projects/linux·blob v4.6 · refs

1847 lines · 42.5 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#include <linux/vmalloc.h>
60
61#include <asm/uaccess.h>
62#include <asm/mmu_context.h>
63#include <asm/tlb.h>
64
65#include <trace/events/task.h>
66#include "internal.h"
67
68#include <trace/events/sched.h>
69
70int suid_dumpable = 0;
71
72static LIST_HEAD(formats);
73static DEFINE_RWLOCK(binfmt_lock);
74
75void __register_binfmt(struct linux_binfmt * fmt, int insert)
76{
77 BUG_ON(!fmt);
78 if (WARN_ON(!fmt->load_binary))
79 return;
80 write_lock(&binfmt_lock);
81 insert ? list_add(&fmt->lh, &formats) :
82 list_add_tail(&fmt->lh, &formats);
83 write_unlock(&binfmt_lock);
84}
85
86EXPORT_SYMBOL(__register_binfmt);
87
88void unregister_binfmt(struct linux_binfmt * fmt)
89{
90 write_lock(&binfmt_lock);
91 list_del(&fmt->lh);
92 write_unlock(&binfmt_lock);
93}
94
95EXPORT_SYMBOL(unregister_binfmt);
96
97static inline void put_binfmt(struct linux_binfmt * fmt)
98{
99 module_put(fmt->module);
100}
101
102bool path_noexec(const struct path *path)
103{
104 return (path->mnt->mnt_flags & MNT_NOEXEC) ||
105 (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
106}
107
108#ifdef CONFIG_USELIB
109/*
110 * Note that a shared library must be both readable and executable due to
111 * security reasons.
112 *
113 * Also note that we take the address to load from from the file itself.
114 */
115SYSCALL_DEFINE1(uselib, const char __user *, library)
116{
117 struct linux_binfmt *fmt;
118 struct file *file;
119 struct filename *tmp = getname(library);
120 int error = PTR_ERR(tmp);
121 static const struct open_flags uselib_flags = {
122 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
123 .acc_mode = MAY_READ | MAY_EXEC,
124 .intent = LOOKUP_OPEN,
125 .lookup_flags = LOOKUP_FOLLOW,
126 };
127
128 if (IS_ERR(tmp))
129 goto out;
130
131 file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
132 putname(tmp);
133 error = PTR_ERR(file);
134 if (IS_ERR(file))
135 goto out;
136
137 error = -EINVAL;
138 if (!S_ISREG(file_inode(file)->i_mode))
139 goto exit;
140
141 error = -EACCES;
142 if (path_noexec(&file->f_path))
143 goto exit;
144
145 fsnotify_open(file);
146
147 error = -ENOEXEC;
148
149 read_lock(&binfmt_lock);
150 list_for_each_entry(fmt, &formats, lh) {
151 if (!fmt->load_shlib)
152 continue;
153 if (!try_module_get(fmt->module))
154 continue;
155 read_unlock(&binfmt_lock);
156 error = fmt->load_shlib(file);
157 read_lock(&binfmt_lock);
158 put_binfmt(fmt);
159 if (error != -ENOEXEC)
160 break;
161 }
162 read_unlock(&binfmt_lock);
163exit:
164 fput(file);
165out:
166 return error;
167}
168#endif /* #ifdef CONFIG_USELIB */
169
170#ifdef CONFIG_MMU
171/*
172 * The nascent bprm->mm is not visible until exec_mmap() but it can
173 * use a lot of memory, account these pages in current->mm temporary
174 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
175 * change the counter back via acct_arg_size(0).
176 */
177static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
178{
179 struct mm_struct *mm = current->mm;
180 long diff = (long)(pages - bprm->vma_pages);
181
182 if (!mm || !diff)
183 return;
184
185 bprm->vma_pages = pages;
186 add_mm_counter(mm, MM_ANONPAGES, diff);
187}
188
189static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
190 int write)
191{
192 struct page *page;
193 int ret;
194
195#ifdef CONFIG_STACK_GROWSUP
196 if (write) {
197 ret = expand_downwards(bprm->vma, pos);
198 if (ret < 0)
199 return NULL;
200 }
201#endif
202 /*
203 * We are doing an exec(). 'current' is the process
204 * doing the exec and bprm->mm is the new process's mm.
205 */
206 ret = get_user_pages_remote(current, bprm->mm, pos, 1, write,
207 1, &page, NULL);
208 if (ret <= 0)
209 return NULL;
210
211 if (write) {
212 unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
213 struct rlimit *rlim;
214
215 acct_arg_size(bprm, size / PAGE_SIZE);
216
217 /*
218 * We've historically supported up to 32 pages (ARG_MAX)
219 * of argument strings even with small stacks
220 */
221 if (size <= ARG_MAX)
222 return page;
223
224 /*
225 * Limit to 1/4-th the stack size for the argv+env strings.
226 * This ensures that:
227 * - the remaining binfmt code will not run out of stack space,
228 * - the program will have a reasonable amount of stack left
229 * to work from.
230 */
231 rlim = current->signal->rlim;
232 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
233 put_page(page);
234 return NULL;
235 }
236 }
237
238 return page;
239}
240
241static void put_arg_page(struct page *page)
242{
243 put_page(page);
244}
245
246static void free_arg_page(struct linux_binprm *bprm, int i)
247{
248}
249
250static void free_arg_pages(struct linux_binprm *bprm)
251{
252}
253
254static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
255 struct page *page)
256{
257 flush_cache_page(bprm->vma, pos, page_to_pfn(page));
258}
259
260static int __bprm_mm_init(struct linux_binprm *bprm)
261{
262 int err;
263 struct vm_area_struct *vma = NULL;
264 struct mm_struct *mm = bprm->mm;
265
266 bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
267 if (!vma)
268 return -ENOMEM;
269
270 down_write(&mm->mmap_sem);
271 vma->vm_mm = mm;
272
273 /*
274 * Place the stack at the largest stack address the architecture
275 * supports. Later, we'll move this to an appropriate place. We don't
276 * use STACK_TOP because that can depend on attributes which aren't
277 * configured yet.
278 */
279 BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
280 vma->vm_end = STACK_TOP_MAX;
281 vma->vm_start = vma->vm_end - PAGE_SIZE;
282 vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
283 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
284 INIT_LIST_HEAD(&vma->anon_vma_chain);
285
286 err = insert_vm_struct(mm, vma);
287 if (err)
288 goto err;
289
290 mm->stack_vm = mm->total_vm = 1;
291 arch_bprm_mm_init(mm, vma);
292 up_write(&mm->mmap_sem);
293 bprm->p = vma->vm_end - sizeof(void *);
294 return 0;
295err:
296 up_write(&mm->mmap_sem);
297 bprm->vma = NULL;
298 kmem_cache_free(vm_area_cachep, vma);
299 return err;
300}
301
302static bool valid_arg_len(struct linux_binprm *bprm, long len)
303{
304 return len <= MAX_ARG_STRLEN;
305}
306
307#else
308
309static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
310{
311}
312
313static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
314 int write)
315{
316 struct page *page;
317
318 page = bprm->page[pos / PAGE_SIZE];
319 if (!page && write) {
320 page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
321 if (!page)
322 return NULL;
323 bprm->page[pos / PAGE_SIZE] = page;
324 }
325
326 return page;
327}
328
329static void put_arg_page(struct page *page)
330{
331}
332
333static void free_arg_page(struct linux_binprm *bprm, int i)
334{
335 if (bprm->page[i]) {
336 __free_page(bprm->page[i]);
337 bprm->page[i] = NULL;
338 }
339}
340
341static void free_arg_pages(struct linux_binprm *bprm)
342{
343 int i;
344
345 for (i = 0; i < MAX_ARG_PAGES; i++)
346 free_arg_page(bprm, i);
347}
348
349static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
350 struct page *page)
351{
352}
353
354static int __bprm_mm_init(struct linux_binprm *bprm)
355{
356 bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
357 return 0;
358}
359
360static bool valid_arg_len(struct linux_binprm *bprm, long len)
361{
362 return len <= bprm->p;
363}
364
365#endif /* CONFIG_MMU */
366
367/*
368 * Create a new mm_struct and populate it with a temporary stack
369 * vm_area_struct. We don't have enough context at this point to set the stack
370 * flags, permissions, and offset, so we use temporary values. We'll update
371 * them later in setup_arg_pages().
372 */
373static int bprm_mm_init(struct linux_binprm *bprm)
374{
375 int err;
376 struct mm_struct *mm = NULL;
377
378 bprm->mm = mm = mm_alloc();
379 err = -ENOMEM;
380 if (!mm)
381 goto err;
382
383 err = __bprm_mm_init(bprm);
384 if (err)
385 goto err;
386
387 return 0;
388
389err:
390 if (mm) {
391 bprm->mm = NULL;
392 mmdrop(mm);
393 }
394
395 return err;
396}
397
398struct user_arg_ptr {
399#ifdef CONFIG_COMPAT
400 bool is_compat;
401#endif
402 union {
403 const char __user *const __user *native;
404#ifdef CONFIG_COMPAT
405 const compat_uptr_t __user *compat;
406#endif
407 } ptr;
408};
409
410static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
411{
412 const char __user *native;
413
414#ifdef CONFIG_COMPAT
415 if (unlikely(argv.is_compat)) {
416 compat_uptr_t compat;
417
418 if (get_user(compat, argv.ptr.compat + nr))
419 return ERR_PTR(-EFAULT);
420
421 return compat_ptr(compat);
422 }
423#endif
424
425 if (get_user(native, argv.ptr.native + nr))
426 return ERR_PTR(-EFAULT);
427
428 return native;
429}
430
431/*
432 * count() counts the number of strings in array ARGV.
433 */
434static int count(struct user_arg_ptr argv, int max)
435{
436 int i = 0;
437
438 if (argv.ptr.native != NULL) {
439 for (;;) {
440 const char __user *p = get_user_arg_ptr(argv, i);
441
442 if (!p)
443 break;
444
445 if (IS_ERR(p))
446 return -EFAULT;
447
448 if (i >= max)
449 return -E2BIG;
450 ++i;
451
452 if (fatal_signal_pending(current))
453 return -ERESTARTNOHAND;
454 cond_resched();
455 }
456 }
457 return i;
458}
459
460/*
461 * 'copy_strings()' copies argument/environment strings from the old
462 * processes's memory to the new process's stack. The call to get_user_pages()
463 * ensures the destination page is created and not swapped out.
464 */
465static int copy_strings(int argc, struct user_arg_ptr argv,
466 struct linux_binprm *bprm)
467{
468 struct page *kmapped_page = NULL;
469 char *kaddr = NULL;
470 unsigned long kpos = 0;
471 int ret;
472
473 while (argc-- > 0) {
474 const char __user *str;
475 int len;
476 unsigned long pos;
477
478 ret = -EFAULT;
479 str = get_user_arg_ptr(argv, argc);
480 if (IS_ERR(str))
481 goto out;
482
483 len = strnlen_user(str, MAX_ARG_STRLEN);
484 if (!len)
485 goto out;
486
487 ret = -E2BIG;
488 if (!valid_arg_len(bprm, len))
489 goto out;
490
491 /* We're going to work our way backwords. */
492 pos = bprm->p;
493 str += len;
494 bprm->p -= len;
495
496 while (len > 0) {
497 int offset, bytes_to_copy;
498
499 if (fatal_signal_pending(current)) {
500 ret = -ERESTARTNOHAND;
501 goto out;
502 }
503 cond_resched();
504
505 offset = pos % PAGE_SIZE;
506 if (offset == 0)
507 offset = PAGE_SIZE;
508
509 bytes_to_copy = offset;
510 if (bytes_to_copy > len)
511 bytes_to_copy = len;
512
513 offset -= bytes_to_copy;
514 pos -= bytes_to_copy;
515 str -= bytes_to_copy;
516 len -= bytes_to_copy;
517
518 if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
519 struct page *page;
520
521 page = get_arg_page(bprm, pos, 1);
522 if (!page) {
523 ret = -E2BIG;
524 goto out;
525 }
526
527 if (kmapped_page) {
528 flush_kernel_dcache_page(kmapped_page);
529 kunmap(kmapped_page);
530 put_arg_page(kmapped_page);
531 }
532 kmapped_page = page;
533 kaddr = kmap(kmapped_page);
534 kpos = pos & PAGE_MASK;
535 flush_arg_page(bprm, kpos, kmapped_page);
536 }
537 if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
538 ret = -EFAULT;
539 goto out;
540 }
541 }
542 }
543 ret = 0;
544out:
545 if (kmapped_page) {
546 flush_kernel_dcache_page(kmapped_page);
547 kunmap(kmapped_page);
548 put_arg_page(kmapped_page);
549 }
550 return ret;
551}
552
553/*
554 * Like copy_strings, but get argv and its values from kernel memory.
555 */
556int copy_strings_kernel(int argc, const char *const *__argv,
557 struct linux_binprm *bprm)
558{
559 int r;
560 mm_segment_t oldfs = get_fs();
561 struct user_arg_ptr argv = {
562 .ptr.native = (const char __user *const __user *)__argv,
563 };
564
565 set_fs(KERNEL_DS);
566 r = copy_strings(argc, argv, bprm);
567 set_fs(oldfs);
568
569 return r;
570}
571EXPORT_SYMBOL(copy_strings_kernel);
572
573#ifdef CONFIG_MMU
574
575/*
576 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
577 * the binfmt code determines where the new stack should reside, we shift it to
578 * its final location. The process proceeds as follows:
579 *
580 * 1) Use shift to calculate the new vma endpoints.
581 * 2) Extend vma to cover both the old and new ranges. This ensures the
582 * arguments passed to subsequent functions are consistent.
583 * 3) Move vma's page tables to the new range.
584 * 4) Free up any cleared pgd range.
585 * 5) Shrink the vma to cover only the new range.
586 */
587static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
588{
589 struct mm_struct *mm = vma->vm_mm;
590 unsigned long old_start = vma->vm_start;
591 unsigned long old_end = vma->vm_end;
592 unsigned long length = old_end - old_start;
593 unsigned long new_start = old_start - shift;
594 unsigned long new_end = old_end - shift;
595 struct mmu_gather tlb;
596
597 BUG_ON(new_start > new_end);
598
599 /*
600 * ensure there are no vmas between where we want to go
601 * and where we are
602 */
603 if (vma != find_vma(mm, new_start))
604 return -EFAULT;
605
606 /*
607 * cover the whole range: [new_start, old_end)
608 */
609 if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
610 return -ENOMEM;
611
612 /*
613 * move the page tables downwards, on failure we rely on
614 * process cleanup to remove whatever mess we made.
615 */
616 if (length != move_page_tables(vma, old_start,
617 vma, new_start, length, false))
618 return -ENOMEM;
619
620 lru_add_drain();
621 tlb_gather_mmu(&tlb, mm, old_start, old_end);
622 if (new_end > old_start) {
623 /*
624 * when the old and new regions overlap clear from new_end.
625 */
626 free_pgd_range(&tlb, new_end, old_end, new_end,
627 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
628 } else {
629 /*
630 * otherwise, clean from old_start; this is done to not touch
631 * the address space in [new_end, old_start) some architectures
632 * have constraints on va-space that make this illegal (IA64) -
633 * for the others its just a little faster.
634 */
635 free_pgd_range(&tlb, old_start, old_end, new_end,
636 vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
637 }
638 tlb_finish_mmu(&tlb, old_start, old_end);
639
640 /*
641 * Shrink the vma to just the new range. Always succeeds.
642 */
643 vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
644
645 return 0;
646}
647
648/*
649 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
650 * the stack is optionally relocated, and some extra space is added.
651 */
652int setup_arg_pages(struct linux_binprm *bprm,
653 unsigned long stack_top,
654 int executable_stack)
655{
656 unsigned long ret;
657 unsigned long stack_shift;
658 struct mm_struct *mm = current->mm;
659 struct vm_area_struct *vma = bprm->vma;
660 struct vm_area_struct *prev = NULL;
661 unsigned long vm_flags;
662 unsigned long stack_base;
663 unsigned long stack_size;
664 unsigned long stack_expand;
665 unsigned long rlim_stack;
666
667#ifdef CONFIG_STACK_GROWSUP
668 /* Limit stack size */
669 stack_base = rlimit_max(RLIMIT_STACK);
670 if (stack_base > STACK_SIZE_MAX)
671 stack_base = STACK_SIZE_MAX;
672
673 /* Add space for stack randomization. */
674 stack_base += (STACK_RND_MASK << PAGE_SHIFT);
675
676 /* Make sure we didn't let the argument array grow too large. */
677 if (vma->vm_end - vma->vm_start > stack_base)
678 return -ENOMEM;
679
680 stack_base = PAGE_ALIGN(stack_top - stack_base);
681
682 stack_shift = vma->vm_start - stack_base;
683 mm->arg_start = bprm->p - stack_shift;
684 bprm->p = vma->vm_end - stack_shift;
685#else
686 stack_top = arch_align_stack(stack_top);
687 stack_top = PAGE_ALIGN(stack_top);
688
689 if (unlikely(stack_top < mmap_min_addr) ||
690 unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
691 return -ENOMEM;
692
693 stack_shift = vma->vm_end - stack_top;
694
695 bprm->p -= stack_shift;
696 mm->arg_start = bprm->p;
697#endif
698
699 if (bprm->loader)
700 bprm->loader -= stack_shift;
701 bprm->exec -= stack_shift;
702
703 down_write(&mm->mmap_sem);
704 vm_flags = VM_STACK_FLAGS;
705
706 /*
707 * Adjust stack execute permissions; explicitly enable for
708 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
709 * (arch default) otherwise.
710 */
711 if (unlikely(executable_stack == EXSTACK_ENABLE_X))
712 vm_flags |= VM_EXEC;
713 else if (executable_stack == EXSTACK_DISABLE_X)
714 vm_flags &= ~VM_EXEC;
715 vm_flags |= mm->def_flags;
716 vm_flags |= VM_STACK_INCOMPLETE_SETUP;
717
718 ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
719 vm_flags);
720 if (ret)
721 goto out_unlock;
722 BUG_ON(prev != vma);
723
724 /* Move stack pages down in memory. */
725 if (stack_shift) {
726 ret = shift_arg_pages(vma, stack_shift);
727 if (ret)
728 goto out_unlock;
729 }
730
731 /* mprotect_fixup is overkill to remove the temporary stack flags */
732 vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
733
734 stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
735 stack_size = vma->vm_end - vma->vm_start;
736 /*
737 * Align this down to a page boundary as expand_stack
738 * will align it up.
739 */
740 rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK;
741#ifdef CONFIG_STACK_GROWSUP
742 if (stack_size + stack_expand > rlim_stack)
743 stack_base = vma->vm_start + rlim_stack;
744 else
745 stack_base = vma->vm_end + stack_expand;
746#else
747 if (stack_size + stack_expand > rlim_stack)
748 stack_base = vma->vm_end - rlim_stack;
749 else
750 stack_base = vma->vm_start - stack_expand;
751#endif
752 current->mm->start_stack = bprm->p;
753 ret = expand_stack(vma, stack_base);
754 if (ret)
755 ret = -EFAULT;
756
757out_unlock:
758 up_write(&mm->mmap_sem);
759 return ret;
760}
761EXPORT_SYMBOL(setup_arg_pages);
762
763#endif /* CONFIG_MMU */
764
765static struct file *do_open_execat(int fd, struct filename *name, int flags)
766{
767 struct file *file;
768 int err;
769 struct open_flags open_exec_flags = {
770 .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
771 .acc_mode = MAY_EXEC,
772 .intent = LOOKUP_OPEN,
773 .lookup_flags = LOOKUP_FOLLOW,
774 };
775
776 if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
777 return ERR_PTR(-EINVAL);
778 if (flags & AT_SYMLINK_NOFOLLOW)
779 open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
780 if (flags & AT_EMPTY_PATH)
781 open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
782
783 file = do_filp_open(fd, name, &open_exec_flags);
784 if (IS_ERR(file))
785 goto out;
786
787 err = -EACCES;
788 if (!S_ISREG(file_inode(file)->i_mode))
789 goto exit;
790
791 if (path_noexec(&file->f_path))
792 goto exit;
793
794 err = deny_write_access(file);
795 if (err)
796 goto exit;
797
798 if (name->name[0] != '\0')
799 fsnotify_open(file);
800
801out:
802 return file;
803
804exit:
805 fput(file);
806 return ERR_PTR(err);
807}
808
809struct file *open_exec(const char *name)
810{
811 struct filename *filename = getname_kernel(name);
812 struct file *f = ERR_CAST(filename);
813
814 if (!IS_ERR(filename)) {
815 f = do_open_execat(AT_FDCWD, filename, 0);
816 putname(filename);
817 }
818 return f;
819}
820EXPORT_SYMBOL(open_exec);
821
822int kernel_read(struct file *file, loff_t offset,
823 char *addr, unsigned long count)
824{
825 mm_segment_t old_fs;
826 loff_t pos = offset;
827 int result;
828
829 old_fs = get_fs();
830 set_fs(get_ds());
831 /* The cast to a user pointer is valid due to the set_fs() */
832 result = vfs_read(file, (void __user *)addr, count, &pos);
833 set_fs(old_fs);
834 return result;
835}
836
837EXPORT_SYMBOL(kernel_read);
838
839int kernel_read_file(struct file *file, void **buf, loff_t *size,
840 loff_t max_size, enum kernel_read_file_id id)
841{
842 loff_t i_size, pos;
843 ssize_t bytes = 0;
844 int ret;
845
846 if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
847 return -EINVAL;
848
849 ret = security_kernel_read_file(file, id);
850 if (ret)
851 return ret;
852
853 i_size = i_size_read(file_inode(file));
854 if (max_size > 0 && i_size > max_size)
855 return -EFBIG;
856 if (i_size <= 0)
857 return -EINVAL;
858
859 *buf = vmalloc(i_size);
860 if (!*buf)
861 return -ENOMEM;
862
863 pos = 0;
864 while (pos < i_size) {
865 bytes = kernel_read(file, pos, (char *)(*buf) + pos,
866 i_size - pos);
867 if (bytes < 0) {
868 ret = bytes;
869 goto out;
870 }
871
872 if (bytes == 0)
873 break;
874 pos += bytes;
875 }
876
877 if (pos != i_size) {
878 ret = -EIO;
879 goto out;
880 }
881
882 ret = security_kernel_post_read_file(file, *buf, i_size, id);
883 if (!ret)
884 *size = pos;
885
886out:
887 if (ret < 0) {
888 vfree(*buf);
889 *buf = NULL;
890 }
891 return ret;
892}
893EXPORT_SYMBOL_GPL(kernel_read_file);
894
895int kernel_read_file_from_path(char *path, void **buf, loff_t *size,
896 loff_t max_size, enum kernel_read_file_id id)
897{
898 struct file *file;
899 int ret;
900
901 if (!path || !*path)
902 return -EINVAL;
903
904 file = filp_open(path, O_RDONLY, 0);
905 if (IS_ERR(file))
906 return PTR_ERR(file);
907
908 ret = kernel_read_file(file, buf, size, max_size, id);
909 fput(file);
910 return ret;
911}
912EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
913
914int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
915 enum kernel_read_file_id id)
916{
917 struct fd f = fdget(fd);
918 int ret = -EBADF;
919
920 if (!f.file)
921 goto out;
922
923 ret = kernel_read_file(f.file, buf, size, max_size, id);
924out:
925 fdput(f);
926 return ret;
927}
928EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
929
930ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
931{
932 ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
933 if (res > 0)
934 flush_icache_range(addr, addr + len);
935 return res;
936}
937EXPORT_SYMBOL(read_code);
938
939static int exec_mmap(struct mm_struct *mm)
940{
941 struct task_struct *tsk;
942 struct mm_struct *old_mm, *active_mm;
943
944 /* Notify parent that we're no longer interested in the old VM */
945 tsk = current;
946 old_mm = current->mm;
947 mm_release(tsk, old_mm);
948
949 if (old_mm) {
950 sync_mm_rss(old_mm);
951 /*
952 * Make sure that if there is a core dump in progress
953 * for the old mm, we get out and die instead of going
954 * through with the exec. We must hold mmap_sem around
955 * checking core_state and changing tsk->mm.
956 */
957 down_read(&old_mm->mmap_sem);
958 if (unlikely(old_mm->core_state)) {
959 up_read(&old_mm->mmap_sem);
960 return -EINTR;
961 }
962 }
963 task_lock(tsk);
964 active_mm = tsk->active_mm;
965 tsk->mm = mm;
966 tsk->active_mm = mm;
967 activate_mm(active_mm, mm);
968 tsk->mm->vmacache_seqnum = 0;
969 vmacache_flush(tsk);
970 task_unlock(tsk);
971 if (old_mm) {
972 up_read(&old_mm->mmap_sem);
973 BUG_ON(active_mm != old_mm);
974 setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
975 mm_update_next_owner(old_mm);
976 mmput(old_mm);
977 return 0;
978 }
979 mmdrop(active_mm);
980 return 0;
981}
982
983/*
984 * This function makes sure the current process has its own signal table,
985 * so that flush_signal_handlers can later reset the handlers without
986 * disturbing other processes. (Other processes might share the signal
987 * table via the CLONE_SIGHAND option to clone().)
988 */
989static int de_thread(struct task_struct *tsk)
990{
991 struct signal_struct *sig = tsk->signal;
992 struct sighand_struct *oldsighand = tsk->sighand;
993 spinlock_t *lock = &oldsighand->siglock;
994
995 if (thread_group_empty(tsk))
996 goto no_thread_group;
997
998 /*
999 * Kill all other threads in the thread group.
1000 */
1001 spin_lock_irq(lock);
1002 if (signal_group_exit(sig)) {
1003 /*
1004 * Another group action in progress, just
1005 * return so that the signal is processed.
1006 */
1007 spin_unlock_irq(lock);
1008 return -EAGAIN;
1009 }
1010
1011 sig->group_exit_task = tsk;
1012 sig->notify_count = zap_other_threads(tsk);
1013 if (!thread_group_leader(tsk))
1014 sig->notify_count--;
1015
1016 while (sig->notify_count) {
1017 __set_current_state(TASK_KILLABLE);
1018 spin_unlock_irq(lock);
1019 schedule();
1020 if (unlikely(__fatal_signal_pending(tsk)))
1021 goto killed;
1022 spin_lock_irq(lock);
1023 }
1024 spin_unlock_irq(lock);
1025
1026 /*
1027 * At this point all other threads have exited, all we have to
1028 * do is to wait for the thread group leader to become inactive,
1029 * and to assume its PID:
1030 */
1031 if (!thread_group_leader(tsk)) {
1032 struct task_struct *leader = tsk->group_leader;
1033
1034 for (;;) {
1035 threadgroup_change_begin(tsk);
1036 write_lock_irq(&tasklist_lock);
1037 /*
1038 * Do this under tasklist_lock to ensure that
1039 * exit_notify() can't miss ->group_exit_task
1040 */
1041 sig->notify_count = -1;
1042 if (likely(leader->exit_state))
1043 break;
1044 __set_current_state(TASK_KILLABLE);
1045 write_unlock_irq(&tasklist_lock);
1046 threadgroup_change_end(tsk);
1047 schedule();
1048 if (unlikely(__fatal_signal_pending(tsk)))
1049 goto killed;
1050 }
1051
1052 /*
1053 * The only record we have of the real-time age of a
1054 * process, regardless of execs it's done, is start_time.
1055 * All the past CPU time is accumulated in signal_struct
1056 * from sister threads now dead. But in this non-leader
1057 * exec, nothing survives from the original leader thread,
1058 * whose birth marks the true age of this process now.
1059 * When we take on its identity by switching to its PID, we
1060 * also take its birthdate (always earlier than our own).
1061 */
1062 tsk->start_time = leader->start_time;
1063 tsk->real_start_time = leader->real_start_time;
1064
1065 BUG_ON(!same_thread_group(leader, tsk));
1066 BUG_ON(has_group_leader_pid(tsk));
1067 /*
1068 * An exec() starts a new thread group with the
1069 * TGID of the previous thread group. Rehash the
1070 * two threads with a switched PID, and release
1071 * the former thread group leader:
1072 */
1073
1074 /* Become a process group leader with the old leader's pid.
1075 * The old leader becomes a thread of the this thread group.
1076 * Note: The old leader also uses this pid until release_task
1077 * is called. Odd but simple and correct.
1078 */
1079 tsk->pid = leader->pid;
1080 change_pid(tsk, PIDTYPE_PID, task_pid(leader));
1081 transfer_pid(leader, tsk, PIDTYPE_PGID);
1082 transfer_pid(leader, tsk, PIDTYPE_SID);
1083
1084 list_replace_rcu(&leader->tasks, &tsk->tasks);
1085 list_replace_init(&leader->sibling, &tsk->sibling);
1086
1087 tsk->group_leader = tsk;
1088 leader->group_leader = tsk;
1089
1090 tsk->exit_signal = SIGCHLD;
1091 leader->exit_signal = -1;
1092
1093 BUG_ON(leader->exit_state != EXIT_ZOMBIE);
1094 leader->exit_state = EXIT_DEAD;
1095
1096 /*
1097 * We are going to release_task()->ptrace_unlink() silently,
1098 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1099 * the tracer wont't block again waiting for this thread.
1100 */
1101 if (unlikely(leader->ptrace))
1102 __wake_up_parent(leader, leader->parent);
1103 write_unlock_irq(&tasklist_lock);
1104 threadgroup_change_end(tsk);
1105
1106 release_task(leader);
1107 }
1108
1109 sig->group_exit_task = NULL;
1110 sig->notify_count = 0;
1111
1112no_thread_group:
1113 /* we have changed execution domain */
1114 tsk->exit_signal = SIGCHLD;
1115
1116 exit_itimers(sig);
1117 flush_itimer_signals();
1118
1119 if (atomic_read(&oldsighand->count) != 1) {
1120 struct sighand_struct *newsighand;
1121 /*
1122 * This ->sighand is shared with the CLONE_SIGHAND
1123 * but not CLONE_THREAD task, switch to the new one.
1124 */
1125 newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1126 if (!newsighand)
1127 return -ENOMEM;
1128
1129 atomic_set(&newsighand->count, 1);
1130 memcpy(newsighand->action, oldsighand->action,
1131 sizeof(newsighand->action));
1132
1133 write_lock_irq(&tasklist_lock);
1134 spin_lock(&oldsighand->siglock);
1135 rcu_assign_pointer(tsk->sighand, newsighand);
1136 spin_unlock(&oldsighand->siglock);
1137 write_unlock_irq(&tasklist_lock);
1138
1139 __cleanup_sighand(oldsighand);
1140 }
1141
1142 BUG_ON(!thread_group_leader(tsk));
1143 return 0;
1144
1145killed:
1146 /* protects against exit_notify() and __exit_signal() */
1147 read_lock(&tasklist_lock);
1148 sig->group_exit_task = NULL;
1149 sig->notify_count = 0;
1150 read_unlock(&tasklist_lock);
1151 return -EAGAIN;
1152}
1153
1154char *get_task_comm(char *buf, struct task_struct *tsk)
1155{
1156 /* buf must be at least sizeof(tsk->comm) in size */
1157 task_lock(tsk);
1158 strncpy(buf, tsk->comm, sizeof(tsk->comm));
1159 task_unlock(tsk);
1160 return buf;
1161}
1162EXPORT_SYMBOL_GPL(get_task_comm);
1163
1164/*
1165 * These functions flushes out all traces of the currently running executable
1166 * so that a new one can be started
1167 */
1168
1169void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
1170{
1171 task_lock(tsk);
1172 trace_task_rename(tsk, buf);
1173 strlcpy(tsk->comm, buf, sizeof(tsk->comm));
1174 task_unlock(tsk);
1175 perf_event_comm(tsk, exec);
1176}
1177
1178int flush_old_exec(struct linux_binprm * bprm)
1179{
1180 int retval;
1181
1182 /*
1183 * Make sure we have a private signal table and that
1184 * we are unassociated from the previous thread group.
1185 */
1186 retval = de_thread(current);
1187 if (retval)
1188 goto out;
1189
1190 /*
1191 * Must be called _before_ exec_mmap() as bprm->mm is
1192 * not visibile until then. This also enables the update
1193 * to be lockless.
1194 */
1195 set_mm_exe_file(bprm->mm, bprm->file);
1196
1197 /*
1198 * Release all of the old mmap stuff
1199 */
1200 acct_arg_size(bprm, 0);
1201 retval = exec_mmap(bprm->mm);
1202 if (retval)
1203 goto out;
1204
1205 bprm->mm = NULL; /* We're using it now */
1206
1207 set_fs(USER_DS);
1208 current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
1209 PF_NOFREEZE | PF_NO_SETAFFINITY);
1210 flush_thread();
1211 current->personality &= ~bprm->per_clear;
1212
1213 return 0;
1214
1215out:
1216 return retval;
1217}
1218EXPORT_SYMBOL(flush_old_exec);
1219
1220void would_dump(struct linux_binprm *bprm, struct file *file)
1221{
1222 if (inode_permission(file_inode(file), MAY_READ) < 0)
1223 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
1224}
1225EXPORT_SYMBOL(would_dump);
1226
1227void setup_new_exec(struct linux_binprm * bprm)
1228{
1229 arch_pick_mmap_layout(current->mm);
1230
1231 /* This is the point of no return */
1232 current->sas_ss_sp = current->sas_ss_size = 0;
1233
1234 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1235 set_dumpable(current->mm, SUID_DUMP_USER);
1236 else
1237 set_dumpable(current->mm, suid_dumpable);
1238
1239 perf_event_exec();
1240 __set_task_comm(current, kbasename(bprm->filename), true);
1241
1242 /* Set the new mm task size. We have to do that late because it may
1243 * depend on TIF_32BIT which is only updated in flush_thread() on
1244 * some architectures like powerpc
1245 */
1246 current->mm->task_size = TASK_SIZE;
1247
1248 /* install the new credentials */
1249 if (!uid_eq(bprm->cred->uid, current_euid()) ||
1250 !gid_eq(bprm->cred->gid, current_egid())) {
1251 current->pdeath_signal = 0;
1252 } else {
1253 would_dump(bprm, bprm->file);
1254 if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
1255 set_dumpable(current->mm, suid_dumpable);
1256 }
1257
1258 /* An exec changes our domain. We are no longer part of the thread
1259 group */
1260 current->self_exec_id++;
1261 flush_signal_handlers(current, 0);
1262 do_close_on_exec(current->files);
1263}
1264EXPORT_SYMBOL(setup_new_exec);
1265
1266/*
1267 * Prepare credentials and lock ->cred_guard_mutex.
1268 * install_exec_creds() commits the new creds and drops the lock.
1269 * Or, if exec fails before, free_bprm() should release ->cred and
1270 * and unlock.
1271 */
1272int prepare_bprm_creds(struct linux_binprm *bprm)
1273{
1274 if (mutex_lock_interruptible(&current->signal->cred_guard_mutex))
1275 return -ERESTARTNOINTR;
1276
1277 bprm->cred = prepare_exec_creds();
1278 if (likely(bprm->cred))
1279 return 0;
1280
1281 mutex_unlock(&current->signal->cred_guard_mutex);
1282 return -ENOMEM;
1283}
1284
1285static void free_bprm(struct linux_binprm *bprm)
1286{
1287 free_arg_pages(bprm);
1288 if (bprm->cred) {
1289 mutex_unlock(&current->signal->cred_guard_mutex);
1290 abort_creds(bprm->cred);
1291 }
1292 if (bprm->file) {
1293 allow_write_access(bprm->file);
1294 fput(bprm->file);
1295 }
1296 /* If a binfmt changed the interp, free it. */
1297 if (bprm->interp != bprm->filename)
1298 kfree(bprm->interp);
1299 kfree(bprm);
1300}
1301
1302int bprm_change_interp(char *interp, struct linux_binprm *bprm)
1303{
1304 /* If a binfmt changed the interp, free it first. */
1305 if (bprm->interp != bprm->filename)
1306 kfree(bprm->interp);
1307 bprm->interp = kstrdup(interp, GFP_KERNEL);
1308 if (!bprm->interp)
1309 return -ENOMEM;
1310 return 0;
1311}
1312EXPORT_SYMBOL(bprm_change_interp);
1313
1314/*
1315 * install the new credentials for this executable
1316 */
1317void install_exec_creds(struct linux_binprm *bprm)
1318{
1319 security_bprm_committing_creds(bprm);
1320
1321 commit_creds(bprm->cred);
1322 bprm->cred = NULL;
1323
1324 /*
1325 * Disable monitoring for regular users
1326 * when executing setuid binaries. Must
1327 * wait until new credentials are committed
1328 * by commit_creds() above
1329 */
1330 if (get_dumpable(current->mm) != SUID_DUMP_USER)
1331 perf_event_exit_task(current);
1332 /*
1333 * cred_guard_mutex must be held at least to this point to prevent
1334 * ptrace_attach() from altering our determination of the task's
1335 * credentials; any time after this it may be unlocked.
1336 */
1337 security_bprm_committed_creds(bprm);
1338 mutex_unlock(&current->signal->cred_guard_mutex);
1339}
1340EXPORT_SYMBOL(install_exec_creds);
1341
1342/*
1343 * determine how safe it is to execute the proposed program
1344 * - the caller must hold ->cred_guard_mutex to protect against
1345 * PTRACE_ATTACH or seccomp thread-sync
1346 */
1347static void check_unsafe_exec(struct linux_binprm *bprm)
1348{
1349 struct task_struct *p = current, *t;
1350 unsigned n_fs;
1351
1352 if (p->ptrace) {
1353 if (p->ptrace & PT_PTRACE_CAP)
1354 bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
1355 else
1356 bprm->unsafe |= LSM_UNSAFE_PTRACE;
1357 }
1358
1359 /*
1360 * This isn't strictly necessary, but it makes it harder for LSMs to
1361 * mess up.
1362 */
1363 if (task_no_new_privs(current))
1364 bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
1365
1366 t = p;
1367 n_fs = 1;
1368 spin_lock(&p->fs->lock);
1369 rcu_read_lock();
1370 while_each_thread(p, t) {
1371 if (t->fs == p->fs)
1372 n_fs++;
1373 }
1374 rcu_read_unlock();
1375
1376 if (p->fs->users > n_fs)
1377 bprm->unsafe |= LSM_UNSAFE_SHARE;
1378 else
1379 p->fs->in_exec = 1;
1380 spin_unlock(&p->fs->lock);
1381}
1382
1383static void bprm_fill_uid(struct linux_binprm *bprm)
1384{
1385 struct inode *inode;
1386 unsigned int mode;
1387 kuid_t uid;
1388 kgid_t gid;
1389
1390 /* clear any previous set[ug]id data from a previous binary */
1391 bprm->cred->euid = current_euid();
1392 bprm->cred->egid = current_egid();
1393
1394 if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
1395 return;
1396
1397 if (task_no_new_privs(current))
1398 return;
1399
1400 inode = file_inode(bprm->file);
1401 mode = READ_ONCE(inode->i_mode);
1402 if (!(mode & (S_ISUID|S_ISGID)))
1403 return;
1404
1405 /* Be careful if suid/sgid is set */
1406 inode_lock(inode);
1407
1408 /* reload atomically mode/uid/gid now that lock held */
1409 mode = inode->i_mode;
1410 uid = inode->i_uid;
1411 gid = inode->i_gid;
1412 inode_unlock(inode);
1413
1414 /* We ignore suid/sgid if there are no mappings for them in the ns */
1415 if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
1416 !kgid_has_mapping(bprm->cred->user_ns, gid))
1417 return;
1418
1419 if (mode & S_ISUID) {
1420 bprm->per_clear |= PER_CLEAR_ON_SETID;
1421 bprm->cred->euid = uid;
1422 }
1423
1424 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
1425 bprm->per_clear |= PER_CLEAR_ON_SETID;
1426 bprm->cred->egid = gid;
1427 }
1428}
1429
1430/*
1431 * Fill the binprm structure from the inode.
1432 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1433 *
1434 * This may be called multiple times for binary chains (scripts for example).
1435 */
1436int prepare_binprm(struct linux_binprm *bprm)
1437{
1438 int retval;
1439
1440 bprm_fill_uid(bprm);
1441
1442 /* fill in binprm security blob */
1443 retval = security_bprm_set_creds(bprm);
1444 if (retval)
1445 return retval;
1446 bprm->cred_prepared = 1;
1447
1448 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
1449 return kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
1450}
1451
1452EXPORT_SYMBOL(prepare_binprm);
1453
1454/*
1455 * Arguments are '\0' separated strings found at the location bprm->p
1456 * points to; chop off the first by relocating brpm->p to right after
1457 * the first '\0' encountered.
1458 */
1459int remove_arg_zero(struct linux_binprm *bprm)
1460{
1461 int ret = 0;
1462 unsigned long offset;
1463 char *kaddr;
1464 struct page *page;
1465
1466 if (!bprm->argc)
1467 return 0;
1468
1469 do {
1470 offset = bprm->p & ~PAGE_MASK;
1471 page = get_arg_page(bprm, bprm->p, 0);
1472 if (!page) {
1473 ret = -EFAULT;
1474 goto out;
1475 }
1476 kaddr = kmap_atomic(page);
1477
1478 for (; offset < PAGE_SIZE && kaddr[offset];
1479 offset++, bprm->p++)
1480 ;
1481
1482 kunmap_atomic(kaddr);
1483 put_arg_page(page);
1484
1485 if (offset == PAGE_SIZE)
1486 free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
1487 } while (offset == PAGE_SIZE);
1488
1489 bprm->p++;
1490 bprm->argc--;
1491 ret = 0;
1492
1493out:
1494 return ret;
1495}
1496EXPORT_SYMBOL(remove_arg_zero);
1497
1498#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1499/*
1500 * cycle the list of binary formats handler, until one recognizes the image
1501 */
1502int search_binary_handler(struct linux_binprm *bprm)
1503{
1504 bool need_retry = IS_ENABLED(CONFIG_MODULES);
1505 struct linux_binfmt *fmt;
1506 int retval;
1507
1508 /* This allows 4 levels of binfmt rewrites before failing hard. */
1509 if (bprm->recursion_depth > 5)
1510 return -ELOOP;
1511
1512 retval = security_bprm_check(bprm);
1513 if (retval)
1514 return retval;
1515
1516 retval = -ENOENT;
1517 retry:
1518 read_lock(&binfmt_lock);
1519 list_for_each_entry(fmt, &formats, lh) {
1520 if (!try_module_get(fmt->module))
1521 continue;
1522 read_unlock(&binfmt_lock);
1523 bprm->recursion_depth++;
1524 retval = fmt->load_binary(bprm);
1525 read_lock(&binfmt_lock);
1526 put_binfmt(fmt);
1527 bprm->recursion_depth--;
1528 if (retval < 0 && !bprm->mm) {
1529 /* we got to flush_old_exec() and failed after it */
1530 read_unlock(&binfmt_lock);
1531 force_sigsegv(SIGSEGV, current);
1532 return retval;
1533 }
1534 if (retval != -ENOEXEC || !bprm->file) {
1535 read_unlock(&binfmt_lock);
1536 return retval;
1537 }
1538 }
1539 read_unlock(&binfmt_lock);
1540
1541 if (need_retry) {
1542 if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
1543 printable(bprm->buf[2]) && printable(bprm->buf[3]))
1544 return retval;
1545 if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
1546 return retval;
1547 need_retry = false;
1548 goto retry;
1549 }
1550
1551 return retval;
1552}
1553EXPORT_SYMBOL(search_binary_handler);
1554
1555static int exec_binprm(struct linux_binprm *bprm)
1556{
1557 pid_t old_pid, old_vpid;
1558 int ret;
1559
1560 /* Need to fetch pid before load_binary changes it */
1561 old_pid = current->pid;
1562 rcu_read_lock();
1563 old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
1564 rcu_read_unlock();
1565
1566 ret = search_binary_handler(bprm);
1567 if (ret >= 0) {
1568 audit_bprm(bprm);
1569 trace_sched_process_exec(current, old_pid, bprm);
1570 ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
1571 proc_exec_connector(current);
1572 }
1573
1574 return ret;
1575}
1576
1577/*
1578 * sys_execve() executes a new program.
1579 */
1580static int do_execveat_common(int fd, struct filename *filename,
1581 struct user_arg_ptr argv,
1582 struct user_arg_ptr envp,
1583 int flags)
1584{
1585 char *pathbuf = NULL;
1586 struct linux_binprm *bprm;
1587 struct file *file;
1588 struct files_struct *displaced;
1589 int retval;
1590
1591 if (IS_ERR(filename))
1592 return PTR_ERR(filename);
1593
1594 /*
1595 * We move the actual failure in case of RLIMIT_NPROC excess from
1596 * set*uid() to execve() because too many poorly written programs
1597 * don't check setuid() return code. Here we additionally recheck
1598 * whether NPROC limit is still exceeded.
1599 */
1600 if ((current->flags & PF_NPROC_EXCEEDED) &&
1601 atomic_read(&current_user()->processes) > rlimit(RLIMIT_NPROC)) {
1602 retval = -EAGAIN;
1603 goto out_ret;
1604 }
1605
1606 /* We're below the limit (still or again), so we don't want to make
1607 * further execve() calls fail. */
1608 current->flags &= ~PF_NPROC_EXCEEDED;
1609
1610 retval = unshare_files(&displaced);
1611 if (retval)
1612 goto out_ret;
1613
1614 retval = -ENOMEM;
1615 bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
1616 if (!bprm)
1617 goto out_files;
1618
1619 retval = prepare_bprm_creds(bprm);
1620 if (retval)
1621 goto out_free;
1622
1623 check_unsafe_exec(bprm);
1624 current->in_execve = 1;
1625
1626 file = do_open_execat(fd, filename, flags);
1627 retval = PTR_ERR(file);
1628 if (IS_ERR(file))
1629 goto out_unmark;
1630
1631 sched_exec();
1632
1633 bprm->file = file;
1634 if (fd == AT_FDCWD || filename->name[0] == '/') {
1635 bprm->filename = filename->name;
1636 } else {
1637 if (filename->name[0] == '\0')
1638 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d", fd);
1639 else
1640 pathbuf = kasprintf(GFP_TEMPORARY, "/dev/fd/%d/%s",
1641 fd, filename->name);
1642 if (!pathbuf) {
1643 retval = -ENOMEM;
1644 goto out_unmark;
1645 }
1646 /*
1647 * Record that a name derived from an O_CLOEXEC fd will be
1648 * inaccessible after exec. Relies on having exclusive access to
1649 * current->files (due to unshare_files above).
1650 */
1651 if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
1652 bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
1653 bprm->filename = pathbuf;
1654 }
1655 bprm->interp = bprm->filename;
1656
1657 retval = bprm_mm_init(bprm);
1658 if (retval)
1659 goto out_unmark;
1660
1661 bprm->argc = count(argv, MAX_ARG_STRINGS);
1662 if ((retval = bprm->argc) < 0)
1663 goto out;
1664
1665 bprm->envc = count(envp, MAX_ARG_STRINGS);
1666 if ((retval = bprm->envc) < 0)
1667 goto out;
1668
1669 retval = prepare_binprm(bprm);
1670 if (retval < 0)
1671 goto out;
1672
1673 retval = copy_strings_kernel(1, &bprm->filename, bprm);
1674 if (retval < 0)
1675 goto out;
1676
1677 bprm->exec = bprm->p;
1678 retval = copy_strings(bprm->envc, envp, bprm);
1679 if (retval < 0)
1680 goto out;
1681
1682 retval = copy_strings(bprm->argc, argv, bprm);
1683 if (retval < 0)
1684 goto out;
1685
1686 retval = exec_binprm(bprm);
1687 if (retval < 0)
1688 goto out;
1689
1690 /* execve succeeded */
1691 current->fs->in_exec = 0;
1692 current->in_execve = 0;
1693 acct_update_integrals(current);
1694 task_numa_free(current);
1695 free_bprm(bprm);
1696 kfree(pathbuf);
1697 putname(filename);
1698 if (displaced)
1699 put_files_struct(displaced);
1700 return retval;
1701
1702out:
1703 if (bprm->mm) {
1704 acct_arg_size(bprm, 0);
1705 mmput(bprm->mm);
1706 }
1707
1708out_unmark:
1709 current->fs->in_exec = 0;
1710 current->in_execve = 0;
1711
1712out_free:
1713 free_bprm(bprm);
1714 kfree(pathbuf);
1715
1716out_files:
1717 if (displaced)
1718 reset_files_struct(displaced);
1719out_ret:
1720 putname(filename);
1721 return retval;
1722}
1723
1724int do_execve(struct filename *filename,
1725 const char __user *const __user *__argv,
1726 const char __user *const __user *__envp)
1727{
1728 struct user_arg_ptr argv = { .ptr.native = __argv };
1729 struct user_arg_ptr envp = { .ptr.native = __envp };
1730 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1731}
1732
1733int do_execveat(int fd, struct filename *filename,
1734 const char __user *const __user *__argv,
1735 const char __user *const __user *__envp,
1736 int flags)
1737{
1738 struct user_arg_ptr argv = { .ptr.native = __argv };
1739 struct user_arg_ptr envp = { .ptr.native = __envp };
1740
1741 return do_execveat_common(fd, filename, argv, envp, flags);
1742}
1743
1744#ifdef CONFIG_COMPAT
1745static int compat_do_execve(struct filename *filename,
1746 const compat_uptr_t __user *__argv,
1747 const compat_uptr_t __user *__envp)
1748{
1749 struct user_arg_ptr argv = {
1750 .is_compat = true,
1751 .ptr.compat = __argv,
1752 };
1753 struct user_arg_ptr envp = {
1754 .is_compat = true,
1755 .ptr.compat = __envp,
1756 };
1757 return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
1758}
1759
1760static int compat_do_execveat(int fd, struct filename *filename,
1761 const compat_uptr_t __user *__argv,
1762 const compat_uptr_t __user *__envp,
1763 int flags)
1764{
1765 struct user_arg_ptr argv = {
1766 .is_compat = true,
1767 .ptr.compat = __argv,
1768 };
1769 struct user_arg_ptr envp = {
1770 .is_compat = true,
1771 .ptr.compat = __envp,
1772 };
1773 return do_execveat_common(fd, filename, argv, envp, flags);
1774}
1775#endif
1776
1777void set_binfmt(struct linux_binfmt *new)
1778{
1779 struct mm_struct *mm = current->mm;
1780
1781 if (mm->binfmt)
1782 module_put(mm->binfmt->module);
1783
1784 mm->binfmt = new;
1785 if (new)
1786 __module_get(new->module);
1787}
1788EXPORT_SYMBOL(set_binfmt);
1789
1790/*
1791 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
1792 */
1793void set_dumpable(struct mm_struct *mm, int value)
1794{
1795 unsigned long old, new;
1796
1797 if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
1798 return;
1799
1800 do {
1801 old = ACCESS_ONCE(mm->flags);
1802 new = (old & ~MMF_DUMPABLE_MASK) | value;
1803 } while (cmpxchg(&mm->flags, old, new) != old);
1804}
1805
1806SYSCALL_DEFINE3(execve,
1807 const char __user *, filename,
1808 const char __user *const __user *, argv,
1809 const char __user *const __user *, envp)
1810{
1811 return do_execve(getname(filename), argv, envp);
1812}
1813
1814SYSCALL_DEFINE5(execveat,
1815 int, fd, const char __user *, filename,
1816 const char __user *const __user *, argv,
1817 const char __user *const __user *, envp,
1818 int, flags)
1819{
1820 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1821
1822 return do_execveat(fd,
1823 getname_flags(filename, lookup_flags, NULL),
1824 argv, envp, flags);
1825}
1826
1827#ifdef CONFIG_COMPAT
1828COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
1829 const compat_uptr_t __user *, argv,
1830 const compat_uptr_t __user *, envp)
1831{
1832 return compat_do_execve(getname(filename), argv, envp);
1833}
1834
1835COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
1836 const char __user *, filename,
1837 const compat_uptr_t __user *, argv,
1838 const compat_uptr_t __user *, envp,
1839 int, flags)
1840{
1841 int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
1842
1843 return compat_do_execveat(fd,
1844 getname_flags(filename, lookup_flags, NULL),
1845 argv, envp, flags);
1846}
1847#endif