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/highmem.h>
36 #include <linux/spinlock.h>
37 #include <linux/key.h>
38 #include <linux/personality.h>
39 #include <linux/binfmts.h>
40 #include <linux/utsname.h>
41 #include <linux/pid_namespace.h>
42 #include <linux/module.h>
43 #include <linux/namei.h>
44 #include <linux/proc_fs.h>
45 #include <linux/ptrace.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>
53 #include <asm/uaccess.h>
54 #include <asm/mmu_context.h>
58 #include <linux/kmod.h>
62 /* for /sbin/loader handling in search_binary_handler() */
63 #include <linux/a.out.h>
67 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
68 int suid_dumpable
= 0;
70 /* The maximal length of core_pattern is also specified in sysctl.c */
72 static LIST_HEAD(formats
);
73 static DEFINE_RWLOCK(binfmt_lock
);
75 int register_binfmt(struct linux_binfmt
* fmt
)
79 write_lock(&binfmt_lock
);
80 list_add(&fmt
->lh
, &formats
);
81 write_unlock(&binfmt_lock
);
85 EXPORT_SYMBOL(register_binfmt
);
87 void unregister_binfmt(struct linux_binfmt
* fmt
)
89 write_lock(&binfmt_lock
);
91 write_unlock(&binfmt_lock
);
94 EXPORT_SYMBOL(unregister_binfmt
);
96 static inline void put_binfmt(struct linux_binfmt
* fmt
)
98 module_put(fmt
->module
);
102 * Note that a shared library must be both readable and executable due to
105 * Also note that we take the address to load from from the file itself.
107 asmlinkage
long sys_uselib(const char __user
* library
)
113 error
= __user_path_lookup_open(library
, LOOKUP_FOLLOW
, &nd
, FMODE_READ
|FMODE_EXEC
);
118 if (!S_ISREG(nd
.path
.dentry
->d_inode
->i_mode
))
121 error
= vfs_permission(&nd
, MAY_READ
| MAY_EXEC
);
125 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
126 error
= PTR_ERR(file
);
132 struct linux_binfmt
* fmt
;
134 read_lock(&binfmt_lock
);
135 list_for_each_entry(fmt
, &formats
, lh
) {
136 if (!fmt
->load_shlib
)
138 if (!try_module_get(fmt
->module
))
140 read_unlock(&binfmt_lock
);
141 error
= fmt
->load_shlib(file
);
142 read_lock(&binfmt_lock
);
144 if (error
!= -ENOEXEC
)
147 read_unlock(&binfmt_lock
);
153 release_open_intent(&nd
);
160 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
166 #ifdef CONFIG_STACK_GROWSUP
168 ret
= expand_stack_downwards(bprm
->vma
, pos
);
173 ret
= get_user_pages(current
, bprm
->mm
, pos
,
174 1, write
, 1, &page
, NULL
);
179 unsigned long size
= bprm
->vma
->vm_end
- bprm
->vma
->vm_start
;
183 * We've historically supported up to 32 pages (ARG_MAX)
184 * of argument strings even with small stacks
190 * Limit to 1/4-th the stack size for the argv+env strings.
192 * - the remaining binfmt code will not run out of stack space,
193 * - the program will have a reasonable amount of stack left
196 rlim
= current
->signal
->rlim
;
197 if (size
> rlim
[RLIMIT_STACK
].rlim_cur
/ 4) {
206 static void put_arg_page(struct page
*page
)
211 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
215 static void free_arg_pages(struct linux_binprm
*bprm
)
219 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
222 flush_cache_page(bprm
->vma
, pos
, page_to_pfn(page
));
225 static int __bprm_mm_init(struct linux_binprm
*bprm
)
228 struct vm_area_struct
*vma
= NULL
;
229 struct mm_struct
*mm
= bprm
->mm
;
231 bprm
->vma
= vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
235 down_write(&mm
->mmap_sem
);
239 * Place the stack at the largest stack address the architecture
240 * supports. Later, we'll move this to an appropriate place. We don't
241 * use STACK_TOP because that can depend on attributes which aren't
244 vma
->vm_end
= STACK_TOP_MAX
;
245 vma
->vm_start
= vma
->vm_end
- PAGE_SIZE
;
247 vma
->vm_flags
= VM_STACK_FLAGS
;
248 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
249 err
= insert_vm_struct(mm
, vma
);
251 up_write(&mm
->mmap_sem
);
255 mm
->stack_vm
= mm
->total_vm
= 1;
256 up_write(&mm
->mmap_sem
);
258 bprm
->p
= vma
->vm_end
- sizeof(void *);
265 kmem_cache_free(vm_area_cachep
, vma
);
271 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
273 return len
<= MAX_ARG_STRLEN
;
278 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
283 page
= bprm
->page
[pos
/ PAGE_SIZE
];
284 if (!page
&& write
) {
285 page
= alloc_page(GFP_HIGHUSER
|__GFP_ZERO
);
288 bprm
->page
[pos
/ PAGE_SIZE
] = page
;
294 static void put_arg_page(struct page
*page
)
298 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
301 __free_page(bprm
->page
[i
]);
302 bprm
->page
[i
] = NULL
;
306 static void free_arg_pages(struct linux_binprm
*bprm
)
310 for (i
= 0; i
< MAX_ARG_PAGES
; i
++)
311 free_arg_page(bprm
, i
);
314 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
319 static int __bprm_mm_init(struct linux_binprm
*bprm
)
321 bprm
->p
= PAGE_SIZE
* MAX_ARG_PAGES
- sizeof(void *);
325 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
327 return len
<= bprm
->p
;
330 #endif /* CONFIG_MMU */
333 * Create a new mm_struct and populate it with a temporary stack
334 * vm_area_struct. We don't have enough context at this point to set the stack
335 * flags, permissions, and offset, so we use temporary values. We'll update
336 * them later in setup_arg_pages().
338 int bprm_mm_init(struct linux_binprm
*bprm
)
341 struct mm_struct
*mm
= NULL
;
343 bprm
->mm
= mm
= mm_alloc();
348 err
= init_new_context(current
, mm
);
352 err
= __bprm_mm_init(bprm
);
368 * count() counts the number of strings in array ARGV.
370 static int count(char __user
* __user
* argv
, int max
)
378 if (get_user(p
, argv
))
392 * 'copy_strings()' copies argument/environment strings from the old
393 * processes's memory to the new process's stack. The call to get_user_pages()
394 * ensures the destination page is created and not swapped out.
396 static int copy_strings(int argc
, char __user
* __user
* argv
,
397 struct linux_binprm
*bprm
)
399 struct page
*kmapped_page
= NULL
;
401 unsigned long kpos
= 0;
409 if (get_user(str
, argv
+argc
) ||
410 !(len
= strnlen_user(str
, MAX_ARG_STRLEN
))) {
415 if (!valid_arg_len(bprm
, len
)) {
420 /* We're going to work our way backwords. */
426 int offset
, bytes_to_copy
;
428 offset
= pos
% PAGE_SIZE
;
432 bytes_to_copy
= offset
;
433 if (bytes_to_copy
> len
)
436 offset
-= bytes_to_copy
;
437 pos
-= bytes_to_copy
;
438 str
-= bytes_to_copy
;
439 len
-= bytes_to_copy
;
441 if (!kmapped_page
|| kpos
!= (pos
& PAGE_MASK
)) {
444 page
= get_arg_page(bprm
, pos
, 1);
451 flush_kernel_dcache_page(kmapped_page
);
452 kunmap(kmapped_page
);
453 put_arg_page(kmapped_page
);
456 kaddr
= kmap(kmapped_page
);
457 kpos
= pos
& PAGE_MASK
;
458 flush_arg_page(bprm
, kpos
, kmapped_page
);
460 if (copy_from_user(kaddr
+offset
, str
, bytes_to_copy
)) {
469 flush_kernel_dcache_page(kmapped_page
);
470 kunmap(kmapped_page
);
471 put_arg_page(kmapped_page
);
477 * Like copy_strings, but get argv and its values from kernel memory.
479 int copy_strings_kernel(int argc
,char ** argv
, struct linux_binprm
*bprm
)
482 mm_segment_t oldfs
= get_fs();
484 r
= copy_strings(argc
, (char __user
* __user
*)argv
, bprm
);
488 EXPORT_SYMBOL(copy_strings_kernel
);
493 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
494 * the binfmt code determines where the new stack should reside, we shift it to
495 * its final location. The process proceeds as follows:
497 * 1) Use shift to calculate the new vma endpoints.
498 * 2) Extend vma to cover both the old and new ranges. This ensures the
499 * arguments passed to subsequent functions are consistent.
500 * 3) Move vma's page tables to the new range.
501 * 4) Free up any cleared pgd range.
502 * 5) Shrink the vma to cover only the new range.
504 static int shift_arg_pages(struct vm_area_struct
*vma
, unsigned long shift
)
506 struct mm_struct
*mm
= vma
->vm_mm
;
507 unsigned long old_start
= vma
->vm_start
;
508 unsigned long old_end
= vma
->vm_end
;
509 unsigned long length
= old_end
- old_start
;
510 unsigned long new_start
= old_start
- shift
;
511 unsigned long new_end
= old_end
- shift
;
512 struct mmu_gather
*tlb
;
514 BUG_ON(new_start
> new_end
);
517 * ensure there are no vmas between where we want to go
520 if (vma
!= find_vma(mm
, new_start
))
524 * cover the whole range: [new_start, old_end)
526 vma_adjust(vma
, new_start
, old_end
, vma
->vm_pgoff
, NULL
);
529 * move the page tables downwards, on failure we rely on
530 * process cleanup to remove whatever mess we made.
532 if (length
!= move_page_tables(vma
, old_start
,
533 vma
, new_start
, length
))
537 tlb
= tlb_gather_mmu(mm
, 0);
538 if (new_end
> old_start
) {
540 * when the old and new regions overlap clear from new_end.
542 free_pgd_range(tlb
, new_end
, old_end
, new_end
,
543 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
546 * otherwise, clean from old_start; this is done to not touch
547 * the address space in [new_end, old_start) some architectures
548 * have constraints on va-space that make this illegal (IA64) -
549 * for the others its just a little faster.
551 free_pgd_range(tlb
, old_start
, old_end
, new_end
,
552 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
554 tlb_finish_mmu(tlb
, new_end
, old_end
);
557 * shrink the vma to just the new range.
559 vma_adjust(vma
, new_start
, new_end
, vma
->vm_pgoff
, NULL
);
564 #define EXTRA_STACK_VM_PAGES 20 /* random */
567 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
568 * the stack is optionally relocated, and some extra space is added.
570 int setup_arg_pages(struct linux_binprm
*bprm
,
571 unsigned long stack_top
,
572 int executable_stack
)
575 unsigned long stack_shift
;
576 struct mm_struct
*mm
= current
->mm
;
577 struct vm_area_struct
*vma
= bprm
->vma
;
578 struct vm_area_struct
*prev
= NULL
;
579 unsigned long vm_flags
;
580 unsigned long stack_base
;
582 #ifdef CONFIG_STACK_GROWSUP
583 /* Limit stack size to 1GB */
584 stack_base
= current
->signal
->rlim
[RLIMIT_STACK
].rlim_max
;
585 if (stack_base
> (1 << 30))
586 stack_base
= 1 << 30;
588 /* Make sure we didn't let the argument array grow too large. */
589 if (vma
->vm_end
- vma
->vm_start
> stack_base
)
592 stack_base
= PAGE_ALIGN(stack_top
- stack_base
);
594 stack_shift
= vma
->vm_start
- stack_base
;
595 mm
->arg_start
= bprm
->p
- stack_shift
;
596 bprm
->p
= vma
->vm_end
- stack_shift
;
598 stack_top
= arch_align_stack(stack_top
);
599 stack_top
= PAGE_ALIGN(stack_top
);
600 stack_shift
= vma
->vm_end
- stack_top
;
602 bprm
->p
-= stack_shift
;
603 mm
->arg_start
= bprm
->p
;
607 bprm
->loader
-= stack_shift
;
608 bprm
->exec
-= stack_shift
;
610 down_write(&mm
->mmap_sem
);
611 vm_flags
= VM_STACK_FLAGS
;
614 * Adjust stack execute permissions; explicitly enable for
615 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
616 * (arch default) otherwise.
618 if (unlikely(executable_stack
== EXSTACK_ENABLE_X
))
620 else if (executable_stack
== EXSTACK_DISABLE_X
)
621 vm_flags
&= ~VM_EXEC
;
622 vm_flags
|= mm
->def_flags
;
624 ret
= mprotect_fixup(vma
, &prev
, vma
->vm_start
, vma
->vm_end
,
630 /* Move stack pages down in memory. */
632 ret
= shift_arg_pages(vma
, stack_shift
);
634 up_write(&mm
->mmap_sem
);
639 #ifdef CONFIG_STACK_GROWSUP
640 stack_base
= vma
->vm_end
+ EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
642 stack_base
= vma
->vm_start
- EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
644 ret
= expand_stack(vma
, stack_base
);
649 up_write(&mm
->mmap_sem
);
652 EXPORT_SYMBOL(setup_arg_pages
);
654 #endif /* CONFIG_MMU */
656 struct file
*open_exec(const char *name
)
662 err
= path_lookup_open(AT_FDCWD
, name
, LOOKUP_FOLLOW
, &nd
, FMODE_READ
|FMODE_EXEC
);
666 struct inode
*inode
= nd
.path
.dentry
->d_inode
;
667 file
= ERR_PTR(-EACCES
);
668 if (S_ISREG(inode
->i_mode
)) {
669 int err
= vfs_permission(&nd
, MAY_EXEC
);
672 file
= nameidata_to_filp(&nd
,
673 O_RDONLY
|O_LARGEFILE
);
675 err
= deny_write_access(file
);
685 release_open_intent(&nd
);
691 EXPORT_SYMBOL(open_exec
);
693 int kernel_read(struct file
*file
, unsigned long offset
,
694 char *addr
, unsigned long count
)
702 /* The cast to a user pointer is valid due to the set_fs() */
703 result
= vfs_read(file
, (void __user
*)addr
, count
, &pos
);
708 EXPORT_SYMBOL(kernel_read
);
710 static int exec_mmap(struct mm_struct
*mm
)
712 struct task_struct
*tsk
;
713 struct mm_struct
* old_mm
, *active_mm
;
715 /* Notify parent that we're no longer interested in the old VM */
717 old_mm
= current
->mm
;
718 mm_release(tsk
, old_mm
);
722 * Make sure that if there is a core dump in progress
723 * for the old mm, we get out and die instead of going
724 * through with the exec. We must hold mmap_sem around
725 * checking core_state and changing tsk->mm.
727 down_read(&old_mm
->mmap_sem
);
728 if (unlikely(old_mm
->core_state
)) {
729 up_read(&old_mm
->mmap_sem
);
734 active_mm
= tsk
->active_mm
;
737 activate_mm(active_mm
, mm
);
739 mm_update_next_owner(old_mm
);
740 arch_pick_mmap_layout(mm
);
742 up_read(&old_mm
->mmap_sem
);
743 BUG_ON(active_mm
!= old_mm
);
752 * This function makes sure the current process has its own signal table,
753 * so that flush_signal_handlers can later reset the handlers without
754 * disturbing other processes. (Other processes might share the signal
755 * table via the CLONE_SIGHAND option to clone().)
757 static int de_thread(struct task_struct
*tsk
)
759 struct signal_struct
*sig
= tsk
->signal
;
760 struct sighand_struct
*oldsighand
= tsk
->sighand
;
761 spinlock_t
*lock
= &oldsighand
->siglock
;
762 struct task_struct
*leader
= NULL
;
765 if (thread_group_empty(tsk
))
766 goto no_thread_group
;
769 * Kill all other threads in the thread group.
772 if (signal_group_exit(sig
)) {
774 * Another group action in progress, just
775 * return so that the signal is processed.
777 spin_unlock_irq(lock
);
780 sig
->group_exit_task
= tsk
;
781 zap_other_threads(tsk
);
783 /* Account for the thread group leader hanging around: */
784 count
= thread_group_leader(tsk
) ? 1 : 2;
785 sig
->notify_count
= count
;
786 while (atomic_read(&sig
->count
) > count
) {
787 __set_current_state(TASK_UNINTERRUPTIBLE
);
788 spin_unlock_irq(lock
);
792 spin_unlock_irq(lock
);
795 * At this point all other threads have exited, all we have to
796 * do is to wait for the thread group leader to become inactive,
797 * and to assume its PID:
799 if (!thread_group_leader(tsk
)) {
800 leader
= tsk
->group_leader
;
802 sig
->notify_count
= -1; /* for exit_notify() */
804 write_lock_irq(&tasklist_lock
);
805 if (likely(leader
->exit_state
))
807 __set_current_state(TASK_UNINTERRUPTIBLE
);
808 write_unlock_irq(&tasklist_lock
);
812 if (unlikely(task_child_reaper(tsk
) == leader
))
813 task_active_pid_ns(tsk
)->child_reaper
= tsk
;
815 * The only record we have of the real-time age of a
816 * process, regardless of execs it's done, is start_time.
817 * All the past CPU time is accumulated in signal_struct
818 * from sister threads now dead. But in this non-leader
819 * exec, nothing survives from the original leader thread,
820 * whose birth marks the true age of this process now.
821 * When we take on its identity by switching to its PID, we
822 * also take its birthdate (always earlier than our own).
824 tsk
->start_time
= leader
->start_time
;
826 BUG_ON(!same_thread_group(leader
, tsk
));
827 BUG_ON(has_group_leader_pid(tsk
));
829 * An exec() starts a new thread group with the
830 * TGID of the previous thread group. Rehash the
831 * two threads with a switched PID, and release
832 * the former thread group leader:
835 /* Become a process group leader with the old leader's pid.
836 * The old leader becomes a thread of the this thread group.
837 * Note: The old leader also uses this pid until release_task
838 * is called. Odd but simple and correct.
840 detach_pid(tsk
, PIDTYPE_PID
);
841 tsk
->pid
= leader
->pid
;
842 attach_pid(tsk
, PIDTYPE_PID
, task_pid(leader
));
843 transfer_pid(leader
, tsk
, PIDTYPE_PGID
);
844 transfer_pid(leader
, tsk
, PIDTYPE_SID
);
845 list_replace_rcu(&leader
->tasks
, &tsk
->tasks
);
847 tsk
->group_leader
= tsk
;
848 leader
->group_leader
= tsk
;
850 tsk
->exit_signal
= SIGCHLD
;
852 BUG_ON(leader
->exit_state
!= EXIT_ZOMBIE
);
853 leader
->exit_state
= EXIT_DEAD
;
855 write_unlock_irq(&tasklist_lock
);
858 sig
->group_exit_task
= NULL
;
859 sig
->notify_count
= 0;
863 flush_itimer_signals();
865 release_task(leader
);
867 if (atomic_read(&oldsighand
->count
) != 1) {
868 struct sighand_struct
*newsighand
;
870 * This ->sighand is shared with the CLONE_SIGHAND
871 * but not CLONE_THREAD task, switch to the new one.
873 newsighand
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
877 atomic_set(&newsighand
->count
, 1);
878 memcpy(newsighand
->action
, oldsighand
->action
,
879 sizeof(newsighand
->action
));
881 write_lock_irq(&tasklist_lock
);
882 spin_lock(&oldsighand
->siglock
);
883 rcu_assign_pointer(tsk
->sighand
, newsighand
);
884 spin_unlock(&oldsighand
->siglock
);
885 write_unlock_irq(&tasklist_lock
);
887 __cleanup_sighand(oldsighand
);
890 BUG_ON(!thread_group_leader(tsk
));
895 * These functions flushes out all traces of the currently running executable
896 * so that a new one can be started
898 static void flush_old_files(struct files_struct
* files
)
903 spin_lock(&files
->file_lock
);
905 unsigned long set
, i
;
909 fdt
= files_fdtable(files
);
910 if (i
>= fdt
->max_fds
)
912 set
= fdt
->close_on_exec
->fds_bits
[j
];
915 fdt
->close_on_exec
->fds_bits
[j
] = 0;
916 spin_unlock(&files
->file_lock
);
917 for ( ; set
; i
++,set
>>= 1) {
922 spin_lock(&files
->file_lock
);
925 spin_unlock(&files
->file_lock
);
928 char *get_task_comm(char *buf
, struct task_struct
*tsk
)
930 /* buf must be at least sizeof(tsk->comm) in size */
932 strncpy(buf
, tsk
->comm
, sizeof(tsk
->comm
));
937 void set_task_comm(struct task_struct
*tsk
, char *buf
)
940 strlcpy(tsk
->comm
, buf
, sizeof(tsk
->comm
));
944 int flush_old_exec(struct linux_binprm
* bprm
)
948 char tcomm
[sizeof(current
->comm
)];
951 * Make sure we have a private signal table and that
952 * we are unassociated from the previous thread group.
954 retval
= de_thread(current
);
958 set_mm_exe_file(bprm
->mm
, bprm
->file
);
961 * Release all of the old mmap stuff
963 retval
= exec_mmap(bprm
->mm
);
967 bprm
->mm
= NULL
; /* We're using it now */
969 /* This is the point of no return */
970 current
->sas_ss_sp
= current
->sas_ss_size
= 0;
972 if (current
->euid
== current
->uid
&& current
->egid
== current
->gid
)
973 set_dumpable(current
->mm
, 1);
975 set_dumpable(current
->mm
, suid_dumpable
);
977 name
= bprm
->filename
;
979 /* Copies the binary name from after last slash */
980 for (i
=0; (ch
= *(name
++)) != '\0';) {
982 i
= 0; /* overwrite what we wrote */
984 if (i
< (sizeof(tcomm
) - 1))
988 set_task_comm(current
, tcomm
);
990 current
->flags
&= ~PF_RANDOMIZE
;
993 /* Set the new mm task size. We have to do that late because it may
994 * depend on TIF_32BIT which is only updated in flush_thread() on
995 * some architectures like powerpc
997 current
->mm
->task_size
= TASK_SIZE
;
999 if (bprm
->e_uid
!= current
->euid
|| bprm
->e_gid
!= current
->egid
) {
1001 set_dumpable(current
->mm
, suid_dumpable
);
1002 current
->pdeath_signal
= 0;
1003 } else if (file_permission(bprm
->file
, MAY_READ
) ||
1004 (bprm
->interp_flags
& BINPRM_FLAGS_ENFORCE_NONDUMP
)) {
1006 set_dumpable(current
->mm
, suid_dumpable
);
1009 /* An exec changes our domain. We are no longer part of the thread
1012 current
->self_exec_id
++;
1014 flush_signal_handlers(current
, 0);
1015 flush_old_files(current
->files
);
1023 EXPORT_SYMBOL(flush_old_exec
);
1026 * Fill the binprm structure from the inode.
1027 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1029 int prepare_binprm(struct linux_binprm
*bprm
)
1032 struct inode
* inode
= bprm
->file
->f_path
.dentry
->d_inode
;
1035 mode
= inode
->i_mode
;
1036 if (bprm
->file
->f_op
== NULL
)
1039 bprm
->e_uid
= current
->euid
;
1040 bprm
->e_gid
= current
->egid
;
1042 if(!(bprm
->file
->f_path
.mnt
->mnt_flags
& MNT_NOSUID
)) {
1044 if (mode
& S_ISUID
) {
1045 current
->personality
&= ~PER_CLEAR_ON_SETID
;
1046 bprm
->e_uid
= inode
->i_uid
;
1051 * If setgid is set but no group execute bit then this
1052 * is a candidate for mandatory locking, not a setgid
1055 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
1056 current
->personality
&= ~PER_CLEAR_ON_SETID
;
1057 bprm
->e_gid
= inode
->i_gid
;
1061 /* fill in binprm security blob */
1062 retval
= security_bprm_set(bprm
);
1066 memset(bprm
->buf
,0,BINPRM_BUF_SIZE
);
1067 return kernel_read(bprm
->file
,0,bprm
->buf
,BINPRM_BUF_SIZE
);
1070 EXPORT_SYMBOL(prepare_binprm
);
1072 static int unsafe_exec(struct task_struct
*p
)
1075 if (p
->ptrace
& PT_PTRACED
) {
1076 if (p
->ptrace
& PT_PTRACE_CAP
)
1077 unsafe
|= LSM_UNSAFE_PTRACE_CAP
;
1079 unsafe
|= LSM_UNSAFE_PTRACE
;
1081 if (atomic_read(&p
->fs
->count
) > 1 ||
1082 atomic_read(&p
->files
->count
) > 1 ||
1083 atomic_read(&p
->sighand
->count
) > 1)
1084 unsafe
|= LSM_UNSAFE_SHARE
;
1089 void compute_creds(struct linux_binprm
*bprm
)
1093 if (bprm
->e_uid
!= current
->uid
) {
1095 current
->pdeath_signal
= 0;
1100 unsafe
= unsafe_exec(current
);
1101 security_bprm_apply_creds(bprm
, unsafe
);
1102 task_unlock(current
);
1103 security_bprm_post_apply_creds(bprm
);
1105 EXPORT_SYMBOL(compute_creds
);
1108 * Arguments are '\0' separated strings found at the location bprm->p
1109 * points to; chop off the first by relocating brpm->p to right after
1110 * the first '\0' encountered.
1112 int remove_arg_zero(struct linux_binprm
*bprm
)
1115 unsigned long offset
;
1123 offset
= bprm
->p
& ~PAGE_MASK
;
1124 page
= get_arg_page(bprm
, bprm
->p
, 0);
1129 kaddr
= kmap_atomic(page
, KM_USER0
);
1131 for (; offset
< PAGE_SIZE
&& kaddr
[offset
];
1132 offset
++, bprm
->p
++)
1135 kunmap_atomic(kaddr
, KM_USER0
);
1138 if (offset
== PAGE_SIZE
)
1139 free_arg_page(bprm
, (bprm
->p
>> PAGE_SHIFT
) - 1);
1140 } while (offset
== PAGE_SIZE
);
1149 EXPORT_SYMBOL(remove_arg_zero
);
1152 * cycle the list of binary formats handler, until one recognizes the image
1154 int search_binary_handler(struct linux_binprm
*bprm
,struct pt_regs
*regs
)
1157 struct linux_binfmt
*fmt
;
1159 /* handle /sbin/loader.. */
1161 struct exec
* eh
= (struct exec
*) bprm
->buf
;
1163 if (!bprm
->loader
&& eh
->fh
.f_magic
== 0x183 &&
1164 (eh
->fh
.f_flags
& 0x3000) == 0x3000)
1167 unsigned long loader
;
1169 allow_write_access(bprm
->file
);
1173 loader
= bprm
->vma
->vm_end
- sizeof(void *);
1175 file
= open_exec("/sbin/loader");
1176 retval
= PTR_ERR(file
);
1180 /* Remember if the application is TASO. */
1181 bprm
->sh_bang
= eh
->ah
.entry
< 0x100000000UL
;
1184 bprm
->loader
= loader
;
1185 retval
= prepare_binprm(bprm
);
1188 /* should call search_binary_handler recursively here,
1189 but it does not matter */
1193 retval
= security_bprm_check(bprm
);
1197 /* kernel module loader fixup */
1198 /* so we don't try to load run modprobe in kernel space. */
1201 retval
= audit_bprm(bprm
);
1206 for (try=0; try<2; try++) {
1207 read_lock(&binfmt_lock
);
1208 list_for_each_entry(fmt
, &formats
, lh
) {
1209 int (*fn
)(struct linux_binprm
*, struct pt_regs
*) = fmt
->load_binary
;
1212 if (!try_module_get(fmt
->module
))
1214 read_unlock(&binfmt_lock
);
1215 retval
= fn(bprm
, regs
);
1218 allow_write_access(bprm
->file
);
1222 current
->did_exec
= 1;
1223 proc_exec_connector(current
);
1226 read_lock(&binfmt_lock
);
1228 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
)
1231 read_unlock(&binfmt_lock
);
1235 read_unlock(&binfmt_lock
);
1236 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
) {
1240 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1241 if (printable(bprm
->buf
[0]) &&
1242 printable(bprm
->buf
[1]) &&
1243 printable(bprm
->buf
[2]) &&
1244 printable(bprm
->buf
[3]))
1245 break; /* -ENOEXEC */
1246 request_module("binfmt-%04x", *(unsigned short *)(&bprm
->buf
[2]));
1253 EXPORT_SYMBOL(search_binary_handler
);
1255 void free_bprm(struct linux_binprm
*bprm
)
1257 free_arg_pages(bprm
);
1262 * sys_execve() executes a new program.
1264 int do_execve(char * filename
,
1265 char __user
*__user
*argv
,
1266 char __user
*__user
*envp
,
1267 struct pt_regs
* regs
)
1269 struct linux_binprm
*bprm
;
1271 struct files_struct
*displaced
;
1274 retval
= unshare_files(&displaced
);
1279 bprm
= kzalloc(sizeof(*bprm
), GFP_KERNEL
);
1283 file
= open_exec(filename
);
1284 retval
= PTR_ERR(file
);
1291 bprm
->filename
= filename
;
1292 bprm
->interp
= filename
;
1294 retval
= bprm_mm_init(bprm
);
1298 bprm
->argc
= count(argv
, MAX_ARG_STRINGS
);
1299 if ((retval
= bprm
->argc
) < 0)
1302 bprm
->envc
= count(envp
, MAX_ARG_STRINGS
);
1303 if ((retval
= bprm
->envc
) < 0)
1306 retval
= security_bprm_alloc(bprm
);
1310 retval
= prepare_binprm(bprm
);
1314 retval
= copy_strings_kernel(1, &bprm
->filename
, bprm
);
1318 bprm
->exec
= bprm
->p
;
1319 retval
= copy_strings(bprm
->envc
, envp
, bprm
);
1323 retval
= copy_strings(bprm
->argc
, argv
, bprm
);
1327 current
->flags
&= ~PF_KTHREAD
;
1328 retval
= search_binary_handler(bprm
,regs
);
1330 /* execve success */
1331 security_bprm_free(bprm
);
1332 acct_update_integrals(current
);
1335 put_files_struct(displaced
);
1341 security_bprm_free(bprm
);
1349 allow_write_access(bprm
->file
);
1357 reset_files_struct(displaced
);
1362 int set_binfmt(struct linux_binfmt
*new)
1364 struct linux_binfmt
*old
= current
->binfmt
;
1367 if (!try_module_get(new->module
))
1370 current
->binfmt
= new;
1372 module_put(old
->module
);
1376 EXPORT_SYMBOL(set_binfmt
);
1378 /* format_corename will inspect the pattern parameter, and output a
1379 * name into corename, which must have space for at least
1380 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1382 static int format_corename(char *corename
, const char *pattern
, long signr
)
1384 const char *pat_ptr
= pattern
;
1385 char *out_ptr
= corename
;
1386 char *const out_end
= corename
+ CORENAME_MAX_SIZE
;
1388 int pid_in_pattern
= 0;
1391 if (*pattern
== '|')
1394 /* Repeat as long as we have more pattern to process and more output
1397 if (*pat_ptr
!= '%') {
1398 if (out_ptr
== out_end
)
1400 *out_ptr
++ = *pat_ptr
++;
1402 switch (*++pat_ptr
) {
1405 /* Double percent, output one percent */
1407 if (out_ptr
== out_end
)
1414 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1415 "%d", task_tgid_vnr(current
));
1416 if (rc
> out_end
- out_ptr
)
1422 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1423 "%d", current
->uid
);
1424 if (rc
> out_end
- out_ptr
)
1430 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1431 "%d", current
->gid
);
1432 if (rc
> out_end
- out_ptr
)
1436 /* signal that caused the coredump */
1438 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1440 if (rc
> out_end
- out_ptr
)
1444 /* UNIX time of coredump */
1447 do_gettimeofday(&tv
);
1448 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1450 if (rc
> out_end
- out_ptr
)
1457 down_read(&uts_sem
);
1458 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1459 "%s", utsname()->nodename
);
1461 if (rc
> out_end
- out_ptr
)
1467 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1468 "%s", current
->comm
);
1469 if (rc
> out_end
- out_ptr
)
1473 /* core limit size */
1475 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1476 "%lu", current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
);
1477 if (rc
> out_end
- out_ptr
)
1487 /* Backward compatibility with core_uses_pid:
1489 * If core_pattern does not include a %p (as is the default)
1490 * and core_uses_pid is set, then .%pid will be appended to
1491 * the filename. Do not do this for piped commands. */
1492 if (!ispipe
&& !pid_in_pattern
1493 && (core_uses_pid
|| atomic_read(¤t
->mm
->mm_users
) != 1)) {
1494 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1495 ".%d", task_tgid_vnr(current
));
1496 if (rc
> out_end
- out_ptr
)
1505 static int zap_process(struct task_struct
*start
)
1507 struct task_struct
*t
;
1510 start
->signal
->flags
= SIGNAL_GROUP_EXIT
;
1511 start
->signal
->group_stop_count
= 0;
1515 if (t
!= current
&& t
->mm
) {
1516 sigaddset(&t
->pending
.signal
, SIGKILL
);
1517 signal_wake_up(t
, 1);
1520 } while_each_thread(start
, t
);
1525 static inline int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
1526 struct core_state
*core_state
, int exit_code
)
1528 struct task_struct
*g
, *p
;
1529 unsigned long flags
;
1532 spin_lock_irq(&tsk
->sighand
->siglock
);
1533 if (!signal_group_exit(tsk
->signal
)) {
1534 mm
->core_state
= core_state
;
1535 tsk
->signal
->group_exit_code
= exit_code
;
1536 nr
= zap_process(tsk
);
1538 spin_unlock_irq(&tsk
->sighand
->siglock
);
1539 if (unlikely(nr
< 0))
1542 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
1545 * We should find and kill all tasks which use this mm, and we should
1546 * count them correctly into ->nr_threads. We don't take tasklist
1547 * lock, but this is safe wrt:
1550 * None of sub-threads can fork after zap_process(leader). All
1551 * processes which were created before this point should be
1552 * visible to zap_threads() because copy_process() adds the new
1553 * process to the tail of init_task.tasks list, and lock/unlock
1554 * of ->siglock provides a memory barrier.
1557 * The caller holds mm->mmap_sem. This means that the task which
1558 * uses this mm can't pass exit_mm(), so it can't exit or clear
1562 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1563 * we must see either old or new leader, this does not matter.
1564 * However, it can change p->sighand, so lock_task_sighand(p)
1565 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1568 * Note also that "g" can be the old leader with ->mm == NULL
1569 * and already unhashed and thus removed from ->thread_group.
1570 * This is OK, __unhash_process()->list_del_rcu() does not
1571 * clear the ->next pointer, we will find the new leader via
1575 for_each_process(g
) {
1576 if (g
== tsk
->group_leader
)
1578 if (g
->flags
& PF_KTHREAD
)
1583 if (unlikely(p
->mm
== mm
)) {
1584 lock_task_sighand(p
, &flags
);
1585 nr
+= zap_process(p
);
1586 unlock_task_sighand(p
, &flags
);
1590 } while_each_thread(g
, p
);
1594 atomic_set(&core_state
->nr_threads
, nr
);
1598 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
1600 struct task_struct
*tsk
= current
;
1601 struct mm_struct
*mm
= tsk
->mm
;
1602 struct completion
*vfork_done
;
1605 init_completion(&core_state
->startup
);
1606 core_state
->dumper
.task
= tsk
;
1607 core_state
->dumper
.next
= NULL
;
1608 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
1609 up_write(&mm
->mmap_sem
);
1611 if (unlikely(core_waiters
< 0))
1615 * Make sure nobody is waiting for us to release the VM,
1616 * otherwise we can deadlock when we wait on each other
1618 vfork_done
= tsk
->vfork_done
;
1620 tsk
->vfork_done
= NULL
;
1621 complete(vfork_done
);
1625 wait_for_completion(&core_state
->startup
);
1627 return core_waiters
;
1630 static void coredump_finish(struct mm_struct
*mm
)
1632 struct core_thread
*curr
, *next
;
1633 struct task_struct
*task
;
1635 next
= mm
->core_state
->dumper
.next
;
1636 while ((curr
= next
) != NULL
) {
1640 * see exit_mm(), curr->task must not see
1641 * ->task == NULL before we read ->next.
1645 wake_up_process(task
);
1648 mm
->core_state
= NULL
;
1652 * set_dumpable converts traditional three-value dumpable to two flags and
1653 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1654 * these bits are not changed atomically. So get_dumpable can observe the
1655 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1656 * return either old dumpable or new one by paying attention to the order of
1657 * modifying the bits.
1659 * dumpable | mm->flags (binary)
1660 * old new | initial interim final
1661 * ---------+-----------------------
1669 * (*) get_dumpable regards interim value of 10 as 11.
1671 void set_dumpable(struct mm_struct
*mm
, int value
)
1675 clear_bit(MMF_DUMPABLE
, &mm
->flags
);
1677 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1680 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1682 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1685 set_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1687 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1692 int get_dumpable(struct mm_struct
*mm
)
1696 ret
= mm
->flags
& 0x3;
1697 return (ret
>= 2) ? 2 : ret
;
1700 int do_coredump(long signr
, int exit_code
, struct pt_regs
* regs
)
1702 struct core_state core_state
;
1703 char corename
[CORENAME_MAX_SIZE
+ 1];
1704 struct mm_struct
*mm
= current
->mm
;
1705 struct linux_binfmt
* binfmt
;
1706 struct inode
* inode
;
1709 int fsuid
= current
->fsuid
;
1712 unsigned long core_limit
= current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
;
1713 char **helper_argv
= NULL
;
1714 int helper_argc
= 0;
1717 audit_core_dumps(signr
);
1719 binfmt
= current
->binfmt
;
1720 if (!binfmt
|| !binfmt
->core_dump
)
1722 down_write(&mm
->mmap_sem
);
1724 * If another thread got here first, or we are not dumpable, bail out.
1726 if (mm
->core_state
|| !get_dumpable(mm
)) {
1727 up_write(&mm
->mmap_sem
);
1732 * We cannot trust fsuid as being the "true" uid of the
1733 * process nor do we know its entire history. We only know it
1734 * was tainted so we dump it as root in mode 2.
1736 if (get_dumpable(mm
) == 2) { /* Setuid core dump mode */
1737 flag
= O_EXCL
; /* Stop rewrite attacks */
1738 current
->fsuid
= 0; /* Dump root private */
1741 retval
= coredump_wait(exit_code
, &core_state
);
1746 * Clear any false indication of pending signals that might
1747 * be seen by the filesystem code called to write the core file.
1749 clear_thread_flag(TIF_SIGPENDING
);
1752 * lock_kernel() because format_corename() is controlled by sysctl, which
1753 * uses lock_kernel()
1756 ispipe
= format_corename(corename
, core_pattern
, signr
);
1759 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1760 * to a pipe. Since we're not writing directly to the filesystem
1761 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1762 * created unless the pipe reader choses to write out the core file
1763 * at which point file size limits and permissions will be imposed
1764 * as it does with any other process
1766 if ((!ispipe
) && (core_limit
< binfmt
->min_coredump
))
1770 helper_argv
= argv_split(GFP_KERNEL
, corename
+1, &helper_argc
);
1771 /* Terminate the string before the first option */
1772 delimit
= strchr(corename
, ' ');
1775 delimit
= strrchr(helper_argv
[0], '/');
1779 delimit
= helper_argv
[0];
1780 if (!strcmp(delimit
, current
->comm
)) {
1781 printk(KERN_NOTICE
"Recursive core dump detected, "
1786 core_limit
= RLIM_INFINITY
;
1788 /* SIGPIPE can happen, but it's just never processed */
1789 if (call_usermodehelper_pipe(corename
+1, helper_argv
, NULL
,
1791 printk(KERN_INFO
"Core dump to %s pipe failed\n",
1796 file
= filp_open(corename
,
1797 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
1801 inode
= file
->f_path
.dentry
->d_inode
;
1802 if (inode
->i_nlink
> 1)
1803 goto close_fail
; /* multiple links - don't dump */
1804 if (!ispipe
&& d_unhashed(file
->f_path
.dentry
))
1807 /* AK: actually i see no reason to not allow this for named pipes etc.,
1808 but keep the previous behaviour for now. */
1809 if (!ispipe
&& !S_ISREG(inode
->i_mode
))
1812 * Dont allow local users get cute and trick others to coredump
1813 * into their pre-created files:
1815 if (inode
->i_uid
!= current
->fsuid
)
1819 if (!file
->f_op
->write
)
1821 if (!ispipe
&& do_truncate(file
->f_path
.dentry
, 0, 0, file
) != 0)
1824 retval
= binfmt
->core_dump(signr
, regs
, file
, core_limit
);
1827 current
->signal
->group_exit_code
|= 0x80;
1829 filp_close(file
, NULL
);
1832 argv_free(helper_argv
);
1834 current
->fsuid
= fsuid
;
1835 coredump_finish(mm
);