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qemu-e2k/os-posix.c
Philippe Mathieu-Daudé 7da1d7dcc0 qemu/osdep: Document os_find_datadir() return value 
Document os_find_datadir() returned data must be freed.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Michael Rolnik <mrolnik@gmail.com>
Tested-by: Michael Rolnik <mrolnik@gmail.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200714164257.23330-2-f4bug@amsat.org>
2020-07-21 16:13:04 +02:00

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/*
* 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>
#include "qemu-common.h"
/* Needed early for CONFIG_BSD etc. */
#include "net/slirp.h"
#include "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>
#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);
}
/*
* Find a likely location for support files using the location of the binary.
* When running from the build tree this will be "$bindir/../pc-bios".
* Otherwise, this is CONFIG_QEMU_DATADIR.
*
* The caller must use g_free() to free the returned data when it is
* no longer required.
*/
char *os_find_datadir(void)
{
g_autofree char *exec_dir = NULL;
g_autofree char *dir = NULL;
exec_dir = qemu_get_exec_dir();
g_return_val_if_fail(exec_dir != NULL, NULL);
dir = g_build_filename(exec_dir, "..", "pc-bios", NULL);
if (g_file_test(dir, G_FILE_TEST_IS_DIR)) {
return g_steal_pointer(&dir);
}
return g_strdup(CONFIG_QEMU_DATADIR);
}
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_enablefips:
fips_set_state(true);
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 (pipe(fds) == -1) {
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];
qemu_set_cloexec(daemon_pipe);
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);
}
TFR(fd = qemu_open("/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_logfile) {
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_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
}
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