projects/linux·blob v2.6.35-rc4 · refs

2007 lines · 46.4 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/fdtable.h>
28#include <linux/mm.h>
29#include <linux/stat.h>
30#include <linux/fcntl.h>
31#include <linux/smp_lock.h>
32#include <linux/swap.h>
33#include <linux/string.h>
34#include <linux/init.h>
35#include <linux/pagemap.h>
36#include <linux/perf_event.h>
37#include <linux/highmem.h>
38#include <linux/spinlock.h>
39#include <linux/key.h>
40#include <linux/personality.h>
41#include <linux/binfmts.h>
42#include <linux/utsname.h>
43#include <linux/pid_namespace.h>
44#include <linux/module.h>
45#include <linux/namei.h>
46#include <linux/proc_fs.h>
47#include <linux/mount.h>
48#include <linux/security.h>
49#include <linux/syscalls.h>
50#include <linux/tsacct_kern.h>
51#include <linux/cn_proc.h>
52#include <linux/audit.h>
53#include <linux/tracehook.h>
54#include <linux/kmod.h>
55#include <linux/fsnotify.h>
56#include <linux/fs_struct.h>
57#include <linux/pipe_fs_i.h>
58
59#include <asm/uaccess.h>
60#include <asm/mmu_context.h>
61#include <asm/tlb.h>
62#include "internal.h"
63
64int core_uses_pid;
65char core_pattern[CORENAME_MAX_SIZE] = "core";
66unsigned int core_pipe_limit;
67int suid_dumpable = 0;
68
69/* The maximal length of core_pattern is also specified in sysctl.c */
70
71static LIST_HEAD(formats);
72static DEFINE_RWLOCK(binfmt_lock);
73
74int __register_binfmt(struct linux_binfmt * fmt, int insert)
75{
76 if (!fmt)
77 return -EINVAL;
78 write_lock(&binfmt_lock);
79 insert ? list_add(&fmt->lh, &formats) :
80 list_add_tail(&fmt->lh, &formats);
81 write_unlock(&binfmt_lock);
82 return 0;
83}
84
85EXPORT_SYMBOL(__register_binfmt);
86
87void unregister_binfmt(struct linux_binfmt * fmt)
88{
89 write_lock(&binfmt_lock);
90 list_del(&fmt->lh);
91 write_unlock(&binfmt_lock);
92}
93
94EXPORT_SYMBOL(unregister_binfmt);
95
96static inline void put_binfmt(struct linux_binfmt * fmt)
97{
98 module_put(fmt->module);
99}
100
101/*
102 * Note that a shared library must be both readable and executable due to
103 * security reasons.
104 *
105 * Also note that we take the address to load from from the file itself.
106 */
107SYSCALL_DEFINE1(uselib, const char __user *, library)
108{
109 struct file *file;
110 char *tmp = getname(library);
111 int error = PTR_ERR(tmp);
112
113 if (IS_ERR(tmp))
114 goto out;
115
116 file = do_filp_open(AT_FDCWD, tmp,
117 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
118 MAY_READ | MAY_EXEC | MAY_OPEN);
119 putname(tmp);
120 error = PTR_ERR(file);
121 if (IS_ERR(file))
122 goto out;
123
124 error = -EINVAL;
125 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
126 goto exit;
127
128 error = -EACCES;
129 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
130 goto exit;
131
132 fsnotify_open(file->f_path.dentry);
133
134 error = -ENOEXEC;
135 if(file->f_op) {
136 struct linux_binfmt * fmt;
137
138 read_lock(&binfmt_lock);
139 list_for_each_entry(fmt, &formats, lh) {
140 if (!fmt->load_shlib)
141 continue;
142 if (!try_module_get(fmt->module))
143 continue;
144 read_unlock(&binfmt_lock);
145 error = fmt->load_shlib(file);
146 read_lock(&binfmt_lock);
147 put_binfmt(fmt);
148 if (error != -ENOEXEC)
149 break;
150 }
151 read_unlock(&binfmt_lock);
152 }
153exit:
154 fput(file);
155out:
156 return error;
157}
158
159#ifdef CONFIG_MMU
160
161static 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 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
181 struct rlimit *rlim;
182
183 /*
184 * We've historically supported up to 32 pages (ARG_MAX)
185 * of argument strings even with small stacks
186 */
187 if (size <= ARG_MAX)
188 return page;
189
190 /*
191 * Limit to 1/4-th the stack size for the argv+env strings.
192 * This ensures that:
193 * - the remaining binfmt code will not run out of stack space,
194 * - the program will have a reasonable amount of stack left
195 * to work from.
196 */
197 rlim = current->signal->rlim;
198 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
199 put_page(page);
200 return NULL;
201 }
202 }
203
204 return page;
205}
206
207static void put_arg_page(struct page *page)
208{
209 put_page(page);
210}
211
212static void free_arg_page(struct linux_binprm *bprm, int i)
213{
214}
215
216static void free_arg_pages(struct linux_binprm *bprm)
217{
218}
219
220static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
221 struct page *page)
222{
223 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
224}
225
226static int __bprm_mm_init(struct linux_binprm *bprm)
227{
228 int err;
229 struct vm_area_struct *vma = NULL;
230 struct mm_struct *mm = bprm->mm;
231
232 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
233 if (!vma)
234 return -ENOMEM;
235
236 down_write(&mm->mmap_sem);
237 vma->vm_mm = mm;
238
239 /*
240 * Place the stack at the largest stack address the architecture
241 * supports. Later, we'll move this to an appropriate place. We don't
242 * use STACK_TOP because that can depend on attributes which aren't
243 * configured yet.
244 */
245 BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
246 vma->vm_end = STACK_TOP_MAX;
247 vma->vm_start = vma->vm_end - PAGE_SIZE;
248 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
249 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
250 INIT_LIST_HEAD(&vma->anon_vma_chain);
251 err = insert_vm_struct(mm, vma);
252 if (err)
253 goto err;
254
255 mm->stack_vm = mm->total_vm = 1;
256 up_write(&mm->mmap_sem);
257 bprm->p = vma->vm_end - sizeof(void *);
258 return 0;
259err:
260 up_write(&mm->mmap_sem);
261 bprm->vma = NULL;
262 kmem_cache_free(vm_area_cachep, vma);
263 return err;
264}
265
266static bool valid_arg_len(struct linux_binprm *bprm, long len)
267{
268 return len <= MAX_ARG_STRLEN;
269}
270
271#else
272
273static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
274 int write)
275{
276 struct page *page;
277
278 page = bprm->page[pos / PAGE_SIZE];
279 if (!page && write) {
280 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
281 if (!page)
282 return NULL;
283 bprm->page[pos / PAGE_SIZE] = page;
284 }
285
286 return page;
287}
288
289static void put_arg_page(struct page *page)
290{
291}
292
293static void free_arg_page(struct linux_binprm *bprm, int i)
294{
295 if (bprm->page[i]) {
296 __free_page(bprm->page[i]);
297 bprm->page[i] = NULL;
298 }
299}
300
301static void free_arg_pages(struct linux_binprm *bprm)
302{
303 int i;
304
305 for (i = 0; i < MAX_ARG_PAGES; i++)
306 free_arg_page(bprm, i);
307}
308
309static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
310 struct page *page)
311{
312}
313
314static int __bprm_mm_init(struct linux_binprm *bprm)
315{
316 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
317 return 0;
318}
319
320static bool valid_arg_len(struct linux_binprm *bprm, long len)
321{
322 return len <= bprm->p;
323}
324
325#endif /* CONFIG_MMU */
326
327/*
328 * Create a new mm_struct and populate it with a temporary stack
329 * vm_area_struct. We don't have enough context at this point to set the stack
330 * flags, permissions, and offset, so we use temporary values. We'll update
331 * them later in setup_arg_pages().
332 */
333int bprm_mm_init(struct linux_binprm *bprm)
334{
335 int err;
336 struct mm_struct *mm = NULL;
337
338 bprm->mm = mm = mm_alloc();
339 err = -ENOMEM;
340 if (!mm)
341 goto err;
342
343 err = init_new_context(current, mm);
344 if (err)
345 goto err;
346
347 err = __bprm_mm_init(bprm);
348 if (err)
349 goto err;
350
351 return 0;
352
353err:
354 if (mm) {
355 bprm->mm = NULL;
356 mmdrop(mm);
357 }
358
359 return err;
360}
361
362/*
363 * count() counts the number of strings in array ARGV.
364 */
365static int count(char __user * __user * argv, int max)
366{
367 int i = 0;
368
369 if (argv != NULL) {
370 for (;;) {
371 char __user * p;
372
373 if (get_user(p, argv))
374 return -EFAULT;
375 if (!p)
376 break;
377 argv++;
378 if (i++ >= max)
379 return -E2BIG;
380 cond_resched();
381 }
382 }
383 return i;
384}
385
386/*
387 * 'copy_strings()' copies argument/environment strings from the old
388 * processes's memory to the new process's stack. The call to get_user_pages()
389 * ensures the destination page is created and not swapped out.
390 */
391static int copy_strings(int argc, char __user * __user * argv,
392 struct linux_binprm *bprm)
393{
394 struct page *kmapped_page = NULL;
395 char *kaddr = NULL;
396 unsigned long kpos = 0;
397 int ret;
398
399 while (argc-- > 0) {
400 char __user *str;
401 int len;
402 unsigned long pos;
403
404 if (get_user(str, argv+argc) ||
405 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
406 ret = -EFAULT;
407 goto out;
408 }
409
410 if (!valid_arg_len(bprm, len)) {
411 ret = -E2BIG;
412 goto out;
413 }
414
415 /* We're going to work our way backwords. */
416 pos = bprm->p;
417 str += len;
418 bprm->p -= len;
419
420 while (len > 0) {
421 int offset, bytes_to_copy;
422
423 offset = pos % PAGE_SIZE;
424 if (offset == 0)
425 offset = PAGE_SIZE;
426
427 bytes_to_copy = offset;
428 if (bytes_to_copy > len)
429 bytes_to_copy = len;
430
431 offset -= bytes_to_copy;
432 pos -= bytes_to_copy;
433 str -= bytes_to_copy;
434 len -= bytes_to_copy;
435
436 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
437 struct page *page;
438
439 page = get_arg_page(bprm, pos, 1);
440 if (!page) {
441 ret = -E2BIG;
442 goto out;
443 }
444
445 if (kmapped_page) {
446 flush_kernel_dcache_page(kmapped_page);
447 kunmap(kmapped_page);
448 put_arg_page(kmapped_page);
449 }
450 kmapped_page = page;
451 kaddr = kmap(kmapped_page);
452 kpos = pos & PAGE_MASK;
453 flush_arg_page(bprm, kpos, kmapped_page);
454 }
455 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
456 ret = -EFAULT;
457 goto out;
458 }
459 }
460 }
461 ret = 0;
462out:
463 if (kmapped_page) {
464 flush_kernel_dcache_page(kmapped_page);
465 kunmap(kmapped_page);
466 put_arg_page(kmapped_page);
467 }
468 return ret;
469}
470
471/*
472 * Like copy_strings, but get argv and its values from kernel memory.
473 */
474int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
475{
476 int r;
477 mm_segment_t oldfs = get_fs();
478 set_fs(KERNEL_DS);
479 r = copy_strings(argc, (char __user * __user *)argv, bprm);
480 set_fs(oldfs);
481 return r;
482}
483EXPORT_SYMBOL(copy_strings_kernel);
484
485#ifdef CONFIG_MMU
486
487/*
488 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
489 * the binfmt code determines where the new stack should reside, we shift it to
490 * its final location. The process proceeds as follows:
491 *
492 * 1) Use shift to calculate the new vma endpoints.
493 * 2) Extend vma to cover both the old and new ranges. This ensures the
494 * arguments passed to subsequent functions are consistent.
495 * 3) Move vma's page tables to the new range.
496 * 4) Free up any cleared pgd range.
497 * 5) Shrink the vma to cover only the new range.
498 */
499static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
500{
501 struct mm_struct *mm = vma->vm_mm;
502 unsigned long old_start = vma->vm_start;
503 unsigned long old_end = vma->vm_end;
504 unsigned long length = old_end - old_start;
505 unsigned long new_start = old_start - shift;
506 unsigned long new_end = old_end - shift;
507 struct mmu_gather *tlb;
508
509 BUG_ON(new_start > new_end);
510
511 /*
512 * ensure there are no vmas between where we want to go
513 * and where we are
514 */
515 if (vma != find_vma(mm, new_start))
516 return -EFAULT;
517
518 /*
519 * cover the whole range: [new_start, old_end)
520 */
521 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
522 return -ENOMEM;
523
524 /*
525 * move the page tables downwards, on failure we rely on
526 * process cleanup to remove whatever mess we made.
527 */
528 if (length != move_page_tables(vma, old_start,
529 vma, new_start, length))
530 return -ENOMEM;
531
532 lru_add_drain();
533 tlb = tlb_gather_mmu(mm, 0);
534 if (new_end > old_start) {
535 /*
536 * when the old and new regions overlap clear from new_end.
537 */
538 free_pgd_range(tlb, new_end, old_end, new_end,
539 vma->vm_next ? vma->vm_next->vm_start : 0);
540 } else {
541 /*
542 * otherwise, clean from old_start; this is done to not touch
543 * the address space in [new_end, old_start) some architectures
544 * have constraints on va-space that make this illegal (IA64) -
545 * for the others its just a little faster.
546 */
547 free_pgd_range(tlb, old_start, old_end, new_end,
548 vma->vm_next ? vma->vm_next->vm_start : 0);
549 }
550 tlb_finish_mmu(tlb, new_end, old_end);
551
552 /*
553 * Shrink the vma to just the new range. Always succeeds.
554 */
555 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
556
557 return 0;
558}
559
560/*
561 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
562 * the stack is optionally relocated, and some extra space is added.
563 */
564int setup_arg_pages(struct linux_binprm *bprm,
565 unsigned long stack_top,
566 int executable_stack)
567{
568 unsigned long ret;
569 unsigned long stack_shift;
570 struct mm_struct *mm = current->mm;
571 struct vm_area_struct *vma = bprm->vma;
572 struct vm_area_struct *prev = NULL;
573 unsigned long vm_flags;
574 unsigned long stack_base;
575 unsigned long stack_size;
576 unsigned long stack_expand;
577 unsigned long rlim_stack;
578
579#ifdef CONFIG_STACK_GROWSUP
580 /* Limit stack size to 1GB */
581 stack_base = rlimit_max(RLIMIT_STACK);
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 = VM_STACK_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 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
621
622 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
623 vm_flags);
624 if (ret)
625 goto out_unlock;
626 BUG_ON(prev != vma);
627
628 /* Move stack pages down in memory. */
629 if (stack_shift) {
630 ret = shift_arg_pages(vma, stack_shift);
631 if (ret)
632 goto out_unlock;
633 }
634
635 /* mprotect_fixup is overkill to remove the temporary stack flags */
636 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
637
638 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
639 stack_size = vma->vm_end - vma->vm_start;
640 /*
641 * Align this down to a page boundary as expand_stack
642 * will align it up.
643 */
644 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
645#ifdef CONFIG_STACK_GROWSUP
646 if (stack_size + stack_expand > rlim_stack)
647 stack_base = vma->vm_start + rlim_stack;
648 else
649 stack_base = vma->vm_end + stack_expand;
650#else
651 if (stack_size + stack_expand > rlim_stack)
652 stack_base = vma->vm_end - rlim_stack;
653 else
654 stack_base = vma->vm_start - stack_expand;
655#endif
656 ret = expand_stack(vma, stack_base);
657 if (ret)
658 ret = -EFAULT;
659
660out_unlock:
661 up_write(&mm->mmap_sem);
662 return ret;
663}
664EXPORT_SYMBOL(setup_arg_pages);
665
666#endif /* CONFIG_MMU */
667
668struct file *open_exec(const char *name)
669{
670 struct file *file;
671 int err;
672
673 file = do_filp_open(AT_FDCWD, name,
674 O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
675 MAY_EXEC | MAY_OPEN);
676 if (IS_ERR(file))
677 goto out;
678
679 err = -EACCES;
680 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
681 goto exit;
682
683 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
684 goto exit;
685
686 fsnotify_open(file->f_path.dentry);
687
688 err = deny_write_access(file);
689 if (err)
690 goto exit;
691
692out:
693 return file;
694
695exit:
696 fput(file);
697 return ERR_PTR(err);
698}
699EXPORT_SYMBOL(open_exec);
700
701int kernel_read(struct file *file, loff_t offset,
702 char *addr, unsigned long count)
703{
704 mm_segment_t old_fs;
705 loff_t pos = offset;
706 int result;
707
708 old_fs = get_fs();
709 set_fs(get_ds());
710 /* The cast to a user pointer is valid due to the set_fs() */
711 result = vfs_read(file, (void __user *)addr, count, &pos);
712 set_fs(old_fs);
713 return result;
714}
715
716EXPORT_SYMBOL(kernel_read);
717
718static int exec_mmap(struct mm_struct *mm)
719{
720 struct task_struct *tsk;
721 struct mm_struct * old_mm, *active_mm;
722
723 /* Notify parent that we're no longer interested in the old VM */
724 tsk = current;
725 old_mm = current->mm;
726 sync_mm_rss(tsk, old_mm);
727 mm_release(tsk, old_mm);
728
729 if (old_mm) {
730 /*
731 * Make sure that if there is a core dump in progress
732 * for the old mm, we get out and die instead of going
733 * through with the exec. We must hold mmap_sem around
734 * checking core_state and changing tsk->mm.
735 */
736 down_read(&old_mm->mmap_sem);
737 if (unlikely(old_mm->core_state)) {
738 up_read(&old_mm->mmap_sem);
739 return -EINTR;
740 }
741 }
742 task_lock(tsk);
743 active_mm = tsk->active_mm;
744 tsk->mm = mm;
745 tsk->active_mm = mm;
746 activate_mm(active_mm, mm);
747 task_unlock(tsk);
748 arch_pick_mmap_layout(mm);
749 if (old_mm) {
750 up_read(&old_mm->mmap_sem);
751 BUG_ON(active_mm != old_mm);
752 mm_update_next_owner(old_mm);
753 mmput(old_mm);
754 return 0;
755 }
756 mmdrop(active_mm);
757 return 0;
758}
759
760/*
761 * This function makes sure the current process has its own signal table,
762 * so that flush_signal_handlers can later reset the handlers without
763 * disturbing other processes. (Other processes might share the signal
764 * table via the CLONE_SIGHAND option to clone().)
765 */
766static int de_thread(struct task_struct *tsk)
767{
768 struct signal_struct *sig = tsk->signal;
769 struct sighand_struct *oldsighand = tsk->sighand;
770 spinlock_t *lock = &oldsighand->siglock;
771
772 if (thread_group_empty(tsk))
773 goto no_thread_group;
774
775 /*
776 * Kill all other threads in the thread group.
777 */
778 spin_lock_irq(lock);
779 if (signal_group_exit(sig)) {
780 /*
781 * Another group action in progress, just
782 * return so that the signal is processed.
783 */
784 spin_unlock_irq(lock);
785 return -EAGAIN;
786 }
787
788 sig->group_exit_task = tsk;
789 sig->notify_count = zap_other_threads(tsk);
790 if (!thread_group_leader(tsk))
791 sig->notify_count--;
792
793 while (sig->notify_count) {
794 __set_current_state(TASK_UNINTERRUPTIBLE);
795 spin_unlock_irq(lock);
796 schedule();
797 spin_lock_irq(lock);
798 }
799 spin_unlock_irq(lock);
800
801 /*
802 * At this point all other threads have exited, all we have to
803 * do is to wait for the thread group leader to become inactive,
804 * and to assume its PID:
805 */
806 if (!thread_group_leader(tsk)) {
807 struct task_struct *leader = tsk->group_leader;
808
809 sig->notify_count = -1; /* for exit_notify() */
810 for (;;) {
811 write_lock_irq(&tasklist_lock);
812 if (likely(leader->exit_state))
813 break;
814 __set_current_state(TASK_UNINTERRUPTIBLE);
815 write_unlock_irq(&tasklist_lock);
816 schedule();
817 }
818
819 /*
820 * The only record we have of the real-time age of a
821 * process, regardless of execs it's done, is start_time.
822 * All the past CPU time is accumulated in signal_struct
823 * from sister threads now dead. But in this non-leader
824 * exec, nothing survives from the original leader thread,
825 * whose birth marks the true age of this process now.
826 * When we take on its identity by switching to its PID, we
827 * also take its birthdate (always earlier than our own).
828 */
829 tsk->start_time = leader->start_time;
830
831 BUG_ON(!same_thread_group(leader, tsk));
832 BUG_ON(has_group_leader_pid(tsk));
833 /*
834 * An exec() starts a new thread group with the
835 * TGID of the previous thread group. Rehash the
836 * two threads with a switched PID, and release
837 * the former thread group leader:
838 */
839
840 /* Become a process group leader with the old leader's pid.
841 * The old leader becomes a thread of the this thread group.
842 * Note: The old leader also uses this pid until release_task
843 * is called. Odd but simple and correct.
844 */
845 detach_pid(tsk, PIDTYPE_PID);
846 tsk->pid = leader->pid;
847 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
848 transfer_pid(leader, tsk, PIDTYPE_PGID);
849 transfer_pid(leader, tsk, PIDTYPE_SID);
850
851 list_replace_rcu(&leader->tasks, &tsk->tasks);
852 list_replace_init(&leader->sibling, &tsk->sibling);
853
854 tsk->group_leader = tsk;
855 leader->group_leader = tsk;
856
857 tsk->exit_signal = SIGCHLD;
858
859 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
860 leader->exit_state = EXIT_DEAD;
861 write_unlock_irq(&tasklist_lock);
862
863 release_task(leader);
864 }
865
866 sig->group_exit_task = NULL;
867 sig->notify_count = 0;
868
869no_thread_group:
870 if (current->mm)
871 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
872
873 exit_itimers(sig);
874 flush_itimer_signals();
875
876 if (atomic_read(&oldsighand->count) != 1) {
877 struct sighand_struct *newsighand;
878 /*
879 * This ->sighand is shared with the CLONE_SIGHAND
880 * but not CLONE_THREAD task, switch to the new one.
881 */
882 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
883 if (!newsighand)
884 return -ENOMEM;
885
886 atomic_set(&newsighand->count, 1);
887 memcpy(newsighand->action, oldsighand->action,
888 sizeof(newsighand->action));
889
890 write_lock_irq(&tasklist_lock);
891 spin_lock(&oldsighand->siglock);
892 rcu_assign_pointer(tsk->sighand, newsighand);
893 spin_unlock(&oldsighand->siglock);
894 write_unlock_irq(&tasklist_lock);
895
896 __cleanup_sighand(oldsighand);
897 }
898
899 BUG_ON(!thread_group_leader(tsk));
900 return 0;
901}
902
903/*
904 * These functions flushes out all traces of the currently running executable
905 * so that a new one can be started
906 */
907static void flush_old_files(struct files_struct * files)
908{
909 long j = -1;
910 struct fdtable *fdt;
911
912 spin_lock(&files->file_lock);
913 for (;;) {
914 unsigned long set, i;
915
916 j++;
917 i = j * __NFDBITS;
918 fdt = files_fdtable(files);
919 if (i >= fdt->max_fds)
920 break;
921 set = fdt->close_on_exec->fds_bits[j];
922 if (!set)
923 continue;
924 fdt->close_on_exec->fds_bits[j] = 0;
925 spin_unlock(&files->file_lock);
926 for ( ; set ; i++,set >>= 1) {
927 if (set & 1) {
928 sys_close(i);
929 }
930 }
931 spin_lock(&files->file_lock);
932
933 }
934 spin_unlock(&files->file_lock);
935}
936
937char *get_task_comm(char *buf, struct task_struct *tsk)
938{
939 /* buf must be at least sizeof(tsk->comm) in size */
940 task_lock(tsk);
941 strncpy(buf, tsk->comm, sizeof(tsk->comm));
942 task_unlock(tsk);
943 return buf;
944}
945
946void set_task_comm(struct task_struct *tsk, char *buf)
947{
948 task_lock(tsk);
949
950 /*
951 * Threads may access current->comm without holding
952 * the task lock, so write the string carefully.
953 * Readers without a lock may see incomplete new
954 * names but are safe from non-terminating string reads.
955 */
956 memset(tsk->comm, 0, TASK_COMM_LEN);
957 wmb();
958 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
959 task_unlock(tsk);
960 perf_event_comm(tsk);
961}
962
963int flush_old_exec(struct linux_binprm * bprm)
964{
965 int retval;
966
967 /*
968 * Make sure we have a private signal table and that
969 * we are unassociated from the previous thread group.
970 */
971 retval = de_thread(current);
972 if (retval)
973 goto out;
974
975 set_mm_exe_file(bprm->mm, bprm->file);
976
977 /*
978 * Release all of the old mmap stuff
979 */
980 retval = exec_mmap(bprm->mm);
981 if (retval)
982 goto out;
983
984 bprm->mm = NULL; /* We're using it now */
985
986 current->flags &= ~PF_RANDOMIZE;
987 flush_thread();
988 current->personality &= ~bprm->per_clear;
989
990 return 0;
991
992out:
993 return retval;
994}
995EXPORT_SYMBOL(flush_old_exec);
996
997void setup_new_exec(struct linux_binprm * bprm)
998{
999 int i, ch;
1000 char * name;
1001 char tcomm[sizeof(current->comm)];
1002
1003 arch_pick_mmap_layout(current->mm);
1004
1005 /* This is the point of no return */
1006 current->sas_ss_sp = current->sas_ss_size = 0;
1007
1008 if (current_euid() == current_uid() && current_egid() == current_gid())
1009 set_dumpable(current->mm, 1);
1010 else
1011 set_dumpable(current->mm, suid_dumpable);
1012
1013 name = bprm->filename;
1014
1015 /* Copies the binary name from after last slash */
1016 for (i=0; (ch = *(name++)) != '\0';) {
1017 if (ch == '/')
1018 i = 0; /* overwrite what we wrote */
1019 else
1020 if (i < (sizeof(tcomm) - 1))
1021 tcomm[i++] = ch;
1022 }
1023 tcomm[i] = '\0';
1024 set_task_comm(current, tcomm);
1025
1026 /* Set the new mm task size. We have to do that late because it may
1027 * depend on TIF_32BIT which is only updated in flush_thread() on
1028 * some architectures like powerpc
1029 */
1030 current->mm->task_size = TASK_SIZE;
1031
1032 /* install the new credentials */
1033 if (bprm->cred->uid != current_euid() ||
1034 bprm->cred->gid != current_egid()) {
1035 current->pdeath_signal = 0;
1036 } else if (file_permission(bprm->file, MAY_READ) ||
1037 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1038 set_dumpable(current->mm, suid_dumpable);
1039 }
1040
1041 /*
1042 * Flush performance counters when crossing a
1043 * security domain:
1044 */
1045 if (!get_dumpable(current->mm))
1046 perf_event_exit_task(current);
1047
1048 /* An exec changes our domain. We are no longer part of the thread
1049 group */
1050
1051 current->self_exec_id++;
1052
1053 flush_signal_handlers(current, 0);
1054 flush_old_files(current->files);
1055}
1056EXPORT_SYMBOL(setup_new_exec);
1057
1058/*
1059 * Prepare credentials and lock ->cred_guard_mutex.
1060 * install_exec_creds() commits the new creds and drops the lock.
1061 * Or, if exec fails before, free_bprm() should release ->cred and
1062 * and unlock.
1063 */
1064int prepare_bprm_creds(struct linux_binprm *bprm)
1065{
1066 if (mutex_lock_interruptible(&current->cred_guard_mutex))
1067 return -ERESTARTNOINTR;
1068
1069 bprm->cred = prepare_exec_creds();
1070 if (likely(bprm->cred))
1071 return 0;
1072
1073 mutex_unlock(&current->cred_guard_mutex);
1074 return -ENOMEM;
1075}
1076
1077void free_bprm(struct linux_binprm *bprm)
1078{
1079 free_arg_pages(bprm);
1080 if (bprm->cred) {
1081 mutex_unlock(&current->cred_guard_mutex);
1082 abort_creds(bprm->cred);
1083 }
1084 kfree(bprm);
1085}
1086
1087/*
1088 * install the new credentials for this executable
1089 */
1090void install_exec_creds(struct linux_binprm *bprm)
1091{
1092 security_bprm_committing_creds(bprm);
1093
1094 commit_creds(bprm->cred);
1095 bprm->cred = NULL;
1096 /*
1097 * cred_guard_mutex must be held at least to this point to prevent
1098 * ptrace_attach() from altering our determination of the task's
1099 * credentials; any time after this it may be unlocked.
1100 */
1101 security_bprm_committed_creds(bprm);
1102 mutex_unlock(&current->cred_guard_mutex);
1103}
1104EXPORT_SYMBOL(install_exec_creds);
1105
1106/*
1107 * determine how safe it is to execute the proposed program
1108 * - the caller must hold current->cred_guard_mutex to protect against
1109 * PTRACE_ATTACH
1110 */
1111int check_unsafe_exec(struct linux_binprm *bprm)
1112{
1113 struct task_struct *p = current, *t;
1114 unsigned n_fs;
1115 int res = 0;
1116
1117 bprm->unsafe = tracehook_unsafe_exec(p);
1118
1119 n_fs = 1;
1120 write_lock(&p->fs->lock);
1121 rcu_read_lock();
1122 for (t = next_thread(p); t != p; t = next_thread(t)) {
1123 if (t->fs == p->fs)
1124 n_fs++;
1125 }
1126 rcu_read_unlock();
1127
1128 if (p->fs->users > n_fs) {
1129 bprm->unsafe |= LSM_UNSAFE_SHARE;
1130 } else {
1131 res = -EAGAIN;
1132 if (!p->fs->in_exec) {
1133 p->fs->in_exec = 1;
1134 res = 1;
1135 }
1136 }
1137 write_unlock(&p->fs->lock);
1138
1139 return res;
1140}
1141
1142/*
1143 * Fill the binprm structure from the inode.
1144 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1145 *
1146 * This may be called multiple times for binary chains (scripts for example).
1147 */
1148int prepare_binprm(struct linux_binprm *bprm)
1149{
1150 umode_t mode;
1151 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1152 int retval;
1153
1154 mode = inode->i_mode;
1155 if (bprm->file->f_op == NULL)
1156 return -EACCES;
1157
1158 /* clear any previous set[ug]id data from a previous binary */
1159 bprm->cred->euid = current_euid();
1160 bprm->cred->egid = current_egid();
1161
1162 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1163 /* Set-uid? */
1164 if (mode & S_ISUID) {
1165 bprm->per_clear |= PER_CLEAR_ON_SETID;
1166 bprm->cred->euid = inode->i_uid;
1167 }
1168
1169 /* Set-gid? */
1170 /*
1171 * If setgid is set but no group execute bit then this
1172 * is a candidate for mandatory locking, not a setgid
1173 * executable.
1174 */
1175 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1176 bprm->per_clear |= PER_CLEAR_ON_SETID;
1177 bprm->cred->egid = inode->i_gid;
1178 }
1179 }
1180
1181 /* fill in binprm security blob */
1182 retval = security_bprm_set_creds(bprm);
1183 if (retval)
1184 return retval;
1185 bprm->cred_prepared = 1;
1186
1187 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1188 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1189}
1190
1191EXPORT_SYMBOL(prepare_binprm);
1192
1193/*
1194 * Arguments are '\0' separated strings found at the location bprm->p
1195 * points to; chop off the first by relocating brpm->p to right after
1196 * the first '\0' encountered.
1197 */
1198int remove_arg_zero(struct linux_binprm *bprm)
1199{
1200 int ret = 0;
1201 unsigned long offset;
1202 char *kaddr;
1203 struct page *page;
1204
1205 if (!bprm->argc)
1206 return 0;
1207
1208 do {
1209 offset = bprm->p & ~PAGE_MASK;
1210 page = get_arg_page(bprm, bprm->p, 0);
1211 if (!page) {
1212 ret = -EFAULT;
1213 goto out;
1214 }
1215 kaddr = kmap_atomic(page, KM_USER0);
1216
1217 for (; offset < PAGE_SIZE && kaddr[offset];
1218 offset++, bprm->p++)
1219 ;
1220
1221 kunmap_atomic(kaddr, KM_USER0);
1222 put_arg_page(page);
1223
1224 if (offset == PAGE_SIZE)
1225 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1226 } while (offset == PAGE_SIZE);
1227
1228 bprm->p++;
1229 bprm->argc--;
1230 ret = 0;
1231
1232out:
1233 return ret;
1234}
1235EXPORT_SYMBOL(remove_arg_zero);
1236
1237/*
1238 * cycle the list of binary formats handler, until one recognizes the image
1239 */
1240int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1241{
1242 unsigned int depth = bprm->recursion_depth;
1243 int try,retval;
1244 struct linux_binfmt *fmt;
1245
1246 retval = security_bprm_check(bprm);
1247 if (retval)
1248 return retval;
1249
1250 /* kernel module loader fixup */
1251 /* so we don't try to load run modprobe in kernel space. */
1252 set_fs(USER_DS);
1253
1254 retval = audit_bprm(bprm);
1255 if (retval)
1256 return retval;
1257
1258 retval = -ENOENT;
1259 for (try=0; try<2; try++) {
1260 read_lock(&binfmt_lock);
1261 list_for_each_entry(fmt, &formats, lh) {
1262 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1263 if (!fn)
1264 continue;
1265 if (!try_module_get(fmt->module))
1266 continue;
1267 read_unlock(&binfmt_lock);
1268 retval = fn(bprm, regs);
1269 /*
1270 * Restore the depth counter to its starting value
1271 * in this call, so we don't have to rely on every
1272 * load_binary function to restore it on return.
1273 */
1274 bprm->recursion_depth = depth;
1275 if (retval >= 0) {
1276 if (depth == 0)
1277 tracehook_report_exec(fmt, bprm, regs);
1278 put_binfmt(fmt);
1279 allow_write_access(bprm->file);
1280 if (bprm->file)
1281 fput(bprm->file);
1282 bprm->file = NULL;
1283 current->did_exec = 1;
1284 proc_exec_connector(current);
1285 return retval;
1286 }
1287 read_lock(&binfmt_lock);
1288 put_binfmt(fmt);
1289 if (retval != -ENOEXEC || bprm->mm == NULL)
1290 break;
1291 if (!bprm->file) {
1292 read_unlock(&binfmt_lock);
1293 return retval;
1294 }
1295 }
1296 read_unlock(&binfmt_lock);
1297 if (retval != -ENOEXEC || bprm->mm == NULL) {
1298 break;
1299#ifdef CONFIG_MODULES
1300 } else {
1301#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1302 if (printable(bprm->buf[0]) &&
1303 printable(bprm->buf[1]) &&
1304 printable(bprm->buf[2]) &&
1305 printable(bprm->buf[3]))
1306 break; /* -ENOEXEC */
1307 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1308#endif
1309 }
1310 }
1311 return retval;
1312}
1313
1314EXPORT_SYMBOL(search_binary_handler);
1315
1316/*
1317 * sys_execve() executes a new program.
1318 */
1319int do_execve(char * filename,
1320 char __user *__user *argv,
1321 char __user *__user *envp,
1322 struct pt_regs * regs)
1323{
1324 struct linux_binprm *bprm;
1325 struct file *file;
1326 struct files_struct *displaced;
1327 bool clear_in_exec;
1328 int retval;
1329
1330 retval = unshare_files(&displaced);
1331 if (retval)
1332 goto out_ret;
1333
1334 retval = -ENOMEM;
1335 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1336 if (!bprm)
1337 goto out_files;
1338
1339 retval = prepare_bprm_creds(bprm);
1340 if (retval)
1341 goto out_free;
1342
1343 retval = check_unsafe_exec(bprm);
1344 if (retval < 0)
1345 goto out_free;
1346 clear_in_exec = retval;
1347 current->in_execve = 1;
1348
1349 file = open_exec(filename);
1350 retval = PTR_ERR(file);
1351 if (IS_ERR(file))
1352 goto out_unmark;
1353
1354 sched_exec();
1355
1356 bprm->file = file;
1357 bprm->filename = filename;
1358 bprm->interp = filename;
1359
1360 retval = bprm_mm_init(bprm);
1361 if (retval)
1362 goto out_file;
1363
1364 bprm->argc = count(argv, MAX_ARG_STRINGS);
1365 if ((retval = bprm->argc) < 0)
1366 goto out;
1367
1368 bprm->envc = count(envp, MAX_ARG_STRINGS);
1369 if ((retval = bprm->envc) < 0)
1370 goto out;
1371
1372 retval = prepare_binprm(bprm);
1373 if (retval < 0)
1374 goto out;
1375
1376 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1377 if (retval < 0)
1378 goto out;
1379
1380 bprm->exec = bprm->p;
1381 retval = copy_strings(bprm->envc, envp, bprm);
1382 if (retval < 0)
1383 goto out;
1384
1385 retval = copy_strings(bprm->argc, argv, bprm);
1386 if (retval < 0)
1387 goto out;
1388
1389 current->flags &= ~PF_KTHREAD;
1390 retval = search_binary_handler(bprm,regs);
1391 if (retval < 0)
1392 goto out;
1393
1394 /* execve succeeded */
1395 current->fs->in_exec = 0;
1396 current->in_execve = 0;
1397 acct_update_integrals(current);
1398 free_bprm(bprm);
1399 if (displaced)
1400 put_files_struct(displaced);
1401 return retval;
1402
1403out:
1404 if (bprm->mm)
1405 mmput (bprm->mm);
1406
1407out_file:
1408 if (bprm->file) {
1409 allow_write_access(bprm->file);
1410 fput(bprm->file);
1411 }
1412
1413out_unmark:
1414 if (clear_in_exec)
1415 current->fs->in_exec = 0;
1416 current->in_execve = 0;
1417
1418out_free:
1419 free_bprm(bprm);
1420
1421out_files:
1422 if (displaced)
1423 reset_files_struct(displaced);
1424out_ret:
1425 return retval;
1426}
1427
1428void set_binfmt(struct linux_binfmt *new)
1429{
1430 struct mm_struct *mm = current->mm;
1431
1432 if (mm->binfmt)
1433 module_put(mm->binfmt->module);
1434
1435 mm->binfmt = new;
1436 if (new)
1437 __module_get(new->module);
1438}
1439
1440EXPORT_SYMBOL(set_binfmt);
1441
1442/* format_corename will inspect the pattern parameter, and output a
1443 * name into corename, which must have space for at least
1444 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1445 */
1446static int format_corename(char *corename, long signr)
1447{
1448 const struct cred *cred = current_cred();
1449 const char *pat_ptr = core_pattern;
1450 int ispipe = (*pat_ptr == '|');
1451 char *out_ptr = corename;
1452 char *const out_end = corename + CORENAME_MAX_SIZE;
1453 int rc;
1454 int pid_in_pattern = 0;
1455
1456 /* Repeat as long as we have more pattern to process and more output
1457 space */
1458 while (*pat_ptr) {
1459 if (*pat_ptr != '%') {
1460 if (out_ptr == out_end)
1461 goto out;
1462 *out_ptr++ = *pat_ptr++;
1463 } else {
1464 switch (*++pat_ptr) {
1465 case 0:
1466 goto out;
1467 /* Double percent, output one percent */
1468 case '%':
1469 if (out_ptr == out_end)
1470 goto out;
1471 *out_ptr++ = '%';
1472 break;
1473 /* pid */
1474 case 'p':
1475 pid_in_pattern = 1;
1476 rc = snprintf(out_ptr, out_end - out_ptr,
1477 "%d", task_tgid_vnr(current));
1478 if (rc > out_end - out_ptr)
1479 goto out;
1480 out_ptr += rc;
1481 break;
1482 /* uid */
1483 case 'u':
1484 rc = snprintf(out_ptr, out_end - out_ptr,
1485 "%d", cred->uid);
1486 if (rc > out_end - out_ptr)
1487 goto out;
1488 out_ptr += rc;
1489 break;
1490 /* gid */
1491 case 'g':
1492 rc = snprintf(out_ptr, out_end - out_ptr,
1493 "%d", cred->gid);
1494 if (rc > out_end - out_ptr)
1495 goto out;
1496 out_ptr += rc;
1497 break;
1498 /* signal that caused the coredump */
1499 case 's':
1500 rc = snprintf(out_ptr, out_end - out_ptr,
1501 "%ld", signr);
1502 if (rc > out_end - out_ptr)
1503 goto out;
1504 out_ptr += rc;
1505 break;
1506 /* UNIX time of coredump */
1507 case 't': {
1508 struct timeval tv;
1509 do_gettimeofday(&tv);
1510 rc = snprintf(out_ptr, out_end - out_ptr,
1511 "%lu", tv.tv_sec);
1512 if (rc > out_end - out_ptr)
1513 goto out;
1514 out_ptr += rc;
1515 break;
1516 }
1517 /* hostname */
1518 case 'h':
1519 down_read(&uts_sem);
1520 rc = snprintf(out_ptr, out_end - out_ptr,
1521 "%s", utsname()->nodename);
1522 up_read(&uts_sem);
1523 if (rc > out_end - out_ptr)
1524 goto out;
1525 out_ptr += rc;
1526 break;
1527 /* executable */
1528 case 'e':
1529 rc = snprintf(out_ptr, out_end - out_ptr,
1530 "%s", current->comm);
1531 if (rc > out_end - out_ptr)
1532 goto out;
1533 out_ptr += rc;
1534 break;
1535 /* core limit size */
1536 case 'c':
1537 rc = snprintf(out_ptr, out_end - out_ptr,
1538 "%lu", rlimit(RLIMIT_CORE));
1539 if (rc > out_end - out_ptr)
1540 goto out;
1541 out_ptr += rc;
1542 break;
1543 default:
1544 break;
1545 }
1546 ++pat_ptr;
1547 }
1548 }
1549 /* Backward compatibility with core_uses_pid:
1550 *
1551 * If core_pattern does not include a %p (as is the default)
1552 * and core_uses_pid is set, then .%pid will be appended to
1553 * the filename. Do not do this for piped commands. */
1554 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1555 rc = snprintf(out_ptr, out_end - out_ptr,
1556 ".%d", task_tgid_vnr(current));
1557 if (rc > out_end - out_ptr)
1558 goto out;
1559 out_ptr += rc;
1560 }
1561out:
1562 *out_ptr = 0;
1563 return ispipe;
1564}
1565
1566static int zap_process(struct task_struct *start, int exit_code)
1567{
1568 struct task_struct *t;
1569 int nr = 0;
1570
1571 start->signal->flags = SIGNAL_GROUP_EXIT;
1572 start->signal->group_exit_code = exit_code;
1573 start->signal->group_stop_count = 0;
1574
1575 t = start;
1576 do {
1577 if (t != current && t->mm) {
1578 sigaddset(&t->pending.signal, SIGKILL);
1579 signal_wake_up(t, 1);
1580 nr++;
1581 }
1582 } while_each_thread(start, t);
1583
1584 return nr;
1585}
1586
1587static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1588 struct core_state *core_state, int exit_code)
1589{
1590 struct task_struct *g, *p;
1591 unsigned long flags;
1592 int nr = -EAGAIN;
1593
1594 spin_lock_irq(&tsk->sighand->siglock);
1595 if (!signal_group_exit(tsk->signal)) {
1596 mm->core_state = core_state;
1597 nr = zap_process(tsk, exit_code);
1598 }
1599 spin_unlock_irq(&tsk->sighand->siglock);
1600 if (unlikely(nr < 0))
1601 return nr;
1602
1603 if (atomic_read(&mm->mm_users) == nr + 1)
1604 goto done;
1605 /*
1606 * We should find and kill all tasks which use this mm, and we should
1607 * count them correctly into ->nr_threads. We don't take tasklist
1608 * lock, but this is safe wrt:
1609 *
1610 * fork:
1611 * None of sub-threads can fork after zap_process(leader). All
1612 * processes which were created before this point should be
1613 * visible to zap_threads() because copy_process() adds the new
1614 * process to the tail of init_task.tasks list, and lock/unlock
1615 * of ->siglock provides a memory barrier.
1616 *
1617 * do_exit:
1618 * The caller holds mm->mmap_sem. This means that the task which
1619 * uses this mm can't pass exit_mm(), so it can't exit or clear
1620 * its ->mm.
1621 *
1622 * de_thread:
1623 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1624 * we must see either old or new leader, this does not matter.
1625 * However, it can change p->sighand, so lock_task_sighand(p)
1626 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1627 * it can't fail.
1628 *
1629 * Note also that "g" can be the old leader with ->mm == NULL
1630 * and already unhashed and thus removed from ->thread_group.
1631 * This is OK, __unhash_process()->list_del_rcu() does not
1632 * clear the ->next pointer, we will find the new leader via
1633 * next_thread().
1634 */
1635 rcu_read_lock();
1636 for_each_process(g) {
1637 if (g == tsk->group_leader)
1638 continue;
1639 if (g->flags & PF_KTHREAD)
1640 continue;
1641 p = g;
1642 do {
1643 if (p->mm) {
1644 if (unlikely(p->mm == mm)) {
1645 lock_task_sighand(p, &flags);
1646 nr += zap_process(p, exit_code);
1647 unlock_task_sighand(p, &flags);
1648 }
1649 break;
1650 }
1651 } while_each_thread(g, p);
1652 }
1653 rcu_read_unlock();
1654done:
1655 atomic_set(&core_state->nr_threads, nr);
1656 return nr;
1657}
1658
1659static int coredump_wait(int exit_code, struct core_state *core_state)
1660{
1661 struct task_struct *tsk = current;
1662 struct mm_struct *mm = tsk->mm;
1663 struct completion *vfork_done;
1664 int core_waiters = -EBUSY;
1665
1666 init_completion(&core_state->startup);
1667 core_state->dumper.task = tsk;
1668 core_state->dumper.next = NULL;
1669
1670 down_write(&mm->mmap_sem);
1671 if (!mm->core_state)
1672 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1673 up_write(&mm->mmap_sem);
1674
1675 if (unlikely(core_waiters < 0))
1676 goto fail;
1677
1678 /*
1679 * Make sure nobody is waiting for us to release the VM,
1680 * otherwise we can deadlock when we wait on each other
1681 */
1682 vfork_done = tsk->vfork_done;
1683 if (vfork_done) {
1684 tsk->vfork_done = NULL;
1685 complete(vfork_done);
1686 }
1687
1688 if (core_waiters)
1689 wait_for_completion(&core_state->startup);
1690fail:
1691 return core_waiters;
1692}
1693
1694static void coredump_finish(struct mm_struct *mm)
1695{
1696 struct core_thread *curr, *next;
1697 struct task_struct *task;
1698
1699 next = mm->core_state->dumper.next;
1700 while ((curr = next) != NULL) {
1701 next = curr->next;
1702 task = curr->task;
1703 /*
1704 * see exit_mm(), curr->task must not see
1705 * ->task == NULL before we read ->next.
1706 */
1707 smp_mb();
1708 curr->task = NULL;
1709 wake_up_process(task);
1710 }
1711
1712 mm->core_state = NULL;
1713}
1714
1715/*
1716 * set_dumpable converts traditional three-value dumpable to two flags and
1717 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1718 * these bits are not changed atomically. So get_dumpable can observe the
1719 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1720 * return either old dumpable or new one by paying attention to the order of
1721 * modifying the bits.
1722 *
1723 * dumpable | mm->flags (binary)
1724 * old new | initial interim final
1725 * ---------+-----------------------
1726 * 0 1 | 00 01 01
1727 * 0 2 | 00 10(*) 11
1728 * 1 0 | 01 00 00
1729 * 1 2 | 01 11 11
1730 * 2 0 | 11 10(*) 00
1731 * 2 1 | 11 11 01
1732 *
1733 * (*) get_dumpable regards interim value of 10 as 11.
1734 */
1735void set_dumpable(struct mm_struct *mm, int value)
1736{
1737 switch (value) {
1738 case 0:
1739 clear_bit(MMF_DUMPABLE, &mm->flags);
1740 smp_wmb();
1741 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1742 break;
1743 case 1:
1744 set_bit(MMF_DUMPABLE, &mm->flags);
1745 smp_wmb();
1746 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1747 break;
1748 case 2:
1749 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1750 smp_wmb();
1751 set_bit(MMF_DUMPABLE, &mm->flags);
1752 break;
1753 }
1754}
1755
1756static int __get_dumpable(unsigned long mm_flags)
1757{
1758 int ret;
1759
1760 ret = mm_flags & MMF_DUMPABLE_MASK;
1761 return (ret >= 2) ? 2 : ret;
1762}
1763
1764int get_dumpable(struct mm_struct *mm)
1765{
1766 return __get_dumpable(mm->flags);
1767}
1768
1769static void wait_for_dump_helpers(struct file *file)
1770{
1771 struct pipe_inode_info *pipe;
1772
1773 pipe = file->f_path.dentry->d_inode->i_pipe;
1774
1775 pipe_lock(pipe);
1776 pipe->readers++;
1777 pipe->writers--;
1778
1779 while ((pipe->readers > 1) && (!signal_pending(current))) {
1780 wake_up_interruptible_sync(&pipe->wait);
1781 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1782 pipe_wait(pipe);
1783 }
1784
1785 pipe->readers--;
1786 pipe->writers++;
1787 pipe_unlock(pipe);
1788
1789}
1790
1791
1792/*
1793 * uhm_pipe_setup
1794 * helper function to customize the process used
1795 * to collect the core in userspace. Specifically
1796 * it sets up a pipe and installs it as fd 0 (stdin)
1797 * for the process. Returns 0 on success, or
1798 * PTR_ERR on failure.
1799 * Note that it also sets the core limit to 1. This
1800 * is a special value that we use to trap recursive
1801 * core dumps
1802 */
1803static int umh_pipe_setup(struct subprocess_info *info)
1804{
1805 struct file *rp, *wp;
1806 struct fdtable *fdt;
1807 struct coredump_params *cp = (struct coredump_params *)info->data;
1808 struct files_struct *cf = current->files;
1809
1810 wp = create_write_pipe(0);
1811 if (IS_ERR(wp))
1812 return PTR_ERR(wp);
1813
1814 rp = create_read_pipe(wp, 0);
1815 if (IS_ERR(rp)) {
1816 free_write_pipe(wp);
1817 return PTR_ERR(rp);
1818 }
1819
1820 cp->file = wp;
1821
1822 sys_close(0);
1823 fd_install(0, rp);
1824 spin_lock(&cf->file_lock);
1825 fdt = files_fdtable(cf);
1826 FD_SET(0, fdt->open_fds);
1827 FD_CLR(0, fdt->close_on_exec);
1828 spin_unlock(&cf->file_lock);
1829
1830 /* and disallow core files too */
1831 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
1832
1833 return 0;
1834}
1835
1836void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1837{
1838 struct core_state core_state;
1839 char corename[CORENAME_MAX_SIZE + 1];
1840 struct mm_struct *mm = current->mm;
1841 struct linux_binfmt * binfmt;
1842 const struct cred *old_cred;
1843 struct cred *cred;
1844 int retval = 0;
1845 int flag = 0;
1846 int ispipe;
1847 static atomic_t core_dump_count = ATOMIC_INIT(0);
1848 struct coredump_params cprm = {
1849 .signr = signr,
1850 .regs = regs,
1851 .limit = rlimit(RLIMIT_CORE),
1852 /*
1853 * We must use the same mm->flags while dumping core to avoid
1854 * inconsistency of bit flags, since this flag is not protected
1855 * by any locks.
1856 */
1857 .mm_flags = mm->flags,
1858 };
1859
1860 audit_core_dumps(signr);
1861
1862 binfmt = mm->binfmt;
1863 if (!binfmt || !binfmt->core_dump)
1864 goto fail;
1865 if (!__get_dumpable(cprm.mm_flags))
1866 goto fail;
1867
1868 cred = prepare_creds();
1869 if (!cred)
1870 goto fail;
1871 /*
1872 * We cannot trust fsuid as being the "true" uid of the
1873 * process nor do we know its entire history. We only know it
1874 * was tainted so we dump it as root in mode 2.
1875 */
1876 if (__get_dumpable(cprm.mm_flags) == 2) {
1877 /* Setuid core dump mode */
1878 flag = O_EXCL; /* Stop rewrite attacks */
1879 cred->fsuid = 0; /* Dump root private */
1880 }
1881
1882 retval = coredump_wait(exit_code, &core_state);
1883 if (retval < 0)
1884 goto fail_creds;
1885
1886 old_cred = override_creds(cred);
1887
1888 /*
1889 * Clear any false indication of pending signals that might
1890 * be seen by the filesystem code called to write the core file.
1891 */
1892 clear_thread_flag(TIF_SIGPENDING);
1893
1894 /*
1895 * lock_kernel() because format_corename() is controlled by sysctl, which
1896 * uses lock_kernel()
1897 */
1898 lock_kernel();
1899 ispipe = format_corename(corename, signr);
1900 unlock_kernel();
1901
1902 if (ispipe) {
1903 int dump_count;
1904 char **helper_argv;
1905
1906 if (cprm.limit == 1) {
1907 /*
1908 * Normally core limits are irrelevant to pipes, since
1909 * we're not writing to the file system, but we use
1910 * cprm.limit of 1 here as a speacial value. Any
1911 * non-1 limit gets set to RLIM_INFINITY below, but
1912 * a limit of 0 skips the dump. This is a consistent
1913 * way to catch recursive crashes. We can still crash
1914 * if the core_pattern binary sets RLIM_CORE = !1
1915 * but it runs as root, and can do lots of stupid things
1916 * Note that we use task_tgid_vnr here to grab the pid
1917 * of the process group leader. That way we get the
1918 * right pid if a thread in a multi-threaded
1919 * core_pattern process dies.
1920 */
1921 printk(KERN_WARNING
1922 "Process %d(%s) has RLIMIT_CORE set to 1\n",
1923 task_tgid_vnr(current), current->comm);
1924 printk(KERN_WARNING "Aborting core\n");
1925 goto fail_unlock;
1926 }
1927 cprm.limit = RLIM_INFINITY;
1928
1929 dump_count = atomic_inc_return(&core_dump_count);
1930 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
1931 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
1932 task_tgid_vnr(current), current->comm);
1933 printk(KERN_WARNING "Skipping core dump\n");
1934 goto fail_dropcount;
1935 }
1936
1937 helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
1938 if (!helper_argv) {
1939 printk(KERN_WARNING "%s failed to allocate memory\n",
1940 __func__);
1941 goto fail_dropcount;
1942 }
1943
1944 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
1945 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
1946 NULL, &cprm);
1947 argv_free(helper_argv);
1948 if (retval) {
1949 printk(KERN_INFO "Core dump to %s pipe failed\n",
1950 corename);
1951 goto close_fail;
1952 }
1953 } else {
1954 struct inode *inode;
1955
1956 if (cprm.limit < binfmt->min_coredump)
1957 goto fail_unlock;
1958
1959 cprm.file = filp_open(corename,
1960 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
1961 0600);
1962 if (IS_ERR(cprm.file))
1963 goto fail_unlock;
1964
1965 inode = cprm.file->f_path.dentry->d_inode;
1966 if (inode->i_nlink > 1)
1967 goto close_fail;
1968 if (d_unhashed(cprm.file->f_path.dentry))
1969 goto close_fail;
1970 /*
1971 * AK: actually i see no reason to not allow this for named
1972 * pipes etc, but keep the previous behaviour for now.
1973 */
1974 if (!S_ISREG(inode->i_mode))
1975 goto close_fail;
1976 /*
1977 * Dont allow local users get cute and trick others to coredump
1978 * into their pre-created files.
1979 */
1980 if (inode->i_uid != current_fsuid())
1981 goto close_fail;
1982 if (!cprm.file->f_op || !cprm.file->f_op->write)
1983 goto close_fail;
1984 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
1985 goto close_fail;
1986 }
1987
1988 retval = binfmt->core_dump(&cprm);
1989 if (retval)
1990 current->signal->group_exit_code |= 0x80;
1991
1992 if (ispipe && core_pipe_limit)
1993 wait_for_dump_helpers(cprm.file);
1994close_fail:
1995 if (cprm.file)
1996 filp_close(cprm.file, NULL);
1997fail_dropcount:
1998 if (ispipe)
1999 atomic_dec(&core_dump_count);
2000fail_unlock:
2001 coredump_finish(mm);
2002 revert_creds(old_cred);
2003fail_creds:
2004 put_cred(cred);
2005fail:
2006 return;
2007}