xref: /openbmc/linux/fs/exec.c (revision ec5c05e5ac8bcb4a6bcd92970e15494a85400d34)
1  // SPDX-License-Identifier: GPL-2.0-only
2  /*
3   *  linux/fs/exec.c
4   *
5   *  Copyright (C) 1991, 1992  Linus Torvalds
6   */
7  
8  /*
9   * #!-checking implemented by tytso.
10   */
11  /*
12   * Demand-loading implemented 01.12.91 - no need to read anything but
13   * the header into memory. The inode of the executable is put into
14   * "current->executable", and page faults do the actual loading. Clean.
15   *
16   * Once more I can proudly say that linux stood up to being changed: it
17   * was less than 2 hours work to get demand-loading completely implemented.
18   *
19   * Demand loading changed July 1993 by Eric Youngdale.   Use mmap instead,
20   * current->executable is only used by the procfs.  This allows a dispatch
21   * table to check for several different types  of binary formats.  We keep
22   * trying until we recognize the file or we run out of supported binary
23   * formats.
24   */
25  
26  #include <linux/kernel_read_file.h>
27  #include <linux/slab.h>
28  #include <linux/file.h>
29  #include <linux/fdtable.h>
30  #include <linux/mm.h>
31  #include <linux/stat.h>
32  #include <linux/fcntl.h>
33  #include <linux/swap.h>
34  #include <linux/string.h>
35  #include <linux/init.h>
36  #include <linux/sched/mm.h>
37  #include <linux/sched/coredump.h>
38  #include <linux/sched/signal.h>
39  #include <linux/sched/numa_balancing.h>
40  #include <linux/sched/task.h>
41  #include <linux/pagemap.h>
42  #include <linux/perf_event.h>
43  #include <linux/highmem.h>
44  #include <linux/spinlock.h>
45  #include <linux/key.h>
46  #include <linux/personality.h>
47  #include <linux/binfmts.h>
48  #include <linux/utsname.h>
49  #include <linux/pid_namespace.h>
50  #include <linux/module.h>
51  #include <linux/namei.h>
52  #include <linux/mount.h>
53  #include <linux/security.h>
54  #include <linux/syscalls.h>
55  #include <linux/tsacct_kern.h>
56  #include <linux/cn_proc.h>
57  #include <linux/audit.h>
58  #include <linux/kmod.h>
59  #include <linux/fsnotify.h>
60  #include <linux/fs_struct.h>
61  #include <linux/oom.h>
62  #include <linux/compat.h>
63  #include <linux/vmalloc.h>
64  #include <linux/io_uring.h>
65  #include <linux/syscall_user_dispatch.h>
66  #include <linux/coredump.h>
67  #include <linux/time_namespace.h>
68  
69  #include <linux/uaccess.h>
70  #include <asm/mmu_context.h>
71  #include <asm/tlb.h>
72  
73  #include <trace/events/task.h>
74  #include "internal.h"
75  
76  #include <trace/events/sched.h>
77  
78  static int bprm_creds_from_file(struct linux_binprm *bprm);
79  
80  int suid_dumpable = 0;
81  
82  static LIST_HEAD(formats);
83  static DEFINE_RWLOCK(binfmt_lock);
84  
85  void __register_binfmt(struct linux_binfmt * fmt, int insert)
86  {
87  	write_lock(&binfmt_lock);
88  	insert ? list_add(&fmt->lh, &formats) :
89  		 list_add_tail(&fmt->lh, &formats);
90  	write_unlock(&binfmt_lock);
91  }
92  
93  EXPORT_SYMBOL(__register_binfmt);
94  
95  void unregister_binfmt(struct linux_binfmt * fmt)
96  {
97  	write_lock(&binfmt_lock);
98  	list_del(&fmt->lh);
99  	write_unlock(&binfmt_lock);
100  }
101  
102  EXPORT_SYMBOL(unregister_binfmt);
103  
104  static inline void put_binfmt(struct linux_binfmt * fmt)
105  {
106  	module_put(fmt->module);
107  }
108  
109  bool path_noexec(const struct path *path)
110  {
111  	return (path->mnt->mnt_flags & MNT_NOEXEC) ||
112  	       (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
113  }
114  
115  #ifdef CONFIG_USELIB
116  /*
117   * Note that a shared library must be both readable and executable due to
118   * security reasons.
119   *
120   * Also note that we take the address to load from the file itself.
121   */
122  SYSCALL_DEFINE1(uselib, const char __user *, library)
123  {
124  	struct linux_binfmt *fmt;
125  	struct file *file;
126  	struct filename *tmp = getname(library);
127  	int error = PTR_ERR(tmp);
128  	static const struct open_flags uselib_flags = {
129  		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
130  		.acc_mode = MAY_READ | MAY_EXEC,
131  		.intent = LOOKUP_OPEN,
132  		.lookup_flags = LOOKUP_FOLLOW,
133  	};
134  
135  	if (IS_ERR(tmp))
136  		goto out;
137  
138  	file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
139  	putname(tmp);
140  	error = PTR_ERR(file);
141  	if (IS_ERR(file))
142  		goto out;
143  
144  	/*
145  	 * may_open() has already checked for this, so it should be
146  	 * impossible to trip now. But we need to be extra cautious
147  	 * and check again at the very end too.
148  	 */
149  	error = -EACCES;
150  	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
151  			 path_noexec(&file->f_path)))
152  		goto exit;
153  
154  	fsnotify_open(file);
155  
156  	error = -ENOEXEC;
157  
158  	read_lock(&binfmt_lock);
159  	list_for_each_entry(fmt, &formats, lh) {
160  		if (!fmt->load_shlib)
161  			continue;
162  		if (!try_module_get(fmt->module))
163  			continue;
164  		read_unlock(&binfmt_lock);
165  		error = fmt->load_shlib(file);
166  		read_lock(&binfmt_lock);
167  		put_binfmt(fmt);
168  		if (error != -ENOEXEC)
169  			break;
170  	}
171  	read_unlock(&binfmt_lock);
172  exit:
173  	fput(file);
174  out:
175  	return error;
176  }
177  #endif /* #ifdef CONFIG_USELIB */
178  
179  #ifdef CONFIG_MMU
180  /*
181   * The nascent bprm->mm is not visible until exec_mmap() but it can
182   * use a lot of memory, account these pages in current->mm temporary
183   * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
184   * change the counter back via acct_arg_size(0).
185   */
186  static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
187  {
188  	struct mm_struct *mm = current->mm;
189  	long diff = (long)(pages - bprm->vma_pages);
190  
191  	if (!mm || !diff)
192  		return;
193  
194  	bprm->vma_pages = pages;
195  	add_mm_counter(mm, MM_ANONPAGES, diff);
196  }
197  
198  static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
199  		int write)
200  {
201  	struct page *page;
202  	int ret;
203  	unsigned int gup_flags = 0;
204  
205  #ifdef CONFIG_STACK_GROWSUP
206  	if (write) {
207  		ret = expand_downwards(bprm->vma, pos);
208  		if (ret < 0)
209  			return NULL;
210  	}
211  #endif
212  
213  	if (write)
214  		gup_flags |= FOLL_WRITE;
215  
216  	/*
217  	 * We are doing an exec().  'current' is the process
218  	 * doing the exec and bprm->mm is the new process's mm.
219  	 */
220  	mmap_read_lock(bprm->mm);
221  	ret = get_user_pages_remote(bprm->mm, pos, 1, gup_flags,
222  			&page, NULL, NULL);
223  	mmap_read_unlock(bprm->mm);
224  	if (ret <= 0)
225  		return NULL;
226  
227  	if (write)
228  		acct_arg_size(bprm, vma_pages(bprm->vma));
229  
230  	return page;
231  }
232  
233  static void put_arg_page(struct page *page)
234  {
235  	put_page(page);
236  }
237  
238  static void free_arg_pages(struct linux_binprm *bprm)
239  {
240  }
241  
242  static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
243  		struct page *page)
244  {
245  	flush_cache_page(bprm->vma, pos, page_to_pfn(page));
246  }
247  
248  static int __bprm_mm_init(struct linux_binprm *bprm)
249  {
250  	int err;
251  	struct vm_area_struct *vma = NULL;
252  	struct mm_struct *mm = bprm->mm;
253  
254  	bprm->vma = vma = vm_area_alloc(mm);
255  	if (!vma)
256  		return -ENOMEM;
257  	vma_set_anonymous(vma);
258  
259  	if (mmap_write_lock_killable(mm)) {
260  		err = -EINTR;
261  		goto err_free;
262  	}
263  
264  	/*
265  	 * Place the stack at the largest stack address the architecture
266  	 * supports. Later, we'll move this to an appropriate place. We don't
267  	 * use STACK_TOP because that can depend on attributes which aren't
268  	 * configured yet.
269  	 */
270  	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
271  	vma->vm_end = STACK_TOP_MAX;
272  	vma->vm_start = vma->vm_end - PAGE_SIZE;
273  	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
274  	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
275  
276  	err = insert_vm_struct(mm, vma);
277  	if (err)
278  		goto err;
279  
280  	mm->stack_vm = mm->total_vm = 1;
281  	mmap_write_unlock(mm);
282  	bprm->p = vma->vm_end - sizeof(void *);
283  	return 0;
284  err:
285  	mmap_write_unlock(mm);
286  err_free:
287  	bprm->vma = NULL;
288  	vm_area_free(vma);
289  	return err;
290  }
291  
292  static bool valid_arg_len(struct linux_binprm *bprm, long len)
293  {
294  	return len <= MAX_ARG_STRLEN;
295  }
296  
297  #else
298  
299  static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
300  {
301  }
302  
303  static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
304  		int write)
305  {
306  	struct page *page;
307  
308  	page = bprm->page[pos / PAGE_SIZE];
309  	if (!page && write) {
310  		page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
311  		if (!page)
312  			return NULL;
313  		bprm->page[pos / PAGE_SIZE] = page;
314  	}
315  
316  	return page;
317  }
318  
319  static void put_arg_page(struct page *page)
320  {
321  }
322  
323  static void free_arg_page(struct linux_binprm *bprm, int i)
324  {
325  	if (bprm->page[i]) {
326  		__free_page(bprm->page[i]);
327  		bprm->page[i] = NULL;
328  	}
329  }
330  
331  static void free_arg_pages(struct linux_binprm *bprm)
332  {
333  	int i;
334  
335  	for (i = 0; i < MAX_ARG_PAGES; i++)
336  		free_arg_page(bprm, i);
337  }
338  
339  static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
340  		struct page *page)
341  {
342  }
343  
344  static int __bprm_mm_init(struct linux_binprm *bprm)
345  {
346  	bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
347  	return 0;
348  }
349  
350  static bool valid_arg_len(struct linux_binprm *bprm, long len)
351  {
352  	return len <= bprm->p;
353  }
354  
355  #endif /* CONFIG_MMU */
356  
357  /*
358   * Create a new mm_struct and populate it with a temporary stack
359   * vm_area_struct.  We don't have enough context at this point to set the stack
360   * flags, permissions, and offset, so we use temporary values.  We'll update
361   * them later in setup_arg_pages().
362   */
363  static int bprm_mm_init(struct linux_binprm *bprm)
364  {
365  	int err;
366  	struct mm_struct *mm = NULL;
367  
368  	bprm->mm = mm = mm_alloc();
369  	err = -ENOMEM;
370  	if (!mm)
371  		goto err;
372  
373  	/* Save current stack limit for all calculations made during exec. */
374  	task_lock(current->group_leader);
375  	bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
376  	task_unlock(current->group_leader);
377  
378  	err = __bprm_mm_init(bprm);
379  	if (err)
380  		goto err;
381  
382  	return 0;
383  
384  err:
385  	if (mm) {
386  		bprm->mm = NULL;
387  		mmdrop(mm);
388  	}
389  
390  	return err;
391  }
392  
393  struct user_arg_ptr {
394  #ifdef CONFIG_COMPAT
395  	bool is_compat;
396  #endif
397  	union {
398  		const char __user *const __user *native;
399  #ifdef CONFIG_COMPAT
400  		const compat_uptr_t __user *compat;
401  #endif
402  	} ptr;
403  };
404  
405  static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
406  {
407  	const char __user *native;
408  
409  #ifdef CONFIG_COMPAT
410  	if (unlikely(argv.is_compat)) {
411  		compat_uptr_t compat;
412  
413  		if (get_user(compat, argv.ptr.compat + nr))
414  			return ERR_PTR(-EFAULT);
415  
416  		return compat_ptr(compat);
417  	}
418  #endif
419  
420  	if (get_user(native, argv.ptr.native + nr))
421  		return ERR_PTR(-EFAULT);
422  
423  	return native;
424  }
425  
426  /*
427   * count() counts the number of strings in array ARGV.
428   */
429  static int count(struct user_arg_ptr argv, int max)
430  {
431  	int i = 0;
432  
433  	if (argv.ptr.native != NULL) {
434  		for (;;) {
435  			const char __user *p = get_user_arg_ptr(argv, i);
436  
437  			if (!p)
438  				break;
439  
440  			if (IS_ERR(p))
441  				return -EFAULT;
442  
443  			if (i >= max)
444  				return -E2BIG;
445  			++i;
446  
447  			if (fatal_signal_pending(current))
448  				return -ERESTARTNOHAND;
449  			cond_resched();
450  		}
451  	}
452  	return i;
453  }
454  
455  static int count_strings_kernel(const char *const *argv)
456  {
457  	int i;
458  
459  	if (!argv)
460  		return 0;
461  
462  	for (i = 0; argv[i]; ++i) {
463  		if (i >= MAX_ARG_STRINGS)
464  			return -E2BIG;
465  		if (fatal_signal_pending(current))
466  			return -ERESTARTNOHAND;
467  		cond_resched();
468  	}
469  	return i;
470  }
471  
472  static int bprm_stack_limits(struct linux_binprm *bprm)
473  {
474  	unsigned long limit, ptr_size;
475  
476  	/*
477  	 * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
478  	 * (whichever is smaller) for the argv+env strings.
479  	 * This ensures that:
480  	 *  - the remaining binfmt code will not run out of stack space,
481  	 *  - the program will have a reasonable amount of stack left
482  	 *    to work from.
483  	 */
484  	limit = _STK_LIM / 4 * 3;
485  	limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
486  	/*
487  	 * We've historically supported up to 32 pages (ARG_MAX)
488  	 * of argument strings even with small stacks
489  	 */
490  	limit = max_t(unsigned long, limit, ARG_MAX);
491  	/*
492  	 * We must account for the size of all the argv and envp pointers to
493  	 * the argv and envp strings, since they will also take up space in
494  	 * the stack. They aren't stored until much later when we can't
495  	 * signal to the parent that the child has run out of stack space.
496  	 * Instead, calculate it here so it's possible to fail gracefully.
497  	 *
498  	 * In the case of argc = 0, make sure there is space for adding a
499  	 * empty string (which will bump argc to 1), to ensure confused
500  	 * userspace programs don't start processing from argv[1], thinking
501  	 * argc can never be 0, to keep them from walking envp by accident.
502  	 * See do_execveat_common().
503  	 */
504  	ptr_size = (max(bprm->argc, 1) + bprm->envc) * sizeof(void *);
505  	if (limit <= ptr_size)
506  		return -E2BIG;
507  	limit -= ptr_size;
508  
509  	bprm->argmin = bprm->p - limit;
510  	return 0;
511  }
512  
513  /*
514   * 'copy_strings()' copies argument/environment strings from the old
515   * processes's memory to the new process's stack.  The call to get_user_pages()
516   * ensures the destination page is created and not swapped out.
517   */
518  static int copy_strings(int argc, struct user_arg_ptr argv,
519  			struct linux_binprm *bprm)
520  {
521  	struct page *kmapped_page = NULL;
522  	char *kaddr = NULL;
523  	unsigned long kpos = 0;
524  	int ret;
525  
526  	while (argc-- > 0) {
527  		const char __user *str;
528  		int len;
529  		unsigned long pos;
530  
531  		ret = -EFAULT;
532  		str = get_user_arg_ptr(argv, argc);
533  		if (IS_ERR(str))
534  			goto out;
535  
536  		len = strnlen_user(str, MAX_ARG_STRLEN);
537  		if (!len)
538  			goto out;
539  
540  		ret = -E2BIG;
541  		if (!valid_arg_len(bprm, len))
542  			goto out;
543  
544  		/* We're going to work our way backwards. */
545  		pos = bprm->p;
546  		str += len;
547  		bprm->p -= len;
548  #ifdef CONFIG_MMU
549  		if (bprm->p < bprm->argmin)
550  			goto out;
551  #endif
552  
553  		while (len > 0) {
554  			int offset, bytes_to_copy;
555  
556  			if (fatal_signal_pending(current)) {
557  				ret = -ERESTARTNOHAND;
558  				goto out;
559  			}
560  			cond_resched();
561  
562  			offset = pos % PAGE_SIZE;
563  			if (offset == 0)
564  				offset = PAGE_SIZE;
565  
566  			bytes_to_copy = offset;
567  			if (bytes_to_copy > len)
568  				bytes_to_copy = len;
569  
570  			offset -= bytes_to_copy;
571  			pos -= bytes_to_copy;
572  			str -= bytes_to_copy;
573  			len -= bytes_to_copy;
574  
575  			if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
576  				struct page *page;
577  
578  				page = get_arg_page(bprm, pos, 1);
579  				if (!page) {
580  					ret = -E2BIG;
581  					goto out;
582  				}
583  
584  				if (kmapped_page) {
585  					flush_dcache_page(kmapped_page);
586  					kunmap_local(kaddr);
587  					put_arg_page(kmapped_page);
588  				}
589  				kmapped_page = page;
590  				kaddr = kmap_local_page(kmapped_page);
591  				kpos = pos & PAGE_MASK;
592  				flush_arg_page(bprm, kpos, kmapped_page);
593  			}
594  			if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
595  				ret = -EFAULT;
596  				goto out;
597  			}
598  		}
599  	}
600  	ret = 0;
601  out:
602  	if (kmapped_page) {
603  		flush_dcache_page(kmapped_page);
604  		kunmap_local(kaddr);
605  		put_arg_page(kmapped_page);
606  	}
607  	return ret;
608  }
609  
610  /*
611   * Copy and argument/environment string from the kernel to the processes stack.
612   */
613  int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
614  {
615  	int len = strnlen(arg, MAX_ARG_STRLEN) + 1 /* terminating NUL */;
616  	unsigned long pos = bprm->p;
617  
618  	if (len == 0)
619  		return -EFAULT;
620  	if (!valid_arg_len(bprm, len))
621  		return -E2BIG;
622  
623  	/* We're going to work our way backwards. */
624  	arg += len;
625  	bprm->p -= len;
626  	if (IS_ENABLED(CONFIG_MMU) && bprm->p < bprm->argmin)
627  		return -E2BIG;
628  
629  	while (len > 0) {
630  		unsigned int bytes_to_copy = min_t(unsigned int, len,
631  				min_not_zero(offset_in_page(pos), PAGE_SIZE));
632  		struct page *page;
633  
634  		pos -= bytes_to_copy;
635  		arg -= bytes_to_copy;
636  		len -= bytes_to_copy;
637  
638  		page = get_arg_page(bprm, pos, 1);
639  		if (!page)
640  			return -E2BIG;
641  		flush_arg_page(bprm, pos & PAGE_MASK, page);
642  		memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
643  		put_arg_page(page);
644  	}
645  
646  	return 0;
647  }
648  EXPORT_SYMBOL(copy_string_kernel);
649  
650  static int copy_strings_kernel(int argc, const char *const *argv,
651  			       struct linux_binprm *bprm)
652  {
653  	while (argc-- > 0) {
654  		int ret = copy_string_kernel(argv[argc], bprm);
655  		if (ret < 0)
656  			return ret;
657  		if (fatal_signal_pending(current))
658  			return -ERESTARTNOHAND;
659  		cond_resched();
660  	}
661  	return 0;
662  }
663  
664  #ifdef CONFIG_MMU
665  
666  /*
667   * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
668   * the binfmt code determines where the new stack should reside, we shift it to
669   * its final location.  The process proceeds as follows:
670   *
671   * 1) Use shift to calculate the new vma endpoints.
672   * 2) Extend vma to cover both the old and new ranges.  This ensures the
673   *    arguments passed to subsequent functions are consistent.
674   * 3) Move vma's page tables to the new range.
675   * 4) Free up any cleared pgd range.
676   * 5) Shrink the vma to cover only the new range.
677   */
678  static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
679  {
680  	struct mm_struct *mm = vma->vm_mm;
681  	unsigned long old_start = vma->vm_start;
682  	unsigned long old_end = vma->vm_end;
683  	unsigned long length = old_end - old_start;
684  	unsigned long new_start = old_start - shift;
685  	unsigned long new_end = old_end - shift;
686  	VMA_ITERATOR(vmi, mm, new_start);
687  	struct vm_area_struct *next;
688  	struct mmu_gather tlb;
689  
690  	BUG_ON(new_start > new_end);
691  
692  	/*
693  	 * ensure there are no vmas between where we want to go
694  	 * and where we are
695  	 */
696  	if (vma != vma_next(&vmi))
697  		return -EFAULT;
698  
699  	/*
700  	 * cover the whole range: [new_start, old_end)
701  	 */
702  	if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
703  		return -ENOMEM;
704  
705  	/*
706  	 * move the page tables downwards, on failure we rely on
707  	 * process cleanup to remove whatever mess we made.
708  	 */
709  	if (length != move_page_tables(vma, old_start,
710  				       vma, new_start, length, false))
711  		return -ENOMEM;
712  
713  	lru_add_drain();
714  	tlb_gather_mmu(&tlb, mm);
715  	next = vma_next(&vmi);
716  	if (new_end > old_start) {
717  		/*
718  		 * when the old and new regions overlap clear from new_end.
719  		 */
720  		free_pgd_range(&tlb, new_end, old_end, new_end,
721  			next ? next->vm_start : USER_PGTABLES_CEILING);
722  	} else {
723  		/*
724  		 * otherwise, clean from old_start; this is done to not touch
725  		 * the address space in [new_end, old_start) some architectures
726  		 * have constraints on va-space that make this illegal (IA64) -
727  		 * for the others its just a little faster.
728  		 */
729  		free_pgd_range(&tlb, old_start, old_end, new_end,
730  			next ? next->vm_start : USER_PGTABLES_CEILING);
731  	}
732  	tlb_finish_mmu(&tlb);
733  
734  	/*
735  	 * Shrink the vma to just the new range.  Always succeeds.
736  	 */
737  	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
738  
739  	return 0;
740  }
741  
742  /*
743   * Finalizes the stack vm_area_struct. The flags and permissions are updated,
744   * the stack is optionally relocated, and some extra space is added.
745   */
746  int setup_arg_pages(struct linux_binprm *bprm,
747  		    unsigned long stack_top,
748  		    int executable_stack)
749  {
750  	unsigned long ret;
751  	unsigned long stack_shift;
752  	struct mm_struct *mm = current->mm;
753  	struct vm_area_struct *vma = bprm->vma;
754  	struct vm_area_struct *prev = NULL;
755  	unsigned long vm_flags;
756  	unsigned long stack_base;
757  	unsigned long stack_size;
758  	unsigned long stack_expand;
759  	unsigned long rlim_stack;
760  	struct mmu_gather tlb;
761  
762  #ifdef CONFIG_STACK_GROWSUP
763  	/* Limit stack size */
764  	stack_base = bprm->rlim_stack.rlim_max;
765  
766  	stack_base = calc_max_stack_size(stack_base);
767  
768  	/* Add space for stack randomization. */
769  	stack_base += (STACK_RND_MASK << PAGE_SHIFT);
770  
771  	/* Make sure we didn't let the argument array grow too large. */
772  	if (vma->vm_end - vma->vm_start > stack_base)
773  		return -ENOMEM;
774  
775  	stack_base = PAGE_ALIGN(stack_top - stack_base);
776  
777  	stack_shift = vma->vm_start - stack_base;
778  	mm->arg_start = bprm->p - stack_shift;
779  	bprm->p = vma->vm_end - stack_shift;
780  #else
781  	stack_top = arch_align_stack(stack_top);
782  	stack_top = PAGE_ALIGN(stack_top);
783  
784  	if (unlikely(stack_top < mmap_min_addr) ||
785  	    unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
786  		return -ENOMEM;
787  
788  	stack_shift = vma->vm_end - stack_top;
789  
790  	bprm->p -= stack_shift;
791  	mm->arg_start = bprm->p;
792  #endif
793  
794  	if (bprm->loader)
795  		bprm->loader -= stack_shift;
796  	bprm->exec -= stack_shift;
797  
798  	if (mmap_write_lock_killable(mm))
799  		return -EINTR;
800  
801  	vm_flags = VM_STACK_FLAGS;
802  
803  	/*
804  	 * Adjust stack execute permissions; explicitly enable for
805  	 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
806  	 * (arch default) otherwise.
807  	 */
808  	if (unlikely(executable_stack == EXSTACK_ENABLE_X))
809  		vm_flags |= VM_EXEC;
810  	else if (executable_stack == EXSTACK_DISABLE_X)
811  		vm_flags &= ~VM_EXEC;
812  	vm_flags |= mm->def_flags;
813  	vm_flags |= VM_STACK_INCOMPLETE_SETUP;
814  
815  	tlb_gather_mmu(&tlb, mm);
816  	ret = mprotect_fixup(&tlb, vma, &prev, vma->vm_start, vma->vm_end,
817  			vm_flags);
818  	tlb_finish_mmu(&tlb);
819  
820  	if (ret)
821  		goto out_unlock;
822  	BUG_ON(prev != vma);
823  
824  	if (unlikely(vm_flags & VM_EXEC)) {
825  		pr_warn_once("process '%pD4' started with executable stack\n",
826  			     bprm->file);
827  	}
828  
829  	/* Move stack pages down in memory. */
830  	if (stack_shift) {
831  		ret = shift_arg_pages(vma, stack_shift);
832  		if (ret)
833  			goto out_unlock;
834  	}
835  
836  	/* mprotect_fixup is overkill to remove the temporary stack flags */
837  	vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
838  
839  	stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
840  	stack_size = vma->vm_end - vma->vm_start;
841  	/*
842  	 * Align this down to a page boundary as expand_stack
843  	 * will align it up.
844  	 */
845  	rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
846  
847  	stack_expand = min(rlim_stack, stack_size + stack_expand);
848  
849  #ifdef CONFIG_STACK_GROWSUP
850  	stack_base = vma->vm_start + stack_expand;
851  #else
852  	stack_base = vma->vm_end - stack_expand;
853  #endif
854  	current->mm->start_stack = bprm->p;
855  	ret = expand_stack(vma, stack_base);
856  	if (ret)
857  		ret = -EFAULT;
858  
859  out_unlock:
860  	mmap_write_unlock(mm);
861  	return ret;
862  }
863  EXPORT_SYMBOL(setup_arg_pages);
864  
865  #else
866  
867  /*
868   * Transfer the program arguments and environment from the holding pages
869   * onto the stack. The provided stack pointer is adjusted accordingly.
870   */
871  int transfer_args_to_stack(struct linux_binprm *bprm,
872  			   unsigned long *sp_location)
873  {
874  	unsigned long index, stop, sp;
875  	int ret = 0;
876  
877  	stop = bprm->p >> PAGE_SHIFT;
878  	sp = *sp_location;
879  
880  	for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
881  		unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
882  		char *src = kmap_local_page(bprm->page[index]) + offset;
883  		sp -= PAGE_SIZE - offset;
884  		if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
885  			ret = -EFAULT;
886  		kunmap_local(src);
887  		if (ret)
888  			goto out;
889  	}
890  
891  	*sp_location = sp;
892  
893  out:
894  	return ret;
895  }
896  EXPORT_SYMBOL(transfer_args_to_stack);
897  
898  #endif /* CONFIG_MMU */
899  
900  static struct file *do_open_execat(int fd, struct filename *name, int flags)
901  {
902  	struct file *file;
903  	int err;
904  	struct open_flags open_exec_flags = {
905  		.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
906  		.acc_mode = MAY_EXEC,
907  		.intent = LOOKUP_OPEN,
908  		.lookup_flags = LOOKUP_FOLLOW,
909  	};
910  
911  	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
912  		return ERR_PTR(-EINVAL);
913  	if (flags & AT_SYMLINK_NOFOLLOW)
914  		open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
915  	if (flags & AT_EMPTY_PATH)
916  		open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
917  
918  	file = do_filp_open(fd, name, &open_exec_flags);
919  	if (IS_ERR(file))
920  		goto out;
921  
922  	/*
923  	 * may_open() has already checked for this, so it should be
924  	 * impossible to trip now. But we need to be extra cautious
925  	 * and check again at the very end too.
926  	 */
927  	err = -EACCES;
928  	if (WARN_ON_ONCE(!S_ISREG(file_inode(file)->i_mode) ||
929  			 path_noexec(&file->f_path)))
930  		goto exit;
931  
932  	err = deny_write_access(file);
933  	if (err)
934  		goto exit;
935  
936  	if (name->name[0] != '\0')
937  		fsnotify_open(file);
938  
939  out:
940  	return file;
941  
942  exit:
943  	fput(file);
944  	return ERR_PTR(err);
945  }
946  
947  struct file *open_exec(const char *name)
948  {
949  	struct filename *filename = getname_kernel(name);
950  	struct file *f = ERR_CAST(filename);
951  
952  	if (!IS_ERR(filename)) {
953  		f = do_open_execat(AT_FDCWD, filename, 0);
954  		putname(filename);
955  	}
956  	return f;
957  }
958  EXPORT_SYMBOL(open_exec);
959  
960  #if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC)
961  ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
962  {
963  	ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
964  	if (res > 0)
965  		flush_icache_user_range(addr, addr + len);
966  	return res;
967  }
968  EXPORT_SYMBOL(read_code);
969  #endif
970  
971  /*
972   * Maps the mm_struct mm into the current task struct.
973   * On success, this function returns with exec_update_lock
974   * held for writing.
975   */
976  static int exec_mmap(struct mm_struct *mm)
977  {
978  	struct task_struct *tsk;
979  	struct mm_struct *old_mm, *active_mm;
980  	int ret;
981  
982  	/* Notify parent that we're no longer interested in the old VM */
983  	tsk = current;
984  	old_mm = current->mm;
985  	exec_mm_release(tsk, old_mm);
986  	if (old_mm)
987  		sync_mm_rss(old_mm);
988  
989  	ret = down_write_killable(&tsk->signal->exec_update_lock);
990  	if (ret)
991  		return ret;
992  
993  	if (old_mm) {
994  		/*
995  		 * If there is a pending fatal signal perhaps a signal
996  		 * whose default action is to create a coredump get
997  		 * out and die instead of going through with the exec.
998  		 */
999  		ret = mmap_read_lock_killable(old_mm);
1000  		if (ret) {
1001  			up_write(&tsk->signal->exec_update_lock);
1002  			return ret;
1003  		}
1004  	}
1005  
1006  	task_lock(tsk);
1007  	membarrier_exec_mmap(mm);
1008  
1009  	local_irq_disable();
1010  	active_mm = tsk->active_mm;
1011  	tsk->active_mm = mm;
1012  	tsk->mm = mm;
1013  	/*
1014  	 * This prevents preemption while active_mm is being loaded and
1015  	 * it and mm are being updated, which could cause problems for
1016  	 * lazy tlb mm refcounting when these are updated by context
1017  	 * switches. Not all architectures can handle irqs off over
1018  	 * activate_mm yet.
1019  	 */
1020  	if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1021  		local_irq_enable();
1022  	activate_mm(active_mm, mm);
1023  	if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
1024  		local_irq_enable();
1025  	lru_gen_add_mm(mm);
1026  	task_unlock(tsk);
1027  	lru_gen_use_mm(mm);
1028  	if (old_mm) {
1029  		mmap_read_unlock(old_mm);
1030  		BUG_ON(active_mm != old_mm);
1031  		setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
1032  		mm_update_next_owner(old_mm);
1033  		mmput(old_mm);
1034  		return 0;
1035  	}
1036  	mmdrop(active_mm);
1037  	return 0;
1038  }
1039  
1040  static int de_thread(struct task_struct *tsk)
1041  {
1042  	struct signal_struct *sig = tsk->signal;
1043  	struct sighand_struct *oldsighand = tsk->sighand;
1044  	spinlock_t *lock = &oldsighand->siglock;
1045  
1046  	if (thread_group_empty(tsk))
1047  		goto no_thread_group;
1048  
1049  	/*
1050  	 * Kill all other threads in the thread group.
1051  	 */
1052  	spin_lock_irq(lock);
1053  	if ((sig->flags & SIGNAL_GROUP_EXIT) || sig->group_exec_task) {
1054  		/*
1055  		 * Another group action in progress, just
1056  		 * return so that the signal is processed.
1057  		 */
1058  		spin_unlock_irq(lock);
1059  		return -EAGAIN;
1060  	}
1061  
1062  	sig->group_exec_task = tsk;
1063  	sig->notify_count = zap_other_threads(tsk);
1064  	if (!thread_group_leader(tsk))
1065  		sig->notify_count--;
1066  
1067  	while (sig->notify_count) {
1068  		__set_current_state(TASK_KILLABLE);
1069  		spin_unlock_irq(lock);
1070  		schedule();
1071  		if (__fatal_signal_pending(tsk))
1072  			goto killed;
1073  		spin_lock_irq(lock);
1074  	}
1075  	spin_unlock_irq(lock);
1076  
1077  	/*
1078  	 * At this point all other threads have exited, all we have to
1079  	 * do is to wait for the thread group leader to become inactive,
1080  	 * and to assume its PID:
1081  	 */
1082  	if (!thread_group_leader(tsk)) {
1083  		struct task_struct *leader = tsk->group_leader;
1084  
1085  		for (;;) {
1086  			cgroup_threadgroup_change_begin(tsk);
1087  			write_lock_irq(&tasklist_lock);
1088  			/*
1089  			 * Do this under tasklist_lock to ensure that
1090  			 * exit_notify() can't miss ->group_exec_task
1091  			 */
1092  			sig->notify_count = -1;
1093  			if (likely(leader->exit_state))
1094  				break;
1095  			__set_current_state(TASK_KILLABLE);
1096  			write_unlock_irq(&tasklist_lock);
1097  			cgroup_threadgroup_change_end(tsk);
1098  			schedule();
1099  			if (__fatal_signal_pending(tsk))
1100  				goto killed;
1101  		}
1102  
1103  		/*
1104  		 * The only record we have of the real-time age of a
1105  		 * process, regardless of execs it's done, is start_time.
1106  		 * All the past CPU time is accumulated in signal_struct
1107  		 * from sister threads now dead.  But in this non-leader
1108  		 * exec, nothing survives from the original leader thread,
1109  		 * whose birth marks the true age of this process now.
1110  		 * When we take on its identity by switching to its PID, we
1111  		 * also take its birthdate (always earlier than our own).
1112  		 */
1113  		tsk->start_time = leader->start_time;
1114  		tsk->start_boottime = leader->start_boottime;
1115  
1116  		BUG_ON(!same_thread_group(leader, tsk));
1117  		/*
1118  		 * An exec() starts a new thread group with the
1119  		 * TGID of the previous thread group. Rehash the
1120  		 * two threads with a switched PID, and release
1121  		 * the former thread group leader:
1122  		 */
1123  
1124  		/* Become a process group leader with the old leader's pid.
1125  		 * The old leader becomes a thread of the this thread group.
1126  		 */
1127  		exchange_tids(tsk, leader);
1128  		transfer_pid(leader, tsk, PIDTYPE_TGID);
1129  		transfer_pid(leader, tsk, PIDTYPE_PGID);
1130  		transfer_pid(leader, tsk, PIDTYPE_SID);
1131  
1132  		list_replace_rcu(&leader->tasks, &tsk->tasks);
1133  		list_replace_init(&leader->sibling, &tsk->sibling);
1134  
1135  		tsk->group_leader = tsk;
1136  		leader->group_leader = tsk;
1137  
1138  		tsk->exit_signal = SIGCHLD;
1139  		leader->exit_signal = -1;
1140  
1141  		BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1142  		leader->exit_state = EXIT_DEAD;
1143  
1144  		/*
1145  		 * We are going to release_task()->ptrace_unlink() silently,
1146  		 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1147  		 * the tracer won't block again waiting for this thread.
1148  		 */
1149  		if (unlikely(leader->ptrace))
1150  			__wake_up_parent(leader, leader->parent);
1151  		write_unlock_irq(&tasklist_lock);
1152  		cgroup_threadgroup_change_end(tsk);
1153  
1154  		release_task(leader);
1155  	}
1156  
1157  	sig->group_exec_task = NULL;
1158  	sig->notify_count = 0;
1159  
1160  no_thread_group:
1161  	/* we have changed execution domain */
1162  	tsk->exit_signal = SIGCHLD;
1163  
1164  	BUG_ON(!thread_group_leader(tsk));
1165  	return 0;
1166  
1167  killed:
1168  	/* protects against exit_notify() and __exit_signal() */
1169  	read_lock(&tasklist_lock);
1170  	sig->group_exec_task = NULL;
1171  	sig->notify_count = 0;
1172  	read_unlock(&tasklist_lock);
1173  	return -EAGAIN;
1174  }
1175  
1176  
1177  /*
1178   * This function makes sure the current process has its own signal table,
1179   * so that flush_signal_handlers can later reset the handlers without
1180   * disturbing other processes.  (Other processes might share the signal
1181   * table via the CLONE_SIGHAND option to clone().)
1182   */
1183  static int unshare_sighand(struct task_struct *me)
1184  {
1185  	struct sighand_struct *oldsighand = me->sighand;
1186  
1187  	if (refcount_read(&oldsighand->count) != 1) {
1188  		struct sighand_struct *newsighand;
1189  		/*
1190  		 * This ->sighand is shared with the CLONE_SIGHAND
1191  		 * but not CLONE_THREAD task, switch to the new one.
1192  		 */
1193  		newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1194  		if (!newsighand)
1195  			return -ENOMEM;
1196  
1197  		refcount_set(&newsighand->count, 1);
1198  
1199  		write_lock_irq(&tasklist_lock);
1200  		spin_lock(&oldsighand->siglock);
1201  		memcpy(newsighand->action, oldsighand->action,
1202  		       sizeof(newsighand->action));
1203  		rcu_assign_pointer(me->sighand, newsighand);
1204  		spin_unlock(&oldsighand->siglock);
1205  		write_unlock_irq(&tasklist_lock);
1206  
1207  		__cleanup_sighand(oldsighand);
1208  	}
1209  	return 0;
1210  }
1211  
1212  char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
1213  {
1214  	task_lock(tsk);
1215  	/* Always NUL terminated and zero-padded */
1216  	strscpy_pad(buf, tsk->comm, buf_size);
1217  	task_unlock(tsk);
1218  	return buf;
1219  }
1220  EXPORT_SYMBOL_GPL(__get_task_comm);
1221  
1222  /*
1223   * These functions flushes out all traces of the currently running executable
1224   * so that a new one can be started
1225   */
1226  
1227  void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1228  {
1229  	task_lock(tsk);
1230  	trace_task_rename(tsk, buf);
1231  	strscpy_pad(tsk->comm, buf, sizeof(tsk->comm));
1232  	task_unlock(tsk);
1233  	perf_event_comm(tsk, exec);
1234  }
1235  
1236  /*
1237   * Calling this is the point of no return. None of the failures will be
1238   * seen by userspace since either the process is already taking a fatal
1239   * signal (via de_thread() or coredump), or will have SEGV raised
1240   * (after exec_mmap()) by search_binary_handler (see below).
1241   */
1242  int begin_new_exec(struct linux_binprm * bprm)
1243  {
1244  	struct task_struct *me = current;
1245  	int retval;
1246  
1247  	/* Once we are committed compute the creds */
1248  	retval = bprm_creds_from_file(bprm);
1249  	if (retval)
1250  		return retval;
1251  
1252  	/*
1253  	 * Ensure all future errors are fatal.
1254  	 */
1255  	bprm->point_of_no_return = true;
1256  
1257  	/*
1258  	 * Make this the only thread in the thread group.
1259  	 */
1260  	retval = de_thread(me);
1261  	if (retval)
1262  		goto out;
1263  
1264  	/*
1265  	 * Cancel any io_uring activity across execve
1266  	 */
1267  	io_uring_task_cancel();
1268  
1269  	/* Ensure the files table is not shared. */
1270  	retval = unshare_files();
1271  	if (retval)
1272  		goto out;
1273  
1274  	/*
1275  	 * Must be called _before_ exec_mmap() as bprm->mm is
1276  	 * not visible until then. This also enables the update
1277  	 * to be lockless.
1278  	 */
1279  	retval = set_mm_exe_file(bprm->mm, bprm->file);
1280  	if (retval)
1281  		goto out;
1282  
1283  	/* If the binary is not readable then enforce mm->dumpable=0 */
1284  	would_dump(bprm, bprm->file);
1285  	if (bprm->have_execfd)
1286  		would_dump(bprm, bprm->executable);
1287  
1288  	/*
1289  	 * Release all of the old mmap stuff
1290  	 */
1291  	acct_arg_size(bprm, 0);
1292  	retval = exec_mmap(bprm->mm);
1293  	if (retval)
1294  		goto out;
1295  
1296  	bprm->mm = NULL;
1297  
1298  	retval = exec_task_namespaces();
1299  	if (retval)
1300  		goto out_unlock;
1301  
1302  #ifdef CONFIG_POSIX_TIMERS
1303  	spin_lock_irq(&me->sighand->siglock);
1304  	posix_cpu_timers_exit(me);
1305  	spin_unlock_irq(&me->sighand->siglock);
1306  	exit_itimers(me);
1307  	flush_itimer_signals();
1308  #endif
1309  
1310  	/*
1311  	 * Make the signal table private.
1312  	 */
1313  	retval = unshare_sighand(me);
1314  	if (retval)
1315  		goto out_unlock;
1316  
1317  	me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC |
1318  					PF_NOFREEZE | PF_NO_SETAFFINITY);
1319  	flush_thread();
1320  	me->personality &= ~bprm->per_clear;
1321  
1322  	clear_syscall_work_syscall_user_dispatch(me);
1323  
1324  	/*
1325  	 * We have to apply CLOEXEC before we change whether the process is
1326  	 * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1327  	 * trying to access the should-be-closed file descriptors of a process
1328  	 * undergoing exec(2).
1329  	 */
1330  	do_close_on_exec(me->files);
1331  
1332  	if (bprm->secureexec) {
1333  		/* Make sure parent cannot signal privileged process. */
1334  		me->pdeath_signal = 0;
1335  
1336  		/*
1337  		 * For secureexec, reset the stack limit to sane default to
1338  		 * avoid bad behavior from the prior rlimits. This has to
1339  		 * happen before arch_pick_mmap_layout(), which examines
1340  		 * RLIMIT_STACK, but after the point of no return to avoid
1341  		 * needing to clean up the change on failure.
1342  		 */
1343  		if (bprm->rlim_stack.rlim_cur > _STK_LIM)
1344  			bprm->rlim_stack.rlim_cur = _STK_LIM;
1345  	}
1346  
1347  	me->sas_ss_sp = me->sas_ss_size = 0;
1348  
1349  	/*
1350  	 * Figure out dumpability. Note that this checking only of current
1351  	 * is wrong, but userspace depends on it. This should be testing
1352  	 * bprm->secureexec instead.
1353  	 */
1354  	if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
1355  	    !(uid_eq(current_euid(), current_uid()) &&
1356  	      gid_eq(current_egid(), current_gid())))
1357  		set_dumpable(current->mm, suid_dumpable);
1358  	else
1359  		set_dumpable(current->mm, SUID_DUMP_USER);
1360  
1361  	perf_event_exec();
1362  	__set_task_comm(me, kbasename(bprm->filename), true);
1363  
1364  	/* An exec changes our domain. We are no longer part of the thread
1365  	   group */
1366  	WRITE_ONCE(me->self_exec_id, me->self_exec_id + 1);
1367  	flush_signal_handlers(me, 0);
1368  
1369  	retval = set_cred_ucounts(bprm->cred);
1370  	if (retval < 0)
1371  		goto out_unlock;
1372  
1373  	/*
1374  	 * install the new credentials for this executable
1375  	 */
1376  	security_bprm_committing_creds(bprm);
1377  
1378  	commit_creds(bprm->cred);
1379  	bprm->cred = NULL;
1380  
1381  	/*
1382  	 * Disable monitoring for regular users
1383  	 * when executing setuid binaries. Must
1384  	 * wait until new credentials are committed
1385  	 * by commit_creds() above
1386  	 */
1387  	if (get_dumpable(me->mm) != SUID_DUMP_USER)
1388  		perf_event_exit_task(me);
1389  	/*
1390  	 * cred_guard_mutex must be held at least to this point to prevent
1391  	 * ptrace_attach() from altering our determination of the task's
1392  	 * credentials; any time after this it may be unlocked.
1393  	 */
1394  	security_bprm_committed_creds(bprm);
1395  
1396  	/* Pass the opened binary to the interpreter. */
1397  	if (bprm->have_execfd) {
1398  		retval = get_unused_fd_flags(0);
1399  		if (retval < 0)
1400  			goto out_unlock;
1401  		fd_install(retval, bprm->executable);
1402  		bprm->executable = NULL;
1403  		bprm->execfd = retval;
1404  	}
1405  	return 0;
1406  
1407  out_unlock:
1408  	up_write(&me->signal->exec_update_lock);
1409  out:
1410  	return retval;
1411  }
1412  EXPORT_SYMBOL(begin_new_exec);
1413  
1414  void would_dump(struct linux_binprm *bprm, struct file *file)
1415  {
1416  	struct inode *inode = file_inode(file);
1417  	struct user_namespace *mnt_userns = file_mnt_user_ns(file);
1418  	if (inode_permission(mnt_userns, inode, MAY_READ) < 0) {
1419  		struct user_namespace *old, *user_ns;
1420  		bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1421  
1422  		/* Ensure mm->user_ns contains the executable */
1423  		user_ns = old = bprm->mm->user_ns;
1424  		while ((user_ns != &init_user_ns) &&
1425  		       !privileged_wrt_inode_uidgid(user_ns, mnt_userns, inode))
1426  			user_ns = user_ns->parent;
1427  
1428  		if (old != user_ns) {
1429  			bprm->mm->user_ns = get_user_ns(user_ns);
1430  			put_user_ns(old);
1431  		}
1432  	}
1433  }
1434  EXPORT_SYMBOL(would_dump);
1435  
1436  void setup_new_exec(struct linux_binprm * bprm)
1437  {
1438  	/* Setup things that can depend upon the personality */
1439  	struct task_struct *me = current;
1440  
1441  	arch_pick_mmap_layout(me->mm, &bprm->rlim_stack);
1442  
1443  	arch_setup_new_exec();
1444  
1445  	/* Set the new mm task size. We have to do that late because it may
1446  	 * depend on TIF_32BIT which is only updated in flush_thread() on
1447  	 * some architectures like powerpc
1448  	 */
1449  	me->mm->task_size = TASK_SIZE;
1450  	up_write(&me->signal->exec_update_lock);
1451  	mutex_unlock(&me->signal->cred_guard_mutex);
1452  }
1453  EXPORT_SYMBOL(setup_new_exec);
1454  
1455  /* Runs immediately before start_thread() takes over. */
1456  void finalize_exec(struct linux_binprm *bprm)
1457  {
1458  	/* Store any stack rlimit changes before starting thread. */
1459  	task_lock(current->group_leader);
1460  	current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
1461  	task_unlock(current->group_leader);
1462  }
1463  EXPORT_SYMBOL(finalize_exec);
1464  
1465  /*
1466   * Prepare credentials and lock ->cred_guard_mutex.
1467   * setup_new_exec() commits the new creds and drops the lock.
1468   * Or, if exec fails before, free_bprm() should release ->cred
1469   * and unlock.
1470   */
1471  static int prepare_bprm_creds(struct linux_binprm *bprm)
1472  {
1473  	if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1474  		return -ERESTARTNOINTR;
1475  
1476  	bprm->cred = prepare_exec_creds();
1477  	if (likely(bprm->cred))
1478  		return 0;
1479  
1480  	mutex_unlock(&current->signal->cred_guard_mutex);
1481  	return -ENOMEM;
1482  }
1483  
1484  static void free_bprm(struct linux_binprm *bprm)
1485  {
1486  	if (bprm->mm) {
1487  		acct_arg_size(bprm, 0);
1488  		mmput(bprm->mm);
1489  	}
1490  	free_arg_pages(bprm);
1491  	if (bprm->cred) {
1492  		mutex_unlock(&current->signal->cred_guard_mutex);
1493  		abort_creds(bprm->cred);
1494  	}
1495  	if (bprm->file) {
1496  		allow_write_access(bprm->file);
1497  		fput(bprm->file);
1498  	}
1499  	if (bprm->executable)
1500  		fput(bprm->executable);
1501  	/* If a binfmt changed the interp, free it. */
1502  	if (bprm->interp != bprm->filename)
1503  		kfree(bprm->interp);
1504  	kfree(bprm->fdpath);
1505  	kfree(bprm);
1506  }
1507  
1508  static struct linux_binprm *alloc_bprm(int fd, struct filename *filename)
1509  {
1510  	struct linux_binprm *bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1511  	int retval = -ENOMEM;
1512  	if (!bprm)
1513  		goto out;
1514  
1515  	if (fd == AT_FDCWD || filename->name[0] == '/') {
1516  		bprm->filename = filename->name;
1517  	} else {
1518  		if (filename->name[0] == '\0')
1519  			bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
1520  		else
1521  			bprm->fdpath = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
1522  						  fd, filename->name);
1523  		if (!bprm->fdpath)
1524  			goto out_free;
1525  
1526  		bprm->filename = bprm->fdpath;
1527  	}
1528  	bprm->interp = bprm->filename;
1529  
1530  	retval = bprm_mm_init(bprm);
1531  	if (retval)
1532  		goto out_free;
1533  	return bprm;
1534  
1535  out_free:
1536  	free_bprm(bprm);
1537  out:
1538  	return ERR_PTR(retval);
1539  }
1540  
1541  int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
1542  {
1543  	/* If a binfmt changed the interp, free it first. */
1544  	if (bprm->interp != bprm->filename)
1545  		kfree(bprm->interp);
1546  	bprm->interp = kstrdup(interp, GFP_KERNEL);
1547  	if (!bprm->interp)
1548  		return -ENOMEM;
1549  	return 0;
1550  }
1551  EXPORT_SYMBOL(bprm_change_interp);
1552  
1553  /*
1554   * determine how safe it is to execute the proposed program
1555   * - the caller must hold ->cred_guard_mutex to protect against
1556   *   PTRACE_ATTACH or seccomp thread-sync
1557   */
1558  static void check_unsafe_exec(struct linux_binprm *bprm)
1559  {
1560  	struct task_struct *p = current, *t;
1561  	unsigned n_fs;
1562  
1563  	if (p->ptrace)
1564  		bprm->unsafe |= LSM_UNSAFE_PTRACE;
1565  
1566  	/*
1567  	 * This isn't strictly necessary, but it makes it harder for LSMs to
1568  	 * mess up.
1569  	 */
1570  	if (task_no_new_privs(current))
1571  		bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1572  
1573  	/*
1574  	 * If another task is sharing our fs, we cannot safely
1575  	 * suid exec because the differently privileged task
1576  	 * will be able to manipulate the current directory, etc.
1577  	 * It would be nice to force an unshare instead...
1578  	 */
1579  	t = p;
1580  	n_fs = 1;
1581  	spin_lock(&p->fs->lock);
1582  	rcu_read_lock();
1583  	while_each_thread(p, t) {
1584  		if (t->fs == p->fs)
1585  			n_fs++;
1586  	}
1587  	rcu_read_unlock();
1588  
1589  	if (p->fs->users > n_fs)
1590  		bprm->unsafe |= LSM_UNSAFE_SHARE;
1591  	else
1592  		p->fs->in_exec = 1;
1593  	spin_unlock(&p->fs->lock);
1594  }
1595  
1596  static void bprm_fill_uid(struct linux_binprm *bprm, struct file *file)
1597  {
1598  	/* Handle suid and sgid on files */
1599  	struct user_namespace *mnt_userns;
1600  	struct inode *inode = file_inode(file);
1601  	unsigned int mode;
1602  	vfsuid_t vfsuid;
1603  	vfsgid_t vfsgid;
1604  
1605  	if (!mnt_may_suid(file->f_path.mnt))
1606  		return;
1607  
1608  	if (task_no_new_privs(current))
1609  		return;
1610  
1611  	mode = READ_ONCE(inode->i_mode);
1612  	if (!(mode & (S_ISUID|S_ISGID)))
1613  		return;
1614  
1615  	mnt_userns = file_mnt_user_ns(file);
1616  
1617  	/* Be careful if suid/sgid is set */
1618  	inode_lock(inode);
1619  
1620  	/* reload atomically mode/uid/gid now that lock held */
1621  	mode = inode->i_mode;
1622  	vfsuid = i_uid_into_vfsuid(mnt_userns, inode);
1623  	vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
1624  	inode_unlock(inode);
1625  
1626  	/* We ignore suid/sgid if there are no mappings for them in the ns */
1627  	if (!vfsuid_has_mapping(bprm->cred->user_ns, vfsuid) ||
1628  	    !vfsgid_has_mapping(bprm->cred->user_ns, vfsgid))
1629  		return;
1630  
1631  	if (mode & S_ISUID) {
1632  		bprm->per_clear |= PER_CLEAR_ON_SETID;
1633  		bprm->cred->euid = vfsuid_into_kuid(vfsuid);
1634  	}
1635  
1636  	if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1637  		bprm->per_clear |= PER_CLEAR_ON_SETID;
1638  		bprm->cred->egid = vfsgid_into_kgid(vfsgid);
1639  	}
1640  }
1641  
1642  /*
1643   * Compute brpm->cred based upon the final binary.
1644   */
1645  static int bprm_creds_from_file(struct linux_binprm *bprm)
1646  {
1647  	/* Compute creds based on which file? */
1648  	struct file *file = bprm->execfd_creds ? bprm->executable : bprm->file;
1649  
1650  	bprm_fill_uid(bprm, file);
1651  	return security_bprm_creds_from_file(bprm, file);
1652  }
1653  
1654  /*
1655   * Fill the binprm structure from the inode.
1656   * Read the first BINPRM_BUF_SIZE bytes
1657   *
1658   * This may be called multiple times for binary chains (scripts for example).
1659   */
1660  static int prepare_binprm(struct linux_binprm *bprm)
1661  {
1662  	loff_t pos = 0;
1663  
1664  	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1665  	return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
1666  }
1667  
1668  /*
1669   * Arguments are '\0' separated strings found at the location bprm->p
1670   * points to; chop off the first by relocating brpm->p to right after
1671   * the first '\0' encountered.
1672   */
1673  int remove_arg_zero(struct linux_binprm *bprm)
1674  {
1675  	int ret = 0;
1676  	unsigned long offset;
1677  	char *kaddr;
1678  	struct page *page;
1679  
1680  	if (!bprm->argc)
1681  		return 0;
1682  
1683  	do {
1684  		offset = bprm->p & ~PAGE_MASK;
1685  		page = get_arg_page(bprm, bprm->p, 0);
1686  		if (!page) {
1687  			ret = -EFAULT;
1688  			goto out;
1689  		}
1690  		kaddr = kmap_local_page(page);
1691  
1692  		for (; offset < PAGE_SIZE && kaddr[offset];
1693  				offset++, bprm->p++)
1694  			;
1695  
1696  		kunmap_local(kaddr);
1697  		put_arg_page(page);
1698  	} while (offset == PAGE_SIZE);
1699  
1700  	bprm->p++;
1701  	bprm->argc--;
1702  	ret = 0;
1703  
1704  out:
1705  	return ret;
1706  }
1707  EXPORT_SYMBOL(remove_arg_zero);
1708  
1709  #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1710  /*
1711   * cycle the list of binary formats handler, until one recognizes the image
1712   */
1713  static int search_binary_handler(struct linux_binprm *bprm)
1714  {
1715  	bool need_retry = IS_ENABLED(CONFIG_MODULES);
1716  	struct linux_binfmt *fmt;
1717  	int retval;
1718  
1719  	retval = prepare_binprm(bprm);
1720  	if (retval < 0)
1721  		return retval;
1722  
1723  	retval = security_bprm_check(bprm);
1724  	if (retval)
1725  		return retval;
1726  
1727  	retval = -ENOENT;
1728   retry:
1729  	read_lock(&binfmt_lock);
1730  	list_for_each_entry(fmt, &formats, lh) {
1731  		if (!try_module_get(fmt->module))
1732  			continue;
1733  		read_unlock(&binfmt_lock);
1734  
1735  		retval = fmt->load_binary(bprm);
1736  
1737  		read_lock(&binfmt_lock);
1738  		put_binfmt(fmt);
1739  		if (bprm->point_of_no_return || (retval != -ENOEXEC)) {
1740  			read_unlock(&binfmt_lock);
1741  			return retval;
1742  		}
1743  	}
1744  	read_unlock(&binfmt_lock);
1745  
1746  	if (need_retry) {
1747  		if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1748  		    printable(bprm->buf[2]) && printable(bprm->buf[3]))
1749  			return retval;
1750  		if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1751  			return retval;
1752  		need_retry = false;
1753  		goto retry;
1754  	}
1755  
1756  	return retval;
1757  }
1758  
1759  /* binfmt handlers will call back into begin_new_exec() on success. */
1760  static int exec_binprm(struct linux_binprm *bprm)
1761  {
1762  	pid_t old_pid, old_vpid;
1763  	int ret, depth;
1764  
1765  	/* Need to fetch pid before load_binary changes it */
1766  	old_pid = current->pid;
1767  	rcu_read_lock();
1768  	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1769  	rcu_read_unlock();
1770  
1771  	/* This allows 4 levels of binfmt rewrites before failing hard. */
1772  	for (depth = 0;; depth++) {
1773  		struct file *exec;
1774  		if (depth > 5)
1775  			return -ELOOP;
1776  
1777  		ret = search_binary_handler(bprm);
1778  		if (ret < 0)
1779  			return ret;
1780  		if (!bprm->interpreter)
1781  			break;
1782  
1783  		exec = bprm->file;
1784  		bprm->file = bprm->interpreter;
1785  		bprm->interpreter = NULL;
1786  
1787  		allow_write_access(exec);
1788  		if (unlikely(bprm->have_execfd)) {
1789  			if (bprm->executable) {
1790  				fput(exec);
1791  				return -ENOEXEC;
1792  			}
1793  			bprm->executable = exec;
1794  		} else
1795  			fput(exec);
1796  	}
1797  
1798  	audit_bprm(bprm);
1799  	trace_sched_process_exec(current, old_pid, bprm);
1800  	ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1801  	proc_exec_connector(current);
1802  	return 0;
1803  }
1804  
1805  /*
1806   * sys_execve() executes a new program.
1807   */
1808  static int bprm_execve(struct linux_binprm *bprm,
1809  		       int fd, struct filename *filename, int flags)
1810  {
1811  	struct file *file;
1812  	int retval;
1813  
1814  	retval = prepare_bprm_creds(bprm);
1815  	if (retval)
1816  		return retval;
1817  
1818  	/*
1819  	 * Check for unsafe execution states before exec_binprm(), which
1820  	 * will call back into begin_new_exec(), into bprm_creds_from_file(),
1821  	 * where setuid-ness is evaluated.
1822  	 */
1823  	check_unsafe_exec(bprm);
1824  	current->in_execve = 1;
1825  
1826  	file = do_open_execat(fd, filename, flags);
1827  	retval = PTR_ERR(file);
1828  	if (IS_ERR(file))
1829  		goto out_unmark;
1830  
1831  	sched_exec();
1832  
1833  	bprm->file = file;
1834  	/*
1835  	 * Record that a name derived from an O_CLOEXEC fd will be
1836  	 * inaccessible after exec.  This allows the code in exec to
1837  	 * choose to fail when the executable is not mmaped into the
1838  	 * interpreter and an open file descriptor is not passed to
1839  	 * the interpreter.  This makes for a better user experience
1840  	 * than having the interpreter start and then immediately fail
1841  	 * when it finds the executable is inaccessible.
1842  	 */
1843  	if (bprm->fdpath && get_close_on_exec(fd))
1844  		bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1845  
1846  	/* Set the unchanging part of bprm->cred */
1847  	retval = security_bprm_creds_for_exec(bprm);
1848  	if (retval)
1849  		goto out;
1850  
1851  	retval = exec_binprm(bprm);
1852  	if (retval < 0)
1853  		goto out;
1854  
1855  	/* execve succeeded */
1856  	current->fs->in_exec = 0;
1857  	current->in_execve = 0;
1858  	rseq_execve(current);
1859  	acct_update_integrals(current);
1860  	task_numa_free(current, false);
1861  	return retval;
1862  
1863  out:
1864  	/*
1865  	 * If past the point of no return ensure the code never
1866  	 * returns to the userspace process.  Use an existing fatal
1867  	 * signal if present otherwise terminate the process with
1868  	 * SIGSEGV.
1869  	 */
1870  	if (bprm->point_of_no_return && !fatal_signal_pending(current))
1871  		force_fatal_sig(SIGSEGV);
1872  
1873  out_unmark:
1874  	current->fs->in_exec = 0;
1875  	current->in_execve = 0;
1876  
1877  	return retval;
1878  }
1879  
1880  static int do_execveat_common(int fd, struct filename *filename,
1881  			      struct user_arg_ptr argv,
1882  			      struct user_arg_ptr envp,
1883  			      int flags)
1884  {
1885  	struct linux_binprm *bprm;
1886  	int retval;
1887  
1888  	if (IS_ERR(filename))
1889  		return PTR_ERR(filename);
1890  
1891  	/*
1892  	 * We move the actual failure in case of RLIMIT_NPROC excess from
1893  	 * set*uid() to execve() because too many poorly written programs
1894  	 * don't check setuid() return code.  Here we additionally recheck
1895  	 * whether NPROC limit is still exceeded.
1896  	 */
1897  	if ((current->flags & PF_NPROC_EXCEEDED) &&
1898  	    is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
1899  		retval = -EAGAIN;
1900  		goto out_ret;
1901  	}
1902  
1903  	/* We're below the limit (still or again), so we don't want to make
1904  	 * further execve() calls fail. */
1905  	current->flags &= ~PF_NPROC_EXCEEDED;
1906  
1907  	bprm = alloc_bprm(fd, filename);
1908  	if (IS_ERR(bprm)) {
1909  		retval = PTR_ERR(bprm);
1910  		goto out_ret;
1911  	}
1912  
1913  	retval = count(argv, MAX_ARG_STRINGS);
1914  	if (retval == 0)
1915  		pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1916  			     current->comm, bprm->filename);
1917  	if (retval < 0)
1918  		goto out_free;
1919  	bprm->argc = retval;
1920  
1921  	retval = count(envp, MAX_ARG_STRINGS);
1922  	if (retval < 0)
1923  		goto out_free;
1924  	bprm->envc = retval;
1925  
1926  	retval = bprm_stack_limits(bprm);
1927  	if (retval < 0)
1928  		goto out_free;
1929  
1930  	retval = copy_string_kernel(bprm->filename, bprm);
1931  	if (retval < 0)
1932  		goto out_free;
1933  	bprm->exec = bprm->p;
1934  
1935  	retval = copy_strings(bprm->envc, envp, bprm);
1936  	if (retval < 0)
1937  		goto out_free;
1938  
1939  	retval = copy_strings(bprm->argc, argv, bprm);
1940  	if (retval < 0)
1941  		goto out_free;
1942  
1943  	/*
1944  	 * When argv is empty, add an empty string ("") as argv[0] to
1945  	 * ensure confused userspace programs that start processing
1946  	 * from argv[1] won't end up walking envp. See also
1947  	 * bprm_stack_limits().
1948  	 */
1949  	if (bprm->argc == 0) {
1950  		retval = copy_string_kernel("", bprm);
1951  		if (retval < 0)
1952  			goto out_free;
1953  		bprm->argc = 1;
1954  	}
1955  
1956  	retval = bprm_execve(bprm, fd, filename, flags);
1957  out_free:
1958  	free_bprm(bprm);
1959  
1960  out_ret:
1961  	putname(filename);
1962  	return retval;
1963  }
1964  
1965  int kernel_execve(const char *kernel_filename,
1966  		  const char *const *argv, const char *const *envp)
1967  {
1968  	struct filename *filename;
1969  	struct linux_binprm *bprm;
1970  	int fd = AT_FDCWD;
1971  	int retval;
1972  
1973  	/* It is non-sense for kernel threads to call execve */
1974  	if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
1975  		return -EINVAL;
1976  
1977  	filename = getname_kernel(kernel_filename);
1978  	if (IS_ERR(filename))
1979  		return PTR_ERR(filename);
1980  
1981  	bprm = alloc_bprm(fd, filename);
1982  	if (IS_ERR(bprm)) {
1983  		retval = PTR_ERR(bprm);
1984  		goto out_ret;
1985  	}
1986  
1987  	retval = count_strings_kernel(argv);
1988  	if (WARN_ON_ONCE(retval == 0))
1989  		retval = -EINVAL;
1990  	if (retval < 0)
1991  		goto out_free;
1992  	bprm->argc = retval;
1993  
1994  	retval = count_strings_kernel(envp);
1995  	if (retval < 0)
1996  		goto out_free;
1997  	bprm->envc = retval;
1998  
1999  	retval = bprm_stack_limits(bprm);
2000  	if (retval < 0)
2001  		goto out_free;
2002  
2003  	retval = copy_string_kernel(bprm->filename, bprm);
2004  	if (retval < 0)
2005  		goto out_free;
2006  	bprm->exec = bprm->p;
2007  
2008  	retval = copy_strings_kernel(bprm->envc, envp, bprm);
2009  	if (retval < 0)
2010  		goto out_free;
2011  
2012  	retval = copy_strings_kernel(bprm->argc, argv, bprm);
2013  	if (retval < 0)
2014  		goto out_free;
2015  
2016  	retval = bprm_execve(bprm, fd, filename, 0);
2017  out_free:
2018  	free_bprm(bprm);
2019  out_ret:
2020  	putname(filename);
2021  	return retval;
2022  }
2023  
2024  static int do_execve(struct filename *filename,
2025  	const char __user *const __user *__argv,
2026  	const char __user *const __user *__envp)
2027  {
2028  	struct user_arg_ptr argv = { .ptr.native = __argv };
2029  	struct user_arg_ptr envp = { .ptr.native = __envp };
2030  	return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2031  }
2032  
2033  static int do_execveat(int fd, struct filename *filename,
2034  		const char __user *const __user *__argv,
2035  		const char __user *const __user *__envp,
2036  		int flags)
2037  {
2038  	struct user_arg_ptr argv = { .ptr.native = __argv };
2039  	struct user_arg_ptr envp = { .ptr.native = __envp };
2040  
2041  	return do_execveat_common(fd, filename, argv, envp, flags);
2042  }
2043  
2044  #ifdef CONFIG_COMPAT
2045  static int compat_do_execve(struct filename *filename,
2046  	const compat_uptr_t __user *__argv,
2047  	const compat_uptr_t __user *__envp)
2048  {
2049  	struct user_arg_ptr argv = {
2050  		.is_compat = true,
2051  		.ptr.compat = __argv,
2052  	};
2053  	struct user_arg_ptr envp = {
2054  		.is_compat = true,
2055  		.ptr.compat = __envp,
2056  	};
2057  	return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
2058  }
2059  
2060  static int compat_do_execveat(int fd, struct filename *filename,
2061  			      const compat_uptr_t __user *__argv,
2062  			      const compat_uptr_t __user *__envp,
2063  			      int flags)
2064  {
2065  	struct user_arg_ptr argv = {
2066  		.is_compat = true,
2067  		.ptr.compat = __argv,
2068  	};
2069  	struct user_arg_ptr envp = {
2070  		.is_compat = true,
2071  		.ptr.compat = __envp,
2072  	};
2073  	return do_execveat_common(fd, filename, argv, envp, flags);
2074  }
2075  #endif
2076  
2077  void set_binfmt(struct linux_binfmt *new)
2078  {
2079  	struct mm_struct *mm = current->mm;
2080  
2081  	if (mm->binfmt)
2082  		module_put(mm->binfmt->module);
2083  
2084  	mm->binfmt = new;
2085  	if (new)
2086  		__module_get(new->module);
2087  }
2088  EXPORT_SYMBOL(set_binfmt);
2089  
2090  /*
2091   * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2092   */
2093  void set_dumpable(struct mm_struct *mm, int value)
2094  {
2095  	if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
2096  		return;
2097  
2098  	set_mask_bits(&mm->flags, MMF_DUMPABLE_MASK, value);
2099  }
2100  
2101  SYSCALL_DEFINE3(execve,
2102  		const char __user *, filename,
2103  		const char __user *const __user *, argv,
2104  		const char __user *const __user *, envp)
2105  {
2106  	return do_execve(getname(filename), argv, envp);
2107  }
2108  
2109  SYSCALL_DEFINE5(execveat,
2110  		int, fd, const char __user *, filename,
2111  		const char __user *const __user *, argv,
2112  		const char __user *const __user *, envp,
2113  		int, flags)
2114  {
2115  	return do_execveat(fd,
2116  			   getname_uflags(filename, flags),
2117  			   argv, envp, flags);
2118  }
2119  
2120  #ifdef CONFIG_COMPAT
2121  COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
2122  	const compat_uptr_t __user *, argv,
2123  	const compat_uptr_t __user *, envp)
2124  {
2125  	return compat_do_execve(getname(filename), argv, envp);
2126  }
2127  
2128  COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
2129  		       const char __user *, filename,
2130  		       const compat_uptr_t __user *, argv,
2131  		       const compat_uptr_t __user *, envp,
2132  		       int,  flags)
2133  {
2134  	return compat_do_execveat(fd,
2135  				  getname_uflags(filename, flags),
2136  				  argv, envp, flags);
2137  }
2138  #endif
2139  
2140  #ifdef CONFIG_SYSCTL
2141  
2142  static int proc_dointvec_minmax_coredump(struct ctl_table *table, int write,
2143  		void *buffer, size_t *lenp, loff_t *ppos)
2144  {
2145  	int error = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2146  
2147  	if (!error)
2148  		validate_coredump_safety();
2149  	return error;
2150  }
2151  
2152  static struct ctl_table fs_exec_sysctls[] = {
2153  	{
2154  		.procname	= "suid_dumpable",
2155  		.data		= &suid_dumpable,
2156  		.maxlen		= sizeof(int),
2157  		.mode		= 0644,
2158  		.proc_handler	= proc_dointvec_minmax_coredump,
2159  		.extra1		= SYSCTL_ZERO,
2160  		.extra2		= SYSCTL_TWO,
2161  	},
2162  	{ }
2163  };
2164  
2165  static int __init init_fs_exec_sysctls(void)
2166  {
2167  	register_sysctl_init("fs", fs_exec_sysctls);
2168  	return 0;
2169  }
2170  
2171  fs_initcall(init_fs_exec_sysctls);
2172  #endif /* CONFIG_SYSCTL */
2173