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linux/kernel/sys.c
Heiko Carstens 836f92adf1 [CVE-2009-0029] System call wrappers part 31 
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2009-01-14 14:15:31 +01:00

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/*
* linux/kernel/sys.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/utsname.h>
#include <linux/mman.h>
#include <linux/smp_lock.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/prctl.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/resource.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/workqueue.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/key.h>
#include <linux/times.h>
#include <linux/posix-timers.h>
#include <linux/security.h>
#include <linux/dcookies.h>
#include <linux/suspend.h>
#include <linux/tty.h>
#include <linux/signal.h>
#include <linux/cn_proc.h>
#include <linux/getcpu.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/seccomp.h>
#include <linux/cpu.h>
#include <linux/ptrace.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/kprobes.h>
#include <linux/user_namespace.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/unistd.h>
#ifndef SET_UNALIGN_CTL
# define SET_UNALIGN_CTL(a,b) (-EINVAL)
#endif
#ifndef GET_UNALIGN_CTL
# define GET_UNALIGN_CTL(a,b) (-EINVAL)
#endif
#ifndef SET_FPEMU_CTL
# define SET_FPEMU_CTL(a,b) (-EINVAL)
#endif
#ifndef GET_FPEMU_CTL
# define GET_FPEMU_CTL(a,b) (-EINVAL)
#endif
#ifndef SET_FPEXC_CTL
# define SET_FPEXC_CTL(a,b) (-EINVAL)
#endif
#ifndef GET_FPEXC_CTL
# define GET_FPEXC_CTL(a,b) (-EINVAL)
#endif
#ifndef GET_ENDIAN
# define GET_ENDIAN(a,b) (-EINVAL)
#endif
#ifndef SET_ENDIAN
# define SET_ENDIAN(a,b) (-EINVAL)
#endif
#ifndef GET_TSC_CTL
# define GET_TSC_CTL(a) (-EINVAL)
#endif
#ifndef SET_TSC_CTL
# define SET_TSC_CTL(a) (-EINVAL)
#endif
/*
* this is where the system-wide overflow UID and GID are defined, for
* architectures that now have 32-bit UID/GID but didn't in the past
*/
int overflowuid = DEFAULT_OVERFLOWUID;
int overflowgid = DEFAULT_OVERFLOWGID;
#ifdef CONFIG_UID16
EXPORT_SYMBOL(overflowuid);
EXPORT_SYMBOL(overflowgid);
#endif
/*
* the same as above, but for filesystems which can only store a 16-bit
* UID and GID. as such, this is needed on all architectures
*/
int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
EXPORT_SYMBOL(fs_overflowuid);
EXPORT_SYMBOL(fs_overflowgid);
/*
* this indicates whether you can reboot with ctrl-alt-del: the default is yes
*/
int C_A_D = 1;
struct pid *cad_pid;
EXPORT_SYMBOL(cad_pid);
/*
* If set, this is used for preparing the system to power off.
*/
void (*pm_power_off_prepare)(void);
/*
* set the priority of a task
* - the caller must hold the RCU read lock
*/
static int set_one_prio(struct task_struct *p, int niceval, int error)
{
const struct cred *cred = current_cred(), *pcred = __task_cred(p);
int no_nice;
if (pcred->uid != cred->euid &&
pcred->euid != cred->euid && !capable(CAP_SYS_NICE)) {
error = -EPERM;
goto out;
}
if (niceval < task_nice(p) && !can_nice(p, niceval)) {
error = -EACCES;
goto out;
}
no_nice = security_task_setnice(p, niceval);
if (no_nice) {
error = no_nice;
goto out;
}
if (error == -ESRCH)
error = 0;
set_user_nice(p, niceval);
out:
return error;
}
SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
{
struct task_struct *g, *p;
struct user_struct *user;
const struct cred *cred = current_cred();
int error = -EINVAL;
struct pid *pgrp;
if (which > PRIO_USER || which < PRIO_PROCESS)
goto out;
/* normalize: avoid signed division (rounding problems) */
error = -ESRCH;
if (niceval < -20)
niceval = -20;
if (niceval > 19)
niceval = 19;
read_lock(&tasklist_lock);
switch (which) {
case PRIO_PROCESS:
if (who)
p = find_task_by_vpid(who);
else
p = current;
if (p)
error = set_one_prio(p, niceval, error);
break;
case PRIO_PGRP:
if (who)
pgrp = find_vpid(who);
else
pgrp = task_pgrp(current);
do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
error = set_one_prio(p, niceval, error);
} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
break;
case PRIO_USER:
user = (struct user_struct *) cred->user;
if (!who)
who = cred->uid;
else if ((who != cred->uid) &&
!(user = find_user(who)))
goto out_unlock; /* No processes for this user */
do_each_thread(g, p)
if (__task_cred(p)->uid == who)
error = set_one_prio(p, niceval, error);
while_each_thread(g, p);
if (who != cred->uid)
free_uid(user); /* For find_user() */
break;
}
out_unlock:
read_unlock(&tasklist_lock);
out:
return error;
}
/*
* Ugh. To avoid negative return values, "getpriority()" will
* not return the normal nice-value, but a negated value that
* has been offset by 20 (ie it returns 40..1 instead of -20..19)
* to stay compatible.
*/
SYSCALL_DEFINE2(getpriority, int, which, int, who)
{
struct task_struct *g, *p;
struct user_struct *user;
const struct cred *cred = current_cred();
long niceval, retval = -ESRCH;
struct pid *pgrp;
if (which > PRIO_USER || which < PRIO_PROCESS)
return -EINVAL;
read_lock(&tasklist_lock);
switch (which) {
case PRIO_PROCESS:
if (who)
p = find_task_by_vpid(who);
else
p = current;
if (p) {
niceval = 20 - task_nice(p);
if (niceval > retval)
retval = niceval;
}
break;
case PRIO_PGRP:
if (who)
pgrp = find_vpid(who);
else
pgrp = task_pgrp(current);
do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
niceval = 20 - task_nice(p);
if (niceval > retval)
retval = niceval;
} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
break;
case PRIO_USER:
user = (struct user_struct *) cred->user;
if (!who)
who = cred->uid;
else if ((who != cred->uid) &&
!(user = find_user(who)))
goto out_unlock; /* No processes for this user */
do_each_thread(g, p)
if (__task_cred(p)->uid == who) {
niceval = 20 - task_nice(p);
if (niceval > retval)
retval = niceval;
}
while_each_thread(g, p);
if (who != cred->uid)
free_uid(user); /* for find_user() */
break;
}
out_unlock:
read_unlock(&tasklist_lock);
return retval;
}
/**
* emergency_restart - reboot the system
*
* Without shutting down any hardware or taking any locks
* reboot the system. This is called when we know we are in
* trouble so this is our best effort to reboot. This is
* safe to call in interrupt context.
*/
void emergency_restart(void)
{
machine_emergency_restart();
}
EXPORT_SYMBOL_GPL(emergency_restart);
void kernel_restart_prepare(char *cmd)
{
blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
system_state = SYSTEM_RESTART;
device_shutdown();
sysdev_shutdown();
}
/**
* kernel_restart - reboot the system
* @cmd: pointer to buffer containing command to execute for restart
* or %NULL
*
* Shutdown everything and perform a clean reboot.
* This is not safe to call in interrupt context.
*/
void kernel_restart(char *cmd)
{
kernel_restart_prepare(cmd);
if (!cmd)
printk(KERN_EMERG "Restarting system.\n");
else
printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
machine_restart(cmd);
}
EXPORT_SYMBOL_GPL(kernel_restart);
static void kernel_shutdown_prepare(enum system_states state)
{
blocking_notifier_call_chain(&reboot_notifier_list,
(state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
system_state = state;
device_shutdown();
}
/**
* kernel_halt - halt the system
*
* Shutdown everything and perform a clean system halt.
*/
void kernel_halt(void)
{
kernel_shutdown_prepare(SYSTEM_HALT);
sysdev_shutdown();
printk(KERN_EMERG "System halted.\n");
machine_halt();
}
EXPORT_SYMBOL_GPL(kernel_halt);
/**
* kernel_power_off - power_off the system
*
* Shutdown everything and perform a clean system power_off.
*/
void kernel_power_off(void)
{
kernel_shutdown_prepare(SYSTEM_POWER_OFF);
if (pm_power_off_prepare)
pm_power_off_prepare();
disable_nonboot_cpus();
sysdev_shutdown();
printk(KERN_EMERG "Power down.\n");
machine_power_off();
}
EXPORT_SYMBOL_GPL(kernel_power_off);
/*
* Reboot system call: for obvious reasons only root may call it,
* and even root needs to set up some magic numbers in the registers
* so that some mistake won't make this reboot the whole machine.
* You can also set the meaning of the ctrl-alt-del-key here.
*
* reboot doesn't sync: do that yourself before calling this.
*/
SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
void __user *, arg)
{
char buffer[256];
/* We only trust the superuser with rebooting the system. */
if (!capable(CAP_SYS_BOOT))
return -EPERM;
/* For safety, we require "magic" arguments. */
if (magic1 != LINUX_REBOOT_MAGIC1 ||
(magic2 != LINUX_REBOOT_MAGIC2 &&
magic2 != LINUX_REBOOT_MAGIC2A &&
magic2 != LINUX_REBOOT_MAGIC2B &&
magic2 != LINUX_REBOOT_MAGIC2C))
return -EINVAL;
/* Instead of trying to make the power_off code look like
* halt when pm_power_off is not set do it the easy way.
*/
if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
cmd = LINUX_REBOOT_CMD_HALT;
lock_kernel();
switch (cmd) {
case LINUX_REBOOT_CMD_RESTART:
kernel_restart(NULL);
break;
case LINUX_REBOOT_CMD_CAD_ON:
C_A_D = 1;
break;
case LINUX_REBOOT_CMD_CAD_OFF:
C_A_D = 0;
break;
case LINUX_REBOOT_CMD_HALT:
kernel_halt();
unlock_kernel();
do_exit(0);
break;
case LINUX_REBOOT_CMD_POWER_OFF:
kernel_power_off();
unlock_kernel();
do_exit(0);
break;
case LINUX_REBOOT_CMD_RESTART2:
if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
unlock_kernel();
return -EFAULT;
}
buffer[sizeof(buffer) - 1] = '\0';
kernel_restart(buffer);
break;
#ifdef CONFIG_KEXEC
case LINUX_REBOOT_CMD_KEXEC:
{
int ret;
ret = kernel_kexec();
unlock_kernel();
return ret;
}
#endif
#ifdef CONFIG_HIBERNATION
case LINUX_REBOOT_CMD_SW_SUSPEND:
{
int ret = hibernate();
unlock_kernel();
return ret;
}
#endif
default:
unlock_kernel();
return -EINVAL;
}
unlock_kernel();
return 0;
}
static void deferred_cad(struct work_struct *dummy)
{
kernel_restart(NULL);
}
/*
* This function gets called by ctrl-alt-del - ie the keyboard interrupt.
* As it's called within an interrupt, it may NOT sync: the only choice
* is whether to reboot at once, or just ignore the ctrl-alt-del.
*/
void ctrl_alt_del(void)
{
static DECLARE_WORK(cad_work, deferred_cad);
if (C_A_D)
schedule_work(&cad_work);
else
kill_cad_pid(SIGINT, 1);
}
/*
* Unprivileged users may change the real gid to the effective gid
* or vice versa. (BSD-style)
*
* If you set the real gid at all, or set the effective gid to a value not
* equal to the real gid, then the saved gid is set to the new effective gid.
*
* This makes it possible for a setgid program to completely drop its
* privileges, which is often a useful assertion to make when you are doing
* a security audit over a program.
*
* The general idea is that a program which uses just setregid() will be
* 100% compatible with BSD. A program which uses just setgid() will be
* 100% compatible with POSIX with saved IDs.
*
* SMP: There are not races, the GIDs are checked only by filesystem
* operations (as far as semantic preservation is concerned).
*/
SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
{
const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
old = current_cred();
retval = security_task_setgid(rgid, egid, (gid_t)-1, LSM_SETID_RE);
if (retval)
goto error;
retval = -EPERM;
if (rgid != (gid_t) -1) {
if (old->gid == rgid ||
old->egid == rgid ||
capable(CAP_SETGID))
new->gid = rgid;
else
goto error;
}
if (egid != (gid_t) -1) {
if (old->gid == egid ||
old->egid == egid ||
old->sgid == egid ||
capable(CAP_SETGID))
new->egid = egid;
else
goto error;
}
if (rgid != (gid_t) -1 ||
(egid != (gid_t) -1 && egid != old->gid))
new->sgid = new->egid;
new->fsgid = new->egid;
return commit_creds(new);
error:
abort_creds(new);
return retval;
}
/*
* setgid() is implemented like SysV w/ SAVED_IDS
*
* SMP: Same implicit races as above.
*/
SYSCALL_DEFINE1(setgid, gid_t, gid)
{
const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
old = current_cred();
retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_ID);
if (retval)
goto error;
retval = -EPERM;
if (capable(CAP_SETGID))
new->gid = new->egid = new->sgid = new->fsgid = gid;
else if (gid == old->gid || gid == old->sgid)
new->egid = new->fsgid = gid;
else
goto error;
return commit_creds(new);
error:
abort_creds(new);
return retval;
}
/*
* change the user struct in a credentials set to match the new UID
*/
static int set_user(struct cred *new)
{
struct user_struct *new_user;
new_user = alloc_uid(current_user_ns(), new->uid);
if (!new_user)
return -EAGAIN;
if (atomic_read(&new_user->processes) >=
current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
new_user != INIT_USER) {
free_uid(new_user);
return -EAGAIN;
}
free_uid(new->user);
new->user = new_user;
return 0;
}
/*
* Unprivileged users may change the real uid to the effective uid
* or vice versa. (BSD-style)
*
* If you set the real uid at all, or set the effective uid to a value not
* equal to the real uid, then the saved uid is set to the new effective uid.
*
* This makes it possible for a setuid program to completely drop its
* privileges, which is often a useful assertion to make when you are doing
* a security audit over a program.
*
* The general idea is that a program which uses just setreuid() will be
* 100% compatible with BSD. A program which uses just setuid() will be
* 100% compatible with POSIX with saved IDs.
*/
SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
{
const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
old = current_cred();
retval = security_task_setuid(ruid, euid, (uid_t)-1, LSM_SETID_RE);
if (retval)
goto error;
retval = -EPERM;
if (ruid != (uid_t) -1) {
new->uid = ruid;
if (old->uid != ruid &&
old->euid != ruid &&
!capable(CAP_SETUID))
goto error;
}
if (euid != (uid_t) -1) {
new->euid = euid;
if (old->uid != euid &&
old->euid != euid &&
old->suid != euid &&
!capable(CAP_SETUID))
goto error;
}
retval = -EAGAIN;
if (new->uid != old->uid && set_user(new) < 0)
goto error;
if (ruid != (uid_t) -1 ||
(euid != (uid_t) -1 && euid != old->uid))
new->suid = new->euid;
new->fsuid = new->euid;
retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
if (retval < 0)
goto error;
return commit_creds(new);
error:
abort_creds(new);
return retval;
}
/*
* setuid() is implemented like SysV with SAVED_IDS
*
* Note that SAVED_ID's is deficient in that a setuid root program
* like sendmail, for example, cannot set its uid to be a normal
* user and then switch back, because if you're root, setuid() sets
* the saved uid too. If you don't like this, blame the bright people
* in the POSIX committee and/or USG. Note that the BSD-style setreuid()
* will allow a root program to temporarily drop privileges and be able to
* regain them by swapping the real and effective uid.
*/
SYSCALL_DEFINE1(setuid, uid_t, uid)
{
const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
old = current_cred();
retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_ID);
if (retval)
goto error;
retval = -EPERM;
if (capable(CAP_SETUID)) {
new->suid = new->uid = uid;
if (uid != old->uid && set_user(new) < 0) {
retval = -EAGAIN;
goto error;
}
} else if (uid != old->uid && uid != new->suid) {
goto error;
}
new->fsuid = new->euid = uid;
retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
if (retval < 0)
goto error;
return commit_creds(new);
error:
abort_creds(new);
return retval;
}
/*
* This function implements a generic ability to update ruid, euid,
* and suid. This allows you to implement the 4.4 compatible seteuid().
*/
SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
{
const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES);
if (retval)
goto error;
old = current_cred();
retval = -EPERM;
if (!capable(CAP_SETUID)) {
if (ruid != (uid_t) -1 && ruid != old->uid &&
ruid != old->euid && ruid != old->suid)
goto error;
if (euid != (uid_t) -1 && euid != old->uid &&
euid != old->euid && euid != old->suid)
goto error;
if (suid != (uid_t) -1 && suid != old->uid &&
suid != old->euid && suid != old->suid)
goto error;
}
retval = -EAGAIN;
if (ruid != (uid_t) -1) {
new->uid = ruid;
if (ruid != old->uid && set_user(new) < 0)
goto error;
}
if (euid != (uid_t) -1)
new->euid = euid;
if (suid != (uid_t) -1)
new->suid = suid;
new->fsuid = new->euid;
retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
if (retval < 0)
goto error;
return commit_creds(new);
error:
abort_creds(new);
return retval;
}
SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __user *, suid)
{
const struct cred *cred = current_cred();
int retval;
if (!(retval = put_user(cred->uid, ruid)) &&
!(retval = put_user(cred->euid, euid)))
retval = put_user(cred->suid, suid);
return retval;
}
/*
* Same as above, but for rgid, egid, sgid.
*/
SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
{
const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
old = current_cred();
retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES);
if (retval)
goto error;
retval = -EPERM;
if (!capable(CAP_SETGID)) {
if (rgid != (gid_t) -1 && rgid != old->gid &&
rgid != old->egid && rgid != old->sgid)
goto error;
if (egid != (gid_t) -1 && egid != old->gid &&
egid != old->egid && egid != old->sgid)
goto error;
if (sgid != (gid_t) -1 && sgid != old->gid &&
sgid != old->egid && sgid != old->sgid)
goto error;
}
if (rgid != (gid_t) -1)
new->gid = rgid;
if (egid != (gid_t) -1)
new->egid = egid;
if (sgid != (gid_t) -1)
new->sgid = sgid;
new->fsgid = new->egid;
return commit_creds(new);
error:
abort_creds(new);
return retval;
}
SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __user *, sgid)
{
const struct cred *cred = current_cred();
int retval;
if (!(retval = put_user(cred->gid, rgid)) &&
!(retval = put_user(cred->egid, egid)))
retval = put_user(cred->sgid, sgid);
return retval;
}
/*
* "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
* is used for "access()" and for the NFS daemon (letting nfsd stay at
* whatever uid it wants to). It normally shadows "euid", except when
* explicitly set by setfsuid() or for access..
*/
SYSCALL_DEFINE1(setfsuid, uid_t, uid)
{
const struct cred *old;
struct cred *new;
uid_t old_fsuid;
new = prepare_creds();
if (!new)
return current_fsuid();
old = current_cred();
old_fsuid = old->fsuid;
if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS) < 0)
goto error;
if (uid == old->uid || uid == old->euid ||
uid == old->suid || uid == old->fsuid ||
capable(CAP_SETUID)) {
if (uid != old_fsuid) {
new->fsuid = uid;
if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
goto change_okay;
}
}
error:
abort_creds(new);
return old_fsuid;
change_okay:
commit_creds(new);
return old_fsuid;
}
/*
* Samma på svenska..
*/
SYSCALL_DEFINE1(setfsgid, gid_t, gid)
{
const struct cred *old;
struct cred *new;
gid_t old_fsgid;
new = prepare_creds();
if (!new)
return current_fsgid();
old = current_cred();
old_fsgid = old->fsgid;
if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS))
goto error;
if (gid == old->gid || gid == old->egid ||
gid == old->sgid || gid == old->fsgid ||
capable(CAP_SETGID)) {
if (gid != old_fsgid) {
new->fsgid = gid;
goto change_okay;
}
}
error:
abort_creds(new);
return old_fsgid;
change_okay:
commit_creds(new);
return old_fsgid;
}
void do_sys_times(struct tms *tms)
{
struct task_cputime cputime;
cputime_t cutime, cstime;
thread_group_cputime(current, &cputime);
spin_lock_irq(&current->sighand->siglock);
cutime = current->signal->cutime;
cstime = current->signal->cstime;
spin_unlock_irq(&current->sighand->siglock);
tms->tms_utime = cputime_to_clock_t(cputime.utime);
tms->tms_stime = cputime_to_clock_t(cputime.stime);
tms->tms_cutime = cputime_to_clock_t(cutime);
tms->tms_cstime = cputime_to_clock_t(cstime);
}
SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
{
if (tbuf) {
struct tms tmp;
do_sys_times(&tmp);
if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
return -EFAULT;
}
force_successful_syscall_return();
return (long) jiffies_64_to_clock_t(get_jiffies_64());
}
/*
* This needs some heavy checking ...
* I just haven't the stomach for it. I also don't fully
* understand sessions/pgrp etc. Let somebody who does explain it.
*
* OK, I think I have the protection semantics right.... this is really
* only important on a multi-user system anyway, to make sure one user
* can't send a signal to a process owned by another. -TYT, 12/12/91
*
* Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
* LBT 04.03.94
*/
SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
{
struct task_struct *p;
struct task_struct *group_leader = current->group_leader;
struct pid *pgrp;
int err;
if (!pid)
pid = task_pid_vnr(group_leader);
if (!pgid)
pgid = pid;
if (pgid < 0)
return -EINVAL;
/* From this point forward we keep holding onto the tasklist lock
* so that our parent does not change from under us. -DaveM
*/
write_lock_irq(&tasklist_lock);
err = -ESRCH;
p = find_task_by_vpid(pid);
if (!p)
goto out;
err = -EINVAL;
if (!thread_group_leader(p))
goto out;
if (same_thread_group(p->real_parent, group_leader)) {
err = -EPERM;
if (task_session(p) != task_session(group_leader))
goto out;
err = -EACCES;
if (p->did_exec)
goto out;
} else {
err = -ESRCH;
if (p != group_leader)
goto out;
}
err = -EPERM;
if (p->signal->leader)
goto out;
pgrp = task_pid(p);
if (pgid != pid) {
struct task_struct *g;
pgrp = find_vpid(pgid);
g = pid_task(pgrp, PIDTYPE_PGID);
if (!g || task_session(g) != task_session(group_leader))
goto out;
}
err = security_task_setpgid(p, pgid);
if (err)
goto out;
if (task_pgrp(p) != pgrp) {
change_pid(p, PIDTYPE_PGID, pgrp);
set_task_pgrp(p, pid_nr(pgrp));
}
err = 0;
out:
/* All paths lead to here, thus we are safe. -DaveM */
write_unlock_irq(&tasklist_lock);
return err;
}
SYSCALL_DEFINE1(getpgid, pid_t, pid)
{
struct task_struct *p;
struct pid *grp;
int retval;
rcu_read_lock();
if (!pid)
grp = task_pgrp(current);
else {
retval = -ESRCH;
p = find_task_by_vpid(pid);
if (!p)
goto out;
grp = task_pgrp(p);
if (!grp)
goto out;
retval = security_task_getpgid(p);
if (retval)
goto out;
}
retval = pid_vnr(grp);
out:
rcu_read_unlock();
return retval;
}
#ifdef __ARCH_WANT_SYS_GETPGRP
SYSCALL_DEFINE0(getpgrp)
{
return sys_getpgid(0);
}
#endif
SYSCALL_DEFINE1(getsid, pid_t, pid)
{
struct task_struct *p;
struct pid *sid;
int retval;
rcu_read_lock();
if (!pid)
sid = task_session(current);
else {
retval = -ESRCH;
p = find_task_by_vpid(pid);
if (!p)
goto out;
sid = task_session(p);
if (!sid)
goto out;
retval = security_task_getsid(p);
if (retval)
goto out;
}
retval = pid_vnr(sid);
out:
rcu_read_unlock();
return retval;
}
SYSCALL_DEFINE0(setsid)
{
struct task_struct *group_leader = current->group_leader;
struct pid *sid = task_pid(group_leader);
pid_t session = pid_vnr(sid);
int err = -EPERM;
write_lock_irq(&tasklist_lock);
/* Fail if I am already a session leader */
if (group_leader->signal->leader)
goto out;
/* Fail if a process group id already exists that equals the
* proposed session id.
*/
if (pid_task(sid, PIDTYPE_PGID))
goto out;
group_leader->signal->leader = 1;
__set_special_pids(sid);
proc_clear_tty(group_leader);
err = session;
out:
write_unlock_irq(&tasklist_lock);
return err;
}
/*
* Supplementary group IDs
*/
/* init to 2 - one for init_task, one to ensure it is never freed */
struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
struct group_info *groups_alloc(int gidsetsize)
{
struct group_info *group_info;
int nblocks;
int i;
nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
/* Make sure we always allocate at least one indirect block pointer */
nblocks = nblocks ? : 1;
group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
if (!group_info)
return NULL;
group_info->ngroups = gidsetsize;
group_info->nblocks = nblocks;
atomic_set(&group_info->usage, 1);
if (gidsetsize <= NGROUPS_SMALL)
group_info->blocks[0] = group_info->small_block;
else {
for (i = 0; i < nblocks; i++) {
gid_t *b;
b = (void *)__get_free_page(GFP_USER);
if (!b)
goto out_undo_partial_alloc;
group_info->blocks[i] = b;
}
}
return group_info;
out_undo_partial_alloc:
while (--i >= 0) {
free_page((unsigned long)group_info->blocks[i]);
}
kfree(group_info);
return NULL;
}
EXPORT_SYMBOL(groups_alloc);
void groups_free(struct group_info *group_info)
{
if (group_info->blocks[0] != group_info->small_block) {
int i;
for (i = 0; i < group_info->nblocks; i++)
free_page((unsigned long)group_info->blocks[i]);
}
kfree(group_info);
}
EXPORT_SYMBOL(groups_free);
/* export the group_info to a user-space array */
static int groups_to_user(gid_t __user *grouplist,
const struct group_info *group_info)
{
int i;
unsigned int count = group_info->ngroups;
for (i = 0; i < group_info->nblocks; i++) {
unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
unsigned int len = cp_count * sizeof(*grouplist);
if (copy_to_user(grouplist, group_info->blocks[i], len))
return -EFAULT;
grouplist += NGROUPS_PER_BLOCK;
count -= cp_count;
}
return 0;
}
/* fill a group_info from a user-space array - it must be allocated already */
static int groups_from_user(struct group_info *group_info,
gid_t __user *grouplist)
{
int i;
unsigned int count = group_info->ngroups;
for (i = 0; i < group_info->nblocks; i++) {
unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
unsigned int len = cp_count * sizeof(*grouplist);
if (copy_from_user(group_info->blocks[i], grouplist, len))
return -EFAULT;
grouplist += NGROUPS_PER_BLOCK;
count -= cp_count;
}
return 0;
}
/* a simple Shell sort */
static void groups_sort(struct group_info *group_info)
{
int base, max, stride;
int gidsetsize = group_info->ngroups;
for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
; /* nothing */
stride /= 3;
while (stride) {
max = gidsetsize - stride;
for (base = 0; base < max; base++) {
int left = base;
int right = left + stride;
gid_t tmp = GROUP_AT(group_info, right);
while (left >= 0 && GROUP_AT(group_info, left) > tmp) {
GROUP_AT(group_info, right) =
GROUP_AT(group_info, left);
right = left;
left -= stride;
}
GROUP_AT(group_info, right) = tmp;
}
stride /= 3;
}
}
/* a simple bsearch */
int groups_search(const struct group_info *group_info, gid_t grp)
{
unsigned int left, right;
if (!group_info)
return 0;
left = 0;
right = group_info->ngroups;
while (left < right) {
unsigned int mid = (left+right)/2;
int cmp = grp - GROUP_AT(group_info, mid);
if (cmp > 0)
left = mid + 1;
else if (cmp < 0)
right = mid;
else
return 1;
}
return 0;
}
/**
* set_groups - Change a group subscription in a set of credentials
* @new: The newly prepared set of credentials to alter
* @group_info: The group list to install
*
* Validate a group subscription and, if valid, insert it into a set
* of credentials.
*/
int set_groups(struct cred *new, struct group_info *group_info)
{
int retval;
retval = security_task_setgroups(group_info);
if (retval)
return retval;
put_group_info(new->group_info);
groups_sort(group_info);
get_group_info(group_info);
new->group_info = group_info;
return 0;
}
EXPORT_SYMBOL(set_groups);
/**
* set_current_groups - Change current's group subscription
* @group_info: The group list to impose
*
* Validate a group subscription and, if valid, impose it upon current's task
* security record.
*/
int set_current_groups(struct group_info *group_info)
{
struct cred *new;
int ret;
new = prepare_creds();
if (!new)
return -ENOMEM;
ret = set_groups(new, group_info);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
}
EXPORT_SYMBOL(set_current_groups);
SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist)
{
const struct cred *cred = current_cred();
int i;
if (gidsetsize < 0)
return -EINVAL;
/* no need to grab task_lock here; it cannot change */
i = cred->group_info->ngroups;
if (gidsetsize) {
if (i > gidsetsize) {
i = -EINVAL;
goto out;
}
if (groups_to_user(grouplist, cred->group_info)) {
i = -EFAULT;
goto out;
}
}
out:
return i;
}
/*
* SMP: Our groups are copy-on-write. We can set them safely
* without another task interfering.
*/
SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist)
{
struct group_info *group_info;
int retval;
if (!capable(CAP_SETGID))
return -EPERM;
if ((unsigned)gidsetsize > NGROUPS_MAX)
return -EINVAL;
group_info = groups_alloc(gidsetsize);
if (!group_info)
return -ENOMEM;
retval = groups_from_user(group_info, grouplist);
if (retval) {
put_group_info(group_info);
return retval;
}
retval = set_current_groups(group_info);
put_group_info(group_info);
return retval;
}
/*
* Check whether we're fsgid/egid or in the supplemental group..
*/
int in_group_p(gid_t grp)
{
const struct cred *cred = current_cred();
int retval = 1;
if (grp != cred->fsgid)
retval = groups_search(cred->group_info, grp);
return retval;
}
EXPORT_SYMBOL(in_group_p);
int in_egroup_p(gid_t grp)
{
const struct cred *cred = current_cred();
int retval = 1;
if (grp != cred->egid)
retval = groups_search(cred->group_info, grp);
return retval;
}
EXPORT_SYMBOL(in_egroup_p);
DECLARE_RWSEM(uts_sem);
SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
{
int errno = 0;
down_read(&uts_sem);
if (copy_to_user(name, utsname(), sizeof *name))
errno = -EFAULT;
up_read(&uts_sem);
return errno;
}
SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
{
int errno;
char tmp[__NEW_UTS_LEN];
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (len < 0 || len > __NEW_UTS_LEN)
return -EINVAL;
down_write(&uts_sem);
errno = -EFAULT;
if (!copy_from_user(tmp, name, len)) {
struct new_utsname *u = utsname();
memcpy(u->nodename, tmp, len);
memset(u->nodename + len, 0, sizeof(u->nodename) - len);
errno = 0;
}
up_write(&uts_sem);
return errno;
}
#ifdef __ARCH_WANT_SYS_GETHOSTNAME
SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
{
int i, errno;
struct new_utsname *u;
if (len < 0)
return -EINVAL;
down_read(&uts_sem);
u = utsname();
i = 1 + strlen(u->nodename);
if (i > len)
i = len;
errno = 0;
if (copy_to_user(name, u->nodename, i))
errno = -EFAULT;
up_read(&uts_sem);
return errno;
}
#endif
/*
* Only setdomainname; getdomainname can be implemented by calling
* uname()
*/
SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
{
int errno;
char tmp[__NEW_UTS_LEN];
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (len < 0 || len > __NEW_UTS_LEN)
return -EINVAL;
down_write(&uts_sem);
errno = -EFAULT;
if (!copy_from_user(tmp, name, len)) {
struct new_utsname *u = utsname();
memcpy(u->domainname, tmp, len);
memset(u->domainname + len, 0, sizeof(u->domainname) - len);
errno = 0;
}
up_write(&uts_sem);
return errno;
}
SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
{
if (resource >= RLIM_NLIMITS)
return -EINVAL;
else {
struct rlimit value;
task_lock(current->group_leader);
value = current->signal->rlim[resource];
task_unlock(current->group_leader);
return copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
}
}
#ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
/*
* Back compatibility for getrlimit. Needed for some apps.
*/
SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
struct rlimit __user *, rlim)
{
struct rlimit x;
if (resource >= RLIM_NLIMITS)
return -EINVAL;
task_lock(current->group_leader);
x = current->signal->rlim[resource];
task_unlock(current->group_leader);
if (x.rlim_cur > 0x7FFFFFFF)
x.rlim_cur = 0x7FFFFFFF;
if (x.rlim_max > 0x7FFFFFFF)
x.rlim_max = 0x7FFFFFFF;
return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
}
#endif
SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
{
struct rlimit new_rlim, *old_rlim;
int retval;
if (resource >= RLIM_NLIMITS)
return -EINVAL;
if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
return -EFAULT;
old_rlim = current->signal->rlim + resource;
if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
!capable(CAP_SYS_RESOURCE))
return -EPERM;
if (resource == RLIMIT_NOFILE) {
if (new_rlim.rlim_max == RLIM_INFINITY)
new_rlim.rlim_max = sysctl_nr_open;
if (new_rlim.rlim_cur == RLIM_INFINITY)
new_rlim.rlim_cur = sysctl_nr_open;
if (new_rlim.rlim_max > sysctl_nr_open)
return -EPERM;
}
if (new_rlim.rlim_cur > new_rlim.rlim_max)
return -EINVAL;
retval = security_task_setrlimit(resource, &new_rlim);
if (retval)
return retval;
if (resource == RLIMIT_CPU && new_rlim.rlim_cur == 0) {
/*
* The caller is asking for an immediate RLIMIT_CPU
* expiry. But we use the zero value to mean "it was
* never set". So let's cheat and make it one second
* instead
*/
new_rlim.rlim_cur = 1;
}
task_lock(current->group_leader);
*old_rlim = new_rlim;
task_unlock(current->group_leader);
if (resource != RLIMIT_CPU)
goto out;
/*
* RLIMIT_CPU handling. Note that the kernel fails to return an error
* code if it rejected the user's attempt to set RLIMIT_CPU. This is a
* very long-standing error, and fixing it now risks breakage of
* applications, so we live with it
*/
if (new_rlim.rlim_cur == RLIM_INFINITY)
goto out;
update_rlimit_cpu(new_rlim.rlim_cur);
out:
return 0;
}
/*
* It would make sense to put struct rusage in the task_struct,
* except that would make the task_struct be *really big*. After
* task_struct gets moved into malloc'ed memory, it would
* make sense to do this. It will make moving the rest of the information
* a lot simpler! (Which we're not doing right now because we're not
* measuring them yet).
*
* When sampling multiple threads for RUSAGE_SELF, under SMP we might have
* races with threads incrementing their own counters. But since word
* reads are atomic, we either get new values or old values and we don't
* care which for the sums. We always take the siglock to protect reading
* the c* fields from p->signal from races with exit.c updating those
* fields when reaping, so a sample either gets all the additions of a
* given child after it's reaped, or none so this sample is before reaping.
*
* Locking:
* We need to take the siglock for CHILDEREN, SELF and BOTH
* for the cases current multithreaded, non-current single threaded
* non-current multithreaded. Thread traversal is now safe with
* the siglock held.
* Strictly speaking, we donot need to take the siglock if we are current and
* single threaded, as no one else can take our signal_struct away, no one
* else can reap the children to update signal->c* counters, and no one else
* can race with the signal-> fields. If we do not take any lock, the
* signal-> fields could be read out of order while another thread was just
* exiting. So we should place a read memory barrier when we avoid the lock.
* On the writer side, write memory barrier is implied in __exit_signal
* as __exit_signal releases the siglock spinlock after updating the signal->
* fields. But we don't do this yet to keep things simple.
*
*/
static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
{
r->ru_nvcsw += t->nvcsw;
r->ru_nivcsw += t->nivcsw;
r->ru_minflt += t->min_flt;
r->ru_majflt += t->maj_flt;
r->ru_inblock += task_io_get_inblock(t);
r->ru_oublock += task_io_get_oublock(t);
}
static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
{
struct task_struct *t;
unsigned long flags;
cputime_t utime, stime;
struct task_cputime cputime;
memset((char *) r, 0, sizeof *r);
utime = stime = cputime_zero;
if (who == RUSAGE_THREAD) {
utime = task_utime(current);
stime = task_stime(current);
accumulate_thread_rusage(p, r);
goto out;
}
if (!lock_task_sighand(p, &flags))
return;
switch (who) {
case RUSAGE_BOTH:
case RUSAGE_CHILDREN:
utime = p->signal->cutime;
stime = p->signal->cstime;
r->ru_nvcsw = p->signal->cnvcsw;
r->ru_nivcsw = p->signal->cnivcsw;
r->ru_minflt = p->signal->cmin_flt;
r->ru_majflt = p->signal->cmaj_flt;
r->ru_inblock = p->signal->cinblock;
r->ru_oublock = p->signal->coublock;
if (who == RUSAGE_CHILDREN)
break;
case RUSAGE_SELF:
thread_group_cputime(p, &cputime);
utime = cputime_add(utime, cputime.utime);
stime = cputime_add(stime, cputime.stime);
r->ru_nvcsw += p->signal->nvcsw;
r->ru_nivcsw += p->signal->nivcsw;
r->ru_minflt += p->signal->min_flt;
r->ru_majflt += p->signal->maj_flt;
r->ru_inblock += p->signal->inblock;
r->ru_oublock += p->signal->oublock;
t = p;
do {
accumulate_thread_rusage(t, r);
t = next_thread(t);
} while (t != p);
break;
default:
BUG();
}
unlock_task_sighand(p, &flags);
out:
cputime_to_timeval(utime, &r->ru_utime);
cputime_to_timeval(stime, &r->ru_stime);
}
int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
{
struct rusage r;
k_getrusage(p, who, &r);
return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
}
SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
{
if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
who != RUSAGE_THREAD)
return -EINVAL;
return getrusage(current, who, ru);
}
SYSCALL_DEFINE1(umask, int, mask)
{
mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
return mask;
}
SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
unsigned long, arg4, unsigned long, arg5)
{
struct task_struct *me = current;
unsigned char comm[sizeof(me->comm)];
long error;
error = security_task_prctl(option, arg2, arg3, arg4, arg5);
if (error != -ENOSYS)
return error;
error = 0;
switch (option) {
case PR_SET_PDEATHSIG:
if (!valid_signal(arg2)) {
error = -EINVAL;
break;
}
me->pdeath_signal = arg2;
error = 0;
break;
case PR_GET_PDEATHSIG:
error = put_user(me->pdeath_signal, (int __user *)arg2);
break;
case PR_GET_DUMPABLE:
error = get_dumpable(me->mm);
break;
case PR_SET_DUMPABLE:
if (arg2 < 0 || arg2 > 1) {
error = -EINVAL;
break;
}
set_dumpable(me->mm, arg2);
error = 0;
break;
case PR_SET_UNALIGN:
error = SET_UNALIGN_CTL(me, arg2);
break;
case PR_GET_UNALIGN:
error = GET_UNALIGN_CTL(me, arg2);
break;
case PR_SET_FPEMU:
error = SET_FPEMU_CTL(me, arg2);
break;
case PR_GET_FPEMU:
error = GET_FPEMU_CTL(me, arg2);
break;
case PR_SET_FPEXC:
error = SET_FPEXC_CTL(me, arg2);
break;
case PR_GET_FPEXC:
error = GET_FPEXC_CTL(me, arg2);
break;
case PR_GET_TIMING:
error = PR_TIMING_STATISTICAL;
break;
case PR_SET_TIMING:
if (arg2 != PR_TIMING_STATISTICAL)
error = -EINVAL;
else
error = 0;
break;
case PR_SET_NAME:
comm[sizeof(me->comm)-1] = 0;
if (strncpy_from_user(comm, (char __user *)arg2,
sizeof(me->comm) - 1) < 0)
return -EFAULT;
set_task_comm(me, comm);
return 0;
case PR_GET_NAME:
get_task_comm(comm, me);
if (copy_to_user((char __user *)arg2, comm,
sizeof(comm)))
return -EFAULT;
return 0;
case PR_GET_ENDIAN:
error = GET_ENDIAN(me, arg2);
break;
case PR_SET_ENDIAN:
error = SET_ENDIAN(me, arg2);
break;
case PR_GET_SECCOMP:
error = prctl_get_seccomp();
break;
case PR_SET_SECCOMP:
error = prctl_set_seccomp(arg2);
break;
case PR_GET_TSC:
error = GET_TSC_CTL(arg2);
break;
case PR_SET_TSC:
error = SET_TSC_CTL(arg2);
break;
case PR_GET_TIMERSLACK:
error = current->timer_slack_ns;
break;
case PR_SET_TIMERSLACK:
if (arg2 <= 0)
current->timer_slack_ns =
current->default_timer_slack_ns;
else
current->timer_slack_ns = arg2;
error = 0;
break;
default:
error = -EINVAL;
break;
}
return error;
}
SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
struct getcpu_cache __user *, unused)
{
int err = 0;
int cpu = raw_smp_processor_id();
if (cpup)
err |= put_user(cpu, cpup);
if (nodep)
err |= put_user(cpu_to_node(cpu), nodep);
return err ? -EFAULT : 0;
}
char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
static void argv_cleanup(char **argv, char **envp)
{
argv_free(argv);
}
/**
* orderly_poweroff - Trigger an orderly system poweroff
* @force: force poweroff if command execution fails
*
* This may be called from any context to trigger a system shutdown.
* If the orderly shutdown fails, it will force an immediate shutdown.
*/
int orderly_poweroff(bool force)
{
int argc;
char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
static char *envp[] = {
"HOME=/",
"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
NULL
};
int ret = -ENOMEM;
struct subprocess_info *info;
if (argv == NULL) {
printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
__func__, poweroff_cmd);
goto out;
}
info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
if (info == NULL) {
argv_free(argv);
goto out;
}
call_usermodehelper_setcleanup(info, argv_cleanup);
ret = call_usermodehelper_exec(info, UMH_NO_WAIT);
out:
if (ret && force) {
printk(KERN_WARNING "Failed to start orderly shutdown: "
"forcing the issue\n");
/* I guess this should try to kick off some daemon to
sync and poweroff asap. Or not even bother syncing
if we're doing an emergency shutdown? */
emergency_sync();
kernel_power_off();
}
return ret;
}
EXPORT_SYMBOL_GPL(orderly_poweroff);
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