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 #include "qemu/error-report.h"
  44
  45 #ifdef CONFIG_LINUX
  46 #include <sys/prctl.h>
  47 #endif
  48
  49 static struct passwd *user_pwd;
  50 static const char *chroot_dir;
  51 static int daemonize;
  52 static int daemon_pipe;
  53
  54 void os_setup_early_signal_handling(void)
  55 {
  56     struct sigaction act;
  57     sigfillset(&act.sa_mask);
  58     act.sa_flags = 0;
  59     act.sa_handler = SIG_IGN;
  60     sigaction(SIGPIPE, &act, NULL);
  61 }
  62
  63 static void termsig_handler(int signal, siginfo_t *info, void *c)
  64 {
  65     qemu_system_killed(info->si_signo, info->si_pid);
  66 }
  67
  68 void os_setup_signal_handling(void)
  69 {
  70     struct sigaction act;
  71
  72     memset(&act, 0, sizeof(act));
  73     act.sa_sigaction = termsig_handler;
  74     act.sa_flags = SA_SIGINFO;
  75     sigaction(SIGINT,  &act, NULL);
  76     sigaction(SIGHUP,  &act, NULL);
  77     sigaction(SIGTERM, &act, NULL);
  78 }
  79
  80 /* Find a likely location for support files using the location of the binary.
  81    For installed binaries this will be "$bindir/../share/qemu".  When
  82    running from the build tree this will be "$bindir/../pc-bios".  */
  83 #define SHARE_SUFFIX "/share/qemu"
  84 #define BUILD_SUFFIX "/pc-bios"
  85 char *os_find_datadir(void)
  86 {
  87     char *dir, *exec_dir;
  88     char *res;
  89     size_t max_len;
  90
  91     exec_dir = qemu_get_exec_dir();
  92     if (exec_dir == NULL) {
  93         return NULL;
  94     }
  95     dir = dirname(exec_dir);
  96
  97     max_len = strlen(dir) +
  98         MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
  99     res = g_malloc0(max_len);
 100     snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
 101     if (access(res, R_OK)) {
 102         snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
 103         if (access(res, R_OK)) {
 104             g_free(res);
 105             res = NULL;
 106         }
 107     }
 108
 109     g_free(exec_dir);
 110     return res;
 111 }
 112 #undef SHARE_SUFFIX
 113 #undef BUILD_SUFFIX
 114
 115 void os_set_proc_name(const char *s)
 116 {
 117 #if defined(PR_SET_NAME)
 118     char name[16];
 119     if (!s)
 120         return;
 121     pstrcpy(name, sizeof(name), s);
 122     /* Could rewrite argv[0] too, but that's a bit more complicated.
 123        This simple way is enough for `top'. */
 124     if (prctl(PR_SET_NAME, name)) {
 125         perror("unable to change process name");
 126         exit(1);
 127     }
 128 #else
 129     fprintf(stderr, "Change of process name not supported by your OS\n");
 130     exit(1);
 131 #endif
 132 }
 133
 134 /*
 135  * Parse OS specific command line options.
 136  * return 0 if option handled, -1 otherwise
 137  */
 138 void os_parse_cmd_args(int index, const char *optarg)
 139 {
 140     switch (index) {
 141 #ifdef CONFIG_SLIRP
 142     case QEMU_OPTION_smb:
 143         error_report("The -smb option is deprecated. "
 144                      "Please use '-netdev user,smb=...' instead.");
 145         if (net_slirp_smb(optarg) < 0)
 146             exit(1);
 147         break;
 148 #endif
 149     case QEMU_OPTION_runas:
 150         user_pwd = getpwnam(optarg);
 151         if (!user_pwd) {
 152             fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
 153             exit(1);
 154         }
 155         break;
 156     case QEMU_OPTION_chroot:
 157         chroot_dir = optarg;
 158         break;
 159     case QEMU_OPTION_daemonize:
 160         daemonize = 1;
 161         break;
 162 #if defined(CONFIG_LINUX)
 163     case QEMU_OPTION_enablefips:
 164         fips_set_state(true);
 165         break;
 166 #endif
 167     }
 168 }
 169
 170 static void change_process_uid(void)
 171 {
 172     if (user_pwd) {
 173         if (setgid(user_pwd->pw_gid) < 0) {
 174             fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
 175             exit(1);
 176         }
 177         if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
 178             fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
 179                     user_pwd->pw_name, user_pwd->pw_gid);
 180             exit(1);
 181         }
 182         if (setuid(user_pwd->pw_uid) < 0) {
 183             fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
 184             exit(1);
 185         }
 186         if (setuid(0) != -1) {
 187             fprintf(stderr, "Dropping privileges failed\n");
 188             exit(1);
 189         }
 190     }
 191 }
 192
 193 static void change_root(void)
 194 {
 195     if (chroot_dir) {
 196         if (chroot(chroot_dir) < 0) {
 197             fprintf(stderr, "chroot failed\n");
 198             exit(1);
 199         }
 200         if (chdir("/")) {
 201             perror("not able to chdir to /");
 202             exit(1);
 203         }
 204     }
 205
 206 }
 207
 208 void os_daemonize(void)
 209 {
 210     if (daemonize) {
 211         pid_t pid;
 212         int fds[2];
 213
 214         if (pipe(fds) == -1) {
 215             exit(1);
 216         }
 217
 218         pid = fork();
 219         if (pid > 0) {
 220             uint8_t status;
 221             ssize_t len;
 222
 223             close(fds[1]);
 224
 225             do {
 226                 len = read(fds[0], &status, 1);
 227             } while (len < 0 && errno == EINTR);
 228
 229             /* only exit successfully if our child actually wrote
 230              * a one-byte zero to our pipe, upon successful init */
 231             exit(len == 1 && status == 0 ? 0 : 1);
 232
 233         } else if (pid < 0) {
 234             exit(1);
 235         }
 236
 237         close(fds[0]);
 238         daemon_pipe = fds[1];
 239         qemu_set_cloexec(daemon_pipe);
 240
 241         setsid();
 242
 243         pid = fork();
 244         if (pid > 0) {
 245             exit(0);
 246         } else if (pid < 0) {
 247             exit(1);
 248         }
 249         umask(027);
 250
 251         signal(SIGTSTP, SIG_IGN);
 252         signal(SIGTTOU, SIG_IGN);
 253         signal(SIGTTIN, SIG_IGN);
 254         rcu_after_fork();
 255     }
 256 }
 257
 258 void os_setup_post(void)
 259 {
 260     int fd = 0;
 261
 262     if (daemonize) {
 263         if (chdir("/")) {
 264             perror("not able to chdir to /");
 265             exit(1);
 266         }
 267         TFR(fd = qemu_open("/dev/null", O_RDWR));
 268         if (fd == -1) {
 269             exit(1);
 270         }
 271     }
 272
 273     change_root();
 274     change_process_uid();
 275
 276     if (daemonize) {
 277         uint8_t status = 0;
 278         ssize_t len;
 279
 280         dup2(fd, 0);
 281         dup2(fd, 1);
 282         dup2(fd, 2);
 283
 284         close(fd);
 285
 286         do {
 287             len = write(daemon_pipe, &status, 1);
 288         } while (len < 0 && errno == EINTR);
 289         if (len != 1) {
 290             exit(1);
 291         }
 292     }
 293 }
 294
 295 void os_set_line_buffering(void)
 296 {
 297     setvbuf(stdout, NULL, _IOLBF, 0);
 298 }
 299
 300 int qemu_create_pidfile(const char *filename)
 301 {
 302     char buffer[128];
 303     int len;
 304     int fd;
 305
 306     fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
 307     if (fd == -1) {
 308         return -1;
 309     }
 310     if (lockf(fd, F_TLOCK, 0) == -1) {
 311         close(fd);
 312         return -1;
 313     }
 314     len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
 315     if (write(fd, buffer, len) != len) {
 316         close(fd);
 317         return -1;
 318     }
 319
 320     /* keep pidfile open & locked forever */
 321     return 0;
 322 }
 323
 324 bool is_daemonized(void)
 325 {
 326     return daemonize;
 327 }
 328
 329 int os_mlock(void)
 330 {
 331     int ret = 0;
 332
 333     ret = mlockall(MCL_CURRENT | MCL_FUTURE);
 334     if (ret < 0) {
 335         perror("mlockall");
 336     }
 337
 338     return ret;
 339 }