linux/kernel/sys.c
<<
>>
Prefs
   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);
1916
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.