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 #if defined(CONFIG_LINUX) 154 case QEMU_OPTION_enablefips: 155 warn_report("-enable-fips is deprecated, please build QEMU with " 156 "the `libgcrypt` library as the cryptography provider " 157 "to enable FIPS compliance"); 158 fips_set_state(true); 159 break; 160 #endif 161 default: 162 return -1; 163 } 164 165 return 0; 166 } 167 168 static void change_process_uid(void) 169 { 170 assert((user_uid == (uid_t)-1) || user_pwd == NULL); 171 assert((user_uid == (uid_t)-1) == 172 (user_gid == (gid_t)-1)); 173 174 if (user_pwd || user_uid != (uid_t)-1) { 175 gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid; 176 uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid; 177 if (setgid(intended_gid) < 0) { 178 error_report("Failed to setgid(%d)", intended_gid); 179 exit(1); 180 } 181 if (user_pwd) { 182 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 183 error_report("Failed to initgroups(\"%s\", %d)", 184 user_pwd->pw_name, user_pwd->pw_gid); 185 exit(1); 186 } 187 } else { 188 if (setgroups(1, &user_gid) < 0) { 189 error_report("Failed to setgroups(1, [%d])", 190 user_gid); 191 exit(1); 192 } 193 } 194 if (setuid(intended_uid) < 0) { 195 error_report("Failed to setuid(%d)", intended_uid); 196 exit(1); 197 } 198 if (setuid(0) != -1) { 199 error_report("Dropping privileges failed"); 200 exit(1); 201 } 202 } 203 } 204 205 static void change_root(void) 206 { 207 if (chroot_dir) { 208 if (chroot(chroot_dir) < 0) { 209 error_report("chroot failed"); 210 exit(1); 211 } 212 if (chdir("/")) { 213 error_report("not able to chdir to /: %s", strerror(errno)); 214 exit(1); 215 } 216 } 217 218 } 219 220 void os_daemonize(void) 221 { 222 if (daemonize) { 223 pid_t pid; 224 int fds[2]; 225 226 if (pipe(fds) == -1) { 227 exit(1); 228 } 229 230 pid = fork(); 231 if (pid > 0) { 232 uint8_t status; 233 ssize_t len; 234 235 close(fds[1]); 236 237 do { 238 len = read(fds[0], &status, 1); 239 } while (len < 0 && errno == EINTR); 240 241 /* only exit successfully if our child actually wrote 242 * a one-byte zero to our pipe, upon successful init */ 243 exit(len == 1 && status == 0 ? 0 : 1); 244 245 } else if (pid < 0) { 246 exit(1); 247 } 248 249 close(fds[0]); 250 daemon_pipe = fds[1]; 251 qemu_set_cloexec(daemon_pipe); 252 253 setsid(); 254 255 pid = fork(); 256 if (pid > 0) { 257 exit(0); 258 } else if (pid < 0) { 259 exit(1); 260 } 261 umask(027); 262 263 signal(SIGTSTP, SIG_IGN); 264 signal(SIGTTOU, SIG_IGN); 265 signal(SIGTTIN, SIG_IGN); 266 } 267 } 268 269 void os_setup_post(void) 270 { 271 int fd = 0; 272 273 if (daemonize) { 274 if (chdir("/")) { 275 error_report("not able to chdir to /: %s", strerror(errno)); 276 exit(1); 277 } 278 TFR(fd = qemu_open_old("/dev/null", O_RDWR)); 279 if (fd == -1) { 280 exit(1); 281 } 282 } 283 284 change_root(); 285 change_process_uid(); 286 287 if (daemonize) { 288 uint8_t status = 0; 289 ssize_t len; 290 291 dup2(fd, 0); 292 dup2(fd, 1); 293 /* In case -D is given do not redirect stderr to /dev/null */ 294 if (!qemu_logfile) { 295 dup2(fd, 2); 296 } 297 298 close(fd); 299 300 do { 301 len = write(daemon_pipe, &status, 1); 302 } while (len < 0 && errno == EINTR); 303 if (len != 1) { 304 exit(1); 305 } 306 } 307 } 308 309 void os_set_line_buffering(void) 310 { 311 setvbuf(stdout, NULL, _IOLBF, 0); 312 } 313 314 bool is_daemonized(void) 315 { 316 return daemonize; 317 } 318 319 int os_set_daemonize(bool d) 320 { 321 daemonize = d; 322 return 0; 323 } 324 325 int os_mlock(void) 326 { 327 #ifdef HAVE_MLOCKALL 328 int ret = 0; 329 330 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 331 if (ret < 0) { 332 error_report("mlockall: %s", strerror(errno)); 333 } 334 335 return ret; 336 #else 337 return -ENOSYS; 338 #endif 339 } 340