a6f64a98ac508a5d29da37f30988e83ef7b1ec9c
[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                         if (!err && !(inode->i_mode & 0111))
490                                 err = -EACCES;
491                         file = ERR_PTR(err);
492                         if (!err) {
493                                 file = nameidata_to_filp(&nd, O_RDONLY);
494                                 if (!IS_ERR(file)) {
495                                         err = deny_write_access(file);
496                                         if (err) {
497                                                 fput(file);
498                                                 file = ERR_PTR(err);
499                                         }
500                                 }
501 out:
502                                 return file;
503                         }
504                 }
505                 release_open_intent(&nd);
506                 path_release(&nd);
507         }
508         goto out;
509 }
510
511 EXPORT_SYMBOL(open_exec);
512
513 int kernel_read(struct file *file, unsigned long offset,
514         char *addr, unsigned long count)
515 {
516         mm_segment_t old_fs;
517         loff_t pos = offset;
518         int result;
519
520         old_fs = get_fs();
521         set_fs(get_ds());
522         /* The cast to a user pointer is valid due to the set_fs() */
523         result = vfs_read(file, (void __user *)addr, count, &pos);
524         set_fs(old_fs);
525         return result;
526 }
527
528 EXPORT_SYMBOL(kernel_read);
529
530 static int exec_mmap(struct mm_struct *mm)
531 {
532         struct task_struct *tsk;
533         struct mm_struct * old_mm, *active_mm;
534
535         /* Notify parent that we're no longer interested in the old VM */
536         tsk = current;
537         old_mm = current->mm;
538         mm_release(tsk, old_mm);
539
540         if (old_mm) {
541                 /*
542                  * Make sure that if there is a core dump in progress
543                  * for the old mm, we get out and die instead of going
544                  * through with the exec.  We must hold mmap_sem around
545                  * checking core_waiters and changing tsk->mm.  The
546                  * core-inducing thread will increment core_waiters for
547                  * each thread whose ->mm == old_mm.
548                  */
549                 down_read(&old_mm->mmap_sem);
550                 if (unlikely(old_mm->core_waiters)) {
551                         up_read(&old_mm->mmap_sem);
552                         return -EINTR;
553                 }
554         }
555         task_lock(tsk);
556         active_mm = tsk->active_mm;
557         tsk->mm = mm;
558         tsk->active_mm = mm;
559         activate_mm(active_mm, mm);
560         task_unlock(tsk);
561         arch_pick_mmap_layout(mm);
562         if (old_mm) {
563                 up_read(&old_mm->mmap_sem);
564                 BUG_ON(active_mm != old_mm);
565                 mmput(old_mm);
566                 return 0;
567         }
568         mmdrop(active_mm);
569         return 0;
570 }
571
572 /*
573  * This function makes sure the current process has its own signal table,
574  * so that flush_signal_handlers can later reset the handlers without
575  * disturbing other processes.  (Other processes might share the signal
576  * table via the CLONE_SIGHAND option to clone().)
577  */
578 static int de_thread(struct task_struct *tsk)
579 {
580         struct signal_struct *sig = tsk->signal;
581         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
582         spinlock_t *lock = &oldsighand->siglock;
583         struct task_struct *leader = NULL;
584         int count;
585
586         /*
587          * If we don't share sighandlers, then we aren't sharing anything
588          * and we can just re-use it all.
589          */
590         if (atomic_read(&oldsighand->count) <= 1) {
591                 BUG_ON(atomic_read(&sig->count) != 1);
592                 exit_itimers(sig);
593                 return 0;
594         }
595
596         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
597         if (!newsighand)
598                 return -ENOMEM;
599
600         if (thread_group_empty(current))
601                 goto no_thread_group;
602
603         /*
604          * Kill all other threads in the thread group.
605          * We must hold tasklist_lock to call zap_other_threads.
606          */
607         read_lock(&tasklist_lock);
608         spin_lock_irq(lock);
609         if (sig->flags & SIGNAL_GROUP_EXIT) {
610                 /*
611                  * Another group action in progress, just
612                  * return so that the signal is processed.
613                  */
614                 spin_unlock_irq(lock);
615                 read_unlock(&tasklist_lock);
616                 kmem_cache_free(sighand_cachep, newsighand);
617                 return -EAGAIN;
618         }
619
620         /*
621          * child_reaper ignores SIGKILL, change it now.
622          * Reparenting needs write_lock on tasklist_lock,
623          * so it is safe to do it under read_lock.
624          */
625         if (unlikely(current->group_leader == child_reaper))
626                 child_reaper = current;
627
628         zap_other_threads(current);
629         read_unlock(&tasklist_lock);
630
631         /*
632          * Account for the thread group leader hanging around:
633          */
634         count = 1;
635         if (!thread_group_leader(current)) {
636                 count = 2;
637                 /*
638                  * The SIGALRM timer survives the exec, but needs to point
639                  * at us as the new group leader now.  We have a race with
640                  * a timer firing now getting the old leader, so we need to
641                  * synchronize with any firing (by calling del_timer_sync)
642                  * before we can safely let the old group leader die.
643                  */
644                 sig->tsk = current;
645                 spin_unlock_irq(lock);
646                 if (hrtimer_cancel(&sig->real_timer))
647                         hrtimer_restart(&sig->real_timer);
648                 spin_lock_irq(lock);
649         }
650         while (atomic_read(&sig->count) > count) {
651                 sig->group_exit_task = current;
652                 sig->notify_count = count;
653                 __set_current_state(TASK_UNINTERRUPTIBLE);
654                 spin_unlock_irq(lock);
655                 schedule();
656                 spin_lock_irq(lock);
657         }
658         sig->group_exit_task = NULL;
659         sig->notify_count = 0;
660         spin_unlock_irq(lock);
661
662         /*
663          * At this point all other threads have exited, all we have to
664          * do is to wait for the thread group leader to become inactive,
665          * and to assume its PID:
666          */
667         if (!thread_group_leader(current)) {
668                 /*
669                  * Wait for the thread group leader to be a zombie.
670                  * It should already be zombie at this point, most
671                  * of the time.
672                  */
673                 leader = current->group_leader;
674                 while (leader->exit_state != EXIT_ZOMBIE)
675                         yield();
676
677                 /*
678                  * The only record we have of the real-time age of a
679                  * process, regardless of execs it's done, is start_time.
680                  * All the past CPU time is accumulated in signal_struct
681                  * from sister threads now dead.  But in this non-leader
682                  * exec, nothing survives from the original leader thread,
683                  * whose birth marks the true age of this process now.
684                  * When we take on its identity by switching to its PID, we
685                  * also take its birthdate (always earlier than our own).
686                  */
687                 current->start_time = leader->start_time;
688
689                 write_lock_irq(&tasklist_lock);
690
691                 BUG_ON(leader->tgid != current->tgid);
692                 BUG_ON(current->pid == current->tgid);
693                 /*
694                  * An exec() starts a new thread group with the
695                  * TGID of the previous thread group. Rehash the
696                  * two threads with a switched PID, and release
697                  * the former thread group leader:
698                  */
699
700                 /* Become a process group leader with the old leader's pid.
701                  * Note: The old leader also uses thispid until release_task
702                  *       is called.  Odd but simple and correct.
703                  */
704                 detach_pid(current, PIDTYPE_PID);
705                 current->pid = leader->pid;
706                 attach_pid(current, PIDTYPE_PID,  current->pid);
707                 attach_pid(current, PIDTYPE_PGID, current->signal->pgrp);
708                 attach_pid(current, PIDTYPE_SID,  current->signal->session);
709                 list_replace_rcu(&leader->tasks, &current->tasks);
710
711                 current->group_leader = current;
712                 leader->group_leader = current;
713
714                 /* Reduce leader to a thread */
715                 detach_pid(leader, PIDTYPE_PGID);
716                 detach_pid(leader, PIDTYPE_SID);
717
718                 current->exit_signal = SIGCHLD;
719
720                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
721                 leader->exit_state = EXIT_DEAD;
722
723                 write_unlock_irq(&tasklist_lock);
724         }
725
726         /*
727          * There may be one thread left which is just exiting,
728          * but it's safe to stop telling the group to kill themselves.
729          */
730         sig->flags = 0;
731
732 no_thread_group:
733         exit_itimers(sig);
734         if (leader)
735                 release_task(leader);
736
737         BUG_ON(atomic_read(&sig->count) != 1);
738
739         if (atomic_read(&oldsighand->count) == 1) {
740                 /*
741                  * Now that we nuked the rest of the thread group,
742                  * it turns out we are not sharing sighand any more either.
743                  * So we can just keep it.
744                  */
745                 kmem_cache_free(sighand_cachep, newsighand);
746         } else {
747                 /*
748                  * Move our state over to newsighand and switch it in.
749                  */
750                 atomic_set(&newsighand->count, 1);
751                 memcpy(newsighand->action, oldsighand->action,
752                        sizeof(newsighand->action));
753
754                 write_lock_irq(&tasklist_lock);
755                 spin_lock(&oldsighand->siglock);
756                 spin_lock(&newsighand->siglock);
757
758                 rcu_assign_pointer(current->sighand, newsighand);
759                 recalc_sigpending();
760
761                 spin_unlock(&newsighand->siglock);
762                 spin_unlock(&oldsighand->siglock);
763                 write_unlock_irq(&tasklist_lock);
764
765                 if (atomic_dec_and_test(&oldsighand->count))
766                         kmem_cache_free(sighand_cachep, oldsighand);
767         }
768
769         BUG_ON(!thread_group_leader(current));
770         return 0;
771 }
772         
773 /*
774  * These functions flushes out all traces of the currently running executable
775  * so that a new one can be started
776  */
777
778 static void flush_old_files(struct files_struct * files)
779 {
780         long j = -1;
781         struct fdtable *fdt;
782
783         spin_lock(&files->file_lock);
784         for (;;) {
785                 unsigned long set, i;
786
787                 j++;
788                 i = j * __NFDBITS;
789                 fdt = files_fdtable(files);
790                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
791                         break;
792                 set = fdt->close_on_exec->fds_bits[j];
793                 if (!set)
794                         continue;
795                 fdt->close_on_exec->fds_bits[j] = 0;
796                 spin_unlock(&files->file_lock);
797                 for ( ; set ; i++,set >>= 1) {
798                         if (set & 1) {
799                                 sys_close(i);
800                         }
801                 }
802                 spin_lock(&files->file_lock);
803
804         }
805         spin_unlock(&files->file_lock);
806 }
807
808 void get_task_comm(char *buf, struct task_struct *tsk)
809 {
810         /* buf must be at least sizeof(tsk->comm) in size */
811         task_lock(tsk);
812         strncpy(buf, tsk->comm, sizeof(tsk->comm));
813         task_unlock(tsk);
814 }
815
816 void set_task_comm(struct task_struct *tsk, char *buf)
817 {
818         task_lock(tsk);
819         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
820         task_unlock(tsk);
821 }
822
823 int flush_old_exec(struct linux_binprm * bprm)
824 {
825         char * name;
826         int i, ch, retval;
827         struct files_struct *files;
828         char tcomm[sizeof(current->comm)];
829
830         /*
831          * Make sure we have a private signal table and that
832          * we are unassociated from the previous thread group.
833          */
834         retval = de_thread(current);
835         if (retval)
836                 goto out;
837
838         /*
839          * Make sure we have private file handles. Ask the
840          * fork helper to do the work for us and the exit
841          * helper to do the cleanup of the old one.
842          */
843         files = current->files;         /* refcounted so safe to hold */
844         retval = unshare_files();
845         if (retval)
846                 goto out;
847         /*
848          * Release all of the old mmap stuff
849          */
850         retval = exec_mmap(bprm->mm);
851         if (retval)
852                 goto mmap_failed;
853
854         bprm->mm = NULL;                /* We're using it now */
855
856         /* This is the point of no return */
857         put_files_struct(files);
858
859         current->sas_ss_sp = current->sas_ss_size = 0;
860
861         if (current->euid == current->uid && current->egid == current->gid)
862                 current->mm->dumpable = 1;
863         else
864                 current->mm->dumpable = suid_dumpable;
865
866         name = bprm->filename;
867
868         /* Copies the binary name from after last slash */
869         for (i=0; (ch = *(name++)) != '\0';) {
870                 if (ch == '/')
871                         i = 0; /* overwrite what we wrote */
872                 else
873                         if (i < (sizeof(tcomm) - 1))
874                                 tcomm[i++] = ch;
875         }
876         tcomm[i] = '\0';
877         set_task_comm(current, tcomm);
878
879         current->flags &= ~PF_RANDOMIZE;
880         flush_thread();
881
882         /* Set the new mm task size. We have to do that late because it may
883          * depend on TIF_32BIT which is only updated in flush_thread() on
884          * some architectures like powerpc
885          */
886         current->mm->task_size = TASK_SIZE;
887
888         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
889             file_permission(bprm->file, MAY_READ) ||
890             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
891                 suid_keys(current);
892                 current->mm->dumpable = suid_dumpable;
893         }
894
895         /* An exec changes our domain. We are no longer part of the thread
896            group */
897
898         current->self_exec_id++;
899                         
900         flush_signal_handlers(current, 0);
901         flush_old_files(current->files);
902
903         return 0;
904
905 mmap_failed:
906         put_files_struct(current->files);
907         current->files = files;
908 out:
909         return retval;
910 }
911
912 EXPORT_SYMBOL(flush_old_exec);
913
914 /* 
915  * Fill the binprm structure from the inode. 
916  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
917  */
918 int prepare_binprm(struct linux_binprm *bprm)
919 {
920         int mode;
921         struct inode * inode = bprm->file->f_dentry->d_inode;
922         int retval;
923
924         mode = inode->i_mode;
925         if (bprm->file->f_op == NULL)
926                 return -EACCES;
927
928         bprm->e_uid = current->euid;
929         bprm->e_gid = current->egid;
930
931         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
932                 /* Set-uid? */
933                 if (mode & S_ISUID) {
934                         current->personality &= ~PER_CLEAR_ON_SETID;
935                         bprm->e_uid = inode->i_uid;
936                 }
937
938                 /* Set-gid? */
939                 /*
940                  * If setgid is set but no group execute bit then this
941                  * is a candidate for mandatory locking, not a setgid
942                  * executable.
943                  */
944                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
945                         current->personality &= ~PER_CLEAR_ON_SETID;
946                         bprm->e_gid = inode->i_gid;
947                 }
948         }
949
950         /* fill in binprm security blob */
951         retval = security_bprm_set(bprm);
952         if (retval)
953                 return retval;
954
955         memset(bprm->buf,0,BINPRM_BUF_SIZE);
956         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
957 }
958
959 EXPORT_SYMBOL(prepare_binprm);
960
961 static int unsafe_exec(struct task_struct *p)
962 {
963         int unsafe = 0;
964         if (p->ptrace & PT_PTRACED) {
965                 if (p->ptrace & PT_PTRACE_CAP)
966                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
967                 else
968                         unsafe |= LSM_UNSAFE_PTRACE;
969         }
970         if (atomic_read(&p->fs->count) > 1 ||
971             atomic_read(&p->files->count) > 1 ||
972             atomic_read(&p->sighand->count) > 1)
973                 unsafe |= LSM_UNSAFE_SHARE;
974
975         return unsafe;
976 }
977
978 void compute_creds(struct linux_binprm *bprm)
979 {
980         int unsafe;
981
982         if (bprm->e_uid != current->uid)
983                 suid_keys(current);
984         exec_keys(current);
985
986         task_lock(current);
987         unsafe = unsafe_exec(current);
988         security_bprm_apply_creds(bprm, unsafe);
989         task_unlock(current);
990         security_bprm_post_apply_creds(bprm);
991 }
992
993 EXPORT_SYMBOL(compute_creds);
994
995 void remove_arg_zero(struct linux_binprm *bprm)
996 {
997         if (bprm->argc) {
998                 unsigned long offset;
999                 char * kaddr;
1000                 struct page *page;
1001
1002                 offset = bprm->p % PAGE_SIZE;
1003                 goto inside;
1004
1005                 while (bprm->p++, *(kaddr+offset++)) {
1006                         if (offset != PAGE_SIZE)
1007                                 continue;
1008                         offset = 0;
1009                         kunmap_atomic(kaddr, KM_USER0);
1010 inside:
1011                         page = bprm->page[bprm->p/PAGE_SIZE];
1012                         kaddr = kmap_atomic(page, KM_USER0);
1013                 }
1014                 kunmap_atomic(kaddr, KM_USER0);
1015                 bprm->argc--;
1016         }
1017 }
1018
1019 EXPORT_SYMBOL(remove_arg_zero);
1020
1021 /*
1022  * cycle the list of binary formats handler, until one recognizes the image
1023  */
1024 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1025 {
1026         int try,retval;
1027         struct linux_binfmt *fmt;
1028 #ifdef __alpha__
1029         /* handle /sbin/loader.. */
1030         {
1031             struct exec * eh = (struct exec *) bprm->buf;
1032
1033             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1034                 (eh->fh.f_flags & 0x3000) == 0x3000)
1035             {
1036                 struct file * file;
1037                 unsigned long loader;
1038
1039                 allow_write_access(bprm->file);
1040                 fput(bprm->file);
1041                 bprm->file = NULL;
1042
1043                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1044
1045                 file = open_exec("/sbin/loader");
1046                 retval = PTR_ERR(file);
1047                 if (IS_ERR(file))
1048                         return retval;
1049
1050                 /* Remember if the application is TASO.  */
1051                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1052
1053                 bprm->file = file;
1054                 bprm->loader = loader;
1055                 retval = prepare_binprm(bprm);
1056                 if (retval<0)
1057                         return retval;
1058                 /* should call search_binary_handler recursively here,
1059                    but it does not matter */
1060             }
1061         }
1062 #endif
1063         retval = security_bprm_check(bprm);
1064         if (retval)
1065                 return retval;
1066
1067         /* kernel module loader fixup */
1068         /* so we don't try to load run modprobe in kernel space. */
1069         set_fs(USER_DS);
1070
1071         retval = audit_bprm(bprm);
1072         if (retval)
1073                 return retval;
1074
1075         retval = -ENOENT;
1076         for (try=0; try<2; try++) {
1077                 read_lock(&binfmt_lock);
1078                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1079                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1080                         if (!fn)
1081                                 continue;
1082                         if (!try_module_get(fmt->module))
1083                                 continue;
1084                         read_unlock(&binfmt_lock);
1085                         retval = fn(bprm, regs);
1086                         if (retval >= 0) {
1087                                 put_binfmt(fmt);
1088                                 allow_write_access(bprm->file);
1089                                 if (bprm->file)
1090                                         fput(bprm->file);
1091                                 bprm->file = NULL;
1092                                 current->did_exec = 1;
1093                                 proc_exec_connector(current);
1094                                 return retval;
1095                         }
1096                         read_lock(&binfmt_lock);
1097                         put_binfmt(fmt);
1098                         if (retval != -ENOEXEC || bprm->mm == NULL)
1099                                 break;
1100                         if (!bprm->file) {
1101                                 read_unlock(&binfmt_lock);
1102                                 return retval;
1103                         }
1104                 }
1105                 read_unlock(&binfmt_lock);
1106                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1107                         break;
1108 #ifdef CONFIG_KMOD
1109                 }else{
1110 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1111                         if (printable(bprm->buf[0]) &&
1112                             printable(bprm->buf[1]) &&
1113                             printable(bprm->buf[2]) &&
1114                             printable(bprm->buf[3]))
1115                                 break; /* -ENOEXEC */
1116                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1117 #endif
1118                 }
1119         }
1120         return retval;
1121 }
1122
1123 EXPORT_SYMBOL(search_binary_handler);
1124
1125 /*
1126  * sys_execve() executes a new program.
1127  */
1128 int do_execve(char * filename,
1129         char __user *__user *argv,
1130         char __user *__user *envp,
1131         struct pt_regs * regs)
1132 {
1133         struct linux_binprm *bprm;
1134         struct file *file;
1135         int retval;
1136         int i;
1137
1138         retval = -ENOMEM;
1139         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1140         if (!bprm)
1141                 goto out_ret;
1142
1143         file = open_exec(filename);
1144         retval = PTR_ERR(file);
1145         if (IS_ERR(file))
1146                 goto out_kfree;
1147
1148         sched_exec();
1149
1150         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1151
1152         bprm->file = file;
1153         bprm->filename = filename;
1154         bprm->interp = filename;
1155         bprm->mm = mm_alloc();
1156         retval = -ENOMEM;
1157         if (!bprm->mm)
1158                 goto out_file;
1159
1160         retval = init_new_context(current, bprm->mm);
1161         if (retval < 0)
1162                 goto out_mm;
1163
1164         bprm->argc = count(argv, bprm->p / sizeof(void *));
1165         if ((retval = bprm->argc) < 0)
1166                 goto out_mm;
1167
1168         bprm->envc = count(envp, bprm->p / sizeof(void *));
1169         if ((retval = bprm->envc) < 0)
1170                 goto out_mm;
1171
1172         retval = security_bprm_alloc(bprm);
1173         if (retval)
1174                 goto out;
1175
1176         retval = prepare_binprm(bprm);
1177         if (retval < 0)
1178                 goto out;
1179
1180         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1181         if (retval < 0)
1182                 goto out;
1183
1184         bprm->exec = bprm->p;
1185         retval = copy_strings(bprm->envc, envp, bprm);
1186         if (retval < 0)
1187                 goto out;
1188
1189         retval = copy_strings(bprm->argc, argv, bprm);
1190         if (retval < 0)
1191                 goto out;
1192
1193         retval = search_binary_handler(bprm,regs);
1194         if (retval >= 0) {
1195                 free_arg_pages(bprm);
1196
1197                 /* execve success */
1198                 security_bprm_free(bprm);
1199                 acct_update_integrals(current);
1200                 kfree(bprm);
1201                 return retval;
1202         }
1203
1204 out:
1205         /* Something went wrong, return the inode and free the argument pages*/
1206         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1207                 struct page * page = bprm->page[i];
1208                 if (page)
1209                         __free_page(page);
1210         }
1211
1212         if (bprm->security)
1213                 security_bprm_free(bprm);
1214
1215 out_mm:
1216         if (bprm->mm)
1217                 mmdrop(bprm->mm);
1218
1219 out_file:
1220         if (bprm->file) {
1221                 allow_write_access(bprm->file);
1222                 fput(bprm->file);
1223         }
1224
1225 out_kfree:
1226         kfree(bprm);
1227
1228 out_ret:
1229         return retval;
1230 }
1231
1232 int set_binfmt(struct linux_binfmt *new)
1233 {
1234         struct linux_binfmt *old = current->binfmt;
1235
1236         if (new) {
1237                 if (!try_module_get(new->module))
1238                         return -1;
1239         }
1240         current->binfmt = new;
1241         if (old)
1242                 module_put(old->module);
1243         return 0;
1244 }
1245
1246 EXPORT_SYMBOL(set_binfmt);
1247
1248 #define CORENAME_MAX_SIZE 64
1249
1250 /* format_corename will inspect the pattern parameter, and output a
1251  * name into corename, which must have space for at least
1252  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1253  */
1254 static void format_corename(char *corename, const char *pattern, long signr)
1255 {
1256         const char *pat_ptr = pattern;
1257         char *out_ptr = corename;
1258         char *const out_end = corename + CORENAME_MAX_SIZE;
1259         int rc;
1260         int pid_in_pattern = 0;
1261
1262         /* Repeat as long as we have more pattern to process and more output
1263            space */
1264         while (*pat_ptr) {
1265                 if (*pat_ptr != '%') {
1266                         if (out_ptr == out_end)
1267                                 goto out;
1268                         *out_ptr++ = *pat_ptr++;
1269                 } else {
1270                         switch (*++pat_ptr) {
1271                         case 0:
1272                                 goto out;
1273                         /* Double percent, output one percent */
1274                         case '%':
1275                                 if (out_ptr == out_end)
1276                                         goto out;
1277                                 *out_ptr++ = '%';
1278                                 break;
1279                         /* pid */
1280                         case 'p':
1281                                 pid_in_pattern = 1;
1282                                 rc = snprintf(out_ptr, out_end - out_ptr,
1283                                               "%d", current->tgid);
1284                                 if (rc > out_end - out_ptr)
1285                                         goto out;
1286                                 out_ptr += rc;
1287                                 break;
1288                         /* uid */
1289                         case 'u':
1290                                 rc = snprintf(out_ptr, out_end - out_ptr,
1291                                               "%d", current->uid);
1292                                 if (rc > out_end - out_ptr)
1293                                         goto out;
1294                                 out_ptr += rc;
1295                                 break;
1296                         /* gid */
1297                         case 'g':
1298                                 rc = snprintf(out_ptr, out_end - out_ptr,
1299                                               "%d", current->gid);
1300                                 if (rc > out_end - out_ptr)
1301                                         goto out;
1302                                 out_ptr += rc;
1303                                 break;
1304                         /* signal that caused the coredump */
1305                         case 's':
1306                                 rc = snprintf(out_ptr, out_end - out_ptr,
1307                                               "%ld", signr);
1308                                 if (rc > out_end - out_ptr)
1309                                         goto out;
1310                                 out_ptr += rc;
1311                                 break;
1312                         /* UNIX time of coredump */
1313                         case 't': {
1314                                 struct timeval tv;
1315                                 do_gettimeofday(&tv);
1316                                 rc = snprintf(out_ptr, out_end - out_ptr,
1317                                               "%lu", tv.tv_sec);
1318                                 if (rc > out_end - out_ptr)
1319                                         goto out;
1320                                 out_ptr += rc;
1321                                 break;
1322                         }
1323                         /* hostname */
1324                         case 'h':
1325                                 down_read(&uts_sem);
1326                                 rc = snprintf(out_ptr, out_end - out_ptr,
1327                                               "%s", system_utsname.nodename);
1328                                 up_read(&uts_sem);
1329                                 if (rc > out_end - out_ptr)
1330                                         goto out;
1331                                 out_ptr += rc;
1332                                 break;
1333                         /* executable */
1334                         case 'e':
1335                                 rc = snprintf(out_ptr, out_end - out_ptr,
1336                                               "%s", current->comm);
1337                                 if (rc > out_end - out_ptr)
1338                                         goto out;
1339                                 out_ptr += rc;
1340                                 break;
1341                         default:
1342                                 break;
1343                         }
1344                         ++pat_ptr;
1345                 }
1346         }
1347         /* Backward compatibility with core_uses_pid:
1348          *
1349          * If core_pattern does not include a %p (as is the default)
1350          * and core_uses_pid is set, then .%pid will be appended to
1351          * the filename */
1352         if (!pid_in_pattern
1353             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1354                 rc = snprintf(out_ptr, out_end - out_ptr,
1355                               ".%d", current->tgid);
1356                 if (rc > out_end - out_ptr)
1357                         goto out;
1358                 out_ptr += rc;
1359         }
1360       out:
1361         *out_ptr = 0;
1362 }
1363
1364 static void zap_process(struct task_struct *start)
1365 {
1366         struct task_struct *t;
1367
1368         start->signal->flags = SIGNAL_GROUP_EXIT;
1369         start->signal->group_stop_count = 0;
1370
1371         t = start;
1372         do {
1373                 if (t != current && t->mm) {
1374                         t->mm->core_waiters++;
1375                         sigaddset(&t->pending.signal, SIGKILL);
1376                         signal_wake_up(t, 1);
1377                 }
1378         } while ((t = next_thread(t)) != start);
1379 }
1380
1381 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1382                                 int exit_code)
1383 {
1384         struct task_struct *g, *p;
1385         unsigned long flags;
1386         int err = -EAGAIN;
1387
1388         spin_lock_irq(&tsk->sighand->siglock);
1389         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1390                 tsk->signal->group_exit_code = exit_code;
1391                 zap_process(tsk);
1392                 err = 0;
1393         }
1394         spin_unlock_irq(&tsk->sighand->siglock);
1395         if (err)
1396                 return err;
1397
1398         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1399                 goto done;
1400
1401         rcu_read_lock();
1402         for_each_process(g) {
1403                 if (g == tsk->group_leader)
1404                         continue;
1405
1406                 p = g;
1407                 do {
1408                         if (p->mm) {
1409                                 if (p->mm == mm) {
1410                                         /*
1411                                          * p->sighand can't disappear, but
1412                                          * may be changed by de_thread()
1413                                          */
1414                                         lock_task_sighand(p, &flags);
1415                                         zap_process(p);
1416                                         unlock_task_sighand(p, &flags);
1417                                 }
1418                                 break;
1419                         }
1420                 } while ((p = next_thread(p)) != g);
1421         }
1422         rcu_read_unlock();
1423 done:
1424         return mm->core_waiters;
1425 }
1426
1427 static int coredump_wait(int exit_code)
1428 {
1429         struct task_struct *tsk = current;
1430         struct mm_struct *mm = tsk->mm;
1431         struct completion startup_done;
1432         struct completion *vfork_done;
1433         int core_waiters;
1434
1435         init_completion(&mm->core_done);
1436         init_completion(&startup_done);
1437         mm->core_startup_done = &startup_done;
1438
1439         core_waiters = zap_threads(tsk, mm, exit_code);
1440         up_write(&mm->mmap_sem);
1441
1442         if (unlikely(core_waiters < 0))
1443                 goto fail;
1444
1445         /*
1446          * Make sure nobody is waiting for us to release the VM,
1447          * otherwise we can deadlock when we wait on each other
1448          */
1449         vfork_done = tsk->vfork_done;
1450         if (vfork_done) {
1451                 tsk->vfork_done = NULL;
1452                 complete(vfork_done);
1453         }
1454
1455         if (core_waiters)
1456                 wait_for_completion(&startup_done);
1457 fail:
1458         BUG_ON(mm->core_waiters);
1459         return core_waiters;
1460 }
1461
1462 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1463 {
1464         char corename[CORENAME_MAX_SIZE + 1];
1465         struct mm_struct *mm = current->mm;
1466         struct linux_binfmt * binfmt;
1467         struct inode * inode;
1468         struct file * file;
1469         int retval = 0;
1470         int fsuid = current->fsuid;
1471         int flag = 0;
1472
1473         binfmt = current->binfmt;
1474         if (!binfmt || !binfmt->core_dump)
1475                 goto fail;
1476         down_write(&mm->mmap_sem);
1477         if (!mm->dumpable) {
1478                 up_write(&mm->mmap_sem);
1479                 goto fail;
1480         }
1481
1482         /*
1483          *      We cannot trust fsuid as being the "true" uid of the
1484          *      process nor do we know its entire history. We only know it
1485          *      was tainted so we dump it as root in mode 2.
1486          */
1487         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1488                 flag = O_EXCL;          /* Stop rewrite attacks */
1489                 current->fsuid = 0;     /* Dump root private */
1490         }
1491         mm->dumpable = 0;
1492
1493         retval = coredump_wait(exit_code);
1494         if (retval < 0)
1495                 goto fail;
1496
1497         /*
1498          * Clear any false indication of pending signals that might
1499          * be seen by the filesystem code called to write the core file.
1500          */
1501         clear_thread_flag(TIF_SIGPENDING);
1502
1503         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1504                 goto fail_unlock;
1505
1506         /*
1507          * lock_kernel() because format_corename() is controlled by sysctl, which
1508          * uses lock_kernel()
1509          */
1510         lock_kernel();
1511         format_corename(corename, core_pattern, signr);
1512         unlock_kernel();
1513         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1514         if (IS_ERR(file))
1515                 goto fail_unlock;
1516         inode = file->f_dentry->d_inode;
1517         if (inode->i_nlink > 1)
1518                 goto close_fail;        /* multiple links - don't dump */
1519         if (d_unhashed(file->f_dentry))
1520                 goto close_fail;
1521
1522         if (!S_ISREG(inode->i_mode))
1523                 goto close_fail;
1524         if (!file->f_op)
1525                 goto close_fail;
1526         if (!file->f_op->write)
1527                 goto close_fail;
1528         if (do_truncate(file->f_dentry, 0, 0, file) != 0)
1529                 goto close_fail;
1530
1531         retval = binfmt->core_dump(signr, regs, file);
1532
1533         if (retval)
1534                 current->signal->group_exit_code |= 0x80;
1535 close_fail:
1536         filp_close(file, NULL);
1537 fail_unlock:
1538         current->fsuid = fsuid;
1539         complete_all(&mm->core_done);
1540 fail:
1541         return retval;
1542 }