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 static struct passwd *user_pwd; 48 static const char *chroot_dir; 49 static int daemonize; 50 static int daemon_pipe; 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(void) 84 { 85 char *dir, *exec_dir; 86 char *res; 87 size_t max_len; 88 89 exec_dir = qemu_get_exec_dir(); 90 if (exec_dir == NULL) { 91 return NULL; 92 } 93 dir = dirname(exec_dir); 94 95 max_len = strlen(dir) + 96 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1; 97 res = g_malloc0(max_len); 98 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX); 99 if (access(res, R_OK)) { 100 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX); 101 if (access(res, R_OK)) { 102 g_free(res); 103 res = NULL; 104 } 105 } 106 107 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 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 dup2(fd, 2); 278 279 close(fd); 280 281 do { 282 len = write(daemon_pipe, &status, 1); 283 } while (len < 0 && errno == EINTR); 284 if (len != 1) { 285 exit(1); 286 } 287 } 288 } 289 290 void os_set_line_buffering(void) 291 { 292 setvbuf(stdout, NULL, _IOLBF, 0); 293 } 294 295 int qemu_create_pidfile(const char *filename) 296 { 297 char buffer[128]; 298 int len; 299 int fd; 300 301 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600); 302 if (fd == -1) { 303 return -1; 304 } 305 if (lockf(fd, F_TLOCK, 0) == -1) { 306 close(fd); 307 return -1; 308 } 309 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid()); 310 if (write(fd, buffer, len) != len) { 311 close(fd); 312 return -1; 313 } 314 315 /* keep pidfile open & locked forever */ 316 return 0; 317 } 318 319 bool is_daemonized(void) 320 { 321 return daemonize; 322 } 323 324 int os_mlock(void) 325 { 326 int ret = 0; 327 328 ret = mlockall(MCL_CURRENT | MCL_FUTURE); 329 if (ret < 0) { 330 perror("mlockall"); 331 } 332 333 return ret; 334 } 335