Root/kernel/sys.c

1/*
2 * linux/kernel/sys.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/export.h>
8#include <linux/mm.h>
9#include <linux/utsname.h>
10#include <linux/mman.h>
11#include <linux/reboot.h>
12#include <linux/prctl.h>
13#include <linux/highuid.h>
14#include <linux/fs.h>
15#include <linux/kmod.h>
16#include <linux/perf_event.h>
17#include <linux/resource.h>
18#include <linux/kernel.h>
19#include <linux/kexec.h>
20#include <linux/workqueue.h>
21#include <linux/capability.h>
22#include <linux/device.h>
23#include <linux/key.h>
24#include <linux/times.h>
25#include <linux/posix-timers.h>
26#include <linux/security.h>
27#include <linux/dcookies.h>
28#include <linux/suspend.h>
29#include <linux/tty.h>
30#include <linux/signal.h>
31#include <linux/cn_proc.h>
32#include <linux/getcpu.h>
33#include <linux/task_io_accounting_ops.h>
34#include <linux/seccomp.h>
35#include <linux/cpu.h>
36#include <linux/personality.h>
37#include <linux/ptrace.h>
38#include <linux/fs_struct.h>
39#include <linux/file.h>
40#include <linux/mount.h>
41#include <linux/gfp.h>
42#include <linux/syscore_ops.h>
43#include <linux/version.h>
44#include <linux/ctype.h>
45
46#include <linux/compat.h>
47#include <linux/syscalls.h>
48#include <linux/kprobes.h>
49#include <linux/user_namespace.h>
50
51#include <linux/kmsg_dump.h>
52/* Move somewhere else to avoid recompiling? */
53#include <generated/utsrelease.h>
54
55#include <asm/uaccess.h>
56#include <asm/io.h>
57#include <asm/unistd.h>
58
59#ifndef SET_UNALIGN_CTL
60# define SET_UNALIGN_CTL(a,b) (-EINVAL)
61#endif
62#ifndef GET_UNALIGN_CTL
63# define GET_UNALIGN_CTL(a,b) (-EINVAL)
64#endif
65#ifndef SET_FPEMU_CTL
66# define SET_FPEMU_CTL(a,b) (-EINVAL)
67#endif
68#ifndef GET_FPEMU_CTL
69# define GET_FPEMU_CTL(a,b) (-EINVAL)
70#endif
71#ifndef SET_FPEXC_CTL
72# define SET_FPEXC_CTL(a,b) (-EINVAL)
73#endif
74#ifndef GET_FPEXC_CTL
75# define GET_FPEXC_CTL(a,b) (-EINVAL)
76#endif
77#ifndef GET_ENDIAN
78# define GET_ENDIAN(a,b) (-EINVAL)
79#endif
80#ifndef SET_ENDIAN
81# define SET_ENDIAN(a,b) (-EINVAL)
82#endif
83#ifndef GET_TSC_CTL
84# define GET_TSC_CTL(a) (-EINVAL)
85#endif
86#ifndef SET_TSC_CTL
87# define SET_TSC_CTL(a) (-EINVAL)
88#endif
89
90/*
91 * this is where the system-wide overflow UID and GID are defined, for
92 * architectures that now have 32-bit UID/GID but didn't in the past
93 */
94
95int overflowuid = DEFAULT_OVERFLOWUID;
96int overflowgid = DEFAULT_OVERFLOWGID;
97
98EXPORT_SYMBOL(overflowuid);
99EXPORT_SYMBOL(overflowgid);
100
101/*
102 * the same as above, but for filesystems which can only store a 16-bit
103 * UID and GID. as such, this is needed on all architectures
104 */
105
106int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
107int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
108
109EXPORT_SYMBOL(fs_overflowuid);
110EXPORT_SYMBOL(fs_overflowgid);
111
112/*
113 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
114 */
115
116int C_A_D = 1;
117struct pid *cad_pid;
118EXPORT_SYMBOL(cad_pid);
119
120/*
121 * If set, this is used for preparing the system to power off.
122 */
123
124void (*pm_power_off_prepare)(void);
125
126/*
127 * Returns true if current's euid is same as p's uid or euid,
128 * or has CAP_SYS_NICE to p's user_ns.
129 *
130 * Called with rcu_read_lock, creds are safe
131 */
132static bool set_one_prio_perm(struct task_struct *p)
133{
134    const struct cred *cred = current_cred(), *pcred = __task_cred(p);
135
136    if (uid_eq(pcred->uid, cred->euid) ||
137        uid_eq(pcred->euid, cred->euid))
138        return true;
139    if (ns_capable(pcred->user_ns, CAP_SYS_NICE))
140        return true;
141    return false;
142}
143
144/*
145 * set the priority of a task
146 * - the caller must hold the RCU read lock
147 */
148static int set_one_prio(struct task_struct *p, int niceval, int error)
149{
150    int no_nice;
151
152    if (!set_one_prio_perm(p)) {
153        error = -EPERM;
154        goto out;
155    }
156    if (niceval < task_nice(p) && !can_nice(p, niceval)) {
157        error = -EACCES;
158        goto out;
159    }
160    no_nice = security_task_setnice(p, niceval);
161    if (no_nice) {
162        error = no_nice;
163        goto out;
164    }
165    if (error == -ESRCH)
166        error = 0;
167    set_user_nice(p, niceval);
168out:
169    return error;
170}
171
172SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
173{
174    struct task_struct *g, *p;
175    struct user_struct *user;
176    const struct cred *cred = current_cred();
177    int error = -EINVAL;
178    struct pid *pgrp;
179    kuid_t uid;
180
181    if (which > PRIO_USER || which < PRIO_PROCESS)
182        goto out;
183
184    /* normalize: avoid signed division (rounding problems) */
185    error = -ESRCH;
186    if (niceval < -20)
187        niceval = -20;
188    if (niceval > 19)
189        niceval = 19;
190
191    rcu_read_lock();
192    read_lock(&tasklist_lock);
193    switch (which) {
194        case PRIO_PROCESS:
195            if (who)
196                p = find_task_by_vpid(who);
197            else
198                p = current;
199            if (p)
200                error = set_one_prio(p, niceval, error);
201            break;
202        case PRIO_PGRP:
203            if (who)
204                pgrp = find_vpid(who);
205            else
206                pgrp = task_pgrp(current);
207            do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
208                error = set_one_prio(p, niceval, error);
209            } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
210            break;
211        case PRIO_USER:
212            uid = make_kuid(cred->user_ns, who);
213            user = cred->user;
214            if (!who)
215                uid = cred->uid;
216            else if (!uid_eq(uid, cred->uid) &&
217                 !(user = find_user(uid)))
218                goto out_unlock; /* No processes for this user */
219
220            do_each_thread(g, p) {
221                if (uid_eq(task_uid(p), uid))
222                    error = set_one_prio(p, niceval, error);
223            } while_each_thread(g, p);
224            if (!uid_eq(uid, cred->uid))
225                free_uid(user); /* For find_user() */
226            break;
227    }
228out_unlock:
229    read_unlock(&tasklist_lock);
230    rcu_read_unlock();
231out:
232    return error;
233}
234
235/*
236 * Ugh. To avoid negative return values, "getpriority()" will
237 * not return the normal nice-value, but a negated value that
238 * has been offset by 20 (ie it returns 40..1 instead of -20..19)
239 * to stay compatible.
240 */
241SYSCALL_DEFINE2(getpriority, int, which, int, who)
242{
243    struct task_struct *g, *p;
244    struct user_struct *user;
245    const struct cred *cred = current_cred();
246    long niceval, retval = -ESRCH;
247    struct pid *pgrp;
248    kuid_t uid;
249
250    if (which > PRIO_USER || which < PRIO_PROCESS)
251        return -EINVAL;
252
253    rcu_read_lock();
254    read_lock(&tasklist_lock);
255    switch (which) {
256        case PRIO_PROCESS:
257            if (who)
258                p = find_task_by_vpid(who);
259            else
260                p = current;
261            if (p) {
262                niceval = 20 - task_nice(p);
263                if (niceval > retval)
264                    retval = niceval;
265            }
266            break;
267        case PRIO_PGRP:
268            if (who)
269                pgrp = find_vpid(who);
270            else
271                pgrp = task_pgrp(current);
272            do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
273                niceval = 20 - task_nice(p);
274                if (niceval > retval)
275                    retval = niceval;
276            } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
277            break;
278        case PRIO_USER:
279            uid = make_kuid(cred->user_ns, who);
280            user = cred->user;
281            if (!who)
282                uid = cred->uid;
283            else if (!uid_eq(uid, cred->uid) &&
284                 !(user = find_user(uid)))
285                goto out_unlock; /* No processes for this user */
286
287            do_each_thread(g, p) {
288                if (uid_eq(task_uid(p), uid)) {
289                    niceval = 20 - task_nice(p);
290                    if (niceval > retval)
291                        retval = niceval;
292                }
293            } while_each_thread(g, p);
294            if (!uid_eq(uid, cred->uid))
295                free_uid(user); /* for find_user() */
296            break;
297    }
298out_unlock:
299    read_unlock(&tasklist_lock);
300    rcu_read_unlock();
301
302    return retval;
303}
304
305/**
306 * emergency_restart - reboot the system
307 *
308 * Without shutting down any hardware or taking any locks
309 * reboot the system. This is called when we know we are in
310 * trouble so this is our best effort to reboot. This is
311 * safe to call in interrupt context.
312 */
313void emergency_restart(void)
314{
315    kmsg_dump(KMSG_DUMP_EMERG);
316    machine_emergency_restart();
317}
318EXPORT_SYMBOL_GPL(emergency_restart);
319
320void kernel_restart_prepare(char *cmd)
321{
322    blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
323    system_state = SYSTEM_RESTART;
324    usermodehelper_disable();
325    device_shutdown();
326    syscore_shutdown();
327}
328
329/**
330 * register_reboot_notifier - Register function to be called at reboot time
331 * @nb: Info about notifier function to be called
332 *
333 * Registers a function with the list of functions
334 * to be called at reboot time.
335 *
336 * Currently always returns zero, as blocking_notifier_chain_register()
337 * always returns zero.
338 */
339int register_reboot_notifier(struct notifier_block *nb)
340{
341    return blocking_notifier_chain_register(&reboot_notifier_list, nb);
342}
343EXPORT_SYMBOL(register_reboot_notifier);
344
345/**
346 * unregister_reboot_notifier - Unregister previously registered reboot notifier
347 * @nb: Hook to be unregistered
348 *
349 * Unregisters a previously registered reboot
350 * notifier function.
351 *
352 * Returns zero on success, or %-ENOENT on failure.
353 */
354int unregister_reboot_notifier(struct notifier_block *nb)
355{
356    return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
357}
358EXPORT_SYMBOL(unregister_reboot_notifier);
359
360/**
361 * kernel_restart - reboot the system
362 * @cmd: pointer to buffer containing command to execute for restart
363 * or %NULL
364 *
365 * Shutdown everything and perform a clean reboot.
366 * This is not safe to call in interrupt context.
367 */
368void kernel_restart(char *cmd)
369{
370    kernel_restart_prepare(cmd);
371    if (!cmd)
372        printk(KERN_EMERG "Restarting system.\n");
373    else
374        printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
375    kmsg_dump(KMSG_DUMP_RESTART);
376    machine_restart(cmd);
377}
378EXPORT_SYMBOL_GPL(kernel_restart);
379
380static void kernel_shutdown_prepare(enum system_states state)
381{
382    blocking_notifier_call_chain(&reboot_notifier_list,
383        (state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
384    system_state = state;
385    usermodehelper_disable();
386    device_shutdown();
387}
388/**
389 * kernel_halt - halt the system
390 *
391 * Shutdown everything and perform a clean system halt.
392 */
393void kernel_halt(void)
394{
395    kernel_shutdown_prepare(SYSTEM_HALT);
396    syscore_shutdown();
397    printk(KERN_EMERG "System halted.\n");
398    kmsg_dump(KMSG_DUMP_HALT);
399    machine_halt();
400}
401
402EXPORT_SYMBOL_GPL(kernel_halt);
403
404/**
405 * kernel_power_off - power_off the system
406 *
407 * Shutdown everything and perform a clean system power_off.
408 */
409void kernel_power_off(void)
410{
411    kernel_shutdown_prepare(SYSTEM_POWER_OFF);
412    if (pm_power_off_prepare)
413        pm_power_off_prepare();
414    disable_nonboot_cpus();
415    syscore_shutdown();
416    printk(KERN_EMERG "Power down.\n");
417    kmsg_dump(KMSG_DUMP_POWEROFF);
418    machine_power_off();
419}
420EXPORT_SYMBOL_GPL(kernel_power_off);
421
422static DEFINE_MUTEX(reboot_mutex);
423
424/*
425 * Reboot system call: for obvious reasons only root may call it,
426 * and even root needs to set up some magic numbers in the registers
427 * so that some mistake won't make this reboot the whole machine.
428 * You can also set the meaning of the ctrl-alt-del-key here.
429 *
430 * reboot doesn't sync: do that yourself before calling this.
431 */
432SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
433        void __user *, arg)
434{
435    char buffer[256];
436    int ret = 0;
437
438    /* We only trust the superuser with rebooting the system. */
439    if (!capable(CAP_SYS_BOOT))
440        return -EPERM;
441
442    /* For safety, we require "magic" arguments. */
443    if (magic1 != LINUX_REBOOT_MAGIC1 ||
444        (magic2 != LINUX_REBOOT_MAGIC2 &&
445                    magic2 != LINUX_REBOOT_MAGIC2A &&
446            magic2 != LINUX_REBOOT_MAGIC2B &&
447                    magic2 != LINUX_REBOOT_MAGIC2C))
448        return -EINVAL;
449
450    /*
451     * If pid namespaces are enabled and the current task is in a child
452     * pid_namespace, the command is handled by reboot_pid_ns() which will
453     * call do_exit().
454     */
455    ret = reboot_pid_ns(task_active_pid_ns(current), cmd);
456    if (ret)
457        return ret;
458
459    /* Instead of trying to make the power_off code look like
460     * halt when pm_power_off is not set do it the easy way.
461     */
462    if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
463        cmd = LINUX_REBOOT_CMD_HALT;
464
465    mutex_lock(&reboot_mutex);
466    switch (cmd) {
467    case LINUX_REBOOT_CMD_RESTART:
468        kernel_restart(NULL);
469        break;
470
471    case LINUX_REBOOT_CMD_CAD_ON:
472        C_A_D = 1;
473        break;
474
475    case LINUX_REBOOT_CMD_CAD_OFF:
476        C_A_D = 0;
477        break;
478
479    case LINUX_REBOOT_CMD_HALT:
480        kernel_halt();
481        do_exit(0);
482        panic("cannot halt");
483
484    case LINUX_REBOOT_CMD_POWER_OFF:
485        kernel_power_off();
486        do_exit(0);
487        break;
488
489    case LINUX_REBOOT_CMD_RESTART2:
490        if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
491            ret = -EFAULT;
492            break;
493        }
494        buffer[sizeof(buffer) - 1] = '\0';
495
496        kernel_restart(buffer);
497        break;
498
499#ifdef CONFIG_KEXEC
500    case LINUX_REBOOT_CMD_KEXEC:
501        ret = kernel_kexec();
502        break;
503#endif
504
505#ifdef CONFIG_HIBERNATION
506    case LINUX_REBOOT_CMD_SW_SUSPEND:
507        ret = hibernate();
508        break;
509#endif
510
511    default:
512        ret = -EINVAL;
513        break;
514    }
515    mutex_unlock(&reboot_mutex);
516    return ret;
517}
518
519static void deferred_cad(struct work_struct *dummy)
520{
521    kernel_restart(NULL);
522}
523
524/*
525 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
526 * As it's called within an interrupt, it may NOT sync: the only choice
527 * is whether to reboot at once, or just ignore the ctrl-alt-del.
528 */
529void ctrl_alt_del(void)
530{
531    static DECLARE_WORK(cad_work, deferred_cad);
532
533    if (C_A_D)
534        schedule_work(&cad_work);
535    else
536        kill_cad_pid(SIGINT, 1);
537}
538    
539/*
540 * Unprivileged users may change the real gid to the effective gid
541 * or vice versa. (BSD-style)
542 *
543 * If you set the real gid at all, or set the effective gid to a value not
544 * equal to the real gid, then the saved gid is set to the new effective gid.
545 *
546 * This makes it possible for a setgid program to completely drop its
547 * privileges, which is often a useful assertion to make when you are doing
548 * a security audit over a program.
549 *
550 * The general idea is that a program which uses just setregid() will be
551 * 100% compatible with BSD. A program which uses just setgid() will be
552 * 100% compatible with POSIX with saved IDs.
553 *
554 * SMP: There are not races, the GIDs are checked only by filesystem
555 * operations (as far as semantic preservation is concerned).
556 */
557SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
558{
559    struct user_namespace *ns = current_user_ns();
560    const struct cred *old;
561    struct cred *new;
562    int retval;
563    kgid_t krgid, kegid;
564
565    krgid = make_kgid(ns, rgid);
566    kegid = make_kgid(ns, egid);
567
568    if ((rgid != (gid_t) -1) && !gid_valid(krgid))
569        return -EINVAL;
570    if ((egid != (gid_t) -1) && !gid_valid(kegid))
571        return -EINVAL;
572
573    new = prepare_creds();
574    if (!new)
575        return -ENOMEM;
576    old = current_cred();
577
578    retval = -EPERM;
579    if (rgid != (gid_t) -1) {
580        if (gid_eq(old->gid, krgid) ||
581            gid_eq(old->egid, krgid) ||
582            nsown_capable(CAP_SETGID))
583            new->gid = krgid;
584        else
585            goto error;
586    }
587    if (egid != (gid_t) -1) {
588        if (gid_eq(old->gid, kegid) ||
589            gid_eq(old->egid, kegid) ||
590            gid_eq(old->sgid, kegid) ||
591            nsown_capable(CAP_SETGID))
592            new->egid = kegid;
593        else
594            goto error;
595    }
596
597    if (rgid != (gid_t) -1 ||
598        (egid != (gid_t) -1 && !gid_eq(kegid, old->gid)))
599        new->sgid = new->egid;
600    new->fsgid = new->egid;
601
602    return commit_creds(new);
603
604error:
605    abort_creds(new);
606    return retval;
607}
608
609/*
610 * setgid() is implemented like SysV w/ SAVED_IDS
611 *
612 * SMP: Same implicit races as above.
613 */
614SYSCALL_DEFINE1(setgid, gid_t, gid)
615{
616    struct user_namespace *ns = current_user_ns();
617    const struct cred *old;
618    struct cred *new;
619    int retval;
620    kgid_t kgid;
621
622    kgid = make_kgid(ns, gid);
623    if (!gid_valid(kgid))
624        return -EINVAL;
625
626    new = prepare_creds();
627    if (!new)
628        return -ENOMEM;
629    old = current_cred();
630
631    retval = -EPERM;
632    if (nsown_capable(CAP_SETGID))
633        new->gid = new->egid = new->sgid = new->fsgid = kgid;
634    else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid))
635        new->egid = new->fsgid = kgid;
636    else
637        goto error;
638
639    return commit_creds(new);
640
641error:
642    abort_creds(new);
643    return retval;
644}
645
646/*
647 * change the user struct in a credentials set to match the new UID
648 */
649static int set_user(struct cred *new)
650{
651    struct user_struct *new_user;
652
653    new_user = alloc_uid(new->uid);
654    if (!new_user)
655        return -EAGAIN;
656
657    /*
658     * We don't fail in case of NPROC limit excess here because too many
659     * poorly written programs don't check set*uid() return code, assuming
660     * it never fails if called by root. We may still enforce NPROC limit
661     * for programs doing set*uid()+execve() by harmlessly deferring the
662     * failure to the execve() stage.
663     */
664    if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
665            new_user != INIT_USER)
666        current->flags |= PF_NPROC_EXCEEDED;
667    else
668        current->flags &= ~PF_NPROC_EXCEEDED;
669
670    free_uid(new->user);
671    new->user = new_user;
672    return 0;
673}
674
675/*
676 * Unprivileged users may change the real uid to the effective uid
677 * or vice versa. (BSD-style)
678 *
679 * If you set the real uid at all, or set the effective uid to a value not
680 * equal to the real uid, then the saved uid is set to the new effective uid.
681 *
682 * This makes it possible for a setuid program to completely drop its
683 * privileges, which is often a useful assertion to make when you are doing
684 * a security audit over a program.
685 *
686 * The general idea is that a program which uses just setreuid() will be
687 * 100% compatible with BSD. A program which uses just setuid() will be
688 * 100% compatible with POSIX with saved IDs.
689 */
690SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
691{
692    struct user_namespace *ns = current_user_ns();
693    const struct cred *old;
694    struct cred *new;
695    int retval;
696    kuid_t kruid, keuid;
697
698    kruid = make_kuid(ns, ruid);
699    keuid = make_kuid(ns, euid);
700
701    if ((ruid != (uid_t) -1) && !uid_valid(kruid))
702        return -EINVAL;
703    if ((euid != (uid_t) -1) && !uid_valid(keuid))
704        return -EINVAL;
705
706    new = prepare_creds();
707    if (!new)
708        return -ENOMEM;
709    old = current_cred();
710
711    retval = -EPERM;
712    if (ruid != (uid_t) -1) {
713        new->uid = kruid;
714        if (!uid_eq(old->uid, kruid) &&
715            !uid_eq(old->euid, kruid) &&
716            !nsown_capable(CAP_SETUID))
717            goto error;
718    }
719
720    if (euid != (uid_t) -1) {
721        new->euid = keuid;
722        if (!uid_eq(old->uid, keuid) &&
723            !uid_eq(old->euid, keuid) &&
724            !uid_eq(old->suid, keuid) &&
725            !nsown_capable(CAP_SETUID))
726            goto error;
727    }
728
729    if (!uid_eq(new->uid, old->uid)) {
730        retval = set_user(new);
731        if (retval < 0)
732            goto error;
733    }
734    if (ruid != (uid_t) -1 ||
735        (euid != (uid_t) -1 && !uid_eq(keuid, old->uid)))
736        new->suid = new->euid;
737    new->fsuid = new->euid;
738
739    retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
740    if (retval < 0)
741        goto error;
742
743    return commit_creds(new);
744
745error:
746    abort_creds(new);
747    return retval;
748}
749        
750/*
751 * setuid() is implemented like SysV with SAVED_IDS
752 *
753 * Note that SAVED_ID's is deficient in that a setuid root program
754 * like sendmail, for example, cannot set its uid to be a normal
755 * user and then switch back, because if you're root, setuid() sets
756 * the saved uid too. If you don't like this, blame the bright people
757 * in the POSIX committee and/or USG. Note that the BSD-style setreuid()
758 * will allow a root program to temporarily drop privileges and be able to
759 * regain them by swapping the real and effective uid.
760 */
761SYSCALL_DEFINE1(setuid, uid_t, uid)
762{
763    struct user_namespace *ns = current_user_ns();
764    const struct cred *old;
765    struct cred *new;
766    int retval;
767    kuid_t kuid;
768
769    kuid = make_kuid(ns, uid);
770    if (!uid_valid(kuid))
771        return -EINVAL;
772
773    new = prepare_creds();
774    if (!new)
775        return -ENOMEM;
776    old = current_cred();
777
778    retval = -EPERM;
779    if (nsown_capable(CAP_SETUID)) {
780        new->suid = new->uid = kuid;
781        if (!uid_eq(kuid, old->uid)) {
782            retval = set_user(new);
783            if (retval < 0)
784                goto error;
785        }
786    } else if (!uid_eq(kuid, old->uid) && !uid_eq(kuid, new->suid)) {
787        goto error;
788    }
789
790    new->fsuid = new->euid = kuid;
791
792    retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
793    if (retval < 0)
794        goto error;
795
796    return commit_creds(new);
797
798error:
799    abort_creds(new);
800    return retval;
801}
802
803
804/*
805 * This function implements a generic ability to update ruid, euid,
806 * and suid. This allows you to implement the 4.4 compatible seteuid().
807 */
808SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
809{
810    struct user_namespace *ns = current_user_ns();
811    const struct cred *old;
812    struct cred *new;
813    int retval;
814    kuid_t kruid, keuid, ksuid;
815
816    kruid = make_kuid(ns, ruid);
817    keuid = make_kuid(ns, euid);
818    ksuid = make_kuid(ns, suid);
819
820    if ((ruid != (uid_t) -1) && !uid_valid(kruid))
821        return -EINVAL;
822
823    if ((euid != (uid_t) -1) && !uid_valid(keuid))
824        return -EINVAL;
825
826    if ((suid != (uid_t) -1) && !uid_valid(ksuid))
827        return -EINVAL;
828
829    new = prepare_creds();
830    if (!new)
831        return -ENOMEM;
832
833    old = current_cred();
834
835    retval = -EPERM;
836    if (!nsown_capable(CAP_SETUID)) {
837        if (ruid != (uid_t) -1 && !uid_eq(kruid, old->uid) &&
838            !uid_eq(kruid, old->euid) && !uid_eq(kruid, old->suid))
839            goto error;
840        if (euid != (uid_t) -1 && !uid_eq(keuid, old->uid) &&
841            !uid_eq(keuid, old->euid) && !uid_eq(keuid, old->suid))
842            goto error;
843        if (suid != (uid_t) -1 && !uid_eq(ksuid, old->uid) &&
844            !uid_eq(ksuid, old->euid) && !uid_eq(ksuid, old->suid))
845            goto error;
846    }
847
848    if (ruid != (uid_t) -1) {
849        new->uid = kruid;
850        if (!uid_eq(kruid, old->uid)) {
851            retval = set_user(new);
852            if (retval < 0)
853                goto error;
854        }
855    }
856    if (euid != (uid_t) -1)
857        new->euid = keuid;
858    if (suid != (uid_t) -1)
859        new->suid = ksuid;
860    new->fsuid = new->euid;
861
862    retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
863    if (retval < 0)
864        goto error;
865
866    return commit_creds(new);
867
868error:
869    abort_creds(new);
870    return retval;
871}
872
873SYSCALL_DEFINE3(getresuid, uid_t __user *, ruidp, uid_t __user *, euidp, uid_t __user *, suidp)
874{
875    const struct cred *cred = current_cred();
876    int retval;
877    uid_t ruid, euid, suid;
878
879    ruid = from_kuid_munged(cred->user_ns, cred->uid);
880    euid = from_kuid_munged(cred->user_ns, cred->euid);
881    suid = from_kuid_munged(cred->user_ns, cred->suid);
882
883    if (!(retval = put_user(ruid, ruidp)) &&
884        !(retval = put_user(euid, euidp)))
885        retval = put_user(suid, suidp);
886
887    return retval;
888}
889
890/*
891 * Same as above, but for rgid, egid, sgid.
892 */
893SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
894{
895    struct user_namespace *ns = current_user_ns();
896    const struct cred *old;
897    struct cred *new;
898    int retval;
899    kgid_t krgid, kegid, ksgid;
900
901    krgid = make_kgid(ns, rgid);
902    kegid = make_kgid(ns, egid);
903    ksgid = make_kgid(ns, sgid);
904
905    if ((rgid != (gid_t) -1) && !gid_valid(krgid))
906        return -EINVAL;
907    if ((egid != (gid_t) -1) && !gid_valid(kegid))
908        return -EINVAL;
909    if ((sgid != (gid_t) -1) && !gid_valid(ksgid))
910        return -EINVAL;
911
912    new = prepare_creds();
913    if (!new)
914        return -ENOMEM;
915    old = current_cred();
916
917    retval = -EPERM;
918    if (!nsown_capable(CAP_SETGID)) {
919        if (rgid != (gid_t) -1 && !gid_eq(krgid, old->gid) &&
920            !gid_eq(krgid, old->egid) && !gid_eq(krgid, old->sgid))
921            goto error;
922        if (egid != (gid_t) -1 && !gid_eq(kegid, old->gid) &&
923            !gid_eq(kegid, old->egid) && !gid_eq(kegid, old->sgid))
924            goto error;
925        if (sgid != (gid_t) -1 && !gid_eq(ksgid, old->gid) &&
926            !gid_eq(ksgid, old->egid) && !gid_eq(ksgid, old->sgid))
927            goto error;
928    }
929
930    if (rgid != (gid_t) -1)
931        new->gid = krgid;
932    if (egid != (gid_t) -1)
933        new->egid = kegid;
934    if (sgid != (gid_t) -1)
935        new->sgid = ksgid;
936    new->fsgid = new->egid;
937
938    return commit_creds(new);
939
940error:
941    abort_creds(new);
942    return retval;
943}
944
945SYSCALL_DEFINE3(getresgid, gid_t __user *, rgidp, gid_t __user *, egidp, gid_t __user *, sgidp)
946{
947    const struct cred *cred = current_cred();
948    int retval;
949    gid_t rgid, egid, sgid;
950
951    rgid = from_kgid_munged(cred->user_ns, cred->gid);
952    egid = from_kgid_munged(cred->user_ns, cred->egid);
953    sgid = from_kgid_munged(cred->user_ns, cred->sgid);
954
955    if (!(retval = put_user(rgid, rgidp)) &&
956        !(retval = put_user(egid, egidp)))
957        retval = put_user(sgid, sgidp);
958
959    return retval;
960}
961
962
963/*
964 * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
965 * is used for "access()" and for the NFS daemon (letting nfsd stay at
966 * whatever uid it wants to). It normally shadows "euid", except when
967 * explicitly set by setfsuid() or for access..
968 */
969SYSCALL_DEFINE1(setfsuid, uid_t, uid)
970{
971    const struct cred *old;
972    struct cred *new;
973    uid_t old_fsuid;
974    kuid_t kuid;
975
976    old = current_cred();
977    old_fsuid = from_kuid_munged(old->user_ns, old->fsuid);
978
979    kuid = make_kuid(old->user_ns, uid);
980    if (!uid_valid(kuid))
981        return old_fsuid;
982
983    new = prepare_creds();
984    if (!new)
985        return old_fsuid;
986
987    if (uid_eq(kuid, old->uid) || uid_eq(kuid, old->euid) ||
988        uid_eq(kuid, old->suid) || uid_eq(kuid, old->fsuid) ||
989        nsown_capable(CAP_SETUID)) {
990        if (!uid_eq(kuid, old->fsuid)) {
991            new->fsuid = kuid;
992            if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
993                goto change_okay;
994        }
995    }
996
997    abort_creds(new);
998    return old_fsuid;
999
1000change_okay:
1001    commit_creds(new);
1002    return old_fsuid;
1003}
1004
1005/*
1006 * Samma på svenska..
1007 */
1008SYSCALL_DEFINE1(setfsgid, gid_t, gid)
1009{
1010    const struct cred *old;
1011    struct cred *new;
1012    gid_t old_fsgid;
1013    kgid_t kgid;
1014
1015    old = current_cred();
1016    old_fsgid = from_kgid_munged(old->user_ns, old->fsgid);
1017
1018    kgid = make_kgid(old->user_ns, gid);
1019    if (!gid_valid(kgid))
1020        return old_fsgid;
1021
1022    new = prepare_creds();
1023    if (!new)
1024        return old_fsgid;
1025
1026    if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->egid) ||
1027        gid_eq(kgid, old->sgid) || gid_eq(kgid, old->fsgid) ||
1028        nsown_capable(CAP_SETGID)) {
1029        if (!gid_eq(kgid, old->fsgid)) {
1030            new->fsgid = kgid;
1031            goto change_okay;
1032        }
1033    }
1034
1035    abort_creds(new);
1036    return old_fsgid;
1037
1038change_okay:
1039    commit_creds(new);
1040    return old_fsgid;
1041}
1042
1043void do_sys_times(struct tms *tms)
1044{
1045    cputime_t tgutime, tgstime, cutime, cstime;
1046
1047    spin_lock_irq(&current->sighand->siglock);
1048    thread_group_times(current, &tgutime, &tgstime);
1049    cutime = current->signal->cutime;
1050    cstime = current->signal->cstime;
1051    spin_unlock_irq(&current->sighand->siglock);
1052    tms->tms_utime = cputime_to_clock_t(tgutime);
1053    tms->tms_stime = cputime_to_clock_t(tgstime);
1054    tms->tms_cutime = cputime_to_clock_t(cutime);
1055    tms->tms_cstime = cputime_to_clock_t(cstime);
1056}
1057
1058SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
1059{
1060    if (tbuf) {
1061        struct tms tmp;
1062
1063        do_sys_times(&tmp);
1064        if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
1065            return -EFAULT;
1066    }
1067    force_successful_syscall_return();
1068    return (long) jiffies_64_to_clock_t(get_jiffies_64());
1069}
1070
1071/*
1072 * This needs some heavy checking ...
1073 * I just haven't the stomach for it. I also don't fully
1074 * understand sessions/pgrp etc. Let somebody who does explain it.
1075 *
1076 * OK, I think I have the protection semantics right.... this is really
1077 * only important on a multi-user system anyway, to make sure one user
1078 * can't send a signal to a process owned by another. -TYT, 12/12/91
1079 *
1080 * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
1081 * LBT 04.03.94
1082 */
1083SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
1084{
1085    struct task_struct *p;
1086    struct task_struct *group_leader = current->group_leader;
1087    struct pid *pgrp;
1088    int err;
1089
1090    if (!pid)
1091        pid = task_pid_vnr(group_leader);
1092    if (!pgid)
1093        pgid = pid;
1094    if (pgid < 0)
1095        return -EINVAL;
1096    rcu_read_lock();
1097
1098    /* From this point forward we keep holding onto the tasklist lock
1099     * so that our parent does not change from under us. -DaveM
1100     */
1101    write_lock_irq(&tasklist_lock);
1102
1103    err = -ESRCH;
1104    p = find_task_by_vpid(pid);
1105    if (!p)
1106        goto out;
1107
1108    err = -EINVAL;
1109    if (!thread_group_leader(p))
1110        goto out;
1111
1112    if (same_thread_group(p->real_parent, group_leader)) {
1113        err = -EPERM;
1114        if (task_session(p) != task_session(group_leader))
1115            goto out;
1116        err = -EACCES;
1117        if (p->did_exec)
1118            goto out;
1119    } else {
1120        err = -ESRCH;
1121        if (p != group_leader)
1122            goto out;
1123    }
1124
1125    err = -EPERM;
1126    if (p->signal->leader)
1127        goto out;
1128
1129    pgrp = task_pid(p);
1130    if (pgid != pid) {
1131        struct task_struct *g;
1132
1133        pgrp = find_vpid(pgid);
1134        g = pid_task(pgrp, PIDTYPE_PGID);
1135        if (!g || task_session(g) != task_session(group_leader))
1136            goto out;
1137    }
1138
1139    err = security_task_setpgid(p, pgid);
1140    if (err)
1141        goto out;
1142
1143    if (task_pgrp(p) != pgrp)
1144        change_pid(p, PIDTYPE_PGID, pgrp);
1145
1146    err = 0;
1147out:
1148    /* All paths lead to here, thus we are safe. -DaveM */
1149    write_unlock_irq(&tasklist_lock);
1150    rcu_read_unlock();
1151    return err;
1152}
1153
1154SYSCALL_DEFINE1(getpgid, pid_t, pid)
1155{
1156    struct task_struct *p;
1157    struct pid *grp;
1158    int retval;
1159
1160    rcu_read_lock();
1161    if (!pid)
1162        grp = task_pgrp(current);
1163    else {
1164        retval = -ESRCH;
1165        p = find_task_by_vpid(pid);
1166        if (!p)
1167            goto out;
1168        grp = task_pgrp(p);
1169        if (!grp)
1170            goto out;
1171
1172        retval = security_task_getpgid(p);
1173        if (retval)
1174            goto out;
1175    }
1176    retval = pid_vnr(grp);
1177out:
1178    rcu_read_unlock();
1179    return retval;
1180}
1181
1182#ifdef __ARCH_WANT_SYS_GETPGRP
1183
1184SYSCALL_DEFINE0(getpgrp)
1185{
1186    return sys_getpgid(0);
1187}
1188
1189#endif
1190
1191SYSCALL_DEFINE1(getsid, pid_t, pid)
1192{
1193    struct task_struct *p;
1194    struct pid *sid;
1195    int retval;
1196
1197    rcu_read_lock();
1198    if (!pid)
1199        sid = task_session(current);
1200    else {
1201        retval = -ESRCH;
1202        p = find_task_by_vpid(pid);
1203        if (!p)
1204            goto out;
1205        sid = task_session(p);
1206        if (!sid)
1207            goto out;
1208
1209        retval = security_task_getsid(p);
1210        if (retval)
1211            goto out;
1212    }
1213    retval = pid_vnr(sid);
1214out:
1215    rcu_read_unlock();
1216    return retval;
1217}
1218
1219SYSCALL_DEFINE0(setsid)
1220{
1221    struct task_struct *group_leader = current->group_leader;
1222    struct pid *sid = task_pid(group_leader);
1223    pid_t session = pid_vnr(sid);
1224    int err = -EPERM;
1225
1226    write_lock_irq(&tasklist_lock);
1227    /* Fail if I am already a session leader */
1228    if (group_leader->signal->leader)
1229        goto out;
1230
1231    /* Fail if a process group id already exists that equals the
1232     * proposed session id.
1233     */
1234    if (pid_task(sid, PIDTYPE_PGID))
1235        goto out;
1236
1237    group_leader->signal->leader = 1;
1238    __set_special_pids(sid);
1239
1240    proc_clear_tty(group_leader);
1241
1242    err = session;
1243out:
1244    write_unlock_irq(&tasklist_lock);
1245    if (err > 0) {
1246        proc_sid_connector(group_leader);
1247        sched_autogroup_create_attach(group_leader);
1248    }
1249    return err;
1250}
1251
1252DECLARE_RWSEM(uts_sem);
1253
1254#ifdef COMPAT_UTS_MACHINE
1255#define override_architecture(name) \
1256    (personality(current->personality) == PER_LINUX32 && \
1257     copy_to_user(name->machine, COMPAT_UTS_MACHINE, \
1258              sizeof(COMPAT_UTS_MACHINE)))
1259#else
1260#define override_architecture(name) 0
1261#endif
1262
1263/*
1264 * Work around broken programs that cannot handle "Linux 3.0".
1265 * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40
1266 */
1267static int override_release(char __user *release, int len)
1268{
1269    int ret = 0;
1270    char buf[65];
1271
1272    if (current->personality & UNAME26) {
1273        char *rest = UTS_RELEASE;
1274        int ndots = 0;
1275        unsigned v;
1276
1277        while (*rest) {
1278            if (*rest == '.' && ++ndots >= 3)
1279                break;
1280            if (!isdigit(*rest) && *rest != '.')
1281                break;
1282            rest++;
1283        }
1284        v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
1285        snprintf(buf, len, "2.6.%u%s", v, rest);
1286        ret = copy_to_user(release, buf, len);
1287    }
1288    return ret;
1289}
1290
1291SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
1292{
1293    int errno = 0;
1294
1295    down_read(&uts_sem);
1296    if (copy_to_user(name, utsname(), sizeof *name))
1297        errno = -EFAULT;
1298    up_read(&uts_sem);
1299
1300    if (!errno && override_release(name->release, sizeof(name->release)))
1301        errno = -EFAULT;
1302    if (!errno && override_architecture(name))
1303        errno = -EFAULT;
1304    return errno;
1305}
1306
1307#ifdef __ARCH_WANT_SYS_OLD_UNAME
1308/*
1309 * Old cruft
1310 */
1311SYSCALL_DEFINE1(uname, struct old_utsname __user *, name)
1312{
1313    int error = 0;
1314
1315    if (!name)
1316        return -EFAULT;
1317
1318    down_read(&uts_sem);
1319    if (copy_to_user(name, utsname(), sizeof(*name)))
1320        error = -EFAULT;
1321    up_read(&uts_sem);
1322
1323    if (!error && override_release(name->release, sizeof(name->release)))
1324        error = -EFAULT;
1325    if (!error && override_architecture(name))
1326        error = -EFAULT;
1327    return error;
1328}
1329
1330SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name)
1331{
1332    int error;
1333
1334    if (!name)
1335        return -EFAULT;
1336    if (!access_ok(VERIFY_WRITE, name, sizeof(struct oldold_utsname)))
1337        return -EFAULT;
1338
1339    down_read(&uts_sem);
1340    error = __copy_to_user(&name->sysname, &utsname()->sysname,
1341                   __OLD_UTS_LEN);
1342    error |= __put_user(0, name->sysname + __OLD_UTS_LEN);
1343    error |= __copy_to_user(&name->nodename, &utsname()->nodename,
1344                __OLD_UTS_LEN);
1345    error |= __put_user(0, name->nodename + __OLD_UTS_LEN);
1346    error |= __copy_to_user(&name->release, &utsname()->release,
1347                __OLD_UTS_LEN);
1348    error |= __put_user(0, name->release + __OLD_UTS_LEN);
1349    error |= __copy_to_user(&name->version, &utsname()->version,
1350                __OLD_UTS_LEN);
1351    error |= __put_user(0, name->version + __OLD_UTS_LEN);
1352    error |= __copy_to_user(&name->machine, &utsname()->machine,
1353                __OLD_UTS_LEN);
1354    error |= __put_user(0, name->machine + __OLD_UTS_LEN);
1355    up_read(&uts_sem);
1356
1357    if (!error && override_architecture(name))
1358        error = -EFAULT;
1359    if (!error && override_release(name->release, sizeof(name->release)))
1360        error = -EFAULT;
1361    return error ? -EFAULT : 0;
1362}
1363#endif
1364
1365SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
1366{
1367    int errno;
1368    char tmp[__NEW_UTS_LEN];
1369
1370    if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1371        return -EPERM;
1372
1373    if (len < 0 || len > __NEW_UTS_LEN)
1374        return -EINVAL;
1375    down_write(&uts_sem);
1376    errno = -EFAULT;
1377    if (!copy_from_user(tmp, name, len)) {
1378        struct new_utsname *u = utsname();
1379
1380        memcpy(u->nodename, tmp, len);
1381        memset(u->nodename + len, 0, sizeof(u->nodename) - len);
1382        errno = 0;
1383        uts_proc_notify(UTS_PROC_HOSTNAME);
1384    }
1385    up_write(&uts_sem);
1386    return errno;
1387}
1388
1389#ifdef __ARCH_WANT_SYS_GETHOSTNAME
1390
1391SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
1392{
1393    int i, errno;
1394    struct new_utsname *u;
1395
1396    if (len < 0)
1397        return -EINVAL;
1398    down_read(&uts_sem);
1399    u = utsname();
1400    i = 1 + strlen(u->nodename);
1401    if (i > len)
1402        i = len;
1403    errno = 0;
1404    if (copy_to_user(name, u->nodename, i))
1405        errno = -EFAULT;
1406    up_read(&uts_sem);
1407    return errno;
1408}
1409
1410#endif
1411
1412/*
1413 * Only setdomainname; getdomainname can be implemented by calling
1414 * uname()
1415 */
1416SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
1417{
1418    int errno;
1419    char tmp[__NEW_UTS_LEN];
1420
1421    if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1422        return -EPERM;
1423    if (len < 0 || len > __NEW_UTS_LEN)
1424        return -EINVAL;
1425
1426    down_write(&uts_sem);
1427    errno = -EFAULT;
1428    if (!copy_from_user(tmp, name, len)) {
1429        struct new_utsname *u = utsname();
1430
1431        memcpy(u->domainname, tmp, len);
1432        memset(u->domainname + len, 0, sizeof(u->domainname) - len);
1433        errno = 0;
1434        uts_proc_notify(UTS_PROC_DOMAINNAME);
1435    }
1436    up_write(&uts_sem);
1437    return errno;
1438}
1439
1440SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1441{
1442    struct rlimit value;
1443    int ret;
1444
1445    ret = do_prlimit(current, resource, NULL, &value);
1446    if (!ret)
1447        ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
1448
1449    return ret;
1450}
1451
1452#ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
1453
1454/*
1455 * Back compatibility for getrlimit. Needed for some apps.
1456 */
1457 
1458SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
1459        struct rlimit __user *, rlim)
1460{
1461    struct rlimit x;
1462    if (resource >= RLIM_NLIMITS)
1463        return -EINVAL;
1464
1465    task_lock(current->group_leader);
1466    x = current->signal->rlim[resource];
1467    task_unlock(current->group_leader);
1468    if (x.rlim_cur > 0x7FFFFFFF)
1469        x.rlim_cur = 0x7FFFFFFF;
1470    if (x.rlim_max > 0x7FFFFFFF)
1471        x.rlim_max = 0x7FFFFFFF;
1472    return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
1473}
1474
1475#endif
1476
1477static inline bool rlim64_is_infinity(__u64 rlim64)
1478{
1479#if BITS_PER_LONG < 64
1480    return rlim64 >= ULONG_MAX;
1481#else
1482    return rlim64 == RLIM64_INFINITY;
1483#endif
1484}
1485
1486static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64)
1487{
1488    if (rlim->rlim_cur == RLIM_INFINITY)
1489        rlim64->rlim_cur = RLIM64_INFINITY;
1490    else
1491        rlim64->rlim_cur = rlim->rlim_cur;
1492    if (rlim->rlim_max == RLIM_INFINITY)
1493        rlim64->rlim_max = RLIM64_INFINITY;
1494    else
1495        rlim64->rlim_max = rlim->rlim_max;
1496}
1497
1498static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim)
1499{
1500    if (rlim64_is_infinity(rlim64->rlim_cur))
1501        rlim->rlim_cur = RLIM_INFINITY;
1502    else
1503        rlim->rlim_cur = (unsigned long)rlim64->rlim_cur;
1504    if (rlim64_is_infinity(rlim64->rlim_max))
1505        rlim->rlim_max = RLIM_INFINITY;
1506    else
1507        rlim->rlim_max = (unsigned long)rlim64->rlim_max;
1508}
1509
1510/* make sure you are allowed to change @tsk limits before calling this */
1511int do_prlimit(struct task_struct *tsk, unsigned int resource,
1512        struct rlimit *new_rlim, struct rlimit *old_rlim)
1513{
1514    struct rlimit *rlim;
1515    int retval = 0;
1516
1517    if (resource >= RLIM_NLIMITS)
1518        return -EINVAL;
1519    if (new_rlim) {
1520        if (new_rlim->rlim_cur > new_rlim->rlim_max)
1521            return -EINVAL;
1522        if (resource == RLIMIT_NOFILE &&
1523                new_rlim->rlim_max > sysctl_nr_open)
1524            return -EPERM;
1525    }
1526
1527    /* protect tsk->signal and tsk->sighand from disappearing */
1528    read_lock(&tasklist_lock);
1529    if (!tsk->sighand) {
1530        retval = -ESRCH;
1531        goto out;
1532    }
1533
1534    rlim = tsk->signal->rlim + resource;
1535    task_lock(tsk->group_leader);
1536    if (new_rlim) {
1537        /* Keep the capable check against init_user_ns until
1538           cgroups can contain all limits */
1539        if (new_rlim->rlim_max > rlim->rlim_max &&
1540                !capable(CAP_SYS_RESOURCE))
1541            retval = -EPERM;
1542        if (!retval)
1543            retval = security_task_setrlimit(tsk->group_leader,
1544                    resource, new_rlim);
1545        if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
1546            /*
1547             * The caller is asking for an immediate RLIMIT_CPU
1548             * expiry. But we use the zero value to mean "it was
1549             * never set". So let's cheat and make it one second
1550             * instead
1551             */
1552            new_rlim->rlim_cur = 1;
1553        }
1554    }
1555    if (!retval) {
1556        if (old_rlim)
1557            *old_rlim = *rlim;
1558        if (new_rlim)
1559            *rlim = *new_rlim;
1560    }
1561    task_unlock(tsk->group_leader);
1562
1563    /*
1564     * RLIMIT_CPU handling. Note that the kernel fails to return an error
1565     * code if it rejected the user's attempt to set RLIMIT_CPU. This is a
1566     * very long-standing error, and fixing it now risks breakage of
1567     * applications, so we live with it
1568     */
1569     if (!retval && new_rlim && resource == RLIMIT_CPU &&
1570             new_rlim->rlim_cur != RLIM_INFINITY)
1571        update_rlimit_cpu(tsk, new_rlim->rlim_cur);
1572out:
1573    read_unlock(&tasklist_lock);
1574    return retval;
1575}
1576
1577/* rcu lock must be held */
1578static int check_prlimit_permission(struct task_struct *task)
1579{
1580    const struct cred *cred = current_cred(), *tcred;
1581
1582    if (current == task)
1583        return 0;
1584
1585    tcred = __task_cred(task);
1586    if (uid_eq(cred->uid, tcred->euid) &&
1587        uid_eq(cred->uid, tcred->suid) &&
1588        uid_eq(cred->uid, tcred->uid) &&
1589        gid_eq(cred->gid, tcred->egid) &&
1590        gid_eq(cred->gid, tcred->sgid) &&
1591        gid_eq(cred->gid, tcred->gid))
1592        return 0;
1593    if (ns_capable(tcred->user_ns, CAP_SYS_RESOURCE))
1594        return 0;
1595
1596    return -EPERM;
1597}
1598
1599SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
1600        const struct rlimit64 __user *, new_rlim,
1601        struct rlimit64 __user *, old_rlim)
1602{
1603    struct rlimit64 old64, new64;
1604    struct rlimit old, new;
1605    struct task_struct *tsk;
1606    int ret;
1607
1608    if (new_rlim) {
1609        if (copy_from_user(&new64, new_rlim, sizeof(new64)))
1610            return -EFAULT;
1611        rlim64_to_rlim(&new64, &new);
1612    }
1613
1614    rcu_read_lock();
1615    tsk = pid ? find_task_by_vpid(pid) : current;
1616    if (!tsk) {
1617        rcu_read_unlock();
1618        return -ESRCH;
1619    }
1620    ret = check_prlimit_permission(tsk);
1621    if (ret) {
1622        rcu_read_unlock();
1623        return ret;
1624    }
1625    get_task_struct(tsk);
1626    rcu_read_unlock();
1627
1628    ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
1629            old_rlim ? &old : NULL);
1630
1631    if (!ret && old_rlim) {
1632        rlim_to_rlim64(&old, &old64);
1633        if (copy_to_user(old_rlim, &old64, sizeof(old64)))
1634            ret = -EFAULT;
1635    }
1636
1637    put_task_struct(tsk);
1638    return ret;
1639}
1640
1641SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1642{
1643    struct rlimit new_rlim;
1644
1645    if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
1646        return -EFAULT;
1647    return do_prlimit(current, resource, &new_rlim, NULL);
1648}
1649
1650/*
1651 * It would make sense to put struct rusage in the task_struct,
1652 * except that would make the task_struct be *really big*. After
1653 * task_struct gets moved into malloc'ed memory, it would
1654 * make sense to do this. It will make moving the rest of the information
1655 * a lot simpler! (Which we're not doing right now because we're not
1656 * measuring them yet).
1657 *
1658 * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
1659 * races with threads incrementing their own counters. But since word
1660 * reads are atomic, we either get new values or old values and we don't
1661 * care which for the sums. We always take the siglock to protect reading
1662 * the c* fields from p->signal from races with exit.c updating those
1663 * fields when reaping, so a sample either gets all the additions of a
1664 * given child after it's reaped, or none so this sample is before reaping.
1665 *
1666 * Locking:
1667 * We need to take the siglock for CHILDEREN, SELF and BOTH
1668 * for the cases current multithreaded, non-current single threaded
1669 * non-current multithreaded. Thread traversal is now safe with
1670 * the siglock held.
1671 * Strictly speaking, we donot need to take the siglock if we are current and
1672 * single threaded, as no one else can take our signal_struct away, no one
1673 * else can reap the children to update signal->c* counters, and no one else
1674 * can race with the signal-> fields. If we do not take any lock, the
1675 * signal-> fields could be read out of order while another thread was just
1676 * exiting. So we should place a read memory barrier when we avoid the lock.
1677 * On the writer side, write memory barrier is implied in __exit_signal
1678 * as __exit_signal releases the siglock spinlock after updating the signal->
1679 * fields. But we don't do this yet to keep things simple.
1680 *
1681 */
1682
1683static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
1684{
1685    r->ru_nvcsw += t->nvcsw;
1686    r->ru_nivcsw += t->nivcsw;
1687    r->ru_minflt += t->min_flt;
1688    r->ru_majflt += t->maj_flt;
1689    r->ru_inblock += task_io_get_inblock(t);
1690    r->ru_oublock += task_io_get_oublock(t);
1691}
1692
1693static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
1694{
1695    struct task_struct *t;
1696    unsigned long flags;
1697    cputime_t tgutime, tgstime, utime, stime;
1698    unsigned long maxrss = 0;
1699
1700    memset((char *) r, 0, sizeof *r);
1701    utime = stime = 0;
1702
1703    if (who == RUSAGE_THREAD) {
1704        task_times(current, &utime, &stime);
1705        accumulate_thread_rusage(p, r);
1706        maxrss = p->signal->maxrss;
1707        goto out;
1708    }
1709
1710    if (!lock_task_sighand(p, &flags))
1711        return;
1712
1713    switch (who) {
1714        case RUSAGE_BOTH:
1715        case RUSAGE_CHILDREN:
1716            utime = p->signal->cutime;
1717            stime = p->signal->cstime;
1718            r->ru_nvcsw = p->signal->cnvcsw;
1719            r->ru_nivcsw = p->signal->cnivcsw;
1720            r->ru_minflt = p->signal->cmin_flt;
1721            r->ru_majflt = p->signal->cmaj_flt;
1722            r->ru_inblock = p->signal->cinblock;
1723            r->ru_oublock = p->signal->coublock;
1724            maxrss = p->signal->cmaxrss;
1725
1726            if (who == RUSAGE_CHILDREN)
1727                break;
1728
1729        case RUSAGE_SELF:
1730            thread_group_times(p, &tgutime, &tgstime);
1731            utime += tgutime;
1732            stime += tgstime;
1733            r->ru_nvcsw += p->signal->nvcsw;
1734            r->ru_nivcsw += p->signal->nivcsw;
1735            r->ru_minflt += p->signal->min_flt;
1736            r->ru_majflt += p->signal->maj_flt;
1737            r->ru_inblock += p->signal->inblock;
1738            r->ru_oublock += p->signal->oublock;
1739            if (maxrss < p->signal->maxrss)
1740                maxrss = p->signal->maxrss;
1741            t = p;
1742            do {
1743                accumulate_thread_rusage(t, r);
1744                t = next_thread(t);
1745            } while (t != p);
1746            break;
1747
1748        default:
1749            BUG();
1750    }
1751    unlock_task_sighand(p, &flags);
1752
1753out:
1754    cputime_to_timeval(utime, &r->ru_utime);
1755    cputime_to_timeval(stime, &r->ru_stime);
1756
1757    if (who != RUSAGE_CHILDREN) {
1758        struct mm_struct *mm = get_task_mm(p);
1759        if (mm) {
1760            setmax_mm_hiwater_rss(&maxrss, mm);
1761            mmput(mm);
1762        }
1763    }
1764    r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
1765}
1766
1767int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
1768{
1769    struct rusage r;
1770    k_getrusage(p, who, &r);
1771    return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
1772}
1773
1774SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
1775{
1776    if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
1777        who != RUSAGE_THREAD)
1778        return -EINVAL;
1779    return getrusage(current, who, ru);
1780}
1781
1782SYSCALL_DEFINE1(umask, int, mask)
1783{
1784    mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
1785    return mask;
1786}
1787
1788#ifdef CONFIG_CHECKPOINT_RESTORE
1789static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
1790{
1791    struct file *exe_file;
1792    struct dentry *dentry;
1793    int err;
1794
1795    exe_file = fget(fd);
1796    if (!exe_file)
1797        return -EBADF;
1798
1799    dentry = exe_file->f_path.dentry;
1800
1801    /*
1802     * Because the original mm->exe_file points to executable file, make
1803     * sure that this one is executable as well, to avoid breaking an
1804     * overall picture.
1805     */
1806    err = -EACCES;
1807    if (!S_ISREG(dentry->d_inode->i_mode) ||
1808        exe_file->f_path.mnt->mnt_flags & MNT_NOEXEC)
1809        goto exit;
1810
1811    err = inode_permission(dentry->d_inode, MAY_EXEC);
1812    if (err)
1813        goto exit;
1814
1815    down_write(&mm->mmap_sem);
1816
1817    /*
1818     * Forbid mm->exe_file change if old file still mapped.
1819     */
1820    err = -EBUSY;
1821    if (mm->exe_file) {
1822        struct vm_area_struct *vma;
1823
1824        for (vma = mm->mmap; vma; vma = vma->vm_next)
1825            if (vma->vm_file &&
1826                path_equal(&vma->vm_file->f_path,
1827                       &mm->exe_file->f_path))
1828                goto exit_unlock;
1829    }
1830
1831    /*
1832     * The symlink can be changed only once, just to disallow arbitrary
1833     * transitions malicious software might bring in. This means one
1834     * could make a snapshot over all processes running and monitor
1835     * /proc/pid/exe changes to notice unusual activity if needed.
1836     */
1837    err = -EPERM;
1838    if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
1839        goto exit_unlock;
1840
1841    err = 0;
1842    set_mm_exe_file(mm, exe_file);
1843exit_unlock:
1844    up_write(&mm->mmap_sem);
1845
1846exit:
1847    fput(exe_file);
1848    return err;
1849}
1850
1851static int prctl_set_mm(int opt, unsigned long addr,
1852            unsigned long arg4, unsigned long arg5)
1853{
1854    unsigned long rlim = rlimit(RLIMIT_DATA);
1855    struct mm_struct *mm = current->mm;
1856    struct vm_area_struct *vma;
1857    int error;
1858
1859    if (arg5 || (arg4 && opt != PR_SET_MM_AUXV))
1860        return -EINVAL;
1861
1862    if (!capable(CAP_SYS_RESOURCE))
1863        return -EPERM;
1864
1865    if (opt == PR_SET_MM_EXE_FILE)
1866        return prctl_set_mm_exe_file(mm, (unsigned int)addr);
1867
1868    if (addr >= TASK_SIZE || addr < mmap_min_addr)
1869        return -EINVAL;
1870
1871    error = -EINVAL;
1872
1873    down_read(&mm->mmap_sem);
1874    vma = find_vma(mm, addr);
1875
1876    switch (opt) {
1877    case PR_SET_MM_START_CODE:
1878        mm->start_code = addr;
1879        break;
1880    case PR_SET_MM_END_CODE:
1881        mm->end_code = addr;
1882        break;
1883    case PR_SET_MM_START_DATA:
1884        mm->start_data = addr;
1885        break;
1886    case PR_SET_MM_END_DATA:
1887        mm->end_data = addr;
1888        break;
1889
1890    case PR_SET_MM_START_BRK:
1891        if (addr <= mm->end_data)
1892            goto out;
1893
1894        if (rlim < RLIM_INFINITY &&
1895            (mm->brk - addr) +
1896            (mm->end_data - mm->start_data) > rlim)
1897            goto out;
1898
1899        mm->start_brk = addr;
1900        break;
1901
1902    case PR_SET_MM_BRK:
1903        if (addr <= mm->end_data)
1904            goto out;
1905
1906        if (rlim < RLIM_INFINITY &&
1907            (addr - mm->start_brk) +
1908            (mm->end_data - mm->start_data) > rlim)
1909            goto out;
1910
1911        mm->brk = addr;
1912        break;
1913
1914    /*
1915     * If command line arguments and environment
1916     * are placed somewhere else on stack, we can
1917     * set them up here, ARG_START/END to setup
1918     * command line argumets and ENV_START/END
1919     * for environment.
1920     */
1921    case PR_SET_MM_START_STACK:
1922    case PR_SET_MM_ARG_START:
1923    case PR_SET_MM_ARG_END:
1924    case PR_SET_MM_ENV_START:
1925    case PR_SET_MM_ENV_END:
1926        if (!vma) {
1927            error = -EFAULT;
1928            goto out;
1929        }
1930        if (opt == PR_SET_MM_START_STACK)
1931            mm->start_stack = addr;
1932        else if (opt == PR_SET_MM_ARG_START)
1933            mm->arg_start = addr;
1934        else if (opt == PR_SET_MM_ARG_END)
1935            mm->arg_end = addr;
1936        else if (opt == PR_SET_MM_ENV_START)
1937            mm->env_start = addr;
1938        else if (opt == PR_SET_MM_ENV_END)
1939            mm->env_end = addr;
1940        break;
1941
1942    /*
1943     * This doesn't move auxiliary vector itself
1944     * since it's pinned to mm_struct, but allow
1945     * to fill vector with new values. It's up
1946     * to a caller to provide sane values here
1947     * otherwise user space tools which use this
1948     * vector might be unhappy.
1949     */
1950    case PR_SET_MM_AUXV: {
1951        unsigned long user_auxv[AT_VECTOR_SIZE];
1952
1953        if (arg4 > sizeof(user_auxv))
1954            goto out;
1955        up_read(&mm->mmap_sem);
1956
1957        if (copy_from_user(user_auxv, (const void __user *)addr, arg4))
1958            return -EFAULT;
1959
1960        /* Make sure the last entry is always AT_NULL */
1961        user_auxv[AT_VECTOR_SIZE - 2] = 0;
1962        user_auxv[AT_VECTOR_SIZE - 1] = 0;
1963
1964        BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv));
1965
1966        task_lock(current);
1967        memcpy(mm->saved_auxv, user_auxv, arg4);
1968        task_unlock(current);
1969
1970        return 0;
1971    }
1972    default:
1973        goto out;
1974    }
1975
1976    error = 0;
1977out:
1978    up_read(&mm->mmap_sem);
1979    return error;
1980}
1981
1982static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
1983{
1984    return put_user(me->clear_child_tid, tid_addr);
1985}
1986
1987#else /* CONFIG_CHECKPOINT_RESTORE */
1988static int prctl_set_mm(int opt, unsigned long addr,
1989            unsigned long arg4, unsigned long arg5)
1990{
1991    return -EINVAL;
1992}
1993static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
1994{
1995    return -EINVAL;
1996}
1997#endif
1998
1999SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
2000        unsigned long, arg4, unsigned long, arg5)
2001{
2002    struct task_struct *me = current;
2003    unsigned char comm[sizeof(me->comm)];
2004    long error;
2005
2006    error = security_task_prctl(option, arg2, arg3, arg4, arg5);
2007    if (error != -ENOSYS)
2008        return error;
2009
2010    error = 0;
2011    switch (option) {
2012        case PR_SET_PDEATHSIG:
2013            if (!valid_signal(arg2)) {
2014                error = -EINVAL;
2015                break;
2016            }
2017            me->pdeath_signal = arg2;
2018            error = 0;
2019            break;
2020        case PR_GET_PDEATHSIG:
2021            error = put_user(me->pdeath_signal, (int __user *)arg2);
2022            break;
2023        case PR_GET_DUMPABLE:
2024            error = get_dumpable(me->mm);
2025            break;
2026        case PR_SET_DUMPABLE:
2027            if (arg2 < 0 || arg2 > 1) {
2028                error = -EINVAL;
2029                break;
2030            }
2031            set_dumpable(me->mm, arg2);
2032            error = 0;
2033            break;
2034
2035        case PR_SET_UNALIGN:
2036            error = SET_UNALIGN_CTL(me, arg2);
2037            break;
2038        case PR_GET_UNALIGN:
2039            error = GET_UNALIGN_CTL(me, arg2);
2040            break;
2041        case PR_SET_FPEMU:
2042            error = SET_FPEMU_CTL(me, arg2);
2043            break;
2044        case PR_GET_FPEMU:
2045            error = GET_FPEMU_CTL(me, arg2);
2046            break;
2047        case PR_SET_FPEXC:
2048            error = SET_FPEXC_CTL(me, arg2);
2049            break;
2050        case PR_GET_FPEXC:
2051            error = GET_FPEXC_CTL(me, arg2);
2052            break;
2053        case PR_GET_TIMING:
2054            error = PR_TIMING_STATISTICAL;
2055            break;
2056        case PR_SET_TIMING:
2057            if (arg2 != PR_TIMING_STATISTICAL)
2058                error = -EINVAL;
2059            else
2060                error = 0;
2061            break;
2062
2063        case PR_SET_NAME:
2064            comm[sizeof(me->comm)-1] = 0;
2065            if (strncpy_from_user(comm, (char __user *)arg2,
2066                          sizeof(me->comm) - 1) < 0)
2067                return -EFAULT;
2068            set_task_comm(me, comm);
2069            proc_comm_connector(me);
2070            return 0;
2071        case PR_GET_NAME:
2072            get_task_comm(comm, me);
2073            if (copy_to_user((char __user *)arg2, comm,
2074                     sizeof(comm)))
2075                return -EFAULT;
2076            return 0;
2077        case PR_GET_ENDIAN:
2078            error = GET_ENDIAN(me, arg2);
2079            break;
2080        case PR_SET_ENDIAN:
2081            error = SET_ENDIAN(me, arg2);
2082            break;
2083
2084        case PR_GET_SECCOMP:
2085            error = prctl_get_seccomp();
2086            break;
2087        case PR_SET_SECCOMP:
2088            error = prctl_set_seccomp(arg2, (char __user *)arg3);
2089            break;
2090        case PR_GET_TSC:
2091            error = GET_TSC_CTL(arg2);
2092            break;
2093        case PR_SET_TSC:
2094            error = SET_TSC_CTL(arg2);
2095            break;
2096        case PR_TASK_PERF_EVENTS_DISABLE:
2097            error = perf_event_task_disable();
2098            break;
2099        case PR_TASK_PERF_EVENTS_ENABLE:
2100            error = perf_event_task_enable();
2101            break;
2102        case PR_GET_TIMERSLACK:
2103            error = current->timer_slack_ns;
2104            break;
2105        case PR_SET_TIMERSLACK:
2106            if (arg2 <= 0)
2107                current->timer_slack_ns =
2108                    current->default_timer_slack_ns;
2109            else
2110                current->timer_slack_ns = arg2;
2111            error = 0;
2112            break;
2113        case PR_MCE_KILL:
2114            if (arg4 | arg5)
2115                return -EINVAL;
2116            switch (arg2) {
2117            case PR_MCE_KILL_CLEAR:
2118                if (arg3 != 0)
2119                    return -EINVAL;
2120                current->flags &= ~PF_MCE_PROCESS;
2121                break;
2122            case PR_MCE_KILL_SET:
2123                current->flags |= PF_MCE_PROCESS;
2124                if (arg3 == PR_MCE_KILL_EARLY)
2125                    current->flags |= PF_MCE_EARLY;
2126                else if (arg3 == PR_MCE_KILL_LATE)
2127                    current->flags &= ~PF_MCE_EARLY;
2128                else if (arg3 == PR_MCE_KILL_DEFAULT)
2129                    current->flags &=
2130                        ~(PF_MCE_EARLY|PF_MCE_PROCESS);
2131                else
2132                    return -EINVAL;
2133                break;
2134            default:
2135                return -EINVAL;
2136            }
2137            error = 0;
2138            break;
2139        case PR_MCE_KILL_GET:
2140            if (arg2 | arg3 | arg4 | arg5)
2141                return -EINVAL;
2142            if (current->flags & PF_MCE_PROCESS)
2143                error = (current->flags & PF_MCE_EARLY) ?
2144                    PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE;
2145            else
2146                error = PR_MCE_KILL_DEFAULT;
2147            break;
2148        case PR_SET_MM:
2149            error = prctl_set_mm(arg2, arg3, arg4, arg5);
2150            break;
2151        case PR_GET_TID_ADDRESS:
2152            error = prctl_get_tid_address(me, (int __user **)arg2);
2153            break;
2154        case PR_SET_CHILD_SUBREAPER:
2155            me->signal->is_child_subreaper = !!arg2;
2156            error = 0;
2157            break;
2158        case PR_GET_CHILD_SUBREAPER:
2159            error = put_user(me->signal->is_child_subreaper,
2160                     (int __user *) arg2);
2161            break;
2162        case PR_SET_NO_NEW_PRIVS:
2163            if (arg2 != 1 || arg3 || arg4 || arg5)
2164                return -EINVAL;
2165
2166            current->no_new_privs = 1;
2167            break;
2168        case PR_GET_NO_NEW_PRIVS:
2169            if (arg2 || arg3 || arg4 || arg5)
2170                return -EINVAL;
2171            return current->no_new_privs ? 1 : 0;
2172        default:
2173            error = -EINVAL;
2174            break;
2175    }
2176    return error;
2177}
2178
2179SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
2180        struct getcpu_cache __user *, unused)
2181{
2182    int err = 0;
2183    int cpu = raw_smp_processor_id();
2184    if (cpup)
2185        err |= put_user(cpu, cpup);
2186    if (nodep)
2187        err |= put_user(cpu_to_node(cpu), nodep);
2188    return err ? -EFAULT : 0;
2189}
2190
2191char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
2192
2193static void argv_cleanup(struct subprocess_info *info)
2194{
2195    argv_free(info->argv);
2196}
2197
2198/**
2199 * orderly_poweroff - Trigger an orderly system poweroff
2200 * @force: force poweroff if command execution fails
2201 *
2202 * This may be called from any context to trigger a system shutdown.
2203 * If the orderly shutdown fails, it will force an immediate shutdown.
2204 */
2205int orderly_poweroff(bool force)
2206{
2207    int argc;
2208    char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
2209    static char *envp[] = {
2210        "HOME=/",
2211        "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
2212        NULL
2213    };
2214    int ret = -ENOMEM;
2215
2216    if (argv == NULL) {
2217        printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
2218               __func__, poweroff_cmd);
2219        goto out;
2220    }
2221
2222    ret = call_usermodehelper_fns(argv[0], argv, envp, UMH_NO_WAIT,
2223                      NULL, argv_cleanup, NULL);
2224out:
2225    if (likely(!ret))
2226        return 0;
2227
2228    if (ret == -ENOMEM)
2229        argv_free(argv);
2230
2231    if (force) {
2232        printk(KERN_WARNING "Failed to start orderly shutdown: "
2233               "forcing the issue\n");
2234
2235        /* I guess this should try to kick off some daemon to
2236           sync and poweroff asap. Or not even bother syncing
2237           if we're doing an emergency shutdown? */
2238        emergency_sync();
2239        kernel_power_off();
2240    }
2241
2242    return ret;
2243}
2244EXPORT_SYMBOL_GPL(orderly_poweroff);
2245

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