54135df2a9662cbf1f222ee468067812f52e1f72
[linux-2.6.git] / fs / exec.c
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/module.h>
42 #include <linux/namei.h>
43 #include <linux/proc_fs.h>
44 #include <linux/ptrace.h>
45 #include <linux/mount.h>
46 #include <linux/security.h>
47 #include <linux/syscalls.h>
48 #include <linux/rmap.h>
49 #include <linux/acct.h>
50 #include <linux/cn_proc.h>
51 #include <linux/audit.h>
52
53 #include <asm/uaccess.h>
54 #include <asm/mmu_context.h>
55
56 #ifdef CONFIG_KMOD
57 #include <linux/kmod.h>
58 #endif
59
60 int core_uses_pid;
61 char core_pattern[65] = "core";
62 int suid_dumpable = 0;
63
64 EXPORT_SYMBOL(suid_dumpable);
65 /* The maximal length of core_pattern is also specified in sysctl.c */
66
67 static struct linux_binfmt *formats;
68 static DEFINE_RWLOCK(binfmt_lock);
69
70 int register_binfmt(struct linux_binfmt * fmt)
71 {
72         struct linux_binfmt ** tmp = &formats;
73
74         if (!fmt)
75                 return -EINVAL;
76         if (fmt->next)
77                 return -EBUSY;
78         write_lock(&binfmt_lock);
79         while (*tmp) {
80                 if (fmt == *tmp) {
81                         write_unlock(&binfmt_lock);
82                         return -EBUSY;
83                 }
84                 tmp = &(*tmp)->next;
85         }
86         fmt->next = formats;
87         formats = fmt;
88         write_unlock(&binfmt_lock);
89         return 0;       
90 }
91
92 EXPORT_SYMBOL(register_binfmt);
93
94 int unregister_binfmt(struct linux_binfmt * fmt)
95 {
96         struct linux_binfmt ** tmp = &formats;
97
98         write_lock(&binfmt_lock);
99         while (*tmp) {
100                 if (fmt == *tmp) {
101                         *tmp = fmt->next;
102                         write_unlock(&binfmt_lock);
103                         return 0;
104                 }
105                 tmp = &(*tmp)->next;
106         }
107         write_unlock(&binfmt_lock);
108         return -EINVAL;
109 }
110
111 EXPORT_SYMBOL(unregister_binfmt);
112
113 static inline void put_binfmt(struct linux_binfmt * fmt)
114 {
115         module_put(fmt->module);
116 }
117
118 /*
119  * Note that a shared library must be both readable and executable due to
120  * security reasons.
121  *
122  * Also note that we take the address to load from from the file itself.
123  */
124 asmlinkage long sys_uselib(const char __user * library)
125 {
126         struct file * file;
127         struct nameidata nd;
128         int error;
129
130         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
131         if (error)
132                 goto out;
133
134         error = -EINVAL;
135         if (!S_ISREG(nd.dentry->d_inode->i_mode))
136                 goto exit;
137
138         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
139         if (error)
140                 goto exit;
141
142         file = nameidata_to_filp(&nd, O_RDONLY);
143         error = PTR_ERR(file);
144         if (IS_ERR(file))
145                 goto out;
146
147         error = -ENOEXEC;
148         if(file->f_op) {
149                 struct linux_binfmt * fmt;
150
151                 read_lock(&binfmt_lock);
152                 for (fmt = formats ; fmt ; fmt = fmt->next) {
153                         if (!fmt->load_shlib)
154                                 continue;
155                         if (!try_module_get(fmt->module))
156                                 continue;
157                         read_unlock(&binfmt_lock);
158                         error = fmt->load_shlib(file);
159                         read_lock(&binfmt_lock);
160                         put_binfmt(fmt);
161                         if (error != -ENOEXEC)
162                                 break;
163                 }
164                 read_unlock(&binfmt_lock);
165         }
166         fput(file);
167 out:
168         return error;
169 exit:
170         release_open_intent(&nd);
171         path_release(&nd);
172         goto out;
173 }
174
175 /*
176  * count() counts the number of strings in array ARGV.
177  */
178 static int count(char __user * __user * argv, int max)
179 {
180         int i = 0;
181
182         if (argv != NULL) {
183                 for (;;) {
184                         char __user * p;
185
186                         if (get_user(p, argv))
187                                 return -EFAULT;
188                         if (!p)
189                                 break;
190                         argv++;
191                         if(++i > max)
192                                 return -E2BIG;
193                         cond_resched();
194                 }
195         }
196         return i;
197 }
198
199 /*
200  * 'copy_strings()' copies argument/environment strings from user
201  * memory to free pages in kernel mem. These are in a format ready
202  * to be put directly into the top of new user memory.
203  */
204 static int copy_strings(int argc, char __user * __user * argv,
205                         struct linux_binprm *bprm)
206 {
207         struct page *kmapped_page = NULL;
208         char *kaddr = NULL;
209         int ret;
210
211         while (argc-- > 0) {
212                 char __user *str;
213                 int len;
214                 unsigned long pos;
215
216                 if (get_user(str, argv+argc) ||
217                                 !(len = strnlen_user(str, bprm->p))) {
218                         ret = -EFAULT;
219                         goto out;
220                 }
221
222                 if (bprm->p < len)  {
223                         ret = -E2BIG;
224                         goto out;
225                 }
226
227                 bprm->p -= len;
228                 /* XXX: add architecture specific overflow check here. */
229                 pos = bprm->p;
230
231                 while (len > 0) {
232                         int i, new, err;
233                         int offset, bytes_to_copy;
234                         struct page *page;
235
236                         offset = pos % PAGE_SIZE;
237                         i = pos/PAGE_SIZE;
238                         page = bprm->page[i];
239                         new = 0;
240                         if (!page) {
241                                 page = alloc_page(GFP_HIGHUSER);
242                                 bprm->page[i] = page;
243                                 if (!page) {
244                                         ret = -ENOMEM;
245                                         goto out;
246                                 }
247                                 new = 1;
248                         }
249
250                         if (page != kmapped_page) {
251                                 if (kmapped_page)
252                                         kunmap(kmapped_page);
253                                 kmapped_page = page;
254                                 kaddr = kmap(kmapped_page);
255                         }
256                         if (new && offset)
257                                 memset(kaddr, 0, offset);
258                         bytes_to_copy = PAGE_SIZE - offset;
259                         if (bytes_to_copy > len) {
260                                 bytes_to_copy = len;
261                                 if (new)
262                                         memset(kaddr+offset+len, 0,
263                                                 PAGE_SIZE-offset-len);
264                         }
265                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
266                         if (err) {
267                                 ret = -EFAULT;
268                                 goto out;
269                         }
270
271                         pos += bytes_to_copy;
272                         str += bytes_to_copy;
273                         len -= bytes_to_copy;
274                 }
275         }
276         ret = 0;
277 out:
278         if (kmapped_page)
279                 kunmap(kmapped_page);
280         return ret;
281 }
282
283 /*
284  * Like copy_strings, but get argv and its values from kernel memory.
285  */
286 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
287 {
288         int r;
289         mm_segment_t oldfs = get_fs();
290         set_fs(KERNEL_DS);
291         r = copy_strings(argc, (char __user * __user *)argv, bprm);
292         set_fs(oldfs);
293         return r;
294 }
295
296 EXPORT_SYMBOL(copy_strings_kernel);
297
298 #ifdef CONFIG_MMU
299 /*
300  * This routine is used to map in a page into an address space: needed by
301  * execve() for the initial stack and environment pages.
302  *
303  * vma->vm_mm->mmap_sem is held for writing.
304  */
305 void install_arg_page(struct vm_area_struct *vma,
306                         struct page *page, unsigned long address)
307 {
308         struct mm_struct *mm = vma->vm_mm;
309         pte_t * pte;
310         spinlock_t *ptl;
311
312         if (unlikely(anon_vma_prepare(vma)))
313                 goto out;
314
315         flush_dcache_page(page);
316         pte = get_locked_pte(mm, address, &ptl);
317         if (!pte)
318                 goto out;
319         if (!pte_none(*pte)) {
320                 pte_unmap_unlock(pte, ptl);
321                 goto out;
322         }
323         inc_mm_counter(mm, anon_rss);
324         lru_cache_add_active(page);
325         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
326                                         page, vma->vm_page_prot))));
327         page_add_new_anon_rmap(page, vma, address);
328         pte_unmap_unlock(pte, ptl);
329
330         /* no need for flush_tlb */
331         return;
332 out:
333         __free_page(page);
334         force_sig(SIGKILL, current);
335 }
336
337 #define EXTRA_STACK_VM_PAGES    20      /* random */
338
339 int setup_arg_pages(struct linux_binprm *bprm,
340                     unsigned long stack_top,
341                     int executable_stack)
342 {
343         unsigned long stack_base;
344         struct vm_area_struct *mpnt;
345         struct mm_struct *mm = current->mm;
346         int i, ret;
347         long arg_size;
348
349 #ifdef CONFIG_STACK_GROWSUP
350         /* Move the argument and environment strings to the bottom of the
351          * stack space.
352          */
353         int offset, j;
354         char *to, *from;
355
356         /* Start by shifting all the pages down */
357         i = 0;
358         for (j = 0; j < MAX_ARG_PAGES; j++) {
359                 struct page *page = bprm->page[j];
360                 if (!page)
361                         continue;
362                 bprm->page[i++] = page;
363         }
364
365         /* Now move them within their pages */
366         offset = bprm->p % PAGE_SIZE;
367         to = kmap(bprm->page[0]);
368         for (j = 1; j < i; j++) {
369                 memmove(to, to + offset, PAGE_SIZE - offset);
370                 from = kmap(bprm->page[j]);
371                 memcpy(to + PAGE_SIZE - offset, from, offset);
372                 kunmap(bprm->page[j - 1]);
373                 to = from;
374         }
375         memmove(to, to + offset, PAGE_SIZE - offset);
376         kunmap(bprm->page[j - 1]);
377
378         /* Limit stack size to 1GB */
379         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
380         if (stack_base > (1 << 30))
381                 stack_base = 1 << 30;
382         stack_base = PAGE_ALIGN(stack_top - stack_base);
383
384         /* Adjust bprm->p to point to the end of the strings. */
385         bprm->p = stack_base + PAGE_SIZE * i - offset;
386
387         mm->arg_start = stack_base;
388         arg_size = i << PAGE_SHIFT;
389
390         /* zero pages that were copied above */
391         while (i < MAX_ARG_PAGES)
392                 bprm->page[i++] = NULL;
393 #else
394         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
395         stack_base = PAGE_ALIGN(stack_base);
396         bprm->p += stack_base;
397         mm->arg_start = bprm->p;
398         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
399 #endif
400
401         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
402
403         if (bprm->loader)
404                 bprm->loader += stack_base;
405         bprm->exec += stack_base;
406
407         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
408         if (!mpnt)
409                 return -ENOMEM;
410
411         memset(mpnt, 0, sizeof(*mpnt));
412
413         down_write(&mm->mmap_sem);
414         {
415                 mpnt->vm_mm = mm;
416 #ifdef CONFIG_STACK_GROWSUP
417                 mpnt->vm_start = stack_base;
418                 mpnt->vm_end = stack_base + arg_size;
419 #else
420                 mpnt->vm_end = stack_top;
421                 mpnt->vm_start = mpnt->vm_end - arg_size;
422 #endif
423                 /* Adjust stack execute permissions; explicitly enable
424                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
425                  * and leave alone (arch default) otherwise. */
426                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
427                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
428                 else if (executable_stack == EXSTACK_DISABLE_X)
429                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
430                 else
431                         mpnt->vm_flags = VM_STACK_FLAGS;
432                 mpnt->vm_flags |= mm->def_flags;
433                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
434                 if ((ret = insert_vm_struct(mm, mpnt))) {
435                         up_write(&mm->mmap_sem);
436                         kmem_cache_free(vm_area_cachep, mpnt);
437                         return ret;
438                 }
439                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
440         }
441
442         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
443                 struct page *page = bprm->page[i];
444                 if (page) {
445                         bprm->page[i] = NULL;
446                         install_arg_page(mpnt, page, stack_base);
447                 }
448                 stack_base += PAGE_SIZE;
449         }
450         up_write(&mm->mmap_sem);
451         
452         return 0;
453 }
454
455 EXPORT_SYMBOL(setup_arg_pages);
456
457 #define free_arg_pages(bprm) do { } while (0)
458
459 #else
460
461 static inline void free_arg_pages(struct linux_binprm *bprm)
462 {
463         int i;
464
465         for (i = 0; i < MAX_ARG_PAGES; i++) {
466                 if (bprm->page[i])
467                         __free_page(bprm->page[i]);
468                 bprm->page[i] = NULL;
469         }
470 }
471
472 #endif /* CONFIG_MMU */
473
474 struct file *open_exec(const char *name)
475 {
476         struct nameidata nd;
477         int err;
478         struct file *file;
479
480         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
481         file = ERR_PTR(err);
482
483         if (!err) {
484                 struct inode *inode = nd.dentry->d_inode;
485                 file = ERR_PTR(-EACCES);
486                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
487                     S_ISREG(inode->i_mode)) {
488                         int err = vfs_permission(&nd, MAY_EXEC);
489                         file = ERR_PTR(err);
490                         if (!err) {
491                                 file = nameidata_to_filp(&nd, O_RDONLY);
492                                 if (!IS_ERR(file)) {
493                                         err = deny_write_access(file);
494                                         if (err) {
495                                                 fput(file);
496                                                 file = ERR_PTR(err);
497                                         }
498                                 }
499 out:
500                                 return file;
501                         }
502                 }
503                 release_open_intent(&nd);
504                 path_release(&nd);
505         }
506         goto out;
507 }
508
509 EXPORT_SYMBOL(open_exec);
510
511 int kernel_read(struct file *file, unsigned long offset,
512         char *addr, unsigned long count)
513 {
514         mm_segment_t old_fs;
515         loff_t pos = offset;
516         int result;
517
518         old_fs = get_fs();
519         set_fs(get_ds());
520         /* The cast to a user pointer is valid due to the set_fs() */
521         result = vfs_read(file, (void __user *)addr, count, &pos);
522         set_fs(old_fs);
523         return result;
524 }
525
526 EXPORT_SYMBOL(kernel_read);
527
528 static int exec_mmap(struct mm_struct *mm)
529 {
530         struct task_struct *tsk;
531         struct mm_struct * old_mm, *active_mm;
532
533         /* Notify parent that we're no longer interested in the old VM */
534         tsk = current;
535         old_mm = current->mm;
536         mm_release(tsk, old_mm);
537
538         if (old_mm) {
539                 /*
540                  * Make sure that if there is a core dump in progress
541                  * for the old mm, we get out and die instead of going
542                  * through with the exec.  We must hold mmap_sem around
543                  * checking core_waiters and changing tsk->mm.  The
544                  * core-inducing thread will increment core_waiters for
545                  * each thread whose ->mm == old_mm.
546                  */
547                 down_read(&old_mm->mmap_sem);
548                 if (unlikely(old_mm->core_waiters)) {
549                         up_read(&old_mm->mmap_sem);
550                         return -EINTR;
551                 }
552         }
553         task_lock(tsk);
554         active_mm = tsk->active_mm;
555         tsk->mm = mm;
556         tsk->active_mm = mm;
557         activate_mm(active_mm, mm);
558         task_unlock(tsk);
559         arch_pick_mmap_layout(mm);
560         if (old_mm) {
561                 up_read(&old_mm->mmap_sem);
562                 BUG_ON(active_mm != old_mm);
563                 mmput(old_mm);
564                 return 0;
565         }
566         mmdrop(active_mm);
567         return 0;
568 }
569
570 /*
571  * This function makes sure the current process has its own signal table,
572  * so that flush_signal_handlers can later reset the handlers without
573  * disturbing other processes.  (Other processes might share the signal
574  * table via the CLONE_SIGHAND option to clone().)
575  */
576 static int de_thread(struct task_struct *tsk)
577 {
578         struct signal_struct *sig = tsk->signal;
579         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
580         spinlock_t *lock = &oldsighand->siglock;
581         struct task_struct *leader = NULL;
582         int count;
583
584         /*
585          * If we don't share sighandlers, then we aren't sharing anything
586          * and we can just re-use it all.
587          */
588         if (atomic_read(&oldsighand->count) <= 1) {
589                 BUG_ON(atomic_read(&sig->count) != 1);
590                 exit_itimers(sig);
591                 return 0;
592         }
593
594         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
595         if (!newsighand)
596                 return -ENOMEM;
597
598         if (thread_group_empty(current))
599                 goto no_thread_group;
600
601         /*
602          * Kill all other threads in the thread group.
603          * We must hold tasklist_lock to call zap_other_threads.
604          */
605         read_lock(&tasklist_lock);
606         spin_lock_irq(lock);
607         if (sig->flags & SIGNAL_GROUP_EXIT) {
608                 /*
609                  * Another group action in progress, just
610                  * return so that the signal is processed.
611                  */
612                 spin_unlock_irq(lock);
613                 read_unlock(&tasklist_lock);
614                 kmem_cache_free(sighand_cachep, newsighand);
615                 return -EAGAIN;
616         }
617
618         /*
619          * child_reaper ignores SIGKILL, change it now.
620          * Reparenting needs write_lock on tasklist_lock,
621          * so it is safe to do it under read_lock.
622          */
623         if (unlikely(current->group_leader == child_reaper))
624                 child_reaper = current;
625
626         zap_other_threads(current);
627         read_unlock(&tasklist_lock);
628
629         /*
630          * Account for the thread group leader hanging around:
631          */
632         count = 1;
633         if (!thread_group_leader(current)) {
634                 count = 2;
635                 /*
636                  * The SIGALRM timer survives the exec, but needs to point
637                  * at us as the new group leader now.  We have a race with
638                  * a timer firing now getting the old leader, so we need to
639                  * synchronize with any firing (by calling del_timer_sync)
640                  * before we can safely let the old group leader die.
641                  */
642                 sig->tsk = current;
643                 spin_unlock_irq(lock);
644                 if (hrtimer_cancel(&sig->real_timer))
645                         hrtimer_restart(&sig->real_timer);
646                 spin_lock_irq(lock);
647         }
648         while (atomic_read(&sig->count) > count) {
649                 sig->group_exit_task = current;
650                 sig->notify_count = count;
651                 __set_current_state(TASK_UNINTERRUPTIBLE);
652                 spin_unlock_irq(lock);
653                 schedule();
654                 spin_lock_irq(lock);
655         }
656         sig->group_exit_task = NULL;
657         sig->notify_count = 0;
658         spin_unlock_irq(lock);
659
660         /*
661          * At this point all other threads have exited, all we have to
662          * do is to wait for the thread group leader to become inactive,
663          * and to assume its PID:
664          */
665         if (!thread_group_leader(current)) {
666                 /*
667                  * Wait for the thread group leader to be a zombie.
668                  * It should already be zombie at this point, most
669                  * of the time.
670                  */
671                 leader = current->group_leader;
672                 while (leader->exit_state != EXIT_ZOMBIE)
673                         yield();
674
675                 /*
676                  * The only record we have of the real-time age of a
677                  * process, regardless of execs it's done, is start_time.
678                  * All the past CPU time is accumulated in signal_struct
679                  * from sister threads now dead.  But in this non-leader
680                  * exec, nothing survives from the original leader thread,
681                  * whose birth marks the true age of this process now.
682                  * When we take on its identity by switching to its PID, we
683                  * also take its birthdate (always earlier than our own).
684                  */
685                 current->start_time = leader->start_time;
686
687                 write_lock_irq(&tasklist_lock);
688
689                 BUG_ON(leader->tgid != current->tgid);
690                 BUG_ON(current->pid == current->tgid);
691                 /*
692                  * An exec() starts a new thread group with the
693                  * TGID of the previous thread group. Rehash the
694                  * two threads with a switched PID, and release
695                  * the former thread group leader:
696                  */
697
698                 /* Become a process group leader with the old leader's pid.
699                  * Note: The old leader also uses thispid until release_task
700                  *       is called.  Odd but simple and correct.
701                  */
702                 detach_pid(current, PIDTYPE_PID);
703                 current->pid = leader->pid;
704                 attach_pid(current, PIDTYPE_PID,  current->pid);
705                 attach_pid(current, PIDTYPE_PGID, current->signal->pgrp);
706                 attach_pid(current, PIDTYPE_SID,  current->signal->session);
707                 list_replace_rcu(&leader->tasks, &current->tasks);
708
709                 current->group_leader = current;
710                 leader->group_leader = current;
711
712                 /* Reduce leader to a thread */
713                 detach_pid(leader, PIDTYPE_PGID);
714                 detach_pid(leader, PIDTYPE_SID);
715
716                 current->exit_signal = SIGCHLD;
717
718                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
719                 leader->exit_state = EXIT_DEAD;
720
721                 write_unlock_irq(&tasklist_lock);
722         }
723
724         /*
725          * There may be one thread left which is just exiting,
726          * but it's safe to stop telling the group to kill themselves.
727          */
728         sig->flags = 0;
729
730 no_thread_group:
731         exit_itimers(sig);
732         if (leader)
733                 release_task(leader);
734
735         BUG_ON(atomic_read(&sig->count) != 1);
736
737         if (atomic_read(&oldsighand->count) == 1) {
738                 /*
739                  * Now that we nuked the rest of the thread group,
740                  * it turns out we are not sharing sighand any more either.
741                  * So we can just keep it.
742                  */
743                 kmem_cache_free(sighand_cachep, newsighand);
744         } else {
745                 /*
746                  * Move our state over to newsighand and switch it in.
747                  */
748                 atomic_set(&newsighand->count, 1);
749                 memcpy(newsighand->action, oldsighand->action,
750                        sizeof(newsighand->action));
751
752                 write_lock_irq(&tasklist_lock);
753                 spin_lock(&oldsighand->siglock);
754                 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
755
756                 rcu_assign_pointer(current->sighand, newsighand);
757                 recalc_sigpending();
758
759                 spin_unlock(&newsighand->siglock);
760                 spin_unlock(&oldsighand->siglock);
761                 write_unlock_irq(&tasklist_lock);
762
763                 if (atomic_dec_and_test(&oldsighand->count))
764                         kmem_cache_free(sighand_cachep, oldsighand);
765         }
766
767         BUG_ON(!thread_group_leader(current));
768         return 0;
769 }
770         
771 /*
772  * These functions flushes out all traces of the currently running executable
773  * so that a new one can be started
774  */
775
776 static void flush_old_files(struct files_struct * files)
777 {
778         long j = -1;
779         struct fdtable *fdt;
780
781         spin_lock(&files->file_lock);
782         for (;;) {
783                 unsigned long set, i;
784
785                 j++;
786                 i = j * __NFDBITS;
787                 fdt = files_fdtable(files);
788                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
789                         break;
790                 set = fdt->close_on_exec->fds_bits[j];
791                 if (!set)
792                         continue;
793                 fdt->close_on_exec->fds_bits[j] = 0;
794                 spin_unlock(&files->file_lock);
795                 for ( ; set ; i++,set >>= 1) {
796                         if (set & 1) {
797                                 sys_close(i);
798                         }
799                 }
800                 spin_lock(&files->file_lock);
801
802         }
803         spin_unlock(&files->file_lock);
804 }
805
806 void get_task_comm(char *buf, struct task_struct *tsk)
807 {
808         /* buf must be at least sizeof(tsk->comm) in size */
809         task_lock(tsk);
810         strncpy(buf, tsk->comm, sizeof(tsk->comm));
811         task_unlock(tsk);
812 }
813
814 void set_task_comm(struct task_struct *tsk, char *buf)
815 {
816         task_lock(tsk);
817         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
818         task_unlock(tsk);
819 }
820
821 int flush_old_exec(struct linux_binprm * bprm)
822 {
823         char * name;
824         int i, ch, retval;
825         struct files_struct *files;
826         char tcomm[sizeof(current->comm)];
827
828         /*
829          * Make sure we have a private signal table and that
830          * we are unassociated from the previous thread group.
831          */
832         retval = de_thread(current);
833         if (retval)
834                 goto out;
835
836         /*
837          * Make sure we have private file handles. Ask the
838          * fork helper to do the work for us and the exit
839          * helper to do the cleanup of the old one.
840          */
841         files = current->files;         /* refcounted so safe to hold */
842         retval = unshare_files();
843         if (retval)
844                 goto out;
845         /*
846          * Release all of the old mmap stuff
847          */
848         retval = exec_mmap(bprm->mm);
849         if (retval)
850                 goto mmap_failed;
851
852         bprm->mm = NULL;                /* We're using it now */
853
854         /* This is the point of no return */
855         put_files_struct(files);
856
857         current->sas_ss_sp = current->sas_ss_size = 0;
858
859         if (current->euid == current->uid && current->egid == current->gid)
860                 current->mm->dumpable = 1;
861         else
862                 current->mm->dumpable = suid_dumpable;
863
864         name = bprm->filename;
865
866         /* Copies the binary name from after last slash */
867         for (i=0; (ch = *(name++)) != '\0';) {
868                 if (ch == '/')
869                         i = 0; /* overwrite what we wrote */
870                 else
871                         if (i < (sizeof(tcomm) - 1))
872                                 tcomm[i++] = ch;
873         }
874         tcomm[i] = '\0';
875         set_task_comm(current, tcomm);
876
877         current->flags &= ~PF_RANDOMIZE;
878         flush_thread();
879
880         /* Set the new mm task size. We have to do that late because it may
881          * depend on TIF_32BIT which is only updated in flush_thread() on
882          * some architectures like powerpc
883          */
884         current->mm->task_size = TASK_SIZE;
885
886         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
887             file_permission(bprm->file, MAY_READ) ||
888             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
889                 suid_keys(current);
890                 current->mm->dumpable = suid_dumpable;
891         }
892
893         /* An exec changes our domain. We are no longer part of the thread
894            group */
895
896         current->self_exec_id++;
897                         
898         flush_signal_handlers(current, 0);
899         flush_old_files(current->files);
900
901         return 0;
902
903 mmap_failed:
904         put_files_struct(current->files);
905         current->files = files;
906 out:
907         return retval;
908 }
909
910 EXPORT_SYMBOL(flush_old_exec);
911
912 /* 
913  * Fill the binprm structure from the inode. 
914  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
915  */
916 int prepare_binprm(struct linux_binprm *bprm)
917 {
918         int mode;
919         struct inode * inode = bprm->file->f_dentry->d_inode;
920         int retval;
921
922         mode = inode->i_mode;
923         if (bprm->file->f_op == NULL)
924                 return -EACCES;
925
926         bprm->e_uid = current->euid;
927         bprm->e_gid = current->egid;
928
929         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
930                 /* Set-uid? */
931                 if (mode & S_ISUID) {
932                         current->personality &= ~PER_CLEAR_ON_SETID;
933                         bprm->e_uid = inode->i_uid;
934                 }
935
936                 /* Set-gid? */
937                 /*
938                  * If setgid is set but no group execute bit then this
939                  * is a candidate for mandatory locking, not a setgid
940                  * executable.
941                  */
942                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
943                         current->personality &= ~PER_CLEAR_ON_SETID;
944                         bprm->e_gid = inode->i_gid;
945                 }
946         }
947
948         /* fill in binprm security blob */
949         retval = security_bprm_set(bprm);
950         if (retval)
951                 return retval;
952
953         memset(bprm->buf,0,BINPRM_BUF_SIZE);
954         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
955 }
956
957 EXPORT_SYMBOL(prepare_binprm);
958
959 static int unsafe_exec(struct task_struct *p)
960 {
961         int unsafe = 0;
962         if (p->ptrace & PT_PTRACED) {
963                 if (p->ptrace & PT_PTRACE_CAP)
964                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
965                 else
966                         unsafe |= LSM_UNSAFE_PTRACE;
967         }
968         if (atomic_read(&p->fs->count) > 1 ||
969             atomic_read(&p->files->count) > 1 ||
970             atomic_read(&p->sighand->count) > 1)
971                 unsafe |= LSM_UNSAFE_SHARE;
972
973         return unsafe;
974 }
975
976 void compute_creds(struct linux_binprm *bprm)
977 {
978         int unsafe;
979
980         if (bprm->e_uid != current->uid)
981                 suid_keys(current);
982         exec_keys(current);
983
984         task_lock(current);
985         unsafe = unsafe_exec(current);
986         security_bprm_apply_creds(bprm, unsafe);
987         task_unlock(current);
988         security_bprm_post_apply_creds(bprm);
989 }
990
991 EXPORT_SYMBOL(compute_creds);
992
993 void remove_arg_zero(struct linux_binprm *bprm)
994 {
995         if (bprm->argc) {
996                 unsigned long offset;
997                 char * kaddr;
998                 struct page *page;
999
1000                 offset = bprm->p % PAGE_SIZE;
1001                 goto inside;
1002
1003                 while (bprm->p++, *(kaddr+offset++)) {
1004                         if (offset != PAGE_SIZE)
1005                                 continue;
1006                         offset = 0;
1007                         kunmap_atomic(kaddr, KM_USER0);
1008 inside:
1009                         page = bprm->page[bprm->p/PAGE_SIZE];
1010                         kaddr = kmap_atomic(page, KM_USER0);
1011                 }
1012                 kunmap_atomic(kaddr, KM_USER0);
1013                 bprm->argc--;
1014         }
1015 }
1016
1017 EXPORT_SYMBOL(remove_arg_zero);
1018
1019 /*
1020  * cycle the list of binary formats handler, until one recognizes the image
1021  */
1022 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1023 {
1024         int try,retval;
1025         struct linux_binfmt *fmt;
1026 #ifdef __alpha__
1027         /* handle /sbin/loader.. */
1028         {
1029             struct exec * eh = (struct exec *) bprm->buf;
1030
1031             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1032                 (eh->fh.f_flags & 0x3000) == 0x3000)
1033             {
1034                 struct file * file;
1035                 unsigned long loader;
1036
1037                 allow_write_access(bprm->file);
1038                 fput(bprm->file);
1039                 bprm->file = NULL;
1040
1041                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1042
1043                 file = open_exec("/sbin/loader");
1044                 retval = PTR_ERR(file);
1045                 if (IS_ERR(file))
1046                         return retval;
1047
1048                 /* Remember if the application is TASO.  */
1049                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1050
1051                 bprm->file = file;
1052                 bprm->loader = loader;
1053                 retval = prepare_binprm(bprm);
1054                 if (retval<0)
1055                         return retval;
1056                 /* should call search_binary_handler recursively here,
1057                    but it does not matter */
1058             }
1059         }
1060 #endif
1061         retval = security_bprm_check(bprm);
1062         if (retval)
1063                 return retval;
1064
1065         /* kernel module loader fixup */
1066         /* so we don't try to load run modprobe in kernel space. */
1067         set_fs(USER_DS);
1068
1069         retval = audit_bprm(bprm);
1070         if (retval)
1071                 return retval;
1072
1073         retval = -ENOENT;
1074         for (try=0; try<2; try++) {
1075                 read_lock(&binfmt_lock);
1076                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1077                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1078                         if (!fn)
1079                                 continue;
1080                         if (!try_module_get(fmt->module))
1081                                 continue;
1082                         read_unlock(&binfmt_lock);
1083                         retval = fn(bprm, regs);
1084                         if (retval >= 0) {
1085                                 put_binfmt(fmt);
1086                                 allow_write_access(bprm->file);
1087                                 if (bprm->file)
1088                                         fput(bprm->file);
1089                                 bprm->file = NULL;
1090                                 current->did_exec = 1;
1091                                 proc_exec_connector(current);
1092                                 return retval;
1093                         }
1094                         read_lock(&binfmt_lock);
1095                         put_binfmt(fmt);
1096                         if (retval != -ENOEXEC || bprm->mm == NULL)
1097                                 break;
1098                         if (!bprm->file) {
1099                                 read_unlock(&binfmt_lock);
1100                                 return retval;
1101                         }
1102                 }
1103                 read_unlock(&binfmt_lock);
1104                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1105                         break;
1106 #ifdef CONFIG_KMOD
1107                 }else{
1108 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1109                         if (printable(bprm->buf[0]) &&
1110                             printable(bprm->buf[1]) &&
1111                             printable(bprm->buf[2]) &&
1112                             printable(bprm->buf[3]))
1113                                 break; /* -ENOEXEC */
1114                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1115 #endif
1116                 }
1117         }
1118         return retval;
1119 }
1120
1121 EXPORT_SYMBOL(search_binary_handler);
1122
1123 /*
1124  * sys_execve() executes a new program.
1125  */
1126 int do_execve(char * filename,
1127         char __user *__user *argv,
1128         char __user *__user *envp,
1129         struct pt_regs * regs)
1130 {
1131         struct linux_binprm *bprm;
1132         struct file *file;
1133         int retval;
1134         int i;
1135
1136         retval = -ENOMEM;
1137         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1138         if (!bprm)
1139                 goto out_ret;
1140
1141         file = open_exec(filename);
1142         retval = PTR_ERR(file);
1143         if (IS_ERR(file))
1144                 goto out_kfree;
1145
1146         sched_exec();
1147
1148         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1149
1150         bprm->file = file;
1151         bprm->filename = filename;
1152         bprm->interp = filename;
1153         bprm->mm = mm_alloc();
1154         retval = -ENOMEM;
1155         if (!bprm->mm)
1156                 goto out_file;
1157
1158         retval = init_new_context(current, bprm->mm);
1159         if (retval < 0)
1160                 goto out_mm;
1161
1162         bprm->argc = count(argv, bprm->p / sizeof(void *));
1163         if ((retval = bprm->argc) < 0)
1164                 goto out_mm;
1165
1166         bprm->envc = count(envp, bprm->p / sizeof(void *));
1167         if ((retval = bprm->envc) < 0)
1168                 goto out_mm;
1169
1170         retval = security_bprm_alloc(bprm);
1171         if (retval)
1172                 goto out;
1173
1174         retval = prepare_binprm(bprm);
1175         if (retval < 0)
1176                 goto out;
1177
1178         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1179         if (retval < 0)
1180                 goto out;
1181
1182         bprm->exec = bprm->p;
1183         retval = copy_strings(bprm->envc, envp, bprm);
1184         if (retval < 0)
1185                 goto out;
1186
1187         retval = copy_strings(bprm->argc, argv, bprm);
1188         if (retval < 0)
1189                 goto out;
1190
1191         retval = search_binary_handler(bprm,regs);
1192         if (retval >= 0) {
1193                 free_arg_pages(bprm);
1194
1195                 /* execve success */
1196                 security_bprm_free(bprm);
1197                 acct_update_integrals(current);
1198                 kfree(bprm);
1199                 return retval;
1200         }
1201
1202 out:
1203         /* Something went wrong, return the inode and free the argument pages*/
1204         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1205                 struct page * page = bprm->page[i];
1206                 if (page)
1207                         __free_page(page);
1208         }
1209
1210         if (bprm->security)
1211                 security_bprm_free(bprm);
1212
1213 out_mm:
1214         if (bprm->mm)
1215                 mmdrop(bprm->mm);
1216
1217 out_file:
1218         if (bprm->file) {
1219                 allow_write_access(bprm->file);
1220                 fput(bprm->file);
1221         }
1222
1223 out_kfree:
1224         kfree(bprm);
1225
1226 out_ret:
1227         return retval;
1228 }
1229
1230 int set_binfmt(struct linux_binfmt *new)
1231 {
1232         struct linux_binfmt *old = current->binfmt;
1233
1234         if (new) {
1235                 if (!try_module_get(new->module))
1236                         return -1;
1237         }
1238         current->binfmt = new;
1239         if (old)
1240                 module_put(old->module);
1241         return 0;
1242 }
1243
1244 EXPORT_SYMBOL(set_binfmt);
1245
1246 #define CORENAME_MAX_SIZE 64
1247
1248 /* format_corename will inspect the pattern parameter, and output a
1249  * name into corename, which must have space for at least
1250  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1251  */
1252 static void format_corename(char *corename, const char *pattern, long signr)
1253 {
1254         const char *pat_ptr = pattern;
1255         char *out_ptr = corename;
1256         char *const out_end = corename + CORENAME_MAX_SIZE;
1257         int rc;
1258         int pid_in_pattern = 0;
1259
1260         /* Repeat as long as we have more pattern to process and more output
1261            space */
1262         while (*pat_ptr) {
1263                 if (*pat_ptr != '%') {
1264                         if (out_ptr == out_end)
1265                                 goto out;
1266                         *out_ptr++ = *pat_ptr++;
1267                 } else {
1268                         switch (*++pat_ptr) {
1269                         case 0:
1270                                 goto out;
1271                         /* Double percent, output one percent */
1272                         case '%':
1273                                 if (out_ptr == out_end)
1274                                         goto out;
1275                                 *out_ptr++ = '%';
1276                                 break;
1277                         /* pid */
1278                         case 'p':
1279                                 pid_in_pattern = 1;
1280                                 rc = snprintf(out_ptr, out_end - out_ptr,
1281                                               "%d", current->tgid);
1282                                 if (rc > out_end - out_ptr)
1283                                         goto out;
1284                                 out_ptr += rc;
1285                                 break;
1286                         /* uid */
1287                         case 'u':
1288                                 rc = snprintf(out_ptr, out_end - out_ptr,
1289                                               "%d", current->uid);
1290                                 if (rc > out_end - out_ptr)
1291                                         goto out;
1292                                 out_ptr += rc;
1293                                 break;
1294                         /* gid */
1295                         case 'g':
1296                                 rc = snprintf(out_ptr, out_end - out_ptr,
1297                                               "%d", current->gid);
1298                                 if (rc > out_end - out_ptr)
1299                                         goto out;
1300                                 out_ptr += rc;
1301                                 break;
1302                         /* signal that caused the coredump */
1303                         case 's':
1304                                 rc = snprintf(out_ptr, out_end - out_ptr,
1305                                               "%ld", signr);
1306                                 if (rc > out_end - out_ptr)
1307                                         goto out;
1308                                 out_ptr += rc;
1309                                 break;
1310                         /* UNIX time of coredump */
1311                         case 't': {
1312                                 struct timeval tv;
1313                                 do_gettimeofday(&tv);
1314                                 rc = snprintf(out_ptr, out_end - out_ptr,
1315                                               "%lu", tv.tv_sec);
1316                                 if (rc > out_end - out_ptr)
1317                                         goto out;
1318                                 out_ptr += rc;
1319                                 break;
1320                         }
1321                         /* hostname */
1322                         case 'h':
1323                                 down_read(&uts_sem);
1324                                 rc = snprintf(out_ptr, out_end - out_ptr,
1325                                               "%s", system_utsname.nodename);
1326                                 up_read(&uts_sem);
1327                                 if (rc > out_end - out_ptr)
1328                                         goto out;
1329                                 out_ptr += rc;
1330                                 break;
1331                         /* executable */
1332                         case 'e':
1333                                 rc = snprintf(out_ptr, out_end - out_ptr,
1334                                               "%s", current->comm);
1335                                 if (rc > out_end - out_ptr)
1336                                         goto out;
1337                                 out_ptr += rc;
1338                                 break;
1339                         default:
1340                                 break;
1341                         }
1342                         ++pat_ptr;
1343                 }
1344         }
1345         /* Backward compatibility with core_uses_pid:
1346          *
1347          * If core_pattern does not include a %p (as is the default)
1348          * and core_uses_pid is set, then .%pid will be appended to
1349          * the filename */
1350         if (!pid_in_pattern
1351             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1352                 rc = snprintf(out_ptr, out_end - out_ptr,
1353                               ".%d", current->tgid);
1354                 if (rc > out_end - out_ptr)
1355                         goto out;
1356                 out_ptr += rc;
1357         }
1358       out:
1359         *out_ptr = 0;
1360 }
1361
1362 static void zap_process(struct task_struct *start)
1363 {
1364         struct task_struct *t;
1365
1366         start->signal->flags = SIGNAL_GROUP_EXIT;
1367         start->signal->group_stop_count = 0;
1368
1369         t = start;
1370         do {
1371                 if (t != current && t->mm) {
1372                         t->mm->core_waiters++;
1373                         sigaddset(&t->pending.signal, SIGKILL);
1374                         signal_wake_up(t, 1);
1375                 }
1376         } while ((t = next_thread(t)) != start);
1377 }
1378
1379 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1380                                 int exit_code)
1381 {
1382         struct task_struct *g, *p;
1383         unsigned long flags;
1384         int err = -EAGAIN;
1385
1386         spin_lock_irq(&tsk->sighand->siglock);
1387         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1388                 tsk->signal->group_exit_code = exit_code;
1389                 zap_process(tsk);
1390                 err = 0;
1391         }
1392         spin_unlock_irq(&tsk->sighand->siglock);
1393         if (err)
1394                 return err;
1395
1396         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1397                 goto done;
1398
1399         rcu_read_lock();
1400         for_each_process(g) {
1401                 if (g == tsk->group_leader)
1402                         continue;
1403
1404                 p = g;
1405                 do {
1406                         if (p->mm) {
1407                                 if (p->mm == mm) {
1408                                         /*
1409                                          * p->sighand can't disappear, but
1410                                          * may be changed by de_thread()
1411                                          */
1412                                         lock_task_sighand(p, &flags);
1413                                         zap_process(p);
1414                                         unlock_task_sighand(p, &flags);
1415                                 }
1416                                 break;
1417                         }
1418                 } while ((p = next_thread(p)) != g);
1419         }
1420         rcu_read_unlock();
1421 done:
1422         return mm->core_waiters;
1423 }
1424
1425 static int coredump_wait(int exit_code)
1426 {
1427         struct task_struct *tsk = current;
1428         struct mm_struct *mm = tsk->mm;
1429         struct completion startup_done;
1430         struct completion *vfork_done;
1431         int core_waiters;
1432
1433         init_completion(&mm->core_done);
1434         init_completion(&startup_done);
1435         mm->core_startup_done = &startup_done;
1436
1437         core_waiters = zap_threads(tsk, mm, exit_code);
1438         up_write(&mm->mmap_sem);
1439
1440         if (unlikely(core_waiters < 0))
1441                 goto fail;
1442
1443         /*
1444          * Make sure nobody is waiting for us to release the VM,
1445          * otherwise we can deadlock when we wait on each other
1446          */
1447         vfork_done = tsk->vfork_done;
1448         if (vfork_done) {
1449                 tsk->vfork_done = NULL;
1450                 complete(vfork_done);
1451         }
1452
1453         if (core_waiters)
1454                 wait_for_completion(&startup_done);
1455 fail:
1456         BUG_ON(mm->core_waiters);
1457         return core_waiters;
1458 }
1459
1460 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1461 {
1462         char corename[CORENAME_MAX_SIZE + 1];
1463         struct mm_struct *mm = current->mm;
1464         struct linux_binfmt * binfmt;
1465         struct inode * inode;
1466         struct file * file;
1467         int retval = 0;
1468         int fsuid = current->fsuid;
1469         int flag = 0;
1470
1471         binfmt = current->binfmt;
1472         if (!binfmt || !binfmt->core_dump)
1473                 goto fail;
1474         down_write(&mm->mmap_sem);
1475         if (!mm->dumpable) {
1476                 up_write(&mm->mmap_sem);
1477                 goto fail;
1478         }
1479
1480         /*
1481          *      We cannot trust fsuid as being the "true" uid of the
1482          *      process nor do we know its entire history. We only know it
1483          *      was tainted so we dump it as root in mode 2.
1484          */
1485         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1486                 flag = O_EXCL;          /* Stop rewrite attacks */
1487                 current->fsuid = 0;     /* Dump root private */
1488         }
1489         mm->dumpable = 0;
1490
1491         retval = coredump_wait(exit_code);
1492         if (retval < 0)
1493                 goto fail;
1494
1495         /*
1496          * Clear any false indication of pending signals that might
1497          * be seen by the filesystem code called to write the core file.
1498          */
1499         clear_thread_flag(TIF_SIGPENDING);
1500
1501         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1502                 goto fail_unlock;
1503
1504         /*
1505          * lock_kernel() because format_corename() is controlled by sysctl, which
1506          * uses lock_kernel()
1507          */
1508         lock_kernel();
1509         format_corename(corename, core_pattern, signr);
1510         unlock_kernel();
1511         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1512         if (IS_ERR(file))
1513                 goto fail_unlock;
1514         inode = file->f_dentry->d_inode;
1515         if (inode->i_nlink > 1)
1516                 goto close_fail;        /* multiple links - don't dump */
1517         if (d_unhashed(file->f_dentry))
1518                 goto close_fail;
1519
1520         if (!S_ISREG(inode->i_mode))
1521                 goto close_fail;
1522         if (!file->f_op)
1523                 goto close_fail;
1524         if (!file->f_op->write)
1525                 goto close_fail;
1526         if (do_truncate(file->f_dentry, 0, 0, file) != 0)
1527                 goto close_fail;
1528
1529         retval = binfmt->core_dump(signr, regs, file);
1530
1531         if (retval)
1532                 current->signal->group_exit_code |= 0x80;
1533 close_fail:
1534         filp_close(file, NULL);
1535 fail_unlock:
1536         current->fsuid = fsuid;
1537         complete_all(&mm->core_done);
1538 fail:
1539         return retval;
1540 }