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 #ifdef __FreeBSD__
  48 #include <sys/sysctl.h>
  49 #endif
  50
  51 static struct passwd *user_pwd;
  52 static const char *chroot_dir;
  53 static int daemonize;
  54 static int fds[2];
  55
  56 void os_setup_early_signal_handling(void)
  57 {
  58     struct sigaction act;
  59     sigfillset(&act.sa_mask);
  60     act.sa_flags = 0;
  61     act.sa_handler = SIG_IGN;
  62     sigaction(SIGPIPE, &act, NULL);
  63 }
  64
  65 static void termsig_handler(int signal, siginfo_t *info, void *c)
  66 {
  67     qemu_system_killed(info->si_signo, info->si_pid);
  68 }
  69
  70 void os_setup_signal_handling(void)
  71 {
  72     struct sigaction act;
  73
  74     memset(&act, 0, sizeof(act));
  75     act.sa_sigaction = termsig_handler;
  76     act.sa_flags = SA_SIGINFO;
  77     sigaction(SIGINT,  &act, NULL);
  78     sigaction(SIGHUP,  &act, NULL);
  79     sigaction(SIGTERM, &act, NULL);
  80 }
  81
  82 /* Find a likely location for support files using the location of the binary.
  83    For installed binaries this will be "$bindir/../share/qemu".  When
  84    running from the build tree this will be "$bindir/../pc-bios".  */
  85 #define SHARE_SUFFIX "/share/qemu"
  86 #define BUILD_SUFFIX "/pc-bios"
  87 char *os_find_datadir(void)
  88 {
  89     char *dir, *exec_dir;
  90     char *res;
  91     size_t max_len;
  92
  93     exec_dir = qemu_get_exec_dir();
  94     if (exec_dir == NULL) {
  95         return NULL;
  96     }
  97     dir = dirname(exec_dir);
  98
  99     max_len = strlen(dir) +
 100         MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
 101     res = g_malloc0(max_len);
 102     snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
 103     if (access(res, R_OK)) {
 104         snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
 105         if (access(res, R_OK)) {
 106             g_free(res);
 107             res = NULL;
 108         }
 109     }
 110
 111     g_free(exec_dir);
 112     return res;
 113 }
 114 #undef SHARE_SUFFIX
 115 #undef BUILD_SUFFIX
 116
 117 void os_set_proc_name(const char *s)
 118 {
 119 #if defined(PR_SET_NAME)
 120     char name[16];
 121     if (!s)
 122         return;
 123     pstrcpy(name, sizeof(name), s);
 124     /* Could rewrite argv[0] too, but that's a bit more complicated.
 125        This simple way is enough for `top'. */
 126     if (prctl(PR_SET_NAME, name)) {
 127         perror("unable to change process name");
 128         exit(1);
 129     }
 130 #else
 131     fprintf(stderr, "Change of process name not supported by your OS\n");
 132     exit(1);
 133 #endif
 134 }
 135
 136 /*
 137  * Parse OS specific command line options.
 138  * return 0 if option handled, -1 otherwise
 139  */
 140 void os_parse_cmd_args(int index, const char *optarg)
 141 {
 142     switch (index) {
 143 #ifdef CONFIG_SLIRP
 144     case QEMU_OPTION_smb:
 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
 213         if (pipe(fds) == -1)
 214             exit(1);
 215
 216         pid = fork();
 217         if (pid > 0) {
 218             uint8_t status;
 219             ssize_t len;
 220
 221             close(fds[1]);
 222
 223         again:
 224             len = read(fds[0], &status, 1);
 225             if (len == -1 && (errno == EINTR))
 226                 goto again;
 227
 228             if (len != 1)
 229                 exit(1);
 230             else if (status == 1) {
 231                 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
 232                 exit(1);
 233             } else
 234                 exit(0);
 235         } else if (pid < 0)
 236             exit(1);
 237
 238         close(fds[0]);
 239         qemu_set_cloexec(fds[1]);
 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     }
 255 }
 256
 257 void os_setup_post(void)
 258 {
 259     int fd = 0;
 260
 261     if (daemonize) {
 262         uint8_t status = 0;
 263         ssize_t len;
 264
 265     again1:
 266         len = write(fds[1], &status, 1);
 267         if (len == -1 && (errno == EINTR))
 268             goto again1;
 269
 270         if (len != 1)
 271             exit(1);
 272
 273         if (chdir("/")) {
 274             perror("not able to chdir to /");
 275             exit(1);
 276         }
 277         TFR(fd = qemu_open("/dev/null", O_RDWR));
 278         if (fd == -1)
 279             exit(1);
 280     }
 281
 282     change_root();
 283     change_process_uid();
 284
 285     if (daemonize) {
 286         dup2(fd, 0);
 287         dup2(fd, 1);
 288         dup2(fd, 2);
 289
 290         close(fd);
 291     }
 292 }
 293
 294 void os_pidfile_error(void)
 295 {
 296     if (daemonize) {
 297         uint8_t status = 1;
 298         if (write(fds[1], &status, 1) != 1) {
 299             perror("daemonize. Writing to pipe\n");
 300         }
 301     } else
 302         fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
 303 }
 304
 305 void os_set_line_buffering(void)
 306 {
 307     setvbuf(stdout, NULL, _IOLBF, 0);
 308 }
 309
 310 int qemu_create_pidfile(const char *filename)
 311 {
 312     char buffer[128];
 313     int len;
 314     int fd;
 315
 316     fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
 317     if (fd == -1) {
 318         return -1;
 319     }
 320     if (lockf(fd, F_TLOCK, 0) == -1) {
 321         close(fd);
 322         return -1;
 323     }
 324     len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
 325     if (write(fd, buffer, len) != len) {
 326         close(fd);
 327         return -1;
 328     }
 329
 330     /* keep pidfile open & locked forever */
 331     return 0;
 332 }
 333
 334 bool is_daemonized(void)
 335 {
 336     return daemonize;
 337 }
 338
 339 int os_mlock(void)
 340 {
 341     int ret = 0;
 342
 343     ret = mlockall(MCL_CURRENT | MCL_FUTURE);
 344     if (ret < 0) {
 345         perror("mlockall");
 346     }
 347
 348     return ret;
 349 }