projects/linux·blob v3.0 · refs

2245 lines · 51.1 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 "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/*
170 * The nascent bprm->mm is not visible until exec_mmap() but it can
171 * use a lot of memory, account these pages in current->mm temporary
172 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
173 * change the counter back via acct_arg_size(0).
174 */
175static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
176{
177 struct mm_struct *mm = current->mm;
178 long diff = (long)(pages - bprm->vma_pages);
179
180 if (!mm || !diff)
181 return;
182
183 bprm->vma_pages = pages;
184
185#ifdef SPLIT_RSS_COUNTING
186 add_mm_counter(mm, MM_ANONPAGES, diff);
187#else
188 spin_lock(&mm->page_table_lock);
189 add_mm_counter(mm, MM_ANONPAGES, diff);
190 spin_unlock(&mm->page_table_lock);
191#endif
192}
193
194static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
195 int write)
196{
197 struct page *page;
198 int ret;
199
200#ifdef CONFIG_STACK_GROWSUP
201 if (write) {
202 ret = expand_downwards(bprm->vma, pos);
203 if (ret < 0)
204 return NULL;
205 }
206#endif
207 ret = get_user_pages(current, bprm->mm, pos,
208 1, write, 1, &page, NULL);
209 if (ret <= 0)
210 return NULL;
211
212 if (write) {
213 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
214 struct rlimit *rlim;
215
216 acct_arg_size(bprm, size / PAGE_SIZE);
217
218 /*
219 * We've historically supported up to 32 pages (ARG_MAX)
220 * of argument strings even with small stacks
221 */
222 if (size <= ARG_MAX)
223 return page;
224
225 /*
226 * Limit to 1/4-th the stack size for the argv+env strings.
227 * This ensures that:
228 * - the remaining binfmt code will not run out of stack space,
229 * - the program will have a reasonable amount of stack left
230 * to work from.
231 */
232 rlim = current->signal->rlim;
233 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
234 put_page(page);
235 return NULL;
236 }
237 }
238
239 return page;
240}
241
242static void put_arg_page(struct page *page)
243{
244 put_page(page);
245}
246
247static void free_arg_page(struct linux_binprm *bprm, int i)
248{
249}
250
251static void free_arg_pages(struct linux_binprm *bprm)
252{
253}
254
255static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
256 struct page *page)
257{
258 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
259}
260
261static int __bprm_mm_init(struct linux_binprm *bprm)
262{
263 int err;
264 struct vm_area_struct *vma = NULL;
265 struct mm_struct *mm = bprm->mm;
266
267 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
268 if (!vma)
269 return -ENOMEM;
270
271 down_write(&mm->mmap_sem);
272 vma->vm_mm = mm;
273
274 /*
275 * Place the stack at the largest stack address the architecture
276 * supports. Later, we'll move this to an appropriate place. We don't
277 * use STACK_TOP because that can depend on attributes which aren't
278 * configured yet.
279 */
280 BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
281 vma->vm_end = STACK_TOP_MAX;
282 vma->vm_start = vma->vm_end - PAGE_SIZE;
283 vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
284 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
285 INIT_LIST_HEAD(&vma->anon_vma_chain);
286
287 err = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
288 if (err)
289 goto err;
290
291 err = insert_vm_struct(mm, vma);
292 if (err)
293 goto err;
294
295 mm->stack_vm = mm->total_vm = 1;
296 up_write(&mm->mmap_sem);
297 bprm->p = vma->vm_end - sizeof(void *);
298 return 0;
299err:
300 up_write(&mm->mmap_sem);
301 bprm->vma = NULL;
302 kmem_cache_free(vm_area_cachep, vma);
303 return err;
304}
305
306static bool valid_arg_len(struct linux_binprm *bprm, long len)
307{
308 return len <= MAX_ARG_STRLEN;
309}
310
311#else
312
313static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
314{
315}
316
317static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
318 int write)
319{
320 struct page *page;
321
322 page = bprm->page[pos / PAGE_SIZE];
323 if (!page && write) {
324 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
325 if (!page)
326 return NULL;
327 bprm->page[pos / PAGE_SIZE] = page;
328 }
329
330 return page;
331}
332
333static void put_arg_page(struct page *page)
334{
335}
336
337static void free_arg_page(struct linux_binprm *bprm, int i)
338{
339 if (bprm->page[i]) {
340 __free_page(bprm->page[i]);
341 bprm->page[i] = NULL;
342 }
343}
344
345static void free_arg_pages(struct linux_binprm *bprm)
346{
347 int i;
348
349 for (i = 0; i < MAX_ARG_PAGES; i++)
350 free_arg_page(bprm, i);
351}
352
353static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
354 struct page *page)
355{
356}
357
358static int __bprm_mm_init(struct linux_binprm *bprm)
359{
360 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
361 return 0;
362}
363
364static bool valid_arg_len(struct linux_binprm *bprm, long len)
365{
366 return len <= bprm->p;
367}
368
369#endif /* CONFIG_MMU */
370
371/*
372 * Create a new mm_struct and populate it with a temporary stack
373 * vm_area_struct. We don't have enough context at this point to set the stack
374 * flags, permissions, and offset, so we use temporary values. We'll update
375 * them later in setup_arg_pages().
376 */
377int bprm_mm_init(struct linux_binprm *bprm)
378{
379 int err;
380 struct mm_struct *mm = NULL;
381
382 bprm->mm = mm = mm_alloc();
383 err = -ENOMEM;
384 if (!mm)
385 goto err;
386
387 err = init_new_context(current, mm);
388 if (err)
389 goto err;
390
391 err = __bprm_mm_init(bprm);
392 if (err)
393 goto err;
394
395 return 0;
396
397err:
398 if (mm) {
399 bprm->mm = NULL;
400 mmdrop(mm);
401 }
402
403 return err;
404}
405
406struct user_arg_ptr {
407#ifdef CONFIG_COMPAT
408 bool is_compat;
409#endif
410 union {
411 const char __user *const __user *native;
412#ifdef CONFIG_COMPAT
413 compat_uptr_t __user *compat;
414#endif
415 } ptr;
416};
417
418static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
419{
420 const char __user *native;
421
422#ifdef CONFIG_COMPAT
423 if (unlikely(argv.is_compat)) {
424 compat_uptr_t compat;
425
426 if (get_user(compat, argv.ptr.compat + nr))
427 return ERR_PTR(-EFAULT);
428
429 return compat_ptr(compat);
430 }
431#endif
432
433 if (get_user(native, argv.ptr.native + nr))
434 return ERR_PTR(-EFAULT);
435
436 return native;
437}
438
439/*
440 * count() counts the number of strings in array ARGV.
441 */
442static int count(struct user_arg_ptr argv, int max)
443{
444 int i = 0;
445
446 if (argv.ptr.native != NULL) {
447 for (;;) {
448 const char __user *p = get_user_arg_ptr(argv, i);
449
450 if (!p)
451 break;
452
453 if (IS_ERR(p))
454 return -EFAULT;
455
456 if (i++ >= max)
457 return -E2BIG;
458
459 if (fatal_signal_pending(current))
460 return -ERESTARTNOHAND;
461 cond_resched();
462 }
463 }
464 return i;
465}
466
467/*
468 * 'copy_strings()' copies argument/environment strings from the old
469 * processes's memory to the new process's stack. The call to get_user_pages()
470 * ensures the destination page is created and not swapped out.
471 */
472static int copy_strings(int argc, struct user_arg_ptr argv,
473 struct linux_binprm *bprm)
474{
475 struct page *kmapped_page = NULL;
476 char *kaddr = NULL;
477 unsigned long kpos = 0;
478 int ret;
479
480 while (argc-- > 0) {
481 const char __user *str;
482 int len;
483 unsigned long pos;
484
485 ret = -EFAULT;
486 str = get_user_arg_ptr(argv, argc);
487 if (IS_ERR(str))
488 goto out;
489
490 len = strnlen_user(str, MAX_ARG_STRLEN);
491 if (!len)
492 goto out;
493
494 ret = -E2BIG;
495 if (!valid_arg_len(bprm, len))
496 goto out;
497
498 /* We're going to work our way backwords. */
499 pos = bprm->p;
500 str += len;
501 bprm->p -= len;
502
503 while (len > 0) {
504 int offset, bytes_to_copy;
505
506 if (fatal_signal_pending(current)) {
507 ret = -ERESTARTNOHAND;
508 goto out;
509 }
510 cond_resched();
511
512 offset = pos % PAGE_SIZE;
513 if (offset == 0)
514 offset = PAGE_SIZE;
515
516 bytes_to_copy = offset;
517 if (bytes_to_copy > len)
518 bytes_to_copy = len;
519
520 offset -= bytes_to_copy;
521 pos -= bytes_to_copy;
522 str -= bytes_to_copy;
523 len -= bytes_to_copy;
524
525 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
526 struct page *page;
527
528 page = get_arg_page(bprm, pos, 1);
529 if (!page) {
530 ret = -E2BIG;
531 goto out;
532 }
533
534 if (kmapped_page) {
535 flush_kernel_dcache_page(kmapped_page);
536 kunmap(kmapped_page);
537 put_arg_page(kmapped_page);
538 }
539 kmapped_page = page;
540 kaddr = kmap(kmapped_page);
541 kpos = pos & PAGE_MASK;
542 flush_arg_page(bprm, kpos, kmapped_page);
543 }
544 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
545 ret = -EFAULT;
546 goto out;
547 }
548 }
549 }
550 ret = 0;
551out:
552 if (kmapped_page) {
553 flush_kernel_dcache_page(kmapped_page);
554 kunmap(kmapped_page);
555 put_arg_page(kmapped_page);
556 }
557 return ret;
558}
559
560/*
561 * Like copy_strings, but get argv and its values from kernel memory.
562 */
563int copy_strings_kernel(int argc, const char *const *__argv,
564 struct linux_binprm *bprm)
565{
566 int r;
567 mm_segment_t oldfs = get_fs();
568 struct user_arg_ptr argv = {
569 .ptr.native = (const char __user *const __user *)__argv,
570 };
571
572 set_fs(KERNEL_DS);
573 r = copy_strings(argc, argv, bprm);
574 set_fs(oldfs);
575
576 return r;
577}
578EXPORT_SYMBOL(copy_strings_kernel);
579
580#ifdef CONFIG_MMU
581
582/*
583 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
584 * the binfmt code determines where the new stack should reside, we shift it to
585 * its final location. The process proceeds as follows:
586 *
587 * 1) Use shift to calculate the new vma endpoints.
588 * 2) Extend vma to cover both the old and new ranges. This ensures the
589 * arguments passed to subsequent functions are consistent.
590 * 3) Move vma's page tables to the new range.
591 * 4) Free up any cleared pgd range.
592 * 5) Shrink the vma to cover only the new range.
593 */
594static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
595{
596 struct mm_struct *mm = vma->vm_mm;
597 unsigned long old_start = vma->vm_start;
598 unsigned long old_end = vma->vm_end;
599 unsigned long length = old_end - old_start;
600 unsigned long new_start = old_start - shift;
601 unsigned long new_end = old_end - shift;
602 struct mmu_gather tlb;
603
604 BUG_ON(new_start > new_end);
605
606 /*
607 * ensure there are no vmas between where we want to go
608 * and where we are
609 */
610 if (vma != find_vma(mm, new_start))
611 return -EFAULT;
612
613 /*
614 * cover the whole range: [new_start, old_end)
615 */
616 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
617 return -ENOMEM;
618
619 /*
620 * move the page tables downwards, on failure we rely on
621 * process cleanup to remove whatever mess we made.
622 */
623 if (length != move_page_tables(vma, old_start,
624 vma, new_start, length))
625 return -ENOMEM;
626
627 lru_add_drain();
628 tlb_gather_mmu(&tlb, mm, 0);
629 if (new_end > old_start) {
630 /*
631 * when the old and new regions overlap clear from new_end.
632 */
633 free_pgd_range(&tlb, new_end, old_end, new_end,
634 vma->vm_next ? vma->vm_next->vm_start : 0);
635 } else {
636 /*
637 * otherwise, clean from old_start; this is done to not touch
638 * the address space in [new_end, old_start) some architectures
639 * have constraints on va-space that make this illegal (IA64) -
640 * for the others its just a little faster.
641 */
642 free_pgd_range(&tlb, old_start, old_end, new_end,
643 vma->vm_next ? vma->vm_next->vm_start : 0);
644 }
645 tlb_finish_mmu(&tlb, new_end, old_end);
646
647 /*
648 * Shrink the vma to just the new range. Always succeeds.
649 */
650 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
651
652 return 0;
653}
654
655/*
656 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
657 * the stack is optionally relocated, and some extra space is added.
658 */
659int setup_arg_pages(struct linux_binprm *bprm,
660 unsigned long stack_top,
661 int executable_stack)
662{
663 unsigned long ret;
664 unsigned long stack_shift;
665 struct mm_struct *mm = current->mm;
666 struct vm_area_struct *vma = bprm->vma;
667 struct vm_area_struct *prev = NULL;
668 unsigned long vm_flags;
669 unsigned long stack_base;
670 unsigned long stack_size;
671 unsigned long stack_expand;
672 unsigned long rlim_stack;
673
674#ifdef CONFIG_STACK_GROWSUP
675 /* Limit stack size to 1GB */
676 stack_base = rlimit_max(RLIMIT_STACK);
677 if (stack_base > (1 << 30))
678 stack_base = 1 << 30;
679
680 /* Make sure we didn't let the argument array grow too large. */
681 if (vma->vm_end - vma->vm_start > stack_base)
682 return -ENOMEM;
683
684 stack_base = PAGE_ALIGN(stack_top - stack_base);
685
686 stack_shift = vma->vm_start - stack_base;
687 mm->arg_start = bprm->p - stack_shift;
688 bprm->p = vma->vm_end - stack_shift;
689#else
690 stack_top = arch_align_stack(stack_top);
691 stack_top = PAGE_ALIGN(stack_top);
692
693 if (unlikely(stack_top < mmap_min_addr) ||
694 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
695 return -ENOMEM;
696
697 stack_shift = vma->vm_end - stack_top;
698
699 bprm->p -= stack_shift;
700 mm->arg_start = bprm->p;
701#endif
702
703 if (bprm->loader)
704 bprm->loader -= stack_shift;
705 bprm->exec -= stack_shift;
706
707 down_write(&mm->mmap_sem);
708 vm_flags = VM_STACK_FLAGS;
709
710 /*
711 * Adjust stack execute permissions; explicitly enable for
712 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
713 * (arch default) otherwise.
714 */
715 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
716 vm_flags |= VM_EXEC;
717 else if (executable_stack == EXSTACK_DISABLE_X)
718 vm_flags &= ~VM_EXEC;
719 vm_flags |= mm->def_flags;
720 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
721
722 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
723 vm_flags);
724 if (ret)
725 goto out_unlock;
726 BUG_ON(prev != vma);
727
728 /* Move stack pages down in memory. */
729 if (stack_shift) {
730 ret = shift_arg_pages(vma, stack_shift);
731 if (ret)
732 goto out_unlock;
733 }
734
735 /* mprotect_fixup is overkill to remove the temporary stack flags */
736 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
737
738 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
739 stack_size = vma->vm_end - vma->vm_start;
740 /*
741 * Align this down to a page boundary as expand_stack
742 * will align it up.
743 */
744 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
745#ifdef CONFIG_STACK_GROWSUP
746 if (stack_size + stack_expand > rlim_stack)
747 stack_base = vma->vm_start + rlim_stack;
748 else
749 stack_base = vma->vm_end + stack_expand;
750#else
751 if (stack_size + stack_expand > rlim_stack)
752 stack_base = vma->vm_end - rlim_stack;
753 else
754 stack_base = vma->vm_start - stack_expand;
755#endif
756 current->mm->start_stack = bprm->p;
757 ret = expand_stack(vma, stack_base);
758 if (ret)
759 ret = -EFAULT;
760
761out_unlock:
762 up_write(&mm->mmap_sem);
763 return ret;
764}
765EXPORT_SYMBOL(setup_arg_pages);
766
767#endif /* CONFIG_MMU */
768
769struct file *open_exec(const char *name)
770{
771 struct file *file;
772 int err;
773 static const struct open_flags open_exec_flags = {
774 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
775 .acc_mode = MAY_EXEC | MAY_OPEN,
776 .intent = LOOKUP_OPEN
777 };
778
779 file = do_filp_open(AT_FDCWD, name, &open_exec_flags, LOOKUP_FOLLOW);
780 if (IS_ERR(file))
781 goto out;
782
783 err = -EACCES;
784 if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
785 goto exit;
786
787 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
788 goto exit;
789
790 fsnotify_open(file);
791
792 err = deny_write_access(file);
793 if (err)
794 goto exit;
795
796out:
797 return file;
798
799exit:
800 fput(file);
801 return ERR_PTR(err);
802}
803EXPORT_SYMBOL(open_exec);
804
805int kernel_read(struct file *file, loff_t offset,
806 char *addr, unsigned long count)
807{
808 mm_segment_t old_fs;
809 loff_t pos = offset;
810 int result;
811
812 old_fs = get_fs();
813 set_fs(get_ds());
814 /* The cast to a user pointer is valid due to the set_fs() */
815 result = vfs_read(file, (void __user *)addr, count, &pos);
816 set_fs(old_fs);
817 return result;
818}
819
820EXPORT_SYMBOL(kernel_read);
821
822static int exec_mmap(struct mm_struct *mm)
823{
824 struct task_struct *tsk;
825 struct mm_struct * old_mm, *active_mm;
826
827 /* Notify parent that we're no longer interested in the old VM */
828 tsk = current;
829 old_mm = current->mm;
830 sync_mm_rss(tsk, old_mm);
831 mm_release(tsk, old_mm);
832
833 if (old_mm) {
834 /*
835 * Make sure that if there is a core dump in progress
836 * for the old mm, we get out and die instead of going
837 * through with the exec. We must hold mmap_sem around
838 * checking core_state and changing tsk->mm.
839 */
840 down_read(&old_mm->mmap_sem);
841 if (unlikely(old_mm->core_state)) {
842 up_read(&old_mm->mmap_sem);
843 return -EINTR;
844 }
845 }
846 task_lock(tsk);
847 active_mm = tsk->active_mm;
848 tsk->mm = mm;
849 tsk->active_mm = mm;
850 activate_mm(active_mm, mm);
851 if (old_mm && tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN) {
852 atomic_dec(&old_mm->oom_disable_count);
853 atomic_inc(&tsk->mm->oom_disable_count);
854 }
855 task_unlock(tsk);
856 arch_pick_mmap_layout(mm);
857 if (old_mm) {
858 up_read(&old_mm->mmap_sem);
859 BUG_ON(active_mm != old_mm);
860 mm_update_next_owner(old_mm);
861 mmput(old_mm);
862 return 0;
863 }
864 mmdrop(active_mm);
865 return 0;
866}
867
868/*
869 * This function makes sure the current process has its own signal table,
870 * so that flush_signal_handlers can later reset the handlers without
871 * disturbing other processes. (Other processes might share the signal
872 * table via the CLONE_SIGHAND option to clone().)
873 */
874static int de_thread(struct task_struct *tsk)
875{
876 struct signal_struct *sig = tsk->signal;
877 struct sighand_struct *oldsighand = tsk->sighand;
878 spinlock_t *lock = &oldsighand->siglock;
879
880 if (thread_group_empty(tsk))
881 goto no_thread_group;
882
883 /*
884 * Kill all other threads in the thread group.
885 */
886 spin_lock_irq(lock);
887 if (signal_group_exit(sig)) {
888 /*
889 * Another group action in progress, just
890 * return so that the signal is processed.
891 */
892 spin_unlock_irq(lock);
893 return -EAGAIN;
894 }
895
896 sig->group_exit_task = tsk;
897 sig->notify_count = zap_other_threads(tsk);
898 if (!thread_group_leader(tsk))
899 sig->notify_count--;
900
901 while (sig->notify_count) {
902 __set_current_state(TASK_UNINTERRUPTIBLE);
903 spin_unlock_irq(lock);
904 schedule();
905 spin_lock_irq(lock);
906 }
907 spin_unlock_irq(lock);
908
909 /*
910 * At this point all other threads have exited, all we have to
911 * do is to wait for the thread group leader to become inactive,
912 * and to assume its PID:
913 */
914 if (!thread_group_leader(tsk)) {
915 struct task_struct *leader = tsk->group_leader;
916
917 sig->notify_count = -1; /* for exit_notify() */
918 for (;;) {
919 write_lock_irq(&tasklist_lock);
920 if (likely(leader->exit_state))
921 break;
922 __set_current_state(TASK_UNINTERRUPTIBLE);
923 write_unlock_irq(&tasklist_lock);
924 schedule();
925 }
926
927 /*
928 * The only record we have of the real-time age of a
929 * process, regardless of execs it's done, is start_time.
930 * All the past CPU time is accumulated in signal_struct
931 * from sister threads now dead. But in this non-leader
932 * exec, nothing survives from the original leader thread,
933 * whose birth marks the true age of this process now.
934 * When we take on its identity by switching to its PID, we
935 * also take its birthdate (always earlier than our own).
936 */
937 tsk->start_time = leader->start_time;
938
939 BUG_ON(!same_thread_group(leader, tsk));
940 BUG_ON(has_group_leader_pid(tsk));
941 /*
942 * An exec() starts a new thread group with the
943 * TGID of the previous thread group. Rehash the
944 * two threads with a switched PID, and release
945 * the former thread group leader:
946 */
947
948 /* Become a process group leader with the old leader's pid.
949 * The old leader becomes a thread of the this thread group.
950 * Note: The old leader also uses this pid until release_task
951 * is called. Odd but simple and correct.
952 */
953 detach_pid(tsk, PIDTYPE_PID);
954 tsk->pid = leader->pid;
955 attach_pid(tsk, PIDTYPE_PID, task_pid(leader));
956 transfer_pid(leader, tsk, PIDTYPE_PGID);
957 transfer_pid(leader, tsk, PIDTYPE_SID);
958
959 list_replace_rcu(&leader->tasks, &tsk->tasks);
960 list_replace_init(&leader->sibling, &tsk->sibling);
961
962 tsk->group_leader = tsk;
963 leader->group_leader = tsk;
964
965 tsk->exit_signal = SIGCHLD;
966
967 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
968 leader->exit_state = EXIT_DEAD;
969 write_unlock_irq(&tasklist_lock);
970
971 release_task(leader);
972 }
973
974 sig->group_exit_task = NULL;
975 sig->notify_count = 0;
976
977no_thread_group:
978 if (current->mm)
979 setmax_mm_hiwater_rss(&sig->maxrss, current->mm);
980
981 exit_itimers(sig);
982 flush_itimer_signals();
983
984 if (atomic_read(&oldsighand->count) != 1) {
985 struct sighand_struct *newsighand;
986 /*
987 * This ->sighand is shared with the CLONE_SIGHAND
988 * but not CLONE_THREAD task, switch to the new one.
989 */
990 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
991 if (!newsighand)
992 return -ENOMEM;
993
994 atomic_set(&newsighand->count, 1);
995 memcpy(newsighand->action, oldsighand->action,
996 sizeof(newsighand->action));
997
998 write_lock_irq(&tasklist_lock);
999 spin_lock(&oldsighand->siglock);
1000 rcu_assign_pointer(tsk->sighand, newsighand);
1001 spin_unlock(&oldsighand->siglock);
1002 write_unlock_irq(&tasklist_lock);
1003
1004 __cleanup_sighand(oldsighand);
1005 }
1006
1007 BUG_ON(!thread_group_leader(tsk));
1008 return 0;
1009}
1010
1011/*
1012 * These functions flushes out all traces of the currently running executable
1013 * so that a new one can be started
1014 */
1015static void flush_old_files(struct files_struct * files)
1016{
1017 long j = -1;
1018 struct fdtable *fdt;
1019
1020 spin_lock(&files->file_lock);
1021 for (;;) {
1022 unsigned long set, i;
1023
1024 j++;
1025 i = j * __NFDBITS;
1026 fdt = files_fdtable(files);
1027 if (i >= fdt->max_fds)
1028 break;
1029 set = fdt->close_on_exec->fds_bits[j];
1030 if (!set)
1031 continue;
1032 fdt->close_on_exec->fds_bits[j] = 0;
1033 spin_unlock(&files->file_lock);
1034 for ( ; set ; i++,set >>= 1) {
1035 if (set & 1) {
1036 sys_close(i);
1037 }
1038 }
1039 spin_lock(&files->file_lock);
1040
1041 }
1042 spin_unlock(&files->file_lock);
1043}
1044
1045char *get_task_comm(char *buf, struct task_struct *tsk)
1046{
1047 /* buf must be at least sizeof(tsk->comm) in size */
1048 task_lock(tsk);
1049 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1050 task_unlock(tsk);
1051 return buf;
1052}
1053EXPORT_SYMBOL_GPL(get_task_comm);
1054
1055void set_task_comm(struct task_struct *tsk, char *buf)
1056{
1057 task_lock(tsk);
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
1072int flush_old_exec(struct linux_binprm * bprm)
1073{
1074 int retval;
1075
1076 /*
1077 * Make sure we have a private signal table and that
1078 * we are unassociated from the previous thread group.
1079 */
1080 retval = de_thread(current);
1081 if (retval)
1082 goto out;
1083
1084 set_mm_exe_file(bprm->mm, bprm->file);
1085
1086 /*
1087 * Release all of the old mmap stuff
1088 */
1089 acct_arg_size(bprm, 0);
1090 retval = exec_mmap(bprm->mm);
1091 if (retval)
1092 goto out;
1093
1094 bprm->mm = NULL; /* We're using it now */
1095
1096 set_fs(USER_DS);
1097 current->flags &= ~(PF_RANDOMIZE | PF_KTHREAD);
1098 flush_thread();
1099 current->personality &= ~bprm->per_clear;
1100
1101 return 0;
1102
1103out:
1104 return retval;
1105}
1106EXPORT_SYMBOL(flush_old_exec);
1107
1108void setup_new_exec(struct linux_binprm * bprm)
1109{
1110 int i, ch;
1111 const char *name;
1112 char tcomm[sizeof(current->comm)];
1113
1114 arch_pick_mmap_layout(current->mm);
1115
1116 /* This is the point of no return */
1117 current->sas_ss_sp = current->sas_ss_size = 0;
1118
1119 if (current_euid() == current_uid() && current_egid() == current_gid())
1120 set_dumpable(current->mm, 1);
1121 else
1122 set_dumpable(current->mm, suid_dumpable);
1123
1124 name = bprm->filename;
1125
1126 /* Copies the binary name from after last slash */
1127 for (i=0; (ch = *(name++)) != '\0';) {
1128 if (ch == '/')
1129 i = 0; /* overwrite what we wrote */
1130 else
1131 if (i < (sizeof(tcomm) - 1))
1132 tcomm[i++] = ch;
1133 }
1134 tcomm[i] = '\0';
1135 set_task_comm(current, tcomm);
1136
1137 /* Set the new mm task size. We have to do that late because it may
1138 * depend on TIF_32BIT which is only updated in flush_thread() on
1139 * some architectures like powerpc
1140 */
1141 current->mm->task_size = TASK_SIZE;
1142
1143 /* install the new credentials */
1144 if (bprm->cred->uid != current_euid() ||
1145 bprm->cred->gid != current_egid()) {
1146 current->pdeath_signal = 0;
1147 } else if (file_permission(bprm->file, MAY_READ) ||
1148 bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP) {
1149 set_dumpable(current->mm, suid_dumpable);
1150 }
1151
1152 /*
1153 * Flush performance counters when crossing a
1154 * security domain:
1155 */
1156 if (!get_dumpable(current->mm))
1157 perf_event_exit_task(current);
1158
1159 /* An exec changes our domain. We are no longer part of the thread
1160 group */
1161
1162 current->self_exec_id++;
1163
1164 flush_signal_handlers(current, 0);
1165 flush_old_files(current->files);
1166}
1167EXPORT_SYMBOL(setup_new_exec);
1168
1169/*
1170 * Prepare credentials and lock ->cred_guard_mutex.
1171 * install_exec_creds() commits the new creds and drops the lock.
1172 * Or, if exec fails before, free_bprm() should release ->cred and
1173 * and unlock.
1174 */
1175int prepare_bprm_creds(struct linux_binprm *bprm)
1176{
1177 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1178 return -ERESTARTNOINTR;
1179
1180 bprm->cred = prepare_exec_creds();
1181 if (likely(bprm->cred))
1182 return 0;
1183
1184 mutex_unlock(&current->signal->cred_guard_mutex);
1185 return -ENOMEM;
1186}
1187
1188void free_bprm(struct linux_binprm *bprm)
1189{
1190 free_arg_pages(bprm);
1191 if (bprm->cred) {
1192 mutex_unlock(&current->signal->cred_guard_mutex);
1193 abort_creds(bprm->cred);
1194 }
1195 kfree(bprm);
1196}
1197
1198/*
1199 * install the new credentials for this executable
1200 */
1201void install_exec_creds(struct linux_binprm *bprm)
1202{
1203 security_bprm_committing_creds(bprm);
1204
1205 commit_creds(bprm->cred);
1206 bprm->cred = NULL;
1207 /*
1208 * cred_guard_mutex must be held at least to this point to prevent
1209 * ptrace_attach() from altering our determination of the task's
1210 * credentials; any time after this it may be unlocked.
1211 */
1212 security_bprm_committed_creds(bprm);
1213 mutex_unlock(&current->signal->cred_guard_mutex);
1214}
1215EXPORT_SYMBOL(install_exec_creds);
1216
1217/*
1218 * determine how safe it is to execute the proposed program
1219 * - the caller must hold ->cred_guard_mutex to protect against
1220 * PTRACE_ATTACH
1221 */
1222int check_unsafe_exec(struct linux_binprm *bprm)
1223{
1224 struct task_struct *p = current, *t;
1225 unsigned n_fs;
1226 int res = 0;
1227
1228 bprm->unsafe = tracehook_unsafe_exec(p);
1229
1230 n_fs = 1;
1231 spin_lock(&p->fs->lock);
1232 rcu_read_lock();
1233 for (t = next_thread(p); t != p; t = next_thread(t)) {
1234 if (t->fs == p->fs)
1235 n_fs++;
1236 }
1237 rcu_read_unlock();
1238
1239 if (p->fs->users > n_fs) {
1240 bprm->unsafe |= LSM_UNSAFE_SHARE;
1241 } else {
1242 res = -EAGAIN;
1243 if (!p->fs->in_exec) {
1244 p->fs->in_exec = 1;
1245 res = 1;
1246 }
1247 }
1248 spin_unlock(&p->fs->lock);
1249
1250 return res;
1251}
1252
1253/*
1254 * Fill the binprm structure from the inode.
1255 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1256 *
1257 * This may be called multiple times for binary chains (scripts for example).
1258 */
1259int prepare_binprm(struct linux_binprm *bprm)
1260{
1261 umode_t mode;
1262 struct inode * inode = bprm->file->f_path.dentry->d_inode;
1263 int retval;
1264
1265 mode = inode->i_mode;
1266 if (bprm->file->f_op == NULL)
1267 return -EACCES;
1268
1269 /* clear any previous set[ug]id data from a previous binary */
1270 bprm->cred->euid = current_euid();
1271 bprm->cred->egid = current_egid();
1272
1273 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)) {
1274 /* Set-uid? */
1275 if (mode & S_ISUID) {
1276 bprm->per_clear |= PER_CLEAR_ON_SETID;
1277 bprm->cred->euid = inode->i_uid;
1278 }
1279
1280 /* Set-gid? */
1281 /*
1282 * If setgid is set but no group execute bit then this
1283 * is a candidate for mandatory locking, not a setgid
1284 * executable.
1285 */
1286 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1287 bprm->per_clear |= PER_CLEAR_ON_SETID;
1288 bprm->cred->egid = inode->i_gid;
1289 }
1290 }
1291
1292 /* fill in binprm security blob */
1293 retval = security_bprm_set_creds(bprm);
1294 if (retval)
1295 return retval;
1296 bprm->cred_prepared = 1;
1297
1298 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1299 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1300}
1301
1302EXPORT_SYMBOL(prepare_binprm);
1303
1304/*
1305 * Arguments are '\0' separated strings found at the location bprm->p
1306 * points to; chop off the first by relocating brpm->p to right after
1307 * the first '\0' encountered.
1308 */
1309int remove_arg_zero(struct linux_binprm *bprm)
1310{
1311 int ret = 0;
1312 unsigned long offset;
1313 char *kaddr;
1314 struct page *page;
1315
1316 if (!bprm->argc)
1317 return 0;
1318
1319 do {
1320 offset = bprm->p & ~PAGE_MASK;
1321 page = get_arg_page(bprm, bprm->p, 0);
1322 if (!page) {
1323 ret = -EFAULT;
1324 goto out;
1325 }
1326 kaddr = kmap_atomic(page, KM_USER0);
1327
1328 for (; offset < PAGE_SIZE && kaddr[offset];
1329 offset++, bprm->p++)
1330 ;
1331
1332 kunmap_atomic(kaddr, KM_USER0);
1333 put_arg_page(page);
1334
1335 if (offset == PAGE_SIZE)
1336 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1337 } while (offset == PAGE_SIZE);
1338
1339 bprm->p++;
1340 bprm->argc--;
1341 ret = 0;
1342
1343out:
1344 return ret;
1345}
1346EXPORT_SYMBOL(remove_arg_zero);
1347
1348/*
1349 * cycle the list of binary formats handler, until one recognizes the image
1350 */
1351int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
1352{
1353 unsigned int depth = bprm->recursion_depth;
1354 int try,retval;
1355 struct linux_binfmt *fmt;
1356
1357 retval = security_bprm_check(bprm);
1358 if (retval)
1359 return retval;
1360
1361 retval = audit_bprm(bprm);
1362 if (retval)
1363 return retval;
1364
1365 retval = -ENOENT;
1366 for (try=0; try<2; try++) {
1367 read_lock(&binfmt_lock);
1368 list_for_each_entry(fmt, &formats, lh) {
1369 int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
1370 if (!fn)
1371 continue;
1372 if (!try_module_get(fmt->module))
1373 continue;
1374 read_unlock(&binfmt_lock);
1375 retval = fn(bprm, regs);
1376 /*
1377 * Restore the depth counter to its starting value
1378 * in this call, so we don't have to rely on every
1379 * load_binary function to restore it on return.
1380 */
1381 bprm->recursion_depth = depth;
1382 if (retval >= 0) {
1383 if (depth == 0)
1384 tracehook_report_exec(fmt, bprm, regs);
1385 put_binfmt(fmt);
1386 allow_write_access(bprm->file);
1387 if (bprm->file)
1388 fput(bprm->file);
1389 bprm->file = NULL;
1390 current->did_exec = 1;
1391 proc_exec_connector(current);
1392 return retval;
1393 }
1394 read_lock(&binfmt_lock);
1395 put_binfmt(fmt);
1396 if (retval != -ENOEXEC || bprm->mm == NULL)
1397 break;
1398 if (!bprm->file) {
1399 read_unlock(&binfmt_lock);
1400 return retval;
1401 }
1402 }
1403 read_unlock(&binfmt_lock);
1404 if (retval != -ENOEXEC || bprm->mm == NULL) {
1405 break;
1406#ifdef CONFIG_MODULES
1407 } else {
1408#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1409 if (printable(bprm->buf[0]) &&
1410 printable(bprm->buf[1]) &&
1411 printable(bprm->buf[2]) &&
1412 printable(bprm->buf[3]))
1413 break; /* -ENOEXEC */
1414 request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
1415#endif
1416 }
1417 }
1418 return retval;
1419}
1420
1421EXPORT_SYMBOL(search_binary_handler);
1422
1423/*
1424 * sys_execve() executes a new program.
1425 */
1426static int do_execve_common(const char *filename,
1427 struct user_arg_ptr argv,
1428 struct user_arg_ptr envp,
1429 struct pt_regs *regs)
1430{
1431 struct linux_binprm *bprm;
1432 struct file *file;
1433 struct files_struct *displaced;
1434 bool clear_in_exec;
1435 int retval;
1436
1437 retval = unshare_files(&displaced);
1438 if (retval)
1439 goto out_ret;
1440
1441 retval = -ENOMEM;
1442 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1443 if (!bprm)
1444 goto out_files;
1445
1446 retval = prepare_bprm_creds(bprm);
1447 if (retval)
1448 goto out_free;
1449
1450 retval = check_unsafe_exec(bprm);
1451 if (retval < 0)
1452 goto out_free;
1453 clear_in_exec = retval;
1454 current->in_execve = 1;
1455
1456 file = open_exec(filename);
1457 retval = PTR_ERR(file);
1458 if (IS_ERR(file))
1459 goto out_unmark;
1460
1461 sched_exec();
1462
1463 bprm->file = file;
1464 bprm->filename = filename;
1465 bprm->interp = filename;
1466
1467 retval = bprm_mm_init(bprm);
1468 if (retval)
1469 goto out_file;
1470
1471 bprm->argc = count(argv, MAX_ARG_STRINGS);
1472 if ((retval = bprm->argc) < 0)
1473 goto out;
1474
1475 bprm->envc = count(envp, MAX_ARG_STRINGS);
1476 if ((retval = bprm->envc) < 0)
1477 goto out;
1478
1479 retval = prepare_binprm(bprm);
1480 if (retval < 0)
1481 goto out;
1482
1483 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1484 if (retval < 0)
1485 goto out;
1486
1487 bprm->exec = bprm->p;
1488 retval = copy_strings(bprm->envc, envp, bprm);
1489 if (retval < 0)
1490 goto out;
1491
1492 retval = copy_strings(bprm->argc, argv, bprm);
1493 if (retval < 0)
1494 goto out;
1495
1496 retval = search_binary_handler(bprm,regs);
1497 if (retval < 0)
1498 goto out;
1499
1500 /* execve succeeded */
1501 current->fs->in_exec = 0;
1502 current->in_execve = 0;
1503 acct_update_integrals(current);
1504 free_bprm(bprm);
1505 if (displaced)
1506 put_files_struct(displaced);
1507 return retval;
1508
1509out:
1510 if (bprm->mm) {
1511 acct_arg_size(bprm, 0);
1512 mmput(bprm->mm);
1513 }
1514
1515out_file:
1516 if (bprm->file) {
1517 allow_write_access(bprm->file);
1518 fput(bprm->file);
1519 }
1520
1521out_unmark:
1522 if (clear_in_exec)
1523 current->fs->in_exec = 0;
1524 current->in_execve = 0;
1525
1526out_free:
1527 free_bprm(bprm);
1528
1529out_files:
1530 if (displaced)
1531 reset_files_struct(displaced);
1532out_ret:
1533 return retval;
1534}
1535
1536int do_execve(const char *filename,
1537 const char __user *const __user *__argv,
1538 const char __user *const __user *__envp,
1539 struct pt_regs *regs)
1540{
1541 struct user_arg_ptr argv = { .ptr.native = __argv };
1542 struct user_arg_ptr envp = { .ptr.native = __envp };
1543 return do_execve_common(filename, argv, envp, regs);
1544}
1545
1546#ifdef CONFIG_COMPAT
1547int compat_do_execve(char *filename,
1548 compat_uptr_t __user *__argv,
1549 compat_uptr_t __user *__envp,
1550 struct pt_regs *regs)
1551{
1552 struct user_arg_ptr argv = {
1553 .is_compat = true,
1554 .ptr.compat = __argv,
1555 };
1556 struct user_arg_ptr envp = {
1557 .is_compat = true,
1558 .ptr.compat = __envp,
1559 };
1560 return do_execve_common(filename, argv, envp, regs);
1561}
1562#endif
1563
1564void set_binfmt(struct linux_binfmt *new)
1565{
1566 struct mm_struct *mm = current->mm;
1567
1568 if (mm->binfmt)
1569 module_put(mm->binfmt->module);
1570
1571 mm->binfmt = new;
1572 if (new)
1573 __module_get(new->module);
1574}
1575
1576EXPORT_SYMBOL(set_binfmt);
1577
1578static int expand_corename(struct core_name *cn)
1579{
1580 char *old_corename = cn->corename;
1581
1582 cn->size = CORENAME_MAX_SIZE * atomic_inc_return(&call_count);
1583 cn->corename = krealloc(old_corename, cn->size, GFP_KERNEL);
1584
1585 if (!cn->corename) {
1586 kfree(old_corename);
1587 return -ENOMEM;
1588 }
1589
1590 return 0;
1591}
1592
1593static int cn_printf(struct core_name *cn, const char *fmt, ...)
1594{
1595 char *cur;
1596 int need;
1597 int ret;
1598 va_list arg;
1599
1600 va_start(arg, fmt);
1601 need = vsnprintf(NULL, 0, fmt, arg);
1602 va_end(arg);
1603
1604 if (likely(need < cn->size - cn->used - 1))
1605 goto out_printf;
1606
1607 ret = expand_corename(cn);
1608 if (ret)
1609 goto expand_fail;
1610
1611out_printf:
1612 cur = cn->corename + cn->used;
1613 va_start(arg, fmt);
1614 vsnprintf(cur, need + 1, fmt, arg);
1615 va_end(arg);
1616 cn->used += need;
1617 return 0;
1618
1619expand_fail:
1620 return ret;
1621}
1622
1623static int cn_print_exe_file(struct core_name *cn)
1624{
1625 struct file *exe_file;
1626 char *pathbuf, *path, *p;
1627 int ret;
1628
1629 exe_file = get_mm_exe_file(current->mm);
1630 if (!exe_file)
1631 return cn_printf(cn, "(unknown)");
1632
1633 pathbuf = kmalloc(PATH_MAX, GFP_TEMPORARY);
1634 if (!pathbuf) {
1635 ret = -ENOMEM;
1636 goto put_exe_file;
1637 }
1638
1639 path = d_path(&exe_file->f_path, pathbuf, PATH_MAX);
1640 if (IS_ERR(path)) {
1641 ret = PTR_ERR(path);
1642 goto free_buf;
1643 }
1644
1645 for (p = path; *p; p++)
1646 if (*p == '/')
1647 *p = '!';
1648
1649 ret = cn_printf(cn, "%s", path);
1650
1651free_buf:
1652 kfree(pathbuf);
1653put_exe_file:
1654 fput(exe_file);
1655 return ret;
1656}
1657
1658/* format_corename will inspect the pattern parameter, and output a
1659 * name into corename, which must have space for at least
1660 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1661 */
1662static int format_corename(struct core_name *cn, long signr)
1663{
1664 const struct cred *cred = current_cred();
1665 const char *pat_ptr = core_pattern;
1666 int ispipe = (*pat_ptr == '|');
1667 int pid_in_pattern = 0;
1668 int err = 0;
1669
1670 cn->size = CORENAME_MAX_SIZE * atomic_read(&call_count);
1671 cn->corename = kmalloc(cn->size, GFP_KERNEL);
1672 cn->used = 0;
1673
1674 if (!cn->corename)
1675 return -ENOMEM;
1676
1677 /* Repeat as long as we have more pattern to process and more output
1678 space */
1679 while (*pat_ptr) {
1680 if (*pat_ptr != '%') {
1681 if (*pat_ptr == 0)
1682 goto out;
1683 err = cn_printf(cn, "%c", *pat_ptr++);
1684 } else {
1685 switch (*++pat_ptr) {
1686 /* single % at the end, drop that */
1687 case 0:
1688 goto out;
1689 /* Double percent, output one percent */
1690 case '%':
1691 err = cn_printf(cn, "%c", '%');
1692 break;
1693 /* pid */
1694 case 'p':
1695 pid_in_pattern = 1;
1696 err = cn_printf(cn, "%d",
1697 task_tgid_vnr(current));
1698 break;
1699 /* uid */
1700 case 'u':
1701 err = cn_printf(cn, "%d", cred->uid);
1702 break;
1703 /* gid */
1704 case 'g':
1705 err = cn_printf(cn, "%d", cred->gid);
1706 break;
1707 /* signal that caused the coredump */
1708 case 's':
1709 err = cn_printf(cn, "%ld", signr);
1710 break;
1711 /* UNIX time of coredump */
1712 case 't': {
1713 struct timeval tv;
1714 do_gettimeofday(&tv);
1715 err = cn_printf(cn, "%lu", tv.tv_sec);
1716 break;
1717 }
1718 /* hostname */
1719 case 'h':
1720 down_read(&uts_sem);
1721 err = cn_printf(cn, "%s",
1722 utsname()->nodename);
1723 up_read(&uts_sem);
1724 break;
1725 /* executable */
1726 case 'e':
1727 err = cn_printf(cn, "%s", current->comm);
1728 break;
1729 case 'E':
1730 err = cn_print_exe_file(cn);
1731 break;
1732 /* core limit size */
1733 case 'c':
1734 err = cn_printf(cn, "%lu",
1735 rlimit(RLIMIT_CORE));
1736 break;
1737 default:
1738 break;
1739 }
1740 ++pat_ptr;
1741 }
1742
1743 if (err)
1744 return err;
1745 }
1746
1747 /* Backward compatibility with core_uses_pid:
1748 *
1749 * If core_pattern does not include a %p (as is the default)
1750 * and core_uses_pid is set, then .%pid will be appended to
1751 * the filename. Do not do this for piped commands. */
1752 if (!ispipe && !pid_in_pattern && core_uses_pid) {
1753 err = cn_printf(cn, ".%d", task_tgid_vnr(current));
1754 if (err)
1755 return err;
1756 }
1757out:
1758 return ispipe;
1759}
1760
1761static int zap_process(struct task_struct *start, int exit_code)
1762{
1763 struct task_struct *t;
1764 int nr = 0;
1765
1766 start->signal->flags = SIGNAL_GROUP_EXIT;
1767 start->signal->group_exit_code = exit_code;
1768 start->signal->group_stop_count = 0;
1769
1770 t = start;
1771 do {
1772 task_clear_group_stop_pending(t);
1773 if (t != current && t->mm) {
1774 sigaddset(&t->pending.signal, SIGKILL);
1775 signal_wake_up(t, 1);
1776 nr++;
1777 }
1778 } while_each_thread(start, t);
1779
1780 return nr;
1781}
1782
1783static inline int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
1784 struct core_state *core_state, int exit_code)
1785{
1786 struct task_struct *g, *p;
1787 unsigned long flags;
1788 int nr = -EAGAIN;
1789
1790 spin_lock_irq(&tsk->sighand->siglock);
1791 if (!signal_group_exit(tsk->signal)) {
1792 mm->core_state = core_state;
1793 nr = zap_process(tsk, exit_code);
1794 }
1795 spin_unlock_irq(&tsk->sighand->siglock);
1796 if (unlikely(nr < 0))
1797 return nr;
1798
1799 if (atomic_read(&mm->mm_users) == nr + 1)
1800 goto done;
1801 /*
1802 * We should find and kill all tasks which use this mm, and we should
1803 * count them correctly into ->nr_threads. We don't take tasklist
1804 * lock, but this is safe wrt:
1805 *
1806 * fork:
1807 * None of sub-threads can fork after zap_process(leader). All
1808 * processes which were created before this point should be
1809 * visible to zap_threads() because copy_process() adds the new
1810 * process to the tail of init_task.tasks list, and lock/unlock
1811 * of ->siglock provides a memory barrier.
1812 *
1813 * do_exit:
1814 * The caller holds mm->mmap_sem. This means that the task which
1815 * uses this mm can't pass exit_mm(), so it can't exit or clear
1816 * its ->mm.
1817 *
1818 * de_thread:
1819 * It does list_replace_rcu(&leader->tasks, &current->tasks),
1820 * we must see either old or new leader, this does not matter.
1821 * However, it can change p->sighand, so lock_task_sighand(p)
1822 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1823 * it can't fail.
1824 *
1825 * Note also that "g" can be the old leader with ->mm == NULL
1826 * and already unhashed and thus removed from ->thread_group.
1827 * This is OK, __unhash_process()->list_del_rcu() does not
1828 * clear the ->next pointer, we will find the new leader via
1829 * next_thread().
1830 */
1831 rcu_read_lock();
1832 for_each_process(g) {
1833 if (g == tsk->group_leader)
1834 continue;
1835 if (g->flags & PF_KTHREAD)
1836 continue;
1837 p = g;
1838 do {
1839 if (p->mm) {
1840 if (unlikely(p->mm == mm)) {
1841 lock_task_sighand(p, &flags);
1842 nr += zap_process(p, exit_code);
1843 unlock_task_sighand(p, &flags);
1844 }
1845 break;
1846 }
1847 } while_each_thread(g, p);
1848 }
1849 rcu_read_unlock();
1850done:
1851 atomic_set(&core_state->nr_threads, nr);
1852 return nr;
1853}
1854
1855static int coredump_wait(int exit_code, struct core_state *core_state)
1856{
1857 struct task_struct *tsk = current;
1858 struct mm_struct *mm = tsk->mm;
1859 struct completion *vfork_done;
1860 int core_waiters = -EBUSY;
1861
1862 init_completion(&core_state->startup);
1863 core_state->dumper.task = tsk;
1864 core_state->dumper.next = NULL;
1865
1866 down_write(&mm->mmap_sem);
1867 if (!mm->core_state)
1868 core_waiters = zap_threads(tsk, mm, core_state, exit_code);
1869 up_write(&mm->mmap_sem);
1870
1871 if (unlikely(core_waiters < 0))
1872 goto fail;
1873
1874 /*
1875 * Make sure nobody is waiting for us to release the VM,
1876 * otherwise we can deadlock when we wait on each other
1877 */
1878 vfork_done = tsk->vfork_done;
1879 if (vfork_done) {
1880 tsk->vfork_done = NULL;
1881 complete(vfork_done);
1882 }
1883
1884 if (core_waiters)
1885 wait_for_completion(&core_state->startup);
1886fail:
1887 return core_waiters;
1888}
1889
1890static void coredump_finish(struct mm_struct *mm)
1891{
1892 struct core_thread *curr, *next;
1893 struct task_struct *task;
1894
1895 next = mm->core_state->dumper.next;
1896 while ((curr = next) != NULL) {
1897 next = curr->next;
1898 task = curr->task;
1899 /*
1900 * see exit_mm(), curr->task must not see
1901 * ->task == NULL before we read ->next.
1902 */
1903 smp_mb();
1904 curr->task = NULL;
1905 wake_up_process(task);
1906 }
1907
1908 mm->core_state = NULL;
1909}
1910
1911/*
1912 * set_dumpable converts traditional three-value dumpable to two flags and
1913 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1914 * these bits are not changed atomically. So get_dumpable can observe the
1915 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1916 * return either old dumpable or new one by paying attention to the order of
1917 * modifying the bits.
1918 *
1919 * dumpable | mm->flags (binary)
1920 * old new | initial interim final
1921 * ---------+-----------------------
1922 * 0 1 | 00 01 01
1923 * 0 2 | 00 10(*) 11
1924 * 1 0 | 01 00 00
1925 * 1 2 | 01 11 11
1926 * 2 0 | 11 10(*) 00
1927 * 2 1 | 11 11 01
1928 *
1929 * (*) get_dumpable regards interim value of 10 as 11.
1930 */
1931void set_dumpable(struct mm_struct *mm, int value)
1932{
1933 switch (value) {
1934 case 0:
1935 clear_bit(MMF_DUMPABLE, &mm->flags);
1936 smp_wmb();
1937 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1938 break;
1939 case 1:
1940 set_bit(MMF_DUMPABLE, &mm->flags);
1941 smp_wmb();
1942 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1943 break;
1944 case 2:
1945 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1946 smp_wmb();
1947 set_bit(MMF_DUMPABLE, &mm->flags);
1948 break;
1949 }
1950}
1951
1952static int __get_dumpable(unsigned long mm_flags)
1953{
1954 int ret;
1955
1956 ret = mm_flags & MMF_DUMPABLE_MASK;
1957 return (ret >= 2) ? 2 : ret;
1958}
1959
1960int get_dumpable(struct mm_struct *mm)
1961{
1962 return __get_dumpable(mm->flags);
1963}
1964
1965static void wait_for_dump_helpers(struct file *file)
1966{
1967 struct pipe_inode_info *pipe;
1968
1969 pipe = file->f_path.dentry->d_inode->i_pipe;
1970
1971 pipe_lock(pipe);
1972 pipe->readers++;
1973 pipe->writers--;
1974
1975 while ((pipe->readers > 1) && (!signal_pending(current))) {
1976 wake_up_interruptible_sync(&pipe->wait);
1977 kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
1978 pipe_wait(pipe);
1979 }
1980
1981 pipe->readers--;
1982 pipe->writers++;
1983 pipe_unlock(pipe);
1984
1985}
1986
1987
1988/*
1989 * umh_pipe_setup
1990 * helper function to customize the process used
1991 * to collect the core in userspace. Specifically
1992 * it sets up a pipe and installs it as fd 0 (stdin)
1993 * for the process. Returns 0 on success, or
1994 * PTR_ERR on failure.
1995 * Note that it also sets the core limit to 1. This
1996 * is a special value that we use to trap recursive
1997 * core dumps
1998 */
1999static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
2000{
2001 struct file *rp, *wp;
2002 struct fdtable *fdt;
2003 struct coredump_params *cp = (struct coredump_params *)info->data;
2004 struct files_struct *cf = current->files;
2005
2006 wp = create_write_pipe(0);
2007 if (IS_ERR(wp))
2008 return PTR_ERR(wp);
2009
2010 rp = create_read_pipe(wp, 0);
2011 if (IS_ERR(rp)) {
2012 free_write_pipe(wp);
2013 return PTR_ERR(rp);
2014 }
2015
2016 cp->file = wp;
2017
2018 sys_close(0);
2019 fd_install(0, rp);
2020 spin_lock(&cf->file_lock);
2021 fdt = files_fdtable(cf);
2022 FD_SET(0, fdt->open_fds);
2023 FD_CLR(0, fdt->close_on_exec);
2024 spin_unlock(&cf->file_lock);
2025
2026 /* and disallow core files too */
2027 current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
2028
2029 return 0;
2030}
2031
2032void do_coredump(long signr, int exit_code, struct pt_regs *regs)
2033{
2034 struct core_state core_state;
2035 struct core_name cn;
2036 struct mm_struct *mm = current->mm;
2037 struct linux_binfmt * binfmt;
2038 const struct cred *old_cred;
2039 struct cred *cred;
2040 int retval = 0;
2041 int flag = 0;
2042 int ispipe;
2043 static atomic_t core_dump_count = ATOMIC_INIT(0);
2044 struct coredump_params cprm = {
2045 .signr = signr,
2046 .regs = regs,
2047 .limit = rlimit(RLIMIT_CORE),
2048 /*
2049 * We must use the same mm->flags while dumping core to avoid
2050 * inconsistency of bit flags, since this flag is not protected
2051 * by any locks.
2052 */
2053 .mm_flags = mm->flags,
2054 };
2055
2056 audit_core_dumps(signr);
2057
2058 binfmt = mm->binfmt;
2059 if (!binfmt || !binfmt->core_dump)
2060 goto fail;
2061 if (!__get_dumpable(cprm.mm_flags))
2062 goto fail;
2063
2064 cred = prepare_creds();
2065 if (!cred)
2066 goto fail;
2067 /*
2068 * We cannot trust fsuid as being the "true" uid of the
2069 * process nor do we know its entire history. We only know it
2070 * was tainted so we dump it as root in mode 2.
2071 */
2072 if (__get_dumpable(cprm.mm_flags) == 2) {
2073 /* Setuid core dump mode */
2074 flag = O_EXCL; /* Stop rewrite attacks */
2075 cred->fsuid = 0; /* Dump root private */
2076 }
2077
2078 retval = coredump_wait(exit_code, &core_state);
2079 if (retval < 0)
2080 goto fail_creds;
2081
2082 old_cred = override_creds(cred);
2083
2084 /*
2085 * Clear any false indication of pending signals that might
2086 * be seen by the filesystem code called to write the core file.
2087 */
2088 clear_thread_flag(TIF_SIGPENDING);
2089
2090 ispipe = format_corename(&cn, signr);
2091
2092 if (ispipe == -ENOMEM) {
2093 printk(KERN_WARNING "format_corename failed\n");
2094 printk(KERN_WARNING "Aborting core\n");
2095 goto fail_corename;
2096 }
2097
2098 if (ispipe) {
2099 int dump_count;
2100 char **helper_argv;
2101
2102 if (cprm.limit == 1) {
2103 /*
2104 * Normally core limits are irrelevant to pipes, since
2105 * we're not writing to the file system, but we use
2106 * cprm.limit of 1 here as a speacial value. Any
2107 * non-1 limit gets set to RLIM_INFINITY below, but
2108 * a limit of 0 skips the dump. This is a consistent
2109 * way to catch recursive crashes. We can still crash
2110 * if the core_pattern binary sets RLIM_CORE = !1
2111 * but it runs as root, and can do lots of stupid things
2112 * Note that we use task_tgid_vnr here to grab the pid
2113 * of the process group leader. That way we get the
2114 * right pid if a thread in a multi-threaded
2115 * core_pattern process dies.
2116 */
2117 printk(KERN_WARNING
2118 "Process %d(%s) has RLIMIT_CORE set to 1\n",
2119 task_tgid_vnr(current), current->comm);
2120 printk(KERN_WARNING "Aborting core\n");
2121 goto fail_unlock;
2122 }
2123 cprm.limit = RLIM_INFINITY;
2124
2125 dump_count = atomic_inc_return(&core_dump_count);
2126 if (core_pipe_limit && (core_pipe_limit < dump_count)) {
2127 printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
2128 task_tgid_vnr(current), current->comm);
2129 printk(KERN_WARNING "Skipping core dump\n");
2130 goto fail_dropcount;
2131 }
2132
2133 helper_argv = argv_split(GFP_KERNEL, cn.corename+1, NULL);
2134 if (!helper_argv) {
2135 printk(KERN_WARNING "%s failed to allocate memory\n",
2136 __func__);
2137 goto fail_dropcount;
2138 }
2139
2140 retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
2141 NULL, UMH_WAIT_EXEC, umh_pipe_setup,
2142 NULL, &cprm);
2143 argv_free(helper_argv);
2144 if (retval) {
2145 printk(KERN_INFO "Core dump to %s pipe failed\n",
2146 cn.corename);
2147 goto close_fail;
2148 }
2149 } else {
2150 struct inode *inode;
2151
2152 if (cprm.limit < binfmt->min_coredump)
2153 goto fail_unlock;
2154
2155 cprm.file = filp_open(cn.corename,
2156 O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
2157 0600);
2158 if (IS_ERR(cprm.file))
2159 goto fail_unlock;
2160
2161 inode = cprm.file->f_path.dentry->d_inode;
2162 if (inode->i_nlink > 1)
2163 goto close_fail;
2164 if (d_unhashed(cprm.file->f_path.dentry))
2165 goto close_fail;
2166 /*
2167 * AK: actually i see no reason to not allow this for named
2168 * pipes etc, but keep the previous behaviour for now.
2169 */
2170 if (!S_ISREG(inode->i_mode))
2171 goto close_fail;
2172 /*
2173 * Dont allow local users get cute and trick others to coredump
2174 * into their pre-created files.
2175 */
2176 if (inode->i_uid != current_fsuid())
2177 goto close_fail;
2178 if (!cprm.file->f_op || !cprm.file->f_op->write)
2179 goto close_fail;
2180 if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
2181 goto close_fail;
2182 }
2183
2184 retval = binfmt->core_dump(&cprm);
2185 if (retval)
2186 current->signal->group_exit_code |= 0x80;
2187
2188 if (ispipe && core_pipe_limit)
2189 wait_for_dump_helpers(cprm.file);
2190close_fail:
2191 if (cprm.file)
2192 filp_close(cprm.file, NULL);
2193fail_dropcount:
2194 if (ispipe)
2195 atomic_dec(&core_dump_count);
2196fail_unlock:
2197 kfree(cn.corename);
2198fail_corename:
2199 coredump_finish(mm);
2200 revert_creds(old_cred);
2201fail_creds:
2202 put_cred(cred);
2203fail:
2204 return;
2205}
2206
2207/*
2208 * Core dumping helper functions. These are the only things you should
2209 * do on a core-file: use only these functions to write out all the
2210 * necessary info.
2211 */
2212int dump_write(struct file *file, const void *addr, int nr)
2213{
2214 return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
2215}
2216EXPORT_SYMBOL(dump_write);
2217
2218int dump_seek(struct file *file, loff_t off)
2219{
2220 int ret = 1;
2221
2222 if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
2223 if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
2224 return 0;
2225 } else {
2226 char *buf = (char *)get_zeroed_page(GFP_KERNEL);
2227
2228 if (!buf)
2229 return 0;
2230 while (off > 0) {
2231 unsigned long n = off;
2232
2233 if (n > PAGE_SIZE)
2234 n = PAGE_SIZE;
2235 if (!dump_write(file, buf, n)) {
2236 ret = 0;
2237 break;
2238 }
2239 off -= n;
2240 }
2241 free_page((unsigned long)buf);
2242 }
2243 return ret;
2244}
2245EXPORT_SYMBOL(dump_seek);