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 "qemu/osdep.h" 27 #include <sys/wait.h> 28 /*needed for MAP_POPULATE before including qemu-options.h */ 29 #include <pwd.h> 30 #include <grp.h> 31 #include <libgen.h> 32 33 /* Needed early for CONFIG_BSD etc. */ 34 #include "sysemu/sysemu.h" 35 #include "net/slirp.h" 36 #include "qemu-options.h" 37 #include "qemu/error-report.h" 38 #include "qemu/log.h" 39 #include "qemu/cutils.h" 40 41 #ifdef CONFIG_LINUX 42 #include <sys/prctl.h> 43 #endif 44 45 static struct passwd *user_pwd; 46 static const char *chroot_dir; 47 static int daemonize; 48 static int daemon_pipe; 49 50 void os_setup_early_signal_handling(void) 51 { 52 struct sigaction act; 53 sigfillset(&act.sa_mask); 54 act.sa_flags = 0; 55 act.sa_handler = SIG_IGN; 56 sigaction(SIGPIPE, &act, NULL); 57 } 58 59 static void termsig_handler(int signal, siginfo_t *info, void *c) 60 { 61 qemu_system_killed(info->si_signo, info->si_pid); 62 } 63 64 void os_setup_signal_handling(void) 65 { 66 struct sigaction act; 67 68 memset(&act, 0, sizeof(act)); 69 act.sa_sigaction = termsig_handler; 70 act.sa_flags = SA_SIGINFO; 71 sigaction(SIGINT, &act, NULL); 72 sigaction(SIGHUP, &act, NULL); 73 sigaction(SIGTERM, &act, NULL); 74 } 75 76 /* Find a likely location for support files using the location of the binary. 77 For installed binaries this will be "$bindir/../share/qemu". When 78 running from the build tree this will be "$bindir/../pc-bios". */ 79 #define SHARE_SUFFIX "/share/qemu" 80 #define BUILD_SUFFIX "/pc-bios" 81 char *os_find_datadir(void) 82 { 83 char *dir, *exec_dir; 84 char *res; 85 size_t max_len; 86 87 exec_dir = qemu_get_exec_dir(); 88 if (exec_dir == NULL) { 89 return NULL; 90 } 91 dir = g_path_get_dirname(exec_dir); 92 93 max_len = strlen(dir) + 94 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; 95 res = g_malloc0(max_len); 96 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); 97 if (access(res, R_OK)) { 98 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); 99 if (access(res, R_OK)) { 100 g_free(res); 101 res = NULL; 102 } 103 } 104 105 g_free(dir); 106 g_free(exec_dir); 107 return res; 108 } 109 #undef SHARE_SUFFIX 110 #undef BUILD_SUFFIX 111 112 void os_set_proc_name(const char *s) 113 { 114 #if defined(PR_SET_NAME) 115 char name[16]; 116 if (!s) 117 return; 118 pstrcpy(name, sizeof(name), s); 119 /* Could rewrite argv[0] too, but that's a bit more complicated. 120 This simple way is enough for `top'. */ 121 if (prctl(PR_SET_NAME, name)) { 122 perror("unable to change process name"); 123 exit(1); 124 } 125 #else 126 fprintf(stderr, "Change of process name not supported by your OS\n"); 127 exit(1); 128 #endif 129 } 130 131 /* 132 * Parse OS specific command line options. 133 * return 0 if option handled, -1 otherwise 134 */ 135 void os_parse_cmd_args(int index, const char *optarg) 136 { 137 switch (index) { 138 #ifdef CONFIG_SLIRP 139 case QEMU_OPTION_smb: 140 error_report("The -smb option is deprecated. " 141 "Please use '-netdev user,smb=...' instead."); 142 if (net_slirp_smb(optarg) < 0) 143 exit(1); 144 break; 145 #endif 146 case QEMU_OPTION_runas: 147 user_pwd = getpwnam(optarg); 148 if (!user_pwd) { 149 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg); 150 exit(1); 151 } 152 break; 153 case QEMU_OPTION_chroot: 154 chroot_dir = optarg; 155 break; 156 case QEMU_OPTION_daemonize: 157 daemonize = 1; 158 break; 159 #if defined(CONFIG_LINUX) 160 case QEMU_OPTION_enablefips: 161 fips_set_state(true); 162 break; 163 #endif 164 } 165 } 166 167 static void change_process_uid(void) 168 { 169 if (user_pwd) { 170 if (setgid(user_pwd->pw_gid) < 0) { 171 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid); 172 exit(1); 173 } 174 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) { 175 fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n", 176 user_pwd->pw_name, user_pwd->pw_gid); 177 exit(1); 178 } 179 if (setuid(user_pwd->pw_uid) < 0) { 180 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid); 181 exit(1); 182 } 183 if (setuid(0) != -1) { 184 fprintf(stderr, "Dropping privileges failed\n"); 185 exit(1); 186 } 187 } 188 } 189 190 static void change_root(void) 191 { 192 if (chroot_dir) { 193 if (chroot(chroot_dir) < 0) { 194 fprintf(stderr, "chroot failed\n"); 195 exit(1); 196 } 197 if (chdir("/")) { 198 perror("not able to chdir to /"); 199 exit(1); 200 } 201 } 202 203 } 204 205 void os_daemonize(void) 206 { 207 if (daemonize) { 208 pid_t pid; 209 int fds[2]; 210 211 if (pipe(fds) == -1) { 212 exit(1); 213 } 214 215 pid = fork(); 216 if (pid > 0) { 217 uint8_t status; 218 ssize_t len; 219 220 close(fds[1]); 221 222 do { 223 len = read(fds[0], &status, 1); 224 } while (len < 0 && errno == EINTR); 225 226 /* only exit successfully if our child actually wrote 227 * a one-byte zero to our pipe, upon successful init */ 228 exit(len == 1 && status == 0 ? 0 : 1); 229 230 } else if (pid < 0) { 231 exit(1); 232 } 233 234 close(fds[0]); 235 daemon_pipe = fds[1]; 236 qemu_set_cloexec(daemon_pipe); 237 238 setsid(); 239 240 pid = fork(); 241 if (pid > 0) { 242 exit(0); 243 } else if (pid < 0) { 244 exit(1); 245 } 246 umask(027); 247 248 signal(SIGTSTP, SIG_IGN); 249 signal(SIGTTOU, SIG_IGN); 250 signal(SIGTTIN, SIG_IGN); 251 } 252 } 253 254 void os_setup_post(void) 255 { 256 int fd = 0; 257 258 if (daemonize) { 259 if (chdir("/")) { 260 perror("not able to chdir to /"); 261 exit(1); 262 } 263 TFR(fd = qemu_open("/dev/null", O_RDWR)); 264 if (fd == -1) { 265 exit(1); 266 } 267 } 268 269 change_root(); 270 change_process_uid(); 271 272 if (daemonize) { 273 uint8_t status = 0; 274 ssize_t len; 275 276 dup2(fd, 0); 277 dup2(fd, 1); 278 /* In case -D is given do not redirect stderr to /dev/null */ 279 if (!qemu_logfile) { 280 dup2(fd, 2); 281 } 282 283 close(fd); 284 285 do { 286 len = write(daemon_pipe, &status, 1); 287 } while (len < 0 && errno == EINTR); 288 if (len != 1) { 289 exit(1); 290 } 291 } 292 } 293 294 void os_set_line_buffering(void) 295 { 296 setvbuf(stdout, NULL, _IOLBF, 0); 297 } 298 299 int qemu_create_pidfile(const char *filename) 300 { 301 char buffer[128]; 302 int len; 303 int fd; 304 305 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 306 if (fd == -1) { 307 return -1; 308 } 309 if (lockf(fd, F_TLOCK, 0) == -1) { 310 close(fd); 311 return -1; 312 } 313 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid()); 314 if (write(fd, buffer, len) != len) { 315 close(fd); 316 return -1; 317 } 318 319 /* keep pidfile open & locked forever */ 320 return 0; 321 } 322 323 bool is_daemonized(void) 324 { 325 return daemonize; 326 } 327 328 int os_mlock(void) 329 { 330 int ret = 0; 331 332 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 333 if (ret < 0) { 334 perror("mlockall"); 335 } 336 337 return ret; 338 } 339