os-posix.c

   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 <sys/mman.h>
  30 #include <pwd.h>
  31 #include <grp.h>
  32 #include <libgen.h>
  33
  34 /* Needed early for CONFIG_BSD etc. */
  35 #include "sysemu/sysemu.h"
  36 #include "net/slirp.h"
  37 #include "qemu-options.h"
  38 #include "qemu/rcu.h"
  39 #include "qemu/error-report.h"
  40 #include "qemu/log.h"
  41 #include "qemu/cutils.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         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 }