kernel/kmod.c

   1 /*
   2         kmod, the new module loader (replaces kerneld)
   3         Kirk Petersen
   4
   5         Reorganized not to be a daemon by Adam Richter, with guidance
   6         from Greg Zornetzer.
   7
   8         Modified to avoid chroot and file sharing problems.
   9         Mikael Pettersson
  10
  11         Limit the concurrent number of kmod modprobes to catch loops from
  12         "modprobe needs a service that is in a module".
  13         Keith Owens <kaos@ocs.com.au> December 1999
  14
  15         Unblock all signals when we exec a usermode process.
  16         Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000
  17
  18         call_usermodehelper wait flag, and remove exec_usermodehelper.
  19         Rusty Russell <rusty@rustcorp.com.au>  Jan 2003
  20 */
  21 #include <linux/module.h>
  22 #include <linux/sched.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/unistd.h>
  25 #include <linux/kmod.h>
  26 #include <linux/slab.h>
  27 #include <linux/completion.h>
  28 #include <linux/cred.h>
  29 #include <linux/file.h>
  30 #include <linux/fdtable.h>
  31 #include <linux/workqueue.h>
  32 #include <linux/security.h>
  33 #include <linux/mount.h>
  34 #include <linux/kernel.h>
  35 #include <linux/init.h>
  36 #include <linux/resource.h>
  37 #include <linux/notifier.h>
  38 #include <linux/suspend.h>
  39 #include <linux/rwsem.h>
  40 #include <linux/ptrace.h>
  41 #include <linux/async.h>
  42 #include <asm/uaccess.h>
  43
  44 #include <trace/events/module.h>
  45
  46 extern int max_threads;
  47
  48 static struct workqueue_struct *khelper_wq;
  49
  50 #define CAP_BSET        (void *)1
  51 #define CAP_PI          (void *)2
  52
  53 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
  54 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
  55 static DEFINE_SPINLOCK(umh_sysctl_lock);
  56 static DECLARE_RWSEM(umhelper_sem);
  57
  58 #ifdef CONFIG_MODULES
  59
  60 /*
  61         modprobe_path is set via /proc/sys.
  62 */
  63 char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
  64
  65 static void free_modprobe_argv(struct subprocess_info *info)
  66 {
  67         kfree(info->argv[3]); /* check call_modprobe() */
  68         kfree(info->argv);
  69 }
  70
  71 static int call_modprobe(char *module_name, int wait)
  72 {
  73         struct subprocess_info *info;
  74         static char *envp[] = {
  75                 "HOME=/",
  76                 "TERM=linux",
  77                 "PATH=/sbin:/usr/sbin:/bin:/usr/bin",
  78                 NULL
  79         };
  80
  81         char **argv = kmalloc(sizeof(char *[5]), GFP_KERNEL);
  82         if (!argv)
  83                 goto out;
  84
  85         module_name = kstrdup(module_name, GFP_KERNEL);
  86         if (!module_name)
  87                 goto free_argv;
  88
  89         argv[0] = modprobe_path;
  90         argv[1] = "-q";
  91         argv[2] = "--";
  92         argv[3] = module_name;  /* check free_modprobe_argv() */
  93         argv[4] = NULL;
  94
  95         info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
  96                                          NULL, free_modprobe_argv, NULL);
  97         if (!info)
  98                 goto free_module_name;
  99
 100         return call_usermodehelper_exec(info, wait | UMH_KILLABLE);
 101
 102 free_module_name:
 103         kfree(module_name);
 104 free_argv:
 105         kfree(argv);
 106 out:
 107         return -ENOMEM;
 108 }
 109
 110 /**
 111  * __request_module - try to load a kernel module
 112  * @wait: wait (or not) for the operation to complete
 113  * @fmt: printf style format string for the name of the module
 114  * @...: arguments as specified in the format string
 115  *
 116  * Load a module using the user mode module loader. The function returns
 117  * zero on success or a negative errno code or positive exit code from
 118  * "modprobe" on failure. Note that a successful module load does not mean
 119  * the module did not then unload and exit on an error of its own. Callers
 120  * must check that the service they requested is now available not blindly
 121  * invoke it.
 122  *
 123  * If module auto-loading support is disabled then this function
 124  * becomes a no-operation.
 125  */
 126 int __request_module(bool wait, const char *fmt, ...)
 127 {
 128         va_list args;
 129         char module_name[MODULE_NAME_LEN];
 130         unsigned int max_modprobes;
 131         int ret;
 132         static atomic_t kmod_concurrent = ATOMIC_INIT(0);
 133 #define MAX_KMOD_CONCURRENT 50  /* Completely arbitrary value - KAO */
 134         static int kmod_loop_msg;
 135
 136         /*
 137          * We don't allow synchronous module loading from async.  Module
 138          * init may invoke async_synchronize_full() which will end up
 139          * waiting for this task which already is waiting for the module
 140          * loading to complete, leading to a deadlock.
 141          */
 142         WARN_ON_ONCE(wait && current_is_async());
 143
 144         if (!modprobe_path[0])
 145                 return 0;
 146
 147         va_start(args, fmt);
 148         ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
 149         va_end(args);
 150         if (ret >= MODULE_NAME_LEN)
 151                 return -ENAMETOOLONG;
 152
 153         ret = security_kernel_module_request(module_name);
 154         if (ret)
 155                 return ret;
 156
 157         /* If modprobe needs a service that is in a module, we get a recursive
 158          * loop.  Limit the number of running kmod threads to max_threads/2 or
 159          * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
 160          * would be to run the parents of this process, counting how many times
 161          * kmod was invoked.  That would mean accessing the internals of the
 162          * process tables to get the command line, proc_pid_cmdline is static
 163          * and it is not worth changing the proc code just to handle this case.
 164          * KAO.
 165          *
 166          * "trace the ppid" is simple, but will fail if someone's
 167          * parent exits.  I think this is as good as it gets. --RR
 168          */
 169         max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
 170         atomic_inc(&kmod_concurrent);
 171         if (atomic_read(&kmod_concurrent) > max_modprobes) {
 172                 /* We may be blaming an innocent here, but unlikely */
 173                 if (kmod_loop_msg < 5) {
 174                         printk(KERN_ERR
 175                                "request_module: runaway loop modprobe %s\n",
 176                                module_name);
 177                         kmod_loop_msg++;
 178                 }
 179                 atomic_dec(&kmod_concurrent);
 180                 return -ENOMEM;
 181         }
 182
 183         trace_module_request(module_name, wait, _RET_IP_);
 184
 185         ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 186
 187         atomic_dec(&kmod_concurrent);
 188         return ret;
 189 }
 190 EXPORT_SYMBOL(__request_module);
 191 #endif /* CONFIG_MODULES */
 192
 193 static void call_usermodehelper_freeinfo(struct subprocess_info *info)
 194 {
 195         if (info->cleanup)
 196                 (*info->cleanup)(info);
 197         kfree(info);
 198 }
 199
 200 static void umh_complete(struct subprocess_info *sub_info)
 201 {
 202         struct completion *comp = xchg(&sub_info->complete, NULL);
 203         /*
 204          * See call_usermodehelper_exec(). If xchg() returns NULL
 205          * we own sub_info, the UMH_KILLABLE caller has gone away
 206          * or the caller used UMH_NO_WAIT.
 207          */
 208         if (comp)
 209                 complete(comp);
 210         else
 211                 call_usermodehelper_freeinfo(sub_info);
 212 }
 213
 214 /*
 215  * This is the task which runs the usermode application
 216  */
 217 static int call_usermodehelper_exec_async(void *data)
 218 {
 219         struct subprocess_info *sub_info = data;
 220         struct cred *new;
 221         int retval;
 222
 223         spin_lock_irq(&current->sighand->siglock);
 224         flush_signal_handlers(current, 1);
 225         spin_unlock_irq(&current->sighand->siglock);
 226
 227         /*
 228          * Our parent is keventd, which runs with elevated scheduling priority.
 229          * Avoid propagating that into the userspace child.
 230          */
 231         set_user_nice(current, 0);
 232
 233         retval = -ENOMEM;
 234         new = prepare_kernel_cred(current);
 235         if (!new)
 236                 goto out;
 237
 238         spin_lock(&umh_sysctl_lock);
 239         new->cap_bset = cap_intersect(usermodehelper_bset, new->cap_bset);
 240         new->cap_inheritable = cap_intersect(usermodehelper_inheritable,
 241                                              new->cap_inheritable);
 242         spin_unlock(&umh_sysctl_lock);
 243
 244         if (sub_info->init) {
 245                 retval = sub_info->init(sub_info, new);
 246                 if (retval) {
 247                         abort_creds(new);
 248                         goto out;
 249                 }
 250         }
 251
 252         commit_creds(new);
 253
 254         retval = do_execve(getname_kernel(sub_info->path),
 255                            (const char __user *const __user *)sub_info->argv,
 256                            (const char __user *const __user *)sub_info->envp);
 257 out:
 258         sub_info->retval = retval;
 259         /*
 260          * call_usermodehelper_exec_sync() will call umh_complete
 261          * if UHM_WAIT_PROC.
 262          */
 263         if (!(sub_info->wait & UMH_WAIT_PROC))
 264                 umh_complete(sub_info);
 265         if (!retval)
 266                 return 0;
 267         do_exit(0);
 268 }
 269
 270 /* Keventd can't block, but this (a child) can. */
 271 static int call_usermodehelper_exec_sync(void *data)
 272 {
 273         struct subprocess_info *sub_info = data;
 274         pid_t pid;
 275
 276         /* If SIGCLD is ignored sys_wait4 won't populate the status. */
 277         kernel_sigaction(SIGCHLD, SIG_DFL);
 278         pid = kernel_thread(call_usermodehelper_exec_async, sub_info, SIGCHLD);
 279         if (pid < 0) {
 280                 sub_info->retval = pid;
 281         } else {
 282                 int ret = -ECHILD;
 283                 /*
 284                  * Normally it is bogus to call wait4() from in-kernel because
 285                  * wait4() wants to write the exit code to a userspace address.
 286                  * But call_usermodehelper_exec_sync() always runs as keventd,
 287                  * and put_user() to a kernel address works OK for kernel
 288                  * threads, due to their having an mm_segment_t which spans the
 289                  * entire address space.
 290                  *
 291                  * Thus the __user pointer cast is valid here.
 292                  */
 293                 sys_wait4(pid, (int __user *)&ret, 0, NULL);
 294
 295                 /*
 296                  * If ret is 0, either call_usermodehelper_exec_async failed and
 297                  * the real error code is already in sub_info->retval or
 298                  * sub_info->retval is 0 anyway, so don't mess with it then.
 299                  */
 300                 if (ret)
 301                         sub_info->retval = ret;
 302         }
 303
 304         umh_complete(sub_info);
 305         do_exit(0);
 306 }
 307
 308 /* This is run by khelper thread  */
 309 static void call_usermodehelper_exec_work(struct work_struct *work)
 310 {
 311         struct subprocess_info *sub_info =
 312                 container_of(work, struct subprocess_info, work);
 313         pid_t pid;
 314
 315         if (sub_info->wait & UMH_WAIT_PROC)
 316                 pid = kernel_thread(call_usermodehelper_exec_sync, sub_info,
 317                                     CLONE_FS | CLONE_FILES | SIGCHLD);
 318         else
 319                 pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
 320                                     SIGCHLD);
 321
 322         if (pid < 0) {
 323                 sub_info->retval = pid;
 324                 umh_complete(sub_info);
 325         }
 326 }
 327
 328 /*
 329  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
 330  * (used for preventing user land processes from being created after the user
 331  * land has been frozen during a system-wide hibernation or suspend operation).
 332  * Should always be manipulated under umhelper_sem acquired for write.
 333  */
 334 static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
 335
 336 /* Number of helpers running */
 337 static atomic_t running_helpers = ATOMIC_INIT(0);
 338
 339 /*
 340  * Wait queue head used by usermodehelper_disable() to wait for all running
 341  * helpers to finish.
 342  */
 343 static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
 344
 345 /*
 346  * Used by usermodehelper_read_lock_wait() to wait for usermodehelper_disabled
 347  * to become 'false'.
 348  */
 349 static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
 350
 351 /*
 352  * Time to wait for running_helpers to become zero before the setting of
 353  * usermodehelper_disabled in usermodehelper_disable() fails
 354  */
 355 #define RUNNING_HELPERS_TIMEOUT (5 * HZ)
 356
 357 int usermodehelper_read_trylock(void)
 358 {
 359         DEFINE_WAIT(wait);
 360         int ret = 0;
 361
 362         down_read(&umhelper_sem);
 363         for (;;) {
 364                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
 365                                 TASK_INTERRUPTIBLE);
 366                 if (!usermodehelper_disabled)
 367                         break;
 368
 369                 if (usermodehelper_disabled == UMH_DISABLED)
 370                         ret = -EAGAIN;
 371
 372                 up_read(&umhelper_sem);
 373
 374                 if (ret)
 375                         break;
 376
 377                 schedule();
 378                 try_to_freeze();
 379
 380                 down_read(&umhelper_sem);
 381         }
 382         finish_wait(&usermodehelper_disabled_waitq, &wait);
 383         return ret;
 384 }
 385 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
 386
 387 long usermodehelper_read_lock_wait(long timeout)
 388 {
 389         DEFINE_WAIT(wait);
 390
 391         if (timeout < 0)
 392                 return -EINVAL;
 393
 394         down_read(&umhelper_sem);
 395         for (;;) {
 396                 prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
 397                                 TASK_UNINTERRUPTIBLE);
 398                 if (!usermodehelper_disabled)
 399                         break;
 400
 401                 up_read(&umhelper_sem);
 402
 403                 timeout = schedule_timeout(timeout);
 404                 if (!timeout)
 405                         break;
 406
 407                 down_read(&umhelper_sem);
 408         }
 409         finish_wait(&usermodehelper_disabled_waitq, &wait);
 410         return timeout;
 411 }
 412 EXPORT_SYMBOL_GPL(usermodehelper_read_lock_wait);
 413
 414 void usermodehelper_read_unlock(void)
 415 {
 416         up_read(&umhelper_sem);
 417 }
 418 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
 419
 420 /**
 421  * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
 422  * @depth: New value to assign to usermodehelper_disabled.
 423  *
 424  * Change the value of usermodehelper_disabled (under umhelper_sem locked for
 425  * writing) and wakeup tasks waiting for it to change.
 426  */
 427 void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
 428 {
 429         down_write(&umhelper_sem);
 430         usermodehelper_disabled = depth;
 431         wake_up(&usermodehelper_disabled_waitq);
 432         up_write(&umhelper_sem);
 433 }
 434
 435 /**
 436  * __usermodehelper_disable - Prevent new helpers from being started.
 437  * @depth: New value to assign to usermodehelper_disabled.
 438  *
 439  * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
 440  */
 441 int __usermodehelper_disable(enum umh_disable_depth depth)
 442 {
 443         long retval;
 444
 445         if (!depth)
 446                 return -EINVAL;
 447
 448         down_write(&umhelper_sem);
 449         usermodehelper_disabled = depth;
 450         up_write(&umhelper_sem);
 451
 452         /*
 453          * From now on call_usermodehelper_exec() won't start any new
 454          * helpers, so it is sufficient if running_helpers turns out to
 455          * be zero at one point (it may be increased later, but that
 456          * doesn't matter).
 457          */
 458         retval = wait_event_timeout(running_helpers_waitq,
 459                                         atomic_read(&running_helpers) == 0,
 460                                         RUNNING_HELPERS_TIMEOUT);
 461         if (retval)
 462                 return 0;
 463
 464         __usermodehelper_set_disable_depth(UMH_ENABLED);
 465         return -EAGAIN;
 466 }
 467
 468 static void helper_lock(void)
 469 {
 470         atomic_inc(&running_helpers);
 471         smp_mb__after_atomic();
 472 }
 473
 474 static void helper_unlock(void)
 475 {
 476         if (atomic_dec_and_test(&running_helpers))
 477                 wake_up(&running_helpers_waitq);
 478 }
 479
 480 /**
 481  * call_usermodehelper_setup - prepare to call a usermode helper
 482  * @path: path to usermode executable
 483  * @argv: arg vector for process
 484  * @envp: environment for process
 485  * @gfp_mask: gfp mask for memory allocation
 486  * @cleanup: a cleanup function
 487  * @init: an init function
 488  * @data: arbitrary context sensitive data
 489  *
 490  * Returns either %NULL on allocation failure, or a subprocess_info
 491  * structure.  This should be passed to call_usermodehelper_exec to
 492  * exec the process and free the structure.
 493  *
 494  * The init function is used to customize the helper process prior to
 495  * exec.  A non-zero return code causes the process to error out, exit,
 496  * and return the failure to the calling process
 497  *
 498  * The cleanup function is just before ethe subprocess_info is about to
 499  * be freed.  This can be used for freeing the argv and envp.  The
 500  * Function must be runnable in either a process context or the
 501  * context in which call_usermodehelper_exec is called.
 502  */
 503 struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
 504                 char **envp, gfp_t gfp_mask,
 505                 int (*init)(struct subprocess_info *info, struct cred *new),
 506                 void (*cleanup)(struct subprocess_info *info),
 507                 void *data)
 508 {
 509         struct subprocess_info *sub_info;
 510         sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
 511         if (!sub_info)
 512                 goto out;
 513
 514         INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
 515         sub_info->path = path;
 516         sub_info->argv = argv;
 517         sub_info->envp = envp;
 518
 519         sub_info->cleanup = cleanup;
 520         sub_info->init = init;
 521         sub_info->data = data;
 522   out:
 523         return sub_info;
 524 }
 525 EXPORT_SYMBOL(call_usermodehelper_setup);
 526
 527 /**
 528  * call_usermodehelper_exec - start a usermode application
 529  * @sub_info: information about the subprocessa
 530  * @wait: wait for the application to finish and return status.
 531  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
 532  *        when the program couldn't be exec'ed. This makes it safe to call
 533  *        from interrupt context.
 534  *
 535  * Runs a user-space application.  The application is started
 536  * asynchronously if wait is not set, and runs as a child of keventd.
 537  * (ie. it runs with full root capabilities).
 538  */
 539 int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
 540 {
 541         DECLARE_COMPLETION_ONSTACK(done);
 542         int retval = 0;
 543
 544         if (!sub_info->path) {
 545                 call_usermodehelper_freeinfo(sub_info);
 546                 return -EINVAL;
 547         }
 548         helper_lock();
 549         if (!khelper_wq || usermodehelper_disabled) {
 550                 retval = -EBUSY;
 551                 goto out;
 552         }
 553         /*
 554          * Set the completion pointer only if there is a waiter.
 555          * This makes it possible to use umh_complete to free
 556          * the data structure in case of UMH_NO_WAIT.
 557          */
 558         sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done;
 559         sub_info->wait = wait;
 560
 561         queue_work(khelper_wq, &sub_info->work);
 562         if (wait == UMH_NO_WAIT)        /* task has freed sub_info */
 563                 goto unlock;
 564
 565         if (wait & UMH_KILLABLE) {
 566                 retval = wait_for_completion_killable(&done);
 567                 if (!retval)
 568                         goto wait_done;
 569
 570                 /* umh_complete() will see NULL and free sub_info */
 571                 if (xchg(&sub_info->complete, NULL))
 572                         goto unlock;
 573                 /* fallthrough, umh_complete() was already called */
 574         }
 575
 576         wait_for_completion(&done);
 577 wait_done:
 578         retval = sub_info->retval;
 579 out:
 580         call_usermodehelper_freeinfo(sub_info);
 581 unlock:
 582         helper_unlock();
 583         return retval;
 584 }
 585 EXPORT_SYMBOL(call_usermodehelper_exec);
 586
 587 /**
 588  * call_usermodehelper() - prepare and start a usermode application
 589  * @path: path to usermode executable
 590  * @argv: arg vector for process
 591  * @envp: environment for process
 592  * @wait: wait for the application to finish and return status.
 593  *        when UMH_NO_WAIT don't wait at all, but you get no useful error back
 594  *        when the program couldn't be exec'ed. This makes it safe to call
 595  *        from interrupt context.
 596  *
 597  * This function is the equivalent to use call_usermodehelper_setup() and
 598  * call_usermodehelper_exec().
 599  */
 600 int call_usermodehelper(char *path, char **argv, char **envp, int wait)
 601 {
 602         struct subprocess_info *info;
 603         gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
 604
 605         info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
 606                                          NULL, NULL, NULL);
 607         if (info == NULL)
 608                 return -ENOMEM;
 609
 610         return call_usermodehelper_exec(info, wait);
 611 }
 612 EXPORT_SYMBOL(call_usermodehelper);
 613
 614 static int proc_cap_handler(struct ctl_table *table, int write,
 615                          void __user *buffer, size_t *lenp, loff_t *ppos)
 616 {
 617         struct ctl_table t;
 618         unsigned long cap_array[_KERNEL_CAPABILITY_U32S];
 619         kernel_cap_t new_cap;
 620         int err, i;
 621
 622         if (write && (!capable(CAP_SETPCAP) ||
 623                       !capable(CAP_SYS_MODULE)))
 624                 return -EPERM;
 625
 626         /*
 627          * convert from the global kernel_cap_t to the ulong array to print to
 628          * userspace if this is a read.
 629          */
 630         spin_lock(&umh_sysctl_lock);
 631         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)  {
 632                 if (table->data == CAP_BSET)
 633                         cap_array[i] = usermodehelper_bset.cap[i];
 634                 else if (table->data == CAP_PI)
 635                         cap_array[i] = usermodehelper_inheritable.cap[i];
 636                 else
 637                         BUG();
 638         }
 639         spin_unlock(&umh_sysctl_lock);
 640
 641         t = *table;
 642         t.data = &cap_array;
 643
 644         /*
 645          * actually read or write and array of ulongs from userspace.  Remember
 646          * these are least significant 32 bits first
 647          */
 648         err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
 649         if (err < 0)
 650                 return err;
 651
 652         /*
 653          * convert from the sysctl array of ulongs to the kernel_cap_t
 654          * internal representation
 655          */
 656         for (i = 0; i < _KERNEL_CAPABILITY_U32S; i++)
 657                 new_cap.cap[i] = cap_array[i];
 658
 659         /*
 660          * Drop everything not in the new_cap (but don't add things)
 661          */
 662         spin_lock(&umh_sysctl_lock);
 663         if (write) {
 664                 if (table->data == CAP_BSET)
 665                         usermodehelper_bset = cap_intersect(usermodehelper_bset, new_cap);
 666                 if (table->data == CAP_PI)
 667                         usermodehelper_inheritable = cap_intersect(usermodehelper_inheritable, new_cap);
 668         }
 669         spin_unlock(&umh_sysctl_lock);
 670
 671         return 0;
 672 }
 673
 674 struct ctl_table usermodehelper_table[] = {
 675         {
 676                 .procname       = "bset",
 677                 .data           = CAP_BSET,
 678                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
 679                 .mode           = 0600,
 680                 .proc_handler   = proc_cap_handler,
 681         },
 682         {
 683                 .procname       = "inheritable",
 684                 .data           = CAP_PI,
 685                 .maxlen         = _KERNEL_CAPABILITY_U32S * sizeof(unsigned long),
 686                 .mode           = 0600,
 687                 .proc_handler   = proc_cap_handler,
 688         },
 689         { }
 690 };
 691
 692 void __init usermodehelper_init(void)
 693 {
 694         khelper_wq = create_singlethread_workqueue("khelper");
 695         BUG_ON(!khelper_wq);
 696 }