1/*
   2 *  linux/kernel/sys.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 */
   6
   7#include <linux/module.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/perf_event.h>
  16#include <linux/resource.h>
  17#include <linux/kernel.h>
  18#include <linux/kexec.h>
  19#include <linux/workqueue.h>
  20#include <linux/capability.h>
  21#include <linux/device.h>
  22#include <linux/key.h>
  23#include <linux/times.h>
  24#include <linux/posix-timers.h>
  25#include <linux/security.h>
  26#include <linux/dcookies.h>
  27#include <linux/suspend.h>
  28#include <linux/tty.h>
  29#include <linux/signal.h>
  30#include <linux/cn_proc.h>
  31#include <linux/getcpu.h>
  32#include <linux/task_io_accounting_ops.h>
  33#include <linux/seccomp.h>
  34#include <linux/cpu.h>
  35#include <linux/personality.h>
  36#include <linux/ptrace.h>
  37#include <linux/fs_struct.h>
 
 
  38#include <linux/gfp.h>
  39#include <linux/syscore_ops.h>
  40#include <linux/version.h>
  41#include <linux/ctype.h>
 
  42
  43#include <linux/compat.h>
  44#include <linux/syscalls.h>
  45#include <linux/kprobes.h>
  46#include <linux/user_namespace.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  47
  48#include <linux/kmsg_dump.h>
  49/* Move somewhere else to avoid recompiling? */
  50#include <generated/utsrelease.h>
  51
  52#include <asm/uaccess.h>
  53#include <asm/io.h>
  54#include <asm/unistd.h>
  55
 
 
  56#ifndef SET_UNALIGN_CTL
  57# define SET_UNALIGN_CTL(a,b)	(-EINVAL)
  58#endif
  59#ifndef GET_UNALIGN_CTL
  60# define GET_UNALIGN_CTL(a,b)	(-EINVAL)
  61#endif
  62#ifndef SET_FPEMU_CTL
  63# define SET_FPEMU_CTL(a,b)	(-EINVAL)
  64#endif
  65#ifndef GET_FPEMU_CTL
  66# define GET_FPEMU_CTL(a,b)	(-EINVAL)
  67#endif
  68#ifndef SET_FPEXC_CTL
  69# define SET_FPEXC_CTL(a,b)	(-EINVAL)
  70#endif
  71#ifndef GET_FPEXC_CTL
  72# define GET_FPEXC_CTL(a,b)	(-EINVAL)
  73#endif
  74#ifndef GET_ENDIAN
  75# define GET_ENDIAN(a,b)	(-EINVAL)
  76#endif
  77#ifndef SET_ENDIAN
  78# define SET_ENDIAN(a,b)	(-EINVAL)
  79#endif
  80#ifndef GET_TSC_CTL
  81# define GET_TSC_CTL(a)		(-EINVAL)
  82#endif
  83#ifndef SET_TSC_CTL
  84# define SET_TSC_CTL(a)		(-EINVAL)
  85#endif
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  86
  87/*
  88 * this is where the system-wide overflow UID and GID are defined, for
  89 * architectures that now have 32-bit UID/GID but didn't in the past
  90 */
  91
  92int overflowuid = DEFAULT_OVERFLOWUID;
  93int overflowgid = DEFAULT_OVERFLOWGID;
  94
  95#ifdef CONFIG_UID16
  96EXPORT_SYMBOL(overflowuid);
  97EXPORT_SYMBOL(overflowgid);
  98#endif
  99
 100/*
 101 * the same as above, but for filesystems which can only store a 16-bit
 102 * UID and GID. as such, this is needed on all architectures
 103 */
 104
 105int fs_overflowuid = DEFAULT_FS_OVERFLOWUID;
 106int fs_overflowgid = DEFAULT_FS_OVERFLOWUID;
 107
 108EXPORT_SYMBOL(fs_overflowuid);
 109EXPORT_SYMBOL(fs_overflowgid);
 110
 111/*
 112 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
 113 */
 114
 115int C_A_D = 1;
 116struct pid *cad_pid;
 117EXPORT_SYMBOL(cad_pid);
 118
 119/*
 120 * If set, this is used for preparing the system to power off.
 121 */
 122
 123void (*pm_power_off_prepare)(void);
 124
 125/*
 126 * Returns true if current's euid is same as p's uid or euid,
 127 * or has CAP_SYS_NICE to p's user_ns.
 128 *
 129 * Called with rcu_read_lock, creds are safe
 130 */
 131static bool set_one_prio_perm(struct task_struct *p)
 132{
 133	const struct cred *cred = current_cred(), *pcred = __task_cred(p);
 134
 135	if (pcred->user->user_ns == cred->user->user_ns &&
 136	    (pcred->uid  == cred->euid ||
 137	     pcred->euid == cred->euid))
 138		return true;
 139	if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE))
 140		return true;
 141	return false;
 142}
 143
 144/*
 145 * set the priority of a task
 146 * - the caller must hold the RCU read lock
 147 */
 148static int set_one_prio(struct task_struct *p, int niceval, int error)
 149{
 150	int no_nice;
 151
 152	if (!set_one_prio_perm(p)) {
 153		error = -EPERM;
 154		goto out;
 155	}
 156	if (niceval < task_nice(p) && !can_nice(p, niceval)) {
 157		error = -EACCES;
 158		goto out;
 159	}
 160	no_nice = security_task_setnice(p, niceval);
 161	if (no_nice) {
 162		error = no_nice;
 163		goto out;
 164	}
 165	if (error == -ESRCH)
 166		error = 0;
 167	set_user_nice(p, niceval);
 168out:
 169	return error;
 170}
 171
 172SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
 173{
 174	struct task_struct *g, *p;
 175	struct user_struct *user;
 176	const struct cred *cred = current_cred();
 177	int error = -EINVAL;
 178	struct pid *pgrp;
 
 179
 180	if (which > PRIO_USER || which < PRIO_PROCESS)
 181		goto out;
 182
 183	/* normalize: avoid signed division (rounding problems) */
 184	error = -ESRCH;
 185	if (niceval < -20)
 186		niceval = -20;
 187	if (niceval > 19)
 188		niceval = 19;
 189
 190	rcu_read_lock();
 191	read_lock(&tasklist_lock);
 192	switch (which) {
 193		case PRIO_PROCESS:
 194			if (who)
 195				p = find_task_by_vpid(who);
 196			else
 197				p = current;
 198			if (p)
 199				error = set_one_prio(p, niceval, error);
 200			break;
 201		case PRIO_PGRP:
 202			if (who)
 203				pgrp = find_vpid(who);
 204			else
 205				pgrp = task_pgrp(current);
 206			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
 207				error = set_one_prio(p, niceval, error);
 208			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
 209			break;
 210		case PRIO_USER:
 211			user = (struct user_struct *) cred->user;
 212			if (!who)
 213				who = cred->uid;
 214			else if ((who != cred->uid) &&
 215				 !(user = find_user(who)))
 
 
 216				goto out_unlock;	/* No processes for this user */
 217
 218			do_each_thread(g, p) {
 219				if (__task_cred(p)->uid == who)
 220					error = set_one_prio(p, niceval, error);
 221			} while_each_thread(g, p);
 222			if (who != cred->uid)
 223				free_uid(user);		/* For find_user() */
 224			break;
 225	}
 226out_unlock:
 227	read_unlock(&tasklist_lock);
 228	rcu_read_unlock();
 229out:
 230	return error;
 231}
 232
 233/*
 234 * Ugh. To avoid negative return values, "getpriority()" will
 235 * not return the normal nice-value, but a negated value that
 236 * has been offset by 20 (ie it returns 40..1 instead of -20..19)
 237 * to stay compatible.
 238 */
 239SYSCALL_DEFINE2(getpriority, int, which, int, who)
 240{
 241	struct task_struct *g, *p;
 242	struct user_struct *user;
 243	const struct cred *cred = current_cred();
 244	long niceval, retval = -ESRCH;
 245	struct pid *pgrp;
 
 246
 247	if (which > PRIO_USER || which < PRIO_PROCESS)
 248		return -EINVAL;
 249
 250	rcu_read_lock();
 251	read_lock(&tasklist_lock);
 252	switch (which) {
 253		case PRIO_PROCESS:
 254			if (who)
 255				p = find_task_by_vpid(who);
 256			else
 257				p = current;
 258			if (p) {
 259				niceval = 20 - task_nice(p);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 260				if (niceval > retval)
 261					retval = niceval;
 262			}
 263			break;
 264		case PRIO_PGRP:
 265			if (who)
 266				pgrp = find_vpid(who);
 267			else
 268				pgrp = task_pgrp(current);
 269			do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
 270				niceval = 20 - task_nice(p);
 271				if (niceval > retval)
 272					retval = niceval;
 273			} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
 274			break;
 275		case PRIO_USER:
 276			user = (struct user_struct *) cred->user;
 277			if (!who)
 278				who = cred->uid;
 279			else if ((who != cred->uid) &&
 280				 !(user = find_user(who)))
 281				goto out_unlock;	/* No processes for this user */
 282
 283			do_each_thread(g, p) {
 284				if (__task_cred(p)->uid == who) {
 285					niceval = 20 - task_nice(p);
 286					if (niceval > retval)
 287						retval = niceval;
 288				}
 289			} while_each_thread(g, p);
 290			if (who != cred->uid)
 291				free_uid(user);		/* for find_user() */
 292			break;
 293	}
 294out_unlock:
 295	read_unlock(&tasklist_lock);
 296	rcu_read_unlock();
 297
 298	return retval;
 299}
 300
 301/**
 302 *	emergency_restart - reboot the system
 303 *
 304 *	Without shutting down any hardware or taking any locks
 305 *	reboot the system.  This is called when we know we are in
 306 *	trouble so this is our best effort to reboot.  This is
 307 *	safe to call in interrupt context.
 308 */
 309void emergency_restart(void)
 310{
 311	kmsg_dump(KMSG_DUMP_EMERG);
 312	machine_emergency_restart();
 313}
 314EXPORT_SYMBOL_GPL(emergency_restart);
 315
 316void kernel_restart_prepare(char *cmd)
 317{
 318	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
 319	system_state = SYSTEM_RESTART;
 320	usermodehelper_disable();
 321	device_shutdown();
 322	syscore_shutdown();
 323}
 324
 325/**
 326 *	register_reboot_notifier - Register function to be called at reboot time
 327 *	@nb: Info about notifier function to be called
 328 *
 329 *	Registers a function with the list of functions
 330 *	to be called at reboot time.
 331 *
 332 *	Currently always returns zero, as blocking_notifier_chain_register()
 333 *	always returns zero.
 334 */
 335int register_reboot_notifier(struct notifier_block *nb)
 336{
 337	return blocking_notifier_chain_register(&reboot_notifier_list, nb);
 338}
 339EXPORT_SYMBOL(register_reboot_notifier);
 340
 341/**
 342 *	unregister_reboot_notifier - Unregister previously registered reboot notifier
 343 *	@nb: Hook to be unregistered
 344 *
 345 *	Unregisters a previously registered reboot
 346 *	notifier function.
 347 *
 348 *	Returns zero on success, or %-ENOENT on failure.
 349 */
 350int unregister_reboot_notifier(struct notifier_block *nb)
 351{
 352	return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
 353}
 354EXPORT_SYMBOL(unregister_reboot_notifier);
 355
 356/**
 357 *	kernel_restart - reboot the system
 358 *	@cmd: pointer to buffer containing command to execute for restart
 359 *		or %NULL
 360 *
 361 *	Shutdown everything and perform a clean reboot.
 362 *	This is not safe to call in interrupt context.
 363 */
 364void kernel_restart(char *cmd)
 365{
 366	kernel_restart_prepare(cmd);
 367	if (!cmd)
 368		printk(KERN_EMERG "Restarting system.\n");
 369	else
 370		printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
 371	kmsg_dump(KMSG_DUMP_RESTART);
 372	machine_restart(cmd);
 373}
 374EXPORT_SYMBOL_GPL(kernel_restart);
 375
 376static void kernel_shutdown_prepare(enum system_states state)
 377{
 378	blocking_notifier_call_chain(&reboot_notifier_list,
 379		(state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
 380	system_state = state;
 381	usermodehelper_disable();
 382	device_shutdown();
 383}
 384/**
 385 *	kernel_halt - halt the system
 386 *
 387 *	Shutdown everything and perform a clean system halt.
 388 */
 389void kernel_halt(void)
 390{
 391	kernel_shutdown_prepare(SYSTEM_HALT);
 392	syscore_shutdown();
 393	printk(KERN_EMERG "System halted.\n");
 394	kmsg_dump(KMSG_DUMP_HALT);
 395	machine_halt();
 396}
 397
 398EXPORT_SYMBOL_GPL(kernel_halt);
 399
 400/**
 401 *	kernel_power_off - power_off the system
 402 *
 403 *	Shutdown everything and perform a clean system power_off.
 404 */
 405void kernel_power_off(void)
 406{
 407	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
 408	if (pm_power_off_prepare)
 409		pm_power_off_prepare();
 410	disable_nonboot_cpus();
 411	syscore_shutdown();
 412	printk(KERN_EMERG "Power down.\n");
 413	kmsg_dump(KMSG_DUMP_POWEROFF);
 414	machine_power_off();
 415}
 416EXPORT_SYMBOL_GPL(kernel_power_off);
 417
 418static DEFINE_MUTEX(reboot_mutex);
 419
 420/*
 421 * Reboot system call: for obvious reasons only root may call it,
 422 * and even root needs to set up some magic numbers in the registers
 423 * so that some mistake won't make this reboot the whole machine.
 424 * You can also set the meaning of the ctrl-alt-del-key here.
 425 *
 426 * reboot doesn't sync: do that yourself before calling this.
 427 */
 428SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 429		void __user *, arg)
 430{
 431	char buffer[256];
 432	int ret = 0;
 433
 434	/* We only trust the superuser with rebooting the system. */
 435	if (!capable(CAP_SYS_BOOT))
 436		return -EPERM;
 437
 438	/* For safety, we require "magic" arguments. */
 439	if (magic1 != LINUX_REBOOT_MAGIC1 ||
 440	    (magic2 != LINUX_REBOOT_MAGIC2 &&
 441	                magic2 != LINUX_REBOOT_MAGIC2A &&
 442			magic2 != LINUX_REBOOT_MAGIC2B &&
 443	                magic2 != LINUX_REBOOT_MAGIC2C))
 444		return -EINVAL;
 445
 446	/* Instead of trying to make the power_off code look like
 447	 * halt when pm_power_off is not set do it the easy way.
 448	 */
 449	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
 450		cmd = LINUX_REBOOT_CMD_HALT;
 451
 452	mutex_lock(&reboot_mutex);
 453	switch (cmd) {
 454	case LINUX_REBOOT_CMD_RESTART:
 455		kernel_restart(NULL);
 456		break;
 457
 458	case LINUX_REBOOT_CMD_CAD_ON:
 459		C_A_D = 1;
 460		break;
 461
 462	case LINUX_REBOOT_CMD_CAD_OFF:
 463		C_A_D = 0;
 464		break;
 465
 466	case LINUX_REBOOT_CMD_HALT:
 467		kernel_halt();
 468		do_exit(0);
 469		panic("cannot halt");
 470
 471	case LINUX_REBOOT_CMD_POWER_OFF:
 472		kernel_power_off();
 473		do_exit(0);
 474		break;
 475
 476	case LINUX_REBOOT_CMD_RESTART2:
 477		if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
 478			ret = -EFAULT;
 479			break;
 480		}
 481		buffer[sizeof(buffer) - 1] = '\0';
 482
 483		kernel_restart(buffer);
 484		break;
 485
 486#ifdef CONFIG_KEXEC
 487	case LINUX_REBOOT_CMD_KEXEC:
 488		ret = kernel_kexec();
 489		break;
 490#endif
 491
 492#ifdef CONFIG_HIBERNATION
 493	case LINUX_REBOOT_CMD_SW_SUSPEND:
 494		ret = hibernate();
 495		break;
 496#endif
 497
 498	default:
 499		ret = -EINVAL;
 500		break;
 501	}
 502	mutex_unlock(&reboot_mutex);
 503	return ret;
 504}
 505
 506static void deferred_cad(struct work_struct *dummy)
 507{
 508	kernel_restart(NULL);
 509}
 510
 511/*
 512 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
 513 * As it's called within an interrupt, it may NOT sync: the only choice
 514 * is whether to reboot at once, or just ignore the ctrl-alt-del.
 515 */
 516void ctrl_alt_del(void)
 517{
 518	static DECLARE_WORK(cad_work, deferred_cad);
 519
 520	if (C_A_D)
 521		schedule_work(&cad_work);
 522	else
 523		kill_cad_pid(SIGINT, 1);
 524}
 525	
 526/*
 527 * Unprivileged users may change the real gid to the effective gid
 528 * or vice versa.  (BSD-style)
 529 *
 530 * If you set the real gid at all, or set the effective gid to a value not
 531 * equal to the real gid, then the saved gid is set to the new effective gid.
 532 *
 533 * This makes it possible for a setgid program to completely drop its
 534 * privileges, which is often a useful assertion to make when you are doing
 535 * a security audit over a program.
 536 *
 537 * The general idea is that a program which uses just setregid() will be
 538 * 100% compatible with BSD.  A program which uses just setgid() will be
 539 * 100% compatible with POSIX with saved IDs. 
 540 *
 541 * SMP: There are not races, the GIDs are checked only by filesystem
 542 *      operations (as far as semantic preservation is concerned).
 543 */
 544SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid)
 
 545{
 
 546	const struct cred *old;
 547	struct cred *new;
 548	int retval;
 
 
 
 
 
 
 
 
 
 549
 550	new = prepare_creds();
 551	if (!new)
 552		return -ENOMEM;
 553	old = current_cred();
 554
 555	retval = -EPERM;
 556	if (rgid != (gid_t) -1) {
 557		if (old->gid == rgid ||
 558		    old->egid == rgid ||
 559		    nsown_capable(CAP_SETGID))
 560			new->gid = rgid;
 561		else
 562			goto error;
 563	}
 564	if (egid != (gid_t) -1) {
 565		if (old->gid == egid ||
 566		    old->egid == egid ||
 567		    old->sgid == egid ||
 568		    nsown_capable(CAP_SETGID))
 569			new->egid = egid;
 570		else
 571			goto error;
 572	}
 573
 574	if (rgid != (gid_t) -1 ||
 575	    (egid != (gid_t) -1 && egid != old->gid))
 576		new->sgid = new->egid;
 577	new->fsgid = new->egid;
 578
 
 
 
 
 579	return commit_creds(new);
 580
 581error:
 582	abort_creds(new);
 583	return retval;
 584}
 585
 
 
 
 
 
 586/*
 587 * setgid() is implemented like SysV w/ SAVED_IDS 
 588 *
 589 * SMP: Same implicit races as above.
 590 */
 591SYSCALL_DEFINE1(setgid, gid_t, gid)
 592{
 
 593	const struct cred *old;
 594	struct cred *new;
 595	int retval;
 
 
 
 
 
 596
 597	new = prepare_creds();
 598	if (!new)
 599		return -ENOMEM;
 600	old = current_cred();
 601
 602	retval = -EPERM;
 603	if (nsown_capable(CAP_SETGID))
 604		new->gid = new->egid = new->sgid = new->fsgid = gid;
 605	else if (gid == old->gid || gid == old->sgid)
 606		new->egid = new->fsgid = gid;
 607	else
 608		goto error;
 609
 
 
 
 
 610	return commit_creds(new);
 611
 612error:
 613	abort_creds(new);
 614	return retval;
 615}
 616
 
 
 
 
 
 617/*
 618 * change the user struct in a credentials set to match the new UID
 619 */
 620static int set_user(struct cred *new)
 621{
 622	struct user_struct *new_user;
 623
 624	new_user = alloc_uid(current_user_ns(), new->uid);
 625	if (!new_user)
 626		return -EAGAIN;
 627
 628	/*
 629	 * We don't fail in case of NPROC limit excess here because too many
 630	 * poorly written programs don't check set*uid() return code, assuming
 631	 * it never fails if called by root.  We may still enforce NPROC limit
 632	 * for programs doing set*uid()+execve() by harmlessly deferring the
 633	 * failure to the execve() stage.
 634	 */
 635	if (atomic_read(&new_user->processes) >= rlimit(RLIMIT_NPROC) &&
 636			new_user != INIT_USER)
 637		current->flags |= PF_NPROC_EXCEEDED;
 638	else
 639		current->flags &= ~PF_NPROC_EXCEEDED;
 640
 641	free_uid(new->user);
 642	new->user = new_user;
 643	return 0;
 644}
 645
 646/*
 647 * Unprivileged users may change the real uid to the effective uid
 648 * or vice versa.  (BSD-style)
 649 *
 650 * If you set the real uid at all, or set the effective uid to a value not
 651 * equal to the real uid, then the saved uid is set to the new effective uid.
 652 *
 653 * This makes it possible for a setuid program to completely drop its
 654 * privileges, which is often a useful assertion to make when you are doing
 655 * a security audit over a program.
 656 *
 657 * The general idea is that a program which uses just setreuid() will be
 658 * 100% compatible with BSD.  A program which uses just setuid() will be
 659 * 100% compatible with POSIX with saved IDs. 
 660 */
 661SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
 662{
 
 663	const struct cred *old;
 664	struct cred *new;
 665	int retval;
 
 
 
 
 
 
 
 
 
 666
 667	new = prepare_creds();
 668	if (!new)
 669		return -ENOMEM;
 670	old = current_cred();
 671
 672	retval = -EPERM;
 673	if (ruid != (uid_t) -1) {
 674		new->uid = ruid;
 675		if (old->uid != ruid &&
 676		    old->euid != ruid &&
 677		    !nsown_capable(CAP_SETUID))
 678			goto error;
 679	}
 680
 681	if (euid != (uid_t) -1) {
 682		new->euid = euid;
 683		if (old->uid != euid &&
 684		    old->euid != euid &&
 685		    old->suid != euid &&
 686		    !nsown_capable(CAP_SETUID))
 687			goto error;
 688	}
 689
 690	if (new->uid != old->uid) {
 691		retval = set_user(new);
 692		if (retval < 0)
 693			goto error;
 694	}
 695	if (ruid != (uid_t) -1 ||
 696	    (euid != (uid_t) -1 && euid != old->uid))
 697		new->suid = new->euid;
 698	new->fsuid = new->euid;
 699
 700	retval = security_task_fix_setuid(new, old, LSM_SETID_RE);
 701	if (retval < 0)
 702		goto error;
 703
 
 
 
 
 704	return commit_creds(new);
 705
 706error:
 707	abort_creds(new);
 708	return retval;
 709}
 710		
 
 
 
 
 
 711/*
 712 * setuid() is implemented like SysV with SAVED_IDS 
 713 * 
 714 * Note that SAVED_ID's is deficient in that a setuid root program
 715 * like sendmail, for example, cannot set its uid to be a normal 
 716 * user and then switch back, because if you're root, setuid() sets
 717 * the saved uid too.  If you don't like this, blame the bright people
 718 * in the POSIX committee and/or USG.  Note that the BSD-style setreuid()
 719 * will allow a root program to temporarily drop privileges and be able to
 720 * regain them by swapping the real and effective uid.  
 721 */
 722SYSCALL_DEFINE1(setuid, uid_t, uid)
 723{
 
 724	const struct cred *old;
 725	struct cred *new;
 726	int retval;
 
 
 
 
 
 727
 728	new = prepare_creds();
 729	if (!new)
 730		return -ENOMEM;
 731	old = current_cred();
 732
 733	retval = -EPERM;
 734	if (nsown_capable(CAP_SETUID)) {
 735		new->suid = new->uid = uid;
 736		if (uid != old->uid) {
 737			retval = set_user(new);
 738			if (retval < 0)
 739				goto error;
 740		}
 741	} else if (uid != old->uid && uid != new->suid) {
 742		goto error;
 743	}
 744
 745	new->fsuid = new->euid = uid;
 746
 747	retval = security_task_fix_setuid(new, old, LSM_SETID_ID);
 748	if (retval < 0)
 749		goto error;
 750
 
 
 
 
 751	return commit_creds(new);
 752
 753error:
 754	abort_creds(new);
 755	return retval;
 756}
 757
 
 
 
 
 
 758
 759/*
 760 * This function implements a generic ability to update ruid, euid,
 761 * and suid.  This allows you to implement the 4.4 compatible seteuid().
 762 */
 763SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
 764{
 
 765	const struct cred *old;
 766	struct cred *new;
 767	int retval;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 768
 769	new = prepare_creds();
 770	if (!new)
 771		return -ENOMEM;
 772
 773	old = current_cred();
 774
 775	retval = -EPERM;
 776	if (!nsown_capable(CAP_SETUID)) {
 777		if (ruid != (uid_t) -1 && ruid != old->uid &&
 778		    ruid != old->euid  && ruid != old->suid)
 779			goto error;
 780		if (euid != (uid_t) -1 && euid != old->uid &&
 781		    euid != old->euid  && euid != old->suid)
 782			goto error;
 783		if (suid != (uid_t) -1 && suid != old->uid &&
 784		    suid != old->euid  && suid != old->suid)
 785			goto error;
 786	}
 787
 788	if (ruid != (uid_t) -1) {
 789		new->uid = ruid;
 790		if (ruid != old->uid) {
 791			retval = set_user(new);
 792			if (retval < 0)
 793				goto error;
 794		}
 795	}
 796	if (euid != (uid_t) -1)
 797		new->euid = euid;
 798	if (suid != (uid_t) -1)
 799		new->suid = suid;
 800	new->fsuid = new->euid;
 801
 802	retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
 803	if (retval < 0)
 804		goto error;
 805
 
 
 
 
 806	return commit_creds(new);
 807
 808error:
 809	abort_creds(new);
 810	return retval;
 811}
 812
 813SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __user *, suid)
 
 
 
 
 
 814{
 815	const struct cred *cred = current_cred();
 816	int retval;
 
 817
 818	if (!(retval   = put_user(cred->uid,  ruid)) &&
 819	    !(retval   = put_user(cred->euid, euid)))
 820		retval = put_user(cred->suid, suid);
 821
 
 
 
 
 
 
 822	return retval;
 823}
 824
 825/*
 826 * Same as above, but for rgid, egid, sgid.
 827 */
 828SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
 829{
 
 830	const struct cred *old;
 831	struct cred *new;
 832	int retval;
 
 
 
 
 
 
 
 
 
 
 
 
 833
 834	new = prepare_creds();
 835	if (!new)
 836		return -ENOMEM;
 837	old = current_cred();
 838
 839	retval = -EPERM;
 840	if (!nsown_capable(CAP_SETGID)) {
 841		if (rgid != (gid_t) -1 && rgid != old->gid &&
 842		    rgid != old->egid  && rgid != old->sgid)
 843			goto error;
 844		if (egid != (gid_t) -1 && egid != old->gid &&
 845		    egid != old->egid  && egid != old->sgid)
 846			goto error;
 847		if (sgid != (gid_t) -1 && sgid != old->gid &&
 848		    sgid != old->egid  && sgid != old->sgid)
 849			goto error;
 850	}
 851
 852	if (rgid != (gid_t) -1)
 853		new->gid = rgid;
 854	if (egid != (gid_t) -1)
 855		new->egid = egid;
 856	if (sgid != (gid_t) -1)
 857		new->sgid = sgid;
 858	new->fsgid = new->egid;
 859
 
 
 
 
 860	return commit_creds(new);
 861
 862error:
 863	abort_creds(new);
 864	return retval;
 865}
 866
 867SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __user *, sgid)
 
 
 
 
 
 868{
 869	const struct cred *cred = current_cred();
 870	int retval;
 
 871
 872	if (!(retval   = put_user(cred->gid,  rgid)) &&
 873	    !(retval   = put_user(cred->egid, egid)))
 874		retval = put_user(cred->sgid, sgid);
 
 
 
 
 
 
 
 875
 876	return retval;
 877}
 878
 879
 880/*
 881 * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This
 882 * is used for "access()" and for the NFS daemon (letting nfsd stay at
 883 * whatever uid it wants to). It normally shadows "euid", except when
 884 * explicitly set by setfsuid() or for access..
 885 */
 886SYSCALL_DEFINE1(setfsuid, uid_t, uid)
 887{
 888	const struct cred *old;
 889	struct cred *new;
 890	uid_t old_fsuid;
 
 
 
 
 
 
 
 
 891
 892	new = prepare_creds();
 893	if (!new)
 894		return current_fsuid();
 895	old = current_cred();
 896	old_fsuid = old->fsuid;
 897
 898	if (uid == old->uid  || uid == old->euid  ||
 899	    uid == old->suid || uid == old->fsuid ||
 900	    nsown_capable(CAP_SETUID)) {
 901		if (uid != old_fsuid) {
 902			new->fsuid = uid;
 903			if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
 904				goto change_okay;
 905		}
 906	}
 907
 908	abort_creds(new);
 909	return old_fsuid;
 910
 911change_okay:
 912	commit_creds(new);
 913	return old_fsuid;
 914}
 915
 
 
 
 
 
 916/*
 917 * Samma på svenska..
 918 */
 919SYSCALL_DEFINE1(setfsgid, gid_t, gid)
 920{
 921	const struct cred *old;
 922	struct cred *new;
 923	gid_t old_fsgid;
 
 
 
 
 
 
 
 
 924
 925	new = prepare_creds();
 926	if (!new)
 927		return current_fsgid();
 928	old = current_cred();
 929	old_fsgid = old->fsgid;
 930
 931	if (gid == old->gid  || gid == old->egid  ||
 932	    gid == old->sgid || gid == old->fsgid ||
 933	    nsown_capable(CAP_SETGID)) {
 934		if (gid != old_fsgid) {
 935			new->fsgid = gid;
 936			goto change_okay;
 
 937		}
 938	}
 939
 940	abort_creds(new);
 941	return old_fsgid;
 942
 943change_okay:
 944	commit_creds(new);
 945	return old_fsgid;
 946}
 947
 948void do_sys_times(struct tms *tms)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 949{
 950	cputime_t tgutime, tgstime, cutime, cstime;
 
 
 951
 952	spin_lock_irq(&current->sighand->siglock);
 953	thread_group_times(current, &tgutime, &tgstime);
 
 
 
 
 
 
 
 
 
 954	cutime = current->signal->cutime;
 955	cstime = current->signal->cstime;
 956	spin_unlock_irq(&current->sighand->siglock);
 957	tms->tms_utime = cputime_to_clock_t(tgutime);
 958	tms->tms_stime = cputime_to_clock_t(tgstime);
 959	tms->tms_cutime = cputime_to_clock_t(cutime);
 960	tms->tms_cstime = cputime_to_clock_t(cstime);
 961}
 962
 963SYSCALL_DEFINE1(times, struct tms __user *, tbuf)
 964{
 965	if (tbuf) {
 966		struct tms tmp;
 967
 968		do_sys_times(&tmp);
 969		if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
 970			return -EFAULT;
 971	}
 972	force_successful_syscall_return();
 973	return (long) jiffies_64_to_clock_t(get_jiffies_64());
 974}
 975
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 976/*
 977 * This needs some heavy checking ...
 978 * I just haven't the stomach for it. I also don't fully
 979 * understand sessions/pgrp etc. Let somebody who does explain it.
 980 *
 981 * OK, I think I have the protection semantics right.... this is really
 982 * only important on a multi-user system anyway, to make sure one user
 983 * can't send a signal to a process owned by another.  -TYT, 12/12/91
 984 *
 985 * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
 986 * LBT 04.03.94
 987 */
 988SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
 989{
 990	struct task_struct *p;
 991	struct task_struct *group_leader = current->group_leader;
 992	struct pid *pgrp;
 993	int err;
 994
 995	if (!pid)
 996		pid = task_pid_vnr(group_leader);
 997	if (!pgid)
 998		pgid = pid;
 999	if (pgid < 0)
1000		return -EINVAL;
1001	rcu_read_lock();
1002
1003	/* From this point forward we keep holding onto the tasklist lock
1004	 * so that our parent does not change from under us. -DaveM
1005	 */
1006	write_lock_irq(&tasklist_lock);
1007
1008	err = -ESRCH;
1009	p = find_task_by_vpid(pid);
1010	if (!p)
1011		goto out;
1012
1013	err = -EINVAL;
1014	if (!thread_group_leader(p))
1015		goto out;
1016
1017	if (same_thread_group(p->real_parent, group_leader)) {
1018		err = -EPERM;
1019		if (task_session(p) != task_session(group_leader))
1020			goto out;
1021		err = -EACCES;
1022		if (p->did_exec)
1023			goto out;
1024	} else {
1025		err = -ESRCH;
1026		if (p != group_leader)
1027			goto out;
1028	}
1029
1030	err = -EPERM;
1031	if (p->signal->leader)
1032		goto out;
1033
1034	pgrp = task_pid(p);
1035	if (pgid != pid) {
1036		struct task_struct *g;
1037
1038		pgrp = find_vpid(pgid);
1039		g = pid_task(pgrp, PIDTYPE_PGID);
1040		if (!g || task_session(g) != task_session(group_leader))
1041			goto out;
1042	}
1043
1044	err = security_task_setpgid(p, pgid);
1045	if (err)
1046		goto out;
1047
1048	if (task_pgrp(p) != pgrp)
1049		change_pid(p, PIDTYPE_PGID, pgrp);
1050
1051	err = 0;
1052out:
1053	/* All paths lead to here, thus we are safe. -DaveM */
1054	write_unlock_irq(&tasklist_lock);
1055	rcu_read_unlock();
1056	return err;
1057}
1058
1059SYSCALL_DEFINE1(getpgid, pid_t, pid)
1060{
1061	struct task_struct *p;
1062	struct pid *grp;
1063	int retval;
1064
1065	rcu_read_lock();
1066	if (!pid)
1067		grp = task_pgrp(current);
1068	else {
1069		retval = -ESRCH;
1070		p = find_task_by_vpid(pid);
1071		if (!p)
1072			goto out;
1073		grp = task_pgrp(p);
1074		if (!grp)
1075			goto out;
1076
1077		retval = security_task_getpgid(p);
1078		if (retval)
1079			goto out;
1080	}
1081	retval = pid_vnr(grp);
1082out:
1083	rcu_read_unlock();
1084	return retval;
1085}
1086
 
 
 
 
 
1087#ifdef __ARCH_WANT_SYS_GETPGRP
1088
1089SYSCALL_DEFINE0(getpgrp)
1090{
1091	return sys_getpgid(0);
1092}
1093
1094#endif
1095
1096SYSCALL_DEFINE1(getsid, pid_t, pid)
1097{
1098	struct task_struct *p;
1099	struct pid *sid;
1100	int retval;
1101
1102	rcu_read_lock();
1103	if (!pid)
1104		sid = task_session(current);
1105	else {
1106		retval = -ESRCH;
1107		p = find_task_by_vpid(pid);
1108		if (!p)
1109			goto out;
1110		sid = task_session(p);
1111		if (!sid)
1112			goto out;
1113
1114		retval = security_task_getsid(p);
1115		if (retval)
1116			goto out;
1117	}
1118	retval = pid_vnr(sid);
1119out:
1120	rcu_read_unlock();
1121	return retval;
1122}
1123
1124SYSCALL_DEFINE0(setsid)
 
 
 
 
 
 
 
 
 
 
 
1125{
1126	struct task_struct *group_leader = current->group_leader;
1127	struct pid *sid = task_pid(group_leader);
1128	pid_t session = pid_vnr(sid);
1129	int err = -EPERM;
1130
1131	write_lock_irq(&tasklist_lock);
1132	/* Fail if I am already a session leader */
1133	if (group_leader->signal->leader)
1134		goto out;
1135
1136	/* Fail if a process group id already exists that equals the
1137	 * proposed session id.
1138	 */
1139	if (pid_task(sid, PIDTYPE_PGID))
1140		goto out;
1141
1142	group_leader->signal->leader = 1;
1143	__set_special_pids(sid);
1144
1145	proc_clear_tty(group_leader);
1146
1147	err = session;
1148out:
1149	write_unlock_irq(&tasklist_lock);
1150	if (err > 0) {
1151		proc_sid_connector(group_leader);
1152		sched_autogroup_create_attach(group_leader);
1153	}
1154	return err;
1155}
1156
 
 
 
 
 
1157DECLARE_RWSEM(uts_sem);
1158
1159#ifdef COMPAT_UTS_MACHINE
1160#define override_architecture(name) \
1161	(personality(current->personality) == PER_LINUX32 && \
1162	 copy_to_user(name->machine, COMPAT_UTS_MACHINE, \
1163		      sizeof(COMPAT_UTS_MACHINE)))
1164#else
1165#define override_architecture(name)	0
1166#endif
1167
1168/*
1169 * Work around broken programs that cannot handle "Linux 3.0".
1170 * Instead we map 3.x to 2.6.40+x, so e.g. 3.0 would be 2.6.40
 
 
1171 */
1172static int override_release(char __user *release, int len)
1173{
1174	int ret = 0;
1175	char buf[65];
1176
1177	if (current->personality & UNAME26) {
1178		char *rest = UTS_RELEASE;
 
1179		int ndots = 0;
1180		unsigned v;
 
1181
1182		while (*rest) {
1183			if (*rest == '.' && ++ndots >= 3)
1184				break;
1185			if (!isdigit(*rest) && *rest != '.')
1186				break;
1187			rest++;
1188		}
1189		v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
1190		snprintf(buf, len, "2.6.%u%s", v, rest);
1191		ret = copy_to_user(release, buf, len);
 
1192	}
1193	return ret;
1194}
1195
1196SYSCALL_DEFINE1(newuname, struct new_utsname __user *, name)
1197{
1198	int errno = 0;
1199
1200	down_read(&uts_sem);
1201	if (copy_to_user(name, utsname(), sizeof *name))
1202		errno = -EFAULT;
1203	up_read(&uts_sem);
 
 
1204
1205	if (!errno && override_release(name->release, sizeof(name->release)))
1206		errno = -EFAULT;
1207	if (!errno && override_architecture(name))
1208		errno = -EFAULT;
1209	return errno;
1210}
1211
1212#ifdef __ARCH_WANT_SYS_OLD_UNAME
1213/*
1214 * Old cruft
1215 */
1216SYSCALL_DEFINE1(uname, struct old_utsname __user *, name)
1217{
1218	int error = 0;
1219
1220	if (!name)
1221		return -EFAULT;
1222
1223	down_read(&uts_sem);
1224	if (copy_to_user(name, utsname(), sizeof(*name)))
1225		error = -EFAULT;
1226	up_read(&uts_sem);
 
 
1227
1228	if (!error && override_release(name->release, sizeof(name->release)))
1229		error = -EFAULT;
1230	if (!error && override_architecture(name))
1231		error = -EFAULT;
1232	return error;
1233}
1234
1235SYSCALL_DEFINE1(olduname, struct oldold_utsname __user *, name)
1236{
1237	int error;
1238
1239	if (!name)
1240		return -EFAULT;
1241	if (!access_ok(VERIFY_WRITE, name, sizeof(struct oldold_utsname)))
1242		return -EFAULT;
1243
1244	down_read(&uts_sem);
1245	error = __copy_to_user(&name->sysname, &utsname()->sysname,
1246			       __OLD_UTS_LEN);
1247	error |= __put_user(0, name->sysname + __OLD_UTS_LEN);
1248	error |= __copy_to_user(&name->nodename, &utsname()->nodename,
1249				__OLD_UTS_LEN);
1250	error |= __put_user(0, name->nodename + __OLD_UTS_LEN);
1251	error |= __copy_to_user(&name->release, &utsname()->release,
1252				__OLD_UTS_LEN);
1253	error |= __put_user(0, name->release + __OLD_UTS_LEN);
1254	error |= __copy_to_user(&name->version, &utsname()->version,
1255				__OLD_UTS_LEN);
1256	error |= __put_user(0, name->version + __OLD_UTS_LEN);
1257	error |= __copy_to_user(&name->machine, &utsname()->machine,
1258				__OLD_UTS_LEN);
1259	error |= __put_user(0, name->machine + __OLD_UTS_LEN);
1260	up_read(&uts_sem);
 
 
1261
1262	if (!error && override_architecture(name))
1263		error = -EFAULT;
1264	if (!error && override_release(name->release, sizeof(name->release)))
1265		error = -EFAULT;
1266	return error ? -EFAULT : 0;
1267}
1268#endif
1269
1270SYSCALL_DEFINE2(sethostname, char __user *, name, int, len)
1271{
1272	int errno;
1273	char tmp[__NEW_UTS_LEN];
1274
1275	if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1276		return -EPERM;
1277
1278	if (len < 0 || len > __NEW_UTS_LEN)
1279		return -EINVAL;
1280	down_write(&uts_sem);
1281	errno = -EFAULT;
1282	if (!copy_from_user(tmp, name, len)) {
1283		struct new_utsname *u = utsname();
1284
 
 
1285		memcpy(u->nodename, tmp, len);
1286		memset(u->nodename + len, 0, sizeof(u->nodename) - len);
1287		errno = 0;
 
 
1288	}
1289	up_write(&uts_sem);
1290	return errno;
1291}
1292
1293#ifdef __ARCH_WANT_SYS_GETHOSTNAME
1294
1295SYSCALL_DEFINE2(gethostname, char __user *, name, int, len)
1296{
1297	int i, errno;
1298	struct new_utsname *u;
 
1299
1300	if (len < 0)
1301		return -EINVAL;
1302	down_read(&uts_sem);
1303	u = utsname();
1304	i = 1 + strlen(u->nodename);
1305	if (i > len)
1306		i = len;
1307	errno = 0;
1308	if (copy_to_user(name, u->nodename, i))
1309		errno = -EFAULT;
1310	up_read(&uts_sem);
1311	return errno;
 
 
1312}
1313
1314#endif
1315
1316/*
1317 * Only setdomainname; getdomainname can be implemented by calling
1318 * uname()
1319 */
1320SYSCALL_DEFINE2(setdomainname, char __user *, name, int, len)
1321{
1322	int errno;
1323	char tmp[__NEW_UTS_LEN];
1324
1325	if (!ns_capable(current->nsproxy->uts_ns->user_ns, CAP_SYS_ADMIN))
1326		return -EPERM;
1327	if (len < 0 || len > __NEW_UTS_LEN)
1328		return -EINVAL;
1329
1330	down_write(&uts_sem);
1331	errno = -EFAULT;
1332	if (!copy_from_user(tmp, name, len)) {
1333		struct new_utsname *u = utsname();
1334
 
 
1335		memcpy(u->domainname, tmp, len);
1336		memset(u->domainname + len, 0, sizeof(u->domainname) - len);
1337		errno = 0;
 
 
1338	}
1339	up_write(&uts_sem);
1340	return errno;
1341}
1342
1343SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1344{
1345	struct rlimit value;
1346	int ret;
1347
1348	ret = do_prlimit(current, resource, NULL, &value);
1349	if (!ret)
1350		ret = copy_to_user(rlim, &value, sizeof(*rlim)) ? -EFAULT : 0;
1351
1352	return ret;
1353}
1354
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1355#ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
1356
1357/*
1358 *	Back compatibility for getrlimit. Needed for some apps.
1359 */
1360 
1361SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
1362		struct rlimit __user *, rlim)
1363{
1364	struct rlimit x;
1365	if (resource >= RLIM_NLIMITS)
1366		return -EINVAL;
1367
 
1368	task_lock(current->group_leader);
1369	x = current->signal->rlim[resource];
1370	task_unlock(current->group_leader);
1371	if (x.rlim_cur > 0x7FFFFFFF)
1372		x.rlim_cur = 0x7FFFFFFF;
1373	if (x.rlim_max > 0x7FFFFFFF)
1374		x.rlim_max = 0x7FFFFFFF;
1375	return copy_to_user(rlim, &x, sizeof(x))?-EFAULT:0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1376}
 
1377
1378#endif
1379
1380static inline bool rlim64_is_infinity(__u64 rlim64)
1381{
1382#if BITS_PER_LONG < 64
1383	return rlim64 >= ULONG_MAX;
1384#else
1385	return rlim64 == RLIM64_INFINITY;
1386#endif
1387}
1388
1389static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64)
1390{
1391	if (rlim->rlim_cur == RLIM_INFINITY)
1392		rlim64->rlim_cur = RLIM64_INFINITY;
1393	else
1394		rlim64->rlim_cur = rlim->rlim_cur;
1395	if (rlim->rlim_max == RLIM_INFINITY)
1396		rlim64->rlim_max = RLIM64_INFINITY;
1397	else
1398		rlim64->rlim_max = rlim->rlim_max;
1399}
1400
1401static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim)
1402{
1403	if (rlim64_is_infinity(rlim64->rlim_cur))
1404		rlim->rlim_cur = RLIM_INFINITY;
1405	else
1406		rlim->rlim_cur = (unsigned long)rlim64->rlim_cur;
1407	if (rlim64_is_infinity(rlim64->rlim_max))
1408		rlim->rlim_max = RLIM_INFINITY;
1409	else
1410		rlim->rlim_max = (unsigned long)rlim64->rlim_max;
1411}
1412
1413/* make sure you are allowed to change @tsk limits before calling this */
1414int do_prlimit(struct task_struct *tsk, unsigned int resource,
1415		struct rlimit *new_rlim, struct rlimit *old_rlim)
1416{
1417	struct rlimit *rlim;
1418	int retval = 0;
1419
1420	if (resource >= RLIM_NLIMITS)
1421		return -EINVAL;
1422	if (new_rlim) {
1423		if (new_rlim->rlim_cur > new_rlim->rlim_max)
1424			return -EINVAL;
1425		if (resource == RLIMIT_NOFILE &&
1426				new_rlim->rlim_max > sysctl_nr_open)
1427			return -EPERM;
1428	}
1429
1430	/* protect tsk->signal and tsk->sighand from disappearing */
1431	read_lock(&tasklist_lock);
1432	if (!tsk->sighand) {
1433		retval = -ESRCH;
1434		goto out;
1435	}
1436
1437	rlim = tsk->signal->rlim + resource;
1438	task_lock(tsk->group_leader);
1439	if (new_rlim) {
1440		/* Keep the capable check against init_user_ns until
1441		   cgroups can contain all limits */
1442		if (new_rlim->rlim_max > rlim->rlim_max &&
1443				!capable(CAP_SYS_RESOURCE))
1444			retval = -EPERM;
1445		if (!retval)
1446			retval = security_task_setrlimit(tsk->group_leader,
1447					resource, new_rlim);
1448		if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
1449			/*
1450			 * The caller is asking for an immediate RLIMIT_CPU
1451			 * expiry.  But we use the zero value to mean "it was
1452			 * never set".  So let's cheat and make it one second
1453			 * instead
1454			 */
1455			new_rlim->rlim_cur = 1;
1456		}
1457	}
1458	if (!retval) {
1459		if (old_rlim)
1460			*old_rlim = *rlim;
1461		if (new_rlim)
1462			*rlim = *new_rlim;
1463	}
1464	task_unlock(tsk->group_leader);
1465
1466	/*
1467	 * RLIMIT_CPU handling.   Note that the kernel fails to return an error
1468	 * code if it rejected the user's attempt to set RLIMIT_CPU.  This is a
1469	 * very long-standing error, and fixing it now risks breakage of
1470	 * applications, so we live with it
1471	 */
1472	 if (!retval && new_rlim && resource == RLIMIT_CPU &&
1473			 new_rlim->rlim_cur != RLIM_INFINITY)
 
1474		update_rlimit_cpu(tsk, new_rlim->rlim_cur);
1475out:
1476	read_unlock(&tasklist_lock);
1477	return retval;
1478}
1479
1480/* rcu lock must be held */
1481static int check_prlimit_permission(struct task_struct *task)
 
1482{
1483	const struct cred *cred = current_cred(), *tcred;
 
1484
1485	if (current == task)
1486		return 0;
1487
1488	tcred = __task_cred(task);
1489	if (cred->user->user_ns == tcred->user->user_ns &&
1490	    (cred->uid == tcred->euid &&
1491	     cred->uid == tcred->suid &&
1492	     cred->uid == tcred->uid  &&
1493	     cred->gid == tcred->egid &&
1494	     cred->gid == tcred->sgid &&
1495	     cred->gid == tcred->gid))
1496		return 0;
1497	if (ns_capable(tcred->user->user_ns, CAP_SYS_RESOURCE))
1498		return 0;
1499
1500	return -EPERM;
1501}
1502
1503SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
1504		const struct rlimit64 __user *, new_rlim,
1505		struct rlimit64 __user *, old_rlim)
1506{
1507	struct rlimit64 old64, new64;
1508	struct rlimit old, new;
1509	struct task_struct *tsk;
 
1510	int ret;
1511
 
 
 
1512	if (new_rlim) {
1513		if (copy_from_user(&new64, new_rlim, sizeof(new64)))
1514			return -EFAULT;
1515		rlim64_to_rlim(&new64, &new);
 
1516	}
1517
1518	rcu_read_lock();
1519	tsk = pid ? find_task_by_vpid(pid) : current;
1520	if (!tsk) {
1521		rcu_read_unlock();
1522		return -ESRCH;
1523	}
1524	ret = check_prlimit_permission(tsk);
1525	if (ret) {
1526		rcu_read_unlock();
1527		return ret;
1528	}
1529	get_task_struct(tsk);
1530	rcu_read_unlock();
1531
1532	ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
1533			old_rlim ? &old : NULL);
1534
1535	if (!ret && old_rlim) {
1536		rlim_to_rlim64(&old, &old64);
1537		if (copy_to_user(old_rlim, &old64, sizeof(old64)))
1538			ret = -EFAULT;
1539	}
1540
1541	put_task_struct(tsk);
1542	return ret;
1543}
1544
1545SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
1546{
1547	struct rlimit new_rlim;
1548
1549	if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
1550		return -EFAULT;
1551	return do_prlimit(current, resource, &new_rlim, NULL);
1552}
1553
1554/*
1555 * It would make sense to put struct rusage in the task_struct,
1556 * except that would make the task_struct be *really big*.  After
1557 * task_struct gets moved into malloc'ed memory, it would
1558 * make sense to do this.  It will make moving the rest of the information
1559 * a lot simpler!  (Which we're not doing right now because we're not
1560 * measuring them yet).
1561 *
1562 * When sampling multiple threads for RUSAGE_SELF, under SMP we might have
1563 * races with threads incrementing their own counters.  But since word
1564 * reads are atomic, we either get new values or old values and we don't
1565 * care which for the sums.  We always take the siglock to protect reading
1566 * the c* fields from p->signal from races with exit.c updating those
1567 * fields when reaping, so a sample either gets all the additions of a
1568 * given child after it's reaped, or none so this sample is before reaping.
1569 *
1570 * Locking:
1571 * We need to take the siglock for CHILDEREN, SELF and BOTH
1572 * for  the cases current multithreaded, non-current single threaded
1573 * non-current multithreaded.  Thread traversal is now safe with
1574 * the siglock held.
1575 * Strictly speaking, we donot need to take the siglock if we are current and
1576 * single threaded,  as no one else can take our signal_struct away, no one
1577 * else can  reap the  children to update signal->c* counters, and no one else
1578 * can race with the signal-> fields. If we do not take any lock, the
1579 * signal-> fields could be read out of order while another thread was just
1580 * exiting. So we should  place a read memory barrier when we avoid the lock.
1581 * On the writer side,  write memory barrier is implied in  __exit_signal
1582 * as __exit_signal releases  the siglock spinlock after updating the signal->
1583 * fields. But we don't do this yet to keep things simple.
1584 *
1585 */
1586
1587static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
1588{
1589	r->ru_nvcsw += t->nvcsw;
1590	r->ru_nivcsw += t->nivcsw;
1591	r->ru_minflt += t->min_flt;
1592	r->ru_majflt += t->maj_flt;
1593	r->ru_inblock += task_io_get_inblock(t);
1594	r->ru_oublock += task_io_get_oublock(t);
1595}
1596
1597static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
1598{
1599	struct task_struct *t;
1600	unsigned long flags;
1601	cputime_t tgutime, tgstime, utime, stime;
1602	unsigned long maxrss = 0;
1603
1604	memset((char *) r, 0, sizeof *r);
1605	utime = stime = cputime_zero;
1606
1607	if (who == RUSAGE_THREAD) {
1608		task_times(current, &utime, &stime);
1609		accumulate_thread_rusage(p, r);
1610		maxrss = p->signal->maxrss;
1611		goto out;
1612	}
1613
1614	if (!lock_task_sighand(p, &flags))
1615		return;
1616
1617	switch (who) {
1618		case RUSAGE_BOTH:
1619		case RUSAGE_CHILDREN:
1620			utime = p->signal->cutime;
1621			stime = p->signal->cstime;
1622			r->ru_nvcsw = p->signal->cnvcsw;
1623			r->ru_nivcsw = p->signal->cnivcsw;
1624			r->ru_minflt = p->signal->cmin_flt;
1625			r->ru_majflt = p->signal->cmaj_flt;
1626			r->ru_inblock = p->signal->cinblock;
1627			r->ru_oublock = p->signal->coublock;
1628			maxrss = p->signal->cmaxrss;
1629
1630			if (who == RUSAGE_CHILDREN)
1631				break;
1632
1633		case RUSAGE_SELF:
1634			thread_group_times(p, &tgutime, &tgstime);
1635			utime = cputime_add(utime, tgutime);
1636			stime = cputime_add(stime, tgstime);
1637			r->ru_nvcsw += p->signal->nvcsw;
1638			r->ru_nivcsw += p->signal->nivcsw;
1639			r->ru_minflt += p->signal->min_flt;
1640			r->ru_majflt += p->signal->maj_flt;
1641			r->ru_inblock += p->signal->inblock;
1642			r->ru_oublock += p->signal->oublock;
1643			if (maxrss < p->signal->maxrss)
1644				maxrss = p->signal->maxrss;
1645			t = p;
1646			do {
1647				accumulate_thread_rusage(t, r);
1648				t = next_thread(t);
1649			} while (t != p);
1650			break;
1651
1652		default:
1653			BUG();
1654	}
1655	unlock_task_sighand(p, &flags);
1656
1657out:
1658	cputime_to_timeval(utime, &r->ru_utime);
1659	cputime_to_timeval(stime, &r->ru_stime);
1660
1661	if (who != RUSAGE_CHILDREN) {
1662		struct mm_struct *mm = get_task_mm(p);
 
1663		if (mm) {
1664			setmax_mm_hiwater_rss(&maxrss, mm);
1665			mmput(mm);
1666		}
1667	}
1668	r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
1669}
1670
1671int getrusage(struct task_struct *p, int who, struct rusage __user *ru)
1672{
1673	struct rusage r;
1674	k_getrusage(p, who, &r);
 
 
 
 
 
1675	return copy_to_user(ru, &r, sizeof(r)) ? -EFAULT : 0;
1676}
1677
1678SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)
 
1679{
 
 
1680	if (who != RUSAGE_SELF && who != RUSAGE_CHILDREN &&
1681	    who != RUSAGE_THREAD)
1682		return -EINVAL;
1683	return getrusage(current, who, ru);
 
 
1684}
 
1685
1686SYSCALL_DEFINE1(umask, int, mask)
1687{
1688	mask = xchg(&current->fs->umask, mask & S_IRWXUGO);
1689	return mask;
1690}
1691
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1692SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
1693		unsigned long, arg4, unsigned long, arg5)
1694{
1695	struct task_struct *me = current;
1696	unsigned char comm[sizeof(me->comm)];
1697	long error;
1698
1699	error = security_task_prctl(option, arg2, arg3, arg4, arg5);
1700	if (error != -ENOSYS)
1701		return error;
1702
1703	error = 0;
1704	switch (option) {
1705		case PR_SET_PDEATHSIG:
1706			if (!valid_signal(arg2)) {
1707				error = -EINVAL;
1708				break;
1709			}
1710			me->pdeath_signal = arg2;
1711			error = 0;
1712			break;
1713		case PR_GET_PDEATHSIG:
1714			error = put_user(me->pdeath_signal, (int __user *)arg2);
1715			break;
1716		case PR_GET_DUMPABLE:
1717			error = get_dumpable(me->mm);
1718			break;
1719		case PR_SET_DUMPABLE:
1720			if (arg2 < 0 || arg2 > 1) {
1721				error = -EINVAL;
1722				break;
1723			}
1724			set_dumpable(me->mm, arg2);
1725			error = 0;
1726			break;
1727
1728		case PR_SET_UNALIGN:
1729			error = SET_UNALIGN_CTL(me, arg2);
1730			break;
1731		case PR_GET_UNALIGN:
1732			error = GET_UNALIGN_CTL(me, arg2);
1733			break;
1734		case PR_SET_FPEMU:
1735			error = SET_FPEMU_CTL(me, arg2);
1736			break;
1737		case PR_GET_FPEMU:
1738			error = GET_FPEMU_CTL(me, arg2);
1739			break;
1740		case PR_SET_FPEXC:
1741			error = SET_FPEXC_CTL(me, arg2);
1742			break;
1743		case PR_GET_FPEXC:
1744			error = GET_FPEXC_CTL(me, arg2);
1745			break;
1746		case PR_GET_TIMING:
1747			error = PR_TIMING_STATISTICAL;
1748			break;
1749		case PR_SET_TIMING:
1750			if (arg2 != PR_TIMING_STATISTICAL)
1751				error = -EINVAL;
1752			else
1753				error = 0;
1754			break;
1755
1756		case PR_SET_NAME:
1757			comm[sizeof(me->comm)-1] = 0;
1758			if (strncpy_from_user(comm, (char __user *)arg2,
1759					      sizeof(me->comm) - 1) < 0)
1760				return -EFAULT;
1761			set_task_comm(me, comm);
1762			return 0;
1763		case PR_GET_NAME:
1764			get_task_comm(comm, me);
1765			if (copy_to_user((char __user *)arg2, comm,
1766					 sizeof(comm)))
1767				return -EFAULT;
1768			return 0;
1769		case PR_GET_ENDIAN:
1770			error = GET_ENDIAN(me, arg2);
1771			break;
1772		case PR_SET_ENDIAN:
1773			error = SET_ENDIAN(me, arg2);
 
 
 
 
 
 
 
 
 
 
1774			break;
 
 
 
1775
1776		case PR_GET_SECCOMP:
1777			error = prctl_get_seccomp();
1778			break;
1779		case PR_SET_SECCOMP:
1780			error = prctl_set_seccomp(arg2);
1781			break;
1782		case PR_GET_TSC:
1783			error = GET_TSC_CTL(arg2);
1784			break;
1785		case PR_SET_TSC:
1786			error = SET_TSC_CTL(arg2);
1787			break;
1788		case PR_TASK_PERF_EVENTS_DISABLE:
1789			error = perf_event_task_disable();
1790			break;
1791		case PR_TASK_PERF_EVENTS_ENABLE:
1792			error = perf_event_task_enable();
1793			break;
1794		case PR_GET_TIMERSLACK:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1795			error = current->timer_slack_ns;
1796			break;
1797		case PR_SET_TIMERSLACK:
1798			if (arg2 <= 0)
1799				current->timer_slack_ns =
1800					current->default_timer_slack_ns;
1801			else
1802				current->timer_slack_ns = arg2;
1803			error = 0;
1804			break;
1805		case PR_MCE_KILL:
1806			if (arg4 | arg5)
1807				return -EINVAL;
1808			switch (arg2) {
1809			case PR_MCE_KILL_CLEAR:
1810				if (arg3 != 0)
1811					return -EINVAL;
1812				current->flags &= ~PF_MCE_PROCESS;
1813				break;
1814			case PR_MCE_KILL_SET:
1815				current->flags |= PF_MCE_PROCESS;
1816				if (arg3 == PR_MCE_KILL_EARLY)
1817					current->flags |= PF_MCE_EARLY;
1818				else if (arg3 == PR_MCE_KILL_LATE)
1819					current->flags &= ~PF_MCE_EARLY;
1820				else if (arg3 == PR_MCE_KILL_DEFAULT)
1821					current->flags &=
1822						~(PF_MCE_EARLY|PF_MCE_PROCESS);
1823				else
1824					return -EINVAL;
1825				break;
1826			default:
1827				return -EINVAL;
1828			}
1829			error = 0;
1830			break;
1831		case PR_MCE_KILL_GET:
1832			if (arg2 | arg3 | arg4 | arg5)
1833				return -EINVAL;
1834			if (current->flags & PF_MCE_PROCESS)
1835				error = (current->flags & PF_MCE_EARLY) ?
1836					PR_MCE_KILL_EARLY : PR_MCE_KILL_LATE;
 
 
 
1837			else
1838				error = PR_MCE_KILL_DEFAULT;
1839			break;
1840		default:
1841			error = -EINVAL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1842			break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1843	}
1844	return error;
1845}
1846
1847SYSCALL_DEFINE3(getcpu, unsigned __user *, cpup, unsigned __user *, nodep,
1848		struct getcpu_cache __user *, unused)
1849{
1850	int err = 0;
1851	int cpu = raw_smp_processor_id();
 
1852	if (cpup)
1853		err |= put_user(cpu, cpup);
1854	if (nodep)
1855		err |= put_user(cpu_to_node(cpu), nodep);
1856	return err ? -EFAULT : 0;
1857}
1858
1859char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
1860
1861static void argv_cleanup(struct subprocess_info *info)
1862{
1863	argv_free(info->argv);
1864}
1865
1866/**
1867 * orderly_poweroff - Trigger an orderly system poweroff
1868 * @force: force poweroff if command execution fails
1869 *
1870 * This may be called from any context to trigger a system shutdown.
1871 * If the orderly shutdown fails, it will force an immediate shutdown.
1872 */
1873int orderly_poweroff(bool force)
1874{
1875	int argc;
1876	char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
1877	static char *envp[] = {
1878		"HOME=/",
1879		"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
1880		NULL
1881	};
1882	int ret = -ENOMEM;
1883	struct subprocess_info *info;
1884
1885	if (argv == NULL) {
1886		printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
1887		       __func__, poweroff_cmd);
1888		goto out;
1889	}
 
 
1890
1891	info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
1892	if (info == NULL) {
1893		argv_free(argv);
 
 
 
 
 
 
 
 
 
 
 
 
 
1894		goto out;
 
 
 
 
 
 
 
 
 
1895	}
1896
1897	call_usermodehelper_setfns(info, NULL, argv_cleanup, NULL);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1898
1899	ret = call_usermodehelper_exec(info, UMH_NO_WAIT);
 
 
1900
1901  out:
1902	if (ret && force) {
1903		printk(KERN_WARNING "Failed to start orderly shutdown: "
1904		       "forcing the issue\n");
1905
1906		/* I guess this should try to kick off some daemon to
1907		   sync and poweroff asap.  Or not even bother syncing
1908		   if we're doing an emergency shutdown? */
1909		emergency_sync();
1910		kernel_power_off();
1911	}
1912
1913	return ret;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1914}
1915EXPORT_SYMBOL_GPL(orderly_poweroff);