qemu/os-posix.c
Fiona Ebner 03e471c41d qemu_init: increase NOFILE soft limit on POSIX
In many configurations, e.g. multiple vNICs with multiple queues or
with many Ceph OSDs, the default soft limit of 1024 is not enough.
QEMU is supposed to work fine with file descriptors >= 1024 and does
not use select() on POSIX. Bump the soft limit to the allowed hard
limit to avoid issues with the aforementioned configurations.

Of course the limit could be raised from the outside, but the man page
of systemd.exec states about 'LimitNOFILE=':

> Don't use.
> [...]
> Typically applications should increase their soft limit to the hard
> limit on their own, if they are OK with working with file
> descriptors above 1023,

If the soft limit is already the same as the hard limit, avoid the
superfluous setrlimit call. This can avoid a warning with a strict
seccomp filter blocking setrlimit if NOFILE was already raised before
executing QEMU.

Buglink: https://bugzilla.proxmox.com/show_bug.cgi?id=4507
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2024-02-09 12:47:58 +00:00

341 lines
8.1 KiB
C

/*
* 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/resource.h>
#include <sys/wait.h>
#include <pwd.h>
#include <grp.h>
#include <libgen.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
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
}
/*
* 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 */
/*
* Prepare to change user ID. user_id can be one of 3 forms:
* - a username, in which case user ID will be changed to its uid,
* with primary and supplementary groups set up too;
* - a numeric uid, in which case only the uid will be set;
* - a pair of numeric uid:gid.
*/
bool os_set_runas(const char *user_id)
{
unsigned long lv;
const char *ep;
uid_t got_uid;
gid_t got_gid;
int rc;
user_pwd = getpwnam(user_id);
if (user_pwd) {
user_uid = -1;
user_gid = -1;
return true;
}
rc = qemu_strtoul(user_id, &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;
}
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 const char *chroot_dir;
void os_set_chroot(const char *path)
{
chroot_dir = path;
}
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);
}
}
}
static int daemonize;
static int daemon_pipe;
bool is_daemonized(void)
{
return daemonize;
}
int os_set_daemonize(bool d)
{
daemonize = d;
return 0;
}
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_limits(void)
{
struct rlimit nofile;
if (getrlimit(RLIMIT_NOFILE, &nofile) < 0) {
warn_report("unable to query NOFILE limit: %s", strerror(errno));
return;
}
if (nofile.rlim_cur == nofile.rlim_max) {
return;
}
nofile.rlim_cur = nofile.rlim_max;
if (setrlimit(RLIMIT_NOFILE, &nofile) < 0) {
warn_report("unable to set NOFILE limit: %s", strerror(errno));
return;
}
}
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);
}
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
}