projects/linux·blob v2.6.39 · refs

2134 lines · 48.9 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/swap.h>
32#include <linux/string.h>
33#include <linux/init.h>
34#include <linux/pagemap.h>
35#include <linux/perf_event.h>
36#include <linux/highmem.h>
37#include <linux/spinlock.h>
38#include <linux/key.h>
39#include <linux/personality.h>
40#include <linux/binfmts.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/mount.h>
47#include <linux/security.h>
48#include <linux/syscalls.h>
49#include <linux/tsacct_kern.h>
50#include <linux/cn_proc.h>
51#include <linux/audit.h>
52#include <linux/tracehook.h>
53#include <linux/kmod.h>
54#include <linux/fsnotify.h>
55#include <linux/fs_struct.h>
56#include <linux/pipe_fs_i.h>
57#include <linux/oom.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
69struct core_name {
70 char *corename;
71 int used, size;
72};
73static atomic_t call_count = ATOMIC_INIT(1);
74
75/* The maximal length of core_pattern is also specified in sysctl.c */
76
77static LIST_HEAD(formats);
78static DEFINE_RWLOCK(binfmt_lock);
79
80int __register_binfmt(struct linux_binfmt * fmt, int insert)
81{
82 if (!fmt)
83 return -EINVAL;
84 write_lock(&binfmt_lock);
85 insert ? list_add(&fmt->lh, &formats) :
86 list_add_tail(&fmt->lh, &formats);
87 write_unlock(&binfmt_lock);
88 return 0;
89}
90
91EXPORT_SYMBOL(__register_binfmt);
92
93void unregister_binfmt(struct linux_binfmt * fmt)
94{
95 write_lock(&binfmt_lock);
96 list_del(&fmt->lh);
97 write_unlock(&binfmt_lock);
98}
99
100EXPORT_SYMBOL(unregister_binfmt);
101
102static inline void put_binfmt(struct linux_binfmt * fmt)
103{
104 module_put(fmt->module);
105}
106
107/*
108 * Note that a shared library must be both readable and executable due to
109 * security reasons.
110 *
111 * Also note that we take the address to load from from the file itself.
112 */
113SYSCALL_DEFINE1(uselib, const char __user *, library)
114{
115 struct file *file;
116 char *tmp = getname(library);
117 int error = PTR_ERR(tmp);
118 static const struct open_flags uselib_flags = {
119 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
120 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
121 .intent = LOOKUP_OPEN
122 };
123
124 if (IS_ERR(tmp))
125 goto out;
126
127 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
128 putname(tmp);
129 error = PTR_ERR(file);
130 if (IS_ERR(file))
131 goto out;
132
133 error = -EINVAL;
134 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
135 goto exit;
136
137 error = -EACCES;
138 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
139 goto exit;
140
141 fsnotify_open(file);
142
143 error = -ENOEXEC;
144 if(file->f_op) {
145 struct linux_binfmt * fmt;
146
147 read_lock(&binfmt_lock);
148 list_for_each_entry(fmt, &formats, lh) {
149 if (!fmt->load_shlib)
150 continue;
151 if (!try_module_get(fmt->module))
152 continue;
153 read_unlock(&binfmt_lock);
154 error = fmt->load_shlib(file);
155 read_lock(&binfmt_lock);
156 put_binfmt(fmt);
157 if (error != -ENOEXEC)
158 break;
159 }
160 read_unlock(&binfmt_lock);
161 }
162exit:
163 fput(file);
164out:
165 return error;
166}
167
168#ifdef CONFIG_MMU
169
170void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
171{
172 struct mm_struct *mm = current->mm;
173 long diff = (long)(pages - bprm->vma_pages);
174
175 if (!mm || !diff)
176 return;
177
178 bprm->vma_pages = pages;
179
180#ifdef SPLIT_RSS_COUNTING
181 add_mm_counter(mm, MM_ANONPAGES, diff);
182#else
183 spin_lock(&mm->page_table_lock);
184 add_mm_counter(mm, MM_ANONPAGES, diff);
185 spin_unlock(&mm->page_table_lock);
186#endif
187}
188
189struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
190 int write)
191{
192 struct page *page;
193 int ret;
194
195#ifdef CONFIG_STACK_GROWSUP
196 if (write) {
197 ret = expand_stack_downwards(bprm->vma, pos);
198 if (ret < 0)
199 return NULL;
200 }
201#endif
202 ret = get_user_pages(current, bprm->mm, pos,
203 1, write, 1, &page, NULL);
204 if (ret <= 0)
205 return NULL;
206
207 if (write) {
208 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
209 struct rlimit *rlim;
210
211 acct_arg_size(bprm, size / PAGE_SIZE);
212
213 /*
214 * We've historically supported up to 32 pages (ARG_MAX)
215 * of argument strings even with small stacks
216 */
217 if (size <= ARG_MAX)
218 return page;
219
220 /*
221 * Limit to 1/4-th the stack size for the argv+env strings.
222 * This ensures that:
223 * - the remaining binfmt code will not run out of stack space,
224 * - the program will have a reasonable amount of stack left
225 * to work from.
226 */
227 rlim = current->signal->rlim;
228 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
229 put_page(page);
230 return NULL;
231 }
232 }
233
234 return page;
235}
236
237static void put_arg_page(struct page *page)
238{
239 put_page(page);
240}
241
242static void free_arg_page(struct linux_binprm *bprm, int i)
243{
244}
245
246static void free_arg_pages(struct linux_binprm *bprm)
247{
248}
249
250static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
251 struct page *page)
252{
253 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
254}
255
256static int __bprm_mm_init(struct linux_binprm *bprm)
257{
258 int err;
259 struct vm_area_struct *vma = NULL;
260 struct mm_struct *mm = bprm->mm;
261
262 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
263 if (!vma)
264 return -ENOMEM;
265
266 down_write(&mm->mmap_sem);
267 vma->vm_mm = mm;
268
269 /*
270 * Place the stack at the largest stack address the architecture
271 * supports. Later, we'll move this to an appropriate place. We don't
272 * use STACK_TOP because that can depend on attributes which aren't
273 * configured yet.
274 */
275 BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
276 vma->vm_end = STACK_TOP_MAX;
277 vma->vm_start = vma->vm_end - PAGE_SIZE;
278 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
279 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
280 INIT_LIST_HEAD(&vma->anon_vma_chain);
281
282 err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
283 if (err)
284 goto err;
285
286 err = insert_vm_struct(mm, vma);
287 if (err)
288 goto err;
289
290 mm->stack_vm = mm->total_vm = 1;
291 up_write(&mm->mmap_sem);
292 bprm->p = vma->vm_end - sizeof(void *);
293 return 0;
294err:
295 up_write(&mm->mmap_sem);
296 bprm->vma = NULL;
297 kmem_cache_free(vm_area_cachep, vma);
298 return err;
299}
300
301static bool valid_arg_len(struct linux_binprm *bprm, long len)
302{
303 return len <= MAX_ARG_STRLEN;
304}
305
306#else
307
308void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
309{
310}
311
312struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
313 int write)
314{
315 struct page *page;
316
317 page = bprm->page[pos / PAGE_SIZE];
318 if (!page && write) {
319 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
320 if (!page)
321 return NULL;
322 bprm->page[pos / PAGE_SIZE] = page;
323 }
324
325 return page;
326}
327
328static void put_arg_page(struct page *page)
329{
330}
331
332static void free_arg_page(struct linux_binprm *bprm, int i)
333{
334 if (bprm->page[i]) {
335 __free_page(bprm->page[i]);
336 bprm->page[i] = NULL;
337 }
338}
339
340static void free_arg_pages(struct linux_binprm *bprm)
341{
342 int i;
343
344 for (i = 0; i < MAX_ARG_PAGES; i++)
345 free_arg_page(bprm, i);
346}
347
348static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
349 struct page *page)
350{
351}
352
353static int __bprm_mm_init(struct linux_binprm *bprm)
354{
355 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
356 return 0;
357}
358
359static bool valid_arg_len(struct linux_binprm *bprm, long len)
360{
361 return len <= bprm->p;
362}
363
364#endif /* CONFIG_MMU */
365
366/*
367 * Create a new mm_struct and populate it with a temporary stack
368 * vm_area_struct. We don't have enough context at this point to set the stack
369 * flags, permissions, and offset, so we use temporary values. We'll update
370 * them later in setup_arg_pages().
371 */
372int bprm_mm_init(struct linux_binprm *bprm)
373{
374 int err;
375 struct mm_struct *mm = NULL;
376
377 bprm->mm = mm = mm_alloc();
378 err = -ENOMEM;
379 if (!mm)
380 goto err;
381
382 err = init_new_context(current, mm);
383 if (err)
384 goto err;
385
386 err = __bprm_mm_init(bprm);
387 if (err)
388 goto err;
389
390 return 0;
391
392err:
393 if (mm) {
394 bprm->mm = NULL;
395 mmdrop(mm);
396 }
397
398 return err;
399}
400
401/*
402 * count() counts the number of strings in array ARGV.
403 */
404static int count(const char __user * const __user * argv, int max)
405{
406 int i = 0;
407
408 if (argv != NULL) {
409 for (;;) {
410 const char __user * p;
411
412 if (get_user(p, argv))
413 return -EFAULT;
414 if (!p)
415 break;
416 argv++;
417 if (i++ >= max)
418 return -E2BIG;
419
420 if (fatal_signal_pending(current))
421 return -ERESTARTNOHAND;
422 cond_resched();
423 }
424 }
425 return i;
426}
427
428/*
429 * 'copy_strings()' copies argument/environment strings from the old
430 * processes's memory to the new process's stack. The call to get_user_pages()
431 * ensures the destination page is created and not swapped out.
432 */
433static int copy_strings(int argc, const char __user *const __user *argv,
434 struct linux_binprm *bprm)
435{
436 struct page *kmapped_page = NULL;
437 char *kaddr = NULL;
438 unsigned long kpos = 0;
439 int ret;
440
441 while (argc-- > 0) {
442 const char __user *str;
443 int len;
444 unsigned long pos;
445
446 if (get_user(str, argv+argc) ||
447 !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
448 ret = -EFAULT;
449 goto out;
450 }
451
452 if (!valid_arg_len(bprm, len)) {
453 ret = -E2BIG;
454 goto out;
455 }
456
457 /* We're going to work our way backwords. */
458 pos = bprm->p;
459 str += len;
460 bprm->p -= len;
461
462 while (len > 0) {
463 int offset, bytes_to_copy;
464
465 if (fatal_signal_pending(current)) {
466 ret = -ERESTARTNOHAND;
467 goto out;
468 }
469 cond_resched();
470
471 offset = pos % PAGE_SIZE;
472 if (offset == 0)
473 offset = PAGE_SIZE;
474
475 bytes_to_copy = offset;
476 if (bytes_to_copy > len)
477 bytes_to_copy = len;
478
479 offset -= bytes_to_copy;
480 pos -= bytes_to_copy;
481 str -= bytes_to_copy;
482 len -= bytes_to_copy;
483
484 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
485 struct page *page;
486
487 page = get_arg_page(bprm, pos, 1);
488 if (!page) {
489 ret = -E2BIG;
490 goto out;
491 }
492
493 if (kmapped_page) {
494 flush_kernel_dcache_page(kmapped_page);
495 kunmap(kmapped_page);
496 put_arg_page(kmapped_page);
497 }
498 kmapped_page = page;
499 kaddr = kmap(kmapped_page);
500 kpos = pos & PAGE_MASK;
501 flush_arg_page(bprm, kpos, kmapped_page);
502 }
503 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
504 ret = -EFAULT;
505 goto out;
506 }
507 }
508 }
509 ret = 0;
510out:
511 if (kmapped_page) {
512 flush_kernel_dcache_page(kmapped_page);
513 kunmap(kmapped_page);
514 put_arg_page(kmapped_page);
515 }
516 return ret;
517}
518
519/*
520 * Like copy_strings, but get argv and its values from kernel memory.
521 */
522int copy_strings_kernel(int argc, const char *const *argv,
523 struct linux_binprm *bprm)
524{
525 int r;
526 mm_segment_t oldfs = get_fs();
527 set_fs(KERNEL_DS);
528 r = copy_strings(argc, (const char __user *const __user *)argv, bprm);
529 set_fs(oldfs);
530 return r;
531}
532EXPORT_SYMBOL(copy_strings_kernel);
533
534#ifdef CONFIG_MMU
535
536/*
537 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
538 * the binfmt code determines where the new stack should reside, we shift it to
539 * its final location. The process proceeds as follows:
540 *
541 * 1) Use shift to calculate the new vma endpoints.
542 * 2) Extend vma to cover both the old and new ranges. This ensures the
543 * arguments passed to subsequent functions are consistent.
544 * 3) Move vma's page tables to the new range.
545 * 4) Free up any cleared pgd range.
546 * 5) Shrink the vma to cover only the new range.
547 */
548static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
549{
550 struct mm_struct *mm = vma->vm_mm;
551 unsigned long old_start = vma->vm_start;
552 unsigned long old_end = vma->vm_end;
553 unsigned long length = old_end - old_start;
554 unsigned long new_start = old_start - shift;
555 unsigned long new_end = old_end - shift;
556 struct mmu_gather *tlb;
557
558 BUG_ON(new_start > new_end);
559
560 /*
561 * ensure there are no vmas between where we want to go
562 * and where we are
563 */
564 if (vma != find_vma(mm, new_start))
565 return -EFAULT;
566
567 /*
568 * cover the whole range: [new_start, old_end)
569 */
570 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
571 return -ENOMEM;
572
573 /*
574 * move the page tables downwards, on failure we rely on
575 * process cleanup to remove whatever mess we made.
576 */
577 if (length != move_page_tables(vma, old_start,
578 vma, new_start, length))
579 return -ENOMEM;
580
581 lru_add_drain();
582 tlb = tlb_gather_mmu(mm, 0);
583 if (new_end > old_start) {
584 /*
585 * when the old and new regions overlap clear from new_end.
586 */
587 free_pgd_range(tlb, new_end, old_end, new_end,
588 vma->vm_next ? vma->vm_next->vm_start : 0);
589 } else {
590 /*
591 * otherwise, clean from old_start; this is done to not touch
592 * the address space in [new_end, old_start) some architectures
593 * have constraints on va-space that make this illegal (IA64) -
594 * for the others its just a little faster.
595 */
596 free_pgd_range(tlb, old_start, old_end, new_end,
597 vma->vm_next ? vma->vm_next->vm_start : 0);
598 }
599 tlb_finish_mmu(tlb, new_end, old_end);
600
601 /*
602 * Shrink the vma to just the new range. Always succeeds.
603 */
604 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
605
606 return 0;
607}
608
609/*
610 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
611 * the stack is optionally relocated, and some extra space is added.
612 */
613int setup_arg_pages(struct linux_binprm *bprm,
614 unsigned long stack_top,
615 int executable_stack)
616{
617 unsigned long ret;
618 unsigned long stack_shift;
619 struct mm_struct *mm = current->mm;
620 struct vm_area_struct *vma = bprm->vma;
621 struct vm_area_struct *prev = NULL;
622 unsigned long vm_flags;
623 unsigned long stack_base;
624 unsigned long stack_size;
625 unsigned long stack_expand;
626 unsigned long rlim_stack;
627
628#ifdef CONFIG_STACK_GROWSUP
629 /* Limit stack size to 1GB */
630 stack_base = rlimit_max(RLIMIT_STACK);
631 if (stack_base > (1 << 30))
632 stack_base = 1 << 30;
633
634 /* Make sure we didn't let the argument array grow too large. */
635 if (vma->vm_end - vma->vm_start > stack_base)
636 return -ENOMEM;
637
638 stack_base = PAGE_ALIGN(stack_top - stack_base);
639
640 stack_shift = vma->vm_start - stack_base;
641 mm->arg_start = bprm->p - stack_shift;
642 bprm->p = vma->vm_end - stack_shift;
643#else
644 stack_top = arch_align_stack(stack_top);
645 stack_top = PAGE_ALIGN(stack_top);
646
647 if (unlikely(stack_top < mmap_min_addr) ||
648 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
649 return -ENOMEM;
650
651 stack_shift = vma->vm_end - stack_top;
652
653 bprm->p -= stack_shift;
654 mm->arg_start = bprm->p;
655#endif
656
657 if (bprm->loader)
658 bprm->loader -= stack_shift;
659 bprm->exec -= stack_shift;
660
661 down_write(&mm->mmap_sem);
662 vm_flags = VM_STACK_FLAGS;
663
664 /*
665 * Adjust stack execute permissions; explicitly enable for
666 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
667 * (arch default) otherwise.
668 */
669 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
670 vm_flags |= VM_EXEC;
671 else if (executable_stack == EXSTACK_DISABLE_X)
672 vm_flags &= ~VM_EXEC;
673 vm_flags |= mm->def_flags;
674 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
675
676 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
677 vm_flags);
678 if (ret)
679 goto out_unlock;
680 BUG_ON(prev != vma);
681
682 /* Move stack pages down in memory. */
683 if (stack_shift) {
684 ret = shift_arg_pages(vma, stack_shift);
685 if (ret)
686 goto out_unlock;
687 }
688
689 /* mprotect_fixup is overkill to remove the temporary stack flags */
690 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
691
692 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
693 stack_size = vma->vm_end - vma->vm_start;
694 /*
695 * Align this down to a page boundary as expand_stack
696 * will align it up.
697 */
698 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
699#ifdef CONFIG_STACK_GROWSUP
700 if (stack_size + stack_expand > rlim_stack)
701 stack_base = vma->vm_start + rlim_stack;
702 else
703 stack_base = vma->vm_end + stack_expand;
704#else
705 if (stack_size + stack_expand > rlim_stack)
706 stack_base = vma->vm_end - rlim_stack;
707 else
708 stack_base = vma->vm_start - stack_expand;
709#endif
710 current->mm->start_stack = bprm->p;
711 ret = expand_stack(vma, stack_base);
712 if (ret)
713 ret = -EFAULT;
714
715out_unlock:
716 up_write(&mm->mmap_sem);
717 return ret;
718}
719EXPORT_SYMBOL(setup_arg_pages);
720
721#endif /* CONFIG_MMU */
722
723struct file *open_exec(const char *name)
724{
725 struct file *file;
726 int err;
727 static const struct open_flags open_exec_flags = {
728 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
729 .acc_mode = MAY_EXEC | MAY_OPEN,
730 .intent = LOOKUP_OPEN
731 };
732
733 file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
734 if (IS_ERR(file))
735 goto out;
736
737 err = -EACCES;
738 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
739 goto exit;
740
741 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
742 goto exit;
743
744 fsnotify_open(file);
745
746 err = deny_write_access(file);
747 if (err)
748 goto exit;
749
750out:
751 return file;
752
753exit:
754 fput(file);
755 return ERR_PTR(err);
756}
757EXPORT_SYMBOL(open_exec);
758
759int kernel_read(struct file *file, loff_t offset,
760 char *addr, unsigned long count)
761{
762 mm_segment_t old_fs;
763 loff_t pos = offset;
764 int result;
765
766 old_fs = get_fs();
767 set_fs(get_ds());
768 /* The cast to a user pointer is valid due to the set_fs() */
769 result = vfs_read(file, (void __user *)addr, count, &pos);
770 set_fs(old_fs);
771 return result;
772}
773
774EXPORT_SYMBOL(kernel_read);
775
776static int exec_mmap(struct mm_struct *mm)
777{
778 struct task_struct *tsk;
779 struct mm_struct * old_mm, *active_mm;
780
781 /* Notify parent that we're no longer interested in the old VM */
782 tsk = current;
783 old_mm = current->mm;
784 sync_mm_rss(tsk, old_mm);
785 mm_release(tsk, old_mm);
786
787 if (old_mm) {
788 /*
789 * Make sure that if there is a core dump in progress
790 * for the old mm, we get out and die instead of going
791 * through with the exec. We must hold mmap_sem around
792 * checking core_state and changing tsk->mm.
793 */
794 down_read(&old_mm->mmap_sem);
795 if (unlikely(old_mm->core_state)) {
796 up_read(&old_mm->mmap_sem);
797 return -EINTR;
798 }
799 }
800 task_lock(tsk);
801 active_mm = tsk->active_mm;
802 tsk->mm = mm;
803 tsk->active_mm = mm;
804 activate_mm(active_mm, mm);
805 if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
806 atomic_dec(&old_mm->oom_disable_count);
807 atomic_inc(&tsk->mm->oom_disable_count);
808 }
809 task_unlock(tsk);
810 arch_pick_mmap_layout(mm);
811 if (old_mm) {
812 up_read(&old_mm->mmap_sem);
813 BUG_ON(active_mm != old_mm);
814 mm_update_next_owner(old_mm);
815 mmput(old_mm);
816 return 0;
817 }
818 mmdrop(active_mm);
819 return 0;
820}
821
822/*
823 * This function makes sure the current process has its own signal table,
824 * so that flush_signal_handlers can later reset the handlers without
825 * disturbing other processes. (Other processes might share the signal
826 * table via the CLONE_SIGHAND option to clone().)
827 */
828static int de_thread(struct task_struct *tsk)
829{
830 struct signal_struct *sig = tsk->signal;
831 struct sighand_struct *oldsighand = tsk->sighand;
832 spinlock_t *lock = &oldsighand->siglock;
833
834 if (thread_group_empty(tsk))
835 goto no_thread_group;
836
837 /*
838 * Kill all other threads in the thread group.
839 */
840 spin_lock_irq(lock);
841 if (signal_group_exit(sig)) {
842 /*
843 * Another group action in progress, just
844 * return so that the signal is processed.
845 */
846 spin_unlock_irq(lock);
847 return -EAGAIN;
848 }
849
850 sig->group_exit_task = tsk;
851 sig->notify_count = zap_other_threads(tsk);
852 if (!thread_group_leader(tsk))
853 sig->notify_count--;
854
855 while (sig->notify_count) {
856 __set_current_state(TASK_UNINTERRUPTIBLE);
857 spin_unlock_irq(lock);
858 schedule();
859 spin_lock_irq(lock);
860 }
861 spin_unlock_irq(lock);
862
863 /*
864 * At this point all other threads have exited, all we have to
865 * do is to wait for the thread group leader to become inactive,
866 * and to assume its PID:
867 */
868 if (!thread_group_leader(tsk)) {
869 struct task_struct *leader = tsk->group_leader;
870
871 sig->notify_count = -1; /* for exit_notify() */
872 for (;;) {
873 write_lock_irq(&tasklist_lock);
874 if (likely(leader->exit_state))
875 break;
876 __set_current_state(TASK_UNINTERRUPTIBLE);
877 write_unlock_irq(&tasklist_lock);
878 schedule();
879 }
880
881 /*
882 * The only record we have of the real-time age of a
883 * process, regardless of execs it's done, is start_time.
884 * All the past CPU time is accumulated in signal_struct
885 * from sister threads now dead. But in this non-leader
886 * exec, nothing survives from the original leader thread,
887 * whose birth marks the true age of this process now.
888 * When we take on its identity by switching to its PID, we
889 * also take its birthdate (always earlier than our own).
890 */
891 tsk->start_time = leader->start_time;
892
893 BUG_ON(!same_thread_group(leader, tsk));
894 BUG_ON(has_group_leader_pid(tsk));
895 /*
896 * An exec() starts a new thread group with the
897 * TGID of the previous thread group. Rehash the
898 * two threads with a switched PID, and release
899 * the former thread group leader:
900 */
901
902 /* Become a process group leader with the old leader's pid.
903 * The old leader becomes a thread of the this thread group.
904 * Note: The old leader also uses this pid until release_task
905 * is called. Odd but simple and correct.
906 */
907 detach_pid(tsk, PIDTYPE_PID);
908 tsk->pid = leader->pid;
909 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
910 transfer_pid(leader, tsk, PIDTYPE_PGID);
911 transfer_pid(leader, tsk, PIDTYPE_SID);
912
913 list_replace_rcu(&leader->tasks, &tsk->tasks);
914 list_replace_init(&leader->sibling, &tsk->sibling);
915
916 tsk->group_leader = tsk;
917 leader->group_leader = tsk;
918
919 tsk->exit_signal = SIGCHLD;
920
921 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
922 leader->exit_state = EXIT_DEAD;
923 write_unlock_irq(&tasklist_lock);
924
925 release_task(leader);
926 }
927
928 sig->group_exit_task = NULL;
929 sig->notify_count = 0;
930
931no_thread_group:
932 if (current->mm)
933 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
934
935 exit_itimers(sig);
936 flush_itimer_signals();
937
938 if (atomic_read(&oldsighand->count) != 1) {
939 struct sighand_struct *newsighand;
940 /*
941 * This ->sighand is shared with the CLONE_SIGHAND
942 * but not CLONE_THREAD task, switch to the new one.
943 */
944 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
945 if (!newsighand)
946 return -ENOMEM;
947
948 atomic_set(&newsighand->count, 1);
949 memcpy(newsighand->action, oldsighand->action,
950 sizeof(newsighand->action));
951
952 write_lock_irq(&tasklist_lock);
953 spin_lock(&oldsighand->siglock);
954 rcu_assign_pointer(tsk->sighand, newsighand);
955 spin_unlock(&oldsighand->siglock);
956 write_unlock_irq(&tasklist_lock);
957
958 __cleanup_sighand(oldsighand);
959 }
960
961 BUG_ON(!thread_group_leader(tsk));
962 return 0;
963}
964
965/*
966 * These functions flushes out all traces of the currently running executable
967 * so that a new one can be started
968 */
969static void flush_old_files(struct files_struct * files)
970{
971 long j = -1;
972 struct fdtable *fdt;
973
974 spin_lock(&files->file_lock);
975 for (;;) {
976 unsigned long set, i;
977
978 j++;
979 i = j * __NFDBITS;
980 fdt = files_fdtable(files);
981 if (i >= fdt->max_fds)
982 break;
983 set = fdt->close_on_exec->fds_bits[j];
984 if (!set)
985 continue;
986 fdt->close_on_exec->fds_bits[j] = 0;
987 spin_unlock(&files->file_lock);
988 for ( ; set ; i++,set >>= 1) {
989 if (set & 1) {
990 sys_close(i);
991 }
992 }
993 spin_lock(&files->file_lock);
994
995 }
996 spin_unlock(&files->file_lock);
997}
998
999char *get_task_comm(char *buf, struct task_struct *tsk)
1000{
1001 /* buf must be at least sizeof(tsk->comm) in size */
1002 task_lock(tsk);
1003 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1004 task_unlock(tsk);
1005 return buf;
1006}
1007
1008void set_task_comm(struct task_struct *tsk, char *buf)
1009{
1010 task_lock(tsk);
1011
1012 /*
1013 * Threads may access current->comm without holding
1014 * the task lock, so write the string carefully.
1015 * Readers without a lock may see incomplete new
1016 * names but are safe from non-terminating string reads.
1017 */
1018 memset(tsk->comm, 0, TASK_COMM_LEN);
1019 wmb();
1020 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1021 task_unlock(tsk);
1022 perf_event_comm(tsk);
1023}
1024
1025int flush_old_exec(struct linux_binprm * bprm)
1026{
1027 int retval;
1028
1029 /*
1030 * Make sure we have a private signal table and that
1031 * we are unassociated from the previous thread group.
1032 */
1033 retval = de_thread(current);
1034 if (retval)
1035 goto out;
1036
1037 set_mm_exe_file(bprm->mm, bprm->file);
1038
1039 /*
1040 * Release all of the old mmap stuff
1041 */
1042 acct_arg_size(bprm, 0);
1043 retval = exec_mmap(bprm->mm);
1044 if (retval)
1045 goto out;
1046
1047 bprm->mm = NULL; /* We're using it now */
1048
1049 current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1050 flush_thread();
1051 current->personality &= ~bprm->per_clear;
1052
1053 return 0;
1054
1055out:
1056 return retval;
1057}
1058EXPORT_SYMBOL(flush_old_exec);
1059
1060void setup_new_exec(struct linux_binprm * bprm)
1061{
1062 int i, ch;
1063 const char *name;
1064 char tcomm[sizeof(current->comm)];
1065
1066 arch_pick_mmap_layout(current->mm);
1067
1068 /* This is the point of no return */
1069 current->sas_ss_sp = current->sas_ss_size = 0;
1070
1071 if (current_euid() == current_uid() && current_egid() == current_gid())
1072 set_dumpable(current->mm, 1);
1073 else
1074 set_dumpable(current->mm, suid_dumpable);
1075
1076 name = bprm->filename;
1077
1078 /* Copies the binary name from after last slash */
1079 for (i=0; (ch = *(name++)) != '\0';) {
1080 if (ch == '/')
1081 i = 0; /* overwrite what we wrote */
1082 else
1083 if (i < (sizeof(tcomm) - 1))
1084 tcomm[i++] = ch;
1085 }
1086 tcomm[i] = '\0';
1087 set_task_comm(current, tcomm);
1088
1089 /* Set the new mm task size. We have to do that late because it may
1090 * depend on TIF_32BIT which is only updated in flush_thread() on
1091 * some architectures like powerpc
1092 */
1093 current->mm->task_size = TASK_SIZE;
1094
1095 /* install the new credentials */
1096 if (bprm->cred->uid != current_euid() ||
1097 bprm->cred->gid != current_egid()) {
1098 current->pdeath_signal = 0;
1099 } else if (file_permission(bprm->file, MAY_READ) ||
1100 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1101 set_dumpable(current->mm, suid_dumpable);
1102 }
1103
1104 /*
1105 * Flush performance counters when crossing a
1106 * security domain:
1107 */
1108 if (!get_dumpable(current->mm))
1109 perf_event_exit_task(current);
1110
1111 /* An exec changes our domain. We are no longer part of the thread
1112 group */
1113
1114 current->self_exec_id++;
1115
1116 flush_signal_handlers(current, 0);
1117 flush_old_files(current->files);
1118}
1119EXPORT_SYMBOL(setup_new_exec);
1120
1121/*
1122 * Prepare credentials and lock ->cred_guard_mutex.
1123 * install_exec_creds() commits the new creds and drops the lock.
1124 * Or, if exec fails before, free_bprm() should release ->cred and
1125 * and unlock.
1126 */
1127int prepare_bprm_creds(struct linux_binprm *bprm)
1128{
1129 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1130 return -ERESTARTNOINTR;
1131
1132 bprm->cred = prepare_exec_creds();
1133 if (likely(bprm->cred))
1134 return 0;
1135
1136 mutex_unlock(&current->signal->cred_guard_mutex);
1137 return -ENOMEM;
1138}
1139
1140void free_bprm(struct linux_binprm *bprm)
1141{
1142 free_arg_pages(bprm);
1143 if (bprm->cred) {
1144 mutex_unlock(&current->signal->cred_guard_mutex);
1145 abort_creds(bprm->cred);
1146 }
1147 kfree(bprm);
1148}
1149
1150/*
1151 * install the new credentials for this executable
1152 */
1153void install_exec_creds(struct linux_binprm *bprm)
1154{
1155 security_bprm_committing_creds(bprm);
1156
1157 commit_creds(bprm->cred);
1158 bprm->cred = NULL;
1159 /*
1160 * cred_guard_mutex must be held at least to this point to prevent
1161 * ptrace_attach() from altering our determination of the task's
1162 * credentials; any time after this it may be unlocked.
1163 */
1164 security_bprm_committed_creds(bprm);
1165 mutex_unlock(&current->signal->cred_guard_mutex);
1166}
1167EXPORT_SYMBOL(install_exec_creds);
1168
1169/*
1170 * determine how safe it is to execute the proposed program
1171 * - the caller must hold ->cred_guard_mutex to protect against
1172 * PTRACE_ATTACH
1173 */
1174int check_unsafe_exec(struct linux_binprm *bprm)
1175{
1176 struct task_struct *p = current, *t;
1177 unsigned n_fs;
1178 int res = 0;
1179
1180 bprm->unsafe = tracehook_unsafe_exec(p);
1181
1182 n_fs = 1;
1183 spin_lock(&p->fs->lock);
1184 rcu_read_lock();
1185 for (t = next_thread(p); t != p; t = next_thread(t)) {
1186 if (t->fs == p->fs)
1187 n_fs++;
1188 }
1189 rcu_read_unlock();
1190
1191 if (p->fs->users > n_fs) {
1192 bprm->unsafe |= LSM_UNSAFE_SHARE;
1193 } else {
1194 res = -EAGAIN;
1195 if (!p->fs->in_exec) {
1196 p->fs->in_exec = 1;
1197 res = 1;
1198 }
1199 }
1200 spin_unlock(&p->fs->lock);
1201
1202 return res;
1203}
1204
1205/*
1206 * Fill the binprm structure from the inode.
1207 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1208 *
1209 * This may be called multiple times for binary chains (scripts for example).
1210 */
1211int prepare_binprm(struct linux_binprm *bprm)
1212{
1213 umode_t mode;
1214 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1215 int retval;
1216
1217 mode = inode->i_mode;
1218 if (bprm->file->f_op == NULL)
1219 return -EACCES;
1220
1221 /* clear any previous set[ug]id data from a previous binary */
1222 bprm->cred->euid = current_euid();
1223 bprm->cred->egid = current_egid();
1224
1225 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1226 /* Set-uid? */
1227 if (mode & S_ISUID) {
1228 bprm->per_clear |= PER_CLEAR_ON_SETID;
1229 bprm->cred->euid = inode->i_uid;
1230 }
1231
1232 /* Set-gid? */
1233 /*
1234 * If setgid is set but no group execute bit then this
1235 * is a candidate for mandatory locking, not a setgid
1236 * executable.
1237 */
1238 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1239 bprm->per_clear |= PER_CLEAR_ON_SETID;
1240 bprm->cred->egid = inode->i_gid;
1241 }
1242 }
1243
1244 /* fill in binprm security blob */
1245 retval = security_bprm_set_creds(bprm);
1246 if (retval)
1247 return retval;
1248 bprm->cred_prepared = 1;
1249
1250 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1251 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1252}
1253
1254EXPORT_SYMBOL(prepare_binprm);
1255
1256/*
1257 * Arguments are '\0' separated strings found at the location bprm->p
1258 * points to; chop off the first by relocating brpm->p to right after
1259 * the first '\0' encountered.
1260 */
1261int remove_arg_zero(struct linux_binprm *bprm)
1262{
1263 int ret = 0;
1264 unsigned long offset;
1265 char *kaddr;
1266 struct page *page;
1267
1268 if (!bprm->argc)
1269 return 0;
1270
1271 do {
1272 offset = bprm->p & ~PAGE_MASK;
1273 page = get_arg_page(bprm, bprm->p, 0);
1274 if (!page) {
1275 ret = -EFAULT;
1276 goto out;
1277 }
1278 kaddr = kmap_atomic(page, KM_USER0);
1279
1280 for (; offset < PAGE_SIZE && kaddr[offset];
1281 offset++, bprm->p++)
1282 ;
1283
1284 kunmap_atomic(kaddr, KM_USER0);
1285 put_arg_page(page);
1286
1287 if (offset == PAGE_SIZE)
1288 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1289 } while (offset == PAGE_SIZE);
1290
1291 bprm->p++;
1292 bprm->argc--;
1293 ret = 0;
1294
1295out:
1296 return ret;
1297}
1298EXPORT_SYMBOL(remove_arg_zero);
1299
1300/*
1301 * cycle the list of binary formats handler, until one recognizes the image
1302 */
1303int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1304{
1305 unsigned int depth = bprm->recursion_depth;
1306 int try,retval;
1307 struct linux_binfmt *fmt;
1308
1309 retval = security_bprm_check(bprm);
1310 if (retval)
1311 return retval;
1312
1313 /* kernel module loader fixup */
1314 /* so we don't try to load run modprobe in kernel space. */
1315 set_fs(USER_DS);
1316
1317 retval = audit_bprm(bprm);
1318 if (retval)
1319 return retval;
1320
1321 retval = -ENOENT;
1322 for (try=0; try<2; try++) {
1323 read_lock(&binfmt_lock);
1324 list_for_each_entry(fmt, &formats, lh) {
1325 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1326 if (!fn)
1327 continue;
1328 if (!try_module_get(fmt->module))
1329 continue;
1330 read_unlock(&binfmt_lock);
1331 retval = fn(bprm, regs);
1332 /*
1333 * Restore the depth counter to its starting value
1334 * in this call, so we don't have to rely on every
1335 * load_binary function to restore it on return.
1336 */
1337 bprm->recursion_depth = depth;
1338 if (retval >= 0) {
1339 if (depth == 0)
1340 tracehook_report_exec(fmt, bprm, regs);
1341 put_binfmt(fmt);
1342 allow_write_access(bprm->file);
1343 if (bprm->file)
1344 fput(bprm->file);
1345 bprm->file = NULL;
1346 current->did_exec = 1;
1347 proc_exec_connector(current);
1348 return retval;
1349 }
1350 read_lock(&binfmt_lock);
1351 put_binfmt(fmt);
1352 if (retval != -ENOEXEC || bprm->mm == NULL)
1353 break;
1354 if (!bprm->file) {
1355 read_unlock(&binfmt_lock);
1356 return retval;
1357 }
1358 }
1359 read_unlock(&binfmt_lock);
1360 if (retval != -ENOEXEC || bprm->mm == NULL) {
1361 break;
1362#ifdef CONFIG_MODULES
1363 } else {
1364#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1365 if (printable(bprm->buf[0]) &&
1366 printable(bprm->buf[1]) &&
1367 printable(bprm->buf[2]) &&
1368 printable(bprm->buf[3]))
1369 break; /* -ENOEXEC */
1370 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1371#endif
1372 }
1373 }
1374 return retval;
1375}
1376
1377EXPORT_SYMBOL(search_binary_handler);
1378
1379/*
1380 * sys_execve() executes a new program.
1381 */
1382int do_execve(const char * filename,
1383 const char __user *const __user *argv,
1384 const char __user *const __user *envp,
1385 struct pt_regs * regs)
1386{
1387 struct linux_binprm *bprm;
1388 struct file *file;
1389 struct files_struct *displaced;
1390 bool clear_in_exec;
1391 int retval;
1392
1393 retval = unshare_files(&displaced);
1394 if (retval)
1395 goto out_ret;
1396
1397 retval = -ENOMEM;
1398 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1399 if (!bprm)
1400 goto out_files;
1401
1402 retval = prepare_bprm_creds(bprm);
1403 if (retval)
1404 goto out_free;
1405
1406 retval = check_unsafe_exec(bprm);
1407 if (retval < 0)
1408 goto out_free;
1409 clear_in_exec = retval;
1410 current->in_execve = 1;
1411
1412 file = open_exec(filename);
1413 retval = PTR_ERR(file);
1414 if (IS_ERR(file))
1415 goto out_unmark;
1416
1417 sched_exec();
1418
1419 bprm->file = file;
1420 bprm->filename = filename;
1421 bprm->interp = filename;
1422
1423 retval = bprm_mm_init(bprm);
1424 if (retval)
1425 goto out_file;
1426
1427 bprm->argc = count(argv, MAX_ARG_STRINGS);
1428 if ((retval = bprm->argc) < 0)
1429 goto out;
1430
1431 bprm->envc = count(envp, MAX_ARG_STRINGS);
1432 if ((retval = bprm->envc) < 0)
1433 goto out;
1434
1435 retval = prepare_binprm(bprm);
1436 if (retval < 0)
1437 goto out;
1438
1439 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1440 if (retval < 0)
1441 goto out;
1442
1443 bprm->exec = bprm->p;
1444 retval = copy_strings(bprm->envc, envp, bprm);
1445 if (retval < 0)
1446 goto out;
1447
1448 retval = copy_strings(bprm->argc, argv, bprm);
1449 if (retval < 0)
1450 goto out;
1451
1452 retval = search_binary_handler(bprm,regs);
1453 if (retval < 0)
1454 goto out;
1455
1456 /* execve succeeded */
1457 current->fs->in_exec = 0;
1458 current->in_execve = 0;
1459 acct_update_integrals(current);
1460 free_bprm(bprm);
1461 if (displaced)
1462 put_files_struct(displaced);
1463 return retval;
1464
1465out:
1466 if (bprm->mm) {
1467 acct_arg_size(bprm, 0);
1468 mmput(bprm->mm);
1469 }
1470
1471out_file:
1472 if (bprm->file) {
1473 allow_write_access(bprm->file);
1474 fput(bprm->file);
1475 }
1476
1477out_unmark:
1478 if (clear_in_exec)
1479 current->fs->in_exec = 0;
1480 current->in_execve = 0;
1481
1482out_free:
1483 free_bprm(bprm);
1484
1485out_files:
1486 if (displaced)
1487 reset_files_struct(displaced);
1488out_ret:
1489 return retval;
1490}
1491
1492void set_binfmt(struct linux_binfmt *new)
1493{
1494 struct mm_struct *mm = current->mm;
1495
1496 if (mm->binfmt)
1497 module_put(mm->binfmt->module);
1498
1499 mm->binfmt = new;
1500 if (new)
1501 __module_get(new->module);
1502}
1503
1504EXPORT_SYMBOL(set_binfmt);
1505
1506static int expand_corename(struct core_name *cn)
1507{
1508 char *old_corename = cn->corename;
1509
1510 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1511 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1512
1513 if (!cn->corename) {
1514 kfree(old_corename);
1515 return -ENOMEM;
1516 }
1517
1518 return 0;
1519}
1520
1521static int cn_printf(struct core_name *cn, const char *fmt, ...)
1522{
1523 char *cur;
1524 int need;
1525 int ret;
1526 va_list arg;
1527
1528 va_start(arg, fmt);
1529 need = vsnprintf(NULL, 0, fmt, arg);
1530 va_end(arg);
1531
1532 if (likely(need < cn->size - cn->used - 1))
1533 goto out_printf;
1534
1535 ret = expand_corename(cn);
1536 if (ret)
1537 goto expand_fail;
1538
1539out_printf:
1540 cur = cn->corename + cn->used;
1541 va_start(arg, fmt);
1542 vsnprintf(cur, need + 1, fmt, arg);
1543 va_end(arg);
1544 cn->used += need;
1545 return 0;
1546
1547expand_fail:
1548 return ret;
1549}
1550
1551/* format_corename will inspect the pattern parameter, and output a
1552 * name into corename, which must have space for at least
1553 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1554 */
1555static int format_corename(struct core_name *cn, long signr)
1556{
1557 const struct cred *cred = current_cred();
1558 const char *pat_ptr = core_pattern;
1559 int ispipe = (*pat_ptr == '|');
1560 int pid_in_pattern = 0;
1561 int err = 0;
1562
1563 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1564 cn->corename = kmalloc(cn->size, GFP_KERNEL);
1565 cn->used = 0;
1566
1567 if (!cn->corename)
1568 return -ENOMEM;
1569
1570 /* Repeat as long as we have more pattern to process and more output
1571 space */
1572 while (*pat_ptr) {
1573 if (*pat_ptr != '%') {
1574 if (*pat_ptr == 0)
1575 goto out;
1576 err = cn_printf(cn, "%c", *pat_ptr++);
1577 } else {
1578 switch (*++pat_ptr) {
1579 /* single % at the end, drop that */
1580 case 0:
1581 goto out;
1582 /* Double percent, output one percent */
1583 case '%':
1584 err = cn_printf(cn, "%c", '%');
1585 break;
1586 /* pid */
1587 case 'p':
1588 pid_in_pattern = 1;
1589 err = cn_printf(cn, "%d",
1590 task_tgid_vnr(current));
1591 break;
1592 /* uid */
1593 case 'u':
1594 err = cn_printf(cn, "%d", cred->uid);
1595 break;
1596 /* gid */
1597 case 'g':
1598 err = cn_printf(cn, "%d", cred->gid);
1599 break;
1600 /* signal that caused the coredump */
1601 case 's':
1602 err = cn_printf(cn, "%ld", signr);
1603 break;
1604 /* UNIX time of coredump */
1605 case 't': {
1606 struct timeval tv;
1607 do_gettimeofday(&tv);
1608 err = cn_printf(cn, "%lu", tv.tv_sec);
1609 break;
1610 }
1611 /* hostname */
1612 case 'h':
1613 down_read(&uts_sem);
1614 err = cn_printf(cn, "%s",
1615 utsname()->nodename);
1616 up_read(&uts_sem);
1617 break;
1618 /* executable */
1619 case 'e':
1620 err = cn_printf(cn, "%s", current->comm);
1621 break;
1622 /* core limit size */
1623 case 'c':
1624 err = cn_printf(cn, "%lu",
1625 rlimit(RLIMIT_CORE));
1626 break;
1627 default:
1628 break;
1629 }
1630 ++pat_ptr;
1631 }
1632
1633 if (err)
1634 return err;
1635 }
1636
1637 /* Backward compatibility with core_uses_pid:
1638 *
1639 * If core_pattern does not include a %p (as is the default)
1640 * and core_uses_pid is set, then .%pid will be appended to
1641 * the filename. Do not do this for piped commands. */
1642 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1643 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1644 if (err)
1645 return err;
1646 }
1647out:
1648 return ispipe;
1649}
1650
1651static int zap_process(struct task_struct *start, int exit_code)
1652{
1653 struct task_struct *t;
1654 int nr = 0;
1655
1656 start->signal->flags = SIGNAL_GROUP_EXIT;
1657 start->signal->group_exit_code = exit_code;
1658 start->signal->group_stop_count = 0;
1659
1660 t = start;
1661 do {
1662 if (t != current && t->mm) {
1663 sigaddset(&t->pending.signal, SIGKILL);
1664 signal_wake_up(t, 1);
1665 nr++;
1666 }
1667 } while_each_thread(start, t);
1668
1669 return nr;
1670}
1671
1672static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1673 struct core_state *core_state, int exit_code)
1674{
1675 struct task_struct *g, *p;
1676 unsigned long flags;
1677 int nr = -EAGAIN;
1678
1679 spin_lock_irq(&tsk->sighand->siglock);
1680 if (!signal_group_exit(tsk->signal)) {
1681 mm->core_state = core_state;
1682 nr = zap_process(tsk, exit_code);
1683 }
1684 spin_unlock_irq(&tsk->sighand->siglock);
1685 if (unlikely(nr < 0))
1686 return nr;
1687
1688 if (atomic_read(&mm->mm_users) == nr + 1)
1689 goto done;
1690 /*
1691 * We should find and kill all tasks which use this mm, and we should
1692 * count them correctly into ->nr_threads. We don't take tasklist
1693 * lock, but this is safe wrt:
1694 *
1695 * fork:
1696 * None of sub-threads can fork after zap_process(leader). All
1697 * processes which were created before this point should be
1698 * visible to zap_threads() because copy_process() adds the new
1699 * process to the tail of init_task.tasks list, and lock/unlock
1700 * of ->siglock provides a memory barrier.
1701 *
1702 * do_exit:
1703 * The caller holds mm->mmap_sem. This means that the task which
1704 * uses this mm can't pass exit_mm(), so it can't exit or clear
1705 * its ->mm.
1706 *
1707 * de_thread:
1708 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1709 * we must see either old or new leader, this does not matter.
1710 * However, it can change p->sighand, so lock_task_sighand(p)
1711 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1712 * it can't fail.
1713 *
1714 * Note also that "g" can be the old leader with ->mm == NULL
1715 * and already unhashed and thus removed from ->thread_group.
1716 * This is OK, __unhash_process()->list_del_rcu() does not
1717 * clear the ->next pointer, we will find the new leader via
1718 * next_thread().
1719 */
1720 rcu_read_lock();
1721 for_each_process(g) {
1722 if (g == tsk->group_leader)
1723 continue;
1724 if (g->flags & PF_KTHREAD)
1725 continue;
1726 p = g;
1727 do {
1728 if (p->mm) {
1729 if (unlikely(p->mm == mm)) {
1730 lock_task_sighand(p, &flags);
1731 nr += zap_process(p, exit_code);
1732 unlock_task_sighand(p, &flags);
1733 }
1734 break;
1735 }
1736 } while_each_thread(g, p);
1737 }
1738 rcu_read_unlock();
1739done:
1740 atomic_set(&core_state->nr_threads, nr);
1741 return nr;
1742}
1743
1744static int coredump_wait(int exit_code, struct core_state *core_state)
1745{
1746 struct task_struct *tsk = current;
1747 struct mm_struct *mm = tsk->mm;
1748 struct completion *vfork_done;
1749 int core_waiters = -EBUSY;
1750
1751 init_completion(&core_state->startup);
1752 core_state->dumper.task = tsk;
1753 core_state->dumper.next = NULL;
1754
1755 down_write(&mm->mmap_sem);
1756 if (!mm->core_state)
1757 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1758 up_write(&mm->mmap_sem);
1759
1760 if (unlikely(core_waiters < 0))
1761 goto fail;
1762
1763 /*
1764 * Make sure nobody is waiting for us to release the VM,
1765 * otherwise we can deadlock when we wait on each other
1766 */
1767 vfork_done = tsk->vfork_done;
1768 if (vfork_done) {
1769 tsk->vfork_done = NULL;
1770 complete(vfork_done);
1771 }
1772
1773 if (core_waiters)
1774 wait_for_completion(&core_state->startup);
1775fail:
1776 return core_waiters;
1777}
1778
1779static void coredump_finish(struct mm_struct *mm)
1780{
1781 struct core_thread *curr, *next;
1782 struct task_struct *task;
1783
1784 next = mm->core_state->dumper.next;
1785 while ((curr = next) != NULL) {
1786 next = curr->next;
1787 task = curr->task;
1788 /*
1789 * see exit_mm(), curr->task must not see
1790 * ->task == NULL before we read ->next.
1791 */
1792 smp_mb();
1793 curr->task = NULL;
1794 wake_up_process(task);
1795 }
1796
1797 mm->core_state = NULL;
1798}
1799
1800/*
1801 * set_dumpable converts traditional three-value dumpable to two flags and
1802 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1803 * these bits are not changed atomically. So get_dumpable can observe the
1804 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1805 * return either old dumpable or new one by paying attention to the order of
1806 * modifying the bits.
1807 *
1808 * dumpable | mm->flags (binary)
1809 * old new | initial interim final
1810 * ---------+-----------------------
1811 * 0 1 | 00 01 01
1812 * 0 2 | 00 10(*) 11
1813 * 1 0 | 01 00 00
1814 * 1 2 | 01 11 11
1815 * 2 0 | 11 10(*) 00
1816 * 2 1 | 11 11 01
1817 *
1818 * (*) get_dumpable regards interim value of 10 as 11.
1819 */
1820void set_dumpable(struct mm_struct *mm, int value)
1821{
1822 switch (value) {
1823 case 0:
1824 clear_bit(MMF_DUMPABLE, &mm->flags);
1825 smp_wmb();
1826 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1827 break;
1828 case 1:
1829 set_bit(MMF_DUMPABLE, &mm->flags);
1830 smp_wmb();
1831 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1832 break;
1833 case 2:
1834 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1835 smp_wmb();
1836 set_bit(MMF_DUMPABLE, &mm->flags);
1837 break;
1838 }
1839}
1840
1841static int __get_dumpable(unsigned long mm_flags)
1842{
1843 int ret;
1844
1845 ret = mm_flags & MMF_DUMPABLE_MASK;
1846 return (ret >= 2) ? 2 : ret;
1847}
1848
1849int get_dumpable(struct mm_struct *mm)
1850{
1851 return __get_dumpable(mm->flags);
1852}
1853
1854static void wait_for_dump_helpers(struct file *file)
1855{
1856 struct pipe_inode_info *pipe;
1857
1858 pipe = file->f_path.dentry->d_inode->i_pipe;
1859
1860 pipe_lock(pipe);
1861 pipe->readers++;
1862 pipe->writers--;
1863
1864 while ((pipe->readers > 1) && (!signal_pending(current))) {
1865 wake_up_interruptible_sync(&pipe->wait);
1866 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1867 pipe_wait(pipe);
1868 }
1869
1870 pipe->readers--;
1871 pipe->writers++;
1872 pipe_unlock(pipe);
1873
1874}
1875
1876
1877/*
1878 * umh_pipe_setup
1879 * helper function to customize the process used
1880 * to collect the core in userspace. Specifically
1881 * it sets up a pipe and installs it as fd 0 (stdin)
1882 * for the process. Returns 0 on success, or
1883 * PTR_ERR on failure.
1884 * Note that it also sets the core limit to 1. This
1885 * is a special value that we use to trap recursive
1886 * core dumps
1887 */
1888static int umh_pipe_setup(struct subprocess_info *info)
1889{
1890 struct file *rp, *wp;
1891 struct fdtable *fdt;
1892 struct coredump_params *cp = (struct coredump_params *)info->data;
1893 struct files_struct *cf = current->files;
1894
1895 wp = create_write_pipe(0);
1896 if (IS_ERR(wp))
1897 return PTR_ERR(wp);
1898
1899 rp = create_read_pipe(wp, 0);
1900 if (IS_ERR(rp)) {
1901 free_write_pipe(wp);
1902 return PTR_ERR(rp);
1903 }
1904
1905 cp->file = wp;
1906
1907 sys_close(0);
1908 fd_install(0, rp);
1909 spin_lock(&cf->file_lock);
1910 fdt = files_fdtable(cf);
1911 FD_SET(0, fdt->open_fds);
1912 FD_CLR(0, fdt->close_on_exec);
1913 spin_unlock(&cf->file_lock);
1914
1915 /* and disallow core files too */
1916 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
1917
1918 return 0;
1919}
1920
1921void do_coredump(long signr, int exit_code, struct pt_regs *regs)
1922{
1923 struct core_state core_state;
1924 struct core_name cn;
1925 struct mm_struct *mm = current->mm;
1926 struct linux_binfmt * binfmt;
1927 const struct cred *old_cred;
1928 struct cred *cred;
1929 int retval = 0;
1930 int flag = 0;
1931 int ispipe;
1932 static atomic_t core_dump_count = ATOMIC_INIT(0);
1933 struct coredump_params cprm = {
1934 .signr = signr,
1935 .regs = regs,
1936 .limit = rlimit(RLIMIT_CORE),
1937 /*
1938 * We must use the same mm->flags while dumping core to avoid
1939 * inconsistency of bit flags, since this flag is not protected
1940 * by any locks.
1941 */
1942 .mm_flags = mm->flags,
1943 };
1944
1945 audit_core_dumps(signr);
1946
1947 binfmt = mm->binfmt;
1948 if (!binfmt || !binfmt->core_dump)
1949 goto fail;
1950 if (!__get_dumpable(cprm.mm_flags))
1951 goto fail;
1952
1953 cred = prepare_creds();
1954 if (!cred)
1955 goto fail;
1956 /*
1957 * We cannot trust fsuid as being the "true" uid of the
1958 * process nor do we know its entire history. We only know it
1959 * was tainted so we dump it as root in mode 2.
1960 */
1961 if (__get_dumpable(cprm.mm_flags) == 2) {
1962 /* Setuid core dump mode */
1963 flag = O_EXCL; /* Stop rewrite attacks */
1964 cred->fsuid = 0; /* Dump root private */
1965 }
1966
1967 retval = coredump_wait(exit_code, &core_state);
1968 if (retval < 0)
1969 goto fail_creds;
1970
1971 old_cred = override_creds(cred);
1972
1973 /*
1974 * Clear any false indication of pending signals that might
1975 * be seen by the filesystem code called to write the core file.
1976 */
1977 clear_thread_flag(TIF_SIGPENDING);
1978
1979 ispipe = format_corename(&cn, signr);
1980
1981 if (ispipe == -ENOMEM) {
1982 printk(KERN_WARNING "format_corename failed\n");
1983 printk(KERN_WARNING "Aborting core\n");
1984 goto fail_corename;
1985 }
1986
1987 if (ispipe) {
1988 int dump_count;
1989 char **helper_argv;
1990
1991 if (cprm.limit == 1) {
1992 /*
1993 * Normally core limits are irrelevant to pipes, since
1994 * we're not writing to the file system, but we use
1995 * cprm.limit of 1 here as a speacial value. Any
1996 * non-1 limit gets set to RLIM_INFINITY below, but
1997 * a limit of 0 skips the dump. This is a consistent
1998 * way to catch recursive crashes. We can still crash
1999 * if the core_pattern binary sets RLIM_CORE = !1
2000 * but it runs as root, and can do lots of stupid things
2001 * Note that we use task_tgid_vnr here to grab the pid
2002 * of the process group leader. That way we get the
2003 * right pid if a thread in a multi-threaded
2004 * core_pattern process dies.
2005 */
2006 printk(KERN_WARNING
2007 "Process %d(%s) has RLIMIT_CORE set to 1\n",
2008 task_tgid_vnr(current), current->comm);
2009 printk(KERN_WARNING "Aborting core\n");
2010 goto fail_unlock;
2011 }
2012 cprm.limit = RLIM_INFINITY;
2013
2014 dump_count = atomic_inc_return(&core_dump_count);
2015 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2016 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2017 task_tgid_vnr(current), current->comm);
2018 printk(KERN_WARNING "Skipping core dump\n");
2019 goto fail_dropcount;
2020 }
2021
2022 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2023 if (!helper_argv) {
2024 printk(KERN_WARNING "%s failed to allocate memory\n",
2025 __func__);
2026 goto fail_dropcount;
2027 }
2028
2029 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2030 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2031 NULL, &cprm);
2032 argv_free(helper_argv);
2033 if (retval) {
2034 printk(KERN_INFO "Core dump to %s pipe failed\n",
2035 cn.corename);
2036 goto close_fail;
2037 }
2038 } else {
2039 struct inode *inode;
2040
2041 if (cprm.limit < binfmt->min_coredump)
2042 goto fail_unlock;
2043
2044 cprm.file = filp_open(cn.corename,
2045 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2046 0600);
2047 if (IS_ERR(cprm.file))
2048 goto fail_unlock;
2049
2050 inode = cprm.file->f_path.dentry->d_inode;
2051 if (inode->i_nlink > 1)
2052 goto close_fail;
2053 if (d_unhashed(cprm.file->f_path.dentry))
2054 goto close_fail;
2055 /*
2056 * AK: actually i see no reason to not allow this for named
2057 * pipes etc, but keep the previous behaviour for now.
2058 */
2059 if (!S_ISREG(inode->i_mode))
2060 goto close_fail;
2061 /*
2062 * Dont allow local users get cute and trick others to coredump
2063 * into their pre-created files.
2064 */
2065 if (inode->i_uid != current_fsuid())
2066 goto close_fail;
2067 if (!cprm.file->f_op || !cprm.file->f_op->write)
2068 goto close_fail;
2069 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2070 goto close_fail;
2071 }
2072
2073 retval = binfmt->core_dump(&cprm);
2074 if (retval)
2075 current->signal->group_exit_code |= 0x80;
2076
2077 if (ispipe && core_pipe_limit)
2078 wait_for_dump_helpers(cprm.file);
2079close_fail:
2080 if (cprm.file)
2081 filp_close(cprm.file, NULL);
2082fail_dropcount:
2083 if (ispipe)
2084 atomic_dec(&core_dump_count);
2085fail_unlock:
2086 kfree(cn.corename);
2087fail_corename:
2088 coredump_finish(mm);
2089 revert_creds(old_cred);
2090fail_creds:
2091 put_cred(cred);
2092fail:
2093 return;
2094}
2095
2096/*
2097 * Core dumping helper functions. These are the only things you should
2098 * do on a core-file: use only these functions to write out all the
2099 * necessary info.
2100 */
2101int dump_write(struct file *file, const void *addr, int nr)
2102{
2103 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2104}
2105EXPORT_SYMBOL(dump_write);
2106
2107int dump_seek(struct file *file, loff_t off)
2108{
2109 int ret = 1;
2110
2111 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2112 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2113 return 0;
2114 } else {
2115 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2116
2117 if (!buf)
2118 return 0;
2119 while (off > 0) {
2120 unsigned long n = off;
2121
2122 if (n > PAGE_SIZE)
2123 n = PAGE_SIZE;
2124 if (!dump_write(file, buf, n)) {
2125 ret = 0;
2126 break;
2127 }
2128 off -= n;
2129 }
2130 free_page((unsigned long)buf);
2131 }
2132 return ret;
2133}
2134EXPORT_SYMBOL(dump_seek);