[PATCH] Char: isicom, remove cvs stuff
[linux-2.6] / 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/pid_namespace.h>
42 #include <linux/module.h>
43 #include <linux/namei.h>
44 #include <linux/proc_fs.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/syscalls.h>
49 #include <linux/rmap.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53
54 #include <asm/uaccess.h>
55 #include <asm/mmu_context.h>
56
57 #ifdef CONFIG_KMOD
58 #include <linux/kmod.h>
59 #endif
60
61 int core_uses_pid;
62 char core_pattern[128] = "core";
63 int suid_dumpable = 0;
64
65 EXPORT_SYMBOL(suid_dumpable);
66 /* The maximal length of core_pattern is also specified in sysctl.c */
67
68 static struct linux_binfmt *formats;
69 static DEFINE_RWLOCK(binfmt_lock);
70
71 int register_binfmt(struct linux_binfmt * fmt)
72 {
73         struct linux_binfmt ** tmp = &formats;
74
75         if (!fmt)
76                 return -EINVAL;
77         if (fmt->next)
78                 return -EBUSY;
79         write_lock(&binfmt_lock);
80         while (*tmp) {
81                 if (fmt == *tmp) {
82                         write_unlock(&binfmt_lock);
83                         return -EBUSY;
84                 }
85                 tmp = &(*tmp)->next;
86         }
87         fmt->next = formats;
88         formats = fmt;
89         write_unlock(&binfmt_lock);
90         return 0;       
91 }
92
93 EXPORT_SYMBOL(register_binfmt);
94
95 int unregister_binfmt(struct linux_binfmt * fmt)
96 {
97         struct linux_binfmt ** tmp = &formats;
98
99         write_lock(&binfmt_lock);
100         while (*tmp) {
101                 if (fmt == *tmp) {
102                         *tmp = fmt->next;
103                         write_unlock(&binfmt_lock);
104                         return 0;
105                 }
106                 tmp = &(*tmp)->next;
107         }
108         write_unlock(&binfmt_lock);
109         return -EINVAL;
110 }
111
112 EXPORT_SYMBOL(unregister_binfmt);
113
114 static inline void put_binfmt(struct linux_binfmt * fmt)
115 {
116         module_put(fmt->module);
117 }
118
119 /*
120  * Note that a shared library must be both readable and executable due to
121  * security reasons.
122  *
123  * Also note that we take the address to load from from the file itself.
124  */
125 asmlinkage long sys_uselib(const char __user * library)
126 {
127         struct file * file;
128         struct nameidata nd;
129         int error;
130
131         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
132         if (error)
133                 goto out;
134
135         error = -EINVAL;
136         if (!S_ISREG(nd.dentry->d_inode->i_mode))
137                 goto exit;
138
139         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
140         if (error)
141                 goto exit;
142
143         file = nameidata_to_filp(&nd, O_RDONLY);
144         error = PTR_ERR(file);
145         if (IS_ERR(file))
146                 goto out;
147
148         error = -ENOEXEC;
149         if(file->f_op) {
150                 struct linux_binfmt * fmt;
151
152                 read_lock(&binfmt_lock);
153                 for (fmt = formats ; fmt ; fmt = fmt->next) {
154                         if (!fmt->load_shlib)
155                                 continue;
156                         if (!try_module_get(fmt->module))
157                                 continue;
158                         read_unlock(&binfmt_lock);
159                         error = fmt->load_shlib(file);
160                         read_lock(&binfmt_lock);
161                         put_binfmt(fmt);
162                         if (error != -ENOEXEC)
163                                 break;
164                 }
165                 read_unlock(&binfmt_lock);
166         }
167         fput(file);
168 out:
169         return error;
170 exit:
171         release_open_intent(&nd);
172         path_release(&nd);
173         goto out;
174 }
175
176 /*
177  * count() counts the number of strings in array ARGV.
178  */
179 static int count(char __user * __user * argv, int max)
180 {
181         int i = 0;
182
183         if (argv != NULL) {
184                 for (;;) {
185                         char __user * p;
186
187                         if (get_user(p, argv))
188                                 return -EFAULT;
189                         if (!p)
190                                 break;
191                         argv++;
192                         if(++i > max)
193                                 return -E2BIG;
194                         cond_resched();
195                 }
196         }
197         return i;
198 }
199
200 /*
201  * 'copy_strings()' copies argument/environment strings from user
202  * memory to free pages in kernel mem. These are in a format ready
203  * to be put directly into the top of new user memory.
204  */
205 static int copy_strings(int argc, char __user * __user * argv,
206                         struct linux_binprm *bprm)
207 {
208         struct page *kmapped_page = NULL;
209         char *kaddr = NULL;
210         int ret;
211
212         while (argc-- > 0) {
213                 char __user *str;
214                 int len;
215                 unsigned long pos;
216
217                 if (get_user(str, argv+argc) ||
218                                 !(len = strnlen_user(str, bprm->p))) {
219                         ret = -EFAULT;
220                         goto out;
221                 }
222
223                 if (bprm->p < len)  {
224                         ret = -E2BIG;
225                         goto out;
226                 }
227
228                 bprm->p -= len;
229                 /* XXX: add architecture specific overflow check here. */
230                 pos = bprm->p;
231
232                 while (len > 0) {
233                         int i, new, err;
234                         int offset, bytes_to_copy;
235                         struct page *page;
236
237                         offset = pos % PAGE_SIZE;
238                         i = pos/PAGE_SIZE;
239                         page = bprm->page[i];
240                         new = 0;
241                         if (!page) {
242                                 page = alloc_page(GFP_HIGHUSER);
243                                 bprm->page[i] = page;
244                                 if (!page) {
245                                         ret = -ENOMEM;
246                                         goto out;
247                                 }
248                                 new = 1;
249                         }
250
251                         if (page != kmapped_page) {
252                                 if (kmapped_page)
253                                         kunmap(kmapped_page);
254                                 kmapped_page = page;
255                                 kaddr = kmap(kmapped_page);
256                         }
257                         if (new && offset)
258                                 memset(kaddr, 0, offset);
259                         bytes_to_copy = PAGE_SIZE - offset;
260                         if (bytes_to_copy > len) {
261                                 bytes_to_copy = len;
262                                 if (new)
263                                         memset(kaddr+offset+len, 0,
264                                                 PAGE_SIZE-offset-len);
265                         }
266                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
267                         if (err) {
268                                 ret = -EFAULT;
269                                 goto out;
270                         }
271
272                         pos += bytes_to_copy;
273                         str += bytes_to_copy;
274                         len -= bytes_to_copy;
275                 }
276         }
277         ret = 0;
278 out:
279         if (kmapped_page)
280                 kunmap(kmapped_page);
281         return ret;
282 }
283
284 /*
285  * Like copy_strings, but get argv and its values from kernel memory.
286  */
287 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
288 {
289         int r;
290         mm_segment_t oldfs = get_fs();
291         set_fs(KERNEL_DS);
292         r = copy_strings(argc, (char __user * __user *)argv, bprm);
293         set_fs(oldfs);
294         return r;
295 }
296
297 EXPORT_SYMBOL(copy_strings_kernel);
298
299 #ifdef CONFIG_MMU
300 /*
301  * This routine is used to map in a page into an address space: needed by
302  * execve() for the initial stack and environment pages.
303  *
304  * vma->vm_mm->mmap_sem is held for writing.
305  */
306 void install_arg_page(struct vm_area_struct *vma,
307                         struct page *page, unsigned long address)
308 {
309         struct mm_struct *mm = vma->vm_mm;
310         pte_t * pte;
311         spinlock_t *ptl;
312
313         if (unlikely(anon_vma_prepare(vma)))
314                 goto out;
315
316         flush_dcache_page(page);
317         pte = get_locked_pte(mm, address, &ptl);
318         if (!pte)
319                 goto out;
320         if (!pte_none(*pte)) {
321                 pte_unmap_unlock(pte, ptl);
322                 goto out;
323         }
324         inc_mm_counter(mm, anon_rss);
325         lru_cache_add_active(page);
326         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
327                                         page, vma->vm_page_prot))));
328         page_add_new_anon_rmap(page, vma, address);
329         pte_unmap_unlock(pte, ptl);
330
331         /* no need for flush_tlb */
332         return;
333 out:
334         __free_page(page);
335         force_sig(SIGKILL, current);
336 }
337
338 #define EXTRA_STACK_VM_PAGES    20      /* random */
339
340 int setup_arg_pages(struct linux_binprm *bprm,
341                     unsigned long stack_top,
342                     int executable_stack)
343 {
344         unsigned long stack_base;
345         struct vm_area_struct *mpnt;
346         struct mm_struct *mm = current->mm;
347         int i, ret;
348         long arg_size;
349
350 #ifdef CONFIG_STACK_GROWSUP
351         /* Move the argument and environment strings to the bottom of the
352          * stack space.
353          */
354         int offset, j;
355         char *to, *from;
356
357         /* Start by shifting all the pages down */
358         i = 0;
359         for (j = 0; j < MAX_ARG_PAGES; j++) {
360                 struct page *page = bprm->page[j];
361                 if (!page)
362                         continue;
363                 bprm->page[i++] = page;
364         }
365
366         /* Now move them within their pages */
367         offset = bprm->p % PAGE_SIZE;
368         to = kmap(bprm->page[0]);
369         for (j = 1; j < i; j++) {
370                 memmove(to, to + offset, PAGE_SIZE - offset);
371                 from = kmap(bprm->page[j]);
372                 memcpy(to + PAGE_SIZE - offset, from, offset);
373                 kunmap(bprm->page[j - 1]);
374                 to = from;
375         }
376         memmove(to, to + offset, PAGE_SIZE - offset);
377         kunmap(bprm->page[j - 1]);
378
379         /* Limit stack size to 1GB */
380         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
381         if (stack_base > (1 << 30))
382                 stack_base = 1 << 30;
383         stack_base = PAGE_ALIGN(stack_top - stack_base);
384
385         /* Adjust bprm->p to point to the end of the strings. */
386         bprm->p = stack_base + PAGE_SIZE * i - offset;
387
388         mm->arg_start = stack_base;
389         arg_size = i << PAGE_SHIFT;
390
391         /* zero pages that were copied above */
392         while (i < MAX_ARG_PAGES)
393                 bprm->page[i++] = NULL;
394 #else
395         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
396         stack_base = PAGE_ALIGN(stack_base);
397         bprm->p += stack_base;
398         mm->arg_start = bprm->p;
399         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
400 #endif
401
402         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
403
404         if (bprm->loader)
405                 bprm->loader += stack_base;
406         bprm->exec += stack_base;
407
408         mpnt = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
409         if (!mpnt)
410                 return -ENOMEM;
411
412         memset(mpnt, 0, sizeof(*mpnt));
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          * If we don't share sighandlers, then we aren't sharing anything
587          * and we can just re-use it all.
588          */
589         if (atomic_read(&oldsighand->count) <= 1) {
590                 BUG_ON(atomic_read(&sig->count) != 1);
591                 exit_itimers(sig);
592                 return 0;
593         }
594
595         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
596         if (!newsighand)
597                 return -ENOMEM;
598
599         if (thread_group_empty(tsk))
600                 goto no_thread_group;
601
602         /*
603          * Kill all other threads in the thread group.
604          * We must hold tasklist_lock to call zap_other_threads.
605          */
606         read_lock(&tasklist_lock);
607         spin_lock_irq(lock);
608         if (sig->flags & SIGNAL_GROUP_EXIT) {
609                 /*
610                  * Another group action in progress, just
611                  * return so that the signal is processed.
612                  */
613                 spin_unlock_irq(lock);
614                 read_unlock(&tasklist_lock);
615                 kmem_cache_free(sighand_cachep, newsighand);
616                 return -EAGAIN;
617         }
618
619         /*
620          * child_reaper ignores SIGKILL, change it now.
621          * Reparenting needs write_lock on tasklist_lock,
622          * so it is safe to do it under read_lock.
623          */
624         if (unlikely(tsk->group_leader == child_reaper(tsk)))
625                 tsk->nsproxy->pid_ns->child_reaper = tsk;
626
627         zap_other_threads(tsk);
628         read_unlock(&tasklist_lock);
629
630         /*
631          * Account for the thread group leader hanging around:
632          */
633         count = 1;
634         if (!thread_group_leader(tsk)) {
635                 count = 2;
636                 /*
637                  * The SIGALRM timer survives the exec, but needs to point
638                  * at us as the new group leader now.  We have a race with
639                  * a timer firing now getting the old leader, so we need to
640                  * synchronize with any firing (by calling del_timer_sync)
641                  * before we can safely let the old group leader die.
642                  */
643                 sig->tsk = tsk;
644                 spin_unlock_irq(lock);
645                 if (hrtimer_cancel(&sig->real_timer))
646                         hrtimer_restart(&sig->real_timer);
647                 spin_lock_irq(lock);
648         }
649         while (atomic_read(&sig->count) > count) {
650                 sig->group_exit_task = tsk;
651                 sig->notify_count = count;
652                 __set_current_state(TASK_UNINTERRUPTIBLE);
653                 spin_unlock_irq(lock);
654                 schedule();
655                 spin_lock_irq(lock);
656         }
657         sig->group_exit_task = NULL;
658         sig->notify_count = 0;
659         spin_unlock_irq(lock);
660
661         /*
662          * At this point all other threads have exited, all we have to
663          * do is to wait for the thread group leader to become inactive,
664          * and to assume its PID:
665          */
666         if (!thread_group_leader(tsk)) {
667                 /*
668                  * Wait for the thread group leader to be a zombie.
669                  * It should already be zombie at this point, most
670                  * of the time.
671                  */
672                 leader = tsk->group_leader;
673                 while (leader->exit_state != EXIT_ZOMBIE)
674                         yield();
675
676                 /*
677                  * The only record we have of the real-time age of a
678                  * process, regardless of execs it's done, is start_time.
679                  * All the past CPU time is accumulated in signal_struct
680                  * from sister threads now dead.  But in this non-leader
681                  * exec, nothing survives from the original leader thread,
682                  * whose birth marks the true age of this process now.
683                  * When we take on its identity by switching to its PID, we
684                  * also take its birthdate (always earlier than our own).
685                  */
686                 tsk->start_time = leader->start_time;
687
688                 write_lock_irq(&tasklist_lock);
689
690                 BUG_ON(leader->tgid != tsk->tgid);
691                 BUG_ON(tsk->pid == tsk->tgid);
692                 /*
693                  * An exec() starts a new thread group with the
694                  * TGID of the previous thread group. Rehash the
695                  * two threads with a switched PID, and release
696                  * the former thread group leader:
697                  */
698
699                 /* Become a process group leader with the old leader's pid.
700                  * The old leader becomes a thread of the this thread group.
701                  * Note: The old leader also uses this pid until release_task
702                  *       is called.  Odd but simple and correct.
703                  */
704                 detach_pid(tsk, PIDTYPE_PID);
705                 tsk->pid = leader->pid;
706                 attach_pid(tsk, PIDTYPE_PID,  tsk->pid);
707                 transfer_pid(leader, tsk, PIDTYPE_PGID);
708                 transfer_pid(leader, tsk, PIDTYPE_SID);
709                 list_replace_rcu(&leader->tasks, &tsk->tasks);
710
711                 tsk->group_leader = tsk;
712                 leader->group_leader = tsk;
713
714                 tsk->exit_signal = SIGCHLD;
715
716                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
717                 leader->exit_state = EXIT_DEAD;
718
719                 write_unlock_irq(&tasklist_lock);
720         }
721
722         /*
723          * There may be one thread left which is just exiting,
724          * but it's safe to stop telling the group to kill themselves.
725          */
726         sig->flags = 0;
727
728 no_thread_group:
729         exit_itimers(sig);
730         if (leader)
731                 release_task(leader);
732
733         BUG_ON(atomic_read(&sig->count) != 1);
734
735         if (atomic_read(&oldsighand->count) == 1) {
736                 /*
737                  * Now that we nuked the rest of the thread group,
738                  * it turns out we are not sharing sighand any more either.
739                  * So we can just keep it.
740                  */
741                 kmem_cache_free(sighand_cachep, newsighand);
742         } else {
743                 /*
744                  * Move our state over to newsighand and switch it in.
745                  */
746                 atomic_set(&newsighand->count, 1);
747                 memcpy(newsighand->action, oldsighand->action,
748                        sizeof(newsighand->action));
749
750                 write_lock_irq(&tasklist_lock);
751                 spin_lock(&oldsighand->siglock);
752                 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
753
754                 rcu_assign_pointer(tsk->sighand, newsighand);
755                 recalc_sigpending();
756
757                 spin_unlock(&newsighand->siglock);
758                 spin_unlock(&oldsighand->siglock);
759                 write_unlock_irq(&tasklist_lock);
760
761                 if (atomic_dec_and_test(&oldsighand->count))
762                         kmem_cache_free(sighand_cachep, oldsighand);
763         }
764
765         BUG_ON(!thread_group_leader(tsk));
766         return 0;
767 }
768         
769 /*
770  * These functions flushes out all traces of the currently running executable
771  * so that a new one can be started
772  */
773
774 static void flush_old_files(struct files_struct * files)
775 {
776         long j = -1;
777         struct fdtable *fdt;
778
779         spin_lock(&files->file_lock);
780         for (;;) {
781                 unsigned long set, i;
782
783                 j++;
784                 i = j * __NFDBITS;
785                 fdt = files_fdtable(files);
786                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
787                         break;
788                 set = fdt->close_on_exec->fds_bits[j];
789                 if (!set)
790                         continue;
791                 fdt->close_on_exec->fds_bits[j] = 0;
792                 spin_unlock(&files->file_lock);
793                 for ( ; set ; i++,set >>= 1) {
794                         if (set & 1) {
795                                 sys_close(i);
796                         }
797                 }
798                 spin_lock(&files->file_lock);
799
800         }
801         spin_unlock(&files->file_lock);
802 }
803
804 void get_task_comm(char *buf, struct task_struct *tsk)
805 {
806         /* buf must be at least sizeof(tsk->comm) in size */
807         task_lock(tsk);
808         strncpy(buf, tsk->comm, sizeof(tsk->comm));
809         task_unlock(tsk);
810 }
811
812 void set_task_comm(struct task_struct *tsk, char *buf)
813 {
814         task_lock(tsk);
815         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
816         task_unlock(tsk);
817 }
818
819 int flush_old_exec(struct linux_binprm * bprm)
820 {
821         char * name;
822         int i, ch, retval;
823         struct files_struct *files;
824         char tcomm[sizeof(current->comm)];
825
826         /*
827          * Make sure we have a private signal table and that
828          * we are unassociated from the previous thread group.
829          */
830         retval = de_thread(current);
831         if (retval)
832                 goto out;
833
834         /*
835          * Make sure we have private file handles. Ask the
836          * fork helper to do the work for us and the exit
837          * helper to do the cleanup of the old one.
838          */
839         files = current->files;         /* refcounted so safe to hold */
840         retval = unshare_files();
841         if (retval)
842                 goto out;
843         /*
844          * Release all of the old mmap stuff
845          */
846         retval = exec_mmap(bprm->mm);
847         if (retval)
848                 goto mmap_failed;
849
850         bprm->mm = NULL;                /* We're using it now */
851
852         /* This is the point of no return */
853         put_files_struct(files);
854
855         current->sas_ss_sp = current->sas_ss_size = 0;
856
857         if (current->euid == current->uid && current->egid == current->gid)
858                 current->mm->dumpable = 1;
859         else
860                 current->mm->dumpable = suid_dumpable;
861
862         name = bprm->filename;
863
864         /* Copies the binary name from after last slash */
865         for (i=0; (ch = *(name++)) != '\0';) {
866                 if (ch == '/')
867                         i = 0; /* overwrite what we wrote */
868                 else
869                         if (i < (sizeof(tcomm) - 1))
870                                 tcomm[i++] = ch;
871         }
872         tcomm[i] = '\0';
873         set_task_comm(current, tcomm);
874
875         current->flags &= ~PF_RANDOMIZE;
876         flush_thread();
877
878         /* Set the new mm task size. We have to do that late because it may
879          * depend on TIF_32BIT which is only updated in flush_thread() on
880          * some architectures like powerpc
881          */
882         current->mm->task_size = TASK_SIZE;
883
884         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
885             file_permission(bprm->file, MAY_READ) ||
886             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
887                 suid_keys(current);
888                 current->mm->dumpable = suid_dumpable;
889         }
890
891         /* An exec changes our domain. We are no longer part of the thread
892            group */
893
894         current->self_exec_id++;
895                         
896         flush_signal_handlers(current, 0);
897         flush_old_files(current->files);
898
899         return 0;
900
901 mmap_failed:
902         reset_files_struct(current, files);
903 out:
904         return retval;
905 }
906
907 EXPORT_SYMBOL(flush_old_exec);
908
909 /* 
910  * Fill the binprm structure from the inode. 
911  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
912  */
913 int prepare_binprm(struct linux_binprm *bprm)
914 {
915         int mode;
916         struct inode * inode = bprm->file->f_path.dentry->d_inode;
917         int retval;
918
919         mode = inode->i_mode;
920         if (bprm->file->f_op == NULL)
921                 return -EACCES;
922
923         bprm->e_uid = current->euid;
924         bprm->e_gid = current->egid;
925
926         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
927                 /* Set-uid? */
928                 if (mode & S_ISUID) {
929                         current->personality &= ~PER_CLEAR_ON_SETID;
930                         bprm->e_uid = inode->i_uid;
931                 }
932
933                 /* Set-gid? */
934                 /*
935                  * If setgid is set but no group execute bit then this
936                  * is a candidate for mandatory locking, not a setgid
937                  * executable.
938                  */
939                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
940                         current->personality &= ~PER_CLEAR_ON_SETID;
941                         bprm->e_gid = inode->i_gid;
942                 }
943         }
944
945         /* fill in binprm security blob */
946         retval = security_bprm_set(bprm);
947         if (retval)
948                 return retval;
949
950         memset(bprm->buf,0,BINPRM_BUF_SIZE);
951         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
952 }
953
954 EXPORT_SYMBOL(prepare_binprm);
955
956 static int unsafe_exec(struct task_struct *p)
957 {
958         int unsafe = 0;
959         if (p->ptrace & PT_PTRACED) {
960                 if (p->ptrace & PT_PTRACE_CAP)
961                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
962                 else
963                         unsafe |= LSM_UNSAFE_PTRACE;
964         }
965         if (atomic_read(&p->fs->count) > 1 ||
966             atomic_read(&p->files->count) > 1 ||
967             atomic_read(&p->sighand->count) > 1)
968                 unsafe |= LSM_UNSAFE_SHARE;
969
970         return unsafe;
971 }
972
973 void compute_creds(struct linux_binprm *bprm)
974 {
975         int unsafe;
976
977         if (bprm->e_uid != current->uid)
978                 suid_keys(current);
979         exec_keys(current);
980
981         task_lock(current);
982         unsafe = unsafe_exec(current);
983         security_bprm_apply_creds(bprm, unsafe);
984         task_unlock(current);
985         security_bprm_post_apply_creds(bprm);
986 }
987
988 EXPORT_SYMBOL(compute_creds);
989
990 void remove_arg_zero(struct linux_binprm *bprm)
991 {
992         if (bprm->argc) {
993                 unsigned long offset;
994                 char * kaddr;
995                 struct page *page;
996
997                 offset = bprm->p % PAGE_SIZE;
998                 goto inside;
999
1000                 while (bprm->p++, *(kaddr+offset++)) {
1001                         if (offset != PAGE_SIZE)
1002                                 continue;
1003                         offset = 0;
1004                         kunmap_atomic(kaddr, KM_USER0);
1005 inside:
1006                         page = bprm->page[bprm->p/PAGE_SIZE];
1007                         kaddr = kmap_atomic(page, KM_USER0);
1008                 }
1009                 kunmap_atomic(kaddr, KM_USER0);
1010                 bprm->argc--;
1011         }
1012 }
1013
1014 EXPORT_SYMBOL(remove_arg_zero);
1015
1016 /*
1017  * cycle the list of binary formats handler, until one recognizes the image
1018  */
1019 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1020 {
1021         int try,retval;
1022         struct linux_binfmt *fmt;
1023 #ifdef __alpha__
1024         /* handle /sbin/loader.. */
1025         {
1026             struct exec * eh = (struct exec *) bprm->buf;
1027
1028             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1029                 (eh->fh.f_flags & 0x3000) == 0x3000)
1030             {
1031                 struct file * file;
1032                 unsigned long loader;
1033
1034                 allow_write_access(bprm->file);
1035                 fput(bprm->file);
1036                 bprm->file = NULL;
1037
1038                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1039
1040                 file = open_exec("/sbin/loader");
1041                 retval = PTR_ERR(file);
1042                 if (IS_ERR(file))
1043                         return retval;
1044
1045                 /* Remember if the application is TASO.  */
1046                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1047
1048                 bprm->file = file;
1049                 bprm->loader = loader;
1050                 retval = prepare_binprm(bprm);
1051                 if (retval<0)
1052                         return retval;
1053                 /* should call search_binary_handler recursively here,
1054                    but it does not matter */
1055             }
1056         }
1057 #endif
1058         retval = security_bprm_check(bprm);
1059         if (retval)
1060                 return retval;
1061
1062         /* kernel module loader fixup */
1063         /* so we don't try to load run modprobe in kernel space. */
1064         set_fs(USER_DS);
1065
1066         retval = audit_bprm(bprm);
1067         if (retval)
1068                 return retval;
1069
1070         retval = -ENOENT;
1071         for (try=0; try<2; try++) {
1072                 read_lock(&binfmt_lock);
1073                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1074                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1075                         if (!fn)
1076                                 continue;
1077                         if (!try_module_get(fmt->module))
1078                                 continue;
1079                         read_unlock(&binfmt_lock);
1080                         retval = fn(bprm, regs);
1081                         if (retval >= 0) {
1082                                 put_binfmt(fmt);
1083                                 allow_write_access(bprm->file);
1084                                 if (bprm->file)
1085                                         fput(bprm->file);
1086                                 bprm->file = NULL;
1087                                 current->did_exec = 1;
1088                                 proc_exec_connector(current);
1089                                 return retval;
1090                         }
1091                         read_lock(&binfmt_lock);
1092                         put_binfmt(fmt);
1093                         if (retval != -ENOEXEC || bprm->mm == NULL)
1094                                 break;
1095                         if (!bprm->file) {
1096                                 read_unlock(&binfmt_lock);
1097                                 return retval;
1098                         }
1099                 }
1100                 read_unlock(&binfmt_lock);
1101                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1102                         break;
1103 #ifdef CONFIG_KMOD
1104                 }else{
1105 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1106                         if (printable(bprm->buf[0]) &&
1107                             printable(bprm->buf[1]) &&
1108                             printable(bprm->buf[2]) &&
1109                             printable(bprm->buf[3]))
1110                                 break; /* -ENOEXEC */
1111                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1112 #endif
1113                 }
1114         }
1115         return retval;
1116 }
1117
1118 EXPORT_SYMBOL(search_binary_handler);
1119
1120 /*
1121  * sys_execve() executes a new program.
1122  */
1123 int do_execve(char * filename,
1124         char __user *__user *argv,
1125         char __user *__user *envp,
1126         struct pt_regs * regs)
1127 {
1128         struct linux_binprm *bprm;
1129         struct file *file;
1130         int retval;
1131         int i;
1132
1133         retval = -ENOMEM;
1134         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1135         if (!bprm)
1136                 goto out_ret;
1137
1138         file = open_exec(filename);
1139         retval = PTR_ERR(file);
1140         if (IS_ERR(file))
1141                 goto out_kfree;
1142
1143         sched_exec();
1144
1145         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1146
1147         bprm->file = file;
1148         bprm->filename = filename;
1149         bprm->interp = filename;
1150         bprm->mm = mm_alloc();
1151         retval = -ENOMEM;
1152         if (!bprm->mm)
1153                 goto out_file;
1154
1155         retval = init_new_context(current, bprm->mm);
1156         if (retval < 0)
1157                 goto out_mm;
1158
1159         bprm->argc = count(argv, bprm->p / sizeof(void *));
1160         if ((retval = bprm->argc) < 0)
1161                 goto out_mm;
1162
1163         bprm->envc = count(envp, bprm->p / sizeof(void *));
1164         if ((retval = bprm->envc) < 0)
1165                 goto out_mm;
1166
1167         retval = security_bprm_alloc(bprm);
1168         if (retval)
1169                 goto out;
1170
1171         retval = prepare_binprm(bprm);
1172         if (retval < 0)
1173                 goto out;
1174
1175         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1176         if (retval < 0)
1177                 goto out;
1178
1179         bprm->exec = bprm->p;
1180         retval = copy_strings(bprm->envc, envp, bprm);
1181         if (retval < 0)
1182                 goto out;
1183
1184         retval = copy_strings(bprm->argc, argv, bprm);
1185         if (retval < 0)
1186                 goto out;
1187
1188         retval = search_binary_handler(bprm,regs);
1189         if (retval >= 0) {
1190                 free_arg_pages(bprm);
1191
1192                 /* execve success */
1193                 security_bprm_free(bprm);
1194                 acct_update_integrals(current);
1195                 kfree(bprm);
1196                 return retval;
1197         }
1198
1199 out:
1200         /* Something went wrong, return the inode and free the argument pages*/
1201         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1202                 struct page * page = bprm->page[i];
1203                 if (page)
1204                         __free_page(page);
1205         }
1206
1207         if (bprm->security)
1208                 security_bprm_free(bprm);
1209
1210 out_mm:
1211         if (bprm->mm)
1212                 mmdrop(bprm->mm);
1213
1214 out_file:
1215         if (bprm->file) {
1216                 allow_write_access(bprm->file);
1217                 fput(bprm->file);
1218         }
1219
1220 out_kfree:
1221         kfree(bprm);
1222
1223 out_ret:
1224         return retval;
1225 }
1226
1227 int set_binfmt(struct linux_binfmt *new)
1228 {
1229         struct linux_binfmt *old = current->binfmt;
1230
1231         if (new) {
1232                 if (!try_module_get(new->module))
1233                         return -1;
1234         }
1235         current->binfmt = new;
1236         if (old)
1237                 module_put(old->module);
1238         return 0;
1239 }
1240
1241 EXPORT_SYMBOL(set_binfmt);
1242
1243 #define CORENAME_MAX_SIZE 64
1244
1245 /* format_corename will inspect the pattern parameter, and output a
1246  * name into corename, which must have space for at least
1247  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1248  */
1249 static void format_corename(char *corename, const char *pattern, long signr)
1250 {
1251         const char *pat_ptr = pattern;
1252         char *out_ptr = corename;
1253         char *const out_end = corename + CORENAME_MAX_SIZE;
1254         int rc;
1255         int pid_in_pattern = 0;
1256
1257         /* Repeat as long as we have more pattern to process and more output
1258            space */
1259         while (*pat_ptr) {
1260                 if (*pat_ptr != '%') {
1261                         if (out_ptr == out_end)
1262                                 goto out;
1263                         *out_ptr++ = *pat_ptr++;
1264                 } else {
1265                         switch (*++pat_ptr) {
1266                         case 0:
1267                                 goto out;
1268                         /* Double percent, output one percent */
1269                         case '%':
1270                                 if (out_ptr == out_end)
1271                                         goto out;
1272                                 *out_ptr++ = '%';
1273                                 break;
1274                         /* pid */
1275                         case 'p':
1276                                 pid_in_pattern = 1;
1277                                 rc = snprintf(out_ptr, out_end - out_ptr,
1278                                               "%d", current->tgid);
1279                                 if (rc > out_end - out_ptr)
1280                                         goto out;
1281                                 out_ptr += rc;
1282                                 break;
1283                         /* uid */
1284                         case 'u':
1285                                 rc = snprintf(out_ptr, out_end - out_ptr,
1286                                               "%d", current->uid);
1287                                 if (rc > out_end - out_ptr)
1288                                         goto out;
1289                                 out_ptr += rc;
1290                                 break;
1291                         /* gid */
1292                         case 'g':
1293                                 rc = snprintf(out_ptr, out_end - out_ptr,
1294                                               "%d", current->gid);
1295                                 if (rc > out_end - out_ptr)
1296                                         goto out;
1297                                 out_ptr += rc;
1298                                 break;
1299                         /* signal that caused the coredump */
1300                         case 's':
1301                                 rc = snprintf(out_ptr, out_end - out_ptr,
1302                                               "%ld", signr);
1303                                 if (rc > out_end - out_ptr)
1304                                         goto out;
1305                                 out_ptr += rc;
1306                                 break;
1307                         /* UNIX time of coredump */
1308                         case 't': {
1309                                 struct timeval tv;
1310                                 do_gettimeofday(&tv);
1311                                 rc = snprintf(out_ptr, out_end - out_ptr,
1312                                               "%lu", tv.tv_sec);
1313                                 if (rc > out_end - out_ptr)
1314                                         goto out;
1315                                 out_ptr += rc;
1316                                 break;
1317                         }
1318                         /* hostname */
1319                         case 'h':
1320                                 down_read(&uts_sem);
1321                                 rc = snprintf(out_ptr, out_end - out_ptr,
1322                                               "%s", utsname()->nodename);
1323                                 up_read(&uts_sem);
1324                                 if (rc > out_end - out_ptr)
1325                                         goto out;
1326                                 out_ptr += rc;
1327                                 break;
1328                         /* executable */
1329                         case 'e':
1330                                 rc = snprintf(out_ptr, out_end - out_ptr,
1331                                               "%s", current->comm);
1332                                 if (rc > out_end - out_ptr)
1333                                         goto out;
1334                                 out_ptr += rc;
1335                                 break;
1336                         default:
1337                                 break;
1338                         }
1339                         ++pat_ptr;
1340                 }
1341         }
1342         /* Backward compatibility with core_uses_pid:
1343          *
1344          * If core_pattern does not include a %p (as is the default)
1345          * and core_uses_pid is set, then .%pid will be appended to
1346          * the filename */
1347         if (!pid_in_pattern
1348             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1349                 rc = snprintf(out_ptr, out_end - out_ptr,
1350                               ".%d", current->tgid);
1351                 if (rc > out_end - out_ptr)
1352                         goto out;
1353                 out_ptr += rc;
1354         }
1355       out:
1356         *out_ptr = 0;
1357 }
1358
1359 static void zap_process(struct task_struct *start)
1360 {
1361         struct task_struct *t;
1362
1363         start->signal->flags = SIGNAL_GROUP_EXIT;
1364         start->signal->group_stop_count = 0;
1365
1366         t = start;
1367         do {
1368                 if (t != current && t->mm) {
1369                         t->mm->core_waiters++;
1370                         sigaddset(&t->pending.signal, SIGKILL);
1371                         signal_wake_up(t, 1);
1372                 }
1373         } while ((t = next_thread(t)) != start);
1374 }
1375
1376 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1377                                 int exit_code)
1378 {
1379         struct task_struct *g, *p;
1380         unsigned long flags;
1381         int err = -EAGAIN;
1382
1383         spin_lock_irq(&tsk->sighand->siglock);
1384         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1385                 tsk->signal->group_exit_code = exit_code;
1386                 zap_process(tsk);
1387                 err = 0;
1388         }
1389         spin_unlock_irq(&tsk->sighand->siglock);
1390         if (err)
1391                 return err;
1392
1393         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1394                 goto done;
1395
1396         rcu_read_lock();
1397         for_each_process(g) {
1398                 if (g == tsk->group_leader)
1399                         continue;
1400
1401                 p = g;
1402                 do {
1403                         if (p->mm) {
1404                                 if (p->mm == mm) {
1405                                         /*
1406                                          * p->sighand can't disappear, but
1407                                          * may be changed by de_thread()
1408                                          */
1409                                         lock_task_sighand(p, &flags);
1410                                         zap_process(p);
1411                                         unlock_task_sighand(p, &flags);
1412                                 }
1413                                 break;
1414                         }
1415                 } while ((p = next_thread(p)) != g);
1416         }
1417         rcu_read_unlock();
1418 done:
1419         return mm->core_waiters;
1420 }
1421
1422 static int coredump_wait(int exit_code)
1423 {
1424         struct task_struct *tsk = current;
1425         struct mm_struct *mm = tsk->mm;
1426         struct completion startup_done;
1427         struct completion *vfork_done;
1428         int core_waiters;
1429
1430         init_completion(&mm->core_done);
1431         init_completion(&startup_done);
1432         mm->core_startup_done = &startup_done;
1433
1434         core_waiters = zap_threads(tsk, mm, exit_code);
1435         up_write(&mm->mmap_sem);
1436
1437         if (unlikely(core_waiters < 0))
1438                 goto fail;
1439
1440         /*
1441          * Make sure nobody is waiting for us to release the VM,
1442          * otherwise we can deadlock when we wait on each other
1443          */
1444         vfork_done = tsk->vfork_done;
1445         if (vfork_done) {
1446                 tsk->vfork_done = NULL;
1447                 complete(vfork_done);
1448         }
1449
1450         if (core_waiters)
1451                 wait_for_completion(&startup_done);
1452 fail:
1453         BUG_ON(mm->core_waiters);
1454         return core_waiters;
1455 }
1456
1457 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1458 {
1459         char corename[CORENAME_MAX_SIZE + 1];
1460         struct mm_struct *mm = current->mm;
1461         struct linux_binfmt * binfmt;
1462         struct inode * inode;
1463         struct file * file;
1464         int retval = 0;
1465         int fsuid = current->fsuid;
1466         int flag = 0;
1467         int ispipe = 0;
1468
1469         binfmt = current->binfmt;
1470         if (!binfmt || !binfmt->core_dump)
1471                 goto fail;
1472         down_write(&mm->mmap_sem);
1473         if (!mm->dumpable) {
1474                 up_write(&mm->mmap_sem);
1475                 goto fail;
1476         }
1477
1478         /*
1479          *      We cannot trust fsuid as being the "true" uid of the
1480          *      process nor do we know its entire history. We only know it
1481          *      was tainted so we dump it as root in mode 2.
1482          */
1483         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1484                 flag = O_EXCL;          /* Stop rewrite attacks */
1485                 current->fsuid = 0;     /* Dump root private */
1486         }
1487         mm->dumpable = 0;
1488
1489         retval = coredump_wait(exit_code);
1490         if (retval < 0)
1491                 goto fail;
1492
1493         /*
1494          * Clear any false indication of pending signals that might
1495          * be seen by the filesystem code called to write the core file.
1496          */
1497         clear_thread_flag(TIF_SIGPENDING);
1498
1499         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1500                 goto fail_unlock;
1501
1502         /*
1503          * lock_kernel() because format_corename() is controlled by sysctl, which
1504          * uses lock_kernel()
1505          */
1506         lock_kernel();
1507         format_corename(corename, core_pattern, signr);
1508         unlock_kernel();
1509         if (corename[0] == '|') {
1510                 /* SIGPIPE can happen, but it's just never processed */
1511                 if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1512                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1513                                corename);
1514                         goto fail_unlock;
1515                 }
1516                 ispipe = 1;
1517         } else
1518                 file = filp_open(corename,
1519                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1520                                  0600);
1521         if (IS_ERR(file))
1522                 goto fail_unlock;
1523         inode = file->f_path.dentry->d_inode;
1524         if (inode->i_nlink > 1)
1525                 goto close_fail;        /* multiple links - don't dump */
1526         if (!ispipe && d_unhashed(file->f_path.dentry))
1527                 goto close_fail;
1528
1529         /* AK: actually i see no reason to not allow this for named pipes etc.,
1530            but keep the previous behaviour for now. */
1531         if (!ispipe && !S_ISREG(inode->i_mode))
1532                 goto close_fail;
1533         if (!file->f_op)
1534                 goto close_fail;
1535         if (!file->f_op->write)
1536                 goto close_fail;
1537         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1538                 goto close_fail;
1539
1540         retval = binfmt->core_dump(signr, regs, file);
1541
1542         if (retval)
1543                 current->signal->group_exit_code |= 0x80;
1544 close_fail:
1545         filp_close(file, NULL);
1546 fail_unlock:
1547         current->fsuid = fsuid;
1548         complete_all(&mm->core_done);
1549 fail:
1550         return retval;
1551 }