2e3f7950c185f1206967bd86b6c6a0fd9f64c411
[linux-3.10.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/pid_namespace.h>
42 #include <linux/module.h>
43 #include <linux/namei.h>
44 #include <linux/proc_fs.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/syscalls.h>
49 #include <linux/rmap.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53 #include <linux/signalfd.h>
54
55 #include <asm/uaccess.h>
56 #include <asm/mmu_context.h>
57
58 #ifdef CONFIG_KMOD
59 #include <linux/kmod.h>
60 #endif
61
62 int core_uses_pid;
63 char core_pattern[CORENAME_MAX_SIZE] = "core";
64 int suid_dumpable = 0;
65
66 EXPORT_SYMBOL(suid_dumpable);
67 /* The maximal length of core_pattern is also specified in sysctl.c */
68
69 static struct linux_binfmt *formats;
70 static DEFINE_RWLOCK(binfmt_lock);
71
72 int register_binfmt(struct linux_binfmt * fmt)
73 {
74         struct linux_binfmt ** tmp = &formats;
75
76         if (!fmt)
77                 return -EINVAL;
78         if (fmt->next)
79                 return -EBUSY;
80         write_lock(&binfmt_lock);
81         while (*tmp) {
82                 if (fmt == *tmp) {
83                         write_unlock(&binfmt_lock);
84                         return -EBUSY;
85                 }
86                 tmp = &(*tmp)->next;
87         }
88         fmt->next = formats;
89         formats = fmt;
90         write_unlock(&binfmt_lock);
91         return 0;       
92 }
93
94 EXPORT_SYMBOL(register_binfmt);
95
96 int unregister_binfmt(struct linux_binfmt * fmt)
97 {
98         struct linux_binfmt ** tmp = &formats;
99
100         write_lock(&binfmt_lock);
101         while (*tmp) {
102                 if (fmt == *tmp) {
103                         *tmp = fmt->next;
104                         fmt->next = NULL;
105                         write_unlock(&binfmt_lock);
106                         return 0;
107                 }
108                 tmp = &(*tmp)->next;
109         }
110         write_unlock(&binfmt_lock);
111         return -EINVAL;
112 }
113
114 EXPORT_SYMBOL(unregister_binfmt);
115
116 static inline void put_binfmt(struct linux_binfmt * fmt)
117 {
118         module_put(fmt->module);
119 }
120
121 /*
122  * Note that a shared library must be both readable and executable due to
123  * security reasons.
124  *
125  * Also note that we take the address to load from from the file itself.
126  */
127 asmlinkage long sys_uselib(const char __user * library)
128 {
129         struct file * file;
130         struct nameidata nd;
131         int error;
132
133         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
134         if (error)
135                 goto out;
136
137         error = -EACCES;
138         if (nd.mnt->mnt_flags & MNT_NOEXEC)
139                 goto exit;
140         error = -EINVAL;
141         if (!S_ISREG(nd.dentry->d_inode->i_mode))
142                 goto exit;
143
144         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
145         if (error)
146                 goto exit;
147
148         file = nameidata_to_filp(&nd, O_RDONLY);
149         error = PTR_ERR(file);
150         if (IS_ERR(file))
151                 goto out;
152
153         error = -ENOEXEC;
154         if(file->f_op) {
155                 struct linux_binfmt * fmt;
156
157                 read_lock(&binfmt_lock);
158                 for (fmt = formats ; fmt ; fmt = fmt->next) {
159                         if (!fmt->load_shlib)
160                                 continue;
161                         if (!try_module_get(fmt->module))
162                                 continue;
163                         read_unlock(&binfmt_lock);
164                         error = fmt->load_shlib(file);
165                         read_lock(&binfmt_lock);
166                         put_binfmt(fmt);
167                         if (error != -ENOEXEC)
168                                 break;
169                 }
170                 read_unlock(&binfmt_lock);
171         }
172         fput(file);
173 out:
174         return error;
175 exit:
176         release_open_intent(&nd);
177         path_release(&nd);
178         goto out;
179 }
180
181 /*
182  * count() counts the number of strings in array ARGV.
183  */
184 static int count(char __user * __user * argv, int max)
185 {
186         int i = 0;
187
188         if (argv != NULL) {
189                 for (;;) {
190                         char __user * p;
191
192                         if (get_user(p, argv))
193                                 return -EFAULT;
194                         if (!p)
195                                 break;
196                         argv++;
197                         if(++i > max)
198                                 return -E2BIG;
199                         cond_resched();
200                 }
201         }
202         return i;
203 }
204
205 /*
206  * 'copy_strings()' copies argument/environment strings from user
207  * memory to free pages in kernel mem. These are in a format ready
208  * to be put directly into the top of new user memory.
209  */
210 static int copy_strings(int argc, char __user * __user * argv,
211                         struct linux_binprm *bprm)
212 {
213         struct page *kmapped_page = NULL;
214         char *kaddr = NULL;
215         int ret;
216
217         while (argc-- > 0) {
218                 char __user *str;
219                 int len;
220                 unsigned long pos;
221
222                 if (get_user(str, argv+argc) ||
223                                 !(len = strnlen_user(str, bprm->p))) {
224                         ret = -EFAULT;
225                         goto out;
226                 }
227
228                 if (bprm->p < len)  {
229                         ret = -E2BIG;
230                         goto out;
231                 }
232
233                 bprm->p -= len;
234                 /* XXX: add architecture specific overflow check here. */
235                 pos = bprm->p;
236
237                 while (len > 0) {
238                         int i, new, err;
239                         int offset, bytes_to_copy;
240                         struct page *page;
241
242                         offset = pos % PAGE_SIZE;
243                         i = pos/PAGE_SIZE;
244                         page = bprm->page[i];
245                         new = 0;
246                         if (!page) {
247                                 page = alloc_page(GFP_HIGHUSER);
248                                 bprm->page[i] = page;
249                                 if (!page) {
250                                         ret = -ENOMEM;
251                                         goto out;
252                                 }
253                                 new = 1;
254                         }
255
256                         if (page != kmapped_page) {
257                                 if (kmapped_page)
258                                         kunmap(kmapped_page);
259                                 kmapped_page = page;
260                                 kaddr = kmap(kmapped_page);
261                         }
262                         if (new && offset)
263                                 memset(kaddr, 0, offset);
264                         bytes_to_copy = PAGE_SIZE - offset;
265                         if (bytes_to_copy > len) {
266                                 bytes_to_copy = len;
267                                 if (new)
268                                         memset(kaddr+offset+len, 0,
269                                                 PAGE_SIZE-offset-len);
270                         }
271                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
272                         if (err) {
273                                 ret = -EFAULT;
274                                 goto out;
275                         }
276
277                         pos += bytes_to_copy;
278                         str += bytes_to_copy;
279                         len -= bytes_to_copy;
280                 }
281         }
282         ret = 0;
283 out:
284         if (kmapped_page)
285                 kunmap(kmapped_page);
286         return ret;
287 }
288
289 /*
290  * Like copy_strings, but get argv and its values from kernel memory.
291  */
292 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
293 {
294         int r;
295         mm_segment_t oldfs = get_fs();
296         set_fs(KERNEL_DS);
297         r = copy_strings(argc, (char __user * __user *)argv, bprm);
298         set_fs(oldfs);
299         return r;
300 }
301
302 EXPORT_SYMBOL(copy_strings_kernel);
303
304 #ifdef CONFIG_MMU
305 /*
306  * This routine is used to map in a page into an address space: needed by
307  * execve() for the initial stack and environment pages.
308  *
309  * vma->vm_mm->mmap_sem is held for writing.
310  */
311 void install_arg_page(struct vm_area_struct *vma,
312                         struct page *page, unsigned long address)
313 {
314         struct mm_struct *mm = vma->vm_mm;
315         pte_t * pte;
316         spinlock_t *ptl;
317
318         if (unlikely(anon_vma_prepare(vma)))
319                 goto out;
320
321         flush_dcache_page(page);
322         pte = get_locked_pte(mm, address, &ptl);
323         if (!pte)
324                 goto out;
325         if (!pte_none(*pte)) {
326                 pte_unmap_unlock(pte, ptl);
327                 goto out;
328         }
329         inc_mm_counter(mm, anon_rss);
330         lru_cache_add_active(page);
331         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
332                                         page, vma->vm_page_prot))));
333         page_add_new_anon_rmap(page, vma, address);
334         pte_unmap_unlock(pte, ptl);
335
336         /* no need for flush_tlb */
337         return;
338 out:
339         __free_page(page);
340         force_sig(SIGKILL, current);
341 }
342
343 #define EXTRA_STACK_VM_PAGES    20      /* random */
344
345 int setup_arg_pages(struct linux_binprm *bprm,
346                     unsigned long stack_top,
347                     int executable_stack)
348 {
349         unsigned long stack_base;
350         struct vm_area_struct *mpnt;
351         struct mm_struct *mm = current->mm;
352         int i, ret;
353         long arg_size;
354
355 #ifdef CONFIG_STACK_GROWSUP
356         /* Move the argument and environment strings to the bottom of the
357          * stack space.
358          */
359         int offset, j;
360         char *to, *from;
361
362         /* Start by shifting all the pages down */
363         i = 0;
364         for (j = 0; j < MAX_ARG_PAGES; j++) {
365                 struct page *page = bprm->page[j];
366                 if (!page)
367                         continue;
368                 bprm->page[i++] = page;
369         }
370
371         /* Now move them within their pages */
372         offset = bprm->p % PAGE_SIZE;
373         to = kmap(bprm->page[0]);
374         for (j = 1; j < i; j++) {
375                 memmove(to, to + offset, PAGE_SIZE - offset);
376                 from = kmap(bprm->page[j]);
377                 memcpy(to + PAGE_SIZE - offset, from, offset);
378                 kunmap(bprm->page[j - 1]);
379                 to = from;
380         }
381         memmove(to, to + offset, PAGE_SIZE - offset);
382         kunmap(bprm->page[j - 1]);
383
384         /* Limit stack size to 1GB */
385         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
386         if (stack_base > (1 << 30))
387                 stack_base = 1 << 30;
388         stack_base = PAGE_ALIGN(stack_top - stack_base);
389
390         /* Adjust bprm->p to point to the end of the strings. */
391         bprm->p = stack_base + PAGE_SIZE * i - offset;
392
393         mm->arg_start = stack_base;
394         arg_size = i << PAGE_SHIFT;
395
396         /* zero pages that were copied above */
397         while (i < MAX_ARG_PAGES)
398                 bprm->page[i++] = NULL;
399 #else
400         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
401         stack_base = PAGE_ALIGN(stack_base);
402         bprm->p += stack_base;
403         mm->arg_start = bprm->p;
404         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
405 #endif
406
407         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
408
409         if (bprm->loader)
410                 bprm->loader += stack_base;
411         bprm->exec += stack_base;
412
413         mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
414         if (!mpnt)
415                 return -ENOMEM;
416
417         down_write(&mm->mmap_sem);
418         {
419                 mpnt->vm_mm = mm;
420 #ifdef CONFIG_STACK_GROWSUP
421                 mpnt->vm_start = stack_base;
422                 mpnt->vm_end = stack_base + arg_size;
423 #else
424                 mpnt->vm_end = stack_top;
425                 mpnt->vm_start = mpnt->vm_end - arg_size;
426 #endif
427                 /* Adjust stack execute permissions; explicitly enable
428                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
429                  * and leave alone (arch default) otherwise. */
430                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
431                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
432                 else if (executable_stack == EXSTACK_DISABLE_X)
433                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
434                 else
435                         mpnt->vm_flags = VM_STACK_FLAGS;
436                 mpnt->vm_flags |= mm->def_flags;
437                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
438                 if ((ret = insert_vm_struct(mm, mpnt))) {
439                         up_write(&mm->mmap_sem);
440                         kmem_cache_free(vm_area_cachep, mpnt);
441                         return ret;
442                 }
443                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
444         }
445
446         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
447                 struct page *page = bprm->page[i];
448                 if (page) {
449                         bprm->page[i] = NULL;
450                         install_arg_page(mpnt, page, stack_base);
451                 }
452                 stack_base += PAGE_SIZE;
453         }
454         up_write(&mm->mmap_sem);
455         
456         return 0;
457 }
458
459 EXPORT_SYMBOL(setup_arg_pages);
460
461 #define free_arg_pages(bprm) do { } while (0)
462
463 #else
464
465 static inline void free_arg_pages(struct linux_binprm *bprm)
466 {
467         int i;
468
469         for (i = 0; i < MAX_ARG_PAGES; i++) {
470                 if (bprm->page[i])
471                         __free_page(bprm->page[i]);
472                 bprm->page[i] = NULL;
473         }
474 }
475
476 #endif /* CONFIG_MMU */
477
478 struct file *open_exec(const char *name)
479 {
480         struct nameidata nd;
481         int err;
482         struct file *file;
483
484         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
485         file = ERR_PTR(err);
486
487         if (!err) {
488                 struct inode *inode = nd.dentry->d_inode;
489                 file = ERR_PTR(-EACCES);
490                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
491                     S_ISREG(inode->i_mode)) {
492                         int err = vfs_permission(&nd, MAY_EXEC);
493                         file = ERR_PTR(err);
494                         if (!err) {
495                                 file = nameidata_to_filp(&nd, O_RDONLY);
496                                 if (!IS_ERR(file)) {
497                                         err = deny_write_access(file);
498                                         if (err) {
499                                                 fput(file);
500                                                 file = ERR_PTR(err);
501                                         }
502                                 }
503 out:
504                                 return file;
505                         }
506                 }
507                 release_open_intent(&nd);
508                 path_release(&nd);
509         }
510         goto out;
511 }
512
513 EXPORT_SYMBOL(open_exec);
514
515 int kernel_read(struct file *file, unsigned long offset,
516         char *addr, unsigned long count)
517 {
518         mm_segment_t old_fs;
519         loff_t pos = offset;
520         int result;
521
522         old_fs = get_fs();
523         set_fs(get_ds());
524         /* The cast to a user pointer is valid due to the set_fs() */
525         result = vfs_read(file, (void __user *)addr, count, &pos);
526         set_fs(old_fs);
527         return result;
528 }
529
530 EXPORT_SYMBOL(kernel_read);
531
532 static int exec_mmap(struct mm_struct *mm)
533 {
534         struct task_struct *tsk;
535         struct mm_struct * old_mm, *active_mm;
536
537         /* Notify parent that we're no longer interested in the old VM */
538         tsk = current;
539         old_mm = current->mm;
540         mm_release(tsk, old_mm);
541
542         if (old_mm) {
543                 /*
544                  * Make sure that if there is a core dump in progress
545                  * for the old mm, we get out and die instead of going
546                  * through with the exec.  We must hold mmap_sem around
547                  * checking core_waiters and changing tsk->mm.  The
548                  * core-inducing thread will increment core_waiters for
549                  * each thread whose ->mm == old_mm.
550                  */
551                 down_read(&old_mm->mmap_sem);
552                 if (unlikely(old_mm->core_waiters)) {
553                         up_read(&old_mm->mmap_sem);
554                         return -EINTR;
555                 }
556         }
557         task_lock(tsk);
558         active_mm = tsk->active_mm;
559         tsk->mm = mm;
560         tsk->active_mm = mm;
561         activate_mm(active_mm, mm);
562         task_unlock(tsk);
563         arch_pick_mmap_layout(mm);
564         if (old_mm) {
565                 up_read(&old_mm->mmap_sem);
566                 BUG_ON(active_mm != old_mm);
567                 mmput(old_mm);
568                 return 0;
569         }
570         mmdrop(active_mm);
571         return 0;
572 }
573
574 /*
575  * This function makes sure the current process has its own signal table,
576  * so that flush_signal_handlers can later reset the handlers without
577  * disturbing other processes.  (Other processes might share the signal
578  * table via the CLONE_SIGHAND option to clone().)
579  */
580 static int de_thread(struct task_struct *tsk)
581 {
582         struct signal_struct *sig = tsk->signal;
583         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
584         spinlock_t *lock = &oldsighand->siglock;
585         struct task_struct *leader = NULL;
586         int count;
587
588         /*
589          * Tell all the sighand listeners that this sighand has
590          * been detached. The signalfd_detach() function grabs the
591          * sighand lock, if signal listeners are present on the sighand.
592          */
593         signalfd_detach(tsk);
594
595         /*
596          * If we don't share sighandlers, then we aren't sharing anything
597          * and we can just re-use it all.
598          */
599         if (atomic_read(&oldsighand->count) <= 1) {
600                 BUG_ON(atomic_read(&sig->count) != 1);
601                 exit_itimers(sig);
602                 return 0;
603         }
604
605         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
606         if (!newsighand)
607                 return -ENOMEM;
608
609         if (thread_group_empty(tsk))
610                 goto no_thread_group;
611
612         /*
613          * Kill all other threads in the thread group.
614          * We must hold tasklist_lock to call zap_other_threads.
615          */
616         read_lock(&tasklist_lock);
617         spin_lock_irq(lock);
618         if (sig->flags & SIGNAL_GROUP_EXIT) {
619                 /*
620                  * Another group action in progress, just
621                  * return so that the signal is processed.
622                  */
623                 spin_unlock_irq(lock);
624                 read_unlock(&tasklist_lock);
625                 kmem_cache_free(sighand_cachep, newsighand);
626                 return -EAGAIN;
627         }
628
629         /*
630          * child_reaper ignores SIGKILL, change it now.
631          * Reparenting needs write_lock on tasklist_lock,
632          * so it is safe to do it under read_lock.
633          */
634         if (unlikely(tsk->group_leader == child_reaper(tsk)))
635                 tsk->nsproxy->pid_ns->child_reaper = tsk;
636
637         zap_other_threads(tsk);
638         read_unlock(&tasklist_lock);
639
640         /*
641          * Account for the thread group leader hanging around:
642          */
643         count = 1;
644         if (!thread_group_leader(tsk)) {
645                 count = 2;
646                 /*
647                  * The SIGALRM timer survives the exec, but needs to point
648                  * at us as the new group leader now.  We have a race with
649                  * a timer firing now getting the old leader, so we need to
650                  * synchronize with any firing (by calling del_timer_sync)
651                  * before we can safely let the old group leader die.
652                  */
653                 sig->tsk = tsk;
654                 spin_unlock_irq(lock);
655                 if (hrtimer_cancel(&sig->real_timer))
656                         hrtimer_restart(&sig->real_timer);
657                 spin_lock_irq(lock);
658         }
659         while (atomic_read(&sig->count) > count) {
660                 sig->group_exit_task = tsk;
661                 sig->notify_count = count;
662                 __set_current_state(TASK_UNINTERRUPTIBLE);
663                 spin_unlock_irq(lock);
664                 schedule();
665                 spin_lock_irq(lock);
666         }
667         sig->group_exit_task = NULL;
668         sig->notify_count = 0;
669         spin_unlock_irq(lock);
670
671         /*
672          * At this point all other threads have exited, all we have to
673          * do is to wait for the thread group leader to become inactive,
674          * and to assume its PID:
675          */
676         if (!thread_group_leader(tsk)) {
677                 /*
678                  * Wait for the thread group leader to be a zombie.
679                  * It should already be zombie at this point, most
680                  * of the time.
681                  */
682                 leader = tsk->group_leader;
683                 while (leader->exit_state != EXIT_ZOMBIE)
684                         yield();
685
686                 /*
687                  * The only record we have of the real-time age of a
688                  * process, regardless of execs it's done, is start_time.
689                  * All the past CPU time is accumulated in signal_struct
690                  * from sister threads now dead.  But in this non-leader
691                  * exec, nothing survives from the original leader thread,
692                  * whose birth marks the true age of this process now.
693                  * When we take on its identity by switching to its PID, we
694                  * also take its birthdate (always earlier than our own).
695                  */
696                 tsk->start_time = leader->start_time;
697
698                 write_lock_irq(&tasklist_lock);
699
700                 BUG_ON(leader->tgid != tsk->tgid);
701                 BUG_ON(tsk->pid == tsk->tgid);
702                 /*
703                  * An exec() starts a new thread group with the
704                  * TGID of the previous thread group. Rehash the
705                  * two threads with a switched PID, and release
706                  * the former thread group leader:
707                  */
708
709                 /* Become a process group leader with the old leader's pid.
710                  * The old leader becomes a thread of the this thread group.
711                  * Note: The old leader also uses this pid until release_task
712                  *       is called.  Odd but simple and correct.
713                  */
714                 detach_pid(tsk, PIDTYPE_PID);
715                 tsk->pid = leader->pid;
716                 attach_pid(tsk, PIDTYPE_PID,  find_pid(tsk->pid));
717                 transfer_pid(leader, tsk, PIDTYPE_PGID);
718                 transfer_pid(leader, tsk, PIDTYPE_SID);
719                 list_replace_rcu(&leader->tasks, &tsk->tasks);
720
721                 tsk->group_leader = tsk;
722                 leader->group_leader = tsk;
723
724                 tsk->exit_signal = SIGCHLD;
725
726                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
727                 leader->exit_state = EXIT_DEAD;
728
729                 write_unlock_irq(&tasklist_lock);
730         }
731
732         /*
733          * There may be one thread left which is just exiting,
734          * but it's safe to stop telling the group to kill themselves.
735          */
736         sig->flags = 0;
737
738 no_thread_group:
739         exit_itimers(sig);
740         if (leader)
741                 release_task(leader);
742
743         BUG_ON(atomic_read(&sig->count) != 1);
744
745         if (atomic_read(&oldsighand->count) == 1) {
746                 /*
747                  * Now that we nuked the rest of the thread group,
748                  * it turns out we are not sharing sighand any more either.
749                  * So we can just keep it.
750                  */
751                 kmem_cache_free(sighand_cachep, newsighand);
752         } else {
753                 /*
754                  * Move our state over to newsighand and switch it in.
755                  */
756                 atomic_set(&newsighand->count, 1);
757                 memcpy(newsighand->action, oldsighand->action,
758                        sizeof(newsighand->action));
759
760                 write_lock_irq(&tasklist_lock);
761                 spin_lock(&oldsighand->siglock);
762                 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
763
764                 rcu_assign_pointer(tsk->sighand, newsighand);
765                 recalc_sigpending();
766
767                 spin_unlock(&newsighand->siglock);
768                 spin_unlock(&oldsighand->siglock);
769                 write_unlock_irq(&tasklist_lock);
770
771                 __cleanup_sighand(oldsighand);
772         }
773
774         BUG_ON(!thread_group_leader(tsk));
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)
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         put_files_struct(files);
863
864         current->sas_ss_sp = current->sas_ss_size = 0;
865
866         if (current->euid == current->uid && current->egid == current->gid)
867                 current->mm->dumpable = 1;
868         else
869                 current->mm->dumpable = suid_dumpable;
870
871         name = bprm->filename;
872
873         /* Copies the binary name from after last slash */
874         for (i=0; (ch = *(name++)) != '\0';) {
875                 if (ch == '/')
876                         i = 0; /* overwrite what we wrote */
877                 else
878                         if (i < (sizeof(tcomm) - 1))
879                                 tcomm[i++] = ch;
880         }
881         tcomm[i] = '\0';
882         set_task_comm(current, tcomm);
883
884         current->flags &= ~PF_RANDOMIZE;
885         flush_thread();
886
887         /* Set the new mm task size. We have to do that late because it may
888          * depend on TIF_32BIT which is only updated in flush_thread() on
889          * some architectures like powerpc
890          */
891         current->mm->task_size = TASK_SIZE;
892
893         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
894             file_permission(bprm->file, MAY_READ) ||
895             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
896                 suid_keys(current);
897                 current->mm->dumpable = suid_dumpable;
898         }
899
900         /* An exec changes our domain. We are no longer part of the thread
901            group */
902
903         current->self_exec_id++;
904                         
905         flush_signal_handlers(current, 0);
906         flush_old_files(current->files);
907
908         return 0;
909
910 mmap_failed:
911         reset_files_struct(current, files);
912 out:
913         return retval;
914 }
915
916 EXPORT_SYMBOL(flush_old_exec);
917
918 /* 
919  * Fill the binprm structure from the inode. 
920  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
921  */
922 int prepare_binprm(struct linux_binprm *bprm)
923 {
924         int mode;
925         struct inode * inode = bprm->file->f_path.dentry->d_inode;
926         int retval;
927
928         mode = inode->i_mode;
929         if (bprm->file->f_op == NULL)
930                 return -EACCES;
931
932         bprm->e_uid = current->euid;
933         bprm->e_gid = current->egid;
934
935         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
936                 /* Set-uid? */
937                 if (mode & S_ISUID) {
938                         current->personality &= ~PER_CLEAR_ON_SETID;
939                         bprm->e_uid = inode->i_uid;
940                 }
941
942                 /* Set-gid? */
943                 /*
944                  * If setgid is set but no group execute bit then this
945                  * is a candidate for mandatory locking, not a setgid
946                  * executable.
947                  */
948                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
949                         current->personality &= ~PER_CLEAR_ON_SETID;
950                         bprm->e_gid = inode->i_gid;
951                 }
952         }
953
954         /* fill in binprm security blob */
955         retval = security_bprm_set(bprm);
956         if (retval)
957                 return retval;
958
959         memset(bprm->buf,0,BINPRM_BUF_SIZE);
960         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
961 }
962
963 EXPORT_SYMBOL(prepare_binprm);
964
965 static int unsafe_exec(struct task_struct *p)
966 {
967         int unsafe = 0;
968         if (p->ptrace & PT_PTRACED) {
969                 if (p->ptrace & PT_PTRACE_CAP)
970                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
971                 else
972                         unsafe |= LSM_UNSAFE_PTRACE;
973         }
974         if (atomic_read(&p->fs->count) > 1 ||
975             atomic_read(&p->files->count) > 1 ||
976             atomic_read(&p->sighand->count) > 1)
977                 unsafe |= LSM_UNSAFE_SHARE;
978
979         return unsafe;
980 }
981
982 void compute_creds(struct linux_binprm *bprm)
983 {
984         int unsafe;
985
986         if (bprm->e_uid != current->uid)
987                 suid_keys(current);
988         exec_keys(current);
989
990         task_lock(current);
991         unsafe = unsafe_exec(current);
992         security_bprm_apply_creds(bprm, unsafe);
993         task_unlock(current);
994         security_bprm_post_apply_creds(bprm);
995 }
996 EXPORT_SYMBOL(compute_creds);
997
998 /*
999  * Arguments are '\0' separated strings found at the location bprm->p
1000  * points to; chop off the first by relocating brpm->p to right after
1001  * the first '\0' encountered.
1002  */
1003 void remove_arg_zero(struct linux_binprm *bprm)
1004 {
1005         if (bprm->argc) {
1006                 char ch;
1007
1008                 do {
1009                         unsigned long offset;
1010                         unsigned long index;
1011                         char *kaddr;
1012                         struct page *page;
1013
1014                         offset = bprm->p & ~PAGE_MASK;
1015                         index = bprm->p >> PAGE_SHIFT;
1016
1017                         page = bprm->page[index];
1018                         kaddr = kmap_atomic(page, KM_USER0);
1019
1020                         /* run through page until we reach end or find NUL */
1021                         do {
1022                                 ch = *(kaddr + offset);
1023
1024                                 /* discard that character... */
1025                                 bprm->p++;
1026                                 offset++;
1027                         } while (offset < PAGE_SIZE && ch != '\0');
1028
1029                         kunmap_atomic(kaddr, KM_USER0);
1030
1031                         /* free the old page */
1032                         if (offset == PAGE_SIZE) {
1033                                 __free_page(page);
1034                                 bprm->page[index] = NULL;
1035                         }
1036                 } while (ch != '\0');
1037
1038                 bprm->argc--;
1039         }
1040 }
1041 EXPORT_SYMBOL(remove_arg_zero);
1042
1043 /*
1044  * cycle the list of binary formats handler, until one recognizes the image
1045  */
1046 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1047 {
1048         int try,retval;
1049         struct linux_binfmt *fmt;
1050 #ifdef __alpha__
1051         /* handle /sbin/loader.. */
1052         {
1053             struct exec * eh = (struct exec *) bprm->buf;
1054
1055             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1056                 (eh->fh.f_flags & 0x3000) == 0x3000)
1057             {
1058                 struct file * file;
1059                 unsigned long loader;
1060
1061                 allow_write_access(bprm->file);
1062                 fput(bprm->file);
1063                 bprm->file = NULL;
1064
1065                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1066
1067                 file = open_exec("/sbin/loader");
1068                 retval = PTR_ERR(file);
1069                 if (IS_ERR(file))
1070                         return retval;
1071
1072                 /* Remember if the application is TASO.  */
1073                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1074
1075                 bprm->file = file;
1076                 bprm->loader = loader;
1077                 retval = prepare_binprm(bprm);
1078                 if (retval<0)
1079                         return retval;
1080                 /* should call search_binary_handler recursively here,
1081                    but it does not matter */
1082             }
1083         }
1084 #endif
1085         retval = security_bprm_check(bprm);
1086         if (retval)
1087                 return retval;
1088
1089         /* kernel module loader fixup */
1090         /* so we don't try to load run modprobe in kernel space. */
1091         set_fs(USER_DS);
1092
1093         retval = audit_bprm(bprm);
1094         if (retval)
1095                 return retval;
1096
1097         retval = -ENOENT;
1098         for (try=0; try<2; try++) {
1099                 read_lock(&binfmt_lock);
1100                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1101                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1102                         if (!fn)
1103                                 continue;
1104                         if (!try_module_get(fmt->module))
1105                                 continue;
1106                         read_unlock(&binfmt_lock);
1107                         retval = fn(bprm, regs);
1108                         if (retval >= 0) {
1109                                 put_binfmt(fmt);
1110                                 allow_write_access(bprm->file);
1111                                 if (bprm->file)
1112                                         fput(bprm->file);
1113                                 bprm->file = NULL;
1114                                 current->did_exec = 1;
1115                                 proc_exec_connector(current);
1116                                 return retval;
1117                         }
1118                         read_lock(&binfmt_lock);
1119                         put_binfmt(fmt);
1120                         if (retval != -ENOEXEC || bprm->mm == NULL)
1121                                 break;
1122                         if (!bprm->file) {
1123                                 read_unlock(&binfmt_lock);
1124                                 return retval;
1125                         }
1126                 }
1127                 read_unlock(&binfmt_lock);
1128                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1129                         break;
1130 #ifdef CONFIG_KMOD
1131                 }else{
1132 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1133                         if (printable(bprm->buf[0]) &&
1134                             printable(bprm->buf[1]) &&
1135                             printable(bprm->buf[2]) &&
1136                             printable(bprm->buf[3]))
1137                                 break; /* -ENOEXEC */
1138                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1139 #endif
1140                 }
1141         }
1142         return retval;
1143 }
1144
1145 EXPORT_SYMBOL(search_binary_handler);
1146
1147 /*
1148  * sys_execve() executes a new program.
1149  */
1150 int do_execve(char * filename,
1151         char __user *__user *argv,
1152         char __user *__user *envp,
1153         struct pt_regs * regs)
1154 {
1155         struct linux_binprm *bprm;
1156         struct file *file;
1157         unsigned long env_p;
1158         int retval;
1159         int i;
1160
1161         retval = -ENOMEM;
1162         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1163         if (!bprm)
1164                 goto out_ret;
1165
1166         file = open_exec(filename);
1167         retval = PTR_ERR(file);
1168         if (IS_ERR(file))
1169                 goto out_kfree;
1170
1171         sched_exec();
1172
1173         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1174
1175         bprm->file = file;
1176         bprm->filename = filename;
1177         bprm->interp = filename;
1178         bprm->mm = mm_alloc();
1179         retval = -ENOMEM;
1180         if (!bprm->mm)
1181                 goto out_file;
1182
1183         retval = init_new_context(current, bprm->mm);
1184         if (retval < 0)
1185                 goto out_mm;
1186
1187         bprm->argc = count(argv, bprm->p / sizeof(void *));
1188         if ((retval = bprm->argc) < 0)
1189                 goto out_mm;
1190
1191         bprm->envc = count(envp, bprm->p / sizeof(void *));
1192         if ((retval = bprm->envc) < 0)
1193                 goto out_mm;
1194
1195         retval = security_bprm_alloc(bprm);
1196         if (retval)
1197                 goto out;
1198
1199         retval = prepare_binprm(bprm);
1200         if (retval < 0)
1201                 goto out;
1202
1203         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1204         if (retval < 0)
1205                 goto out;
1206
1207         bprm->exec = bprm->p;
1208         retval = copy_strings(bprm->envc, envp, bprm);
1209         if (retval < 0)
1210                 goto out;
1211
1212         env_p = bprm->p;
1213         retval = copy_strings(bprm->argc, argv, bprm);
1214         if (retval < 0)
1215                 goto out;
1216         bprm->argv_len = env_p - bprm->p;
1217
1218         retval = search_binary_handler(bprm,regs);
1219         if (retval >= 0) {
1220                 free_arg_pages(bprm);
1221
1222                 /* execve success */
1223                 security_bprm_free(bprm);
1224                 acct_update_integrals(current);
1225                 kfree(bprm);
1226                 return retval;
1227         }
1228
1229 out:
1230         /* Something went wrong, return the inode and free the argument pages*/
1231         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1232                 struct page * page = bprm->page[i];
1233                 if (page)
1234                         __free_page(page);
1235         }
1236
1237         if (bprm->security)
1238                 security_bprm_free(bprm);
1239
1240 out_mm:
1241         if (bprm->mm)
1242                 mmdrop(bprm->mm);
1243
1244 out_file:
1245         if (bprm->file) {
1246                 allow_write_access(bprm->file);
1247                 fput(bprm->file);
1248         }
1249
1250 out_kfree:
1251         kfree(bprm);
1252
1253 out_ret:
1254         return retval;
1255 }
1256
1257 int set_binfmt(struct linux_binfmt *new)
1258 {
1259         struct linux_binfmt *old = current->binfmt;
1260
1261         if (new) {
1262                 if (!try_module_get(new->module))
1263                         return -1;
1264         }
1265         current->binfmt = new;
1266         if (old)
1267                 module_put(old->module);
1268         return 0;
1269 }
1270
1271 EXPORT_SYMBOL(set_binfmt);
1272
1273 /* format_corename will inspect the pattern parameter, and output a
1274  * name into corename, which must have space for at least
1275  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1276  */
1277 static int format_corename(char *corename, const char *pattern, long signr)
1278 {
1279         const char *pat_ptr = pattern;
1280         char *out_ptr = corename;
1281         char *const out_end = corename + CORENAME_MAX_SIZE;
1282         int rc;
1283         int pid_in_pattern = 0;
1284         int ispipe = 0;
1285
1286         if (*pattern == '|')
1287                 ispipe = 1;
1288
1289         /* Repeat as long as we have more pattern to process and more output
1290            space */
1291         while (*pat_ptr) {
1292                 if (*pat_ptr != '%') {
1293                         if (out_ptr == out_end)
1294                                 goto out;
1295                         *out_ptr++ = *pat_ptr++;
1296                 } else {
1297                         switch (*++pat_ptr) {
1298                         case 0:
1299                                 goto out;
1300                         /* Double percent, output one percent */
1301                         case '%':
1302                                 if (out_ptr == out_end)
1303                                         goto out;
1304                                 *out_ptr++ = '%';
1305                                 break;
1306                         /* pid */
1307                         case 'p':
1308                                 pid_in_pattern = 1;
1309                                 rc = snprintf(out_ptr, out_end - out_ptr,
1310                                               "%d", current->tgid);
1311                                 if (rc > out_end - out_ptr)
1312                                         goto out;
1313                                 out_ptr += rc;
1314                                 break;
1315                         /* uid */
1316                         case 'u':
1317                                 rc = snprintf(out_ptr, out_end - out_ptr,
1318                                               "%d", current->uid);
1319                                 if (rc > out_end - out_ptr)
1320                                         goto out;
1321                                 out_ptr += rc;
1322                                 break;
1323                         /* gid */
1324                         case 'g':
1325                                 rc = snprintf(out_ptr, out_end - out_ptr,
1326                                               "%d", current->gid);
1327                                 if (rc > out_end - out_ptr)
1328                                         goto out;
1329                                 out_ptr += rc;
1330                                 break;
1331                         /* signal that caused the coredump */
1332                         case 's':
1333                                 rc = snprintf(out_ptr, out_end - out_ptr,
1334                                               "%ld", signr);
1335                                 if (rc > out_end - out_ptr)
1336                                         goto out;
1337                                 out_ptr += rc;
1338                                 break;
1339                         /* UNIX time of coredump */
1340                         case 't': {
1341                                 struct timeval tv;
1342                                 do_gettimeofday(&tv);
1343                                 rc = snprintf(out_ptr, out_end - out_ptr,
1344                                               "%lu", tv.tv_sec);
1345                                 if (rc > out_end - out_ptr)
1346                                         goto out;
1347                                 out_ptr += rc;
1348                                 break;
1349                         }
1350                         /* hostname */
1351                         case 'h':
1352                                 down_read(&uts_sem);
1353                                 rc = snprintf(out_ptr, out_end - out_ptr,
1354                                               "%s", utsname()->nodename);
1355                                 up_read(&uts_sem);
1356                                 if (rc > out_end - out_ptr)
1357                                         goto out;
1358                                 out_ptr += rc;
1359                                 break;
1360                         /* executable */
1361                         case 'e':
1362                                 rc = snprintf(out_ptr, out_end - out_ptr,
1363                                               "%s", current->comm);
1364                                 if (rc > out_end - out_ptr)
1365                                         goto out;
1366                                 out_ptr += rc;
1367                                 break;
1368                         default:
1369                                 break;
1370                         }
1371                         ++pat_ptr;
1372                 }
1373         }
1374         /* Backward compatibility with core_uses_pid:
1375          *
1376          * If core_pattern does not include a %p (as is the default)
1377          * and core_uses_pid is set, then .%pid will be appended to
1378          * the filename. Do not do this for piped commands. */
1379         if (!ispipe && !pid_in_pattern
1380             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1381                 rc = snprintf(out_ptr, out_end - out_ptr,
1382                               ".%d", current->tgid);
1383                 if (rc > out_end - out_ptr)
1384                         goto out;
1385                 out_ptr += rc;
1386         }
1387 out:
1388         *out_ptr = 0;
1389         return ispipe;
1390 }
1391
1392 static void zap_process(struct task_struct *start)
1393 {
1394         struct task_struct *t;
1395
1396         start->signal->flags = SIGNAL_GROUP_EXIT;
1397         start->signal->group_stop_count = 0;
1398
1399         t = start;
1400         do {
1401                 if (t != current && t->mm) {
1402                         t->mm->core_waiters++;
1403                         sigaddset(&t->pending.signal, SIGKILL);
1404                         signal_wake_up(t, 1);
1405                 }
1406         } while ((t = next_thread(t)) != start);
1407 }
1408
1409 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1410                                 int exit_code)
1411 {
1412         struct task_struct *g, *p;
1413         unsigned long flags;
1414         int err = -EAGAIN;
1415
1416         spin_lock_irq(&tsk->sighand->siglock);
1417         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1418                 tsk->signal->group_exit_code = exit_code;
1419                 zap_process(tsk);
1420                 err = 0;
1421         }
1422         spin_unlock_irq(&tsk->sighand->siglock);
1423         if (err)
1424                 return err;
1425
1426         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1427                 goto done;
1428
1429         rcu_read_lock();
1430         for_each_process(g) {
1431                 if (g == tsk->group_leader)
1432                         continue;
1433
1434                 p = g;
1435                 do {
1436                         if (p->mm) {
1437                                 if (p->mm == mm) {
1438                                         /*
1439                                          * p->sighand can't disappear, but
1440                                          * may be changed by de_thread()
1441                                          */
1442                                         lock_task_sighand(p, &flags);
1443                                         zap_process(p);
1444                                         unlock_task_sighand(p, &flags);
1445                                 }
1446                                 break;
1447                         }
1448                 } while ((p = next_thread(p)) != g);
1449         }
1450         rcu_read_unlock();
1451 done:
1452         return mm->core_waiters;
1453 }
1454
1455 static int coredump_wait(int exit_code)
1456 {
1457         struct task_struct *tsk = current;
1458         struct mm_struct *mm = tsk->mm;
1459         struct completion startup_done;
1460         struct completion *vfork_done;
1461         int core_waiters;
1462
1463         init_completion(&mm->core_done);
1464         init_completion(&startup_done);
1465         mm->core_startup_done = &startup_done;
1466
1467         core_waiters = zap_threads(tsk, mm, exit_code);
1468         up_write(&mm->mmap_sem);
1469
1470         if (unlikely(core_waiters < 0))
1471                 goto fail;
1472
1473         /*
1474          * Make sure nobody is waiting for us to release the VM,
1475          * otherwise we can deadlock when we wait on each other
1476          */
1477         vfork_done = tsk->vfork_done;
1478         if (vfork_done) {
1479                 tsk->vfork_done = NULL;
1480                 complete(vfork_done);
1481         }
1482
1483         if (core_waiters)
1484                 wait_for_completion(&startup_done);
1485 fail:
1486         BUG_ON(mm->core_waiters);
1487         return core_waiters;
1488 }
1489
1490 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1491 {
1492         char corename[CORENAME_MAX_SIZE + 1];
1493         struct mm_struct *mm = current->mm;
1494         struct linux_binfmt * binfmt;
1495         struct inode * inode;
1496         struct file * file;
1497         int retval = 0;
1498         int fsuid = current->fsuid;
1499         int flag = 0;
1500         int ispipe = 0;
1501
1502         audit_core_dumps(signr);
1503
1504         binfmt = current->binfmt;
1505         if (!binfmt || !binfmt->core_dump)
1506                 goto fail;
1507         down_write(&mm->mmap_sem);
1508         if (!mm->dumpable) {
1509                 up_write(&mm->mmap_sem);
1510                 goto fail;
1511         }
1512
1513         /*
1514          *      We cannot trust fsuid as being the "true" uid of the
1515          *      process nor do we know its entire history. We only know it
1516          *      was tainted so we dump it as root in mode 2.
1517          */
1518         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1519                 flag = O_EXCL;          /* Stop rewrite attacks */
1520                 current->fsuid = 0;     /* Dump root private */
1521         }
1522         mm->dumpable = 0;
1523
1524         retval = coredump_wait(exit_code);
1525         if (retval < 0)
1526                 goto fail;
1527
1528         /*
1529          * Clear any false indication of pending signals that might
1530          * be seen by the filesystem code called to write the core file.
1531          */
1532         clear_thread_flag(TIF_SIGPENDING);
1533
1534         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1535                 goto fail_unlock;
1536
1537         /*
1538          * lock_kernel() because format_corename() is controlled by sysctl, which
1539          * uses lock_kernel()
1540          */
1541         lock_kernel();
1542         ispipe = format_corename(corename, core_pattern, signr);
1543         unlock_kernel();
1544         if (ispipe) {
1545                 /* SIGPIPE can happen, but it's just never processed */
1546                 if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1547                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1548                                corename);
1549                         goto fail_unlock;
1550                 }
1551         } else
1552                 file = filp_open(corename,
1553                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1554                                  0600);
1555         if (IS_ERR(file))
1556                 goto fail_unlock;
1557         inode = file->f_path.dentry->d_inode;
1558         if (inode->i_nlink > 1)
1559                 goto close_fail;        /* multiple links - don't dump */
1560         if (!ispipe && d_unhashed(file->f_path.dentry))
1561                 goto close_fail;
1562
1563         /* AK: actually i see no reason to not allow this for named pipes etc.,
1564            but keep the previous behaviour for now. */
1565         if (!ispipe && !S_ISREG(inode->i_mode))
1566                 goto close_fail;
1567         if (!file->f_op)
1568                 goto close_fail;
1569         if (!file->f_op->write)
1570                 goto close_fail;
1571         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1572                 goto close_fail;
1573
1574         retval = binfmt->core_dump(signr, regs, file);
1575
1576         if (retval)
1577                 current->signal->group_exit_code |= 0x80;
1578 close_fail:
1579         filp_close(file, NULL);
1580 fail_unlock:
1581         current->fsuid = fsuid;
1582         complete_all(&mm->core_done);
1583 fail:
1584         return retval;
1585 }