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 <grp.h> 35 #include <libgen.h> 36 37 /* Needed early for CONFIG_BSD etc. */ 38 #include "config-host.h" 39 #include "sysemu.h" 40 #include "net/slirp.h" 41 #include "qemu-options.h" 42 43 #ifdef CONFIG_LINUX 44 #include <sys/prctl.h> 45 #endif 46 47 static struct passwd *user_pwd; 48 static const char *chroot_dir; 49 static int daemonize; 50 static int fds[2]; 51 52 void os_setup_early_signal_handling(void) 53 { 54 struct sigaction act; 55 sigfillset(&act.sa_mask); 56 act.sa_flags = 0; 57 act.sa_handler = SIG_IGN; 58 sigaction(SIGPIPE, &act, NULL); 59 } 60 61 static void termsig_handler(int signal, siginfo_t *info, void *c) 62 { 63 qemu_system_killed(info->si_signo, info->si_pid); 64 } 65 66 void os_setup_signal_handling(void) 67 { 68 struct sigaction act; 69 70 memset(&act, 0, sizeof(act)); 71 act.sa_sigaction = termsig_handler; 72 act.sa_flags = SA_SIGINFO; 73 sigaction(SIGINT, &act, NULL); 74 sigaction(SIGHUP, &act, NULL); 75 sigaction(SIGTERM, &act, NULL); 76 } 77 78 /* Find a likely location for support files using the location of the binary. 79 For installed binaries this will be "$bindir/../share/qemu". When 80 running from the build tree this will be "$bindir/../pc-bios". */ 81 #define SHARE_SUFFIX "/share/qemu" 82 #define BUILD_SUFFIX "/pc-bios" 83 char *os_find_datadir(const char *argv0) 84 { 85 char *dir; 86 char *p = NULL; 87 char *res; 88 char buf[PATH_MAX]; 89 size_t max_len; 90 91 #if defined(__linux__) 92 { 93 int len; 94 len = readlink("/proc/self/exe", buf, sizeof(buf) - 1); 95 if (len > 0) { 96 buf[len] = 0; 97 p = buf; 98 } 99 } 100 #elif defined(__FreeBSD__) 101 { 102 static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1}; 103 size_t len = sizeof(buf) - 1; 104 105 *buf = '\0'; 106 if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) && 107 *buf) { 108 buf[sizeof(buf) - 1] = '\0'; 109 p = buf; 110 } 111 } 112 #endif 113 /* If we don't have any way of figuring out the actual executable 114 location then try argv[0]. */ 115 if (!p) { 116 p = realpath(argv0, buf); 117 if (!p) { 118 return NULL; 119 } 120 } 121 dir = dirname(p); 122 dir = dirname(dir); 123 124 max_len = strlen(dir) + 125 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; 126 res = g_malloc0(max_len); 127 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); 128 if (access(res, R_OK)) { 129 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); 130 if (access(res, R_OK)) { 131 g_free(res); 132 res = NULL; 133 } 134 } 135 136 return res; 137 } 138 #undef SHARE_SUFFIX 139 #undef BUILD_SUFFIX 140 141 void os_set_proc_name(const char *s) 142 { 143 #if defined(PR_SET_NAME) 144 char name[16]; 145 if (!s) 146 return; 147 name[sizeof(name) - 1] = 0; 148 strncpy(name, s, sizeof(name)); 149 /* Could rewrite argv[0] too, but that's a bit more complicated. 150 This simple way is enough for `top'. */ 151 if (prctl(PR_SET_NAME, name)) { 152 perror("unable to change process name"); 153 exit(1); 154 } 155 #else 156 fprintf(stderr, "Change of process name not supported by your OS\n"); 157 exit(1); 158 #endif 159 } 160 161 /* 162 * Parse OS specific command line options. 163 * return 0 if option handled, -1 otherwise 164 */ 165 void os_parse_cmd_args(int index, const char *optarg) 166 { 167 switch (index) { 168 #ifdef CONFIG_SLIRP 169 case QEMU_OPTION_smb: 170 if (net_slirp_smb(optarg) < 0) 171 exit(1); 172 break; 173 #endif 174 case QEMU_OPTION_runas: 175 user_pwd = getpwnam(optarg); 176 if (!user_pwd) { 177 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg); 178 exit(1); 179 } 180 break; 181 case QEMU_OPTION_chroot: 182 chroot_dir = optarg; 183 break; 184 case QEMU_OPTION_daemonize: 185 daemonize = 1; 186 break; 187 } 188 return; 189 } 190 191 static void change_process_uid(void) 192 { 193 if (user_pwd) { 194 if (setgid(user_pwd->pw_gid) < 0) { 195 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid); 196 exit(1); 197 } 198 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 199 fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n", 200 user_pwd->pw_name, user_pwd->pw_gid); 201 exit(1); 202 } 203 if (setuid(user_pwd->pw_uid) < 0) { 204 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid); 205 exit(1); 206 } 207 if (setuid(0) != -1) { 208 fprintf(stderr, "Dropping privileges failed\n"); 209 exit(1); 210 } 211 } 212 } 213 214 static void change_root(void) 215 { 216 if (chroot_dir) { 217 if (chroot(chroot_dir) < 0) { 218 fprintf(stderr, "chroot failed\n"); 219 exit(1); 220 } 221 if (chdir("/")) { 222 perror("not able to chdir to /"); 223 exit(1); 224 } 225 } 226 227 } 228 229 void os_daemonize(void) 230 { 231 if (daemonize) { 232 pid_t pid; 233 234 if (pipe(fds) == -1) 235 exit(1); 236 237 pid = fork(); 238 if (pid > 0) { 239 uint8_t status; 240 ssize_t len; 241 242 close(fds[1]); 243 244 again: 245 len = read(fds[0], &status, 1); 246 if (len == -1 && (errno == EINTR)) 247 goto again; 248 249 if (len != 1) 250 exit(1); 251 else if (status == 1) { 252 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno)); 253 exit(1); 254 } else 255 exit(0); 256 } else if (pid < 0) 257 exit(1); 258 259 close(fds[0]); 260 qemu_set_cloexec(fds[1]); 261 262 setsid(); 263 264 pid = fork(); 265 if (pid > 0) 266 exit(0); 267 else if (pid < 0) 268 exit(1); 269 270 umask(027); 271 272 signal(SIGTSTP, SIG_IGN); 273 signal(SIGTTOU, SIG_IGN); 274 signal(SIGTTIN, SIG_IGN); 275 } 276 } 277 278 void os_setup_post(void) 279 { 280 int fd = 0; 281 282 if (daemonize) { 283 uint8_t status = 0; 284 ssize_t len; 285 286 again1: 287 len = write(fds[1], &status, 1); 288 if (len == -1 && (errno == EINTR)) 289 goto again1; 290 291 if (len != 1) 292 exit(1); 293 294 if (chdir("/")) { 295 perror("not able to chdir to /"); 296 exit(1); 297 } 298 TFR(fd = qemu_open("/dev/null", O_RDWR)); 299 if (fd == -1) 300 exit(1); 301 } 302 303 change_root(); 304 change_process_uid(); 305 306 if (daemonize) { 307 dup2(fd, 0); 308 dup2(fd, 1); 309 dup2(fd, 2); 310 311 close(fd); 312 } 313 } 314 315 void os_pidfile_error(void) 316 { 317 if (daemonize) { 318 uint8_t status = 1; 319 if (write(fds[1], &status, 1) != 1) { 320 perror("daemonize. Writing to pipe\n"); 321 } 322 } else 323 fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno)); 324 } 325 326 void os_set_line_buffering(void) 327 { 328 setvbuf(stdout, NULL, _IOLBF, 0); 329 } 330 331 int qemu_create_pidfile(const char *filename) 332 { 333 char buffer[128]; 334 int len; 335 int fd; 336 337 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 338 if (fd == -1) { 339 return -1; 340 } 341 if (lockf(fd, F_TLOCK, 0) == -1) { 342 close(fd); 343 return -1; 344 } 345 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid()); 346 if (write(fd, buffer, len) != len) { 347 close(fd); 348 return -1; 349 } 350 351 /* keep pidfile open & locked forever */ 352 return 0; 353 } 354