[PATCH] add a vfs_permission helper
[linux-2.6.git] / fs / exec.c
1 /*
2  *  linux/fs/exec.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 /*
8  * #!-checking implemented by tytso.
9  */
10 /*
11  * Demand-loading implemented 01.12.91 - no need to read anything but
12  * the header into memory. The inode of the executable is put into
13  * "current->executable", and page faults do the actual loading. Clean.
14  *
15  * Once more I can proudly say that linux stood up to being changed: it
16  * was less than 2 hours work to get demand-loading completely implemented.
17  *
18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
19  * current->executable is only used by the procfs.  This allows a dispatch
20  * table to check for several different types  of binary formats.  We keep
21  * trying until we recognize the file or we run out of supported binary
22  * formats. 
23  */
24
25 #include <linux/config.h>
26 #include <linux/slab.h>
27 #include <linux/file.h>
28 #include <linux/mman.h>
29 #include <linux/a.out.h>
30 #include <linux/stat.h>
31 #include <linux/fcntl.h>
32 #include <linux/smp_lock.h>
33 #include <linux/init.h>
34 #include <linux/pagemap.h>
35 #include <linux/highmem.h>
36 #include <linux/spinlock.h>
37 #include <linux/key.h>
38 #include <linux/personality.h>
39 #include <linux/binfmts.h>
40 #include <linux/swap.h>
41 #include <linux/utsname.h>
42 #include <linux/module.h>
43 #include <linux/namei.h>
44 #include <linux/proc_fs.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/syscalls.h>
49 #include <linux/rmap.h>
50 #include <linux/acct.h>
51 #include <linux/cn_proc.h>
52
53 #include <asm/uaccess.h>
54 #include <asm/mmu_context.h>
55
56 #ifdef CONFIG_KMOD
57 #include <linux/kmod.h>
58 #endif
59
60 int core_uses_pid;
61 char core_pattern[65] = "core";
62 int suid_dumpable = 0;
63
64 EXPORT_SYMBOL(suid_dumpable);
65 /* The maximal length of core_pattern is also specified in sysctl.c */
66
67 static struct linux_binfmt *formats;
68 static DEFINE_RWLOCK(binfmt_lock);
69
70 int register_binfmt(struct linux_binfmt * fmt)
71 {
72         struct linux_binfmt ** tmp = &formats;
73
74         if (!fmt)
75                 return -EINVAL;
76         if (fmt->next)
77                 return -EBUSY;
78         write_lock(&binfmt_lock);
79         while (*tmp) {
80                 if (fmt == *tmp) {
81                         write_unlock(&binfmt_lock);
82                         return -EBUSY;
83                 }
84                 tmp = &(*tmp)->next;
85         }
86         fmt->next = formats;
87         formats = fmt;
88         write_unlock(&binfmt_lock);
89         return 0;       
90 }
91
92 EXPORT_SYMBOL(register_binfmt);
93
94 int unregister_binfmt(struct linux_binfmt * fmt)
95 {
96         struct linux_binfmt ** tmp = &formats;
97
98         write_lock(&binfmt_lock);
99         while (*tmp) {
100                 if (fmt == *tmp) {
101                         *tmp = fmt->next;
102                         write_unlock(&binfmt_lock);
103                         return 0;
104                 }
105                 tmp = &(*tmp)->next;
106         }
107         write_unlock(&binfmt_lock);
108         return -EINVAL;
109 }
110
111 EXPORT_SYMBOL(unregister_binfmt);
112
113 static inline void put_binfmt(struct linux_binfmt * fmt)
114 {
115         module_put(fmt->module);
116 }
117
118 /*
119  * Note that a shared library must be both readable and executable due to
120  * security reasons.
121  *
122  * Also note that we take the address to load from from the file itself.
123  */
124 asmlinkage long sys_uselib(const char __user * library)
125 {
126         struct file * file;
127         struct nameidata nd;
128         int error;
129
130         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ);
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         pgd_t * pgd;
310         pud_t * pud;
311         pmd_t * pmd;
312         pte_t * pte;
313         spinlock_t *ptl;
314
315         if (unlikely(anon_vma_prepare(vma)))
316                 goto out;
317
318         flush_dcache_page(page);
319         pgd = pgd_offset(mm, address);
320         pud = pud_alloc(mm, pgd, address);
321         if (!pud)
322                 goto out;
323         pmd = pmd_alloc(mm, pud, address);
324         if (!pmd)
325                 goto out;
326         pte = pte_alloc_map_lock(mm, pmd, address, &ptl);
327         if (!pte)
328                 goto out;
329         if (!pte_none(*pte)) {
330                 pte_unmap_unlock(pte, ptl);
331                 goto out;
332         }
333         inc_mm_counter(mm, anon_rss);
334         lru_cache_add_active(page);
335         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
336                                         page, vma->vm_page_prot))));
337         page_add_anon_rmap(page, vma, address);
338         pte_unmap_unlock(pte, ptl);
339
340         /* no need for flush_tlb */
341         return;
342 out:
343         __free_page(page);
344         force_sig(SIGKILL, current);
345 }
346
347 #define EXTRA_STACK_VM_PAGES    20      /* random */
348
349 int setup_arg_pages(struct linux_binprm *bprm,
350                     unsigned long stack_top,
351                     int executable_stack)
352 {
353         unsigned long stack_base;
354         struct vm_area_struct *mpnt;
355         struct mm_struct *mm = current->mm;
356         int i, ret;
357         long arg_size;
358
359 #ifdef CONFIG_STACK_GROWSUP
360         /* Move the argument and environment strings to the bottom of the
361          * stack space.
362          */
363         int offset, j;
364         char *to, *from;
365
366         /* Start by shifting all the pages down */
367         i = 0;
368         for (j = 0; j < MAX_ARG_PAGES; j++) {
369                 struct page *page = bprm->page[j];
370                 if (!page)
371                         continue;
372                 bprm->page[i++] = page;
373         }
374
375         /* Now move them within their pages */
376         offset = bprm->p % PAGE_SIZE;
377         to = kmap(bprm->page[0]);
378         for (j = 1; j < i; j++) {
379                 memmove(to, to + offset, PAGE_SIZE - offset);
380                 from = kmap(bprm->page[j]);
381                 memcpy(to + PAGE_SIZE - offset, from, offset);
382                 kunmap(bprm->page[j - 1]);
383                 to = from;
384         }
385         memmove(to, to + offset, PAGE_SIZE - offset);
386         kunmap(bprm->page[j - 1]);
387
388         /* Limit stack size to 1GB */
389         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
390         if (stack_base > (1 << 30))
391                 stack_base = 1 << 30;
392         stack_base = PAGE_ALIGN(stack_top - stack_base);
393
394         /* Adjust bprm->p to point to the end of the strings. */
395         bprm->p = stack_base + PAGE_SIZE * i - offset;
396
397         mm->arg_start = stack_base;
398         arg_size = i << PAGE_SHIFT;
399
400         /* zero pages that were copied above */
401         while (i < MAX_ARG_PAGES)
402                 bprm->page[i++] = NULL;
403 #else
404         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
405         stack_base = PAGE_ALIGN(stack_base);
406         bprm->p += stack_base;
407         mm->arg_start = bprm->p;
408         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
409 #endif
410
411         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
412
413         if (bprm->loader)
414                 bprm->loader += stack_base;
415         bprm->exec += stack_base;
416
417         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
418         if (!mpnt)
419                 return -ENOMEM;
420
421         memset(mpnt, 0, sizeof(*mpnt));
422
423         down_write(&mm->mmap_sem);
424         {
425                 mpnt->vm_mm = mm;
426 #ifdef CONFIG_STACK_GROWSUP
427                 mpnt->vm_start = stack_base;
428                 mpnt->vm_end = stack_base + arg_size;
429 #else
430                 mpnt->vm_end = stack_top;
431                 mpnt->vm_start = mpnt->vm_end - arg_size;
432 #endif
433                 /* Adjust stack execute permissions; explicitly enable
434                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
435                  * and leave alone (arch default) otherwise. */
436                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
437                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
438                 else if (executable_stack == EXSTACK_DISABLE_X)
439                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
440                 else
441                         mpnt->vm_flags = VM_STACK_FLAGS;
442                 mpnt->vm_flags |= mm->def_flags;
443                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
444                 if ((ret = insert_vm_struct(mm, mpnt))) {
445                         up_write(&mm->mmap_sem);
446                         kmem_cache_free(vm_area_cachep, mpnt);
447                         return ret;
448                 }
449                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
450         }
451
452         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
453                 struct page *page = bprm->page[i];
454                 if (page) {
455                         bprm->page[i] = NULL;
456                         install_arg_page(mpnt, page, stack_base);
457                 }
458                 stack_base += PAGE_SIZE;
459         }
460         up_write(&mm->mmap_sem);
461         
462         return 0;
463 }
464
465 EXPORT_SYMBOL(setup_arg_pages);
466
467 #define free_arg_pages(bprm) do { } while (0)
468
469 #else
470
471 static inline void free_arg_pages(struct linux_binprm *bprm)
472 {
473         int i;
474
475         for (i = 0; i < MAX_ARG_PAGES; i++) {
476                 if (bprm->page[i])
477                         __free_page(bprm->page[i]);
478                 bprm->page[i] = NULL;
479         }
480 }
481
482 #endif /* CONFIG_MMU */
483
484 struct file *open_exec(const char *name)
485 {
486         struct nameidata nd;
487         int err;
488         struct file *file;
489
490         err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ);
491         file = ERR_PTR(err);
492
493         if (!err) {
494                 struct inode *inode = nd.dentry->d_inode;
495                 file = ERR_PTR(-EACCES);
496                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
497                     S_ISREG(inode->i_mode)) {
498                         int err = vfs_permission(&nd, MAY_EXEC);
499                         if (!err && !(inode->i_mode & 0111))
500                                 err = -EACCES;
501                         file = ERR_PTR(err);
502                         if (!err) {
503                                 file = nameidata_to_filp(&nd, O_RDONLY);
504                                 if (!IS_ERR(file)) {
505                                         err = deny_write_access(file);
506                                         if (err) {
507                                                 fput(file);
508                                                 file = ERR_PTR(err);
509                                         }
510                                 }
511 out:
512                                 return file;
513                         }
514                 }
515                 release_open_intent(&nd);
516                 path_release(&nd);
517         }
518         goto out;
519 }
520
521 EXPORT_SYMBOL(open_exec);
522
523 int kernel_read(struct file *file, unsigned long offset,
524         char *addr, unsigned long count)
525 {
526         mm_segment_t old_fs;
527         loff_t pos = offset;
528         int result;
529
530         old_fs = get_fs();
531         set_fs(get_ds());
532         /* The cast to a user pointer is valid due to the set_fs() */
533         result = vfs_read(file, (void __user *)addr, count, &pos);
534         set_fs(old_fs);
535         return result;
536 }
537
538 EXPORT_SYMBOL(kernel_read);
539
540 static int exec_mmap(struct mm_struct *mm)
541 {
542         struct task_struct *tsk;
543         struct mm_struct * old_mm, *active_mm;
544
545         /* Notify parent that we're no longer interested in the old VM */
546         tsk = current;
547         old_mm = current->mm;
548         mm_release(tsk, old_mm);
549
550         if (old_mm) {
551                 /*
552                  * Make sure that if there is a core dump in progress
553                  * for the old mm, we get out and die instead of going
554                  * through with the exec.  We must hold mmap_sem around
555                  * checking core_waiters and changing tsk->mm.  The
556                  * core-inducing thread will increment core_waiters for
557                  * each thread whose ->mm == old_mm.
558                  */
559                 down_read(&old_mm->mmap_sem);
560                 if (unlikely(old_mm->core_waiters)) {
561                         up_read(&old_mm->mmap_sem);
562                         return -EINTR;
563                 }
564         }
565         task_lock(tsk);
566         active_mm = tsk->active_mm;
567         tsk->mm = mm;
568         tsk->active_mm = mm;
569         activate_mm(active_mm, mm);
570         task_unlock(tsk);
571         arch_pick_mmap_layout(mm);
572         if (old_mm) {
573                 up_read(&old_mm->mmap_sem);
574                 if (active_mm != old_mm) BUG();
575                 mmput(old_mm);
576                 return 0;
577         }
578         mmdrop(active_mm);
579         return 0;
580 }
581
582 /*
583  * This function makes sure the current process has its own signal table,
584  * so that flush_signal_handlers can later reset the handlers without
585  * disturbing other processes.  (Other processes might share the signal
586  * table via the CLONE_SIGHAND option to clone().)
587  */
588 static inline int de_thread(struct task_struct *tsk)
589 {
590         struct signal_struct *sig = tsk->signal;
591         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
592         spinlock_t *lock = &oldsighand->siglock;
593         struct task_struct *leader = NULL;
594         int count;
595
596         /*
597          * If we don't share sighandlers, then we aren't sharing anything
598          * and we can just re-use it all.
599          */
600         if (atomic_read(&oldsighand->count) <= 1) {
601                 BUG_ON(atomic_read(&sig->count) != 1);
602                 exit_itimers(sig);
603                 return 0;
604         }
605
606         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
607         if (!newsighand)
608                 return -ENOMEM;
609
610         if (thread_group_empty(current))
611                 goto no_thread_group;
612
613         /*
614          * Kill all other threads in the thread group.
615          * We must hold tasklist_lock to call zap_other_threads.
616          */
617         read_lock(&tasklist_lock);
618         spin_lock_irq(lock);
619         if (sig->flags & SIGNAL_GROUP_EXIT) {
620                 /*
621                  * Another group action in progress, just
622                  * return so that the signal is processed.
623                  */
624                 spin_unlock_irq(lock);
625                 read_unlock(&tasklist_lock);
626                 kmem_cache_free(sighand_cachep, newsighand);
627                 return -EAGAIN;
628         }
629         zap_other_threads(current);
630         read_unlock(&tasklist_lock);
631
632         /*
633          * Account for the thread group leader hanging around:
634          */
635         count = 1;
636         if (!thread_group_leader(current)) {
637                 count = 2;
638                 /*
639                  * The SIGALRM timer survives the exec, but needs to point
640                  * at us as the new group leader now.  We have a race with
641                  * a timer firing now getting the old leader, so we need to
642                  * synchronize with any firing (by calling del_timer_sync)
643                  * before we can safely let the old group leader die.
644                  */
645                 sig->real_timer.data = (unsigned long)current;
646                 spin_unlock_irq(lock);
647                 if (del_timer_sync(&sig->real_timer))
648                         add_timer(&sig->real_timer);
649                 spin_lock_irq(lock);
650         }
651         while (atomic_read(&sig->count) > count) {
652                 sig->group_exit_task = current;
653                 sig->notify_count = count;
654                 __set_current_state(TASK_UNINTERRUPTIBLE);
655                 spin_unlock_irq(lock);
656                 schedule();
657                 spin_lock_irq(lock);
658         }
659         sig->group_exit_task = NULL;
660         sig->notify_count = 0;
661         spin_unlock_irq(lock);
662
663         /*
664          * At this point all other threads have exited, all we have to
665          * do is to wait for the thread group leader to become inactive,
666          * and to assume its PID:
667          */
668         if (!thread_group_leader(current)) {
669                 struct task_struct *parent;
670                 struct dentry *proc_dentry1, *proc_dentry2;
671                 unsigned long exit_state, ptrace;
672
673                 /*
674                  * Wait for the thread group leader to be a zombie.
675                  * It should already be zombie at this point, most
676                  * of the time.
677                  */
678                 leader = current->group_leader;
679                 while (leader->exit_state != EXIT_ZOMBIE)
680                         yield();
681
682                 spin_lock(&leader->proc_lock);
683                 spin_lock(&current->proc_lock);
684                 proc_dentry1 = proc_pid_unhash(current);
685                 proc_dentry2 = proc_pid_unhash(leader);
686                 write_lock_irq(&tasklist_lock);
687
688                 BUG_ON(leader->tgid != current->tgid);
689                 BUG_ON(current->pid == current->tgid);
690                 /*
691                  * An exec() starts a new thread group with the
692                  * TGID of the previous thread group. Rehash the
693                  * two threads with a switched PID, and release
694                  * the former thread group leader:
695                  */
696                 ptrace = leader->ptrace;
697                 parent = leader->parent;
698                 if (unlikely(ptrace) && unlikely(parent == current)) {
699                         /*
700                          * Joker was ptracing his own group leader,
701                          * and now he wants to be his own parent!
702                          * We can't have that.
703                          */
704                         ptrace = 0;
705                 }
706
707                 ptrace_unlink(current);
708                 ptrace_unlink(leader);
709                 remove_parent(current);
710                 remove_parent(leader);
711
712                 switch_exec_pids(leader, current);
713
714                 current->parent = current->real_parent = leader->real_parent;
715                 leader->parent = leader->real_parent = child_reaper;
716                 current->group_leader = current;
717                 leader->group_leader = leader;
718
719                 add_parent(current, current->parent);
720                 add_parent(leader, leader->parent);
721                 if (ptrace) {
722                         current->ptrace = ptrace;
723                         __ptrace_link(current, parent);
724                 }
725
726                 list_del(&current->tasks);
727                 list_add_tail(&current->tasks, &init_task.tasks);
728                 current->exit_signal = SIGCHLD;
729                 exit_state = leader->exit_state;
730
731                 write_unlock_irq(&tasklist_lock);
732                 spin_unlock(&leader->proc_lock);
733                 spin_unlock(&current->proc_lock);
734                 proc_pid_flush(proc_dentry1);
735                 proc_pid_flush(proc_dentry2);
736
737                 BUG_ON(exit_state != EXIT_ZOMBIE);
738         }
739
740         /*
741          * There may be one thread left which is just exiting,
742          * but it's safe to stop telling the group to kill themselves.
743          */
744         sig->flags = 0;
745
746 no_thread_group:
747         exit_itimers(sig);
748         if (leader)
749                 release_task(leader);
750
751         BUG_ON(atomic_read(&sig->count) != 1);
752
753         if (atomic_read(&oldsighand->count) == 1) {
754                 /*
755                  * Now that we nuked the rest of the thread group,
756                  * it turns out we are not sharing sighand any more either.
757                  * So we can just keep it.
758                  */
759                 kmem_cache_free(sighand_cachep, newsighand);
760         } else {
761                 /*
762                  * Move our state over to newsighand and switch it in.
763                  */
764                 spin_lock_init(&newsighand->siglock);
765                 atomic_set(&newsighand->count, 1);
766                 memcpy(newsighand->action, oldsighand->action,
767                        sizeof(newsighand->action));
768
769                 write_lock_irq(&tasklist_lock);
770                 spin_lock(&oldsighand->siglock);
771                 spin_lock(&newsighand->siglock);
772
773                 current->sighand = newsighand;
774                 recalc_sigpending();
775
776                 spin_unlock(&newsighand->siglock);
777                 spin_unlock(&oldsighand->siglock);
778                 write_unlock_irq(&tasklist_lock);
779
780                 if (atomic_dec_and_test(&oldsighand->count))
781                         kmem_cache_free(sighand_cachep, oldsighand);
782         }
783
784         BUG_ON(!thread_group_leader(current));
785         return 0;
786 }
787         
788 /*
789  * These functions flushes out all traces of the currently running executable
790  * so that a new one can be started
791  */
792
793 static inline void flush_old_files(struct files_struct * files)
794 {
795         long j = -1;
796         struct fdtable *fdt;
797
798         spin_lock(&files->file_lock);
799         for (;;) {
800                 unsigned long set, i;
801
802                 j++;
803                 i = j * __NFDBITS;
804                 fdt = files_fdtable(files);
805                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
806                         break;
807                 set = fdt->close_on_exec->fds_bits[j];
808                 if (!set)
809                         continue;
810                 fdt->close_on_exec->fds_bits[j] = 0;
811                 spin_unlock(&files->file_lock);
812                 for ( ; set ; i++,set >>= 1) {
813                         if (set & 1) {
814                                 sys_close(i);
815                         }
816                 }
817                 spin_lock(&files->file_lock);
818
819         }
820         spin_unlock(&files->file_lock);
821 }
822
823 void get_task_comm(char *buf, struct task_struct *tsk)
824 {
825         /* buf must be at least sizeof(tsk->comm) in size */
826         task_lock(tsk);
827         strncpy(buf, tsk->comm, sizeof(tsk->comm));
828         task_unlock(tsk);
829 }
830
831 void set_task_comm(struct task_struct *tsk, char *buf)
832 {
833         task_lock(tsk);
834         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
835         task_unlock(tsk);
836 }
837
838 int flush_old_exec(struct linux_binprm * bprm)
839 {
840         char * name;
841         int i, ch, retval;
842         struct files_struct *files;
843         char tcomm[sizeof(current->comm)];
844
845         /*
846          * Make sure we have a private signal table and that
847          * we are unassociated from the previous thread group.
848          */
849         retval = de_thread(current);
850         if (retval)
851                 goto out;
852
853         /*
854          * Make sure we have private file handles. Ask the
855          * fork helper to do the work for us and the exit
856          * helper to do the cleanup of the old one.
857          */
858         files = current->files;         /* refcounted so safe to hold */
859         retval = unshare_files();
860         if (retval)
861                 goto out;
862         /*
863          * Release all of the old mmap stuff
864          */
865         retval = exec_mmap(bprm->mm);
866         if (retval)
867                 goto mmap_failed;
868
869         bprm->mm = NULL;                /* We're using it now */
870
871         /* This is the point of no return */
872         steal_locks(files);
873         put_files_struct(files);
874
875         current->sas_ss_sp = current->sas_ss_size = 0;
876
877         if (current->euid == current->uid && current->egid == current->gid)
878                 current->mm->dumpable = 1;
879         else
880                 current->mm->dumpable = suid_dumpable;
881
882         name = bprm->filename;
883
884         /* Copies the binary name from after last slash */
885         for (i=0; (ch = *(name++)) != '\0';) {
886                 if (ch == '/')
887                         i = 0; /* overwrite what we wrote */
888                 else
889                         if (i < (sizeof(tcomm) - 1))
890                                 tcomm[i++] = ch;
891         }
892         tcomm[i] = '\0';
893         set_task_comm(current, tcomm);
894
895         current->flags &= ~PF_RANDOMIZE;
896         flush_thread();
897
898         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
899             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
900             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
901                 suid_keys(current);
902                 current->mm->dumpable = suid_dumpable;
903         }
904
905         /* An exec changes our domain. We are no longer part of the thread
906            group */
907
908         current->self_exec_id++;
909                         
910         flush_signal_handlers(current, 0);
911         flush_old_files(current->files);
912
913         return 0;
914
915 mmap_failed:
916         put_files_struct(current->files);
917         current->files = files;
918 out:
919         return retval;
920 }
921
922 EXPORT_SYMBOL(flush_old_exec);
923
924 /* 
925  * Fill the binprm structure from the inode. 
926  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
927  */
928 int prepare_binprm(struct linux_binprm *bprm)
929 {
930         int mode;
931         struct inode * inode = bprm->file->f_dentry->d_inode;
932         int retval;
933
934         mode = inode->i_mode;
935         /*
936          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
937          * generic_permission lets a non-executable through
938          */
939         if (!(mode & 0111))     /* with at least _one_ execute bit set */
940                 return -EACCES;
941         if (bprm->file->f_op == NULL)
942                 return -EACCES;
943
944         bprm->e_uid = current->euid;
945         bprm->e_gid = current->egid;
946
947         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
948                 /* Set-uid? */
949                 if (mode & S_ISUID) {
950                         current->personality &= ~PER_CLEAR_ON_SETID;
951                         bprm->e_uid = inode->i_uid;
952                 }
953
954                 /* Set-gid? */
955                 /*
956                  * If setgid is set but no group execute bit then this
957                  * is a candidate for mandatory locking, not a setgid
958                  * executable.
959                  */
960                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
961                         current->personality &= ~PER_CLEAR_ON_SETID;
962                         bprm->e_gid = inode->i_gid;
963                 }
964         }
965
966         /* fill in binprm security blob */
967         retval = security_bprm_set(bprm);
968         if (retval)
969                 return retval;
970
971         memset(bprm->buf,0,BINPRM_BUF_SIZE);
972         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
973 }
974
975 EXPORT_SYMBOL(prepare_binprm);
976
977 static inline int unsafe_exec(struct task_struct *p)
978 {
979         int unsafe = 0;
980         if (p->ptrace & PT_PTRACED) {
981                 if (p->ptrace & PT_PTRACE_CAP)
982                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
983                 else
984                         unsafe |= LSM_UNSAFE_PTRACE;
985         }
986         if (atomic_read(&p->fs->count) > 1 ||
987             atomic_read(&p->files->count) > 1 ||
988             atomic_read(&p->sighand->count) > 1)
989                 unsafe |= LSM_UNSAFE_SHARE;
990
991         return unsafe;
992 }
993
994 void compute_creds(struct linux_binprm *bprm)
995 {
996         int unsafe;
997
998         if (bprm->e_uid != current->uid)
999                 suid_keys(current);
1000         exec_keys(current);
1001
1002         task_lock(current);
1003         unsafe = unsafe_exec(current);
1004         security_bprm_apply_creds(bprm, unsafe);
1005         task_unlock(current);
1006         security_bprm_post_apply_creds(bprm);
1007 }
1008
1009 EXPORT_SYMBOL(compute_creds);
1010
1011 void remove_arg_zero(struct linux_binprm *bprm)
1012 {
1013         if (bprm->argc) {
1014                 unsigned long offset;
1015                 char * kaddr;
1016                 struct page *page;
1017
1018                 offset = bprm->p % PAGE_SIZE;
1019                 goto inside;
1020
1021                 while (bprm->p++, *(kaddr+offset++)) {
1022                         if (offset != PAGE_SIZE)
1023                                 continue;
1024                         offset = 0;
1025                         kunmap_atomic(kaddr, KM_USER0);
1026 inside:
1027                         page = bprm->page[bprm->p/PAGE_SIZE];
1028                         kaddr = kmap_atomic(page, KM_USER0);
1029                 }
1030                 kunmap_atomic(kaddr, KM_USER0);
1031                 bprm->argc--;
1032         }
1033 }
1034
1035 EXPORT_SYMBOL(remove_arg_zero);
1036
1037 /*
1038  * cycle the list of binary formats handler, until one recognizes the image
1039  */
1040 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1041 {
1042         int try,retval;
1043         struct linux_binfmt *fmt;
1044 #ifdef __alpha__
1045         /* handle /sbin/loader.. */
1046         {
1047             struct exec * eh = (struct exec *) bprm->buf;
1048
1049             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1050                 (eh->fh.f_flags & 0x3000) == 0x3000)
1051             {
1052                 struct file * file;
1053                 unsigned long loader;
1054
1055                 allow_write_access(bprm->file);
1056                 fput(bprm->file);
1057                 bprm->file = NULL;
1058
1059                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1060
1061                 file = open_exec("/sbin/loader");
1062                 retval = PTR_ERR(file);
1063                 if (IS_ERR(file))
1064                         return retval;
1065
1066                 /* Remember if the application is TASO.  */
1067                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1068
1069                 bprm->file = file;
1070                 bprm->loader = loader;
1071                 retval = prepare_binprm(bprm);
1072                 if (retval<0)
1073                         return retval;
1074                 /* should call search_binary_handler recursively here,
1075                    but it does not matter */
1076             }
1077         }
1078 #endif
1079         retval = security_bprm_check(bprm);
1080         if (retval)
1081                 return retval;
1082
1083         /* kernel module loader fixup */
1084         /* so we don't try to load run modprobe in kernel space. */
1085         set_fs(USER_DS);
1086         retval = -ENOENT;
1087         for (try=0; try<2; try++) {
1088                 read_lock(&binfmt_lock);
1089                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1090                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1091                         if (!fn)
1092                                 continue;
1093                         if (!try_module_get(fmt->module))
1094                                 continue;
1095                         read_unlock(&binfmt_lock);
1096                         retval = fn(bprm, regs);
1097                         if (retval >= 0) {
1098                                 put_binfmt(fmt);
1099                                 allow_write_access(bprm->file);
1100                                 if (bprm->file)
1101                                         fput(bprm->file);
1102                                 bprm->file = NULL;
1103                                 current->did_exec = 1;
1104                                 proc_exec_connector(current);
1105                                 return retval;
1106                         }
1107                         read_lock(&binfmt_lock);
1108                         put_binfmt(fmt);
1109                         if (retval != -ENOEXEC || bprm->mm == NULL)
1110                                 break;
1111                         if (!bprm->file) {
1112                                 read_unlock(&binfmt_lock);
1113                                 return retval;
1114                         }
1115                 }
1116                 read_unlock(&binfmt_lock);
1117                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1118                         break;
1119 #ifdef CONFIG_KMOD
1120                 }else{
1121 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1122                         if (printable(bprm->buf[0]) &&
1123                             printable(bprm->buf[1]) &&
1124                             printable(bprm->buf[2]) &&
1125                             printable(bprm->buf[3]))
1126                                 break; /* -ENOEXEC */
1127                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1128 #endif
1129                 }
1130         }
1131         return retval;
1132 }
1133
1134 EXPORT_SYMBOL(search_binary_handler);
1135
1136 /*
1137  * sys_execve() executes a new program.
1138  */
1139 int do_execve(char * filename,
1140         char __user *__user *argv,
1141         char __user *__user *envp,
1142         struct pt_regs * regs)
1143 {
1144         struct linux_binprm *bprm;
1145         struct file *file;
1146         int retval;
1147         int i;
1148
1149         retval = -ENOMEM;
1150         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1151         if (!bprm)
1152                 goto out_ret;
1153         memset(bprm, 0, sizeof(*bprm));
1154
1155         file = open_exec(filename);
1156         retval = PTR_ERR(file);
1157         if (IS_ERR(file))
1158                 goto out_kfree;
1159
1160         sched_exec();
1161
1162         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1163
1164         bprm->file = file;
1165         bprm->filename = filename;
1166         bprm->interp = filename;
1167         bprm->mm = mm_alloc();
1168         retval = -ENOMEM;
1169         if (!bprm->mm)
1170                 goto out_file;
1171
1172         retval = init_new_context(current, bprm->mm);
1173         if (retval < 0)
1174                 goto out_mm;
1175
1176         bprm->argc = count(argv, bprm->p / sizeof(void *));
1177         if ((retval = bprm->argc) < 0)
1178                 goto out_mm;
1179
1180         bprm->envc = count(envp, bprm->p / sizeof(void *));
1181         if ((retval = bprm->envc) < 0)
1182                 goto out_mm;
1183
1184         retval = security_bprm_alloc(bprm);
1185         if (retval)
1186                 goto out;
1187
1188         retval = prepare_binprm(bprm);
1189         if (retval < 0)
1190                 goto out;
1191
1192         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1193         if (retval < 0)
1194                 goto out;
1195
1196         bprm->exec = bprm->p;
1197         retval = copy_strings(bprm->envc, envp, bprm);
1198         if (retval < 0)
1199                 goto out;
1200
1201         retval = copy_strings(bprm->argc, argv, bprm);
1202         if (retval < 0)
1203                 goto out;
1204
1205         retval = search_binary_handler(bprm,regs);
1206         if (retval >= 0) {
1207                 free_arg_pages(bprm);
1208
1209                 /* execve success */
1210                 security_bprm_free(bprm);
1211                 acct_update_integrals(current);
1212                 kfree(bprm);
1213                 return retval;
1214         }
1215
1216 out:
1217         /* Something went wrong, return the inode and free the argument pages*/
1218         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1219                 struct page * page = bprm->page[i];
1220                 if (page)
1221                         __free_page(page);
1222         }
1223
1224         if (bprm->security)
1225                 security_bprm_free(bprm);
1226
1227 out_mm:
1228         if (bprm->mm)
1229                 mmdrop(bprm->mm);
1230
1231 out_file:
1232         if (bprm->file) {
1233                 allow_write_access(bprm->file);
1234                 fput(bprm->file);
1235         }
1236
1237 out_kfree:
1238         kfree(bprm);
1239
1240 out_ret:
1241         return retval;
1242 }
1243
1244 int set_binfmt(struct linux_binfmt *new)
1245 {
1246         struct linux_binfmt *old = current->binfmt;
1247
1248         if (new) {
1249                 if (!try_module_get(new->module))
1250                         return -1;
1251         }
1252         current->binfmt = new;
1253         if (old)
1254                 module_put(old->module);
1255         return 0;
1256 }
1257
1258 EXPORT_SYMBOL(set_binfmt);
1259
1260 #define CORENAME_MAX_SIZE 64
1261
1262 /* format_corename will inspect the pattern parameter, and output a
1263  * name into corename, which must have space for at least
1264  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1265  */
1266 static void format_corename(char *corename, const char *pattern, long signr)
1267 {
1268         const char *pat_ptr = pattern;
1269         char *out_ptr = corename;
1270         char *const out_end = corename + CORENAME_MAX_SIZE;
1271         int rc;
1272         int pid_in_pattern = 0;
1273
1274         /* Repeat as long as we have more pattern to process and more output
1275            space */
1276         while (*pat_ptr) {
1277                 if (*pat_ptr != '%') {
1278                         if (out_ptr == out_end)
1279                                 goto out;
1280                         *out_ptr++ = *pat_ptr++;
1281                 } else {
1282                         switch (*++pat_ptr) {
1283                         case 0:
1284                                 goto out;
1285                         /* Double percent, output one percent */
1286                         case '%':
1287                                 if (out_ptr == out_end)
1288                                         goto out;
1289                                 *out_ptr++ = '%';
1290                                 break;
1291                         /* pid */
1292                         case 'p':
1293                                 pid_in_pattern = 1;
1294                                 rc = snprintf(out_ptr, out_end - out_ptr,
1295                                               "%d", current->tgid);
1296                                 if (rc > out_end - out_ptr)
1297                                         goto out;
1298                                 out_ptr += rc;
1299                                 break;
1300                         /* uid */
1301                         case 'u':
1302                                 rc = snprintf(out_ptr, out_end - out_ptr,
1303                                               "%d", current->uid);
1304                                 if (rc > out_end - out_ptr)
1305                                         goto out;
1306                                 out_ptr += rc;
1307                                 break;
1308                         /* gid */
1309                         case 'g':
1310                                 rc = snprintf(out_ptr, out_end - out_ptr,
1311                                               "%d", current->gid);
1312                                 if (rc > out_end - out_ptr)
1313                                         goto out;
1314                                 out_ptr += rc;
1315                                 break;
1316                         /* signal that caused the coredump */
1317                         case 's':
1318                                 rc = snprintf(out_ptr, out_end - out_ptr,
1319                                               "%ld", signr);
1320                                 if (rc > out_end - out_ptr)
1321                                         goto out;
1322                                 out_ptr += rc;
1323                                 break;
1324                         /* UNIX time of coredump */
1325                         case 't': {
1326                                 struct timeval tv;
1327                                 do_gettimeofday(&tv);
1328                                 rc = snprintf(out_ptr, out_end - out_ptr,
1329                                               "%lu", tv.tv_sec);
1330                                 if (rc > out_end - out_ptr)
1331                                         goto out;
1332                                 out_ptr += rc;
1333                                 break;
1334                         }
1335                         /* hostname */
1336                         case 'h':
1337                                 down_read(&uts_sem);
1338                                 rc = snprintf(out_ptr, out_end - out_ptr,
1339                                               "%s", system_utsname.nodename);
1340                                 up_read(&uts_sem);
1341                                 if (rc > out_end - out_ptr)
1342                                         goto out;
1343                                 out_ptr += rc;
1344                                 break;
1345                         /* executable */
1346                         case 'e':
1347                                 rc = snprintf(out_ptr, out_end - out_ptr,
1348                                               "%s", current->comm);
1349                                 if (rc > out_end - out_ptr)
1350                                         goto out;
1351                                 out_ptr += rc;
1352                                 break;
1353                         default:
1354                                 break;
1355                         }
1356                         ++pat_ptr;
1357                 }
1358         }
1359         /* Backward compatibility with core_uses_pid:
1360          *
1361          * If core_pattern does not include a %p (as is the default)
1362          * and core_uses_pid is set, then .%pid will be appended to
1363          * the filename */
1364         if (!pid_in_pattern
1365             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1366                 rc = snprintf(out_ptr, out_end - out_ptr,
1367                               ".%d", current->tgid);
1368                 if (rc > out_end - out_ptr)
1369                         goto out;
1370                 out_ptr += rc;
1371         }
1372       out:
1373         *out_ptr = 0;
1374 }
1375
1376 static void zap_threads (struct mm_struct *mm)
1377 {
1378         struct task_struct *g, *p;
1379         struct task_struct *tsk = current;
1380         struct completion *vfork_done = tsk->vfork_done;
1381         int traced = 0;
1382
1383         /*
1384          * Make sure nobody is waiting for us to release the VM,
1385          * otherwise we can deadlock when we wait on each other
1386          */
1387         if (vfork_done) {
1388                 tsk->vfork_done = NULL;
1389                 complete(vfork_done);
1390         }
1391
1392         read_lock(&tasklist_lock);
1393         do_each_thread(g,p)
1394                 if (mm == p->mm && p != tsk) {
1395                         force_sig_specific(SIGKILL, p);
1396                         mm->core_waiters++;
1397                         if (unlikely(p->ptrace) &&
1398                             unlikely(p->parent->mm == mm))
1399                                 traced = 1;
1400                 }
1401         while_each_thread(g,p);
1402
1403         read_unlock(&tasklist_lock);
1404
1405         if (unlikely(traced)) {
1406                 /*
1407                  * We are zapping a thread and the thread it ptraces.
1408                  * If the tracee went into a ptrace stop for exit tracing,
1409                  * we could deadlock since the tracer is waiting for this
1410                  * coredump to finish.  Detach them so they can both die.
1411                  */
1412                 write_lock_irq(&tasklist_lock);
1413                 do_each_thread(g,p) {
1414                         if (mm == p->mm && p != tsk &&
1415                             p->ptrace && p->parent->mm == mm) {
1416                                 __ptrace_unlink(p);
1417                         }
1418                 } while_each_thread(g,p);
1419                 write_unlock_irq(&tasklist_lock);
1420         }
1421 }
1422
1423 static void coredump_wait(struct mm_struct *mm)
1424 {
1425         DECLARE_COMPLETION(startup_done);
1426         int core_waiters;
1427
1428         mm->core_startup_done = &startup_done;
1429
1430         zap_threads(mm);
1431         core_waiters = mm->core_waiters;
1432         up_write(&mm->mmap_sem);
1433
1434         if (core_waiters)
1435                 wait_for_completion(&startup_done);
1436         BUG_ON(mm->core_waiters);
1437 }
1438
1439 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1440 {
1441         char corename[CORENAME_MAX_SIZE + 1];
1442         struct mm_struct *mm = current->mm;
1443         struct linux_binfmt * binfmt;
1444         struct inode * inode;
1445         struct file * file;
1446         int retval = 0;
1447         int fsuid = current->fsuid;
1448         int flag = 0;
1449
1450         binfmt = current->binfmt;
1451         if (!binfmt || !binfmt->core_dump)
1452                 goto fail;
1453         down_write(&mm->mmap_sem);
1454         if (!mm->dumpable) {
1455                 up_write(&mm->mmap_sem);
1456                 goto fail;
1457         }
1458
1459         /*
1460          *      We cannot trust fsuid as being the "true" uid of the
1461          *      process nor do we know its entire history. We only know it
1462          *      was tainted so we dump it as root in mode 2.
1463          */
1464         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1465                 flag = O_EXCL;          /* Stop rewrite attacks */
1466                 current->fsuid = 0;     /* Dump root private */
1467         }
1468         mm->dumpable = 0;
1469
1470         retval = -EAGAIN;
1471         spin_lock_irq(&current->sighand->siglock);
1472         if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
1473                 current->signal->flags = SIGNAL_GROUP_EXIT;
1474                 current->signal->group_exit_code = exit_code;
1475                 retval = 0;
1476         }
1477         spin_unlock_irq(&current->sighand->siglock);
1478         if (retval) {
1479                 up_write(&mm->mmap_sem);
1480                 goto fail;
1481         }
1482
1483         init_completion(&mm->core_done);
1484         coredump_wait(mm);
1485
1486         /*
1487          * Clear any false indication of pending signals that might
1488          * be seen by the filesystem code called to write the core file.
1489          */
1490         current->signal->group_stop_count = 0;
1491         clear_thread_flag(TIF_SIGPENDING);
1492
1493         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1494                 goto fail_unlock;
1495
1496         /*
1497          * lock_kernel() because format_corename() is controlled by sysctl, which
1498          * uses lock_kernel()
1499          */
1500         lock_kernel();
1501         format_corename(corename, core_pattern, signr);
1502         unlock_kernel();
1503         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1504         if (IS_ERR(file))
1505                 goto fail_unlock;
1506         inode = file->f_dentry->d_inode;
1507         if (inode->i_nlink > 1)
1508                 goto close_fail;        /* multiple links - don't dump */
1509         if (d_unhashed(file->f_dentry))
1510                 goto close_fail;
1511
1512         if (!S_ISREG(inode->i_mode))
1513                 goto close_fail;
1514         if (!file->f_op)
1515                 goto close_fail;
1516         if (!file->f_op->write)
1517                 goto close_fail;
1518         if (do_truncate(file->f_dentry, 0, file) != 0)
1519                 goto close_fail;
1520
1521         retval = binfmt->core_dump(signr, regs, file);
1522
1523         if (retval)
1524                 current->signal->group_exit_code |= 0x80;
1525 close_fail:
1526         filp_close(file, NULL);
1527 fail_unlock:
1528         current->fsuid = fsuid;
1529         complete_all(&mm->core_done);
1530 fail:
1531         return retval;
1532 }