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 #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 }