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 <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 }