4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * #!-checking implemented by tytso.
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.
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.
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
25 #include <linux/slab.h>
26 #include <linux/file.h>
27 #include <linux/fdtable.h>
29 #include <linux/stat.h>
30 #include <linux/fcntl.h>
31 #include <linux/swap.h>
32 #include <linux/string.h>
33 #include <linux/init.h>
34 #include <linux/pagemap.h>
35 #include <linux/perf_event.h>
36 #include <linux/highmem.h>
37 #include <linux/spinlock.h>
38 #include <linux/key.h>
39 #include <linux/personality.h>
40 #include <linux/binfmts.h>
41 #include <linux/utsname.h>
42 #include <linux/pid_namespace.h>
43 #include <linux/module.h>
44 #include <linux/namei.h>
45 #include <linux/mount.h>
46 #include <linux/security.h>
47 #include <linux/syscalls.h>
48 #include <linux/tsacct_kern.h>
49 #include <linux/cn_proc.h>
50 #include <linux/audit.h>
51 #include <linux/tracehook.h>
52 #include <linux/kmod.h>
53 #include <linux/fsnotify.h>
54 #include <linux/fs_struct.h>
55 #include <linux/pipe_fs_i.h>
56 #include <linux/oom.h>
57 #include <linux/compat.h>
59 #include <asm/uaccess.h>
60 #include <asm/mmu_context.h>
63 #include <trace/events/task.h>
67 #include <trace/events/sched.h>
69 int suid_dumpable
= 0;
71 static LIST_HEAD(formats
);
72 static DEFINE_RWLOCK(binfmt_lock
);
74 void __register_binfmt(struct linux_binfmt
* fmt
, int insert
)
77 write_lock(&binfmt_lock
);
78 insert
? list_add(&fmt
->lh
, &formats
) :
79 list_add_tail(&fmt
->lh
, &formats
);
80 write_unlock(&binfmt_lock
);
83 EXPORT_SYMBOL(__register_binfmt
);
85 void unregister_binfmt(struct linux_binfmt
* fmt
)
87 write_lock(&binfmt_lock
);
89 write_unlock(&binfmt_lock
);
92 EXPORT_SYMBOL(unregister_binfmt
);
94 static inline void put_binfmt(struct linux_binfmt
* fmt
)
96 module_put(fmt
->module
);
100 * Note that a shared library must be both readable and executable due to
103 * Also note that we take the address to load from from the file itself.
105 SYSCALL_DEFINE1(uselib
, const char __user
*, library
)
108 struct filename
*tmp
= getname(library
);
109 int error
= PTR_ERR(tmp
);
110 static const struct open_flags uselib_flags
= {
111 .open_flag
= O_LARGEFILE
| O_RDONLY
| __FMODE_EXEC
,
112 .acc_mode
= MAY_READ
| MAY_EXEC
| MAY_OPEN
,
113 .intent
= LOOKUP_OPEN
119 file
= do_filp_open(AT_FDCWD
, tmp
, &uselib_flags
, LOOKUP_FOLLOW
);
121 error
= PTR_ERR(file
);
126 if (!S_ISREG(file_inode(file
)->i_mode
))
130 if (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
)
137 struct linux_binfmt
* fmt
;
139 read_lock(&binfmt_lock
);
140 list_for_each_entry(fmt
, &formats
, lh
) {
141 if (!fmt
->load_shlib
)
143 if (!try_module_get(fmt
->module
))
145 read_unlock(&binfmt_lock
);
146 error
= fmt
->load_shlib(file
);
147 read_lock(&binfmt_lock
);
149 if (error
!= -ENOEXEC
)
152 read_unlock(&binfmt_lock
);
162 * The nascent bprm->mm is not visible until exec_mmap() but it can
163 * use a lot of memory, account these pages in current->mm temporary
164 * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
165 * change the counter back via acct_arg_size(0).
167 static void acct_arg_size(struct linux_binprm
*bprm
, unsigned long pages
)
169 struct mm_struct
*mm
= current
->mm
;
170 long diff
= (long)(pages
- bprm
->vma_pages
);
175 bprm
->vma_pages
= pages
;
176 add_mm_counter(mm
, MM_ANONPAGES
, diff
);
179 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
185 #ifdef CONFIG_STACK_GROWSUP
187 ret
= expand_downwards(bprm
->vma
, pos
);
192 ret
= get_user_pages(current
, bprm
->mm
, pos
,
193 1, write
, 1, &page
, NULL
);
198 unsigned long size
= bprm
->vma
->vm_end
- bprm
->vma
->vm_start
;
201 acct_arg_size(bprm
, size
/ PAGE_SIZE
);
204 * We've historically supported up to 32 pages (ARG_MAX)
205 * of argument strings even with small stacks
211 * Limit to 1/4-th the stack size for the argv+env strings.
213 * - the remaining binfmt code will not run out of stack space,
214 * - the program will have a reasonable amount of stack left
217 rlim
= current
->signal
->rlim
;
218 if (size
> ACCESS_ONCE(rlim
[RLIMIT_STACK
].rlim_cur
) / 4) {
227 static void put_arg_page(struct page
*page
)
232 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
236 static void free_arg_pages(struct linux_binprm
*bprm
)
240 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
243 flush_cache_page(bprm
->vma
, pos
, page_to_pfn(page
));
246 static int __bprm_mm_init(struct linux_binprm
*bprm
)
249 struct vm_area_struct
*vma
= NULL
;
250 struct mm_struct
*mm
= bprm
->mm
;
252 bprm
->vma
= vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
256 down_write(&mm
->mmap_sem
);
260 * Place the stack at the largest stack address the architecture
261 * supports. Later, we'll move this to an appropriate place. We don't
262 * use STACK_TOP because that can depend on attributes which aren't
265 BUILD_BUG_ON(VM_STACK_FLAGS
& VM_STACK_INCOMPLETE_SETUP
);
266 vma
->vm_end
= STACK_TOP_MAX
;
267 vma
->vm_start
= vma
->vm_end
- PAGE_SIZE
;
268 vma
->vm_flags
= VM_STACK_FLAGS
| VM_STACK_INCOMPLETE_SETUP
;
269 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
270 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
272 err
= insert_vm_struct(mm
, vma
);
276 mm
->stack_vm
= mm
->total_vm
= 1;
277 up_write(&mm
->mmap_sem
);
278 bprm
->p
= vma
->vm_end
- sizeof(void *);
281 up_write(&mm
->mmap_sem
);
283 kmem_cache_free(vm_area_cachep
, vma
);
287 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
289 return len
<= MAX_ARG_STRLEN
;
294 static inline void acct_arg_size(struct linux_binprm
*bprm
, unsigned long pages
)
298 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
303 page
= bprm
->page
[pos
/ PAGE_SIZE
];
304 if (!page
&& write
) {
305 page
= alloc_page(GFP_HIGHUSER
|__GFP_ZERO
);
308 bprm
->page
[pos
/ PAGE_SIZE
] = page
;
314 static void put_arg_page(struct page
*page
)
318 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
321 __free_page(bprm
->page
[i
]);
322 bprm
->page
[i
] = NULL
;
326 static void free_arg_pages(struct linux_binprm
*bprm
)
330 for (i
= 0; i
< MAX_ARG_PAGES
; i
++)
331 free_arg_page(bprm
, i
);
334 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
339 static int __bprm_mm_init(struct linux_binprm
*bprm
)
341 bprm
->p
= PAGE_SIZE
* MAX_ARG_PAGES
- sizeof(void *);
345 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
347 return len
<= bprm
->p
;
350 #endif /* CONFIG_MMU */
353 * Create a new mm_struct and populate it with a temporary stack
354 * vm_area_struct. We don't have enough context at this point to set the stack
355 * flags, permissions, and offset, so we use temporary values. We'll update
356 * them later in setup_arg_pages().
358 static int bprm_mm_init(struct linux_binprm
*bprm
)
361 struct mm_struct
*mm
= NULL
;
363 bprm
->mm
= mm
= mm_alloc();
368 err
= init_new_context(current
, mm
);
372 err
= __bprm_mm_init(bprm
);
387 struct user_arg_ptr
{
392 const char __user
*const __user
*native
;
394 const compat_uptr_t __user
*compat
;
399 static const char __user
*get_user_arg_ptr(struct user_arg_ptr argv
, int nr
)
401 const char __user
*native
;
404 if (unlikely(argv
.is_compat
)) {
405 compat_uptr_t compat
;
407 if (get_user(compat
, argv
.ptr
.compat
+ nr
))
408 return ERR_PTR(-EFAULT
);
410 return compat_ptr(compat
);
414 if (get_user(native
, argv
.ptr
.native
+ nr
))
415 return ERR_PTR(-EFAULT
);
421 * count() counts the number of strings in array ARGV.
423 static int count(struct user_arg_ptr argv
, int max
)
427 if (argv
.ptr
.native
!= NULL
) {
429 const char __user
*p
= get_user_arg_ptr(argv
, i
);
441 if (fatal_signal_pending(current
))
442 return -ERESTARTNOHAND
;
450 * 'copy_strings()' copies argument/environment strings from the old
451 * processes's memory to the new process's stack. The call to get_user_pages()
452 * ensures the destination page is created and not swapped out.
454 static int copy_strings(int argc
, struct user_arg_ptr argv
,
455 struct linux_binprm
*bprm
)
457 struct page
*kmapped_page
= NULL
;
459 unsigned long kpos
= 0;
463 const char __user
*str
;
468 str
= get_user_arg_ptr(argv
, argc
);
472 len
= strnlen_user(str
, MAX_ARG_STRLEN
);
477 if (!valid_arg_len(bprm
, len
))
480 /* We're going to work our way backwords. */
486 int offset
, bytes_to_copy
;
488 if (fatal_signal_pending(current
)) {
489 ret
= -ERESTARTNOHAND
;
494 offset
= pos
% PAGE_SIZE
;
498 bytes_to_copy
= offset
;
499 if (bytes_to_copy
> len
)
502 offset
-= bytes_to_copy
;
503 pos
-= bytes_to_copy
;
504 str
-= bytes_to_copy
;
505 len
-= bytes_to_copy
;
507 if (!kmapped_page
|| kpos
!= (pos
& PAGE_MASK
)) {
510 page
= get_arg_page(bprm
, pos
, 1);
517 flush_kernel_dcache_page(kmapped_page
);
518 kunmap(kmapped_page
);
519 put_arg_page(kmapped_page
);
522 kaddr
= kmap(kmapped_page
);
523 kpos
= pos
& PAGE_MASK
;
524 flush_arg_page(bprm
, kpos
, kmapped_page
);
526 if (copy_from_user(kaddr
+offset
, str
, bytes_to_copy
)) {
535 flush_kernel_dcache_page(kmapped_page
);
536 kunmap(kmapped_page
);
537 put_arg_page(kmapped_page
);
543 * Like copy_strings, but get argv and its values from kernel memory.
545 int copy_strings_kernel(int argc
, const char *const *__argv
,
546 struct linux_binprm
*bprm
)
549 mm_segment_t oldfs
= get_fs();
550 struct user_arg_ptr argv
= {
551 .ptr
.native
= (const char __user
*const __user
*)__argv
,
555 r
= copy_strings(argc
, argv
, bprm
);
560 EXPORT_SYMBOL(copy_strings_kernel
);
565 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
566 * the binfmt code determines where the new stack should reside, we shift it to
567 * its final location. The process proceeds as follows:
569 * 1) Use shift to calculate the new vma endpoints.
570 * 2) Extend vma to cover both the old and new ranges. This ensures the
571 * arguments passed to subsequent functions are consistent.
572 * 3) Move vma's page tables to the new range.
573 * 4) Free up any cleared pgd range.
574 * 5) Shrink the vma to cover only the new range.
576 static int shift_arg_pages(struct vm_area_struct
*vma
, unsigned long shift
)
578 struct mm_struct
*mm
= vma
->vm_mm
;
579 unsigned long old_start
= vma
->vm_start
;
580 unsigned long old_end
= vma
->vm_end
;
581 unsigned long length
= old_end
- old_start
;
582 unsigned long new_start
= old_start
- shift
;
583 unsigned long new_end
= old_end
- shift
;
584 struct mmu_gather tlb
;
586 BUG_ON(new_start
> new_end
);
589 * ensure there are no vmas between where we want to go
592 if (vma
!= find_vma(mm
, new_start
))
596 * cover the whole range: [new_start, old_end)
598 if (vma_adjust(vma
, new_start
, old_end
, vma
->vm_pgoff
, NULL
))
602 * move the page tables downwards, on failure we rely on
603 * process cleanup to remove whatever mess we made.
605 if (length
!= move_page_tables(vma
, old_start
,
606 vma
, new_start
, length
, false))
610 tlb_gather_mmu(&tlb
, mm
, 0);
611 if (new_end
> old_start
) {
613 * when the old and new regions overlap clear from new_end.
615 free_pgd_range(&tlb
, new_end
, old_end
, new_end
,
616 vma
->vm_next
? vma
->vm_next
->vm_start
: USER_PGTABLES_CEILING
);
619 * otherwise, clean from old_start; this is done to not touch
620 * the address space in [new_end, old_start) some architectures
621 * have constraints on va-space that make this illegal (IA64) -
622 * for the others its just a little faster.
624 free_pgd_range(&tlb
, old_start
, old_end
, new_end
,
625 vma
->vm_next
? vma
->vm_next
->vm_start
: USER_PGTABLES_CEILING
);
627 tlb_finish_mmu(&tlb
, new_end
, old_end
);
630 * Shrink the vma to just the new range. Always succeeds.
632 vma_adjust(vma
, new_start
, new_end
, vma
->vm_pgoff
, NULL
);
638 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
639 * the stack is optionally relocated, and some extra space is added.
641 int setup_arg_pages(struct linux_binprm
*bprm
,
642 unsigned long stack_top
,
643 int executable_stack
)
646 unsigned long stack_shift
;
647 struct mm_struct
*mm
= current
->mm
;
648 struct vm_area_struct
*vma
= bprm
->vma
;
649 struct vm_area_struct
*prev
= NULL
;
650 unsigned long vm_flags
;
651 unsigned long stack_base
;
652 unsigned long stack_size
;
653 unsigned long stack_expand
;
654 unsigned long rlim_stack
;
656 #ifdef CONFIG_STACK_GROWSUP
657 /* Limit stack size to 1GB */
658 stack_base
= rlimit_max(RLIMIT_STACK
);
659 if (stack_base
> (1 << 30))
660 stack_base
= 1 << 30;
662 /* Make sure we didn't let the argument array grow too large. */
663 if (vma
->vm_end
- vma
->vm_start
> stack_base
)
666 stack_base
= PAGE_ALIGN(stack_top
- stack_base
);
668 stack_shift
= vma
->vm_start
- stack_base
;
669 mm
->arg_start
= bprm
->p
- stack_shift
;
670 bprm
->p
= vma
->vm_end
- stack_shift
;
672 stack_top
= arch_align_stack(stack_top
);
673 stack_top
= PAGE_ALIGN(stack_top
);
675 if (unlikely(stack_top
< mmap_min_addr
) ||
676 unlikely(vma
->vm_end
- vma
->vm_start
>= stack_top
- mmap_min_addr
))
679 stack_shift
= vma
->vm_end
- stack_top
;
681 bprm
->p
-= stack_shift
;
682 mm
->arg_start
= bprm
->p
;
686 bprm
->loader
-= stack_shift
;
687 bprm
->exec
-= stack_shift
;
689 down_write(&mm
->mmap_sem
);
690 vm_flags
= VM_STACK_FLAGS
;
693 * Adjust stack execute permissions; explicitly enable for
694 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
695 * (arch default) otherwise.
697 if (unlikely(executable_stack
== EXSTACK_ENABLE_X
))
699 else if (executable_stack
== EXSTACK_DISABLE_X
)
700 vm_flags
&= ~VM_EXEC
;
701 vm_flags
|= mm
->def_flags
;
702 vm_flags
|= VM_STACK_INCOMPLETE_SETUP
;
704 ret
= mprotect_fixup(vma
, &prev
, vma
->vm_start
, vma
->vm_end
,
710 /* Move stack pages down in memory. */
712 ret
= shift_arg_pages(vma
, stack_shift
);
717 /* mprotect_fixup is overkill to remove the temporary stack flags */
718 vma
->vm_flags
&= ~VM_STACK_INCOMPLETE_SETUP
;
720 stack_expand
= 131072UL; /* randomly 32*4k (or 2*64k) pages */
721 stack_size
= vma
->vm_end
- vma
->vm_start
;
723 * Align this down to a page boundary as expand_stack
726 rlim_stack
= rlimit(RLIMIT_STACK
) & PAGE_MASK
;
727 #ifdef CONFIG_STACK_GROWSUP
728 if (stack_size
+ stack_expand
> rlim_stack
)
729 stack_base
= vma
->vm_start
+ rlim_stack
;
731 stack_base
= vma
->vm_end
+ stack_expand
;
733 if (stack_size
+ stack_expand
> rlim_stack
)
734 stack_base
= vma
->vm_end
- rlim_stack
;
736 stack_base
= vma
->vm_start
- stack_expand
;
738 current
->mm
->start_stack
= bprm
->p
;
739 ret
= expand_stack(vma
, stack_base
);
744 up_write(&mm
->mmap_sem
);
747 EXPORT_SYMBOL(setup_arg_pages
);
749 #endif /* CONFIG_MMU */
751 struct file
*open_exec(const char *name
)
755 struct filename tmp
= { .name
= name
};
756 static const struct open_flags open_exec_flags
= {
757 .open_flag
= O_LARGEFILE
| O_RDONLY
| __FMODE_EXEC
,
758 .acc_mode
= MAY_EXEC
| MAY_OPEN
,
759 .intent
= LOOKUP_OPEN
762 file
= do_filp_open(AT_FDCWD
, &tmp
, &open_exec_flags
, LOOKUP_FOLLOW
);
767 if (!S_ISREG(file_inode(file
)->i_mode
))
770 if (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
)
775 err
= deny_write_access(file
);
786 EXPORT_SYMBOL(open_exec
);
788 int kernel_read(struct file
*file
, loff_t offset
,
789 char *addr
, unsigned long count
)
797 /* The cast to a user pointer is valid due to the set_fs() */
798 result
= vfs_read(file
, (void __user
*)addr
, count
, &pos
);
803 EXPORT_SYMBOL(kernel_read
);
805 static int exec_mmap(struct mm_struct
*mm
)
807 struct task_struct
*tsk
;
808 struct mm_struct
* old_mm
, *active_mm
;
810 /* Notify parent that we're no longer interested in the old VM */
812 old_mm
= current
->mm
;
813 mm_release(tsk
, old_mm
);
818 * Make sure that if there is a core dump in progress
819 * for the old mm, we get out and die instead of going
820 * through with the exec. We must hold mmap_sem around
821 * checking core_state and changing tsk->mm.
823 down_read(&old_mm
->mmap_sem
);
824 if (unlikely(old_mm
->core_state
)) {
825 up_read(&old_mm
->mmap_sem
);
830 active_mm
= tsk
->active_mm
;
833 activate_mm(active_mm
, mm
);
835 arch_pick_mmap_layout(mm
);
837 up_read(&old_mm
->mmap_sem
);
838 BUG_ON(active_mm
!= old_mm
);
839 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, old_mm
);
840 mm_update_next_owner(old_mm
);
849 * This function makes sure the current process has its own signal table,
850 * so that flush_signal_handlers can later reset the handlers without
851 * disturbing other processes. (Other processes might share the signal
852 * table via the CLONE_SIGHAND option to clone().)
854 static int de_thread(struct task_struct
*tsk
)
856 struct signal_struct
*sig
= tsk
->signal
;
857 struct sighand_struct
*oldsighand
= tsk
->sighand
;
858 spinlock_t
*lock
= &oldsighand
->siglock
;
860 if (thread_group_empty(tsk
))
861 goto no_thread_group
;
864 * Kill all other threads in the thread group.
867 if (signal_group_exit(sig
)) {
869 * Another group action in progress, just
870 * return so that the signal is processed.
872 spin_unlock_irq(lock
);
876 sig
->group_exit_task
= tsk
;
877 sig
->notify_count
= zap_other_threads(tsk
);
878 if (!thread_group_leader(tsk
))
881 while (sig
->notify_count
) {
882 __set_current_state(TASK_KILLABLE
);
883 spin_unlock_irq(lock
);
885 if (unlikely(__fatal_signal_pending(tsk
)))
889 spin_unlock_irq(lock
);
892 * At this point all other threads have exited, all we have to
893 * do is to wait for the thread group leader to become inactive,
894 * and to assume its PID:
896 if (!thread_group_leader(tsk
)) {
897 struct task_struct
*leader
= tsk
->group_leader
;
899 sig
->notify_count
= -1; /* for exit_notify() */
901 write_lock_irq(&tasklist_lock
);
902 if (likely(leader
->exit_state
))
904 __set_current_state(TASK_KILLABLE
);
905 write_unlock_irq(&tasklist_lock
);
907 if (unlikely(__fatal_signal_pending(tsk
)))
912 * The only record we have of the real-time age of a
913 * process, regardless of execs it's done, is start_time.
914 * All the past CPU time is accumulated in signal_struct
915 * from sister threads now dead. But in this non-leader
916 * exec, nothing survives from the original leader thread,
917 * whose birth marks the true age of this process now.
918 * When we take on its identity by switching to its PID, we
919 * also take its birthdate (always earlier than our own).
921 tsk
->start_time
= leader
->start_time
;
923 BUG_ON(!same_thread_group(leader
, tsk
));
924 BUG_ON(has_group_leader_pid(tsk
));
926 * An exec() starts a new thread group with the
927 * TGID of the previous thread group. Rehash the
928 * two threads with a switched PID, and release
929 * the former thread group leader:
932 /* Become a process group leader with the old leader's pid.
933 * The old leader becomes a thread of the this thread group.
934 * Note: The old leader also uses this pid until release_task
935 * is called. Odd but simple and correct.
937 detach_pid(tsk
, PIDTYPE_PID
);
938 tsk
->pid
= leader
->pid
;
939 attach_pid(tsk
, PIDTYPE_PID
, task_pid(leader
));
940 transfer_pid(leader
, tsk
, PIDTYPE_PGID
);
941 transfer_pid(leader
, tsk
, PIDTYPE_SID
);
943 list_replace_rcu(&leader
->tasks
, &tsk
->tasks
);
944 list_replace_init(&leader
->sibling
, &tsk
->sibling
);
946 tsk
->group_leader
= tsk
;
947 leader
->group_leader
= tsk
;
949 tsk
->exit_signal
= SIGCHLD
;
950 leader
->exit_signal
= -1;
952 BUG_ON(leader
->exit_state
!= EXIT_ZOMBIE
);
953 leader
->exit_state
= EXIT_DEAD
;
956 * We are going to release_task()->ptrace_unlink() silently,
957 * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
958 * the tracer wont't block again waiting for this thread.
960 if (unlikely(leader
->ptrace
))
961 __wake_up_parent(leader
, leader
->parent
);
962 write_unlock_irq(&tasklist_lock
);
964 release_task(leader
);
967 sig
->group_exit_task
= NULL
;
968 sig
->notify_count
= 0;
971 /* we have changed execution domain */
972 tsk
->exit_signal
= SIGCHLD
;
975 flush_itimer_signals();
977 if (atomic_read(&oldsighand
->count
) != 1) {
978 struct sighand_struct
*newsighand
;
980 * This ->sighand is shared with the CLONE_SIGHAND
981 * but not CLONE_THREAD task, switch to the new one.
983 newsighand
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
987 atomic_set(&newsighand
->count
, 1);
988 memcpy(newsighand
->action
, oldsighand
->action
,
989 sizeof(newsighand
->action
));
991 write_lock_irq(&tasklist_lock
);
992 spin_lock(&oldsighand
->siglock
);
993 rcu_assign_pointer(tsk
->sighand
, newsighand
);
994 spin_unlock(&oldsighand
->siglock
);
995 write_unlock_irq(&tasklist_lock
);
997 __cleanup_sighand(oldsighand
);
1000 BUG_ON(!thread_group_leader(tsk
));
1004 /* protects against exit_notify() and __exit_signal() */
1005 read_lock(&tasklist_lock
);
1006 sig
->group_exit_task
= NULL
;
1007 sig
->notify_count
= 0;
1008 read_unlock(&tasklist_lock
);
1012 char *get_task_comm(char *buf
, struct task_struct
*tsk
)
1014 /* buf must be at least sizeof(tsk->comm) in size */
1016 strncpy(buf
, tsk
->comm
, sizeof(tsk
->comm
));
1020 EXPORT_SYMBOL_GPL(get_task_comm
);
1023 * These functions flushes out all traces of the currently running executable
1024 * so that a new one can be started
1027 void set_task_comm(struct task_struct
*tsk
, char *buf
)
1030 trace_task_rename(tsk
, buf
);
1031 strlcpy(tsk
->comm
, buf
, sizeof(tsk
->comm
));
1033 perf_event_comm(tsk
);
1036 static void filename_to_taskname(char *tcomm
, const char *fn
, unsigned int len
)
1040 /* Copies the binary name from after last slash */
1041 for (i
= 0; (ch
= *(fn
++)) != '\0';) {
1043 i
= 0; /* overwrite what we wrote */
1051 int flush_old_exec(struct linux_binprm
* bprm
)
1056 * Make sure we have a private signal table and that
1057 * we are unassociated from the previous thread group.
1059 retval
= de_thread(current
);
1063 set_mm_exe_file(bprm
->mm
, bprm
->file
);
1065 filename_to_taskname(bprm
->tcomm
, bprm
->filename
, sizeof(bprm
->tcomm
));
1067 * Release all of the old mmap stuff
1069 acct_arg_size(bprm
, 0);
1070 retval
= exec_mmap(bprm
->mm
);
1074 bprm
->mm
= NULL
; /* We're using it now */
1078 ~(PF_RANDOMIZE
| PF_FORKNOEXEC
| PF_KTHREAD
| PF_NOFREEZE
);
1080 current
->personality
&= ~bprm
->per_clear
;
1087 EXPORT_SYMBOL(flush_old_exec
);
1089 void would_dump(struct linux_binprm
*bprm
, struct file
*file
)
1091 if (inode_permission(file_inode(file
), MAY_READ
) < 0)
1092 bprm
->interp_flags
|= BINPRM_FLAGS_ENFORCE_NONDUMP
;
1094 EXPORT_SYMBOL(would_dump
);
1096 void setup_new_exec(struct linux_binprm
* bprm
)
1098 arch_pick_mmap_layout(current
->mm
);
1100 /* This is the point of no return */
1101 current
->sas_ss_sp
= current
->sas_ss_size
= 0;
1103 if (uid_eq(current_euid(), current_uid()) && gid_eq(current_egid(), current_gid()))
1104 set_dumpable(current
->mm
, SUID_DUMP_USER
);
1106 set_dumpable(current
->mm
, suid_dumpable
);
1108 set_task_comm(current
, bprm
->tcomm
);
1110 /* Set the new mm task size. We have to do that late because it may
1111 * depend on TIF_32BIT which is only updated in flush_thread() on
1112 * some architectures like powerpc
1114 current
->mm
->task_size
= TASK_SIZE
;
1116 /* install the new credentials */
1117 if (!uid_eq(bprm
->cred
->uid
, current_euid()) ||
1118 !gid_eq(bprm
->cred
->gid
, current_egid())) {
1119 current
->pdeath_signal
= 0;
1121 would_dump(bprm
, bprm
->file
);
1122 if (bprm
->interp_flags
& BINPRM_FLAGS_ENFORCE_NONDUMP
)
1123 set_dumpable(current
->mm
, suid_dumpable
);
1127 * Flush performance counters when crossing a
1130 if (!get_dumpable(current
->mm
))
1131 perf_event_exit_task(current
);
1133 /* An exec changes our domain. We are no longer part of the thread
1136 current
->self_exec_id
++;
1138 flush_signal_handlers(current
, 0);
1139 do_close_on_exec(current
->files
);
1141 EXPORT_SYMBOL(setup_new_exec
);
1144 * Prepare credentials and lock ->cred_guard_mutex.
1145 * install_exec_creds() commits the new creds and drops the lock.
1146 * Or, if exec fails before, free_bprm() should release ->cred and
1149 int prepare_bprm_creds(struct linux_binprm
*bprm
)
1151 if (mutex_lock_interruptible(¤t
->signal
->cred_guard_mutex
))
1152 return -ERESTARTNOINTR
;
1154 bprm
->cred
= prepare_exec_creds();
1155 if (likely(bprm
->cred
))
1158 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1162 void free_bprm(struct linux_binprm
*bprm
)
1164 free_arg_pages(bprm
);
1166 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1167 abort_creds(bprm
->cred
);
1169 /* If a binfmt changed the interp, free it. */
1170 if (bprm
->interp
!= bprm
->filename
)
1171 kfree(bprm
->interp
);
1175 int bprm_change_interp(char *interp
, struct linux_binprm
*bprm
)
1177 /* If a binfmt changed the interp, free it first. */
1178 if (bprm
->interp
!= bprm
->filename
)
1179 kfree(bprm
->interp
);
1180 bprm
->interp
= kstrdup(interp
, GFP_KERNEL
);
1185 EXPORT_SYMBOL(bprm_change_interp
);
1188 * install the new credentials for this executable
1190 void install_exec_creds(struct linux_binprm
*bprm
)
1192 security_bprm_committing_creds(bprm
);
1194 commit_creds(bprm
->cred
);
1197 * cred_guard_mutex must be held at least to this point to prevent
1198 * ptrace_attach() from altering our determination of the task's
1199 * credentials; any time after this it may be unlocked.
1201 security_bprm_committed_creds(bprm
);
1202 mutex_unlock(¤t
->signal
->cred_guard_mutex
);
1204 EXPORT_SYMBOL(install_exec_creds
);
1207 * determine how safe it is to execute the proposed program
1208 * - the caller must hold ->cred_guard_mutex to protect against
1211 static int check_unsafe_exec(struct linux_binprm
*bprm
)
1213 struct task_struct
*p
= current
, *t
;
1218 if (p
->ptrace
& PT_PTRACE_CAP
)
1219 bprm
->unsafe
|= LSM_UNSAFE_PTRACE_CAP
;
1221 bprm
->unsafe
|= LSM_UNSAFE_PTRACE
;
1225 * This isn't strictly necessary, but it makes it harder for LSMs to
1228 if (current
->no_new_privs
)
1229 bprm
->unsafe
|= LSM_UNSAFE_NO_NEW_PRIVS
;
1232 spin_lock(&p
->fs
->lock
);
1234 for (t
= next_thread(p
); t
!= p
; t
= next_thread(t
)) {
1240 if (p
->fs
->users
> n_fs
) {
1241 bprm
->unsafe
|= LSM_UNSAFE_SHARE
;
1244 if (!p
->fs
->in_exec
) {
1249 spin_unlock(&p
->fs
->lock
);
1255 * Fill the binprm structure from the inode.
1256 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1258 * This may be called multiple times for binary chains (scripts for example).
1260 int prepare_binprm(struct linux_binprm
*bprm
)
1263 struct inode
* inode
= file_inode(bprm
->file
);
1266 mode
= inode
->i_mode
;
1267 if (bprm
->file
->f_op
== NULL
)
1270 /* clear any previous set[ug]id data from a previous binary */
1271 bprm
->cred
->euid
= current_euid();
1272 bprm
->cred
->egid
= current_egid();
1274 if (!(bprm
->file
->f_path
.mnt
->mnt_flags
& MNT_NOSUID
) &&
1275 !current
->no_new_privs
&&
1276 kuid_has_mapping(bprm
->cred
->user_ns
, inode
->i_uid
) &&
1277 kgid_has_mapping(bprm
->cred
->user_ns
, inode
->i_gid
)) {
1279 if (mode
& S_ISUID
) {
1280 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1281 bprm
->cred
->euid
= inode
->i_uid
;
1286 * If setgid is set but no group execute bit then this
1287 * is a candidate for mandatory locking, not a setgid
1290 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
1291 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1292 bprm
->cred
->egid
= inode
->i_gid
;
1296 /* fill in binprm security blob */
1297 retval
= security_bprm_set_creds(bprm
);
1300 bprm
->cred_prepared
= 1;
1302 memset(bprm
->buf
, 0, BINPRM_BUF_SIZE
);
1303 return kernel_read(bprm
->file
, 0, bprm
->buf
, BINPRM_BUF_SIZE
);
1306 EXPORT_SYMBOL(prepare_binprm
);
1309 * Arguments are '\0' separated strings found at the location bprm->p
1310 * points to; chop off the first by relocating brpm->p to right after
1311 * the first '\0' encountered.
1313 int remove_arg_zero(struct linux_binprm
*bprm
)
1316 unsigned long offset
;
1324 offset
= bprm
->p
& ~PAGE_MASK
;
1325 page
= get_arg_page(bprm
, bprm
->p
, 0);
1330 kaddr
= kmap_atomic(page
);
1332 for (; offset
< PAGE_SIZE
&& kaddr
[offset
];
1333 offset
++, bprm
->p
++)
1336 kunmap_atomic(kaddr
);
1339 if (offset
== PAGE_SIZE
)
1340 free_arg_page(bprm
, (bprm
->p
>> PAGE_SHIFT
) - 1);
1341 } while (offset
== PAGE_SIZE
);
1350 EXPORT_SYMBOL(remove_arg_zero
);
1353 * cycle the list of binary formats handler, until one recognizes the image
1355 int search_binary_handler(struct linux_binprm
*bprm
)
1357 unsigned int depth
= bprm
->recursion_depth
;
1359 struct linux_binfmt
*fmt
;
1360 pid_t old_pid
, old_vpid
;
1362 /* This allows 4 levels of binfmt rewrites before failing hard. */
1366 retval
= security_bprm_check(bprm
);
1370 retval
= audit_bprm(bprm
);
1374 /* Need to fetch pid before load_binary changes it */
1375 old_pid
= current
->pid
;
1377 old_vpid
= task_pid_nr_ns(current
, task_active_pid_ns(current
->parent
));
1381 for (try=0; try<2; try++) {
1382 read_lock(&binfmt_lock
);
1383 list_for_each_entry(fmt
, &formats
, lh
) {
1384 int (*fn
)(struct linux_binprm
*) = fmt
->load_binary
;
1387 if (!try_module_get(fmt
->module
))
1389 read_unlock(&binfmt_lock
);
1390 bprm
->recursion_depth
= depth
+ 1;
1392 bprm
->recursion_depth
= depth
;
1395 trace_sched_process_exec(current
, old_pid
, bprm
);
1396 ptrace_event(PTRACE_EVENT_EXEC
, old_vpid
);
1399 allow_write_access(bprm
->file
);
1403 current
->did_exec
= 1;
1404 proc_exec_connector(current
);
1407 read_lock(&binfmt_lock
);
1409 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
)
1412 read_unlock(&binfmt_lock
);
1416 read_unlock(&binfmt_lock
);
1417 #ifdef CONFIG_MODULES
1418 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
) {
1421 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1422 if (printable(bprm
->buf
[0]) &&
1423 printable(bprm
->buf
[1]) &&
1424 printable(bprm
->buf
[2]) &&
1425 printable(bprm
->buf
[3]))
1426 break; /* -ENOEXEC */
1428 break; /* -ENOEXEC */
1429 request_module("binfmt-%04x", *(unsigned short *)(&bprm
->buf
[2]));
1438 EXPORT_SYMBOL(search_binary_handler
);
1441 * sys_execve() executes a new program.
1443 static int do_execve_common(const char *filename
,
1444 struct user_arg_ptr argv
,
1445 struct user_arg_ptr envp
)
1447 struct linux_binprm
*bprm
;
1449 struct files_struct
*displaced
;
1452 const struct cred
*cred
= current_cred();
1455 * We move the actual failure in case of RLIMIT_NPROC excess from
1456 * set*uid() to execve() because too many poorly written programs
1457 * don't check setuid() return code. Here we additionally recheck
1458 * whether NPROC limit is still exceeded.
1460 if ((current
->flags
& PF_NPROC_EXCEEDED
) &&
1461 atomic_read(&cred
->user
->processes
) > rlimit(RLIMIT_NPROC
)) {
1466 /* We're below the limit (still or again), so we don't want to make
1467 * further execve() calls fail. */
1468 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1470 retval
= unshare_files(&displaced
);
1475 bprm
= kzalloc(sizeof(*bprm
), GFP_KERNEL
);
1479 retval
= prepare_bprm_creds(bprm
);
1483 retval
= check_unsafe_exec(bprm
);
1486 clear_in_exec
= retval
;
1487 current
->in_execve
= 1;
1489 file
= open_exec(filename
);
1490 retval
= PTR_ERR(file
);
1497 bprm
->filename
= filename
;
1498 bprm
->interp
= filename
;
1500 retval
= bprm_mm_init(bprm
);
1504 bprm
->argc
= count(argv
, MAX_ARG_STRINGS
);
1505 if ((retval
= bprm
->argc
) < 0)
1508 bprm
->envc
= count(envp
, MAX_ARG_STRINGS
);
1509 if ((retval
= bprm
->envc
) < 0)
1512 retval
= prepare_binprm(bprm
);
1516 retval
= copy_strings_kernel(1, &bprm
->filename
, bprm
);
1520 bprm
->exec
= bprm
->p
;
1521 retval
= copy_strings(bprm
->envc
, envp
, bprm
);
1525 retval
= copy_strings(bprm
->argc
, argv
, bprm
);
1529 retval
= search_binary_handler(bprm
);
1533 /* execve succeeded */
1534 current
->fs
->in_exec
= 0;
1535 current
->in_execve
= 0;
1536 acct_update_integrals(current
);
1539 put_files_struct(displaced
);
1544 acct_arg_size(bprm
, 0);
1550 allow_write_access(bprm
->file
);
1556 current
->fs
->in_exec
= 0;
1557 current
->in_execve
= 0;
1564 reset_files_struct(displaced
);
1569 int do_execve(const char *filename
,
1570 const char __user
*const __user
*__argv
,
1571 const char __user
*const __user
*__envp
)
1573 struct user_arg_ptr argv
= { .ptr
.native
= __argv
};
1574 struct user_arg_ptr envp
= { .ptr
.native
= __envp
};
1575 return do_execve_common(filename
, argv
, envp
);
1578 #ifdef CONFIG_COMPAT
1579 static int compat_do_execve(const char *filename
,
1580 const compat_uptr_t __user
*__argv
,
1581 const compat_uptr_t __user
*__envp
)
1583 struct user_arg_ptr argv
= {
1585 .ptr
.compat
= __argv
,
1587 struct user_arg_ptr envp
= {
1589 .ptr
.compat
= __envp
,
1591 return do_execve_common(filename
, argv
, envp
);
1595 void set_binfmt(struct linux_binfmt
*new)
1597 struct mm_struct
*mm
= current
->mm
;
1600 module_put(mm
->binfmt
->module
);
1604 __module_get(new->module
);
1607 EXPORT_SYMBOL(set_binfmt
);
1610 * set_dumpable converts traditional three-value dumpable to two flags and
1611 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1612 * these bits are not changed atomically. So get_dumpable can observe the
1613 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1614 * return either old dumpable or new one by paying attention to the order of
1615 * modifying the bits.
1617 * dumpable | mm->flags (binary)
1618 * old new | initial interim final
1619 * ---------+-----------------------
1627 * (*) get_dumpable regards interim value of 10 as 11.
1629 void set_dumpable(struct mm_struct
*mm
, int value
)
1632 case SUID_DUMP_DISABLE
:
1633 clear_bit(MMF_DUMPABLE
, &mm
->flags
);
1635 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1637 case SUID_DUMP_USER
:
1638 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1640 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1642 case SUID_DUMP_ROOT
:
1643 set_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1645 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1650 int __get_dumpable(unsigned long mm_flags
)
1654 ret
= mm_flags
& MMF_DUMPABLE_MASK
;
1655 return (ret
> SUID_DUMP_USER
) ? SUID_DUMP_ROOT
: ret
;
1658 int get_dumpable(struct mm_struct
*mm
)
1660 return __get_dumpable(mm
->flags
);
1663 SYSCALL_DEFINE3(execve
,
1664 const char __user
*, filename
,
1665 const char __user
*const __user
*, argv
,
1666 const char __user
*const __user
*, envp
)
1668 struct filename
*path
= getname(filename
);
1669 int error
= PTR_ERR(path
);
1670 if (!IS_ERR(path
)) {
1671 error
= do_execve(path
->name
, argv
, envp
);
1676 #ifdef CONFIG_COMPAT
1677 asmlinkage
long compat_sys_execve(const char __user
* filename
,
1678 const compat_uptr_t __user
* argv
,
1679 const compat_uptr_t __user
* envp
)
1681 struct filename
*path
= getname(filename
);
1682 int error
= PTR_ERR(path
);
1683 if (!IS_ERR(path
)) {
1684 error
= compat_do_execve(path
->name
, argv
, envp
);