projects/linux·blob v3.5-rc1 · refs

2316 lines · 53.2 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/mount.h>
46#include <linux/security.h>
47#include <linux/syscalls.h>
48#include <linux/tsacct_kern.h>
49#include <linux/cn_proc.h>
50#include <linux/audit.h>
51#include <linux/tracehook.h>
52#include <linux/kmod.h>
53#include <linux/fsnotify.h>
54#include <linux/fs_struct.h>
55#include <linux/pipe_fs_i.h>
56#include <linux/oom.h>
57#include <linux/compat.h>
58
59#include <asm/uaccess.h>
60#include <asm/mmu_context.h>
61#include <asm/tlb.h>
62#include <asm/exec.h>
63
64#include <trace/events/task.h>
65#include "internal.h"
66
67#include <trace/events/sched.h>
68
69int core_uses_pid;
70char core_pattern[CORENAME_MAX_SIZE] = "core";
71unsigned int core_pipe_limit;
72int suid_dumpable = 0;
73
74struct core_name {
75 char *corename;
76 int used, size;
77};
78static atomic_t call_count = ATOMIC_INIT(1);
79
80/* The maximal length of core_pattern is also specified in sysctl.c */
81
82static LIST_HEAD(formats);
83static DEFINE_RWLOCK(binfmt_lock);
84
85void __register_binfmt(struct linux_binfmt * fmt, int insert)
86{
87 BUG_ON(!fmt);
88 write_lock(&binfmt_lock);
89 insert ? list_add(&fmt->lh, &formats) :
90 list_add_tail(&fmt->lh, &formats);
91 write_unlock(&binfmt_lock);
92}
93
94EXPORT_SYMBOL(__register_binfmt);
95
96void unregister_binfmt(struct linux_binfmt * fmt)
97{
98 write_lock(&binfmt_lock);
99 list_del(&fmt->lh);
100 write_unlock(&binfmt_lock);
101}
102
103EXPORT_SYMBOL(unregister_binfmt);
104
105static inline void put_binfmt(struct linux_binfmt * fmt)
106{
107 module_put(fmt->module);
108}
109
110/*
111 * Note that a shared library must be both readable and executable due to
112 * security reasons.
113 *
114 * Also note that we take the address to load from from the file itself.
115 */
116SYSCALL_DEFINE1(uselib, const char __user *, library)
117{
118 struct file *file;
119 char *tmp = getname(library);
120 int error = PTR_ERR(tmp);
121 static const struct open_flags uselib_flags = {
122 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
123 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
124 .intent = LOOKUP_OPEN
125 };
126
127 if (IS_ERR(tmp))
128 goto out;
129
130 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags, LOOKUP_FOLLOW);
131 putname(tmp);
132 error = PTR_ERR(file);
133 if (IS_ERR(file))
134 goto out;
135
136 error = -EINVAL;
137 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
138 goto exit;
139
140 error = -EACCES;
141 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
142 goto exit;
143
144 fsnotify_open(file);
145
146 error = -ENOEXEC;
147 if(file->f_op) {
148 struct linux_binfmt * fmt;
149
150 read_lock(&binfmt_lock);
151 list_for_each_entry(fmt, &formats, lh) {
152 if (!fmt->load_shlib)
153 continue;
154 if (!try_module_get(fmt->module))
155 continue;
156 read_unlock(&binfmt_lock);
157 error = fmt->load_shlib(file);
158 read_lock(&binfmt_lock);
159 put_binfmt(fmt);
160 if (error != -ENOEXEC)
161 break;
162 }
163 read_unlock(&binfmt_lock);
164 }
165exit:
166 fput(file);
167out:
168 return error;
169}
170
171#ifdef CONFIG_MMU
172/*
173 * The nascent bprm->mm is not visible until exec_mmap() but it can
174 * use a lot of memory, account these pages in current->mm temporary
175 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
176 * change the counter back via acct_arg_size(0).
177 */
178static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
179{
180 struct mm_struct *mm = current->mm;
181 long diff = (long)(pages - bprm->vma_pages);
182
183 if (!mm || !diff)
184 return;
185
186 bprm->vma_pages = pages;
187 add_mm_counter(mm, MM_ANONPAGES, diff);
188}
189
190static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
191 int write)
192{
193 struct page *page;
194 int ret;
195
196#ifdef CONFIG_STACK_GROWSUP
197 if (write) {
198 ret = expand_downwards(bprm->vma, pos);
199 if (ret < 0)
200 return NULL;
201 }
202#endif
203 ret = get_user_pages(current, bprm->mm, pos,
204 1, write, 1, &page, NULL);
205 if (ret <= 0)
206 return NULL;
207
208 if (write) {
209 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
210 struct rlimit *rlim;
211
212 acct_arg_size(bprm, size / PAGE_SIZE);
213
214 /*
215 * We've historically supported up to 32 pages (ARG_MAX)
216 * of argument strings even with small stacks
217 */
218 if (size <= ARG_MAX)
219 return page;
220
221 /*
222 * Limit to 1/4-th the stack size for the argv+env strings.
223 * This ensures that:
224 * - the remaining binfmt code will not run out of stack space,
225 * - the program will have a reasonable amount of stack left
226 * to work from.
227 */
228 rlim = current->signal->rlim;
229 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
230 put_page(page);
231 return NULL;
232 }
233 }
234
235 return page;
236}
237
238static void put_arg_page(struct page *page)
239{
240 put_page(page);
241}
242
243static void free_arg_page(struct linux_binprm *bprm, int i)
244{
245}
246
247static void free_arg_pages(struct linux_binprm *bprm)
248{
249}
250
251static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
252 struct page *page)
253{
254 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
255}
256
257static int __bprm_mm_init(struct linux_binprm *bprm)
258{
259 int err;
260 struct vm_area_struct *vma = NULL;
261 struct mm_struct *mm = bprm->mm;
262
263 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
264 if (!vma)
265 return -ENOMEM;
266
267 down_write(&mm->mmap_sem);
268 vma->vm_mm = mm;
269
270 /*
271 * Place the stack at the largest stack address the architecture
272 * supports. Later, we'll move this to an appropriate place. We don't
273 * use STACK_TOP because that can depend on attributes which aren't
274 * configured yet.
275 */
276 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
277 vma->vm_end = STACK_TOP_MAX;
278 vma->vm_start = vma->vm_end - PAGE_SIZE;
279 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
280 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
281 INIT_LIST_HEAD(&vma->anon_vma_chain);
282
283 err = insert_vm_struct(mm, vma);
284 if (err)
285 goto err;
286
287 mm->stack_vm = mm->total_vm = 1;
288 up_write(&mm->mmap_sem);
289 bprm->p = vma->vm_end - sizeof(void *);
290 return 0;
291err:
292 up_write(&mm->mmap_sem);
293 bprm->vma = NULL;
294 kmem_cache_free(vm_area_cachep, vma);
295 return err;
296}
297
298static bool valid_arg_len(struct linux_binprm *bprm, long len)
299{
300 return len <= MAX_ARG_STRLEN;
301}
302
303#else
304
305static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
306{
307}
308
309static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
310 int write)
311{
312 struct page *page;
313
314 page = bprm->page[pos / PAGE_SIZE];
315 if (!page && write) {
316 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
317 if (!page)
318 return NULL;
319 bprm->page[pos / PAGE_SIZE] = page;
320 }
321
322 return page;
323}
324
325static void put_arg_page(struct page *page)
326{
327}
328
329static void free_arg_page(struct linux_binprm *bprm, int i)
330{
331 if (bprm->page[i]) {
332 __free_page(bprm->page[i]);
333 bprm->page[i] = NULL;
334 }
335}
336
337static void free_arg_pages(struct linux_binprm *bprm)
338{
339 int i;
340
341 for (i = 0; i < MAX_ARG_PAGES; i++)
342 free_arg_page(bprm, i);
343}
344
345static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
346 struct page *page)
347{
348}
349
350static int __bprm_mm_init(struct linux_binprm *bprm)
351{
352 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
353 return 0;
354}
355
356static bool valid_arg_len(struct linux_binprm *bprm, long len)
357{
358 return len <= bprm->p;
359}
360
361#endif /* CONFIG_MMU */
362
363/*
364 * Create a new mm_struct and populate it with a temporary stack
365 * vm_area_struct. We don't have enough context at this point to set the stack
366 * flags, permissions, and offset, so we use temporary values. We'll update
367 * them later in setup_arg_pages().
368 */
369int bprm_mm_init(struct linux_binprm *bprm)
370{
371 int err;
372 struct mm_struct *mm = NULL;
373
374 bprm->mm = mm = mm_alloc();
375 err = -ENOMEM;
376 if (!mm)
377 goto err;
378
379 err = init_new_context(current, mm);
380 if (err)
381 goto err;
382
383 err = __bprm_mm_init(bprm);
384 if (err)
385 goto err;
386
387 return 0;
388
389err:
390 if (mm) {
391 bprm->mm = NULL;
392 mmdrop(mm);
393 }
394
395 return err;
396}
397
398struct user_arg_ptr {
399#ifdef CONFIG_COMPAT
400 bool is_compat;
401#endif
402 union {
403 const char __user *const __user *native;
404#ifdef CONFIG_COMPAT
405 compat_uptr_t __user *compat;
406#endif
407 } ptr;
408};
409
410static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
411{
412 const char __user *native;
413
414#ifdef CONFIG_COMPAT
415 if (unlikely(argv.is_compat)) {
416 compat_uptr_t compat;
417
418 if (get_user(compat, argv.ptr.compat + nr))
419 return ERR_PTR(-EFAULT);
420
421 return compat_ptr(compat);
422 }
423#endif
424
425 if (get_user(native, argv.ptr.native + nr))
426 return ERR_PTR(-EFAULT);
427
428 return native;
429}
430
431/*
432 * count() counts the number of strings in array ARGV.
433 */
434static int count(struct user_arg_ptr argv, int max)
435{
436 int i = 0;
437
438 if (argv.ptr.native != NULL) {
439 for (;;) {
440 const char __user *p = get_user_arg_ptr(argv, i);
441
442 if (!p)
443 break;
444
445 if (IS_ERR(p))
446 return -EFAULT;
447
448 if (i++ >= max)
449 return -E2BIG;
450
451 if (fatal_signal_pending(current))
452 return -ERESTARTNOHAND;
453 cond_resched();
454 }
455 }
456 return i;
457}
458
459/*
460 * 'copy_strings()' copies argument/environment strings from the old
461 * processes's memory to the new process's stack. The call to get_user_pages()
462 * ensures the destination page is created and not swapped out.
463 */
464static int copy_strings(int argc, struct user_arg_ptr argv,
465 struct linux_binprm *bprm)
466{
467 struct page *kmapped_page = NULL;
468 char *kaddr = NULL;
469 unsigned long kpos = 0;
470 int ret;
471
472 while (argc-- > 0) {
473 const char __user *str;
474 int len;
475 unsigned long pos;
476
477 ret = -EFAULT;
478 str = get_user_arg_ptr(argv, argc);
479 if (IS_ERR(str))
480 goto out;
481
482 len = strnlen_user(str, MAX_ARG_STRLEN);
483 if (!len)
484 goto out;
485
486 ret = -E2BIG;
487 if (!valid_arg_len(bprm, len))
488 goto out;
489
490 /* We're going to work our way backwords. */
491 pos = bprm->p;
492 str += len;
493 bprm->p -= len;
494
495 while (len > 0) {
496 int offset, bytes_to_copy;
497
498 if (fatal_signal_pending(current)) {
499 ret = -ERESTARTNOHAND;
500 goto out;
501 }
502 cond_resched();
503
504 offset = pos % PAGE_SIZE;
505 if (offset == 0)
506 offset = PAGE_SIZE;
507
508 bytes_to_copy = offset;
509 if (bytes_to_copy > len)
510 bytes_to_copy = len;
511
512 offset -= bytes_to_copy;
513 pos -= bytes_to_copy;
514 str -= bytes_to_copy;
515 len -= bytes_to_copy;
516
517 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
518 struct page *page;
519
520 page = get_arg_page(bprm, pos, 1);
521 if (!page) {
522 ret = -E2BIG;
523 goto out;
524 }
525
526 if (kmapped_page) {
527 flush_kernel_dcache_page(kmapped_page);
528 kunmap(kmapped_page);
529 put_arg_page(kmapped_page);
530 }
531 kmapped_page = page;
532 kaddr = kmap(kmapped_page);
533 kpos = pos & PAGE_MASK;
534 flush_arg_page(bprm, kpos, kmapped_page);
535 }
536 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
537 ret = -EFAULT;
538 goto out;
539 }
540 }
541 }
542 ret = 0;
543out:
544 if (kmapped_page) {
545 flush_kernel_dcache_page(kmapped_page);
546 kunmap(kmapped_page);
547 put_arg_page(kmapped_page);
548 }
549 return ret;
550}
551
552/*
553 * Like copy_strings, but get argv and its values from kernel memory.
554 */
555int copy_strings_kernel(int argc, const char *const *__argv,
556 struct linux_binprm *bprm)
557{
558 int r;
559 mm_segment_t oldfs = get_fs();
560 struct user_arg_ptr argv = {
561 .ptr.native = (const char __user *const __user *)__argv,
562 };
563
564 set_fs(KERNEL_DS);
565 r = copy_strings(argc, argv, bprm);
566 set_fs(oldfs);
567
568 return r;
569}
570EXPORT_SYMBOL(copy_strings_kernel);
571
572#ifdef CONFIG_MMU
573
574/*
575 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
576 * the binfmt code determines where the new stack should reside, we shift it to
577 * its final location. The process proceeds as follows:
578 *
579 * 1) Use shift to calculate the new vma endpoints.
580 * 2) Extend vma to cover both the old and new ranges. This ensures the
581 * arguments passed to subsequent functions are consistent.
582 * 3) Move vma's page tables to the new range.
583 * 4) Free up any cleared pgd range.
584 * 5) Shrink the vma to cover only the new range.
585 */
586static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
587{
588 struct mm_struct *mm = vma->vm_mm;
589 unsigned long old_start = vma->vm_start;
590 unsigned long old_end = vma->vm_end;
591 unsigned long length = old_end - old_start;
592 unsigned long new_start = old_start - shift;
593 unsigned long new_end = old_end - shift;
594 struct mmu_gather tlb;
595
596 BUG_ON(new_start > new_end);
597
598 /*
599 * ensure there are no vmas between where we want to go
600 * and where we are
601 */
602 if (vma != find_vma(mm, new_start))
603 return -EFAULT;
604
605 /*
606 * cover the whole range: [new_start, old_end)
607 */
608 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
609 return -ENOMEM;
610
611 /*
612 * move the page tables downwards, on failure we rely on
613 * process cleanup to remove whatever mess we made.
614 */
615 if (length != move_page_tables(vma, old_start,
616 vma, new_start, length))
617 return -ENOMEM;
618
619 lru_add_drain();
620 tlb_gather_mmu(&tlb, mm, 0);
621 if (new_end > old_start) {
622 /*
623 * when the old and new regions overlap clear from new_end.
624 */
625 free_pgd_range(&tlb, new_end, old_end, new_end,
626 vma->vm_next ? vma->vm_next->vm_start : 0);
627 } else {
628 /*
629 * otherwise, clean from old_start; this is done to not touch
630 * the address space in [new_end, old_start) some architectures
631 * have constraints on va-space that make this illegal (IA64) -
632 * for the others its just a little faster.
633 */
634 free_pgd_range(&tlb, old_start, old_end, new_end,
635 vma->vm_next ? vma->vm_next->vm_start : 0);
636 }
637 tlb_finish_mmu(&tlb, new_end, old_end);
638
639 /*
640 * Shrink the vma to just the new range. Always succeeds.
641 */
642 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
643
644 return 0;
645}
646
647/*
648 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
649 * the stack is optionally relocated, and some extra space is added.
650 */
651int setup_arg_pages(struct linux_binprm *bprm,
652 unsigned long stack_top,
653 int executable_stack)
654{
655 unsigned long ret;
656 unsigned long stack_shift;
657 struct mm_struct *mm = current->mm;
658 struct vm_area_struct *vma = bprm->vma;
659 struct vm_area_struct *prev = NULL;
660 unsigned long vm_flags;
661 unsigned long stack_base;
662 unsigned long stack_size;
663 unsigned long stack_expand;
664 unsigned long rlim_stack;
665
666#ifdef CONFIG_STACK_GROWSUP
667 /* Limit stack size to 1GB */
668 stack_base = rlimit_max(RLIMIT_STACK);
669 if (stack_base > (1 << 30))
670 stack_base = 1 << 30;
671
672 /* Make sure we didn't let the argument array grow too large. */
673 if (vma->vm_end - vma->vm_start > stack_base)
674 return -ENOMEM;
675
676 stack_base = PAGE_ALIGN(stack_top - stack_base);
677
678 stack_shift = vma->vm_start - stack_base;
679 mm->arg_start = bprm->p - stack_shift;
680 bprm->p = vma->vm_end - stack_shift;
681#else
682 stack_top = arch_align_stack(stack_top);
683 stack_top = PAGE_ALIGN(stack_top);
684
685 if (unlikely(stack_top < mmap_min_addr) ||
686 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
687 return -ENOMEM;
688
689 stack_shift = vma->vm_end - stack_top;
690
691 bprm->p -= stack_shift;
692 mm->arg_start = bprm->p;
693#endif
694
695 if (bprm->loader)
696 bprm->loader -= stack_shift;
697 bprm->exec -= stack_shift;
698
699 down_write(&mm->mmap_sem);
700 vm_flags = VM_STACK_FLAGS;
701
702 /*
703 * Adjust stack execute permissions; explicitly enable for
704 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
705 * (arch default) otherwise.
706 */
707 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
708 vm_flags |= VM_EXEC;
709 else if (executable_stack == EXSTACK_DISABLE_X)
710 vm_flags &= ~VM_EXEC;
711 vm_flags |= mm->def_flags;
712 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
713
714 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
715 vm_flags);
716 if (ret)
717 goto out_unlock;
718 BUG_ON(prev != vma);
719
720 /* Move stack pages down in memory. */
721 if (stack_shift) {
722 ret = shift_arg_pages(vma, stack_shift);
723 if (ret)
724 goto out_unlock;
725 }
726
727 /* mprotect_fixup is overkill to remove the temporary stack flags */
728 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
729
730 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
731 stack_size = vma->vm_end - vma->vm_start;
732 /*
733 * Align this down to a page boundary as expand_stack
734 * will align it up.
735 */
736 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
737#ifdef CONFIG_STACK_GROWSUP
738 if (stack_size + stack_expand > rlim_stack)
739 stack_base = vma->vm_start + rlim_stack;
740 else
741 stack_base = vma->vm_end + stack_expand;
742#else
743 if (stack_size + stack_expand > rlim_stack)
744 stack_base = vma->vm_end - rlim_stack;
745 else
746 stack_base = vma->vm_start - stack_expand;
747#endif
748 current->mm->start_stack = bprm->p;
749 ret = expand_stack(vma, stack_base);
750 if (ret)
751 ret = -EFAULT;
752
753out_unlock:
754 up_write(&mm->mmap_sem);
755 return ret;
756}
757EXPORT_SYMBOL(setup_arg_pages);
758
759#endif /* CONFIG_MMU */
760
761struct file *open_exec(const char *name)
762{
763 struct file *file;
764 int err;
765 static const struct open_flags open_exec_flags = {
766 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
767 .acc_mode = MAY_EXEC | MAY_OPEN,
768 .intent = LOOKUP_OPEN
769 };
770
771 file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
772 if (IS_ERR(file))
773 goto out;
774
775 err = -EACCES;
776 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
777 goto exit;
778
779 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
780 goto exit;
781
782 fsnotify_open(file);
783
784 err = deny_write_access(file);
785 if (err)
786 goto exit;
787
788out:
789 return file;
790
791exit:
792 fput(file);
793 return ERR_PTR(err);
794}
795EXPORT_SYMBOL(open_exec);
796
797int kernel_read(struct file *file, loff_t offset,
798 char *addr, unsigned long count)
799{
800 mm_segment_t old_fs;
801 loff_t pos = offset;
802 int result;
803
804 old_fs = get_fs();
805 set_fs(get_ds());
806 /* The cast to a user pointer is valid due to the set_fs() */
807 result = vfs_read(file, (void __user *)addr, count, &pos);
808 set_fs(old_fs);
809 return result;
810}
811
812EXPORT_SYMBOL(kernel_read);
813
814static int exec_mmap(struct mm_struct *mm)
815{
816 struct task_struct *tsk;
817 struct mm_struct * old_mm, *active_mm;
818
819 /* Notify parent that we're no longer interested in the old VM */
820 tsk = current;
821 old_mm = current->mm;
822 sync_mm_rss(old_mm);
823 mm_release(tsk, old_mm);
824
825 if (old_mm) {
826 /*
827 * Make sure that if there is a core dump in progress
828 * for the old mm, we get out and die instead of going
829 * through with the exec. We must hold mmap_sem around
830 * checking core_state and changing tsk->mm.
831 */
832 down_read(&old_mm->mmap_sem);
833 if (unlikely(old_mm->core_state)) {
834 up_read(&old_mm->mmap_sem);
835 return -EINTR;
836 }
837 }
838 task_lock(tsk);
839 active_mm = tsk->active_mm;
840 tsk->mm = mm;
841 tsk->active_mm = mm;
842 activate_mm(active_mm, mm);
843 task_unlock(tsk);
844 arch_pick_mmap_layout(mm);
845 if (old_mm) {
846 up_read(&old_mm->mmap_sem);
847 BUG_ON(active_mm != old_mm);
848 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
849 mm_update_next_owner(old_mm);
850 mmput(old_mm);
851 return 0;
852 }
853 mmdrop(active_mm);
854 return 0;
855}
856
857/*
858 * This function makes sure the current process has its own signal table,
859 * so that flush_signal_handlers can later reset the handlers without
860 * disturbing other processes. (Other processes might share the signal
861 * table via the CLONE_SIGHAND option to clone().)
862 */
863static int de_thread(struct task_struct *tsk)
864{
865 struct signal_struct *sig = tsk->signal;
866 struct sighand_struct *oldsighand = tsk->sighand;
867 spinlock_t *lock = &oldsighand->siglock;
868
869 if (thread_group_empty(tsk))
870 goto no_thread_group;
871
872 /*
873 * Kill all other threads in the thread group.
874 */
875 spin_lock_irq(lock);
876 if (signal_group_exit(sig)) {
877 /*
878 * Another group action in progress, just
879 * return so that the signal is processed.
880 */
881 spin_unlock_irq(lock);
882 return -EAGAIN;
883 }
884
885 sig->group_exit_task = tsk;
886 sig->notify_count = zap_other_threads(tsk);
887 if (!thread_group_leader(tsk))
888 sig->notify_count--;
889
890 while (sig->notify_count) {
891 __set_current_state(TASK_UNINTERRUPTIBLE);
892 spin_unlock_irq(lock);
893 schedule();
894 spin_lock_irq(lock);
895 }
896 spin_unlock_irq(lock);
897
898 /*
899 * At this point all other threads have exited, all we have to
900 * do is to wait for the thread group leader to become inactive,
901 * and to assume its PID:
902 */
903 if (!thread_group_leader(tsk)) {
904 struct task_struct *leader = tsk->group_leader;
905
906 sig->notify_count = -1; /* for exit_notify() */
907 for (;;) {
908 write_lock_irq(&tasklist_lock);
909 if (likely(leader->exit_state))
910 break;
911 __set_current_state(TASK_UNINTERRUPTIBLE);
912 write_unlock_irq(&tasklist_lock);
913 schedule();
914 }
915
916 /*
917 * The only record we have of the real-time age of a
918 * process, regardless of execs it's done, is start_time.
919 * All the past CPU time is accumulated in signal_struct
920 * from sister threads now dead. But in this non-leader
921 * exec, nothing survives from the original leader thread,
922 * whose birth marks the true age of this process now.
923 * When we take on its identity by switching to its PID, we
924 * also take its birthdate (always earlier than our own).
925 */
926 tsk->start_time = leader->start_time;
927
928 BUG_ON(!same_thread_group(leader, tsk));
929 BUG_ON(has_group_leader_pid(tsk));
930 /*
931 * An exec() starts a new thread group with the
932 * TGID of the previous thread group. Rehash the
933 * two threads with a switched PID, and release
934 * the former thread group leader:
935 */
936
937 /* Become a process group leader with the old leader's pid.
938 * The old leader becomes a thread of the this thread group.
939 * Note: The old leader also uses this pid until release_task
940 * is called. Odd but simple and correct.
941 */
942 detach_pid(tsk, PIDTYPE_PID);
943 tsk->pid = leader->pid;
944 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
945 transfer_pid(leader, tsk, PIDTYPE_PGID);
946 transfer_pid(leader, tsk, PIDTYPE_SID);
947
948 list_replace_rcu(&leader->tasks, &tsk->tasks);
949 list_replace_init(&leader->sibling, &tsk->sibling);
950
951 tsk->group_leader = tsk;
952 leader->group_leader = tsk;
953
954 tsk->exit_signal = SIGCHLD;
955 leader->exit_signal = -1;
956
957 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
958 leader->exit_state = EXIT_DEAD;
959
960 /*
961 * We are going to release_task()->ptrace_unlink() silently,
962 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
963 * the tracer wont't block again waiting for this thread.
964 */
965 if (unlikely(leader->ptrace))
966 __wake_up_parent(leader, leader->parent);
967 write_unlock_irq(&tasklist_lock);
968
969 release_task(leader);
970 }
971
972 sig->group_exit_task = NULL;
973 sig->notify_count = 0;
974
975no_thread_group:
976 /* we have changed execution domain */
977 tsk->exit_signal = SIGCHLD;
978
979 exit_itimers(sig);
980 flush_itimer_signals();
981
982 if (atomic_read(&oldsighand->count) != 1) {
983 struct sighand_struct *newsighand;
984 /*
985 * This ->sighand is shared with the CLONE_SIGHAND
986 * but not CLONE_THREAD task, switch to the new one.
987 */
988 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
989 if (!newsighand)
990 return -ENOMEM;
991
992 atomic_set(&newsighand->count, 1);
993 memcpy(newsighand->action, oldsighand->action,
994 sizeof(newsighand->action));
995
996 write_lock_irq(&tasklist_lock);
997 spin_lock(&oldsighand->siglock);
998 rcu_assign_pointer(tsk->sighand, newsighand);
999 spin_unlock(&oldsighand->siglock);
1000 write_unlock_irq(&tasklist_lock);
1001
1002 __cleanup_sighand(oldsighand);
1003 }
1004
1005 BUG_ON(!thread_group_leader(tsk));
1006 return 0;
1007}
1008
1009/*
1010 * These functions flushes out all traces of the currently running executable
1011 * so that a new one can be started
1012 */
1013static void flush_old_files(struct files_struct * files)
1014{
1015 long j = -1;
1016 struct fdtable *fdt;
1017
1018 spin_lock(&files->file_lock);
1019 for (;;) {
1020 unsigned long set, i;
1021
1022 j++;
1023 i = j * __NFDBITS;
1024 fdt = files_fdtable(files);
1025 if (i >= fdt->max_fds)
1026 break;
1027 set = fdt->close_on_exec[j];
1028 if (!set)
1029 continue;
1030 fdt->close_on_exec[j] = 0;
1031 spin_unlock(&files->file_lock);
1032 for ( ; set ; i++,set >>= 1) {
1033 if (set & 1) {
1034 sys_close(i);
1035 }
1036 }
1037 spin_lock(&files->file_lock);
1038
1039 }
1040 spin_unlock(&files->file_lock);
1041}
1042
1043char *get_task_comm(char *buf, struct task_struct *tsk)
1044{
1045 /* buf must be at least sizeof(tsk->comm) in size */
1046 task_lock(tsk);
1047 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1048 task_unlock(tsk);
1049 return buf;
1050}
1051EXPORT_SYMBOL_GPL(get_task_comm);
1052
1053void set_task_comm(struct task_struct *tsk, char *buf)
1054{
1055 task_lock(tsk);
1056
1057 trace_task_rename(tsk, buf);
1058
1059 /*
1060 * Threads may access current->comm without holding
1061 * the task lock, so write the string carefully.
1062 * Readers without a lock may see incomplete new
1063 * names but are safe from non-terminating string reads.
1064 */
1065 memset(tsk->comm, 0, TASK_COMM_LEN);
1066 wmb();
1067 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1068 task_unlock(tsk);
1069 perf_event_comm(tsk);
1070}
1071
1072static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len)
1073{
1074 int i, ch;
1075
1076 /* Copies the binary name from after last slash */
1077 for (i = 0; (ch = *(fn++)) != '\0';) {
1078 if (ch == '/')
1079 i = 0; /* overwrite what we wrote */
1080 else
1081 if (i < len - 1)
1082 tcomm[i++] = ch;
1083 }
1084 tcomm[i] = '\0';
1085}
1086
1087int flush_old_exec(struct linux_binprm * bprm)
1088{
1089 int retval;
1090
1091 /*
1092 * Make sure we have a private signal table and that
1093 * we are unassociated from the previous thread group.
1094 */
1095 retval = de_thread(current);
1096 if (retval)
1097 goto out;
1098
1099 set_mm_exe_file(bprm->mm, bprm->file);
1100
1101 filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm));
1102 /*
1103 * Release all of the old mmap stuff
1104 */
1105 acct_arg_size(bprm, 0);
1106 retval = exec_mmap(bprm->mm);
1107 if (retval)
1108 goto out;
1109
1110 bprm->mm = NULL; /* We're using it now */
1111
1112 set_fs(USER_DS);
1113 current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD);
1114 flush_thread();
1115 current->personality &= ~bprm->per_clear;
1116
1117 return 0;
1118
1119out:
1120 return retval;
1121}
1122EXPORT_SYMBOL(flush_old_exec);
1123
1124void would_dump(struct linux_binprm *bprm, struct file *file)
1125{
1126 if (inode_permission(file->f_path.dentry->d_inode, MAY_READ) < 0)
1127 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1128}
1129EXPORT_SYMBOL(would_dump);
1130
1131void setup_new_exec(struct linux_binprm * bprm)
1132{
1133 arch_pick_mmap_layout(current->mm);
1134
1135 /* This is the point of no return */
1136 current->sas_ss_sp = current->sas_ss_size = 0;
1137
1138 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1139 set_dumpable(current->mm, 1);
1140 else
1141 set_dumpable(current->mm, suid_dumpable);
1142
1143 set_task_comm(current, bprm->tcomm);
1144
1145 /* Set the new mm task size. We have to do that late because it may
1146 * depend on TIF_32BIT which is only updated in flush_thread() on
1147 * some architectures like powerpc
1148 */
1149 current->mm->task_size = TASK_SIZE;
1150
1151 /* install the new credentials */
1152 if (!uid_eq(bprm->cred->uid, current_euid()) ||
1153 !gid_eq(bprm->cred->gid, current_egid())) {
1154 current->pdeath_signal = 0;
1155 } else {
1156 would_dump(bprm, bprm->file);
1157 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1158 set_dumpable(current->mm, suid_dumpable);
1159 }
1160
1161 /*
1162 * Flush performance counters when crossing a
1163 * security domain:
1164 */
1165 if (!get_dumpable(current->mm))
1166 perf_event_exit_task(current);
1167
1168 /* An exec changes our domain. We are no longer part of the thread
1169 group */
1170
1171 current->self_exec_id++;
1172
1173 flush_signal_handlers(current, 0);
1174 flush_old_files(current->files);
1175}
1176EXPORT_SYMBOL(setup_new_exec);
1177
1178/*
1179 * Prepare credentials and lock ->cred_guard_mutex.
1180 * install_exec_creds() commits the new creds and drops the lock.
1181 * Or, if exec fails before, free_bprm() should release ->cred and
1182 * and unlock.
1183 */
1184int prepare_bprm_creds(struct linux_binprm *bprm)
1185{
1186 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1187 return -ERESTARTNOINTR;
1188
1189 bprm->cred = prepare_exec_creds();
1190 if (likely(bprm->cred))
1191 return 0;
1192
1193 mutex_unlock(&current->signal->cred_guard_mutex);
1194 return -ENOMEM;
1195}
1196
1197void free_bprm(struct linux_binprm *bprm)
1198{
1199 free_arg_pages(bprm);
1200 if (bprm->cred) {
1201 mutex_unlock(&current->signal->cred_guard_mutex);
1202 abort_creds(bprm->cred);
1203 }
1204 kfree(bprm);
1205}
1206
1207/*
1208 * install the new credentials for this executable
1209 */
1210void install_exec_creds(struct linux_binprm *bprm)
1211{
1212 security_bprm_committing_creds(bprm);
1213
1214 commit_creds(bprm->cred);
1215 bprm->cred = NULL;
1216 /*
1217 * cred_guard_mutex must be held at least to this point to prevent
1218 * ptrace_attach() from altering our determination of the task's
1219 * credentials; any time after this it may be unlocked.
1220 */
1221 security_bprm_committed_creds(bprm);
1222 mutex_unlock(&current->signal->cred_guard_mutex);
1223}
1224EXPORT_SYMBOL(install_exec_creds);
1225
1226/*
1227 * determine how safe it is to execute the proposed program
1228 * - the caller must hold ->cred_guard_mutex to protect against
1229 * PTRACE_ATTACH
1230 */
1231static int check_unsafe_exec(struct linux_binprm *bprm)
1232{
1233 struct task_struct *p = current, *t;
1234 unsigned n_fs;
1235 int res = 0;
1236
1237 if (p->ptrace) {
1238 if (p->ptrace & PT_PTRACE_CAP)
1239 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1240 else
1241 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1242 }
1243
1244 /*
1245 * This isn't strictly necessary, but it makes it harder for LSMs to
1246 * mess up.
1247 */
1248 if (current->no_new_privs)
1249 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1250
1251 n_fs = 1;
1252 spin_lock(&p->fs->lock);
1253 rcu_read_lock();
1254 for (t = next_thread(p); t != p; t = next_thread(t)) {
1255 if (t->fs == p->fs)
1256 n_fs++;
1257 }
1258 rcu_read_unlock();
1259
1260 if (p->fs->users > n_fs) {
1261 bprm->unsafe |= LSM_UNSAFE_SHARE;
1262 } else {
1263 res = -EAGAIN;
1264 if (!p->fs->in_exec) {
1265 p->fs->in_exec = 1;
1266 res = 1;
1267 }
1268 }
1269 spin_unlock(&p->fs->lock);
1270
1271 return res;
1272}
1273
1274/*
1275 * Fill the binprm structure from the inode.
1276 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1277 *
1278 * This may be called multiple times for binary chains (scripts for example).
1279 */
1280int prepare_binprm(struct linux_binprm *bprm)
1281{
1282 umode_t mode;
1283 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1284 int retval;
1285
1286 mode = inode->i_mode;
1287 if (bprm->file->f_op == NULL)
1288 return -EACCES;
1289
1290 /* clear any previous set[ug]id data from a previous binary */
1291 bprm->cred->euid = current_euid();
1292 bprm->cred->egid = current_egid();
1293
1294 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1295 !current->no_new_privs) {
1296 /* Set-uid? */
1297 if (mode & S_ISUID) {
1298 if (!kuid_has_mapping(bprm->cred->user_ns, inode->i_uid))
1299 return -EPERM;
1300 bprm->per_clear |= PER_CLEAR_ON_SETID;
1301 bprm->cred->euid = inode->i_uid;
1302
1303 }
1304
1305 /* Set-gid? */
1306 /*
1307 * If setgid is set but no group execute bit then this
1308 * is a candidate for mandatory locking, not a setgid
1309 * executable.
1310 */
1311 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1312 if (!kgid_has_mapping(bprm->cred->user_ns, inode->i_gid))
1313 return -EPERM;
1314 bprm->per_clear |= PER_CLEAR_ON_SETID;
1315 bprm->cred->egid = inode->i_gid;
1316 }
1317 }
1318
1319 /* fill in binprm security blob */
1320 retval = security_bprm_set_creds(bprm);
1321 if (retval)
1322 return retval;
1323 bprm->cred_prepared = 1;
1324
1325 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1326 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1327}
1328
1329EXPORT_SYMBOL(prepare_binprm);
1330
1331/*
1332 * Arguments are '\0' separated strings found at the location bprm->p
1333 * points to; chop off the first by relocating brpm->p to right after
1334 * the first '\0' encountered.
1335 */
1336int remove_arg_zero(struct linux_binprm *bprm)
1337{
1338 int ret = 0;
1339 unsigned long offset;
1340 char *kaddr;
1341 struct page *page;
1342
1343 if (!bprm->argc)
1344 return 0;
1345
1346 do {
1347 offset = bprm->p & ~PAGE_MASK;
1348 page = get_arg_page(bprm, bprm->p, 0);
1349 if (!page) {
1350 ret = -EFAULT;
1351 goto out;
1352 }
1353 kaddr = kmap_atomic(page);
1354
1355 for (; offset < PAGE_SIZE && kaddr[offset];
1356 offset++, bprm->p++)
1357 ;
1358
1359 kunmap_atomic(kaddr);
1360 put_arg_page(page);
1361
1362 if (offset == PAGE_SIZE)
1363 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1364 } while (offset == PAGE_SIZE);
1365
1366 bprm->p++;
1367 bprm->argc--;
1368 ret = 0;
1369
1370out:
1371 return ret;
1372}
1373EXPORT_SYMBOL(remove_arg_zero);
1374
1375/*
1376 * cycle the list of binary formats handler, until one recognizes the image
1377 */
1378int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1379{
1380 unsigned int depth = bprm->recursion_depth;
1381 int try,retval;
1382 struct linux_binfmt *fmt;
1383 pid_t old_pid, old_vpid;
1384
1385 retval = security_bprm_check(bprm);
1386 if (retval)
1387 return retval;
1388
1389 retval = audit_bprm(bprm);
1390 if (retval)
1391 return retval;
1392
1393 /* Need to fetch pid before load_binary changes it */
1394 old_pid = current->pid;
1395 rcu_read_lock();
1396 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1397 rcu_read_unlock();
1398
1399 retval = -ENOENT;
1400 for (try=0; try<2; try++) {
1401 read_lock(&binfmt_lock);
1402 list_for_each_entry(fmt, &formats, lh) {
1403 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1404 if (!fn)
1405 continue;
1406 if (!try_module_get(fmt->module))
1407 continue;
1408 read_unlock(&binfmt_lock);
1409 retval = fn(bprm, regs);
1410 /*
1411 * Restore the depth counter to its starting value
1412 * in this call, so we don't have to rely on every
1413 * load_binary function to restore it on return.
1414 */
1415 bprm->recursion_depth = depth;
1416 if (retval >= 0) {
1417 if (depth == 0) {
1418 trace_sched_process_exec(current, old_pid, bprm);
1419 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1420 }
1421 put_binfmt(fmt);
1422 allow_write_access(bprm->file);
1423 if (bprm->file)
1424 fput(bprm->file);
1425 bprm->file = NULL;
1426 current->did_exec = 1;
1427 proc_exec_connector(current);
1428 return retval;
1429 }
1430 read_lock(&binfmt_lock);
1431 put_binfmt(fmt);
1432 if (retval != -ENOEXEC || bprm->mm == NULL)
1433 break;
1434 if (!bprm->file) {
1435 read_unlock(&binfmt_lock);
1436 return retval;
1437 }
1438 }
1439 read_unlock(&binfmt_lock);
1440#ifdef CONFIG_MODULES
1441 if (retval != -ENOEXEC || bprm->mm == NULL) {
1442 break;
1443 } else {
1444#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1445 if (printable(bprm->buf[0]) &&
1446 printable(bprm->buf[1]) &&
1447 printable(bprm->buf[2]) &&
1448 printable(bprm->buf[3]))
1449 break; /* -ENOEXEC */
1450 if (try)
1451 break; /* -ENOEXEC */
1452 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1453 }
1454#else
1455 break;
1456#endif
1457 }
1458 return retval;
1459}
1460
1461EXPORT_SYMBOL(search_binary_handler);
1462
1463/*
1464 * sys_execve() executes a new program.
1465 */
1466static int do_execve_common(const char *filename,
1467 struct user_arg_ptr argv,
1468 struct user_arg_ptr envp,
1469 struct pt_regs *regs)
1470{
1471 struct linux_binprm *bprm;
1472 struct file *file;
1473 struct files_struct *displaced;
1474 bool clear_in_exec;
1475 int retval;
1476 const struct cred *cred = current_cred();
1477
1478 /*
1479 * We move the actual failure in case of RLIMIT_NPROC excess from
1480 * set*uid() to execve() because too many poorly written programs
1481 * don't check setuid() return code. Here we additionally recheck
1482 * whether NPROC limit is still exceeded.
1483 */
1484 if ((current->flags & PF_NPROC_EXCEEDED) &&
1485 atomic_read(&cred->user->processes) > rlimit(RLIMIT_NPROC)) {
1486 retval = -EAGAIN;
1487 goto out_ret;
1488 }
1489
1490 /* We're below the limit (still or again), so we don't want to make
1491 * further execve() calls fail. */
1492 current->flags &= ~PF_NPROC_EXCEEDED;
1493
1494 retval = unshare_files(&displaced);
1495 if (retval)
1496 goto out_ret;
1497
1498 retval = -ENOMEM;
1499 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1500 if (!bprm)
1501 goto out_files;
1502
1503 retval = prepare_bprm_creds(bprm);
1504 if (retval)
1505 goto out_free;
1506
1507 retval = check_unsafe_exec(bprm);
1508 if (retval < 0)
1509 goto out_free;
1510 clear_in_exec = retval;
1511 current->in_execve = 1;
1512
1513 file = open_exec(filename);
1514 retval = PTR_ERR(file);
1515 if (IS_ERR(file))
1516 goto out_unmark;
1517
1518 sched_exec();
1519
1520 bprm->file = file;
1521 bprm->filename = filename;
1522 bprm->interp = filename;
1523
1524 retval = bprm_mm_init(bprm);
1525 if (retval)
1526 goto out_file;
1527
1528 bprm->argc = count(argv, MAX_ARG_STRINGS);
1529 if ((retval = bprm->argc) < 0)
1530 goto out;
1531
1532 bprm->envc = count(envp, MAX_ARG_STRINGS);
1533 if ((retval = bprm->envc) < 0)
1534 goto out;
1535
1536 retval = prepare_binprm(bprm);
1537 if (retval < 0)
1538 goto out;
1539
1540 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1541 if (retval < 0)
1542 goto out;
1543
1544 bprm->exec = bprm->p;
1545 retval = copy_strings(bprm->envc, envp, bprm);
1546 if (retval < 0)
1547 goto out;
1548
1549 retval = copy_strings(bprm->argc, argv, bprm);
1550 if (retval < 0)
1551 goto out;
1552
1553 retval = search_binary_handler(bprm,regs);
1554 if (retval < 0)
1555 goto out;
1556
1557 /* execve succeeded */
1558 current->fs->in_exec = 0;
1559 current->in_execve = 0;
1560 acct_update_integrals(current);
1561 free_bprm(bprm);
1562 if (displaced)
1563 put_files_struct(displaced);
1564 return retval;
1565
1566out:
1567 if (bprm->mm) {
1568 acct_arg_size(bprm, 0);
1569 mmput(bprm->mm);
1570 }
1571
1572out_file:
1573 if (bprm->file) {
1574 allow_write_access(bprm->file);
1575 fput(bprm->file);
1576 }
1577
1578out_unmark:
1579 if (clear_in_exec)
1580 current->fs->in_exec = 0;
1581 current->in_execve = 0;
1582
1583out_free:
1584 free_bprm(bprm);
1585
1586out_files:
1587 if (displaced)
1588 reset_files_struct(displaced);
1589out_ret:
1590 return retval;
1591}
1592
1593int do_execve(const char *filename,
1594 const char __user *const __user *__argv,
1595 const char __user *const __user *__envp,
1596 struct pt_regs *regs)
1597{
1598 struct user_arg_ptr argv = { .ptr.native = __argv };
1599 struct user_arg_ptr envp = { .ptr.native = __envp };
1600 return do_execve_common(filename, argv, envp, regs);
1601}
1602
1603#ifdef CONFIG_COMPAT
1604int compat_do_execve(char *filename,
1605 compat_uptr_t __user *__argv,
1606 compat_uptr_t __user *__envp,
1607 struct pt_regs *regs)
1608{
1609 struct user_arg_ptr argv = {
1610 .is_compat = true,
1611 .ptr.compat = __argv,
1612 };
1613 struct user_arg_ptr envp = {
1614 .is_compat = true,
1615 .ptr.compat = __envp,
1616 };
1617 return do_execve_common(filename, argv, envp, regs);
1618}
1619#endif
1620
1621void set_binfmt(struct linux_binfmt *new)
1622{
1623 struct mm_struct *mm = current->mm;
1624
1625 if (mm->binfmt)
1626 module_put(mm->binfmt->module);
1627
1628 mm->binfmt = new;
1629 if (new)
1630 __module_get(new->module);
1631}
1632
1633EXPORT_SYMBOL(set_binfmt);
1634
1635static int expand_corename(struct core_name *cn)
1636{
1637 char *old_corename = cn->corename;
1638
1639 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1640 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1641
1642 if (!cn->corename) {
1643 kfree(old_corename);
1644 return -ENOMEM;
1645 }
1646
1647 return 0;
1648}
1649
1650static int cn_printf(struct core_name *cn, const char *fmt, ...)
1651{
1652 char *cur;
1653 int need;
1654 int ret;
1655 va_list arg;
1656
1657 va_start(arg, fmt);
1658 need = vsnprintf(NULL, 0, fmt, arg);
1659 va_end(arg);
1660
1661 if (likely(need < cn->size - cn->used - 1))
1662 goto out_printf;
1663
1664 ret = expand_corename(cn);
1665 if (ret)
1666 goto expand_fail;
1667
1668out_printf:
1669 cur = cn->corename + cn->used;
1670 va_start(arg, fmt);
1671 vsnprintf(cur, need + 1, fmt, arg);
1672 va_end(arg);
1673 cn->used += need;
1674 return 0;
1675
1676expand_fail:
1677 return ret;
1678}
1679
1680static void cn_escape(char *str)
1681{
1682 for (; *str; str++)
1683 if (*str == '/')
1684 *str = '!';
1685}
1686
1687static int cn_print_exe_file(struct core_name *cn)
1688{
1689 struct file *exe_file;
1690 char *pathbuf, *path;
1691 int ret;
1692
1693 exe_file = get_mm_exe_file(current->mm);
1694 if (!exe_file) {
1695 char *commstart = cn->corename + cn->used;
1696 ret = cn_printf(cn, "%s (path unknown)", current->comm);
1697 cn_escape(commstart);
1698 return ret;
1699 }
1700
1701 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1702 if (!pathbuf) {
1703 ret = -ENOMEM;
1704 goto put_exe_file;
1705 }
1706
1707 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1708 if (IS_ERR(path)) {
1709 ret = PTR_ERR(path);
1710 goto free_buf;
1711 }
1712
1713 cn_escape(path);
1714
1715 ret = cn_printf(cn, "%s", path);
1716
1717free_buf:
1718 kfree(pathbuf);
1719put_exe_file:
1720 fput(exe_file);
1721 return ret;
1722}
1723
1724/* format_corename will inspect the pattern parameter, and output a
1725 * name into corename, which must have space for at least
1726 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1727 */
1728static int format_corename(struct core_name *cn, long signr)
1729{
1730 const struct cred *cred = current_cred();
1731 const char *pat_ptr = core_pattern;
1732 int ispipe = (*pat_ptr == '|');
1733 int pid_in_pattern = 0;
1734 int err = 0;
1735
1736 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1737 cn->corename = kmalloc(cn->size, GFP_KERNEL);
1738 cn->used = 0;
1739
1740 if (!cn->corename)
1741 return -ENOMEM;
1742
1743 /* Repeat as long as we have more pattern to process and more output
1744 space */
1745 while (*pat_ptr) {
1746 if (*pat_ptr != '%') {
1747 if (*pat_ptr == 0)
1748 goto out;
1749 err = cn_printf(cn, "%c", *pat_ptr++);
1750 } else {
1751 switch (*++pat_ptr) {
1752 /* single % at the end, drop that */
1753 case 0:
1754 goto out;
1755 /* Double percent, output one percent */
1756 case '%':
1757 err = cn_printf(cn, "%c", '%');
1758 break;
1759 /* pid */
1760 case 'p':
1761 pid_in_pattern = 1;
1762 err = cn_printf(cn, "%d",
1763 task_tgid_vnr(current));
1764 break;
1765 /* uid */
1766 case 'u':
1767 err = cn_printf(cn, "%d", cred->uid);
1768 break;
1769 /* gid */
1770 case 'g':
1771 err = cn_printf(cn, "%d", cred->gid);
1772 break;
1773 /* signal that caused the coredump */
1774 case 's':
1775 err = cn_printf(cn, "%ld", signr);
1776 break;
1777 /* UNIX time of coredump */
1778 case 't': {
1779 struct timeval tv;
1780 do_gettimeofday(&tv);
1781 err = cn_printf(cn, "%lu", tv.tv_sec);
1782 break;
1783 }
1784 /* hostname */
1785 case 'h': {
1786 char *namestart = cn->corename + cn->used;
1787 down_read(&uts_sem);
1788 err = cn_printf(cn, "%s",
1789 utsname()->nodename);
1790 up_read(&uts_sem);
1791 cn_escape(namestart);
1792 break;
1793 }
1794 /* executable */
1795 case 'e': {
1796 char *commstart = cn->corename + cn->used;
1797 err = cn_printf(cn, "%s", current->comm);
1798 cn_escape(commstart);
1799 break;
1800 }
1801 case 'E':
1802 err = cn_print_exe_file(cn);
1803 break;
1804 /* core limit size */
1805 case 'c':
1806 err = cn_printf(cn, "%lu",
1807 rlimit(RLIMIT_CORE));
1808 break;
1809 default:
1810 break;
1811 }
1812 ++pat_ptr;
1813 }
1814
1815 if (err)
1816 return err;
1817 }
1818
1819 /* Backward compatibility with core_uses_pid:
1820 *
1821 * If core_pattern does not include a %p (as is the default)
1822 * and core_uses_pid is set, then .%pid will be appended to
1823 * the filename. Do not do this for piped commands. */
1824 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1825 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1826 if (err)
1827 return err;
1828 }
1829out:
1830 return ispipe;
1831}
1832
1833static int zap_process(struct task_struct *start, int exit_code)
1834{
1835 struct task_struct *t;
1836 int nr = 0;
1837
1838 start->signal->flags = SIGNAL_GROUP_EXIT;
1839 start->signal->group_exit_code = exit_code;
1840 start->signal->group_stop_count = 0;
1841
1842 t = start;
1843 do {
1844 task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
1845 if (t != current && t->mm) {
1846 sigaddset(&t->pending.signal, SIGKILL);
1847 signal_wake_up(t, 1);
1848 nr++;
1849 }
1850 } while_each_thread(start, t);
1851
1852 return nr;
1853}
1854
1855static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1856 struct core_state *core_state, int exit_code)
1857{
1858 struct task_struct *g, *p;
1859 unsigned long flags;
1860 int nr = -EAGAIN;
1861
1862 spin_lock_irq(&tsk->sighand->siglock);
1863 if (!signal_group_exit(tsk->signal)) {
1864 mm->core_state = core_state;
1865 nr = zap_process(tsk, exit_code);
1866 }
1867 spin_unlock_irq(&tsk->sighand->siglock);
1868 if (unlikely(nr < 0))
1869 return nr;
1870
1871 if (atomic_read(&mm->mm_users) == nr + 1)
1872 goto done;
1873 /*
1874 * We should find and kill all tasks which use this mm, and we should
1875 * count them correctly into ->nr_threads. We don't take tasklist
1876 * lock, but this is safe wrt:
1877 *
1878 * fork:
1879 * None of sub-threads can fork after zap_process(leader). All
1880 * processes which were created before this point should be
1881 * visible to zap_threads() because copy_process() adds the new
1882 * process to the tail of init_task.tasks list, and lock/unlock
1883 * of ->siglock provides a memory barrier.
1884 *
1885 * do_exit:
1886 * The caller holds mm->mmap_sem. This means that the task which
1887 * uses this mm can't pass exit_mm(), so it can't exit or clear
1888 * its ->mm.
1889 *
1890 * de_thread:
1891 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1892 * we must see either old or new leader, this does not matter.
1893 * However, it can change p->sighand, so lock_task_sighand(p)
1894 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1895 * it can't fail.
1896 *
1897 * Note also that "g" can be the old leader with ->mm == NULL
1898 * and already unhashed and thus removed from ->thread_group.
1899 * This is OK, __unhash_process()->list_del_rcu() does not
1900 * clear the ->next pointer, we will find the new leader via
1901 * next_thread().
1902 */
1903 rcu_read_lock();
1904 for_each_process(g) {
1905 if (g == tsk->group_leader)
1906 continue;
1907 if (g->flags & PF_KTHREAD)
1908 continue;
1909 p = g;
1910 do {
1911 if (p->mm) {
1912 if (unlikely(p->mm == mm)) {
1913 lock_task_sighand(p, &flags);
1914 nr += zap_process(p, exit_code);
1915 unlock_task_sighand(p, &flags);
1916 }
1917 break;
1918 }
1919 } while_each_thread(g, p);
1920 }
1921 rcu_read_unlock();
1922done:
1923 atomic_set(&core_state->nr_threads, nr);
1924 return nr;
1925}
1926
1927static int coredump_wait(int exit_code, struct core_state *core_state)
1928{
1929 struct task_struct *tsk = current;
1930 struct mm_struct *mm = tsk->mm;
1931 int core_waiters = -EBUSY;
1932
1933 init_completion(&core_state->startup);
1934 core_state->dumper.task = tsk;
1935 core_state->dumper.next = NULL;
1936
1937 down_write(&mm->mmap_sem);
1938 if (!mm->core_state)
1939 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1940 up_write(&mm->mmap_sem);
1941
1942 if (core_waiters > 0) {
1943 struct core_thread *ptr;
1944
1945 wait_for_completion(&core_state->startup);
1946 /*
1947 * Wait for all the threads to become inactive, so that
1948 * all the thread context (extended register state, like
1949 * fpu etc) gets copied to the memory.
1950 */
1951 ptr = core_state->dumper.next;
1952 while (ptr != NULL) {
1953 wait_task_inactive(ptr->task, 0);
1954 ptr = ptr->next;
1955 }
1956 }
1957
1958 return core_waiters;
1959}
1960
1961static void coredump_finish(struct mm_struct *mm)
1962{
1963 struct core_thread *curr, *next;
1964 struct task_struct *task;
1965
1966 next = mm->core_state->dumper.next;
1967 while ((curr = next) != NULL) {
1968 next = curr->next;
1969 task = curr->task;
1970 /*
1971 * see exit_mm(), curr->task must not see
1972 * ->task == NULL before we read ->next.
1973 */
1974 smp_mb();
1975 curr->task = NULL;
1976 wake_up_process(task);
1977 }
1978
1979 mm->core_state = NULL;
1980}
1981
1982/*
1983 * set_dumpable converts traditional three-value dumpable to two flags and
1984 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1985 * these bits are not changed atomically. So get_dumpable can observe the
1986 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1987 * return either old dumpable or new one by paying attention to the order of
1988 * modifying the bits.
1989 *
1990 * dumpable | mm->flags (binary)
1991 * old new | initial interim final
1992 * ---------+-----------------------
1993 * 0 1 | 00 01 01
1994 * 0 2 | 00 10(*) 11
1995 * 1 0 | 01 00 00
1996 * 1 2 | 01 11 11
1997 * 2 0 | 11 10(*) 00
1998 * 2 1 | 11 11 01
1999 *
2000 * (*) get_dumpable regards interim value of 10 as 11.
2001 */
2002void set_dumpable(struct mm_struct *mm, int value)
2003{
2004 switch (value) {
2005 case 0:
2006 clear_bit(MMF_DUMPABLE, &mm->flags);
2007 smp_wmb();
2008 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2009 break;
2010 case 1:
2011 set_bit(MMF_DUMPABLE, &mm->flags);
2012 smp_wmb();
2013 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
2014 break;
2015 case 2:
2016 set_bit(MMF_DUMP_SECURELY, &mm->flags);
2017 smp_wmb();
2018 set_bit(MMF_DUMPABLE, &mm->flags);
2019 break;
2020 }
2021}
2022
2023static int __get_dumpable(unsigned long mm_flags)
2024{
2025 int ret;
2026
2027 ret = mm_flags & MMF_DUMPABLE_MASK;
2028 return (ret >= 2) ? 2 : ret;
2029}
2030
2031int get_dumpable(struct mm_struct *mm)
2032{
2033 return __get_dumpable(mm->flags);
2034}
2035
2036static void wait_for_dump_helpers(struct file *file)
2037{
2038 struct pipe_inode_info *pipe;
2039
2040 pipe = file->f_path.dentry->d_inode->i_pipe;
2041
2042 pipe_lock(pipe);
2043 pipe->readers++;
2044 pipe->writers--;
2045
2046 while ((pipe->readers > 1) && (!signal_pending(current))) {
2047 wake_up_interruptible_sync(&pipe->wait);
2048 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
2049 pipe_wait(pipe);
2050 }
2051
2052 pipe->readers--;
2053 pipe->writers++;
2054 pipe_unlock(pipe);
2055
2056}
2057
2058
2059/*
2060 * umh_pipe_setup
2061 * helper function to customize the process used
2062 * to collect the core in userspace. Specifically
2063 * it sets up a pipe and installs it as fd 0 (stdin)
2064 * for the process. Returns 0 on success, or
2065 * PTR_ERR on failure.
2066 * Note that it also sets the core limit to 1. This
2067 * is a special value that we use to trap recursive
2068 * core dumps
2069 */
2070static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2071{
2072 struct file *rp, *wp;
2073 struct fdtable *fdt;
2074 struct coredump_params *cp = (struct coredump_params *)info->data;
2075 struct files_struct *cf = current->files;
2076
2077 wp = create_write_pipe(0);
2078 if (IS_ERR(wp))
2079 return PTR_ERR(wp);
2080
2081 rp = create_read_pipe(wp, 0);
2082 if (IS_ERR(rp)) {
2083 free_write_pipe(wp);
2084 return PTR_ERR(rp);
2085 }
2086
2087 cp->file = wp;
2088
2089 sys_close(0);
2090 fd_install(0, rp);
2091 spin_lock(&cf->file_lock);
2092 fdt = files_fdtable(cf);
2093 __set_open_fd(0, fdt);
2094 __clear_close_on_exec(0, fdt);
2095 spin_unlock(&cf->file_lock);
2096
2097 /* and disallow core files too */
2098 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2099
2100 return 0;
2101}
2102
2103void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2104{
2105 struct core_state core_state;
2106 struct core_name cn;
2107 struct mm_struct *mm = current->mm;
2108 struct linux_binfmt * binfmt;
2109 const struct cred *old_cred;
2110 struct cred *cred;
2111 int retval = 0;
2112 int flag = 0;
2113 int ispipe;
2114 static atomic_t core_dump_count = ATOMIC_INIT(0);
2115 struct coredump_params cprm = {
2116 .signr = signr,
2117 .regs = regs,
2118 .limit = rlimit(RLIMIT_CORE),
2119 /*
2120 * We must use the same mm->flags while dumping core to avoid
2121 * inconsistency of bit flags, since this flag is not protected
2122 * by any locks.
2123 */
2124 .mm_flags = mm->flags,
2125 };
2126
2127 audit_core_dumps(signr);
2128
2129 binfmt = mm->binfmt;
2130 if (!binfmt || !binfmt->core_dump)
2131 goto fail;
2132 if (!__get_dumpable(cprm.mm_flags))
2133 goto fail;
2134
2135 cred = prepare_creds();
2136 if (!cred)
2137 goto fail;
2138 /*
2139 * We cannot trust fsuid as being the "true" uid of the
2140 * process nor do we know its entire history. We only know it
2141 * was tainted so we dump it as root in mode 2.
2142 */
2143 if (__get_dumpable(cprm.mm_flags) == 2) {
2144 /* Setuid core dump mode */
2145 flag = O_EXCL; /* Stop rewrite attacks */
2146 cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
2147 }
2148
2149 retval = coredump_wait(exit_code, &core_state);
2150 if (retval < 0)
2151 goto fail_creds;
2152
2153 old_cred = override_creds(cred);
2154
2155 /*
2156 * Clear any false indication of pending signals that might
2157 * be seen by the filesystem code called to write the core file.
2158 */
2159 clear_thread_flag(TIF_SIGPENDING);
2160
2161 ispipe = format_corename(&cn, signr);
2162
2163 if (ispipe) {
2164 int dump_count;
2165 char **helper_argv;
2166
2167 if (ispipe < 0) {
2168 printk(KERN_WARNING "format_corename failed\n");
2169 printk(KERN_WARNING "Aborting core\n");
2170 goto fail_corename;
2171 }
2172
2173 if (cprm.limit == 1) {
2174 /*
2175 * Normally core limits are irrelevant to pipes, since
2176 * we're not writing to the file system, but we use
2177 * cprm.limit of 1 here as a speacial value. Any
2178 * non-1 limit gets set to RLIM_INFINITY below, but
2179 * a limit of 0 skips the dump. This is a consistent
2180 * way to catch recursive crashes. We can still crash
2181 * if the core_pattern binary sets RLIM_CORE = !1
2182 * but it runs as root, and can do lots of stupid things
2183 * Note that we use task_tgid_vnr here to grab the pid
2184 * of the process group leader. That way we get the
2185 * right pid if a thread in a multi-threaded
2186 * core_pattern process dies.
2187 */
2188 printk(KERN_WARNING
2189 "Process %d(%s) has RLIMIT_CORE set to 1\n",
2190 task_tgid_vnr(current), current->comm);
2191 printk(KERN_WARNING "Aborting core\n");
2192 goto fail_unlock;
2193 }
2194 cprm.limit = RLIM_INFINITY;
2195
2196 dump_count = atomic_inc_return(&core_dump_count);
2197 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2198 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2199 task_tgid_vnr(current), current->comm);
2200 printk(KERN_WARNING "Skipping core dump\n");
2201 goto fail_dropcount;
2202 }
2203
2204 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2205 if (!helper_argv) {
2206 printk(KERN_WARNING "%s failed to allocate memory\n",
2207 __func__);
2208 goto fail_dropcount;
2209 }
2210
2211 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2212 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2213 NULL, &cprm);
2214 argv_free(helper_argv);
2215 if (retval) {
2216 printk(KERN_INFO "Core dump to %s pipe failed\n",
2217 cn.corename);
2218 goto close_fail;
2219 }
2220 } else {
2221 struct inode *inode;
2222
2223 if (cprm.limit < binfmt->min_coredump)
2224 goto fail_unlock;
2225
2226 cprm.file = filp_open(cn.corename,
2227 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2228 0600);
2229 if (IS_ERR(cprm.file))
2230 goto fail_unlock;
2231
2232 inode = cprm.file->f_path.dentry->d_inode;
2233 if (inode->i_nlink > 1)
2234 goto close_fail;
2235 if (d_unhashed(cprm.file->f_path.dentry))
2236 goto close_fail;
2237 /*
2238 * AK: actually i see no reason to not allow this for named
2239 * pipes etc, but keep the previous behaviour for now.
2240 */
2241 if (!S_ISREG(inode->i_mode))
2242 goto close_fail;
2243 /*
2244 * Dont allow local users get cute and trick others to coredump
2245 * into their pre-created files.
2246 */
2247 if (!uid_eq(inode->i_uid, current_fsuid()))
2248 goto close_fail;
2249 if (!cprm.file->f_op || !cprm.file->f_op->write)
2250 goto close_fail;
2251 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2252 goto close_fail;
2253 }
2254
2255 retval = binfmt->core_dump(&cprm);
2256 if (retval)
2257 current->signal->group_exit_code |= 0x80;
2258
2259 if (ispipe && core_pipe_limit)
2260 wait_for_dump_helpers(cprm.file);
2261close_fail:
2262 if (cprm.file)
2263 filp_close(cprm.file, NULL);
2264fail_dropcount:
2265 if (ispipe)
2266 atomic_dec(&core_dump_count);
2267fail_unlock:
2268 kfree(cn.corename);
2269fail_corename:
2270 coredump_finish(mm);
2271 revert_creds(old_cred);
2272fail_creds:
2273 put_cred(cred);
2274fail:
2275 return;
2276}
2277
2278/*
2279 * Core dumping helper functions. These are the only things you should
2280 * do on a core-file: use only these functions to write out all the
2281 * necessary info.
2282 */
2283int dump_write(struct file *file, const void *addr, int nr)
2284{
2285 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2286}
2287EXPORT_SYMBOL(dump_write);
2288
2289int dump_seek(struct file *file, loff_t off)
2290{
2291 int ret = 1;
2292
2293 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2294 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2295 return 0;
2296 } else {
2297 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2298
2299 if (!buf)
2300 return 0;
2301 while (off > 0) {
2302 unsigned long n = off;
2303
2304 if (n > PAGE_SIZE)
2305 n = PAGE_SIZE;
2306 if (!dump_write(file, buf, n)) {
2307 ret = 0;
2308 break;
2309 }
2310 off -= n;
2311 }
2312 free_page((unsigned long)buf);
2313 }
2314 return ret;
2315}
2316EXPORT_SYMBOL(dump_seek);