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/smp_lock.h>
32 #include <linux/swap.h>
33 #include <linux/string.h>
34 #include <linux/init.h>
35 #include <linux/pagemap.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/proc_fs.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>
55 #include <asm/uaccess.h>
56 #include <asm/mmu_context.h>
61 /* for /sbin/loader handling in search_binary_handler() */
62 #include <linux/a.out.h>
66 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
67 int suid_dumpable
= 0;
69 /* The maximal length of core_pattern is also specified in sysctl.c */
71 static LIST_HEAD(formats
);
72 static DEFINE_RWLOCK(binfmt_lock
);
74 int register_binfmt(struct linux_binfmt
* fmt
)
78 write_lock(&binfmt_lock
);
79 list_add(&fmt
->lh
, &formats
);
80 write_unlock(&binfmt_lock
);
84 EXPORT_SYMBOL(register_binfmt
);
86 void unregister_binfmt(struct linux_binfmt
* fmt
)
88 write_lock(&binfmt_lock
);
90 write_unlock(&binfmt_lock
);
93 EXPORT_SYMBOL(unregister_binfmt
);
95 static inline void put_binfmt(struct linux_binfmt
* fmt
)
97 module_put(fmt
->module
);
101 * Note that a shared library must be both readable and executable due to
104 * Also note that we take the address to load from from the file itself.
106 asmlinkage
long sys_uselib(const char __user
* library
)
110 char *tmp
= getname(library
);
111 int error
= PTR_ERR(tmp
);
114 error
= path_lookup_open(AT_FDCWD
, tmp
,
116 FMODE_READ
|FMODE_EXEC
);
123 if (!S_ISREG(nd
.path
.dentry
->d_inode
->i_mode
))
127 if (nd
.path
.mnt
->mnt_flags
& MNT_NOEXEC
)
130 error
= vfs_permission(&nd
, MAY_READ
| MAY_EXEC
| MAY_OPEN
);
134 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
135 error
= PTR_ERR(file
);
141 struct linux_binfmt
* fmt
;
143 read_lock(&binfmt_lock
);
144 list_for_each_entry(fmt
, &formats
, lh
) {
145 if (!fmt
->load_shlib
)
147 if (!try_module_get(fmt
->module
))
149 read_unlock(&binfmt_lock
);
150 error
= fmt
->load_shlib(file
);
151 read_lock(&binfmt_lock
);
153 if (error
!= -ENOEXEC
)
156 read_unlock(&binfmt_lock
);
162 release_open_intent(&nd
);
169 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
175 #ifdef CONFIG_STACK_GROWSUP
177 ret
= expand_stack_downwards(bprm
->vma
, pos
);
182 ret
= get_user_pages(current
, bprm
->mm
, pos
,
183 1, write
, 1, &page
, NULL
);
188 unsigned long size
= bprm
->vma
->vm_end
- bprm
->vma
->vm_start
;
192 * We've historically supported up to 32 pages (ARG_MAX)
193 * of argument strings even with small stacks
199 * Limit to 1/4-th the stack size for the argv+env strings.
201 * - the remaining binfmt code will not run out of stack space,
202 * - the program will have a reasonable amount of stack left
205 rlim
= current
->signal
->rlim
;
206 if (size
> rlim
[RLIMIT_STACK
].rlim_cur
/ 4) {
215 static void put_arg_page(struct page
*page
)
220 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
224 static void free_arg_pages(struct linux_binprm
*bprm
)
228 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
231 flush_cache_page(bprm
->vma
, pos
, page_to_pfn(page
));
234 static int __bprm_mm_init(struct linux_binprm
*bprm
)
237 struct vm_area_struct
*vma
= NULL
;
238 struct mm_struct
*mm
= bprm
->mm
;
240 bprm
->vma
= vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
244 down_write(&mm
->mmap_sem
);
248 * Place the stack at the largest stack address the architecture
249 * supports. Later, we'll move this to an appropriate place. We don't
250 * use STACK_TOP because that can depend on attributes which aren't
253 vma
->vm_end
= STACK_TOP_MAX
;
254 vma
->vm_start
= vma
->vm_end
- PAGE_SIZE
;
256 vma
->vm_flags
= VM_STACK_FLAGS
;
257 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
258 err
= insert_vm_struct(mm
, vma
);
260 up_write(&mm
->mmap_sem
);
264 mm
->stack_vm
= mm
->total_vm
= 1;
265 up_write(&mm
->mmap_sem
);
267 bprm
->p
= vma
->vm_end
- sizeof(void *);
274 kmem_cache_free(vm_area_cachep
, vma
);
280 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
282 return len
<= MAX_ARG_STRLEN
;
287 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
292 page
= bprm
->page
[pos
/ PAGE_SIZE
];
293 if (!page
&& write
) {
294 page
= alloc_page(GFP_HIGHUSER
|__GFP_ZERO
);
297 bprm
->page
[pos
/ PAGE_SIZE
] = page
;
303 static void put_arg_page(struct page
*page
)
307 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
310 __free_page(bprm
->page
[i
]);
311 bprm
->page
[i
] = NULL
;
315 static void free_arg_pages(struct linux_binprm
*bprm
)
319 for (i
= 0; i
< MAX_ARG_PAGES
; i
++)
320 free_arg_page(bprm
, i
);
323 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
328 static int __bprm_mm_init(struct linux_binprm
*bprm
)
330 bprm
->p
= PAGE_SIZE
* MAX_ARG_PAGES
- sizeof(void *);
334 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
336 return len
<= bprm
->p
;
339 #endif /* CONFIG_MMU */
342 * Create a new mm_struct and populate it with a temporary stack
343 * vm_area_struct. We don't have enough context at this point to set the stack
344 * flags, permissions, and offset, so we use temporary values. We'll update
345 * them later in setup_arg_pages().
347 int bprm_mm_init(struct linux_binprm
*bprm
)
350 struct mm_struct
*mm
= NULL
;
352 bprm
->mm
= mm
= mm_alloc();
357 err
= init_new_context(current
, mm
);
361 err
= __bprm_mm_init(bprm
);
377 * count() counts the number of strings in array ARGV.
379 static int count(char __user
* __user
* argv
, int max
)
387 if (get_user(p
, argv
))
401 * 'copy_strings()' copies argument/environment strings from the old
402 * processes's memory to the new process's stack. The call to get_user_pages()
403 * ensures the destination page is created and not swapped out.
405 static int copy_strings(int argc
, char __user
* __user
* argv
,
406 struct linux_binprm
*bprm
)
408 struct page
*kmapped_page
= NULL
;
410 unsigned long kpos
= 0;
418 if (get_user(str
, argv
+argc
) ||
419 !(len
= strnlen_user(str
, MAX_ARG_STRLEN
))) {
424 if (!valid_arg_len(bprm
, len
)) {
429 /* We're going to work our way backwords. */
435 int offset
, bytes_to_copy
;
437 offset
= pos
% PAGE_SIZE
;
441 bytes_to_copy
= offset
;
442 if (bytes_to_copy
> len
)
445 offset
-= bytes_to_copy
;
446 pos
-= bytes_to_copy
;
447 str
-= bytes_to_copy
;
448 len
-= bytes_to_copy
;
450 if (!kmapped_page
|| kpos
!= (pos
& PAGE_MASK
)) {
453 page
= get_arg_page(bprm
, pos
, 1);
460 flush_kernel_dcache_page(kmapped_page
);
461 kunmap(kmapped_page
);
462 put_arg_page(kmapped_page
);
465 kaddr
= kmap(kmapped_page
);
466 kpos
= pos
& PAGE_MASK
;
467 flush_arg_page(bprm
, kpos
, kmapped_page
);
469 if (copy_from_user(kaddr
+offset
, str
, bytes_to_copy
)) {
478 flush_kernel_dcache_page(kmapped_page
);
479 kunmap(kmapped_page
);
480 put_arg_page(kmapped_page
);
486 * Like copy_strings, but get argv and its values from kernel memory.
488 int copy_strings_kernel(int argc
,char ** argv
, struct linux_binprm
*bprm
)
491 mm_segment_t oldfs
= get_fs();
493 r
= copy_strings(argc
, (char __user
* __user
*)argv
, bprm
);
497 EXPORT_SYMBOL(copy_strings_kernel
);
502 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
503 * the binfmt code determines where the new stack should reside, we shift it to
504 * its final location. The process proceeds as follows:
506 * 1) Use shift to calculate the new vma endpoints.
507 * 2) Extend vma to cover both the old and new ranges. This ensures the
508 * arguments passed to subsequent functions are consistent.
509 * 3) Move vma's page tables to the new range.
510 * 4) Free up any cleared pgd range.
511 * 5) Shrink the vma to cover only the new range.
513 static int shift_arg_pages(struct vm_area_struct
*vma
, unsigned long shift
)
515 struct mm_struct
*mm
= vma
->vm_mm
;
516 unsigned long old_start
= vma
->vm_start
;
517 unsigned long old_end
= vma
->vm_end
;
518 unsigned long length
= old_end
- old_start
;
519 unsigned long new_start
= old_start
- shift
;
520 unsigned long new_end
= old_end
- shift
;
521 struct mmu_gather
*tlb
;
523 BUG_ON(new_start
> new_end
);
526 * ensure there are no vmas between where we want to go
529 if (vma
!= find_vma(mm
, new_start
))
533 * cover the whole range: [new_start, old_end)
535 vma_adjust(vma
, new_start
, old_end
, vma
->vm_pgoff
, NULL
);
538 * move the page tables downwards, on failure we rely on
539 * process cleanup to remove whatever mess we made.
541 if (length
!= move_page_tables(vma
, old_start
,
542 vma
, new_start
, length
))
546 tlb
= tlb_gather_mmu(mm
, 0);
547 if (new_end
> old_start
) {
549 * when the old and new regions overlap clear from new_end.
551 free_pgd_range(tlb
, new_end
, old_end
, new_end
,
552 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
555 * otherwise, clean from old_start; this is done to not touch
556 * the address space in [new_end, old_start) some architectures
557 * have constraints on va-space that make this illegal (IA64) -
558 * for the others its just a little faster.
560 free_pgd_range(tlb
, old_start
, old_end
, new_end
,
561 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
563 tlb_finish_mmu(tlb
, new_end
, old_end
);
566 * shrink the vma to just the new range.
568 vma_adjust(vma
, new_start
, new_end
, vma
->vm_pgoff
, NULL
);
573 #define EXTRA_STACK_VM_PAGES 20 /* random */
576 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
577 * the stack is optionally relocated, and some extra space is added.
579 int setup_arg_pages(struct linux_binprm
*bprm
,
580 unsigned long stack_top
,
581 int executable_stack
)
584 unsigned long stack_shift
;
585 struct mm_struct
*mm
= current
->mm
;
586 struct vm_area_struct
*vma
= bprm
->vma
;
587 struct vm_area_struct
*prev
= NULL
;
588 unsigned long vm_flags
;
589 unsigned long stack_base
;
591 #ifdef CONFIG_STACK_GROWSUP
592 /* Limit stack size to 1GB */
593 stack_base
= current
->signal
->rlim
[RLIMIT_STACK
].rlim_max
;
594 if (stack_base
> (1 << 30))
595 stack_base
= 1 << 30;
597 /* Make sure we didn't let the argument array grow too large. */
598 if (vma
->vm_end
- vma
->vm_start
> stack_base
)
601 stack_base
= PAGE_ALIGN(stack_top
- stack_base
);
603 stack_shift
= vma
->vm_start
- stack_base
;
604 mm
->arg_start
= bprm
->p
- stack_shift
;
605 bprm
->p
= vma
->vm_end
- stack_shift
;
607 stack_top
= arch_align_stack(stack_top
);
608 stack_top
= PAGE_ALIGN(stack_top
);
609 stack_shift
= vma
->vm_end
- stack_top
;
611 bprm
->p
-= stack_shift
;
612 mm
->arg_start
= bprm
->p
;
616 bprm
->loader
-= stack_shift
;
617 bprm
->exec
-= stack_shift
;
619 down_write(&mm
->mmap_sem
);
620 vm_flags
= VM_STACK_FLAGS
;
623 * Adjust stack execute permissions; explicitly enable for
624 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
625 * (arch default) otherwise.
627 if (unlikely(executable_stack
== EXSTACK_ENABLE_X
))
629 else if (executable_stack
== EXSTACK_DISABLE_X
)
630 vm_flags
&= ~VM_EXEC
;
631 vm_flags
|= mm
->def_flags
;
633 ret
= mprotect_fixup(vma
, &prev
, vma
->vm_start
, vma
->vm_end
,
639 /* Move stack pages down in memory. */
641 ret
= shift_arg_pages(vma
, stack_shift
);
643 up_write(&mm
->mmap_sem
);
648 #ifdef CONFIG_STACK_GROWSUP
649 stack_base
= vma
->vm_end
+ EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
651 stack_base
= vma
->vm_start
- EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
653 ret
= expand_stack(vma
, stack_base
);
658 up_write(&mm
->mmap_sem
);
661 EXPORT_SYMBOL(setup_arg_pages
);
663 #endif /* CONFIG_MMU */
665 struct file
*open_exec(const char *name
)
671 err
= path_lookup_open(AT_FDCWD
, name
, LOOKUP_FOLLOW
, &nd
,
672 FMODE_READ
|FMODE_EXEC
);
677 if (!S_ISREG(nd
.path
.dentry
->d_inode
->i_mode
))
680 if (nd
.path
.mnt
->mnt_flags
& MNT_NOEXEC
)
683 err
= vfs_permission(&nd
, MAY_EXEC
| MAY_OPEN
);
687 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
691 err
= deny_write_access(file
);
700 release_open_intent(&nd
);
705 EXPORT_SYMBOL(open_exec
);
707 int kernel_read(struct file
*file
, unsigned long offset
,
708 char *addr
, unsigned long count
)
716 /* The cast to a user pointer is valid due to the set_fs() */
717 result
= vfs_read(file
, (void __user
*)addr
, count
, &pos
);
722 EXPORT_SYMBOL(kernel_read
);
724 static int exec_mmap(struct mm_struct
*mm
)
726 struct task_struct
*tsk
;
727 struct mm_struct
* old_mm
, *active_mm
;
729 /* Notify parent that we're no longer interested in the old VM */
731 old_mm
= current
->mm
;
732 mm_release(tsk
, old_mm
);
736 * Make sure that if there is a core dump in progress
737 * for the old mm, we get out and die instead of going
738 * through with the exec. We must hold mmap_sem around
739 * checking core_state and changing tsk->mm.
741 down_read(&old_mm
->mmap_sem
);
742 if (unlikely(old_mm
->core_state
)) {
743 up_read(&old_mm
->mmap_sem
);
748 active_mm
= tsk
->active_mm
;
751 activate_mm(active_mm
, mm
);
753 arch_pick_mmap_layout(mm
);
755 up_read(&old_mm
->mmap_sem
);
756 BUG_ON(active_mm
!= old_mm
);
757 mm_update_next_owner(old_mm
);
766 * This function makes sure the current process has its own signal table,
767 * so that flush_signal_handlers can later reset the handlers without
768 * disturbing other processes. (Other processes might share the signal
769 * table via the CLONE_SIGHAND option to clone().)
771 static int de_thread(struct task_struct
*tsk
)
773 struct signal_struct
*sig
= tsk
->signal
;
774 struct sighand_struct
*oldsighand
= tsk
->sighand
;
775 spinlock_t
*lock
= &oldsighand
->siglock
;
778 if (thread_group_empty(tsk
))
779 goto no_thread_group
;
782 * Kill all other threads in the thread group.
785 if (signal_group_exit(sig
)) {
787 * Another group action in progress, just
788 * return so that the signal is processed.
790 spin_unlock_irq(lock
);
793 sig
->group_exit_task
= tsk
;
794 zap_other_threads(tsk
);
796 /* Account for the thread group leader hanging around: */
797 count
= thread_group_leader(tsk
) ? 1 : 2;
798 sig
->notify_count
= count
;
799 while (atomic_read(&sig
->count
) > count
) {
800 __set_current_state(TASK_UNINTERRUPTIBLE
);
801 spin_unlock_irq(lock
);
805 spin_unlock_irq(lock
);
808 * At this point all other threads have exited, all we have to
809 * do is to wait for the thread group leader to become inactive,
810 * and to assume its PID:
812 if (!thread_group_leader(tsk
)) {
813 struct task_struct
*leader
= tsk
->group_leader
;
815 sig
->notify_count
= -1; /* for exit_notify() */
817 write_lock_irq(&tasklist_lock
);
818 if (likely(leader
->exit_state
))
820 __set_current_state(TASK_UNINTERRUPTIBLE
);
821 write_unlock_irq(&tasklist_lock
);
826 * The only record we have of the real-time age of a
827 * process, regardless of execs it's done, is start_time.
828 * All the past CPU time is accumulated in signal_struct
829 * from sister threads now dead. But in this non-leader
830 * exec, nothing survives from the original leader thread,
831 * whose birth marks the true age of this process now.
832 * When we take on its identity by switching to its PID, we
833 * also take its birthdate (always earlier than our own).
835 tsk
->start_time
= leader
->start_time
;
837 BUG_ON(!same_thread_group(leader
, tsk
));
838 BUG_ON(has_group_leader_pid(tsk
));
840 * An exec() starts a new thread group with the
841 * TGID of the previous thread group. Rehash the
842 * two threads with a switched PID, and release
843 * the former thread group leader:
846 /* Become a process group leader with the old leader's pid.
847 * The old leader becomes a thread of the this thread group.
848 * Note: The old leader also uses this pid until release_task
849 * is called. Odd but simple and correct.
851 detach_pid(tsk
, PIDTYPE_PID
);
852 tsk
->pid
= leader
->pid
;
853 attach_pid(tsk
, PIDTYPE_PID
, task_pid(leader
));
854 transfer_pid(leader
, tsk
, PIDTYPE_PGID
);
855 transfer_pid(leader
, tsk
, PIDTYPE_SID
);
856 list_replace_rcu(&leader
->tasks
, &tsk
->tasks
);
858 tsk
->group_leader
= tsk
;
859 leader
->group_leader
= tsk
;
861 tsk
->exit_signal
= SIGCHLD
;
863 BUG_ON(leader
->exit_state
!= EXIT_ZOMBIE
);
864 leader
->exit_state
= EXIT_DEAD
;
865 write_unlock_irq(&tasklist_lock
);
867 release_task(leader
);
870 sig
->group_exit_task
= NULL
;
871 sig
->notify_count
= 0;
875 flush_itimer_signals();
877 if (atomic_read(&oldsighand
->count
) != 1) {
878 struct sighand_struct
*newsighand
;
880 * This ->sighand is shared with the CLONE_SIGHAND
881 * but not CLONE_THREAD task, switch to the new one.
883 newsighand
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
887 atomic_set(&newsighand
->count
, 1);
888 memcpy(newsighand
->action
, oldsighand
->action
,
889 sizeof(newsighand
->action
));
891 write_lock_irq(&tasklist_lock
);
892 spin_lock(&oldsighand
->siglock
);
893 rcu_assign_pointer(tsk
->sighand
, newsighand
);
894 spin_unlock(&oldsighand
->siglock
);
895 write_unlock_irq(&tasklist_lock
);
897 __cleanup_sighand(oldsighand
);
900 BUG_ON(!thread_group_leader(tsk
));
905 * These functions flushes out all traces of the currently running executable
906 * so that a new one can be started
908 static void flush_old_files(struct files_struct
* files
)
913 spin_lock(&files
->file_lock
);
915 unsigned long set
, i
;
919 fdt
= files_fdtable(files
);
920 if (i
>= fdt
->max_fds
)
922 set
= fdt
->close_on_exec
->fds_bits
[j
];
925 fdt
->close_on_exec
->fds_bits
[j
] = 0;
926 spin_unlock(&files
->file_lock
);
927 for ( ; set
; i
++,set
>>= 1) {
932 spin_lock(&files
->file_lock
);
935 spin_unlock(&files
->file_lock
);
938 char *get_task_comm(char *buf
, struct task_struct
*tsk
)
940 /* buf must be at least sizeof(tsk->comm) in size */
942 strncpy(buf
, tsk
->comm
, sizeof(tsk
->comm
));
947 void set_task_comm(struct task_struct
*tsk
, char *buf
)
950 strlcpy(tsk
->comm
, buf
, sizeof(tsk
->comm
));
954 int flush_old_exec(struct linux_binprm
* bprm
)
958 char tcomm
[sizeof(current
->comm
)];
961 * Make sure we have a private signal table and that
962 * we are unassociated from the previous thread group.
964 retval
= de_thread(current
);
968 set_mm_exe_file(bprm
->mm
, bprm
->file
);
971 * Release all of the old mmap stuff
973 retval
= exec_mmap(bprm
->mm
);
977 bprm
->mm
= NULL
; /* We're using it now */
979 /* This is the point of no return */
980 current
->sas_ss_sp
= current
->sas_ss_size
= 0;
982 if (current_euid() == current_uid() && current_egid() == current_gid())
983 set_dumpable(current
->mm
, 1);
985 set_dumpable(current
->mm
, suid_dumpable
);
987 name
= bprm
->filename
;
989 /* Copies the binary name from after last slash */
990 for (i
=0; (ch
= *(name
++)) != '\0';) {
992 i
= 0; /* overwrite what we wrote */
994 if (i
< (sizeof(tcomm
) - 1))
998 set_task_comm(current
, tcomm
);
1000 current
->flags
&= ~PF_RANDOMIZE
;
1003 /* Set the new mm task size. We have to do that late because it may
1004 * depend on TIF_32BIT which is only updated in flush_thread() on
1005 * some architectures like powerpc
1007 current
->mm
->task_size
= TASK_SIZE
;
1009 /* install the new credentials */
1010 if (bprm
->cred
->uid
!= current_euid() ||
1011 bprm
->cred
->gid
!= current_egid()) {
1012 current
->pdeath_signal
= 0;
1013 } else if (file_permission(bprm
->file
, MAY_READ
) ||
1014 bprm
->interp_flags
& BINPRM_FLAGS_ENFORCE_NONDUMP
) {
1015 set_dumpable(current
->mm
, suid_dumpable
);
1018 current
->personality
&= ~bprm
->per_clear
;
1020 /* An exec changes our domain. We are no longer part of the thread
1023 current
->self_exec_id
++;
1025 flush_signal_handlers(current
, 0);
1026 flush_old_files(current
->files
);
1034 EXPORT_SYMBOL(flush_old_exec
);
1037 * install the new credentials for this executable
1039 void install_exec_creds(struct linux_binprm
*bprm
)
1041 security_bprm_committing_creds(bprm
);
1043 commit_creds(bprm
->cred
);
1046 /* cred_exec_mutex must be held at least to this point to prevent
1047 * ptrace_attach() from altering our determination of the task's
1048 * credentials; any time after this it may be unlocked */
1050 security_bprm_committed_creds(bprm
);
1052 EXPORT_SYMBOL(install_exec_creds
);
1055 * determine how safe it is to execute the proposed program
1056 * - the caller must hold current->cred_exec_mutex to protect against
1059 void check_unsafe_exec(struct linux_binprm
*bprm
)
1061 struct task_struct
*p
= current
;
1063 bprm
->unsafe
= tracehook_unsafe_exec(p
);
1065 if (atomic_read(&p
->fs
->count
) > 1 ||
1066 atomic_read(&p
->files
->count
) > 1 ||
1067 atomic_read(&p
->sighand
->count
) > 1)
1068 bprm
->unsafe
|= LSM_UNSAFE_SHARE
;
1072 * Fill the binprm structure from the inode.
1073 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1075 * This may be called multiple times for binary chains (scripts for example).
1077 int prepare_binprm(struct linux_binprm
*bprm
)
1080 struct inode
* inode
= bprm
->file
->f_path
.dentry
->d_inode
;
1083 mode
= inode
->i_mode
;
1084 if (bprm
->file
->f_op
== NULL
)
1087 /* clear any previous set[ug]id data from a previous binary */
1088 bprm
->cred
->euid
= current_euid();
1089 bprm
->cred
->egid
= current_egid();
1091 if (!(bprm
->file
->f_path
.mnt
->mnt_flags
& MNT_NOSUID
)) {
1093 if (mode
& S_ISUID
) {
1094 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1095 bprm
->cred
->euid
= inode
->i_uid
;
1100 * If setgid is set but no group execute bit then this
1101 * is a candidate for mandatory locking, not a setgid
1104 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
1105 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1106 bprm
->cred
->egid
= inode
->i_gid
;
1110 /* fill in binprm security blob */
1111 retval
= security_bprm_set_creds(bprm
);
1114 bprm
->cred_prepared
= 1;
1116 memset(bprm
->buf
, 0, BINPRM_BUF_SIZE
);
1117 return kernel_read(bprm
->file
, 0, bprm
->buf
, BINPRM_BUF_SIZE
);
1120 EXPORT_SYMBOL(prepare_binprm
);
1123 * Arguments are '\0' separated strings found at the location bprm->p
1124 * points to; chop off the first by relocating brpm->p to right after
1125 * the first '\0' encountered.
1127 int remove_arg_zero(struct linux_binprm
*bprm
)
1130 unsigned long offset
;
1138 offset
= bprm
->p
& ~PAGE_MASK
;
1139 page
= get_arg_page(bprm
, bprm
->p
, 0);
1144 kaddr
= kmap_atomic(page
, KM_USER0
);
1146 for (; offset
< PAGE_SIZE
&& kaddr
[offset
];
1147 offset
++, bprm
->p
++)
1150 kunmap_atomic(kaddr
, KM_USER0
);
1153 if (offset
== PAGE_SIZE
)
1154 free_arg_page(bprm
, (bprm
->p
>> PAGE_SHIFT
) - 1);
1155 } while (offset
== PAGE_SIZE
);
1164 EXPORT_SYMBOL(remove_arg_zero
);
1167 * cycle the list of binary formats handler, until one recognizes the image
1169 int search_binary_handler(struct linux_binprm
*bprm
,struct pt_regs
*regs
)
1171 unsigned int depth
= bprm
->recursion_depth
;
1173 struct linux_binfmt
*fmt
;
1175 /* handle /sbin/loader.. */
1177 struct exec
* eh
= (struct exec
*) bprm
->buf
;
1179 if (!bprm
->loader
&& eh
->fh
.f_magic
== 0x183 &&
1180 (eh
->fh
.f_flags
& 0x3000) == 0x3000)
1183 unsigned long loader
;
1185 allow_write_access(bprm
->file
);
1189 loader
= bprm
->vma
->vm_end
- sizeof(void *);
1191 file
= open_exec("/sbin/loader");
1192 retval
= PTR_ERR(file
);
1196 /* Remember if the application is TASO. */
1197 bprm
->taso
= eh
->ah
.entry
< 0x100000000UL
;
1200 bprm
->loader
= loader
;
1201 retval
= prepare_binprm(bprm
);
1204 /* should call search_binary_handler recursively here,
1205 but it does not matter */
1209 retval
= security_bprm_check(bprm
);
1213 /* kernel module loader fixup */
1214 /* so we don't try to load run modprobe in kernel space. */
1217 retval
= audit_bprm(bprm
);
1222 for (try=0; try<2; try++) {
1223 read_lock(&binfmt_lock
);
1224 list_for_each_entry(fmt
, &formats
, lh
) {
1225 int (*fn
)(struct linux_binprm
*, struct pt_regs
*) = fmt
->load_binary
;
1228 if (!try_module_get(fmt
->module
))
1230 read_unlock(&binfmt_lock
);
1231 retval
= fn(bprm
, regs
);
1233 * Restore the depth counter to its starting value
1234 * in this call, so we don't have to rely on every
1235 * load_binary function to restore it on return.
1237 bprm
->recursion_depth
= depth
;
1240 tracehook_report_exec(fmt
, bprm
, regs
);
1242 allow_write_access(bprm
->file
);
1246 current
->did_exec
= 1;
1247 proc_exec_connector(current
);
1250 read_lock(&binfmt_lock
);
1252 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
)
1255 read_unlock(&binfmt_lock
);
1259 read_unlock(&binfmt_lock
);
1260 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
) {
1262 #ifdef CONFIG_MODULES
1264 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1265 if (printable(bprm
->buf
[0]) &&
1266 printable(bprm
->buf
[1]) &&
1267 printable(bprm
->buf
[2]) &&
1268 printable(bprm
->buf
[3]))
1269 break; /* -ENOEXEC */
1270 request_module("binfmt-%04x", *(unsigned short *)(&bprm
->buf
[2]));
1277 EXPORT_SYMBOL(search_binary_handler
);
1279 void free_bprm(struct linux_binprm
*bprm
)
1281 free_arg_pages(bprm
);
1283 abort_creds(bprm
->cred
);
1288 * sys_execve() executes a new program.
1290 int do_execve(char * filename
,
1291 char __user
*__user
*argv
,
1292 char __user
*__user
*envp
,
1293 struct pt_regs
* regs
)
1295 struct linux_binprm
*bprm
;
1297 struct files_struct
*displaced
;
1300 retval
= unshare_files(&displaced
);
1305 bprm
= kzalloc(sizeof(*bprm
), GFP_KERNEL
);
1309 retval
= mutex_lock_interruptible(¤t
->cred_exec_mutex
);
1314 bprm
->cred
= prepare_exec_creds();
1317 check_unsafe_exec(bprm
);
1319 file
= open_exec(filename
);
1320 retval
= PTR_ERR(file
);
1327 bprm
->filename
= filename
;
1328 bprm
->interp
= filename
;
1330 retval
= bprm_mm_init(bprm
);
1334 bprm
->argc
= count(argv
, MAX_ARG_STRINGS
);
1335 if ((retval
= bprm
->argc
) < 0)
1338 bprm
->envc
= count(envp
, MAX_ARG_STRINGS
);
1339 if ((retval
= bprm
->envc
) < 0)
1342 retval
= prepare_binprm(bprm
);
1346 retval
= copy_strings_kernel(1, &bprm
->filename
, bprm
);
1350 bprm
->exec
= bprm
->p
;
1351 retval
= copy_strings(bprm
->envc
, envp
, bprm
);
1355 retval
= copy_strings(bprm
->argc
, argv
, bprm
);
1359 current
->flags
&= ~PF_KTHREAD
;
1360 retval
= search_binary_handler(bprm
,regs
);
1364 /* execve succeeded */
1365 mutex_unlock(¤t
->cred_exec_mutex
);
1366 acct_update_integrals(current
);
1369 put_files_struct(displaced
);
1378 allow_write_access(bprm
->file
);
1383 mutex_unlock(¤t
->cred_exec_mutex
);
1390 reset_files_struct(displaced
);
1395 int set_binfmt(struct linux_binfmt
*new)
1397 struct linux_binfmt
*old
= current
->binfmt
;
1400 if (!try_module_get(new->module
))
1403 current
->binfmt
= new;
1405 module_put(old
->module
);
1409 EXPORT_SYMBOL(set_binfmt
);
1411 /* format_corename will inspect the pattern parameter, and output a
1412 * name into corename, which must have space for at least
1413 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1415 static int format_corename(char *corename
, long signr
)
1417 const struct cred
*cred
= current_cred();
1418 const char *pat_ptr
= core_pattern
;
1419 int ispipe
= (*pat_ptr
== '|');
1420 char *out_ptr
= corename
;
1421 char *const out_end
= corename
+ CORENAME_MAX_SIZE
;
1423 int pid_in_pattern
= 0;
1425 /* Repeat as long as we have more pattern to process and more output
1428 if (*pat_ptr
!= '%') {
1429 if (out_ptr
== out_end
)
1431 *out_ptr
++ = *pat_ptr
++;
1433 switch (*++pat_ptr
) {
1436 /* Double percent, output one percent */
1438 if (out_ptr
== out_end
)
1445 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1446 "%d", task_tgid_vnr(current
));
1447 if (rc
> out_end
- out_ptr
)
1453 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1455 if (rc
> out_end
- out_ptr
)
1461 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1463 if (rc
> out_end
- out_ptr
)
1467 /* signal that caused the coredump */
1469 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1471 if (rc
> out_end
- out_ptr
)
1475 /* UNIX time of coredump */
1478 do_gettimeofday(&tv
);
1479 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1481 if (rc
> out_end
- out_ptr
)
1488 down_read(&uts_sem
);
1489 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1490 "%s", utsname()->nodename
);
1492 if (rc
> out_end
- out_ptr
)
1498 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1499 "%s", current
->comm
);
1500 if (rc
> out_end
- out_ptr
)
1504 /* core limit size */
1506 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1507 "%lu", current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
);
1508 if (rc
> out_end
- out_ptr
)
1518 /* Backward compatibility with core_uses_pid:
1520 * If core_pattern does not include a %p (as is the default)
1521 * and core_uses_pid is set, then .%pid will be appended to
1522 * the filename. Do not do this for piped commands. */
1523 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
1524 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1525 ".%d", task_tgid_vnr(current
));
1526 if (rc
> out_end
- out_ptr
)
1535 static int zap_process(struct task_struct
*start
)
1537 struct task_struct
*t
;
1540 start
->signal
->flags
= SIGNAL_GROUP_EXIT
;
1541 start
->signal
->group_stop_count
= 0;
1545 if (t
!= current
&& t
->mm
) {
1546 sigaddset(&t
->pending
.signal
, SIGKILL
);
1547 signal_wake_up(t
, 1);
1550 } while_each_thread(start
, t
);
1555 static inline int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
1556 struct core_state
*core_state
, int exit_code
)
1558 struct task_struct
*g
, *p
;
1559 unsigned long flags
;
1562 spin_lock_irq(&tsk
->sighand
->siglock
);
1563 if (!signal_group_exit(tsk
->signal
)) {
1564 mm
->core_state
= core_state
;
1565 tsk
->signal
->group_exit_code
= exit_code
;
1566 nr
= zap_process(tsk
);
1568 spin_unlock_irq(&tsk
->sighand
->siglock
);
1569 if (unlikely(nr
< 0))
1572 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
1575 * We should find and kill all tasks which use this mm, and we should
1576 * count them correctly into ->nr_threads. We don't take tasklist
1577 * lock, but this is safe wrt:
1580 * None of sub-threads can fork after zap_process(leader). All
1581 * processes which were created before this point should be
1582 * visible to zap_threads() because copy_process() adds the new
1583 * process to the tail of init_task.tasks list, and lock/unlock
1584 * of ->siglock provides a memory barrier.
1587 * The caller holds mm->mmap_sem. This means that the task which
1588 * uses this mm can't pass exit_mm(), so it can't exit or clear
1592 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1593 * we must see either old or new leader, this does not matter.
1594 * However, it can change p->sighand, so lock_task_sighand(p)
1595 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1598 * Note also that "g" can be the old leader with ->mm == NULL
1599 * and already unhashed and thus removed from ->thread_group.
1600 * This is OK, __unhash_process()->list_del_rcu() does not
1601 * clear the ->next pointer, we will find the new leader via
1605 for_each_process(g
) {
1606 if (g
== tsk
->group_leader
)
1608 if (g
->flags
& PF_KTHREAD
)
1613 if (unlikely(p
->mm
== mm
)) {
1614 lock_task_sighand(p
, &flags
);
1615 nr
+= zap_process(p
);
1616 unlock_task_sighand(p
, &flags
);
1620 } while_each_thread(g
, p
);
1624 atomic_set(&core_state
->nr_threads
, nr
);
1628 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
1630 struct task_struct
*tsk
= current
;
1631 struct mm_struct
*mm
= tsk
->mm
;
1632 struct completion
*vfork_done
;
1635 init_completion(&core_state
->startup
);
1636 core_state
->dumper
.task
= tsk
;
1637 core_state
->dumper
.next
= NULL
;
1638 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
1639 up_write(&mm
->mmap_sem
);
1641 if (unlikely(core_waiters
< 0))
1645 * Make sure nobody is waiting for us to release the VM,
1646 * otherwise we can deadlock when we wait on each other
1648 vfork_done
= tsk
->vfork_done
;
1650 tsk
->vfork_done
= NULL
;
1651 complete(vfork_done
);
1655 wait_for_completion(&core_state
->startup
);
1657 return core_waiters
;
1660 static void coredump_finish(struct mm_struct
*mm
)
1662 struct core_thread
*curr
, *next
;
1663 struct task_struct
*task
;
1665 next
= mm
->core_state
->dumper
.next
;
1666 while ((curr
= next
) != NULL
) {
1670 * see exit_mm(), curr->task must not see
1671 * ->task == NULL before we read ->next.
1675 wake_up_process(task
);
1678 mm
->core_state
= NULL
;
1682 * set_dumpable converts traditional three-value dumpable to two flags and
1683 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1684 * these bits are not changed atomically. So get_dumpable can observe the
1685 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1686 * return either old dumpable or new one by paying attention to the order of
1687 * modifying the bits.
1689 * dumpable | mm->flags (binary)
1690 * old new | initial interim final
1691 * ---------+-----------------------
1699 * (*) get_dumpable regards interim value of 10 as 11.
1701 void set_dumpable(struct mm_struct
*mm
, int value
)
1705 clear_bit(MMF_DUMPABLE
, &mm
->flags
);
1707 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1710 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1712 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1715 set_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1717 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1722 int get_dumpable(struct mm_struct
*mm
)
1726 ret
= mm
->flags
& 0x3;
1727 return (ret
>= 2) ? 2 : ret
;
1730 int do_coredump(long signr
, int exit_code
, struct pt_regs
* regs
)
1732 struct core_state core_state
;
1733 char corename
[CORENAME_MAX_SIZE
+ 1];
1734 struct mm_struct
*mm
= current
->mm
;
1735 struct linux_binfmt
* binfmt
;
1736 struct inode
* inode
;
1738 const struct cred
*old_cred
;
1743 unsigned long core_limit
= current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
;
1744 char **helper_argv
= NULL
;
1745 int helper_argc
= 0;
1748 audit_core_dumps(signr
);
1750 binfmt
= current
->binfmt
;
1751 if (!binfmt
|| !binfmt
->core_dump
)
1754 cred
= prepare_creds();
1760 down_write(&mm
->mmap_sem
);
1762 * If another thread got here first, or we are not dumpable, bail out.
1764 if (mm
->core_state
|| !get_dumpable(mm
)) {
1765 up_write(&mm
->mmap_sem
);
1771 * We cannot trust fsuid as being the "true" uid of the
1772 * process nor do we know its entire history. We only know it
1773 * was tainted so we dump it as root in mode 2.
1775 if (get_dumpable(mm
) == 2) { /* Setuid core dump mode */
1776 flag
= O_EXCL
; /* Stop rewrite attacks */
1777 cred
->fsuid
= 0; /* Dump root private */
1780 retval
= coredump_wait(exit_code
, &core_state
);
1786 old_cred
= override_creds(cred
);
1789 * Clear any false indication of pending signals that might
1790 * be seen by the filesystem code called to write the core file.
1792 clear_thread_flag(TIF_SIGPENDING
);
1795 * lock_kernel() because format_corename() is controlled by sysctl, which
1796 * uses lock_kernel()
1799 ispipe
= format_corename(corename
, signr
);
1802 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1803 * to a pipe. Since we're not writing directly to the filesystem
1804 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1805 * created unless the pipe reader choses to write out the core file
1806 * at which point file size limits and permissions will be imposed
1807 * as it does with any other process
1809 if ((!ispipe
) && (core_limit
< binfmt
->min_coredump
))
1813 helper_argv
= argv_split(GFP_KERNEL
, corename
+1, &helper_argc
);
1814 /* Terminate the string before the first option */
1815 delimit
= strchr(corename
, ' ');
1818 delimit
= strrchr(helper_argv
[0], '/');
1822 delimit
= helper_argv
[0];
1823 if (!strcmp(delimit
, current
->comm
)) {
1824 printk(KERN_NOTICE
"Recursive core dump detected, "
1829 core_limit
= RLIM_INFINITY
;
1831 /* SIGPIPE can happen, but it's just never processed */
1832 if (call_usermodehelper_pipe(corename
+1, helper_argv
, NULL
,
1834 printk(KERN_INFO
"Core dump to %s pipe failed\n",
1839 file
= filp_open(corename
,
1840 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
1844 inode
= file
->f_path
.dentry
->d_inode
;
1845 if (inode
->i_nlink
> 1)
1846 goto close_fail
; /* multiple links - don't dump */
1847 if (!ispipe
&& d_unhashed(file
->f_path
.dentry
))
1850 /* AK: actually i see no reason to not allow this for named pipes etc.,
1851 but keep the previous behaviour for now. */
1852 if (!ispipe
&& !S_ISREG(inode
->i_mode
))
1855 * Dont allow local users get cute and trick others to coredump
1856 * into their pre-created files:
1858 if (inode
->i_uid
!= current_fsuid())
1862 if (!file
->f_op
->write
)
1864 if (!ispipe
&& do_truncate(file
->f_path
.dentry
, 0, 0, file
) != 0)
1867 retval
= binfmt
->core_dump(signr
, regs
, file
, core_limit
);
1870 current
->signal
->group_exit_code
|= 0x80;
1872 filp_close(file
, NULL
);
1875 argv_free(helper_argv
);
1877 revert_creds(old_cred
);
1879 coredump_finish(mm
);