projects/linux·blob v2.6.23 · refs

1807 lines · 40.7 KiB

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
54#include <asm/uaccess.h>
55#include <asm/mmu_context.h>
56#include <asm/tlb.h>
57
58#ifdef CONFIG_KMOD
59#include <linux/kmod.h>
60#endif
61
62int core_uses_pid;
63char core_pattern[CORENAME_MAX_SIZE] = "core";
64int suid_dumpable = 0;
65
66EXPORT_SYMBOL(suid_dumpable);
67/* The maximal length of core_pattern is also specified in sysctl.c */
68
69static struct linux_binfmt *formats;
70static DEFINE_RWLOCK(binfmt_lock);
71
72int 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
94EXPORT_SYMBOL(register_binfmt);
95
96int 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
114EXPORT_SYMBOL(unregister_binfmt);
115
116static 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 */
127asmlinkage long sys_uselib(const char __user * library)
128{
129 struct file * file;
130 struct nameidata nd;
131 int error;
132
133 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
134 if (error)
135 goto out;
136
137 error = -EACCES;
138 if (nd.mnt->mnt_flags & MNT_NOEXEC)
139 goto exit;
140 error = -EINVAL;
141 if (!S_ISREG(nd.dentry->d_inode->i_mode))
142 goto exit;
143
144 error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
145 if (error)
146 goto exit;
147
148 file = nameidata_to_filp(&nd, O_RDONLY);
149 error = PTR_ERR(file);
150 if (IS_ERR(file))
151 goto out;
152
153 error = -ENOEXEC;
154 if(file->f_op) {
155 struct linux_binfmt * fmt;
156
157 read_lock(&binfmt_lock);
158 for (fmt = formats ; fmt ; fmt = fmt->next) {
159 if (!fmt->load_shlib)
160 continue;
161 if (!try_module_get(fmt->module))
162 continue;
163 read_unlock(&binfmt_lock);
164 error = fmt->load_shlib(file);
165 read_lock(&binfmt_lock);
166 put_binfmt(fmt);
167 if (error != -ENOEXEC)
168 break;
169 }
170 read_unlock(&binfmt_lock);
171 }
172 fput(file);
173out:
174 return error;
175exit:
176 release_open_intent(&nd);
177 path_release(&nd);
178 goto out;
179}
180
181#ifdef CONFIG_MMU
182
183static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
184 int write)
185{
186 struct page *page;
187 int ret;
188
189#ifdef CONFIG_STACK_GROWSUP
190 if (write) {
191 ret = expand_stack_downwards(bprm->vma, pos);
192 if (ret < 0)
193 return NULL;
194 }
195#endif
196 ret = get_user_pages(current, bprm->mm, pos,
197 1, write, 1, &page, NULL);
198 if (ret <= 0)
199 return NULL;
200
201 if (write) {
202 struct rlimit *rlim = current->signal->rlim;
203 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
204
205 /*
206 * Limit to 1/4-th the stack size for the argv+env strings.
207 * This ensures that:
208 * - the remaining binfmt code will not run out of stack space,
209 * - the program will have a reasonable amount of stack left
210 * to work from.
211 */
212 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
213 put_page(page);
214 return NULL;
215 }
216 }
217
218 return page;
219}
220
221static void put_arg_page(struct page *page)
222{
223 put_page(page);
224}
225
226static void free_arg_page(struct linux_binprm *bprm, int i)
227{
228}
229
230static void free_arg_pages(struct linux_binprm *bprm)
231{
232}
233
234static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
235 struct page *page)
236{
237 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
238}
239
240static int __bprm_mm_init(struct linux_binprm *bprm)
241{
242 int err = -ENOMEM;
243 struct vm_area_struct *vma = NULL;
244 struct mm_struct *mm = bprm->mm;
245
246 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
247 if (!vma)
248 goto err;
249
250 down_write(&mm->mmap_sem);
251 vma->vm_mm = mm;
252
253 /*
254 * Place the stack at the largest stack address the architecture
255 * supports. Later, we'll move this to an appropriate place. We don't
256 * use STACK_TOP because that can depend on attributes which aren't
257 * configured yet.
258 */
259 vma->vm_end = STACK_TOP_MAX;
260 vma->vm_start = vma->vm_end - PAGE_SIZE;
261
262 vma->vm_flags = VM_STACK_FLAGS;
263 vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
264 err = insert_vm_struct(mm, vma);
265 if (err) {
266 up_write(&mm->mmap_sem);
267 goto err;
268 }
269
270 mm->stack_vm = mm->total_vm = 1;
271 up_write(&mm->mmap_sem);
272
273 bprm->p = vma->vm_end - sizeof(void *);
274
275 return 0;
276
277err:
278 if (vma) {
279 bprm->vma = NULL;
280 kmem_cache_free(vm_area_cachep, vma);
281 }
282
283 return err;
284}
285
286static bool valid_arg_len(struct linux_binprm *bprm, long len)
287{
288 return len <= MAX_ARG_STRLEN;
289}
290
291#else
292
293static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
294 int write)
295{
296 struct page *page;
297
298 page = bprm->page[pos / PAGE_SIZE];
299 if (!page && write) {
300 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
301 if (!page)
302 return NULL;
303 bprm->page[pos / PAGE_SIZE] = page;
304 }
305
306 return page;
307}
308
309static void put_arg_page(struct page *page)
310{
311}
312
313static void free_arg_page(struct linux_binprm *bprm, int i)
314{
315 if (bprm->page[i]) {
316 __free_page(bprm->page[i]);
317 bprm->page[i] = NULL;
318 }
319}
320
321static void free_arg_pages(struct linux_binprm *bprm)
322{
323 int i;
324
325 for (i = 0; i < MAX_ARG_PAGES; i++)
326 free_arg_page(bprm, i);
327}
328
329static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
330 struct page *page)
331{
332}
333
334static int __bprm_mm_init(struct linux_binprm *bprm)
335{
336 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
337 return 0;
338}
339
340static bool valid_arg_len(struct linux_binprm *bprm, long len)
341{
342 return len <= bprm->p;
343}
344
345#endif /* CONFIG_MMU */
346
347/*
348 * Create a new mm_struct and populate it with a temporary stack
349 * vm_area_struct. We don't have enough context at this point to set the stack
350 * flags, permissions, and offset, so we use temporary values. We'll update
351 * them later in setup_arg_pages().
352 */
353int bprm_mm_init(struct linux_binprm *bprm)
354{
355 int err;
356 struct mm_struct *mm = NULL;
357
358 bprm->mm = mm = mm_alloc();
359 err = -ENOMEM;
360 if (!mm)
361 goto err;
362
363 err = init_new_context(current, mm);
364 if (err)
365 goto err;
366
367 err = __bprm_mm_init(bprm);
368 if (err)
369 goto err;
370
371 return 0;
372
373err:
374 if (mm) {
375 bprm->mm = NULL;
376 mmdrop(mm);
377 }
378
379 return err;
380}
381
382/*
383 * count() counts the number of strings in array ARGV.
384 */
385static int count(char __user * __user * argv, int max)
386{
387 int i = 0;
388
389 if (argv != NULL) {
390 for (;;) {
391 char __user * p;
392
393 if (get_user(p, argv))
394 return -EFAULT;
395 if (!p)
396 break;
397 argv++;
398 if(++i > max)
399 return -E2BIG;
400 cond_resched();
401 }
402 }
403 return i;
404}
405
406/*
407 * 'copy_strings()' copies argument/environment strings from the old
408 * processes's memory to the new process's stack. The call to get_user_pages()
409 * ensures the destination page is created and not swapped out.
410 */
411static int copy_strings(int argc, char __user * __user * argv,
412 struct linux_binprm *bprm)
413{
414 struct page *kmapped_page = NULL;
415 char *kaddr = NULL;
416 unsigned long kpos = 0;
417 int ret;
418
419 while (argc-- > 0) {
420 char __user *str;
421 int len;
422 unsigned long pos;
423
424 if (get_user(str, argv+argc) ||
425 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
426 ret = -EFAULT;
427 goto out;
428 }
429
430 if (!valid_arg_len(bprm, len)) {
431 ret = -E2BIG;
432 goto out;
433 }
434
435 /* We're going to work our way backwords. */
436 pos = bprm->p;
437 str += len;
438 bprm->p -= len;
439
440 while (len > 0) {
441 int offset, bytes_to_copy;
442
443 offset = pos % PAGE_SIZE;
444 if (offset == 0)
445 offset = PAGE_SIZE;
446
447 bytes_to_copy = offset;
448 if (bytes_to_copy > len)
449 bytes_to_copy = len;
450
451 offset -= bytes_to_copy;
452 pos -= bytes_to_copy;
453 str -= bytes_to_copy;
454 len -= bytes_to_copy;
455
456 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
457 struct page *page;
458
459 page = get_arg_page(bprm, pos, 1);
460 if (!page) {
461 ret = -E2BIG;
462 goto out;
463 }
464
465 if (kmapped_page) {
466 flush_kernel_dcache_page(kmapped_page);
467 kunmap(kmapped_page);
468 put_arg_page(kmapped_page);
469 }
470 kmapped_page = page;
471 kaddr = kmap(kmapped_page);
472 kpos = pos & PAGE_MASK;
473 flush_arg_page(bprm, kpos, kmapped_page);
474 }
475 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
476 ret = -EFAULT;
477 goto out;
478 }
479 }
480 }
481 ret = 0;
482out:
483 if (kmapped_page) {
484 flush_kernel_dcache_page(kmapped_page);
485 kunmap(kmapped_page);
486 put_arg_page(kmapped_page);
487 }
488 return ret;
489}
490
491/*
492 * Like copy_strings, but get argv and its values from kernel memory.
493 */
494int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
495{
496 int r;
497 mm_segment_t oldfs = get_fs();
498 set_fs(KERNEL_DS);
499 r = copy_strings(argc, (char __user * __user *)argv, bprm);
500 set_fs(oldfs);
501 return r;
502}
503EXPORT_SYMBOL(copy_strings_kernel);
504
505#ifdef CONFIG_MMU
506
507/*
508 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
509 * the binfmt code determines where the new stack should reside, we shift it to
510 * its final location. The process proceeds as follows:
511 *
512 * 1) Use shift to calculate the new vma endpoints.
513 * 2) Extend vma to cover both the old and new ranges. This ensures the
514 * arguments passed to subsequent functions are consistent.
515 * 3) Move vma's page tables to the new range.
516 * 4) Free up any cleared pgd range.
517 * 5) Shrink the vma to cover only the new range.
518 */
519static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
520{
521 struct mm_struct *mm = vma->vm_mm;
522 unsigned long old_start = vma->vm_start;
523 unsigned long old_end = vma->vm_end;
524 unsigned long length = old_end - old_start;
525 unsigned long new_start = old_start - shift;
526 unsigned long new_end = old_end - shift;
527 struct mmu_gather *tlb;
528
529 BUG_ON(new_start > new_end);
530
531 /*
532 * ensure there are no vmas between where we want to go
533 * and where we are
534 */
535 if (vma != find_vma(mm, new_start))
536 return -EFAULT;
537
538 /*
539 * cover the whole range: [new_start, old_end)
540 */
541 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
542
543 /*
544 * move the page tables downwards, on failure we rely on
545 * process cleanup to remove whatever mess we made.
546 */
547 if (length != move_page_tables(vma, old_start,
548 vma, new_start, length))
549 return -ENOMEM;
550
551 lru_add_drain();
552 tlb = tlb_gather_mmu(mm, 0);
553 if (new_end > old_start) {
554 /*
555 * when the old and new regions overlap clear from new_end.
556 */
557 free_pgd_range(&tlb, new_end, old_end, new_end,
558 vma->vm_next ? vma->vm_next->vm_start : 0);
559 } else {
560 /*
561 * otherwise, clean from old_start; this is done to not touch
562 * the address space in [new_end, old_start) some architectures
563 * have constraints on va-space that make this illegal (IA64) -
564 * for the others its just a little faster.
565 */
566 free_pgd_range(&tlb, old_start, old_end, new_end,
567 vma->vm_next ? vma->vm_next->vm_start : 0);
568 }
569 tlb_finish_mmu(tlb, new_end, old_end);
570
571 /*
572 * shrink the vma to just the new range.
573 */
574 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
575
576 return 0;
577}
578
579#define EXTRA_STACK_VM_PAGES 20 /* random */
580
581/*
582 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
583 * the stack is optionally relocated, and some extra space is added.
584 */
585int setup_arg_pages(struct linux_binprm *bprm,
586 unsigned long stack_top,
587 int executable_stack)
588{
589 unsigned long ret;
590 unsigned long stack_shift;
591 struct mm_struct *mm = current->mm;
592 struct vm_area_struct *vma = bprm->vma;
593 struct vm_area_struct *prev = NULL;
594 unsigned long vm_flags;
595 unsigned long stack_base;
596
597#ifdef CONFIG_STACK_GROWSUP
598 /* Limit stack size to 1GB */
599 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
600 if (stack_base > (1 << 30))
601 stack_base = 1 << 30;
602
603 /* Make sure we didn't let the argument array grow too large. */
604 if (vma->vm_end - vma->vm_start > stack_base)
605 return -ENOMEM;
606
607 stack_base = PAGE_ALIGN(stack_top - stack_base);
608
609 stack_shift = vma->vm_start - stack_base;
610 mm->arg_start = bprm->p - stack_shift;
611 bprm->p = vma->vm_end - stack_shift;
612#else
613 stack_top = arch_align_stack(stack_top);
614 stack_top = PAGE_ALIGN(stack_top);
615 stack_shift = vma->vm_end - stack_top;
616
617 bprm->p -= stack_shift;
618 mm->arg_start = bprm->p;
619#endif
620
621 if (bprm->loader)
622 bprm->loader -= stack_shift;
623 bprm->exec -= stack_shift;
624
625 down_write(&mm->mmap_sem);
626 vm_flags = vma->vm_flags;
627
628 /*
629 * Adjust stack execute permissions; explicitly enable for
630 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
631 * (arch default) otherwise.
632 */
633 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
634 vm_flags |= VM_EXEC;
635 else if (executable_stack == EXSTACK_DISABLE_X)
636 vm_flags &= ~VM_EXEC;
637 vm_flags |= mm->def_flags;
638
639 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
640 vm_flags);
641 if (ret)
642 goto out_unlock;
643 BUG_ON(prev != vma);
644
645 /* Move stack pages down in memory. */
646 if (stack_shift) {
647 ret = shift_arg_pages(vma, stack_shift);
648 if (ret) {
649 up_write(&mm->mmap_sem);
650 return ret;
651 }
652 }
653
654#ifdef CONFIG_STACK_GROWSUP
655 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
656#else
657 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
658#endif
659 ret = expand_stack(vma, stack_base);
660 if (ret)
661 ret = -EFAULT;
662
663out_unlock:
664 up_write(&mm->mmap_sem);
665 return 0;
666}
667EXPORT_SYMBOL(setup_arg_pages);
668
669#endif /* CONFIG_MMU */
670
671struct file *open_exec(const char *name)
672{
673 struct nameidata nd;
674 int err;
675 struct file *file;
676
677 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
678 file = ERR_PTR(err);
679
680 if (!err) {
681 struct inode *inode = nd.dentry->d_inode;
682 file = ERR_PTR(-EACCES);
683 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
684 S_ISREG(inode->i_mode)) {
685 int err = vfs_permission(&nd, MAY_EXEC);
686 file = ERR_PTR(err);
687 if (!err) {
688 file = nameidata_to_filp(&nd, O_RDONLY);
689 if (!IS_ERR(file)) {
690 err = deny_write_access(file);
691 if (err) {
692 fput(file);
693 file = ERR_PTR(err);
694 }
695 }
696out:
697 return file;
698 }
699 }
700 release_open_intent(&nd);
701 path_release(&nd);
702 }
703 goto out;
704}
705
706EXPORT_SYMBOL(open_exec);
707
708int kernel_read(struct file *file, unsigned long offset,
709 char *addr, unsigned long count)
710{
711 mm_segment_t old_fs;
712 loff_t pos = offset;
713 int result;
714
715 old_fs = get_fs();
716 set_fs(get_ds());
717 /* The cast to a user pointer is valid due to the set_fs() */
718 result = vfs_read(file, (void __user *)addr, count, &pos);
719 set_fs(old_fs);
720 return result;
721}
722
723EXPORT_SYMBOL(kernel_read);
724
725static int exec_mmap(struct mm_struct *mm)
726{
727 struct task_struct *tsk;
728 struct mm_struct * old_mm, *active_mm;
729
730 /* Notify parent that we're no longer interested in the old VM */
731 tsk = current;
732 old_mm = current->mm;
733 mm_release(tsk, old_mm);
734
735 if (old_mm) {
736 /*
737 * Make sure that if there is a core dump in progress
738 * for the old mm, we get out and die instead of going
739 * through with the exec. We must hold mmap_sem around
740 * checking core_waiters and changing tsk->mm. The
741 * core-inducing thread will increment core_waiters for
742 * each thread whose ->mm == old_mm.
743 */
744 down_read(&old_mm->mmap_sem);
745 if (unlikely(old_mm->core_waiters)) {
746 up_read(&old_mm->mmap_sem);
747 return -EINTR;
748 }
749 }
750 task_lock(tsk);
751 active_mm = tsk->active_mm;
752 tsk->mm = mm;
753 tsk->active_mm = mm;
754 activate_mm(active_mm, mm);
755 task_unlock(tsk);
756 arch_pick_mmap_layout(mm);
757 if (old_mm) {
758 up_read(&old_mm->mmap_sem);
759 BUG_ON(active_mm != old_mm);
760 mmput(old_mm);
761 return 0;
762 }
763 mmdrop(active_mm);
764 return 0;
765}
766
767/*
768 * This function makes sure the current process has its own signal table,
769 * so that flush_signal_handlers can later reset the handlers without
770 * disturbing other processes. (Other processes might share the signal
771 * table via the CLONE_SIGHAND option to clone().)
772 */
773static int de_thread(struct task_struct *tsk)
774{
775 struct signal_struct *sig = tsk->signal;
776 struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
777 spinlock_t *lock = &oldsighand->siglock;
778 struct task_struct *leader = NULL;
779 int count;
780
781 /*
782 * If we don't share sighandlers, then we aren't sharing anything
783 * and we can just re-use it all.
784 */
785 if (atomic_read(&oldsighand->count) <= 1) {
786 exit_itimers(sig);
787 return 0;
788 }
789
790 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
791 if (!newsighand)
792 return -ENOMEM;
793
794 if (thread_group_empty(tsk))
795 goto no_thread_group;
796
797 /*
798 * Kill all other threads in the thread group.
799 * We must hold tasklist_lock to call zap_other_threads.
800 */
801 read_lock(&tasklist_lock);
802 spin_lock_irq(lock);
803 if (sig->flags & SIGNAL_GROUP_EXIT) {
804 /*
805 * Another group action in progress, just
806 * return so that the signal is processed.
807 */
808 spin_unlock_irq(lock);
809 read_unlock(&tasklist_lock);
810 kmem_cache_free(sighand_cachep, newsighand);
811 return -EAGAIN;
812 }
813
814 /*
815 * child_reaper ignores SIGKILL, change it now.
816 * Reparenting needs write_lock on tasklist_lock,
817 * so it is safe to do it under read_lock.
818 */
819 if (unlikely(tsk->group_leader == child_reaper(tsk)))
820 tsk->nsproxy->pid_ns->child_reaper = tsk;
821
822 zap_other_threads(tsk);
823 read_unlock(&tasklist_lock);
824
825 /*
826 * Account for the thread group leader hanging around:
827 */
828 count = 1;
829 if (!thread_group_leader(tsk)) {
830 count = 2;
831 /*
832 * The SIGALRM timer survives the exec, but needs to point
833 * at us as the new group leader now. We have a race with
834 * a timer firing now getting the old leader, so we need to
835 * synchronize with any firing (by calling del_timer_sync)
836 * before we can safely let the old group leader die.
837 */
838 sig->tsk = tsk;
839 spin_unlock_irq(lock);
840 if (hrtimer_cancel(&sig->real_timer))
841 hrtimer_restart(&sig->real_timer);
842 spin_lock_irq(lock);
843 }
844 while (atomic_read(&sig->count) > count) {
845 sig->group_exit_task = tsk;
846 sig->notify_count = count;
847 __set_current_state(TASK_UNINTERRUPTIBLE);
848 spin_unlock_irq(lock);
849 schedule();
850 spin_lock_irq(lock);
851 }
852 sig->group_exit_task = NULL;
853 sig->notify_count = 0;
854 spin_unlock_irq(lock);
855
856 /*
857 * At this point all other threads have exited, all we have to
858 * do is to wait for the thread group leader to become inactive,
859 * and to assume its PID:
860 */
861 if (!thread_group_leader(tsk)) {
862 /*
863 * Wait for the thread group leader to be a zombie.
864 * It should already be zombie at this point, most
865 * of the time.
866 */
867 leader = tsk->group_leader;
868 while (leader->exit_state != EXIT_ZOMBIE)
869 yield();
870
871 /*
872 * The only record we have of the real-time age of a
873 * process, regardless of execs it's done, is start_time.
874 * All the past CPU time is accumulated in signal_struct
875 * from sister threads now dead. But in this non-leader
876 * exec, nothing survives from the original leader thread,
877 * whose birth marks the true age of this process now.
878 * When we take on its identity by switching to its PID, we
879 * also take its birthdate (always earlier than our own).
880 */
881 tsk->start_time = leader->start_time;
882
883 write_lock_irq(&tasklist_lock);
884
885 BUG_ON(leader->tgid != tsk->tgid);
886 BUG_ON(tsk->pid == tsk->tgid);
887 /*
888 * An exec() starts a new thread group with the
889 * TGID of the previous thread group. Rehash the
890 * two threads with a switched PID, and release
891 * the former thread group leader:
892 */
893
894 /* Become a process group leader with the old leader's pid.
895 * The old leader becomes a thread of the this thread group.
896 * Note: The old leader also uses this pid until release_task
897 * is called. Odd but simple and correct.
898 */
899 detach_pid(tsk, PIDTYPE_PID);
900 tsk->pid = leader->pid;
901 attach_pid(tsk, PIDTYPE_PID, find_pid(tsk->pid));
902 transfer_pid(leader, tsk, PIDTYPE_PGID);
903 transfer_pid(leader, tsk, PIDTYPE_SID);
904 list_replace_rcu(&leader->tasks, &tsk->tasks);
905
906 tsk->group_leader = tsk;
907 leader->group_leader = tsk;
908
909 tsk->exit_signal = SIGCHLD;
910
911 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
912 leader->exit_state = EXIT_DEAD;
913
914 write_unlock_irq(&tasklist_lock);
915 }
916
917 /*
918 * There may be one thread left which is just exiting,
919 * but it's safe to stop telling the group to kill themselves.
920 */
921 sig->flags = 0;
922
923no_thread_group:
924 exit_itimers(sig);
925 if (leader)
926 release_task(leader);
927
928 if (atomic_read(&oldsighand->count) == 1) {
929 /*
930 * Now that we nuked the rest of the thread group,
931 * it turns out we are not sharing sighand any more either.
932 * So we can just keep it.
933 */
934 kmem_cache_free(sighand_cachep, newsighand);
935 } else {
936 /*
937 * Move our state over to newsighand and switch it in.
938 */
939 atomic_set(&newsighand->count, 1);
940 memcpy(newsighand->action, oldsighand->action,
941 sizeof(newsighand->action));
942
943 write_lock_irq(&tasklist_lock);
944 spin_lock(&oldsighand->siglock);
945 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
946
947 rcu_assign_pointer(tsk->sighand, newsighand);
948 recalc_sigpending();
949
950 spin_unlock(&newsighand->siglock);
951 spin_unlock(&oldsighand->siglock);
952 write_unlock_irq(&tasklist_lock);
953
954 __cleanup_sighand(oldsighand);
955 }
956
957 BUG_ON(!thread_group_leader(tsk));
958 return 0;
959}
960
961/*
962 * These functions flushes out all traces of the currently running executable
963 * so that a new one can be started
964 */
965
966static void flush_old_files(struct files_struct * files)
967{
968 long j = -1;
969 struct fdtable *fdt;
970
971 spin_lock(&files->file_lock);
972 for (;;) {
973 unsigned long set, i;
974
975 j++;
976 i = j * __NFDBITS;
977 fdt = files_fdtable(files);
978 if (i >= fdt->max_fds)
979 break;
980 set = fdt->close_on_exec->fds_bits[j];
981 if (!set)
982 continue;
983 fdt->close_on_exec->fds_bits[j] = 0;
984 spin_unlock(&files->file_lock);
985 for ( ; set ; i++,set >>= 1) {
986 if (set & 1) {
987 sys_close(i);
988 }
989 }
990 spin_lock(&files->file_lock);
991
992 }
993 spin_unlock(&files->file_lock);
994}
995
996void get_task_comm(char *buf, struct task_struct *tsk)
997{
998 /* buf must be at least sizeof(tsk->comm) in size */
999 task_lock(tsk);
1000 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1001 task_unlock(tsk);
1002}
1003
1004void set_task_comm(struct task_struct *tsk, char *buf)
1005{
1006 task_lock(tsk);
1007 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1008 task_unlock(tsk);
1009}
1010
1011int flush_old_exec(struct linux_binprm * bprm)
1012{
1013 char * name;
1014 int i, ch, retval;
1015 struct files_struct *files;
1016 char tcomm[sizeof(current->comm)];
1017
1018 /*
1019 * Make sure we have a private signal table and that
1020 * we are unassociated from the previous thread group.
1021 */
1022 retval = de_thread(current);
1023 if (retval)
1024 goto out;
1025
1026 /*
1027 * Make sure we have private file handles. Ask the
1028 * fork helper to do the work for us and the exit
1029 * helper to do the cleanup of the old one.
1030 */
1031 files = current->files; /* refcounted so safe to hold */
1032 retval = unshare_files();
1033 if (retval)
1034 goto out;
1035 /*
1036 * Release all of the old mmap stuff
1037 */
1038 retval = exec_mmap(bprm->mm);
1039 if (retval)
1040 goto mmap_failed;
1041
1042 bprm->mm = NULL; /* We're using it now */
1043
1044 /* This is the point of no return */
1045 put_files_struct(files);
1046
1047 current->sas_ss_sp = current->sas_ss_size = 0;
1048
1049 if (current->euid == current->uid && current->egid == current->gid)
1050 set_dumpable(current->mm, 1);
1051 else
1052 set_dumpable(current->mm, suid_dumpable);
1053
1054 name = bprm->filename;
1055
1056 /* Copies the binary name from after last slash */
1057 for (i=0; (ch = *(name++)) != '\0';) {
1058 if (ch == '/')
1059 i = 0; /* overwrite what we wrote */
1060 else
1061 if (i < (sizeof(tcomm) - 1))
1062 tcomm[i++] = ch;
1063 }
1064 tcomm[i] = '\0';
1065 set_task_comm(current, tcomm);
1066
1067 current->flags &= ~PF_RANDOMIZE;
1068 flush_thread();
1069
1070 /* Set the new mm task size. We have to do that late because it may
1071 * depend on TIF_32BIT which is only updated in flush_thread() on
1072 * some architectures like powerpc
1073 */
1074 current->mm->task_size = TASK_SIZE;
1075
1076 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1077 suid_keys(current);
1078 set_dumpable(current->mm, suid_dumpable);
1079 current->pdeath_signal = 0;
1080 } else if (file_permission(bprm->file, MAY_READ) ||
1081 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1082 suid_keys(current);
1083 set_dumpable(current->mm, suid_dumpable);
1084 }
1085
1086 /* An exec changes our domain. We are no longer part of the thread
1087 group */
1088
1089 current->self_exec_id++;
1090
1091 flush_signal_handlers(current, 0);
1092 flush_old_files(current->files);
1093
1094 return 0;
1095
1096mmap_failed:
1097 reset_files_struct(current, files);
1098out:
1099 return retval;
1100}
1101
1102EXPORT_SYMBOL(flush_old_exec);
1103
1104/*
1105 * Fill the binprm structure from the inode.
1106 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1107 */
1108int prepare_binprm(struct linux_binprm *bprm)
1109{
1110 int mode;
1111 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1112 int retval;
1113
1114 mode = inode->i_mode;
1115 if (bprm->file->f_op == NULL)
1116 return -EACCES;
1117
1118 bprm->e_uid = current->euid;
1119 bprm->e_gid = current->egid;
1120
1121 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1122 /* Set-uid? */
1123 if (mode & S_ISUID) {
1124 current->personality &= ~PER_CLEAR_ON_SETID;
1125 bprm->e_uid = inode->i_uid;
1126 }
1127
1128 /* Set-gid? */
1129 /*
1130 * If setgid is set but no group execute bit then this
1131 * is a candidate for mandatory locking, not a setgid
1132 * executable.
1133 */
1134 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1135 current->personality &= ~PER_CLEAR_ON_SETID;
1136 bprm->e_gid = inode->i_gid;
1137 }
1138 }
1139
1140 /* fill in binprm security blob */
1141 retval = security_bprm_set(bprm);
1142 if (retval)
1143 return retval;
1144
1145 memset(bprm->buf,0,BINPRM_BUF_SIZE);
1146 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1147}
1148
1149EXPORT_SYMBOL(prepare_binprm);
1150
1151static int unsafe_exec(struct task_struct *p)
1152{
1153 int unsafe = 0;
1154 if (p->ptrace & PT_PTRACED) {
1155 if (p->ptrace & PT_PTRACE_CAP)
1156 unsafe |= LSM_UNSAFE_PTRACE_CAP;
1157 else
1158 unsafe |= LSM_UNSAFE_PTRACE;
1159 }
1160 if (atomic_read(&p->fs->count) > 1 ||
1161 atomic_read(&p->files->count) > 1 ||
1162 atomic_read(&p->sighand->count) > 1)
1163 unsafe |= LSM_UNSAFE_SHARE;
1164
1165 return unsafe;
1166}
1167
1168void compute_creds(struct linux_binprm *bprm)
1169{
1170 int unsafe;
1171
1172 if (bprm->e_uid != current->uid) {
1173 suid_keys(current);
1174 current->pdeath_signal = 0;
1175 }
1176 exec_keys(current);
1177
1178 task_lock(current);
1179 unsafe = unsafe_exec(current);
1180 security_bprm_apply_creds(bprm, unsafe);
1181 task_unlock(current);
1182 security_bprm_post_apply_creds(bprm);
1183}
1184EXPORT_SYMBOL(compute_creds);
1185
1186/*
1187 * Arguments are '\0' separated strings found at the location bprm->p
1188 * points to; chop off the first by relocating brpm->p to right after
1189 * the first '\0' encountered.
1190 */
1191int remove_arg_zero(struct linux_binprm *bprm)
1192{
1193 int ret = 0;
1194 unsigned long offset;
1195 char *kaddr;
1196 struct page *page;
1197
1198 if (!bprm->argc)
1199 return 0;
1200
1201 do {
1202 offset = bprm->p & ~PAGE_MASK;
1203 page = get_arg_page(bprm, bprm->p, 0);
1204 if (!page) {
1205 ret = -EFAULT;
1206 goto out;
1207 }
1208 kaddr = kmap_atomic(page, KM_USER0);
1209
1210 for (; offset < PAGE_SIZE && kaddr[offset];
1211 offset++, bprm->p++)
1212 ;
1213
1214 kunmap_atomic(kaddr, KM_USER0);
1215 put_arg_page(page);
1216
1217 if (offset == PAGE_SIZE)
1218 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1219 } while (offset == PAGE_SIZE);
1220
1221 bprm->p++;
1222 bprm->argc--;
1223 ret = 0;
1224
1225out:
1226 return ret;
1227}
1228EXPORT_SYMBOL(remove_arg_zero);
1229
1230/*
1231 * cycle the list of binary formats handler, until one recognizes the image
1232 */
1233int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1234{
1235 int try,retval;
1236 struct linux_binfmt *fmt;
1237#ifdef __alpha__
1238 /* handle /sbin/loader.. */
1239 {
1240 struct exec * eh = (struct exec *) bprm->buf;
1241
1242 if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1243 (eh->fh.f_flags & 0x3000) == 0x3000)
1244 {
1245 struct file * file;
1246 unsigned long loader;
1247
1248 allow_write_access(bprm->file);
1249 fput(bprm->file);
1250 bprm->file = NULL;
1251
1252 loader = bprm->vma->vm_end - sizeof(void *);
1253
1254 file = open_exec("/sbin/loader");
1255 retval = PTR_ERR(file);
1256 if (IS_ERR(file))
1257 return retval;
1258
1259 /* Remember if the application is TASO. */
1260 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1261
1262 bprm->file = file;
1263 bprm->loader = loader;
1264 retval = prepare_binprm(bprm);
1265 if (retval<0)
1266 return retval;
1267 /* should call search_binary_handler recursively here,
1268 but it does not matter */
1269 }
1270 }
1271#endif
1272 retval = security_bprm_check(bprm);
1273 if (retval)
1274 return retval;
1275
1276 /* kernel module loader fixup */
1277 /* so we don't try to load run modprobe in kernel space. */
1278 set_fs(USER_DS);
1279
1280 retval = audit_bprm(bprm);
1281 if (retval)
1282 return retval;
1283
1284 retval = -ENOENT;
1285 for (try=0; try<2; try++) {
1286 read_lock(&binfmt_lock);
1287 for (fmt = formats ; fmt ; fmt = fmt->next) {
1288 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1289 if (!fn)
1290 continue;
1291 if (!try_module_get(fmt->module))
1292 continue;
1293 read_unlock(&binfmt_lock);
1294 retval = fn(bprm, regs);
1295 if (retval >= 0) {
1296 put_binfmt(fmt);
1297 allow_write_access(bprm->file);
1298 if (bprm->file)
1299 fput(bprm->file);
1300 bprm->file = NULL;
1301 current->did_exec = 1;
1302 proc_exec_connector(current);
1303 return retval;
1304 }
1305 read_lock(&binfmt_lock);
1306 put_binfmt(fmt);
1307 if (retval != -ENOEXEC || bprm->mm == NULL)
1308 break;
1309 if (!bprm->file) {
1310 read_unlock(&binfmt_lock);
1311 return retval;
1312 }
1313 }
1314 read_unlock(&binfmt_lock);
1315 if (retval != -ENOEXEC || bprm->mm == NULL) {
1316 break;
1317#ifdef CONFIG_KMOD
1318 }else{
1319#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1320 if (printable(bprm->buf[0]) &&
1321 printable(bprm->buf[1]) &&
1322 printable(bprm->buf[2]) &&
1323 printable(bprm->buf[3]))
1324 break; /* -ENOEXEC */
1325 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1326#endif
1327 }
1328 }
1329 return retval;
1330}
1331
1332EXPORT_SYMBOL(search_binary_handler);
1333
1334/*
1335 * sys_execve() executes a new program.
1336 */
1337int do_execve(char * filename,
1338 char __user *__user *argv,
1339 char __user *__user *envp,
1340 struct pt_regs * regs)
1341{
1342 struct linux_binprm *bprm;
1343 struct file *file;
1344 unsigned long env_p;
1345 int retval;
1346
1347 retval = -ENOMEM;
1348 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1349 if (!bprm)
1350 goto out_ret;
1351
1352 file = open_exec(filename);
1353 retval = PTR_ERR(file);
1354 if (IS_ERR(file))
1355 goto out_kfree;
1356
1357 sched_exec();
1358
1359 bprm->file = file;
1360 bprm->filename = filename;
1361 bprm->interp = filename;
1362
1363 retval = bprm_mm_init(bprm);
1364 if (retval)
1365 goto out_file;
1366
1367 bprm->argc = count(argv, MAX_ARG_STRINGS);
1368 if ((retval = bprm->argc) < 0)
1369 goto out_mm;
1370
1371 bprm->envc = count(envp, MAX_ARG_STRINGS);
1372 if ((retval = bprm->envc) < 0)
1373 goto out_mm;
1374
1375 retval = security_bprm_alloc(bprm);
1376 if (retval)
1377 goto out;
1378
1379 retval = prepare_binprm(bprm);
1380 if (retval < 0)
1381 goto out;
1382
1383 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1384 if (retval < 0)
1385 goto out;
1386
1387 bprm->exec = bprm->p;
1388 retval = copy_strings(bprm->envc, envp, bprm);
1389 if (retval < 0)
1390 goto out;
1391
1392 env_p = bprm->p;
1393 retval = copy_strings(bprm->argc, argv, bprm);
1394 if (retval < 0)
1395 goto out;
1396 bprm->argv_len = env_p - bprm->p;
1397
1398 retval = search_binary_handler(bprm,regs);
1399 if (retval >= 0) {
1400 /* execve success */
1401 free_arg_pages(bprm);
1402 security_bprm_free(bprm);
1403 acct_update_integrals(current);
1404 kfree(bprm);
1405 return retval;
1406 }
1407
1408out:
1409 free_arg_pages(bprm);
1410 if (bprm->security)
1411 security_bprm_free(bprm);
1412
1413out_mm:
1414 if (bprm->mm)
1415 mmput (bprm->mm);
1416
1417out_file:
1418 if (bprm->file) {
1419 allow_write_access(bprm->file);
1420 fput(bprm->file);
1421 }
1422out_kfree:
1423 kfree(bprm);
1424
1425out_ret:
1426 return retval;
1427}
1428
1429int set_binfmt(struct linux_binfmt *new)
1430{
1431 struct linux_binfmt *old = current->binfmt;
1432
1433 if (new) {
1434 if (!try_module_get(new->module))
1435 return -1;
1436 }
1437 current->binfmt = new;
1438 if (old)
1439 module_put(old->module);
1440 return 0;
1441}
1442
1443EXPORT_SYMBOL(set_binfmt);
1444
1445/* format_corename will inspect the pattern parameter, and output a
1446 * name into corename, which must have space for at least
1447 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1448 */
1449static int format_corename(char *corename, const char *pattern, long signr)
1450{
1451 const char *pat_ptr = pattern;
1452 char *out_ptr = corename;
1453 char *const out_end = corename + CORENAME_MAX_SIZE;
1454 int rc;
1455 int pid_in_pattern = 0;
1456 int ispipe = 0;
1457
1458 if (*pattern == '|')
1459 ispipe = 1;
1460
1461 /* Repeat as long as we have more pattern to process and more output
1462 space */
1463 while (*pat_ptr) {
1464 if (*pat_ptr != '%') {
1465 if (out_ptr == out_end)
1466 goto out;
1467 *out_ptr++ = *pat_ptr++;
1468 } else {
1469 switch (*++pat_ptr) {
1470 case 0:
1471 goto out;
1472 /* Double percent, output one percent */
1473 case '%':
1474 if (out_ptr == out_end)
1475 goto out;
1476 *out_ptr++ = '%';
1477 break;
1478 /* pid */
1479 case 'p':
1480 pid_in_pattern = 1;
1481 rc = snprintf(out_ptr, out_end - out_ptr,
1482 "%d", current->tgid);
1483 if (rc > out_end - out_ptr)
1484 goto out;
1485 out_ptr += rc;
1486 break;
1487 /* uid */
1488 case 'u':
1489 rc = snprintf(out_ptr, out_end - out_ptr,
1490 "%d", current->uid);
1491 if (rc > out_end - out_ptr)
1492 goto out;
1493 out_ptr += rc;
1494 break;
1495 /* gid */
1496 case 'g':
1497 rc = snprintf(out_ptr, out_end - out_ptr,
1498 "%d", current->gid);
1499 if (rc > out_end - out_ptr)
1500 goto out;
1501 out_ptr += rc;
1502 break;
1503 /* signal that caused the coredump */
1504 case 's':
1505 rc = snprintf(out_ptr, out_end - out_ptr,
1506 "%ld", signr);
1507 if (rc > out_end - out_ptr)
1508 goto out;
1509 out_ptr += rc;
1510 break;
1511 /* UNIX time of coredump */
1512 case 't': {
1513 struct timeval tv;
1514 do_gettimeofday(&tv);
1515 rc = snprintf(out_ptr, out_end - out_ptr,
1516 "%lu", tv.tv_sec);
1517 if (rc > out_end - out_ptr)
1518 goto out;
1519 out_ptr += rc;
1520 break;
1521 }
1522 /* hostname */
1523 case 'h':
1524 down_read(&uts_sem);
1525 rc = snprintf(out_ptr, out_end - out_ptr,
1526 "%s", utsname()->nodename);
1527 up_read(&uts_sem);
1528 if (rc > out_end - out_ptr)
1529 goto out;
1530 out_ptr += rc;
1531 break;
1532 /* executable */
1533 case 'e':
1534 rc = snprintf(out_ptr, out_end - out_ptr,
1535 "%s", current->comm);
1536 if (rc > out_end - out_ptr)
1537 goto out;
1538 out_ptr += rc;
1539 break;
1540 default:
1541 break;
1542 }
1543 ++pat_ptr;
1544 }
1545 }
1546 /* Backward compatibility with core_uses_pid:
1547 *
1548 * If core_pattern does not include a %p (as is the default)
1549 * and core_uses_pid is set, then .%pid will be appended to
1550 * the filename. Do not do this for piped commands. */
1551 if (!ispipe && !pid_in_pattern
1552 && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1553 rc = snprintf(out_ptr, out_end - out_ptr,
1554 ".%d", current->tgid);
1555 if (rc > out_end - out_ptr)
1556 goto out;
1557 out_ptr += rc;
1558 }
1559out:
1560 *out_ptr = 0;
1561 return ispipe;
1562}
1563
1564static void zap_process(struct task_struct *start)
1565{
1566 struct task_struct *t;
1567
1568 start->signal->flags = SIGNAL_GROUP_EXIT;
1569 start->signal->group_stop_count = 0;
1570
1571 t = start;
1572 do {
1573 if (t != current && t->mm) {
1574 t->mm->core_waiters++;
1575 sigaddset(&t->pending.signal, SIGKILL);
1576 signal_wake_up(t, 1);
1577 }
1578 } while ((t = next_thread(t)) != start);
1579}
1580
1581static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1582 int exit_code)
1583{
1584 struct task_struct *g, *p;
1585 unsigned long flags;
1586 int err = -EAGAIN;
1587
1588 spin_lock_irq(&tsk->sighand->siglock);
1589 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1590 tsk->signal->group_exit_code = exit_code;
1591 zap_process(tsk);
1592 err = 0;
1593 }
1594 spin_unlock_irq(&tsk->sighand->siglock);
1595 if (err)
1596 return err;
1597
1598 if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1599 goto done;
1600
1601 rcu_read_lock();
1602 for_each_process(g) {
1603 if (g == tsk->group_leader)
1604 continue;
1605
1606 p = g;
1607 do {
1608 if (p->mm) {
1609 if (p->mm == mm) {
1610 /*
1611 * p->sighand can't disappear, but
1612 * may be changed by de_thread()
1613 */
1614 lock_task_sighand(p, &flags);
1615 zap_process(p);
1616 unlock_task_sighand(p, &flags);
1617 }
1618 break;
1619 }
1620 } while ((p = next_thread(p)) != g);
1621 }
1622 rcu_read_unlock();
1623done:
1624 return mm->core_waiters;
1625}
1626
1627static int coredump_wait(int exit_code)
1628{
1629 struct task_struct *tsk = current;
1630 struct mm_struct *mm = tsk->mm;
1631 struct completion startup_done;
1632 struct completion *vfork_done;
1633 int core_waiters;
1634
1635 init_completion(&mm->core_done);
1636 init_completion(&startup_done);
1637 mm->core_startup_done = &startup_done;
1638
1639 core_waiters = zap_threads(tsk, mm, exit_code);
1640 up_write(&mm->mmap_sem);
1641
1642 if (unlikely(core_waiters < 0))
1643 goto fail;
1644
1645 /*
1646 * Make sure nobody is waiting for us to release the VM,
1647 * otherwise we can deadlock when we wait on each other
1648 */
1649 vfork_done = tsk->vfork_done;
1650 if (vfork_done) {
1651 tsk->vfork_done = NULL;
1652 complete(vfork_done);
1653 }
1654
1655 if (core_waiters)
1656 wait_for_completion(&startup_done);
1657fail:
1658 BUG_ON(mm->core_waiters);
1659 return core_waiters;
1660}
1661
1662/*
1663 * set_dumpable converts traditional three-value dumpable to two flags and
1664 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1665 * these bits are not changed atomically. So get_dumpable can observe the
1666 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1667 * return either old dumpable or new one by paying attention to the order of
1668 * modifying the bits.
1669 *
1670 * dumpable | mm->flags (binary)
1671 * old new | initial interim final
1672 * ---------+-----------------------
1673 * 0 1 | 00 01 01
1674 * 0 2 | 00 10(*) 11
1675 * 1 0 | 01 00 00
1676 * 1 2 | 01 11 11
1677 * 2 0 | 11 10(*) 00
1678 * 2 1 | 11 11 01
1679 *
1680 * (*) get_dumpable regards interim value of 10 as 11.
1681 */
1682void set_dumpable(struct mm_struct *mm, int value)
1683{
1684 switch (value) {
1685 case 0:
1686 clear_bit(MMF_DUMPABLE, &mm->flags);
1687 smp_wmb();
1688 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1689 break;
1690 case 1:
1691 set_bit(MMF_DUMPABLE, &mm->flags);
1692 smp_wmb();
1693 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1694 break;
1695 case 2:
1696 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1697 smp_wmb();
1698 set_bit(MMF_DUMPABLE, &mm->flags);
1699 break;
1700 }
1701}
1702EXPORT_SYMBOL_GPL(set_dumpable);
1703
1704int get_dumpable(struct mm_struct *mm)
1705{
1706 int ret;
1707
1708 ret = mm->flags & 0x3;
1709 return (ret >= 2) ? 2 : ret;
1710}
1711
1712int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1713{
1714 char corename[CORENAME_MAX_SIZE + 1];
1715 struct mm_struct *mm = current->mm;
1716 struct linux_binfmt * binfmt;
1717 struct inode * inode;
1718 struct file * file;
1719 int retval = 0;
1720 int fsuid = current->fsuid;
1721 int flag = 0;
1722 int ispipe = 0;
1723
1724 audit_core_dumps(signr);
1725
1726 binfmt = current->binfmt;
1727 if (!binfmt || !binfmt->core_dump)
1728 goto fail;
1729 down_write(&mm->mmap_sem);
1730 if (!get_dumpable(mm)) {
1731 up_write(&mm->mmap_sem);
1732 goto fail;
1733 }
1734
1735 /*
1736 * We cannot trust fsuid as being the "true" uid of the
1737 * process nor do we know its entire history. We only know it
1738 * was tainted so we dump it as root in mode 2.
1739 */
1740 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1741 flag = O_EXCL; /* Stop rewrite attacks */
1742 current->fsuid = 0; /* Dump root private */
1743 }
1744 set_dumpable(mm, 0);
1745
1746 retval = coredump_wait(exit_code);
1747 if (retval < 0)
1748 goto fail;
1749
1750 /*
1751 * Clear any false indication of pending signals that might
1752 * be seen by the filesystem code called to write the core file.
1753 */
1754 clear_thread_flag(TIF_SIGPENDING);
1755
1756 if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
1757 goto fail_unlock;
1758
1759 /*
1760 * lock_kernel() because format_corename() is controlled by sysctl, which
1761 * uses lock_kernel()
1762 */
1763 lock_kernel();
1764 ispipe = format_corename(corename, core_pattern, signr);
1765 unlock_kernel();
1766 if (ispipe) {
1767 /* SIGPIPE can happen, but it's just never processed */
1768 if(call_usermodehelper_pipe(corename+1, NULL, NULL, &file)) {
1769 printk(KERN_INFO "Core dump to %s pipe failed\n",
1770 corename);
1771 goto fail_unlock;
1772 }
1773 } else
1774 file = filp_open(corename,
1775 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1776 0600);
1777 if (IS_ERR(file))
1778 goto fail_unlock;
1779 inode = file->f_path.dentry->d_inode;
1780 if (inode->i_nlink > 1)
1781 goto close_fail; /* multiple links - don't dump */
1782 if (!ispipe && d_unhashed(file->f_path.dentry))
1783 goto close_fail;
1784
1785 /* AK: actually i see no reason to not allow this for named pipes etc.,
1786 but keep the previous behaviour for now. */
1787 if (!ispipe && !S_ISREG(inode->i_mode))
1788 goto close_fail;
1789 if (!file->f_op)
1790 goto close_fail;
1791 if (!file->f_op->write)
1792 goto close_fail;
1793 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1794 goto close_fail;
1795
1796 retval = binfmt->core_dump(signr, regs, file);
1797
1798 if (retval)
1799 current->signal->group_exit_code |= 0x80;
1800close_fail:
1801 filp_close(file, NULL);
1802fail_unlock:
1803 current->fsuid = fsuid;
1804 complete_all(&mm->core_done);
1805fail:
1806 return retval;
1807}