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/ima.h>
49 #include <linux/syscalls.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/audit.h>
53 #include <linux/tracehook.h>
54 #include <linux/kmod.h>
55 #include <linux/fsnotify.h>
56 #include <linux/fs_struct.h>
58 #include <asm/uaccess.h>
59 #include <asm/mmu_context.h>
64 char core_pattern
[CORENAME_MAX_SIZE
] = "core";
65 int suid_dumpable
= 0;
67 /* The maximal length of core_pattern is also specified in sysctl.c */
69 static LIST_HEAD(formats
);
70 static DEFINE_RWLOCK(binfmt_lock
);
72 int __register_binfmt(struct linux_binfmt
* fmt
, int insert
)
76 write_lock(&binfmt_lock
);
77 insert
? list_add(&fmt
->lh
, &formats
) :
78 list_add_tail(&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
,
138 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
139 error
= PTR_ERR(file
);
143 fsnotify_open(file
->f_path
.dentry
);
147 struct linux_binfmt
* fmt
;
149 read_lock(&binfmt_lock
);
150 list_for_each_entry(fmt
, &formats
, lh
) {
151 if (!fmt
->load_shlib
)
153 if (!try_module_get(fmt
->module
))
155 read_unlock(&binfmt_lock
);
156 error
= fmt
->load_shlib(file
);
157 read_lock(&binfmt_lock
);
159 if (error
!= -ENOEXEC
)
162 read_unlock(&binfmt_lock
);
168 release_open_intent(&nd
);
175 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
181 #ifdef CONFIG_STACK_GROWSUP
183 ret
= expand_stack_downwards(bprm
->vma
, pos
);
188 ret
= get_user_pages(current
, bprm
->mm
, pos
,
189 1, write
, 1, &page
, NULL
);
194 unsigned long size
= bprm
->vma
->vm_end
- bprm
->vma
->vm_start
;
198 * We've historically supported up to 32 pages (ARG_MAX)
199 * of argument strings even with small stacks
205 * Limit to 1/4-th the stack size for the argv+env strings.
207 * - the remaining binfmt code will not run out of stack space,
208 * - the program will have a reasonable amount of stack left
211 rlim
= current
->signal
->rlim
;
212 if (size
> rlim
[RLIMIT_STACK
].rlim_cur
/ 4) {
221 static void put_arg_page(struct page
*page
)
226 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
230 static void free_arg_pages(struct linux_binprm
*bprm
)
234 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
237 flush_cache_page(bprm
->vma
, pos
, page_to_pfn(page
));
240 static int __bprm_mm_init(struct linux_binprm
*bprm
)
243 struct vm_area_struct
*vma
= NULL
;
244 struct mm_struct
*mm
= bprm
->mm
;
246 bprm
->vma
= vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
250 down_write(&mm
->mmap_sem
);
254 * Place the stack at the largest stack address the architecture
255 * supports. Later, we'll move this to an appropriate place. We don't
256 * use STACK_TOP because that can depend on attributes which aren't
259 vma
->vm_end
= STACK_TOP_MAX
;
260 vma
->vm_start
= vma
->vm_end
- PAGE_SIZE
;
261 vma
->vm_flags
= VM_STACK_FLAGS
;
262 vma
->vm_page_prot
= vm_get_page_prot(vma
->vm_flags
);
263 err
= insert_vm_struct(mm
, vma
);
267 mm
->stack_vm
= mm
->total_vm
= 1;
268 up_write(&mm
->mmap_sem
);
269 bprm
->p
= vma
->vm_end
- sizeof(void *);
272 up_write(&mm
->mmap_sem
);
274 kmem_cache_free(vm_area_cachep
, vma
);
278 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
280 return len
<= MAX_ARG_STRLEN
;
285 static struct page
*get_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
290 page
= bprm
->page
[pos
/ PAGE_SIZE
];
291 if (!page
&& write
) {
292 page
= alloc_page(GFP_HIGHUSER
|__GFP_ZERO
);
295 bprm
->page
[pos
/ PAGE_SIZE
] = page
;
301 static void put_arg_page(struct page
*page
)
305 static void free_arg_page(struct linux_binprm
*bprm
, int i
)
308 __free_page(bprm
->page
[i
]);
309 bprm
->page
[i
] = NULL
;
313 static void free_arg_pages(struct linux_binprm
*bprm
)
317 for (i
= 0; i
< MAX_ARG_PAGES
; i
++)
318 free_arg_page(bprm
, i
);
321 static void flush_arg_page(struct linux_binprm
*bprm
, unsigned long pos
,
326 static int __bprm_mm_init(struct linux_binprm
*bprm
)
328 bprm
->p
= PAGE_SIZE
* MAX_ARG_PAGES
- sizeof(void *);
332 static bool valid_arg_len(struct linux_binprm
*bprm
, long len
)
334 return len
<= bprm
->p
;
337 #endif /* CONFIG_MMU */
340 * Create a new mm_struct and populate it with a temporary stack
341 * vm_area_struct. We don't have enough context at this point to set the stack
342 * flags, permissions, and offset, so we use temporary values. We'll update
343 * them later in setup_arg_pages().
345 int bprm_mm_init(struct linux_binprm
*bprm
)
348 struct mm_struct
*mm
= NULL
;
350 bprm
->mm
= mm
= mm_alloc();
355 err
= init_new_context(current
, mm
);
359 err
= __bprm_mm_init(bprm
);
375 * count() counts the number of strings in array ARGV.
377 static int count(char __user
* __user
* argv
, int max
)
385 if (get_user(p
, argv
))
399 * 'copy_strings()' copies argument/environment strings from the old
400 * processes's memory to the new process's stack. The call to get_user_pages()
401 * ensures the destination page is created and not swapped out.
403 static int copy_strings(int argc
, char __user
* __user
* argv
,
404 struct linux_binprm
*bprm
)
406 struct page
*kmapped_page
= NULL
;
408 unsigned long kpos
= 0;
416 if (get_user(str
, argv
+argc
) ||
417 !(len
= strnlen_user(str
, MAX_ARG_STRLEN
))) {
422 if (!valid_arg_len(bprm
, len
)) {
427 /* We're going to work our way backwords. */
433 int offset
, bytes_to_copy
;
435 offset
= pos
% PAGE_SIZE
;
439 bytes_to_copy
= offset
;
440 if (bytes_to_copy
> len
)
443 offset
-= bytes_to_copy
;
444 pos
-= bytes_to_copy
;
445 str
-= bytes_to_copy
;
446 len
-= bytes_to_copy
;
448 if (!kmapped_page
|| kpos
!= (pos
& PAGE_MASK
)) {
451 page
= get_arg_page(bprm
, pos
, 1);
458 flush_kernel_dcache_page(kmapped_page
);
459 kunmap(kmapped_page
);
460 put_arg_page(kmapped_page
);
463 kaddr
= kmap(kmapped_page
);
464 kpos
= pos
& PAGE_MASK
;
465 flush_arg_page(bprm
, kpos
, kmapped_page
);
467 if (copy_from_user(kaddr
+offset
, str
, bytes_to_copy
)) {
476 flush_kernel_dcache_page(kmapped_page
);
477 kunmap(kmapped_page
);
478 put_arg_page(kmapped_page
);
484 * Like copy_strings, but get argv and its values from kernel memory.
486 int copy_strings_kernel(int argc
,char ** argv
, struct linux_binprm
*bprm
)
489 mm_segment_t oldfs
= get_fs();
491 r
= copy_strings(argc
, (char __user
* __user
*)argv
, bprm
);
495 EXPORT_SYMBOL(copy_strings_kernel
);
500 * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
501 * the binfmt code determines where the new stack should reside, we shift it to
502 * its final location. The process proceeds as follows:
504 * 1) Use shift to calculate the new vma endpoints.
505 * 2) Extend vma to cover both the old and new ranges. This ensures the
506 * arguments passed to subsequent functions are consistent.
507 * 3) Move vma's page tables to the new range.
508 * 4) Free up any cleared pgd range.
509 * 5) Shrink the vma to cover only the new range.
511 static int shift_arg_pages(struct vm_area_struct
*vma
, unsigned long shift
)
513 struct mm_struct
*mm
= vma
->vm_mm
;
514 unsigned long old_start
= vma
->vm_start
;
515 unsigned long old_end
= vma
->vm_end
;
516 unsigned long length
= old_end
- old_start
;
517 unsigned long new_start
= old_start
- shift
;
518 unsigned long new_end
= old_end
- shift
;
519 struct mmu_gather
*tlb
;
521 BUG_ON(new_start
> new_end
);
524 * ensure there are no vmas between where we want to go
527 if (vma
!= find_vma(mm
, new_start
))
531 * cover the whole range: [new_start, old_end)
533 vma_adjust(vma
, new_start
, old_end
, vma
->vm_pgoff
, NULL
);
536 * move the page tables downwards, on failure we rely on
537 * process cleanup to remove whatever mess we made.
539 if (length
!= move_page_tables(vma
, old_start
,
540 vma
, new_start
, length
))
544 tlb
= tlb_gather_mmu(mm
, 0);
545 if (new_end
> old_start
) {
547 * when the old and new regions overlap clear from new_end.
549 free_pgd_range(tlb
, new_end
, old_end
, new_end
,
550 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
553 * otherwise, clean from old_start; this is done to not touch
554 * the address space in [new_end, old_start) some architectures
555 * have constraints on va-space that make this illegal (IA64) -
556 * for the others its just a little faster.
558 free_pgd_range(tlb
, old_start
, old_end
, new_end
,
559 vma
->vm_next
? vma
->vm_next
->vm_start
: 0);
561 tlb_finish_mmu(tlb
, new_end
, old_end
);
564 * shrink the vma to just the new range.
566 vma_adjust(vma
, new_start
, new_end
, vma
->vm_pgoff
, NULL
);
571 #define EXTRA_STACK_VM_PAGES 20 /* random */
574 * Finalizes the stack vm_area_struct. The flags and permissions are updated,
575 * the stack is optionally relocated, and some extra space is added.
577 int setup_arg_pages(struct linux_binprm
*bprm
,
578 unsigned long stack_top
,
579 int executable_stack
)
582 unsigned long stack_shift
;
583 struct mm_struct
*mm
= current
->mm
;
584 struct vm_area_struct
*vma
= bprm
->vma
;
585 struct vm_area_struct
*prev
= NULL
;
586 unsigned long vm_flags
;
587 unsigned long stack_base
;
589 #ifdef CONFIG_STACK_GROWSUP
590 /* Limit stack size to 1GB */
591 stack_base
= current
->signal
->rlim
[RLIMIT_STACK
].rlim_max
;
592 if (stack_base
> (1 << 30))
593 stack_base
= 1 << 30;
595 /* Make sure we didn't let the argument array grow too large. */
596 if (vma
->vm_end
- vma
->vm_start
> stack_base
)
599 stack_base
= PAGE_ALIGN(stack_top
- stack_base
);
601 stack_shift
= vma
->vm_start
- stack_base
;
602 mm
->arg_start
= bprm
->p
- stack_shift
;
603 bprm
->p
= vma
->vm_end
- stack_shift
;
605 stack_top
= arch_align_stack(stack_top
);
606 stack_top
= PAGE_ALIGN(stack_top
);
607 stack_shift
= vma
->vm_end
- stack_top
;
609 bprm
->p
-= stack_shift
;
610 mm
->arg_start
= bprm
->p
;
614 bprm
->loader
-= stack_shift
;
615 bprm
->exec
-= stack_shift
;
617 down_write(&mm
->mmap_sem
);
618 vm_flags
= VM_STACK_FLAGS
;
621 * Adjust stack execute permissions; explicitly enable for
622 * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
623 * (arch default) otherwise.
625 if (unlikely(executable_stack
== EXSTACK_ENABLE_X
))
627 else if (executable_stack
== EXSTACK_DISABLE_X
)
628 vm_flags
&= ~VM_EXEC
;
629 vm_flags
|= mm
->def_flags
;
631 ret
= mprotect_fixup(vma
, &prev
, vma
->vm_start
, vma
->vm_end
,
637 /* Move stack pages down in memory. */
639 ret
= shift_arg_pages(vma
, stack_shift
);
641 up_write(&mm
->mmap_sem
);
646 #ifdef CONFIG_STACK_GROWSUP
647 stack_base
= vma
->vm_end
+ EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
649 stack_base
= vma
->vm_start
- EXTRA_STACK_VM_PAGES
* PAGE_SIZE
;
651 ret
= expand_stack(vma
, stack_base
);
656 up_write(&mm
->mmap_sem
);
659 EXPORT_SYMBOL(setup_arg_pages
);
661 #endif /* CONFIG_MMU */
663 struct file
*open_exec(const char *name
)
669 err
= path_lookup_open(AT_FDCWD
, name
, LOOKUP_FOLLOW
, &nd
,
670 FMODE_READ
|FMODE_EXEC
);
675 if (!S_ISREG(nd
.path
.dentry
->d_inode
->i_mode
))
678 if (nd
.path
.mnt
->mnt_flags
& MNT_NOEXEC
)
681 err
= inode_permission(nd
.path
.dentry
->d_inode
, MAY_EXEC
| MAY_OPEN
);
684 err
= ima_path_check(&nd
.path
, MAY_EXEC
| MAY_OPEN
, IMA_COUNT_UPDATE
);
688 file
= nameidata_to_filp(&nd
, O_RDONLY
|O_LARGEFILE
);
692 fsnotify_open(file
->f_path
.dentry
);
694 err
= deny_write_access(file
);
703 release_open_intent(&nd
);
708 EXPORT_SYMBOL(open_exec
);
710 int kernel_read(struct file
*file
, unsigned long offset
,
711 char *addr
, unsigned long count
)
719 /* The cast to a user pointer is valid due to the set_fs() */
720 result
= vfs_read(file
, (void __user
*)addr
, count
, &pos
);
725 EXPORT_SYMBOL(kernel_read
);
727 static int exec_mmap(struct mm_struct
*mm
)
729 struct task_struct
*tsk
;
730 struct mm_struct
* old_mm
, *active_mm
;
732 /* Notify parent that we're no longer interested in the old VM */
734 old_mm
= current
->mm
;
735 mm_release(tsk
, old_mm
);
739 * Make sure that if there is a core dump in progress
740 * for the old mm, we get out and die instead of going
741 * through with the exec. We must hold mmap_sem around
742 * checking core_state and changing tsk->mm.
744 down_read(&old_mm
->mmap_sem
);
745 if (unlikely(old_mm
->core_state
)) {
746 up_read(&old_mm
->mmap_sem
);
751 active_mm
= tsk
->active_mm
;
754 activate_mm(active_mm
, mm
);
756 arch_pick_mmap_layout(mm
);
758 up_read(&old_mm
->mmap_sem
);
759 BUG_ON(active_mm
!= old_mm
);
760 mm_update_next_owner(old_mm
);
769 * This function makes sure the current process has its own signal table,
770 * so that flush_signal_handlers can later reset the handlers without
771 * disturbing other processes. (Other processes might share the signal
772 * table via the CLONE_SIGHAND option to clone().)
774 static int de_thread(struct task_struct
*tsk
)
776 struct signal_struct
*sig
= tsk
->signal
;
777 struct sighand_struct
*oldsighand
= tsk
->sighand
;
778 spinlock_t
*lock
= &oldsighand
->siglock
;
781 if (thread_group_empty(tsk
))
782 goto no_thread_group
;
785 * Kill all other threads in the thread group.
788 if (signal_group_exit(sig
)) {
790 * Another group action in progress, just
791 * return so that the signal is processed.
793 spin_unlock_irq(lock
);
796 sig
->group_exit_task
= tsk
;
797 zap_other_threads(tsk
);
799 /* Account for the thread group leader hanging around: */
800 count
= thread_group_leader(tsk
) ? 1 : 2;
801 sig
->notify_count
= count
;
802 while (atomic_read(&sig
->count
) > count
) {
803 __set_current_state(TASK_UNINTERRUPTIBLE
);
804 spin_unlock_irq(lock
);
808 spin_unlock_irq(lock
);
811 * At this point all other threads have exited, all we have to
812 * do is to wait for the thread group leader to become inactive,
813 * and to assume its PID:
815 if (!thread_group_leader(tsk
)) {
816 struct task_struct
*leader
= tsk
->group_leader
;
818 sig
->notify_count
= -1; /* for exit_notify() */
820 write_lock_irq(&tasklist_lock
);
821 if (likely(leader
->exit_state
))
823 __set_current_state(TASK_UNINTERRUPTIBLE
);
824 write_unlock_irq(&tasklist_lock
);
829 * The only record we have of the real-time age of a
830 * process, regardless of execs it's done, is start_time.
831 * All the past CPU time is accumulated in signal_struct
832 * from sister threads now dead. But in this non-leader
833 * exec, nothing survives from the original leader thread,
834 * whose birth marks the true age of this process now.
835 * When we take on its identity by switching to its PID, we
836 * also take its birthdate (always earlier than our own).
838 tsk
->start_time
= leader
->start_time
;
840 BUG_ON(!same_thread_group(leader
, tsk
));
841 BUG_ON(has_group_leader_pid(tsk
));
843 * An exec() starts a new thread group with the
844 * TGID of the previous thread group. Rehash the
845 * two threads with a switched PID, and release
846 * the former thread group leader:
849 /* Become a process group leader with the old leader's pid.
850 * The old leader becomes a thread of the this thread group.
851 * Note: The old leader also uses this pid until release_task
852 * is called. Odd but simple and correct.
854 detach_pid(tsk
, PIDTYPE_PID
);
855 tsk
->pid
= leader
->pid
;
856 attach_pid(tsk
, PIDTYPE_PID
, task_pid(leader
));
857 transfer_pid(leader
, tsk
, PIDTYPE_PGID
);
858 transfer_pid(leader
, tsk
, PIDTYPE_SID
);
859 list_replace_rcu(&leader
->tasks
, &tsk
->tasks
);
861 tsk
->group_leader
= tsk
;
862 leader
->group_leader
= tsk
;
864 tsk
->exit_signal
= SIGCHLD
;
866 BUG_ON(leader
->exit_state
!= EXIT_ZOMBIE
);
867 leader
->exit_state
= EXIT_DEAD
;
868 write_unlock_irq(&tasklist_lock
);
870 release_task(leader
);
873 sig
->group_exit_task
= NULL
;
874 sig
->notify_count
= 0;
878 flush_itimer_signals();
880 if (atomic_read(&oldsighand
->count
) != 1) {
881 struct sighand_struct
*newsighand
;
883 * This ->sighand is shared with the CLONE_SIGHAND
884 * but not CLONE_THREAD task, switch to the new one.
886 newsighand
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
890 atomic_set(&newsighand
->count
, 1);
891 memcpy(newsighand
->action
, oldsighand
->action
,
892 sizeof(newsighand
->action
));
894 write_lock_irq(&tasklist_lock
);
895 spin_lock(&oldsighand
->siglock
);
896 rcu_assign_pointer(tsk
->sighand
, newsighand
);
897 spin_unlock(&oldsighand
->siglock
);
898 write_unlock_irq(&tasklist_lock
);
900 __cleanup_sighand(oldsighand
);
903 BUG_ON(!thread_group_leader(tsk
));
908 * These functions flushes out all traces of the currently running executable
909 * so that a new one can be started
911 static void flush_old_files(struct files_struct
* files
)
916 spin_lock(&files
->file_lock
);
918 unsigned long set
, i
;
922 fdt
= files_fdtable(files
);
923 if (i
>= fdt
->max_fds
)
925 set
= fdt
->close_on_exec
->fds_bits
[j
];
928 fdt
->close_on_exec
->fds_bits
[j
] = 0;
929 spin_unlock(&files
->file_lock
);
930 for ( ; set
; i
++,set
>>= 1) {
935 spin_lock(&files
->file_lock
);
938 spin_unlock(&files
->file_lock
);
941 char *get_task_comm(char *buf
, struct task_struct
*tsk
)
943 /* buf must be at least sizeof(tsk->comm) in size */
945 strncpy(buf
, tsk
->comm
, sizeof(tsk
->comm
));
950 void set_task_comm(struct task_struct
*tsk
, char *buf
)
953 strlcpy(tsk
->comm
, buf
, sizeof(tsk
->comm
));
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
;
1023 /* An exec changes our domain. We are no longer part of the thread
1026 current
->self_exec_id
++;
1028 flush_signal_handlers(current
, 0);
1029 flush_old_files(current
->files
);
1037 EXPORT_SYMBOL(flush_old_exec
);
1040 * install the new credentials for this executable
1042 void install_exec_creds(struct linux_binprm
*bprm
)
1044 security_bprm_committing_creds(bprm
);
1046 commit_creds(bprm
->cred
);
1049 /* cred_guard_mutex must be held at least to this point to prevent
1050 * ptrace_attach() from altering our determination of the task's
1051 * credentials; any time after this it may be unlocked */
1053 security_bprm_committed_creds(bprm
);
1055 EXPORT_SYMBOL(install_exec_creds
);
1058 * determine how safe it is to execute the proposed program
1059 * - the caller must hold current->cred_guard_mutex to protect against
1062 int check_unsafe_exec(struct linux_binprm
*bprm
)
1064 struct task_struct
*p
= current
, *t
;
1068 bprm
->unsafe
= tracehook_unsafe_exec(p
);
1071 write_lock(&p
->fs
->lock
);
1073 for (t
= next_thread(p
); t
!= p
; t
= next_thread(t
)) {
1079 if (p
->fs
->users
> n_fs
) {
1080 bprm
->unsafe
|= LSM_UNSAFE_SHARE
;
1083 if (!p
->fs
->in_exec
) {
1088 write_unlock(&p
->fs
->lock
);
1094 * Fill the binprm structure from the inode.
1095 * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
1097 * This may be called multiple times for binary chains (scripts for example).
1099 int prepare_binprm(struct linux_binprm
*bprm
)
1102 struct inode
* inode
= bprm
->file
->f_path
.dentry
->d_inode
;
1105 mode
= inode
->i_mode
;
1106 if (bprm
->file
->f_op
== NULL
)
1109 /* clear any previous set[ug]id data from a previous binary */
1110 bprm
->cred
->euid
= current_euid();
1111 bprm
->cred
->egid
= current_egid();
1113 if (!(bprm
->file
->f_path
.mnt
->mnt_flags
& MNT_NOSUID
)) {
1115 if (mode
& S_ISUID
) {
1116 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1117 bprm
->cred
->euid
= inode
->i_uid
;
1122 * If setgid is set but no group execute bit then this
1123 * is a candidate for mandatory locking, not a setgid
1126 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
1127 bprm
->per_clear
|= PER_CLEAR_ON_SETID
;
1128 bprm
->cred
->egid
= inode
->i_gid
;
1132 /* fill in binprm security blob */
1133 retval
= security_bprm_set_creds(bprm
);
1136 bprm
->cred_prepared
= 1;
1138 memset(bprm
->buf
, 0, BINPRM_BUF_SIZE
);
1139 return kernel_read(bprm
->file
, 0, bprm
->buf
, BINPRM_BUF_SIZE
);
1142 EXPORT_SYMBOL(prepare_binprm
);
1145 * Arguments are '\0' separated strings found at the location bprm->p
1146 * points to; chop off the first by relocating brpm->p to right after
1147 * the first '\0' encountered.
1149 int remove_arg_zero(struct linux_binprm
*bprm
)
1152 unsigned long offset
;
1160 offset
= bprm
->p
& ~PAGE_MASK
;
1161 page
= get_arg_page(bprm
, bprm
->p
, 0);
1166 kaddr
= kmap_atomic(page
, KM_USER0
);
1168 for (; offset
< PAGE_SIZE
&& kaddr
[offset
];
1169 offset
++, bprm
->p
++)
1172 kunmap_atomic(kaddr
, KM_USER0
);
1175 if (offset
== PAGE_SIZE
)
1176 free_arg_page(bprm
, (bprm
->p
>> PAGE_SHIFT
) - 1);
1177 } while (offset
== PAGE_SIZE
);
1186 EXPORT_SYMBOL(remove_arg_zero
);
1189 * cycle the list of binary formats handler, until one recognizes the image
1191 int search_binary_handler(struct linux_binprm
*bprm
,struct pt_regs
*regs
)
1193 unsigned int depth
= bprm
->recursion_depth
;
1195 struct linux_binfmt
*fmt
;
1197 retval
= security_bprm_check(bprm
);
1200 retval
= ima_bprm_check(bprm
);
1204 /* kernel module loader fixup */
1205 /* so we don't try to load run modprobe in kernel space. */
1208 retval
= audit_bprm(bprm
);
1213 for (try=0; try<2; try++) {
1214 read_lock(&binfmt_lock
);
1215 list_for_each_entry(fmt
, &formats
, lh
) {
1216 int (*fn
)(struct linux_binprm
*, struct pt_regs
*) = fmt
->load_binary
;
1219 if (!try_module_get(fmt
->module
))
1221 read_unlock(&binfmt_lock
);
1222 retval
= fn(bprm
, regs
);
1224 * Restore the depth counter to its starting value
1225 * in this call, so we don't have to rely on every
1226 * load_binary function to restore it on return.
1228 bprm
->recursion_depth
= depth
;
1231 tracehook_report_exec(fmt
, bprm
, regs
);
1233 allow_write_access(bprm
->file
);
1237 current
->did_exec
= 1;
1238 proc_exec_connector(current
);
1241 read_lock(&binfmt_lock
);
1243 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
)
1246 read_unlock(&binfmt_lock
);
1250 read_unlock(&binfmt_lock
);
1251 if (retval
!= -ENOEXEC
|| bprm
->mm
== NULL
) {
1253 #ifdef CONFIG_MODULES
1255 #define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
1256 if (printable(bprm
->buf
[0]) &&
1257 printable(bprm
->buf
[1]) &&
1258 printable(bprm
->buf
[2]) &&
1259 printable(bprm
->buf
[3]))
1260 break; /* -ENOEXEC */
1261 request_module("binfmt-%04x", *(unsigned short *)(&bprm
->buf
[2]));
1268 EXPORT_SYMBOL(search_binary_handler
);
1270 void free_bprm(struct linux_binprm
*bprm
)
1272 free_arg_pages(bprm
);
1274 abort_creds(bprm
->cred
);
1279 * sys_execve() executes a new program.
1281 int do_execve(char * filename
,
1282 char __user
*__user
*argv
,
1283 char __user
*__user
*envp
,
1284 struct pt_regs
* regs
)
1286 struct linux_binprm
*bprm
;
1288 struct files_struct
*displaced
;
1292 retval
= unshare_files(&displaced
);
1297 bprm
= kzalloc(sizeof(*bprm
), GFP_KERNEL
);
1301 retval
= mutex_lock_interruptible(¤t
->cred_guard_mutex
);
1304 current
->in_execve
= 1;
1307 bprm
->cred
= prepare_exec_creds();
1311 retval
= check_unsafe_exec(bprm
);
1314 clear_in_exec
= retval
;
1316 file
= open_exec(filename
);
1317 retval
= PTR_ERR(file
);
1324 bprm
->filename
= filename
;
1325 bprm
->interp
= filename
;
1327 retval
= bprm_mm_init(bprm
);
1331 bprm
->argc
= count(argv
, MAX_ARG_STRINGS
);
1332 if ((retval
= bprm
->argc
) < 0)
1335 bprm
->envc
= count(envp
, MAX_ARG_STRINGS
);
1336 if ((retval
= bprm
->envc
) < 0)
1339 retval
= prepare_binprm(bprm
);
1343 retval
= copy_strings_kernel(1, &bprm
->filename
, bprm
);
1347 bprm
->exec
= bprm
->p
;
1348 retval
= copy_strings(bprm
->envc
, envp
, bprm
);
1352 retval
= copy_strings(bprm
->argc
, argv
, bprm
);
1356 current
->flags
&= ~PF_KTHREAD
;
1357 retval
= search_binary_handler(bprm
,regs
);
1361 /* execve succeeded */
1362 current
->fs
->in_exec
= 0;
1363 current
->in_execve
= 0;
1364 mutex_unlock(¤t
->cred_guard_mutex
);
1365 acct_update_integrals(current
);
1368 put_files_struct(displaced
);
1377 allow_write_access(bprm
->file
);
1383 current
->fs
->in_exec
= 0;
1386 current
->in_execve
= 0;
1387 mutex_unlock(¤t
->cred_guard_mutex
);
1394 reset_files_struct(displaced
);
1399 int set_binfmt(struct linux_binfmt
*new)
1401 struct linux_binfmt
*old
= current
->binfmt
;
1404 if (!try_module_get(new->module
))
1407 current
->binfmt
= new;
1409 module_put(old
->module
);
1413 EXPORT_SYMBOL(set_binfmt
);
1415 /* format_corename will inspect the pattern parameter, and output a
1416 * name into corename, which must have space for at least
1417 * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
1419 static int format_corename(char *corename
, long signr
)
1421 const struct cred
*cred
= current_cred();
1422 const char *pat_ptr
= core_pattern
;
1423 int ispipe
= (*pat_ptr
== '|');
1424 char *out_ptr
= corename
;
1425 char *const out_end
= corename
+ CORENAME_MAX_SIZE
;
1427 int pid_in_pattern
= 0;
1429 /* Repeat as long as we have more pattern to process and more output
1432 if (*pat_ptr
!= '%') {
1433 if (out_ptr
== out_end
)
1435 *out_ptr
++ = *pat_ptr
++;
1437 switch (*++pat_ptr
) {
1440 /* Double percent, output one percent */
1442 if (out_ptr
== out_end
)
1449 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1450 "%d", task_tgid_vnr(current
));
1451 if (rc
> out_end
- out_ptr
)
1457 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1459 if (rc
> out_end
- out_ptr
)
1465 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1467 if (rc
> out_end
- out_ptr
)
1471 /* signal that caused the coredump */
1473 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1475 if (rc
> out_end
- out_ptr
)
1479 /* UNIX time of coredump */
1482 do_gettimeofday(&tv
);
1483 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1485 if (rc
> out_end
- out_ptr
)
1492 down_read(&uts_sem
);
1493 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1494 "%s", utsname()->nodename
);
1496 if (rc
> out_end
- out_ptr
)
1502 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1503 "%s", current
->comm
);
1504 if (rc
> out_end
- out_ptr
)
1508 /* core limit size */
1510 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1511 "%lu", current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
);
1512 if (rc
> out_end
- out_ptr
)
1522 /* Backward compatibility with core_uses_pid:
1524 * If core_pattern does not include a %p (as is the default)
1525 * and core_uses_pid is set, then .%pid will be appended to
1526 * the filename. Do not do this for piped commands. */
1527 if (!ispipe
&& !pid_in_pattern
&& core_uses_pid
) {
1528 rc
= snprintf(out_ptr
, out_end
- out_ptr
,
1529 ".%d", task_tgid_vnr(current
));
1530 if (rc
> out_end
- out_ptr
)
1539 static int zap_process(struct task_struct
*start
)
1541 struct task_struct
*t
;
1544 start
->signal
->flags
= SIGNAL_GROUP_EXIT
;
1545 start
->signal
->group_stop_count
= 0;
1549 if (t
!= current
&& t
->mm
) {
1550 sigaddset(&t
->pending
.signal
, SIGKILL
);
1551 signal_wake_up(t
, 1);
1554 } while_each_thread(start
, t
);
1559 static inline int zap_threads(struct task_struct
*tsk
, struct mm_struct
*mm
,
1560 struct core_state
*core_state
, int exit_code
)
1562 struct task_struct
*g
, *p
;
1563 unsigned long flags
;
1566 spin_lock_irq(&tsk
->sighand
->siglock
);
1567 if (!signal_group_exit(tsk
->signal
)) {
1568 mm
->core_state
= core_state
;
1569 tsk
->signal
->group_exit_code
= exit_code
;
1570 nr
= zap_process(tsk
);
1572 spin_unlock_irq(&tsk
->sighand
->siglock
);
1573 if (unlikely(nr
< 0))
1576 if (atomic_read(&mm
->mm_users
) == nr
+ 1)
1579 * We should find and kill all tasks which use this mm, and we should
1580 * count them correctly into ->nr_threads. We don't take tasklist
1581 * lock, but this is safe wrt:
1584 * None of sub-threads can fork after zap_process(leader). All
1585 * processes which were created before this point should be
1586 * visible to zap_threads() because copy_process() adds the new
1587 * process to the tail of init_task.tasks list, and lock/unlock
1588 * of ->siglock provides a memory barrier.
1591 * The caller holds mm->mmap_sem. This means that the task which
1592 * uses this mm can't pass exit_mm(), so it can't exit or clear
1596 * It does list_replace_rcu(&leader->tasks, ¤t->tasks),
1597 * we must see either old or new leader, this does not matter.
1598 * However, it can change p->sighand, so lock_task_sighand(p)
1599 * must be used. Since p->mm != NULL and we hold ->mmap_sem
1602 * Note also that "g" can be the old leader with ->mm == NULL
1603 * and already unhashed and thus removed from ->thread_group.
1604 * This is OK, __unhash_process()->list_del_rcu() does not
1605 * clear the ->next pointer, we will find the new leader via
1609 for_each_process(g
) {
1610 if (g
== tsk
->group_leader
)
1612 if (g
->flags
& PF_KTHREAD
)
1617 if (unlikely(p
->mm
== mm
)) {
1618 lock_task_sighand(p
, &flags
);
1619 nr
+= zap_process(p
);
1620 unlock_task_sighand(p
, &flags
);
1624 } while_each_thread(g
, p
);
1628 atomic_set(&core_state
->nr_threads
, nr
);
1632 static int coredump_wait(int exit_code
, struct core_state
*core_state
)
1634 struct task_struct
*tsk
= current
;
1635 struct mm_struct
*mm
= tsk
->mm
;
1636 struct completion
*vfork_done
;
1639 init_completion(&core_state
->startup
);
1640 core_state
->dumper
.task
= tsk
;
1641 core_state
->dumper
.next
= NULL
;
1642 core_waiters
= zap_threads(tsk
, mm
, core_state
, exit_code
);
1643 up_write(&mm
->mmap_sem
);
1645 if (unlikely(core_waiters
< 0))
1649 * Make sure nobody is waiting for us to release the VM,
1650 * otherwise we can deadlock when we wait on each other
1652 vfork_done
= tsk
->vfork_done
;
1654 tsk
->vfork_done
= NULL
;
1655 complete(vfork_done
);
1659 wait_for_completion(&core_state
->startup
);
1661 return core_waiters
;
1664 static void coredump_finish(struct mm_struct
*mm
)
1666 struct core_thread
*curr
, *next
;
1667 struct task_struct
*task
;
1669 next
= mm
->core_state
->dumper
.next
;
1670 while ((curr
= next
) != NULL
) {
1674 * see exit_mm(), curr->task must not see
1675 * ->task == NULL before we read ->next.
1679 wake_up_process(task
);
1682 mm
->core_state
= NULL
;
1686 * set_dumpable converts traditional three-value dumpable to two flags and
1687 * stores them into mm->flags. It modifies lower two bits of mm->flags, but
1688 * these bits are not changed atomically. So get_dumpable can observe the
1689 * intermediate state. To avoid doing unexpected behavior, get get_dumpable
1690 * return either old dumpable or new one by paying attention to the order of
1691 * modifying the bits.
1693 * dumpable | mm->flags (binary)
1694 * old new | initial interim final
1695 * ---------+-----------------------
1703 * (*) get_dumpable regards interim value of 10 as 11.
1705 void set_dumpable(struct mm_struct
*mm
, int value
)
1709 clear_bit(MMF_DUMPABLE
, &mm
->flags
);
1711 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1714 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1716 clear_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1719 set_bit(MMF_DUMP_SECURELY
, &mm
->flags
);
1721 set_bit(MMF_DUMPABLE
, &mm
->flags
);
1726 int get_dumpable(struct mm_struct
*mm
)
1730 ret
= mm
->flags
& 0x3;
1731 return (ret
>= 2) ? 2 : ret
;
1734 void do_coredump(long signr
, int exit_code
, struct pt_regs
*regs
)
1736 struct core_state core_state
;
1737 char corename
[CORENAME_MAX_SIZE
+ 1];
1738 struct mm_struct
*mm
= current
->mm
;
1739 struct linux_binfmt
* binfmt
;
1740 struct inode
* inode
;
1742 const struct cred
*old_cred
;
1747 unsigned long core_limit
= current
->signal
->rlim
[RLIMIT_CORE
].rlim_cur
;
1748 char **helper_argv
= NULL
;
1749 int helper_argc
= 0;
1752 audit_core_dumps(signr
);
1754 binfmt
= current
->binfmt
;
1755 if (!binfmt
|| !binfmt
->core_dump
)
1758 cred
= prepare_creds();
1764 down_write(&mm
->mmap_sem
);
1766 * If another thread got here first, or we are not dumpable, bail out.
1768 if (mm
->core_state
|| !get_dumpable(mm
)) {
1769 up_write(&mm
->mmap_sem
);
1775 * We cannot trust fsuid as being the "true" uid of the
1776 * process nor do we know its entire history. We only know it
1777 * was tainted so we dump it as root in mode 2.
1779 if (get_dumpable(mm
) == 2) { /* Setuid core dump mode */
1780 flag
= O_EXCL
; /* Stop rewrite attacks */
1781 cred
->fsuid
= 0; /* Dump root private */
1784 retval
= coredump_wait(exit_code
, &core_state
);
1790 old_cred
= override_creds(cred
);
1793 * Clear any false indication of pending signals that might
1794 * be seen by the filesystem code called to write the core file.
1796 clear_thread_flag(TIF_SIGPENDING
);
1799 * lock_kernel() because format_corename() is controlled by sysctl, which
1800 * uses lock_kernel()
1803 ispipe
= format_corename(corename
, signr
);
1806 * Don't bother to check the RLIMIT_CORE value if core_pattern points
1807 * to a pipe. Since we're not writing directly to the filesystem
1808 * RLIMIT_CORE doesn't really apply, as no actual core file will be
1809 * created unless the pipe reader choses to write out the core file
1810 * at which point file size limits and permissions will be imposed
1811 * as it does with any other process
1813 if ((!ispipe
) && (core_limit
< binfmt
->min_coredump
))
1817 helper_argv
= argv_split(GFP_KERNEL
, corename
+1, &helper_argc
);
1819 printk(KERN_WARNING
"%s failed to allocate memory\n",
1823 /* Terminate the string before the first option */
1824 delimit
= strchr(corename
, ' ');
1827 delimit
= strrchr(helper_argv
[0], '/');
1831 delimit
= helper_argv
[0];
1832 if (!strcmp(delimit
, current
->comm
)) {
1833 printk(KERN_NOTICE
"Recursive core dump detected, "
1838 core_limit
= RLIM_INFINITY
;
1840 /* SIGPIPE can happen, but it's just never processed */
1841 if (call_usermodehelper_pipe(corename
+1, helper_argv
, NULL
,
1843 printk(KERN_INFO
"Core dump to %s pipe failed\n",
1848 file
= filp_open(corename
,
1849 O_CREAT
| 2 | O_NOFOLLOW
| O_LARGEFILE
| flag
,
1853 inode
= file
->f_path
.dentry
->d_inode
;
1854 if (inode
->i_nlink
> 1)
1855 goto close_fail
; /* multiple links - don't dump */
1856 if (!ispipe
&& d_unhashed(file
->f_path
.dentry
))
1859 /* AK: actually i see no reason to not allow this for named pipes etc.,
1860 but keep the previous behaviour for now. */
1861 if (!ispipe
&& !S_ISREG(inode
->i_mode
))
1864 * Dont allow local users get cute and trick others to coredump
1865 * into their pre-created files:
1867 if (inode
->i_uid
!= current_fsuid())
1871 if (!file
->f_op
->write
)
1873 if (!ispipe
&& do_truncate(file
->f_path
.dentry
, 0, 0, file
) != 0)
1876 retval
= binfmt
->core_dump(signr
, regs
, file
, core_limit
);
1879 current
->signal
->group_exit_code
|= 0x80;
1881 filp_close(file
, NULL
);
1884 argv_free(helper_argv
);
1886 revert_creds(old_cred
);
1888 coredump_finish(mm
);