1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * #!-checking implemented by tytso.
12 * Demand-loading implemented 01.12.91 - no need to read anything but
13 * the header into memory. The inode of the executable is put into
14 * "current->executable", and page faults do the actual loading. Clean.
16 * Once more I can proudly say that linux stood up to being changed: it
17 * was less than 2 hours work to get demand-loading completely implemented.
19 * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
20 * current->executable is only used by the procfs. This allows a dispatch
21 * table to check for several different types of binary formats. We keep
22 * trying until we recognize the file or we run out of supported binary
26 #include <linux/kernel_read_file.h>
27 #include <linux/slab.h>
28 #include <linux/file.h>
29 #include <linux/fdtable.h>
31 #include <linux/stat.h>
32 #include <linux/fcntl.h>
33 #include <linux/swap.h>
34 #include <linux/string.h>
35 #include <linux/init.h>
36 #include <linux/sched/mm.h>
37 #include <linux/sched/coredump.h>
38 #include <linux/sched/signal.h>
39 #include <linux/sched/numa_balancing.h>
40 #include <linux/sched/task.h>
41 #include <linux/pagemap.h>
42 #include <linux/perf_event.h>
43 #include <linux/highmem.h>
44 #include <linux/spinlock.h>
45 #include <linux/key.h>
46 #include <linux/personality.h>
47 #include <linux/binfmts.h>
48 #include <linux/utsname.h>
49 #include <linux/pid_namespace.h>
50 #include <linux/module.h>
51 #include <linux/namei.h>
52 #include <linux/mount.h>
53 #include <linux/security.h>
54 #include <linux/syscalls.h>
55 #include <linux/tsacct_kern.h>
56 #include <linux/cn_proc.h>
57 #include <linux/audit.h>
58 #include <linux/kmod.h>
59 #include <linux/fsnotify.h>
60 #include <linux/fs_struct.h>
61 #include <linux/oom.h>
62 #include <linux/compat.h>
63 #include <linux/vmalloc.h>
64 #include <linux/io_uring.h>
65 #include <linux/syscall_user_dispatch.h>
66 #include <linux/coredump.h>
67 #include <linux/time_namespace.h>
68 #include <linux/user_events.h>
69 #include <linux/rseq.h>
71 #include <linux/uaccess.h>
72 #include <asm/mmu_context.h>
75 #include <trace/events/task.h>
78 #include <trace/events/sched.h>
80 static int bprm_creds_from_file(struct linux_binprm
*bprm
);
82 int suid_dumpable
= 0;
84 static LIST_HEAD(formats
);
85 static DEFINE_RWLOCK(binfmt_lock
);
87 void __register_binfmt(struct linux_binfmt
* fmt
, int insert
)
89 write_lock(&binfmt_lock
);
90 insert
? list_add(&fmt
->lh
, &formats
) :
91 list_add_tail(&fmt
->lh
, &formats
);
92 write_unlock(&binfmt_lock
);
95 EXPORT_SYMBOL(__register_binfmt
);
97 void unregister_binfmt(struct linux_binfmt
* fmt
)
99 write_lock(&binfmt_lock
);
101 write_unlock(&binfmt_lock
);
104 EXPORT_SYMBOL(unregister_binfmt
);
106 static inline void put_binfmt(struct linux_binfmt
* fmt
)
108 module_put(fmt
->module
);
111 bool path_noexec(const struct path
*path
)
113 return (path
->mnt
->mnt_flags
& MNT_NOEXEC
) ||
114 (path
->mnt
->mnt_sb
->s_iflags
& SB_I_NOEXEC
);
119 * Note that a shared library must be both readable and executable due to
122 * Also note that we take the address to load from the file itself.
124 SYSCALL_DEFINE1(uselib
, const char __user
*, library
)
126 struct linux_binfmt
*fmt
;
128 struct filename
*tmp
= getname(library
);
129 int error
= PTR_ERR(tmp
);
130 static const struct open_flags uselib_flags
= {
131 .open_flag
= O_LARGEFILE
| O_RDONLY
| __FMODE_EXEC
,
132 .acc_mode
= MAY_READ
| MAY_EXEC
,
133 .intent
= LOOKUP_OPEN
,
134 .lookup_flags
= LOOKUP_FOLLOW
,
140 file
= do_filp_open(AT_FDCWD
, tmp
, &uselib_flags
);
142 error
= PTR_ERR(file
);
147 * may_open() has already checked for this, so it should be
148 * impossible to trip now. But we need to be extra cautious
149 * and check again at the very end too.
152 if (WARN_ON_ONCE(!S_ISREG(file_inode(file
)->i_mode
) ||
153 path_noexec(&file
->f_path
)))
158 read_lock(&binfmt_lock
);
159 list_for_each_entry(fmt
, &formats
, lh
) {
160 if (!fmt
->load_shlib
)
162 if (!try_module_get(fmt
->module
))
164 read_unlock(&binfmt_lock
);
165 error
= fmt
->load_shlib(file
);
166 read_lock(&binfmt_lock
);
168 if (error
!= -ENOEXEC
)
171 read_unlock(&binfmt_lock
);
177 #endif /* #ifdef CONFIG_USELIB */
181 * The nascent bprm->mm is not visible until exec_mmap() but it can
182 * use a lot of memory, account these pages in current->mm temporary
183 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
184 * change the counter back via acct_arg_size(0).
186 static void acct_arg_size(struct linux_binprm
*bprm
, unsigned long pages
)
188 struct mm_struct
*mm
= current
->mm
;
189 long diff
= (long)(pages
- bprm
->vma_pages
);
194 bprm
->vma_pages
= pages
;
195 add_mm_counter(mm
, MM_ANONPAGES
, diff
);
198 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
202 struct vm_area_struct
*vma
= bprm
->vma
;
203 struct mm_struct
*mm
= bprm
->mm
;
207 * Avoid relying on expanding the stack down in GUP (which
208 * does not work for STACK_GROWSUP anyway), and just do it
209 * by hand ahead of time.
211 if (write
&& pos
< vma
->vm_start
) {
213 ret
= expand_downwards(vma
, pos
);
214 if (unlikely(ret
< 0)) {
215 mmap_write_unlock(mm
);
218 mmap_write_downgrade(mm
);
223 * We are doing an exec(). 'current' is the process
224 * doing the exec and 'mm' is the new process's mm.
226 ret
= get_user_pages_remote(mm
, pos
, 1,
227 write
? FOLL_WRITE
: 0,
229 mmap_read_unlock(mm
);
234 acct_arg_size(bprm
, vma_pages(vma
));
239 static void put_arg_page(struct page
*page
)
244 static void free_arg_pages(struct linux_binprm
*bprm
)
248 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
251 flush_cache_page(bprm
->vma
, pos
, page_to_pfn(page
));
254 static int __bprm_mm_init(struct linux_binprm
*bprm
)
257 struct vm_area_struct
*vma
= NULL
;
258 struct mm_struct
*mm
= bprm
->mm
;
260 bprm
->vma
= vma
= vm_area_alloc(mm
);
263 vma_set_anonymous(vma
);
265 if (mmap_write_lock_killable(mm
)) {
271 * Place the stack at the largest stack address the architecture
272 * supports. Later, we'll move this to an appropriate place. We don't
273 * use STACK_TOP because that can depend on attributes which aren't
276 BUILD_BUG_ON(VM_STACK_FLAGS
& VM_STACK_INCOMPLETE_SETUP
);
277 vma
->vm_end
= STACK_TOP_MAX
;
278 vma
->vm_start
= vma
->vm_end
- PAGE_SIZE
;
279 vm_flags_init(vma
, VM_SOFTDIRTY
| VM_STACK_FLAGS
| VM_STACK_INCOMPLETE_SETUP
);
280 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
282 err
= insert_vm_struct(mm
, vma
);
286 mm
->stack_vm
= mm
->total_vm
= 1;
287 mmap_write_unlock(mm
);
288 bprm
->p
= vma
->vm_end
- sizeof(void *);
291 mmap_write_unlock(mm
);
298 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
300 return len
<= MAX_ARG_STRLEN
;
305 static inline void acct_arg_size(struct linux_binprm
*bprm
, unsigned long pages
)
309 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
314 page
= bprm
->page
[pos
/ PAGE_SIZE
];
315 if (!page
&& write
) {
316 page
= alloc_page(GFP_HIGHUSER
|__GFP_ZERO
);
319 bprm
->page
[pos
/ PAGE_SIZE
] = page
;
325 static void put_arg_page(struct page
*page
)
329 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
332 __free_page(bprm
->page
[i
]);
333 bprm
->page
[i
] = NULL
;
337 static void free_arg_pages(struct linux_binprm
*bprm
)
341 for (i
= 0; i
< MAX_ARG_PAGES
; i
++)
342 free_arg_page(bprm
, i
);
345 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
350 static int __bprm_mm_init(struct linux_binprm
*bprm
)
352 bprm
->p
= PAGE_SIZE
* MAX_ARG_PAGES
- sizeof(void *);
356 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
358 return len
<= bprm
->p
;
361 #endif /* CONFIG_MMU */
364 * Create a new mm_struct and populate it with a temporary stack
365 * vm_area_struct. We don't have enough context at this point to set the stack
366 * flags, permissions, and offset, so we use temporary values. We'll update
367 * them later in setup_arg_pages().
369 static int bprm_mm_init(struct linux_binprm
*bprm
)
372 struct mm_struct
*mm
= NULL
;
374 bprm
->mm
= mm
= mm_alloc();
379 /* Save current stack limit for all calculations made during exec. */
380 task_lock(current
->group_leader
);
381 bprm
->rlim_stack
= current
->signal
->rlim
[RLIMIT_STACK
];
382 task_unlock(current
->group_leader
);
384 err
= __bprm_mm_init(bprm
);
399 struct user_arg_ptr
{
404 const char __user
*const __user
*native
;
406 const compat_uptr_t __user
*compat
;
411 static const char __user
*get_user_arg_ptr(struct user_arg_ptr argv
, int nr
)
413 const char __user
*native
;
416 if (unlikely(argv
.is_compat
)) {
417 compat_uptr_t compat
;
419 if (get_user(compat
, argv
.ptr
.compat
+ nr
))
420 return ERR_PTR(-EFAULT
);
422 return compat_ptr(compat
);
426 if (get_user(native
, argv
.ptr
.native
+ nr
))
427 return ERR_PTR(-EFAULT
);
433 * count() counts the number of strings in array ARGV.
435 static int count(struct user_arg_ptr argv
, int max
)
439 if (argv
.ptr
.native
!= NULL
) {
441 const char __user
*p
= get_user_arg_ptr(argv
, i
);
453 if (fatal_signal_pending(current
))
454 return -ERESTARTNOHAND
;
461 static int count_strings_kernel(const char *const *argv
)
468 for (i
= 0; argv
[i
]; ++i
) {
469 if (i
>= MAX_ARG_STRINGS
)
471 if (fatal_signal_pending(current
))
472 return -ERESTARTNOHAND
;
478 static int bprm_stack_limits(struct linux_binprm
*bprm
)
480 unsigned long limit
, ptr_size
;
483 * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
484 * (whichever is smaller) for the argv+env strings.
486 * - the remaining binfmt code will not run out of stack space,
487 * - the program will have a reasonable amount of stack left
490 limit
= _STK_LIM
/ 4 * 3;
491 limit
= min(limit
, bprm
->rlim_stack
.rlim_cur
/ 4);
493 * We've historically supported up to 32 pages (ARG_MAX)
494 * of argument strings even with small stacks
496 limit
= max_t(unsigned long, limit
, ARG_MAX
);
498 * We must account for the size of all the argv and envp pointers to
499 * the argv and envp strings, since they will also take up space in
500 * the stack. They aren't stored until much later when we can't
501 * signal to the parent that the child has run out of stack space.
502 * Instead, calculate it here so it's possible to fail gracefully.
504 * In the case of argc = 0, make sure there is space for adding a
505 * empty string (which will bump argc to 1), to ensure confused
506 * userspace programs don't start processing from argv[1], thinking
507 * argc can never be 0, to keep them from walking envp by accident.
508 * See do_execveat_common().
510 ptr_size
= (max(bprm
->argc
, 1) + bprm
->envc
) * sizeof(void *);
511 if (limit
<= ptr_size
)
515 bprm
->argmin
= bprm
->p
- limit
;
520 * 'copy_strings()' copies argument/environment strings from the old
521 * processes's memory to the new process's stack. The call to get_user_pages()
522 * ensures the destination page is created and not swapped out.
524 static int copy_strings(int argc
, struct user_arg_ptr argv
,
525 struct linux_binprm
*bprm
)
527 struct page
*kmapped_page
= NULL
;
529 unsigned long kpos
= 0;
533 const char __user
*str
;
538 str
= get_user_arg_ptr(argv
, argc
);
542 len
= strnlen_user(str
, MAX_ARG_STRLEN
);
547 if (!valid_arg_len(bprm
, len
))
550 /* We're going to work our way backwards. */
555 if (bprm
->p
< bprm
->argmin
)
560 int offset
, bytes_to_copy
;
562 if (fatal_signal_pending(current
)) {
563 ret
= -ERESTARTNOHAND
;
568 offset
= pos
% PAGE_SIZE
;
572 bytes_to_copy
= offset
;
573 if (bytes_to_copy
> len
)
576 offset
-= bytes_to_copy
;
577 pos
-= bytes_to_copy
;
578 str
-= bytes_to_copy
;
579 len
-= bytes_to_copy
;
581 if (!kmapped_page
|| kpos
!= (pos
& PAGE_MASK
)) {
584 page
= get_arg_page(bprm
, pos
, 1);
591 flush_dcache_page(kmapped_page
);
593 put_arg_page(kmapped_page
);
596 kaddr
= kmap_local_page(kmapped_page
);
597 kpos
= pos
& PAGE_MASK
;
598 flush_arg_page(bprm
, kpos
, kmapped_page
);
600 if (copy_from_user(kaddr
+offset
, str
, bytes_to_copy
)) {
609 flush_dcache_page(kmapped_page
);
611 put_arg_page(kmapped_page
);
617 * Copy and argument/environment string from the kernel to the processes stack.
619 int copy_string_kernel(const char *arg
, struct linux_binprm
*bprm
)
621 int len
= strnlen(arg
, MAX_ARG_STRLEN
) + 1 /* terminating NUL */;
622 unsigned long pos
= bprm
->p
;
626 if (!valid_arg_len(bprm
, len
))
629 /* We're going to work our way backwards. */
632 if (IS_ENABLED(CONFIG_MMU
) && bprm
->p
< bprm
->argmin
)
636 unsigned int bytes_to_copy
= min_t(unsigned int, len
,
637 min_not_zero(offset_in_page(pos
), PAGE_SIZE
));
640 pos
-= bytes_to_copy
;
641 arg
-= bytes_to_copy
;
642 len
-= bytes_to_copy
;
644 page
= get_arg_page(bprm
, pos
, 1);
647 flush_arg_page(bprm
, pos
& PAGE_MASK
, page
);
648 memcpy_to_page(page
, offset_in_page(pos
), arg
, bytes_to_copy
);
654 EXPORT_SYMBOL(copy_string_kernel
);
656 static int copy_strings_kernel(int argc
, const char *const *argv
,
657 struct linux_binprm
*bprm
)
660 int ret
= copy_string_kernel(argv
[argc
], bprm
);
663 if (fatal_signal_pending(current
))
664 return -ERESTARTNOHAND
;
673 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
674 * the binfmt code determines where the new stack should reside, we shift it to
675 * its final location. The process proceeds as follows:
677 * 1) Use shift to calculate the new vma endpoints.
678 * 2) Extend vma to cover both the old and new ranges. This ensures the
679 * arguments passed to subsequent functions are consistent.
680 * 3) Move vma's page tables to the new range.
681 * 4) Free up any cleared pgd range.
682 * 5) Shrink the vma to cover only the new range.
684 static int shift_arg_pages(struct vm_area_struct
*vma
, unsigned long shift
)
686 struct mm_struct
*mm
= vma
->vm_mm
;
687 unsigned long old_start
= vma
->vm_start
;
688 unsigned long old_end
= vma
->vm_end
;
689 unsigned long length
= old_end
- old_start
;
690 unsigned long new_start
= old_start
- shift
;
691 unsigned long new_end
= old_end
- shift
;
692 VMA_ITERATOR(vmi
, mm
, new_start
);
693 struct vm_area_struct
*next
;
694 struct mmu_gather tlb
;
696 BUG_ON(new_start
> new_end
);
699 * ensure there are no vmas between where we want to go
702 if (vma
!= vma_next(&vmi
))
705 vma_iter_prev_range(&vmi
);
707 * cover the whole range: [new_start, old_end)
709 if (vma_expand(&vmi
, vma
, new_start
, old_end
, vma
->vm_pgoff
, NULL
))
713 * move the page tables downwards, on failure we rely on
714 * process cleanup to remove whatever mess we made.
716 if (length
!= move_page_tables(vma
, old_start
,
717 vma
, new_start
, length
, false, true))
721 tlb_gather_mmu(&tlb
, mm
);
722 next
= vma_next(&vmi
);
723 if (new_end
> old_start
) {
725 * when the old and new regions overlap clear from new_end.
727 free_pgd_range(&tlb
, new_end
, old_end
, new_end
,
728 next
? next
->vm_start
: USER_PGTABLES_CEILING
);
731 * otherwise, clean from old_start; this is done to not touch
732 * the address space in [new_end, old_start) some architectures
733 * have constraints on va-space that make this illegal (IA64) -
734 * for the others its just a little faster.
736 free_pgd_range(&tlb
, old_start
, old_end
, new_end
,
737 next
? next
->vm_start
: USER_PGTABLES_CEILING
);
739 tlb_finish_mmu(&tlb
);
742 /* Shrink the vma to just the new range */
743 return vma_shrink(&vmi
, vma
, new_start
, new_end
, vma
->vm_pgoff
);
747 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
748 * the stack is optionally relocated, and some extra space is added.
750 int setup_arg_pages(struct linux_binprm
*bprm
,
751 unsigned long stack_top
,
752 int executable_stack
)
755 unsigned long stack_shift
;
756 struct mm_struct
*mm
= current
->mm
;
757 struct vm_area_struct
*vma
= bprm
->vma
;
758 struct vm_area_struct
*prev
= NULL
;
759 unsigned long vm_flags
;
760 unsigned long stack_base
;
761 unsigned long stack_size
;
762 unsigned long stack_expand
;
763 unsigned long rlim_stack
;
764 struct mmu_gather tlb
;
765 struct vma_iterator vmi
;
767 #ifdef CONFIG_STACK_GROWSUP
768 /* Limit stack size */
769 stack_base
= bprm
->rlim_stack
.rlim_max
;
771 stack_base
= calc_max_stack_size(stack_base
);
773 /* Add space for stack randomization. */
774 stack_base
+= (STACK_RND_MASK
<< PAGE_SHIFT
);
776 /* Make sure we didn't let the argument array grow too large. */
777 if (vma
->vm_end
- vma
->vm_start
> stack_base
)
780 stack_base
= PAGE_ALIGN(stack_top
- stack_base
);
782 stack_shift
= vma
->vm_start
- stack_base
;
783 mm
->arg_start
= bprm
->p
- stack_shift
;
784 bprm
->p
= vma
->vm_end
- stack_shift
;
786 stack_top
= arch_align_stack(stack_top
);
787 stack_top
= PAGE_ALIGN(stack_top
);
789 if (unlikely(stack_top
< mmap_min_addr
) ||
790 unlikely(vma
->vm_end
- vma
->vm_start
>= stack_top
- mmap_min_addr
))
793 stack_shift
= vma
->vm_end
- stack_top
;
795 bprm
->p
-= stack_shift
;
796 mm
->arg_start
= bprm
->p
;
800 bprm
->loader
-= stack_shift
;
801 bprm
->exec
-= stack_shift
;
803 if (mmap_write_lock_killable(mm
))
806 vm_flags
= VM_STACK_FLAGS
;
809 * Adjust stack execute permissions; explicitly enable for
810 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
811 * (arch default) otherwise.
813 if (unlikely(executable_stack
== EXSTACK_ENABLE_X
))
815 else if (executable_stack
== EXSTACK_DISABLE_X
)
816 vm_flags
&= ~VM_EXEC
;
817 vm_flags
|= mm
->def_flags
;
818 vm_flags
|= VM_STACK_INCOMPLETE_SETUP
;
820 vma_iter_init(&vmi
, mm
, vma
->vm_start
);
822 tlb_gather_mmu(&tlb
, mm
);
823 ret
= mprotect_fixup(&vmi
, &tlb
, vma
, &prev
, vma
->vm_start
, vma
->vm_end
,
825 tlb_finish_mmu(&tlb
);
831 if (unlikely(vm_flags
& VM_EXEC
)) {
832 pr_warn_once("process '%pD4' started with executable stack\n",
836 /* Move stack pages down in memory. */
838 ret
= shift_arg_pages(vma
, stack_shift
);
843 /* mprotect_fixup is overkill to remove the temporary stack flags */
844 vm_flags_clear(vma
, VM_STACK_INCOMPLETE_SETUP
);
846 stack_expand
= 131072UL; /* randomly 32*4k (or 2*64k) pages */
847 stack_size
= vma
->vm_end
- vma
->vm_start
;
849 * Align this down to a page boundary as expand_stack
852 rlim_stack
= bprm
->rlim_stack
.rlim_cur
& PAGE_MASK
;
854 stack_expand
= min(rlim_stack
, stack_size
+ stack_expand
);
856 #ifdef CONFIG_STACK_GROWSUP
857 stack_base
= vma
->vm_start
+ stack_expand
;
859 stack_base
= vma
->vm_end
- stack_expand
;
861 current
->mm
->start_stack
= bprm
->p
;
862 ret
= expand_stack_locked(vma
, stack_base
);
867 mmap_write_unlock(mm
);
870 EXPORT_SYMBOL(setup_arg_pages
);
875 * Transfer the program arguments and environment from the holding pages
876 * onto the stack. The provided stack pointer is adjusted accordingly.
878 int transfer_args_to_stack(struct linux_binprm
*bprm
,
879 unsigned long *sp_location
)
881 unsigned long index
, stop
, sp
;
884 stop
= bprm
->p
>> PAGE_SHIFT
;
887 for (index
= MAX_ARG_PAGES
- 1; index
>= stop
; index
--) {
888 unsigned int offset
= index
== stop
? bprm
->p
& ~PAGE_MASK
: 0;
889 char *src
= kmap_local_page(bprm
->page
[index
]) + offset
;
890 sp
-= PAGE_SIZE
- offset
;
891 if (copy_to_user((void *) sp
, src
, PAGE_SIZE
- offset
) != 0)
903 EXPORT_SYMBOL(transfer_args_to_stack
);
905 #endif /* CONFIG_MMU */
907 static struct file
*do_open_execat(int fd
, struct filename
*name
, int flags
)
911 struct open_flags open_exec_flags
= {
912 .open_flag
= O_LARGEFILE
| O_RDONLY
| __FMODE_EXEC
,
913 .acc_mode
= MAY_EXEC
,
914 .intent
= LOOKUP_OPEN
,
915 .lookup_flags
= LOOKUP_FOLLOW
,
918 if ((flags
& ~(AT_SYMLINK_NOFOLLOW
| AT_EMPTY_PATH
)) != 0)
919 return ERR_PTR(-EINVAL
);
920 if (flags
& AT_SYMLINK_NOFOLLOW
)
921 open_exec_flags
.lookup_flags
&= ~LOOKUP_FOLLOW
;
922 if (flags
& AT_EMPTY_PATH
)
923 open_exec_flags
.lookup_flags
|= LOOKUP_EMPTY
;
925 file
= do_filp_open(fd
, name
, &open_exec_flags
);
930 * may_open() has already checked for this, so it should be
931 * impossible to trip now. But we need to be extra cautious
932 * and check again at the very end too.
935 if (WARN_ON_ONCE(!S_ISREG(file_inode(file
)->i_mode
) ||
936 path_noexec(&file
->f_path
)))
939 err
= deny_write_access(file
);
951 struct file
*open_exec(const char *name
)
953 struct filename
*filename
= getname_kernel(name
);
954 struct file
*f
= ERR_CAST(filename
);
956 if (!IS_ERR(filename
)) {
957 f
= do_open_execat(AT_FDCWD
, filename
, 0);
962 EXPORT_SYMBOL(open_exec
);
964 #if defined(CONFIG_BINFMT_FLAT) || defined(CONFIG_BINFMT_ELF_FDPIC)
965 ssize_t
read_code(struct file
*file
, unsigned long addr
, loff_t pos
, size_t len
)
967 ssize_t res
= vfs_read(file
, (void __user
*)addr
, len
, &pos
);
969 flush_icache_user_range(addr
, addr
+ len
);
972 EXPORT_SYMBOL(read_code
);
976 * Maps the mm_struct mm into the current task struct.
977 * On success, this function returns with exec_update_lock
980 static int exec_mmap(struct mm_struct
*mm
)
982 struct task_struct
*tsk
;
983 struct mm_struct
*old_mm
, *active_mm
;
986 /* Notify parent that we're no longer interested in the old VM */
988 old_mm
= current
->mm
;
989 exec_mm_release(tsk
, old_mm
);
991 ret
= down_write_killable(&tsk
->signal
->exec_update_lock
);
997 * If there is a pending fatal signal perhaps a signal
998 * whose default action is to create a coredump get
999 * out and die instead of going through with the exec.
1001 ret
= mmap_read_lock_killable(old_mm
);
1003 up_write(&tsk
->signal
->exec_update_lock
);
1009 membarrier_exec_mmap(mm
);
1011 local_irq_disable();
1012 active_mm
= tsk
->active_mm
;
1013 tsk
->active_mm
= mm
;
1017 * This prevents preemption while active_mm is being loaded and
1018 * it and mm are being updated, which could cause problems for
1019 * lazy tlb mm refcounting when these are updated by context
1020 * switches. Not all architectures can handle irqs off over
1023 if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM
))
1025 activate_mm(active_mm
, mm
);
1026 if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM
))
1032 mmap_read_unlock(old_mm
);
1033 BUG_ON(active_mm
!= old_mm
);
1034 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, old_mm
);
1035 mm_update_next_owner(old_mm
);
1039 mmdrop_lazy_tlb(active_mm
);
1043 static int de_thread(struct task_struct
*tsk
)
1045 struct signal_struct
*sig
= tsk
->signal
;
1046 struct sighand_struct
*oldsighand
= tsk
->sighand
;
1047 spinlock_t
*lock
= &oldsighand
->siglock
;
1049 if (thread_group_empty(tsk
))
1050 goto no_thread_group
;
1053 * Kill all other threads in the thread group.
1055 spin_lock_irq(lock
);
1056 if ((sig
->flags
& SIGNAL_GROUP_EXIT
) || sig
->group_exec_task
) {
1058 * Another group action in progress, just
1059 * return so that the signal is processed.
1061 spin_unlock_irq(lock
);
1065 sig
->group_exec_task
= tsk
;
1066 sig
->notify_count
= zap_other_threads(tsk
);
1067 if (!thread_group_leader(tsk
))
1068 sig
->notify_count
--;
1070 while (sig
->notify_count
) {
1071 __set_current_state(TASK_KILLABLE
);
1072 spin_unlock_irq(lock
);
1074 if (__fatal_signal_pending(tsk
))
1076 spin_lock_irq(lock
);
1078 spin_unlock_irq(lock
);
1081 * At this point all other threads have exited, all we have to
1082 * do is to wait for the thread group leader to become inactive,
1083 * and to assume its PID:
1085 if (!thread_group_leader(tsk
)) {
1086 struct task_struct
*leader
= tsk
->group_leader
;
1089 cgroup_threadgroup_change_begin(tsk
);
1090 write_lock_irq(&tasklist_lock
);
1092 * Do this under tasklist_lock to ensure that
1093 * exit_notify() can't miss ->group_exec_task
1095 sig
->notify_count
= -1;
1096 if (likely(leader
->exit_state
))
1098 __set_current_state(TASK_KILLABLE
);
1099 write_unlock_irq(&tasklist_lock
);
1100 cgroup_threadgroup_change_end(tsk
);
1102 if (__fatal_signal_pending(tsk
))
1107 * The only record we have of the real-time age of a
1108 * process, regardless of execs it's done, is start_time.
1109 * All the past CPU time is accumulated in signal_struct
1110 * from sister threads now dead. But in this non-leader
1111 * exec, nothing survives from the original leader thread,
1112 * whose birth marks the true age of this process now.
1113 * When we take on its identity by switching to its PID, we
1114 * also take its birthdate (always earlier than our own).
1116 tsk
->start_time
= leader
->start_time
;
1117 tsk
->start_boottime
= leader
->start_boottime
;
1119 BUG_ON(!same_thread_group(leader
, tsk
));
1121 * An exec() starts a new thread group with the
1122 * TGID of the previous thread group. Rehash the
1123 * two threads with a switched PID, and release
1124 * the former thread group leader:
1127 /* Become a process group leader with the old leader's pid.
1128 * The old leader becomes a thread of the this thread group.
1130 exchange_tids(tsk
, leader
);
1131 transfer_pid(leader
, tsk
, PIDTYPE_TGID
);
1132 transfer_pid(leader
, tsk
, PIDTYPE_PGID
);
1133 transfer_pid(leader
, tsk
, PIDTYPE_SID
);
1135 list_replace_rcu(&leader
->tasks
, &tsk
->tasks
);
1136 list_replace_init(&leader
->sibling
, &tsk
->sibling
);
1138 tsk
->group_leader
= tsk
;
1139 leader
->group_leader
= tsk
;
1141 tsk
->exit_signal
= SIGCHLD
;
1142 leader
->exit_signal
= -1;
1144 BUG_ON(leader
->exit_state
!= EXIT_ZOMBIE
);
1145 leader
->exit_state
= EXIT_DEAD
;
1148 * We are going to release_task()->ptrace_unlink() silently,
1149 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
1150 * the tracer won't block again waiting for this thread.
1152 if (unlikely(leader
->ptrace
))
1153 __wake_up_parent(leader
, leader
->parent
);
1154 write_unlock_irq(&tasklist_lock
);
1155 cgroup_threadgroup_change_end(tsk
);
1157 release_task(leader
);
1160 sig
->group_exec_task
= NULL
;
1161 sig
->notify_count
= 0;
1164 /* we have changed execution domain */
1165 tsk
->exit_signal
= SIGCHLD
;
1167 BUG_ON(!thread_group_leader(tsk
));
1171 /* protects against exit_notify() and __exit_signal() */
1172 read_lock(&tasklist_lock
);
1173 sig
->group_exec_task
= NULL
;
1174 sig
->notify_count
= 0;
1175 read_unlock(&tasklist_lock
);
1181 * This function makes sure the current process has its own signal table,
1182 * so that flush_signal_handlers can later reset the handlers without
1183 * disturbing other processes. (Other processes might share the signal
1184 * table via the CLONE_SIGHAND option to clone().)
1186 static int unshare_sighand(struct task_struct
*me
)
1188 struct sighand_struct
*oldsighand
= me
->sighand
;
1190 if (refcount_read(&oldsighand
->count
) != 1) {
1191 struct sighand_struct
*newsighand
;
1193 * This ->sighand is shared with the CLONE_SIGHAND
1194 * but not CLONE_THREAD task, switch to the new one.
1196 newsighand
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1200 refcount_set(&newsighand
->count
, 1);
1202 write_lock_irq(&tasklist_lock
);
1203 spin_lock(&oldsighand
->siglock
);
1204 memcpy(newsighand
->action
, oldsighand
->action
,
1205 sizeof(newsighand
->action
));
1206 rcu_assign_pointer(me
->sighand
, newsighand
);
1207 spin_unlock(&oldsighand
->siglock
);
1208 write_unlock_irq(&tasklist_lock
);
1210 __cleanup_sighand(oldsighand
);
1215 char *__get_task_comm(char *buf
, size_t buf_size
, struct task_struct
*tsk
)
1218 /* Always NUL terminated and zero-padded */
1219 strscpy_pad(buf
, tsk
->comm
, buf_size
);
1223 EXPORT_SYMBOL_GPL(__get_task_comm
);
1226 * These functions flushes out all traces of the currently running executable
1227 * so that a new one can be started
1230 void __set_task_comm(struct task_struct
*tsk
, const char *buf
, bool exec
)
1233 trace_task_rename(tsk
, buf
);
1234 strscpy_pad(tsk
->comm
, buf
, sizeof(tsk
->comm
));
1236 perf_event_comm(tsk
, exec
);
1240 * Calling this is the point of no return. None of the failures will be
1241 * seen by userspace since either the process is already taking a fatal
1242 * signal (via de_thread() or coredump), or will have SEGV raised
1243 * (after exec_mmap()) by search_binary_handler (see below).
1245 int begin_new_exec(struct linux_binprm
* bprm
)
1247 struct task_struct
*me
= current
;
1250 /* Once we are committed compute the creds */
1251 retval
= bprm_creds_from_file(bprm
);
1256 * Ensure all future errors are fatal.
1258 bprm
->point_of_no_return
= true;
1261 * Make this the only thread in the thread group.
1263 retval
= de_thread(me
);
1268 * Cancel any io_uring activity across execve
1270 io_uring_task_cancel();
1272 /* Ensure the files table is not shared. */
1273 retval
= unshare_files();
1278 * Must be called _before_ exec_mmap() as bprm->mm is
1279 * not visible until then. Doing it here also ensures
1280 * we don't race against replace_mm_exe_file().
1282 retval
= set_mm_exe_file(bprm
->mm
, bprm
->file
);
1286 /* If the binary is not readable then enforce mm->dumpable=0 */
1287 would_dump(bprm
, bprm
->file
);
1288 if (bprm
->have_execfd
)
1289 would_dump(bprm
, bprm
->executable
);
1292 * Release all of the old mmap stuff
1294 acct_arg_size(bprm
, 0);
1295 retval
= exec_mmap(bprm
->mm
);
1301 retval
= exec_task_namespaces();
1305 #ifdef CONFIG_POSIX_TIMERS
1306 spin_lock_irq(&me
->sighand
->siglock
);
1307 posix_cpu_timers_exit(me
);
1308 spin_unlock_irq(&me
->sighand
->siglock
);
1310 flush_itimer_signals();
1314 * Make the signal table private.
1316 retval
= unshare_sighand(me
);
1320 me
->flags
&= ~(PF_RANDOMIZE
| PF_FORKNOEXEC
|
1321 PF_NOFREEZE
| PF_NO_SETAFFINITY
);
1323 me
->personality
&= ~bprm
->per_clear
;
1325 clear_syscall_work_syscall_user_dispatch(me
);
1328 * We have to apply CLOEXEC before we change whether the process is
1329 * dumpable (in setup_new_exec) to avoid a race with a process in userspace
1330 * trying to access the should-be-closed file descriptors of a process
1331 * undergoing exec(2).
1333 do_close_on_exec(me
->files
);
1335 if (bprm
->secureexec
) {
1336 /* Make sure parent cannot signal privileged process. */
1337 me
->pdeath_signal
= 0;
1340 * For secureexec, reset the stack limit to sane default to
1341 * avoid bad behavior from the prior rlimits. This has to
1342 * happen before arch_pick_mmap_layout(), which examines
1343 * RLIMIT_STACK, but after the point of no return to avoid
1344 * needing to clean up the change on failure.
1346 if (bprm
->rlim_stack
.rlim_cur
> _STK_LIM
)
1347 bprm
->rlim_stack
.rlim_cur
= _STK_LIM
;
1350 me
->sas_ss_sp
= me
->sas_ss_size
= 0;
1353 * Figure out dumpability. Note that this checking only of current
1354 * is wrong, but userspace depends on it. This should be testing
1355 * bprm->secureexec instead.
1357 if (bprm
->interp_flags
& BINPRM_FLAGS_ENFORCE_NONDUMP
||
1358 !(uid_eq(current_euid(), current_uid()) &&
1359 gid_eq(current_egid(), current_gid())))
1360 set_dumpable(current
->mm
, suid_dumpable
);
1362 set_dumpable(current
->mm
, SUID_DUMP_USER
);
1365 __set_task_comm(me
, kbasename(bprm
->filename
), true);
1367 /* An exec changes our domain. We are no longer part of the thread
1369 WRITE_ONCE(me
->self_exec_id
, me
->self_exec_id
+ 1);
1370 flush_signal_handlers(me
, 0);
1372 retval
= set_cred_ucounts(bprm
->cred
);
1377 * install the new credentials for this executable
1379 security_bprm_committing_creds(bprm
);
1381 commit_creds(bprm
->cred
);
1385 * Disable monitoring for regular users
1386 * when executing setuid binaries. Must
1387 * wait until new credentials are committed
1388 * by commit_creds() above
1390 if (get_dumpable(me
->mm
) != SUID_DUMP_USER
)
1391 perf_event_exit_task(me
);
1393 * cred_guard_mutex must be held at least to this point to prevent
1394 * ptrace_attach() from altering our determination of the task's
1395 * credentials; any time after this it may be unlocked.
1397 security_bprm_committed_creds(bprm
);
1399 /* Pass the opened binary to the interpreter. */
1400 if (bprm
->have_execfd
) {
1401 retval
= get_unused_fd_flags(0);
1404 fd_install(retval
, bprm
->executable
);
1405 bprm
->executable
= NULL
;
1406 bprm
->execfd
= retval
;
1411 up_write(&me
->signal
->exec_update_lock
);
1415 EXPORT_SYMBOL(begin_new_exec
);
1417 void would_dump(struct linux_binprm
*bprm
, struct file
*file
)
1419 struct inode
*inode
= file_inode(file
);
1420 struct mnt_idmap
*idmap
= file_mnt_idmap(file
);
1421 if (inode_permission(idmap
, inode
, MAY_READ
) < 0) {
1422 struct user_namespace
*old
, *user_ns
;
1423 bprm
->interp_flags
|= BINPRM_FLAGS_ENFORCE_NONDUMP
;
1425 /* Ensure mm->user_ns contains the executable */
1426 user_ns
= old
= bprm
->mm
->user_ns
;
1427 while ((user_ns
!= &init_user_ns
) &&
1428 !privileged_wrt_inode_uidgid(user_ns
, idmap
, inode
))
1429 user_ns
= user_ns
->parent
;
1431 if (old
!= user_ns
) {
1432 bprm
->mm
->user_ns
= get_user_ns(user_ns
);
1437 EXPORT_SYMBOL(would_dump
);
1439 void setup_new_exec(struct linux_binprm
* bprm
)
1441 /* Setup things that can depend upon the personality */
1442 struct task_struct
*me
= current
;
1444 arch_pick_mmap_layout(me
->mm
, &bprm
->rlim_stack
);
1446 arch_setup_new_exec();
1448 /* Set the new mm task size. We have to do that late because it may
1449 * depend on TIF_32BIT which is only updated in flush_thread() on
1450 * some architectures like powerpc
1452 me
->mm
->task_size
= TASK_SIZE
;
1453 up_write(&me
->signal
->exec_update_lock
);
1454 mutex_unlock(&me
->signal
->cred_guard_mutex
);
1456 EXPORT_SYMBOL(setup_new_exec
);
1458 /* Runs immediately before start_thread() takes over. */
1459 void finalize_exec(struct linux_binprm
*bprm
)
1461 /* Store any stack rlimit changes before starting thread. */
1462 task_lock(current
->group_leader
);
1463 current
->signal
->rlim
[RLIMIT_STACK
] = bprm
->rlim_stack
;
1464 task_unlock(current
->group_leader
);
1466 EXPORT_SYMBOL(finalize_exec
);
1469 * Prepare credentials and lock ->cred_guard_mutex.
1470 * setup_new_exec() commits the new creds and drops the lock.
1471 * Or, if exec fails before, free_bprm() should release ->cred
1474 static int prepare_bprm_creds(struct linux_binprm
*bprm
)
1476 if (mutex_lock_interruptible(¤t
->signal
->cred_guard_mutex
))
1477 return -ERESTARTNOINTR
;
1479 bprm
->cred
= prepare_exec_creds();
1480 if (likely(bprm
->cred
))
1483 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1487 static void free_bprm(struct linux_binprm
*bprm
)
1490 acct_arg_size(bprm
, 0);
1493 free_arg_pages(bprm
);
1495 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1496 abort_creds(bprm
->cred
);
1499 allow_write_access(bprm
->file
);
1502 if (bprm
->executable
)
1503 fput(bprm
->executable
);
1504 /* If a binfmt changed the interp, free it. */
1505 if (bprm
->interp
!= bprm
->filename
)
1506 kfree(bprm
->interp
);
1507 kfree(bprm
->fdpath
);
1511 static struct linux_binprm
*alloc_bprm(int fd
, struct filename
*filename
, int flags
)
1513 struct linux_binprm
*bprm
;
1515 int retval
= -ENOMEM
;
1517 file
= do_open_execat(fd
, filename
, flags
);
1519 return ERR_CAST(file
);
1521 bprm
= kzalloc(sizeof(*bprm
), GFP_KERNEL
);
1523 allow_write_access(file
);
1525 return ERR_PTR(-ENOMEM
);
1530 if (fd
== AT_FDCWD
|| filename
->name
[0] == '/') {
1531 bprm
->filename
= filename
->name
;
1533 if (filename
->name
[0] == '\0')
1534 bprm
->fdpath
= kasprintf(GFP_KERNEL
, "/dev/fd/%d", fd
);
1536 bprm
->fdpath
= kasprintf(GFP_KERNEL
, "/dev/fd/%d/%s",
1537 fd
, filename
->name
);
1542 * Record that a name derived from an O_CLOEXEC fd will be
1543 * inaccessible after exec. This allows the code in exec to
1544 * choose to fail when the executable is not mmaped into the
1545 * interpreter and an open file descriptor is not passed to
1546 * the interpreter. This makes for a better user experience
1547 * than having the interpreter start and then immediately fail
1548 * when it finds the executable is inaccessible.
1550 if (get_close_on_exec(fd
))
1551 bprm
->interp_flags
|= BINPRM_FLAGS_PATH_INACCESSIBLE
;
1553 bprm
->filename
= bprm
->fdpath
;
1555 bprm
->interp
= bprm
->filename
;
1557 retval
= bprm_mm_init(bprm
);
1563 return ERR_PTR(retval
);
1566 int bprm_change_interp(const char *interp
, struct linux_binprm
*bprm
)
1568 /* If a binfmt changed the interp, free it first. */
1569 if (bprm
->interp
!= bprm
->filename
)
1570 kfree(bprm
->interp
);
1571 bprm
->interp
= kstrdup(interp
, GFP_KERNEL
);
1576 EXPORT_SYMBOL(bprm_change_interp
);
1579 * determine how safe it is to execute the proposed program
1580 * - the caller must hold ->cred_guard_mutex to protect against
1581 * PTRACE_ATTACH or seccomp thread-sync
1583 static void check_unsafe_exec(struct linux_binprm
*bprm
)
1585 struct task_struct
*p
= current
, *t
;
1589 bprm
->unsafe
|= LSM_UNSAFE_PTRACE
;
1592 * This isn't strictly necessary, but it makes it harder for LSMs to
1595 if (task_no_new_privs(current
))
1596 bprm
->unsafe
|= LSM_UNSAFE_NO_NEW_PRIVS
;
1599 * If another task is sharing our fs, we cannot safely
1600 * suid exec because the differently privileged task
1601 * will be able to manipulate the current directory, etc.
1602 * It would be nice to force an unshare instead...
1605 spin_lock(&p
->fs
->lock
);
1607 for_other_threads(p
, t
) {
1613 if (p
->fs
->users
> n_fs
)
1614 bprm
->unsafe
|= LSM_UNSAFE_SHARE
;
1617 spin_unlock(&p
->fs
->lock
);
1620 static void bprm_fill_uid(struct linux_binprm
*bprm
, struct file
*file
)
1622 /* Handle suid and sgid on files */
1623 struct mnt_idmap
*idmap
;
1624 struct inode
*inode
= file_inode(file
);
1629 if (!mnt_may_suid(file
->f_path
.mnt
))
1632 if (task_no_new_privs(current
))
1635 mode
= READ_ONCE(inode
->i_mode
);
1636 if (!(mode
& (S_ISUID
|S_ISGID
)))
1639 idmap
= file_mnt_idmap(file
);
1641 /* Be careful if suid/sgid is set */
1644 /* reload atomically mode/uid/gid now that lock held */
1645 mode
= inode
->i_mode
;
1646 vfsuid
= i_uid_into_vfsuid(idmap
, inode
);
1647 vfsgid
= i_gid_into_vfsgid(idmap
, inode
);
1648 inode_unlock(inode
);
1650 /* We ignore suid/sgid if there are no mappings for them in the ns */
1651 if (!vfsuid_has_mapping(bprm
->cred
->user_ns
, vfsuid
) ||
1652 !vfsgid_has_mapping(bprm
->cred
->user_ns
, vfsgid
))
1655 if (mode
& S_ISUID
) {
1656 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1657 bprm
->cred
->euid
= vfsuid_into_kuid(vfsuid
);
1660 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
1661 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1662 bprm
->cred
->egid
= vfsgid_into_kgid(vfsgid
);
1667 * Compute brpm->cred based upon the final binary.
1669 static int bprm_creds_from_file(struct linux_binprm
*bprm
)
1671 /* Compute creds based on which file? */
1672 struct file
*file
= bprm
->execfd_creds
? bprm
->executable
: bprm
->file
;
1674 bprm_fill_uid(bprm
, file
);
1675 return security_bprm_creds_from_file(bprm
, file
);
1679 * Fill the binprm structure from the inode.
1680 * Read the first BINPRM_BUF_SIZE bytes
1682 * This may be called multiple times for binary chains (scripts for example).
1684 static int prepare_binprm(struct linux_binprm
*bprm
)
1688 memset(bprm
->buf
, 0, BINPRM_BUF_SIZE
);
1689 return kernel_read(bprm
->file
, bprm
->buf
, BINPRM_BUF_SIZE
, &pos
);
1693 * Arguments are '\0' separated strings found at the location bprm->p
1694 * points to; chop off the first by relocating brpm->p to right after
1695 * the first '\0' encountered.
1697 int remove_arg_zero(struct linux_binprm
*bprm
)
1700 unsigned long offset
;
1708 offset
= bprm
->p
& ~PAGE_MASK
;
1709 page
= get_arg_page(bprm
, bprm
->p
, 0);
1714 kaddr
= kmap_local_page(page
);
1716 for (; offset
< PAGE_SIZE
&& kaddr
[offset
];
1717 offset
++, bprm
->p
++)
1720 kunmap_local(kaddr
);
1722 } while (offset
== PAGE_SIZE
);
1731 EXPORT_SYMBOL(remove_arg_zero
);
1733 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1735 * cycle the list of binary formats handler, until one recognizes the image
1737 static int search_binary_handler(struct linux_binprm
*bprm
)
1739 bool need_retry
= IS_ENABLED(CONFIG_MODULES
);
1740 struct linux_binfmt
*fmt
;
1743 retval
= prepare_binprm(bprm
);
1747 retval
= security_bprm_check(bprm
);
1753 read_lock(&binfmt_lock
);
1754 list_for_each_entry(fmt
, &formats
, lh
) {
1755 if (!try_module_get(fmt
->module
))
1757 read_unlock(&binfmt_lock
);
1759 retval
= fmt
->load_binary(bprm
);
1761 read_lock(&binfmt_lock
);
1763 if (bprm
->point_of_no_return
|| (retval
!= -ENOEXEC
)) {
1764 read_unlock(&binfmt_lock
);
1768 read_unlock(&binfmt_lock
);
1771 if (printable(bprm
->buf
[0]) && printable(bprm
->buf
[1]) &&
1772 printable(bprm
->buf
[2]) && printable(bprm
->buf
[3]))
1774 if (request_module("binfmt-%04x", *(ushort
*)(bprm
->buf
+ 2)) < 0)
1783 /* binfmt handlers will call back into begin_new_exec() on success. */
1784 static int exec_binprm(struct linux_binprm
*bprm
)
1786 pid_t old_pid
, old_vpid
;
1789 /* Need to fetch pid before load_binary changes it */
1790 old_pid
= current
->pid
;
1792 old_vpid
= task_pid_nr_ns(current
, task_active_pid_ns(current
->parent
));
1795 /* This allows 4 levels of binfmt rewrites before failing hard. */
1796 for (depth
= 0;; depth
++) {
1801 ret
= search_binary_handler(bprm
);
1804 if (!bprm
->interpreter
)
1808 bprm
->file
= bprm
->interpreter
;
1809 bprm
->interpreter
= NULL
;
1811 allow_write_access(exec
);
1812 if (unlikely(bprm
->have_execfd
)) {
1813 if (bprm
->executable
) {
1817 bprm
->executable
= exec
;
1823 trace_sched_process_exec(current
, old_pid
, bprm
);
1824 ptrace_event(PTRACE_EVENT_EXEC
, old_vpid
);
1825 proc_exec_connector(current
);
1830 * sys_execve() executes a new program.
1832 static int bprm_execve(struct linux_binprm
*bprm
)
1836 retval
= prepare_bprm_creds(bprm
);
1841 * Check for unsafe execution states before exec_binprm(), which
1842 * will call back into begin_new_exec(), into bprm_creds_from_file(),
1843 * where setuid-ness is evaluated.
1845 check_unsafe_exec(bprm
);
1846 current
->in_execve
= 1;
1847 sched_mm_cid_before_execve(current
);
1851 /* Set the unchanging part of bprm->cred */
1852 retval
= security_bprm_creds_for_exec(bprm
);
1856 retval
= exec_binprm(bprm
);
1860 sched_mm_cid_after_execve(current
);
1861 /* execve succeeded */
1862 current
->fs
->in_exec
= 0;
1863 current
->in_execve
= 0;
1864 rseq_execve(current
);
1865 user_events_execve(current
);
1866 acct_update_integrals(current
);
1867 task_numa_free(current
, false);
1872 * If past the point of no return ensure the code never
1873 * returns to the userspace process. Use an existing fatal
1874 * signal if present otherwise terminate the process with
1877 if (bprm
->point_of_no_return
&& !fatal_signal_pending(current
))
1878 force_fatal_sig(SIGSEGV
);
1880 sched_mm_cid_after_execve(current
);
1881 current
->fs
->in_exec
= 0;
1882 current
->in_execve
= 0;
1887 static int do_execveat_common(int fd
, struct filename
*filename
,
1888 struct user_arg_ptr argv
,
1889 struct user_arg_ptr envp
,
1892 struct linux_binprm
*bprm
;
1895 if (IS_ERR(filename
))
1896 return PTR_ERR(filename
);
1899 * We move the actual failure in case of RLIMIT_NPROC excess from
1900 * set*uid() to execve() because too many poorly written programs
1901 * don't check setuid() return code. Here we additionally recheck
1902 * whether NPROC limit is still exceeded.
1904 if ((current
->flags
& PF_NPROC_EXCEEDED
) &&
1905 is_rlimit_overlimit(current_ucounts(), UCOUNT_RLIMIT_NPROC
, rlimit(RLIMIT_NPROC
))) {
1910 /* We're below the limit (still or again), so we don't want to make
1911 * further execve() calls fail. */
1912 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1914 bprm
= alloc_bprm(fd
, filename
, flags
);
1916 retval
= PTR_ERR(bprm
);
1920 retval
= count(argv
, MAX_ARG_STRINGS
);
1922 pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
1923 current
->comm
, bprm
->filename
);
1926 bprm
->argc
= retval
;
1928 retval
= count(envp
, MAX_ARG_STRINGS
);
1931 bprm
->envc
= retval
;
1933 retval
= bprm_stack_limits(bprm
);
1937 retval
= copy_string_kernel(bprm
->filename
, bprm
);
1940 bprm
->exec
= bprm
->p
;
1942 retval
= copy_strings(bprm
->envc
, envp
, bprm
);
1946 retval
= copy_strings(bprm
->argc
, argv
, bprm
);
1951 * When argv is empty, add an empty string ("") as argv[0] to
1952 * ensure confused userspace programs that start processing
1953 * from argv[1] won't end up walking envp. See also
1954 * bprm_stack_limits().
1956 if (bprm
->argc
== 0) {
1957 retval
= copy_string_kernel("", bprm
);
1963 retval
= bprm_execve(bprm
);
1972 int kernel_execve(const char *kernel_filename
,
1973 const char *const *argv
, const char *const *envp
)
1975 struct filename
*filename
;
1976 struct linux_binprm
*bprm
;
1980 /* It is non-sense for kernel threads to call execve */
1981 if (WARN_ON_ONCE(current
->flags
& PF_KTHREAD
))
1984 filename
= getname_kernel(kernel_filename
);
1985 if (IS_ERR(filename
))
1986 return PTR_ERR(filename
);
1988 bprm
= alloc_bprm(fd
, filename
, 0);
1990 retval
= PTR_ERR(bprm
);
1994 retval
= count_strings_kernel(argv
);
1995 if (WARN_ON_ONCE(retval
== 0))
1999 bprm
->argc
= retval
;
2001 retval
= count_strings_kernel(envp
);
2004 bprm
->envc
= retval
;
2006 retval
= bprm_stack_limits(bprm
);
2010 retval
= copy_string_kernel(bprm
->filename
, bprm
);
2013 bprm
->exec
= bprm
->p
;
2015 retval
= copy_strings_kernel(bprm
->envc
, envp
, bprm
);
2019 retval
= copy_strings_kernel(bprm
->argc
, argv
, bprm
);
2023 retval
= bprm_execve(bprm
);
2031 static int do_execve(struct filename
*filename
,
2032 const char __user
*const __user
*__argv
,
2033 const char __user
*const __user
*__envp
)
2035 struct user_arg_ptr argv
= { .ptr
.native
= __argv
};
2036 struct user_arg_ptr envp
= { .ptr
.native
= __envp
};
2037 return do_execveat_common(AT_FDCWD
, filename
, argv
, envp
, 0);
2040 static int do_execveat(int fd
, struct filename
*filename
,
2041 const char __user
*const __user
*__argv
,
2042 const char __user
*const __user
*__envp
,
2045 struct user_arg_ptr argv
= { .ptr
.native
= __argv
};
2046 struct user_arg_ptr envp
= { .ptr
.native
= __envp
};
2048 return do_execveat_common(fd
, filename
, argv
, envp
, flags
);
2051 #ifdef CONFIG_COMPAT
2052 static int compat_do_execve(struct filename
*filename
,
2053 const compat_uptr_t __user
*__argv
,
2054 const compat_uptr_t __user
*__envp
)
2056 struct user_arg_ptr argv
= {
2058 .ptr
.compat
= __argv
,
2060 struct user_arg_ptr envp
= {
2062 .ptr
.compat
= __envp
,
2064 return do_execveat_common(AT_FDCWD
, filename
, argv
, envp
, 0);
2067 static int compat_do_execveat(int fd
, struct filename
*filename
,
2068 const compat_uptr_t __user
*__argv
,
2069 const compat_uptr_t __user
*__envp
,
2072 struct user_arg_ptr argv
= {
2074 .ptr
.compat
= __argv
,
2076 struct user_arg_ptr envp
= {
2078 .ptr
.compat
= __envp
,
2080 return do_execveat_common(fd
, filename
, argv
, envp
, flags
);
2084 void set_binfmt(struct linux_binfmt
*new)
2086 struct mm_struct
*mm
= current
->mm
;
2089 module_put(mm
->binfmt
->module
);
2093 __module_get(new->module
);
2095 EXPORT_SYMBOL(set_binfmt
);
2098 * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
2100 void set_dumpable(struct mm_struct
*mm
, int value
)
2102 if (WARN_ON((unsigned)value
> SUID_DUMP_ROOT
))
2105 set_mask_bits(&mm
->flags
, MMF_DUMPABLE_MASK
, value
);
2108 SYSCALL_DEFINE3(execve
,
2109 const char __user
*, filename
,
2110 const char __user
*const __user
*, argv
,
2111 const char __user
*const __user
*, envp
)
2113 return do_execve(getname(filename
), argv
, envp
);
2116 SYSCALL_DEFINE5(execveat
,
2117 int, fd
, const char __user
*, filename
,
2118 const char __user
*const __user
*, argv
,
2119 const char __user
*const __user
*, envp
,
2122 return do_execveat(fd
,
2123 getname_uflags(filename
, flags
),
2127 #ifdef CONFIG_COMPAT
2128 COMPAT_SYSCALL_DEFINE3(execve
, const char __user
*, filename
,
2129 const compat_uptr_t __user
*, argv
,
2130 const compat_uptr_t __user
*, envp
)
2132 return compat_do_execve(getname(filename
), argv
, envp
);
2135 COMPAT_SYSCALL_DEFINE5(execveat
, int, fd
,
2136 const char __user
*, filename
,
2137 const compat_uptr_t __user
*, argv
,
2138 const compat_uptr_t __user
*, envp
,
2141 return compat_do_execveat(fd
,
2142 getname_uflags(filename
, flags
),
2147 #ifdef CONFIG_SYSCTL
2149 static int proc_dointvec_minmax_coredump(struct ctl_table
*table
, int write
,
2150 void *buffer
, size_t *lenp
, loff_t
*ppos
)
2152 int error
= proc_dointvec_minmax(table
, write
, buffer
, lenp
, ppos
);
2155 validate_coredump_safety();
2159 static struct ctl_table fs_exec_sysctls
[] = {
2161 .procname
= "suid_dumpable",
2162 .data
= &suid_dumpable
,
2163 .maxlen
= sizeof(int),
2165 .proc_handler
= proc_dointvec_minmax_coredump
,
2166 .extra1
= SYSCTL_ZERO
,
2167 .extra2
= SYSCTL_TWO
,
2171 static int __init
init_fs_exec_sysctls(void)
2173 register_sysctl_init("fs", fs_exec_sysctls
);
2177 fs_initcall(init_fs_exec_sysctls
);
2178 #endif /* CONFIG_SYSCTL */