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