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 #endif 45 46 #ifdef CONFIG_EVENTFD 47 #include <sys/eventfd.h> 48 #endif 49 50 static struct passwd *user_pwd; 51 static const char *chroot_dir; 52 static int daemonize; 53 static int fds[2]; 54 55 void os_setup_early_signal_handling(void) 56 { 57 struct sigaction act; 58 sigfillset(&act.sa_mask); 59 act.sa_flags = 0; 60 act.sa_handler = SIG_IGN; 61 sigaction(SIGPIPE, &act, NULL); 62 } 63 64 static void termsig_handler(int signal) 65 { 66 qemu_system_shutdown_request(); 67 } 68 69 static void sigchld_handler(int signal) 70 { 71 waitpid(-1, NULL, WNOHANG); 72 } 73 74 void os_setup_signal_handling(void) 75 { 76 struct sigaction act; 77 78 memset(&act, 0, sizeof(act)); 79 act.sa_handler = termsig_handler; 80 sigaction(SIGINT, &act, NULL); 81 sigaction(SIGHUP, &act, NULL); 82 sigaction(SIGTERM, &act, NULL); 83 84 act.sa_handler = sigchld_handler; 85 act.sa_flags = SA_NOCLDSTOP; 86 sigaction(SIGCHLD, &act, NULL); 87 } 88 89 /* Find a likely location for support files using the location of the binary. 90 For installed binaries this will be "$bindir/../share/qemu". When 91 running from the build tree this will be "$bindir/../pc-bios". */ 92 #define SHARE_SUFFIX "/share/qemu" 93 #define BUILD_SUFFIX "/pc-bios" 94 char *os_find_datadir(const char *argv0) 95 { 96 char *dir; 97 char *p = NULL; 98 char *res; 99 char buf[PATH_MAX]; 100 size_t max_len; 101 102 #if defined(__linux__) 103 { 104 int len; 105 len = readlink("/proc/self/exe", buf, sizeof(buf) - 1); 106 if (len > 0) { 107 buf[len] = 0; 108 p = buf; 109 } 110 } 111 #elif defined(__FreeBSD__) 112 { 113 static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1}; 114 size_t len = sizeof(buf) - 1; 115 116 *buf = '\0'; 117 if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) && 118 *buf) { 119 buf[sizeof(buf) - 1] = '\0'; 120 p = buf; 121 } 122 } 123 #endif 124 /* If we don't have any way of figuring out the actual executable 125 location then try argv[0]. */ 126 if (!p) { 127 p = realpath(argv0, buf); 128 if (!p) { 129 return NULL; 130 } 131 } 132 dir = dirname(p); 133 dir = dirname(dir); 134 135 max_len = strlen(dir) + 136 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; 137 res = qemu_mallocz(max_len); 138 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); 139 if (access(res, R_OK)) { 140 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); 141 if (access(res, R_OK)) { 142 qemu_free(res); 143 res = NULL; 144 } 145 } 146 147 return res; 148 } 149 #undef SHARE_SUFFIX 150 #undef BUILD_SUFFIX 151 152 void os_set_proc_name(const char *s) 153 { 154 #if defined(PR_SET_NAME) 155 char name[16]; 156 if (!s) 157 return; 158 name[sizeof(name) - 1] = 0; 159 strncpy(name, s, sizeof(name)); 160 /* Could rewrite argv[0] too, but that's a bit more complicated. 161 This simple way is enough for `top'. */ 162 if (prctl(PR_SET_NAME, name)) { 163 perror("unable to change process name"); 164 exit(1); 165 } 166 #else 167 fprintf(stderr, "Change of process name not supported by your OS\n"); 168 exit(1); 169 #endif 170 } 171 172 /* 173 * Parse OS specific command line options. 174 * return 0 if option handled, -1 otherwise 175 */ 176 void os_parse_cmd_args(int index, const char *optarg) 177 { 178 switch (index) { 179 #ifdef CONFIG_SLIRP 180 case QEMU_OPTION_smb: 181 if (net_slirp_smb(optarg) < 0) 182 exit(1); 183 break; 184 #endif 185 case QEMU_OPTION_runas: 186 user_pwd = getpwnam(optarg); 187 if (!user_pwd) { 188 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg); 189 exit(1); 190 } 191 break; 192 case QEMU_OPTION_chroot: 193 chroot_dir = optarg; 194 break; 195 case QEMU_OPTION_daemonize: 196 daemonize = 1; 197 break; 198 } 199 return; 200 } 201 202 static void change_process_uid(void) 203 { 204 if (user_pwd) { 205 if (setgid(user_pwd->pw_gid) < 0) { 206 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid); 207 exit(1); 208 } 209 if (setuid(user_pwd->pw_uid) < 0) { 210 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid); 211 exit(1); 212 } 213 if (setuid(0) != -1) { 214 fprintf(stderr, "Dropping privileges failed\n"); 215 exit(1); 216 } 217 } 218 } 219 220 static void change_root(void) 221 { 222 if (chroot_dir) { 223 if (chroot(chroot_dir) < 0) { 224 fprintf(stderr, "chroot failed\n"); 225 exit(1); 226 } 227 if (chdir("/")) { 228 perror("not able to chdir to /"); 229 exit(1); 230 } 231 } 232 233 } 234 235 void os_daemonize(void) 236 { 237 if (daemonize) { 238 pid_t pid; 239 240 if (pipe(fds) == -1) 241 exit(1); 242 243 pid = fork(); 244 if (pid > 0) { 245 uint8_t status; 246 ssize_t len; 247 248 close(fds[1]); 249 250 again: 251 len = read(fds[0], &status, 1); 252 if (len == -1 && (errno == EINTR)) 253 goto again; 254 255 if (len != 1) 256 exit(1); 257 else if (status == 1) { 258 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno)); 259 exit(1); 260 } else 261 exit(0); 262 } else if (pid < 0) 263 exit(1); 264 265 close(fds[0]); 266 qemu_set_cloexec(fds[1]); 267 268 setsid(); 269 270 pid = fork(); 271 if (pid > 0) 272 exit(0); 273 else if (pid < 0) 274 exit(1); 275 276 umask(027); 277 278 signal(SIGTSTP, SIG_IGN); 279 signal(SIGTTOU, SIG_IGN); 280 signal(SIGTTIN, SIG_IGN); 281 } 282 } 283 284 void os_setup_post(void) 285 { 286 int fd = 0; 287 288 if (daemonize) { 289 uint8_t status = 0; 290 ssize_t len; 291 292 again1: 293 len = write(fds[1], &status, 1); 294 if (len == -1 && (errno == EINTR)) 295 goto again1; 296 297 if (len != 1) 298 exit(1); 299 300 if (chdir("/")) { 301 perror("not able to chdir to /"); 302 exit(1); 303 } 304 TFR(fd = qemu_open("/dev/null", O_RDWR)); 305 if (fd == -1) 306 exit(1); 307 } 308 309 change_root(); 310 change_process_uid(); 311 312 if (daemonize) { 313 dup2(fd, 0); 314 dup2(fd, 1); 315 dup2(fd, 2); 316 317 close(fd); 318 } 319 } 320 321 void os_pidfile_error(void) 322 { 323 if (daemonize) { 324 uint8_t status = 1; 325 if (write(fds[1], &status, 1) != 1) { 326 perror("daemonize. Writing to pipe\n"); 327 } 328 } else 329 fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno)); 330 } 331 332 void os_set_line_buffering(void) 333 { 334 setvbuf(stdout, NULL, _IOLBF, 0); 335 } 336 337 /* 338 * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set. 339 */ 340 int qemu_eventfd(int fds[2]) 341 { 342 #ifdef CONFIG_EVENTFD 343 int ret; 344 345 ret = eventfd(0, 0); 346 if (ret >= 0) { 347 fds[0] = ret; 348 qemu_set_cloexec(ret); 349 if ((fds[1] = dup(ret)) == -1) { 350 close(ret); 351 return -1; 352 } 353 qemu_set_cloexec(fds[1]); 354 return 0; 355 } 356 357 if (errno != ENOSYS) { 358 return -1; 359 } 360 #endif 361 362 return qemu_pipe(fds); 363 } 364 365 int qemu_create_pidfile(const char *filename) 366 { 367 char buffer[128]; 368 int len; 369 int fd; 370 371 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 372 if (fd == -1) { 373 return -1; 374 } 375 if (lockf(fd, F_TLOCK, 0) == -1) { 376 return -1; 377 } 378 len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid()); 379 if (write(fd, buffer, len) != len) { 380 return -1; 381 } 382 383 return 0; 384 } 385