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/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 #ifdef __FreeBSD__ 48 #include <sys/sysctl.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 = g_malloc0(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 g_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 pstrcpy(name, sizeof(name), s); 152 /* Could rewrite argv[0] too, but that's a bit more complicated. 153 This simple way is enough for `top'. */ 154 if (prctl(PR_SET_NAME, name)) { 155 perror("unable to change process name"); 156 exit(1); 157 } 158 #else 159 fprintf(stderr, "Change of process name not supported by your OS\n"); 160 exit(1); 161 #endif 162 } 163 164 /* 165 * Parse OS specific command line options. 166 * return 0 if option handled, -1 otherwise 167 */ 168 void os_parse_cmd_args(int index, const char *optarg) 169 { 170 switch (index) { 171 #ifdef CONFIG_SLIRP 172 case QEMU_OPTION_smb: 173 if (net_slirp_smb(optarg) < 0) 174 exit(1); 175 break; 176 #endif 177 case QEMU_OPTION_runas: 178 user_pwd = getpwnam(optarg); 179 if (!user_pwd) { 180 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg); 181 exit(1); 182 } 183 break; 184 case QEMU_OPTION_chroot: 185 chroot_dir = optarg; 186 break; 187 case QEMU_OPTION_daemonize: 188 daemonize = 1; 189 break; 190 #if defined(CONFIG_LINUX) 191 case QEMU_OPTION_enablefips: 192 fips_set_state(true); 193 break; 194 #endif 195 } 196 } 197 198 static void change_process_uid(void) 199 { 200 if (user_pwd) { 201 if (setgid(user_pwd->pw_gid) < 0) { 202 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid); 203 exit(1); 204 } 205 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 206 fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n", 207 user_pwd->pw_name, user_pwd->pw_gid); 208 exit(1); 209 } 210 if (setuid(user_pwd->pw_uid) < 0) { 211 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid); 212 exit(1); 213 } 214 if (setuid(0) != -1) { 215 fprintf(stderr, "Dropping privileges failed\n"); 216 exit(1); 217 } 218 } 219 } 220 221 static void change_root(void) 222 { 223 if (chroot_dir) { 224 if (chroot(chroot_dir) < 0) { 225 fprintf(stderr, "chroot failed\n"); 226 exit(1); 227 } 228 if (chdir("/")) { 229 perror("not able to chdir to /"); 230 exit(1); 231 } 232 } 233 234 } 235 236 void os_daemonize(void) 237 { 238 if (daemonize) { 239 pid_t pid; 240 241 if (pipe(fds) == -1) 242 exit(1); 243 244 pid = fork(); 245 if (pid > 0) { 246 uint8_t status; 247 ssize_t len; 248 249 close(fds[1]); 250 251 again: 252 len = read(fds[0], &status, 1); 253 if (len == -1 && (errno == EINTR)) 254 goto again; 255 256 if (len != 1) 257 exit(1); 258 else if (status == 1) { 259 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno)); 260 exit(1); 261 } else 262 exit(0); 263 } else if (pid < 0) 264 exit(1); 265 266 close(fds[0]); 267 qemu_set_cloexec(fds[1]); 268 269 setsid(); 270 271 pid = fork(); 272 if (pid > 0) 273 exit(0); 274 else if (pid < 0) 275 exit(1); 276 277 umask(027); 278 279 signal(SIGTSTP, SIG_IGN); 280 signal(SIGTTOU, SIG_IGN); 281 signal(SIGTTIN, SIG_IGN); 282 } 283 } 284 285 void os_setup_post(void) 286 { 287 int fd = 0; 288 289 if (daemonize) { 290 uint8_t status = 0; 291 ssize_t len; 292 293 again1: 294 len = write(fds[1], &status, 1); 295 if (len == -1 && (errno == EINTR)) 296 goto again1; 297 298 if (len != 1) 299 exit(1); 300 301 if (chdir("/")) { 302 perror("not able to chdir to /"); 303 exit(1); 304 } 305 TFR(fd = qemu_open("/dev/null", O_RDWR)); 306 if (fd == -1) 307 exit(1); 308 } 309 310 change_root(); 311 change_process_uid(); 312 313 if (daemonize) { 314 dup2(fd, 0); 315 dup2(fd, 1); 316 dup2(fd, 2); 317 318 close(fd); 319 } 320 } 321 322 void os_pidfile_error(void) 323 { 324 if (daemonize) { 325 uint8_t status = 1; 326 if (write(fds[1], &status, 1) != 1) { 327 perror("daemonize. Writing to pipe\n"); 328 } 329 } else 330 fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno)); 331 } 332 333 void os_set_line_buffering(void) 334 { 335 setvbuf(stdout, NULL, _IOLBF, 0); 336 } 337 338 int qemu_create_pidfile(const char *filename) 339 { 340 char buffer[128]; 341 int len; 342 int fd; 343 344 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 345 if (fd == -1) { 346 return -1; 347 } 348 if (lockf(fd, F_TLOCK, 0) == -1) { 349 close(fd); 350 return -1; 351 } 352 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid()); 353 if (write(fd, buffer, len) != len) { 354 close(fd); 355 return -1; 356 } 357 358 /* keep pidfile open & locked forever */ 359 return 0; 360 } 361 362 bool is_daemonized(void) 363 { 364 return daemonize; 365 } 366