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