEMU_OPTION_daemonize: 151 daemonize = 1; 152 break; 153 default: 154 return -1; 155 } 156 157 return 0; 158 } 159 160 static void change_process_uid(void) 161 { 162 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 163 assert((user_uid == (uid_t)-1) == 164 (user_gid == (gid_t)-1)); 165 166 if (user_pwd || user_uid != (uid_t)-1) { 167 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 168 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 169 if (setgid(intended_gid) < 0) { 170 error_report("Failed to setgid(%d)", intended_gid); 171 exit(1); 172 } 173 if (user_pwd) { 174 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 175 error_report("Failed to initgroups(\"%s\", %d)", 176 user_pwd->pw_name, user_pwd->pw_gid); 177 exit(1); 178 } 179 } else { 180 if (setgroups(1, &user_gid) < 0) { 181 error_report("Failed to setgroups(1, [%d])", 182 user_gid); 183 exit(1); 184 } 185 } 186 if (setuid(intended_uid) < 0) { 187 error_report("Failed to setuid(%d)", intended_uid); 188 exit(1); 189 } 190 if (setuid(0) != -1) { 191 error_report("Dropping privileges failed"); 192 exit(1); 193 } 194 } 195 } 196 197 static void change_root(void) 198 { 199 if (chroot_dir) { 200 if (chroot(chroot_dir) < 0) { 201 error_report("chroot failed"); 202 exit(1); 203 } 204 if (chdir("/")) { 205 error_report("not able to chdir to /: %s", strerror(errno)); 206 exit(1); 207 } 208 } 209 210 } 211 212 void os_daemonize(void) 213 { 214 if (daemonize) { 215 pid_t pid; 216 int fds[2]; 217 218 if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { 219 exit(1); 220 } 221 222 pid = fork(); 223 if (pid > 0) { 224 uint8_t status; 225 ssize_t len; 226 227 close(fds[1]); 228 229 do { 230 len = read(fds[0], &status, 1); 231 } while (len < 0 && errno == EINTR); 232 233 /* only exit successfully if our child actually wrote 234 * a one-byte zero to our pipe, upon successful init */ 235 exit(len == 1 && status == 0 ? 0 : 1); 236 237 } else if (pid < 0) { 238 exit(1); 239 } 240 241 close(fds[0]); 242 daemon_pipe = fds[1]; 243 244 setsid(); 245 246 pid = fork(); 247 if (pid > 0) { 248 exit(0); 249 } else if (pid < 0) { 250 exit(1); 251 } 252 umask(027); 253 254 signal(SIGTSTP, SIG_IGN); 255 signal(SIGTTOU, SIG_IGN); 256 signal(SIGTTIN, SIG_IGN); 257 } 258 } 259 260 void os_setup_post(void) 261 { 262 int fd = 0; 263 264 if (daemonize) { 265 if (chdir("/")) { 266 error_report("not able to chdir to /: %s", strerror(errno)); 267 exit(1); 268 } 269 TFR(fd = qemu_open_old("/dev/null", O_RDWR)); 270 if (fd == -1) { 271 exit(1); 272 } 273 } 274 275 change_root(); 276 change_process_uid(); 277 278 if (daemonize) { 279 uint8_t status = 0; 280 ssize_t len; 281 282 dup2(fd, 0); 283 dup2(fd, 1); 284 /* In case -D is given do not redirect stderr to /dev/null */ 285 if (!qemu_log_enabled()) { 286 dup2(fd, 2); 287 } 288 289 close(fd); 290 291 do { 292 len = write(daemon_pipe, &status, 1); 293 } while (len < 0 && errno == EINTR); 294 if (len != 1) { 295 exit(1); 296 } 297 } 298 } 299 300 void os_set_line_buffering(void) 301 { 302 setvbuf(stdout, NULL, _IOLBF, 0); 303 } 304 305 bool is_daemonized(void) 306 { 307 return daemonize; 308 } 309 310 int os_set_daemonize(bool d) 311 { 312 daemonize = d; 313 return 0; 314 } 315 316 int os_mlock(void) 317 { 318 #ifdef HAVE_MLOCKALL 319 int ret = 0; 320 321 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 322 if (ret < 0) { 323 error_report("mlockall: %s", strerror(errno)); 324 } 325 326 return ret; 327 #else 328 return -ENOSYS; 329 #endif 330 } 331