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