xref: /openbmc/linux/fs/exec.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 #include <linux/signalfd.h>
54 
55 #include <asm/uaccess.h>
56 #include <asm/mmu_context.h>
57 
58 #ifdef CONFIG_KMOD
59 #include <linux/kmod.h>
60 #endif
61 
62 int core_uses_pid;
63 char core_pattern[128] = "core";
64 int suid_dumpable = 0;
65 
66 EXPORT_SYMBOL(suid_dumpable);
67 /* The maximal length of core_pattern is also specified in sysctl.c */
68 
69 static struct linux_binfmt *formats;
70 static DEFINE_RWLOCK(binfmt_lock);
71 
72 int register_binfmt(struct linux_binfmt * fmt)
73 {
74 	struct linux_binfmt ** tmp = &formats;
75 
76 	if (!fmt)
77 		return -EINVAL;
78 	if (fmt->next)
79 		return -EBUSY;
80 	write_lock(&binfmt_lock);
81 	while (*tmp) {
82 		if (fmt == *tmp) {
83 			write_unlock(&binfmt_lock);
84 			return -EBUSY;
85 		}
86 		tmp = &(*tmp)->next;
87 	}
88 	fmt->next = formats;
89 	formats = fmt;
90 	write_unlock(&binfmt_lock);
91 	return 0;
92 }
93 
94 EXPORT_SYMBOL(register_binfmt);
95 
96 int unregister_binfmt(struct linux_binfmt * fmt)
97 {
98 	struct linux_binfmt ** tmp = &formats;
99 
100 	write_lock(&binfmt_lock);
101 	while (*tmp) {
102 		if (fmt == *tmp) {
103 			*tmp = fmt->next;
104 			fmt->next = NULL;
105 			write_unlock(&binfmt_lock);
106 			return 0;
107 		}
108 		tmp = &(*tmp)->next;
109 	}
110 	write_unlock(&binfmt_lock);
111 	return -EINVAL;
112 }
113 
114 EXPORT_SYMBOL(unregister_binfmt);
115 
116 static inline void put_binfmt(struct linux_binfmt * fmt)
117 {
118 	module_put(fmt->module);
119 }
120 
121 /*
122  * Note that a shared library must be both readable and executable due to
123  * security reasons.
124  *
125  * Also note that we take the address to load from from the file itself.
126  */
127 asmlinkage long sys_uselib(const char __user * library)
128 {
129 	struct file * file;
130 	struct nameidata nd;
131 	int error;
132 
133 	error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
134 	if (error)
135 		goto out;
136 
137 	error = -EINVAL;
138 	if (!S_ISREG(nd.dentry->d_inode->i_mode))
139 		goto exit;
140 
141 	error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
142 	if (error)
143 		goto exit;
144 
145 	file = nameidata_to_filp(&nd, O_RDONLY);
146 	error = PTR_ERR(file);
147 	if (IS_ERR(file))
148 		goto out;
149 
150 	error = -ENOEXEC;
151 	if(file->f_op) {
152 		struct linux_binfmt * fmt;
153 
154 		read_lock(&binfmt_lock);
155 		for (fmt = formats ; fmt ; fmt = fmt->next) {
156 			if (!fmt->load_shlib)
157 				continue;
158 			if (!try_module_get(fmt->module))
159 				continue;
160 			read_unlock(&binfmt_lock);
161 			error = fmt->load_shlib(file);
162 			read_lock(&binfmt_lock);
163 			put_binfmt(fmt);
164 			if (error != -ENOEXEC)
165 				break;
166 		}
167 		read_unlock(&binfmt_lock);
168 	}
169 	fput(file);
170 out:
171   	return error;
172 exit:
173 	release_open_intent(&nd);
174 	path_release(&nd);
175 	goto out;
176 }
177 
178 /*
179  * count() counts the number of strings in array ARGV.
180  */
181 static int count(char __user * __user * argv, int max)
182 {
183 	int i = 0;
184 
185 	if (argv != NULL) {
186 		for (;;) {
187 			char __user * p;
188 
189 			if (get_user(p, argv))
190 				return -EFAULT;
191 			if (!p)
192 				break;
193 			argv++;
194 			if(++i > max)
195 				return -E2BIG;
196 			cond_resched();
197 		}
198 	}
199 	return i;
200 }
201 
202 /*
203  * 'copy_strings()' copies argument/environment strings from user
204  * memory to free pages in kernel mem. These are in a format ready
205  * to be put directly into the top of new user memory.
206  */
207 static int copy_strings(int argc, char __user * __user * argv,
208 			struct linux_binprm *bprm)
209 {
210 	struct page *kmapped_page = NULL;
211 	char *kaddr = NULL;
212 	int ret;
213 
214 	while (argc-- > 0) {
215 		char __user *str;
216 		int len;
217 		unsigned long pos;
218 
219 		if (get_user(str, argv+argc) ||
220 				!(len = strnlen_user(str, bprm->p))) {
221 			ret = -EFAULT;
222 			goto out;
223 		}
224 
225 		if (bprm->p < len)  {
226 			ret = -E2BIG;
227 			goto out;
228 		}
229 
230 		bprm->p -= len;
231 		/* XXX: add architecture specific overflow check here. */
232 		pos = bprm->p;
233 
234 		while (len > 0) {
235 			int i, new, err;
236 			int offset, bytes_to_copy;
237 			struct page *page;
238 
239 			offset = pos % PAGE_SIZE;
240 			i = pos/PAGE_SIZE;
241 			page = bprm->page[i];
242 			new = 0;
243 			if (!page) {
244 				page = alloc_page(GFP_HIGHUSER);
245 				bprm->page[i] = page;
246 				if (!page) {
247 					ret = -ENOMEM;
248 					goto out;
249 				}
250 				new = 1;
251 			}
252 
253 			if (page != kmapped_page) {
254 				if (kmapped_page)
255 					kunmap(kmapped_page);
256 				kmapped_page = page;
257 				kaddr = kmap(kmapped_page);
258 			}
259 			if (new && offset)
260 				memset(kaddr, 0, offset);
261 			bytes_to_copy = PAGE_SIZE - offset;
262 			if (bytes_to_copy > len) {
263 				bytes_to_copy = len;
264 				if (new)
265 					memset(kaddr+offset+len, 0,
266 						PAGE_SIZE-offset-len);
267 			}
268 			err = copy_from_user(kaddr+offset, str, bytes_to_copy);
269 			if (err) {
270 				ret = -EFAULT;
271 				goto out;
272 			}
273 
274 			pos += bytes_to_copy;
275 			str += bytes_to_copy;
276 			len -= bytes_to_copy;
277 		}
278 	}
279 	ret = 0;
280 out:
281 	if (kmapped_page)
282 		kunmap(kmapped_page);
283 	return ret;
284 }
285 
286 /*
287  * Like copy_strings, but get argv and its values from kernel memory.
288  */
289 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
290 {
291 	int r;
292 	mm_segment_t oldfs = get_fs();
293 	set_fs(KERNEL_DS);
294 	r = copy_strings(argc, (char __user * __user *)argv, bprm);
295 	set_fs(oldfs);
296 	return r;
297 }
298 
299 EXPORT_SYMBOL(copy_strings_kernel);
300 
301 #ifdef CONFIG_MMU
302 /*
303  * This routine is used to map in a page into an address space: needed by
304  * execve() for the initial stack and environment pages.
305  *
306  * vma->vm_mm->mmap_sem is held for writing.
307  */
308 void install_arg_page(struct vm_area_struct *vma,
309 			struct page *page, unsigned long address)
310 {
311 	struct mm_struct *mm = vma->vm_mm;
312 	pte_t * pte;
313 	spinlock_t *ptl;
314 
315 	if (unlikely(anon_vma_prepare(vma)))
316 		goto out;
317 
318 	flush_dcache_page(page);
319 	pte = get_locked_pte(mm, address, &ptl);
320 	if (!pte)
321 		goto out;
322 	if (!pte_none(*pte)) {
323 		pte_unmap_unlock(pte, ptl);
324 		goto out;
325 	}
326 	inc_mm_counter(mm, anon_rss);
327 	lru_cache_add_active(page);
328 	set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
329 					page, vma->vm_page_prot))));
330 	page_add_new_anon_rmap(page, vma, address);
331 	pte_unmap_unlock(pte, ptl);
332 
333 	/* no need for flush_tlb */
334 	return;
335 out:
336 	__free_page(page);
337 	force_sig(SIGKILL, current);
338 }
339 
340 #define EXTRA_STACK_VM_PAGES	20	/* random */
341 
342 int setup_arg_pages(struct linux_binprm *bprm,
343 		    unsigned long stack_top,
344 		    int executable_stack)
345 {
346 	unsigned long stack_base;
347 	struct vm_area_struct *mpnt;
348 	struct mm_struct *mm = current->mm;
349 	int i, ret;
350 	long arg_size;
351 
352 #ifdef CONFIG_STACK_GROWSUP
353 	/* Move the argument and environment strings to the bottom of the
354 	 * stack space.
355 	 */
356 	int offset, j;
357 	char *to, *from;
358 
359 	/* Start by shifting all the pages down */
360 	i = 0;
361 	for (j = 0; j < MAX_ARG_PAGES; j++) {
362 		struct page *page = bprm->page[j];
363 		if (!page)
364 			continue;
365 		bprm->page[i++] = page;
366 	}
367 
368 	/* Now move them within their pages */
369 	offset = bprm->p % PAGE_SIZE;
370 	to = kmap(bprm->page[0]);
371 	for (j = 1; j < i; j++) {
372 		memmove(to, to + offset, PAGE_SIZE - offset);
373 		from = kmap(bprm->page[j]);
374 		memcpy(to + PAGE_SIZE - offset, from, offset);
375 		kunmap(bprm->page[j - 1]);
376 		to = from;
377 	}
378 	memmove(to, to + offset, PAGE_SIZE - offset);
379 	kunmap(bprm->page[j - 1]);
380 
381 	/* Limit stack size to 1GB */
382 	stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
383 	if (stack_base > (1 << 30))
384 		stack_base = 1 << 30;
385 	stack_base = PAGE_ALIGN(stack_top - stack_base);
386 
387 	/* Adjust bprm->p to point to the end of the strings. */
388 	bprm->p = stack_base + PAGE_SIZE * i - offset;
389 
390 	mm->arg_start = stack_base;
391 	arg_size = i << PAGE_SHIFT;
392 
393 	/* zero pages that were copied above */
394 	while (i < MAX_ARG_PAGES)
395 		bprm->page[i++] = NULL;
396 #else
397 	stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
398 	stack_base = PAGE_ALIGN(stack_base);
399 	bprm->p += stack_base;
400 	mm->arg_start = bprm->p;
401 	arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
402 #endif
403 
404 	arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
405 
406 	if (bprm->loader)
407 		bprm->loader += stack_base;
408 	bprm->exec += stack_base;
409 
410 	mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
411 	if (!mpnt)
412 		return -ENOMEM;
413 
414 	down_write(&mm->mmap_sem);
415 	{
416 		mpnt->vm_mm = mm;
417 #ifdef CONFIG_STACK_GROWSUP
418 		mpnt->vm_start = stack_base;
419 		mpnt->vm_end = stack_base + arg_size;
420 #else
421 		mpnt->vm_end = stack_top;
422 		mpnt->vm_start = mpnt->vm_end - arg_size;
423 #endif
424 		/* Adjust stack execute permissions; explicitly enable
425 		 * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
426 		 * and leave alone (arch default) otherwise. */
427 		if (unlikely(executable_stack == EXSTACK_ENABLE_X))
428 			mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
429 		else if (executable_stack == EXSTACK_DISABLE_X)
430 			mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
431 		else
432 			mpnt->vm_flags = VM_STACK_FLAGS;
433 		mpnt->vm_flags |= mm->def_flags;
434 		mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
435 		if ((ret = insert_vm_struct(mm, mpnt))) {
436 			up_write(&mm->mmap_sem);
437 			kmem_cache_free(vm_area_cachep, mpnt);
438 			return ret;
439 		}
440 		mm->stack_vm = mm->total_vm = vma_pages(mpnt);
441 	}
442 
443 	for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
444 		struct page *page = bprm->page[i];
445 		if (page) {
446 			bprm->page[i] = NULL;
447 			install_arg_page(mpnt, page, stack_base);
448 		}
449 		stack_base += PAGE_SIZE;
450 	}
451 	up_write(&mm->mmap_sem);
452 
453 	return 0;
454 }
455 
456 EXPORT_SYMBOL(setup_arg_pages);
457 
458 #define free_arg_pages(bprm) do { } while (0)
459 
460 #else
461 
462 static inline void free_arg_pages(struct linux_binprm *bprm)
463 {
464 	int i;
465 
466 	for (i = 0; i < MAX_ARG_PAGES; i++) {
467 		if (bprm->page[i])
468 			__free_page(bprm->page[i]);
469 		bprm->page[i] = NULL;
470 	}
471 }
472 
473 #endif /* CONFIG_MMU */
474 
475 struct file *open_exec(const char *name)
476 {
477 	struct nameidata nd;
478 	int err;
479 	struct file *file;
480 
481 	err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
482 	file = ERR_PTR(err);
483 
484 	if (!err) {
485 		struct inode *inode = nd.dentry->d_inode;
486 		file = ERR_PTR(-EACCES);
487 		if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
488 		    S_ISREG(inode->i_mode)) {
489 			int err = vfs_permission(&nd, MAY_EXEC);
490 			file = ERR_PTR(err);
491 			if (!err) {
492 				file = nameidata_to_filp(&nd, O_RDONLY);
493 				if (!IS_ERR(file)) {
494 					err = deny_write_access(file);
495 					if (err) {
496 						fput(file);
497 						file = ERR_PTR(err);
498 					}
499 				}
500 out:
501 				return file;
502 			}
503 		}
504 		release_open_intent(&nd);
505 		path_release(&nd);
506 	}
507 	goto out;
508 }
509 
510 EXPORT_SYMBOL(open_exec);
511 
512 int kernel_read(struct file *file, unsigned long offset,
513 	char *addr, unsigned long count)
514 {
515 	mm_segment_t old_fs;
516 	loff_t pos = offset;
517 	int result;
518 
519 	old_fs = get_fs();
520 	set_fs(get_ds());
521 	/* The cast to a user pointer is valid due to the set_fs() */
522 	result = vfs_read(file, (void __user *)addr, count, &pos);
523 	set_fs(old_fs);
524 	return result;
525 }
526 
527 EXPORT_SYMBOL(kernel_read);
528 
529 static int exec_mmap(struct mm_struct *mm)
530 {
531 	struct task_struct *tsk;
532 	struct mm_struct * old_mm, *active_mm;
533 
534 	/* Notify parent that we're no longer interested in the old VM */
535 	tsk = current;
536 	old_mm = current->mm;
537 	mm_release(tsk, old_mm);
538 
539 	if (old_mm) {
540 		/*
541 		 * Make sure that if there is a core dump in progress
542 		 * for the old mm, we get out and die instead of going
543 		 * through with the exec.  We must hold mmap_sem around
544 		 * checking core_waiters and changing tsk->mm.  The
545 		 * core-inducing thread will increment core_waiters for
546 		 * each thread whose ->mm == old_mm.
547 		 */
548 		down_read(&old_mm->mmap_sem);
549 		if (unlikely(old_mm->core_waiters)) {
550 			up_read(&old_mm->mmap_sem);
551 			return -EINTR;
552 		}
553 	}
554 	task_lock(tsk);
555 	active_mm = tsk->active_mm;
556 	tsk->mm = mm;
557 	tsk->active_mm = mm;
558 	activate_mm(active_mm, mm);
559 	task_unlock(tsk);
560 	arch_pick_mmap_layout(mm);
561 	if (old_mm) {
562 		up_read(&old_mm->mmap_sem);
563 		BUG_ON(active_mm != old_mm);
564 		mmput(old_mm);
565 		return 0;
566 	}
567 	mmdrop(active_mm);
568 	return 0;
569 }
570 
571 /*
572  * This function makes sure the current process has its own signal table,
573  * so that flush_signal_handlers can later reset the handlers without
574  * disturbing other processes.  (Other processes might share the signal
575  * table via the CLONE_SIGHAND option to clone().)
576  */
577 static int de_thread(struct task_struct *tsk)
578 {
579 	struct signal_struct *sig = tsk->signal;
580 	struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
581 	spinlock_t *lock = &oldsighand->siglock;
582 	struct task_struct *leader = NULL;
583 	int count;
584 
585 	/*
586 	 * Tell all the sighand listeners that this sighand has
587 	 * been detached. The signalfd_detach() function grabs the
588 	 * sighand lock, if signal listeners are present on the sighand.
589 	 */
590 	signalfd_detach(tsk);
591 
592 	/*
593 	 * If we don't share sighandlers, then we aren't sharing anything
594 	 * and we can just re-use it all.
595 	 */
596 	if (atomic_read(&oldsighand->count) <= 1) {
597 		BUG_ON(atomic_read(&sig->count) != 1);
598 		exit_itimers(sig);
599 		return 0;
600 	}
601 
602 	newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
603 	if (!newsighand)
604 		return -ENOMEM;
605 
606 	if (thread_group_empty(tsk))
607 		goto no_thread_group;
608 
609 	/*
610 	 * Kill all other threads in the thread group.
611 	 * We must hold tasklist_lock to call zap_other_threads.
612 	 */
613 	read_lock(&tasklist_lock);
614 	spin_lock_irq(lock);
615 	if (sig->flags & SIGNAL_GROUP_EXIT) {
616 		/*
617 		 * Another group action in progress, just
618 		 * return so that the signal is processed.
619 		 */
620 		spin_unlock_irq(lock);
621 		read_unlock(&tasklist_lock);
622 		kmem_cache_free(sighand_cachep, newsighand);
623 		return -EAGAIN;
624 	}
625 
626 	/*
627 	 * child_reaper ignores SIGKILL, change it now.
628 	 * Reparenting needs write_lock on tasklist_lock,
629 	 * so it is safe to do it under read_lock.
630 	 */
631 	if (unlikely(tsk->group_leader == child_reaper(tsk)))
632 		tsk->nsproxy->pid_ns->child_reaper = tsk;
633 
634 	zap_other_threads(tsk);
635 	read_unlock(&tasklist_lock);
636 
637 	/*
638 	 * Account for the thread group leader hanging around:
639 	 */
640 	count = 1;
641 	if (!thread_group_leader(tsk)) {
642 		count = 2;
643 		/*
644 		 * The SIGALRM timer survives the exec, but needs to point
645 		 * at us as the new group leader now.  We have a race with
646 		 * a timer firing now getting the old leader, so we need to
647 		 * synchronize with any firing (by calling del_timer_sync)
648 		 * before we can safely let the old group leader die.
649 		 */
650 		sig->tsk = tsk;
651 		spin_unlock_irq(lock);
652 		if (hrtimer_cancel(&sig->real_timer))
653 			hrtimer_restart(&sig->real_timer);
654 		spin_lock_irq(lock);
655 	}
656 	while (atomic_read(&sig->count) > count) {
657 		sig->group_exit_task = tsk;
658 		sig->notify_count = count;
659 		__set_current_state(TASK_UNINTERRUPTIBLE);
660 		spin_unlock_irq(lock);
661 		schedule();
662 		spin_lock_irq(lock);
663 	}
664 	sig->group_exit_task = NULL;
665 	sig->notify_count = 0;
666 	spin_unlock_irq(lock);
667 
668 	/*
669 	 * At this point all other threads have exited, all we have to
670 	 * do is to wait for the thread group leader to become inactive,
671 	 * and to assume its PID:
672 	 */
673 	if (!thread_group_leader(tsk)) {
674 		/*
675 		 * Wait for the thread group leader to be a zombie.
676 		 * It should already be zombie at this point, most
677 		 * of the time.
678 		 */
679 		leader = tsk->group_leader;
680 		while (leader->exit_state != EXIT_ZOMBIE)
681 			yield();
682 
683 		/*
684 		 * The only record we have of the real-time age of a
685 		 * process, regardless of execs it's done, is start_time.
686 		 * All the past CPU time is accumulated in signal_struct
687 		 * from sister threads now dead.  But in this non-leader
688 		 * exec, nothing survives from the original leader thread,
689 		 * whose birth marks the true age of this process now.
690 		 * When we take on its identity by switching to its PID, we
691 		 * also take its birthdate (always earlier than our own).
692 		 */
693 		tsk->start_time = leader->start_time;
694 
695 		write_lock_irq(&tasklist_lock);
696 
697 		BUG_ON(leader->tgid != tsk->tgid);
698 		BUG_ON(tsk->pid == tsk->tgid);
699 		/*
700 		 * An exec() starts a new thread group with the
701 		 * TGID of the previous thread group. Rehash the
702 		 * two threads with a switched PID, and release
703 		 * the former thread group leader:
704 		 */
705 
706 		/* Become a process group leader with the old leader's pid.
707 		 * The old leader becomes a thread of the this thread group.
708 		 * Note: The old leader also uses this pid until release_task
709 		 *       is called.  Odd but simple and correct.
710 		 */
711 		detach_pid(tsk, PIDTYPE_PID);
712 		tsk->pid = leader->pid;
713 		attach_pid(tsk, PIDTYPE_PID,  find_pid(tsk->pid));
714 		transfer_pid(leader, tsk, PIDTYPE_PGID);
715 		transfer_pid(leader, tsk, PIDTYPE_SID);
716 		list_replace_rcu(&leader->tasks, &tsk->tasks);
717 
718 		tsk->group_leader = tsk;
719 		leader->group_leader = tsk;
720 
721 		tsk->exit_signal = SIGCHLD;
722 
723 		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
724 		leader->exit_state = EXIT_DEAD;
725 
726 		write_unlock_irq(&tasklist_lock);
727         }
728 
729 	/*
730 	 * There may be one thread left which is just exiting,
731 	 * but it's safe to stop telling the group to kill themselves.
732 	 */
733 	sig->flags = 0;
734 
735 no_thread_group:
736 	exit_itimers(sig);
737 	if (leader)
738 		release_task(leader);
739 
740 	BUG_ON(atomic_read(&sig->count) != 1);
741 
742 	if (atomic_read(&oldsighand->count) == 1) {
743 		/*
744 		 * Now that we nuked the rest of the thread group,
745 		 * it turns out we are not sharing sighand any more either.
746 		 * So we can just keep it.
747 		 */
748 		kmem_cache_free(sighand_cachep, newsighand);
749 	} else {
750 		/*
751 		 * Move our state over to newsighand and switch it in.
752 		 */
753 		atomic_set(&newsighand->count, 1);
754 		memcpy(newsighand->action, oldsighand->action,
755 		       sizeof(newsighand->action));
756 
757 		write_lock_irq(&tasklist_lock);
758 		spin_lock(&oldsighand->siglock);
759 		spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
760 
761 		rcu_assign_pointer(tsk->sighand, newsighand);
762 		recalc_sigpending();
763 
764 		spin_unlock(&newsighand->siglock);
765 		spin_unlock(&oldsighand->siglock);
766 		write_unlock_irq(&tasklist_lock);
767 
768 		__cleanup_sighand(oldsighand);
769 	}
770 
771 	BUG_ON(!thread_group_leader(tsk));
772 	return 0;
773 }
774 
775 /*
776  * These functions flushes out all traces of the currently running executable
777  * so that a new one can be started
778  */
779 
780 static void flush_old_files(struct files_struct * files)
781 {
782 	long j = -1;
783 	struct fdtable *fdt;
784 
785 	spin_lock(&files->file_lock);
786 	for (;;) {
787 		unsigned long set, i;
788 
789 		j++;
790 		i = j * __NFDBITS;
791 		fdt = files_fdtable(files);
792 		if (i >= fdt->max_fds)
793 			break;
794 		set = fdt->close_on_exec->fds_bits[j];
795 		if (!set)
796 			continue;
797 		fdt->close_on_exec->fds_bits[j] = 0;
798 		spin_unlock(&files->file_lock);
799 		for ( ; set ; i++,set >>= 1) {
800 			if (set & 1) {
801 				sys_close(i);
802 			}
803 		}
804 		spin_lock(&files->file_lock);
805 
806 	}
807 	spin_unlock(&files->file_lock);
808 }
809 
810 void get_task_comm(char *buf, struct task_struct *tsk)
811 {
812 	/* buf must be at least sizeof(tsk->comm) in size */
813 	task_lock(tsk);
814 	strncpy(buf, tsk->comm, sizeof(tsk->comm));
815 	task_unlock(tsk);
816 }
817 
818 void set_task_comm(struct task_struct *tsk, char *buf)
819 {
820 	task_lock(tsk);
821 	strlcpy(tsk->comm, buf, sizeof(tsk->comm));
822 	task_unlock(tsk);
823 }
824 
825 int flush_old_exec(struct linux_binprm * bprm)
826 {
827 	char * name;
828 	int i, ch, retval;
829 	struct files_struct *files;
830 	char tcomm[sizeof(current->comm)];
831 
832 	/*
833 	 * Make sure we have a private signal table and that
834 	 * we are unassociated from the previous thread group.
835 	 */
836 	retval = de_thread(current);
837 	if (retval)
838 		goto out;
839 
840 	/*
841 	 * Make sure we have private file handles. Ask the
842 	 * fork helper to do the work for us and the exit
843 	 * helper to do the cleanup of the old one.
844 	 */
845 	files = current->files;		/* refcounted so safe to hold */
846 	retval = unshare_files();
847 	if (retval)
848 		goto out;
849 	/*
850 	 * Release all of the old mmap stuff
851 	 */
852 	retval = exec_mmap(bprm->mm);
853 	if (retval)
854 		goto mmap_failed;
855 
856 	bprm->mm = NULL;		/* We're using it now */
857 
858 	/* This is the point of no return */
859 	put_files_struct(files);
860 
861 	current->sas_ss_sp = current->sas_ss_size = 0;
862 
863 	if (current->euid == current->uid && current->egid == current->gid)
864 		current->mm->dumpable = 1;
865 	else
866 		current->mm->dumpable = suid_dumpable;
867 
868 	name = bprm->filename;
869 
870 	/* Copies the binary name from after last slash */
871 	for (i=0; (ch = *(name++)) != '\0';) {
872 		if (ch == '/')
873 			i = 0; /* overwrite what we wrote */
874 		else
875 			if (i < (sizeof(tcomm) - 1))
876 				tcomm[i++] = ch;
877 	}
878 	tcomm[i] = '\0';
879 	set_task_comm(current, tcomm);
880 
881 	current->flags &= ~PF_RANDOMIZE;
882 	flush_thread();
883 
884 	/* Set the new mm task size. We have to do that late because it may
885 	 * depend on TIF_32BIT which is only updated in flush_thread() on
886 	 * some architectures like powerpc
887 	 */
888 	current->mm->task_size = TASK_SIZE;
889 
890 	if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
891 	    file_permission(bprm->file, MAY_READ) ||
892 	    (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
893 		suid_keys(current);
894 		current->mm->dumpable = suid_dumpable;
895 	}
896 
897 	/* An exec changes our domain. We are no longer part of the thread
898 	   group */
899 
900 	current->self_exec_id++;
901 
902 	flush_signal_handlers(current, 0);
903 	flush_old_files(current->files);
904 
905 	return 0;
906 
907 mmap_failed:
908 	reset_files_struct(current, files);
909 out:
910 	return retval;
911 }
912 
913 EXPORT_SYMBOL(flush_old_exec);
914 
915 /*
916  * Fill the binprm structure from the inode.
917  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
918  */
919 int prepare_binprm(struct linux_binprm *bprm)
920 {
921 	int mode;
922 	struct inode * inode = bprm->file->f_path.dentry->d_inode;
923 	int retval;
924 
925 	mode = inode->i_mode;
926 	if (bprm->file->f_op == NULL)
927 		return -EACCES;
928 
929 	bprm->e_uid = current->euid;
930 	bprm->e_gid = current->egid;
931 
932 	if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
933 		/* Set-uid? */
934 		if (mode & S_ISUID) {
935 			current->personality &= ~PER_CLEAR_ON_SETID;
936 			bprm->e_uid = inode->i_uid;
937 		}
938 
939 		/* Set-gid? */
940 		/*
941 		 * If setgid is set but no group execute bit then this
942 		 * is a candidate for mandatory locking, not a setgid
943 		 * executable.
944 		 */
945 		if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
946 			current->personality &= ~PER_CLEAR_ON_SETID;
947 			bprm->e_gid = inode->i_gid;
948 		}
949 	}
950 
951 	/* fill in binprm security blob */
952 	retval = security_bprm_set(bprm);
953 	if (retval)
954 		return retval;
955 
956 	memset(bprm->buf,0,BINPRM_BUF_SIZE);
957 	return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
958 }
959 
960 EXPORT_SYMBOL(prepare_binprm);
961 
962 static int unsafe_exec(struct task_struct *p)
963 {
964 	int unsafe = 0;
965 	if (p->ptrace & PT_PTRACED) {
966 		if (p->ptrace & PT_PTRACE_CAP)
967 			unsafe |= LSM_UNSAFE_PTRACE_CAP;
968 		else
969 			unsafe |= LSM_UNSAFE_PTRACE;
970 	}
971 	if (atomic_read(&p->fs->count) > 1 ||
972 	    atomic_read(&p->files->count) > 1 ||
973 	    atomic_read(&p->sighand->count) > 1)
974 		unsafe |= LSM_UNSAFE_SHARE;
975 
976 	return unsafe;
977 }
978 
979 void compute_creds(struct linux_binprm *bprm)
980 {
981 	int unsafe;
982 
983 	if (bprm->e_uid != current->uid)
984 		suid_keys(current);
985 	exec_keys(current);
986 
987 	task_lock(current);
988 	unsafe = unsafe_exec(current);
989 	security_bprm_apply_creds(bprm, unsafe);
990 	task_unlock(current);
991 	security_bprm_post_apply_creds(bprm);
992 }
993 EXPORT_SYMBOL(compute_creds);
994 
995 /*
996  * Arguments are '\0' separated strings found at the location bprm->p
997  * points to; chop off the first by relocating brpm->p to right after
998  * the first '\0' encountered.
999  */
1000 void remove_arg_zero(struct linux_binprm *bprm)
1001 {
1002 	if (bprm->argc) {
1003 		char ch;
1004 
1005 		do {
1006 			unsigned long offset;
1007 			unsigned long index;
1008 			char *kaddr;
1009 			struct page *page;
1010 
1011 			offset = bprm->p & ~PAGE_MASK;
1012 			index = bprm->p >> PAGE_SHIFT;
1013 
1014 			page = bprm->page[index];
1015 			kaddr = kmap_atomic(page, KM_USER0);
1016 
1017 			/* run through page until we reach end or find NUL */
1018 			do {
1019 				ch = *(kaddr + offset);
1020 
1021 				/* discard that character... */
1022 				bprm->p++;
1023 				offset++;
1024 			} while (offset < PAGE_SIZE && ch != '\0');
1025 
1026 			kunmap_atomic(kaddr, KM_USER0);
1027 
1028 			/* free the old page */
1029 			if (offset == PAGE_SIZE) {
1030 				__free_page(page);
1031 				bprm->page[index] = NULL;
1032 			}
1033 		} while (ch != '\0');
1034 
1035 		bprm->argc--;
1036 	}
1037 }
1038 EXPORT_SYMBOL(remove_arg_zero);
1039 
1040 /*
1041  * cycle the list of binary formats handler, until one recognizes the image
1042  */
1043 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1044 {
1045 	int try,retval;
1046 	struct linux_binfmt *fmt;
1047 #ifdef __alpha__
1048 	/* handle /sbin/loader.. */
1049 	{
1050 	    struct exec * eh = (struct exec *) bprm->buf;
1051 
1052 	    if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1053 		(eh->fh.f_flags & 0x3000) == 0x3000)
1054 	    {
1055 		struct file * file;
1056 		unsigned long loader;
1057 
1058 		allow_write_access(bprm->file);
1059 		fput(bprm->file);
1060 		bprm->file = NULL;
1061 
1062 	        loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1063 
1064 		file = open_exec("/sbin/loader");
1065 		retval = PTR_ERR(file);
1066 		if (IS_ERR(file))
1067 			return retval;
1068 
1069 		/* Remember if the application is TASO.  */
1070 		bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1071 
1072 		bprm->file = file;
1073 		bprm->loader = loader;
1074 		retval = prepare_binprm(bprm);
1075 		if (retval<0)
1076 			return retval;
1077 		/* should call search_binary_handler recursively here,
1078 		   but it does not matter */
1079 	    }
1080 	}
1081 #endif
1082 	retval = security_bprm_check(bprm);
1083 	if (retval)
1084 		return retval;
1085 
1086 	/* kernel module loader fixup */
1087 	/* so we don't try to load run modprobe in kernel space. */
1088 	set_fs(USER_DS);
1089 
1090 	retval = audit_bprm(bprm);
1091 	if (retval)
1092 		return retval;
1093 
1094 	retval = -ENOENT;
1095 	for (try=0; try<2; try++) {
1096 		read_lock(&binfmt_lock);
1097 		for (fmt = formats ; fmt ; fmt = fmt->next) {
1098 			int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1099 			if (!fn)
1100 				continue;
1101 			if (!try_module_get(fmt->module))
1102 				continue;
1103 			read_unlock(&binfmt_lock);
1104 			retval = fn(bprm, regs);
1105 			if (retval >= 0) {
1106 				put_binfmt(fmt);
1107 				allow_write_access(bprm->file);
1108 				if (bprm->file)
1109 					fput(bprm->file);
1110 				bprm->file = NULL;
1111 				current->did_exec = 1;
1112 				proc_exec_connector(current);
1113 				return retval;
1114 			}
1115 			read_lock(&binfmt_lock);
1116 			put_binfmt(fmt);
1117 			if (retval != -ENOEXEC || bprm->mm == NULL)
1118 				break;
1119 			if (!bprm->file) {
1120 				read_unlock(&binfmt_lock);
1121 				return retval;
1122 			}
1123 		}
1124 		read_unlock(&binfmt_lock);
1125 		if (retval != -ENOEXEC || bprm->mm == NULL) {
1126 			break;
1127 #ifdef CONFIG_KMOD
1128 		}else{
1129 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1130 			if (printable(bprm->buf[0]) &&
1131 			    printable(bprm->buf[1]) &&
1132 			    printable(bprm->buf[2]) &&
1133 			    printable(bprm->buf[3]))
1134 				break; /* -ENOEXEC */
1135 			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1136 #endif
1137 		}
1138 	}
1139 	return retval;
1140 }
1141 
1142 EXPORT_SYMBOL(search_binary_handler);
1143 
1144 /*
1145  * sys_execve() executes a new program.
1146  */
1147 int do_execve(char * filename,
1148 	char __user *__user *argv,
1149 	char __user *__user *envp,
1150 	struct pt_regs * regs)
1151 {
1152 	struct linux_binprm *bprm;
1153 	struct file *file;
1154 	int retval;
1155 	int i;
1156 
1157 	retval = -ENOMEM;
1158 	bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1159 	if (!bprm)
1160 		goto out_ret;
1161 
1162 	file = open_exec(filename);
1163 	retval = PTR_ERR(file);
1164 	if (IS_ERR(file))
1165 		goto out_kfree;
1166 
1167 	sched_exec();
1168 
1169 	bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1170 
1171 	bprm->file = file;
1172 	bprm->filename = filename;
1173 	bprm->interp = filename;
1174 	bprm->mm = mm_alloc();
1175 	retval = -ENOMEM;
1176 	if (!bprm->mm)
1177 		goto out_file;
1178 
1179 	retval = init_new_context(current, bprm->mm);
1180 	if (retval < 0)
1181 		goto out_mm;
1182 
1183 	bprm->argc = count(argv, bprm->p / sizeof(void *));
1184 	if ((retval = bprm->argc) < 0)
1185 		goto out_mm;
1186 
1187 	bprm->envc = count(envp, bprm->p / sizeof(void *));
1188 	if ((retval = bprm->envc) < 0)
1189 		goto out_mm;
1190 
1191 	retval = security_bprm_alloc(bprm);
1192 	if (retval)
1193 		goto out;
1194 
1195 	retval = prepare_binprm(bprm);
1196 	if (retval < 0)
1197 		goto out;
1198 
1199 	retval = copy_strings_kernel(1, &bprm->filename, bprm);
1200 	if (retval < 0)
1201 		goto out;
1202 
1203 	bprm->exec = bprm->p;
1204 	retval = copy_strings(bprm->envc, envp, bprm);
1205 	if (retval < 0)
1206 		goto out;
1207 
1208 	retval = copy_strings(bprm->argc, argv, bprm);
1209 	if (retval < 0)
1210 		goto out;
1211 
1212 	retval = search_binary_handler(bprm,regs);
1213 	if (retval >= 0) {
1214 		free_arg_pages(bprm);
1215 
1216 		/* execve success */
1217 		security_bprm_free(bprm);
1218 		acct_update_integrals(current);
1219 		kfree(bprm);
1220 		return retval;
1221 	}
1222 
1223 out:
1224 	/* Something went wrong, return the inode and free the argument pages*/
1225 	for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1226 		struct page * page = bprm->page[i];
1227 		if (page)
1228 			__free_page(page);
1229 	}
1230 
1231 	if (bprm->security)
1232 		security_bprm_free(bprm);
1233 
1234 out_mm:
1235 	if (bprm->mm)
1236 		mmdrop(bprm->mm);
1237 
1238 out_file:
1239 	if (bprm->file) {
1240 		allow_write_access(bprm->file);
1241 		fput(bprm->file);
1242 	}
1243 
1244 out_kfree:
1245 	kfree(bprm);
1246 
1247 out_ret:
1248 	return retval;
1249 }
1250 
1251 int set_binfmt(struct linux_binfmt *new)
1252 {
1253 	struct linux_binfmt *old = current->binfmt;
1254 
1255 	if (new) {
1256 		if (!try_module_get(new->module))
1257 			return -1;
1258 	}
1259 	current->binfmt = new;
1260 	if (old)
1261 		module_put(old->module);
1262 	return 0;
1263 }
1264 
1265 EXPORT_SYMBOL(set_binfmt);
1266 
1267 #define CORENAME_MAX_SIZE 64
1268 
1269 /* format_corename will inspect the pattern parameter, and output a
1270  * name into corename, which must have space for at least
1271  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1272  */
1273 static int format_corename(char *corename, const char *pattern, long signr)
1274 {
1275 	const char *pat_ptr = pattern;
1276 	char *out_ptr = corename;
1277 	char *const out_end = corename + CORENAME_MAX_SIZE;
1278 	int rc;
1279 	int pid_in_pattern = 0;
1280 	int ispipe = 0;
1281 
1282 	if (*pattern == '|')
1283 		ispipe = 1;
1284 
1285 	/* Repeat as long as we have more pattern to process and more output
1286 	   space */
1287 	while (*pat_ptr) {
1288 		if (*pat_ptr != '%') {
1289 			if (out_ptr == out_end)
1290 				goto out;
1291 			*out_ptr++ = *pat_ptr++;
1292 		} else {
1293 			switch (*++pat_ptr) {
1294 			case 0:
1295 				goto out;
1296 			/* Double percent, output one percent */
1297 			case '%':
1298 				if (out_ptr == out_end)
1299 					goto out;
1300 				*out_ptr++ = '%';
1301 				break;
1302 			/* pid */
1303 			case 'p':
1304 				pid_in_pattern = 1;
1305 				rc = snprintf(out_ptr, out_end - out_ptr,
1306 					      "%d", current->tgid);
1307 				if (rc > out_end - out_ptr)
1308 					goto out;
1309 				out_ptr += rc;
1310 				break;
1311 			/* uid */
1312 			case 'u':
1313 				rc = snprintf(out_ptr, out_end - out_ptr,
1314 					      "%d", current->uid);
1315 				if (rc > out_end - out_ptr)
1316 					goto out;
1317 				out_ptr += rc;
1318 				break;
1319 			/* gid */
1320 			case 'g':
1321 				rc = snprintf(out_ptr, out_end - out_ptr,
1322 					      "%d", current->gid);
1323 				if (rc > out_end - out_ptr)
1324 					goto out;
1325 				out_ptr += rc;
1326 				break;
1327 			/* signal that caused the coredump */
1328 			case 's':
1329 				rc = snprintf(out_ptr, out_end - out_ptr,
1330 					      "%ld", signr);
1331 				if (rc > out_end - out_ptr)
1332 					goto out;
1333 				out_ptr += rc;
1334 				break;
1335 			/* UNIX time of coredump */
1336 			case 't': {
1337 				struct timeval tv;
1338 				do_gettimeofday(&tv);
1339 				rc = snprintf(out_ptr, out_end - out_ptr,
1340 					      "%lu", tv.tv_sec);
1341 				if (rc > out_end - out_ptr)
1342 					goto out;
1343 				out_ptr += rc;
1344 				break;
1345 			}
1346 			/* hostname */
1347 			case 'h':
1348 				down_read(&uts_sem);
1349 				rc = snprintf(out_ptr, out_end - out_ptr,
1350 					      "%s", utsname()->nodename);
1351 				up_read(&uts_sem);
1352 				if (rc > out_end - out_ptr)
1353 					goto out;
1354 				out_ptr += rc;
1355 				break;
1356 			/* executable */
1357 			case 'e':
1358 				rc = snprintf(out_ptr, out_end - out_ptr,
1359 					      "%s", current->comm);
1360 				if (rc > out_end - out_ptr)
1361 					goto out;
1362 				out_ptr += rc;
1363 				break;
1364 			default:
1365 				break;
1366 			}
1367 			++pat_ptr;
1368 		}
1369 	}
1370 	/* Backward compatibility with core_uses_pid:
1371 	 *
1372 	 * If core_pattern does not include a %p (as is the default)
1373 	 * and core_uses_pid is set, then .%pid will be appended to
1374 	 * the filename. Do not do this for piped commands. */
1375 	if (!ispipe && !pid_in_pattern
1376             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1377 		rc = snprintf(out_ptr, out_end - out_ptr,
1378 			      ".%d", current->tgid);
1379 		if (rc > out_end - out_ptr)
1380 			goto out;
1381 		out_ptr += rc;
1382 	}
1383 out:
1384 	*out_ptr = 0;
1385 	return ispipe;
1386 }
1387 
1388 static void zap_process(struct task_struct *start)
1389 {
1390 	struct task_struct *t;
1391 
1392 	start->signal->flags = SIGNAL_GROUP_EXIT;
1393 	start->signal->group_stop_count = 0;
1394 
1395 	t = start;
1396 	do {
1397 		if (t != current && t->mm) {
1398 			t->mm->core_waiters++;
1399 			sigaddset(&t->pending.signal, SIGKILL);
1400 			signal_wake_up(t, 1);
1401 		}
1402 	} while ((t = next_thread(t)) != start);
1403 }
1404 
1405 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1406 				int exit_code)
1407 {
1408 	struct task_struct *g, *p;
1409 	unsigned long flags;
1410 	int err = -EAGAIN;
1411 
1412 	spin_lock_irq(&tsk->sighand->siglock);
1413 	if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1414 		tsk->signal->group_exit_code = exit_code;
1415 		zap_process(tsk);
1416 		err = 0;
1417 	}
1418 	spin_unlock_irq(&tsk->sighand->siglock);
1419 	if (err)
1420 		return err;
1421 
1422 	if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1423 		goto done;
1424 
1425 	rcu_read_lock();
1426 	for_each_process(g) {
1427 		if (g == tsk->group_leader)
1428 			continue;
1429 
1430 		p = g;
1431 		do {
1432 			if (p->mm) {
1433 				if (p->mm == mm) {
1434 					/*
1435 					 * p->sighand can't disappear, but
1436 					 * may be changed by de_thread()
1437 					 */
1438 					lock_task_sighand(p, &flags);
1439 					zap_process(p);
1440 					unlock_task_sighand(p, &flags);
1441 				}
1442 				break;
1443 			}
1444 		} while ((p = next_thread(p)) != g);
1445 	}
1446 	rcu_read_unlock();
1447 done:
1448 	return mm->core_waiters;
1449 }
1450 
1451 static int coredump_wait(int exit_code)
1452 {
1453 	struct task_struct *tsk = current;
1454 	struct mm_struct *mm = tsk->mm;
1455 	struct completion startup_done;
1456 	struct completion *vfork_done;
1457 	int core_waiters;
1458 
1459 	init_completion(&mm->core_done);
1460 	init_completion(&startup_done);
1461 	mm->core_startup_done = &startup_done;
1462 
1463 	core_waiters = zap_threads(tsk, mm, exit_code);
1464 	up_write(&mm->mmap_sem);
1465 
1466 	if (unlikely(core_waiters < 0))
1467 		goto fail;
1468 
1469 	/*
1470 	 * Make sure nobody is waiting for us to release the VM,
1471 	 * otherwise we can deadlock when we wait on each other
1472 	 */
1473 	vfork_done = tsk->vfork_done;
1474 	if (vfork_done) {
1475 		tsk->vfork_done = NULL;
1476 		complete(vfork_done);
1477 	}
1478 
1479 	if (core_waiters)
1480 		wait_for_completion(&startup_done);
1481 fail:
1482 	BUG_ON(mm->core_waiters);
1483 	return core_waiters;
1484 }
1485 
1486 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1487 {
1488 	char corename[CORENAME_MAX_SIZE + 1];
1489 	struct mm_struct *mm = current->mm;
1490 	struct linux_binfmt * binfmt;
1491 	struct inode * inode;
1492 	struct file * file;
1493 	int retval = 0;
1494 	int fsuid = current->fsuid;
1495 	int flag = 0;
1496 	int ispipe = 0;
1497 
1498 	audit_core_dumps(signr);
1499 
1500 	binfmt = current->binfmt;
1501 	if (!binfmt || !binfmt->core_dump)
1502 		goto fail;
1503 	down_write(&mm->mmap_sem);
1504 	if (!mm->dumpable) {
1505 		up_write(&mm->mmap_sem);
1506 		goto fail;
1507 	}
1508 
1509 	/*
1510 	 *	We cannot trust fsuid as being the "true" uid of the
1511 	 *	process nor do we know its entire history. We only know it
1512 	 *	was tainted so we dump it as root in mode 2.
1513 	 */
1514 	if (mm->dumpable == 2) {	/* Setuid core dump mode */
1515 		flag = O_EXCL;		/* Stop rewrite attacks */
1516 		current->fsuid = 0;	/* Dump root private */
1517 	}
1518 	mm->dumpable = 0;
1519 
1520 	retval = coredump_wait(exit_code);
1521 	if (retval < 0)
1522 		goto fail;
1523 
1524 	/*
1525 	 * Clear any false indication of pending signals that might
1526 	 * be seen by the filesystem code called to write the core file.
1527 	 */
1528 	clear_thread_flag(TIF_SIGPENDING);
1529 
1530 	if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1531 		goto fail_unlock;
1532 
1533 	/*
1534 	 * lock_kernel() because format_corename() is controlled by sysctl, which
1535 	 * uses lock_kernel()
1536 	 */
1537  	lock_kernel();
1538 	ispipe = format_corename(corename, core_pattern, signr);
1539 	unlock_kernel();
1540  	if (ispipe) {
1541 		/* SIGPIPE can happen, but it's just never processed */
1542  		if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1543  			printk(KERN_INFO "Core dump to %s pipe failed\n",
1544 			       corename);
1545  			goto fail_unlock;
1546  		}
1547  	} else
1548  		file = filp_open(corename,
1549 				 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1550 				 0600);
1551 	if (IS_ERR(file))
1552 		goto fail_unlock;
1553 	inode = file->f_path.dentry->d_inode;
1554 	if (inode->i_nlink > 1)
1555 		goto close_fail;	/* multiple links - don't dump */
1556 	if (!ispipe && d_unhashed(file->f_path.dentry))
1557 		goto close_fail;
1558 
1559 	/* AK: actually i see no reason to not allow this for named pipes etc.,
1560 	   but keep the previous behaviour for now. */
1561 	if (!ispipe && !S_ISREG(inode->i_mode))
1562 		goto close_fail;
1563 	if (!file->f_op)
1564 		goto close_fail;
1565 	if (!file->f_op->write)
1566 		goto close_fail;
1567 	if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1568 		goto close_fail;
1569 
1570 	retval = binfmt->core_dump(signr, regs, file);
1571 
1572 	if (retval)
1573 		current->signal->group_exit_code |= 0x80;
1574 close_fail:
1575 	filp_close(file, NULL);
1576 fail_unlock:
1577 	current->fsuid = fsuid;
1578 	complete_all(&mm->core_done);
1579 fail:
1580 	return retval;
1581 }
1582