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
  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 = 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(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         rcu_after_fork();
 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         dup2(fd, 2);
 279
 280         close(fd);
 281
 282         do {
 283             len = write(daemon_pipe, &status, 1);
 284         } while (len < 0 && errno == EINTR);
 285         if (len != 1) {
 286             exit(1);
 287         }
 288     }
 289 }
 290
 291 void os_set_line_buffering(void)
 292 {
 293     setvbuf(stdout, NULL, _IOLBF, 0);
 294 }
 295
 296 int qemu_create_pidfile(const char *filename)
 297 {
 298     char buffer[128];
 299     int len;
 300     int fd;
 301
 302     fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
 303     if (fd == -1) {
 304         return -1;
 305     }
 306     if (lockf(fd, F_TLOCK, 0) == -1) {
 307         close(fd);
 308         return -1;
 309     }
 310     len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
 311     if (write(fd, buffer, len) != len) {
 312         close(fd);
 313         return -1;
 314     }
 315
 316     /* keep pidfile open & locked forever */
 317     return 0;
 318 }
 319
 320 bool is_daemonized(void)
 321 {
 322     return daemonize;
 323 }
 324
 325 int os_mlock(void)
 326 {
 327     int ret = 0;
 328
 329     ret = mlockall(MCL_CURRENT | MCL_FUTURE);
 330     if (ret < 0) {
 331         perror("mlockall");
 332     }
 333
 334     return ret;
 335 }