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