xref: /openbmc/linux/kernel/sys.c (revision b34081f1)
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 #include <linux/binfmts.h>
51 
52 #include <linux/sched.h>
53 #include <linux/rcupdate.h>
54 #include <linux/uidgid.h>
55 #include <linux/cred.h>
56 
57 #include <linux/kmsg_dump.h>
58 /* Move somewhere else to avoid recompiling? */
59 #include <generated/utsrelease.h>
60 
61 #include <asm/uaccess.h>
62 #include <asm/io.h>
63 #include <asm/unistd.h>
64 
65 #ifndef SET_UNALIGN_CTL
66 # define SET_UNALIGN_CTL(a,b)	(-EINVAL)
67 #endif
68 #ifndef GET_UNALIGN_CTL
69 # define GET_UNALIGN_CTL(a,b)	(-EINVAL)
70 #endif
71 #ifndef SET_FPEMU_CTL
72 # define SET_FPEMU_CTL(a,b)	(-EINVAL)
73 #endif
74 #ifndef GET_FPEMU_CTL
75 # define GET_FPEMU_CTL(a,b)	(-EINVAL)
76 #endif
77 #ifndef SET_FPEXC_CTL
78 # define SET_FPEXC_CTL(a,b)	(-EINVAL)
79 #endif
80 #ifndef GET_FPEXC_CTL
81 # define GET_FPEXC_CTL(a,b)	(-EINVAL)
82 #endif
83 #ifndef GET_ENDIAN
84 # define GET_ENDIAN(a,b)	(-EINVAL)
85 #endif
86 #ifndef SET_ENDIAN
87 # define SET_ENDIAN(a,b)	(-EINVAL)
88 #endif
89 #ifndef GET_TSC_CTL
90 # define GET_TSC_CTL(a)		(-EINVAL)
91 #endif
92 #ifndef SET_TSC_CTL
93 # define SET_TSC_CTL(a)		(-EINVAL)
94 #endif
95 
96 /*
97  * this is where the system-wide overflow UID and GID are defined, for
98  * architectures that now have 32-bit UID/GID but didn't in the past
99  */
100 
101 int overflowuid = DEFAULT_OVERFLOWUID;
102 int overflowgid = DEFAULT_OVERFLOWGID;
103 
104 EXPORT_SYMBOL(overflowuid);
105 EXPORT_SYMBOL(overflowgid);
106 
107 /*
108  * the same as above, but for filesystems which can only store a 16-bit
109  * UID and GID. as such, this is needed on all architectures
110  */
111 
112 int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
113 int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
114 
115 EXPORT_SYMBOL(fs_overflowuid);
116 EXPORT_SYMBOL(fs_overflowgid);
117 
118 /*
119  * Returns true if current's euid is same as p's uid or euid,
120  * or has CAP_SYS_NICE to p's user_ns.
121  *
122  * Called with rcu_read_lock, creds are safe
123  */
124 static bool set_one_prio_perm(struct task_struct *p)
125 {
126 	const struct cred *cred = current_cred(), *pcred = __task_cred(p);
127 
128 	if (uid_eq(pcred->uid,  cred->euid) ||
129 	    uid_eq(pcred->euid, cred->euid))
130 		return true;
131 	if (ns_capable(pcred->user_ns, CAP_SYS_NICE))
132 		return true;
133 	return false;
134 }
135 
136 /*
137  * set the priority of a task
138  * - the caller must hold the RCU read lock
139  */
140 static int set_one_prio(struct task_struct *p, int niceval, int error)
141 {
142 	int no_nice;
143 
144 	if (!set_one_prio_perm(p)) {
145 		error = -EPERM;
146 		goto out;
147 	}
148 	if (niceval < task_nice(p) && !can_nice(p, niceval)) {
149 		error = -EACCES;
150 		goto out;
151 	}
152 	no_nice = security_task_setnice(p, niceval);
153 	if (no_nice) {
154 		error = no_nice;
155 		goto out;
156 	}
157 	if (error == -ESRCH)
158 		error = 0;
159 	set_user_nice(p, niceval);
160 out:
161 	return error;
162 }
163 
164 SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
165 {
166 	struct task_struct *g, *p;
167 	struct user_struct *user;
168 	const struct cred *cred = current_cred();
169 	int error = -EINVAL;
170 	struct pid *pgrp;
171 	kuid_t uid;
172 
173 	if (which > PRIO_USER || which < PRIO_PROCESS)
174 		goto out;
175 
176 	/* normalize: avoid signed division (rounding problems) */
177 	error = -ESRCH;
178 	if (niceval < -20)
179 		niceval = -20;
180 	if (niceval > 19)
181 		niceval = 19;
182 
183 	rcu_read_lock();
184 	read_lock(&tasklist_lock);
185 	switch (which) {
186 		case PRIO_PROCESS:
187 			if (who)
188 				p = find_task_by_vpid(who);
189 			else
190 				p = current;
191 			if (p)
192 				error = set_one_prio(p, niceval, error);
193 			break;
194 		case PRIO_PGRP:
195 			if (who)
196 				pgrp = find_vpid(who);
197 			else
198 				pgrp = task_pgrp(current);
199 			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
200 				error = set_one_prio(p, niceval, error);
201 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
202 			break;
203 		case PRIO_USER:
204 			uid = make_kuid(cred->user_ns, who);
205 			user = cred->user;
206 			if (!who)
207 				uid = cred->uid;
208 			else if (!uid_eq(uid, cred->uid) &&
209 				 !(user = find_user(uid)))
210 				goto out_unlock;	/* No processes for this user */
211 
212 			do_each_thread(g, p) {
213 				if (uid_eq(task_uid(p), uid))
214 					error = set_one_prio(p, niceval, error);
215 			} while_each_thread(g, p);
216 			if (!uid_eq(uid, cred->uid))
217 				free_uid(user);		/* For find_user() */
218 			break;
219 	}
220 out_unlock:
221 	read_unlock(&tasklist_lock);
222 	rcu_read_unlock();
223 out:
224 	return error;
225 }
226 
227 /*
228  * Ugh. To avoid negative return values, "getpriority()" will
229  * not return the normal nice-value, but a negated value that
230  * has been offset by 20 (ie it returns 40..1 instead of -20..19)
231  * to stay compatible.
232  */
233 SYSCALL_DEFINE2(getpriority, int, which, int, who)
234 {
235 	struct task_struct *g, *p;
236 	struct user_struct *user;
237 	const struct cred *cred = current_cred();
238 	long niceval, retval = -ESRCH;
239 	struct pid *pgrp;
240 	kuid_t uid;
241 
242 	if (which > PRIO_USER || which < PRIO_PROCESS)
243 		return -EINVAL;
244 
245 	rcu_read_lock();
246 	read_lock(&tasklist_lock);
247 	switch (which) {
248 		case PRIO_PROCESS:
249 			if (who)
250 				p = find_task_by_vpid(who);
251 			else
252 				p = current;
253 			if (p) {
254 				niceval = 20 - task_nice(p);
255 				if (niceval > retval)
256 					retval = niceval;
257 			}
258 			break;
259 		case PRIO_PGRP:
260 			if (who)
261 				pgrp = find_vpid(who);
262 			else
263 				pgrp = task_pgrp(current);
264 			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
265 				niceval = 20 - task_nice(p);
266 				if (niceval > retval)
267 					retval = niceval;
268 			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
269 			break;
270 		case PRIO_USER:
271 			uid = make_kuid(cred->user_ns, who);
272 			user = cred->user;
273 			if (!who)
274 				uid = cred->uid;
275 			else if (!uid_eq(uid, cred->uid) &&
276 				 !(user = find_user(uid)))
277 				goto out_unlock;	/* No processes for this user */
278 
279 			do_each_thread(g, p) {
280 				if (uid_eq(task_uid(p), uid)) {
281 					niceval = 20 - task_nice(p);
282 					if (niceval > retval)
283 						retval = niceval;
284 				}
285 			} while_each_thread(g, p);
286 			if (!uid_eq(uid, cred->uid))
287 				free_uid(user);		/* for find_user() */
288 			break;
289 	}
290 out_unlock:
291 	read_unlock(&tasklist_lock);
292 	rcu_read_unlock();
293 
294 	return retval;
295 }
296 
297 /*
298  * Unprivileged users may change the real gid to the effective gid
299  * or vice versa.  (BSD-style)
300  *
301  * If you set the real gid at all, or set the effective gid to a value not
302  * equal to the real gid, then the saved gid is set to the new effective gid.
303  *
304  * This makes it possible for a setgid program to completely drop its
305  * privileges, which is often a useful assertion to make when you are doing
306  * a security audit over a program.
307  *
308  * The general idea is that a program which uses just setregid() will be
309  * 100% compatible with BSD.  A program which uses just setgid() will be
310  * 100% compatible with POSIX with saved IDs.
311  *
312  * SMP: There are not races, the GIDs are checked only by filesystem
313  *      operations (as far as semantic preservation is concerned).
314  */
315 SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
316 {
317 	struct user_namespace *ns = current_user_ns();
318 	const struct cred *old;
319 	struct cred *new;
320 	int retval;
321 	kgid_t krgid, kegid;
322 
323 	krgid = make_kgid(ns, rgid);
324 	kegid = make_kgid(ns, egid);
325 
326 	if ((rgid != (gid_t) -1) && !gid_valid(krgid))
327 		return -EINVAL;
328 	if ((egid != (gid_t) -1) && !gid_valid(kegid))
329 		return -EINVAL;
330 
331 	new = prepare_creds();
332 	if (!new)
333 		return -ENOMEM;
334 	old = current_cred();
335 
336 	retval = -EPERM;
337 	if (rgid != (gid_t) -1) {
338 		if (gid_eq(old->gid, krgid) ||
339 		    gid_eq(old->egid, krgid) ||
340 		    ns_capable(old->user_ns, CAP_SETGID))
341 			new->gid = krgid;
342 		else
343 			goto error;
344 	}
345 	if (egid != (gid_t) -1) {
346 		if (gid_eq(old->gid, kegid) ||
347 		    gid_eq(old->egid, kegid) ||
348 		    gid_eq(old->sgid, kegid) ||
349 		    ns_capable(old->user_ns, CAP_SETGID))
350 			new->egid = kegid;
351 		else
352 			goto error;
353 	}
354 
355 	if (rgid != (gid_t) -1 ||
356 	    (egid != (gid_t) -1 && !gid_eq(kegid, old->gid)))
357 		new->sgid = new->egid;
358 	new->fsgid = new->egid;
359 
360 	return commit_creds(new);
361 
362 error:
363 	abort_creds(new);
364 	return retval;
365 }
366 
367 /*
368  * setgid() is implemented like SysV w/ SAVED_IDS
369  *
370  * SMP: Same implicit races as above.
371  */
372 SYSCALL_DEFINE1(setgid, gid_t, gid)
373 {
374 	struct user_namespace *ns = current_user_ns();
375 	const struct cred *old;
376 	struct cred *new;
377 	int retval;
378 	kgid_t kgid;
379 
380 	kgid = make_kgid(ns, gid);
381 	if (!gid_valid(kgid))
382 		return -EINVAL;
383 
384 	new = prepare_creds();
385 	if (!new)
386 		return -ENOMEM;
387 	old = current_cred();
388 
389 	retval = -EPERM;
390 	if (ns_capable(old->user_ns, CAP_SETGID))
391 		new->gid = new->egid = new->sgid = new->fsgid = kgid;
392 	else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid))
393 		new->egid = new->fsgid = kgid;
394 	else
395 		goto error;
396 
397 	return commit_creds(new);
398 
399 error:
400 	abort_creds(new);
401 	return retval;
402 }
403 
404 /*
405  * change the user struct in a credentials set to match the new UID
406  */
407 static int set_user(struct cred *new)
408 {
409 	struct user_struct *new_user;
410 
411 	new_user = alloc_uid(new->uid);
412 	if (!new_user)
413 		return -EAGAIN;
414 
415 	/*
416 	 * We don't fail in case of NPROC limit excess here because too many
417 	 * poorly written programs don't check set*uid() return code, assuming
418 	 * it never fails if called by root.  We may still enforce NPROC limit
419 	 * for programs doing set*uid()+execve() by harmlessly deferring the
420 	 * failure to the execve() stage.
421 	 */
422 	if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
423 			new_user != INIT_USER)
424 		current->flags |= PF_NPROC_EXCEEDED;
425 	else
426 		current->flags &= ~PF_NPROC_EXCEEDED;
427 
428 	free_uid(new->user);
429 	new->user = new_user;
430 	return 0;
431 }
432 
433 /*
434  * Unprivileged users may change the real uid to the effective uid
435  * or vice versa.  (BSD-style)
436  *
437  * If you set the real uid at all, or set the effective uid to a value not
438  * equal to the real uid, then the saved uid is set to the new effective uid.
439  *
440  * This makes it possible for a setuid program to completely drop its
441  * privileges, which is often a useful assertion to make when you are doing
442  * a security audit over a program.
443  *
444  * The general idea is that a program which uses just setreuid() will be
445  * 100% compatible with BSD.  A program which uses just setuid() will be
446  * 100% compatible with POSIX with saved IDs.
447  */
448 SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
449 {
450 	struct user_namespace *ns = current_user_ns();
451 	const struct cred *old;
452 	struct cred *new;
453 	int retval;
454 	kuid_t kruid, keuid;
455 
456 	kruid = make_kuid(ns, ruid);
457 	keuid = make_kuid(ns, euid);
458 
459 	if ((ruid != (uid_t) -1) && !uid_valid(kruid))
460 		return -EINVAL;
461 	if ((euid != (uid_t) -1) && !uid_valid(keuid))
462 		return -EINVAL;
463 
464 	new = prepare_creds();
465 	if (!new)
466 		return -ENOMEM;
467 	old = current_cred();
468 
469 	retval = -EPERM;
470 	if (ruid != (uid_t) -1) {
471 		new->uid = kruid;
472 		if (!uid_eq(old->uid, kruid) &&
473 		    !uid_eq(old->euid, kruid) &&
474 		    !ns_capable(old->user_ns, CAP_SETUID))
475 			goto error;
476 	}
477 
478 	if (euid != (uid_t) -1) {
479 		new->euid = keuid;
480 		if (!uid_eq(old->uid, keuid) &&
481 		    !uid_eq(old->euid, keuid) &&
482 		    !uid_eq(old->suid, keuid) &&
483 		    !ns_capable(old->user_ns, CAP_SETUID))
484 			goto error;
485 	}
486 
487 	if (!uid_eq(new->uid, old->uid)) {
488 		retval = set_user(new);
489 		if (retval < 0)
490 			goto error;
491 	}
492 	if (ruid != (uid_t) -1 ||
493 	    (euid != (uid_t) -1 && !uid_eq(keuid, old->uid)))
494 		new->suid = new->euid;
495 	new->fsuid = new->euid;
496 
497 	retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
498 	if (retval < 0)
499 		goto error;
500 
501 	return commit_creds(new);
502 
503 error:
504 	abort_creds(new);
505 	return retval;
506 }
507 
508 /*
509  * setuid() is implemented like SysV with SAVED_IDS
510  *
511  * Note that SAVED_ID's is deficient in that a setuid root program
512  * like sendmail, for example, cannot set its uid to be a normal
513  * user and then switch back, because if you're root, setuid() sets
514  * the saved uid too.  If you don't like this, blame the bright people
515  * in the POSIX committee and/or USG.  Note that the BSD-style setreuid()
516  * will allow a root program to temporarily drop privileges and be able to
517  * regain them by swapping the real and effective uid.
518  */
519 SYSCALL_DEFINE1(setuid, uid_t, uid)
520 {
521 	struct user_namespace *ns = current_user_ns();
522 	const struct cred *old;
523 	struct cred *new;
524 	int retval;
525 	kuid_t kuid;
526 
527 	kuid = make_kuid(ns, uid);
528 	if (!uid_valid(kuid))
529 		return -EINVAL;
530 
531 	new = prepare_creds();
532 	if (!new)
533 		return -ENOMEM;
534 	old = current_cred();
535 
536 	retval = -EPERM;
537 	if (ns_capable(old->user_ns, CAP_SETUID)) {
538 		new->suid = new->uid = kuid;
539 		if (!uid_eq(kuid, old->uid)) {
540 			retval = set_user(new);
541 			if (retval < 0)
542 				goto error;
543 		}
544 	} else if (!uid_eq(kuid, old->uid) && !uid_eq(kuid, new->suid)) {
545 		goto error;
546 	}
547 
548 	new->fsuid = new->euid = kuid;
549 
550 	retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
551 	if (retval < 0)
552 		goto error;
553 
554 	return commit_creds(new);
555 
556 error:
557 	abort_creds(new);
558 	return retval;
559 }
560 
561 
562 /*
563  * This function implements a generic ability to update ruid, euid,
564  * and suid.  This allows you to implement the 4.4 compatible seteuid().
565  */
566 SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
567 {
568 	struct user_namespace *ns = current_user_ns();
569 	const struct cred *old;
570 	struct cred *new;
571 	int retval;
572 	kuid_t kruid, keuid, ksuid;
573 
574 	kruid = make_kuid(ns, ruid);
575 	keuid = make_kuid(ns, euid);
576 	ksuid = make_kuid(ns, suid);
577 
578 	if ((ruid != (uid_t) -1) && !uid_valid(kruid))
579 		return -EINVAL;
580 
581 	if ((euid != (uid_t) -1) && !uid_valid(keuid))
582 		return -EINVAL;
583 
584 	if ((suid != (uid_t) -1) && !uid_valid(ksuid))
585 		return -EINVAL;
586 
587 	new = prepare_creds();
588 	if (!new)
589 		return -ENOMEM;
590 
591 	old = current_cred();
592 
593 	retval = -EPERM;
594 	if (!ns_capable(old->user_ns, CAP_SETUID)) {
595 		if (ruid != (uid_t) -1        && !uid_eq(kruid, old->uid) &&
596 		    !uid_eq(kruid, old->euid) && !uid_eq(kruid, old->suid))
597 			goto error;
598 		if (euid != (uid_t) -1        && !uid_eq(keuid, old->uid) &&
599 		    !uid_eq(keuid, old->euid) && !uid_eq(keuid, old->suid))
600 			goto error;
601 		if (suid != (uid_t) -1        && !uid_eq(ksuid, old->uid) &&
602 		    !uid_eq(ksuid, old->euid) && !uid_eq(ksuid, old->suid))
603 			goto error;
604 	}
605 
606 	if (ruid != (uid_t) -1) {
607 		new->uid = kruid;
608 		if (!uid_eq(kruid, old->uid)) {
609 			retval = set_user(new);
610 			if (retval < 0)
611 				goto error;
612 		}
613 	}
614 	if (euid != (uid_t) -1)
615 		new->euid = keuid;
616 	if (suid != (uid_t) -1)
617 		new->suid = ksuid;
618 	new->fsuid = new->euid;
619 
620 	retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
621 	if (retval < 0)
622 		goto error;
623 
624 	return commit_creds(new);
625 
626 error:
627 	abort_creds(new);
628 	return retval;
629 }
630 
631 SYSCALL_DEFINE3(getresuid, uid_t __user *, ruidp, uid_t __user *, euidp, uid_t __user *, suidp)
632 {
633 	const struct cred *cred = current_cred();
634 	int retval;
635 	uid_t ruid, euid, suid;
636 
637 	ruid = from_kuid_munged(cred->user_ns, cred->uid);
638 	euid = from_kuid_munged(cred->user_ns, cred->euid);
639 	suid = from_kuid_munged(cred->user_ns, cred->suid);
640 
641 	if (!(retval   = put_user(ruid, ruidp)) &&
642 	    !(retval   = put_user(euid, euidp)))
643 		retval = put_user(suid, suidp);
644 
645 	return retval;
646 }
647 
648 /*
649  * Same as above, but for rgid, egid, sgid.
650  */
651 SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
652 {
653 	struct user_namespace *ns = current_user_ns();
654 	const struct cred *old;
655 	struct cred *new;
656 	int retval;
657 	kgid_t krgid, kegid, ksgid;
658 
659 	krgid = make_kgid(ns, rgid);
660 	kegid = make_kgid(ns, egid);
661 	ksgid = make_kgid(ns, sgid);
662 
663 	if ((rgid != (gid_t) -1) && !gid_valid(krgid))
664 		return -EINVAL;
665 	if ((egid != (gid_t) -1) && !gid_valid(kegid))
666 		return -EINVAL;
667 	if ((sgid != (gid_t) -1) && !gid_valid(ksgid))
668 		return -EINVAL;
669 
670 	new = prepare_creds();
671 	if (!new)
672 		return -ENOMEM;
673 	old = current_cred();
674 
675 	retval = -EPERM;
676 	if (!ns_capable(old->user_ns, CAP_SETGID)) {
677 		if (rgid != (gid_t) -1        && !gid_eq(krgid, old->gid) &&
678 		    !gid_eq(krgid, old->egid) && !gid_eq(krgid, old->sgid))
679 			goto error;
680 		if (egid != (gid_t) -1        && !gid_eq(kegid, old->gid) &&
681 		    !gid_eq(kegid, old->egid) && !gid_eq(kegid, old->sgid))
682 			goto error;
683 		if (sgid != (gid_t) -1        && !gid_eq(ksgid, old->gid) &&
684 		    !gid_eq(ksgid, old->egid) && !gid_eq(ksgid, old->sgid))
685 			goto error;
686 	}
687 
688 	if (rgid != (gid_t) -1)
689 		new->gid = krgid;
690 	if (egid != (gid_t) -1)
691 		new->egid = kegid;
692 	if (sgid != (gid_t) -1)
693 		new->sgid = ksgid;
694 	new->fsgid = new->egid;
695 
696 	return commit_creds(new);
697 
698 error:
699 	abort_creds(new);
700 	return retval;
701 }
702 
703 SYSCALL_DEFINE3(getresgid, gid_t __user *, rgidp, gid_t __user *, egidp, gid_t __user *, sgidp)
704 {
705 	const struct cred *cred = current_cred();
706 	int retval;
707 	gid_t rgid, egid, sgid;
708 
709 	rgid = from_kgid_munged(cred->user_ns, cred->gid);
710 	egid = from_kgid_munged(cred->user_ns, cred->egid);
711 	sgid = from_kgid_munged(cred->user_ns, cred->sgid);
712 
713 	if (!(retval   = put_user(rgid, rgidp)) &&
714 	    !(retval   = put_user(egid, egidp)))
715 		retval = put_user(sgid, sgidp);
716 
717 	return retval;
718 }
719 
720 
721 /*
722  * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
723  * is used for "access()" and for the NFS daemon (letting nfsd stay at
724  * whatever uid it wants to). It normally shadows "euid", except when
725  * explicitly set by setfsuid() or for access..
726  */
727 SYSCALL_DEFINE1(setfsuid, uid_t, uid)
728 {
729 	const struct cred *old;
730 	struct cred *new;
731 	uid_t old_fsuid;
732 	kuid_t kuid;
733 
734 	old = current_cred();
735 	old_fsuid = from_kuid_munged(old->user_ns, old->fsuid);
736 
737 	kuid = make_kuid(old->user_ns, uid);
738 	if (!uid_valid(kuid))
739 		return old_fsuid;
740 
741 	new = prepare_creds();
742 	if (!new)
743 		return old_fsuid;
744 
745 	if (uid_eq(kuid, old->uid)  || uid_eq(kuid, old->euid)  ||
746 	    uid_eq(kuid, old->suid) || uid_eq(kuid, old->fsuid) ||
747 	    ns_capable(old->user_ns, CAP_SETUID)) {
748 		if (!uid_eq(kuid, old->fsuid)) {
749 			new->fsuid = kuid;
750 			if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
751 				goto change_okay;
752 		}
753 	}
754 
755 	abort_creds(new);
756 	return old_fsuid;
757 
758 change_okay:
759 	commit_creds(new);
760 	return old_fsuid;
761 }
762 
763 /*
764  * Samma på svenska..
765  */
766 SYSCALL_DEFINE1(setfsgid, gid_t, gid)
767 {
768 	const struct cred *old;
769 	struct cred *new;
770 	gid_t old_fsgid;
771 	kgid_t kgid;
772 
773 	old = current_cred();
774 	old_fsgid = from_kgid_munged(old->user_ns, old->fsgid);
775 
776 	kgid = make_kgid(old->user_ns, gid);
777 	if (!gid_valid(kgid))
778 		return old_fsgid;
779 
780 	new = prepare_creds();
781 	if (!new)
782 		return old_fsgid;
783 
784 	if (gid_eq(kgid, old->gid)  || gid_eq(kgid, old->egid)  ||
785 	    gid_eq(kgid, old->sgid) || gid_eq(kgid, old->fsgid) ||
786 	    ns_capable(old->user_ns, CAP_SETGID)) {
787 		if (!gid_eq(kgid, old->fsgid)) {
788 			new->fsgid = kgid;
789 			goto change_okay;
790 		}
791 	}
792 
793 	abort_creds(new);
794 	return old_fsgid;
795 
796 change_okay:
797 	commit_creds(new);
798 	return old_fsgid;
799 }
800 
801 /**
802  * sys_getpid - return the thread group id of the current process
803  *
804  * Note, despite the name, this returns the tgid not the pid.  The tgid and
805  * the pid are identical unless CLONE_THREAD was specified on clone() in
806  * which case the tgid is the same in all threads of the same group.
807  *
808  * This is SMP safe as current->tgid does not change.
809  */
810 SYSCALL_DEFINE0(getpid)
811 {
812 	return task_tgid_vnr(current);
813 }
814 
815 /* Thread ID - the internal kernel "pid" */
816 SYSCALL_DEFINE0(gettid)
817 {
818 	return task_pid_vnr(current);
819 }
820 
821 /*
822  * Accessing ->real_parent is not SMP-safe, it could
823  * change from under us. However, we can use a stale
824  * value of ->real_parent under rcu_read_lock(), see
825  * release_task()->call_rcu(delayed_put_task_struct).
826  */
827 SYSCALL_DEFINE0(getppid)
828 {
829 	int pid;
830 
831 	rcu_read_lock();
832 	pid = task_tgid_vnr(rcu_dereference(current->real_parent));
833 	rcu_read_unlock();
834 
835 	return pid;
836 }
837 
838 SYSCALL_DEFINE0(getuid)
839 {
840 	/* Only we change this so SMP safe */
841 	return from_kuid_munged(current_user_ns(), current_uid());
842 }
843 
844 SYSCALL_DEFINE0(geteuid)
845 {
846 	/* Only we change this so SMP safe */
847 	return from_kuid_munged(current_user_ns(), current_euid());
848 }
849 
850 SYSCALL_DEFINE0(getgid)
851 {
852 	/* Only we change this so SMP safe */
853 	return from_kgid_munged(current_user_ns(), current_gid());
854 }
855 
856 SYSCALL_DEFINE0(getegid)
857 {
858 	/* Only we change this so SMP safe */
859 	return from_kgid_munged(current_user_ns(), current_egid());
860 }
861 
862 void do_sys_times(struct tms *tms)
863 {
864 	cputime_t tgutime, tgstime, cutime, cstime;
865 
866 	spin_lock_irq(&current->sighand->siglock);
867 	thread_group_cputime_adjusted(current, &tgutime, &tgstime);
868 	cutime = current->signal->cutime;
869 	cstime = current->signal->cstime;
870 	spin_unlock_irq(&current->sighand->siglock);
871 	tms->tms_utime = cputime_to_clock_t(tgutime);
872 	tms->tms_stime = cputime_to_clock_t(tgstime);
873 	tms->tms_cutime = cputime_to_clock_t(cutime);
874 	tms->tms_cstime = cputime_to_clock_t(cstime);
875 }
876 
877 SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
878 {
879 	if (tbuf) {
880 		struct tms tmp;
881 
882 		do_sys_times(&tmp);
883 		if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
884 			return -EFAULT;
885 	}
886 	force_successful_syscall_return();
887 	return (long) jiffies_64_to_clock_t(get_jiffies_64());
888 }
889 
890 /*
891  * This needs some heavy checking ...
892  * I just haven't the stomach for it. I also don't fully
893  * understand sessions/pgrp etc. Let somebody who does explain it.
894  *
895  * OK, I think I have the protection semantics right.... this is really
896  * only important on a multi-user system anyway, to make sure one user
897  * can't send a signal to a process owned by another.  -TYT, 12/12/91
898  *
899  * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
900  * LBT 04.03.94
901  */
902 SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
903 {
904 	struct task_struct *p;
905 	struct task_struct *group_leader = current->group_leader;
906 	struct pid *pgrp;
907 	int err;
908 
909 	if (!pid)
910 		pid = task_pid_vnr(group_leader);
911 	if (!pgid)
912 		pgid = pid;
913 	if (pgid < 0)
914 		return -EINVAL;
915 	rcu_read_lock();
916 
917 	/* From this point forward we keep holding onto the tasklist lock
918 	 * so that our parent does not change from under us. -DaveM
919 	 */
920 	write_lock_irq(&tasklist_lock);
921 
922 	err = -ESRCH;
923 	p = find_task_by_vpid(pid);
924 	if (!p)
925 		goto out;
926 
927 	err = -EINVAL;
928 	if (!thread_group_leader(p))
929 		goto out;
930 
931 	if (same_thread_group(p->real_parent, group_leader)) {
932 		err = -EPERM;
933 		if (task_session(p) != task_session(group_leader))
934 			goto out;
935 		err = -EACCES;
936 		if (p->did_exec)
937 			goto out;
938 	} else {
939 		err = -ESRCH;
940 		if (p != group_leader)
941 			goto out;
942 	}
943 
944 	err = -EPERM;
945 	if (p->signal->leader)
946 		goto out;
947 
948 	pgrp = task_pid(p);
949 	if (pgid != pid) {
950 		struct task_struct *g;
951 
952 		pgrp = find_vpid(pgid);
953 		g = pid_task(pgrp, PIDTYPE_PGID);
954 		if (!g || task_session(g) != task_session(group_leader))
955 			goto out;
956 	}
957 
958 	err = security_task_setpgid(p, pgid);
959 	if (err)
960 		goto out;
961 
962 	if (task_pgrp(p) != pgrp)
963 		change_pid(p, PIDTYPE_PGID, pgrp);
964 
965 	err = 0;
966 out:
967 	/* All paths lead to here, thus we are safe. -DaveM */
968 	write_unlock_irq(&tasklist_lock);
969 	rcu_read_unlock();
970 	return err;
971 }
972 
973 SYSCALL_DEFINE1(getpgid, pid_t, pid)
974 {
975 	struct task_struct *p;
976 	struct pid *grp;
977 	int retval;
978 
979 	rcu_read_lock();
980 	if (!pid)
981 		grp = task_pgrp(current);
982 	else {
983 		retval = -ESRCH;
984 		p = find_task_by_vpid(pid);
985 		if (!p)
986 			goto out;
987 		grp = task_pgrp(p);
988 		if (!grp)
989 			goto out;
990 
991 		retval = security_task_getpgid(p);
992 		if (retval)
993 			goto out;
994 	}
995 	retval = pid_vnr(grp);
996 out:
997 	rcu_read_unlock();
998 	return retval;
999 }
1000 
1001 #ifdef __ARCH_WANT_SYS_GETPGRP
1002 
1003 SYSCALL_DEFINE0(getpgrp)
1004 {
1005 	return sys_getpgid(0);
1006 }
1007 
1008 #endif
1009 
1010 SYSCALL_DEFINE1(getsid, pid_t, pid)
1011 {
1012 	struct task_struct *p;
1013 	struct pid *sid;
1014 	int retval;
1015 
1016 	rcu_read_lock();
1017 	if (!pid)
1018 		sid = task_session(current);
1019 	else {
1020 		retval = -ESRCH;
1021 		p = find_task_by_vpid(pid);
1022 		if (!p)
1023 			goto out;
1024 		sid = task_session(p);
1025 		if (!sid)
1026 			goto out;
1027 
1028 		retval = security_task_getsid(p);
1029 		if (retval)
1030 			goto out;
1031 	}
1032 	retval = pid_vnr(sid);
1033 out:
1034 	rcu_read_unlock();
1035 	return retval;
1036 }
1037 
1038 static void set_special_pids(struct pid *pid)
1039 {
1040 	struct task_struct *curr = current->group_leader;
1041 
1042 	if (task_session(curr) != pid)
1043 		change_pid(curr, PIDTYPE_SID, pid);
1044 
1045 	if (task_pgrp(curr) != pid)
1046 		change_pid(curr, PIDTYPE_PGID, pid);
1047 }
1048 
1049 SYSCALL_DEFINE0(setsid)
1050 {
1051 	struct task_struct *group_leader = current->group_leader;
1052 	struct pid *sid = task_pid(group_leader);
1053 	pid_t session = pid_vnr(sid);
1054 	int err = -EPERM;
1055 
1056 	write_lock_irq(&tasklist_lock);
1057 	/* Fail if I am already a session leader */
1058 	if (group_leader->signal->leader)
1059 		goto out;
1060 
1061 	/* Fail if a process group id already exists that equals the
1062 	 * proposed session id.
1063 	 */
1064 	if (pid_task(sid, PIDTYPE_PGID))
1065 		goto out;
1066 
1067 	group_leader->signal->leader = 1;
1068 	set_special_pids(sid);
1069 
1070 	proc_clear_tty(group_leader);
1071 
1072 	err = session;
1073 out:
1074 	write_unlock_irq(&tasklist_lock);
1075 	if (err > 0) {
1076 		proc_sid_connector(group_leader);
1077 		sched_autogroup_create_attach(group_leader);
1078 	}
1079 	return err;
1080 }
1081 
1082 DECLARE_RWSEM(uts_sem);
1083 
1084 #ifdef COMPAT_UTS_MACHINE
1085 #define override_architecture(name) \
1086 	(personality(current->personality) == PER_LINUX32 && \
1087 	 copy_to_user(name->machine, COMPAT_UTS_MACHINE, \
1088 		      sizeof(COMPAT_UTS_MACHINE)))
1089 #else
1090 #define override_architecture(name)	0
1091 #endif
1092 
1093 /*
1094  * Work around broken programs that cannot handle "Linux 3.0".
1095  * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40
1096  */
1097 static int override_release(char __user *release, size_t len)
1098 {
1099 	int ret = 0;
1100 
1101 	if (current->personality & UNAME26) {
1102 		const char *rest = UTS_RELEASE;
1103 		char buf[65] = { 0 };
1104 		int ndots = 0;
1105 		unsigned v;
1106 		size_t copy;
1107 
1108 		while (*rest) {
1109 			if (*rest == '.' && ++ndots >= 3)
1110 				break;
1111 			if (!isdigit(*rest) && *rest != '.')
1112 				break;
1113 			rest++;
1114 		}
1115 		v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
1116 		copy = clamp_t(size_t, len, 1, sizeof(buf));
1117 		copy = scnprintf(buf, copy, "2.6.%u%s", v, rest);
1118 		ret = copy_to_user(release, buf, copy + 1);
1119 	}
1120 	return ret;
1121 }
1122 
1123 SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
1124 {
1125 	int errno = 0;
1126 
1127 	down_read(&uts_sem);
1128 	if (copy_to_user(name, utsname(), sizeof *name))
1129 		errno = -EFAULT;
1130 	up_read(&uts_sem);
1131 
1132 	if (!errno && override_release(name->release, sizeof(name->release)))
1133 		errno = -EFAULT;
1134 	if (!errno && override_architecture(name))
1135 		errno = -EFAULT;
1136 	return errno;
1137 }
1138 
1139 #ifdef __ARCH_WANT_SYS_OLD_UNAME
1140 /*
1141  * Old cruft
1142  */
1143 SYSCALL_DEFINE1(uname, struct old_utsname __user *, name)
1144 {
1145 	int error = 0;
1146 
1147 	if (!name)
1148 		return -EFAULT;
1149 
1150 	down_read(&uts_sem);
1151 	if (copy_to_user(name, utsname(), sizeof(*name)))
1152 		error = -EFAULT;
1153 	up_read(&uts_sem);
1154 
1155 	if (!error && override_release(name->release, sizeof(name->release)))
1156 		error = -EFAULT;
1157 	if (!error && override_architecture(name))
1158 		error = -EFAULT;
1159 	return error;
1160 }
1161 
1162 SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name)
1163 {
1164 	int error;
1165 
1166 	if (!name)
1167 		return -EFAULT;
1168 	if (!access_ok(VERIFY_WRITE, name, sizeof(struct oldold_utsname)))
1169 		return -EFAULT;
1170 
1171 	down_read(&uts_sem);
1172 	error = __copy_to_user(&name->sysname, &utsname()->sysname,
1173 			       __OLD_UTS_LEN);
1174 	error |= __put_user(0, name->sysname + __OLD_UTS_LEN);
1175 	error |= __copy_to_user(&name->nodename, &utsname()->nodename,
1176 				__OLD_UTS_LEN);
1177 	error |= __put_user(0, name->nodename + __OLD_UTS_LEN);
1178 	error |= __copy_to_user(&name->release, &utsname()->release,
1179 				__OLD_UTS_LEN);
1180 	error |= __put_user(0, name->release + __OLD_UTS_LEN);
1181 	error |= __copy_to_user(&name->version, &utsname()->version,
1182 				__OLD_UTS_LEN);
1183 	error |= __put_user(0, name->version + __OLD_UTS_LEN);
1184 	error |= __copy_to_user(&name->machine, &utsname()->machine,
1185 				__OLD_UTS_LEN);
1186 	error |= __put_user(0, name->machine + __OLD_UTS_LEN);
1187 	up_read(&uts_sem);
1188 
1189 	if (!error && override_architecture(name))
1190 		error = -EFAULT;
1191 	if (!error && override_release(name->release, sizeof(name->release)))
1192 		error = -EFAULT;
1193 	return error ? -EFAULT : 0;
1194 }
1195 #endif
1196 
1197 SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
1198 {
1199 	int errno;
1200 	char tmp[__NEW_UTS_LEN];
1201 
1202 	if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1203 		return -EPERM;
1204 
1205 	if (len < 0 || len > __NEW_UTS_LEN)
1206 		return -EINVAL;
1207 	down_write(&uts_sem);
1208 	errno = -EFAULT;
1209 	if (!copy_from_user(tmp, name, len)) {
1210 		struct new_utsname *u = utsname();
1211 
1212 		memcpy(u->nodename, tmp, len);
1213 		memset(u->nodename + len, 0, sizeof(u->nodename) - len);
1214 		errno = 0;
1215 		uts_proc_notify(UTS_PROC_HOSTNAME);
1216 	}
1217 	up_write(&uts_sem);
1218 	return errno;
1219 }
1220 
1221 #ifdef __ARCH_WANT_SYS_GETHOSTNAME
1222 
1223 SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
1224 {
1225 	int i, errno;
1226 	struct new_utsname *u;
1227 
1228 	if (len < 0)
1229 		return -EINVAL;
1230 	down_read(&uts_sem);
1231 	u = utsname();
1232 	i = 1 + strlen(u->nodename);
1233 	if (i > len)
1234 		i = len;
1235 	errno = 0;
1236 	if (copy_to_user(name, u->nodename, i))
1237 		errno = -EFAULT;
1238 	up_read(&uts_sem);
1239 	return errno;
1240 }
1241 
1242 #endif
1243 
1244 /*
1245  * Only setdomainname; getdomainname can be implemented by calling
1246  * uname()
1247  */
1248 SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
1249 {
1250 	int errno;
1251 	char tmp[__NEW_UTS_LEN];
1252 
1253 	if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1254 		return -EPERM;
1255 	if (len < 0 || len > __NEW_UTS_LEN)
1256 		return -EINVAL;
1257 
1258 	down_write(&uts_sem);
1259 	errno = -EFAULT;
1260 	if (!copy_from_user(tmp, name, len)) {
1261 		struct new_utsname *u = utsname();
1262 
1263 		memcpy(u->domainname, tmp, len);
1264 		memset(u->domainname + len, 0, sizeof(u->domainname) - len);
1265 		errno = 0;
1266 		uts_proc_notify(UTS_PROC_DOMAINNAME);
1267 	}
1268 	up_write(&uts_sem);
1269 	return errno;
1270 }
1271 
1272 SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1273 {
1274 	struct rlimit value;
1275 	int ret;
1276 
1277 	ret = do_prlimit(current, resource, NULL, &value);
1278 	if (!ret)
1279 		ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
1280 
1281 	return ret;
1282 }
1283 
1284 #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
1285 
1286 /*
1287  *	Back compatibility for getrlimit. Needed for some apps.
1288  */
1289 
1290 SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
1291 		struct rlimit __user *, rlim)
1292 {
1293 	struct rlimit x;
1294 	if (resource >= RLIM_NLIMITS)
1295 		return -EINVAL;
1296 
1297 	task_lock(current->group_leader);
1298 	x = current->signal->rlim[resource];
1299 	task_unlock(current->group_leader);
1300 	if (x.rlim_cur > 0x7FFFFFFF)
1301 		x.rlim_cur = 0x7FFFFFFF;
1302 	if (x.rlim_max > 0x7FFFFFFF)
1303 		x.rlim_max = 0x7FFFFFFF;
1304 	return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
1305 }
1306 
1307 #endif
1308 
1309 static inline bool rlim64_is_infinity(__u64 rlim64)
1310 {
1311 #if BITS_PER_LONG < 64
1312 	return rlim64 >= ULONG_MAX;
1313 #else
1314 	return rlim64 == RLIM64_INFINITY;
1315 #endif
1316 }
1317 
1318 static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64)
1319 {
1320 	if (rlim->rlim_cur == RLIM_INFINITY)
1321 		rlim64->rlim_cur = RLIM64_INFINITY;
1322 	else
1323 		rlim64->rlim_cur = rlim->rlim_cur;
1324 	if (rlim->rlim_max == RLIM_INFINITY)
1325 		rlim64->rlim_max = RLIM64_INFINITY;
1326 	else
1327 		rlim64->rlim_max = rlim->rlim_max;
1328 }
1329 
1330 static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim)
1331 {
1332 	if (rlim64_is_infinity(rlim64->rlim_cur))
1333 		rlim->rlim_cur = RLIM_INFINITY;
1334 	else
1335 		rlim->rlim_cur = (unsigned long)rlim64->rlim_cur;
1336 	if (rlim64_is_infinity(rlim64->rlim_max))
1337 		rlim->rlim_max = RLIM_INFINITY;
1338 	else
1339 		rlim->rlim_max = (unsigned long)rlim64->rlim_max;
1340 }
1341 
1342 /* make sure you are allowed to change @tsk limits before calling this */
1343 int do_prlimit(struct task_struct *tsk, unsigned int resource,
1344 		struct rlimit *new_rlim, struct rlimit *old_rlim)
1345 {
1346 	struct rlimit *rlim;
1347 	int retval = 0;
1348 
1349 	if (resource >= RLIM_NLIMITS)
1350 		return -EINVAL;
1351 	if (new_rlim) {
1352 		if (new_rlim->rlim_cur > new_rlim->rlim_max)
1353 			return -EINVAL;
1354 		if (resource == RLIMIT_NOFILE &&
1355 				new_rlim->rlim_max > sysctl_nr_open)
1356 			return -EPERM;
1357 	}
1358 
1359 	/* protect tsk->signal and tsk->sighand from disappearing */
1360 	read_lock(&tasklist_lock);
1361 	if (!tsk->sighand) {
1362 		retval = -ESRCH;
1363 		goto out;
1364 	}
1365 
1366 	rlim = tsk->signal->rlim + resource;
1367 	task_lock(tsk->group_leader);
1368 	if (new_rlim) {
1369 		/* Keep the capable check against init_user_ns until
1370 		   cgroups can contain all limits */
1371 		if (new_rlim->rlim_max > rlim->rlim_max &&
1372 				!capable(CAP_SYS_RESOURCE))
1373 			retval = -EPERM;
1374 		if (!retval)
1375 			retval = security_task_setrlimit(tsk->group_leader,
1376 					resource, new_rlim);
1377 		if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
1378 			/*
1379 			 * The caller is asking for an immediate RLIMIT_CPU
1380 			 * expiry.  But we use the zero value to mean "it was
1381 			 * never set".  So let's cheat and make it one second
1382 			 * instead
1383 			 */
1384 			new_rlim->rlim_cur = 1;
1385 		}
1386 	}
1387 	if (!retval) {
1388 		if (old_rlim)
1389 			*old_rlim = *rlim;
1390 		if (new_rlim)
1391 			*rlim = *new_rlim;
1392 	}
1393 	task_unlock(tsk->group_leader);
1394 
1395 	/*
1396 	 * RLIMIT_CPU handling.   Note that the kernel fails to return an error
1397 	 * code if it rejected the user's attempt to set RLIMIT_CPU.  This is a
1398 	 * very long-standing error, and fixing it now risks breakage of
1399 	 * applications, so we live with it
1400 	 */
1401 	 if (!retval && new_rlim && resource == RLIMIT_CPU &&
1402 			 new_rlim->rlim_cur != RLIM_INFINITY)
1403 		update_rlimit_cpu(tsk, new_rlim->rlim_cur);
1404 out:
1405 	read_unlock(&tasklist_lock);
1406 	return retval;
1407 }
1408 
1409 /* rcu lock must be held */
1410 static int check_prlimit_permission(struct task_struct *task)
1411 {
1412 	const struct cred *cred = current_cred(), *tcred;
1413 
1414 	if (current == task)
1415 		return 0;
1416 
1417 	tcred = __task_cred(task);
1418 	if (uid_eq(cred->uid, tcred->euid) &&
1419 	    uid_eq(cred->uid, tcred->suid) &&
1420 	    uid_eq(cred->uid, tcred->uid)  &&
1421 	    gid_eq(cred->gid, tcred->egid) &&
1422 	    gid_eq(cred->gid, tcred->sgid) &&
1423 	    gid_eq(cred->gid, tcred->gid))
1424 		return 0;
1425 	if (ns_capable(tcred->user_ns, CAP_SYS_RESOURCE))
1426 		return 0;
1427 
1428 	return -EPERM;
1429 }
1430 
1431 SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
1432 		const struct rlimit64 __user *, new_rlim,
1433 		struct rlimit64 __user *, old_rlim)
1434 {
1435 	struct rlimit64 old64, new64;
1436 	struct rlimit old, new;
1437 	struct task_struct *tsk;
1438 	int ret;
1439 
1440 	if (new_rlim) {
1441 		if (copy_from_user(&new64, new_rlim, sizeof(new64)))
1442 			return -EFAULT;
1443 		rlim64_to_rlim(&new64, &new);
1444 	}
1445 
1446 	rcu_read_lock();
1447 	tsk = pid ? find_task_by_vpid(pid) : current;
1448 	if (!tsk) {
1449 		rcu_read_unlock();
1450 		return -ESRCH;
1451 	}
1452 	ret = check_prlimit_permission(tsk);
1453 	if (ret) {
1454 		rcu_read_unlock();
1455 		return ret;
1456 	}
1457 	get_task_struct(tsk);
1458 	rcu_read_unlock();
1459 
1460 	ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
1461 			old_rlim ? &old : NULL);
1462 
1463 	if (!ret && old_rlim) {
1464 		rlim_to_rlim64(&old, &old64);
1465 		if (copy_to_user(old_rlim, &old64, sizeof(old64)))
1466 			ret = -EFAULT;
1467 	}
1468 
1469 	put_task_struct(tsk);
1470 	return ret;
1471 }
1472 
1473 SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1474 {
1475 	struct rlimit new_rlim;
1476 
1477 	if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
1478 		return -EFAULT;
1479 	return do_prlimit(current, resource, &new_rlim, NULL);
1480 }
1481 
1482 /*
1483  * It would make sense to put struct rusage in the task_struct,
1484  * except that would make the task_struct be *really big*.  After
1485  * task_struct gets moved into malloc'ed memory, it would
1486  * make sense to do this.  It will make moving the rest of the information
1487  * a lot simpler!  (Which we're not doing right now because we're not
1488  * measuring them yet).
1489  *
1490  * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
1491  * races with threads incrementing their own counters.  But since word
1492  * reads are atomic, we either get new values or old values and we don't
1493  * care which for the sums.  We always take the siglock to protect reading
1494  * the c* fields from p->signal from races with exit.c updating those
1495  * fields when reaping, so a sample either gets all the additions of a
1496  * given child after it's reaped, or none so this sample is before reaping.
1497  *
1498  * Locking:
1499  * We need to take the siglock for CHILDEREN, SELF and BOTH
1500  * for  the cases current multithreaded, non-current single threaded
1501  * non-current multithreaded.  Thread traversal is now safe with
1502  * the siglock held.
1503  * Strictly speaking, we donot need to take the siglock if we are current and
1504  * single threaded,  as no one else can take our signal_struct away, no one
1505  * else can  reap the  children to update signal->c* counters, and no one else
1506  * can race with the signal-> fields. If we do not take any lock, the
1507  * signal-> fields could be read out of order while another thread was just
1508  * exiting. So we should  place a read memory barrier when we avoid the lock.
1509  * On the writer side,  write memory barrier is implied in  __exit_signal
1510  * as __exit_signal releases  the siglock spinlock after updating the signal->
1511  * fields. But we don't do this yet to keep things simple.
1512  *
1513  */
1514 
1515 static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
1516 {
1517 	r->ru_nvcsw += t->nvcsw;
1518 	r->ru_nivcsw += t->nivcsw;
1519 	r->ru_minflt += t->min_flt;
1520 	r->ru_majflt += t->maj_flt;
1521 	r->ru_inblock += task_io_get_inblock(t);
1522 	r->ru_oublock += task_io_get_oublock(t);
1523 }
1524 
1525 static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
1526 {
1527 	struct task_struct *t;
1528 	unsigned long flags;
1529 	cputime_t tgutime, tgstime, utime, stime;
1530 	unsigned long maxrss = 0;
1531 
1532 	memset((char *) r, 0, sizeof *r);
1533 	utime = stime = 0;
1534 
1535 	if (who == RUSAGE_THREAD) {
1536 		task_cputime_adjusted(current, &utime, &stime);
1537 		accumulate_thread_rusage(p, r);
1538 		maxrss = p->signal->maxrss;
1539 		goto out;
1540 	}
1541 
1542 	if (!lock_task_sighand(p, &flags))
1543 		return;
1544 
1545 	switch (who) {
1546 		case RUSAGE_BOTH:
1547 		case RUSAGE_CHILDREN:
1548 			utime = p->signal->cutime;
1549 			stime = p->signal->cstime;
1550 			r->ru_nvcsw = p->signal->cnvcsw;
1551 			r->ru_nivcsw = p->signal->cnivcsw;
1552 			r->ru_minflt = p->signal->cmin_flt;
1553 			r->ru_majflt = p->signal->cmaj_flt;
1554 			r->ru_inblock = p->signal->cinblock;
1555 			r->ru_oublock = p->signal->coublock;
1556 			maxrss = p->signal->cmaxrss;
1557 
1558 			if (who == RUSAGE_CHILDREN)
1559 				break;
1560 
1561 		case RUSAGE_SELF:
1562 			thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1563 			utime += tgutime;
1564 			stime += tgstime;
1565 			r->ru_nvcsw += p->signal->nvcsw;
1566 			r->ru_nivcsw += p->signal->nivcsw;
1567 			r->ru_minflt += p->signal->min_flt;
1568 			r->ru_majflt += p->signal->maj_flt;
1569 			r->ru_inblock += p->signal->inblock;
1570 			r->ru_oublock += p->signal->oublock;
1571 			if (maxrss < p->signal->maxrss)
1572 				maxrss = p->signal->maxrss;
1573 			t = p;
1574 			do {
1575 				accumulate_thread_rusage(t, r);
1576 				t = next_thread(t);
1577 			} while (t != p);
1578 			break;
1579 
1580 		default:
1581 			BUG();
1582 	}
1583 	unlock_task_sighand(p, &flags);
1584 
1585 out:
1586 	cputime_to_timeval(utime, &r->ru_utime);
1587 	cputime_to_timeval(stime, &r->ru_stime);
1588 
1589 	if (who != RUSAGE_CHILDREN) {
1590 		struct mm_struct *mm = get_task_mm(p);
1591 		if (mm) {
1592 			setmax_mm_hiwater_rss(&maxrss, mm);
1593 			mmput(mm);
1594 		}
1595 	}
1596 	r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
1597 }
1598 
1599 int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
1600 {
1601 	struct rusage r;
1602 	k_getrusage(p, who, &r);
1603 	return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
1604 }
1605 
1606 SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
1607 {
1608 	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
1609 	    who != RUSAGE_THREAD)
1610 		return -EINVAL;
1611 	return getrusage(current, who, ru);
1612 }
1613 
1614 #ifdef CONFIG_COMPAT
1615 COMPAT_SYSCALL_DEFINE2(getrusage, int, who, struct compat_rusage __user *, ru)
1616 {
1617 	struct rusage r;
1618 
1619 	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
1620 	    who != RUSAGE_THREAD)
1621 		return -EINVAL;
1622 
1623 	k_getrusage(current, who, &r);
1624 	return put_compat_rusage(&r, ru);
1625 }
1626 #endif
1627 
1628 SYSCALL_DEFINE1(umask, int, mask)
1629 {
1630 	mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
1631 	return mask;
1632 }
1633 
1634 static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
1635 {
1636 	struct fd exe;
1637 	struct inode *inode;
1638 	int err;
1639 
1640 	exe = fdget(fd);
1641 	if (!exe.file)
1642 		return -EBADF;
1643 
1644 	inode = file_inode(exe.file);
1645 
1646 	/*
1647 	 * Because the original mm->exe_file points to executable file, make
1648 	 * sure that this one is executable as well, to avoid breaking an
1649 	 * overall picture.
1650 	 */
1651 	err = -EACCES;
1652 	if (!S_ISREG(inode->i_mode)	||
1653 	    exe.file->f_path.mnt->mnt_flags & MNT_NOEXEC)
1654 		goto exit;
1655 
1656 	err = inode_permission(inode, MAY_EXEC);
1657 	if (err)
1658 		goto exit;
1659 
1660 	down_write(&mm->mmap_sem);
1661 
1662 	/*
1663 	 * Forbid mm->exe_file change if old file still mapped.
1664 	 */
1665 	err = -EBUSY;
1666 	if (mm->exe_file) {
1667 		struct vm_area_struct *vma;
1668 
1669 		for (vma = mm->mmap; vma; vma = vma->vm_next)
1670 			if (vma->vm_file &&
1671 			    path_equal(&vma->vm_file->f_path,
1672 				       &mm->exe_file->f_path))
1673 				goto exit_unlock;
1674 	}
1675 
1676 	/*
1677 	 * The symlink can be changed only once, just to disallow arbitrary
1678 	 * transitions malicious software might bring in. This means one
1679 	 * could make a snapshot over all processes running and monitor
1680 	 * /proc/pid/exe changes to notice unusual activity if needed.
1681 	 */
1682 	err = -EPERM;
1683 	if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
1684 		goto exit_unlock;
1685 
1686 	err = 0;
1687 	set_mm_exe_file(mm, exe.file);	/* this grabs a reference to exe.file */
1688 exit_unlock:
1689 	up_write(&mm->mmap_sem);
1690 
1691 exit:
1692 	fdput(exe);
1693 	return err;
1694 }
1695 
1696 static int prctl_set_mm(int opt, unsigned long addr,
1697 			unsigned long arg4, unsigned long arg5)
1698 {
1699 	unsigned long rlim = rlimit(RLIMIT_DATA);
1700 	struct mm_struct *mm = current->mm;
1701 	struct vm_area_struct *vma;
1702 	int error;
1703 
1704 	if (arg5 || (arg4 && opt != PR_SET_MM_AUXV))
1705 		return -EINVAL;
1706 
1707 	if (!capable(CAP_SYS_RESOURCE))
1708 		return -EPERM;
1709 
1710 	if (opt == PR_SET_MM_EXE_FILE)
1711 		return prctl_set_mm_exe_file(mm, (unsigned int)addr);
1712 
1713 	if (addr >= TASK_SIZE || addr < mmap_min_addr)
1714 		return -EINVAL;
1715 
1716 	error = -EINVAL;
1717 
1718 	down_read(&mm->mmap_sem);
1719 	vma = find_vma(mm, addr);
1720 
1721 	switch (opt) {
1722 	case PR_SET_MM_START_CODE:
1723 		mm->start_code = addr;
1724 		break;
1725 	case PR_SET_MM_END_CODE:
1726 		mm->end_code = addr;
1727 		break;
1728 	case PR_SET_MM_START_DATA:
1729 		mm->start_data = addr;
1730 		break;
1731 	case PR_SET_MM_END_DATA:
1732 		mm->end_data = addr;
1733 		break;
1734 
1735 	case PR_SET_MM_START_BRK:
1736 		if (addr <= mm->end_data)
1737 			goto out;
1738 
1739 		if (rlim < RLIM_INFINITY &&
1740 		    (mm->brk - addr) +
1741 		    (mm->end_data - mm->start_data) > rlim)
1742 			goto out;
1743 
1744 		mm->start_brk = addr;
1745 		break;
1746 
1747 	case PR_SET_MM_BRK:
1748 		if (addr <= mm->end_data)
1749 			goto out;
1750 
1751 		if (rlim < RLIM_INFINITY &&
1752 		    (addr - mm->start_brk) +
1753 		    (mm->end_data - mm->start_data) > rlim)
1754 			goto out;
1755 
1756 		mm->brk = addr;
1757 		break;
1758 
1759 	/*
1760 	 * If command line arguments and environment
1761 	 * are placed somewhere else on stack, we can
1762 	 * set them up here, ARG_START/END to setup
1763 	 * command line argumets and ENV_START/END
1764 	 * for environment.
1765 	 */
1766 	case PR_SET_MM_START_STACK:
1767 	case PR_SET_MM_ARG_START:
1768 	case PR_SET_MM_ARG_END:
1769 	case PR_SET_MM_ENV_START:
1770 	case PR_SET_MM_ENV_END:
1771 		if (!vma) {
1772 			error = -EFAULT;
1773 			goto out;
1774 		}
1775 		if (opt == PR_SET_MM_START_STACK)
1776 			mm->start_stack = addr;
1777 		else if (opt == PR_SET_MM_ARG_START)
1778 			mm->arg_start = addr;
1779 		else if (opt == PR_SET_MM_ARG_END)
1780 			mm->arg_end = addr;
1781 		else if (opt == PR_SET_MM_ENV_START)
1782 			mm->env_start = addr;
1783 		else if (opt == PR_SET_MM_ENV_END)
1784 			mm->env_end = addr;
1785 		break;
1786 
1787 	/*
1788 	 * This doesn't move auxiliary vector itself
1789 	 * since it's pinned to mm_struct, but allow
1790 	 * to fill vector with new values. It's up
1791 	 * to a caller to provide sane values here
1792 	 * otherwise user space tools which use this
1793 	 * vector might be unhappy.
1794 	 */
1795 	case PR_SET_MM_AUXV: {
1796 		unsigned long user_auxv[AT_VECTOR_SIZE];
1797 
1798 		if (arg4 > sizeof(user_auxv))
1799 			goto out;
1800 		up_read(&mm->mmap_sem);
1801 
1802 		if (copy_from_user(user_auxv, (const void __user *)addr, arg4))
1803 			return -EFAULT;
1804 
1805 		/* Make sure the last entry is always AT_NULL */
1806 		user_auxv[AT_VECTOR_SIZE - 2] = 0;
1807 		user_auxv[AT_VECTOR_SIZE - 1] = 0;
1808 
1809 		BUILD_BUG_ON(sizeof(user_auxv) != sizeof(mm->saved_auxv));
1810 
1811 		task_lock(current);
1812 		memcpy(mm->saved_auxv, user_auxv, arg4);
1813 		task_unlock(current);
1814 
1815 		return 0;
1816 	}
1817 	default:
1818 		goto out;
1819 	}
1820 
1821 	error = 0;
1822 out:
1823 	up_read(&mm->mmap_sem);
1824 	return error;
1825 }
1826 
1827 #ifdef CONFIG_CHECKPOINT_RESTORE
1828 static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
1829 {
1830 	return put_user(me->clear_child_tid, tid_addr);
1831 }
1832 #else
1833 static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr)
1834 {
1835 	return -EINVAL;
1836 }
1837 #endif
1838 
1839 SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
1840 		unsigned long, arg4, unsigned long, arg5)
1841 {
1842 	struct task_struct *me = current;
1843 	unsigned char comm[sizeof(me->comm)];
1844 	long error;
1845 
1846 	error = security_task_prctl(option, arg2, arg3, arg4, arg5);
1847 	if (error != -ENOSYS)
1848 		return error;
1849 
1850 	error = 0;
1851 	switch (option) {
1852 	case PR_SET_PDEATHSIG:
1853 		if (!valid_signal(arg2)) {
1854 			error = -EINVAL;
1855 			break;
1856 		}
1857 		me->pdeath_signal = arg2;
1858 		break;
1859 	case PR_GET_PDEATHSIG:
1860 		error = put_user(me->pdeath_signal, (int __user *)arg2);
1861 		break;
1862 	case PR_GET_DUMPABLE:
1863 		error = get_dumpable(me->mm);
1864 		break;
1865 	case PR_SET_DUMPABLE:
1866 		if (arg2 != SUID_DUMP_DISABLE && arg2 != SUID_DUMP_USER) {
1867 			error = -EINVAL;
1868 			break;
1869 		}
1870 		set_dumpable(me->mm, arg2);
1871 		break;
1872 
1873 	case PR_SET_UNALIGN:
1874 		error = SET_UNALIGN_CTL(me, arg2);
1875 		break;
1876 	case PR_GET_UNALIGN:
1877 		error = GET_UNALIGN_CTL(me, arg2);
1878 		break;
1879 	case PR_SET_FPEMU:
1880 		error = SET_FPEMU_CTL(me, arg2);
1881 		break;
1882 	case PR_GET_FPEMU:
1883 		error = GET_FPEMU_CTL(me, arg2);
1884 		break;
1885 	case PR_SET_FPEXC:
1886 		error = SET_FPEXC_CTL(me, arg2);
1887 		break;
1888 	case PR_GET_FPEXC:
1889 		error = GET_FPEXC_CTL(me, arg2);
1890 		break;
1891 	case PR_GET_TIMING:
1892 		error = PR_TIMING_STATISTICAL;
1893 		break;
1894 	case PR_SET_TIMING:
1895 		if (arg2 != PR_TIMING_STATISTICAL)
1896 			error = -EINVAL;
1897 		break;
1898 	case PR_SET_NAME:
1899 		comm[sizeof(me->comm) - 1] = 0;
1900 		if (strncpy_from_user(comm, (char __user *)arg2,
1901 				      sizeof(me->comm) - 1) < 0)
1902 			return -EFAULT;
1903 		set_task_comm(me, comm);
1904 		proc_comm_connector(me);
1905 		break;
1906 	case PR_GET_NAME:
1907 		get_task_comm(comm, me);
1908 		if (copy_to_user((char __user *)arg2, comm, sizeof(comm)))
1909 			return -EFAULT;
1910 		break;
1911 	case PR_GET_ENDIAN:
1912 		error = GET_ENDIAN(me, arg2);
1913 		break;
1914 	case PR_SET_ENDIAN:
1915 		error = SET_ENDIAN(me, arg2);
1916 		break;
1917 	case PR_GET_SECCOMP:
1918 		error = prctl_get_seccomp();
1919 		break;
1920 	case PR_SET_SECCOMP:
1921 		error = prctl_set_seccomp(arg2, (char __user *)arg3);
1922 		break;
1923 	case PR_GET_TSC:
1924 		error = GET_TSC_CTL(arg2);
1925 		break;
1926 	case PR_SET_TSC:
1927 		error = SET_TSC_CTL(arg2);
1928 		break;
1929 	case PR_TASK_PERF_EVENTS_DISABLE:
1930 		error = perf_event_task_disable();
1931 		break;
1932 	case PR_TASK_PERF_EVENTS_ENABLE:
1933 		error = perf_event_task_enable();
1934 		break;
1935 	case PR_GET_TIMERSLACK:
1936 		error = current->timer_slack_ns;
1937 		break;
1938 	case PR_SET_TIMERSLACK:
1939 		if (arg2 <= 0)
1940 			current->timer_slack_ns =
1941 					current->default_timer_slack_ns;
1942 		else
1943 			current->timer_slack_ns = arg2;
1944 		break;
1945 	case PR_MCE_KILL:
1946 		if (arg4 | arg5)
1947 			return -EINVAL;
1948 		switch (arg2) {
1949 		case PR_MCE_KILL_CLEAR:
1950 			if (arg3 != 0)
1951 				return -EINVAL;
1952 			current->flags &= ~PF_MCE_PROCESS;
1953 			break;
1954 		case PR_MCE_KILL_SET:
1955 			current->flags |= PF_MCE_PROCESS;
1956 			if (arg3 == PR_MCE_KILL_EARLY)
1957 				current->flags |= PF_MCE_EARLY;
1958 			else if (arg3 == PR_MCE_KILL_LATE)
1959 				current->flags &= ~PF_MCE_EARLY;
1960 			else if (arg3 == PR_MCE_KILL_DEFAULT)
1961 				current->flags &=
1962 						~(PF_MCE_EARLY|PF_MCE_PROCESS);
1963 			else
1964 				return -EINVAL;
1965 			break;
1966 		default:
1967 			return -EINVAL;
1968 		}
1969 		break;
1970 	case PR_MCE_KILL_GET:
1971 		if (arg2 | arg3 | arg4 | arg5)
1972 			return -EINVAL;
1973 		if (current->flags & PF_MCE_PROCESS)
1974 			error = (current->flags & PF_MCE_EARLY) ?
1975 				PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE;
1976 		else
1977 			error = PR_MCE_KILL_DEFAULT;
1978 		break;
1979 	case PR_SET_MM:
1980 		error = prctl_set_mm(arg2, arg3, arg4, arg5);
1981 		break;
1982 	case PR_GET_TID_ADDRESS:
1983 		error = prctl_get_tid_address(me, (int __user **)arg2);
1984 		break;
1985 	case PR_SET_CHILD_SUBREAPER:
1986 		me->signal->is_child_subreaper = !!arg2;
1987 		break;
1988 	case PR_GET_CHILD_SUBREAPER:
1989 		error = put_user(me->signal->is_child_subreaper,
1990 				 (int __user *)arg2);
1991 		break;
1992 	case PR_SET_NO_NEW_PRIVS:
1993 		if (arg2 != 1 || arg3 || arg4 || arg5)
1994 			return -EINVAL;
1995 
1996 		current->no_new_privs = 1;
1997 		break;
1998 	case PR_GET_NO_NEW_PRIVS:
1999 		if (arg2 || arg3 || arg4 || arg5)
2000 			return -EINVAL;
2001 		return current->no_new_privs ? 1 : 0;
2002 	default:
2003 		error = -EINVAL;
2004 		break;
2005 	}
2006 	return error;
2007 }
2008 
2009 SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
2010 		struct getcpu_cache __user *, unused)
2011 {
2012 	int err = 0;
2013 	int cpu = raw_smp_processor_id();
2014 	if (cpup)
2015 		err |= put_user(cpu, cpup);
2016 	if (nodep)
2017 		err |= put_user(cpu_to_node(cpu), nodep);
2018 	return err ? -EFAULT : 0;
2019 }
2020 
2021 /**
2022  * do_sysinfo - fill in sysinfo struct
2023  * @info: pointer to buffer to fill
2024  */
2025 static int do_sysinfo(struct sysinfo *info)
2026 {
2027 	unsigned long mem_total, sav_total;
2028 	unsigned int mem_unit, bitcount;
2029 	struct timespec tp;
2030 
2031 	memset(info, 0, sizeof(struct sysinfo));
2032 
2033 	get_monotonic_boottime(&tp);
2034 	info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
2035 
2036 	get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
2037 
2038 	info->procs = nr_threads;
2039 
2040 	si_meminfo(info);
2041 	si_swapinfo(info);
2042 
2043 	/*
2044 	 * If the sum of all the available memory (i.e. ram + swap)
2045 	 * is less than can be stored in a 32 bit unsigned long then
2046 	 * we can be binary compatible with 2.2.x kernels.  If not,
2047 	 * well, in that case 2.2.x was broken anyways...
2048 	 *
2049 	 *  -Erik Andersen <andersee@debian.org>
2050 	 */
2051 
2052 	mem_total = info->totalram + info->totalswap;
2053 	if (mem_total < info->totalram || mem_total < info->totalswap)
2054 		goto out;
2055 	bitcount = 0;
2056 	mem_unit = info->mem_unit;
2057 	while (mem_unit > 1) {
2058 		bitcount++;
2059 		mem_unit >>= 1;
2060 		sav_total = mem_total;
2061 		mem_total <<= 1;
2062 		if (mem_total < sav_total)
2063 			goto out;
2064 	}
2065 
2066 	/*
2067 	 * If mem_total did not overflow, multiply all memory values by
2068 	 * info->mem_unit and set it to 1.  This leaves things compatible
2069 	 * with 2.2.x, and also retains compatibility with earlier 2.4.x
2070 	 * kernels...
2071 	 */
2072 
2073 	info->mem_unit = 1;
2074 	info->totalram <<= bitcount;
2075 	info->freeram <<= bitcount;
2076 	info->sharedram <<= bitcount;
2077 	info->bufferram <<= bitcount;
2078 	info->totalswap <<= bitcount;
2079 	info->freeswap <<= bitcount;
2080 	info->totalhigh <<= bitcount;
2081 	info->freehigh <<= bitcount;
2082 
2083 out:
2084 	return 0;
2085 }
2086 
2087 SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
2088 {
2089 	struct sysinfo val;
2090 
2091 	do_sysinfo(&val);
2092 
2093 	if (copy_to_user(info, &val, sizeof(struct sysinfo)))
2094 		return -EFAULT;
2095 
2096 	return 0;
2097 }
2098 
2099 #ifdef CONFIG_COMPAT
2100 struct compat_sysinfo {
2101 	s32 uptime;
2102 	u32 loads[3];
2103 	u32 totalram;
2104 	u32 freeram;
2105 	u32 sharedram;
2106 	u32 bufferram;
2107 	u32 totalswap;
2108 	u32 freeswap;
2109 	u16 procs;
2110 	u16 pad;
2111 	u32 totalhigh;
2112 	u32 freehigh;
2113 	u32 mem_unit;
2114 	char _f[20-2*sizeof(u32)-sizeof(int)];
2115 };
2116 
2117 COMPAT_SYSCALL_DEFINE1(sysinfo, struct compat_sysinfo __user *, info)
2118 {
2119 	struct sysinfo s;
2120 
2121 	do_sysinfo(&s);
2122 
2123 	/* Check to see if any memory value is too large for 32-bit and scale
2124 	 *  down if needed
2125 	 */
2126 	if ((s.totalram >> 32) || (s.totalswap >> 32)) {
2127 		int bitcount = 0;
2128 
2129 		while (s.mem_unit < PAGE_SIZE) {
2130 			s.mem_unit <<= 1;
2131 			bitcount++;
2132 		}
2133 
2134 		s.totalram >>= bitcount;
2135 		s.freeram >>= bitcount;
2136 		s.sharedram >>= bitcount;
2137 		s.bufferram >>= bitcount;
2138 		s.totalswap >>= bitcount;
2139 		s.freeswap >>= bitcount;
2140 		s.totalhigh >>= bitcount;
2141 		s.freehigh >>= bitcount;
2142 	}
2143 
2144 	if (!access_ok(VERIFY_WRITE, info, sizeof(struct compat_sysinfo)) ||
2145 	    __put_user(s.uptime, &info->uptime) ||
2146 	    __put_user(s.loads[0], &info->loads[0]) ||
2147 	    __put_user(s.loads[1], &info->loads[1]) ||
2148 	    __put_user(s.loads[2], &info->loads[2]) ||
2149 	    __put_user(s.totalram, &info->totalram) ||
2150 	    __put_user(s.freeram, &info->freeram) ||
2151 	    __put_user(s.sharedram, &info->sharedram) ||
2152 	    __put_user(s.bufferram, &info->bufferram) ||
2153 	    __put_user(s.totalswap, &info->totalswap) ||
2154 	    __put_user(s.freeswap, &info->freeswap) ||
2155 	    __put_user(s.procs, &info->procs) ||
2156 	    __put_user(s.totalhigh, &info->totalhigh) ||
2157 	    __put_user(s.freehigh, &info->freehigh) ||
2158 	    __put_user(s.mem_unit, &info->mem_unit))
2159 		return -EFAULT;
2160 
2161 	return 0;
2162 }
2163 #endif /* CONFIG_COMPAT */
2164