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