0b685888ff6f9b1c51c860191828adbde4950fe6
[sfrench/cifs-2.6.git] / fs / exec.c
1 /*
2  *  linux/fs/exec.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 /*
8  * #!-checking implemented by tytso.
9  */
10 /*
11  * Demand-loading implemented 01.12.91 - no need to read anything but
12  * the header into memory. The inode of the executable is put into
13  * "current->executable", and page faults do the actual loading. Clean.
14  *
15  * Once more I can proudly say that linux stood up to being changed: it
16  * was less than 2 hours work to get demand-loading completely implemented.
17  *
18  * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
19  * current->executable is only used by the procfs.  This allows a dispatch
20  * table to check for several different types  of binary formats.  We keep
21  * trying until we recognize the file or we run out of supported binary
22  * formats. 
23  */
24
25 #include <linux/slab.h>
26 #include <linux/file.h>
27 #include <linux/mman.h>
28 #include <linux/a.out.h>
29 #include <linux/stat.h>
30 #include <linux/fcntl.h>
31 #include <linux/smp_lock.h>
32 #include <linux/init.h>
33 #include <linux/pagemap.h>
34 #include <linux/highmem.h>
35 #include <linux/spinlock.h>
36 #include <linux/key.h>
37 #include <linux/personality.h>
38 #include <linux/binfmts.h>
39 #include <linux/swap.h>
40 #include <linux/utsname.h>
41 #include <linux/pid_namespace.h>
42 #include <linux/module.h>
43 #include <linux/namei.h>
44 #include <linux/proc_fs.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/security.h>
48 #include <linux/syscalls.h>
49 #include <linux/rmap.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53 #include <linux/signalfd.h>
54
55 #include <asm/uaccess.h>
56 #include <asm/mmu_context.h>
57
58 #ifdef CONFIG_KMOD
59 #include <linux/kmod.h>
60 #endif
61
62 int core_uses_pid;
63 char core_pattern[CORENAME_MAX_SIZE] = "core";
64 int suid_dumpable = 0;
65
66 EXPORT_SYMBOL(suid_dumpable);
67 /* The maximal length of core_pattern is also specified in sysctl.c */
68
69 static struct linux_binfmt *formats;
70 static DEFINE_RWLOCK(binfmt_lock);
71
72 int register_binfmt(struct linux_binfmt * fmt)
73 {
74         struct linux_binfmt ** tmp = &formats;
75
76         if (!fmt)
77                 return -EINVAL;
78         if (fmt->next)
79                 return -EBUSY;
80         write_lock(&binfmt_lock);
81         while (*tmp) {
82                 if (fmt == *tmp) {
83                         write_unlock(&binfmt_lock);
84                         return -EBUSY;
85                 }
86                 tmp = &(*tmp)->next;
87         }
88         fmt->next = formats;
89         formats = fmt;
90         write_unlock(&binfmt_lock);
91         return 0;       
92 }
93
94 EXPORT_SYMBOL(register_binfmt);
95
96 int unregister_binfmt(struct linux_binfmt * fmt)
97 {
98         struct linux_binfmt ** tmp = &formats;
99
100         write_lock(&binfmt_lock);
101         while (*tmp) {
102                 if (fmt == *tmp) {
103                         *tmp = fmt->next;
104                         fmt->next = NULL;
105                         write_unlock(&binfmt_lock);
106                         return 0;
107                 }
108                 tmp = &(*tmp)->next;
109         }
110         write_unlock(&binfmt_lock);
111         return -EINVAL;
112 }
113
114 EXPORT_SYMBOL(unregister_binfmt);
115
116 static inline void put_binfmt(struct linux_binfmt * fmt)
117 {
118         module_put(fmt->module);
119 }
120
121 /*
122  * Note that a shared library must be both readable and executable due to
123  * security reasons.
124  *
125  * Also note that we take the address to load from from the file itself.
126  */
127 asmlinkage long sys_uselib(const char __user * library)
128 {
129         struct file * file;
130         struct nameidata nd;
131         int error;
132
133         error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
134         if (error)
135                 goto out;
136
137         error = -EINVAL;
138         if (!S_ISREG(nd.dentry->d_inode->i_mode))
139                 goto exit;
140
141         error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
142         if (error)
143                 goto exit;
144
145         file = nameidata_to_filp(&nd, O_RDONLY);
146         error = PTR_ERR(file);
147         if (IS_ERR(file))
148                 goto out;
149
150         error = -ENOEXEC;
151         if(file->f_op) {
152                 struct linux_binfmt * fmt;
153
154                 read_lock(&binfmt_lock);
155                 for (fmt = formats ; fmt ; fmt = fmt->next) {
156                         if (!fmt->load_shlib)
157                                 continue;
158                         if (!try_module_get(fmt->module))
159                                 continue;
160                         read_unlock(&binfmt_lock);
161                         error = fmt->load_shlib(file);
162                         read_lock(&binfmt_lock);
163                         put_binfmt(fmt);
164                         if (error != -ENOEXEC)
165                                 break;
166                 }
167                 read_unlock(&binfmt_lock);
168         }
169         fput(file);
170 out:
171         return error;
172 exit:
173         release_open_intent(&nd);
174         path_release(&nd);
175         goto out;
176 }
177
178 /*
179  * count() counts the number of strings in array ARGV.
180  */
181 static int count(char __user * __user * argv, int max)
182 {
183         int i = 0;
184
185         if (argv != NULL) {
186                 for (;;) {
187                         char __user * p;
188
189                         if (get_user(p, argv))
190                                 return -EFAULT;
191                         if (!p)
192                                 break;
193                         argv++;
194                         if(++i > max)
195                                 return -E2BIG;
196                         cond_resched();
197                 }
198         }
199         return i;
200 }
201
202 /*
203  * 'copy_strings()' copies argument/environment strings from user
204  * memory to free pages in kernel mem. These are in a format ready
205  * to be put directly into the top of new user memory.
206  */
207 static int copy_strings(int argc, char __user * __user * argv,
208                         struct linux_binprm *bprm)
209 {
210         struct page *kmapped_page = NULL;
211         char *kaddr = NULL;
212         int ret;
213
214         while (argc-- > 0) {
215                 char __user *str;
216                 int len;
217                 unsigned long pos;
218
219                 if (get_user(str, argv+argc) ||
220                                 !(len = strnlen_user(str, bprm->p))) {
221                         ret = -EFAULT;
222                         goto out;
223                 }
224
225                 if (bprm->p < len)  {
226                         ret = -E2BIG;
227                         goto out;
228                 }
229
230                 bprm->p -= len;
231                 /* XXX: add architecture specific overflow check here. */
232                 pos = bprm->p;
233
234                 while (len > 0) {
235                         int i, new, err;
236                         int offset, bytes_to_copy;
237                         struct page *page;
238
239                         offset = pos % PAGE_SIZE;
240                         i = pos/PAGE_SIZE;
241                         page = bprm->page[i];
242                         new = 0;
243                         if (!page) {
244                                 page = alloc_page(GFP_HIGHUSER);
245                                 bprm->page[i] = page;
246                                 if (!page) {
247                                         ret = -ENOMEM;
248                                         goto out;
249                                 }
250                                 new = 1;
251                         }
252
253                         if (page != kmapped_page) {
254                                 if (kmapped_page)
255                                         kunmap(kmapped_page);
256                                 kmapped_page = page;
257                                 kaddr = kmap(kmapped_page);
258                         }
259                         if (new && offset)
260                                 memset(kaddr, 0, offset);
261                         bytes_to_copy = PAGE_SIZE - offset;
262                         if (bytes_to_copy > len) {
263                                 bytes_to_copy = len;
264                                 if (new)
265                                         memset(kaddr+offset+len, 0,
266                                                 PAGE_SIZE-offset-len);
267                         }
268                         err = copy_from_user(kaddr+offset, str, bytes_to_copy);
269                         if (err) {
270                                 ret = -EFAULT;
271                                 goto out;
272                         }
273
274                         pos += bytes_to_copy;
275                         str += bytes_to_copy;
276                         len -= bytes_to_copy;
277                 }
278         }
279         ret = 0;
280 out:
281         if (kmapped_page)
282                 kunmap(kmapped_page);
283         return ret;
284 }
285
286 /*
287  * Like copy_strings, but get argv and its values from kernel memory.
288  */
289 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
290 {
291         int r;
292         mm_segment_t oldfs = get_fs();
293         set_fs(KERNEL_DS);
294         r = copy_strings(argc, (char __user * __user *)argv, bprm);
295         set_fs(oldfs);
296         return r;
297 }
298
299 EXPORT_SYMBOL(copy_strings_kernel);
300
301 #ifdef CONFIG_MMU
302 /*
303  * This routine is used to map in a page into an address space: needed by
304  * execve() for the initial stack and environment pages.
305  *
306  * vma->vm_mm->mmap_sem is held for writing.
307  */
308 void install_arg_page(struct vm_area_struct *vma,
309                         struct page *page, unsigned long address)
310 {
311         struct mm_struct *mm = vma->vm_mm;
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         pte = get_locked_pte(mm, address, &ptl);
320         if (!pte)
321                 goto out;
322         if (!pte_none(*pte)) {
323                 pte_unmap_unlock(pte, ptl);
324                 goto out;
325         }
326         inc_mm_counter(mm, anon_rss);
327         lru_cache_add_active(page);
328         set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
329                                         page, vma->vm_page_prot))));
330         page_add_new_anon_rmap(page, vma, address);
331         pte_unmap_unlock(pte, ptl);
332
333         /* no need for flush_tlb */
334         return;
335 out:
336         __free_page(page);
337         force_sig(SIGKILL, current);
338 }
339
340 #define EXTRA_STACK_VM_PAGES    20      /* random */
341
342 int setup_arg_pages(struct linux_binprm *bprm,
343                     unsigned long stack_top,
344                     int executable_stack)
345 {
346         unsigned long stack_base;
347         struct vm_area_struct *mpnt;
348         struct mm_struct *mm = current->mm;
349         int i, ret;
350         long arg_size;
351
352 #ifdef CONFIG_STACK_GROWSUP
353         /* Move the argument and environment strings to the bottom of the
354          * stack space.
355          */
356         int offset, j;
357         char *to, *from;
358
359         /* Start by shifting all the pages down */
360         i = 0;
361         for (j = 0; j < MAX_ARG_PAGES; j++) {
362                 struct page *page = bprm->page[j];
363                 if (!page)
364                         continue;
365                 bprm->page[i++] = page;
366         }
367
368         /* Now move them within their pages */
369         offset = bprm->p % PAGE_SIZE;
370         to = kmap(bprm->page[0]);
371         for (j = 1; j < i; j++) {
372                 memmove(to, to + offset, PAGE_SIZE - offset);
373                 from = kmap(bprm->page[j]);
374                 memcpy(to + PAGE_SIZE - offset, from, offset);
375                 kunmap(bprm->page[j - 1]);
376                 to = from;
377         }
378         memmove(to, to + offset, PAGE_SIZE - offset);
379         kunmap(bprm->page[j - 1]);
380
381         /* Limit stack size to 1GB */
382         stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
383         if (stack_base > (1 << 30))
384                 stack_base = 1 << 30;
385         stack_base = PAGE_ALIGN(stack_top - stack_base);
386
387         /* Adjust bprm->p to point to the end of the strings. */
388         bprm->p = stack_base + PAGE_SIZE * i - offset;
389
390         mm->arg_start = stack_base;
391         arg_size = i << PAGE_SHIFT;
392
393         /* zero pages that were copied above */
394         while (i < MAX_ARG_PAGES)
395                 bprm->page[i++] = NULL;
396 #else
397         stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
398         stack_base = PAGE_ALIGN(stack_base);
399         bprm->p += stack_base;
400         mm->arg_start = bprm->p;
401         arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
402 #endif
403
404         arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
405
406         if (bprm->loader)
407                 bprm->loader += stack_base;
408         bprm->exec += stack_base;
409
410         mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
411         if (!mpnt)
412                 return -ENOMEM;
413
414         down_write(&mm->mmap_sem);
415         {
416                 mpnt->vm_mm = mm;
417 #ifdef CONFIG_STACK_GROWSUP
418                 mpnt->vm_start = stack_base;
419                 mpnt->vm_end = stack_base + arg_size;
420 #else
421                 mpnt->vm_end = stack_top;
422                 mpnt->vm_start = mpnt->vm_end - arg_size;
423 #endif
424                 /* Adjust stack execute permissions; explicitly enable
425                  * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
426                  * and leave alone (arch default) otherwise. */
427                 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
428                         mpnt->vm_flags = VM_STACK_FLAGS |  VM_EXEC;
429                 else if (executable_stack == EXSTACK_DISABLE_X)
430                         mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
431                 else
432                         mpnt->vm_flags = VM_STACK_FLAGS;
433                 mpnt->vm_flags |= mm->def_flags;
434                 mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
435                 if ((ret = insert_vm_struct(mm, mpnt))) {
436                         up_write(&mm->mmap_sem);
437                         kmem_cache_free(vm_area_cachep, mpnt);
438                         return ret;
439                 }
440                 mm->stack_vm = mm->total_vm = vma_pages(mpnt);
441         }
442
443         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
444                 struct page *page = bprm->page[i];
445                 if (page) {
446                         bprm->page[i] = NULL;
447                         install_arg_page(mpnt, page, stack_base);
448                 }
449                 stack_base += PAGE_SIZE;
450         }
451         up_write(&mm->mmap_sem);
452         
453         return 0;
454 }
455
456 EXPORT_SYMBOL(setup_arg_pages);
457
458 #define free_arg_pages(bprm) do { } while (0)
459
460 #else
461
462 static inline void free_arg_pages(struct linux_binprm *bprm)
463 {
464         int i;
465
466         for (i = 0; i < MAX_ARG_PAGES; i++) {
467                 if (bprm->page[i])
468                         __free_page(bprm->page[i]);
469                 bprm->page[i] = NULL;
470         }
471 }
472
473 #endif /* CONFIG_MMU */
474
475 struct file *open_exec(const char *name)
476 {
477         struct nameidata nd;
478         int err;
479         struct file *file;
480
481         err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
482         file = ERR_PTR(err);
483
484         if (!err) {
485                 struct inode *inode = nd.dentry->d_inode;
486                 file = ERR_PTR(-EACCES);
487                 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
488                     S_ISREG(inode->i_mode)) {
489                         int err = vfs_permission(&nd, MAY_EXEC);
490                         file = ERR_PTR(err);
491                         if (!err) {
492                                 file = nameidata_to_filp(&nd, O_RDONLY);
493                                 if (!IS_ERR(file)) {
494                                         err = deny_write_access(file);
495                                         if (err) {
496                                                 fput(file);
497                                                 file = ERR_PTR(err);
498                                         }
499                                 }
500 out:
501                                 return file;
502                         }
503                 }
504                 release_open_intent(&nd);
505                 path_release(&nd);
506         }
507         goto out;
508 }
509
510 EXPORT_SYMBOL(open_exec);
511
512 int kernel_read(struct file *file, unsigned long offset,
513         char *addr, unsigned long count)
514 {
515         mm_segment_t old_fs;
516         loff_t pos = offset;
517         int result;
518
519         old_fs = get_fs();
520         set_fs(get_ds());
521         /* The cast to a user pointer is valid due to the set_fs() */
522         result = vfs_read(file, (void __user *)addr, count, &pos);
523         set_fs(old_fs);
524         return result;
525 }
526
527 EXPORT_SYMBOL(kernel_read);
528
529 static int exec_mmap(struct mm_struct *mm)
530 {
531         struct task_struct *tsk;
532         struct mm_struct * old_mm, *active_mm;
533
534         /* Notify parent that we're no longer interested in the old VM */
535         tsk = current;
536         old_mm = current->mm;
537         mm_release(tsk, old_mm);
538
539         if (old_mm) {
540                 /*
541                  * Make sure that if there is a core dump in progress
542                  * for the old mm, we get out and die instead of going
543                  * through with the exec.  We must hold mmap_sem around
544                  * checking core_waiters and changing tsk->mm.  The
545                  * core-inducing thread will increment core_waiters for
546                  * each thread whose ->mm == old_mm.
547                  */
548                 down_read(&old_mm->mmap_sem);
549                 if (unlikely(old_mm->core_waiters)) {
550                         up_read(&old_mm->mmap_sem);
551                         return -EINTR;
552                 }
553         }
554         task_lock(tsk);
555         active_mm = tsk->active_mm;
556         tsk->mm = mm;
557         tsk->active_mm = mm;
558         activate_mm(active_mm, mm);
559         task_unlock(tsk);
560         arch_pick_mmap_layout(mm);
561         if (old_mm) {
562                 up_read(&old_mm->mmap_sem);
563                 BUG_ON(active_mm != old_mm);
564                 mmput(old_mm);
565                 return 0;
566         }
567         mmdrop(active_mm);
568         return 0;
569 }
570
571 /*
572  * This function makes sure the current process has its own signal table,
573  * so that flush_signal_handlers can later reset the handlers without
574  * disturbing other processes.  (Other processes might share the signal
575  * table via the CLONE_SIGHAND option to clone().)
576  */
577 static int de_thread(struct task_struct *tsk)
578 {
579         struct signal_struct *sig = tsk->signal;
580         struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
581         spinlock_t *lock = &oldsighand->siglock;
582         struct task_struct *leader = NULL;
583         int count;
584
585         /*
586          * Tell all the sighand listeners that this sighand has
587          * been detached. The signalfd_detach() function grabs the
588          * sighand lock, if signal listeners are present on the sighand.
589          */
590         signalfd_detach(tsk);
591
592         /*
593          * If we don't share sighandlers, then we aren't sharing anything
594          * and we can just re-use it all.
595          */
596         if (atomic_read(&oldsighand->count) <= 1) {
597                 BUG_ON(atomic_read(&sig->count) != 1);
598                 exit_itimers(sig);
599                 return 0;
600         }
601
602         newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
603         if (!newsighand)
604                 return -ENOMEM;
605
606         if (thread_group_empty(tsk))
607                 goto no_thread_group;
608
609         /*
610          * Kill all other threads in the thread group.
611          * We must hold tasklist_lock to call zap_other_threads.
612          */
613         read_lock(&tasklist_lock);
614         spin_lock_irq(lock);
615         if (sig->flags & SIGNAL_GROUP_EXIT) {
616                 /*
617                  * Another group action in progress, just
618                  * return so that the signal is processed.
619                  */
620                 spin_unlock_irq(lock);
621                 read_unlock(&tasklist_lock);
622                 kmem_cache_free(sighand_cachep, newsighand);
623                 return -EAGAIN;
624         }
625
626         /*
627          * child_reaper ignores SIGKILL, change it now.
628          * Reparenting needs write_lock on tasklist_lock,
629          * so it is safe to do it under read_lock.
630          */
631         if (unlikely(tsk->group_leader == child_reaper(tsk)))
632                 tsk->nsproxy->pid_ns->child_reaper = tsk;
633
634         zap_other_threads(tsk);
635         read_unlock(&tasklist_lock);
636
637         /*
638          * Account for the thread group leader hanging around:
639          */
640         count = 1;
641         if (!thread_group_leader(tsk)) {
642                 count = 2;
643                 /*
644                  * The SIGALRM timer survives the exec, but needs to point
645                  * at us as the new group leader now.  We have a race with
646                  * a timer firing now getting the old leader, so we need to
647                  * synchronize with any firing (by calling del_timer_sync)
648                  * before we can safely let the old group leader die.
649                  */
650                 sig->tsk = tsk;
651                 spin_unlock_irq(lock);
652                 if (hrtimer_cancel(&sig->real_timer))
653                         hrtimer_restart(&sig->real_timer);
654                 spin_lock_irq(lock);
655         }
656         while (atomic_read(&sig->count) > count) {
657                 sig->group_exit_task = tsk;
658                 sig->notify_count = count;
659                 __set_current_state(TASK_UNINTERRUPTIBLE);
660                 spin_unlock_irq(lock);
661                 schedule();
662                 spin_lock_irq(lock);
663         }
664         sig->group_exit_task = NULL;
665         sig->notify_count = 0;
666         spin_unlock_irq(lock);
667
668         /*
669          * At this point all other threads have exited, all we have to
670          * do is to wait for the thread group leader to become inactive,
671          * and to assume its PID:
672          */
673         if (!thread_group_leader(tsk)) {
674                 /*
675                  * Wait for the thread group leader to be a zombie.
676                  * It should already be zombie at this point, most
677                  * of the time.
678                  */
679                 leader = tsk->group_leader;
680                 while (leader->exit_state != EXIT_ZOMBIE)
681                         yield();
682
683                 /*
684                  * The only record we have of the real-time age of a
685                  * process, regardless of execs it's done, is start_time.
686                  * All the past CPU time is accumulated in signal_struct
687                  * from sister threads now dead.  But in this non-leader
688                  * exec, nothing survives from the original leader thread,
689                  * whose birth marks the true age of this process now.
690                  * When we take on its identity by switching to its PID, we
691                  * also take its birthdate (always earlier than our own).
692                  */
693                 tsk->start_time = leader->start_time;
694
695                 write_lock_irq(&tasklist_lock);
696
697                 BUG_ON(leader->tgid != tsk->tgid);
698                 BUG_ON(tsk->pid == tsk->tgid);
699                 /*
700                  * An exec() starts a new thread group with the
701                  * TGID of the previous thread group. Rehash the
702                  * two threads with a switched PID, and release
703                  * the former thread group leader:
704                  */
705
706                 /* Become a process group leader with the old leader's pid.
707                  * The old leader becomes a thread of the this thread group.
708                  * Note: The old leader also uses this pid until release_task
709                  *       is called.  Odd but simple and correct.
710                  */
711                 detach_pid(tsk, PIDTYPE_PID);
712                 tsk->pid = leader->pid;
713                 attach_pid(tsk, PIDTYPE_PID,  find_pid(tsk->pid));
714                 transfer_pid(leader, tsk, PIDTYPE_PGID);
715                 transfer_pid(leader, tsk, PIDTYPE_SID);
716                 list_replace_rcu(&leader->tasks, &tsk->tasks);
717
718                 tsk->group_leader = tsk;
719                 leader->group_leader = tsk;
720
721                 tsk->exit_signal = SIGCHLD;
722
723                 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
724                 leader->exit_state = EXIT_DEAD;
725
726                 write_unlock_irq(&tasklist_lock);
727         }
728
729         /*
730          * There may be one thread left which is just exiting,
731          * but it's safe to stop telling the group to kill themselves.
732          */
733         sig->flags = 0;
734
735 no_thread_group:
736         exit_itimers(sig);
737         if (leader)
738                 release_task(leader);
739
740         BUG_ON(atomic_read(&sig->count) != 1);
741
742         if (atomic_read(&oldsighand->count) == 1) {
743                 /*
744                  * Now that we nuked the rest of the thread group,
745                  * it turns out we are not sharing sighand any more either.
746                  * So we can just keep it.
747                  */
748                 kmem_cache_free(sighand_cachep, newsighand);
749         } else {
750                 /*
751                  * Move our state over to newsighand and switch it in.
752                  */
753                 atomic_set(&newsighand->count, 1);
754                 memcpy(newsighand->action, oldsighand->action,
755                        sizeof(newsighand->action));
756
757                 write_lock_irq(&tasklist_lock);
758                 spin_lock(&oldsighand->siglock);
759                 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
760
761                 rcu_assign_pointer(tsk->sighand, newsighand);
762                 recalc_sigpending();
763
764                 spin_unlock(&newsighand->siglock);
765                 spin_unlock(&oldsighand->siglock);
766                 write_unlock_irq(&tasklist_lock);
767
768                 __cleanup_sighand(oldsighand);
769         }
770
771         BUG_ON(!thread_group_leader(tsk));
772         return 0;
773 }
774         
775 /*
776  * These functions flushes out all traces of the currently running executable
777  * so that a new one can be started
778  */
779
780 static void flush_old_files(struct files_struct * files)
781 {
782         long j = -1;
783         struct fdtable *fdt;
784
785         spin_lock(&files->file_lock);
786         for (;;) {
787                 unsigned long set, i;
788
789                 j++;
790                 i = j * __NFDBITS;
791                 fdt = files_fdtable(files);
792                 if (i >= fdt->max_fds)
793                         break;
794                 set = fdt->close_on_exec->fds_bits[j];
795                 if (!set)
796                         continue;
797                 fdt->close_on_exec->fds_bits[j] = 0;
798                 spin_unlock(&files->file_lock);
799                 for ( ; set ; i++,set >>= 1) {
800                         if (set & 1) {
801                                 sys_close(i);
802                         }
803                 }
804                 spin_lock(&files->file_lock);
805
806         }
807         spin_unlock(&files->file_lock);
808 }
809
810 void get_task_comm(char *buf, struct task_struct *tsk)
811 {
812         /* buf must be at least sizeof(tsk->comm) in size */
813         task_lock(tsk);
814         strncpy(buf, tsk->comm, sizeof(tsk->comm));
815         task_unlock(tsk);
816 }
817
818 void set_task_comm(struct task_struct *tsk, char *buf)
819 {
820         task_lock(tsk);
821         strlcpy(tsk->comm, buf, sizeof(tsk->comm));
822         task_unlock(tsk);
823 }
824
825 int flush_old_exec(struct linux_binprm * bprm)
826 {
827         char * name;
828         int i, ch, retval;
829         struct files_struct *files;
830         char tcomm[sizeof(current->comm)];
831
832         /*
833          * Make sure we have a private signal table and that
834          * we are unassociated from the previous thread group.
835          */
836         retval = de_thread(current);
837         if (retval)
838                 goto out;
839
840         /*
841          * Make sure we have private file handles. Ask the
842          * fork helper to do the work for us and the exit
843          * helper to do the cleanup of the old one.
844          */
845         files = current->files;         /* refcounted so safe to hold */
846         retval = unshare_files();
847         if (retval)
848                 goto out;
849         /*
850          * Release all of the old mmap stuff
851          */
852         retval = exec_mmap(bprm->mm);
853         if (retval)
854                 goto mmap_failed;
855
856         bprm->mm = NULL;                /* We're using it now */
857
858         /* This is the point of no return */
859         put_files_struct(files);
860
861         current->sas_ss_sp = current->sas_ss_size = 0;
862
863         if (current->euid == current->uid && current->egid == current->gid)
864                 current->mm->dumpable = 1;
865         else
866                 current->mm->dumpable = suid_dumpable;
867
868         name = bprm->filename;
869
870         /* Copies the binary name from after last slash */
871         for (i=0; (ch = *(name++)) != '\0';) {
872                 if (ch == '/')
873                         i = 0; /* overwrite what we wrote */
874                 else
875                         if (i < (sizeof(tcomm) - 1))
876                                 tcomm[i++] = ch;
877         }
878         tcomm[i] = '\0';
879         set_task_comm(current, tcomm);
880
881         current->flags &= ~PF_RANDOMIZE;
882         flush_thread();
883
884         /* Set the new mm task size. We have to do that late because it may
885          * depend on TIF_32BIT which is only updated in flush_thread() on
886          * some architectures like powerpc
887          */
888         current->mm->task_size = TASK_SIZE;
889
890         if (bprm->e_uid != current->euid || bprm->e_gid != current->egid || 
891             file_permission(bprm->file, MAY_READ) ||
892             (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
893                 suid_keys(current);
894                 current->mm->dumpable = suid_dumpable;
895         }
896
897         /* An exec changes our domain. We are no longer part of the thread
898            group */
899
900         current->self_exec_id++;
901                         
902         flush_signal_handlers(current, 0);
903         flush_old_files(current->files);
904
905         return 0;
906
907 mmap_failed:
908         reset_files_struct(current, files);
909 out:
910         return retval;
911 }
912
913 EXPORT_SYMBOL(flush_old_exec);
914
915 /* 
916  * Fill the binprm structure from the inode. 
917  * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
918  */
919 int prepare_binprm(struct linux_binprm *bprm)
920 {
921         int mode;
922         struct inode * inode = bprm->file->f_path.dentry->d_inode;
923         int retval;
924
925         mode = inode->i_mode;
926         if (bprm->file->f_op == NULL)
927                 return -EACCES;
928
929         bprm->e_uid = current->euid;
930         bprm->e_gid = current->egid;
931
932         if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
933                 /* Set-uid? */
934                 if (mode & S_ISUID) {
935                         current->personality &= ~PER_CLEAR_ON_SETID;
936                         bprm->e_uid = inode->i_uid;
937                 }
938
939                 /* Set-gid? */
940                 /*
941                  * If setgid is set but no group execute bit then this
942                  * is a candidate for mandatory locking, not a setgid
943                  * executable.
944                  */
945                 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
946                         current->personality &= ~PER_CLEAR_ON_SETID;
947                         bprm->e_gid = inode->i_gid;
948                 }
949         }
950
951         /* fill in binprm security blob */
952         retval = security_bprm_set(bprm);
953         if (retval)
954                 return retval;
955
956         memset(bprm->buf,0,BINPRM_BUF_SIZE);
957         return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
958 }
959
960 EXPORT_SYMBOL(prepare_binprm);
961
962 static int unsafe_exec(struct task_struct *p)
963 {
964         int unsafe = 0;
965         if (p->ptrace & PT_PTRACED) {
966                 if (p->ptrace & PT_PTRACE_CAP)
967                         unsafe |= LSM_UNSAFE_PTRACE_CAP;
968                 else
969                         unsafe |= LSM_UNSAFE_PTRACE;
970         }
971         if (atomic_read(&p->fs->count) > 1 ||
972             atomic_read(&p->files->count) > 1 ||
973             atomic_read(&p->sighand->count) > 1)
974                 unsafe |= LSM_UNSAFE_SHARE;
975
976         return unsafe;
977 }
978
979 void compute_creds(struct linux_binprm *bprm)
980 {
981         int unsafe;
982
983         if (bprm->e_uid != current->uid)
984                 suid_keys(current);
985         exec_keys(current);
986
987         task_lock(current);
988         unsafe = unsafe_exec(current);
989         security_bprm_apply_creds(bprm, unsafe);
990         task_unlock(current);
991         security_bprm_post_apply_creds(bprm);
992 }
993 EXPORT_SYMBOL(compute_creds);
994
995 /*
996  * Arguments are '\0' separated strings found at the location bprm->p
997  * points to; chop off the first by relocating brpm->p to right after
998  * the first '\0' encountered.
999  */
1000 void remove_arg_zero(struct linux_binprm *bprm)
1001 {
1002         if (bprm->argc) {
1003                 char ch;
1004
1005                 do {
1006                         unsigned long offset;
1007                         unsigned long index;
1008                         char *kaddr;
1009                         struct page *page;
1010
1011                         offset = bprm->p & ~PAGE_MASK;
1012                         index = bprm->p >> PAGE_SHIFT;
1013
1014                         page = bprm->page[index];
1015                         kaddr = kmap_atomic(page, KM_USER0);
1016
1017                         /* run through page until we reach end or find NUL */
1018                         do {
1019                                 ch = *(kaddr + offset);
1020
1021                                 /* discard that character... */
1022                                 bprm->p++;
1023                                 offset++;
1024                         } while (offset < PAGE_SIZE && ch != '\0');
1025
1026                         kunmap_atomic(kaddr, KM_USER0);
1027
1028                         /* free the old page */
1029                         if (offset == PAGE_SIZE) {
1030                                 __free_page(page);
1031                                 bprm->page[index] = NULL;
1032                         }
1033                 } while (ch != '\0');
1034
1035                 bprm->argc--;
1036         }
1037 }
1038 EXPORT_SYMBOL(remove_arg_zero);
1039
1040 /*
1041  * cycle the list of binary formats handler, until one recognizes the image
1042  */
1043 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1044 {
1045         int try,retval;
1046         struct linux_binfmt *fmt;
1047 #ifdef __alpha__
1048         /* handle /sbin/loader.. */
1049         {
1050             struct exec * eh = (struct exec *) bprm->buf;
1051
1052             if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1053                 (eh->fh.f_flags & 0x3000) == 0x3000)
1054             {
1055                 struct file * file;
1056                 unsigned long loader;
1057
1058                 allow_write_access(bprm->file);
1059                 fput(bprm->file);
1060                 bprm->file = NULL;
1061
1062                 loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1063
1064                 file = open_exec("/sbin/loader");
1065                 retval = PTR_ERR(file);
1066                 if (IS_ERR(file))
1067                         return retval;
1068
1069                 /* Remember if the application is TASO.  */
1070                 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1071
1072                 bprm->file = file;
1073                 bprm->loader = loader;
1074                 retval = prepare_binprm(bprm);
1075                 if (retval<0)
1076                         return retval;
1077                 /* should call search_binary_handler recursively here,
1078                    but it does not matter */
1079             }
1080         }
1081 #endif
1082         retval = security_bprm_check(bprm);
1083         if (retval)
1084                 return retval;
1085
1086         /* kernel module loader fixup */
1087         /* so we don't try to load run modprobe in kernel space. */
1088         set_fs(USER_DS);
1089
1090         retval = audit_bprm(bprm);
1091         if (retval)
1092                 return retval;
1093
1094         retval = -ENOENT;
1095         for (try=0; try<2; try++) {
1096                 read_lock(&binfmt_lock);
1097                 for (fmt = formats ; fmt ; fmt = fmt->next) {
1098                         int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1099                         if (!fn)
1100                                 continue;
1101                         if (!try_module_get(fmt->module))
1102                                 continue;
1103                         read_unlock(&binfmt_lock);
1104                         retval = fn(bprm, regs);
1105                         if (retval >= 0) {
1106                                 put_binfmt(fmt);
1107                                 allow_write_access(bprm->file);
1108                                 if (bprm->file)
1109                                         fput(bprm->file);
1110                                 bprm->file = NULL;
1111                                 current->did_exec = 1;
1112                                 proc_exec_connector(current);
1113                                 return retval;
1114                         }
1115                         read_lock(&binfmt_lock);
1116                         put_binfmt(fmt);
1117                         if (retval != -ENOEXEC || bprm->mm == NULL)
1118                                 break;
1119                         if (!bprm->file) {
1120                                 read_unlock(&binfmt_lock);
1121                                 return retval;
1122                         }
1123                 }
1124                 read_unlock(&binfmt_lock);
1125                 if (retval != -ENOEXEC || bprm->mm == NULL) {
1126                         break;
1127 #ifdef CONFIG_KMOD
1128                 }else{
1129 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1130                         if (printable(bprm->buf[0]) &&
1131                             printable(bprm->buf[1]) &&
1132                             printable(bprm->buf[2]) &&
1133                             printable(bprm->buf[3]))
1134                                 break; /* -ENOEXEC */
1135                         request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1136 #endif
1137                 }
1138         }
1139         return retval;
1140 }
1141
1142 EXPORT_SYMBOL(search_binary_handler);
1143
1144 /*
1145  * sys_execve() executes a new program.
1146  */
1147 int do_execve(char * filename,
1148         char __user *__user *argv,
1149         char __user *__user *envp,
1150         struct pt_regs * regs)
1151 {
1152         struct linux_binprm *bprm;
1153         struct file *file;
1154         int retval;
1155         int i;
1156
1157         retval = -ENOMEM;
1158         bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1159         if (!bprm)
1160                 goto out_ret;
1161
1162         file = open_exec(filename);
1163         retval = PTR_ERR(file);
1164         if (IS_ERR(file))
1165                 goto out_kfree;
1166
1167         sched_exec();
1168
1169         bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
1170
1171         bprm->file = file;
1172         bprm->filename = filename;
1173         bprm->interp = filename;
1174         bprm->mm = mm_alloc();
1175         retval = -ENOMEM;
1176         if (!bprm->mm)
1177                 goto out_file;
1178
1179         retval = init_new_context(current, bprm->mm);
1180         if (retval < 0)
1181                 goto out_mm;
1182
1183         bprm->argc = count(argv, bprm->p / sizeof(void *));
1184         if ((retval = bprm->argc) < 0)
1185                 goto out_mm;
1186
1187         bprm->envc = count(envp, bprm->p / sizeof(void *));
1188         if ((retval = bprm->envc) < 0)
1189                 goto out_mm;
1190
1191         retval = security_bprm_alloc(bprm);
1192         if (retval)
1193                 goto out;
1194
1195         retval = prepare_binprm(bprm);
1196         if (retval < 0)
1197                 goto out;
1198
1199         retval = copy_strings_kernel(1, &bprm->filename, bprm);
1200         if (retval < 0)
1201                 goto out;
1202
1203         bprm->exec = bprm->p;
1204         retval = copy_strings(bprm->envc, envp, bprm);
1205         if (retval < 0)
1206                 goto out;
1207
1208         retval = copy_strings(bprm->argc, argv, bprm);
1209         if (retval < 0)
1210                 goto out;
1211
1212         retval = search_binary_handler(bprm,regs);
1213         if (retval >= 0) {
1214                 free_arg_pages(bprm);
1215
1216                 /* execve success */
1217                 security_bprm_free(bprm);
1218                 acct_update_integrals(current);
1219                 kfree(bprm);
1220                 return retval;
1221         }
1222
1223 out:
1224         /* Something went wrong, return the inode and free the argument pages*/
1225         for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
1226                 struct page * page = bprm->page[i];
1227                 if (page)
1228                         __free_page(page);
1229         }
1230
1231         if (bprm->security)
1232                 security_bprm_free(bprm);
1233
1234 out_mm:
1235         if (bprm->mm)
1236                 mmdrop(bprm->mm);
1237
1238 out_file:
1239         if (bprm->file) {
1240                 allow_write_access(bprm->file);
1241                 fput(bprm->file);
1242         }
1243
1244 out_kfree:
1245         kfree(bprm);
1246
1247 out_ret:
1248         return retval;
1249 }
1250
1251 int set_binfmt(struct linux_binfmt *new)
1252 {
1253         struct linux_binfmt *old = current->binfmt;
1254
1255         if (new) {
1256                 if (!try_module_get(new->module))
1257                         return -1;
1258         }
1259         current->binfmt = new;
1260         if (old)
1261                 module_put(old->module);
1262         return 0;
1263 }
1264
1265 EXPORT_SYMBOL(set_binfmt);
1266
1267 /* format_corename will inspect the pattern parameter, and output a
1268  * name into corename, which must have space for at least
1269  * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1270  */
1271 static int format_corename(char *corename, const char *pattern, long signr)
1272 {
1273         const char *pat_ptr = pattern;
1274         char *out_ptr = corename;
1275         char *const out_end = corename + CORENAME_MAX_SIZE;
1276         int rc;
1277         int pid_in_pattern = 0;
1278         int ispipe = 0;
1279
1280         if (*pattern == '|')
1281                 ispipe = 1;
1282
1283         /* Repeat as long as we have more pattern to process and more output
1284            space */
1285         while (*pat_ptr) {
1286                 if (*pat_ptr != '%') {
1287                         if (out_ptr == out_end)
1288                                 goto out;
1289                         *out_ptr++ = *pat_ptr++;
1290                 } else {
1291                         switch (*++pat_ptr) {
1292                         case 0:
1293                                 goto out;
1294                         /* Double percent, output one percent */
1295                         case '%':
1296                                 if (out_ptr == out_end)
1297                                         goto out;
1298                                 *out_ptr++ = '%';
1299                                 break;
1300                         /* pid */
1301                         case 'p':
1302                                 pid_in_pattern = 1;
1303                                 rc = snprintf(out_ptr, out_end - out_ptr,
1304                                               "%d", current->tgid);
1305                                 if (rc > out_end - out_ptr)
1306                                         goto out;
1307                                 out_ptr += rc;
1308                                 break;
1309                         /* uid */
1310                         case 'u':
1311                                 rc = snprintf(out_ptr, out_end - out_ptr,
1312                                               "%d", current->uid);
1313                                 if (rc > out_end - out_ptr)
1314                                         goto out;
1315                                 out_ptr += rc;
1316                                 break;
1317                         /* gid */
1318                         case 'g':
1319                                 rc = snprintf(out_ptr, out_end - out_ptr,
1320                                               "%d", current->gid);
1321                                 if (rc > out_end - out_ptr)
1322                                         goto out;
1323                                 out_ptr += rc;
1324                                 break;
1325                         /* signal that caused the coredump */
1326                         case 's':
1327                                 rc = snprintf(out_ptr, out_end - out_ptr,
1328                                               "%ld", signr);
1329                                 if (rc > out_end - out_ptr)
1330                                         goto out;
1331                                 out_ptr += rc;
1332                                 break;
1333                         /* UNIX time of coredump */
1334                         case 't': {
1335                                 struct timeval tv;
1336                                 do_gettimeofday(&tv);
1337                                 rc = snprintf(out_ptr, out_end - out_ptr,
1338                                               "%lu", tv.tv_sec);
1339                                 if (rc > out_end - out_ptr)
1340                                         goto out;
1341                                 out_ptr += rc;
1342                                 break;
1343                         }
1344                         /* hostname */
1345                         case 'h':
1346                                 down_read(&uts_sem);
1347                                 rc = snprintf(out_ptr, out_end - out_ptr,
1348                                               "%s", utsname()->nodename);
1349                                 up_read(&uts_sem);
1350                                 if (rc > out_end - out_ptr)
1351                                         goto out;
1352                                 out_ptr += rc;
1353                                 break;
1354                         /* executable */
1355                         case 'e':
1356                                 rc = snprintf(out_ptr, out_end - out_ptr,
1357                                               "%s", current->comm);
1358                                 if (rc > out_end - out_ptr)
1359                                         goto out;
1360                                 out_ptr += rc;
1361                                 break;
1362                         default:
1363                                 break;
1364                         }
1365                         ++pat_ptr;
1366                 }
1367         }
1368         /* Backward compatibility with core_uses_pid:
1369          *
1370          * If core_pattern does not include a %p (as is the default)
1371          * and core_uses_pid is set, then .%pid will be appended to
1372          * the filename. Do not do this for piped commands. */
1373         if (!ispipe && !pid_in_pattern
1374             && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1375                 rc = snprintf(out_ptr, out_end - out_ptr,
1376                               ".%d", current->tgid);
1377                 if (rc > out_end - out_ptr)
1378                         goto out;
1379                 out_ptr += rc;
1380         }
1381 out:
1382         *out_ptr = 0;
1383         return ispipe;
1384 }
1385
1386 static void zap_process(struct task_struct *start)
1387 {
1388         struct task_struct *t;
1389
1390         start->signal->flags = SIGNAL_GROUP_EXIT;
1391         start->signal->group_stop_count = 0;
1392
1393         t = start;
1394         do {
1395                 if (t != current && t->mm) {
1396                         t->mm->core_waiters++;
1397                         sigaddset(&t->pending.signal, SIGKILL);
1398                         signal_wake_up(t, 1);
1399                 }
1400         } while ((t = next_thread(t)) != start);
1401 }
1402
1403 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1404                                 int exit_code)
1405 {
1406         struct task_struct *g, *p;
1407         unsigned long flags;
1408         int err = -EAGAIN;
1409
1410         spin_lock_irq(&tsk->sighand->siglock);
1411         if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1412                 tsk->signal->group_exit_code = exit_code;
1413                 zap_process(tsk);
1414                 err = 0;
1415         }
1416         spin_unlock_irq(&tsk->sighand->siglock);
1417         if (err)
1418                 return err;
1419
1420         if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1421                 goto done;
1422
1423         rcu_read_lock();
1424         for_each_process(g) {
1425                 if (g == tsk->group_leader)
1426                         continue;
1427
1428                 p = g;
1429                 do {
1430                         if (p->mm) {
1431                                 if (p->mm == mm) {
1432                                         /*
1433                                          * p->sighand can't disappear, but
1434                                          * may be changed by de_thread()
1435                                          */
1436                                         lock_task_sighand(p, &flags);
1437                                         zap_process(p);
1438                                         unlock_task_sighand(p, &flags);
1439                                 }
1440                                 break;
1441                         }
1442                 } while ((p = next_thread(p)) != g);
1443         }
1444         rcu_read_unlock();
1445 done:
1446         return mm->core_waiters;
1447 }
1448
1449 static int coredump_wait(int exit_code)
1450 {
1451         struct task_struct *tsk = current;
1452         struct mm_struct *mm = tsk->mm;
1453         struct completion startup_done;
1454         struct completion *vfork_done;
1455         int core_waiters;
1456
1457         init_completion(&mm->core_done);
1458         init_completion(&startup_done);
1459         mm->core_startup_done = &startup_done;
1460
1461         core_waiters = zap_threads(tsk, mm, exit_code);
1462         up_write(&mm->mmap_sem);
1463
1464         if (unlikely(core_waiters < 0))
1465                 goto fail;
1466
1467         /*
1468          * Make sure nobody is waiting for us to release the VM,
1469          * otherwise we can deadlock when we wait on each other
1470          */
1471         vfork_done = tsk->vfork_done;
1472         if (vfork_done) {
1473                 tsk->vfork_done = NULL;
1474                 complete(vfork_done);
1475         }
1476
1477         if (core_waiters)
1478                 wait_for_completion(&startup_done);
1479 fail:
1480         BUG_ON(mm->core_waiters);
1481         return core_waiters;
1482 }
1483
1484 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1485 {
1486         char corename[CORENAME_MAX_SIZE + 1];
1487         struct mm_struct *mm = current->mm;
1488         struct linux_binfmt * binfmt;
1489         struct inode * inode;
1490         struct file * file;
1491         int retval = 0;
1492         int fsuid = current->fsuid;
1493         int flag = 0;
1494         int ispipe = 0;
1495
1496         audit_core_dumps(signr);
1497
1498         binfmt = current->binfmt;
1499         if (!binfmt || !binfmt->core_dump)
1500                 goto fail;
1501         down_write(&mm->mmap_sem);
1502         if (!mm->dumpable) {
1503                 up_write(&mm->mmap_sem);
1504                 goto fail;
1505         }
1506
1507         /*
1508          *      We cannot trust fsuid as being the "true" uid of the
1509          *      process nor do we know its entire history. We only know it
1510          *      was tainted so we dump it as root in mode 2.
1511          */
1512         if (mm->dumpable == 2) {        /* Setuid core dump mode */
1513                 flag = O_EXCL;          /* Stop rewrite attacks */
1514                 current->fsuid = 0;     /* Dump root private */
1515         }
1516         mm->dumpable = 0;
1517
1518         retval = coredump_wait(exit_code);
1519         if (retval < 0)
1520                 goto fail;
1521
1522         /*
1523          * Clear any false indication of pending signals that might
1524          * be seen by the filesystem code called to write the core file.
1525          */
1526         clear_thread_flag(TIF_SIGPENDING);
1527
1528         if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1529                 goto fail_unlock;
1530
1531         /*
1532          * lock_kernel() because format_corename() is controlled by sysctl, which
1533          * uses lock_kernel()
1534          */
1535         lock_kernel();
1536         ispipe = format_corename(corename, core_pattern, signr);
1537         unlock_kernel();
1538         if (ispipe) {
1539                 /* SIGPIPE can happen, but it's just never processed */
1540                 if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1541                         printk(KERN_INFO "Core dump to %s pipe failed\n",
1542                                corename);
1543                         goto fail_unlock;
1544                 }
1545         } else
1546                 file = filp_open(corename,
1547                                  O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1548                                  0600);
1549         if (IS_ERR(file))
1550                 goto fail_unlock;
1551         inode = file->f_path.dentry->d_inode;
1552         if (inode->i_nlink > 1)
1553                 goto close_fail;        /* multiple links - don't dump */
1554         if (!ispipe && d_unhashed(file->f_path.dentry))
1555                 goto close_fail;
1556
1557         /* AK: actually i see no reason to not allow this for named pipes etc.,
1558            but keep the previous behaviour for now. */
1559         if (!ispipe && !S_ISREG(inode->i_mode))
1560                 goto close_fail;
1561         if (!file->f_op)
1562                 goto close_fail;
1563         if (!file->f_op->write)
1564                 goto close_fail;
1565         if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1566                 goto close_fail;
1567
1568         retval = binfmt->core_dump(signr, regs, file);
1569
1570         if (retval)
1571                 current->signal->group_exit_code |= 0x80;
1572 close_fail:
1573         filp_close(file, NULL);
1574 fail_unlock:
1575         current->fsuid = fsuid;
1576         complete_all(&mm->core_done);
1577 fail:
1578         return retval;
1579 }