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/perf_counter.h>
37 #include <linux/highmem.h>
38 #include <linux/spinlock.h>
39 #include <linux/key.h>
40 #include <linux/personality.h>
41 #include <linux/binfmts.h>
42 #include <linux/utsname.h>
43 #include <linux/pid_namespace.h>
44 #include <linux/module.h>
45 #include <linux/namei.h>
46 #include <linux/proc_fs.h>
47 #include <linux/mount.h>
48 #include <linux/security.h>
49 #include <linux/ima.h>
50 #include <linux/syscalls.h>
51 #include <linux/tsacct_kern.h>
52 #include <linux/cn_proc.h>
53 #include <linux/audit.h>
54 #include <linux/tracehook.h>
55 #include <linux/kmod.h>
56 #include <linux/fsnotify.h>
57 #include <linux/fs_struct.h>
59 #include <asm/uaccess.h>
60 #include <asm/mmu_context.h>
65 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
66 int suid_dumpable
= 0;
68 /* The maximal length of core_pattern is also specified in sysctl.c */
70 static LIST_HEAD(formats
);
71 static DEFINE_RWLOCK(binfmt_lock
);
73 int register_binfmt(struct linux_binfmt
* fmt
)
77 write_lock(&binfmt_lock
);
78 list_add(&fmt
->lh
, &formats
);
79 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
)
109 char *tmp
= getname(library
);
110 int error
= PTR_ERR(tmp
);
113 error
= path_lookup_open(AT_FDCWD
, tmp
,
115 FMODE_READ
|FMODE_EXEC
);
122 if (!S_ISREG(nd
.path
.dentry
->d_inode
->i_mode
))
126 if (nd
.path
.mnt
->mnt_flags
& MNT_NOEXEC
)
129 error
= inode_permission(nd
.path
.dentry
->d_inode
,
130 MAY_READ
| MAY_EXEC
| MAY_OPEN
);
133 error
= ima_path_check(&nd
.path
, MAY_READ
| MAY_EXEC
| MAY_OPEN
);
137 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
138 error
= PTR_ERR(file
);
142 fsnotify_open(file
->f_path
.dentry
);
146 struct linux_binfmt
* fmt
;
148 read_lock(&binfmt_lock
);
149 list_for_each_entry(fmt
, &formats
, lh
) {
150 if (!fmt
->load_shlib
)
152 if (!try_module_get(fmt
->module
))
154 read_unlock(&binfmt_lock
);
155 error
= fmt
->load_shlib(file
);
156 read_lock(&binfmt_lock
);
158 if (error
!= -ENOEXEC
)
161 read_unlock(&binfmt_lock
);
167 release_open_intent(&nd
);
174 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
180 #ifdef CONFIG_STACK_GROWSUP
182 ret
= expand_stack_downwards(bprm
->vma
, pos
);
187 ret
= get_user_pages(current
, bprm
->mm
, pos
,
188 1, write
, 1, &page
, NULL
);
193 unsigned long size
= bprm
->vma
->vm_end
- bprm
->vma
->vm_start
;
197 * We've historically supported up to 32 pages (ARG_MAX)
198 * of argument strings even with small stacks
204 * Limit to 1/4-th the stack size for the argv+env strings.
206 * - the remaining binfmt code will not run out of stack space,
207 * - the program will have a reasonable amount of stack left
210 rlim
= current
->signal
->rlim
;
211 if (size
> rlim
[RLIMIT_STACK
].rlim_cur
/ 4) {
220 static void put_arg_page(struct page
*page
)
225 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
229 static void free_arg_pages(struct linux_binprm
*bprm
)
233 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
236 flush_cache_page(bprm
->vma
, pos
, page_to_pfn(page
));
239 static int __bprm_mm_init(struct linux_binprm
*bprm
)
242 struct vm_area_struct
*vma
= NULL
;
243 struct mm_struct
*mm
= bprm
->mm
;
245 bprm
->vma
= vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
249 down_write(&mm
->mmap_sem
);
253 * Place the stack at the largest stack address the architecture
254 * supports. Later, we'll move this to an appropriate place. We don't
255 * use STACK_TOP because that can depend on attributes which aren't
258 vma
->vm_end
= STACK_TOP_MAX
;
259 vma
->vm_start
= vma
->vm_end
- PAGE_SIZE
;
260 vma
->vm_flags
= VM_STACK_FLAGS
;
261 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
262 err
= insert_vm_struct(mm
, vma
);
266 mm
->stack_vm
= mm
->total_vm
= 1;
267 up_write(&mm
->mmap_sem
);
268 bprm
->p
= vma
->vm_end
- sizeof(void *);
271 up_write(&mm
->mmap_sem
);
273 kmem_cache_free(vm_area_cachep
, vma
);
277 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
279 return len
<= MAX_ARG_STRLEN
;
284 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
289 page
= bprm
->page
[pos
/ PAGE_SIZE
];
290 if (!page
&& write
) {
291 page
= alloc_page(GFP_HIGHUSER
|__GFP_ZERO
);
294 bprm
->page
[pos
/ PAGE_SIZE
] = page
;
300 static void put_arg_page(struct page
*page
)
304 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
307 __free_page(bprm
->page
[i
]);
308 bprm
->page
[i
] = NULL
;
312 static void free_arg_pages(struct linux_binprm
*bprm
)
316 for (i
= 0; i
< MAX_ARG_PAGES
; i
++)
317 free_arg_page(bprm
, i
);
320 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
325 static int __bprm_mm_init(struct linux_binprm
*bprm
)
327 bprm
->p
= PAGE_SIZE
* MAX_ARG_PAGES
- sizeof(void *);
331 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
333 return len
<= bprm
->p
;
336 #endif /* CONFIG_MMU */
339 * Create a new mm_struct and populate it with a temporary stack
340 * vm_area_struct. We don't have enough context at this point to set the stack
341 * flags, permissions, and offset, so we use temporary values. We'll update
342 * them later in setup_arg_pages().
344 int bprm_mm_init(struct linux_binprm
*bprm
)
347 struct mm_struct
*mm
= NULL
;
349 bprm
->mm
= mm
= mm_alloc();
354 err
= init_new_context(current
, mm
);
358 err
= __bprm_mm_init(bprm
);
374 * count() counts the number of strings in array ARGV.
376 static int count(char __user
* __user
* argv
, int max
)
384 if (get_user(p
, argv
))
398 * 'copy_strings()' copies argument/environment strings from the old
399 * processes's memory to the new process's stack. The call to get_user_pages()
400 * ensures the destination page is created and not swapped out.
402 static int copy_strings(int argc
, char __user
* __user
* argv
,
403 struct linux_binprm
*bprm
)
405 struct page
*kmapped_page
= NULL
;
407 unsigned long kpos
= 0;
415 if (get_user(str
, argv
+argc
) ||
416 !(len
= strnlen_user(str
, MAX_ARG_STRLEN
))) {
421 if (!valid_arg_len(bprm
, len
)) {
426 /* We're going to work our way backwords. */
432 int offset
, bytes_to_copy
;
434 offset
= pos
% PAGE_SIZE
;
438 bytes_to_copy
= offset
;
439 if (bytes_to_copy
> len
)
442 offset
-= bytes_to_copy
;
443 pos
-= bytes_to_copy
;
444 str
-= bytes_to_copy
;
445 len
-= bytes_to_copy
;
447 if (!kmapped_page
|| kpos
!= (pos
& PAGE_MASK
)) {
450 page
= get_arg_page(bprm
, pos
, 1);
457 flush_kernel_dcache_page(kmapped_page
);
458 kunmap(kmapped_page
);
459 put_arg_page(kmapped_page
);
462 kaddr
= kmap(kmapped_page
);
463 kpos
= pos
& PAGE_MASK
;
464 flush_arg_page(bprm
, kpos
, kmapped_page
);
466 if (copy_from_user(kaddr
+offset
, str
, bytes_to_copy
)) {
475 flush_kernel_dcache_page(kmapped_page
);
476 kunmap(kmapped_page
);
477 put_arg_page(kmapped_page
);
483 * Like copy_strings, but get argv and its values from kernel memory.
485 int copy_strings_kernel(int argc
,char ** argv
, struct linux_binprm
*bprm
)
488 mm_segment_t oldfs
= get_fs();
490 r
= copy_strings(argc
, (char __user
* __user
*)argv
, bprm
);
494 EXPORT_SYMBOL(copy_strings_kernel
);
499 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
500 * the binfmt code determines where the new stack should reside, we shift it to
501 * its final location. The process proceeds as follows:
503 * 1) Use shift to calculate the new vma endpoints.
504 * 2) Extend vma to cover both the old and new ranges. This ensures the
505 * arguments passed to subsequent functions are consistent.
506 * 3) Move vma's page tables to the new range.
507 * 4) Free up any cleared pgd range.
508 * 5) Shrink the vma to cover only the new range.
510 static int shift_arg_pages(struct vm_area_struct
*vma
, unsigned long shift
)
512 struct mm_struct
*mm
= vma
->vm_mm
;
513 unsigned long old_start
= vma
->vm_start
;
514 unsigned long old_end
= vma
->vm_end
;
515 unsigned long length
= old_end
- old_start
;
516 unsigned long new_start
= old_start
- shift
;
517 unsigned long new_end
= old_end
- shift
;
518 struct mmu_gather
*tlb
;
520 BUG_ON(new_start
> new_end
);
523 * ensure there are no vmas between where we want to go
526 if (vma
!= find_vma(mm
, new_start
))
530 * cover the whole range: [new_start, old_end)
532 vma_adjust(vma
, new_start
, old_end
, vma
->vm_pgoff
, NULL
);
535 * move the page tables downwards, on failure we rely on
536 * process cleanup to remove whatever mess we made.
538 if (length
!= move_page_tables(vma
, old_start
,
539 vma
, new_start
, length
))
543 tlb
= tlb_gather_mmu(mm
, 0);
544 if (new_end
> old_start
) {
546 * when the old and new regions overlap clear from new_end.
548 free_pgd_range(tlb
, new_end
, old_end
, new_end
,
549 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
552 * otherwise, clean from old_start; this is done to not touch
553 * the address space in [new_end, old_start) some architectures
554 * have constraints on va-space that make this illegal (IA64) -
555 * for the others its just a little faster.
557 free_pgd_range(tlb
, old_start
, old_end
, new_end
,
558 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
560 tlb_finish_mmu(tlb
, new_end
, old_end
);
563 * shrink the vma to just the new range.
565 vma_adjust(vma
, new_start
, new_end
, vma
->vm_pgoff
, NULL
);
570 #define EXTRA_STACK_VM_PAGES 20 /* random */
573 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
574 * the stack is optionally relocated, and some extra space is added.
576 int setup_arg_pages(struct linux_binprm
*bprm
,
577 unsigned long stack_top
,
578 int executable_stack
)
581 unsigned long stack_shift
;
582 struct mm_struct
*mm
= current
->mm
;
583 struct vm_area_struct
*vma
= bprm
->vma
;
584 struct vm_area_struct
*prev
= NULL
;
585 unsigned long vm_flags
;
586 unsigned long stack_base
;
588 #ifdef CONFIG_STACK_GROWSUP
589 /* Limit stack size to 1GB */
590 stack_base
= current
->signal
->rlim
[RLIMIT_STACK
].rlim_max
;
591 if (stack_base
> (1 << 30))
592 stack_base
= 1 << 30;
594 /* Make sure we didn't let the argument array grow too large. */
595 if (vma
->vm_end
- vma
->vm_start
> stack_base
)
598 stack_base
= PAGE_ALIGN(stack_top
- stack_base
);
600 stack_shift
= vma
->vm_start
- stack_base
;
601 mm
->arg_start
= bprm
->p
- stack_shift
;
602 bprm
->p
= vma
->vm_end
- stack_shift
;
604 stack_top
= arch_align_stack(stack_top
);
605 stack_top
= PAGE_ALIGN(stack_top
);
606 stack_shift
= vma
->vm_end
- stack_top
;
608 bprm
->p
-= stack_shift
;
609 mm
->arg_start
= bprm
->p
;
613 bprm
->loader
-= stack_shift
;
614 bprm
->exec
-= stack_shift
;
616 down_write(&mm
->mmap_sem
);
617 vm_flags
= VM_STACK_FLAGS
;
620 * Adjust stack execute permissions; explicitly enable for
621 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
622 * (arch default) otherwise.
624 if (unlikely(executable_stack
== EXSTACK_ENABLE_X
))
626 else if (executable_stack
== EXSTACK_DISABLE_X
)
627 vm_flags
&= ~VM_EXEC
;
628 vm_flags
|= mm
->def_flags
;
630 ret
= mprotect_fixup(vma
, &prev
, vma
->vm_start
, vma
->vm_end
,
636 /* Move stack pages down in memory. */
638 ret
= shift_arg_pages(vma
, stack_shift
);
640 up_write(&mm
->mmap_sem
);
645 #ifdef CONFIG_STACK_GROWSUP
646 stack_base
= vma
->vm_end
+ EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
648 stack_base
= vma
->vm_start
- EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
650 ret
= expand_stack(vma
, stack_base
);
655 up_write(&mm
->mmap_sem
);
658 EXPORT_SYMBOL(setup_arg_pages
);
660 #endif /* CONFIG_MMU */
662 struct file
*open_exec(const char *name
)
668 err
= path_lookup_open(AT_FDCWD
, name
, LOOKUP_FOLLOW
, &nd
,
669 FMODE_READ
|FMODE_EXEC
);
674 if (!S_ISREG(nd
.path
.dentry
->d_inode
->i_mode
))
677 if (nd
.path
.mnt
->mnt_flags
& MNT_NOEXEC
)
680 err
= inode_permission(nd
.path
.dentry
->d_inode
, MAY_EXEC
| MAY_OPEN
);
683 err
= ima_path_check(&nd
.path
, MAY_EXEC
| MAY_OPEN
);
687 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
691 fsnotify_open(file
->f_path
.dentry
);
693 err
= deny_write_access(file
);
702 release_open_intent(&nd
);
707 EXPORT_SYMBOL(open_exec
);
709 int kernel_read(struct file
*file
, unsigned long offset
,
710 char *addr
, unsigned long count
)
718 /* The cast to a user pointer is valid due to the set_fs() */
719 result
= vfs_read(file
, (void __user
*)addr
, count
, &pos
);
724 EXPORT_SYMBOL(kernel_read
);
726 static int exec_mmap(struct mm_struct
*mm
)
728 struct task_struct
*tsk
;
729 struct mm_struct
* old_mm
, *active_mm
;
731 /* Notify parent that we're no longer interested in the old VM */
733 old_mm
= current
->mm
;
734 mm_release(tsk
, old_mm
);
738 * Make sure that if there is a core dump in progress
739 * for the old mm, we get out and die instead of going
740 * through with the exec. We must hold mmap_sem around
741 * checking core_state and changing tsk->mm.
743 down_read(&old_mm
->mmap_sem
);
744 if (unlikely(old_mm
->core_state
)) {
745 up_read(&old_mm
->mmap_sem
);
750 active_mm
= tsk
->active_mm
;
753 activate_mm(active_mm
, mm
);
755 arch_pick_mmap_layout(mm
);
757 up_read(&old_mm
->mmap_sem
);
758 BUG_ON(active_mm
!= old_mm
);
759 mm_update_next_owner(old_mm
);
768 * This function makes sure the current process has its own signal table,
769 * so that flush_signal_handlers can later reset the handlers without
770 * disturbing other processes. (Other processes might share the signal
771 * table via the CLONE_SIGHAND option to clone().)
773 static int de_thread(struct task_struct
*tsk
)
775 struct signal_struct
*sig
= tsk
->signal
;
776 struct sighand_struct
*oldsighand
= tsk
->sighand
;
777 spinlock_t
*lock
= &oldsighand
->siglock
;
780 if (thread_group_empty(tsk
))
781 goto no_thread_group
;
784 * Kill all other threads in the thread group.
787 if (signal_group_exit(sig
)) {
789 * Another group action in progress, just
790 * return so that the signal is processed.
792 spin_unlock_irq(lock
);
795 sig
->group_exit_task
= tsk
;
796 zap_other_threads(tsk
);
798 /* Account for the thread group leader hanging around: */
799 count
= thread_group_leader(tsk
) ? 1 : 2;
800 sig
->notify_count
= count
;
801 while (atomic_read(&sig
->count
) > count
) {
802 __set_current_state(TASK_UNINTERRUPTIBLE
);
803 spin_unlock_irq(lock
);
807 spin_unlock_irq(lock
);
810 * At this point all other threads have exited, all we have to
811 * do is to wait for the thread group leader to become inactive,
812 * and to assume its PID:
814 if (!thread_group_leader(tsk
)) {
815 struct task_struct
*leader
= tsk
->group_leader
;
817 sig
->notify_count
= -1; /* for exit_notify() */
819 write_lock_irq(&tasklist_lock
);
820 if (likely(leader
->exit_state
))
822 __set_current_state(TASK_UNINTERRUPTIBLE
);
823 write_unlock_irq(&tasklist_lock
);
828 * The only record we have of the real-time age of a
829 * process, regardless of execs it's done, is start_time.
830 * All the past CPU time is accumulated in signal_struct
831 * from sister threads now dead. But in this non-leader
832 * exec, nothing survives from the original leader thread,
833 * whose birth marks the true age of this process now.
834 * When we take on its identity by switching to its PID, we
835 * also take its birthdate (always earlier than our own).
837 tsk
->start_time
= leader
->start_time
;
839 BUG_ON(!same_thread_group(leader
, tsk
));
840 BUG_ON(has_group_leader_pid(tsk
));
842 * An exec() starts a new thread group with the
843 * TGID of the previous thread group. Rehash the
844 * two threads with a switched PID, and release
845 * the former thread group leader:
848 /* Become a process group leader with the old leader's pid.
849 * The old leader becomes a thread of the this thread group.
850 * Note: The old leader also uses this pid until release_task
851 * is called. Odd but simple and correct.
853 detach_pid(tsk
, PIDTYPE_PID
);
854 tsk
->pid
= leader
->pid
;
855 attach_pid(tsk
, PIDTYPE_PID
, task_pid(leader
));
856 transfer_pid(leader
, tsk
, PIDTYPE_PGID
);
857 transfer_pid(leader
, tsk
, PIDTYPE_SID
);
858 list_replace_rcu(&leader
->tasks
, &tsk
->tasks
);
860 tsk
->group_leader
= tsk
;
861 leader
->group_leader
= tsk
;
863 tsk
->exit_signal
= SIGCHLD
;
865 BUG_ON(leader
->exit_state
!= EXIT_ZOMBIE
);
866 leader
->exit_state
= EXIT_DEAD
;
867 write_unlock_irq(&tasklist_lock
);
869 release_task(leader
);
872 sig
->group_exit_task
= NULL
;
873 sig
->notify_count
= 0;
877 flush_itimer_signals();
879 if (atomic_read(&oldsighand
->count
) != 1) {
880 struct sighand_struct
*newsighand
;
882 * This ->sighand is shared with the CLONE_SIGHAND
883 * but not CLONE_THREAD task, switch to the new one.
885 newsighand
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
889 atomic_set(&newsighand
->count
, 1);
890 memcpy(newsighand
->action
, oldsighand
->action
,
891 sizeof(newsighand
->action
));
893 write_lock_irq(&tasklist_lock
);
894 spin_lock(&oldsighand
->siglock
);
895 rcu_assign_pointer(tsk
->sighand
, newsighand
);
896 spin_unlock(&oldsighand
->siglock
);
897 write_unlock_irq(&tasklist_lock
);
899 __cleanup_sighand(oldsighand
);
902 BUG_ON(!thread_group_leader(tsk
));
907 * These functions flushes out all traces of the currently running executable
908 * so that a new one can be started
910 static void flush_old_files(struct files_struct
* files
)
915 spin_lock(&files
->file_lock
);
917 unsigned long set
, i
;
921 fdt
= files_fdtable(files
);
922 if (i
>= fdt
->max_fds
)
924 set
= fdt
->close_on_exec
->fds_bits
[j
];
927 fdt
->close_on_exec
->fds_bits
[j
] = 0;
928 spin_unlock(&files
->file_lock
);
929 for ( ; set
; i
++,set
>>= 1) {
934 spin_lock(&files
->file_lock
);
937 spin_unlock(&files
->file_lock
);
940 char *get_task_comm(char *buf
, struct task_struct
*tsk
)
942 /* buf must be at least sizeof(tsk->comm) in size */
944 strncpy(buf
, tsk
->comm
, sizeof(tsk
->comm
));
949 void set_task_comm(struct task_struct
*tsk
, char *buf
)
952 strlcpy(tsk
->comm
, buf
, sizeof(tsk
->comm
));
954 perf_counter_comm(tsk
);
957 int flush_old_exec(struct linux_binprm
* bprm
)
961 char tcomm
[sizeof(current
->comm
)];
964 * Make sure we have a private signal table and that
965 * we are unassociated from the previous thread group.
967 retval
= de_thread(current
);
971 set_mm_exe_file(bprm
->mm
, bprm
->file
);
974 * Release all of the old mmap stuff
976 retval
= exec_mmap(bprm
->mm
);
980 bprm
->mm
= NULL
; /* We're using it now */
982 /* This is the point of no return */
983 current
->sas_ss_sp
= current
->sas_ss_size
= 0;
985 if (current_euid() == current_uid() && current_egid() == current_gid())
986 set_dumpable(current
->mm
, 1);
988 set_dumpable(current
->mm
, suid_dumpable
);
990 name
= bprm
->filename
;
992 /* Copies the binary name from after last slash */
993 for (i
=0; (ch
= *(name
++)) != '\0';) {
995 i
= 0; /* overwrite what we wrote */
997 if (i
< (sizeof(tcomm
) - 1))
1001 set_task_comm(current
, tcomm
);
1003 current
->flags
&= ~PF_RANDOMIZE
;
1006 /* Set the new mm task size. We have to do that late because it may
1007 * depend on TIF_32BIT which is only updated in flush_thread() on
1008 * some architectures like powerpc
1010 current
->mm
->task_size
= TASK_SIZE
;
1012 /* install the new credentials */
1013 if (bprm
->cred
->uid
!= current_euid() ||
1014 bprm
->cred
->gid
!= current_egid()) {
1015 current
->pdeath_signal
= 0;
1016 } else if (file_permission(bprm
->file
, MAY_READ
) ||
1017 bprm
->interp_flags
& BINPRM_FLAGS_ENFORCE_NONDUMP
) {
1018 set_dumpable(current
->mm
, suid_dumpable
);
1021 current
->personality
&= ~bprm
->per_clear
;
1024 * Flush performance counters when crossing a
1027 if (!get_dumpable(current
->mm
))
1028 perf_counter_exit_task(current
);
1030 /* An exec changes our domain. We are no longer part of the thread
1033 current
->self_exec_id
++;
1035 flush_signal_handlers(current
, 0);
1036 flush_old_files(current
->files
);
1044 EXPORT_SYMBOL(flush_old_exec
);
1047 * install the new credentials for this executable
1049 void install_exec_creds(struct linux_binprm
*bprm
)
1051 security_bprm_committing_creds(bprm
);
1053 commit_creds(bprm
->cred
);
1056 /* cred_exec_mutex must be held at least to this point to prevent
1057 * ptrace_attach() from altering our determination of the task's
1058 * credentials; any time after this it may be unlocked */
1060 security_bprm_committed_creds(bprm
);
1062 EXPORT_SYMBOL(install_exec_creds
);
1065 * determine how safe it is to execute the proposed program
1066 * - the caller must hold current->cred_exec_mutex to protect against
1069 int check_unsafe_exec(struct linux_binprm
*bprm
)
1071 struct task_struct
*p
= current
, *t
;
1075 bprm
->unsafe
= tracehook_unsafe_exec(p
);
1078 write_lock(&p
->fs
->lock
);
1080 for (t
= next_thread(p
); t
!= p
; t
= next_thread(t
)) {
1086 if (p
->fs
->users
> n_fs
) {
1087 bprm
->unsafe
|= LSM_UNSAFE_SHARE
;
1090 if (!p
->fs
->in_exec
) {
1095 write_unlock(&p
->fs
->lock
);
1101 * Fill the binprm structure from the inode.
1102 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1104 * This may be called multiple times for binary chains (scripts for example).
1106 int prepare_binprm(struct linux_binprm
*bprm
)
1109 struct inode
* inode
= bprm
->file
->f_path
.dentry
->d_inode
;
1112 mode
= inode
->i_mode
;
1113 if (bprm
->file
->f_op
== NULL
)
1116 /* clear any previous set[ug]id data from a previous binary */
1117 bprm
->cred
->euid
= current_euid();
1118 bprm
->cred
->egid
= current_egid();
1120 if (!(bprm
->file
->f_path
.mnt
->mnt_flags
& MNT_NOSUID
)) {
1122 if (mode
& S_ISUID
) {
1123 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1124 bprm
->cred
->euid
= inode
->i_uid
;
1129 * If setgid is set but no group execute bit then this
1130 * is a candidate for mandatory locking, not a setgid
1133 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
1134 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1135 bprm
->cred
->egid
= inode
->i_gid
;
1139 /* fill in binprm security blob */
1140 retval
= security_bprm_set_creds(bprm
);
1143 bprm
->cred_prepared
= 1;
1145 memset(bprm
->buf
, 0, BINPRM_BUF_SIZE
);
1146 return kernel_read(bprm
->file
, 0, bprm
->buf
, BINPRM_BUF_SIZE
);
1149 EXPORT_SYMBOL(prepare_binprm
);
1152 * Arguments are '\0' separated strings found at the location bprm->p
1153 * points to; chop off the first by relocating brpm->p to right after
1154 * the first '\0' encountered.
1156 int remove_arg_zero(struct linux_binprm
*bprm
)
1159 unsigned long offset
;
1167 offset
= bprm
->p
& ~PAGE_MASK
;
1168 page
= get_arg_page(bprm
, bprm
->p
, 0);
1173 kaddr
= kmap_atomic(page
, KM_USER0
);
1175 for (; offset
< PAGE_SIZE
&& kaddr
[offset
];
1176 offset
++, bprm
->p
++)
1179 kunmap_atomic(kaddr
, KM_USER0
);
1182 if (offset
== PAGE_SIZE
)
1183 free_arg_page(bprm
, (bprm
->p
>> PAGE_SHIFT
) - 1);
1184 } while (offset
== PAGE_SIZE
);
1193 EXPORT_SYMBOL(remove_arg_zero
);
1196 * cycle the list of binary formats handler, until one recognizes the image
1198 int search_binary_handler(struct linux_binprm
*bprm
,struct pt_regs
*regs
)
1200 unsigned int depth
= bprm
->recursion_depth
;
1202 struct linux_binfmt
*fmt
;
1204 retval
= security_bprm_check(bprm
);
1207 retval
= ima_bprm_check(bprm
);
1211 /* kernel module loader fixup */
1212 /* so we don't try to load run modprobe in kernel space. */
1215 retval
= audit_bprm(bprm
);
1220 for (try=0; try<2; try++) {
1221 read_lock(&binfmt_lock
);
1222 list_for_each_entry(fmt
, &formats
, lh
) {
1223 int (*fn
)(struct linux_binprm
*, struct pt_regs
*) = fmt
->load_binary
;
1226 if (!try_module_get(fmt
->module
))
1228 read_unlock(&binfmt_lock
);
1229 retval
= fn(bprm
, regs
);
1231 * Restore the depth counter to its starting value
1232 * in this call, so we don't have to rely on every
1233 * load_binary function to restore it on return.
1235 bprm
->recursion_depth
= depth
;
1238 tracehook_report_exec(fmt
, bprm
, regs
);
1240 allow_write_access(bprm
->file
);
1244 current
->did_exec
= 1;
1245 proc_exec_connector(current
);
1248 read_lock(&binfmt_lock
);
1250 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
)
1253 read_unlock(&binfmt_lock
);
1257 read_unlock(&binfmt_lock
);
1258 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
) {
1260 #ifdef CONFIG_MODULES
1262 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1263 if (printable(bprm
->buf
[0]) &&
1264 printable(bprm
->buf
[1]) &&
1265 printable(bprm
->buf
[2]) &&
1266 printable(bprm
->buf
[3]))
1267 break; /* -ENOEXEC */
1268 request_module("binfmt-%04x", *(unsigned short *)(&bprm
->buf
[2]));
1275 EXPORT_SYMBOL(search_binary_handler
);
1277 void free_bprm(struct linux_binprm
*bprm
)
1279 free_arg_pages(bprm
);
1281 abort_creds(bprm
->cred
);
1286 * sys_execve() executes a new program.
1288 int do_execve(char * filename
,
1289 char __user
*__user
*argv
,
1290 char __user
*__user
*envp
,
1291 struct pt_regs
* regs
)
1293 struct linux_binprm
*bprm
;
1295 struct files_struct
*displaced
;
1299 retval
= unshare_files(&displaced
);
1304 bprm
= kzalloc(sizeof(*bprm
), GFP_KERNEL
);
1308 retval
= mutex_lock_interruptible(¤t
->cred_exec_mutex
);
1311 current
->in_execve
= 1;
1314 bprm
->cred
= prepare_exec_creds();
1318 retval
= check_unsafe_exec(bprm
);
1321 clear_in_exec
= retval
;
1323 file
= open_exec(filename
);
1324 retval
= PTR_ERR(file
);
1331 bprm
->filename
= filename
;
1332 bprm
->interp
= filename
;
1334 retval
= bprm_mm_init(bprm
);
1338 bprm
->argc
= count(argv
, MAX_ARG_STRINGS
);
1339 if ((retval
= bprm
->argc
) < 0)
1342 bprm
->envc
= count(envp
, MAX_ARG_STRINGS
);
1343 if ((retval
= bprm
->envc
) < 0)
1346 retval
= prepare_binprm(bprm
);
1350 retval
= copy_strings_kernel(1, &bprm
->filename
, bprm
);
1354 bprm
->exec
= bprm
->p
;
1355 retval
= copy_strings(bprm
->envc
, envp
, bprm
);
1359 retval
= copy_strings(bprm
->argc
, argv
, bprm
);
1363 current
->flags
&= ~PF_KTHREAD
;
1364 retval
= search_binary_handler(bprm
,regs
);
1368 /* execve succeeded */
1369 current
->fs
->in_exec
= 0;
1370 current
->in_execve
= 0;
1371 mutex_unlock(¤t
->cred_exec_mutex
);
1372 acct_update_integrals(current
);
1375 put_files_struct(displaced
);
1384 allow_write_access(bprm
->file
);
1390 current
->fs
->in_exec
= 0;
1393 current
->in_execve
= 0;
1394 mutex_unlock(¤t
->cred_exec_mutex
);
1401 reset_files_struct(displaced
);
1406 int set_binfmt(struct linux_binfmt
*new)
1408 struct linux_binfmt
*old
= current
->binfmt
;
1411 if (!try_module_get(new->module
))
1414 current
->binfmt
= new;
1416 module_put(old
->module
);
1420 EXPORT_SYMBOL(set_binfmt
);
1422 /* format_corename will inspect the pattern parameter, and output a
1423 * name into corename, which must have space for at least
1424 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1426 static int format_corename(char *corename
, long signr
)
1428 const struct cred
*cred
= current_cred();
1429 const char *pat_ptr
= core_pattern
;
1430 int ispipe
= (*pat_ptr
== '|');
1431 char *out_ptr
= corename
;
1432 char *const out_end
= corename
+ CORENAME_MAX_SIZE
;
1434 int pid_in_pattern
= 0;
1436 /* Repeat as long as we have more pattern to process and more output
1439 if (*pat_ptr
!= '%') {
1440 if (out_ptr
== out_end
)
1442 *out_ptr
++ = *pat_ptr
++;
1444 switch (*++pat_ptr
) {
1447 /* Double percent, output one percent */
1449 if (out_ptr
== out_end
)
1456 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1457 "%d", task_tgid_vnr(current
));
1458 if (rc
> out_end
- out_ptr
)
1464 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1466 if (rc
> out_end
- out_ptr
)
1472 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1474 if (rc
> out_end
- out_ptr
)
1478 /* signal that caused the coredump */
1480 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1482 if (rc
> out_end
- out_ptr
)
1486 /* UNIX time of coredump */
1489 do_gettimeofday(&tv
);
1490 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1492 if (rc
> out_end
- out_ptr
)
1499 down_read(&uts_sem
);
1500 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1501 "%s", utsname()->nodename
);
1503 if (rc
> out_end
- out_ptr
)
1509 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1510 "%s", current
->comm
);
1511 if (rc
> out_end
- out_ptr
)
1515 /* core limit size */
1517 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1518 "%lu", current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
);
1519 if (rc
> out_end
- out_ptr
)
1529 /* Backward compatibility with core_uses_pid:
1531 * If core_pattern does not include a %p (as is the default)
1532 * and core_uses_pid is set, then .%pid will be appended to
1533 * the filename. Do not do this for piped commands. */
1534 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
1535 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1536 ".%d", task_tgid_vnr(current
));
1537 if (rc
> out_end
- out_ptr
)
1546 static int zap_process(struct task_struct
*start
)
1548 struct task_struct
*t
;
1551 start
->signal
->flags
= SIGNAL_GROUP_EXIT
;
1552 start
->signal
->group_stop_count
= 0;
1556 if (t
!= current
&& t
->mm
) {
1557 sigaddset(&t
->pending
.signal
, SIGKILL
);
1558 signal_wake_up(t
, 1);
1561 } while_each_thread(start
, t
);
1566 static inline int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
1567 struct core_state
*core_state
, int exit_code
)
1569 struct task_struct
*g
, *p
;
1570 unsigned long flags
;
1573 spin_lock_irq(&tsk
->sighand
->siglock
);
1574 if (!signal_group_exit(tsk
->signal
)) {
1575 mm
->core_state
= core_state
;
1576 tsk
->signal
->group_exit_code
= exit_code
;
1577 nr
= zap_process(tsk
);
1579 spin_unlock_irq(&tsk
->sighand
->siglock
);
1580 if (unlikely(nr
< 0))
1583 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
1586 * We should find and kill all tasks which use this mm, and we should
1587 * count them correctly into ->nr_threads. We don't take tasklist
1588 * lock, but this is safe wrt:
1591 * None of sub-threads can fork after zap_process(leader). All
1592 * processes which were created before this point should be
1593 * visible to zap_threads() because copy_process() adds the new
1594 * process to the tail of init_task.tasks list, and lock/unlock
1595 * of ->siglock provides a memory barrier.
1598 * The caller holds mm->mmap_sem. This means that the task which
1599 * uses this mm can't pass exit_mm(), so it can't exit or clear
1603 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1604 * we must see either old or new leader, this does not matter.
1605 * However, it can change p->sighand, so lock_task_sighand(p)
1606 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1609 * Note also that "g" can be the old leader with ->mm == NULL
1610 * and already unhashed and thus removed from ->thread_group.
1611 * This is OK, __unhash_process()->list_del_rcu() does not
1612 * clear the ->next pointer, we will find the new leader via
1616 for_each_process(g
) {
1617 if (g
== tsk
->group_leader
)
1619 if (g
->flags
& PF_KTHREAD
)
1624 if (unlikely(p
->mm
== mm
)) {
1625 lock_task_sighand(p
, &flags
);
1626 nr
+= zap_process(p
);
1627 unlock_task_sighand(p
, &flags
);
1631 } while_each_thread(g
, p
);
1635 atomic_set(&core_state
->nr_threads
, nr
);
1639 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
1641 struct task_struct
*tsk
= current
;
1642 struct mm_struct
*mm
= tsk
->mm
;
1643 struct completion
*vfork_done
;
1646 init_completion(&core_state
->startup
);
1647 core_state
->dumper
.task
= tsk
;
1648 core_state
->dumper
.next
= NULL
;
1649 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
1650 up_write(&mm
->mmap_sem
);
1652 if (unlikely(core_waiters
< 0))
1656 * Make sure nobody is waiting for us to release the VM,
1657 * otherwise we can deadlock when we wait on each other
1659 vfork_done
= tsk
->vfork_done
;
1661 tsk
->vfork_done
= NULL
;
1662 complete(vfork_done
);
1666 wait_for_completion(&core_state
->startup
);
1668 return core_waiters
;
1671 static void coredump_finish(struct mm_struct
*mm
)
1673 struct core_thread
*curr
, *next
;
1674 struct task_struct
*task
;
1676 next
= mm
->core_state
->dumper
.next
;
1677 while ((curr
= next
) != NULL
) {
1681 * see exit_mm(), curr->task must not see
1682 * ->task == NULL before we read ->next.
1686 wake_up_process(task
);
1689 mm
->core_state
= NULL
;
1693 * set_dumpable converts traditional three-value dumpable to two flags and
1694 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1695 * these bits are not changed atomically. So get_dumpable can observe the
1696 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1697 * return either old dumpable or new one by paying attention to the order of
1698 * modifying the bits.
1700 * dumpable | mm->flags (binary)
1701 * old new | initial interim final
1702 * ---------+-----------------------
1710 * (*) get_dumpable regards interim value of 10 as 11.
1712 void set_dumpable(struct mm_struct
*mm
, int value
)
1716 clear_bit(MMF_DUMPABLE
, &mm
->flags
);
1718 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1721 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1723 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1726 set_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1728 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1733 int get_dumpable(struct mm_struct
*mm
)
1737 ret
= mm
->flags
& 0x3;
1738 return (ret
>= 2) ? 2 : ret
;
1741 void do_coredump(long signr
, int exit_code
, struct pt_regs
*regs
)
1743 struct core_state core_state
;
1744 char corename
[CORENAME_MAX_SIZE
+ 1];
1745 struct mm_struct
*mm
= current
->mm
;
1746 struct linux_binfmt
* binfmt
;
1747 struct inode
* inode
;
1749 const struct cred
*old_cred
;
1754 unsigned long core_limit
= current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
;
1755 char **helper_argv
= NULL
;
1756 int helper_argc
= 0;
1759 audit_core_dumps(signr
);
1761 binfmt
= current
->binfmt
;
1762 if (!binfmt
|| !binfmt
->core_dump
)
1765 cred
= prepare_creds();
1771 down_write(&mm
->mmap_sem
);
1773 * If another thread got here first, or we are not dumpable, bail out.
1775 if (mm
->core_state
|| !get_dumpable(mm
)) {
1776 up_write(&mm
->mmap_sem
);
1782 * We cannot trust fsuid as being the "true" uid of the
1783 * process nor do we know its entire history. We only know it
1784 * was tainted so we dump it as root in mode 2.
1786 if (get_dumpable(mm
) == 2) { /* Setuid core dump mode */
1787 flag
= O_EXCL
; /* Stop rewrite attacks */
1788 cred
->fsuid
= 0; /* Dump root private */
1791 retval
= coredump_wait(exit_code
, &core_state
);
1797 old_cred
= override_creds(cred
);
1800 * Clear any false indication of pending signals that might
1801 * be seen by the filesystem code called to write the core file.
1803 clear_thread_flag(TIF_SIGPENDING
);
1806 * lock_kernel() because format_corename() is controlled by sysctl, which
1807 * uses lock_kernel()
1810 ispipe
= format_corename(corename
, signr
);
1813 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1814 * to a pipe. Since we're not writing directly to the filesystem
1815 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1816 * created unless the pipe reader choses to write out the core file
1817 * at which point file size limits and permissions will be imposed
1818 * as it does with any other process
1820 if ((!ispipe
) && (core_limit
< binfmt
->min_coredump
))
1824 helper_argv
= argv_split(GFP_KERNEL
, corename
+1, &helper_argc
);
1826 printk(KERN_WARNING
"%s failed to allocate memory\n",
1830 /* Terminate the string before the first option */
1831 delimit
= strchr(corename
, ' ');
1834 delimit
= strrchr(helper_argv
[0], '/');
1838 delimit
= helper_argv
[0];
1839 if (!strcmp(delimit
, current
->comm
)) {
1840 printk(KERN_NOTICE
"Recursive core dump detected, "
1845 core_limit
= RLIM_INFINITY
;
1847 /* SIGPIPE can happen, but it's just never processed */
1848 if (call_usermodehelper_pipe(corename
+1, helper_argv
, NULL
,
1850 printk(KERN_INFO
"Core dump to %s pipe failed\n",
1855 file
= filp_open(corename
,
1856 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
1860 inode
= file
->f_path
.dentry
->d_inode
;
1861 if (inode
->i_nlink
> 1)
1862 goto close_fail
; /* multiple links - don't dump */
1863 if (!ispipe
&& d_unhashed(file
->f_path
.dentry
))
1866 /* AK: actually i see no reason to not allow this for named pipes etc.,
1867 but keep the previous behaviour for now. */
1868 if (!ispipe
&& !S_ISREG(inode
->i_mode
))
1871 * Dont allow local users get cute and trick others to coredump
1872 * into their pre-created files:
1874 if (inode
->i_uid
!= current_fsuid())
1878 if (!file
->f_op
->write
)
1880 if (!ispipe
&& do_truncate(file
->f_path
.dentry
, 0, 0, file
) != 0)
1883 retval
= binfmt
->core_dump(signr
, regs
, file
, core_limit
);
1886 current
->signal
->group_exit_code
|= 0x80;
1888 filp_close(file
, NULL
);
1891 argv_free(helper_argv
);
1893 revert_creds(old_cred
);
1895 coredump_finish(mm
);