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 <unistd.h> 27 #include <fcntl.h> 28 #include <signal.h> 29 #include <sys/types.h> 30 #include <sys/wait.h> 31 /*needed for MAP_POPULATE before including qemu-options.h */ 32 #include <sys/mman.h> 33 #include <pwd.h> 34 #include <libgen.h> 35 36 /* Needed early for CONFIG_BSD etc. */ 37 #include "config-host.h" 38 #include "sysemu/sysemu.h" 39 #include "net/net.h" 40 #include "qemu-options.h" 41 42 #ifdef CONFIG_LINUX 43 #include <sys/prctl.h> 44 #include <sys/syscall.h> 45 #endif 46 47 #ifdef CONFIG_EVENTFD 48 #include <sys/eventfd.h> 49 #endif 50 51 static struct passwd *user_pwd; 52 static const char *chroot_dir; 53 static int daemonize; 54 static int fds[2]; 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) 66 { 67 qemu_system_shutdown_request(); 68 } 69 70 static void sigchld_handler(int signal) 71 { 72 waitpid(-1, NULL, WNOHANG); 73 } 74 75 void os_setup_signal_handling(void) 76 { 77 struct sigaction act; 78 79 memset(&act, 0, sizeof(act)); 80 act.sa_handler = termsig_handler; 81 sigaction(SIGINT, &act, NULL); 82 sigaction(SIGHUP, &act, NULL); 83 sigaction(SIGTERM, &act, NULL); 84 85 act.sa_handler = sigchld_handler; 86 act.sa_flags = SA_NOCLDSTOP; 87 sigaction(SIGCHLD, &act, NULL); 88 } 89 90 /* Find a likely location for support files using the location of the binary. 91 For installed binaries this will be "$bindir/../share/qemu". When 92 running from the build tree this will be "$bindir/../pc-bios". */ 93 #define SHARE_SUFFIX "/share/qemu" 94 #define BUILD_SUFFIX "/pc-bios" 95 char *os_find_datadir(const char *argv0) 96 { 97 char *dir; 98 char *p = NULL; 99 char *res; 100 char buf[PATH_MAX]; 101 size_t max_len; 102 103 #if defined(__linux__) 104 { 105 int len; 106 len = readlink("/proc/self/exe", buf, sizeof(buf) - 1); 107 if (len > 0) { 108 buf[len] = 0; 109 p = buf; 110 } 111 } 112 #elif defined(__FreeBSD__) 113 { 114 static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1}; 115 size_t len = sizeof(buf) - 1; 116 117 *buf = '\0'; 118 if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) && 119 *buf) { 120 buf[sizeof(buf) - 1] = '\0'; 121 p = buf; 122 } 123 } 124 #endif 125 /* If we don't have any way of figuring out the actual executable 126 location then try argv[0]. */ 127 if (!p) { 128 p = realpath(argv0, buf); 129 if (!p) { 130 return NULL; 131 } 132 } 133 dir = dirname(p); 134 dir = dirname(dir); 135 136 max_len = strlen(dir) + 137 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; 138 res = g_malloc0(max_len); 139 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); 140 if (access(res, R_OK)) { 141 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); 142 if (access(res, R_OK)) { 143 g_free(res); 144 res = NULL; 145 } 146 } 147 148 return res; 149 } 150 #undef SHARE_SUFFIX 151 #undef BUILD_SUFFIX 152 153 void os_set_proc_name(const char *s) 154 { 155 #if defined(PR_SET_NAME) 156 char name[16]; 157 if (!s) 158 return; 159 name[sizeof(name) - 1] = 0; 160 strncpy(name, s, sizeof(name)); 161 /* Could rewrite argv[0] too, but that's a bit more complicated. 162 This simple way is enough for `top'. */ 163 if (prctl(PR_SET_NAME, name)) { 164 perror("unable to change process name"); 165 exit(1); 166 } 167 #else 168 fprintf(stderr, "Change of process name not supported by your OS\n"); 169 exit(1); 170 #endif 171 } 172 173 /* 174 * Parse OS specific command line options. 175 * return 0 if option handled, -1 otherwise 176 */ 177 void os_parse_cmd_args(int index, const char *optarg) 178 { 179 switch (index) { 180 #ifdef CONFIG_SLIRP 181 case QEMU_OPTION_smb: 182 #if 1 183 net_slirp_smb(optarg); 184 #else 185 if (net_slirp_smb(optarg) < 0) 186 exit(1); 187 #endif 188 break; 189 #endif 190 case QEMU_OPTION_runas: 191 user_pwd = getpwnam(optarg); 192 if (!user_pwd) { 193 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg); 194 exit(1); 195 } 196 break; 197 case QEMU_OPTION_chroot: 198 chroot_dir = optarg; 199 break; 200 case QEMU_OPTION_daemonize: 201 daemonize = 1; 202 break; 203 } 204 return; 205 } 206 207 static void change_process_uid(void) 208 { 209 if (user_pwd) { 210 if (setgid(user_pwd->pw_gid) < 0) { 211 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid); 212 exit(1); 213 } 214 if (setuid(user_pwd->pw_uid) < 0) { 215 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid); 216 exit(1); 217 } 218 if (setuid(0) != -1) { 219 fprintf(stderr, "Dropping privileges failed\n"); 220 exit(1); 221 } 222 } 223 } 224 225 static void change_root(void) 226 { 227 if (chroot_dir) { 228 if (chroot(chroot_dir) < 0) { 229 fprintf(stderr, "chroot failed\n"); 230 exit(1); 231 } 232 if (chdir("/")) { 233 perror("not able to chdir to /"); 234 exit(1); 235 } 236 } 237 238 } 239 240 void os_daemonize(void) 241 { 242 if (daemonize) { 243 pid_t pid; 244 245 if (pipe(fds) == -1) 246 exit(1); 247 248 pid = fork(); 249 if (pid > 0) { 250 uint8_t status; 251 ssize_t len; 252 253 close(fds[1]); 254 255 again: 256 len = read(fds[0], &status, 1); 257 if (len == -1 && (errno == EINTR)) 258 goto again; 259 260 if (len != 1) 261 exit(1); 262 else if (status == 1) { 263 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno)); 264 exit(1); 265 } else 266 exit(0); 267 } else if (pid < 0) 268 exit(1); 269 270 close(fds[0]); 271 qemu_set_cloexec(fds[1]); 272 273 setsid(); 274 275 pid = fork(); 276 if (pid > 0) 277 exit(0); 278 else if (pid < 0) 279 exit(1); 280 281 umask(027); 282 283 signal(SIGTSTP, SIG_IGN); 284 signal(SIGTTOU, SIG_IGN); 285 signal(SIGTTIN, SIG_IGN); 286 } 287 } 288 289 void os_setup_post(void) 290 { 291 int fd = 0; 292 293 if (daemonize) { 294 uint8_t status = 0; 295 ssize_t len; 296 297 again1: 298 len = write(fds[1], &status, 1); 299 if (len == -1 && (errno == EINTR)) 300 goto again1; 301 302 if (len != 1) 303 exit(1); 304 305 if (chdir("/")) { 306 perror("not able to chdir to /"); 307 exit(1); 308 } 309 TFR(fd = qemu_open("/dev/null", O_RDWR)); 310 if (fd == -1) 311 exit(1); 312 } 313 314 change_root(); 315 change_process_uid(); 316 317 if (daemonize) { 318 dup2(fd, 0); 319 dup2(fd, 1); 320 dup2(fd, 2); 321 322 close(fd); 323 } 324 } 325 326 void os_pidfile_error(void) 327 { 328 if (daemonize) { 329 uint8_t status = 1; 330 if (write(fds[1], &status, 1) != 1) { 331 perror("daemonize. Writing to pipe\n"); 332 } 333 } else 334 fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno)); 335 } 336 337 void os_set_line_buffering(void) 338 { 339 setvbuf(stdout, NULL, _IOLBF, 0); 340 } 341 342 /* 343 * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set. 344 */ 345 int qemu_eventfd(int fds[2]) 346 { 347 #ifdef CONFIG_EVENTFD 348 int ret; 349 350 ret = eventfd(0, 0); 351 if (ret >= 0) { 352 fds[0] = ret; 353 qemu_set_cloexec(ret); 354 if ((fds[1] = dup(ret)) == -1) { 355 close(ret); 356 return -1; 357 } 358 qemu_set_cloexec(fds[1]); 359 return 0; 360 } 361 362 if (errno != ENOSYS) { 363 return -1; 364 } 365 #endif 366 367 return qemu_pipe(fds); 368 } 369 370 int qemu_create_pidfile(const char *filename) 371 { 372 char buffer[128]; 373 int len; 374 int fd; 375 376 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 377 if (fd == -1) { 378 return -1; 379 } 380 if (lockf(fd, F_TLOCK, 0) == -1) { 381 return -1; 382 } 383 len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid()); 384 if (write(fd, buffer, len) != len) { 385 return -1; 386 } 387 388 return 0; 389 } 390
