xref: /openbmc/linux/fs/exec.c (revision c376222960ae91d5ffb9197ee36771aaed1d9f90)
1 /*
2  *  linux/fs/exec.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6 
7 /*
8  * #!-checking implemented by tytso.
9  */
10 /*
11  * Demand-loading implemented 01.12.91 - no need to read anything but
12  * the header into memory. The inode of the executable is put into
13  * "current->executable", and page faults do the actual loading. Clean.
14  *
15  * Once more I can proudly say that linux stood up to being changed: it
16  * was less than 2 hours work to get demand-loading completely implemented.
17  *
18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
19  * current->executable is only used by the procfs.  This allows a dispatch
20  * table to check for several different types  of binary formats.  We keep
21  * trying until we recognize the file or we run out of supported binary
22  * formats.
23  */
24 
25 #include <linux/slab.h>
26 #include <linux/file.h>
27 #include <linux/mman.h>
28 #include <linux/a.out.h>
29 #include <linux/stat.h>
30 #include <linux/fcntl.h>
31 #include <linux/smp_lock.h>
32 #include <linux/init.h>
33 #include <linux/pagemap.h>
34 #include <linux/highmem.h>
35 #include <linux/spinlock.h>
36 #include <linux/key.h>
37 #include <linux/personality.h>
38 #include <linux/binfmts.h>
39 #include <linux/swap.h>
40 #include <linux/utsname.h>
41 #include <linux/pid_namespace.h>
42 #include <linux/module.h>
43 #include <linux/namei.h>
44 #include <linux/proc_fs.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/syscalls.h>
49 #include <linux/rmap.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53 
54 #include <asm/uaccess.h>
55 #include <asm/mmu_context.h>
56 
57 #ifdef CONFIG_KMOD
58 #include <linux/kmod.h>
59 #endif
60 
61 int core_uses_pid;
62 char core_pattern[128] = "core";
63 int suid_dumpable = 0;
64 
65 EXPORT_SYMBOL(suid_dumpable);
66 /* The maximal length of core_pattern is also specified in sysctl.c */
67 
68 static struct linux_binfmt *formats;
69 static DEFINE_RWLOCK(binfmt_lock);
70 
71 int register_binfmt(struct linux_binfmt * fmt)
72 {
73 	struct linux_binfmt ** tmp = &formats;
74 
75 	if (!fmt)
76 		return -EINVAL;
77 	if (fmt->next)
78 		return -EBUSY;
79 	write_lock(&binfmt_lock);
80 	while (*tmp) {
81 		if (fmt == *tmp) {
82 			write_unlock(&binfmt_lock);
83 			return -EBUSY;
84 		}
85 		tmp = &(*tmp)->next;
86 	}
87 	fmt->next = formats;
88 	formats = fmt;
89 	write_unlock(&binfmt_lock);
90 	return 0;
91 }
92 
93 EXPORT_SYMBOL(register_binfmt);
94 
95 int unregister_binfmt(struct linux_binfmt * fmt)
96 {
97 	struct linux_binfmt ** tmp = &formats;
98 
99 	write_lock(&binfmt_lock);
100 	while (*tmp) {
101 		if (fmt == *tmp) {
102 			*tmp = fmt->next;
103 			write_unlock(&binfmt_lock);
104 			return 0;
105 		}
106 		tmp = &(*tmp)->next;
107 	}
108 	write_unlock(&binfmt_lock);
109 	return -EINVAL;
110 }
111 
112 EXPORT_SYMBOL(unregister_binfmt);
113 
114 static inline void put_binfmt(struct linux_binfmt * fmt)
115 {
116 	module_put(fmt->module);
117 }
118 
119 /*
120  * Note that a shared library must be both readable and executable due to
121  * security reasons.
122  *
123  * Also note that we take the address to load from from the file itself.
124  */
125 asmlinkage long sys_uselib(const char __user * library)
126 {
127 	struct file * file;
128 	struct nameidata nd;
129 	int error;
130 
131 	error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
132 	if (error)
133 		goto out;
134 
135 	error = -EINVAL;
136 	if (!S_ISREG(nd.dentry->d_inode->i_mode))
137 		goto exit;
138 
139 	error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
140 	if (error)
141 		goto exit;
142 
143 	file = nameidata_to_filp(&nd, O_RDONLY);
144 	error = PTR_ERR(file);
145 	if (IS_ERR(file))
146 		goto out;
147 
148 	error = -ENOEXEC;
149 	if(file->f_op) {
150 		struct linux_binfmt * fmt;
151 
152 		read_lock(&binfmt_lock);
153 		for (fmt = formats ; fmt ; fmt = fmt->next) {
154 			if (!fmt->load_shlib)
155 				continue;
156 			if (!try_module_get(fmt->module))
157 				continue;
158 			read_unlock(&binfmt_lock);
159 			error = fmt->load_shlib(file);
160 			read_lock(&binfmt_lock);
161 			put_binfmt(fmt);
162 			if (error != -ENOEXEC)
163 				break;
164 		}
165 		read_unlock(&binfmt_lock);
166 	}
167 	fput(file);
168 out:
169   	return error;
170 exit:
171 	release_open_intent(&nd);
172 	path_release(&nd);
173 	goto out;
174 }
175 
176 /*
177  * count() counts the number of strings in array ARGV.
178  */
179 static int count(char __user * __user * argv, int max)
180 {
181 	int i = 0;
182 
183 	if (argv != NULL) {
184 		for (;;) {
185 			char __user * p;
186 
187 			if (get_user(p, argv))
188 				return -EFAULT;
189 			if (!p)
190 				break;
191 			argv++;
192 			if(++i > max)
193 				return -E2BIG;
194 			cond_resched();
195 		}
196 	}
197 	return i;
198 }
199 
200 /*
201  * 'copy_strings()' copies argument/environment strings from user
202  * memory to free pages in kernel mem. These are in a format ready
203  * to be put directly into the top of new user memory.
204  */
205 static int copy_strings(int argc, char __user * __user * argv,
206 			struct linux_binprm *bprm)
207 {
208 	struct page *kmapped_page = NULL;
209 	char *kaddr = NULL;
210 	int ret;
211 
212 	while (argc-- > 0) {
213 		char __user *str;
214 		int len;
215 		unsigned long pos;
216 
217 		if (get_user(str, argv+argc) ||
218 				!(len = strnlen_user(str, bprm->p))) {
219 			ret = -EFAULT;
220 			goto out;
221 		}
222 
223 		if (bprm->p < len)  {
224 			ret = -E2BIG;
225 			goto out;
226 		}
227 
228 		bprm->p -= len;
229 		/* XXX: add architecture specific overflow check here. */
230 		pos = bprm->p;
231 
232 		while (len > 0) {
233 			int i, new, err;
234 			int offset, bytes_to_copy;
235 			struct page *page;
236 
237 			offset = pos % PAGE_SIZE;
238 			i = pos/PAGE_SIZE;
239 			page = bprm->page[i];
240 			new = 0;
241 			if (!page) {
242 				page = alloc_page(GFP_HIGHUSER);
243 				bprm->page[i] = page;
244 				if (!page) {
245 					ret = -ENOMEM;
246 					goto out;
247 				}
248 				new = 1;
249 			}
250 
251 			if (page != kmapped_page) {
252 				if (kmapped_page)
253 					kunmap(kmapped_page);
254 				kmapped_page = page;
255 				kaddr = kmap(kmapped_page);
256 			}
257 			if (new && offset)
258 				memset(kaddr, 0, offset);
259 			bytes_to_copy = PAGE_SIZE - offset;
260 			if (bytes_to_copy > len) {
261 				bytes_to_copy = len;
262 				if (new)
263 					memset(kaddr+offset+len, 0,
264 						PAGE_SIZE-offset-len);
265 			}
266 			err = copy_from_user(kaddr+offset, str, bytes_to_copy);
267 			if (err) {
268 				ret = -EFAULT;
269 				goto out;
270 			}
271 
272 			pos += bytes_to_copy;
273 			str += bytes_to_copy;
274 			len -= bytes_to_copy;
275 		}
276 	}
277 	ret = 0;
278 out:
279 	if (kmapped_page)
280 		kunmap(kmapped_page);
281 	return ret;
282 }
283 
284 /*
285  * Like copy_strings, but get argv and its values from kernel memory.
286  */
287 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
288 {
289 	int r;
290 	mm_segment_t oldfs = get_fs();
291 	set_fs(KERNEL_DS);
292 	r = copy_strings(argc, (char __user * __user *)argv, bprm);
293 	set_fs(oldfs);
294 	return r;
295 }
296 
297 EXPORT_SYMBOL(copy_strings_kernel);
298 
299 #ifdef CONFIG_MMU
300 /*
301  * This routine is used to map in a page into an address space: needed by
302  * execve() for the initial stack and environment pages.
303  *
304  * vma->vm_mm->mmap_sem is held for writing.
305  */
306 void install_arg_page(struct vm_area_struct *vma,
307 			struct page *page, unsigned long address)
308 {
309 	struct mm_struct *mm = vma->vm_mm;
310 	pte_t * pte;
311 	spinlock_t *ptl;
312 
313 	if (unlikely(anon_vma_prepare(vma)))
314 		goto out;
315 
316 	flush_dcache_page(page);
317 	pte = get_locked_pte(mm, address, &ptl);
318 	if (!pte)
319 		goto out;
320 	if (!pte_none(*pte)) {
321 		pte_unmap_unlock(pte, ptl);
322 		goto out;
323 	}
324 	inc_mm_counter(mm, anon_rss);
325 	lru_cache_add_active(page);
326 	set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
327 					page, vma->vm_page_prot))));
328 	page_add_new_anon_rmap(page, vma, address);
329 	pte_unmap_unlock(pte, ptl);
330 
331 	/* no need for flush_tlb */
332 	return;
333 out:
334 	__free_page(page);
335 	force_sig(SIGKILL, current);
336 }
337 
338 #define EXTRA_STACK_VM_PAGES	20	/* random */
339 
340 int setup_arg_pages(struct linux_binprm *bprm,
341 		    unsigned long stack_top,
342 		    int executable_stack)
343 {
344 	unsigned long stack_base;
345 	struct vm_area_struct *mpnt;
346 	struct mm_struct *mm = current->mm;
347 	int i, ret;
348 	long arg_size;
349 
350 #ifdef CONFIG_STACK_GROWSUP
351 	/* Move the argument and environment strings to the bottom of the
352 	 * stack space.
353 	 */
354 	int offset, j;
355 	char *to, *from;
356 
357 	/* Start by shifting all the pages down */
358 	i = 0;
359 	for (j = 0; j < MAX_ARG_PAGES; j++) {
360 		struct page *page = bprm->page[j];
361 		if (!page)
362 			continue;
363 		bprm->page[i++] = page;
364 	}
365 
366 	/* Now move them within their pages */
367 	offset = bprm->p % PAGE_SIZE;
368 	to = kmap(bprm->page[0]);
369 	for (j = 1; j < i; j++) {
370 		memmove(to, to + offset, PAGE_SIZE - offset);
371 		from = kmap(bprm->page[j]);
372 		memcpy(to + PAGE_SIZE - offset, from, offset);
373 		kunmap(bprm->page[j - 1]);
374 		to = from;
375 	}
376 	memmove(to, to + offset, PAGE_SIZE - offset);
377 	kunmap(bprm->page[j - 1]);
378 
379 	/* Limit stack size to 1GB */
380 	stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
381 	if (stack_base > (1 << 30))
382 		stack_base = 1 << 30;
383 	stack_base = PAGE_ALIGN(stack_top - stack_base);
384 
385 	/* Adjust bprm->p to point to the end of the strings. */
386 	bprm->p = stack_base + PAGE_SIZE * i - offset;
387 
388 	mm->arg_start = stack_base;
389 	arg_size = i << PAGE_SHIFT;
390 
391 	/* zero pages that were copied above */
392 	while (i < MAX_ARG_PAGES)
393 		bprm->page[i++] = NULL;
394 #else
395 	stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
396 	stack_base = PAGE_ALIGN(stack_base);
397 	bprm->p += stack_base;
398 	mm->arg_start = bprm->p;
399 	arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
400 #endif
401 
402 	arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
403 
404 	if (bprm->loader)
405 		bprm->loader += stack_base;
406 	bprm->exec += stack_base;
407 
408 	mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
409 	if (!mpnt)
410 		return -ENOMEM;
411 
412 	down_write(&mm->mmap_sem);
413 	{
414 		mpnt->vm_mm = mm;
415 #ifdef CONFIG_STACK_GROWSUP
416 		mpnt->vm_start = stack_base;
417 		mpnt->vm_end = stack_base + arg_size;
418 #else
419 		mpnt->vm_end = stack_top;
420 		mpnt->vm_start = mpnt->vm_end - arg_size;
421 #endif
422 		/* Adjust stack execute permissions; explicitly enable
423 		 * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
424 		 * and leave alone (arch default) otherwise. */
425 		if (unlikely(executable_stack == EXSTACK_ENABLE_X))
426 			mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
427 		else if (executable_stack == EXSTACK_DISABLE_X)
428 			mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
429 		else
430 			mpnt->vm_flags = VM_STACK_FLAGS;
431 		mpnt->vm_flags |= mm->def_flags;
432 		mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
433 		if ((ret = insert_vm_struct(mm, mpnt))) {
434 			up_write(&mm->mmap_sem);
435 			kmem_cache_free(vm_area_cachep, mpnt);
436 			return ret;
437 		}
438 		mm->stack_vm = mm->total_vm = vma_pages(mpnt);
439 	}
440 
441 	for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
442 		struct page *page = bprm->page[i];
443 		if (page) {
444 			bprm->page[i] = NULL;
445 			install_arg_page(mpnt, page, stack_base);
446 		}
447 		stack_base += PAGE_SIZE;
448 	}
449 	up_write(&mm->mmap_sem);
450 
451 	return 0;
452 }
453 
454 EXPORT_SYMBOL(setup_arg_pages);
455 
456 #define free_arg_pages(bprm) do { } while (0)
457 
458 #else
459 
460 static inline void free_arg_pages(struct linux_binprm *bprm)
461 {
462 	int i;
463 
464 	for (i = 0; i < MAX_ARG_PAGES; i++) {
465 		if (bprm->page[i])
466 			__free_page(bprm->page[i]);
467 		bprm->page[i] = NULL;
468 	}
469 }
470 
471 #endif /* CONFIG_MMU */
472 
473 struct file *open_exec(const char *name)
474 {
475 	struct nameidata nd;
476 	int err;
477 	struct file *file;
478 
479 	err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
480 	file = ERR_PTR(err);
481 
482 	if (!err) {
483 		struct inode *inode = nd.dentry->d_inode;
484 		file = ERR_PTR(-EACCES);
485 		if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
486 		    S_ISREG(inode->i_mode)) {
487 			int err = vfs_permission(&nd, MAY_EXEC);
488 			file = ERR_PTR(err);
489 			if (!err) {
490 				file = nameidata_to_filp(&nd, O_RDONLY);
491 				if (!IS_ERR(file)) {
492 					err = deny_write_access(file);
493 					if (err) {
494 						fput(file);
495 						file = ERR_PTR(err);
496 					}
497 				}
498 out:
499 				return file;
500 			}
501 		}
502 		release_open_intent(&nd);
503 		path_release(&nd);
504 	}
505 	goto out;
506 }
507 
508 EXPORT_SYMBOL(open_exec);
509 
510 int kernel_read(struct file *file, unsigned long offset,
511 	char *addr, unsigned long count)
512 {
513 	mm_segment_t old_fs;
514 	loff_t pos = offset;
515 	int result;
516 
517 	old_fs = get_fs();
518 	set_fs(get_ds());
519 	/* The cast to a user pointer is valid due to the set_fs() */
520 	result = vfs_read(file, (void __user *)addr, count, &pos);
521 	set_fs(old_fs);
522 	return result;
523 }
524 
525 EXPORT_SYMBOL(kernel_read);
526 
527 static int exec_mmap(struct mm_struct *mm)
528 {
529 	struct task_struct *tsk;
530 	struct mm_struct * old_mm, *active_mm;
531 
532 	/* Notify parent that we're no longer interested in the old VM */
533 	tsk = current;
534 	old_mm = current->mm;
535 	mm_release(tsk, old_mm);
536 
537 	if (old_mm) {
538 		/*
539 		 * Make sure that if there is a core dump in progress
540 		 * for the old mm, we get out and die instead of going
541 		 * through with the exec.  We must hold mmap_sem around
542 		 * checking core_waiters and changing tsk->mm.  The
543 		 * core-inducing thread will increment core_waiters for
544 		 * each thread whose ->mm == old_mm.
545 		 */
546 		down_read(&old_mm->mmap_sem);
547 		if (unlikely(old_mm->core_waiters)) {
548 			up_read(&old_mm->mmap_sem);
549 			return -EINTR;
550 		}
551 	}
552 	task_lock(tsk);
553 	active_mm = tsk->active_mm;
554 	tsk->mm = mm;
555 	tsk->active_mm = mm;
556 	activate_mm(active_mm, mm);
557 	task_unlock(tsk);
558 	arch_pick_mmap_layout(mm);
559 	if (old_mm) {
560 		up_read(&old_mm->mmap_sem);
561 		BUG_ON(active_mm != old_mm);
562 		mmput(old_mm);
563 		return 0;
564 	}
565 	mmdrop(active_mm);
566 	return 0;
567 }
568 
569 /*
570  * This function makes sure the current process has its own signal table,
571  * so that flush_signal_handlers can later reset the handlers without
572  * disturbing other processes.  (Other processes might share the signal
573  * table via the CLONE_SIGHAND option to clone().)
574  */
575 static int de_thread(struct task_struct *tsk)
576 {
577 	struct signal_struct *sig = tsk->signal;
578 	struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
579 	spinlock_t *lock = &oldsighand->siglock;
580 	struct task_struct *leader = NULL;
581 	int count;
582 
583 	/*
584 	 * If we don't share sighandlers, then we aren't sharing anything
585 	 * and we can just re-use it all.
586 	 */
587 	if (atomic_read(&oldsighand->count) <= 1) {
588 		BUG_ON(atomic_read(&sig->count) != 1);
589 		exit_itimers(sig);
590 		return 0;
591 	}
592 
593 	newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
594 	if (!newsighand)
595 		return -ENOMEM;
596 
597 	if (thread_group_empty(tsk))
598 		goto no_thread_group;
599 
600 	/*
601 	 * Kill all other threads in the thread group.
602 	 * We must hold tasklist_lock to call zap_other_threads.
603 	 */
604 	read_lock(&tasklist_lock);
605 	spin_lock_irq(lock);
606 	if (sig->flags & SIGNAL_GROUP_EXIT) {
607 		/*
608 		 * Another group action in progress, just
609 		 * return so that the signal is processed.
610 		 */
611 		spin_unlock_irq(lock);
612 		read_unlock(&tasklist_lock);
613 		kmem_cache_free(sighand_cachep, newsighand);
614 		return -EAGAIN;
615 	}
616 
617 	/*
618 	 * child_reaper ignores SIGKILL, change it now.
619 	 * Reparenting needs write_lock on tasklist_lock,
620 	 * so it is safe to do it under read_lock.
621 	 */
622 	if (unlikely(tsk->group_leader == child_reaper(tsk)))
623 		tsk->nsproxy->pid_ns->child_reaper = tsk;
624 
625 	zap_other_threads(tsk);
626 	read_unlock(&tasklist_lock);
627 
628 	/*
629 	 * Account for the thread group leader hanging around:
630 	 */
631 	count = 1;
632 	if (!thread_group_leader(tsk)) {
633 		count = 2;
634 		/*
635 		 * The SIGALRM timer survives the exec, but needs to point
636 		 * at us as the new group leader now.  We have a race with
637 		 * a timer firing now getting the old leader, so we need to
638 		 * synchronize with any firing (by calling del_timer_sync)
639 		 * before we can safely let the old group leader die.
640 		 */
641 		sig->tsk = tsk;
642 		spin_unlock_irq(lock);
643 		if (hrtimer_cancel(&sig->real_timer))
644 			hrtimer_restart(&sig->real_timer);
645 		spin_lock_irq(lock);
646 	}
647 	while (atomic_read(&sig->count) > count) {
648 		sig->group_exit_task = tsk;
649 		sig->notify_count = count;
650 		__set_current_state(TASK_UNINTERRUPTIBLE);
651 		spin_unlock_irq(lock);
652 		schedule();
653 		spin_lock_irq(lock);
654 	}
655 	sig->group_exit_task = NULL;
656 	sig->notify_count = 0;
657 	spin_unlock_irq(lock);
658 
659 	/*
660 	 * At this point all other threads have exited, all we have to
661 	 * do is to wait for the thread group leader to become inactive,
662 	 * and to assume its PID:
663 	 */
664 	if (!thread_group_leader(tsk)) {
665 		/*
666 		 * Wait for the thread group leader to be a zombie.
667 		 * It should already be zombie at this point, most
668 		 * of the time.
669 		 */
670 		leader = tsk->group_leader;
671 		while (leader->exit_state != EXIT_ZOMBIE)
672 			yield();
673 
674 		/*
675 		 * The only record we have of the real-time age of a
676 		 * process, regardless of execs it's done, is start_time.
677 		 * All the past CPU time is accumulated in signal_struct
678 		 * from sister threads now dead.  But in this non-leader
679 		 * exec, nothing survives from the original leader thread,
680 		 * whose birth marks the true age of this process now.
681 		 * When we take on its identity by switching to its PID, we
682 		 * also take its birthdate (always earlier than our own).
683 		 */
684 		tsk->start_time = leader->start_time;
685 
686 		write_lock_irq(&tasklist_lock);
687 
688 		BUG_ON(leader->tgid != tsk->tgid);
689 		BUG_ON(tsk->pid == tsk->tgid);
690 		/*
691 		 * An exec() starts a new thread group with the
692 		 * TGID of the previous thread group. Rehash the
693 		 * two threads with a switched PID, and release
694 		 * the former thread group leader:
695 		 */
696 
697 		/* Become a process group leader with the old leader's pid.
698 		 * The old leader becomes a thread of the this thread group.
699 		 * Note: The old leader also uses this pid until release_task
700 		 *       is called.  Odd but simple and correct.
701 		 */
702 		detach_pid(tsk, PIDTYPE_PID);
703 		tsk->pid = leader->pid;
704 		attach_pid(tsk, PIDTYPE_PID,  tsk->pid);
705 		transfer_pid(leader, tsk, PIDTYPE_PGID);
706 		transfer_pid(leader, tsk, PIDTYPE_SID);
707 		list_replace_rcu(&leader->tasks, &tsk->tasks);
708 
709 		tsk->group_leader = tsk;
710 		leader->group_leader = tsk;
711 
712 		tsk->exit_signal = SIGCHLD;
713 
714 		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
715 		leader->exit_state = EXIT_DEAD;
716 
717 		write_unlock_irq(&tasklist_lock);
718         }
719 
720 	/*
721 	 * There may be one thread left which is just exiting,
722 	 * but it's safe to stop telling the group to kill themselves.
723 	 */
724 	sig->flags = 0;
725 
726 no_thread_group:
727 	exit_itimers(sig);
728 	if (leader)
729 		release_task(leader);
730 
731 	BUG_ON(atomic_read(&sig->count) != 1);
732 
733 	if (atomic_read(&oldsighand->count) == 1) {
734 		/*
735 		 * Now that we nuked the rest of the thread group,
736 		 * it turns out we are not sharing sighand any more either.
737 		 * So we can just keep it.
738 		 */
739 		kmem_cache_free(sighand_cachep, newsighand);
740 	} else {
741 		/*
742 		 * Move our state over to newsighand and switch it in.
743 		 */
744 		atomic_set(&newsighand->count, 1);
745 		memcpy(newsighand->action, oldsighand->action,
746 		       sizeof(newsighand->action));
747 
748 		write_lock_irq(&tasklist_lock);
749 		spin_lock(&oldsighand->siglock);
750 		spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
751 
752 		rcu_assign_pointer(tsk->sighand, newsighand);
753 		recalc_sigpending();
754 
755 		spin_unlock(&newsighand->siglock);
756 		spin_unlock(&oldsighand->siglock);
757 		write_unlock_irq(&tasklist_lock);
758 
759 		if (atomic_dec_and_test(&oldsighand->count))
760 			kmem_cache_free(sighand_cachep, oldsighand);
761 	}
762 
763 	BUG_ON(!thread_group_leader(tsk));
764 	return 0;
765 }
766 
767 /*
768  * These functions flushes out all traces of the currently running executable
769  * so that a new one can be started
770  */
771 
772 static void flush_old_files(struct files_struct * files)
773 {
774 	long j = -1;
775 	struct fdtable *fdt;
776 
777 	spin_lock(&files->file_lock);
778 	for (;;) {
779 		unsigned long set, i;
780 
781 		j++;
782 		i = j * __NFDBITS;
783 		fdt = files_fdtable(files);
784 		if (i >= fdt->max_fds)
785 			break;
786 		set = fdt->close_on_exec->fds_bits[j];
787 		if (!set)
788 			continue;
789 		fdt->close_on_exec->fds_bits[j] = 0;
790 		spin_unlock(&files->file_lock);
791 		for ( ; set ; i++,set >>= 1) {
792 			if (set & 1) {
793 				sys_close(i);
794 			}
795 		}
796 		spin_lock(&files->file_lock);
797 
798 	}
799 	spin_unlock(&files->file_lock);
800 }
801 
802 void get_task_comm(char *buf, struct task_struct *tsk)
803 {
804 	/* buf must be at least sizeof(tsk->comm) in size */
805 	task_lock(tsk);
806 	strncpy(buf, tsk->comm, sizeof(tsk->comm));
807 	task_unlock(tsk);
808 }
809 
810 void set_task_comm(struct task_struct *tsk, char *buf)
811 {
812 	task_lock(tsk);
813 	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
814 	task_unlock(tsk);
815 }
816 
817 int flush_old_exec(struct linux_binprm * bprm)
818 {
819 	char * name;
820 	int i, ch, retval;
821 	struct files_struct *files;
822 	char tcomm[sizeof(current->comm)];
823 
824 	/*
825 	 * Make sure we have a private signal table and that
826 	 * we are unassociated from the previous thread group.
827 	 */
828 	retval = de_thread(current);
829 	if (retval)
830 		goto out;
831 
832 	/*
833 	 * Make sure we have private file handles. Ask the
834 	 * fork helper to do the work for us and the exit
835 	 * helper to do the cleanup of the old one.
836 	 */
837 	files = current->files;		/* refcounted so safe to hold */
838 	retval = unshare_files();
839 	if (retval)
840 		goto out;
841 	/*
842 	 * Release all of the old mmap stuff
843 	 */
844 	retval = exec_mmap(bprm->mm);
845 	if (retval)
846 		goto mmap_failed;
847 
848 	bprm->mm = NULL;		/* We're using it now */
849 
850 	/* This is the point of no return */
851 	put_files_struct(files);
852 
853 	current->sas_ss_sp = current->sas_ss_size = 0;
854 
855 	if (current->euid == current->uid && current->egid == current->gid)
856 		current->mm->dumpable = 1;
857 	else
858 		current->mm->dumpable = suid_dumpable;
859 
860 	name = bprm->filename;
861 
862 	/* Copies the binary name from after last slash */
863 	for (i=0; (ch = *(name++)) != '\0';) {
864 		if (ch == '/')
865 			i = 0; /* overwrite what we wrote */
866 		else
867 			if (i < (sizeof(tcomm) - 1))
868 				tcomm[i++] = ch;
869 	}
870 	tcomm[i] = '\0';
871 	set_task_comm(current, tcomm);
872 
873 	current->flags &= ~PF_RANDOMIZE;
874 	flush_thread();
875 
876 	/* Set the new mm task size. We have to do that late because it may
877 	 * depend on TIF_32BIT which is only updated in flush_thread() on
878 	 * some architectures like powerpc
879 	 */
880 	current->mm->task_size = TASK_SIZE;
881 
882 	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
883 	    file_permission(bprm->file, MAY_READ) ||
884 	    (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
885 		suid_keys(current);
886 		current->mm->dumpable = suid_dumpable;
887 	}
888 
889 	/* An exec changes our domain. We are no longer part of the thread
890 	   group */
891 
892 	current->self_exec_id++;
893 
894 	flush_signal_handlers(current, 0);
895 	flush_old_files(current->files);
896 
897 	return 0;
898 
899 mmap_failed:
900 	reset_files_struct(current, files);
901 out:
902 	return retval;
903 }
904 
905 EXPORT_SYMBOL(flush_old_exec);
906 
907 /*
908  * Fill the binprm structure from the inode.
909  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
910  */
911 int prepare_binprm(struct linux_binprm *bprm)
912 {
913 	int mode;
914 	struct inode * inode = bprm->file->f_path.dentry->d_inode;
915 	int retval;
916 
917 	mode = inode->i_mode;
918 	if (bprm->file->f_op == NULL)
919 		return -EACCES;
920 
921 	bprm->e_uid = current->euid;
922 	bprm->e_gid = current->egid;
923 
924 	if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
925 		/* Set-uid? */
926 		if (mode & S_ISUID) {
927 			current->personality &= ~PER_CLEAR_ON_SETID;
928 			bprm->e_uid = inode->i_uid;
929 		}
930 
931 		/* Set-gid? */
932 		/*
933 		 * If setgid is set but no group execute bit then this
934 		 * is a candidate for mandatory locking, not a setgid
935 		 * executable.
936 		 */
937 		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
938 			current->personality &= ~PER_CLEAR_ON_SETID;
939 			bprm->e_gid = inode->i_gid;
940 		}
941 	}
942 
943 	/* fill in binprm security blob */
944 	retval = security_bprm_set(bprm);
945 	if (retval)
946 		return retval;
947 
948 	memset(bprm->buf,0,BINPRM_BUF_SIZE);
949 	return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
950 }
951 
952 EXPORT_SYMBOL(prepare_binprm);
953 
954 static int unsafe_exec(struct task_struct *p)
955 {
956 	int unsafe = 0;
957 	if (p->ptrace & PT_PTRACED) {
958 		if (p->ptrace & PT_PTRACE_CAP)
959 			unsafe |= LSM_UNSAFE_PTRACE_CAP;
960 		else
961 			unsafe |= LSM_UNSAFE_PTRACE;
962 	}
963 	if (atomic_read(&p->fs->count) > 1 ||
964 	    atomic_read(&p->files->count) > 1 ||
965 	    atomic_read(&p->sighand->count) > 1)
966 		unsafe |= LSM_UNSAFE_SHARE;
967 
968 	return unsafe;
969 }
970 
971 void compute_creds(struct linux_binprm *bprm)
972 {
973 	int unsafe;
974 
975 	if (bprm->e_uid != current->uid)
976 		suid_keys(current);
977 	exec_keys(current);
978 
979 	task_lock(current);
980 	unsafe = unsafe_exec(current);
981 	security_bprm_apply_creds(bprm, unsafe);
982 	task_unlock(current);
983 	security_bprm_post_apply_creds(bprm);
984 }
985 
986 EXPORT_SYMBOL(compute_creds);
987 
988 void remove_arg_zero(struct linux_binprm *bprm)
989 {
990 	if (bprm->argc) {
991 		unsigned long offset;
992 		char * kaddr;
993 		struct page *page;
994 
995 		offset = bprm->p % PAGE_SIZE;
996 		goto inside;
997 
998 		while (bprm->p++, *(kaddr+offset++)) {
999 			if (offset != PAGE_SIZE)
1000 				continue;
1001 			offset = 0;
1002 			kunmap_atomic(kaddr, KM_USER0);
1003 inside:
1004 			page = bprm->page[bprm->p/PAGE_SIZE];
1005 			kaddr = kmap_atomic(page, KM_USER0);
1006 		}
1007 		kunmap_atomic(kaddr, KM_USER0);
1008 		bprm->argc--;
1009 	}
1010 }
1011 
1012 EXPORT_SYMBOL(remove_arg_zero);
1013 
1014 /*
1015  * cycle the list of binary formats handler, until one recognizes the image
1016  */
1017 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1018 {
1019 	int try,retval;
1020 	struct linux_binfmt *fmt;
1021 #ifdef __alpha__
1022 	/* handle /sbin/loader.. */
1023 	{
1024 	    struct exec * eh = (struct exec *) bprm->buf;
1025 
1026 	    if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1027 		(eh->fh.f_flags & 0x3000) == 0x3000)
1028 	    {
1029 		struct file * file;
1030 		unsigned long loader;
1031 
1032 		allow_write_access(bprm->file);
1033 		fput(bprm->file);
1034 		bprm->file = NULL;
1035 
1036 	        loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1037 
1038 		file = open_exec("/sbin/loader");
1039 		retval = PTR_ERR(file);
1040 		if (IS_ERR(file))
1041 			return retval;
1042 
1043 		/* Remember if the application is TASO.  */
1044 		bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1045 
1046 		bprm->file = file;
1047 		bprm->loader = loader;
1048 		retval = prepare_binprm(bprm);
1049 		if (retval<0)
1050 			return retval;
1051 		/* should call search_binary_handler recursively here,
1052 		   but it does not matter */
1053 	    }
1054 	}
1055 #endif
1056 	retval = security_bprm_check(bprm);
1057 	if (retval)
1058 		return retval;
1059 
1060 	/* kernel module loader fixup */
1061 	/* so we don't try to load run modprobe in kernel space. */
1062 	set_fs(USER_DS);
1063 
1064 	retval = audit_bprm(bprm);
1065 	if (retval)
1066 		return retval;
1067 
1068 	retval = -ENOENT;
1069 	for (try=0; try<2; try++) {
1070 		read_lock(&binfmt_lock);
1071 		for (fmt = formats ; fmt ; fmt = fmt->next) {
1072 			int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1073 			if (!fn)
1074 				continue;
1075 			if (!try_module_get(fmt->module))
1076 				continue;
1077 			read_unlock(&binfmt_lock);
1078 			retval = fn(bprm, regs);
1079 			if (retval >= 0) {
1080 				put_binfmt(fmt);
1081 				allow_write_access(bprm->file);
1082 				if (bprm->file)
1083 					fput(bprm->file);
1084 				bprm->file = NULL;
1085 				current->did_exec = 1;
1086 				proc_exec_connector(current);
1087 				return retval;
1088 			}
1089 			read_lock(&binfmt_lock);
1090 			put_binfmt(fmt);
1091 			if (retval != -ENOEXEC || bprm->mm == NULL)
1092 				break;
1093 			if (!bprm->file) {
1094 				read_unlock(&binfmt_lock);
1095 				return retval;
1096 			}
1097 		}
1098 		read_unlock(&binfmt_lock);
1099 		if (retval != -ENOEXEC || bprm->mm == NULL) {
1100 			break;
1101 #ifdef CONFIG_KMOD
1102 		}else{
1103 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1104 			if (printable(bprm->buf[0]) &&
1105 			    printable(bprm->buf[1]) &&
1106 			    printable(bprm->buf[2]) &&
1107 			    printable(bprm->buf[3]))
1108 				break; /* -ENOEXEC */
1109 			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1110 #endif
1111 		}
1112 	}
1113 	return retval;
1114 }
1115 
1116 EXPORT_SYMBOL(search_binary_handler);
1117 
1118 /*
1119  * sys_execve() executes a new program.
1120  */
1121 int do_execve(char * filename,
1122 	char __user *__user *argv,
1123 	char __user *__user *envp,
1124 	struct pt_regs * regs)
1125 {
1126 	struct linux_binprm *bprm;
1127 	struct file *file;
1128 	int retval;
1129 	int i;
1130 
1131 	retval = -ENOMEM;
1132 	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1133 	if (!bprm)
1134 		goto out_ret;
1135 
1136 	file = open_exec(filename);
1137 	retval = PTR_ERR(file);
1138 	if (IS_ERR(file))
1139 		goto out_kfree;
1140 
1141 	sched_exec();
1142 
1143 	bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1144 
1145 	bprm->file = file;
1146 	bprm->filename = filename;
1147 	bprm->interp = filename;
1148 	bprm->mm = mm_alloc();
1149 	retval = -ENOMEM;
1150 	if (!bprm->mm)
1151 		goto out_file;
1152 
1153 	retval = init_new_context(current, bprm->mm);
1154 	if (retval < 0)
1155 		goto out_mm;
1156 
1157 	bprm->argc = count(argv, bprm->p / sizeof(void *));
1158 	if ((retval = bprm->argc) < 0)
1159 		goto out_mm;
1160 
1161 	bprm->envc = count(envp, bprm->p / sizeof(void *));
1162 	if ((retval = bprm->envc) < 0)
1163 		goto out_mm;
1164 
1165 	retval = security_bprm_alloc(bprm);
1166 	if (retval)
1167 		goto out;
1168 
1169 	retval = prepare_binprm(bprm);
1170 	if (retval < 0)
1171 		goto out;
1172 
1173 	retval = copy_strings_kernel(1, &bprm->filename, bprm);
1174 	if (retval < 0)
1175 		goto out;
1176 
1177 	bprm->exec = bprm->p;
1178 	retval = copy_strings(bprm->envc, envp, bprm);
1179 	if (retval < 0)
1180 		goto out;
1181 
1182 	retval = copy_strings(bprm->argc, argv, bprm);
1183 	if (retval < 0)
1184 		goto out;
1185 
1186 	retval = search_binary_handler(bprm,regs);
1187 	if (retval >= 0) {
1188 		free_arg_pages(bprm);
1189 
1190 		/* execve success */
1191 		security_bprm_free(bprm);
1192 		acct_update_integrals(current);
1193 		kfree(bprm);
1194 		return retval;
1195 	}
1196 
1197 out:
1198 	/* Something went wrong, return the inode and free the argument pages*/
1199 	for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1200 		struct page * page = bprm->page[i];
1201 		if (page)
1202 			__free_page(page);
1203 	}
1204 
1205 	if (bprm->security)
1206 		security_bprm_free(bprm);
1207 
1208 out_mm:
1209 	if (bprm->mm)
1210 		mmdrop(bprm->mm);
1211 
1212 out_file:
1213 	if (bprm->file) {
1214 		allow_write_access(bprm->file);
1215 		fput(bprm->file);
1216 	}
1217 
1218 out_kfree:
1219 	kfree(bprm);
1220 
1221 out_ret:
1222 	return retval;
1223 }
1224 
1225 int set_binfmt(struct linux_binfmt *new)
1226 {
1227 	struct linux_binfmt *old = current->binfmt;
1228 
1229 	if (new) {
1230 		if (!try_module_get(new->module))
1231 			return -1;
1232 	}
1233 	current->binfmt = new;
1234 	if (old)
1235 		module_put(old->module);
1236 	return 0;
1237 }
1238 
1239 EXPORT_SYMBOL(set_binfmt);
1240 
1241 #define CORENAME_MAX_SIZE 64
1242 
1243 /* format_corename will inspect the pattern parameter, and output a
1244  * name into corename, which must have space for at least
1245  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1246  */
1247 static void format_corename(char *corename, const char *pattern, long signr)
1248 {
1249 	const char *pat_ptr = pattern;
1250 	char *out_ptr = corename;
1251 	char *const out_end = corename + CORENAME_MAX_SIZE;
1252 	int rc;
1253 	int pid_in_pattern = 0;
1254 
1255 	/* Repeat as long as we have more pattern to process and more output
1256 	   space */
1257 	while (*pat_ptr) {
1258 		if (*pat_ptr != '%') {
1259 			if (out_ptr == out_end)
1260 				goto out;
1261 			*out_ptr++ = *pat_ptr++;
1262 		} else {
1263 			switch (*++pat_ptr) {
1264 			case 0:
1265 				goto out;
1266 			/* Double percent, output one percent */
1267 			case '%':
1268 				if (out_ptr == out_end)
1269 					goto out;
1270 				*out_ptr++ = '%';
1271 				break;
1272 			/* pid */
1273 			case 'p':
1274 				pid_in_pattern = 1;
1275 				rc = snprintf(out_ptr, out_end - out_ptr,
1276 					      "%d", current->tgid);
1277 				if (rc > out_end - out_ptr)
1278 					goto out;
1279 				out_ptr += rc;
1280 				break;
1281 			/* uid */
1282 			case 'u':
1283 				rc = snprintf(out_ptr, out_end - out_ptr,
1284 					      "%d", current->uid);
1285 				if (rc > out_end - out_ptr)
1286 					goto out;
1287 				out_ptr += rc;
1288 				break;
1289 			/* gid */
1290 			case 'g':
1291 				rc = snprintf(out_ptr, out_end - out_ptr,
1292 					      "%d", current->gid);
1293 				if (rc > out_end - out_ptr)
1294 					goto out;
1295 				out_ptr += rc;
1296 				break;
1297 			/* signal that caused the coredump */
1298 			case 's':
1299 				rc = snprintf(out_ptr, out_end - out_ptr,
1300 					      "%ld", signr);
1301 				if (rc > out_end - out_ptr)
1302 					goto out;
1303 				out_ptr += rc;
1304 				break;
1305 			/* UNIX time of coredump */
1306 			case 't': {
1307 				struct timeval tv;
1308 				do_gettimeofday(&tv);
1309 				rc = snprintf(out_ptr, out_end - out_ptr,
1310 					      "%lu", tv.tv_sec);
1311 				if (rc > out_end - out_ptr)
1312 					goto out;
1313 				out_ptr += rc;
1314 				break;
1315 			}
1316 			/* hostname */
1317 			case 'h':
1318 				down_read(&uts_sem);
1319 				rc = snprintf(out_ptr, out_end - out_ptr,
1320 					      "%s", utsname()->nodename);
1321 				up_read(&uts_sem);
1322 				if (rc > out_end - out_ptr)
1323 					goto out;
1324 				out_ptr += rc;
1325 				break;
1326 			/* executable */
1327 			case 'e':
1328 				rc = snprintf(out_ptr, out_end - out_ptr,
1329 					      "%s", current->comm);
1330 				if (rc > out_end - out_ptr)
1331 					goto out;
1332 				out_ptr += rc;
1333 				break;
1334 			default:
1335 				break;
1336 			}
1337 			++pat_ptr;
1338 		}
1339 	}
1340 	/* Backward compatibility with core_uses_pid:
1341 	 *
1342 	 * If core_pattern does not include a %p (as is the default)
1343 	 * and core_uses_pid is set, then .%pid will be appended to
1344 	 * the filename */
1345 	if (!pid_in_pattern
1346             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1347 		rc = snprintf(out_ptr, out_end - out_ptr,
1348 			      ".%d", current->tgid);
1349 		if (rc > out_end - out_ptr)
1350 			goto out;
1351 		out_ptr += rc;
1352 	}
1353       out:
1354 	*out_ptr = 0;
1355 }
1356 
1357 static void zap_process(struct task_struct *start)
1358 {
1359 	struct task_struct *t;
1360 
1361 	start->signal->flags = SIGNAL_GROUP_EXIT;
1362 	start->signal->group_stop_count = 0;
1363 
1364 	t = start;
1365 	do {
1366 		if (t != current && t->mm) {
1367 			t->mm->core_waiters++;
1368 			sigaddset(&t->pending.signal, SIGKILL);
1369 			signal_wake_up(t, 1);
1370 		}
1371 	} while ((t = next_thread(t)) != start);
1372 }
1373 
1374 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1375 				int exit_code)
1376 {
1377 	struct task_struct *g, *p;
1378 	unsigned long flags;
1379 	int err = -EAGAIN;
1380 
1381 	spin_lock_irq(&tsk->sighand->siglock);
1382 	if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1383 		tsk->signal->group_exit_code = exit_code;
1384 		zap_process(tsk);
1385 		err = 0;
1386 	}
1387 	spin_unlock_irq(&tsk->sighand->siglock);
1388 	if (err)
1389 		return err;
1390 
1391 	if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1392 		goto done;
1393 
1394 	rcu_read_lock();
1395 	for_each_process(g) {
1396 		if (g == tsk->group_leader)
1397 			continue;
1398 
1399 		p = g;
1400 		do {
1401 			if (p->mm) {
1402 				if (p->mm == mm) {
1403 					/*
1404 					 * p->sighand can't disappear, but
1405 					 * may be changed by de_thread()
1406 					 */
1407 					lock_task_sighand(p, &flags);
1408 					zap_process(p);
1409 					unlock_task_sighand(p, &flags);
1410 				}
1411 				break;
1412 			}
1413 		} while ((p = next_thread(p)) != g);
1414 	}
1415 	rcu_read_unlock();
1416 done:
1417 	return mm->core_waiters;
1418 }
1419 
1420 static int coredump_wait(int exit_code)
1421 {
1422 	struct task_struct *tsk = current;
1423 	struct mm_struct *mm = tsk->mm;
1424 	struct completion startup_done;
1425 	struct completion *vfork_done;
1426 	int core_waiters;
1427 
1428 	init_completion(&mm->core_done);
1429 	init_completion(&startup_done);
1430 	mm->core_startup_done = &startup_done;
1431 
1432 	core_waiters = zap_threads(tsk, mm, exit_code);
1433 	up_write(&mm->mmap_sem);
1434 
1435 	if (unlikely(core_waiters < 0))
1436 		goto fail;
1437 
1438 	/*
1439 	 * Make sure nobody is waiting for us to release the VM,
1440 	 * otherwise we can deadlock when we wait on each other
1441 	 */
1442 	vfork_done = tsk->vfork_done;
1443 	if (vfork_done) {
1444 		tsk->vfork_done = NULL;
1445 		complete(vfork_done);
1446 	}
1447 
1448 	if (core_waiters)
1449 		wait_for_completion(&startup_done);
1450 fail:
1451 	BUG_ON(mm->core_waiters);
1452 	return core_waiters;
1453 }
1454 
1455 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1456 {
1457 	char corename[CORENAME_MAX_SIZE + 1];
1458 	struct mm_struct *mm = current->mm;
1459 	struct linux_binfmt * binfmt;
1460 	struct inode * inode;
1461 	struct file * file;
1462 	int retval = 0;
1463 	int fsuid = current->fsuid;
1464 	int flag = 0;
1465 	int ispipe = 0;
1466 
1467 	binfmt = current->binfmt;
1468 	if (!binfmt || !binfmt->core_dump)
1469 		goto fail;
1470 	down_write(&mm->mmap_sem);
1471 	if (!mm->dumpable) {
1472 		up_write(&mm->mmap_sem);
1473 		goto fail;
1474 	}
1475 
1476 	/*
1477 	 *	We cannot trust fsuid as being the "true" uid of the
1478 	 *	process nor do we know its entire history. We only know it
1479 	 *	was tainted so we dump it as root in mode 2.
1480 	 */
1481 	if (mm->dumpable == 2) {	/* Setuid core dump mode */
1482 		flag = O_EXCL;		/* Stop rewrite attacks */
1483 		current->fsuid = 0;	/* Dump root private */
1484 	}
1485 	mm->dumpable = 0;
1486 
1487 	retval = coredump_wait(exit_code);
1488 	if (retval < 0)
1489 		goto fail;
1490 
1491 	/*
1492 	 * Clear any false indication of pending signals that might
1493 	 * be seen by the filesystem code called to write the core file.
1494 	 */
1495 	clear_thread_flag(TIF_SIGPENDING);
1496 
1497 	if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1498 		goto fail_unlock;
1499 
1500 	/*
1501 	 * lock_kernel() because format_corename() is controlled by sysctl, which
1502 	 * uses lock_kernel()
1503 	 */
1504  	lock_kernel();
1505 	format_corename(corename, core_pattern, signr);
1506 	unlock_kernel();
1507  	if (corename[0] == '|') {
1508 		/* SIGPIPE can happen, but it's just never processed */
1509  		if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1510  			printk(KERN_INFO "Core dump to %s pipe failed\n",
1511 			       corename);
1512  			goto fail_unlock;
1513  		}
1514 		ispipe = 1;
1515  	} else
1516  		file = filp_open(corename,
1517 				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1518 				 0600);
1519 	if (IS_ERR(file))
1520 		goto fail_unlock;
1521 	inode = file->f_path.dentry->d_inode;
1522 	if (inode->i_nlink > 1)
1523 		goto close_fail;	/* multiple links - don't dump */
1524 	if (!ispipe && d_unhashed(file->f_path.dentry))
1525 		goto close_fail;
1526 
1527 	/* AK: actually i see no reason to not allow this for named pipes etc.,
1528 	   but keep the previous behaviour for now. */
1529 	if (!ispipe && !S_ISREG(inode->i_mode))
1530 		goto close_fail;
1531 	if (!file->f_op)
1532 		goto close_fail;
1533 	if (!file->f_op->write)
1534 		goto close_fail;
1535 	if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1536 		goto close_fail;
1537 
1538 	retval = binfmt->core_dump(signr, regs, file);
1539 
1540 	if (retval)
1541 		current->signal->group_exit_code |= 0x80;
1542 close_fail:
1543 	filp_close(file, NULL);
1544 fail_unlock:
1545 	current->fsuid = fsuid;
1546 	complete_all(&mm->core_done);
1547 fail:
1548 	return retval;
1549 }
1550