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core_pattern: fix up a few miscellaneous bugs
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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
63 int core_uses_pid;
64 char core_pattern[CORENAME_MAX_SIZE] = "core";
65 int suid_dumpable = 0;
66
67 EXPORT_SYMBOL(suid_dumpable);
68 /* The maximal length of core_pattern is also specified in sysctl.c */
69
70 static LIST_HEAD(formats);
71 static DEFINE_RWLOCK(binfmt_lock);
72
73 int register_binfmt(struct linux_binfmt * fmt)
74 {
75 if (!fmt)
76 return -EINVAL;
77 write_lock(&binfmt_lock);
78 list_add(&fmt->lh, &formats);
79 write_unlock(&binfmt_lock);
80 return 0;
81 }
82
83 EXPORT_SYMBOL(register_binfmt);
84
85 void unregister_binfmt(struct linux_binfmt * fmt)
86 {
87 write_lock(&binfmt_lock);
88 list_del(&fmt->lh);
89 write_unlock(&binfmt_lock);
90 }
91
92 EXPORT_SYMBOL(unregister_binfmt);
93
94 static inline void put_binfmt(struct linux_binfmt * fmt)
95 {
96 module_put(fmt->module);
97 }
98
99 /*
100 * Note that a shared library must be both readable and executable due to
101 * security reasons.
102 *
103 * Also note that we take the address to load from from the file itself.
104 */
105 asmlinkage long sys_uselib(const char __user * library)
106 {
107 struct file * file;
108 struct nameidata nd;
109 int error;
110
111 error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
112 if (error)
113 goto out;
114
115 error = -EACCES;
116 if (nd.mnt->mnt_flags & MNT_NOEXEC)
117 goto exit;
118 error = -EINVAL;
119 if (!S_ISREG(nd.dentry->d_inode->i_mode))
120 goto exit;
121
122 error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
123 if (error)
124 goto exit;
125
126 file = nameidata_to_filp(&nd, O_RDONLY);
127 error = PTR_ERR(file);
128 if (IS_ERR(file))
129 goto out;
130
131 error = -ENOEXEC;
132 if(file->f_op) {
133 struct linux_binfmt * fmt;
134
135 read_lock(&binfmt_lock);
136 list_for_each_entry(fmt, &formats, lh) {
137 if (!fmt->load_shlib)
138 continue;
139 if (!try_module_get(fmt->module))
140 continue;
141 read_unlock(&binfmt_lock);
142 error = fmt->load_shlib(file);
143 read_lock(&binfmt_lock);
144 put_binfmt(fmt);
145 if (error != -ENOEXEC)
146 break;
147 }
148 read_unlock(&binfmt_lock);
149 }
150 fput(file);
151 out:
152 return error;
153 exit:
154 release_open_intent(&nd);
155 path_release(&nd);
156 goto out;
157 }
158
159 #ifdef CONFIG_MMU
160
161 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
162 int write)
163 {
164 struct page *page;
165 int ret;
166
167 #ifdef CONFIG_STACK_GROWSUP
168 if (write) {
169 ret = expand_stack_downwards(bprm->vma, pos);
170 if (ret < 0)
171 return NULL;
172 }
173 #endif
174 ret = get_user_pages(current, bprm->mm, pos,
175 1, write, 1, &page, NULL);
176 if (ret <= 0)
177 return NULL;
178
179 if (write) {
180 struct rlimit *rlim = current->signal->rlim;
181 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
182
183 /*
184 * Limit to 1/4-th the stack size for the argv+env strings.
185 * This ensures that:
186 * - the remaining binfmt code will not run out of stack space,
187 * - the program will have a reasonable amount of stack left
188 * to work from.
189 */
190 if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
191 put_page(page);
192 return NULL;
193 }
194 }
195
196 return page;
197 }
198
199 static void put_arg_page(struct page *page)
200 {
201 put_page(page);
202 }
203
204 static void free_arg_page(struct linux_binprm *bprm, int i)
205 {
206 }
207
208 static void free_arg_pages(struct linux_binprm *bprm)
209 {
210 }
211
212 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
213 struct page *page)
214 {
215 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
216 }
217
218 static int __bprm_mm_init(struct linux_binprm *bprm)
219 {
220 int err = -ENOMEM;
221 struct vm_area_struct *vma = NULL;
222 struct mm_struct *mm = bprm->mm;
223
224 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
225 if (!vma)
226 goto err;
227
228 down_write(&mm->mmap_sem);
229 vma->vm_mm = mm;
230
231 /*
232 * Place the stack at the largest stack address the architecture
233 * supports. Later, we'll move this to an appropriate place. We don't
234 * use STACK_TOP because that can depend on attributes which aren't
235 * configured yet.
236 */
237 vma->vm_end = STACK_TOP_MAX;
238 vma->vm_start = vma->vm_end - PAGE_SIZE;
239
240 vma->vm_flags = VM_STACK_FLAGS;
241 vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
242 err = insert_vm_struct(mm, vma);
243 if (err) {
244 up_write(&mm->mmap_sem);
245 goto err;
246 }
247
248 mm->stack_vm = mm->total_vm = 1;
249 up_write(&mm->mmap_sem);
250
251 bprm->p = vma->vm_end - sizeof(void *);
252
253 return 0;
254
255 err:
256 if (vma) {
257 bprm->vma = NULL;
258 kmem_cache_free(vm_area_cachep, vma);
259 }
260
261 return err;
262 }
263
264 static bool valid_arg_len(struct linux_binprm *bprm, long len)
265 {
266 return len <= MAX_ARG_STRLEN;
267 }
268
269 #else
270
271 static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
272 int write)
273 {
274 struct page *page;
275
276 page = bprm->page[pos / PAGE_SIZE];
277 if (!page && write) {
278 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
279 if (!page)
280 return NULL;
281 bprm->page[pos / PAGE_SIZE] = page;
282 }
283
284 return page;
285 }
286
287 static void put_arg_page(struct page *page)
288 {
289 }
290
291 static void free_arg_page(struct linux_binprm *bprm, int i)
292 {
293 if (bprm->page[i]) {
294 __free_page(bprm->page[i]);
295 bprm->page[i] = NULL;
296 }
297 }
298
299 static void free_arg_pages(struct linux_binprm *bprm)
300 {
301 int i;
302
303 for (i = 0; i < MAX_ARG_PAGES; i++)
304 free_arg_page(bprm, i);
305 }
306
307 static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
308 struct page *page)
309 {
310 }
311
312 static int __bprm_mm_init(struct linux_binprm *bprm)
313 {
314 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
315 return 0;
316 }
317
318 static bool valid_arg_len(struct linux_binprm *bprm, long len)
319 {
320 return len <= bprm->p;
321 }
322
323 #endif /* CONFIG_MMU */
324
325 /*
326 * Create a new mm_struct and populate it with a temporary stack
327 * vm_area_struct. We don't have enough context at this point to set the stack
328 * flags, permissions, and offset, so we use temporary values. We'll update
329 * them later in setup_arg_pages().
330 */
331 int bprm_mm_init(struct linux_binprm *bprm)
332 {
333 int err;
334 struct mm_struct *mm = NULL;
335
336 bprm->mm = mm = mm_alloc();
337 err = -ENOMEM;
338 if (!mm)
339 goto err;
340
341 err = init_new_context(current, mm);
342 if (err)
343 goto err;
344
345 err = __bprm_mm_init(bprm);
346 if (err)
347 goto err;
348
349 return 0;
350
351 err:
352 if (mm) {
353 bprm->mm = NULL;
354 mmdrop(mm);
355 }
356
357 return err;
358 }
359
360 /*
361 * count() counts the number of strings in array ARGV.
362 */
363 static int count(char __user * __user * argv, int max)
364 {
365 int i = 0;
366
367 if (argv != NULL) {
368 for (;;) {
369 char __user * p;
370
371 if (get_user(p, argv))
372 return -EFAULT;
373 if (!p)
374 break;
375 argv++;
376 if(++i > max)
377 return -E2BIG;
378 cond_resched();
379 }
380 }
381 return i;
382 }
383
384 /*
385 * 'copy_strings()' copies argument/environment strings from the old
386 * processes's memory to the new process's stack. The call to get_user_pages()
387 * ensures the destination page is created and not swapped out.
388 */
389 static int copy_strings(int argc, char __user * __user * argv,
390 struct linux_binprm *bprm)
391 {
392 struct page *kmapped_page = NULL;
393 char *kaddr = NULL;
394 unsigned long kpos = 0;
395 int ret;
396
397 while (argc-- > 0) {
398 char __user *str;
399 int len;
400 unsigned long pos;
401
402 if (get_user(str, argv+argc) ||
403 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
404 ret = -EFAULT;
405 goto out;
406 }
407
408 if (!valid_arg_len(bprm, len)) {
409 ret = -E2BIG;
410 goto out;
411 }
412
413 /* We're going to work our way backwords. */
414 pos = bprm->p;
415 str += len;
416 bprm->p -= len;
417
418 while (len > 0) {
419 int offset, bytes_to_copy;
420
421 offset = pos % PAGE_SIZE;
422 if (offset == 0)
423 offset = PAGE_SIZE;
424
425 bytes_to_copy = offset;
426 if (bytes_to_copy > len)
427 bytes_to_copy = len;
428
429 offset -= bytes_to_copy;
430 pos -= bytes_to_copy;
431 str -= bytes_to_copy;
432 len -= bytes_to_copy;
433
434 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
435 struct page *page;
436
437 page = get_arg_page(bprm, pos, 1);
438 if (!page) {
439 ret = -E2BIG;
440 goto out;
441 }
442
443 if (kmapped_page) {
444 flush_kernel_dcache_page(kmapped_page);
445 kunmap(kmapped_page);
446 put_arg_page(kmapped_page);
447 }
448 kmapped_page = page;
449 kaddr = kmap(kmapped_page);
450 kpos = pos & PAGE_MASK;
451 flush_arg_page(bprm, kpos, kmapped_page);
452 }
453 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
454 ret = -EFAULT;
455 goto out;
456 }
457 }
458 }
459 ret = 0;
460 out:
461 if (kmapped_page) {
462 flush_kernel_dcache_page(kmapped_page);
463 kunmap(kmapped_page);
464 put_arg_page(kmapped_page);
465 }
466 return ret;
467 }
468
469 /*
470 * Like copy_strings, but get argv and its values from kernel memory.
471 */
472 int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
473 {
474 int r;
475 mm_segment_t oldfs = get_fs();
476 set_fs(KERNEL_DS);
477 r = copy_strings(argc, (char __user * __user *)argv, bprm);
478 set_fs(oldfs);
479 return r;
480 }
481 EXPORT_SYMBOL(copy_strings_kernel);
482
483 #ifdef CONFIG_MMU
484
485 /*
486 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
487 * the binfmt code determines where the new stack should reside, we shift it to
488 * its final location. The process proceeds as follows:
489 *
490 * 1) Use shift to calculate the new vma endpoints.
491 * 2) Extend vma to cover both the old and new ranges. This ensures the
492 * arguments passed to subsequent functions are consistent.
493 * 3) Move vma's page tables to the new range.
494 * 4) Free up any cleared pgd range.
495 * 5) Shrink the vma to cover only the new range.
496 */
497 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
498 {
499 struct mm_struct *mm = vma->vm_mm;
500 unsigned long old_start = vma->vm_start;
501 unsigned long old_end = vma->vm_end;
502 unsigned long length = old_end - old_start;
503 unsigned long new_start = old_start - shift;
504 unsigned long new_end = old_end - shift;
505 struct mmu_gather *tlb;
506
507 BUG_ON(new_start > new_end);
508
509 /*
510 * ensure there are no vmas between where we want to go
511 * and where we are
512 */
513 if (vma != find_vma(mm, new_start))
514 return -EFAULT;
515
516 /*
517 * cover the whole range: [new_start, old_end)
518 */
519 vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
520
521 /*
522 * move the page tables downwards, on failure we rely on
523 * process cleanup to remove whatever mess we made.
524 */
525 if (length != move_page_tables(vma, old_start,
526 vma, new_start, length))
527 return -ENOMEM;
528
529 lru_add_drain();
530 tlb = tlb_gather_mmu(mm, 0);
531 if (new_end > old_start) {
532 /*
533 * when the old and new regions overlap clear from new_end.
534 */
535 free_pgd_range(&tlb, new_end, old_end, new_end,
536 vma->vm_next ? vma->vm_next->vm_start : 0);
537 } else {
538 /*
539 * otherwise, clean from old_start; this is done to not touch
540 * the address space in [new_end, old_start) some architectures
541 * have constraints on va-space that make this illegal (IA64) -
542 * for the others its just a little faster.
543 */
544 free_pgd_range(&tlb, old_start, old_end, new_end,
545 vma->vm_next ? vma->vm_next->vm_start : 0);
546 }
547 tlb_finish_mmu(tlb, new_end, old_end);
548
549 /*
550 * shrink the vma to just the new range.
551 */
552 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
553
554 return 0;
555 }
556
557 #define EXTRA_STACK_VM_PAGES 20 /* random */
558
559 /*
560 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
561 * the stack is optionally relocated, and some extra space is added.
562 */
563 int setup_arg_pages(struct linux_binprm *bprm,
564 unsigned long stack_top,
565 int executable_stack)
566 {
567 unsigned long ret;
568 unsigned long stack_shift;
569 struct mm_struct *mm = current->mm;
570 struct vm_area_struct *vma = bprm->vma;
571 struct vm_area_struct *prev = NULL;
572 unsigned long vm_flags;
573 unsigned long stack_base;
574
575 #ifdef CONFIG_STACK_GROWSUP
576 /* Limit stack size to 1GB */
577 stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
578 if (stack_base > (1 << 30))
579 stack_base = 1 << 30;
580
581 /* Make sure we didn't let the argument array grow too large. */
582 if (vma->vm_end - vma->vm_start > stack_base)
583 return -ENOMEM;
584
585 stack_base = PAGE_ALIGN(stack_top - stack_base);
586
587 stack_shift = vma->vm_start - stack_base;
588 mm->arg_start = bprm->p - stack_shift;
589 bprm->p = vma->vm_end - stack_shift;
590 #else
591 stack_top = arch_align_stack(stack_top);
592 stack_top = PAGE_ALIGN(stack_top);
593 stack_shift = vma->vm_end - stack_top;
594
595 bprm->p -= stack_shift;
596 mm->arg_start = bprm->p;
597 #endif
598
599 if (bprm->loader)
600 bprm->loader -= stack_shift;
601 bprm->exec -= stack_shift;
602
603 down_write(&mm->mmap_sem);
604 vm_flags = vma->vm_flags;
605
606 /*
607 * Adjust stack execute permissions; explicitly enable for
608 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
609 * (arch default) otherwise.
610 */
611 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
612 vm_flags |= VM_EXEC;
613 else if (executable_stack == EXSTACK_DISABLE_X)
614 vm_flags &= ~VM_EXEC;
615 vm_flags |= mm->def_flags;
616
617 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
618 vm_flags);
619 if (ret)
620 goto out_unlock;
621 BUG_ON(prev != vma);
622
623 /* Move stack pages down in memory. */
624 if (stack_shift) {
625 ret = shift_arg_pages(vma, stack_shift);
626 if (ret) {
627 up_write(&mm->mmap_sem);
628 return ret;
629 }
630 }
631
632 #ifdef CONFIG_STACK_GROWSUP
633 stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
634 #else
635 stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
636 #endif
637 ret = expand_stack(vma, stack_base);
638 if (ret)
639 ret = -EFAULT;
640
641 out_unlock:
642 up_write(&mm->mmap_sem);
643 return 0;
644 }
645 EXPORT_SYMBOL(setup_arg_pages);
646
647 #endif /* CONFIG_MMU */
648
649 struct file *open_exec(const char *name)
650 {
651 struct nameidata nd;
652 int err;
653 struct file *file;
654
655 err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
656 file = ERR_PTR(err);
657
658 if (!err) {
659 struct inode *inode = nd.dentry->d_inode;
660 file = ERR_PTR(-EACCES);
661 if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
662 S_ISREG(inode->i_mode)) {
663 int err = vfs_permission(&nd, MAY_EXEC);
664 file = ERR_PTR(err);
665 if (!err) {
666 file = nameidata_to_filp(&nd, O_RDONLY);
667 if (!IS_ERR(file)) {
668 err = deny_write_access(file);
669 if (err) {
670 fput(file);
671 file = ERR_PTR(err);
672 }
673 }
674 out:
675 return file;
676 }
677 }
678 release_open_intent(&nd);
679 path_release(&nd);
680 }
681 goto out;
682 }
683
684 EXPORT_SYMBOL(open_exec);
685
686 int kernel_read(struct file *file, unsigned long offset,
687 char *addr, unsigned long count)
688 {
689 mm_segment_t old_fs;
690 loff_t pos = offset;
691 int result;
692
693 old_fs = get_fs();
694 set_fs(get_ds());
695 /* The cast to a user pointer is valid due to the set_fs() */
696 result = vfs_read(file, (void __user *)addr, count, &pos);
697 set_fs(old_fs);
698 return result;
699 }
700
701 EXPORT_SYMBOL(kernel_read);
702
703 static int exec_mmap(struct mm_struct *mm)
704 {
705 struct task_struct *tsk;
706 struct mm_struct * old_mm, *active_mm;
707
708 /* Notify parent that we're no longer interested in the old VM */
709 tsk = current;
710 old_mm = current->mm;
711 mm_release(tsk, old_mm);
712
713 if (old_mm) {
714 /*
715 * Make sure that if there is a core dump in progress
716 * for the old mm, we get out and die instead of going
717 * through with the exec. We must hold mmap_sem around
718 * checking core_waiters and changing tsk->mm. The
719 * core-inducing thread will increment core_waiters for
720 * each thread whose ->mm == old_mm.
721 */
722 down_read(&old_mm->mmap_sem);
723 if (unlikely(old_mm->core_waiters)) {
724 up_read(&old_mm->mmap_sem);
725 return -EINTR;
726 }
727 }
728 task_lock(tsk);
729 active_mm = tsk->active_mm;
730 tsk->mm = mm;
731 tsk->active_mm = mm;
732 activate_mm(active_mm, mm);
733 task_unlock(tsk);
734 arch_pick_mmap_layout(mm);
735 if (old_mm) {
736 up_read(&old_mm->mmap_sem);
737 BUG_ON(active_mm != old_mm);
738 mmput(old_mm);
739 return 0;
740 }
741 mmdrop(active_mm);
742 return 0;
743 }
744
745 /*
746 * This function makes sure the current process has its own signal table,
747 * so that flush_signal_handlers can later reset the handlers without
748 * disturbing other processes. (Other processes might share the signal
749 * table via the CLONE_SIGHAND option to clone().)
750 */
751 static int de_thread(struct task_struct *tsk)
752 {
753 struct signal_struct *sig = tsk->signal;
754 struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
755 spinlock_t *lock = &oldsighand->siglock;
756 struct task_struct *leader = NULL;
757 int count;
758
759 /*
760 * If we don't share sighandlers, then we aren't sharing anything
761 * and we can just re-use it all.
762 */
763 if (atomic_read(&oldsighand->count) <= 1) {
764 exit_itimers(sig);
765 return 0;
766 }
767
768 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
769 if (!newsighand)
770 return -ENOMEM;
771
772 if (thread_group_empty(tsk))
773 goto no_thread_group;
774
775 /*
776 * Kill all other threads in the thread group.
777 * We must hold tasklist_lock to call zap_other_threads.
778 */
779 read_lock(&tasklist_lock);
780 spin_lock_irq(lock);
781 if (sig->flags & SIGNAL_GROUP_EXIT) {
782 /*
783 * Another group action in progress, just
784 * return so that the signal is processed.
785 */
786 spin_unlock_irq(lock);
787 read_unlock(&tasklist_lock);
788 kmem_cache_free(sighand_cachep, newsighand);
789 return -EAGAIN;
790 }
791
792 /*
793 * child_reaper ignores SIGKILL, change it now.
794 * Reparenting needs write_lock on tasklist_lock,
795 * so it is safe to do it under read_lock.
796 */
797 if (unlikely(tsk->group_leader == child_reaper(tsk)))
798 tsk->nsproxy->pid_ns->child_reaper = tsk;
799
800 zap_other_threads(tsk);
801 read_unlock(&tasklist_lock);
802
803 /*
804 * Account for the thread group leader hanging around:
805 */
806 count = 1;
807 if (!thread_group_leader(tsk)) {
808 count = 2;
809 /*
810 * The SIGALRM timer survives the exec, but needs to point
811 * at us as the new group leader now. We have a race with
812 * a timer firing now getting the old leader, so we need to
813 * synchronize with any firing (by calling del_timer_sync)
814 * before we can safely let the old group leader die.
815 */
816 sig->tsk = tsk;
817 spin_unlock_irq(lock);
818 if (hrtimer_cancel(&sig->real_timer))
819 hrtimer_restart(&sig->real_timer);
820 spin_lock_irq(lock);
821 }
822 while (atomic_read(&sig->count) > count) {
823 sig->group_exit_task = tsk;
824 sig->notify_count = count;
825 __set_current_state(TASK_UNINTERRUPTIBLE);
826 spin_unlock_irq(lock);
827 schedule();
828 spin_lock_irq(lock);
829 }
830 sig->group_exit_task = NULL;
831 sig->notify_count = 0;
832 spin_unlock_irq(lock);
833
834 /*
835 * At this point all other threads have exited, all we have to
836 * do is to wait for the thread group leader to become inactive,
837 * and to assume its PID:
838 */
839 if (!thread_group_leader(tsk)) {
840 /*
841 * Wait for the thread group leader to be a zombie.
842 * It should already be zombie at this point, most
843 * of the time.
844 */
845 leader = tsk->group_leader;
846 while (leader->exit_state != EXIT_ZOMBIE)
847 yield();
848
849 /*
850 * The only record we have of the real-time age of a
851 * process, regardless of execs it's done, is start_time.
852 * All the past CPU time is accumulated in signal_struct
853 * from sister threads now dead. But in this non-leader
854 * exec, nothing survives from the original leader thread,
855 * whose birth marks the true age of this process now.
856 * When we take on its identity by switching to its PID, we
857 * also take its birthdate (always earlier than our own).
858 */
859 tsk->start_time = leader->start_time;
860
861 write_lock_irq(&tasklist_lock);
862
863 BUG_ON(leader->tgid != tsk->tgid);
864 BUG_ON(tsk->pid == tsk->tgid);
865 /*
866 * An exec() starts a new thread group with the
867 * TGID of the previous thread group. Rehash the
868 * two threads with a switched PID, and release
869 * the former thread group leader:
870 */
871
872 /* Become a process group leader with the old leader's pid.
873 * The old leader becomes a thread of the this thread group.
874 * Note: The old leader also uses this pid until release_task
875 * is called. Odd but simple and correct.
876 */
877 detach_pid(tsk, PIDTYPE_PID);
878 tsk->pid = leader->pid;
879 attach_pid(tsk, PIDTYPE_PID, find_pid(tsk->pid));
880 transfer_pid(leader, tsk, PIDTYPE_PGID);
881 transfer_pid(leader, tsk, PIDTYPE_SID);
882 list_replace_rcu(&leader->tasks, &tsk->tasks);
883
884 tsk->group_leader = tsk;
885 leader->group_leader = tsk;
886
887 tsk->exit_signal = SIGCHLD;
888
889 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
890 leader->exit_state = EXIT_DEAD;
891
892 write_unlock_irq(&tasklist_lock);
893 }
894
895 /*
896 * There may be one thread left which is just exiting,
897 * but it's safe to stop telling the group to kill themselves.
898 */
899 sig->flags = 0;
900
901 no_thread_group:
902 exit_itimers(sig);
903 if (leader)
904 release_task(leader);
905
906 if (atomic_read(&oldsighand->count) == 1) {
907 /*
908 * Now that we nuked the rest of the thread group,
909 * it turns out we are not sharing sighand any more either.
910 * So we can just keep it.
911 */
912 kmem_cache_free(sighand_cachep, newsighand);
913 } else {
914 /*
915 * Move our state over to newsighand and switch it in.
916 */
917 atomic_set(&newsighand->count, 1);
918 memcpy(newsighand->action, oldsighand->action,
919 sizeof(newsighand->action));
920
921 write_lock_irq(&tasklist_lock);
922 spin_lock(&oldsighand->siglock);
923 spin_lock_nested(&newsighand->siglock, SINGLE_DEPTH_NESTING);
924
925 rcu_assign_pointer(tsk->sighand, newsighand);
926 recalc_sigpending();
927
928 spin_unlock(&newsighand->siglock);
929 spin_unlock(&oldsighand->siglock);
930 write_unlock_irq(&tasklist_lock);
931
932 __cleanup_sighand(oldsighand);
933 }
934
935 BUG_ON(!thread_group_leader(tsk));
936 return 0;
937 }
938
939 /*
940 * These functions flushes out all traces of the currently running executable
941 * so that a new one can be started
942 */
943
944 static void flush_old_files(struct files_struct * files)
945 {
946 long j = -1;
947 struct fdtable *fdt;
948
949 spin_lock(&files->file_lock);
950 for (;;) {
951 unsigned long set, i;
952
953 j++;
954 i = j * __NFDBITS;
955 fdt = files_fdtable(files);
956 if (i >= fdt->max_fds)
957 break;
958 set = fdt->close_on_exec->fds_bits[j];
959 if (!set)
960 continue;
961 fdt->close_on_exec->fds_bits[j] = 0;
962 spin_unlock(&files->file_lock);
963 for ( ; set ; i++,set >>= 1) {
964 if (set & 1) {
965 sys_close(i);
966 }
967 }
968 spin_lock(&files->file_lock);
969
970 }
971 spin_unlock(&files->file_lock);
972 }
973
974 void get_task_comm(char *buf, struct task_struct *tsk)
975 {
976 /* buf must be at least sizeof(tsk->comm) in size */
977 task_lock(tsk);
978 strncpy(buf, tsk->comm, sizeof(tsk->comm));
979 task_unlock(tsk);
980 }
981
982 void set_task_comm(struct task_struct *tsk, char *buf)
983 {
984 task_lock(tsk);
985 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
986 task_unlock(tsk);
987 }
988
989 int flush_old_exec(struct linux_binprm * bprm)
990 {
991 char * name;
992 int i, ch, retval;
993 struct files_struct *files;
994 char tcomm[sizeof(current->comm)];
995
996 /*
997 * Make sure we have a private signal table and that
998 * we are unassociated from the previous thread group.
999 */
1000 retval = de_thread(current);
1001 if (retval)
1002 goto out;
1003
1004 /*
1005 * Make sure we have private file handles. Ask the
1006 * fork helper to do the work for us and the exit
1007 * helper to do the cleanup of the old one.
1008 */
1009 files = current->files; /* refcounted so safe to hold */
1010 retval = unshare_files();
1011 if (retval)
1012 goto out;
1013 /*
1014 * Release all of the old mmap stuff
1015 */
1016 retval = exec_mmap(bprm->mm);
1017 if (retval)
1018 goto mmap_failed;
1019
1020 bprm->mm = NULL; /* We're using it now */
1021
1022 /* This is the point of no return */
1023 put_files_struct(files);
1024
1025 current->sas_ss_sp = current->sas_ss_size = 0;
1026
1027 if (current->euid == current->uid && current->egid == current->gid)
1028 set_dumpable(current->mm, 1);
1029 else
1030 set_dumpable(current->mm, suid_dumpable);
1031
1032 name = bprm->filename;
1033
1034 /* Copies the binary name from after last slash */
1035 for (i=0; (ch = *(name++)) != '\0';) {
1036 if (ch == '/')
1037 i = 0; /* overwrite what we wrote */
1038 else
1039 if (i < (sizeof(tcomm) - 1))
1040 tcomm[i++] = ch;
1041 }
1042 tcomm[i] = '\0';
1043 set_task_comm(current, tcomm);
1044
1045 current->flags &= ~PF_RANDOMIZE;
1046 flush_thread();
1047
1048 /* Set the new mm task size. We have to do that late because it may
1049 * depend on TIF_32BIT which is only updated in flush_thread() on
1050 * some architectures like powerpc
1051 */
1052 current->mm->task_size = TASK_SIZE;
1053
1054 if (bprm->e_uid != current->euid || bprm->e_gid != current->egid) {
1055 suid_keys(current);
1056 set_dumpable(current->mm, suid_dumpable);
1057 current->pdeath_signal = 0;
1058 } else if (file_permission(bprm->file, MAY_READ) ||
1059 (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
1060 suid_keys(current);
1061 set_dumpable(current->mm, suid_dumpable);
1062 }
1063
1064 /* An exec changes our domain. We are no longer part of the thread
1065 group */
1066
1067 current->self_exec_id++;
1068
1069 flush_signal_handlers(current, 0);
1070 flush_old_files(current->files);
1071
1072 return 0;
1073
1074 mmap_failed:
1075 reset_files_struct(current, files);
1076 out:
1077 return retval;
1078 }
1079
1080 EXPORT_SYMBOL(flush_old_exec);
1081
1082 /*
1083 * Fill the binprm structure from the inode.
1084 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1085 */
1086 int prepare_binprm(struct linux_binprm *bprm)
1087 {
1088 int mode;
1089 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1090 int retval;
1091
1092 mode = inode->i_mode;
1093 if (bprm->file->f_op == NULL)
1094 return -EACCES;
1095
1096 bprm->e_uid = current->euid;
1097 bprm->e_gid = current->egid;
1098
1099 if(!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1100 /* Set-uid? */
1101 if (mode & S_ISUID) {
1102 current->personality &= ~PER_CLEAR_ON_SETID;
1103 bprm->e_uid = inode->i_uid;
1104 }
1105
1106 /* Set-gid? */
1107 /*
1108 * If setgid is set but no group execute bit then this
1109 * is a candidate for mandatory locking, not a setgid
1110 * executable.
1111 */
1112 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1113 current->personality &= ~PER_CLEAR_ON_SETID;
1114 bprm->e_gid = inode->i_gid;
1115 }
1116 }
1117
1118 /* fill in binprm security blob */
1119 retval = security_bprm_set(bprm);
1120 if (retval)
1121 return retval;
1122
1123 memset(bprm->buf,0,BINPRM_BUF_SIZE);
1124 return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
1125 }
1126
1127 EXPORT_SYMBOL(prepare_binprm);
1128
1129 static int unsafe_exec(struct task_struct *p)
1130 {
1131 int unsafe = 0;
1132 if (p->ptrace & PT_PTRACED) {
1133 if (p->ptrace & PT_PTRACE_CAP)
1134 unsafe |= LSM_UNSAFE_PTRACE_CAP;
1135 else
1136 unsafe |= LSM_UNSAFE_PTRACE;
1137 }
1138 if (atomic_read(&p->fs->count) > 1 ||
1139 atomic_read(&p->files->count) > 1 ||
1140 atomic_read(&p->sighand->count) > 1)
1141 unsafe |= LSM_UNSAFE_SHARE;
1142
1143 return unsafe;
1144 }
1145
1146 void compute_creds(struct linux_binprm *bprm)
1147 {
1148 int unsafe;
1149
1150 if (bprm->e_uid != current->uid) {
1151 suid_keys(current);
1152 current->pdeath_signal = 0;
1153 }
1154 exec_keys(current);
1155
1156 task_lock(current);
1157 unsafe = unsafe_exec(current);
1158 security_bprm_apply_creds(bprm, unsafe);
1159 task_unlock(current);
1160 security_bprm_post_apply_creds(bprm);
1161 }
1162 EXPORT_SYMBOL(compute_creds);
1163
1164 /*
1165 * Arguments are '\0' separated strings found at the location bprm->p
1166 * points to; chop off the first by relocating brpm->p to right after
1167 * the first '\0' encountered.
1168 */
1169 int remove_arg_zero(struct linux_binprm *bprm)
1170 {
1171 int ret = 0;
1172 unsigned long offset;
1173 char *kaddr;
1174 struct page *page;
1175
1176 if (!bprm->argc)
1177 return 0;
1178
1179 do {
1180 offset = bprm->p & ~PAGE_MASK;
1181 page = get_arg_page(bprm, bprm->p, 0);
1182 if (!page) {
1183 ret = -EFAULT;
1184 goto out;
1185 }
1186 kaddr = kmap_atomic(page, KM_USER0);
1187
1188 for (; offset < PAGE_SIZE && kaddr[offset];
1189 offset++, bprm->p++)
1190 ;
1191
1192 kunmap_atomic(kaddr, KM_USER0);
1193 put_arg_page(page);
1194
1195 if (offset == PAGE_SIZE)
1196 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1197 } while (offset == PAGE_SIZE);
1198
1199 bprm->p++;
1200 bprm->argc--;
1201 ret = 0;
1202
1203 out:
1204 return ret;
1205 }
1206 EXPORT_SYMBOL(remove_arg_zero);
1207
1208 /*
1209 * cycle the list of binary formats handler, until one recognizes the image
1210 */
1211 int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1212 {
1213 int try,retval;
1214 struct linux_binfmt *fmt;
1215 #ifdef __alpha__
1216 /* handle /sbin/loader.. */
1217 {
1218 struct exec * eh = (struct exec *) bprm->buf;
1219
1220 if (!bprm->loader && eh->fh.f_magic == 0x183 &&
1221 (eh->fh.f_flags & 0x3000) == 0x3000)
1222 {
1223 struct file * file;
1224 unsigned long loader;
1225
1226 allow_write_access(bprm->file);
1227 fput(bprm->file);
1228 bprm->file = NULL;
1229
1230 loader = bprm->vma->vm_end - sizeof(void *);
1231
1232 file = open_exec("/sbin/loader");
1233 retval = PTR_ERR(file);
1234 if (IS_ERR(file))
1235 return retval;
1236
1237 /* Remember if the application is TASO. */
1238 bprm->sh_bang = eh->ah.entry < 0x100000000UL;
1239
1240 bprm->file = file;
1241 bprm->loader = loader;
1242 retval = prepare_binprm(bprm);
1243 if (retval<0)
1244 return retval;
1245 /* should call search_binary_handler recursively here,
1246 but it does not matter */
1247 }
1248 }
1249 #endif
1250 retval = security_bprm_check(bprm);
1251 if (retval)
1252 return retval;
1253
1254 /* kernel module loader fixup */
1255 /* so we don't try to load run modprobe in kernel space. */
1256 set_fs(USER_DS);
1257
1258 retval = audit_bprm(bprm);
1259 if (retval)
1260 return retval;
1261
1262 retval = -ENOENT;
1263 for (try=0; try<2; try++) {
1264 read_lock(&binfmt_lock);
1265 list_for_each_entry(fmt, &formats, lh) {
1266 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1267 if (!fn)
1268 continue;
1269 if (!try_module_get(fmt->module))
1270 continue;
1271 read_unlock(&binfmt_lock);
1272 retval = fn(bprm, regs);
1273 if (retval >= 0) {
1274 put_binfmt(fmt);
1275 allow_write_access(bprm->file);
1276 if (bprm->file)
1277 fput(bprm->file);
1278 bprm->file = NULL;
1279 current->did_exec = 1;
1280 proc_exec_connector(current);
1281 return retval;
1282 }
1283 read_lock(&binfmt_lock);
1284 put_binfmt(fmt);
1285 if (retval != -ENOEXEC || bprm->mm == NULL)
1286 break;
1287 if (!bprm->file) {
1288 read_unlock(&binfmt_lock);
1289 return retval;
1290 }
1291 }
1292 read_unlock(&binfmt_lock);
1293 if (retval != -ENOEXEC || bprm->mm == NULL) {
1294 break;
1295 #ifdef CONFIG_KMOD
1296 }else{
1297 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1298 if (printable(bprm->buf[0]) &&
1299 printable(bprm->buf[1]) &&
1300 printable(bprm->buf[2]) &&
1301 printable(bprm->buf[3]))
1302 break; /* -ENOEXEC */
1303 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1304 #endif
1305 }
1306 }
1307 return retval;
1308 }
1309
1310 EXPORT_SYMBOL(search_binary_handler);
1311
1312 /*
1313 * sys_execve() executes a new program.
1314 */
1315 int do_execve(char * filename,
1316 char __user *__user *argv,
1317 char __user *__user *envp,
1318 struct pt_regs * regs)
1319 {
1320 struct linux_binprm *bprm;
1321 struct file *file;
1322 unsigned long env_p;
1323 int retval;
1324
1325 retval = -ENOMEM;
1326 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1327 if (!bprm)
1328 goto out_ret;
1329
1330 file = open_exec(filename);
1331 retval = PTR_ERR(file);
1332 if (IS_ERR(file))
1333 goto out_kfree;
1334
1335 sched_exec();
1336
1337 bprm->file = file;
1338 bprm->filename = filename;
1339 bprm->interp = filename;
1340
1341 retval = bprm_mm_init(bprm);
1342 if (retval)
1343 goto out_file;
1344
1345 bprm->argc = count(argv, MAX_ARG_STRINGS);
1346 if ((retval = bprm->argc) < 0)
1347 goto out_mm;
1348
1349 bprm->envc = count(envp, MAX_ARG_STRINGS);
1350 if ((retval = bprm->envc) < 0)
1351 goto out_mm;
1352
1353 retval = security_bprm_alloc(bprm);
1354 if (retval)
1355 goto out;
1356
1357 retval = prepare_binprm(bprm);
1358 if (retval < 0)
1359 goto out;
1360
1361 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1362 if (retval < 0)
1363 goto out;
1364
1365 bprm->exec = bprm->p;
1366 retval = copy_strings(bprm->envc, envp, bprm);
1367 if (retval < 0)
1368 goto out;
1369
1370 env_p = bprm->p;
1371 retval = copy_strings(bprm->argc, argv, bprm);
1372 if (retval < 0)
1373 goto out;
1374 bprm->argv_len = env_p - bprm->p;
1375
1376 retval = search_binary_handler(bprm,regs);
1377 if (retval >= 0) {
1378 /* execve success */
1379 free_arg_pages(bprm);
1380 security_bprm_free(bprm);
1381 acct_update_integrals(current);
1382 kfree(bprm);
1383 return retval;
1384 }
1385
1386 out:
1387 free_arg_pages(bprm);
1388 if (bprm->security)
1389 security_bprm_free(bprm);
1390
1391 out_mm:
1392 if (bprm->mm)
1393 mmput (bprm->mm);
1394
1395 out_file:
1396 if (bprm->file) {
1397 allow_write_access(bprm->file);
1398 fput(bprm->file);
1399 }
1400 out_kfree:
1401 kfree(bprm);
1402
1403 out_ret:
1404 return retval;
1405 }
1406
1407 int set_binfmt(struct linux_binfmt *new)
1408 {
1409 struct linux_binfmt *old = current->binfmt;
1410
1411 if (new) {
1412 if (!try_module_get(new->module))
1413 return -1;
1414 }
1415 current->binfmt = new;
1416 if (old)
1417 module_put(old->module);
1418 return 0;
1419 }
1420
1421 EXPORT_SYMBOL(set_binfmt);
1422
1423 /* format_corename will inspect the pattern parameter, and output a
1424 * name into corename, which must have space for at least
1425 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1426 */
1427 static int format_corename(char *corename, const char *pattern, long signr)
1428 {
1429 const char *pat_ptr = pattern;
1430 char *out_ptr = corename;
1431 char *const out_end = corename + CORENAME_MAX_SIZE;
1432 int rc;
1433 int pid_in_pattern = 0;
1434 int ispipe = 0;
1435
1436 if (*pattern == '|')
1437 ispipe = 1;
1438
1439 /* Repeat as long as we have more pattern to process and more output
1440 space */
1441 while (*pat_ptr) {
1442 if (*pat_ptr != '%') {
1443 if (out_ptr == out_end)
1444 goto out;
1445 *out_ptr++ = *pat_ptr++;
1446 } else {
1447 switch (*++pat_ptr) {
1448 case 0:
1449 goto out;
1450 /* Double percent, output one percent */
1451 case '%':
1452 if (out_ptr == out_end)
1453 goto out;
1454 *out_ptr++ = '%';
1455 break;
1456 /* pid */
1457 case 'p':
1458 pid_in_pattern = 1;
1459 rc = snprintf(out_ptr, out_end - out_ptr,
1460 "%d", current->tgid);
1461 if (rc > out_end - out_ptr)
1462 goto out;
1463 out_ptr += rc;
1464 break;
1465 /* uid */
1466 case 'u':
1467 rc = snprintf(out_ptr, out_end - out_ptr,
1468 "%d", current->uid);
1469 if (rc > out_end - out_ptr)
1470 goto out;
1471 out_ptr += rc;
1472 break;
1473 /* gid */
1474 case 'g':
1475 rc = snprintf(out_ptr, out_end - out_ptr,
1476 "%d", current->gid);
1477 if (rc > out_end - out_ptr)
1478 goto out;
1479 out_ptr += rc;
1480 break;
1481 /* signal that caused the coredump */
1482 case 's':
1483 rc = snprintf(out_ptr, out_end - out_ptr,
1484 "%ld", signr);
1485 if (rc > out_end - out_ptr)
1486 goto out;
1487 out_ptr += rc;
1488 break;
1489 /* UNIX time of coredump */
1490 case 't': {
1491 struct timeval tv;
1492 do_gettimeofday(&tv);
1493 rc = snprintf(out_ptr, out_end - out_ptr,
1494 "%lu", tv.tv_sec);
1495 if (rc > out_end - out_ptr)
1496 goto out;
1497 out_ptr += rc;
1498 break;
1499 }
1500 /* hostname */
1501 case 'h':
1502 down_read(&uts_sem);
1503 rc = snprintf(out_ptr, out_end - out_ptr,
1504 "%s", utsname()->nodename);
1505 up_read(&uts_sem);
1506 if (rc > out_end - out_ptr)
1507 goto out;
1508 out_ptr += rc;
1509 break;
1510 /* executable */
1511 case 'e':
1512 rc = snprintf(out_ptr, out_end - out_ptr,
1513 "%s", current->comm);
1514 if (rc > out_end - out_ptr)
1515 goto out;
1516 out_ptr += rc;
1517 break;
1518 /* core limit size */
1519 case 'c':
1520 rc = snprintf(out_ptr, out_end - out_ptr,
1521 "%lu", current->signal->rlim[RLIMIT_CORE].rlim_cur);
1522 if (rc > out_end - out_ptr)
1523 goto out;
1524 out_ptr += rc;
1525 break;
1526 default:
1527 break;
1528 }
1529 ++pat_ptr;
1530 }
1531 }
1532 /* Backward compatibility with core_uses_pid:
1533 *
1534 * If core_pattern does not include a %p (as is the default)
1535 * and core_uses_pid is set, then .%pid will be appended to
1536 * the filename. Do not do this for piped commands. */
1537 if (!ispipe && !pid_in_pattern
1538 && (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
1539 rc = snprintf(out_ptr, out_end - out_ptr,
1540 ".%d", current->tgid);
1541 if (rc > out_end - out_ptr)
1542 goto out;
1543 out_ptr += rc;
1544 }
1545 out:
1546 *out_ptr = 0;
1547 return ispipe;
1548 }
1549
1550 static void zap_process(struct task_struct *start)
1551 {
1552 struct task_struct *t;
1553
1554 start->signal->flags = SIGNAL_GROUP_EXIT;
1555 start->signal->group_stop_count = 0;
1556
1557 t = start;
1558 do {
1559 if (t != current && t->mm) {
1560 t->mm->core_waiters++;
1561 sigaddset(&t->pending.signal, SIGKILL);
1562 signal_wake_up(t, 1);
1563 }
1564 } while ((t = next_thread(t)) != start);
1565 }
1566
1567 static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1568 int exit_code)
1569 {
1570 struct task_struct *g, *p;
1571 unsigned long flags;
1572 int err = -EAGAIN;
1573
1574 spin_lock_irq(&tsk->sighand->siglock);
1575 if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT)) {
1576 tsk->signal->group_exit_code = exit_code;
1577 zap_process(tsk);
1578 err = 0;
1579 }
1580 spin_unlock_irq(&tsk->sighand->siglock);
1581 if (err)
1582 return err;
1583
1584 if (atomic_read(&mm->mm_users) == mm->core_waiters + 1)
1585 goto done;
1586
1587 rcu_read_lock();
1588 for_each_process(g) {
1589 if (g == tsk->group_leader)
1590 continue;
1591
1592 p = g;
1593 do {
1594 if (p->mm) {
1595 if (p->mm == mm) {
1596 /*
1597 * p->sighand can't disappear, but
1598 * may be changed by de_thread()
1599 */
1600 lock_task_sighand(p, &flags);
1601 zap_process(p);
1602 unlock_task_sighand(p, &flags);
1603 }
1604 break;
1605 }
1606 } while ((p = next_thread(p)) != g);
1607 }
1608 rcu_read_unlock();
1609 done:
1610 return mm->core_waiters;
1611 }
1612
1613 static int coredump_wait(int exit_code)
1614 {
1615 struct task_struct *tsk = current;
1616 struct mm_struct *mm = tsk->mm;
1617 struct completion startup_done;
1618 struct completion *vfork_done;
1619 int core_waiters;
1620
1621 init_completion(&mm->core_done);
1622 init_completion(&startup_done);
1623 mm->core_startup_done = &startup_done;
1624
1625 core_waiters = zap_threads(tsk, mm, exit_code);
1626 up_write(&mm->mmap_sem);
1627
1628 if (unlikely(core_waiters < 0))
1629 goto fail;
1630
1631 /*
1632 * Make sure nobody is waiting for us to release the VM,
1633 * otherwise we can deadlock when we wait on each other
1634 */
1635 vfork_done = tsk->vfork_done;
1636 if (vfork_done) {
1637 tsk->vfork_done = NULL;
1638 complete(vfork_done);
1639 }
1640
1641 if (core_waiters)
1642 wait_for_completion(&startup_done);
1643 fail:
1644 BUG_ON(mm->core_waiters);
1645 return core_waiters;
1646 }
1647
1648 /*
1649 * set_dumpable converts traditional three-value dumpable to two flags and
1650 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1651 * these bits are not changed atomically. So get_dumpable can observe the
1652 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1653 * return either old dumpable or new one by paying attention to the order of
1654 * modifying the bits.
1655 *
1656 * dumpable | mm->flags (binary)
1657 * old new | initial interim final
1658 * ---------+-----------------------
1659 * 0 1 | 00 01 01
1660 * 0 2 | 00 10(*) 11
1661 * 1 0 | 01 00 00
1662 * 1 2 | 01 11 11
1663 * 2 0 | 11 10(*) 00
1664 * 2 1 | 11 11 01
1665 *
1666 * (*) get_dumpable regards interim value of 10 as 11.
1667 */
1668 void set_dumpable(struct mm_struct *mm, int value)
1669 {
1670 switch (value) {
1671 case 0:
1672 clear_bit(MMF_DUMPABLE, &mm->flags);
1673 smp_wmb();
1674 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1675 break;
1676 case 1:
1677 set_bit(MMF_DUMPABLE, &mm->flags);
1678 smp_wmb();
1679 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1680 break;
1681 case 2:
1682 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1683 smp_wmb();
1684 set_bit(MMF_DUMPABLE, &mm->flags);
1685 break;
1686 }
1687 }
1688 EXPORT_SYMBOL_GPL(set_dumpable);
1689
1690 int get_dumpable(struct mm_struct *mm)
1691 {
1692 int ret;
1693
1694 ret = mm->flags & 0x3;
1695 return (ret >= 2) ? 2 : ret;
1696 }
1697
1698 int do_coredump(long signr, int exit_code, struct pt_regs * regs)
1699 {
1700 char corename[CORENAME_MAX_SIZE + 1];
1701 struct mm_struct *mm = current->mm;
1702 struct linux_binfmt * binfmt;
1703 struct inode * inode;
1704 struct file * file;
1705 int retval = 0;
1706 int fsuid = current->fsuid;
1707 int flag = 0;
1708 int ispipe = 0;
1709 unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
1710 char **helper_argv = NULL;
1711 int helper_argc = 0;
1712 char *delimit;
1713
1714 audit_core_dumps(signr);
1715
1716 binfmt = current->binfmt;
1717 if (!binfmt || !binfmt->core_dump)
1718 goto fail;
1719 down_write(&mm->mmap_sem);
1720 if (!get_dumpable(mm)) {
1721 up_write(&mm->mmap_sem);
1722 goto fail;
1723 }
1724
1725 /*
1726 * We cannot trust fsuid as being the "true" uid of the
1727 * process nor do we know its entire history. We only know it
1728 * was tainted so we dump it as root in mode 2.
1729 */
1730 if (get_dumpable(mm) == 2) { /* Setuid core dump mode */
1731 flag = O_EXCL; /* Stop rewrite attacks */
1732 current->fsuid = 0; /* Dump root private */
1733 }
1734 set_dumpable(mm, 0);
1735
1736 retval = coredump_wait(exit_code);
1737 if (retval < 0)
1738 goto fail;
1739
1740 /*
1741 * Clear any false indication of pending signals that might
1742 * be seen by the filesystem code called to write the core file.
1743 */
1744 clear_thread_flag(TIF_SIGPENDING);
1745
1746 /*
1747 * lock_kernel() because format_corename() is controlled by sysctl, which
1748 * uses lock_kernel()
1749 */
1750 lock_kernel();
1751 ispipe = format_corename(corename, core_pattern, signr);
1752 unlock_kernel();
1753 /*
1754 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1755 * to a pipe. Since we're not writing directly to the filesystem
1756 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1757 * created unless the pipe reader choses to write out the core file
1758 * at which point file size limits and permissions will be imposed
1759 * as it does with any other process
1760 */
1761 if ((!ispipe) && (core_limit < binfmt->min_coredump))
1762 goto fail_unlock;
1763
1764 if (ispipe) {
1765 helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
1766 /* Terminate the string before the first option */
1767 delimit = strchr(corename, ' ');
1768 if (delimit)
1769 *delimit = '\0';
1770 delimit = strrchr(helper_argv[0], '/');
1771 if (delimit)
1772 delimit++;
1773 else
1774 delimit = helper_argv[0];
1775 if (!strcmp(delimit, current->comm)) {
1776 printk(KERN_NOTICE "Recursive core dump detected, "
1777 "aborting\n");
1778 goto fail_unlock;
1779 }
1780
1781 core_limit = RLIM_INFINITY;
1782
1783 /* SIGPIPE can happen, but it's just never processed */
1784 if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
1785 &file)) {
1786 printk(KERN_INFO "Core dump to %s pipe failed\n",
1787 corename);
1788 goto fail_unlock;
1789 }
1790 } else
1791 file = filp_open(corename,
1792 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1793 0600);
1794 if (IS_ERR(file))
1795 goto fail_unlock;
1796 inode = file->f_path.dentry->d_inode;
1797 if (inode->i_nlink > 1)
1798 goto close_fail; /* multiple links - don't dump */
1799 if (!ispipe && d_unhashed(file->f_path.dentry))
1800 goto close_fail;
1801
1802 /* AK: actually i see no reason to not allow this for named pipes etc.,
1803 but keep the previous behaviour for now. */
1804 if (!ispipe && !S_ISREG(inode->i_mode))
1805 goto close_fail;
1806 if (!file->f_op)
1807 goto close_fail;
1808 if (!file->f_op->write)
1809 goto close_fail;
1810 if (!ispipe && do_truncate(file->f_path.dentry, 0, 0, file) != 0)
1811 goto close_fail;
1812
1813 retval = binfmt->core_dump(signr, regs, file, core_limit);
1814
1815 if (retval)
1816 current->signal->group_exit_code |= 0x80;
1817 close_fail:
1818 filp_close(file, NULL);
1819 fail_unlock:
1820 if (helper_argv)
1821 argv_free(helper_argv);
1822
1823 current->fsuid = fsuid;
1824 complete_all(&mm->core_done);
1825 fail:
1826 return retval;
1827 }