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include: replace linux/module.h with "struct module" wherever possible
[linux-2.6/next.git] / kernel / sys.c
blob6075260f696b0b322d332c8b5d634c27a82d0268
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/gfp.h>
40 #include <linux/syscore_ops.h>
41
42 #include <linux/compat.h>
43 #include <linux/syscalls.h>
44 #include <linux/kprobes.h>
45 #include <linux/user_namespace.h>
46
47 #include <linux/kmsg_dump.h>
48
49 #include <asm/uaccess.h>
50 #include <asm/io.h>
51 #include <asm/unistd.h>
52
53 #ifndef SET_UNALIGN_CTL
54 # define SET_UNALIGN_CTL(a,b) (-EINVAL)
55 #endif
56 #ifndef GET_UNALIGN_CTL
57 # define GET_UNALIGN_CTL(a,b) (-EINVAL)
58 #endif
59 #ifndef SET_FPEMU_CTL
60 # define SET_FPEMU_CTL(a,b) (-EINVAL)
61 #endif
62 #ifndef GET_FPEMU_CTL
63 # define GET_FPEMU_CTL(a,b) (-EINVAL)
64 #endif
65 #ifndef SET_FPEXC_CTL
66 # define SET_FPEXC_CTL(a,b) (-EINVAL)
67 #endif
68 #ifndef GET_FPEXC_CTL
69 # define GET_FPEXC_CTL(a,b) (-EINVAL)
70 #endif
71 #ifndef GET_ENDIAN
72 # define GET_ENDIAN(a,b) (-EINVAL)
73 #endif
74 #ifndef SET_ENDIAN
75 # define SET_ENDIAN(a,b) (-EINVAL)
76 #endif
77 #ifndef GET_TSC_CTL
78 # define GET_TSC_CTL(a) (-EINVAL)
79 #endif
80 #ifndef SET_TSC_CTL
81 # define SET_TSC_CTL(a) (-EINVAL)
82 #endif
83
84 /*
85 * this is where the system-wide overflow UID and GID are defined, for
86 * architectures that now have 32-bit UID/GID but didn't in the past
87 */
88
89 int overflowuid = DEFAULT_OVERFLOWUID;
90 int overflowgid = DEFAULT_OVERFLOWGID;
91
92 #ifdef CONFIG_UID16
93 EXPORT_SYMBOL(overflowuid);
94 EXPORT_SYMBOL(overflowgid);
95 #endif
96
97 /*
98 * the same as above, but for filesystems which can only store a 16-bit
99 * UID and GID. as such, this is needed on all architectures
100 */
101
102 int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
103 int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
104
105 EXPORT_SYMBOL(fs_overflowuid);
106 EXPORT_SYMBOL(fs_overflowgid);
107
108 /*
109 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
110 */
111
112 int C_A_D = 1;
113 struct pid *cad_pid;
114 EXPORT_SYMBOL(cad_pid);
115
116 /*
117 * If set, this is used for preparing the system to power off.
118 */
119
120 void (*pm_power_off_prepare)(void);
121
122 /*
123 * Returns true if current's euid is same as p's uid or euid,
124 * or has CAP_SYS_NICE to p's user_ns.
125 *
126 * Called with rcu_read_lock, creds are safe
127 */
128 static bool set_one_prio_perm(struct task_struct *p)
129 {
130 const struct cred *cred = current_cred(), *pcred = __task_cred(p);
131
132 if (pcred->user->user_ns == cred->user->user_ns &&
133 (pcred->uid == cred->euid ||
134 pcred->euid == cred->euid))
135 return true;
136 if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE))
137 return true;
138 return false;
139 }
140
141 /*
142 * set the priority of a task
143 * - the caller must hold the RCU read lock
144 */
145 static int set_one_prio(struct task_struct *p, int niceval, int error)
146 {
147 int no_nice;
148
149 if (!set_one_prio_perm(p)) {
150 error = -EPERM;
151 goto out;
152 }
153 if (niceval < task_nice(p) && !can_nice(p, niceval)) {
154 error = -EACCES;
155 goto out;
156 }
157 no_nice = security_task_setnice(p, niceval);
158 if (no_nice) {
159 error = no_nice;
160 goto out;
161 }
162 if (error == -ESRCH)
163 error = 0;
164 set_user_nice(p, niceval);
165 out:
166 return error;
167 }
168
169 SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
170 {
171 struct task_struct *g, *p;
172 struct user_struct *user;
173 const struct cred *cred = current_cred();
174 int error = -EINVAL;
175 struct pid *pgrp;
176
177 if (which > PRIO_USER || which < PRIO_PROCESS)
178 goto out;
179
180 /* normalize: avoid signed division (rounding problems) */
181 error = -ESRCH;
182 if (niceval < -20)
183 niceval = -20;
184 if (niceval > 19)
185 niceval = 19;
186
187 rcu_read_lock();
188 read_lock(&tasklist_lock);
189 switch (which) {
190 case PRIO_PROCESS:
191 if (who)
192 p = find_task_by_vpid(who);
193 else
194 p = current;
195 if (p)
196 error = set_one_prio(p, niceval, error);
197 break;
198 case PRIO_PGRP:
199 if (who)
200 pgrp = find_vpid(who);
201 else
202 pgrp = task_pgrp(current);
203 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
204 error = set_one_prio(p, niceval, error);
205 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
206 break;
207 case PRIO_USER:
208 user = (struct user_struct *) cred->user;
209 if (!who)
210 who = cred->uid;
211 else if ((who != cred->uid) &&
212 !(user = find_user(who)))
213 goto out_unlock; /* No processes for this user */
214
215 do_each_thread(g, p) {
216 if (__task_cred(p)->uid == who)
217 error = set_one_prio(p, niceval, error);
218 } while_each_thread(g, p);
219 if (who != cred->uid)
220 free_uid(user); /* For find_user() */
221 break;
222 }
223 out_unlock:
224 read_unlock(&tasklist_lock);
225 rcu_read_unlock();
226 out:
227 return error;
228 }
229
230 /*
231 * Ugh. To avoid negative return values, "getpriority()" will
232 * not return the normal nice-value, but a negated value that
233 * has been offset by 20 (ie it returns 40..1 instead of -20..19)
234 * to stay compatible.
235 */
236 SYSCALL_DEFINE2(getpriority, int, which, int, who)
237 {
238 struct task_struct *g, *p;
239 struct user_struct *user;
240 const struct cred *cred = current_cred();
241 long niceval, retval = -ESRCH;
242 struct pid *pgrp;
243
244 if (which > PRIO_USER || which < PRIO_PROCESS)
245 return -EINVAL;
246
247 rcu_read_lock();
248 read_lock(&tasklist_lock);
249 switch (which) {
250 case PRIO_PROCESS:
251 if (who)
252 p = find_task_by_vpid(who);
253 else
254 p = current;
255 if (p) {
256 niceval = 20 - task_nice(p);
257 if (niceval > retval)
258 retval = niceval;
259 }
260 break;
261 case PRIO_PGRP:
262 if (who)
263 pgrp = find_vpid(who);
264 else
265 pgrp = task_pgrp(current);
266 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
267 niceval = 20 - task_nice(p);
268 if (niceval > retval)
269 retval = niceval;
270 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
271 break;
272 case PRIO_USER:
273 user = (struct user_struct *) cred->user;
274 if (!who)
275 who = cred->uid;
276 else if ((who != cred->uid) &&
277 !(user = find_user(who)))
278 goto out_unlock; /* No processes for this user */
279
280 do_each_thread(g, p) {
281 if (__task_cred(p)->uid == who) {
282 niceval = 20 - task_nice(p);
283 if (niceval > retval)
284 retval = niceval;
285 }
286 } while_each_thread(g, p);
287 if (who != cred->uid)
288 free_uid(user); /* for find_user() */
289 break;
290 }
291 out_unlock:
292 read_unlock(&tasklist_lock);
293 rcu_read_unlock();
294
295 return retval;
296 }
297
298 /**
299 * emergency_restart - reboot the system
300 *
301 * Without shutting down any hardware or taking any locks
302 * reboot the system. This is called when we know we are in
303 * trouble so this is our best effort to reboot. This is
304 * safe to call in interrupt context.
305 */
306 void emergency_restart(void)
307 {
308 kmsg_dump(KMSG_DUMP_EMERG);
309 machine_emergency_restart();
310 }
311 EXPORT_SYMBOL_GPL(emergency_restart);
312
313 void kernel_restart_prepare(char *cmd)
314 {
315 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
316 system_state = SYSTEM_RESTART;
317 usermodehelper_disable();
318 device_shutdown();
319 syscore_shutdown();
320 }
321
322 /**
323 * register_reboot_notifier - Register function to be called at reboot time
324 * @nb: Info about notifier function to be called
325 *
326 * Registers a function with the list of functions
327 * to be called at reboot time.
328 *
329 * Currently always returns zero, as blocking_notifier_chain_register()
330 * always returns zero.
331 */
332 int register_reboot_notifier(struct notifier_block *nb)
333 {
334 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
335 }
336 EXPORT_SYMBOL(register_reboot_notifier);
337
338 /**
339 * unregister_reboot_notifier - Unregister previously registered reboot notifier
340 * @nb: Hook to be unregistered
341 *
342 * Unregisters a previously registered reboot
343 * notifier function.
344 *
345 * Returns zero on success, or %-ENOENT on failure.
346 */
347 int unregister_reboot_notifier(struct notifier_block *nb)
348 {
349 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
350 }
351 EXPORT_SYMBOL(unregister_reboot_notifier);
352
353 /**
354 * kernel_restart - reboot the system
355 * @cmd: pointer to buffer containing command to execute for restart
356 * or %NULL
357 *
358 * Shutdown everything and perform a clean reboot.
359 * This is not safe to call in interrupt context.
360 */
361 void kernel_restart(char *cmd)
362 {
363 kernel_restart_prepare(cmd);
364 if (!cmd)
365 printk(KERN_EMERG "Restarting system.\n");
366 else
367 printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
368 kmsg_dump(KMSG_DUMP_RESTART);
369 machine_restart(cmd);
370 }
371 EXPORT_SYMBOL_GPL(kernel_restart);
372
373 static void kernel_shutdown_prepare(enum system_states state)
374 {
375 blocking_notifier_call_chain(&reboot_notifier_list,
376 (state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
377 system_state = state;
378 usermodehelper_disable();
379 device_shutdown();
380 }
381 /**
382 * kernel_halt - halt the system
383 *
384 * Shutdown everything and perform a clean system halt.
385 */
386 void kernel_halt(void)
387 {
388 kernel_shutdown_prepare(SYSTEM_HALT);
389 syscore_shutdown();
390 printk(KERN_EMERG "System halted.\n");
391 kmsg_dump(KMSG_DUMP_HALT);
392 machine_halt();
393 }
394
395 EXPORT_SYMBOL_GPL(kernel_halt);
396
397 /**
398 * kernel_power_off - power_off the system
399 *
400 * Shutdown everything and perform a clean system power_off.
401 */
402 void kernel_power_off(void)
403 {
404 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
405 if (pm_power_off_prepare)
406 pm_power_off_prepare();
407 disable_nonboot_cpus();
408 syscore_shutdown();
409 printk(KERN_EMERG "Power down.\n");
410 kmsg_dump(KMSG_DUMP_POWEROFF);
411 machine_power_off();
412 }
413 EXPORT_SYMBOL_GPL(kernel_power_off);
414
415 static DEFINE_MUTEX(reboot_mutex);
416
417 /*
418 * Reboot system call: for obvious reasons only root may call it,
419 * and even root needs to set up some magic numbers in the registers
420 * so that some mistake won't make this reboot the whole machine.
421 * You can also set the meaning of the ctrl-alt-del-key here.
422 *
423 * reboot doesn't sync: do that yourself before calling this.
424 */
425 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
426 void __user *, arg)
427 {
428 char buffer[256];
429 int ret = 0;
430
431 /* We only trust the superuser with rebooting the system. */
432 if (!capable(CAP_SYS_BOOT))
433 return -EPERM;
434
435 /* For safety, we require "magic" arguments. */
436 if (magic1 != LINUX_REBOOT_MAGIC1 ||
437 (magic2 != LINUX_REBOOT_MAGIC2 &&
438 magic2 != LINUX_REBOOT_MAGIC2A &&
439 magic2 != LINUX_REBOOT_MAGIC2B &&
440 magic2 != LINUX_REBOOT_MAGIC2C))
441 return -EINVAL;
442
443 /* Instead of trying to make the power_off code look like
444 * halt when pm_power_off is not set do it the easy way.
445 */
446 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
447 cmd = LINUX_REBOOT_CMD_HALT;
448
449 mutex_lock(&reboot_mutex);
450 switch (cmd) {
451 case LINUX_REBOOT_CMD_RESTART:
452 kernel_restart(NULL);
453 break;
454
455 case LINUX_REBOOT_CMD_CAD_ON:
456 C_A_D = 1;
457 break;
458
459 case LINUX_REBOOT_CMD_CAD_OFF:
460 C_A_D = 0;
461 break;
462
463 case LINUX_REBOOT_CMD_HALT:
464 kernel_halt();
465 do_exit(0);
466 panic("cannot halt");
467
468 case LINUX_REBOOT_CMD_POWER_OFF:
469 kernel_power_off();
470 do_exit(0);
471 break;
472
473 case LINUX_REBOOT_CMD_RESTART2:
474 if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
475 ret = -EFAULT;
476 break;
477 }
478 buffer[sizeof(buffer) - 1] = '\0';
479
480 kernel_restart(buffer);
481 break;
482
483 #ifdef CONFIG_KEXEC
484 case LINUX_REBOOT_CMD_KEXEC:
485 ret = kernel_kexec();
486 break;
487 #endif
488
489 #ifdef CONFIG_HIBERNATION
490 case LINUX_REBOOT_CMD_SW_SUSPEND:
491 ret = hibernate();
492 break;
493 #endif
494
495 default:
496 ret = -EINVAL;
497 break;
498 }
499 mutex_unlock(&reboot_mutex);
500 return ret;
501 }
502
503 static void deferred_cad(struct work_struct *dummy)
504 {
505 kernel_restart(NULL);
506 }
507
508 /*
509 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
510 * As it's called within an interrupt, it may NOT sync: the only choice
511 * is whether to reboot at once, or just ignore the ctrl-alt-del.
512 */
513 void ctrl_alt_del(void)
514 {
515 static DECLARE_WORK(cad_work, deferred_cad);
516
517 if (C_A_D)
518 schedule_work(&cad_work);
519 else
520 kill_cad_pid(SIGINT, 1);
521 }
522
523 /*
524 * Unprivileged users may change the real gid to the effective gid
525 * or vice versa. (BSD-style)
526 *
527 * If you set the real gid at all, or set the effective gid to a value not
528 * equal to the real gid, then the saved gid is set to the new effective gid.
529 *
530 * This makes it possible for a setgid program to completely drop its
531 * privileges, which is often a useful assertion to make when you are doing
532 * a security audit over a program.
533 *
534 * The general idea is that a program which uses just setregid() will be
535 * 100% compatible with BSD. A program which uses just setgid() will be
536 * 100% compatible with POSIX with saved IDs.
537 *
538 * SMP: There are not races, the GIDs are checked only by filesystem
539 * operations (as far as semantic preservation is concerned).
540 */
541 SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
542 {
543 const struct cred *old;
544 struct cred *new;
545 int retval;
546
547 new = prepare_creds();
548 if (!new)
549 return -ENOMEM;
550 old = current_cred();
551
552 retval = -EPERM;
553 if (rgid != (gid_t) -1) {
554 if (old->gid == rgid ||
555 old->egid == rgid ||
556 nsown_capable(CAP_SETGID))
557 new->gid = rgid;
558 else
559 goto error;
560 }
561 if (egid != (gid_t) -1) {
562 if (old->gid == egid ||
563 old->egid == egid ||
564 old->sgid == egid ||
565 nsown_capable(CAP_SETGID))
566 new->egid = egid;
567 else
568 goto error;
569 }
570
571 if (rgid != (gid_t) -1 ||
572 (egid != (gid_t) -1 && egid != old->gid))
573 new->sgid = new->egid;
574 new->fsgid = new->egid;
575
576 return commit_creds(new);
577
578 error:
579 abort_creds(new);
580 return retval;
581 }
582
583 /*
584 * setgid() is implemented like SysV w/ SAVED_IDS
585 *
586 * SMP: Same implicit races as above.
587 */
588 SYSCALL_DEFINE1(setgid, gid_t, gid)
589 {
590 const struct cred *old;
591 struct cred *new;
592 int retval;
593
594 new = prepare_creds();
595 if (!new)
596 return -ENOMEM;
597 old = current_cred();
598
599 retval = -EPERM;
600 if (nsown_capable(CAP_SETGID))
601 new->gid = new->egid = new->sgid = new->fsgid = gid;
602 else if (gid == old->gid || gid == old->sgid)
603 new->egid = new->fsgid = gid;
604 else
605 goto error;
606
607 return commit_creds(new);
608
609 error:
610 abort_creds(new);
611 return retval;
612 }
613
614 /*
615 * change the user struct in a credentials set to match the new UID
616 */
617 static int set_user(struct cred *new)
618 {
619 struct user_struct *new_user;
620
621 new_user = alloc_uid(current_user_ns(), new->uid);
622 if (!new_user)
623 return -EAGAIN;
624
625 /*
626 * We don't fail in case of NPROC limit excess here because too many
627 * poorly written programs don't check set*uid() return code, assuming
628 * it never fails if called by root. We may still enforce NPROC limit
629 * for programs doing set*uid()+execve() by harmlessly deferring the
630 * failure to the execve() stage.
631 */
632 if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
633 new_user != INIT_USER)
634 current->flags |= PF_NPROC_EXCEEDED;
635 else
636 current->flags &= ~PF_NPROC_EXCEEDED;
637
638 free_uid(new->user);
639 new->user = new_user;
640 return 0;
641 }
642
643 /*
644 * Unprivileged users may change the real uid to the effective uid
645 * or vice versa. (BSD-style)
646 *
647 * If you set the real uid at all, or set the effective uid to a value not
648 * equal to the real uid, then the saved uid is set to the new effective uid.
649 *
650 * This makes it possible for a setuid program to completely drop its
651 * privileges, which is often a useful assertion to make when you are doing
652 * a security audit over a program.
653 *
654 * The general idea is that a program which uses just setreuid() will be
655 * 100% compatible with BSD. A program which uses just setuid() will be
656 * 100% compatible with POSIX with saved IDs.
657 */
658 SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
659 {
660 const struct cred *old;
661 struct cred *new;
662 int retval;
663
664 new = prepare_creds();
665 if (!new)
666 return -ENOMEM;
667 old = current_cred();
668
669 retval = -EPERM;
670 if (ruid != (uid_t) -1) {
671 new->uid = ruid;
672 if (old->uid != ruid &&
673 old->euid != ruid &&
674 !nsown_capable(CAP_SETUID))
675 goto error;
676 }
677
678 if (euid != (uid_t) -1) {
679 new->euid = euid;
680 if (old->uid != euid &&
681 old->euid != euid &&
682 old->suid != euid &&
683 !nsown_capable(CAP_SETUID))
684 goto error;
685 }
686
687 if (new->uid != old->uid) {
688 retval = set_user(new);
689 if (retval < 0)
690 goto error;
691 }
692 if (ruid != (uid_t) -1 ||
693 (euid != (uid_t) -1 && euid != old->uid))
694 new->suid = new->euid;
695 new->fsuid = new->euid;
696
697 retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
698 if (retval < 0)
699 goto error;
700
701 return commit_creds(new);
702
703 error:
704 abort_creds(new);
705 return retval;
706 }
707
708 /*
709 * setuid() is implemented like SysV with SAVED_IDS
710 *
711 * Note that SAVED_ID's is deficient in that a setuid root program
712 * like sendmail, for example, cannot set its uid to be a normal
713 * user and then switch back, because if you're root, setuid() sets
714 * the saved uid too. If you don't like this, blame the bright people
715 * in the POSIX committee and/or USG. Note that the BSD-style setreuid()
716 * will allow a root program to temporarily drop privileges and be able to
717 * regain them by swapping the real and effective uid.
718 */
719 SYSCALL_DEFINE1(setuid, uid_t, uid)
720 {
721 const struct cred *old;
722 struct cred *new;
723 int retval;
724
725 new = prepare_creds();
726 if (!new)
727 return -ENOMEM;
728 old = current_cred();
729
730 retval = -EPERM;
731 if (nsown_capable(CAP_SETUID)) {
732 new->suid = new->uid = uid;
733 if (uid != old->uid) {
734 retval = set_user(new);
735 if (retval < 0)
736 goto error;
737 }
738 } else if (uid != old->uid && uid != new->suid) {
739 goto error;
740 }
741
742 new->fsuid = new->euid = uid;
743
744 retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
745 if (retval < 0)
746 goto error;
747
748 return commit_creds(new);
749
750 error:
751 abort_creds(new);
752 return retval;
753 }
754
755
756 /*
757 * This function implements a generic ability to update ruid, euid,
758 * and suid. This allows you to implement the 4.4 compatible seteuid().
759 */
760 SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
761 {
762 const struct cred *old;
763 struct cred *new;
764 int retval;
765
766 new = prepare_creds();
767 if (!new)
768 return -ENOMEM;
769
770 old = current_cred();
771
772 retval = -EPERM;
773 if (!nsown_capable(CAP_SETUID)) {
774 if (ruid != (uid_t) -1 && ruid != old->uid &&
775 ruid != old->euid && ruid != old->suid)
776 goto error;
777 if (euid != (uid_t) -1 && euid != old->uid &&
778 euid != old->euid && euid != old->suid)
779 goto error;
780 if (suid != (uid_t) -1 && suid != old->uid &&
781 suid != old->euid && suid != old->suid)
782 goto error;
783 }
784
785 if (ruid != (uid_t) -1) {
786 new->uid = ruid;
787 if (ruid != old->uid) {
788 retval = set_user(new);
789 if (retval < 0)
790 goto error;
791 }
792 }
793 if (euid != (uid_t) -1)
794 new->euid = euid;
795 if (suid != (uid_t) -1)
796 new->suid = suid;
797 new->fsuid = new->euid;
798
799 retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
800 if (retval < 0)
801 goto error;
802
803 return commit_creds(new);
804
805 error:
806 abort_creds(new);
807 return retval;
808 }
809
810 SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __user *, suid)
811 {
812 const struct cred *cred = current_cred();
813 int retval;
814
815 if (!(retval = put_user(cred->uid, ruid)) &&
816 !(retval = put_user(cred->euid, euid)))
817 retval = put_user(cred->suid, suid);
818
819 return retval;
820 }
821
822 /*
823 * Same as above, but for rgid, egid, sgid.
824 */
825 SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
826 {
827 const struct cred *old;
828 struct cred *new;
829 int retval;
830
831 new = prepare_creds();
832 if (!new)
833 return -ENOMEM;
834 old = current_cred();
835
836 retval = -EPERM;
837 if (!nsown_capable(CAP_SETGID)) {
838 if (rgid != (gid_t) -1 && rgid != old->gid &&
839 rgid != old->egid && rgid != old->sgid)
840 goto error;
841 if (egid != (gid_t) -1 && egid != old->gid &&
842 egid != old->egid && egid != old->sgid)
843 goto error;
844 if (sgid != (gid_t) -1 && sgid != old->gid &&
845 sgid != old->egid && sgid != old->sgid)
846 goto error;
847 }
848
849 if (rgid != (gid_t) -1)
850 new->gid = rgid;
851 if (egid != (gid_t) -1)
852 new->egid = egid;
853 if (sgid != (gid_t) -1)
854 new->sgid = sgid;
855 new->fsgid = new->egid;
856
857 return commit_creds(new);
858
859 error:
860 abort_creds(new);
861 return retval;
862 }
863
864 SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __user *, sgid)
865 {
866 const struct cred *cred = current_cred();
867 int retval;
868
869 if (!(retval = put_user(cred->gid, rgid)) &&
870 !(retval = put_user(cred->egid, egid)))
871 retval = put_user(cred->sgid, sgid);
872
873 return retval;
874 }
875
876
877 /*
878 * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
879 * is used for "access()" and for the NFS daemon (letting nfsd stay at
880 * whatever uid it wants to). It normally shadows "euid", except when
881 * explicitly set by setfsuid() or for access..
882 */
883 SYSCALL_DEFINE1(setfsuid, uid_t, uid)
884 {
885 const struct cred *old;
886 struct cred *new;
887 uid_t old_fsuid;
888
889 new = prepare_creds();
890 if (!new)
891 return current_fsuid();
892 old = current_cred();
893 old_fsuid = old->fsuid;
894
895 if (uid == old->uid || uid == old->euid ||
896 uid == old->suid || uid == old->fsuid ||
897 nsown_capable(CAP_SETUID)) {
898 if (uid != old_fsuid) {
899 new->fsuid = uid;
900 if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
901 goto change_okay;
902 }
903 }
904
905 abort_creds(new);
906 return old_fsuid;
907
908 change_okay:
909 commit_creds(new);
910 return old_fsuid;
911 }
912
913 /*
914 * Samma på svenska..
915 */
916 SYSCALL_DEFINE1(setfsgid, gid_t, gid)
917 {
918 const struct cred *old;
919 struct cred *new;
920 gid_t old_fsgid;
921
922 new = prepare_creds();
923 if (!new)
924 return current_fsgid();
925 old = current_cred();
926 old_fsgid = old->fsgid;
927
928 if (gid == old->gid || gid == old->egid ||
929 gid == old->sgid || gid == old->fsgid ||
930 nsown_capable(CAP_SETGID)) {
931 if (gid != old_fsgid) {
932 new->fsgid = gid;
933 goto change_okay;
934 }
935 }
936
937 abort_creds(new);
938 return old_fsgid;
939
940 change_okay:
941 commit_creds(new);
942 return old_fsgid;
943 }
944
945 void do_sys_times(struct tms *tms)
946 {
947 cputime_t tgutime, tgstime, cutime, cstime;
948
949 spin_lock_irq(&current->sighand->siglock);
950 thread_group_times(current, &tgutime, &tgstime);
951 cutime = current->signal->cutime;
952 cstime = current->signal->cstime;
953 spin_unlock_irq(&current->sighand->siglock);
954 tms->tms_utime = cputime_to_clock_t(tgutime);
955 tms->tms_stime = cputime_to_clock_t(tgstime);
956 tms->tms_cutime = cputime_to_clock_t(cutime);
957 tms->tms_cstime = cputime_to_clock_t(cstime);
958 }
959
960 SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
961 {
962 if (tbuf) {
963 struct tms tmp;
964
965 do_sys_times(&tmp);
966 if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
967 return -EFAULT;
968 }
969 force_successful_syscall_return();
970 return (long) jiffies_64_to_clock_t(get_jiffies_64());
971 }
972
973 /*
974 * This needs some heavy checking ...
975 * I just haven't the stomach for it. I also don't fully
976 * understand sessions/pgrp etc. Let somebody who does explain it.
977 *
978 * OK, I think I have the protection semantics right.... this is really
979 * only important on a multi-user system anyway, to make sure one user
980 * can't send a signal to a process owned by another. -TYT, 12/12/91
981 *
982 * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
983 * LBT 04.03.94
984 */
985 SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
986 {
987 struct task_struct *p;
988 struct task_struct *group_leader = current->group_leader;
989 struct pid *pgrp;
990 int err;
991
992 if (!pid)
993 pid = task_pid_vnr(group_leader);
994 if (!pgid)
995 pgid = pid;
996 if (pgid < 0)
997 return -EINVAL;
998 rcu_read_lock();
999
1000 /* From this point forward we keep holding onto the tasklist lock
1001 * so that our parent does not change from under us. -DaveM
1002 */
1003 write_lock_irq(&tasklist_lock);
1004
1005 err = -ESRCH;
1006 p = find_task_by_vpid(pid);
1007 if (!p)
1008 goto out;
1009
1010 err = -EINVAL;
1011 if (!thread_group_leader(p))
1012 goto out;
1013
1014 if (same_thread_group(p->real_parent, group_leader)) {
1015 err = -EPERM;
1016 if (task_session(p) != task_session(group_leader))
1017 goto out;
1018 err = -EACCES;
1019 if (p->did_exec)
1020 goto out;
1021 } else {
1022 err = -ESRCH;
1023 if (p != group_leader)
1024 goto out;
1025 }
1026
1027 err = -EPERM;
1028 if (p->signal->leader)
1029 goto out;
1030
1031 pgrp = task_pid(p);
1032 if (pgid != pid) {
1033 struct task_struct *g;
1034
1035 pgrp = find_vpid(pgid);
1036 g = pid_task(pgrp, PIDTYPE_PGID);
1037 if (!g || task_session(g) != task_session(group_leader))
1038 goto out;
1039 }
1040
1041 err = security_task_setpgid(p, pgid);
1042 if (err)
1043 goto out;
1044
1045 if (task_pgrp(p) != pgrp)
1046 change_pid(p, PIDTYPE_PGID, pgrp);
1047
1048 err = 0;
1049 out:
1050 /* All paths lead to here, thus we are safe. -DaveM */
1051 write_unlock_irq(&tasklist_lock);
1052 rcu_read_unlock();
1053 return err;
1054 }
1055
1056 SYSCALL_DEFINE1(getpgid, pid_t, pid)
1057 {
1058 struct task_struct *p;
1059 struct pid *grp;
1060 int retval;
1061
1062 rcu_read_lock();
1063 if (!pid)
1064 grp = task_pgrp(current);
1065 else {
1066 retval = -ESRCH;
1067 p = find_task_by_vpid(pid);
1068 if (!p)
1069 goto out;
1070 grp = task_pgrp(p);
1071 if (!grp)
1072 goto out;
1073
1074 retval = security_task_getpgid(p);
1075 if (retval)
1076 goto out;
1077 }
1078 retval = pid_vnr(grp);
1079 out:
1080 rcu_read_unlock();
1081 return retval;
1082 }
1083
1084 #ifdef __ARCH_WANT_SYS_GETPGRP
1085
1086 SYSCALL_DEFINE0(getpgrp)
1087 {
1088 return sys_getpgid(0);
1089 }
1090
1091 #endif
1092
1093 SYSCALL_DEFINE1(getsid, pid_t, pid)
1094 {
1095 struct task_struct *p;
1096 struct pid *sid;
1097 int retval;
1098
1099 rcu_read_lock();
1100 if (!pid)
1101 sid = task_session(current);
1102 else {
1103 retval = -ESRCH;
1104 p = find_task_by_vpid(pid);
1105 if (!p)
1106 goto out;
1107 sid = task_session(p);
1108 if (!sid)
1109 goto out;
1110
1111 retval = security_task_getsid(p);
1112 if (retval)
1113 goto out;
1114 }
1115 retval = pid_vnr(sid);
1116 out:
1117 rcu_read_unlock();
1118 return retval;
1119 }
1120
1121 SYSCALL_DEFINE0(setsid)
1122 {
1123 struct task_struct *group_leader = current->group_leader;
1124 struct pid *sid = task_pid(group_leader);
1125 pid_t session = pid_vnr(sid);
1126 int err = -EPERM;
1127
1128 write_lock_irq(&tasklist_lock);
1129 /* Fail if I am already a session leader */
1130 if (group_leader->signal->leader)
1131 goto out;
1132
1133 /* Fail if a process group id already exists that equals the
1134 * proposed session id.
1135 */
1136 if (pid_task(sid, PIDTYPE_PGID))
1137 goto out;
1138
1139 group_leader->signal->leader = 1;
1140 __set_special_pids(sid);
1141
1142 proc_clear_tty(group_leader);
1143
1144 err = session;
1145 out:
1146 write_unlock_irq(&tasklist_lock);
1147 if (err > 0) {
1148 proc_sid_connector(group_leader);
1149 sched_autogroup_create_attach(group_leader);
1150 }
1151 return err;
1152 }
1153
1154 DECLARE_RWSEM(uts_sem);
1155
1156 #ifdef COMPAT_UTS_MACHINE
1157 #define override_architecture(name) \
1158 (personality(current->personality) == PER_LINUX32 && \
1159 copy_to_user(name->machine, COMPAT_UTS_MACHINE, \
1160 sizeof(COMPAT_UTS_MACHINE)))
1161 #else
1162 #define override_architecture(name) 0
1163 #endif
1164
1165 SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
1166 {
1167 int errno = 0;
1168
1169 down_read(&uts_sem);
1170 if (copy_to_user(name, utsname(), sizeof *name))
1171 errno = -EFAULT;
1172 up_read(&uts_sem);
1173
1174 if (!errno && override_architecture(name))
1175 errno = -EFAULT;
1176 return errno;
1177 }
1178
1179 #ifdef __ARCH_WANT_SYS_OLD_UNAME
1180 /*
1181 * Old cruft
1182 */
1183 SYSCALL_DEFINE1(uname, struct old_utsname __user *, name)
1184 {
1185 int error = 0;
1186
1187 if (!name)
1188 return -EFAULT;
1189
1190 down_read(&uts_sem);
1191 if (copy_to_user(name, utsname(), sizeof(*name)))
1192 error = -EFAULT;
1193 up_read(&uts_sem);
1194
1195 if (!error && override_architecture(name))
1196 error = -EFAULT;
1197 return error;
1198 }
1199
1200 SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name)
1201 {
1202 int error;
1203
1204 if (!name)
1205 return -EFAULT;
1206 if (!access_ok(VERIFY_WRITE, name, sizeof(struct oldold_utsname)))
1207 return -EFAULT;
1208
1209 down_read(&uts_sem);
1210 error = __copy_to_user(&name->sysname, &utsname()->sysname,
1211 __OLD_UTS_LEN);
1212 error |= __put_user(0, name->sysname + __OLD_UTS_LEN);
1213 error |= __copy_to_user(&name->nodename, &utsname()->nodename,
1214 __OLD_UTS_LEN);
1215 error |= __put_user(0, name->nodename + __OLD_UTS_LEN);
1216 error |= __copy_to_user(&name->release, &utsname()->release,
1217 __OLD_UTS_LEN);
1218 error |= __put_user(0, name->release + __OLD_UTS_LEN);
1219 error |= __copy_to_user(&name->version, &utsname()->version,
1220 __OLD_UTS_LEN);
1221 error |= __put_user(0, name->version + __OLD_UTS_LEN);
1222 error |= __copy_to_user(&name->machine, &utsname()->machine,
1223 __OLD_UTS_LEN);
1224 error |= __put_user(0, name->machine + __OLD_UTS_LEN);
1225 up_read(&uts_sem);
1226
1227 if (!error && override_architecture(name))
1228 error = -EFAULT;
1229 return error ? -EFAULT : 0;
1230 }
1231 #endif
1232
1233 SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
1234 {
1235 int errno;
1236 char tmp[__NEW_UTS_LEN];
1237
1238 if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1239 return -EPERM;
1240
1241 if (len < 0 || len > __NEW_UTS_LEN)
1242 return -EINVAL;
1243 down_write(&uts_sem);
1244 errno = -EFAULT;
1245 if (!copy_from_user(tmp, name, len)) {
1246 struct new_utsname *u = utsname();
1247
1248 memcpy(u->nodename, tmp, len);
1249 memset(u->nodename + len, 0, sizeof(u->nodename) - len);
1250 errno = 0;
1251 }
1252 up_write(&uts_sem);
1253 return errno;
1254 }
1255
1256 #ifdef __ARCH_WANT_SYS_GETHOSTNAME
1257
1258 SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
1259 {
1260 int i, errno;
1261 struct new_utsname *u;
1262
1263 if (len < 0)
1264 return -EINVAL;
1265 down_read(&uts_sem);
1266 u = utsname();
1267 i = 1 + strlen(u->nodename);
1268 if (i > len)
1269 i = len;
1270 errno = 0;
1271 if (copy_to_user(name, u->nodename, i))
1272 errno = -EFAULT;
1273 up_read(&uts_sem);
1274 return errno;
1275 }
1276
1277 #endif
1278
1279 /*
1280 * Only setdomainname; getdomainname can be implemented by calling
1281 * uname()
1282 */
1283 SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
1284 {
1285 int errno;
1286 char tmp[__NEW_UTS_LEN];
1287
1288 if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1289 return -EPERM;
1290 if (len < 0 || len > __NEW_UTS_LEN)
1291 return -EINVAL;
1292
1293 down_write(&uts_sem);
1294 errno = -EFAULT;
1295 if (!copy_from_user(tmp, name, len)) {
1296 struct new_utsname *u = utsname();
1297
1298 memcpy(u->domainname, tmp, len);
1299 memset(u->domainname + len, 0, sizeof(u->domainname) - len);
1300 errno = 0;
1301 }
1302 up_write(&uts_sem);
1303 return errno;
1304 }
1305
1306 SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1307 {
1308 struct rlimit value;
1309 int ret;
1310
1311 ret = do_prlimit(current, resource, NULL, &value);
1312 if (!ret)
1313 ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
1314
1315 return ret;
1316 }
1317
1318 #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
1319
1320 /*
1321 * Back compatibility for getrlimit. Needed for some apps.
1322 */
1323
1324 SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
1325 struct rlimit __user *, rlim)
1326 {
1327 struct rlimit x;
1328 if (resource >= RLIM_NLIMITS)
1329 return -EINVAL;
1330
1331 task_lock(current->group_leader);
1332 x = current->signal->rlim[resource];
1333 task_unlock(current->group_leader);
1334 if (x.rlim_cur > 0x7FFFFFFF)
1335 x.rlim_cur = 0x7FFFFFFF;
1336 if (x.rlim_max > 0x7FFFFFFF)
1337 x.rlim_max = 0x7FFFFFFF;
1338 return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
1339 }
1340
1341 #endif
1342
1343 static inline bool rlim64_is_infinity(__u64 rlim64)
1344 {
1345 #if BITS_PER_LONG < 64
1346 return rlim64 >= ULONG_MAX;
1347 #else
1348 return rlim64 == RLIM64_INFINITY;
1349 #endif
1350 }
1351
1352 static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64)
1353 {
1354 if (rlim->rlim_cur == RLIM_INFINITY)
1355 rlim64->rlim_cur = RLIM64_INFINITY;
1356 else
1357 rlim64->rlim_cur = rlim->rlim_cur;
1358 if (rlim->rlim_max == RLIM_INFINITY)
1359 rlim64->rlim_max = RLIM64_INFINITY;
1360 else
1361 rlim64->rlim_max = rlim->rlim_max;
1362 }
1363
1364 static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim)
1365 {
1366 if (rlim64_is_infinity(rlim64->rlim_cur))
1367 rlim->rlim_cur = RLIM_INFINITY;
1368 else
1369 rlim->rlim_cur = (unsigned long)rlim64->rlim_cur;
1370 if (rlim64_is_infinity(rlim64->rlim_max))
1371 rlim->rlim_max = RLIM_INFINITY;
1372 else
1373 rlim->rlim_max = (unsigned long)rlim64->rlim_max;
1374 }
1375
1376 /* make sure you are allowed to change @tsk limits before calling this */
1377 int do_prlimit(struct task_struct *tsk, unsigned int resource,
1378 struct rlimit *new_rlim, struct rlimit *old_rlim)
1379 {
1380 struct rlimit *rlim;
1381 int retval = 0;
1382
1383 if (resource >= RLIM_NLIMITS)
1384 return -EINVAL;
1385 if (new_rlim) {
1386 if (new_rlim->rlim_cur > new_rlim->rlim_max)
1387 return -EINVAL;
1388 if (resource == RLIMIT_NOFILE &&
1389 new_rlim->rlim_max > sysctl_nr_open)
1390 return -EPERM;
1391 }
1392
1393 /* protect tsk->signal and tsk->sighand from disappearing */
1394 read_lock(&tasklist_lock);
1395 if (!tsk->sighand) {
1396 retval = -ESRCH;
1397 goto out;
1398 }
1399
1400 rlim = tsk->signal->rlim + resource;
1401 task_lock(tsk->group_leader);
1402 if (new_rlim) {
1403 /* Keep the capable check against init_user_ns until
1404 cgroups can contain all limits */
1405 if (new_rlim->rlim_max > rlim->rlim_max &&
1406 !capable(CAP_SYS_RESOURCE))
1407 retval = -EPERM;
1408 if (!retval)
1409 retval = security_task_setrlimit(tsk->group_leader,
1410 resource, new_rlim);
1411 if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
1412 /*
1413 * The caller is asking for an immediate RLIMIT_CPU
1414 * expiry. But we use the zero value to mean "it was
1415 * never set". So let's cheat and make it one second
1416 * instead
1417 */
1418 new_rlim->rlim_cur = 1;
1419 }
1420 }
1421 if (!retval) {
1422 if (old_rlim)
1423 *old_rlim = *rlim;
1424 if (new_rlim)
1425 *rlim = *new_rlim;
1426 }
1427 task_unlock(tsk->group_leader);
1428
1429 /*
1430 * RLIMIT_CPU handling. Note that the kernel fails to return an error
1431 * code if it rejected the user's attempt to set RLIMIT_CPU. This is a
1432 * very long-standing error, and fixing it now risks breakage of
1433 * applications, so we live with it
1434 */
1435 if (!retval && new_rlim && resource == RLIMIT_CPU &&
1436 new_rlim->rlim_cur != RLIM_INFINITY)
1437 update_rlimit_cpu(tsk, new_rlim->rlim_cur);
1438 out:
1439 read_unlock(&tasklist_lock);
1440 return retval;
1441 }
1442
1443 /* rcu lock must be held */
1444 static int check_prlimit_permission(struct task_struct *task)
1445 {
1446 const struct cred *cred = current_cred(), *tcred;
1447
1448 if (current == task)
1449 return 0;
1450
1451 tcred = __task_cred(task);
1452 if (cred->user->user_ns == tcred->user->user_ns &&
1453 (cred->uid == tcred->euid &&
1454 cred->uid == tcred->suid &&
1455 cred->uid == tcred->uid &&
1456 cred->gid == tcred->egid &&
1457 cred->gid == tcred->sgid &&
1458 cred->gid == tcred->gid))
1459 return 0;
1460 if (ns_capable(tcred->user->user_ns, CAP_SYS_RESOURCE))
1461 return 0;
1462
1463 return -EPERM;
1464 }
1465
1466 SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
1467 const struct rlimit64 __user *, new_rlim,
1468 struct rlimit64 __user *, old_rlim)
1469 {
1470 struct rlimit64 old64, new64;
1471 struct rlimit old, new;
1472 struct task_struct *tsk;
1473 int ret;
1474
1475 if (new_rlim) {
1476 if (copy_from_user(&new64, new_rlim, sizeof(new64)))
1477 return -EFAULT;
1478 rlim64_to_rlim(&new64, &new);
1479 }
1480
1481 rcu_read_lock();
1482 tsk = pid ? find_task_by_vpid(pid) : current;
1483 if (!tsk) {
1484 rcu_read_unlock();
1485 return -ESRCH;
1486 }
1487 ret = check_prlimit_permission(tsk);
1488 if (ret) {
1489 rcu_read_unlock();
1490 return ret;
1491 }
1492 get_task_struct(tsk);
1493 rcu_read_unlock();
1494
1495 ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
1496 old_rlim ? &old : NULL);
1497
1498 if (!ret && old_rlim) {
1499 rlim_to_rlim64(&old, &old64);
1500 if (copy_to_user(old_rlim, &old64, sizeof(old64)))
1501 ret = -EFAULT;
1502 }
1503
1504 put_task_struct(tsk);
1505 return ret;
1506 }
1507
1508 SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1509 {
1510 struct rlimit new_rlim;
1511
1512 if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
1513 return -EFAULT;
1514 return do_prlimit(current, resource, &new_rlim, NULL);
1515 }
1516
1517 /*
1518 * It would make sense to put struct rusage in the task_struct,
1519 * except that would make the task_struct be *really big*. After
1520 * task_struct gets moved into malloc'ed memory, it would
1521 * make sense to do this. It will make moving the rest of the information
1522 * a lot simpler! (Which we're not doing right now because we're not
1523 * measuring them yet).
1524 *
1525 * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
1526 * races with threads incrementing their own counters. But since word
1527 * reads are atomic, we either get new values or old values and we don't
1528 * care which for the sums. We always take the siglock to protect reading
1529 * the c* fields from p->signal from races with exit.c updating those
1530 * fields when reaping, so a sample either gets all the additions of a
1531 * given child after it's reaped, or none so this sample is before reaping.
1532 *
1533 * Locking:
1534 * We need to take the siglock for CHILDEREN, SELF and BOTH
1535 * for the cases current multithreaded, non-current single threaded
1536 * non-current multithreaded. Thread traversal is now safe with
1537 * the siglock held.
1538 * Strictly speaking, we donot need to take the siglock if we are current and
1539 * single threaded, as no one else can take our signal_struct away, no one
1540 * else can reap the children to update signal->c* counters, and no one else
1541 * can race with the signal-> fields. If we do not take any lock, the
1542 * signal-> fields could be read out of order while another thread was just
1543 * exiting. So we should place a read memory barrier when we avoid the lock.
1544 * On the writer side, write memory barrier is implied in __exit_signal
1545 * as __exit_signal releases the siglock spinlock after updating the signal->
1546 * fields. But we don't do this yet to keep things simple.
1547 *
1548 */
1549
1550 static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
1551 {
1552 r->ru_nvcsw += t->nvcsw;
1553 r->ru_nivcsw += t->nivcsw;
1554 r->ru_minflt += t->min_flt;
1555 r->ru_majflt += t->maj_flt;
1556 r->ru_inblock += task_io_get_inblock(t);
1557 r->ru_oublock += task_io_get_oublock(t);
1558 }
1559
1560 static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
1561 {
1562 struct task_struct *t;
1563 unsigned long flags;
1564 cputime_t tgutime, tgstime, utime, stime;
1565 unsigned long maxrss = 0;
1566
1567 memset((char *) r, 0, sizeof *r);
1568 utime = stime = cputime_zero;
1569
1570 if (who == RUSAGE_THREAD) {
1571 task_times(current, &utime, &stime);
1572 accumulate_thread_rusage(p, r);
1573 maxrss = p->signal->maxrss;
1574 goto out;
1575 }
1576
1577 if (!lock_task_sighand(p, &flags))
1578 return;
1579
1580 switch (who) {
1581 case RUSAGE_BOTH:
1582 case RUSAGE_CHILDREN:
1583 utime = p->signal->cutime;
1584 stime = p->signal->cstime;
1585 r->ru_nvcsw = p->signal->cnvcsw;
1586 r->ru_nivcsw = p->signal->cnivcsw;
1587 r->ru_minflt = p->signal->cmin_flt;
1588 r->ru_majflt = p->signal->cmaj_flt;
1589 r->ru_inblock = p->signal->cinblock;
1590 r->ru_oublock = p->signal->coublock;
1591 maxrss = p->signal->cmaxrss;
1592
1593 if (who == RUSAGE_CHILDREN)
1594 break;
1595
1596 case RUSAGE_SELF:
1597 thread_group_times(p, &tgutime, &tgstime);
1598 utime = cputime_add(utime, tgutime);
1599 stime = cputime_add(stime, tgstime);
1600 r->ru_nvcsw += p->signal->nvcsw;
1601 r->ru_nivcsw += p->signal->nivcsw;
1602 r->ru_minflt += p->signal->min_flt;
1603 r->ru_majflt += p->signal->maj_flt;
1604 r->ru_inblock += p->signal->inblock;
1605 r->ru_oublock += p->signal->oublock;
1606 if (maxrss < p->signal->maxrss)
1607 maxrss = p->signal->maxrss;
1608 t = p;
1609 do {
1610 accumulate_thread_rusage(t, r);
1611 t = next_thread(t);
1612 } while (t != p);
1613 break;
1614
1615 default:
1616 BUG();
1617 }
1618 unlock_task_sighand(p, &flags);
1619
1620 out:
1621 cputime_to_timeval(utime, &r->ru_utime);
1622 cputime_to_timeval(stime, &r->ru_stime);
1623
1624 if (who != RUSAGE_CHILDREN) {
1625 struct mm_struct *mm = get_task_mm(p);
1626 if (mm) {
1627 setmax_mm_hiwater_rss(&maxrss, mm);
1628 mmput(mm);
1629 }
1630 }
1631 r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
1632 }
1633
1634 int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
1635 {
1636 struct rusage r;
1637 k_getrusage(p, who, &r);
1638 return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
1639 }
1640
1641 SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
1642 {
1643 if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
1644 who != RUSAGE_THREAD)
1645 return -EINVAL;
1646 return getrusage(current, who, ru);
1647 }
1648
1649 SYSCALL_DEFINE1(umask, int, mask)
1650 {
1651 mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
1652 return mask;
1653 }
1654
1655 SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
1656 unsigned long, arg4, unsigned long, arg5)
1657 {
1658 struct task_struct *me = current;
1659 unsigned char comm[sizeof(me->comm)];
1660 long error;
1661
1662 error = security_task_prctl(option, arg2, arg3, arg4, arg5);
1663 if (error != -ENOSYS)
1664 return error;
1665
1666 error = 0;
1667 switch (option) {
1668 case PR_SET_PDEATHSIG:
1669 if (!valid_signal(arg2)) {
1670 error = -EINVAL;
1671 break;
1672 }
1673 me->pdeath_signal = arg2;
1674 error = 0;
1675 break;
1676 case PR_GET_PDEATHSIG:
1677 error = put_user(me->pdeath_signal, (int __user *)arg2);
1678 break;
1679 case PR_GET_DUMPABLE:
1680 error = get_dumpable(me->mm);
1681 break;
1682 case PR_SET_DUMPABLE:
1683 if (arg2 < 0 || arg2 > 1) {
1684 error = -EINVAL;
1685 break;
1686 }
1687 set_dumpable(me->mm, arg2);
1688 error = 0;
1689 break;
1690
1691 case PR_SET_UNALIGN:
1692 error = SET_UNALIGN_CTL(me, arg2);
1693 break;
1694 case PR_GET_UNALIGN:
1695 error = GET_UNALIGN_CTL(me, arg2);
1696 break;
1697 case PR_SET_FPEMU:
1698 error = SET_FPEMU_CTL(me, arg2);
1699 break;
1700 case PR_GET_FPEMU:
1701 error = GET_FPEMU_CTL(me, arg2);
1702 break;
1703 case PR_SET_FPEXC:
1704 error = SET_FPEXC_CTL(me, arg2);
1705 break;
1706 case PR_GET_FPEXC:
1707 error = GET_FPEXC_CTL(me, arg2);
1708 break;
1709 case PR_GET_TIMING:
1710 error = PR_TIMING_STATISTICAL;
1711 break;
1712 case PR_SET_TIMING:
1713 if (arg2 != PR_TIMING_STATISTICAL)
1714 error = -EINVAL;
1715 else
1716 error = 0;
1717 break;
1718
1719 case PR_SET_NAME:
1720 comm[sizeof(me->comm)-1] = 0;
1721 if (strncpy_from_user(comm, (char __user *)arg2,
1722 sizeof(me->comm) - 1) < 0)
1723 return -EFAULT;
1724 set_task_comm(me, comm);
1725 return 0;
1726 case PR_GET_NAME:
1727 get_task_comm(comm, me);
1728 if (copy_to_user((char __user *)arg2, comm,
1729 sizeof(comm)))
1730 return -EFAULT;
1731 return 0;
1732 case PR_GET_ENDIAN:
1733 error = GET_ENDIAN(me, arg2);
1734 break;
1735 case PR_SET_ENDIAN:
1736 error = SET_ENDIAN(me, arg2);
1737 break;
1738
1739 case PR_GET_SECCOMP:
1740 error = prctl_get_seccomp();
1741 break;
1742 case PR_SET_SECCOMP:
1743 error = prctl_set_seccomp(arg2);
1744 break;
1745 case PR_GET_TSC:
1746 error = GET_TSC_CTL(arg2);
1747 break;
1748 case PR_SET_TSC:
1749 error = SET_TSC_CTL(arg2);
1750 break;
1751 case PR_TASK_PERF_EVENTS_DISABLE:
1752 error = perf_event_task_disable();
1753 break;
1754 case PR_TASK_PERF_EVENTS_ENABLE:
1755 error = perf_event_task_enable();
1756 break;
1757 case PR_GET_TIMERSLACK:
1758 error = current->timer_slack_ns;
1759 break;
1760 case PR_SET_TIMERSLACK:
1761 if (arg2 <= 0)
1762 current->timer_slack_ns =
1763 current->default_timer_slack_ns;
1764 else
1765 current->timer_slack_ns = arg2;
1766 error = 0;
1767 break;
1768 case PR_MCE_KILL:
1769 if (arg4 | arg5)
1770 return -EINVAL;
1771 switch (arg2) {
1772 case PR_MCE_KILL_CLEAR:
1773 if (arg3 != 0)
1774 return -EINVAL;
1775 current->flags &= ~PF_MCE_PROCESS;
1776 break;
1777 case PR_MCE_KILL_SET:
1778 current->flags |= PF_MCE_PROCESS;
1779 if (arg3 == PR_MCE_KILL_EARLY)
1780 current->flags |= PF_MCE_EARLY;
1781 else if (arg3 == PR_MCE_KILL_LATE)
1782 current->flags &= ~PF_MCE_EARLY;
1783 else if (arg3 == PR_MCE_KILL_DEFAULT)
1784 current->flags &=
1785 ~(PF_MCE_EARLY|PF_MCE_PROCESS);
1786 else
1787 return -EINVAL;
1788 break;
1789 default:
1790 return -EINVAL;
1791 }
1792 error = 0;
1793 break;
1794 case PR_MCE_KILL_GET:
1795 if (arg2 | arg3 | arg4 | arg5)
1796 return -EINVAL;
1797 if (current->flags & PF_MCE_PROCESS)
1798 error = (current->flags & PF_MCE_EARLY) ?
1799 PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE;
1800 else
1801 error = PR_MCE_KILL_DEFAULT;
1802 break;
1803 default:
1804 error = -EINVAL;
1805 break;
1806 }
1807 return error;
1808 }
1809
1810 SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
1811 struct getcpu_cache __user *, unused)
1812 {
1813 int err = 0;
1814 int cpu = raw_smp_processor_id();
1815 if (cpup)
1816 err |= put_user(cpu, cpup);
1817 if (nodep)
1818 err |= put_user(cpu_to_node(cpu), nodep);
1819 return err ? -EFAULT : 0;
1820 }
1821
1822 char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
1823
1824 static void argv_cleanup(struct subprocess_info *info)
1825 {
1826 argv_free(info->argv);
1827 }
1828
1829 /**
1830 * orderly_poweroff - Trigger an orderly system poweroff
1831 * @force: force poweroff if command execution fails
1832 *
1833 * This may be called from any context to trigger a system shutdown.
1834 * If the orderly shutdown fails, it will force an immediate shutdown.
1835 */
1836 int orderly_poweroff(bool force)
1837 {
1838 int argc;
1839 char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
1840 static char *envp[] = {
1841 "HOME=/",
1842 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
1843 NULL
1844 };
1845 int ret = -ENOMEM;
1846 struct subprocess_info *info;
1847
1848 if (argv == NULL) {
1849 printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
1850 __func__, poweroff_cmd);
1851 goto out;
1852 }
1853
1854 info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
1855 if (info == NULL) {
1856 argv_free(argv);
1857 goto out;
1858 }
1859
1860 call_usermodehelper_setfns(info, NULL, argv_cleanup, NULL);
1861
1862 ret = call_usermodehelper_exec(info, UMH_NO_WAIT);
1863
1864 out:
1865 if (ret && force) {
1866 printk(KERN_WARNING "Failed to start orderly shutdown: "
1867 "forcing the issue\n");
1868
1869 /* I guess this should try to kick off some daemon to
1870 sync and poweroff asap. Or not even bother syncing
1871 if we're doing an emergency shutdown? */
1872 emergency_sync();
1873 kernel_power_off();
1874 }
1875
1876 return ret;
1877 }
1878 EXPORT_SYMBOL_GPL(orderly_poweroff);
linux-next