projects/linux·blob v3.13-rc5 · refs

1701 lines · 39.3 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
63#include <trace/events/task.h>
64#include "internal.h"
65#include "coredump.h"
66
67#include <trace/events/sched.h>
68
69int suid_dumpable = 0;
70
71static LIST_HEAD(formats);
72static DEFINE_RWLOCK(binfmt_lock);
73
74void __register_binfmt(struct linux_binfmt * fmt, int insert)
75{
76 BUG_ON(!fmt);
77 if (WARN_ON(!fmt->load_binary))
78 return;
79 write_lock(&binfmt_lock);
80 insert ? list_add(&fmt->lh, &formats) :
81 list_add_tail(&fmt->lh, &formats);
82 write_unlock(&binfmt_lock);
83}
84
85EXPORT_SYMBOL(__register_binfmt);
86
87void unregister_binfmt(struct linux_binfmt * fmt)
88{
89 write_lock(&binfmt_lock);
90 list_del(&fmt->lh);
91 write_unlock(&binfmt_lock);
92}
93
94EXPORT_SYMBOL(unregister_binfmt);
95
96static inline void put_binfmt(struct linux_binfmt * fmt)
97{
98 module_put(fmt->module);
99}
100
101/*
102 * Note that a shared library must be both readable and executable due to
103 * security reasons.
104 *
105 * Also note that we take the address to load from from the file itself.
106 */
107SYSCALL_DEFINE1(uselib, const char __user *, library)
108{
109 struct linux_binfmt *fmt;
110 struct file *file;
111 struct filename *tmp = getname(library);
112 int error = PTR_ERR(tmp);
113 static const struct open_flags uselib_flags = {
114 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
115 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
116 .intent = LOOKUP_OPEN,
117 .lookup_flags = LOOKUP_FOLLOW,
118 };
119
120 if (IS_ERR(tmp))
121 goto out;
122
123 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
124 putname(tmp);
125 error = PTR_ERR(file);
126 if (IS_ERR(file))
127 goto out;
128
129 error = -EINVAL;
130 if (!S_ISREG(file_inode(file)->i_mode))
131 goto exit;
132
133 error = -EACCES;
134 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
135 goto exit;
136
137 fsnotify_open(file);
138
139 error = -ENOEXEC;
140
141 read_lock(&binfmt_lock);
142 list_for_each_entry(fmt, &formats, lh) {
143 if (!fmt->load_shlib)
144 continue;
145 if (!try_module_get(fmt->module))
146 continue;
147 read_unlock(&binfmt_lock);
148 error = fmt->load_shlib(file);
149 read_lock(&binfmt_lock);
150 put_binfmt(fmt);
151 if (error != -ENOEXEC)
152 break;
153 }
154 read_unlock(&binfmt_lock);
155exit:
156 fput(file);
157out:
158 return error;
159}
160
161#ifdef CONFIG_MMU
162/*
163 * The nascent bprm->mm is not visible until exec_mmap() but it can
164 * use a lot of memory, account these pages in current->mm temporary
165 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
166 * change the counter back via acct_arg_size(0).
167 */
168static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
169{
170 struct mm_struct *mm = current->mm;
171 long diff = (long)(pages - bprm->vma_pages);
172
173 if (!mm || !diff)
174 return;
175
176 bprm->vma_pages = pages;
177 add_mm_counter(mm, MM_ANONPAGES, diff);
178}
179
180static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
181 int write)
182{
183 struct page *page;
184 int ret;
185
186#ifdef CONFIG_STACK_GROWSUP
187 if (write) {
188 ret = expand_downwards(bprm->vma, pos);
189 if (ret < 0)
190 return NULL;
191 }
192#endif
193 ret = get_user_pages(current, bprm->mm, pos,
194 1, write, 1, &page, NULL);
195 if (ret <= 0)
196 return NULL;
197
198 if (write) {
199 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
200 struct rlimit *rlim;
201
202 acct_arg_size(bprm, size / PAGE_SIZE);
203
204 /*
205 * We've historically supported up to 32 pages (ARG_MAX)
206 * of argument strings even with small stacks
207 */
208 if (size <= ARG_MAX)
209 return page;
210
211 /*
212 * Limit to 1/4-th the stack size for the argv+env strings.
213 * This ensures that:
214 * - the remaining binfmt code will not run out of stack space,
215 * - the program will have a reasonable amount of stack left
216 * to work from.
217 */
218 rlim = current->signal->rlim;
219 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
220 put_page(page);
221 return NULL;
222 }
223 }
224
225 return page;
226}
227
228static void put_arg_page(struct page *page)
229{
230 put_page(page);
231}
232
233static void free_arg_page(struct linux_binprm *bprm, int i)
234{
235}
236
237static void free_arg_pages(struct linux_binprm *bprm)
238{
239}
240
241static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
242 struct page *page)
243{
244 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
245}
246
247static int __bprm_mm_init(struct linux_binprm *bprm)
248{
249 int err;
250 struct vm_area_struct *vma = NULL;
251 struct mm_struct *mm = bprm->mm;
252
253 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
254 if (!vma)
255 return -ENOMEM;
256
257 down_write(&mm->mmap_sem);
258 vma->vm_mm = mm;
259
260 /*
261 * Place the stack at the largest stack address the architecture
262 * supports. Later, we'll move this to an appropriate place. We don't
263 * use STACK_TOP because that can depend on attributes which aren't
264 * configured yet.
265 */
266 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
267 vma->vm_end = STACK_TOP_MAX;
268 vma->vm_start = vma->vm_end - PAGE_SIZE;
269 vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
270 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
271 INIT_LIST_HEAD(&vma->anon_vma_chain);
272
273 err = insert_vm_struct(mm, vma);
274 if (err)
275 goto err;
276
277 mm->stack_vm = mm->total_vm = 1;
278 up_write(&mm->mmap_sem);
279 bprm->p = vma->vm_end - sizeof(void *);
280 return 0;
281err:
282 up_write(&mm->mmap_sem);
283 bprm->vma = NULL;
284 kmem_cache_free(vm_area_cachep, vma);
285 return err;
286}
287
288static bool valid_arg_len(struct linux_binprm *bprm, long len)
289{
290 return len <= MAX_ARG_STRLEN;
291}
292
293#else
294
295static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
296{
297}
298
299static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
300 int write)
301{
302 struct page *page;
303
304 page = bprm->page[pos / PAGE_SIZE];
305 if (!page && write) {
306 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
307 if (!page)
308 return NULL;
309 bprm->page[pos / PAGE_SIZE] = page;
310 }
311
312 return page;
313}
314
315static void put_arg_page(struct page *page)
316{
317}
318
319static void free_arg_page(struct linux_binprm *bprm, int i)
320{
321 if (bprm->page[i]) {
322 __free_page(bprm->page[i]);
323 bprm->page[i] = NULL;
324 }
325}
326
327static void free_arg_pages(struct linux_binprm *bprm)
328{
329 int i;
330
331 for (i = 0; i < MAX_ARG_PAGES; i++)
332 free_arg_page(bprm, i);
333}
334
335static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
336 struct page *page)
337{
338}
339
340static int __bprm_mm_init(struct linux_binprm *bprm)
341{
342 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
343 return 0;
344}
345
346static bool valid_arg_len(struct linux_binprm *bprm, long len)
347{
348 return len <= bprm->p;
349}
350
351#endif /* CONFIG_MMU */
352
353/*
354 * Create a new mm_struct and populate it with a temporary stack
355 * vm_area_struct. We don't have enough context at this point to set the stack
356 * flags, permissions, and offset, so we use temporary values. We'll update
357 * them later in setup_arg_pages().
358 */
359static int bprm_mm_init(struct linux_binprm *bprm)
360{
361 int err;
362 struct mm_struct *mm = NULL;
363
364 bprm->mm = mm = mm_alloc();
365 err = -ENOMEM;
366 if (!mm)
367 goto err;
368
369 err = init_new_context(current, mm);
370 if (err)
371 goto err;
372
373 err = __bprm_mm_init(bprm);
374 if (err)
375 goto err;
376
377 return 0;
378
379err:
380 if (mm) {
381 bprm->mm = NULL;
382 mmdrop(mm);
383 }
384
385 return err;
386}
387
388struct user_arg_ptr {
389#ifdef CONFIG_COMPAT
390 bool is_compat;
391#endif
392 union {
393 const char __user *const __user *native;
394#ifdef CONFIG_COMPAT
395 const compat_uptr_t __user *compat;
396#endif
397 } ptr;
398};
399
400static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
401{
402 const char __user *native;
403
404#ifdef CONFIG_COMPAT
405 if (unlikely(argv.is_compat)) {
406 compat_uptr_t compat;
407
408 if (get_user(compat, argv.ptr.compat + nr))
409 return ERR_PTR(-EFAULT);
410
411 return compat_ptr(compat);
412 }
413#endif
414
415 if (get_user(native, argv.ptr.native + nr))
416 return ERR_PTR(-EFAULT);
417
418 return native;
419}
420
421/*
422 * count() counts the number of strings in array ARGV.
423 */
424static int count(struct user_arg_ptr argv, int max)
425{
426 int i = 0;
427
428 if (argv.ptr.native != NULL) {
429 for (;;) {
430 const char __user *p = get_user_arg_ptr(argv, i);
431
432 if (!p)
433 break;
434
435 if (IS_ERR(p))
436 return -EFAULT;
437
438 if (i >= max)
439 return -E2BIG;
440 ++i;
441
442 if (fatal_signal_pending(current))
443 return -ERESTARTNOHAND;
444 cond_resched();
445 }
446 }
447 return i;
448}
449
450/*
451 * 'copy_strings()' copies argument/environment strings from the old
452 * processes's memory to the new process's stack. The call to get_user_pages()
453 * ensures the destination page is created and not swapped out.
454 */
455static int copy_strings(int argc, struct user_arg_ptr argv,
456 struct linux_binprm *bprm)
457{
458 struct page *kmapped_page = NULL;
459 char *kaddr = NULL;
460 unsigned long kpos = 0;
461 int ret;
462
463 while (argc-- > 0) {
464 const char __user *str;
465 int len;
466 unsigned long pos;
467
468 ret = -EFAULT;
469 str = get_user_arg_ptr(argv, argc);
470 if (IS_ERR(str))
471 goto out;
472
473 len = strnlen_user(str, MAX_ARG_STRLEN);
474 if (!len)
475 goto out;
476
477 ret = -E2BIG;
478 if (!valid_arg_len(bprm, len))
479 goto out;
480
481 /* We're going to work our way backwords. */
482 pos = bprm->p;
483 str += len;
484 bprm->p -= len;
485
486 while (len > 0) {
487 int offset, bytes_to_copy;
488
489 if (fatal_signal_pending(current)) {
490 ret = -ERESTARTNOHAND;
491 goto out;
492 }
493 cond_resched();
494
495 offset = pos % PAGE_SIZE;
496 if (offset == 0)
497 offset = PAGE_SIZE;
498
499 bytes_to_copy = offset;
500 if (bytes_to_copy > len)
501 bytes_to_copy = len;
502
503 offset -= bytes_to_copy;
504 pos -= bytes_to_copy;
505 str -= bytes_to_copy;
506 len -= bytes_to_copy;
507
508 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
509 struct page *page;
510
511 page = get_arg_page(bprm, pos, 1);
512 if (!page) {
513 ret = -E2BIG;
514 goto out;
515 }
516
517 if (kmapped_page) {
518 flush_kernel_dcache_page(kmapped_page);
519 kunmap(kmapped_page);
520 put_arg_page(kmapped_page);
521 }
522 kmapped_page = page;
523 kaddr = kmap(kmapped_page);
524 kpos = pos & PAGE_MASK;
525 flush_arg_page(bprm, kpos, kmapped_page);
526 }
527 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
528 ret = -EFAULT;
529 goto out;
530 }
531 }
532 }
533 ret = 0;
534out:
535 if (kmapped_page) {
536 flush_kernel_dcache_page(kmapped_page);
537 kunmap(kmapped_page);
538 put_arg_page(kmapped_page);
539 }
540 return ret;
541}
542
543/*
544 * Like copy_strings, but get argv and its values from kernel memory.
545 */
546int copy_strings_kernel(int argc, const char *const *__argv,
547 struct linux_binprm *bprm)
548{
549 int r;
550 mm_segment_t oldfs = get_fs();
551 struct user_arg_ptr argv = {
552 .ptr.native = (const char __user *const __user *)__argv,
553 };
554
555 set_fs(KERNEL_DS);
556 r = copy_strings(argc, argv, bprm);
557 set_fs(oldfs);
558
559 return r;
560}
561EXPORT_SYMBOL(copy_strings_kernel);
562
563#ifdef CONFIG_MMU
564
565/*
566 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
567 * the binfmt code determines where the new stack should reside, we shift it to
568 * its final location. The process proceeds as follows:
569 *
570 * 1) Use shift to calculate the new vma endpoints.
571 * 2) Extend vma to cover both the old and new ranges. This ensures the
572 * arguments passed to subsequent functions are consistent.
573 * 3) Move vma's page tables to the new range.
574 * 4) Free up any cleared pgd range.
575 * 5) Shrink the vma to cover only the new range.
576 */
577static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
578{
579 struct mm_struct *mm = vma->vm_mm;
580 unsigned long old_start = vma->vm_start;
581 unsigned long old_end = vma->vm_end;
582 unsigned long length = old_end - old_start;
583 unsigned long new_start = old_start - shift;
584 unsigned long new_end = old_end - shift;
585 struct mmu_gather tlb;
586
587 BUG_ON(new_start > new_end);
588
589 /*
590 * ensure there are no vmas between where we want to go
591 * and where we are
592 */
593 if (vma != find_vma(mm, new_start))
594 return -EFAULT;
595
596 /*
597 * cover the whole range: [new_start, old_end)
598 */
599 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
600 return -ENOMEM;
601
602 /*
603 * move the page tables downwards, on failure we rely on
604 * process cleanup to remove whatever mess we made.
605 */
606 if (length != move_page_tables(vma, old_start,
607 vma, new_start, length, false))
608 return -ENOMEM;
609
610 lru_add_drain();
611 tlb_gather_mmu(&tlb, mm, old_start, old_end);
612 if (new_end > old_start) {
613 /*
614 * when the old and new regions overlap clear from new_end.
615 */
616 free_pgd_range(&tlb, new_end, old_end, new_end,
617 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
618 } else {
619 /*
620 * otherwise, clean from old_start; this is done to not touch
621 * the address space in [new_end, old_start) some architectures
622 * have constraints on va-space that make this illegal (IA64) -
623 * for the others its just a little faster.
624 */
625 free_pgd_range(&tlb, old_start, old_end, new_end,
626 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
627 }
628 tlb_finish_mmu(&tlb, old_start, old_end);
629
630 /*
631 * Shrink the vma to just the new range. Always succeeds.
632 */
633 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
634
635 return 0;
636}
637
638/*
639 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
640 * the stack is optionally relocated, and some extra space is added.
641 */
642int setup_arg_pages(struct linux_binprm *bprm,
643 unsigned long stack_top,
644 int executable_stack)
645{
646 unsigned long ret;
647 unsigned long stack_shift;
648 struct mm_struct *mm = current->mm;
649 struct vm_area_struct *vma = bprm->vma;
650 struct vm_area_struct *prev = NULL;
651 unsigned long vm_flags;
652 unsigned long stack_base;
653 unsigned long stack_size;
654 unsigned long stack_expand;
655 unsigned long rlim_stack;
656
657#ifdef CONFIG_STACK_GROWSUP
658 /* Limit stack size to 1GB */
659 stack_base = rlimit_max(RLIMIT_STACK);
660 if (stack_base > (1 << 30))
661 stack_base = 1 << 30;
662
663 /* Make sure we didn't let the argument array grow too large. */
664 if (vma->vm_end - vma->vm_start > stack_base)
665 return -ENOMEM;
666
667 stack_base = PAGE_ALIGN(stack_top - stack_base);
668
669 stack_shift = vma->vm_start - stack_base;
670 mm->arg_start = bprm->p - stack_shift;
671 bprm->p = vma->vm_end - stack_shift;
672#else
673 stack_top = arch_align_stack(stack_top);
674 stack_top = PAGE_ALIGN(stack_top);
675
676 if (unlikely(stack_top < mmap_min_addr) ||
677 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
678 return -ENOMEM;
679
680 stack_shift = vma->vm_end - stack_top;
681
682 bprm->p -= stack_shift;
683 mm->arg_start = bprm->p;
684#endif
685
686 if (bprm->loader)
687 bprm->loader -= stack_shift;
688 bprm->exec -= stack_shift;
689
690 down_write(&mm->mmap_sem);
691 vm_flags = VM_STACK_FLAGS;
692
693 /*
694 * Adjust stack execute permissions; explicitly enable for
695 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
696 * (arch default) otherwise.
697 */
698 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
699 vm_flags |= VM_EXEC;
700 else if (executable_stack == EXSTACK_DISABLE_X)
701 vm_flags &= ~VM_EXEC;
702 vm_flags |= mm->def_flags;
703 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
704
705 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
706 vm_flags);
707 if (ret)
708 goto out_unlock;
709 BUG_ON(prev != vma);
710
711 /* Move stack pages down in memory. */
712 if (stack_shift) {
713 ret = shift_arg_pages(vma, stack_shift);
714 if (ret)
715 goto out_unlock;
716 }
717
718 /* mprotect_fixup is overkill to remove the temporary stack flags */
719 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
720
721 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
722 stack_size = vma->vm_end - vma->vm_start;
723 /*
724 * Align this down to a page boundary as expand_stack
725 * will align it up.
726 */
727 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
728#ifdef CONFIG_STACK_GROWSUP
729 if (stack_size + stack_expand > rlim_stack)
730 stack_base = vma->vm_start + rlim_stack;
731 else
732 stack_base = vma->vm_end + stack_expand;
733#else
734 if (stack_size + stack_expand > rlim_stack)
735 stack_base = vma->vm_end - rlim_stack;
736 else
737 stack_base = vma->vm_start - stack_expand;
738#endif
739 current->mm->start_stack = bprm->p;
740 ret = expand_stack(vma, stack_base);
741 if (ret)
742 ret = -EFAULT;
743
744out_unlock:
745 up_write(&mm->mmap_sem);
746 return ret;
747}
748EXPORT_SYMBOL(setup_arg_pages);
749
750#endif /* CONFIG_MMU */
751
752struct file *open_exec(const char *name)
753{
754 struct file *file;
755 int err;
756 struct filename tmp = { .name = name };
757 static const struct open_flags open_exec_flags = {
758 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
759 .acc_mode = MAY_EXEC | MAY_OPEN,
760 .intent = LOOKUP_OPEN,
761 .lookup_flags = LOOKUP_FOLLOW,
762 };
763
764 file = do_filp_open(AT_FDCWD, &tmp, &open_exec_flags);
765 if (IS_ERR(file))
766 goto out;
767
768 err = -EACCES;
769 if (!S_ISREG(file_inode(file)->i_mode))
770 goto exit;
771
772 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
773 goto exit;
774
775 fsnotify_open(file);
776
777 err = deny_write_access(file);
778 if (err)
779 goto exit;
780
781out:
782 return file;
783
784exit:
785 fput(file);
786 return ERR_PTR(err);
787}
788EXPORT_SYMBOL(open_exec);
789
790int kernel_read(struct file *file, loff_t offset,
791 char *addr, unsigned long count)
792{
793 mm_segment_t old_fs;
794 loff_t pos = offset;
795 int result;
796
797 old_fs = get_fs();
798 set_fs(get_ds());
799 /* The cast to a user pointer is valid due to the set_fs() */
800 result = vfs_read(file, (void __user *)addr, count, &pos);
801 set_fs(old_fs);
802 return result;
803}
804
805EXPORT_SYMBOL(kernel_read);
806
807ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
808{
809 ssize_t res = file->f_op->read(file, (void __user *)addr, len, &pos);
810 if (res > 0)
811 flush_icache_range(addr, addr + len);
812 return res;
813}
814EXPORT_SYMBOL(read_code);
815
816static int exec_mmap(struct mm_struct *mm)
817{
818 struct task_struct *tsk;
819 struct mm_struct * old_mm, *active_mm;
820
821 /* Notify parent that we're no longer interested in the old VM */
822 tsk = current;
823 old_mm = current->mm;
824 mm_release(tsk, old_mm);
825
826 if (old_mm) {
827 sync_mm_rss(old_mm);
828 /*
829 * Make sure that if there is a core dump in progress
830 * for the old mm, we get out and die instead of going
831 * through with the exec. We must hold mmap_sem around
832 * checking core_state and changing tsk->mm.
833 */
834 down_read(&old_mm->mmap_sem);
835 if (unlikely(old_mm->core_state)) {
836 up_read(&old_mm->mmap_sem);
837 return -EINTR;
838 }
839 }
840 task_lock(tsk);
841 active_mm = tsk->active_mm;
842 tsk->mm = mm;
843 tsk->active_mm = mm;
844 activate_mm(active_mm, mm);
845 task_unlock(tsk);
846 arch_pick_mmap_layout(mm);
847 if (old_mm) {
848 up_read(&old_mm->mmap_sem);
849 BUG_ON(active_mm != old_mm);
850 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
851 mm_update_next_owner(old_mm);
852 mmput(old_mm);
853 return 0;
854 }
855 mmdrop(active_mm);
856 return 0;
857}
858
859/*
860 * This function makes sure the current process has its own signal table,
861 * so that flush_signal_handlers can later reset the handlers without
862 * disturbing other processes. (Other processes might share the signal
863 * table via the CLONE_SIGHAND option to clone().)
864 */
865static int de_thread(struct task_struct *tsk)
866{
867 struct signal_struct *sig = tsk->signal;
868 struct sighand_struct *oldsighand = tsk->sighand;
869 spinlock_t *lock = &oldsighand->siglock;
870
871 if (thread_group_empty(tsk))
872 goto no_thread_group;
873
874 /*
875 * Kill all other threads in the thread group.
876 */
877 spin_lock_irq(lock);
878 if (signal_group_exit(sig)) {
879 /*
880 * Another group action in progress, just
881 * return so that the signal is processed.
882 */
883 spin_unlock_irq(lock);
884 return -EAGAIN;
885 }
886
887 sig->group_exit_task = tsk;
888 sig->notify_count = zap_other_threads(tsk);
889 if (!thread_group_leader(tsk))
890 sig->notify_count--;
891
892 while (sig->notify_count) {
893 __set_current_state(TASK_KILLABLE);
894 spin_unlock_irq(lock);
895 schedule();
896 if (unlikely(__fatal_signal_pending(tsk)))
897 goto killed;
898 spin_lock_irq(lock);
899 }
900 spin_unlock_irq(lock);
901
902 /*
903 * At this point all other threads have exited, all we have to
904 * do is to wait for the thread group leader to become inactive,
905 * and to assume its PID:
906 */
907 if (!thread_group_leader(tsk)) {
908 struct task_struct *leader = tsk->group_leader;
909
910 sig->notify_count = -1; /* for exit_notify() */
911 for (;;) {
912 threadgroup_change_begin(tsk);
913 write_lock_irq(&tasklist_lock);
914 if (likely(leader->exit_state))
915 break;
916 __set_current_state(TASK_KILLABLE);
917 write_unlock_irq(&tasklist_lock);
918 threadgroup_change_end(tsk);
919 schedule();
920 if (unlikely(__fatal_signal_pending(tsk)))
921 goto killed;
922 }
923
924 /*
925 * The only record we have of the real-time age of a
926 * process, regardless of execs it's done, is start_time.
927 * All the past CPU time is accumulated in signal_struct
928 * from sister threads now dead. But in this non-leader
929 * exec, nothing survives from the original leader thread,
930 * whose birth marks the true age of this process now.
931 * When we take on its identity by switching to its PID, we
932 * also take its birthdate (always earlier than our own).
933 */
934 tsk->start_time = leader->start_time;
935 tsk->real_start_time = leader->real_start_time;
936
937 BUG_ON(!same_thread_group(leader, tsk));
938 BUG_ON(has_group_leader_pid(tsk));
939 /*
940 * An exec() starts a new thread group with the
941 * TGID of the previous thread group. Rehash the
942 * two threads with a switched PID, and release
943 * the former thread group leader:
944 */
945
946 /* Become a process group leader with the old leader's pid.
947 * The old leader becomes a thread of the this thread group.
948 * Note: The old leader also uses this pid until release_task
949 * is called. Odd but simple and correct.
950 */
951 tsk->pid = leader->pid;
952 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
953 transfer_pid(leader, tsk, PIDTYPE_PGID);
954 transfer_pid(leader, tsk, PIDTYPE_SID);
955
956 list_replace_rcu(&leader->tasks, &tsk->tasks);
957 list_replace_init(&leader->sibling, &tsk->sibling);
958
959 tsk->group_leader = tsk;
960 leader->group_leader = tsk;
961
962 tsk->exit_signal = SIGCHLD;
963 leader->exit_signal = -1;
964
965 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
966 leader->exit_state = EXIT_DEAD;
967
968 /*
969 * We are going to release_task()->ptrace_unlink() silently,
970 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
971 * the tracer wont't block again waiting for this thread.
972 */
973 if (unlikely(leader->ptrace))
974 __wake_up_parent(leader, leader->parent);
975 write_unlock_irq(&tasklist_lock);
976 threadgroup_change_end(tsk);
977
978 release_task(leader);
979 }
980
981 sig->group_exit_task = NULL;
982 sig->notify_count = 0;
983
984no_thread_group:
985 /* we have changed execution domain */
986 tsk->exit_signal = SIGCHLD;
987
988 exit_itimers(sig);
989 flush_itimer_signals();
990
991 if (atomic_read(&oldsighand->count) != 1) {
992 struct sighand_struct *newsighand;
993 /*
994 * This ->sighand is shared with the CLONE_SIGHAND
995 * but not CLONE_THREAD task, switch to the new one.
996 */
997 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
998 if (!newsighand)
999 return -ENOMEM;
1000
1001 atomic_set(&newsighand->count, 1);
1002 memcpy(newsighand->action, oldsighand->action,
1003 sizeof(newsighand->action));
1004
1005 write_lock_irq(&tasklist_lock);
1006 spin_lock(&oldsighand->siglock);
1007 rcu_assign_pointer(tsk->sighand, newsighand);
1008 spin_unlock(&oldsighand->siglock);
1009 write_unlock_irq(&tasklist_lock);
1010
1011 __cleanup_sighand(oldsighand);
1012 }
1013
1014 BUG_ON(!thread_group_leader(tsk));
1015 return 0;
1016
1017killed:
1018 /* protects against exit_notify() and __exit_signal() */
1019 read_lock(&tasklist_lock);
1020 sig->group_exit_task = NULL;
1021 sig->notify_count = 0;
1022 read_unlock(&tasklist_lock);
1023 return -EAGAIN;
1024}
1025
1026char *get_task_comm(char *buf, struct task_struct *tsk)
1027{
1028 /* buf must be at least sizeof(tsk->comm) in size */
1029 task_lock(tsk);
1030 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1031 task_unlock(tsk);
1032 return buf;
1033}
1034EXPORT_SYMBOL_GPL(get_task_comm);
1035
1036/*
1037 * These functions flushes out all traces of the currently running executable
1038 * so that a new one can be started
1039 */
1040
1041void set_task_comm(struct task_struct *tsk, char *buf)
1042{
1043 task_lock(tsk);
1044 trace_task_rename(tsk, buf);
1045 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1046 task_unlock(tsk);
1047 perf_event_comm(tsk);
1048}
1049
1050static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len)
1051{
1052 int i, ch;
1053
1054 /* Copies the binary name from after last slash */
1055 for (i = 0; (ch = *(fn++)) != '\0';) {
1056 if (ch == '/')
1057 i = 0; /* overwrite what we wrote */
1058 else
1059 if (i < len - 1)
1060 tcomm[i++] = ch;
1061 }
1062 tcomm[i] = '\0';
1063}
1064
1065int flush_old_exec(struct linux_binprm * bprm)
1066{
1067 int retval;
1068
1069 /*
1070 * Make sure we have a private signal table and that
1071 * we are unassociated from the previous thread group.
1072 */
1073 retval = de_thread(current);
1074 if (retval)
1075 goto out;
1076
1077 set_mm_exe_file(bprm->mm, bprm->file);
1078
1079 filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm));
1080 /*
1081 * Release all of the old mmap stuff
1082 */
1083 acct_arg_size(bprm, 0);
1084 retval = exec_mmap(bprm->mm);
1085 if (retval)
1086 goto out;
1087
1088 bprm->mm = NULL; /* We're using it now */
1089
1090 set_fs(USER_DS);
1091 current->flags &=
1092 ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD | PF_NOFREEZE);
1093 flush_thread();
1094 current->personality &= ~bprm->per_clear;
1095
1096 return 0;
1097
1098out:
1099 return retval;
1100}
1101EXPORT_SYMBOL(flush_old_exec);
1102
1103void would_dump(struct linux_binprm *bprm, struct file *file)
1104{
1105 if (inode_permission(file_inode(file), MAY_READ) < 0)
1106 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1107}
1108EXPORT_SYMBOL(would_dump);
1109
1110void setup_new_exec(struct linux_binprm * bprm)
1111{
1112 arch_pick_mmap_layout(current->mm);
1113
1114 /* This is the point of no return */
1115 current->sas_ss_sp = current->sas_ss_size = 0;
1116
1117 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1118 set_dumpable(current->mm, SUID_DUMP_USER);
1119 else
1120 set_dumpable(current->mm, suid_dumpable);
1121
1122 set_task_comm(current, bprm->tcomm);
1123
1124 /* Set the new mm task size. We have to do that late because it may
1125 * depend on TIF_32BIT which is only updated in flush_thread() on
1126 * some architectures like powerpc
1127 */
1128 current->mm->task_size = TASK_SIZE;
1129
1130 /* install the new credentials */
1131 if (!uid_eq(bprm->cred->uid, current_euid()) ||
1132 !gid_eq(bprm->cred->gid, current_egid())) {
1133 current->pdeath_signal = 0;
1134 } else {
1135 would_dump(bprm, bprm->file);
1136 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1137 set_dumpable(current->mm, suid_dumpable);
1138 }
1139
1140 /* An exec changes our domain. We are no longer part of the thread
1141 group */
1142
1143 current->self_exec_id++;
1144
1145 flush_signal_handlers(current, 0);
1146 do_close_on_exec(current->files);
1147}
1148EXPORT_SYMBOL(setup_new_exec);
1149
1150/*
1151 * Prepare credentials and lock ->cred_guard_mutex.
1152 * install_exec_creds() commits the new creds and drops the lock.
1153 * Or, if exec fails before, free_bprm() should release ->cred and
1154 * and unlock.
1155 */
1156int prepare_bprm_creds(struct linux_binprm *bprm)
1157{
1158 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1159 return -ERESTARTNOINTR;
1160
1161 bprm->cred = prepare_exec_creds();
1162 if (likely(bprm->cred))
1163 return 0;
1164
1165 mutex_unlock(&current->signal->cred_guard_mutex);
1166 return -ENOMEM;
1167}
1168
1169void free_bprm(struct linux_binprm *bprm)
1170{
1171 free_arg_pages(bprm);
1172 if (bprm->cred) {
1173 mutex_unlock(&current->signal->cred_guard_mutex);
1174 abort_creds(bprm->cred);
1175 }
1176 /* If a binfmt changed the interp, free it. */
1177 if (bprm->interp != bprm->filename)
1178 kfree(bprm->interp);
1179 kfree(bprm);
1180}
1181
1182int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1183{
1184 /* If a binfmt changed the interp, free it first. */
1185 if (bprm->interp != bprm->filename)
1186 kfree(bprm->interp);
1187 bprm->interp = kstrdup(interp, GFP_KERNEL);
1188 if (!bprm->interp)
1189 return -ENOMEM;
1190 return 0;
1191}
1192EXPORT_SYMBOL(bprm_change_interp);
1193
1194/*
1195 * install the new credentials for this executable
1196 */
1197void install_exec_creds(struct linux_binprm *bprm)
1198{
1199 security_bprm_committing_creds(bprm);
1200
1201 commit_creds(bprm->cred);
1202 bprm->cred = NULL;
1203
1204 /*
1205 * Disable monitoring for regular users
1206 * when executing setuid binaries. Must
1207 * wait until new credentials are committed
1208 * by commit_creds() above
1209 */
1210 if (get_dumpable(current->mm) != SUID_DUMP_USER)
1211 perf_event_exit_task(current);
1212 /*
1213 * cred_guard_mutex must be held at least to this point to prevent
1214 * ptrace_attach() from altering our determination of the task's
1215 * credentials; any time after this it may be unlocked.
1216 */
1217 security_bprm_committed_creds(bprm);
1218 mutex_unlock(&current->signal->cred_guard_mutex);
1219}
1220EXPORT_SYMBOL(install_exec_creds);
1221
1222/*
1223 * determine how safe it is to execute the proposed program
1224 * - the caller must hold ->cred_guard_mutex to protect against
1225 * PTRACE_ATTACH
1226 */
1227static int check_unsafe_exec(struct linux_binprm *bprm)
1228{
1229 struct task_struct *p = current, *t;
1230 unsigned n_fs;
1231 int res = 0;
1232
1233 if (p->ptrace) {
1234 if (p->ptrace & PT_PTRACE_CAP)
1235 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1236 else
1237 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1238 }
1239
1240 /*
1241 * This isn't strictly necessary, but it makes it harder for LSMs to
1242 * mess up.
1243 */
1244 if (current->no_new_privs)
1245 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1246
1247 n_fs = 1;
1248 spin_lock(&p->fs->lock);
1249 rcu_read_lock();
1250 for (t = next_thread(p); t != p; t = next_thread(t)) {
1251 if (t->fs == p->fs)
1252 n_fs++;
1253 }
1254 rcu_read_unlock();
1255
1256 if (p->fs->users > n_fs) {
1257 bprm->unsafe |= LSM_UNSAFE_SHARE;
1258 } else {
1259 res = -EAGAIN;
1260 if (!p->fs->in_exec) {
1261 p->fs->in_exec = 1;
1262 res = 1;
1263 }
1264 }
1265 spin_unlock(&p->fs->lock);
1266
1267 return res;
1268}
1269
1270/*
1271 * Fill the binprm structure from the inode.
1272 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1273 *
1274 * This may be called multiple times for binary chains (scripts for example).
1275 */
1276int prepare_binprm(struct linux_binprm *bprm)
1277{
1278 struct inode *inode = file_inode(bprm->file);
1279 umode_t mode = inode->i_mode;
1280 int retval;
1281
1282
1283 /* clear any previous set[ug]id data from a previous binary */
1284 bprm->cred->euid = current_euid();
1285 bprm->cred->egid = current_egid();
1286
1287 if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) &&
1288 !current->no_new_privs &&
1289 kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) &&
1290 kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) {
1291 /* Set-uid? */
1292 if (mode & S_ISUID) {
1293 bprm->per_clear |= PER_CLEAR_ON_SETID;
1294 bprm->cred->euid = inode->i_uid;
1295 }
1296
1297 /* Set-gid? */
1298 /*
1299 * If setgid is set but no group execute bit then this
1300 * is a candidate for mandatory locking, not a setgid
1301 * executable.
1302 */
1303 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1304 bprm->per_clear |= PER_CLEAR_ON_SETID;
1305 bprm->cred->egid = inode->i_gid;
1306 }
1307 }
1308
1309 /* fill in binprm security blob */
1310 retval = security_bprm_set_creds(bprm);
1311 if (retval)
1312 return retval;
1313 bprm->cred_prepared = 1;
1314
1315 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1316 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1317}
1318
1319EXPORT_SYMBOL(prepare_binprm);
1320
1321/*
1322 * Arguments are '\0' separated strings found at the location bprm->p
1323 * points to; chop off the first by relocating brpm->p to right after
1324 * the first '\0' encountered.
1325 */
1326int remove_arg_zero(struct linux_binprm *bprm)
1327{
1328 int ret = 0;
1329 unsigned long offset;
1330 char *kaddr;
1331 struct page *page;
1332
1333 if (!bprm->argc)
1334 return 0;
1335
1336 do {
1337 offset = bprm->p & ~PAGE_MASK;
1338 page = get_arg_page(bprm, bprm->p, 0);
1339 if (!page) {
1340 ret = -EFAULT;
1341 goto out;
1342 }
1343 kaddr = kmap_atomic(page);
1344
1345 for (; offset < PAGE_SIZE && kaddr[offset];
1346 offset++, bprm->p++)
1347 ;
1348
1349 kunmap_atomic(kaddr);
1350 put_arg_page(page);
1351
1352 if (offset == PAGE_SIZE)
1353 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1354 } while (offset == PAGE_SIZE);
1355
1356 bprm->p++;
1357 bprm->argc--;
1358 ret = 0;
1359
1360out:
1361 return ret;
1362}
1363EXPORT_SYMBOL(remove_arg_zero);
1364
1365#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1366/*
1367 * cycle the list of binary formats handler, until one recognizes the image
1368 */
1369int search_binary_handler(struct linux_binprm *bprm)
1370{
1371 bool need_retry = IS_ENABLED(CONFIG_MODULES);
1372 struct linux_binfmt *fmt;
1373 int retval;
1374
1375 /* This allows 4 levels of binfmt rewrites before failing hard. */
1376 if (bprm->recursion_depth > 5)
1377 return -ELOOP;
1378
1379 retval = security_bprm_check(bprm);
1380 if (retval)
1381 return retval;
1382
1383 retval = -ENOENT;
1384 retry:
1385 read_lock(&binfmt_lock);
1386 list_for_each_entry(fmt, &formats, lh) {
1387 if (!try_module_get(fmt->module))
1388 continue;
1389 read_unlock(&binfmt_lock);
1390 bprm->recursion_depth++;
1391 retval = fmt->load_binary(bprm);
1392 bprm->recursion_depth--;
1393 if (retval >= 0 || retval != -ENOEXEC ||
1394 bprm->mm == NULL || bprm->file == NULL) {
1395 put_binfmt(fmt);
1396 return retval;
1397 }
1398 read_lock(&binfmt_lock);
1399 put_binfmt(fmt);
1400 }
1401 read_unlock(&binfmt_lock);
1402
1403 if (need_retry && retval == -ENOEXEC) {
1404 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1405 printable(bprm->buf[2]) && printable(bprm->buf[3]))
1406 return retval;
1407 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1408 return retval;
1409 need_retry = false;
1410 goto retry;
1411 }
1412
1413 return retval;
1414}
1415EXPORT_SYMBOL(search_binary_handler);
1416
1417static int exec_binprm(struct linux_binprm *bprm)
1418{
1419 pid_t old_pid, old_vpid;
1420 int ret;
1421
1422 /* Need to fetch pid before load_binary changes it */
1423 old_pid = current->pid;
1424 rcu_read_lock();
1425 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1426 rcu_read_unlock();
1427
1428 ret = search_binary_handler(bprm);
1429 if (ret >= 0) {
1430 audit_bprm(bprm);
1431 trace_sched_process_exec(current, old_pid, bprm);
1432 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1433 current->did_exec = 1;
1434 proc_exec_connector(current);
1435
1436 if (bprm->file) {
1437 allow_write_access(bprm->file);
1438 fput(bprm->file);
1439 bprm->file = NULL; /* to catch use-after-free */
1440 }
1441 }
1442
1443 return ret;
1444}
1445
1446/*
1447 * sys_execve() executes a new program.
1448 */
1449static int do_execve_common(const char *filename,
1450 struct user_arg_ptr argv,
1451 struct user_arg_ptr envp)
1452{
1453 struct linux_binprm *bprm;
1454 struct file *file;
1455 struct files_struct *displaced;
1456 bool clear_in_exec;
1457 int retval;
1458
1459 /*
1460 * We move the actual failure in case of RLIMIT_NPROC excess from
1461 * set*uid() to execve() because too many poorly written programs
1462 * don't check setuid() return code. Here we additionally recheck
1463 * whether NPROC limit is still exceeded.
1464 */
1465 if ((current->flags & PF_NPROC_EXCEEDED) &&
1466 atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1467 retval = -EAGAIN;
1468 goto out_ret;
1469 }
1470
1471 /* We're below the limit (still or again), so we don't want to make
1472 * further execve() calls fail. */
1473 current->flags &= ~PF_NPROC_EXCEEDED;
1474
1475 retval = unshare_files(&displaced);
1476 if (retval)
1477 goto out_ret;
1478
1479 retval = -ENOMEM;
1480 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1481 if (!bprm)
1482 goto out_files;
1483
1484 retval = prepare_bprm_creds(bprm);
1485 if (retval)
1486 goto out_free;
1487
1488 retval = check_unsafe_exec(bprm);
1489 if (retval < 0)
1490 goto out_free;
1491 clear_in_exec = retval;
1492 current->in_execve = 1;
1493
1494 file = open_exec(filename);
1495 retval = PTR_ERR(file);
1496 if (IS_ERR(file))
1497 goto out_unmark;
1498
1499 sched_exec();
1500
1501 bprm->file = file;
1502 bprm->filename = filename;
1503 bprm->interp = filename;
1504
1505 retval = bprm_mm_init(bprm);
1506 if (retval)
1507 goto out_file;
1508
1509 bprm->argc = count(argv, MAX_ARG_STRINGS);
1510 if ((retval = bprm->argc) < 0)
1511 goto out;
1512
1513 bprm->envc = count(envp, MAX_ARG_STRINGS);
1514 if ((retval = bprm->envc) < 0)
1515 goto out;
1516
1517 retval = prepare_binprm(bprm);
1518 if (retval < 0)
1519 goto out;
1520
1521 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1522 if (retval < 0)
1523 goto out;
1524
1525 bprm->exec = bprm->p;
1526 retval = copy_strings(bprm->envc, envp, bprm);
1527 if (retval < 0)
1528 goto out;
1529
1530 retval = copy_strings(bprm->argc, argv, bprm);
1531 if (retval < 0)
1532 goto out;
1533
1534 retval = exec_binprm(bprm);
1535 if (retval < 0)
1536 goto out;
1537
1538 /* execve succeeded */
1539 current->fs->in_exec = 0;
1540 current->in_execve = 0;
1541 acct_update_integrals(current);
1542 task_numa_free(current);
1543 free_bprm(bprm);
1544 if (displaced)
1545 put_files_struct(displaced);
1546 return retval;
1547
1548out:
1549 if (bprm->mm) {
1550 acct_arg_size(bprm, 0);
1551 mmput(bprm->mm);
1552 }
1553
1554out_file:
1555 if (bprm->file) {
1556 allow_write_access(bprm->file);
1557 fput(bprm->file);
1558 }
1559
1560out_unmark:
1561 if (clear_in_exec)
1562 current->fs->in_exec = 0;
1563 current->in_execve = 0;
1564
1565out_free:
1566 free_bprm(bprm);
1567
1568out_files:
1569 if (displaced)
1570 reset_files_struct(displaced);
1571out_ret:
1572 return retval;
1573}
1574
1575int do_execve(const char *filename,
1576 const char __user *const __user *__argv,
1577 const char __user *const __user *__envp)
1578{
1579 struct user_arg_ptr argv = { .ptr.native = __argv };
1580 struct user_arg_ptr envp = { .ptr.native = __envp };
1581 return do_execve_common(filename, argv, envp);
1582}
1583
1584#ifdef CONFIG_COMPAT
1585static int compat_do_execve(const char *filename,
1586 const compat_uptr_t __user *__argv,
1587 const compat_uptr_t __user *__envp)
1588{
1589 struct user_arg_ptr argv = {
1590 .is_compat = true,
1591 .ptr.compat = __argv,
1592 };
1593 struct user_arg_ptr envp = {
1594 .is_compat = true,
1595 .ptr.compat = __envp,
1596 };
1597 return do_execve_common(filename, argv, envp);
1598}
1599#endif
1600
1601void set_binfmt(struct linux_binfmt *new)
1602{
1603 struct mm_struct *mm = current->mm;
1604
1605 if (mm->binfmt)
1606 module_put(mm->binfmt->module);
1607
1608 mm->binfmt = new;
1609 if (new)
1610 __module_get(new->module);
1611}
1612
1613EXPORT_SYMBOL(set_binfmt);
1614
1615/*
1616 * set_dumpable converts traditional three-value dumpable to two flags and
1617 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1618 * these bits are not changed atomically. So get_dumpable can observe the
1619 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1620 * return either old dumpable or new one by paying attention to the order of
1621 * modifying the bits.
1622 *
1623 * dumpable | mm->flags (binary)
1624 * old new | initial interim final
1625 * ---------+-----------------------
1626 * 0 1 | 00 01 01
1627 * 0 2 | 00 10(*) 11
1628 * 1 0 | 01 00 00
1629 * 1 2 | 01 11 11
1630 * 2 0 | 11 10(*) 00
1631 * 2 1 | 11 11 01
1632 *
1633 * (*) get_dumpable regards interim value of 10 as 11.
1634 */
1635void set_dumpable(struct mm_struct *mm, int value)
1636{
1637 switch (value) {
1638 case SUID_DUMP_DISABLE:
1639 clear_bit(MMF_DUMPABLE, &mm->flags);
1640 smp_wmb();
1641 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1642 break;
1643 case SUID_DUMP_USER:
1644 set_bit(MMF_DUMPABLE, &mm->flags);
1645 smp_wmb();
1646 clear_bit(MMF_DUMP_SECURELY, &mm->flags);
1647 break;
1648 case SUID_DUMP_ROOT:
1649 set_bit(MMF_DUMP_SECURELY, &mm->flags);
1650 smp_wmb();
1651 set_bit(MMF_DUMPABLE, &mm->flags);
1652 break;
1653 }
1654}
1655
1656int __get_dumpable(unsigned long mm_flags)
1657{
1658 int ret;
1659
1660 ret = mm_flags & MMF_DUMPABLE_MASK;
1661 return (ret > SUID_DUMP_USER) ? SUID_DUMP_ROOT : ret;
1662}
1663
1664/*
1665 * This returns the actual value of the suid_dumpable flag. For things
1666 * that are using this for checking for privilege transitions, it must
1667 * test against SUID_DUMP_USER rather than treating it as a boolean
1668 * value.
1669 */
1670int get_dumpable(struct mm_struct *mm)
1671{
1672 return __get_dumpable(mm->flags);
1673}
1674
1675SYSCALL_DEFINE3(execve,
1676 const char __user *, filename,
1677 const char __user *const __user *, argv,
1678 const char __user *const __user *, envp)
1679{
1680 struct filename *path = getname(filename);
1681 int error = PTR_ERR(path);
1682 if (!IS_ERR(path)) {
1683 error = do_execve(path->name, argv, envp);
1684 putname(path);
1685 }
1686 return error;
1687}
1688#ifdef CONFIG_COMPAT
1689asmlinkage long compat_sys_execve(const char __user * filename,
1690 const compat_uptr_t __user * argv,
1691 const compat_uptr_t __user * envp)
1692{
1693 struct filename *path = getname(filename);
1694 int error = PTR_ERR(path);
1695 if (!IS_ERR(path)) {
1696 error = compat_do_execve(path->name, argv, envp);
1697 putname(path);
1698 }
1699 return error;
1700}
1701#endif