projects/linux·blob v2.6.25 · refs

1797 lines · 40.8 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/string.h>
33#include <linux/init.h>
34#include <linux/pagemap.h>
35#include <linux/highmem.h>
36#include <linux/spinlock.h>
37#include <linux/key.h>
38#include <linux/personality.h>
39#include <linux/binfmts.h>
40#include <linux/swap.h>
41#include <linux/utsname.h>
42#include <linux/pid_namespace.h>
43#include <linux/module.h>
44#include <linux/namei.h>
45#include <linux/proc_fs.h>
46#include <linux/ptrace.h>
47#include <linux/mount.h>
48#include <linux/security.h>
49#include <linux/syscalls.h>
50#include <linux/rmap.h>
51#include <linux/tsacct_kern.h>
52#include <linux/cn_proc.h>
53#include <linux/audit.h>
54
55#include <asm/uaccess.h>
56#include <asm/mmu_context.h>
57#include <asm/tlb.h>
58
59#ifdef CONFIG_KMOD
60#include <linux/kmod.h>
61#endif
62
63int core_uses_pid;
64char core_pattern[CORENAME_MAX_SIZE] = "core";
65int suid_dumpable = 0;
66
67/* The maximal length of core_pattern is also specified in sysctl.c */
68
69static LIST_HEAD(formats);
70static DEFINE_RWLOCK(binfmt_lock);
71
72int register_binfmt(struct linux_binfmt * fmt)
73{
74 if (!fmt)
75 return -EINVAL;
76 write_lock(&binfmt_lock);
77 list_add(&fmt->lh, &formats);
78 write_unlock(&binfmt_lock);
79 return 0;
80}
81
82EXPORT_SYMBOL(register_binfmt);
83
84void unregister_binfmt(struct linux_binfmt * fmt)
85{
86 write_lock(&binfmt_lock);
87 list_del(&fmt->lh);
88 write_unlock(&binfmt_lock);
89}
90
91EXPORT_SYMBOL(unregister_binfmt);
92
93static inline void put_binfmt(struct linux_binfmt * fmt)
94{
95 module_put(fmt->module);
96}
97
98/*
99 * Note that a shared library must be both readable and executable due to
100 * security reasons.
101 *
102 * Also note that we take the address to load from from the file itself.
103 */
104asmlinkage long sys_uselib(const char __user * library)
105{
106 struct file * file;
107 struct nameidata nd;
108 int error;
109
110 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
111 if (error)
112 goto out;
113
114 error = -EINVAL;
115 if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
116 goto exit;
117
118 error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
119 if (error)
120 goto exit;
121
122 file = nameidata_to_filp(&nd, O_RDONLY|O_LARGEFILE);
123 error = PTR_ERR(file);
124 if (IS_ERR(file))
125 goto out;
126
127 error = -ENOEXEC;
128 if(file->f_op) {
129 struct linux_binfmt * fmt;
130
131 read_lock(&binfmt_lock);
132 list_for_each_entry(fmt, &formats, lh) {
133 if (!fmt->load_shlib)
134 continue;
135 if (!try_module_get(fmt->module))
136 continue;
137 read_unlock(&binfmt_lock);
138 error = fmt->load_shlib(file);
139 read_lock(&binfmt_lock);
140 put_binfmt(fmt);
141 if (error != -ENOEXEC)
142 break;
143 }
144 read_unlock(&binfmt_lock);
145 }
146 fput(file);
147out:
148 return error;
149exit:
150 release_open_intent(&nd);
151 path_put(&nd.path);
152 goto out;
153}
154
155#ifdef CONFIG_MMU
156
157static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
158 int write)
159{
160 struct page *page;
161 int ret;
162
163#ifdef CONFIG_STACK_GROWSUP
164 if (write) {
165 ret = expand_stack_downwards(bprm->vma, pos);
166 if (ret < 0)
167 return NULL;
168 }
169#endif
170 ret = get_user_pages(current, bprm->mm, pos,
171 1, write, 1, &page, NULL);
172 if (ret <= 0)
173 return NULL;
174
175 if (write) {
176 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
177 struct rlimit *rlim;
178
179 /*
180 * We've historically supported up to 32 pages (ARG_MAX)
181 * of argument strings even with small stacks
182 */
183 if (size <= ARG_MAX)
184 return page;
185
186 /*
187 * Limit to 1/4-th the stack size for the argv+env strings.
188 * This ensures that:
189 * - the remaining binfmt code will not run out of stack space,
190 * - the program will have a reasonable amount of stack left
191 * to work from.
192 */
193 rlim = current->signal->rlim;
194 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
195 put_page(page);
196 return NULL;
197 }
198 }
199
200 return page;
201}
202
203static void put_arg_page(struct page *page)
204{
205 put_page(page);
206}
207
208static void free_arg_page(struct linux_binprm *bprm, int i)
209{
210}
211
212static void free_arg_pages(struct linux_binprm *bprm)
213{
214}
215
216static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
217 struct page *page)
218{
219 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
220}
221
222static int __bprm_mm_init(struct linux_binprm *bprm)
223{
224 int err = -ENOMEM;
225 struct vm_area_struct *vma = NULL;
226 struct mm_struct *mm = bprm->mm;
227
228 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
229 if (!vma)
230 goto err;
231
232 down_write(&mm->mmap_sem);
233 vma->vm_mm = mm;
234
235 /*
236 * Place the stack at the largest stack address the architecture
237 * supports. Later, we'll move this to an appropriate place. We don't
238 * use STACK_TOP because that can depend on attributes which aren't
239 * configured yet.
240 */
241 vma->vm_end = STACK_TOP_MAX;
242 vma->vm_start = vma->vm_end - PAGE_SIZE;
243
244 vma->vm_flags = VM_STACK_FLAGS;
245 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
246 err = insert_vm_struct(mm, vma);
247 if (err) {
248 up_write(&mm->mmap_sem);
249 goto err;
250 }
251
252 mm->stack_vm = mm->total_vm = 1;
253 up_write(&mm->mmap_sem);
254
255 bprm->p = vma->vm_end - sizeof(void *);
256
257 return 0;
258
259err:
260 if (vma) {
261 bprm->vma = NULL;
262 kmem_cache_free(vm_area_cachep, vma);
263 }
264
265 return err;
266}
267
268static bool valid_arg_len(struct linux_binprm *bprm, long len)
269{
270 return len <= MAX_ARG_STRLEN;
271}
272
273#else
274
275static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
276 int write)
277{
278 struct page *page;
279
280 page = bprm->page[pos / PAGE_SIZE];
281 if (!page && write) {
282 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
283 if (!page)
284 return NULL;
285 bprm->page[pos / PAGE_SIZE] = page;
286 }
287
288 return page;
289}
290
291static void put_arg_page(struct page *page)
292{
293}
294
295static void free_arg_page(struct linux_binprm *bprm, int i)
296{
297 if (bprm->page[i]) {
298 __free_page(bprm->page[i]);
299 bprm->page[i] = NULL;
300 }
301}
302
303static void free_arg_pages(struct linux_binprm *bprm)
304{
305 int i;
306
307 for (i = 0; i < MAX_ARG_PAGES; i++)
308 free_arg_page(bprm, i);
309}
310
311static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
312 struct page *page)
313{
314}
315
316static int __bprm_mm_init(struct linux_binprm *bprm)
317{
318 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
319 return 0;
320}
321
322static bool valid_arg_len(struct linux_binprm *bprm, long len)
323{
324 return len <= bprm->p;
325}
326
327#endif /* CONFIG_MMU */
328
329/*
330 * Create a new mm_struct and populate it with a temporary stack
331 * vm_area_struct. We don't have enough context at this point to set the stack
332 * flags, permissions, and offset, so we use temporary values. We'll update
333 * them later in setup_arg_pages().
334 */
335int bprm_mm_init(struct linux_binprm *bprm)
336{
337 int err;
338 struct mm_struct *mm = NULL;
339
340 bprm->mm = mm = mm_alloc();
341 err = -ENOMEM;
342 if (!mm)
343 goto err;
344
345 err = init_new_context(current, mm);
346 if (err)
347 goto err;
348
349 err = __bprm_mm_init(bprm);
350 if (err)
351 goto err;
352
353 return 0;
354
355err:
356 if (mm) {
357 bprm->mm = NULL;
358 mmdrop(mm);
359 }
360
361 return err;
362}
363
364/*
365 * count() counts the number of strings in array ARGV.
366 */
367static int count(char __user * __user * argv, int max)
368{
369 int i = 0;
370
371 if (argv != NULL) {
372 for (;;) {
373 char __user * p;
374
375 if (get_user(p, argv))
376 return -EFAULT;
377 if (!p)
378 break;
379 argv++;
380 if(++i > max)
381 return -E2BIG;
382 cond_resched();
383 }
384 }
385 return i;
386}
387
388/*
389 * 'copy_strings()' copies argument/environment strings from the old
390 * processes's memory to the new process's stack. The call to get_user_pages()
391 * ensures the destination page is created and not swapped out.
392 */
393static int copy_strings(int argc, char __user * __user * argv,
394 struct linux_binprm *bprm)
395{
396 struct page *kmapped_page = NULL;
397 char *kaddr = NULL;
398 unsigned long kpos = 0;
399 int ret;
400
401 while (argc-- > 0) {
402 char __user *str;
403 int len;
404 unsigned long pos;
405
406 if (get_user(str, argv+argc) ||
407 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
408 ret = -EFAULT;
409 goto out;
410 }
411
412 if (!valid_arg_len(bprm, len)) {
413 ret = -E2BIG;
414 goto out;
415 }
416
417 /* We're going to work our way backwords. */
418 pos = bprm->p;
419 str += len;
420 bprm->p -= len;
421
422 while (len > 0) {
423 int offset, bytes_to_copy;
424
425 offset = pos % PAGE_SIZE;
426 if (offset == 0)
427 offset = PAGE_SIZE;
428
429 bytes_to_copy = offset;
430 if (bytes_to_copy > len)
431 bytes_to_copy = len;
432
433 offset -= bytes_to_copy;
434 pos -= bytes_to_copy;
435 str -= bytes_to_copy;
436 len -= bytes_to_copy;
437
438 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
439 struct page *page;
440
441 page = get_arg_page(bprm, pos, 1);
442 if (!page) {
443 ret = -E2BIG;
444 goto out;
445 }
446
447 if (kmapped_page) {
448 flush_kernel_dcache_page(kmapped_page);
449 kunmap(kmapped_page);
450 put_arg_page(kmapped_page);
451 }
452 kmapped_page = page;
453 kaddr = kmap(kmapped_page);
454 kpos = pos & PAGE_MASK;
455 flush_arg_page(bprm, kpos, kmapped_page);
456 }
457 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
458 ret = -EFAULT;
459 goto out;
460 }
461 }
462 }
463 ret = 0;
464out:
465 if (kmapped_page) {
466 flush_kernel_dcache_page(kmapped_page);
467 kunmap(kmapped_page);
468 put_arg_page(kmapped_page);
469 }
470 return ret;
471}
472
473/*
474 * Like copy_strings, but get argv and its values from kernel memory.
475 */
476int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
477{
478 int r;
479 mm_segment_t oldfs = get_fs();
480 set_fs(KERNEL_DS);
481 r = copy_strings(argc, (char __user * __user *)argv, bprm);
482 set_fs(oldfs);
483 return r;
484}
485EXPORT_SYMBOL(copy_strings_kernel);
486
487#ifdef CONFIG_MMU
488
489/*
490 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
491 * the binfmt code determines where the new stack should reside, we shift it to
492 * its final location. The process proceeds as follows:
493 *
494 * 1) Use shift to calculate the new vma endpoints.
495 * 2) Extend vma to cover both the old and new ranges. This ensures the
496 * arguments passed to subsequent functions are consistent.
497 * 3) Move vma's page tables to the new range.
498 * 4) Free up any cleared pgd range.
499 * 5) Shrink the vma to cover only the new range.
500 */
501static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
502{
503 struct mm_struct *mm = vma->vm_mm;
504 unsigned long old_start = vma->vm_start;
505 unsigned long old_end = vma->vm_end;
506 unsigned long length = old_end - old_start;
507 unsigned long new_start = old_start - shift;
508 unsigned long new_end = old_end - shift;
509 struct mmu_gather *tlb;
510
511 BUG_ON(new_start > new_end);
512
513 /*
514 * ensure there are no vmas between where we want to go
515 * and where we are
516 */
517 if (vma != find_vma(mm, new_start))
518 return -EFAULT;
519
520 /*
521 * cover the whole range: [new_start, old_end)
522 */
523 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
524
525 /*
526 * move the page tables downwards, on failure we rely on
527 * process cleanup to remove whatever mess we made.
528 */
529 if (length != move_page_tables(vma, old_start,
530 vma, new_start, length))
531 return -ENOMEM;
532
533 lru_add_drain();
534 tlb = tlb_gather_mmu(mm, 0);
535 if (new_end > old_start) {
536 /*
537 * when the old and new regions overlap clear from new_end.
538 */
539 free_pgd_range(&tlb, new_end, old_end, new_end,
540 vma->vm_next ? vma->vm_next->vm_start : 0);
541 } else {
542 /*
543 * otherwise, clean from old_start; this is done to not touch
544 * the address space in [new_end, old_start) some architectures
545 * have constraints on va-space that make this illegal (IA64) -
546 * for the others its just a little faster.
547 */
548 free_pgd_range(&tlb, old_start, old_end, new_end,
549 vma->vm_next ? vma->vm_next->vm_start : 0);
550 }
551 tlb_finish_mmu(tlb, new_end, old_end);
552
553 /*
554 * shrink the vma to just the new range.
555 */
556 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
557
558 return 0;
559}
560
561#define EXTRA_STACK_VM_PAGES 20 /* random */
562
563/*
564 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
565 * the stack is optionally relocated, and some extra space is added.
566 */
567int setup_arg_pages(struct linux_binprm *bprm,
568 unsigned long stack_top,
569 int executable_stack)
570{
571 unsigned long ret;
572 unsigned long stack_shift;
573 struct mm_struct *mm = current->mm;
574 struct vm_area_struct *vma = bprm->vma;
575 struct vm_area_struct *prev = NULL;
576 unsigned long vm_flags;
577 unsigned long stack_base;
578
579#ifdef CONFIG_STACK_GROWSUP
580 /* Limit stack size to 1GB */
581 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
582 if (stack_base > (1 << 30))
583 stack_base = 1 << 30;
584
585 /* Make sure we didn't let the argument array grow too large. */
586 if (vma->vm_end - vma->vm_start > stack_base)
587 return -ENOMEM;
588
589 stack_base = PAGE_ALIGN(stack_top - stack_base);
590
591 stack_shift = vma->vm_start - stack_base;
592 mm->arg_start = bprm->p - stack_shift;
593 bprm->p = vma->vm_end - stack_shift;
594#else
595 stack_top = arch_align_stack(stack_top);
596 stack_top = PAGE_ALIGN(stack_top);
597 stack_shift = vma->vm_end - stack_top;
598
599 bprm->p -= stack_shift;
600 mm->arg_start = bprm->p;
601#endif
602
603 if (bprm->loader)
604 bprm->loader -= stack_shift;
605 bprm->exec -= stack_shift;
606
607 down_write(&mm->mmap_sem);
608 vm_flags = vma->vm_flags;
609
610 /*
611 * Adjust stack execute permissions; explicitly enable for
612 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
613 * (arch default) otherwise.
614 */
615 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
616 vm_flags |= VM_EXEC;
617 else if (executable_stack == EXSTACK_DISABLE_X)
618 vm_flags &= ~VM_EXEC;
619 vm_flags |= mm->def_flags;
620
621 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
622 vm_flags);
623 if (ret)
624 goto out_unlock;
625 BUG_ON(prev != vma);
626
627 /* Move stack pages down in memory. */
628 if (stack_shift) {
629 ret = shift_arg_pages(vma, stack_shift);
630 if (ret) {
631 up_write(&mm->mmap_sem);
632 return ret;
633 }
634 }
635
636#ifdef CONFIG_STACK_GROWSUP
637 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
638#else
639 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
640#endif
641 ret = expand_stack(vma, stack_base);
642 if (ret)
643 ret = -EFAULT;
644
645out_unlock:
646 up_write(&mm->mmap_sem);
647 return 0;
648}
649EXPORT_SYMBOL(setup_arg_pages);
650
651#endif /* CONFIG_MMU */
652
653struct file *open_exec(const char *name)
654{
655 struct nameidata nd;
656 int err;
657 struct file *file;
658
659 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
660 file = ERR_PTR(err);
661
662 if (!err) {
663 struct inode *inode = nd.path.dentry->d_inode;
664 file = ERR_PTR(-EACCES);
665 if (S_ISREG(inode->i_mode)) {
666 int err = vfs_permission(&nd, MAY_EXEC);
667 file = ERR_PTR(err);
668 if (!err) {
669 file = nameidata_to_filp(&nd,
670 O_RDONLY|O_LARGEFILE);
671 if (!IS_ERR(file)) {
672 err = deny_write_access(file);
673 if (err) {
674 fput(file);
675 file = ERR_PTR(err);
676 }
677 }
678out:
679 return file;
680 }
681 }
682 release_open_intent(&nd);
683 path_put(&nd.path);
684 }
685 goto out;
686}
687
688EXPORT_SYMBOL(open_exec);
689
690int kernel_read(struct file *file, unsigned long offset,
691 char *addr, unsigned long count)
692{
693 mm_segment_t old_fs;
694 loff_t pos = offset;
695 int result;
696
697 old_fs = get_fs();
698 set_fs(get_ds());
699 /* The cast to a user pointer is valid due to the set_fs() */
700 result = vfs_read(file, (void __user *)addr, count, &pos);
701 set_fs(old_fs);
702 return result;
703}
704
705EXPORT_SYMBOL(kernel_read);
706
707static int exec_mmap(struct mm_struct *mm)
708{
709 struct task_struct *tsk;
710 struct mm_struct * old_mm, *active_mm;
711
712 /* Notify parent that we're no longer interested in the old VM */
713 tsk = current;
714 old_mm = current->mm;
715 mm_release(tsk, old_mm);
716
717 if (old_mm) {
718 /*
719 * Make sure that if there is a core dump in progress
720 * for the old mm, we get out and die instead of going
721 * through with the exec. We must hold mmap_sem around
722 * checking core_waiters and changing tsk->mm. The
723 * core-inducing thread will increment core_waiters for
724 * each thread whose ->mm == old_mm.
725 */
726 down_read(&old_mm->mmap_sem);
727 if (unlikely(old_mm->core_waiters)) {
728 up_read(&old_mm->mmap_sem);
729 return -EINTR;
730 }
731 }
732 task_lock(tsk);
733 active_mm = tsk->active_mm;
734 tsk->mm = mm;
735 tsk->active_mm = mm;
736 activate_mm(active_mm, mm);
737 task_unlock(tsk);
738 arch_pick_mmap_layout(mm);
739 if (old_mm) {
740 up_read(&old_mm->mmap_sem);
741 BUG_ON(active_mm != old_mm);
742 mmput(old_mm);
743 return 0;
744 }
745 mmdrop(active_mm);
746 return 0;
747}
748
749/*
750 * This function makes sure the current process has its own signal table,
751 * so that flush_signal_handlers can later reset the handlers without
752 * disturbing other processes. (Other processes might share the signal
753 * table via the CLONE_SIGHAND option to clone().)
754 */
755static int de_thread(struct task_struct *tsk)
756{
757 struct signal_struct *sig = tsk->signal;
758 struct sighand_struct *oldsighand = tsk->sighand;
759 spinlock_t *lock = &oldsighand->siglock;
760 struct task_struct *leader = NULL;
761 int count;
762
763 if (thread_group_empty(tsk))
764 goto no_thread_group;
765
766 /*
767 * Kill all other threads in the thread group.
768 * We must hold tasklist_lock to call zap_other_threads.
769 */
770 read_lock(&tasklist_lock);
771 spin_lock_irq(lock);
772 if (signal_group_exit(sig)) {
773 /*
774 * Another group action in progress, just
775 * return so that the signal is processed.
776 */
777 spin_unlock_irq(lock);
778 read_unlock(&tasklist_lock);
779 return -EAGAIN;
780 }
781
782 /*
783 * child_reaper ignores SIGKILL, change it now.
784 * Reparenting needs write_lock on tasklist_lock,
785 * so it is safe to do it under read_lock.
786 */
787 if (unlikely(tsk->group_leader == task_child_reaper(tsk)))
788 task_active_pid_ns(tsk)->child_reaper = tsk;
789
790 sig->group_exit_task = tsk;
791 zap_other_threads(tsk);
792 read_unlock(&tasklist_lock);
793
794 /* Account for the thread group leader hanging around: */
795 count = thread_group_leader(tsk) ? 1 : 2;
796 sig->notify_count = count;
797 while (atomic_read(&sig->count) > count) {
798 __set_current_state(TASK_UNINTERRUPTIBLE);
799 spin_unlock_irq(lock);
800 schedule();
801 spin_lock_irq(lock);
802 }
803 spin_unlock_irq(lock);
804
805 /*
806 * At this point all other threads have exited, all we have to
807 * do is to wait for the thread group leader to become inactive,
808 * and to assume its PID:
809 */
810 if (!thread_group_leader(tsk)) {
811 leader = tsk->group_leader;
812
813 sig->notify_count = -1;
814 for (;;) {
815 write_lock_irq(&tasklist_lock);
816 if (likely(leader->exit_state))
817 break;
818 __set_current_state(TASK_UNINTERRUPTIBLE);
819 write_unlock_irq(&tasklist_lock);
820 schedule();
821 }
822
823 /*
824 * The only record we have of the real-time age of a
825 * process, regardless of execs it's done, is start_time.
826 * All the past CPU time is accumulated in signal_struct
827 * from sister threads now dead. But in this non-leader
828 * exec, nothing survives from the original leader thread,
829 * whose birth marks the true age of this process now.
830 * When we take on its identity by switching to its PID, we
831 * also take its birthdate (always earlier than our own).
832 */
833 tsk->start_time = leader->start_time;
834
835 BUG_ON(!same_thread_group(leader, tsk));
836 BUG_ON(has_group_leader_pid(tsk));
837 /*
838 * An exec() starts a new thread group with the
839 * TGID of the previous thread group. Rehash the
840 * two threads with a switched PID, and release
841 * the former thread group leader:
842 */
843
844 /* Become a process group leader with the old leader's pid.
845 * The old leader becomes a thread of the this thread group.
846 * Note: The old leader also uses this pid until release_task
847 * is called. Odd but simple and correct.
848 */
849 detach_pid(tsk, PIDTYPE_PID);
850 tsk->pid = leader->pid;
851 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
852 transfer_pid(leader, tsk, PIDTYPE_PGID);
853 transfer_pid(leader, tsk, PIDTYPE_SID);
854 list_replace_rcu(&leader->tasks, &tsk->tasks);
855
856 tsk->group_leader = tsk;
857 leader->group_leader = tsk;
858
859 tsk->exit_signal = SIGCHLD;
860
861 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
862 leader->exit_state = EXIT_DEAD;
863
864 write_unlock_irq(&tasklist_lock);
865 }
866
867 sig->group_exit_task = NULL;
868 sig->notify_count = 0;
869
870no_thread_group:
871 exit_itimers(sig);
872 if (leader)
873 release_task(leader);
874
875 if (atomic_read(&oldsighand->count) != 1) {
876 struct sighand_struct *newsighand;
877 /*
878 * This ->sighand is shared with the CLONE_SIGHAND
879 * but not CLONE_THREAD task, switch to the new one.
880 */
881 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
882 if (!newsighand)
883 return -ENOMEM;
884
885 atomic_set(&newsighand->count, 1);
886 memcpy(newsighand->action, oldsighand->action,
887 sizeof(newsighand->action));
888
889 write_lock_irq(&tasklist_lock);
890 spin_lock(&oldsighand->siglock);
891 rcu_assign_pointer(tsk->sighand, newsighand);
892 spin_unlock(&oldsighand->siglock);
893 write_unlock_irq(&tasklist_lock);
894
895 __cleanup_sighand(oldsighand);
896 }
897
898 BUG_ON(!thread_group_leader(tsk));
899 return 0;
900}
901
902/*
903 * These functions flushes out all traces of the currently running executable
904 * so that a new one can be started
905 */
906static void flush_old_files(struct files_struct * files)
907{
908 long j = -1;
909 struct fdtable *fdt;
910
911 spin_lock(&files->file_lock);
912 for (;;) {
913 unsigned long set, i;
914
915 j++;
916 i = j * __NFDBITS;
917 fdt = files_fdtable(files);
918 if (i >= fdt->max_fds)
919 break;
920 set = fdt->close_on_exec->fds_bits[j];
921 if (!set)
922 continue;
923 fdt->close_on_exec->fds_bits[j] = 0;
924 spin_unlock(&files->file_lock);
925 for ( ; set ; i++,set >>= 1) {
926 if (set & 1) {
927 sys_close(i);
928 }
929 }
930 spin_lock(&files->file_lock);
931
932 }
933 spin_unlock(&files->file_lock);
934}
935
936char *get_task_comm(char *buf, struct task_struct *tsk)
937{
938 /* buf must be at least sizeof(tsk->comm) in size */
939 task_lock(tsk);
940 strncpy(buf, tsk->comm, sizeof(tsk->comm));
941 task_unlock(tsk);
942 return buf;
943}
944
945void set_task_comm(struct task_struct *tsk, char *buf)
946{
947 task_lock(tsk);
948 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
949 task_unlock(tsk);
950}
951
952int flush_old_exec(struct linux_binprm * bprm)
953{
954 char * name;
955 int i, ch, retval;
956 struct files_struct *files;
957 char tcomm[sizeof(current->comm)];
958
959 /*
960 * Make sure we have a private signal table and that
961 * we are unassociated from the previous thread group.
962 */
963 retval = de_thread(current);
964 if (retval)
965 goto out;
966
967 /*
968 * Make sure we have private file handles. Ask the
969 * fork helper to do the work for us and the exit
970 * helper to do the cleanup of the old one.
971 */
972 files = current->files; /* refcounted so safe to hold */
973 retval = unshare_files();
974 if (retval)
975 goto out;
976 /*
977 * Release all of the old mmap stuff
978 */
979 retval = exec_mmap(bprm->mm);
980 if (retval)
981 goto mmap_failed;
982
983 bprm->mm = NULL; /* We're using it now */
984
985 /* This is the point of no return */
986 put_files_struct(files);
987
988 current->sas_ss_sp = current->sas_ss_size = 0;
989
990 if (current->euid == current->uid && current->egid == current->gid)
991 set_dumpable(current->mm, 1);
992 else
993 set_dumpable(current->mm, suid_dumpable);
994
995 name = bprm->filename;
996
997 /* Copies the binary name from after last slash */
998 for (i=0; (ch = *(name++)) != '\0';) {
999 if (ch == '/')
1000 i = 0; /* overwrite what we wrote */
1001 else
1002 if (i < (sizeof(tcomm) - 1))
1003 tcomm[i++] = ch;
1004 }
1005 tcomm[i] = '\0';
1006 set_task_comm(current, tcomm);
1007
1008 current->flags &= ~PF_RANDOMIZE;
1009 flush_thread();
1010
1011 /* Set the new mm task size. We have to do that late because it may
1012 * depend on TIF_32BIT which is only updated in flush_thread() on
1013 * some architectures like powerpc
1014 */
1015 current->mm->task_size = TASK_SIZE;
1016
1017 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1018 suid_keys(current);
1019 set_dumpable(current->mm, suid_dumpable);
1020 current->pdeath_signal = 0;
1021 } else if (file_permission(bprm->file, MAY_READ) ||
1022 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1023 suid_keys(current);
1024 set_dumpable(current->mm, suid_dumpable);
1025 }
1026
1027 /* An exec changes our domain. We are no longer part of the thread
1028 group */
1029
1030 current->self_exec_id++;
1031
1032 flush_signal_handlers(current, 0);
1033 flush_old_files(current->files);
1034
1035 return 0;
1036
1037mmap_failed:
1038 reset_files_struct(current, files);
1039out:
1040 return retval;
1041}
1042
1043EXPORT_SYMBOL(flush_old_exec);
1044
1045/*
1046 * Fill the binprm structure from the inode.
1047 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1048 */
1049int prepare_binprm(struct linux_binprm *bprm)
1050{
1051 int mode;
1052 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1053 int retval;
1054
1055 mode = inode->i_mode;
1056 if (bprm->file->f_op == NULL)
1057 return -EACCES;
1058
1059 bprm->e_uid = current->euid;
1060 bprm->e_gid = current->egid;
1061
1062 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1063 /* Set-uid? */
1064 if (mode & S_ISUID) {
1065 current->personality &= ~PER_CLEAR_ON_SETID;
1066 bprm->e_uid = inode->i_uid;
1067 }
1068
1069 /* Set-gid? */
1070 /*
1071 * If setgid is set but no group execute bit then this
1072 * is a candidate for mandatory locking, not a setgid
1073 * executable.
1074 */
1075 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1076 current->personality &= ~PER_CLEAR_ON_SETID;
1077 bprm->e_gid = inode->i_gid;
1078 }
1079 }
1080
1081 /* fill in binprm security blob */
1082 retval = security_bprm_set(bprm);
1083 if (retval)
1084 return retval;
1085
1086 memset(bprm->buf,0,BINPRM_BUF_SIZE);
1087 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1088}
1089
1090EXPORT_SYMBOL(prepare_binprm);
1091
1092static int unsafe_exec(struct task_struct *p)
1093{
1094 int unsafe = 0;
1095 if (p->ptrace & PT_PTRACED) {
1096 if (p->ptrace & PT_PTRACE_CAP)
1097 unsafe |= LSM_UNSAFE_PTRACE_CAP;
1098 else
1099 unsafe |= LSM_UNSAFE_PTRACE;
1100 }
1101 if (atomic_read(&p->fs->count) > 1 ||
1102 atomic_read(&p->files->count) > 1 ||
1103 atomic_read(&p->sighand->count) > 1)
1104 unsafe |= LSM_UNSAFE_SHARE;
1105
1106 return unsafe;
1107}
1108
1109void compute_creds(struct linux_binprm *bprm)
1110{
1111 int unsafe;
1112
1113 if (bprm->e_uid != current->uid) {
1114 suid_keys(current);
1115 current->pdeath_signal = 0;
1116 }
1117 exec_keys(current);
1118
1119 task_lock(current);
1120 unsafe = unsafe_exec(current);
1121 security_bprm_apply_creds(bprm, unsafe);
1122 task_unlock(current);
1123 security_bprm_post_apply_creds(bprm);
1124}
1125EXPORT_SYMBOL(compute_creds);
1126
1127/*
1128 * Arguments are '\0' separated strings found at the location bprm->p
1129 * points to; chop off the first by relocating brpm->p to right after
1130 * the first '\0' encountered.
1131 */
1132int remove_arg_zero(struct linux_binprm *bprm)
1133{
1134 int ret = 0;
1135 unsigned long offset;
1136 char *kaddr;
1137 struct page *page;
1138
1139 if (!bprm->argc)
1140 return 0;
1141
1142 do {
1143 offset = bprm->p & ~PAGE_MASK;
1144 page = get_arg_page(bprm, bprm->p, 0);
1145 if (!page) {
1146 ret = -EFAULT;
1147 goto out;
1148 }
1149 kaddr = kmap_atomic(page, KM_USER0);
1150
1151 for (; offset < PAGE_SIZE && kaddr[offset];
1152 offset++, bprm->p++)
1153 ;
1154
1155 kunmap_atomic(kaddr, KM_USER0);
1156 put_arg_page(page);
1157
1158 if (offset == PAGE_SIZE)
1159 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1160 } while (offset == PAGE_SIZE);
1161
1162 bprm->p++;
1163 bprm->argc--;
1164 ret = 0;
1165
1166out:
1167 return ret;
1168}
1169EXPORT_SYMBOL(remove_arg_zero);
1170
1171/*
1172 * cycle the list of binary formats handler, until one recognizes the image
1173 */
1174int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1175{
1176 int try,retval;
1177 struct linux_binfmt *fmt;
1178#if defined(__alpha__) && defined(CONFIG_ARCH_SUPPORTS_AOUT)
1179 /* handle /sbin/loader.. */
1180 {
1181 struct exec * eh = (struct exec *) bprm->buf;
1182
1183 if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1184 (eh->fh.f_flags & 0x3000) == 0x3000)
1185 {
1186 struct file * file;
1187 unsigned long loader;
1188
1189 allow_write_access(bprm->file);
1190 fput(bprm->file);
1191 bprm->file = NULL;
1192
1193 loader = bprm->vma->vm_end - sizeof(void *);
1194
1195 file = open_exec("/sbin/loader");
1196 retval = PTR_ERR(file);
1197 if (IS_ERR(file))
1198 return retval;
1199
1200 /* Remember if the application is TASO. */
1201 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1202
1203 bprm->file = file;
1204 bprm->loader = loader;
1205 retval = prepare_binprm(bprm);
1206 if (retval<0)
1207 return retval;
1208 /* should call search_binary_handler recursively here,
1209 but it does not matter */
1210 }
1211 }
1212#endif
1213 retval = security_bprm_check(bprm);
1214 if (retval)
1215 return retval;
1216
1217 /* kernel module loader fixup */
1218 /* so we don't try to load run modprobe in kernel space. */
1219 set_fs(USER_DS);
1220
1221 retval = audit_bprm(bprm);
1222 if (retval)
1223 return retval;
1224
1225 retval = -ENOENT;
1226 for (try=0; try<2; try++) {
1227 read_lock(&binfmt_lock);
1228 list_for_each_entry(fmt, &formats, lh) {
1229 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1230 if (!fn)
1231 continue;
1232 if (!try_module_get(fmt->module))
1233 continue;
1234 read_unlock(&binfmt_lock);
1235 retval = fn(bprm, regs);
1236 if (retval >= 0) {
1237 put_binfmt(fmt);
1238 allow_write_access(bprm->file);
1239 if (bprm->file)
1240 fput(bprm->file);
1241 bprm->file = NULL;
1242 current->did_exec = 1;
1243 proc_exec_connector(current);
1244 return retval;
1245 }
1246 read_lock(&binfmt_lock);
1247 put_binfmt(fmt);
1248 if (retval != -ENOEXEC || bprm->mm == NULL)
1249 break;
1250 if (!bprm->file) {
1251 read_unlock(&binfmt_lock);
1252 return retval;
1253 }
1254 }
1255 read_unlock(&binfmt_lock);
1256 if (retval != -ENOEXEC || bprm->mm == NULL) {
1257 break;
1258#ifdef CONFIG_KMOD
1259 }else{
1260#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1261 if (printable(bprm->buf[0]) &&
1262 printable(bprm->buf[1]) &&
1263 printable(bprm->buf[2]) &&
1264 printable(bprm->buf[3]))
1265 break; /* -ENOEXEC */
1266 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1267#endif
1268 }
1269 }
1270 return retval;
1271}
1272
1273EXPORT_SYMBOL(search_binary_handler);
1274
1275/*
1276 * sys_execve() executes a new program.
1277 */
1278int do_execve(char * filename,
1279 char __user *__user *argv,
1280 char __user *__user *envp,
1281 struct pt_regs * regs)
1282{
1283 struct linux_binprm *bprm;
1284 struct file *file;
1285 unsigned long env_p;
1286 int retval;
1287
1288 retval = -ENOMEM;
1289 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1290 if (!bprm)
1291 goto out_ret;
1292
1293 file = open_exec(filename);
1294 retval = PTR_ERR(file);
1295 if (IS_ERR(file))
1296 goto out_kfree;
1297
1298 sched_exec();
1299
1300 bprm->file = file;
1301 bprm->filename = filename;
1302 bprm->interp = filename;
1303
1304 retval = bprm_mm_init(bprm);
1305 if (retval)
1306 goto out_file;
1307
1308 bprm->argc = count(argv, MAX_ARG_STRINGS);
1309 if ((retval = bprm->argc) < 0)
1310 goto out_mm;
1311
1312 bprm->envc = count(envp, MAX_ARG_STRINGS);
1313 if ((retval = bprm->envc) < 0)
1314 goto out_mm;
1315
1316 retval = security_bprm_alloc(bprm);
1317 if (retval)
1318 goto out;
1319
1320 retval = prepare_binprm(bprm);
1321 if (retval < 0)
1322 goto out;
1323
1324 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1325 if (retval < 0)
1326 goto out;
1327
1328 bprm->exec = bprm->p;
1329 retval = copy_strings(bprm->envc, envp, bprm);
1330 if (retval < 0)
1331 goto out;
1332
1333 env_p = bprm->p;
1334 retval = copy_strings(bprm->argc, argv, bprm);
1335 if (retval < 0)
1336 goto out;
1337 bprm->argv_len = env_p - bprm->p;
1338
1339 retval = search_binary_handler(bprm,regs);
1340 if (retval >= 0) {
1341 /* execve success */
1342 free_arg_pages(bprm);
1343 security_bprm_free(bprm);
1344 acct_update_integrals(current);
1345 kfree(bprm);
1346 return retval;
1347 }
1348
1349out:
1350 free_arg_pages(bprm);
1351 if (bprm->security)
1352 security_bprm_free(bprm);
1353
1354out_mm:
1355 if (bprm->mm)
1356 mmput (bprm->mm);
1357
1358out_file:
1359 if (bprm->file) {
1360 allow_write_access(bprm->file);
1361 fput(bprm->file);
1362 }
1363out_kfree:
1364 kfree(bprm);
1365
1366out_ret:
1367 return retval;
1368}
1369
1370int set_binfmt(struct linux_binfmt *new)
1371{
1372 struct linux_binfmt *old = current->binfmt;
1373
1374 if (new) {
1375 if (!try_module_get(new->module))
1376 return -1;
1377 }
1378 current->binfmt = new;
1379 if (old)
1380 module_put(old->module);
1381 return 0;
1382}
1383
1384EXPORT_SYMBOL(set_binfmt);
1385
1386/* format_corename will inspect the pattern parameter, and output a
1387 * name into corename, which must have space for at least
1388 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1389 */
1390static int format_corename(char *corename, const char *pattern, long signr)
1391{
1392 const char *pat_ptr = pattern;
1393 char *out_ptr = corename;
1394 char *const out_end = corename + CORENAME_MAX_SIZE;
1395 int rc;
1396 int pid_in_pattern = 0;
1397 int ispipe = 0;
1398
1399 if (*pattern == '|')
1400 ispipe = 1;
1401
1402 /* Repeat as long as we have more pattern to process and more output
1403 space */
1404 while (*pat_ptr) {
1405 if (*pat_ptr != '%') {
1406 if (out_ptr == out_end)
1407 goto out;
1408 *out_ptr++ = *pat_ptr++;
1409 } else {
1410 switch (*++pat_ptr) {
1411 case 0:
1412 goto out;
1413 /* Double percent, output one percent */
1414 case '%':
1415 if (out_ptr == out_end)
1416 goto out;
1417 *out_ptr++ = '%';
1418 break;
1419 /* pid */
1420 case 'p':
1421 pid_in_pattern = 1;
1422 rc = snprintf(out_ptr, out_end - out_ptr,
1423 "%d", task_tgid_vnr(current));
1424 if (rc > out_end - out_ptr)
1425 goto out;
1426 out_ptr += rc;
1427 break;
1428 /* uid */
1429 case 'u':
1430 rc = snprintf(out_ptr, out_end - out_ptr,
1431 "%d", current->uid);
1432 if (rc > out_end - out_ptr)
1433 goto out;
1434 out_ptr += rc;
1435 break;
1436 /* gid */
1437 case 'g':
1438 rc = snprintf(out_ptr, out_end - out_ptr,
1439 "%d", current->gid);
1440 if (rc > out_end - out_ptr)
1441 goto out;
1442 out_ptr += rc;
1443 break;
1444 /* signal that caused the coredump */
1445 case 's':
1446 rc = snprintf(out_ptr, out_end - out_ptr,
1447 "%ld", signr);
1448 if (rc > out_end - out_ptr)
1449 goto out;
1450 out_ptr += rc;
1451 break;
1452 /* UNIX time of coredump */
1453 case 't': {
1454 struct timeval tv;
1455 do_gettimeofday(&tv);
1456 rc = snprintf(out_ptr, out_end - out_ptr,
1457 "%lu", tv.tv_sec);
1458 if (rc > out_end - out_ptr)
1459 goto out;
1460 out_ptr += rc;
1461 break;
1462 }
1463 /* hostname */
1464 case 'h':
1465 down_read(&uts_sem);
1466 rc = snprintf(out_ptr, out_end - out_ptr,
1467 "%s", utsname()->nodename);
1468 up_read(&uts_sem);
1469 if (rc > out_end - out_ptr)
1470 goto out;
1471 out_ptr += rc;
1472 break;
1473 /* executable */
1474 case 'e':
1475 rc = snprintf(out_ptr, out_end - out_ptr,
1476 "%s", current->comm);
1477 if (rc > out_end - out_ptr)
1478 goto out;
1479 out_ptr += rc;
1480 break;
1481 /* core limit size */
1482 case 'c':
1483 rc = snprintf(out_ptr, out_end - out_ptr,
1484 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1485 if (rc > out_end - out_ptr)
1486 goto out;
1487 out_ptr += rc;
1488 break;
1489 default:
1490 break;
1491 }
1492 ++pat_ptr;
1493 }
1494 }
1495 /* Backward compatibility with core_uses_pid:
1496 *
1497 * If core_pattern does not include a %p (as is the default)
1498 * and core_uses_pid is set, then .%pid will be appended to
1499 * the filename. Do not do this for piped commands. */
1500 if (!ispipe && !pid_in_pattern
1501 && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1502 rc = snprintf(out_ptr, out_end - out_ptr,
1503 ".%d", task_tgid_vnr(current));
1504 if (rc > out_end - out_ptr)
1505 goto out;
1506 out_ptr += rc;
1507 }
1508out:
1509 *out_ptr = 0;
1510 return ispipe;
1511}
1512
1513static void zap_process(struct task_struct *start)
1514{
1515 struct task_struct *t;
1516
1517 start->signal->flags = SIGNAL_GROUP_EXIT;
1518 start->signal->group_stop_count = 0;
1519
1520 t = start;
1521 do {
1522 if (t != current && t->mm) {
1523 t->mm->core_waiters++;
1524 sigaddset(&t->pending.signal, SIGKILL);
1525 signal_wake_up(t, 1);
1526 }
1527 } while ((t = next_thread(t)) != start);
1528}
1529
1530static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1531 int exit_code)
1532{
1533 struct task_struct *g, *p;
1534 unsigned long flags;
1535 int err = -EAGAIN;
1536
1537 spin_lock_irq(&tsk->sighand->siglock);
1538 if (!signal_group_exit(tsk->signal)) {
1539 tsk->signal->group_exit_code = exit_code;
1540 zap_process(tsk);
1541 err = 0;
1542 }
1543 spin_unlock_irq(&tsk->sighand->siglock);
1544 if (err)
1545 return err;
1546
1547 if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1548 goto done;
1549
1550 rcu_read_lock();
1551 for_each_process(g) {
1552 if (g == tsk->group_leader)
1553 continue;
1554
1555 p = g;
1556 do {
1557 if (p->mm) {
1558 if (p->mm == mm) {
1559 /*
1560 * p->sighand can't disappear, but
1561 * may be changed by de_thread()
1562 */
1563 lock_task_sighand(p, &flags);
1564 zap_process(p);
1565 unlock_task_sighand(p, &flags);
1566 }
1567 break;
1568 }
1569 } while ((p = next_thread(p)) != g);
1570 }
1571 rcu_read_unlock();
1572done:
1573 return mm->core_waiters;
1574}
1575
1576static int coredump_wait(int exit_code)
1577{
1578 struct task_struct *tsk = current;
1579 struct mm_struct *mm = tsk->mm;
1580 struct completion startup_done;
1581 struct completion *vfork_done;
1582 int core_waiters;
1583
1584 init_completion(&mm->core_done);
1585 init_completion(&startup_done);
1586 mm->core_startup_done = &startup_done;
1587
1588 core_waiters = zap_threads(tsk, mm, exit_code);
1589 up_write(&mm->mmap_sem);
1590
1591 if (unlikely(core_waiters < 0))
1592 goto fail;
1593
1594 /*
1595 * Make sure nobody is waiting for us to release the VM,
1596 * otherwise we can deadlock when we wait on each other
1597 */
1598 vfork_done = tsk->vfork_done;
1599 if (vfork_done) {
1600 tsk->vfork_done = NULL;
1601 complete(vfork_done);
1602 }
1603
1604 if (core_waiters)
1605 wait_for_completion(&startup_done);
1606fail:
1607 BUG_ON(mm->core_waiters);
1608 return core_waiters;
1609}
1610
1611/*
1612 * set_dumpable converts traditional three-value dumpable to two flags and
1613 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1614 * these bits are not changed atomically. So get_dumpable can observe the
1615 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1616 * return either old dumpable or new one by paying attention to the order of
1617 * modifying the bits.
1618 *
1619 * dumpable | mm->flags (binary)
1620 * old new | initial interim final
1621 * ---------+-----------------------
1622 * 0 1 | 00 01 01
1623 * 0 2 | 00 10(*) 11
1624 * 1 0 | 01 00 00
1625 * 1 2 | 01 11 11
1626 * 2 0 | 11 10(*) 00
1627 * 2 1 | 11 11 01
1628 *
1629 * (*) get_dumpable regards interim value of 10 as 11.
1630 */
1631void set_dumpable(struct mm_struct *mm, int value)
1632{
1633 switch (value) {
1634 case 0:
1635 clear_bit(MMF_DUMPABLE, &mm->flags);
1636 smp_wmb();
1637 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1638 break;
1639 case 1:
1640 set_bit(MMF_DUMPABLE, &mm->flags);
1641 smp_wmb();
1642 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1643 break;
1644 case 2:
1645 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1646 smp_wmb();
1647 set_bit(MMF_DUMPABLE, &mm->flags);
1648 break;
1649 }
1650}
1651
1652int get_dumpable(struct mm_struct *mm)
1653{
1654 int ret;
1655
1656 ret = mm->flags & 0x3;
1657 return (ret >= 2) ? 2 : ret;
1658}
1659
1660int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1661{
1662 char corename[CORENAME_MAX_SIZE + 1];
1663 struct mm_struct *mm = current->mm;
1664 struct linux_binfmt * binfmt;
1665 struct inode * inode;
1666 struct file * file;
1667 int retval = 0;
1668 int fsuid = current->fsuid;
1669 int flag = 0;
1670 int ispipe = 0;
1671 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1672 char **helper_argv = NULL;
1673 int helper_argc = 0;
1674 char *delimit;
1675
1676 audit_core_dumps(signr);
1677
1678 binfmt = current->binfmt;
1679 if (!binfmt || !binfmt->core_dump)
1680 goto fail;
1681 down_write(&mm->mmap_sem);
1682 /*
1683 * If another thread got here first, or we are not dumpable, bail out.
1684 */
1685 if (mm->core_waiters || !get_dumpable(mm)) {
1686 up_write(&mm->mmap_sem);
1687 goto fail;
1688 }
1689
1690 /*
1691 * We cannot trust fsuid as being the "true" uid of the
1692 * process nor do we know its entire history. We only know it
1693 * was tainted so we dump it as root in mode 2.
1694 */
1695 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1696 flag = O_EXCL; /* Stop rewrite attacks */
1697 current->fsuid = 0; /* Dump root private */
1698 }
1699
1700 retval = coredump_wait(exit_code);
1701 if (retval < 0)
1702 goto fail;
1703
1704 /*
1705 * Clear any false indication of pending signals that might
1706 * be seen by the filesystem code called to write the core file.
1707 */
1708 clear_thread_flag(TIF_SIGPENDING);
1709
1710 /*
1711 * lock_kernel() because format_corename() is controlled by sysctl, which
1712 * uses lock_kernel()
1713 */
1714 lock_kernel();
1715 ispipe = format_corename(corename, core_pattern, signr);
1716 unlock_kernel();
1717 /*
1718 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1719 * to a pipe. Since we're not writing directly to the filesystem
1720 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1721 * created unless the pipe reader choses to write out the core file
1722 * at which point file size limits and permissions will be imposed
1723 * as it does with any other process
1724 */
1725 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1726 goto fail_unlock;
1727
1728 if (ispipe) {
1729 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1730 /* Terminate the string before the first option */
1731 delimit = strchr(corename, ' ');
1732 if (delimit)
1733 *delimit = '\0';
1734 delimit = strrchr(helper_argv[0], '/');
1735 if (delimit)
1736 delimit++;
1737 else
1738 delimit = helper_argv[0];
1739 if (!strcmp(delimit, current->comm)) {
1740 printk(KERN_NOTICE "Recursive core dump detected, "
1741 "aborting\n");
1742 goto fail_unlock;
1743 }
1744
1745 core_limit = RLIM_INFINITY;
1746
1747 /* SIGPIPE can happen, but it's just never processed */
1748 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1749 &file)) {
1750 printk(KERN_INFO "Core dump to %s pipe failed\n",
1751 corename);
1752 goto fail_unlock;
1753 }
1754 } else
1755 file = filp_open(corename,
1756 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1757 0600);
1758 if (IS_ERR(file))
1759 goto fail_unlock;
1760 inode = file->f_path.dentry->d_inode;
1761 if (inode->i_nlink > 1)
1762 goto close_fail; /* multiple links - don't dump */
1763 if (!ispipe && d_unhashed(file->f_path.dentry))
1764 goto close_fail;
1765
1766 /* AK: actually i see no reason to not allow this for named pipes etc.,
1767 but keep the previous behaviour for now. */
1768 if (!ispipe && !S_ISREG(inode->i_mode))
1769 goto close_fail;
1770 /*
1771 * Dont allow local users get cute and trick others to coredump
1772 * into their pre-created files:
1773 */
1774 if (inode->i_uid != current->fsuid)
1775 goto close_fail;
1776 if (!file->f_op)
1777 goto close_fail;
1778 if (!file->f_op->write)
1779 goto close_fail;
1780 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1781 goto close_fail;
1782
1783 retval = binfmt->core_dump(signr, regs, file, core_limit);
1784
1785 if (retval)
1786 current->signal->group_exit_code |= 0x80;
1787close_fail:
1788 filp_close(file, NULL);
1789fail_unlock:
1790 if (helper_argv)
1791 argv_free(helper_argv);
1792
1793 current->fsuid = fsuid;
1794 complete_all(&mm->core_done);
1795fail:
1796 return retval;
1797}