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 #include "qemu/rcu.h"
  43
  44 #ifdef CONFIG_LINUX
  45 #include <sys/prctl.h>
  46 #endif
  47
  48 static struct passwd *user_pwd;
  49 static const char *chroot_dir;
  50 static int daemonize;
  51 static int daemon_pipe;
  52
  53 void os_setup_early_signal_handling(void)
  54 {
  55     struct sigaction act;
  56     sigfillset(&act.sa_mask);
  57     act.sa_flags = 0;
  58     act.sa_handler = SIG_IGN;
  59     sigaction(SIGPIPE, &act, NULL);
  60 }
  61
  62 static void termsig_handler(int signal, siginfo_t *info, void *c)
  63 {
  64     qemu_system_killed(info->si_signo, info->si_pid);
  65 }
  66
  67 void os_setup_signal_handling(void)
  68 {
  69     struct sigaction act;
  70
  71     memset(&act, 0, sizeof(act));
  72     act.sa_sigaction = termsig_handler;
  73     act.sa_flags = SA_SIGINFO;
  74     sigaction(SIGINT,  &act, NULL);
  75     sigaction(SIGHUP,  &act, NULL);
  76     sigaction(SIGTERM, &act, NULL);
  77 }
  78
  79 /* Find a likely location for support files using the location of the binary.
  80    For installed binaries this will be "$bindir/../share/qemu".  When
  81    running from the build tree this will be "$bindir/../pc-bios".  */
  82 #define SHARE_SUFFIX "/share/qemu"
  83 #define BUILD_SUFFIX "/pc-bios"
  84 char *os_find_datadir(void)
  85 {
  86     char *dir, *exec_dir;
  87     char *res;
  88     size_t max_len;
  89
  90     exec_dir = qemu_get_exec_dir();
  91     if (exec_dir == NULL) {
  92         return NULL;
  93     }
  94     dir = dirname(exec_dir);
  95
  96     max_len = strlen(dir) +
  97         MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
  98     res = g_malloc0(max_len);
  99     snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
 100     if (access(res, R_OK)) {
 101         snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
 102         if (access(res, R_OK)) {
 103             g_free(res);
 104             res = NULL;
 105         }
 106     }
 107
 108     g_free(exec_dir);
 109     return res;
 110 }
 111 #undef SHARE_SUFFIX
 112 #undef BUILD_SUFFIX
 113
 114 void os_set_proc_name(const char *s)
 115 {
 116 #if defined(PR_SET_NAME)
 117     char name[16];
 118     if (!s)
 119         return;
 120     pstrcpy(name, sizeof(name), s);
 121     /* Could rewrite argv[0] too, but that's a bit more complicated.
 122        This simple way is enough for `top'. */
 123     if (prctl(PR_SET_NAME, name)) {
 124         perror("unable to change process name");
 125         exit(1);
 126     }
 127 #else
 128     fprintf(stderr, "Change of process name not supported by your OS\n");
 129     exit(1);
 130 #endif
 131 }
 132
 133 /*
 134  * Parse OS specific command line options.
 135  * return 0 if option handled, -1 otherwise
 136  */
 137 void os_parse_cmd_args(int index, const char *optarg)
 138 {
 139     switch (index) {
 140 #ifdef CONFIG_SLIRP
 141     case QEMU_OPTION_smb:
 142         if (net_slirp_smb(optarg) < 0)
 143             exit(1);
 144         break;
 145 #endif
 146     case QEMU_OPTION_runas:
 147         user_pwd = getpwnam(optarg);
 148         if (!user_pwd) {
 149             fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
 150             exit(1);
 151         }
 152         break;
 153     case QEMU_OPTION_chroot:
 154         chroot_dir = optarg;
 155         break;
 156     case QEMU_OPTION_daemonize:
 157         daemonize = 1;
 158         break;
 159 #if defined(CONFIG_LINUX)
 160     case QEMU_OPTION_enablefips:
 161         fips_set_state(true);
 162         break;
 163 #endif
 164     }
 165 }
 166
 167 static void change_process_uid(void)
 168 {
 169     if (user_pwd) {
 170         if (setgid(user_pwd->pw_gid) < 0) {
 171             fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
 172             exit(1);
 173         }
 174         if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
 175             fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
 176                     user_pwd->pw_name, user_pwd->pw_gid);
 177             exit(1);
 178         }
 179         if (setuid(user_pwd->pw_uid) < 0) {
 180             fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
 181             exit(1);
 182         }
 183         if (setuid(0) != -1) {
 184             fprintf(stderr, "Dropping privileges failed\n");
 185             exit(1);
 186         }
 187     }
 188 }
 189
 190 static void change_root(void)
 191 {
 192     if (chroot_dir) {
 193         if (chroot(chroot_dir) < 0) {
 194             fprintf(stderr, "chroot failed\n");
 195             exit(1);
 196         }
 197         if (chdir("/")) {
 198             perror("not able to chdir to /");
 199             exit(1);
 200         }
 201     }
 202
 203 }
 204
 205 void os_daemonize(void)
 206 {
 207     if (daemonize) {
 208         pid_t pid;
 209         int fds[2];
 210
 211         if (pipe(fds) == -1) {
 212             exit(1);
 213         }
 214
 215         pid = fork();
 216         if (pid > 0) {
 217             uint8_t status;
 218             ssize_t len;
 219
 220             close(fds[1]);
 221
 222             do {
 223                 len = read(fds[0], &status, 1);
 224             } while (len < 0 && errno == EINTR);
 225
 226             /* only exit successfully if our child actually wrote
 227              * a one-byte zero to our pipe, upon successful init */
 228             exit(len == 1 && status == 0 ? 0 : 1);
 229
 230         } else if (pid < 0) {
 231             exit(1);
 232         }
 233
 234         close(fds[0]);
 235         daemon_pipe = fds[1];
 236         qemu_set_cloexec(daemon_pipe);
 237
 238         setsid();
 239
 240         pid = fork();
 241         if (pid > 0) {
 242             exit(0);
 243         } else if (pid < 0) {
 244             exit(1);
 245         }
 246         umask(027);
 247
 248         signal(SIGTSTP, SIG_IGN);
 249         signal(SIGTTOU, SIG_IGN);
 250         signal(SIGTTIN, SIG_IGN);
 251         rcu_after_fork();
 252     }
 253 }
 254
 255 void os_setup_post(void)
 256 {
 257     int fd = 0;
 258
 259     if (daemonize) {
 260         if (chdir("/")) {
 261             perror("not able to chdir to /");
 262             exit(1);
 263         }
 264         TFR(fd = qemu_open("/dev/null", O_RDWR));
 265         if (fd == -1) {
 266             exit(1);
 267         }
 268     }
 269
 270     change_root();
 271     change_process_uid();
 272
 273     if (daemonize) {
 274         uint8_t status = 0;
 275         ssize_t len;
 276
 277         dup2(fd, 0);
 278         dup2(fd, 1);
 279         dup2(fd, 2);
 280
 281         close(fd);
 282
 283         do {
 284             len = write(daemon_pipe, &status, 1);
 285         } while (len < 0 && errno == EINTR);
 286         if (len != 1) {
 287             exit(1);
 288         }
 289     }
 290 }
 291
 292 void os_set_line_buffering(void)
 293 {
 294     setvbuf(stdout, NULL, _IOLBF, 0);
 295 }
 296
 297 int qemu_create_pidfile(const char *filename)
 298 {
 299     char buffer[128];
 300     int len;
 301     int fd;
 302
 303     fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
 304     if (fd == -1) {
 305         return -1;
 306     }
 307     if (lockf(fd, F_TLOCK, 0) == -1) {
 308         close(fd);
 309         return -1;
 310     }
 311     len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
 312     if (write(fd, buffer, len) != len) {
 313         close(fd);
 314         return -1;
 315     }
 316
 317     /* keep pidfile open & locked forever */
 318     return 0;
 319 }
 320
 321 bool is_daemonized(void)
 322 {
 323     return daemonize;
 324 }
 325
 326 int os_mlock(void)
 327 {
 328     int ret = 0;
 329
 330     ret = mlockall(MCL_CURRENT | MCL_FUTURE);
 331     if (ret < 0) {
 332         perror("mlockall");
 333     }
 334
 335     return ret;
 336 }