[PATCH] Fix fs/exec.c:788 (de_thread()) BUG_ON
[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
52 #include <asm/uaccess.h>
53 #include <asm/mmu_context.h>
54
55 #ifdef CONFIG_KMOD
56 #include <linux/kmod.h>
57 #endif
58
59 int core_uses_pid;
60 char core_pattern[65] = "core";
61 int suid_dumpable = 0;
62
63 EXPORT_SYMBOL(suid_dumpable);
64 /* The maximal length of core_pattern is also specified in sysctl.c */
65
66 static struct linux_binfmt *formats;
67 static DEFINE_RWLOCK(binfmt_lock);
68
69 int register_binfmt(struct linux_binfmt * fmt)
70 {
71         struct linux_binfmt ** tmp = &formats;
72
73         if (!fmt)
74                 return -EINVAL;
75         if (fmt->next)
76                 return -EBUSY;
77         write_lock(&binfmt_lock);
78         while (*tmp) {
79                 if (fmt == *tmp) {
80                         write_unlock(&binfmt_lock);
81                         return -EBUSY;
82                 }
83                 tmp = &(*tmp)->next;
84         }
85         fmt->next = formats;
86         formats = fmt;
87         write_unlock(&binfmt_lock);
88         return 0;       
89 }
90
91 EXPORT_SYMBOL(register_binfmt);
92
93 int unregister_binfmt(struct linux_binfmt * fmt)
94 {
95         struct linux_binfmt ** tmp = &formats;
96
97         write_lock(&binfmt_lock);
98         while (*tmp) {
99                 if (fmt == *tmp) {
100                         *tmp = fmt->next;
101                         write_unlock(&binfmt_lock);
102                         return 0;
103                 }
104                 tmp = &(*tmp)->next;
105         }
106         write_unlock(&binfmt_lock);
107         return -EINVAL;
108 }
109
110 EXPORT_SYMBOL(unregister_binfmt);
111
112 static inline void put_binfmt(struct linux_binfmt * fmt)
113 {
114         module_put(fmt->module);
115 }
116
117 /*
118  * Note that a shared library must be both readable and executable due to
119  * security reasons.
120  *
121  * Also note that we take the address to load from from the file itself.
122  */
123 asmlinkage long sys_uselib(const char __user * library)
124 {
125         struct file * file;
126         struct nameidata nd;
127         int error;
128
129         nd.intent.open.flags = FMODE_READ;
130         error = __user_walk(library, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
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 = permission(nd.dentry->d_inode, MAY_READ | MAY_EXEC, &nd);
139         if (error)
140                 goto exit;
141
142         file = dentry_open(nd.dentry, nd.mnt, 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         path_release(&nd);
171         goto out;
172 }
173
174 /*
175  * count() counts the number of strings in array ARGV.
176  */
177 static int count(char __user * __user * argv, int max)
178 {
179         int i = 0;
180
181         if (argv != NULL) {
182                 for (;;) {
183                         char __user * p;
184
185                         if (get_user(p, argv))
186                                 return -EFAULT;
187                         if (!p)
188                                 break;
189                         argv++;
190                         if(++i > max)
191                                 return -E2BIG;
192                         cond_resched();
193                 }
194         }
195         return i;
196 }
197
198 /*
199  * 'copy_strings()' copies argument/environment strings from user
200  * memory to free pages in kernel mem. These are in a format ready
201  * to be put directly into the top of new user memory.
202  */
203 static int copy_strings(int argc, char __user * __user * argv,
204                         struct linux_binprm *bprm)
205 {
206         struct page *kmapped_page = NULL;
207         char *kaddr = NULL;
208         int ret;
209
210         while (argc-- > 0) {
211                 char __user *str;
212                 int len;
213                 unsigned long pos;
214
215                 if (get_user(str, argv+argc) ||
216                                 !(len = strnlen_user(str, bprm->p))) {
217                         ret = -EFAULT;
218                         goto out;
219                 }
220
221                 if (bprm->p < len)  {
222                         ret = -E2BIG;
223                         goto out;
224                 }
225
226                 bprm->p -= len;
227                 /* XXX: add architecture specific overflow check here. */
228                 pos = bprm->p;
229
230                 while (len > 0) {
231                         int i, new, err;
232                         int offset, bytes_to_copy;
233                         struct page *page;
234
235                         offset = pos % PAGE_SIZE;
236                         i = pos/PAGE_SIZE;
237                         page = bprm->page[i];
238                         new = 0;
239                         if (!page) {
240                                 page = alloc_page(GFP_HIGHUSER);
241                                 bprm->page[i] = page;
242                                 if (!page) {
243                                         ret = -ENOMEM;
244                                         goto out;
245                                 }
246                                 new = 1;
247                         }
248
249                         if (page != kmapped_page) {
250                                 if (kmapped_page)
251                                         kunmap(kmapped_page);
252                                 kmapped_page = page;
253                                 kaddr = kmap(kmapped_page);
254                         }
255                         if (new && offset)
256                                 memset(kaddr, 0, offset);
257                         bytes_to_copy = PAGE_SIZE - offset;
258                         if (bytes_to_copy > len) {
259                                 bytes_to_copy = len;
260                                 if (new)
261                                         memset(kaddr+offset+len, 0,
262                                                 PAGE_SIZE-offset-len);
263                         }
264                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
265                         if (err) {
266                                 ret = -EFAULT;
267                                 goto out;
268                         }
269
270                         pos += bytes_to_copy;
271                         str += bytes_to_copy;
272                         len -= bytes_to_copy;
273                 }
274         }
275         ret = 0;
276 out:
277         if (kmapped_page)
278                 kunmap(kmapped_page);
279         return ret;
280 }
281
282 /*
283  * Like copy_strings, but get argv and its values from kernel memory.
284  */
285 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
286 {
287         int r;
288         mm_segment_t oldfs = get_fs();
289         set_fs(KERNEL_DS);
290         r = copy_strings(argc, (char __user * __user *)argv, bprm);
291         set_fs(oldfs);
292         return r;
293 }
294
295 EXPORT_SYMBOL(copy_strings_kernel);
296
297 #ifdef CONFIG_MMU
298 /*
299  * This routine is used to map in a page into an address space: needed by
300  * execve() for the initial stack and environment pages.
301  *
302  * vma->vm_mm->mmap_sem is held for writing.
303  */
304 void install_arg_page(struct vm_area_struct *vma,
305                         struct page *page, unsigned long address)
306 {
307         struct mm_struct *mm = vma->vm_mm;
308         pgd_t * pgd;
309         pud_t * pud;
310         pmd_t * pmd;
311         pte_t * pte;
312
313         if (unlikely(anon_vma_prepare(vma)))
314                 goto out_sig;
315
316         flush_dcache_page(page);
317         pgd = pgd_offset(mm, address);
318
319         spin_lock(&mm->page_table_lock);
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(mm, pmd, address);
327         if (!pte)
328                 goto out;
329         if (!pte_none(*pte)) {
330                 pte_unmap(pte);
331                 goto out;
332         }
333         inc_mm_counter(mm, 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(pte);
339         spin_unlock(&mm->page_table_lock);
340
341         /* no need for flush_tlb */
342         return;
343 out:
344         spin_unlock(&mm->page_table_lock);
345 out_sig:
346         __free_page(page);
347         force_sig(SIGKILL, current);
348 }
349
350 #define EXTRA_STACK_VM_PAGES    20      /* random */
351
352 int setup_arg_pages(struct linux_binprm *bprm,
353                     unsigned long stack_top,
354                     int executable_stack)
355 {
356         unsigned long stack_base;
357         struct vm_area_struct *mpnt;
358         struct mm_struct *mm = current->mm;
359         int i, ret;
360         long arg_size;
361
362 #ifdef CONFIG_STACK_GROWSUP
363         /* Move the argument and environment strings to the bottom of the
364          * stack space.
365          */
366         int offset, j;
367         char *to, *from;
368
369         /* Start by shifting all the pages down */
370         i = 0;
371         for (j = 0; j < MAX_ARG_PAGES; j++) {
372                 struct page *page = bprm->page[j];
373                 if (!page)
374                         continue;
375                 bprm->page[i++] = page;
376         }
377
378         /* Now move them within their pages */
379         offset = bprm->p % PAGE_SIZE;
380         to = kmap(bprm->page[0]);
381         for (j = 1; j < i; j++) {
382                 memmove(to, to + offset, PAGE_SIZE - offset);
383                 from = kmap(bprm->page[j]);
384                 memcpy(to + PAGE_SIZE - offset, from, offset);
385                 kunmap(bprm->page[j - 1]);
386                 to = from;
387         }
388         memmove(to, to + offset, PAGE_SIZE - offset);
389         kunmap(bprm->page[j - 1]);
390
391         /* Limit stack size to 1GB */
392         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
393         if (stack_base > (1 << 30))
394                 stack_base = 1 << 30;
395         stack_base = PAGE_ALIGN(stack_top - stack_base);
396
397         /* Adjust bprm->p to point to the end of the strings. */
398         bprm->p = stack_base + PAGE_SIZE * i - offset;
399
400         mm->arg_start = stack_base;
401         arg_size = i << PAGE_SHIFT;
402
403         /* zero pages that were copied above */
404         while (i < MAX_ARG_PAGES)
405                 bprm->page[i++] = NULL;
406 #else
407         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
408         stack_base = PAGE_ALIGN(stack_base);
409         bprm->p += stack_base;
410         mm->arg_start = bprm->p;
411         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
412 #endif
413
414         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
415
416         if (bprm->loader)
417                 bprm->loader += stack_base;
418         bprm->exec += stack_base;
419
420         mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
421         if (!mpnt)
422                 return -ENOMEM;
423
424         if (security_vm_enough_memory(arg_size >> PAGE_SHIFT)) {
425                 kmem_cache_free(vm_area_cachep, mpnt);
426                 return -ENOMEM;
427         }
428
429         memset(mpnt, 0, sizeof(*mpnt));
430
431         down_write(&mm->mmap_sem);
432         {
433                 mpnt->vm_mm = mm;
434 #ifdef CONFIG_STACK_GROWSUP
435                 mpnt->vm_start = stack_base;
436                 mpnt->vm_end = stack_base + arg_size;
437 #else
438                 mpnt->vm_end = stack_top;
439                 mpnt->vm_start = mpnt->vm_end - arg_size;
440 #endif
441                 /* Adjust stack execute permissions; explicitly enable
442                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
443                  * and leave alone (arch default) otherwise. */
444                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
445                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
446                 else if (executable_stack == EXSTACK_DISABLE_X)
447                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
448                 else
449                         mpnt->vm_flags = VM_STACK_FLAGS;
450                 mpnt->vm_flags |= mm->def_flags;
451                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
452                 if ((ret = insert_vm_struct(mm, mpnt))) {
453                         up_write(&mm->mmap_sem);
454                         kmem_cache_free(vm_area_cachep, mpnt);
455                         return ret;
456                 }
457                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
458         }
459
460         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
461                 struct page *page = bprm->page[i];
462                 if (page) {
463                         bprm->page[i] = NULL;
464                         install_arg_page(mpnt, page, stack_base);
465                 }
466                 stack_base += PAGE_SIZE;
467         }
468         up_write(&mm->mmap_sem);
469         
470         return 0;
471 }
472
473 EXPORT_SYMBOL(setup_arg_pages);
474
475 #define free_arg_pages(bprm) do { } while (0)
476
477 #else
478
479 static inline void free_arg_pages(struct linux_binprm *bprm)
480 {
481         int i;
482
483         for (i = 0; i < MAX_ARG_PAGES; i++) {
484                 if (bprm->page[i])
485                         __free_page(bprm->page[i]);
486                 bprm->page[i] = NULL;
487         }
488 }
489
490 #endif /* CONFIG_MMU */
491
492 struct file *open_exec(const char *name)
493 {
494         struct nameidata nd;
495         int err;
496         struct file *file;
497
498         nd.intent.open.flags = FMODE_READ;
499         err = path_lookup(name, LOOKUP_FOLLOW|LOOKUP_OPEN, &nd);
500         file = ERR_PTR(err);
501
502         if (!err) {
503                 struct inode *inode = nd.dentry->d_inode;
504                 file = ERR_PTR(-EACCES);
505                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
506                     S_ISREG(inode->i_mode)) {
507                         int err = permission(inode, MAY_EXEC, &nd);
508                         if (!err && !(inode->i_mode & 0111))
509                                 err = -EACCES;
510                         file = ERR_PTR(err);
511                         if (!err) {
512                                 file = dentry_open(nd.dentry, nd.mnt, O_RDONLY);
513                                 if (!IS_ERR(file)) {
514                                         err = deny_write_access(file);
515                                         if (err) {
516                                                 fput(file);
517                                                 file = ERR_PTR(err);
518                                         }
519                                 }
520 out:
521                                 return file;
522                         }
523                 }
524                 path_release(&nd);
525         }
526         goto out;
527 }
528
529 EXPORT_SYMBOL(open_exec);
530
531 int kernel_read(struct file *file, unsigned long offset,
532         char *addr, unsigned long count)
533 {
534         mm_segment_t old_fs;
535         loff_t pos = offset;
536         int result;
537
538         old_fs = get_fs();
539         set_fs(get_ds());
540         /* The cast to a user pointer is valid due to the set_fs() */
541         result = vfs_read(file, (void __user *)addr, count, &pos);
542         set_fs(old_fs);
543         return result;
544 }
545
546 EXPORT_SYMBOL(kernel_read);
547
548 static int exec_mmap(struct mm_struct *mm)
549 {
550         struct task_struct *tsk;
551         struct mm_struct * old_mm, *active_mm;
552
553         /* Notify parent that we're no longer interested in the old VM */
554         tsk = current;
555         old_mm = current->mm;
556         mm_release(tsk, old_mm);
557
558         if (old_mm) {
559                 /*
560                  * Make sure that if there is a core dump in progress
561                  * for the old mm, we get out and die instead of going
562                  * through with the exec.  We must hold mmap_sem around
563                  * checking core_waiters and changing tsk->mm.  The
564                  * core-inducing thread will increment core_waiters for
565                  * each thread whose ->mm == old_mm.
566                  */
567                 down_read(&old_mm->mmap_sem);
568                 if (unlikely(old_mm->core_waiters)) {
569                         up_read(&old_mm->mmap_sem);
570                         return -EINTR;
571                 }
572         }
573         task_lock(tsk);
574         active_mm = tsk->active_mm;
575         tsk->mm = mm;
576         tsk->active_mm = mm;
577         activate_mm(active_mm, mm);
578         task_unlock(tsk);
579         arch_pick_mmap_layout(mm);
580         if (old_mm) {
581                 up_read(&old_mm->mmap_sem);
582                 if (active_mm != old_mm) BUG();
583                 mmput(old_mm);
584                 return 0;
585         }
586         mmdrop(active_mm);
587         return 0;
588 }
589
590 /*
591  * This function makes sure the current process has its own signal table,
592  * so that flush_signal_handlers can later reset the handlers without
593  * disturbing other processes.  (Other processes might share the signal
594  * table via the CLONE_SIGHAND option to clone().)
595  */
596 static inline int de_thread(struct task_struct *tsk)
597 {
598         struct signal_struct *sig = tsk->signal;
599         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
600         spinlock_t *lock = &oldsighand->siglock;
601         int count;
602
603         /*
604          * If we don't share sighandlers, then we aren't sharing anything
605          * and we can just re-use it all.
606          */
607         if (atomic_read(&oldsighand->count) <= 1) {
608                 BUG_ON(atomic_read(&sig->count) != 1);
609                 exit_itimers(sig);
610                 return 0;
611         }
612
613         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
614         if (!newsighand)
615                 return -ENOMEM;
616
617         if (thread_group_empty(current))
618                 goto no_thread_group;
619
620         /*
621          * Kill all other threads in the thread group.
622          * We must hold tasklist_lock to call zap_other_threads.
623          */
624         read_lock(&tasklist_lock);
625         spin_lock_irq(lock);
626         if (sig->flags & SIGNAL_GROUP_EXIT) {
627                 /*
628                  * Another group action in progress, just
629                  * return so that the signal is processed.
630                  */
631                 spin_unlock_irq(lock);
632                 read_unlock(&tasklist_lock);
633                 kmem_cache_free(sighand_cachep, newsighand);
634                 return -EAGAIN;
635         }
636         zap_other_threads(current);
637         read_unlock(&tasklist_lock);
638
639         /*
640          * Account for the thread group leader hanging around:
641          */
642         count = 2;
643         if (thread_group_leader(current))
644                 count = 1;
645         else {
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->real_timer.data = (unsigned long)current;
654                 if (del_timer_sync(&sig->real_timer))
655                         add_timer(&sig->real_timer);
656         }
657         while (atomic_read(&sig->count) > count) {
658                 sig->group_exit_task = current;
659                 sig->notify_count = count;
660                 __set_current_state(TASK_UNINTERRUPTIBLE);
661                 spin_unlock_irq(lock);
662                 schedule();
663                 spin_lock_irq(lock);
664         }
665         sig->group_exit_task = NULL;
666         sig->notify_count = 0;
667         sig->real_timer.data = (unsigned long)current;
668         spin_unlock_irq(lock);
669
670         /*
671          * At this point all other threads have exited, all we have to
672          * do is to wait for the thread group leader to become inactive,
673          * and to assume its PID:
674          */
675         if (!thread_group_leader(current)) {
676                 struct task_struct *leader = current->group_leader, *parent;
677                 struct dentry *proc_dentry1, *proc_dentry2;
678                 unsigned long exit_state, ptrace;
679
680                 /*
681                  * Wait for the thread group leader to be a zombie.
682                  * It should already be zombie at this point, most
683                  * of the time.
684                  */
685                 while (leader->exit_state != EXIT_ZOMBIE)
686                         yield();
687
688                 spin_lock(&leader->proc_lock);
689                 spin_lock(&current->proc_lock);
690                 proc_dentry1 = proc_pid_unhash(current);
691                 proc_dentry2 = proc_pid_unhash(leader);
692                 write_lock_irq(&tasklist_lock);
693
694                 BUG_ON(leader->tgid != current->tgid);
695                 BUG_ON(current->pid == current->tgid);
696                 /*
697                  * An exec() starts a new thread group with the
698                  * TGID of the previous thread group. Rehash the
699                  * two threads with a switched PID, and release
700                  * the former thread group leader:
701                  */
702                 ptrace = leader->ptrace;
703                 parent = leader->parent;
704                 if (unlikely(ptrace) && unlikely(parent == current)) {
705                         /*
706                          * Joker was ptracing his own group leader,
707                          * and now he wants to be his own parent!
708                          * We can't have that.
709                          */
710                         ptrace = 0;
711                 }
712
713                 ptrace_unlink(current);
714                 ptrace_unlink(leader);
715                 remove_parent(current);
716                 remove_parent(leader);
717
718                 switch_exec_pids(leader, current);
719
720                 current->parent = current->real_parent = leader->real_parent;
721                 leader->parent = leader->real_parent = child_reaper;
722                 current->group_leader = current;
723                 leader->group_leader = leader;
724
725                 add_parent(current, current->parent);
726                 add_parent(leader, leader->parent);
727                 if (ptrace) {
728                         current->ptrace = ptrace;
729                         __ptrace_link(current, parent);
730                 }
731
732                 list_del(&current->tasks);
733                 list_add_tail(&current->tasks, &init_task.tasks);
734                 current->exit_signal = SIGCHLD;
735                 exit_state = leader->exit_state;
736
737                 write_unlock_irq(&tasklist_lock);
738                 spin_unlock(&leader->proc_lock);
739                 spin_unlock(&current->proc_lock);
740                 proc_pid_flush(proc_dentry1);
741                 proc_pid_flush(proc_dentry2);
742
743                 BUG_ON(exit_state != EXIT_ZOMBIE);
744                 release_task(leader);
745         }
746
747         /*
748          * There may be one thread left which is just exiting,
749          * but it's safe to stop telling the group to kill themselves.
750          */
751         sig->flags = 0;
752
753 no_thread_group:
754         BUG_ON(atomic_read(&sig->count) != 1);
755         exit_itimers(sig);
756
757         if (atomic_read(&oldsighand->count) == 1) {
758                 /*
759                  * Now that we nuked the rest of the thread group,
760                  * it turns out we are not sharing sighand any more either.
761                  * So we can just keep it.
762                  */
763                 kmem_cache_free(sighand_cachep, newsighand);
764         } else {
765                 /*
766                  * Move our state over to newsighand and switch it in.
767                  */
768                 spin_lock_init(&newsighand->siglock);
769                 atomic_set(&newsighand->count, 1);
770                 memcpy(newsighand->action, oldsighand->action,
771                        sizeof(newsighand->action));
772
773                 write_lock_irq(&tasklist_lock);
774                 spin_lock(&oldsighand->siglock);
775                 spin_lock(&newsighand->siglock);
776
777                 current->sighand = newsighand;
778                 recalc_sigpending();
779
780                 spin_unlock(&newsighand->siglock);
781                 spin_unlock(&oldsighand->siglock);
782                 write_unlock_irq(&tasklist_lock);
783
784                 if (atomic_dec_and_test(&oldsighand->count))
785                         kmem_cache_free(sighand_cachep, oldsighand);
786         }
787
788         BUG_ON(!thread_group_leader(current));
789         return 0;
790 }
791         
792 /*
793  * These functions flushes out all traces of the currently running executable
794  * so that a new one can be started
795  */
796
797 static inline void flush_old_files(struct files_struct * files)
798 {
799         long j = -1;
800         struct fdtable *fdt;
801
802         spin_lock(&files->file_lock);
803         for (;;) {
804                 unsigned long set, i;
805
806                 j++;
807                 i = j * __NFDBITS;
808                 fdt = files_fdtable(files);
809                 if (i >= fdt->max_fds || i >= fdt->max_fdset)
810                         break;
811                 set = fdt->close_on_exec->fds_bits[j];
812                 if (!set)
813                         continue;
814                 fdt->close_on_exec->fds_bits[j] = 0;
815                 spin_unlock(&files->file_lock);
816                 for ( ; set ; i++,set >>= 1) {
817                         if (set & 1) {
818                                 sys_close(i);
819                         }
820                 }
821                 spin_lock(&files->file_lock);
822
823         }
824         spin_unlock(&files->file_lock);
825 }
826
827 void get_task_comm(char *buf, struct task_struct *tsk)
828 {
829         /* buf must be at least sizeof(tsk->comm) in size */
830         task_lock(tsk);
831         strncpy(buf, tsk->comm, sizeof(tsk->comm));
832         task_unlock(tsk);
833 }
834
835 void set_task_comm(struct task_struct *tsk, char *buf)
836 {
837         task_lock(tsk);
838         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
839         task_unlock(tsk);
840 }
841
842 int flush_old_exec(struct linux_binprm * bprm)
843 {
844         char * name;
845         int i, ch, retval;
846         struct files_struct *files;
847         char tcomm[sizeof(current->comm)];
848
849         /*
850          * Make sure we have a private signal table and that
851          * we are unassociated from the previous thread group.
852          */
853         retval = de_thread(current);
854         if (retval)
855                 goto out;
856
857         /*
858          * Make sure we have private file handles. Ask the
859          * fork helper to do the work for us and the exit
860          * helper to do the cleanup of the old one.
861          */
862         files = current->files;         /* refcounted so safe to hold */
863         retval = unshare_files();
864         if (retval)
865                 goto out;
866         /*
867          * Release all of the old mmap stuff
868          */
869         retval = exec_mmap(bprm->mm);
870         if (retval)
871                 goto mmap_failed;
872
873         bprm->mm = NULL;                /* We're using it now */
874
875         /* This is the point of no return */
876         steal_locks(files);
877         put_files_struct(files);
878
879         current->sas_ss_sp = current->sas_ss_size = 0;
880
881         if (current->euid == current->uid && current->egid == current->gid)
882                 current->mm->dumpable = 1;
883         else
884                 current->mm->dumpable = suid_dumpable;
885
886         name = bprm->filename;
887
888         /* Copies the binary name from after last slash */
889         for (i=0; (ch = *(name++)) != '\0';) {
890                 if (ch == '/')
891                         i = 0; /* overwrite what we wrote */
892                 else
893                         if (i < (sizeof(tcomm) - 1))
894                                 tcomm[i++] = ch;
895         }
896         tcomm[i] = '\0';
897         set_task_comm(current, tcomm);
898
899         current->flags &= ~PF_RANDOMIZE;
900         flush_thread();
901
902         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
903             permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
904             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
905                 suid_keys(current);
906                 current->mm->dumpable = suid_dumpable;
907         }
908
909         /* An exec changes our domain. We are no longer part of the thread
910            group */
911
912         current->self_exec_id++;
913                         
914         flush_signal_handlers(current, 0);
915         flush_old_files(current->files);
916
917         return 0;
918
919 mmap_failed:
920         put_files_struct(current->files);
921         current->files = files;
922 out:
923         return retval;
924 }
925
926 EXPORT_SYMBOL(flush_old_exec);
927
928 /* 
929  * Fill the binprm structure from the inode. 
930  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
931  */
932 int prepare_binprm(struct linux_binprm *bprm)
933 {
934         int mode;
935         struct inode * inode = bprm->file->f_dentry->d_inode;
936         int retval;
937
938         mode = inode->i_mode;
939         /*
940          * Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
941          * generic_permission lets a non-executable through
942          */
943         if (!(mode & 0111))     /* with at least _one_ execute bit set */
944                 return -EACCES;
945         if (bprm->file->f_op == NULL)
946                 return -EACCES;
947
948         bprm->e_uid = current->euid;
949         bprm->e_gid = current->egid;
950
951         if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
952                 /* Set-uid? */
953                 if (mode & S_ISUID) {
954                         current->personality &= ~PER_CLEAR_ON_SETID;
955                         bprm->e_uid = inode->i_uid;
956                 }
957
958                 /* Set-gid? */
959                 /*
960                  * If setgid is set but no group execute bit then this
961                  * is a candidate for mandatory locking, not a setgid
962                  * executable.
963                  */
964                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
965                         current->personality &= ~PER_CLEAR_ON_SETID;
966                         bprm->e_gid = inode->i_gid;
967                 }
968         }
969
970         /* fill in binprm security blob */
971         retval = security_bprm_set(bprm);
972         if (retval)
973                 return retval;
974
975         memset(bprm->buf,0,BINPRM_BUF_SIZE);
976         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
977 }
978
979 EXPORT_SYMBOL(prepare_binprm);
980
981 static inline int unsafe_exec(struct task_struct *p)
982 {
983         int unsafe = 0;
984         if (p->ptrace & PT_PTRACED) {
985                 if (p->ptrace & PT_PTRACE_CAP)
986                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
987                 else
988                         unsafe |= LSM_UNSAFE_PTRACE;
989         }
990         if (atomic_read(&p->fs->count) > 1 ||
991             atomic_read(&p->files->count) > 1 ||
992             atomic_read(&p->sighand->count) > 1)
993                 unsafe |= LSM_UNSAFE_SHARE;
994
995         return unsafe;
996 }
997
998 void compute_creds(struct linux_binprm *bprm)
999 {
1000         int unsafe;
1001
1002         if (bprm->e_uid != current->uid)
1003                 suid_keys(current);
1004         exec_keys(current);
1005
1006         task_lock(current);
1007         unsafe = unsafe_exec(current);
1008         security_bprm_apply_creds(bprm, unsafe);
1009         task_unlock(current);
1010         security_bprm_post_apply_creds(bprm);
1011 }
1012
1013 EXPORT_SYMBOL(compute_creds);
1014
1015 void remove_arg_zero(struct linux_binprm *bprm)
1016 {
1017         if (bprm->argc) {
1018                 unsigned long offset;
1019                 char * kaddr;
1020                 struct page *page;
1021
1022                 offset = bprm->p % PAGE_SIZE;
1023                 goto inside;
1024
1025                 while (bprm->p++, *(kaddr+offset++)) {
1026                         if (offset != PAGE_SIZE)
1027                                 continue;
1028                         offset = 0;
1029                         kunmap_atomic(kaddr, KM_USER0);
1030 inside:
1031                         page = bprm->page[bprm->p/PAGE_SIZE];
1032                         kaddr = kmap_atomic(page, KM_USER0);
1033                 }
1034                 kunmap_atomic(kaddr, KM_USER0);
1035                 bprm->argc--;
1036         }
1037 }
1038
1039 EXPORT_SYMBOL(remove_arg_zero);
1040
1041 /*
1042  * cycle the list of binary formats handler, until one recognizes the image
1043  */
1044 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1045 {
1046         int try,retval;
1047         struct linux_binfmt *fmt;
1048 #ifdef __alpha__
1049         /* handle /sbin/loader.. */
1050         {
1051             struct exec * eh = (struct exec *) bprm->buf;
1052
1053             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1054                 (eh->fh.f_flags & 0x3000) == 0x3000)
1055             {
1056                 struct file * file;
1057                 unsigned long loader;
1058
1059                 allow_write_access(bprm->file);
1060                 fput(bprm->file);
1061                 bprm->file = NULL;
1062
1063                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1064
1065                 file = open_exec("/sbin/loader");
1066                 retval = PTR_ERR(file);
1067                 if (IS_ERR(file))
1068                         return retval;
1069
1070                 /* Remember if the application is TASO.  */
1071                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1072
1073                 bprm->file = file;
1074                 bprm->loader = loader;
1075                 retval = prepare_binprm(bprm);
1076                 if (retval<0)
1077                         return retval;
1078                 /* should call search_binary_handler recursively here,
1079                    but it does not matter */
1080             }
1081         }
1082 #endif
1083         retval = security_bprm_check(bprm);
1084         if (retval)
1085                 return retval;
1086
1087         /* kernel module loader fixup */
1088         /* so we don't try to load run modprobe in kernel space. */
1089         set_fs(USER_DS);
1090         retval = -ENOENT;
1091         for (try=0; try<2; try++) {
1092                 read_lock(&binfmt_lock);
1093                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1094                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1095                         if (!fn)
1096                                 continue;
1097                         if (!try_module_get(fmt->module))
1098                                 continue;
1099                         read_unlock(&binfmt_lock);
1100                         retval = fn(bprm, regs);
1101                         if (retval >= 0) {
1102                                 put_binfmt(fmt);
1103                                 allow_write_access(bprm->file);
1104                                 if (bprm->file)
1105                                         fput(bprm->file);
1106                                 bprm->file = NULL;
1107                                 current->did_exec = 1;
1108                                 return retval;
1109                         }
1110                         read_lock(&binfmt_lock);
1111                         put_binfmt(fmt);
1112                         if (retval != -ENOEXEC || bprm->mm == NULL)
1113                                 break;
1114                         if (!bprm->file) {
1115                                 read_unlock(&binfmt_lock);
1116                                 return retval;
1117                         }
1118                 }
1119                 read_unlock(&binfmt_lock);
1120                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1121                         break;
1122 #ifdef CONFIG_KMOD
1123                 }else{
1124 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1125                         if (printable(bprm->buf[0]) &&
1126                             printable(bprm->buf[1]) &&
1127                             printable(bprm->buf[2]) &&
1128                             printable(bprm->buf[3]))
1129                                 break; /* -ENOEXEC */
1130                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1131 #endif
1132                 }
1133         }
1134         return retval;
1135 }
1136
1137 EXPORT_SYMBOL(search_binary_handler);
1138
1139 /*
1140  * sys_execve() executes a new program.
1141  */
1142 int do_execve(char * filename,
1143         char __user *__user *argv,
1144         char __user *__user *envp,
1145         struct pt_regs * regs)
1146 {
1147         struct linux_binprm *bprm;
1148         struct file *file;
1149         int retval;
1150         int i;
1151
1152         retval = -ENOMEM;
1153         bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
1154         if (!bprm)
1155                 goto out_ret;
1156         memset(bprm, 0, sizeof(*bprm));
1157
1158         file = open_exec(filename);
1159         retval = PTR_ERR(file);
1160         if (IS_ERR(file))
1161                 goto out_kfree;
1162
1163         sched_exec();
1164
1165         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1166
1167         bprm->file = file;
1168         bprm->filename = filename;
1169         bprm->interp = filename;
1170         bprm->mm = mm_alloc();
1171         retval = -ENOMEM;
1172         if (!bprm->mm)
1173                 goto out_file;
1174
1175         retval = init_new_context(current, bprm->mm);
1176         if (retval < 0)
1177                 goto out_mm;
1178
1179         bprm->argc = count(argv, bprm->p / sizeof(void *));
1180         if ((retval = bprm->argc) < 0)
1181                 goto out_mm;
1182
1183         bprm->envc = count(envp, bprm->p / sizeof(void *));
1184         if ((retval = bprm->envc) < 0)
1185                 goto out_mm;
1186
1187         retval = security_bprm_alloc(bprm);
1188         if (retval)
1189                 goto out;
1190
1191         retval = prepare_binprm(bprm);
1192         if (retval < 0)
1193                 goto out;
1194
1195         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1196         if (retval < 0)
1197                 goto out;
1198
1199         bprm->exec = bprm->p;
1200         retval = copy_strings(bprm->envc, envp, bprm);
1201         if (retval < 0)
1202                 goto out;
1203
1204         retval = copy_strings(bprm->argc, argv, bprm);
1205         if (retval < 0)
1206                 goto out;
1207
1208         retval = search_binary_handler(bprm,regs);
1209         if (retval >= 0) {
1210                 free_arg_pages(bprm);
1211
1212                 /* execve success */
1213                 security_bprm_free(bprm);
1214                 acct_update_integrals(current);
1215                 update_mem_hiwater(current);
1216                 kfree(bprm);
1217                 return retval;
1218         }
1219
1220 out:
1221         /* Something went wrong, return the inode and free the argument pages*/
1222         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1223                 struct page * page = bprm->page[i];
1224                 if (page)
1225                         __free_page(page);
1226         }
1227
1228         if (bprm->security)
1229                 security_bprm_free(bprm);
1230
1231 out_mm:
1232         if (bprm->mm)
1233                 mmdrop(bprm->mm);
1234
1235 out_file:
1236         if (bprm->file) {
1237                 allow_write_access(bprm->file);
1238                 fput(bprm->file);
1239         }
1240
1241 out_kfree:
1242         kfree(bprm);
1243
1244 out_ret:
1245         return retval;
1246 }
1247
1248 int set_binfmt(struct linux_binfmt *new)
1249 {
1250         struct linux_binfmt *old = current->binfmt;
1251
1252         if (new) {
1253                 if (!try_module_get(new->module))
1254                         return -1;
1255         }
1256         current->binfmt = new;
1257         if (old)
1258                 module_put(old->module);
1259         return 0;
1260 }
1261
1262 EXPORT_SYMBOL(set_binfmt);
1263
1264 #define CORENAME_MAX_SIZE 64
1265
1266 /* format_corename will inspect the pattern parameter, and output a
1267  * name into corename, which must have space for at least
1268  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1269  */
1270 static void format_corename(char *corename, const char *pattern, long signr)
1271 {
1272         const char *pat_ptr = pattern;
1273         char *out_ptr = corename;
1274         char *const out_end = corename + CORENAME_MAX_SIZE;
1275         int rc;
1276         int pid_in_pattern = 0;
1277
1278         /* Repeat as long as we have more pattern to process and more output
1279            space */
1280         while (*pat_ptr) {
1281                 if (*pat_ptr != '%') {
1282                         if (out_ptr == out_end)
1283                                 goto out;
1284                         *out_ptr++ = *pat_ptr++;
1285                 } else {
1286                         switch (*++pat_ptr) {
1287                         case 0:
1288                                 goto out;
1289                         /* Double percent, output one percent */
1290                         case '%':
1291                                 if (out_ptr == out_end)
1292                                         goto out;
1293                                 *out_ptr++ = '%';
1294                                 break;
1295                         /* pid */
1296                         case 'p':
1297                                 pid_in_pattern = 1;
1298                                 rc = snprintf(out_ptr, out_end - out_ptr,
1299                                               "%d", current->tgid);
1300                                 if (rc > out_end - out_ptr)
1301                                         goto out;
1302                                 out_ptr += rc;
1303                                 break;
1304                         /* uid */
1305                         case 'u':
1306                                 rc = snprintf(out_ptr, out_end - out_ptr,
1307                                               "%d", current->uid);
1308                                 if (rc > out_end - out_ptr)
1309                                         goto out;
1310                                 out_ptr += rc;
1311                                 break;
1312                         /* gid */
1313                         case 'g':
1314                                 rc = snprintf(out_ptr, out_end - out_ptr,
1315                                               "%d", current->gid);
1316                                 if (rc > out_end - out_ptr)
1317                                         goto out;
1318                                 out_ptr += rc;
1319                                 break;
1320                         /* signal that caused the coredump */
1321                         case 's':
1322                                 rc = snprintf(out_ptr, out_end - out_ptr,
1323                                               "%ld", signr);
1324                                 if (rc > out_end - out_ptr)
1325                                         goto out;
1326                                 out_ptr += rc;
1327                                 break;
1328                         /* UNIX time of coredump */
1329                         case 't': {
1330                                 struct timeval tv;
1331                                 do_gettimeofday(&tv);
1332                                 rc = snprintf(out_ptr, out_end - out_ptr,
1333                                               "%lu", tv.tv_sec);
1334                                 if (rc > out_end - out_ptr)
1335                                         goto out;
1336                                 out_ptr += rc;
1337                                 break;
1338                         }
1339                         /* hostname */
1340                         case 'h':
1341                                 down_read(&uts_sem);
1342                                 rc = snprintf(out_ptr, out_end - out_ptr,
1343                                               "%s", system_utsname.nodename);
1344                                 up_read(&uts_sem);
1345                                 if (rc > out_end - out_ptr)
1346                                         goto out;
1347                                 out_ptr += rc;
1348                                 break;
1349                         /* executable */
1350                         case 'e':
1351                                 rc = snprintf(out_ptr, out_end - out_ptr,
1352                                               "%s", current->comm);
1353                                 if (rc > out_end - out_ptr)
1354                                         goto out;
1355                                 out_ptr += rc;
1356                                 break;
1357                         default:
1358                                 break;
1359                         }
1360                         ++pat_ptr;
1361                 }
1362         }
1363         /* Backward compatibility with core_uses_pid:
1364          *
1365          * If core_pattern does not include a %p (as is the default)
1366          * and core_uses_pid is set, then .%pid will be appended to
1367          * the filename */
1368         if (!pid_in_pattern
1369             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1370                 rc = snprintf(out_ptr, out_end - out_ptr,
1371                               ".%d", current->tgid);
1372                 if (rc > out_end - out_ptr)
1373                         goto out;
1374                 out_ptr += rc;
1375         }
1376       out:
1377         *out_ptr = 0;
1378 }
1379
1380 static void zap_threads (struct mm_struct *mm)
1381 {
1382         struct task_struct *g, *p;
1383         struct task_struct *tsk = current;
1384         struct completion *vfork_done = tsk->vfork_done;
1385         int traced = 0;
1386
1387         /*
1388          * Make sure nobody is waiting for us to release the VM,
1389          * otherwise we can deadlock when we wait on each other
1390          */
1391         if (vfork_done) {
1392                 tsk->vfork_done = NULL;
1393                 complete(vfork_done);
1394         }
1395
1396         read_lock(&tasklist_lock);
1397         do_each_thread(g,p)
1398                 if (mm == p->mm && p != tsk) {
1399                         force_sig_specific(SIGKILL, p);
1400                         mm->core_waiters++;
1401                         if (unlikely(p->ptrace) &&
1402                             unlikely(p->parent->mm == mm))
1403                                 traced = 1;
1404                 }
1405         while_each_thread(g,p);
1406
1407         read_unlock(&tasklist_lock);
1408
1409         if (unlikely(traced)) {
1410                 /*
1411                  * We are zapping a thread and the thread it ptraces.
1412                  * If the tracee went into a ptrace stop for exit tracing,
1413                  * we could deadlock since the tracer is waiting for this
1414                  * coredump to finish.  Detach them so they can both die.
1415                  */
1416                 write_lock_irq(&tasklist_lock);
1417                 do_each_thread(g,p) {
1418                         if (mm == p->mm && p != tsk &&
1419                             p->ptrace && p->parent->mm == mm) {
1420                                 __ptrace_unlink(p);
1421                         }
1422                 } while_each_thread(g,p);
1423                 write_unlock_irq(&tasklist_lock);
1424         }
1425 }
1426
1427 static void coredump_wait(struct mm_struct *mm)
1428 {
1429         DECLARE_COMPLETION(startup_done);
1430
1431         mm->core_waiters++; /* let other threads block */
1432         mm->core_startup_done = &startup_done;
1433
1434         /* give other threads a chance to run: */
1435         yield();
1436
1437         zap_threads(mm);
1438         if (--mm->core_waiters) {
1439                 up_write(&mm->mmap_sem);
1440                 wait_for_completion(&startup_done);
1441         } else
1442                 up_write(&mm->mmap_sem);
1443         BUG_ON(mm->core_waiters);
1444 }
1445
1446 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1447 {
1448         char corename[CORENAME_MAX_SIZE + 1];
1449         struct mm_struct *mm = current->mm;
1450         struct linux_binfmt * binfmt;
1451         struct inode * inode;
1452         struct file * file;
1453         int retval = 0;
1454         int fsuid = current->fsuid;
1455         int flag = 0;
1456
1457         binfmt = current->binfmt;
1458         if (!binfmt || !binfmt->core_dump)
1459                 goto fail;
1460         down_write(&mm->mmap_sem);
1461         if (!mm->dumpable) {
1462                 up_write(&mm->mmap_sem);
1463                 goto fail;
1464         }
1465
1466         /*
1467          *      We cannot trust fsuid as being the "true" uid of the
1468          *      process nor do we know its entire history. We only know it
1469          *      was tainted so we dump it as root in mode 2.
1470          */
1471         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1472                 flag = O_EXCL;          /* Stop rewrite attacks */
1473                 current->fsuid = 0;     /* Dump root private */
1474         }
1475         mm->dumpable = 0;
1476         init_completion(&mm->core_done);
1477         spin_lock_irq(&current->sighand->siglock);
1478         current->signal->flags = SIGNAL_GROUP_EXIT;
1479         current->signal->group_exit_code = exit_code;
1480         spin_unlock_irq(&current->sighand->siglock);
1481         coredump_wait(mm);
1482
1483         /*
1484          * Clear any false indication of pending signals that might
1485          * be seen by the filesystem code called to write the core file.
1486          */
1487         current->signal->group_stop_count = 0;
1488         clear_thread_flag(TIF_SIGPENDING);
1489
1490         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1491                 goto fail_unlock;
1492
1493         /*
1494          * lock_kernel() because format_corename() is controlled by sysctl, which
1495          * uses lock_kernel()
1496          */
1497         lock_kernel();
1498         format_corename(corename, core_pattern, signr);
1499         unlock_kernel();
1500         file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
1501         if (IS_ERR(file))
1502                 goto fail_unlock;
1503         inode = file->f_dentry->d_inode;
1504         if (inode->i_nlink > 1)
1505                 goto close_fail;        /* multiple links - don't dump */
1506         if (d_unhashed(file->f_dentry))
1507                 goto close_fail;
1508
1509         if (!S_ISREG(inode->i_mode))
1510                 goto close_fail;
1511         if (!file->f_op)
1512                 goto close_fail;
1513         if (!file->f_op->write)
1514                 goto close_fail;
1515         if (do_truncate(file->f_dentry, 0) != 0)
1516                 goto close_fail;
1517
1518         retval = binfmt->core_dump(signr, regs, file);
1519
1520         if (retval)
1521                 current->signal->group_exit_code |= 0x80;
1522 close_fail:
1523         filp_close(file, NULL);
1524 fail_unlock:
1525         current->fsuid = fsuid;
1526         complete_all(&mm->core_done);
1527 fail:
1528         return retval;
1529 }