[PATCH] use kzalloc and kcalloc in core fs code
[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/config.h>
26 #include <linux/slab.h>
27 #include <linux/file.h>
28 #include <linux/mman.h>
29 #include <linux/a.out.h>
30 #include <linux/stat.h>
31 #include <linux/fcntl.h>
32 #include <linux/smp_lock.h>
33 #include <linux/init.h>
34 #include <linux/pagemap.h>
35 #include <linux/highmem.h>
36 #include <linux/spinlock.h>
37 #include <linux/key.h>
38 #include <linux/personality.h>
39 #include <linux/binfmts.h>
40 #include <linux/swap.h>
41 #include <linux/utsname.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/acct.h>
51 #include <linux/cn_proc.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                 if (active_mm != old_mm) BUG();
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         zap_other_threads(current);
620         read_unlock(&tasklist_lock);
621
622         /*
623          * Account for the thread group leader hanging around:
624          */
625         count = 1;
626         if (!thread_group_leader(current)) {
627                 count = 2;
628                 /*
629                  * The SIGALRM timer survives the exec, but needs to point
630                  * at us as the new group leader now.  We have a race with
631                  * a timer firing now getting the old leader, so we need to
632                  * synchronize with any firing (by calling del_timer_sync)
633                  * before we can safely let the old group leader die.
634                  */
635                 sig->real_timer.data = current;
636                 spin_unlock_irq(lock);
637                 if (hrtimer_cancel(&sig->real_timer))
638                         hrtimer_restart(&sig->real_timer);
639                 spin_lock_irq(lock);
640         }
641         while (atomic_read(&sig->count) > count) {
642                 sig->group_exit_task = current;
643                 sig->notify_count = count;
644                 __set_current_state(TASK_UNINTERRUPTIBLE);
645                 spin_unlock_irq(lock);
646                 schedule();
647                 spin_lock_irq(lock);
648         }
649         sig->group_exit_task = NULL;
650         sig->notify_count = 0;
651         spin_unlock_irq(lock);
652
653         /*
654          * At this point all other threads have exited, all we have to
655          * do is to wait for the thread group leader to become inactive,
656          * and to assume its PID:
657          */
658         if (!thread_group_leader(current)) {
659                 struct task_struct *parent;
660                 struct dentry *proc_dentry1, *proc_dentry2;
661                 unsigned long ptrace;
662
663                 /*
664                  * Wait for the thread group leader to be a zombie.
665                  * It should already be zombie at this point, most
666                  * of the time.
667                  */
668                 leader = current->group_leader;
669                 while (leader->exit_state != EXIT_ZOMBIE)
670                         yield();
671
672                 spin_lock(&leader->proc_lock);
673                 spin_lock(&current->proc_lock);
674                 proc_dentry1 = proc_pid_unhash(current);
675                 proc_dentry2 = proc_pid_unhash(leader);
676                 write_lock_irq(&tasklist_lock);
677
678                 BUG_ON(leader->tgid != current->tgid);
679                 BUG_ON(current->pid == current->tgid);
680                 /*
681                  * An exec() starts a new thread group with the
682                  * TGID of the previous thread group. Rehash the
683                  * two threads with a switched PID, and release
684                  * the former thread group leader:
685                  */
686                 ptrace = leader->ptrace;
687                 parent = leader->parent;
688                 if (unlikely(ptrace) && unlikely(parent == current)) {
689                         /*
690                          * Joker was ptracing his own group leader,
691                          * and now he wants to be his own parent!
692                          * We can't have that.
693                          */
694                         ptrace = 0;
695                 }
696
697                 ptrace_unlink(current);
698                 ptrace_unlink(leader);
699                 remove_parent(current);
700                 remove_parent(leader);
701
702                 switch_exec_pids(leader, current);
703
704                 current->parent = current->real_parent = leader->real_parent;
705                 leader->parent = leader->real_parent = child_reaper;
706                 current->group_leader = current;
707                 leader->group_leader = leader;
708
709                 add_parent(current, current->parent);
710                 add_parent(leader, leader->parent);
711                 if (ptrace) {
712                         current->ptrace = ptrace;
713                         __ptrace_link(current, parent);
714                 }
715
716                 list_del(&current->tasks);
717                 list_add_tail(&current->tasks, &init_task.tasks);
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                 spin_unlock(&leader->proc_lock);
725                 spin_unlock(&current->proc_lock);
726                 proc_pid_flush(proc_dentry1);
727                 proc_pid_flush(proc_dentry2);
728         }
729
730         /*
731          * There may be one thread left which is just exiting,
732          * but it's safe to stop telling the group to kill themselves.
733          */
734         sig->flags = 0;
735
736 no_thread_group:
737         exit_itimers(sig);
738         if (leader)
739                 release_task(leader);
740
741         BUG_ON(atomic_read(&sig->count) != 1);
742
743         if (atomic_read(&oldsighand->count) == 1) {
744                 /*
745                  * Now that we nuked the rest of the thread group,
746                  * it turns out we are not sharing sighand any more either.
747                  * So we can just keep it.
748                  */
749                 kmem_cache_free(sighand_cachep, newsighand);
750         } else {
751                 /*
752                  * Move our state over to newsighand and switch it in.
753                  */
754                 spin_lock_init(&newsighand->siglock);
755                 atomic_set(&newsighand->count, 1);
756                 memcpy(newsighand->action, oldsighand->action,
757                        sizeof(newsighand->action));
758
759                 write_lock_irq(&tasklist_lock);
760                 spin_lock(&oldsighand->siglock);
761                 spin_lock(&newsighand->siglock);
762
763                 rcu_assign_pointer(current->sighand, newsighand);
764                 recalc_sigpending();
765
766                 spin_unlock(&newsighand->siglock);
767                 spin_unlock(&oldsighand->siglock);
768                 write_unlock_irq(&tasklist_lock);
769
770                 if (atomic_dec_and_test(&oldsighand->count))
771                         sighand_free(oldsighand);
772         }
773
774         BUG_ON(!thread_group_leader(current));
775         return 0;
776 }
777         
778 /*
779  * These functions flushes out all traces of the currently running executable
780  * so that a new one can be started
781  */
782
783 static void flush_old_files(struct files_struct * files)
784 {
785         long j = -1;
786         struct fdtable *fdt;
787
788         spin_lock(&files->file_lock);
789         for (;;) {
790                 unsigned long set, i;
791
792                 j++;
793                 i = j * __NFDBITS;
794                 fdt = files_fdtable(files);
795                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
796                         break;
797                 set = fdt->close_on_exec->fds_bits[j];
798                 if (!set)
799                         continue;
800                 fdt->close_on_exec->fds_bits[j] = 0;
801                 spin_unlock(&files->file_lock);
802                 for ( ; set ; i++,set >>= 1) {
803                         if (set & 1) {
804                                 sys_close(i);
805                         }
806                 }
807                 spin_lock(&files->file_lock);
808
809         }
810         spin_unlock(&files->file_lock);
811 }
812
813 void get_task_comm(char *buf, struct task_struct *tsk)
814 {
815         /* buf must be at least sizeof(tsk->comm) in size */
816         task_lock(tsk);
817         strncpy(buf, tsk->comm, sizeof(tsk->comm));
818         task_unlock(tsk);
819 }
820
821 void set_task_comm(struct task_struct *tsk, char *buf)
822 {
823         task_lock(tsk);
824         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
825         task_unlock(tsk);
826 }
827
828 int flush_old_exec(struct linux_binprm * bprm)
829 {
830         char * name;
831         int i, ch, retval;
832         struct files_struct *files;
833         char tcomm[sizeof(current->comm)];
834
835         /*
836          * Make sure we have a private signal table and that
837          * we are unassociated from the previous thread group.
838          */
839         retval = de_thread(current);
840         if (retval)
841                 goto out;
842
843         /*
844          * Make sure we have private file handles. Ask the
845          * fork helper to do the work for us and the exit
846          * helper to do the cleanup of the old one.
847          */
848         files = current->files;         /* refcounted so safe to hold */
849         retval = unshare_files();
850         if (retval)
851                 goto out;
852         /*
853          * Release all of the old mmap stuff
854          */
855         retval = exec_mmap(bprm->mm);
856         if (retval)
857                 goto mmap_failed;
858
859         bprm->mm = NULL;                /* We're using it now */
860
861         /* This is the point of no return */
862         steal_locks(files);
863         put_files_struct(files);
864
865         current->sas_ss_sp = current->sas_ss_size = 0;
866
867         if (current->euid == current->uid && current->egid == current->gid)
868                 current->mm->dumpable = 1;
869         else
870                 current->mm->dumpable = suid_dumpable;
871
872         name = bprm->filename;
873
874         /* Copies the binary name from after last slash */
875         for (i=0; (ch = *(name++)) != '\0';) {
876                 if (ch == '/')
877                         i = 0; /* overwrite what we wrote */
878                 else
879                         if (i < (sizeof(tcomm) - 1))
880                                 tcomm[i++] = ch;
881         }
882         tcomm[i] = '\0';
883         set_task_comm(current, tcomm);
884
885         current->flags &= ~PF_RANDOMIZE;
886         flush_thread();
887
888         /* Set the new mm task size. We have to do that late because it may
889          * depend on TIF_32BIT which is only updated in flush_thread() on
890          * some architectures like powerpc
891          */
892         current->mm->task_size = TASK_SIZE;
893
894         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
895             file_permission(bprm->file, MAY_READ) ||
896             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
897                 suid_keys(current);
898                 current->mm->dumpable = suid_dumpable;
899         }
900
901         /* An exec changes our domain. We are no longer part of the thread
902            group */
903
904         current->self_exec_id++;
905                         
906         flush_signal_handlers(current, 0);
907         flush_old_files(current->files);
908
909         return 0;
910
911 mmap_failed:
912         put_files_struct(current->files);
913         current->files = files;
914 out:
915         return retval;
916 }
917
918 EXPORT_SYMBOL(flush_old_exec);
919
920 /* 
921  * Fill the binprm structure from the inode. 
922  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
923  */
924 int prepare_binprm(struct linux_binprm *bprm)
925 {
926         int mode;
927         struct inode * inode = bprm->file->f_dentry->d_inode;
928         int retval;
929
930         mode = inode->i_mode;
931         /*
932          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
933          * generic_permission lets a non-executable through
934          */
935         if (!(mode & 0111))     /* with at least _one_ execute bit set */
936                 return -EACCES;
937         if (bprm->file->f_op == NULL)
938                 return -EACCES;
939
940         bprm->e_uid = current->euid;
941         bprm->e_gid = current->egid;
942
943         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
944                 /* Set-uid? */
945                 if (mode & S_ISUID) {
946                         current->personality &= ~PER_CLEAR_ON_SETID;
947                         bprm->e_uid = inode->i_uid;
948                 }
949
950                 /* Set-gid? */
951                 /*
952                  * If setgid is set but no group execute bit then this
953                  * is a candidate for mandatory locking, not a setgid
954                  * executable.
955                  */
956                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
957                         current->personality &= ~PER_CLEAR_ON_SETID;
958                         bprm->e_gid = inode->i_gid;
959                 }
960         }
961
962         /* fill in binprm security blob */
963         retval = security_bprm_set(bprm);
964         if (retval)
965                 return retval;
966
967         memset(bprm->buf,0,BINPRM_BUF_SIZE);
968         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
969 }
970
971 EXPORT_SYMBOL(prepare_binprm);
972
973 static int unsafe_exec(struct task_struct *p)
974 {
975         int unsafe = 0;
976         if (p->ptrace & PT_PTRACED) {
977                 if (p->ptrace & PT_PTRACE_CAP)
978                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
979                 else
980                         unsafe |= LSM_UNSAFE_PTRACE;
981         }
982         if (atomic_read(&p->fs->count) > 1 ||
983             atomic_read(&p->files->count) > 1 ||
984             atomic_read(&p->sighand->count) > 1)
985                 unsafe |= LSM_UNSAFE_SHARE;
986
987         return unsafe;
988 }
989
990 void compute_creds(struct linux_binprm *bprm)
991 {
992         int unsafe;
993
994         if (bprm->e_uid != current->uid)
995                 suid_keys(current);
996         exec_keys(current);
997
998         task_lock(current);
999         unsafe = unsafe_exec(current);
1000         security_bprm_apply_creds(bprm, unsafe);
1001         task_unlock(current);
1002         security_bprm_post_apply_creds(bprm);
1003 }
1004
1005 EXPORT_SYMBOL(compute_creds);
1006
1007 void remove_arg_zero(struct linux_binprm *bprm)
1008 {
1009         if (bprm->argc) {
1010                 unsigned long offset;
1011                 char * kaddr;
1012                 struct page *page;
1013
1014                 offset = bprm->p % PAGE_SIZE;
1015                 goto inside;
1016
1017                 while (bprm->p++, *(kaddr+offset++)) {
1018                         if (offset != PAGE_SIZE)
1019                                 continue;
1020                         offset = 0;
1021                         kunmap_atomic(kaddr, KM_USER0);
1022 inside:
1023                         page = bprm->page[bprm->p/PAGE_SIZE];
1024                         kaddr = kmap_atomic(page, KM_USER0);
1025                 }
1026                 kunmap_atomic(kaddr, KM_USER0);
1027                 bprm->argc--;
1028         }
1029 }
1030
1031 EXPORT_SYMBOL(remove_arg_zero);
1032
1033 /*
1034  * cycle the list of binary formats handler, until one recognizes the image
1035  */
1036 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1037 {
1038         int try,retval;
1039         struct linux_binfmt *fmt;
1040 #ifdef __alpha__
1041         /* handle /sbin/loader.. */
1042         {
1043             struct exec * eh = (struct exec *) bprm->buf;
1044
1045             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1046                 (eh->fh.f_flags & 0x3000) == 0x3000)
1047             {
1048                 struct file * file;
1049                 unsigned long loader;
1050
1051                 allow_write_access(bprm->file);
1052                 fput(bprm->file);
1053                 bprm->file = NULL;
1054
1055                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1056
1057                 file = open_exec("/sbin/loader");
1058                 retval = PTR_ERR(file);
1059                 if (IS_ERR(file))
1060                         return retval;
1061
1062                 /* Remember if the application is TASO.  */
1063                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1064
1065                 bprm->file = file;
1066                 bprm->loader = loader;
1067                 retval = prepare_binprm(bprm);
1068                 if (retval<0)
1069                         return retval;
1070                 /* should call search_binary_handler recursively here,
1071                    but it does not matter */
1072             }
1073         }
1074 #endif
1075         retval = security_bprm_check(bprm);
1076         if (retval)
1077                 return retval;
1078
1079         /* kernel module loader fixup */
1080         /* so we don't try to load run modprobe in kernel space. */
1081         set_fs(USER_DS);
1082         retval = -ENOENT;
1083         for (try=0; try<2; try++) {
1084                 read_lock(&binfmt_lock);
1085                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1086                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1087                         if (!fn)
1088                                 continue;
1089                         if (!try_module_get(fmt->module))
1090                                 continue;
1091                         read_unlock(&binfmt_lock);
1092                         retval = fn(bprm, regs);
1093                         if (retval >= 0) {
1094                                 put_binfmt(fmt);
1095                                 allow_write_access(bprm->file);
1096                                 if (bprm->file)
1097                                         fput(bprm->file);
1098                                 bprm->file = NULL;
1099                                 current->did_exec = 1;
1100                                 proc_exec_connector(current);
1101                                 return retval;
1102                         }
1103                         read_lock(&binfmt_lock);
1104                         put_binfmt(fmt);
1105                         if (retval != -ENOEXEC || bprm->mm == NULL)
1106                                 break;
1107                         if (!bprm->file) {
1108                                 read_unlock(&binfmt_lock);
1109                                 return retval;
1110                         }
1111                 }
1112                 read_unlock(&binfmt_lock);
1113                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1114                         break;
1115 #ifdef CONFIG_KMOD
1116                 }else{
1117 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1118                         if (printable(bprm->buf[0]) &&
1119                             printable(bprm->buf[1]) &&
1120                             printable(bprm->buf[2]) &&
1121                             printable(bprm->buf[3]))
1122                                 break; /* -ENOEXEC */
1123                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1124 #endif
1125                 }
1126         }
1127         return retval;
1128 }
1129
1130 EXPORT_SYMBOL(search_binary_handler);
1131
1132 /*
1133  * sys_execve() executes a new program.
1134  */
1135 int do_execve(char * filename,
1136         char __user *__user *argv,
1137         char __user *__user *envp,
1138         struct pt_regs * regs)
1139 {
1140         struct linux_binprm *bprm;
1141         struct file *file;
1142         int retval;
1143         int i;
1144
1145         retval = -ENOMEM;
1146         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1147         if (!bprm)
1148                 goto out_ret;
1149
1150         file = open_exec(filename);
1151         retval = PTR_ERR(file);
1152         if (IS_ERR(file))
1153                 goto out_kfree;
1154
1155         sched_exec();
1156
1157         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1158
1159         bprm->file = file;
1160         bprm->filename = filename;
1161         bprm->interp = filename;
1162         bprm->mm = mm_alloc();
1163         retval = -ENOMEM;
1164         if (!bprm->mm)
1165                 goto out_file;
1166
1167         retval = init_new_context(current, bprm->mm);
1168         if (retval < 0)
1169                 goto out_mm;
1170
1171         bprm->argc = count(argv, bprm->p / sizeof(void *));
1172         if ((retval = bprm->argc) < 0)
1173                 goto out_mm;
1174
1175         bprm->envc = count(envp, bprm->p / sizeof(void *));
1176         if ((retval = bprm->envc) < 0)
1177                 goto out_mm;
1178
1179         retval = security_bprm_alloc(bprm);
1180         if (retval)
1181                 goto out;
1182
1183         retval = prepare_binprm(bprm);
1184         if (retval < 0)
1185                 goto out;
1186
1187         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1188         if (retval < 0)
1189                 goto out;
1190
1191         bprm->exec = bprm->p;
1192         retval = copy_strings(bprm->envc, envp, bprm);
1193         if (retval < 0)
1194                 goto out;
1195
1196         retval = copy_strings(bprm->argc, argv, bprm);
1197         if (retval < 0)
1198                 goto out;
1199
1200         retval = search_binary_handler(bprm,regs);
1201         if (retval >= 0) {
1202                 free_arg_pages(bprm);
1203
1204                 /* execve success */
1205                 security_bprm_free(bprm);
1206                 acct_update_integrals(current);
1207                 kfree(bprm);
1208                 return retval;
1209         }
1210
1211 out:
1212         /* Something went wrong, return the inode and free the argument pages*/
1213         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1214                 struct page * page = bprm->page[i];
1215                 if (page)
1216                         __free_page(page);
1217         }
1218
1219         if (bprm->security)
1220                 security_bprm_free(bprm);
1221
1222 out_mm:
1223         if (bprm->mm)
1224                 mmdrop(bprm->mm);
1225
1226 out_file:
1227         if (bprm->file) {
1228                 allow_write_access(bprm->file);
1229                 fput(bprm->file);
1230         }
1231
1232 out_kfree:
1233         kfree(bprm);
1234
1235 out_ret:
1236         return retval;
1237 }
1238
1239 int set_binfmt(struct linux_binfmt *new)
1240 {
1241         struct linux_binfmt *old = current->binfmt;
1242
1243         if (new) {
1244                 if (!try_module_get(new->module))
1245                         return -1;
1246         }
1247         current->binfmt = new;
1248         if (old)
1249                 module_put(old->module);
1250         return 0;
1251 }
1252
1253 EXPORT_SYMBOL(set_binfmt);
1254
1255 #define CORENAME_MAX_SIZE 64
1256
1257 /* format_corename will inspect the pattern parameter, and output a
1258  * name into corename, which must have space for at least
1259  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1260  */
1261 static void format_corename(char *corename, const char *pattern, long signr)
1262 {
1263         const char *pat_ptr = pattern;
1264         char *out_ptr = corename;
1265         char *const out_end = corename + CORENAME_MAX_SIZE;
1266         int rc;
1267         int pid_in_pattern = 0;
1268
1269         /* Repeat as long as we have more pattern to process and more output
1270            space */
1271         while (*pat_ptr) {
1272                 if (*pat_ptr != '%') {
1273                         if (out_ptr == out_end)
1274                                 goto out;
1275                         *out_ptr++ = *pat_ptr++;
1276                 } else {
1277                         switch (*++pat_ptr) {
1278                         case 0:
1279                                 goto out;
1280                         /* Double percent, output one percent */
1281                         case '%':
1282                                 if (out_ptr == out_end)
1283                                         goto out;
1284                                 *out_ptr++ = '%';
1285                                 break;
1286                         /* pid */
1287                         case 'p':
1288                                 pid_in_pattern = 1;
1289                                 rc = snprintf(out_ptr, out_end - out_ptr,
1290                                               "%d", current->tgid);
1291                                 if (rc > out_end - out_ptr)
1292                                         goto out;
1293                                 out_ptr += rc;
1294                                 break;
1295                         /* uid */
1296                         case 'u':
1297                                 rc = snprintf(out_ptr, out_end - out_ptr,
1298                                               "%d", current->uid);
1299                                 if (rc > out_end - out_ptr)
1300                                         goto out;
1301                                 out_ptr += rc;
1302                                 break;
1303                         /* gid */
1304                         case 'g':
1305                                 rc = snprintf(out_ptr, out_end - out_ptr,
1306                                               "%d", current->gid);
1307                                 if (rc > out_end - out_ptr)
1308                                         goto out;
1309                                 out_ptr += rc;
1310                                 break;
1311                         /* signal that caused the coredump */
1312                         case 's':
1313                                 rc = snprintf(out_ptr, out_end - out_ptr,
1314                                               "%ld", signr);
1315                                 if (rc > out_end - out_ptr)
1316                                         goto out;
1317                                 out_ptr += rc;
1318                                 break;
1319                         /* UNIX time of coredump */
1320                         case 't': {
1321                                 struct timeval tv;
1322                                 do_gettimeofday(&tv);
1323                                 rc = snprintf(out_ptr, out_end - out_ptr,
1324                                               "%lu", tv.tv_sec);
1325                                 if (rc > out_end - out_ptr)
1326                                         goto out;
1327                                 out_ptr += rc;
1328                                 break;
1329                         }
1330                         /* hostname */
1331                         case 'h':
1332                                 down_read(&uts_sem);
1333                                 rc = snprintf(out_ptr, out_end - out_ptr,
1334                                               "%s", system_utsname.nodename);
1335                                 up_read(&uts_sem);
1336                                 if (rc > out_end - out_ptr)
1337                                         goto out;
1338                                 out_ptr += rc;
1339                                 break;
1340                         /* executable */
1341                         case 'e':
1342                                 rc = snprintf(out_ptr, out_end - out_ptr,
1343                                               "%s", current->comm);
1344                                 if (rc > out_end - out_ptr)
1345                                         goto out;
1346                                 out_ptr += rc;
1347                                 break;
1348                         default:
1349                                 break;
1350                         }
1351                         ++pat_ptr;
1352                 }
1353         }
1354         /* Backward compatibility with core_uses_pid:
1355          *
1356          * If core_pattern does not include a %p (as is the default)
1357          * and core_uses_pid is set, then .%pid will be appended to
1358          * the filename */
1359         if (!pid_in_pattern
1360             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1361                 rc = snprintf(out_ptr, out_end - out_ptr,
1362                               ".%d", current->tgid);
1363                 if (rc > out_end - out_ptr)
1364                         goto out;
1365                 out_ptr += rc;
1366         }
1367       out:
1368         *out_ptr = 0;
1369 }
1370
1371 static void zap_threads (struct mm_struct *mm)
1372 {
1373         struct task_struct *g, *p;
1374         struct task_struct *tsk = current;
1375         struct completion *vfork_done = tsk->vfork_done;
1376         int traced = 0;
1377
1378         /*
1379          * Make sure nobody is waiting for us to release the VM,
1380          * otherwise we can deadlock when we wait on each other
1381          */
1382         if (vfork_done) {
1383                 tsk->vfork_done = NULL;
1384                 complete(vfork_done);
1385         }
1386
1387         read_lock(&tasklist_lock);
1388         do_each_thread(g,p)
1389                 if (mm == p->mm && p != tsk) {
1390                         force_sig_specific(SIGKILL, p);
1391                         mm->core_waiters++;
1392                         if (unlikely(p->ptrace) &&
1393                             unlikely(p->parent->mm == mm))
1394                                 traced = 1;
1395                 }
1396         while_each_thread(g,p);
1397
1398         read_unlock(&tasklist_lock);
1399
1400         if (unlikely(traced)) {
1401                 /*
1402                  * We are zapping a thread and the thread it ptraces.
1403                  * If the tracee went into a ptrace stop for exit tracing,
1404                  * we could deadlock since the tracer is waiting for this
1405                  * coredump to finish.  Detach them so they can both die.
1406                  */
1407                 write_lock_irq(&tasklist_lock);
1408                 do_each_thread(g,p) {
1409                         if (mm == p->mm && p != tsk &&
1410                             p->ptrace && p->parent->mm == mm) {
1411                                 __ptrace_detach(p, 0);
1412                         }
1413                 } while_each_thread(g,p);
1414                 write_unlock_irq(&tasklist_lock);
1415         }
1416 }
1417
1418 static void coredump_wait(struct mm_struct *mm)
1419 {
1420         DECLARE_COMPLETION(startup_done);
1421         int core_waiters;
1422
1423         mm->core_startup_done = &startup_done;
1424
1425         zap_threads(mm);
1426         core_waiters = mm->core_waiters;
1427         up_write(&mm->mmap_sem);
1428
1429         if (core_waiters)
1430                 wait_for_completion(&startup_done);
1431         BUG_ON(mm->core_waiters);
1432 }
1433
1434 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1435 {
1436         char corename[CORENAME_MAX_SIZE + 1];
1437         struct mm_struct *mm = current->mm;
1438         struct linux_binfmt * binfmt;
1439         struct inode * inode;
1440         struct file * file;
1441         int retval = 0;
1442         int fsuid = current->fsuid;
1443         int flag = 0;
1444
1445         binfmt = current->binfmt;
1446         if (!binfmt || !binfmt->core_dump)
1447                 goto fail;
1448         down_write(&mm->mmap_sem);
1449         if (!mm->dumpable) {
1450                 up_write(&mm->mmap_sem);
1451                 goto fail;
1452         }
1453
1454         /*
1455          *      We cannot trust fsuid as being the "true" uid of the
1456          *      process nor do we know its entire history. We only know it
1457          *      was tainted so we dump it as root in mode 2.
1458          */
1459         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1460                 flag = O_EXCL;          /* Stop rewrite attacks */
1461                 current->fsuid = 0;     /* Dump root private */
1462         }
1463         mm->dumpable = 0;
1464
1465         retval = -EAGAIN;
1466         spin_lock_irq(&current->sighand->siglock);
1467         if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
1468                 current->signal->flags = SIGNAL_GROUP_EXIT;
1469                 current->signal->group_exit_code = exit_code;
1470                 current->signal->group_stop_count = 0;
1471                 retval = 0;
1472         }
1473         spin_unlock_irq(&current->sighand->siglock);
1474         if (retval) {
1475                 up_write(&mm->mmap_sem);
1476                 goto fail;
1477         }
1478
1479         init_completion(&mm->core_done);
1480         coredump_wait(mm);
1481
1482         /*
1483          * Clear any false indication of pending signals that might
1484          * be seen by the filesystem code called to write the core file.
1485          */
1486         clear_thread_flag(TIF_SIGPENDING);
1487
1488         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1489                 goto fail_unlock;
1490
1491         /*
1492          * lock_kernel() because format_corename() is controlled by sysctl, which
1493          * uses lock_kernel()
1494          */
1495         lock_kernel();
1496         format_corename(corename, core_pattern, signr);
1497         unlock_kernel();
1498         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1499         if (IS_ERR(file))
1500                 goto fail_unlock;
1501         inode = file->f_dentry->d_inode;
1502         if (inode->i_nlink > 1)
1503                 goto close_fail;        /* multiple links - don't dump */
1504         if (d_unhashed(file->f_dentry))
1505                 goto close_fail;
1506
1507         if (!S_ISREG(inode->i_mode))
1508                 goto close_fail;
1509         if (!file->f_op)
1510                 goto close_fail;
1511         if (!file->f_op->write)
1512                 goto close_fail;
1513         if (do_truncate(file->f_dentry, 0, 0, file) != 0)
1514                 goto close_fail;
1515
1516         retval = binfmt->core_dump(signr, regs, file);
1517
1518         if (retval)
1519                 current->signal->group_exit_code |= 0x80;
1520 close_fail:
1521         filp_close(file, NULL);
1522 fail_unlock:
1523         current->fsuid = fsuid;
1524         complete_all(&mm->core_done);
1525 fail:
1526         return retval;
1527 }