projects/linux·blob v4.3 · refs

1751 lines · 40.7 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/vmacache.h>
30#include <linux/stat.h>
31#include <linux/fcntl.h>
32#include <linux/swap.h>
33#include <linux/string.h>
34#include <linux/init.h>
35#include <linux/pagemap.h>
36#include <linux/perf_event.h>
37#include <linux/highmem.h>
38#include <linux/spinlock.h>
39#include <linux/key.h>
40#include <linux/personality.h>
41#include <linux/binfmts.h>
42#include <linux/utsname.h>
43#include <linux/pid_namespace.h>
44#include <linux/module.h>
45#include <linux/namei.h>
46#include <linux/mount.h>
47#include <linux/security.h>
48#include <linux/syscalls.h>
49#include <linux/tsacct_kern.h>
50#include <linux/cn_proc.h>
51#include <linux/audit.h>
52#include <linux/tracehook.h>
53#include <linux/kmod.h>
54#include <linux/fsnotify.h>
55#include <linux/fs_struct.h>
56#include <linux/pipe_fs_i.h>
57#include <linux/oom.h>
58#include <linux/compat.h>
59
60#include <asm/uaccess.h>
61#include <asm/mmu_context.h>
62#include <asm/tlb.h>
63
64#include <trace/events/task.h>
65#include "internal.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
101bool path_noexec(const struct path *path)
102{
103 return (path->mnt->mnt_flags & MNT_NOEXEC) ||
104 (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
105}
106
107#ifdef CONFIG_USELIB
108/*
109 * Note that a shared library must be both readable and executable due to
110 * security reasons.
111 *
112 * Also note that we take the address to load from from the file itself.
113 */
114SYSCALL_DEFINE1(uselib, const char __user *, library)
115{
116 struct linux_binfmt *fmt;
117 struct file *file;
118 struct filename *tmp = getname(library);
119 int error = PTR_ERR(tmp);
120 static const struct open_flags uselib_flags = {
121 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
122 .acc_mode = MAY_READ | MAY_EXEC | MAY_OPEN,
123 .intent = LOOKUP_OPEN,
124 .lookup_flags = LOOKUP_FOLLOW,
125 };
126
127 if (IS_ERR(tmp))
128 goto out;
129
130 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
131 putname(tmp);
132 error = PTR_ERR(file);
133 if (IS_ERR(file))
134 goto out;
135
136 error = -EINVAL;
137 if (!S_ISREG(file_inode(file)->i_mode))
138 goto exit;
139
140 error = -EACCES;
141 if (path_noexec(&file->f_path))
142 goto exit;
143
144 fsnotify_open(file);
145
146 error = -ENOEXEC;
147
148 read_lock(&binfmt_lock);
149 list_for_each_entry(fmt, &formats, lh) {
150 if (!fmt->load_shlib)
151 continue;
152 if (!try_module_get(fmt->module))
153 continue;
154 read_unlock(&binfmt_lock);
155 error = fmt->load_shlib(file);
156 read_lock(&binfmt_lock);
157 put_binfmt(fmt);
158 if (error != -ENOEXEC)
159 break;
160 }
161 read_unlock(&binfmt_lock);
162exit:
163 fput(file);
164out:
165 return error;
166}
167#endif /* #ifdef CONFIG_USELIB */
168
169#ifdef CONFIG_MMU
170/*
171 * The nascent bprm->mm is not visible until exec_mmap() but it can
172 * use a lot of memory, account these pages in current->mm temporary
173 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
174 * change the counter back via acct_arg_size(0).
175 */
176static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
177{
178 struct mm_struct *mm = current->mm;
179 long diff = (long)(pages - bprm->vma_pages);
180
181 if (!mm || !diff)
182 return;
183
184 bprm->vma_pages = pages;
185 add_mm_counter(mm, MM_ANONPAGES, diff);
186}
187
188static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
189 int write)
190{
191 struct page *page;
192 int ret;
193
194#ifdef CONFIG_STACK_GROWSUP
195 if (write) {
196 ret = expand_downwards(bprm->vma, pos);
197 if (ret < 0)
198 return NULL;
199 }
200#endif
201 ret = get_user_pages(current, bprm->mm, pos,
202 1, write, 1, &page, NULL);
203 if (ret <= 0)
204 return NULL;
205
206 if (write) {
207 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
208 struct rlimit *rlim;
209
210 acct_arg_size(bprm, size / PAGE_SIZE);
211
212 /*
213 * We've historically supported up to 32 pages (ARG_MAX)
214 * of argument strings even with small stacks
215 */
216 if (size <= ARG_MAX)
217 return page;
218
219 /*
220 * Limit to 1/4-th the stack size for the argv+env strings.
221 * This ensures that:
222 * - the remaining binfmt code will not run out of stack space,
223 * - the program will have a reasonable amount of stack left
224 * to work from.
225 */
226 rlim = current->signal->rlim;
227 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
228 put_page(page);
229 return NULL;
230 }
231 }
232
233 return page;
234}
235
236static void put_arg_page(struct page *page)
237{
238 put_page(page);
239}
240
241static void free_arg_page(struct linux_binprm *bprm, int i)
242{
243}
244
245static void free_arg_pages(struct linux_binprm *bprm)
246{
247}
248
249static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
250 struct page *page)
251{
252 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
253}
254
255static int __bprm_mm_init(struct linux_binprm *bprm)
256{
257 int err;
258 struct vm_area_struct *vma = NULL;
259 struct mm_struct *mm = bprm->mm;
260
261 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
262 if (!vma)
263 return -ENOMEM;
264
265 down_write(&mm->mmap_sem);
266 vma->vm_mm = mm;
267
268 /*
269 * Place the stack at the largest stack address the architecture
270 * supports. Later, we'll move this to an appropriate place. We don't
271 * use STACK_TOP because that can depend on attributes which aren't
272 * configured yet.
273 */
274 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
275 vma->vm_end = STACK_TOP_MAX;
276 vma->vm_start = vma->vm_end - PAGE_SIZE;
277 vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
278 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
279 INIT_LIST_HEAD(&vma->anon_vma_chain);
280
281 err = insert_vm_struct(mm, vma);
282 if (err)
283 goto err;
284
285 mm->stack_vm = mm->total_vm = 1;
286 arch_bprm_mm_init(mm, vma);
287 up_write(&mm->mmap_sem);
288 bprm->p = vma->vm_end - sizeof(void *);
289 return 0;
290err:
291 up_write(&mm->mmap_sem);
292 bprm->vma = NULL;
293 kmem_cache_free(vm_area_cachep, vma);
294 return err;
295}
296
297static bool valid_arg_len(struct linux_binprm *bprm, long len)
298{
299 return len <= MAX_ARG_STRLEN;
300}
301
302#else
303
304static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
305{
306}
307
308static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
309 int write)
310{
311 struct page *page;
312
313 page = bprm->page[pos / PAGE_SIZE];
314 if (!page && write) {
315 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
316 if (!page)
317 return NULL;
318 bprm->page[pos / PAGE_SIZE] = page;
319 }
320
321 return page;
322}
323
324static void put_arg_page(struct page *page)
325{
326}
327
328static void free_arg_page(struct linux_binprm *bprm, int i)
329{
330 if (bprm->page[i]) {
331 __free_page(bprm->page[i]);
332 bprm->page[i] = NULL;
333 }
334}
335
336static void free_arg_pages(struct linux_binprm *bprm)
337{
338 int i;
339
340 for (i = 0; i < MAX_ARG_PAGES; i++)
341 free_arg_page(bprm, i);
342}
343
344static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
345 struct page *page)
346{
347}
348
349static int __bprm_mm_init(struct linux_binprm *bprm)
350{
351 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
352 return 0;
353}
354
355static bool valid_arg_len(struct linux_binprm *bprm, long len)
356{
357 return len <= bprm->p;
358}
359
360#endif /* CONFIG_MMU */
361
362/*
363 * Create a new mm_struct and populate it with a temporary stack
364 * vm_area_struct. We don't have enough context at this point to set the stack
365 * flags, permissions, and offset, so we use temporary values. We'll update
366 * them later in setup_arg_pages().
367 */
368static int bprm_mm_init(struct linux_binprm *bprm)
369{
370 int err;
371 struct mm_struct *mm = NULL;
372
373 bprm->mm = mm = mm_alloc();
374 err = -ENOMEM;
375 if (!mm)
376 goto err;
377
378 err = __bprm_mm_init(bprm);
379 if (err)
380 goto err;
381
382 return 0;
383
384err:
385 if (mm) {
386 bprm->mm = NULL;
387 mmdrop(mm);
388 }
389
390 return err;
391}
392
393struct 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
405static 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 */
429static 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/*
456 * 'copy_strings()' copies argument/environment strings from the old
457 * processes's memory to the new process's stack. The call to get_user_pages()
458 * ensures the destination page is created and not swapped out.
459 */
460static int copy_strings(int argc, struct user_arg_ptr argv,
461 struct linux_binprm *bprm)
462{
463 struct page *kmapped_page = NULL;
464 char *kaddr = NULL;
465 unsigned long kpos = 0;
466 int ret;
467
468 while (argc-- > 0) {
469 const char __user *str;
470 int len;
471 unsigned long pos;
472
473 ret = -EFAULT;
474 str = get_user_arg_ptr(argv, argc);
475 if (IS_ERR(str))
476 goto out;
477
478 len = strnlen_user(str, MAX_ARG_STRLEN);
479 if (!len)
480 goto out;
481
482 ret = -E2BIG;
483 if (!valid_arg_len(bprm, len))
484 goto out;
485
486 /* We're going to work our way backwords. */
487 pos = bprm->p;
488 str += len;
489 bprm->p -= len;
490
491 while (len > 0) {
492 int offset, bytes_to_copy;
493
494 if (fatal_signal_pending(current)) {
495 ret = -ERESTARTNOHAND;
496 goto out;
497 }
498 cond_resched();
499
500 offset = pos % PAGE_SIZE;
501 if (offset == 0)
502 offset = PAGE_SIZE;
503
504 bytes_to_copy = offset;
505 if (bytes_to_copy > len)
506 bytes_to_copy = len;
507
508 offset -= bytes_to_copy;
509 pos -= bytes_to_copy;
510 str -= bytes_to_copy;
511 len -= bytes_to_copy;
512
513 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
514 struct page *page;
515
516 page = get_arg_page(bprm, pos, 1);
517 if (!page) {
518 ret = -E2BIG;
519 goto out;
520 }
521
522 if (kmapped_page) {
523 flush_kernel_dcache_page(kmapped_page);
524 kunmap(kmapped_page);
525 put_arg_page(kmapped_page);
526 }
527 kmapped_page = page;
528 kaddr = kmap(kmapped_page);
529 kpos = pos & PAGE_MASK;
530 flush_arg_page(bprm, kpos, kmapped_page);
531 }
532 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
533 ret = -EFAULT;
534 goto out;
535 }
536 }
537 }
538 ret = 0;
539out:
540 if (kmapped_page) {
541 flush_kernel_dcache_page(kmapped_page);
542 kunmap(kmapped_page);
543 put_arg_page(kmapped_page);
544 }
545 return ret;
546}
547
548/*
549 * Like copy_strings, but get argv and its values from kernel memory.
550 */
551int copy_strings_kernel(int argc, const char *const *__argv,
552 struct linux_binprm *bprm)
553{
554 int r;
555 mm_segment_t oldfs = get_fs();
556 struct user_arg_ptr argv = {
557 .ptr.native = (const char __user *const __user *)__argv,
558 };
559
560 set_fs(KERNEL_DS);
561 r = copy_strings(argc, argv, bprm);
562 set_fs(oldfs);
563
564 return r;
565}
566EXPORT_SYMBOL(copy_strings_kernel);
567
568#ifdef CONFIG_MMU
569
570/*
571 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
572 * the binfmt code determines where the new stack should reside, we shift it to
573 * its final location. The process proceeds as follows:
574 *
575 * 1) Use shift to calculate the new vma endpoints.
576 * 2) Extend vma to cover both the old and new ranges. This ensures the
577 * arguments passed to subsequent functions are consistent.
578 * 3) Move vma's page tables to the new range.
579 * 4) Free up any cleared pgd range.
580 * 5) Shrink the vma to cover only the new range.
581 */
582static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
583{
584 struct mm_struct *mm = vma->vm_mm;
585 unsigned long old_start = vma->vm_start;
586 unsigned long old_end = vma->vm_end;
587 unsigned long length = old_end - old_start;
588 unsigned long new_start = old_start - shift;
589 unsigned long new_end = old_end - shift;
590 struct mmu_gather tlb;
591
592 BUG_ON(new_start > new_end);
593
594 /*
595 * ensure there are no vmas between where we want to go
596 * and where we are
597 */
598 if (vma != find_vma(mm, new_start))
599 return -EFAULT;
600
601 /*
602 * cover the whole range: [new_start, old_end)
603 */
604 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
605 return -ENOMEM;
606
607 /*
608 * move the page tables downwards, on failure we rely on
609 * process cleanup to remove whatever mess we made.
610 */
611 if (length != move_page_tables(vma, old_start,
612 vma, new_start, length, false))
613 return -ENOMEM;
614
615 lru_add_drain();
616 tlb_gather_mmu(&tlb, mm, old_start, old_end);
617 if (new_end > old_start) {
618 /*
619 * when the old and new regions overlap clear from new_end.
620 */
621 free_pgd_range(&tlb, new_end, old_end, new_end,
622 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
623 } else {
624 /*
625 * otherwise, clean from old_start; this is done to not touch
626 * the address space in [new_end, old_start) some architectures
627 * have constraints on va-space that make this illegal (IA64) -
628 * for the others its just a little faster.
629 */
630 free_pgd_range(&tlb, old_start, old_end, new_end,
631 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
632 }
633 tlb_finish_mmu(&tlb, old_start, old_end);
634
635 /*
636 * Shrink the vma to just the new range. Always succeeds.
637 */
638 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
639
640 return 0;
641}
642
643/*
644 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
645 * the stack is optionally relocated, and some extra space is added.
646 */
647int setup_arg_pages(struct linux_binprm *bprm,
648 unsigned long stack_top,
649 int executable_stack)
650{
651 unsigned long ret;
652 unsigned long stack_shift;
653 struct mm_struct *mm = current->mm;
654 struct vm_area_struct *vma = bprm->vma;
655 struct vm_area_struct *prev = NULL;
656 unsigned long vm_flags;
657 unsigned long stack_base;
658 unsigned long stack_size;
659 unsigned long stack_expand;
660 unsigned long rlim_stack;
661
662#ifdef CONFIG_STACK_GROWSUP
663 /* Limit stack size */
664 stack_base = rlimit_max(RLIMIT_STACK);
665 if (stack_base > STACK_SIZE_MAX)
666 stack_base = STACK_SIZE_MAX;
667
668 /* Add space for stack randomization. */
669 stack_base += (STACK_RND_MASK << PAGE_SHIFT);
670
671 /* Make sure we didn't let the argument array grow too large. */
672 if (vma->vm_end - vma->vm_start > stack_base)
673 return -ENOMEM;
674
675 stack_base = PAGE_ALIGN(stack_top - stack_base);
676
677 stack_shift = vma->vm_start - stack_base;
678 mm->arg_start = bprm->p - stack_shift;
679 bprm->p = vma->vm_end - stack_shift;
680#else
681 stack_top = arch_align_stack(stack_top);
682 stack_top = PAGE_ALIGN(stack_top);
683
684 if (unlikely(stack_top < mmap_min_addr) ||
685 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
686 return -ENOMEM;
687
688 stack_shift = vma->vm_end - stack_top;
689
690 bprm->p -= stack_shift;
691 mm->arg_start = bprm->p;
692#endif
693
694 if (bprm->loader)
695 bprm->loader -= stack_shift;
696 bprm->exec -= stack_shift;
697
698 down_write(&mm->mmap_sem);
699 vm_flags = VM_STACK_FLAGS;
700
701 /*
702 * Adjust stack execute permissions; explicitly enable for
703 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
704 * (arch default) otherwise.
705 */
706 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
707 vm_flags |= VM_EXEC;
708 else if (executable_stack == EXSTACK_DISABLE_X)
709 vm_flags &= ~VM_EXEC;
710 vm_flags |= mm->def_flags;
711 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
712
713 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
714 vm_flags);
715 if (ret)
716 goto out_unlock;
717 BUG_ON(prev != vma);
718
719 /* Move stack pages down in memory. */
720 if (stack_shift) {
721 ret = shift_arg_pages(vma, stack_shift);
722 if (ret)
723 goto out_unlock;
724 }
725
726 /* mprotect_fixup is overkill to remove the temporary stack flags */
727 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
728
729 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
730 stack_size = vma->vm_end - vma->vm_start;
731 /*
732 * Align this down to a page boundary as expand_stack
733 * will align it up.
734 */
735 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
736#ifdef CONFIG_STACK_GROWSUP
737 if (stack_size + stack_expand > rlim_stack)
738 stack_base = vma->vm_start + rlim_stack;
739 else
740 stack_base = vma->vm_end + stack_expand;
741#else
742 if (stack_size + stack_expand > rlim_stack)
743 stack_base = vma->vm_end - rlim_stack;
744 else
745 stack_base = vma->vm_start - stack_expand;
746#endif
747 current->mm->start_stack = bprm->p;
748 ret = expand_stack(vma, stack_base);
749 if (ret)
750 ret = -EFAULT;
751
752out_unlock:
753 up_write(&mm->mmap_sem);
754 return ret;
755}
756EXPORT_SYMBOL(setup_arg_pages);
757
758#endif /* CONFIG_MMU */
759
760static struct file *do_open_execat(int fd, struct filename *name, int flags)
761{
762 struct file *file;
763 int err;
764 struct open_flags open_exec_flags = {
765 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
766 .acc_mode = MAY_EXEC | MAY_OPEN,
767 .intent = LOOKUP_OPEN,
768 .lookup_flags = LOOKUP_FOLLOW,
769 };
770
771 if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
772 return ERR_PTR(-EINVAL);
773 if (flags & AT_SYMLINK_NOFOLLOW)
774 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
775 if (flags & AT_EMPTY_PATH)
776 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
777
778 file = do_filp_open(fd, name, &open_exec_flags);
779 if (IS_ERR(file))
780 goto out;
781
782 err = -EACCES;
783 if (!S_ISREG(file_inode(file)->i_mode))
784 goto exit;
785
786 if (path_noexec(&file->f_path))
787 goto exit;
788
789 err = deny_write_access(file);
790 if (err)
791 goto exit;
792
793 if (name->name[0] != '\0')
794 fsnotify_open(file);
795
796out:
797 return file;
798
799exit:
800 fput(file);
801 return ERR_PTR(err);
802}
803
804struct file *open_exec(const char *name)
805{
806 struct filename *filename = getname_kernel(name);
807 struct file *f = ERR_CAST(filename);
808
809 if (!IS_ERR(filename)) {
810 f = do_open_execat(AT_FDCWD, filename, 0);
811 putname(filename);
812 }
813 return f;
814}
815EXPORT_SYMBOL(open_exec);
816
817int kernel_read(struct file *file, loff_t offset,
818 char *addr, unsigned long count)
819{
820 mm_segment_t old_fs;
821 loff_t pos = offset;
822 int result;
823
824 old_fs = get_fs();
825 set_fs(get_ds());
826 /* The cast to a user pointer is valid due to the set_fs() */
827 result = vfs_read(file, (void __user *)addr, count, &pos);
828 set_fs(old_fs);
829 return result;
830}
831
832EXPORT_SYMBOL(kernel_read);
833
834ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
835{
836 ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
837 if (res > 0)
838 flush_icache_range(addr, addr + len);
839 return res;
840}
841EXPORT_SYMBOL(read_code);
842
843static int exec_mmap(struct mm_struct *mm)
844{
845 struct task_struct *tsk;
846 struct mm_struct *old_mm, *active_mm;
847
848 /* Notify parent that we're no longer interested in the old VM */
849 tsk = current;
850 old_mm = current->mm;
851 mm_release(tsk, old_mm);
852
853 if (old_mm) {
854 sync_mm_rss(old_mm);
855 /*
856 * Make sure that if there is a core dump in progress
857 * for the old mm, we get out and die instead of going
858 * through with the exec. We must hold mmap_sem around
859 * checking core_state and changing tsk->mm.
860 */
861 down_read(&old_mm->mmap_sem);
862 if (unlikely(old_mm->core_state)) {
863 up_read(&old_mm->mmap_sem);
864 return -EINTR;
865 }
866 }
867 task_lock(tsk);
868 active_mm = tsk->active_mm;
869 tsk->mm = mm;
870 tsk->active_mm = mm;
871 activate_mm(active_mm, mm);
872 tsk->mm->vmacache_seqnum = 0;
873 vmacache_flush(tsk);
874 task_unlock(tsk);
875 if (old_mm) {
876 up_read(&old_mm->mmap_sem);
877 BUG_ON(active_mm != old_mm);
878 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
879 mm_update_next_owner(old_mm);
880 mmput(old_mm);
881 return 0;
882 }
883 mmdrop(active_mm);
884 return 0;
885}
886
887/*
888 * This function makes sure the current process has its own signal table,
889 * so that flush_signal_handlers can later reset the handlers without
890 * disturbing other processes. (Other processes might share the signal
891 * table via the CLONE_SIGHAND option to clone().)
892 */
893static int de_thread(struct task_struct *tsk)
894{
895 struct signal_struct *sig = tsk->signal;
896 struct sighand_struct *oldsighand = tsk->sighand;
897 spinlock_t *lock = &oldsighand->siglock;
898
899 if (thread_group_empty(tsk))
900 goto no_thread_group;
901
902 /*
903 * Kill all other threads in the thread group.
904 */
905 spin_lock_irq(lock);
906 if (signal_group_exit(sig)) {
907 /*
908 * Another group action in progress, just
909 * return so that the signal is processed.
910 */
911 spin_unlock_irq(lock);
912 return -EAGAIN;
913 }
914
915 sig->group_exit_task = tsk;
916 sig->notify_count = zap_other_threads(tsk);
917 if (!thread_group_leader(tsk))
918 sig->notify_count--;
919
920 while (sig->notify_count) {
921 __set_current_state(TASK_KILLABLE);
922 spin_unlock_irq(lock);
923 schedule();
924 if (unlikely(__fatal_signal_pending(tsk)))
925 goto killed;
926 spin_lock_irq(lock);
927 }
928 spin_unlock_irq(lock);
929
930 /*
931 * At this point all other threads have exited, all we have to
932 * do is to wait for the thread group leader to become inactive,
933 * and to assume its PID:
934 */
935 if (!thread_group_leader(tsk)) {
936 struct task_struct *leader = tsk->group_leader;
937
938 for (;;) {
939 threadgroup_change_begin(tsk);
940 write_lock_irq(&tasklist_lock);
941 /*
942 * Do this under tasklist_lock to ensure that
943 * exit_notify() can't miss ->group_exit_task
944 */
945 sig->notify_count = -1;
946 if (likely(leader->exit_state))
947 break;
948 __set_current_state(TASK_KILLABLE);
949 write_unlock_irq(&tasklist_lock);
950 threadgroup_change_end(tsk);
951 schedule();
952 if (unlikely(__fatal_signal_pending(tsk)))
953 goto killed;
954 }
955
956 /*
957 * The only record we have of the real-time age of a
958 * process, regardless of execs it's done, is start_time.
959 * All the past CPU time is accumulated in signal_struct
960 * from sister threads now dead. But in this non-leader
961 * exec, nothing survives from the original leader thread,
962 * whose birth marks the true age of this process now.
963 * When we take on its identity by switching to its PID, we
964 * also take its birthdate (always earlier than our own).
965 */
966 tsk->start_time = leader->start_time;
967 tsk->real_start_time = leader->real_start_time;
968
969 BUG_ON(!same_thread_group(leader, tsk));
970 BUG_ON(has_group_leader_pid(tsk));
971 /*
972 * An exec() starts a new thread group with the
973 * TGID of the previous thread group. Rehash the
974 * two threads with a switched PID, and release
975 * the former thread group leader:
976 */
977
978 /* Become a process group leader with the old leader's pid.
979 * The old leader becomes a thread of the this thread group.
980 * Note: The old leader also uses this pid until release_task
981 * is called. Odd but simple and correct.
982 */
983 tsk->pid = leader->pid;
984 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
985 transfer_pid(leader, tsk, PIDTYPE_PGID);
986 transfer_pid(leader, tsk, PIDTYPE_SID);
987
988 list_replace_rcu(&leader->tasks, &tsk->tasks);
989 list_replace_init(&leader->sibling, &tsk->sibling);
990
991 tsk->group_leader = tsk;
992 leader->group_leader = tsk;
993
994 tsk->exit_signal = SIGCHLD;
995 leader->exit_signal = -1;
996
997 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
998 leader->exit_state = EXIT_DEAD;
999
1000 /*
1001 * We are going to release_task()->ptrace_unlink() silently,
1002 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1003 * the tracer wont't block again waiting for this thread.
1004 */
1005 if (unlikely(leader->ptrace))
1006 __wake_up_parent(leader, leader->parent);
1007 write_unlock_irq(&tasklist_lock);
1008 threadgroup_change_end(tsk);
1009
1010 release_task(leader);
1011 }
1012
1013 sig->group_exit_task = NULL;
1014 sig->notify_count = 0;
1015
1016no_thread_group:
1017 /* we have changed execution domain */
1018 tsk->exit_signal = SIGCHLD;
1019
1020 exit_itimers(sig);
1021 flush_itimer_signals();
1022
1023 if (atomic_read(&oldsighand->count) != 1) {
1024 struct sighand_struct *newsighand;
1025 /*
1026 * This ->sighand is shared with the CLONE_SIGHAND
1027 * but not CLONE_THREAD task, switch to the new one.
1028 */
1029 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1030 if (!newsighand)
1031 return -ENOMEM;
1032
1033 atomic_set(&newsighand->count, 1);
1034 memcpy(newsighand->action, oldsighand->action,
1035 sizeof(newsighand->action));
1036
1037 write_lock_irq(&tasklist_lock);
1038 spin_lock(&oldsighand->siglock);
1039 rcu_assign_pointer(tsk->sighand, newsighand);
1040 spin_unlock(&oldsighand->siglock);
1041 write_unlock_irq(&tasklist_lock);
1042
1043 __cleanup_sighand(oldsighand);
1044 }
1045
1046 BUG_ON(!thread_group_leader(tsk));
1047 return 0;
1048
1049killed:
1050 /* protects against exit_notify() and __exit_signal() */
1051 read_lock(&tasklist_lock);
1052 sig->group_exit_task = NULL;
1053 sig->notify_count = 0;
1054 read_unlock(&tasklist_lock);
1055 return -EAGAIN;
1056}
1057
1058char *get_task_comm(char *buf, struct task_struct *tsk)
1059{
1060 /* buf must be at least sizeof(tsk->comm) in size */
1061 task_lock(tsk);
1062 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1063 task_unlock(tsk);
1064 return buf;
1065}
1066EXPORT_SYMBOL_GPL(get_task_comm);
1067
1068/*
1069 * These functions flushes out all traces of the currently running executable
1070 * so that a new one can be started
1071 */
1072
1073void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1074{
1075 task_lock(tsk);
1076 trace_task_rename(tsk, buf);
1077 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1078 task_unlock(tsk);
1079 perf_event_comm(tsk, exec);
1080}
1081
1082int flush_old_exec(struct linux_binprm * bprm)
1083{
1084 int retval;
1085
1086 /*
1087 * Make sure we have a private signal table and that
1088 * we are unassociated from the previous thread group.
1089 */
1090 retval = de_thread(current);
1091 if (retval)
1092 goto out;
1093
1094 /*
1095 * Must be called _before_ exec_mmap() as bprm->mm is
1096 * not visibile until then. This also enables the update
1097 * to be lockless.
1098 */
1099 set_mm_exe_file(bprm->mm, bprm->file);
1100
1101 /*
1102 * Release all of the old mmap stuff
1103 */
1104 acct_arg_size(bprm, 0);
1105 retval = exec_mmap(bprm->mm);
1106 if (retval)
1107 goto out;
1108
1109 bprm->mm = NULL; /* We're using it now */
1110
1111 set_fs(USER_DS);
1112 current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1113 PF_NOFREEZE | PF_NO_SETAFFINITY);
1114 flush_thread();
1115 current->personality &= ~bprm->per_clear;
1116
1117 return 0;
1118
1119out:
1120 return retval;
1121}
1122EXPORT_SYMBOL(flush_old_exec);
1123
1124void would_dump(struct linux_binprm *bprm, struct file *file)
1125{
1126 if (inode_permission(file_inode(file), MAY_READ) < 0)
1127 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1128}
1129EXPORT_SYMBOL(would_dump);
1130
1131void setup_new_exec(struct linux_binprm * bprm)
1132{
1133 arch_pick_mmap_layout(current->mm);
1134
1135 /* This is the point of no return */
1136 current->sas_ss_sp = current->sas_ss_size = 0;
1137
1138 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1139 set_dumpable(current->mm, SUID_DUMP_USER);
1140 else
1141 set_dumpable(current->mm, suid_dumpable);
1142
1143 perf_event_exec();
1144 __set_task_comm(current, kbasename(bprm->filename), true);
1145
1146 /* Set the new mm task size. We have to do that late because it may
1147 * depend on TIF_32BIT which is only updated in flush_thread() on
1148 * some architectures like powerpc
1149 */
1150 current->mm->task_size = TASK_SIZE;
1151
1152 /* install the new credentials */
1153 if (!uid_eq(bprm->cred->uid, current_euid()) ||
1154 !gid_eq(bprm->cred->gid, current_egid())) {
1155 current->pdeath_signal = 0;
1156 } else {
1157 would_dump(bprm, bprm->file);
1158 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1159 set_dumpable(current->mm, suid_dumpable);
1160 }
1161
1162 /* An exec changes our domain. We are no longer part of the thread
1163 group */
1164 current->self_exec_id++;
1165 flush_signal_handlers(current, 0);
1166 do_close_on_exec(current->files);
1167}
1168EXPORT_SYMBOL(setup_new_exec);
1169
1170/*
1171 * Prepare credentials and lock ->cred_guard_mutex.
1172 * install_exec_creds() commits the new creds and drops the lock.
1173 * Or, if exec fails before, free_bprm() should release ->cred and
1174 * and unlock.
1175 */
1176int prepare_bprm_creds(struct linux_binprm *bprm)
1177{
1178 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1179 return -ERESTARTNOINTR;
1180
1181 bprm->cred = prepare_exec_creds();
1182 if (likely(bprm->cred))
1183 return 0;
1184
1185 mutex_unlock(&current->signal->cred_guard_mutex);
1186 return -ENOMEM;
1187}
1188
1189static void free_bprm(struct linux_binprm *bprm)
1190{
1191 free_arg_pages(bprm);
1192 if (bprm->cred) {
1193 mutex_unlock(&current->signal->cred_guard_mutex);
1194 abort_creds(bprm->cred);
1195 }
1196 if (bprm->file) {
1197 allow_write_access(bprm->file);
1198 fput(bprm->file);
1199 }
1200 /* If a binfmt changed the interp, free it. */
1201 if (bprm->interp != bprm->filename)
1202 kfree(bprm->interp);
1203 kfree(bprm);
1204}
1205
1206int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1207{
1208 /* If a binfmt changed the interp, free it first. */
1209 if (bprm->interp != bprm->filename)
1210 kfree(bprm->interp);
1211 bprm->interp = kstrdup(interp, GFP_KERNEL);
1212 if (!bprm->interp)
1213 return -ENOMEM;
1214 return 0;
1215}
1216EXPORT_SYMBOL(bprm_change_interp);
1217
1218/*
1219 * install the new credentials for this executable
1220 */
1221void install_exec_creds(struct linux_binprm *bprm)
1222{
1223 security_bprm_committing_creds(bprm);
1224
1225 commit_creds(bprm->cred);
1226 bprm->cred = NULL;
1227
1228 /*
1229 * Disable monitoring for regular users
1230 * when executing setuid binaries. Must
1231 * wait until new credentials are committed
1232 * by commit_creds() above
1233 */
1234 if (get_dumpable(current->mm) != SUID_DUMP_USER)
1235 perf_event_exit_task(current);
1236 /*
1237 * cred_guard_mutex must be held at least to this point to prevent
1238 * ptrace_attach() from altering our determination of the task's
1239 * credentials; any time after this it may be unlocked.
1240 */
1241 security_bprm_committed_creds(bprm);
1242 mutex_unlock(&current->signal->cred_guard_mutex);
1243}
1244EXPORT_SYMBOL(install_exec_creds);
1245
1246/*
1247 * determine how safe it is to execute the proposed program
1248 * - the caller must hold ->cred_guard_mutex to protect against
1249 * PTRACE_ATTACH or seccomp thread-sync
1250 */
1251static void check_unsafe_exec(struct linux_binprm *bprm)
1252{
1253 struct task_struct *p = current, *t;
1254 unsigned n_fs;
1255
1256 if (p->ptrace) {
1257 if (p->ptrace & PT_PTRACE_CAP)
1258 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1259 else
1260 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1261 }
1262
1263 /*
1264 * This isn't strictly necessary, but it makes it harder for LSMs to
1265 * mess up.
1266 */
1267 if (task_no_new_privs(current))
1268 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1269
1270 t = p;
1271 n_fs = 1;
1272 spin_lock(&p->fs->lock);
1273 rcu_read_lock();
1274 while_each_thread(p, t) {
1275 if (t->fs == p->fs)
1276 n_fs++;
1277 }
1278 rcu_read_unlock();
1279
1280 if (p->fs->users > n_fs)
1281 bprm->unsafe |= LSM_UNSAFE_SHARE;
1282 else
1283 p->fs->in_exec = 1;
1284 spin_unlock(&p->fs->lock);
1285}
1286
1287static void bprm_fill_uid(struct linux_binprm *bprm)
1288{
1289 struct inode *inode;
1290 unsigned int mode;
1291 kuid_t uid;
1292 kgid_t gid;
1293
1294 /* clear any previous set[ug]id data from a previous binary */
1295 bprm->cred->euid = current_euid();
1296 bprm->cred->egid = current_egid();
1297
1298 if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
1299 return;
1300
1301 if (task_no_new_privs(current))
1302 return;
1303
1304 inode = file_inode(bprm->file);
1305 mode = READ_ONCE(inode->i_mode);
1306 if (!(mode & (S_ISUID|S_ISGID)))
1307 return;
1308
1309 /* Be careful if suid/sgid is set */
1310 mutex_lock(&inode->i_mutex);
1311
1312 /* reload atomically mode/uid/gid now that lock held */
1313 mode = inode->i_mode;
1314 uid = inode->i_uid;
1315 gid = inode->i_gid;
1316 mutex_unlock(&inode->i_mutex);
1317
1318 /* We ignore suid/sgid if there are no mappings for them in the ns */
1319 if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1320 !kgid_has_mapping(bprm->cred->user_ns, gid))
1321 return;
1322
1323 if (mode & S_ISUID) {
1324 bprm->per_clear |= PER_CLEAR_ON_SETID;
1325 bprm->cred->euid = uid;
1326 }
1327
1328 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1329 bprm->per_clear |= PER_CLEAR_ON_SETID;
1330 bprm->cred->egid = gid;
1331 }
1332}
1333
1334/*
1335 * Fill the binprm structure from the inode.
1336 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1337 *
1338 * This may be called multiple times for binary chains (scripts for example).
1339 */
1340int prepare_binprm(struct linux_binprm *bprm)
1341{
1342 int retval;
1343
1344 bprm_fill_uid(bprm);
1345
1346 /* fill in binprm security blob */
1347 retval = security_bprm_set_creds(bprm);
1348 if (retval)
1349 return retval;
1350 bprm->cred_prepared = 1;
1351
1352 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1353 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1354}
1355
1356EXPORT_SYMBOL(prepare_binprm);
1357
1358/*
1359 * Arguments are '\0' separated strings found at the location bprm->p
1360 * points to; chop off the first by relocating brpm->p to right after
1361 * the first '\0' encountered.
1362 */
1363int remove_arg_zero(struct linux_binprm *bprm)
1364{
1365 int ret = 0;
1366 unsigned long offset;
1367 char *kaddr;
1368 struct page *page;
1369
1370 if (!bprm->argc)
1371 return 0;
1372
1373 do {
1374 offset = bprm->p & ~PAGE_MASK;
1375 page = get_arg_page(bprm, bprm->p, 0);
1376 if (!page) {
1377 ret = -EFAULT;
1378 goto out;
1379 }
1380 kaddr = kmap_atomic(page);
1381
1382 for (; offset < PAGE_SIZE && kaddr[offset];
1383 offset++, bprm->p++)
1384 ;
1385
1386 kunmap_atomic(kaddr);
1387 put_arg_page(page);
1388
1389 if (offset == PAGE_SIZE)
1390 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1391 } while (offset == PAGE_SIZE);
1392
1393 bprm->p++;
1394 bprm->argc--;
1395 ret = 0;
1396
1397out:
1398 return ret;
1399}
1400EXPORT_SYMBOL(remove_arg_zero);
1401
1402#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1403/*
1404 * cycle the list of binary formats handler, until one recognizes the image
1405 */
1406int search_binary_handler(struct linux_binprm *bprm)
1407{
1408 bool need_retry = IS_ENABLED(CONFIG_MODULES);
1409 struct linux_binfmt *fmt;
1410 int retval;
1411
1412 /* This allows 4 levels of binfmt rewrites before failing hard. */
1413 if (bprm->recursion_depth > 5)
1414 return -ELOOP;
1415
1416 retval = security_bprm_check(bprm);
1417 if (retval)
1418 return retval;
1419
1420 retval = -ENOENT;
1421 retry:
1422 read_lock(&binfmt_lock);
1423 list_for_each_entry(fmt, &formats, lh) {
1424 if (!try_module_get(fmt->module))
1425 continue;
1426 read_unlock(&binfmt_lock);
1427 bprm->recursion_depth++;
1428 retval = fmt->load_binary(bprm);
1429 read_lock(&binfmt_lock);
1430 put_binfmt(fmt);
1431 bprm->recursion_depth--;
1432 if (retval < 0 && !bprm->mm) {
1433 /* we got to flush_old_exec() and failed after it */
1434 read_unlock(&binfmt_lock);
1435 force_sigsegv(SIGSEGV, current);
1436 return retval;
1437 }
1438 if (retval != -ENOEXEC || !bprm->file) {
1439 read_unlock(&binfmt_lock);
1440 return retval;
1441 }
1442 }
1443 read_unlock(&binfmt_lock);
1444
1445 if (need_retry) {
1446 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1447 printable(bprm->buf[2]) && printable(bprm->buf[3]))
1448 return retval;
1449 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1450 return retval;
1451 need_retry = false;
1452 goto retry;
1453 }
1454
1455 return retval;
1456}
1457EXPORT_SYMBOL(search_binary_handler);
1458
1459static int exec_binprm(struct linux_binprm *bprm)
1460{
1461 pid_t old_pid, old_vpid;
1462 int ret;
1463
1464 /* Need to fetch pid before load_binary changes it */
1465 old_pid = current->pid;
1466 rcu_read_lock();
1467 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1468 rcu_read_unlock();
1469
1470 ret = search_binary_handler(bprm);
1471 if (ret >= 0) {
1472 audit_bprm(bprm);
1473 trace_sched_process_exec(current, old_pid, bprm);
1474 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1475 proc_exec_connector(current);
1476 }
1477
1478 return ret;
1479}
1480
1481/*
1482 * sys_execve() executes a new program.
1483 */
1484static int do_execveat_common(int fd, struct filename *filename,
1485 struct user_arg_ptr argv,
1486 struct user_arg_ptr envp,
1487 int flags)
1488{
1489 char *pathbuf = NULL;
1490 struct linux_binprm *bprm;
1491 struct file *file;
1492 struct files_struct *displaced;
1493 int retval;
1494
1495 if (IS_ERR(filename))
1496 return PTR_ERR(filename);
1497
1498 /*
1499 * We move the actual failure in case of RLIMIT_NPROC excess from
1500 * set*uid() to execve() because too many poorly written programs
1501 * don't check setuid() return code. Here we additionally recheck
1502 * whether NPROC limit is still exceeded.
1503 */
1504 if ((current->flags & PF_NPROC_EXCEEDED) &&
1505 atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1506 retval = -EAGAIN;
1507 goto out_ret;
1508 }
1509
1510 /* We're below the limit (still or again), so we don't want to make
1511 * further execve() calls fail. */
1512 current->flags &= ~PF_NPROC_EXCEEDED;
1513
1514 retval = unshare_files(&displaced);
1515 if (retval)
1516 goto out_ret;
1517
1518 retval = -ENOMEM;
1519 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1520 if (!bprm)
1521 goto out_files;
1522
1523 retval = prepare_bprm_creds(bprm);
1524 if (retval)
1525 goto out_free;
1526
1527 check_unsafe_exec(bprm);
1528 current->in_execve = 1;
1529
1530 file = do_open_execat(fd, filename, flags);
1531 retval = PTR_ERR(file);
1532 if (IS_ERR(file))
1533 goto out_unmark;
1534
1535 sched_exec();
1536
1537 bprm->file = file;
1538 if (fd == AT_FDCWD || filename->name[0] == '/') {
1539 bprm->filename = filename->name;
1540 } else {
1541 if (filename->name[0] == '\0')
1542 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1543 else
1544 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1545 fd, filename->name);
1546 if (!pathbuf) {
1547 retval = -ENOMEM;
1548 goto out_unmark;
1549 }
1550 /*
1551 * Record that a name derived from an O_CLOEXEC fd will be
1552 * inaccessible after exec. Relies on having exclusive access to
1553 * current->files (due to unshare_files above).
1554 */
1555 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1556 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1557 bprm->filename = pathbuf;
1558 }
1559 bprm->interp = bprm->filename;
1560
1561 retval = bprm_mm_init(bprm);
1562 if (retval)
1563 goto out_unmark;
1564
1565 bprm->argc = count(argv, MAX_ARG_STRINGS);
1566 if ((retval = bprm->argc) < 0)
1567 goto out;
1568
1569 bprm->envc = count(envp, MAX_ARG_STRINGS);
1570 if ((retval = bprm->envc) < 0)
1571 goto out;
1572
1573 retval = prepare_binprm(bprm);
1574 if (retval < 0)
1575 goto out;
1576
1577 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1578 if (retval < 0)
1579 goto out;
1580
1581 bprm->exec = bprm->p;
1582 retval = copy_strings(bprm->envc, envp, bprm);
1583 if (retval < 0)
1584 goto out;
1585
1586 retval = copy_strings(bprm->argc, argv, bprm);
1587 if (retval < 0)
1588 goto out;
1589
1590 retval = exec_binprm(bprm);
1591 if (retval < 0)
1592 goto out;
1593
1594 /* execve succeeded */
1595 current->fs->in_exec = 0;
1596 current->in_execve = 0;
1597 acct_update_integrals(current);
1598 task_numa_free(current);
1599 free_bprm(bprm);
1600 kfree(pathbuf);
1601 putname(filename);
1602 if (displaced)
1603 put_files_struct(displaced);
1604 return retval;
1605
1606out:
1607 if (bprm->mm) {
1608 acct_arg_size(bprm, 0);
1609 mmput(bprm->mm);
1610 }
1611
1612out_unmark:
1613 current->fs->in_exec = 0;
1614 current->in_execve = 0;
1615
1616out_free:
1617 free_bprm(bprm);
1618 kfree(pathbuf);
1619
1620out_files:
1621 if (displaced)
1622 reset_files_struct(displaced);
1623out_ret:
1624 putname(filename);
1625 return retval;
1626}
1627
1628int do_execve(struct filename *filename,
1629 const char __user *const __user *__argv,
1630 const char __user *const __user *__envp)
1631{
1632 struct user_arg_ptr argv = { .ptr.native = __argv };
1633 struct user_arg_ptr envp = { .ptr.native = __envp };
1634 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1635}
1636
1637int do_execveat(int fd, struct filename *filename,
1638 const char __user *const __user *__argv,
1639 const char __user *const __user *__envp,
1640 int flags)
1641{
1642 struct user_arg_ptr argv = { .ptr.native = __argv };
1643 struct user_arg_ptr envp = { .ptr.native = __envp };
1644
1645 return do_execveat_common(fd, filename, argv, envp, flags);
1646}
1647
1648#ifdef CONFIG_COMPAT
1649static int compat_do_execve(struct filename *filename,
1650 const compat_uptr_t __user *__argv,
1651 const compat_uptr_t __user *__envp)
1652{
1653 struct user_arg_ptr argv = {
1654 .is_compat = true,
1655 .ptr.compat = __argv,
1656 };
1657 struct user_arg_ptr envp = {
1658 .is_compat = true,
1659 .ptr.compat = __envp,
1660 };
1661 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1662}
1663
1664static int compat_do_execveat(int fd, struct filename *filename,
1665 const compat_uptr_t __user *__argv,
1666 const compat_uptr_t __user *__envp,
1667 int flags)
1668{
1669 struct user_arg_ptr argv = {
1670 .is_compat = true,
1671 .ptr.compat = __argv,
1672 };
1673 struct user_arg_ptr envp = {
1674 .is_compat = true,
1675 .ptr.compat = __envp,
1676 };
1677 return do_execveat_common(fd, filename, argv, envp, flags);
1678}
1679#endif
1680
1681void set_binfmt(struct linux_binfmt *new)
1682{
1683 struct mm_struct *mm = current->mm;
1684
1685 if (mm->binfmt)
1686 module_put(mm->binfmt->module);
1687
1688 mm->binfmt = new;
1689 if (new)
1690 __module_get(new->module);
1691}
1692EXPORT_SYMBOL(set_binfmt);
1693
1694/*
1695 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1696 */
1697void set_dumpable(struct mm_struct *mm, int value)
1698{
1699 unsigned long old, new;
1700
1701 if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1702 return;
1703
1704 do {
1705 old = ACCESS_ONCE(mm->flags);
1706 new = (old & ~MMF_DUMPABLE_MASK) | value;
1707 } while (cmpxchg(&mm->flags, old, new) != old);
1708}
1709
1710SYSCALL_DEFINE3(execve,
1711 const char __user *, filename,
1712 const char __user *const __user *, argv,
1713 const char __user *const __user *, envp)
1714{
1715 return do_execve(getname(filename), argv, envp);
1716}
1717
1718SYSCALL_DEFINE5(execveat,
1719 int, fd, const char __user *, filename,
1720 const char __user *const __user *, argv,
1721 const char __user *const __user *, envp,
1722 int, flags)
1723{
1724 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1725
1726 return do_execveat(fd,
1727 getname_flags(filename, lookup_flags, NULL),
1728 argv, envp, flags);
1729}
1730
1731#ifdef CONFIG_COMPAT
1732COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1733 const compat_uptr_t __user *, argv,
1734 const compat_uptr_t __user *, envp)
1735{
1736 return compat_do_execve(getname(filename), argv, envp);
1737}
1738
1739COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1740 const char __user *, filename,
1741 const compat_uptr_t __user *, argv,
1742 const compat_uptr_t __user *, envp,
1743 int, flags)
1744{
1745 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1746
1747 return compat_do_execveat(fd,
1748 getname_flags(filename, lookup_flags, NULL),
1749 argv, envp, flags);
1750}
1751#endif