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qemu/os-posix.c
Daniel P. Berrangé 166310299a os: deprecate the -enable-fips option and QEMU's FIPS enforcement 
The -enable-fips option was added a long time ago to prevent the use of
single DES when VNC when FIPS mode is enabled. It should never have been
added, because apps are supposed to unconditionally honour FIPS mode
based on the '/proc/sys/crypto/fips_enabled' file contents.

In addition there is more to achieving FIPS compliance than merely
blocking use of certain algorithms. Those algorithms which are used
need to perform self-tests at runtime.

QEMU's built-in cryptography provider has no support for self-tests,
and neither does the nettle library.

If QEMU is required to be used in a FIPS enabled host, then it must be
built with the libgcrypt library enabled, which will unconditionally
enforce FIPS compliance in any algorithm usage.

Thus there is no need to keep either the -enable-fips option in QEMU, or
QEMU's internal FIPS checking methods.

Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2021-01-29 17:07:53 +00:00

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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);
}
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:
warn_report("-enable-fips is deprecated, please build QEMU with "
"the `libgcrypt` library as the cryptography provider "
"to enable FIPS compliance");
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_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_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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