os-posix.c - qemu - Git at Google

 /*
  * os-posix.c
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  * Copyright (c) 2010 Red Hat, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */

 #include "qemu/osdep.h"
 #include <sys/wait.h>
 #include <pwd.h>
 #include <grp.h>
 #include <libgen.h>

 /* Needed early for CONFIG_BSD etc. */
 #include "net/slirp.h"
 #include "qemu/qemu-options.h"
 #include "qemu/error-report.h"
 #include "qemu/log.h"
 #include "sysemu/runstate.h"
 #include "qemu/cutils.h"

 #ifdef CONFIG_LINUX
 #include <sys/prctl.h>
 #include "qemu/async-teardown.h"
 #endif

 /*
  * Must set all three of these at once.
  * Legal combinations are              unset   by name   by uid
  */
 static struct passwd *user_pwd;    /*   NULL   non-NULL   NULL   */
 static uid_t user_uid = (uid_t)-1; /*   -1      -1        >=0    */
 static gid_t user_gid = (gid_t)-1; /*   -1      -1        >=0    */

 static const char *chroot_dir;
 static int daemonize;
 static int daemon_pipe;

 void os_setup_early_signal_handling(void)
 {
     struct sigaction act;
     sigfillset(&act.sa_mask);
     act.sa_flags = 0;
     act.sa_handler = SIG_IGN;
     sigaction(SIGPIPE, &act, NULL);
 }

 static void termsig_handler(int signal, siginfo_t *info, void *c)
 {
     qemu_system_killed(info->si_signo, info->si_pid);
 }

 void os_setup_signal_handling(void)
 {
     struct sigaction act;

     memset(&act, 0, sizeof(act));
     act.sa_sigaction = termsig_handler;
     act.sa_flags = SA_SIGINFO;
     sigaction(SIGINT,  &act, NULL);
     sigaction(SIGHUP,  &act, NULL);
     sigaction(SIGTERM, &act, NULL);
 }

 void os_set_proc_name(const char *s)
 {
 #if defined(PR_SET_NAME)
     char name[16];
     if (!s)
         return;
     pstrcpy(name, sizeof(name), s);
     /* Could rewrite argv[0] too, but that's a bit more complicated.
        This simple way is enough for `top'. */
     if (prctl(PR_SET_NAME, name)) {
         error_report("unable to change process name: %s", strerror(errno));
         exit(1);
     }
 #else
     error_report("Change of process name not supported by your OS");
     exit(1);
 #endif
 }


 static bool os_parse_runas_uid_gid(const char *optarg)
 {
     unsigned long lv;
     const char *ep;
     uid_t got_uid;
     gid_t got_gid;
     int rc;

     rc = qemu_strtoul(optarg, &ep, 0, &lv);
     got_uid = lv; /* overflow here is ID in C99 */
     if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) {
         return false;
     }

     rc = qemu_strtoul(ep + 1, 0, 0, &lv);
     got_gid = lv; /* overflow here is ID in C99 */
     if (rc || got_gid != lv || got_gid == (gid_t)-1) {
         return false;
     }

     user_pwd = NULL;
     user_uid = got_uid;
     user_gid = got_gid;
     return true;
 }

 /*
  * Parse OS specific command line options.
  * return 0 if option handled, -1 otherwise
  */
 int os_parse_cmd_args(int index, const char *optarg)
 {
     switch (index) {
     case QEMU_OPTION_runas:
         user_pwd = getpwnam(optarg);
         if (user_pwd) {
             user_uid = -1;
             user_gid = -1;
         } else if (!os_parse_runas_uid_gid(optarg)) {
             error_report("User \"%s\" doesn't exist"
                          " (and is not <uid>:<gid>)",
                          optarg);
             exit(1);
         }
         break;
     case QEMU_OPTION_chroot:
         chroot_dir = optarg;
         break;
     case QEMU_OPTION_daemonize:
         daemonize = 1;
         break;
 #if defined(CONFIG_LINUX)
     case QEMU_OPTION_asyncteardown:
         init_async_teardown();
         break;
 #endif
     default:
         return -1;
     }

     return 0;
 }

 static void change_process_uid(void)
 {
     assert((user_uid == (uid_t)-1) || user_pwd == NULL);
     assert((user_uid == (uid_t)-1) ==
            (user_gid == (gid_t)-1));

     if (user_pwd || user_uid != (uid_t)-1) {
         gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
         uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
         if (setgid(intended_gid) < 0) {
             error_report("Failed to setgid(%d)", intended_gid);
             exit(1);
         }
         if (user_pwd) {
             if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
                 error_report("Failed to initgroups(\"%s\", %d)",
                         user_pwd->pw_name, user_pwd->pw_gid);
                 exit(1);
             }
         } else {
             if (setgroups(1, &user_gid) < 0) {
                 error_report("Failed to setgroups(1, [%d])",
                         user_gid);
                 exit(1);
             }
         }
         if (setuid(intended_uid) < 0) {
             error_report("Failed to setuid(%d)", intended_uid);
             exit(1);
         }
         if (setuid(0) != -1) {
             error_report("Dropping privileges failed");
             exit(1);
         }
     }
 }

 static void change_root(void)
 {
     if (chroot_dir) {
         if (chroot(chroot_dir) < 0) {
             error_report("chroot failed");
             exit(1);
         }
         if (chdir("/")) {
             error_report("not able to chdir to /: %s", strerror(errno));
             exit(1);
         }
     }

 }

 void os_daemonize(void)
 {
     if (daemonize) {
         pid_t pid;
         int fds[2];

         if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
             exit(1);
         }

         pid = fork();
         if (pid > 0) {
             uint8_t status;
             ssize_t len;

             close(fds[1]);

             do {
                 len = read(fds[0], &status, 1);
             } while (len < 0 && errno == EINTR);

             /* only exit successfully if our child actually wrote
              * a one-byte zero to our pipe, upon successful init */
             exit(len == 1 && status == 0 ? 0 : 1);

         } else if (pid < 0) {
             exit(1);
         }

         close(fds[0]);
         daemon_pipe = fds[1];

         setsid();

         pid = fork();
         if (pid > 0) {
             exit(0);
         } else if (pid < 0) {
             exit(1);
         }
         umask(027);

         signal(SIGTSTP, SIG_IGN);
         signal(SIGTTOU, SIG_IGN);
         signal(SIGTTIN, SIG_IGN);
     }
 }

 void os_setup_post(void)
 {
     int fd = 0;

     if (daemonize) {
         if (chdir("/")) {
             error_report("not able to chdir to /: %s", strerror(errno));
             exit(1);
         }
         fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR));
         if (fd == -1) {
             exit(1);
         }
     }

     change_root();
     change_process_uid();

     if (daemonize) {
         uint8_t status = 0;
         ssize_t len;

         dup2(fd, 0);
         dup2(fd, 1);
         /* In case -D is given do not redirect stderr to /dev/null */
         if (!qemu_log_enabled()) {
             dup2(fd, 2);
         }

         close(fd);

         do {
             len = write(daemon_pipe, &status, 1);
         } while (len < 0 && errno == EINTR);
         if (len != 1) {
             exit(1);
         }
     }
 }

 void os_set_line_buffering(void)
 {
     setvbuf(stdout, NULL, _IOLBF, 0);
 }

 bool is_daemonized(void)
 {
     return daemonize;
 }

 int os_set_daemonize(bool d)
 {
     daemonize = d;
     return 0;
 }

 int os_mlock(void)
 {
 #ifdef HAVE_MLOCKALL
     int ret = 0;

     ret = mlockall(MCL_CURRENT | MCL_FUTURE);
     if (ret < 0) {
         error_report("mlockall: %s", strerror(errno));
     }

     return ret;
 #else
     return -ENOSYS;
 #endif
 }
	/*
	* os-posix.c
	*
	* Copyright (c) 2003-2008 Fabrice Bellard
	* Copyright (c) 2010 Red Hat, Inc.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/

	#include "qemu/osdep.h"
	#include <sys/wait.h>
	#include <pwd.h>
	#include <grp.h>
	#include <libgen.h>

	/* Needed early for CONFIG_BSD etc. */
	#include "net/slirp.h"
	#include "qemu/qemu-options.h"
	#include "qemu/error-report.h"
	#include "qemu/log.h"
	#include "sysemu/runstate.h"
	#include "qemu/cutils.h"

	#ifdef CONFIG_LINUX
	#include <sys/prctl.h>
	#include "qemu/async-teardown.h"
	#endif

	/*
	* Must set all three of these at once.
	* Legal combinations are unset by name by uid
	*/
	static struct passwd user_pwd; / NULL non-NULL NULL */
	static uid_t user_uid = (uid_t)-1; /* -1 -1 >=0 */
	static gid_t user_gid = (gid_t)-1; /* -1 -1 >=0 */

	static const char *chroot_dir;
	static int daemonize;
	static int daemon_pipe;

	void os_setup_early_signal_handling(void)
	{
	struct sigaction act;
	sigfillset(&act.sa_mask);
	act.sa_flags = 0;
	act.sa_handler = SIG_IGN;
	sigaction(SIGPIPE, &act, NULL);
	}

	static void termsig_handler(int signal, siginfo_t info, void c)
	{
	qemu_system_killed(info->si_signo, info->si_pid);
	}

	void os_setup_signal_handling(void)
	{
	struct sigaction act;

	memset(&act, 0, sizeof(act));
	act.sa_sigaction = termsig_handler;
	act.sa_flags = SA_SIGINFO;
	sigaction(SIGINT, &act, NULL);
	sigaction(SIGHUP, &act, NULL);
	sigaction(SIGTERM, &act, NULL);
	}

	void os_set_proc_name(const char *s)
	{
	#if defined(PR_SET_NAME)
	char name[16];
	if (!s)
	return;
	pstrcpy(name, sizeof(name), s);
	/* Could rewrite argv[0] too, but that's a bit more complicated.
	This simple way is enough for `top'. */
	if (prctl(PR_SET_NAME, name)) {
	error_report("unable to change process name: %s", strerror(errno));
	exit(1);
	}
	#else
	error_report("Change of process name not supported by your OS");
	exit(1);
	#endif
	}


	static bool os_parse_runas_uid_gid(const char *optarg)
	{
	unsigned long lv;
	const char *ep;
	uid_t got_uid;
	gid_t got_gid;
	int rc;

	rc = qemu_strtoul(optarg, &ep, 0, &lv);
	got_uid = lv; /* overflow here is ID in C99 */
	if (rc \|\| *ep != ':' \|\| got_uid != lv \|\| got_uid == (uid_t)-1) {
	return false;
	}

	rc = qemu_strtoul(ep + 1, 0, 0, &lv);
	got_gid = lv; /* overflow here is ID in C99 */
	if (rc \|\| got_gid != lv \|\| got_gid == (gid_t)-1) {
	return false;
	}

	user_pwd = NULL;
	user_uid = got_uid;
	user_gid = got_gid;
	return true;
	}

	/*
	* Parse OS specific command line options.
	* return 0 if option handled, -1 otherwise
	*/
	int os_parse_cmd_args(int index, const char *optarg)
	{
	switch (index) {
	case QEMU_OPTION_runas:
	user_pwd = getpwnam(optarg);
	if (user_pwd) {
	user_uid = -1;
	user_gid = -1;
	} else if (!os_parse_runas_uid_gid(optarg)) {
	error_report("User \"%s\" doesn't exist"
	" (and is not <uid>:<gid>)",
	optarg);
	exit(1);
	}
	break;
	case QEMU_OPTION_chroot:
	chroot_dir = optarg;
	break;
	case QEMU_OPTION_daemonize:
	daemonize = 1;
	break;
	#if defined(CONFIG_LINUX)
	case QEMU_OPTION_asyncteardown:
	init_async_teardown();
	break;
	#endif
	default:
	return -1;
	}

	return 0;
	}

	static void change_process_uid(void)
	{
	assert((user_uid == (uid_t)-1) \|\| user_pwd == NULL);
	assert((user_uid == (uid_t)-1) ==
	(user_gid == (gid_t)-1));

	if (user_pwd \|\| user_uid != (uid_t)-1) {
	gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
	uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
	if (setgid(intended_gid) < 0) {
	error_report("Failed to setgid(%d)", intended_gid);
	exit(1);
	}
	if (user_pwd) {
	if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
	error_report("Failed to initgroups(\"%s\", %d)",
	user_pwd->pw_name, user_pwd->pw_gid);
	exit(1);
	}
	} else {
	if (setgroups(1, &user_gid) < 0) {
	error_report("Failed to setgroups(1, [%d])",
	user_gid);
	exit(1);
	}
	}
	if (setuid(intended_uid) < 0) {
	error_report("Failed to setuid(%d)", intended_uid);
	exit(1);
	}
	if (setuid(0) != -1) {
	error_report("Dropping privileges failed");
	exit(1);
	}
	}
	}

	static void change_root(void)
	{
	if (chroot_dir) {
	if (chroot(chroot_dir) < 0) {
	error_report("chroot failed");
	exit(1);
	}
	if (chdir("/")) {
	error_report("not able to chdir to /: %s", strerror(errno));
	exit(1);
	}
	}

	}

	void os_daemonize(void)
	{
	if (daemonize) {
	pid_t pid;
	int fds[2];

	if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) {
	exit(1);
	}

	pid = fork();
	if (pid > 0) {
	uint8_t status;
	ssize_t len;

	close(fds[1]);

	do {
	len = read(fds[0], &status, 1);
	} while (len < 0 && errno == EINTR);

	/* only exit successfully if our child actually wrote
	* a one-byte zero to our pipe, upon successful init */
	exit(len == 1 && status == 0 ? 0 : 1);

	} else if (pid < 0) {
	exit(1);
	}

	close(fds[0]);
	daemon_pipe = fds[1];

	setsid();

	pid = fork();
	if (pid > 0) {
	exit(0);
	} else if (pid < 0) {
	exit(1);
	}
	umask(027);

	signal(SIGTSTP, SIG_IGN);
	signal(SIGTTOU, SIG_IGN);
	signal(SIGTTIN, SIG_IGN);
	}
	}

	void os_setup_post(void)
	{
	int fd = 0;

	if (daemonize) {
	if (chdir("/")) {
	error_report("not able to chdir to /: %s", strerror(errno));
	exit(1);
	}
	fd = RETRY_ON_EINTR(qemu_open_old("/dev/null", O_RDWR));
	if (fd == -1) {
	exit(1);
	}
	}

	change_root();
	change_process_uid();

	if (daemonize) {
	uint8_t status = 0;
	ssize_t len;

	dup2(fd, 0);
	dup2(fd, 1);
	/* In case -D is given do not redirect stderr to /dev/null */
	if (!qemu_log_enabled()) {
	dup2(fd, 2);
	}

	close(fd);

	do {
	len = write(daemon_pipe, &status, 1);
	} while (len < 0 && errno == EINTR);
	if (len != 1) {
	exit(1);
	}
	}
	}

	void os_set_line_buffering(void)
	{
	setvbuf(stdout, NULL, _IOLBF, 0);
	}

	bool is_daemonized(void)
	{
	return daemonize;
	}

	int os_set_daemonize(bool d)
	{
	daemonize = d;
	return 0;
	}

	int os_mlock(void)
	{
	#ifdef HAVE_MLOCKALL
	int ret = 0;

	ret = mlockall(MCL_CURRENT \| MCL_FUTURE);
	if (ret < 0) {
	error_report("mlockall: %s", strerror(errno));
	}

	return ret;
	#else
	return -ENOSYS;
	#endif
	}