1 // SPDX-License-Identifier: GPL-2.0
5 #include <linux/init.h>
6 #include <linux/sysctl.h>
7 #include <linux/poll.h>
8 #include <linux/proc_fs.h>
9 #include <linux/printk.h>
10 #include <linux/security.h>
11 #include <linux/sched.h>
12 #include <linux/cred.h>
13 #include <linux/namei.h>
15 #include <linux/uio.h>
16 #include <linux/module.h>
17 #include <linux/bpf-cgroup.h>
18 #include <linux/mount.h>
21 static const struct dentry_operations proc_sys_dentry_operations
;
22 static const struct file_operations proc_sys_file_operations
;
23 static const struct inode_operations proc_sys_inode_operations
;
24 static const struct file_operations proc_sys_dir_file_operations
;
25 static const struct inode_operations proc_sys_dir_operations
;
27 /* shared constants to be used in various sysctls */
28 const int sysctl_vals
[] = { 0, 1, INT_MAX
};
29 EXPORT_SYMBOL(sysctl_vals
);
31 /* Support for permanently empty directories */
33 struct ctl_table sysctl_mount_point
[] = {
37 static bool is_empty_dir(struct ctl_table_header
*head
)
39 return head
->ctl_table
[0].child
== sysctl_mount_point
;
42 static void set_empty_dir(struct ctl_dir
*dir
)
44 dir
->header
.ctl_table
[0].child
= sysctl_mount_point
;
47 static void clear_empty_dir(struct ctl_dir
*dir
)
50 dir
->header
.ctl_table
[0].child
= NULL
;
53 void proc_sys_poll_notify(struct ctl_table_poll
*poll
)
58 atomic_inc(&poll
->event
);
59 wake_up_interruptible(&poll
->wait
);
62 static struct ctl_table root_table
[] = {
65 .mode
= S_IFDIR
|S_IRUGO
|S_IXUGO
,
69 static struct ctl_table_root sysctl_table_root
= {
70 .default_set
.dir
.header
= {
73 .ctl_table
= root_table
}},
74 .ctl_table_arg
= root_table
,
75 .root
= &sysctl_table_root
,
76 .set
= &sysctl_table_root
.default_set
,
80 static DEFINE_SPINLOCK(sysctl_lock
);
82 static void drop_sysctl_table(struct ctl_table_header
*header
);
83 static int sysctl_follow_link(struct ctl_table_header
**phead
,
84 struct ctl_table
**pentry
);
85 static int insert_links(struct ctl_table_header
*head
);
86 static void put_links(struct ctl_table_header
*header
);
88 static void sysctl_print_dir(struct ctl_dir
*dir
)
90 if (dir
->header
.parent
)
91 sysctl_print_dir(dir
->header
.parent
);
92 pr_cont("%s/", dir
->header
.ctl_table
[0].procname
);
95 static int namecmp(const char *name1
, int len1
, const char *name2
, int len2
)
99 cmp
= memcmp(name1
, name2
, min(len1
, len2
));
105 /* Called under sysctl_lock */
106 static struct ctl_table
*find_entry(struct ctl_table_header
**phead
,
107 struct ctl_dir
*dir
, const char *name
, int namelen
)
109 struct ctl_table_header
*head
;
110 struct ctl_table
*entry
;
111 struct rb_node
*node
= dir
->root
.rb_node
;
115 struct ctl_node
*ctl_node
;
116 const char *procname
;
119 ctl_node
= rb_entry(node
, struct ctl_node
, node
);
120 head
= ctl_node
->header
;
121 entry
= &head
->ctl_table
[ctl_node
- head
->node
];
122 procname
= entry
->procname
;
124 cmp
= namecmp(name
, namelen
, procname
, strlen(procname
));
126 node
= node
->rb_left
;
128 node
= node
->rb_right
;
137 static int insert_entry(struct ctl_table_header
*head
, struct ctl_table
*entry
)
139 struct rb_node
*node
= &head
->node
[entry
- head
->ctl_table
].node
;
140 struct rb_node
**p
= &head
->parent
->root
.rb_node
;
141 struct rb_node
*parent
= NULL
;
142 const char *name
= entry
->procname
;
143 int namelen
= strlen(name
);
146 struct ctl_table_header
*parent_head
;
147 struct ctl_table
*parent_entry
;
148 struct ctl_node
*parent_node
;
149 const char *parent_name
;
153 parent_node
= rb_entry(parent
, struct ctl_node
, node
);
154 parent_head
= parent_node
->header
;
155 parent_entry
= &parent_head
->ctl_table
[parent_node
- parent_head
->node
];
156 parent_name
= parent_entry
->procname
;
158 cmp
= namecmp(name
, namelen
, parent_name
, strlen(parent_name
));
164 pr_err("sysctl duplicate entry: ");
165 sysctl_print_dir(head
->parent
);
166 pr_cont("/%s\n", entry
->procname
);
171 rb_link_node(node
, parent
, p
);
172 rb_insert_color(node
, &head
->parent
->root
);
176 static void erase_entry(struct ctl_table_header
*head
, struct ctl_table
*entry
)
178 struct rb_node
*node
= &head
->node
[entry
- head
->ctl_table
].node
;
180 rb_erase(node
, &head
->parent
->root
);
183 static void init_header(struct ctl_table_header
*head
,
184 struct ctl_table_root
*root
, struct ctl_table_set
*set
,
185 struct ctl_node
*node
, struct ctl_table
*table
)
187 head
->ctl_table
= table
;
188 head
->ctl_table_arg
= table
;
192 head
->unregistering
= NULL
;
197 INIT_HLIST_HEAD(&head
->inodes
);
199 struct ctl_table
*entry
;
200 for (entry
= table
; entry
->procname
; entry
++, node
++)
205 static void erase_header(struct ctl_table_header
*head
)
207 struct ctl_table
*entry
;
208 for (entry
= head
->ctl_table
; entry
->procname
; entry
++)
209 erase_entry(head
, entry
);
212 static int insert_header(struct ctl_dir
*dir
, struct ctl_table_header
*header
)
214 struct ctl_table
*entry
;
217 /* Is this a permanently empty directory? */
218 if (is_empty_dir(&dir
->header
))
221 /* Am I creating a permanently empty directory? */
222 if (header
->ctl_table
== sysctl_mount_point
) {
223 if (!RB_EMPTY_ROOT(&dir
->root
))
229 header
->parent
= dir
;
230 err
= insert_links(header
);
233 for (entry
= header
->ctl_table
; entry
->procname
; entry
++) {
234 err
= insert_entry(header
, entry
);
240 erase_header(header
);
243 if (header
->ctl_table
== sysctl_mount_point
)
244 clear_empty_dir(dir
);
245 header
->parent
= NULL
;
246 drop_sysctl_table(&dir
->header
);
250 /* called under sysctl_lock */
251 static int use_table(struct ctl_table_header
*p
)
253 if (unlikely(p
->unregistering
))
259 /* called under sysctl_lock */
260 static void unuse_table(struct ctl_table_header
*p
)
263 if (unlikely(p
->unregistering
))
264 complete(p
->unregistering
);
267 static void proc_sys_invalidate_dcache(struct ctl_table_header
*head
)
269 proc_invalidate_siblings_dcache(&head
->inodes
, &sysctl_lock
);
272 /* called under sysctl_lock, will reacquire if has to wait */
273 static void start_unregistering(struct ctl_table_header
*p
)
276 * if p->used is 0, nobody will ever touch that entry again;
277 * we'll eliminate all paths to it before dropping sysctl_lock
279 if (unlikely(p
->used
)) {
280 struct completion wait
;
281 init_completion(&wait
);
282 p
->unregistering
= &wait
;
283 spin_unlock(&sysctl_lock
);
284 wait_for_completion(&wait
);
286 /* anything non-NULL; we'll never dereference it */
287 p
->unregistering
= ERR_PTR(-EINVAL
);
288 spin_unlock(&sysctl_lock
);
291 * Invalidate dentries for unregistered sysctls: namespaced sysctls
292 * can have duplicate names and contaminate dcache very badly.
294 proc_sys_invalidate_dcache(p
);
296 * do not remove from the list until nobody holds it; walking the
297 * list in do_sysctl() relies on that.
299 spin_lock(&sysctl_lock
);
303 static struct ctl_table_header
*sysctl_head_grab(struct ctl_table_header
*head
)
306 spin_lock(&sysctl_lock
);
307 if (!use_table(head
))
308 head
= ERR_PTR(-ENOENT
);
309 spin_unlock(&sysctl_lock
);
313 static void sysctl_head_finish(struct ctl_table_header
*head
)
317 spin_lock(&sysctl_lock
);
319 spin_unlock(&sysctl_lock
);
322 static struct ctl_table_set
*
323 lookup_header_set(struct ctl_table_root
*root
)
325 struct ctl_table_set
*set
= &root
->default_set
;
327 set
= root
->lookup(root
);
331 static struct ctl_table
*lookup_entry(struct ctl_table_header
**phead
,
333 const char *name
, int namelen
)
335 struct ctl_table_header
*head
;
336 struct ctl_table
*entry
;
338 spin_lock(&sysctl_lock
);
339 entry
= find_entry(&head
, dir
, name
, namelen
);
340 if (entry
&& use_table(head
))
344 spin_unlock(&sysctl_lock
);
348 static struct ctl_node
*first_usable_entry(struct rb_node
*node
)
350 struct ctl_node
*ctl_node
;
352 for (;node
; node
= rb_next(node
)) {
353 ctl_node
= rb_entry(node
, struct ctl_node
, node
);
354 if (use_table(ctl_node
->header
))
360 static void first_entry(struct ctl_dir
*dir
,
361 struct ctl_table_header
**phead
, struct ctl_table
**pentry
)
363 struct ctl_table_header
*head
= NULL
;
364 struct ctl_table
*entry
= NULL
;
365 struct ctl_node
*ctl_node
;
367 spin_lock(&sysctl_lock
);
368 ctl_node
= first_usable_entry(rb_first(&dir
->root
));
369 spin_unlock(&sysctl_lock
);
371 head
= ctl_node
->header
;
372 entry
= &head
->ctl_table
[ctl_node
- head
->node
];
378 static void next_entry(struct ctl_table_header
**phead
, struct ctl_table
**pentry
)
380 struct ctl_table_header
*head
= *phead
;
381 struct ctl_table
*entry
= *pentry
;
382 struct ctl_node
*ctl_node
= &head
->node
[entry
- head
->ctl_table
];
384 spin_lock(&sysctl_lock
);
387 ctl_node
= first_usable_entry(rb_next(&ctl_node
->node
));
388 spin_unlock(&sysctl_lock
);
391 head
= ctl_node
->header
;
392 entry
= &head
->ctl_table
[ctl_node
- head
->node
];
399 * sysctl_perm does NOT grant the superuser all rights automatically, because
400 * some sysctl variables are readonly even to root.
403 static int test_perm(int mode
, int op
)
405 if (uid_eq(current_euid(), GLOBAL_ROOT_UID
))
407 else if (in_egroup_p(GLOBAL_ROOT_GID
))
409 if ((op
& ~mode
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
)) == 0)
414 static int sysctl_perm(struct ctl_table_header
*head
, struct ctl_table
*table
, int op
)
416 struct ctl_table_root
*root
= head
->root
;
419 if (root
->permissions
)
420 mode
= root
->permissions(head
, table
);
424 return test_perm(mode
, op
);
427 static struct inode
*proc_sys_make_inode(struct super_block
*sb
,
428 struct ctl_table_header
*head
, struct ctl_table
*table
)
430 struct ctl_table_root
*root
= head
->root
;
432 struct proc_inode
*ei
;
434 inode
= new_inode(sb
);
436 return ERR_PTR(-ENOMEM
);
438 inode
->i_ino
= get_next_ino();
442 spin_lock(&sysctl_lock
);
443 if (unlikely(head
->unregistering
)) {
444 spin_unlock(&sysctl_lock
);
446 return ERR_PTR(-ENOENT
);
449 ei
->sysctl_entry
= table
;
450 hlist_add_head_rcu(&ei
->sibling_inodes
, &head
->inodes
);
452 spin_unlock(&sysctl_lock
);
454 inode
->i_mtime
= inode
->i_atime
= inode
->i_ctime
= current_time(inode
);
455 inode
->i_mode
= table
->mode
;
456 if (!S_ISDIR(table
->mode
)) {
457 inode
->i_mode
|= S_IFREG
;
458 inode
->i_op
= &proc_sys_inode_operations
;
459 inode
->i_fop
= &proc_sys_file_operations
;
461 inode
->i_mode
|= S_IFDIR
;
462 inode
->i_op
= &proc_sys_dir_operations
;
463 inode
->i_fop
= &proc_sys_dir_file_operations
;
464 if (is_empty_dir(head
))
465 make_empty_dir_inode(inode
);
468 if (root
->set_ownership
)
469 root
->set_ownership(head
, table
, &inode
->i_uid
, &inode
->i_gid
);
471 inode
->i_uid
= GLOBAL_ROOT_UID
;
472 inode
->i_gid
= GLOBAL_ROOT_GID
;
478 void proc_sys_evict_inode(struct inode
*inode
, struct ctl_table_header
*head
)
480 spin_lock(&sysctl_lock
);
481 hlist_del_init_rcu(&PROC_I(inode
)->sibling_inodes
);
483 kfree_rcu(head
, rcu
);
484 spin_unlock(&sysctl_lock
);
487 static struct ctl_table_header
*grab_header(struct inode
*inode
)
489 struct ctl_table_header
*head
= PROC_I(inode
)->sysctl
;
491 head
= &sysctl_table_root
.default_set
.dir
.header
;
492 return sysctl_head_grab(head
);
495 static struct dentry
*proc_sys_lookup(struct inode
*dir
, struct dentry
*dentry
,
498 struct ctl_table_header
*head
= grab_header(dir
);
499 struct ctl_table_header
*h
= NULL
;
500 const struct qstr
*name
= &dentry
->d_name
;
503 struct dentry
*err
= ERR_PTR(-ENOENT
);
504 struct ctl_dir
*ctl_dir
;
508 return ERR_CAST(head
);
510 ctl_dir
= container_of(head
, struct ctl_dir
, header
);
512 p
= lookup_entry(&h
, ctl_dir
, name
->name
, name
->len
);
516 if (S_ISLNK(p
->mode
)) {
517 ret
= sysctl_follow_link(&h
, &p
);
523 inode
= proc_sys_make_inode(dir
->i_sb
, h
? h
: head
, p
);
525 err
= ERR_CAST(inode
);
529 d_set_d_op(dentry
, &proc_sys_dentry_operations
);
530 err
= d_splice_alias(inode
, dentry
);
534 sysctl_head_finish(h
);
535 sysctl_head_finish(head
);
539 static ssize_t
proc_sys_call_handler(struct kiocb
*iocb
, struct iov_iter
*iter
,
542 struct inode
*inode
= file_inode(iocb
->ki_filp
);
543 struct ctl_table_header
*head
= grab_header(inode
);
544 struct ctl_table
*table
= PROC_I(inode
)->sysctl_entry
;
545 size_t count
= iov_iter_count(iter
);
550 return PTR_ERR(head
);
553 * At this point we know that the sysctl was not unregistered
554 * and won't be until we finish.
557 if (sysctl_perm(head
, table
, write
? MAY_WRITE
: MAY_READ
))
560 /* if that can happen at all, it should be -EINVAL, not -EISDIR */
562 if (!table
->proc_handler
)
565 /* don't even try if the size is too large */
567 if (count
>= KMALLOC_MAX_SIZE
)
569 kbuf
= kvzalloc(count
+ 1, GFP_KERNEL
);
575 if (!copy_from_iter_full(kbuf
, count
, iter
))
580 error
= BPF_CGROUP_RUN_PROG_SYSCTL(head
, table
, write
, &kbuf
, &count
,
585 /* careful: calling conventions are nasty here */
586 error
= table
->proc_handler(table
, write
, kbuf
, &count
, &iocb
->ki_pos
);
592 if (copy_to_iter(kbuf
, count
, iter
) < count
)
600 sysctl_head_finish(head
);
605 static ssize_t
proc_sys_read(struct kiocb
*iocb
, struct iov_iter
*iter
)
607 return proc_sys_call_handler(iocb
, iter
, 0);
610 static ssize_t
proc_sys_write(struct kiocb
*iocb
, struct iov_iter
*iter
)
612 return proc_sys_call_handler(iocb
, iter
, 1);
615 static int proc_sys_open(struct inode
*inode
, struct file
*filp
)
617 struct ctl_table_header
*head
= grab_header(inode
);
618 struct ctl_table
*table
= PROC_I(inode
)->sysctl_entry
;
620 /* sysctl was unregistered */
622 return PTR_ERR(head
);
625 filp
->private_data
= proc_sys_poll_event(table
->poll
);
627 sysctl_head_finish(head
);
632 static __poll_t
proc_sys_poll(struct file
*filp
, poll_table
*wait
)
634 struct inode
*inode
= file_inode(filp
);
635 struct ctl_table_header
*head
= grab_header(inode
);
636 struct ctl_table
*table
= PROC_I(inode
)->sysctl_entry
;
637 __poll_t ret
= DEFAULT_POLLMASK
;
640 /* sysctl was unregistered */
642 return EPOLLERR
| EPOLLHUP
;
644 if (!table
->proc_handler
)
650 event
= (unsigned long)filp
->private_data
;
651 poll_wait(filp
, &table
->poll
->wait
, wait
);
653 if (event
!= atomic_read(&table
->poll
->event
)) {
654 filp
->private_data
= proc_sys_poll_event(table
->poll
);
655 ret
= EPOLLIN
| EPOLLRDNORM
| EPOLLERR
| EPOLLPRI
;
659 sysctl_head_finish(head
);
664 static bool proc_sys_fill_cache(struct file
*file
,
665 struct dir_context
*ctx
,
666 struct ctl_table_header
*head
,
667 struct ctl_table
*table
)
669 struct dentry
*child
, *dir
= file
->f_path
.dentry
;
673 unsigned type
= DT_UNKNOWN
;
675 qname
.name
= table
->procname
;
676 qname
.len
= strlen(table
->procname
);
677 qname
.hash
= full_name_hash(dir
, qname
.name
, qname
.len
);
679 child
= d_lookup(dir
, &qname
);
681 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq
);
682 child
= d_alloc_parallel(dir
, &qname
, &wq
);
685 if (d_in_lookup(child
)) {
687 inode
= proc_sys_make_inode(dir
->d_sb
, head
, table
);
689 d_lookup_done(child
);
693 d_set_d_op(child
, &proc_sys_dentry_operations
);
694 res
= d_splice_alias(inode
, child
);
695 d_lookup_done(child
);
706 inode
= d_inode(child
);
708 type
= inode
->i_mode
>> 12;
710 return dir_emit(ctx
, qname
.name
, qname
.len
, ino
, type
);
713 static bool proc_sys_link_fill_cache(struct file
*file
,
714 struct dir_context
*ctx
,
715 struct ctl_table_header
*head
,
716 struct ctl_table
*table
)
720 head
= sysctl_head_grab(head
);
724 /* It is not an error if we can not follow the link ignore it */
725 if (sysctl_follow_link(&head
, &table
))
728 ret
= proc_sys_fill_cache(file
, ctx
, head
, table
);
730 sysctl_head_finish(head
);
734 static int scan(struct ctl_table_header
*head
, struct ctl_table
*table
,
735 unsigned long *pos
, struct file
*file
,
736 struct dir_context
*ctx
)
740 if ((*pos
)++ < ctx
->pos
)
743 if (unlikely(S_ISLNK(table
->mode
)))
744 res
= proc_sys_link_fill_cache(file
, ctx
, head
, table
);
746 res
= proc_sys_fill_cache(file
, ctx
, head
, table
);
754 static int proc_sys_readdir(struct file
*file
, struct dir_context
*ctx
)
756 struct ctl_table_header
*head
= grab_header(file_inode(file
));
757 struct ctl_table_header
*h
= NULL
;
758 struct ctl_table
*entry
;
759 struct ctl_dir
*ctl_dir
;
763 return PTR_ERR(head
);
765 ctl_dir
= container_of(head
, struct ctl_dir
, header
);
767 if (!dir_emit_dots(file
, ctx
))
772 for (first_entry(ctl_dir
, &h
, &entry
); h
; next_entry(&h
, &entry
)) {
773 if (!scan(h
, entry
, &pos
, file
, ctx
)) {
774 sysctl_head_finish(h
);
779 sysctl_head_finish(head
);
783 static int proc_sys_permission(struct user_namespace
*mnt_userns
,
784 struct inode
*inode
, int mask
)
787 * sysctl entries that are not writeable,
788 * are _NOT_ writeable, capabilities or not.
790 struct ctl_table_header
*head
;
791 struct ctl_table
*table
;
794 /* Executable files are not allowed under /proc/sys/ */
795 if ((mask
& MAY_EXEC
) && S_ISREG(inode
->i_mode
))
798 head
= grab_header(inode
);
800 return PTR_ERR(head
);
802 table
= PROC_I(inode
)->sysctl_entry
;
803 if (!table
) /* global root - r-xr-xr-x */
804 error
= mask
& MAY_WRITE
? -EACCES
: 0;
805 else /* Use the permissions on the sysctl table entry */
806 error
= sysctl_perm(head
, table
, mask
& ~MAY_NOT_BLOCK
);
808 sysctl_head_finish(head
);
812 static int proc_sys_setattr(struct user_namespace
*mnt_userns
,
813 struct dentry
*dentry
, struct iattr
*attr
)
815 struct inode
*inode
= d_inode(dentry
);
818 if (attr
->ia_valid
& (ATTR_MODE
| ATTR_UID
| ATTR_GID
))
821 error
= setattr_prepare(&init_user_ns
, dentry
, attr
);
825 setattr_copy(&init_user_ns
, inode
, attr
);
826 mark_inode_dirty(inode
);
830 static int proc_sys_getattr(struct user_namespace
*mnt_userns
,
831 const struct path
*path
, struct kstat
*stat
,
832 u32 request_mask
, unsigned int query_flags
)
834 struct inode
*inode
= d_inode(path
->dentry
);
835 struct ctl_table_header
*head
= grab_header(inode
);
836 struct ctl_table
*table
= PROC_I(inode
)->sysctl_entry
;
839 return PTR_ERR(head
);
841 generic_fillattr(&init_user_ns
, inode
, stat
);
843 stat
->mode
= (stat
->mode
& S_IFMT
) | table
->mode
;
845 sysctl_head_finish(head
);
849 static const struct file_operations proc_sys_file_operations
= {
850 .open
= proc_sys_open
,
851 .poll
= proc_sys_poll
,
852 .read_iter
= proc_sys_read
,
853 .write_iter
= proc_sys_write
,
854 .splice_read
= generic_file_splice_read
,
855 .splice_write
= iter_file_splice_write
,
856 .llseek
= default_llseek
,
859 static const struct file_operations proc_sys_dir_file_operations
= {
860 .read
= generic_read_dir
,
861 .iterate_shared
= proc_sys_readdir
,
862 .llseek
= generic_file_llseek
,
865 static const struct inode_operations proc_sys_inode_operations
= {
866 .permission
= proc_sys_permission
,
867 .setattr
= proc_sys_setattr
,
868 .getattr
= proc_sys_getattr
,
871 static const struct inode_operations proc_sys_dir_operations
= {
872 .lookup
= proc_sys_lookup
,
873 .permission
= proc_sys_permission
,
874 .setattr
= proc_sys_setattr
,
875 .getattr
= proc_sys_getattr
,
878 static int proc_sys_revalidate(struct dentry
*dentry
, unsigned int flags
)
880 if (flags
& LOOKUP_RCU
)
882 return !PROC_I(d_inode(dentry
))->sysctl
->unregistering
;
885 static int proc_sys_delete(const struct dentry
*dentry
)
887 return !!PROC_I(d_inode(dentry
))->sysctl
->unregistering
;
890 static int sysctl_is_seen(struct ctl_table_header
*p
)
892 struct ctl_table_set
*set
= p
->set
;
894 spin_lock(&sysctl_lock
);
895 if (p
->unregistering
)
897 else if (!set
->is_seen
)
900 res
= set
->is_seen(set
);
901 spin_unlock(&sysctl_lock
);
905 static int proc_sys_compare(const struct dentry
*dentry
,
906 unsigned int len
, const char *str
, const struct qstr
*name
)
908 struct ctl_table_header
*head
;
911 /* Although proc doesn't have negative dentries, rcu-walk means
912 * that inode here can be NULL */
913 /* AV: can it, indeed? */
914 inode
= d_inode_rcu(dentry
);
917 if (name
->len
!= len
)
919 if (memcmp(name
->name
, str
, len
))
921 head
= rcu_dereference(PROC_I(inode
)->sysctl
);
922 return !head
|| !sysctl_is_seen(head
);
925 static const struct dentry_operations proc_sys_dentry_operations
= {
926 .d_revalidate
= proc_sys_revalidate
,
927 .d_delete
= proc_sys_delete
,
928 .d_compare
= proc_sys_compare
,
931 static struct ctl_dir
*find_subdir(struct ctl_dir
*dir
,
932 const char *name
, int namelen
)
934 struct ctl_table_header
*head
;
935 struct ctl_table
*entry
;
937 entry
= find_entry(&head
, dir
, name
, namelen
);
939 return ERR_PTR(-ENOENT
);
940 if (!S_ISDIR(entry
->mode
))
941 return ERR_PTR(-ENOTDIR
);
942 return container_of(head
, struct ctl_dir
, header
);
945 static struct ctl_dir
*new_dir(struct ctl_table_set
*set
,
946 const char *name
, int namelen
)
948 struct ctl_table
*table
;
950 struct ctl_node
*node
;
953 new = kzalloc(sizeof(*new) + sizeof(struct ctl_node
) +
954 sizeof(struct ctl_table
)*2 + namelen
+ 1,
959 node
= (struct ctl_node
*)(new + 1);
960 table
= (struct ctl_table
*)(node
+ 1);
961 new_name
= (char *)(table
+ 2);
962 memcpy(new_name
, name
, namelen
);
963 new_name
[namelen
] = '\0';
964 table
[0].procname
= new_name
;
965 table
[0].mode
= S_IFDIR
|S_IRUGO
|S_IXUGO
;
966 init_header(&new->header
, set
->dir
.header
.root
, set
, node
, table
);
972 * get_subdir - find or create a subdir with the specified name.
973 * @dir: Directory to create the subdirectory in
974 * @name: The name of the subdirectory to find or create
975 * @namelen: The length of name
977 * Takes a directory with an elevated reference count so we know that
978 * if we drop the lock the directory will not go away. Upon success
979 * the reference is moved from @dir to the returned subdirectory.
980 * Upon error an error code is returned and the reference on @dir is
983 static struct ctl_dir
*get_subdir(struct ctl_dir
*dir
,
984 const char *name
, int namelen
)
986 struct ctl_table_set
*set
= dir
->header
.set
;
987 struct ctl_dir
*subdir
, *new = NULL
;
990 spin_lock(&sysctl_lock
);
991 subdir
= find_subdir(dir
, name
, namelen
);
994 if (PTR_ERR(subdir
) != -ENOENT
)
997 spin_unlock(&sysctl_lock
);
998 new = new_dir(set
, name
, namelen
);
999 spin_lock(&sysctl_lock
);
1000 subdir
= ERR_PTR(-ENOMEM
);
1004 /* Was the subdir added while we dropped the lock? */
1005 subdir
= find_subdir(dir
, name
, namelen
);
1006 if (!IS_ERR(subdir
))
1008 if (PTR_ERR(subdir
) != -ENOENT
)
1011 /* Nope. Use the our freshly made directory entry. */
1012 err
= insert_header(dir
, &new->header
);
1013 subdir
= ERR_PTR(err
);
1018 subdir
->header
.nreg
++;
1020 if (IS_ERR(subdir
)) {
1021 pr_err("sysctl could not get directory: ");
1022 sysctl_print_dir(dir
);
1023 pr_cont("/%*.*s %ld\n",
1024 namelen
, namelen
, name
, PTR_ERR(subdir
));
1026 drop_sysctl_table(&dir
->header
);
1028 drop_sysctl_table(&new->header
);
1029 spin_unlock(&sysctl_lock
);
1033 static struct ctl_dir
*xlate_dir(struct ctl_table_set
*set
, struct ctl_dir
*dir
)
1035 struct ctl_dir
*parent
;
1036 const char *procname
;
1037 if (!dir
->header
.parent
)
1039 parent
= xlate_dir(set
, dir
->header
.parent
);
1042 procname
= dir
->header
.ctl_table
[0].procname
;
1043 return find_subdir(parent
, procname
, strlen(procname
));
1046 static int sysctl_follow_link(struct ctl_table_header
**phead
,
1047 struct ctl_table
**pentry
)
1049 struct ctl_table_header
*head
;
1050 struct ctl_table_root
*root
;
1051 struct ctl_table_set
*set
;
1052 struct ctl_table
*entry
;
1053 struct ctl_dir
*dir
;
1057 spin_lock(&sysctl_lock
);
1058 root
= (*pentry
)->data
;
1059 set
= lookup_header_set(root
);
1060 dir
= xlate_dir(set
, (*phead
)->parent
);
1064 const char *procname
= (*pentry
)->procname
;
1066 entry
= find_entry(&head
, dir
, procname
, strlen(procname
));
1068 if (entry
&& use_table(head
)) {
1069 unuse_table(*phead
);
1076 spin_unlock(&sysctl_lock
);
1080 static int sysctl_err(const char *path
, struct ctl_table
*table
, char *fmt
, ...)
1082 struct va_format vaf
;
1085 va_start(args
, fmt
);
1089 pr_err("sysctl table check failed: %s/%s %pV\n",
1090 path
, table
->procname
, &vaf
);
1096 static int sysctl_check_table_array(const char *path
, struct ctl_table
*table
)
1100 if ((table
->proc_handler
== proc_douintvec
) ||
1101 (table
->proc_handler
== proc_douintvec_minmax
)) {
1102 if (table
->maxlen
!= sizeof(unsigned int))
1103 err
|= sysctl_err(path
, table
, "array not allowed");
1106 if (table
->proc_handler
== proc_dou8vec_minmax
) {
1107 if (table
->maxlen
!= sizeof(u8
))
1108 err
|= sysctl_err(path
, table
, "array not allowed");
1114 static int sysctl_check_table(const char *path
, struct ctl_table
*table
)
1117 for (; table
->procname
; table
++) {
1119 err
|= sysctl_err(path
, table
, "Not a file");
1121 if ((table
->proc_handler
== proc_dostring
) ||
1122 (table
->proc_handler
== proc_dointvec
) ||
1123 (table
->proc_handler
== proc_douintvec
) ||
1124 (table
->proc_handler
== proc_douintvec_minmax
) ||
1125 (table
->proc_handler
== proc_dointvec_minmax
) ||
1126 (table
->proc_handler
== proc_dou8vec_minmax
) ||
1127 (table
->proc_handler
== proc_dointvec_jiffies
) ||
1128 (table
->proc_handler
== proc_dointvec_userhz_jiffies
) ||
1129 (table
->proc_handler
== proc_dointvec_ms_jiffies
) ||
1130 (table
->proc_handler
== proc_doulongvec_minmax
) ||
1131 (table
->proc_handler
== proc_doulongvec_ms_jiffies_minmax
)) {
1133 err
|= sysctl_err(path
, table
, "No data");
1135 err
|= sysctl_err(path
, table
, "No maxlen");
1137 err
|= sysctl_check_table_array(path
, table
);
1139 if (!table
->proc_handler
)
1140 err
|= sysctl_err(path
, table
, "No proc_handler");
1142 if ((table
->mode
& (S_IRUGO
|S_IWUGO
)) != table
->mode
)
1143 err
|= sysctl_err(path
, table
, "bogus .mode 0%o",
1149 static struct ctl_table_header
*new_links(struct ctl_dir
*dir
, struct ctl_table
*table
,
1150 struct ctl_table_root
*link_root
)
1152 struct ctl_table
*link_table
, *entry
, *link
;
1153 struct ctl_table_header
*links
;
1154 struct ctl_node
*node
;
1156 int nr_entries
, name_bytes
;
1160 for (entry
= table
; entry
->procname
; entry
++) {
1162 name_bytes
+= strlen(entry
->procname
) + 1;
1165 links
= kzalloc(sizeof(struct ctl_table_header
) +
1166 sizeof(struct ctl_node
)*nr_entries
+
1167 sizeof(struct ctl_table
)*(nr_entries
+ 1) +
1174 node
= (struct ctl_node
*)(links
+ 1);
1175 link_table
= (struct ctl_table
*)(node
+ nr_entries
);
1176 link_name
= (char *)&link_table
[nr_entries
+ 1];
1178 for (link
= link_table
, entry
= table
; entry
->procname
; link
++, entry
++) {
1179 int len
= strlen(entry
->procname
) + 1;
1180 memcpy(link_name
, entry
->procname
, len
);
1181 link
->procname
= link_name
;
1182 link
->mode
= S_IFLNK
|S_IRWXUGO
;
1183 link
->data
= link_root
;
1186 init_header(links
, dir
->header
.root
, dir
->header
.set
, node
, link_table
);
1187 links
->nreg
= nr_entries
;
1192 static bool get_links(struct ctl_dir
*dir
,
1193 struct ctl_table
*table
, struct ctl_table_root
*link_root
)
1195 struct ctl_table_header
*head
;
1196 struct ctl_table
*entry
, *link
;
1198 /* Are there links available for every entry in table? */
1199 for (entry
= table
; entry
->procname
; entry
++) {
1200 const char *procname
= entry
->procname
;
1201 link
= find_entry(&head
, dir
, procname
, strlen(procname
));
1204 if (S_ISDIR(link
->mode
) && S_ISDIR(entry
->mode
))
1206 if (S_ISLNK(link
->mode
) && (link
->data
== link_root
))
1211 /* The checks passed. Increase the registration count on the links */
1212 for (entry
= table
; entry
->procname
; entry
++) {
1213 const char *procname
= entry
->procname
;
1214 link
= find_entry(&head
, dir
, procname
, strlen(procname
));
1220 static int insert_links(struct ctl_table_header
*head
)
1222 struct ctl_table_set
*root_set
= &sysctl_table_root
.default_set
;
1223 struct ctl_dir
*core_parent
= NULL
;
1224 struct ctl_table_header
*links
;
1227 if (head
->set
== root_set
)
1230 core_parent
= xlate_dir(root_set
, head
->parent
);
1231 if (IS_ERR(core_parent
))
1234 if (get_links(core_parent
, head
->ctl_table
, head
->root
))
1237 core_parent
->header
.nreg
++;
1238 spin_unlock(&sysctl_lock
);
1240 links
= new_links(core_parent
, head
->ctl_table
, head
->root
);
1242 spin_lock(&sysctl_lock
);
1248 if (get_links(core_parent
, head
->ctl_table
, head
->root
)) {
1253 err
= insert_header(core_parent
, links
);
1257 drop_sysctl_table(&core_parent
->header
);
1262 * __register_sysctl_table - register a leaf sysctl table
1263 * @set: Sysctl tree to register on
1264 * @path: The path to the directory the sysctl table is in.
1265 * @table: the top-level table structure
1267 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1268 * array. A completely 0 filled entry terminates the table.
1270 * The members of the &struct ctl_table structure are used as follows:
1272 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
1273 * enter a sysctl file
1275 * data - a pointer to data for use by proc_handler
1277 * maxlen - the maximum size in bytes of the data
1279 * mode - the file permissions for the /proc/sys file
1281 * child - must be %NULL.
1283 * proc_handler - the text handler routine (described below)
1285 * extra1, extra2 - extra pointers usable by the proc handler routines
1287 * Leaf nodes in the sysctl tree will be represented by a single file
1288 * under /proc; non-leaf nodes will be represented by directories.
1290 * There must be a proc_handler routine for any terminal nodes.
1291 * Several default handlers are available to cover common cases -
1293 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
1294 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
1295 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
1297 * It is the handler's job to read the input buffer from user memory
1298 * and process it. The handler should return 0 on success.
1300 * This routine returns %NULL on a failure to register, and a pointer
1301 * to the table header on success.
1303 struct ctl_table_header
*__register_sysctl_table(
1304 struct ctl_table_set
*set
,
1305 const char *path
, struct ctl_table
*table
)
1307 struct ctl_table_root
*root
= set
->dir
.header
.root
;
1308 struct ctl_table_header
*header
;
1309 const char *name
, *nextname
;
1310 struct ctl_dir
*dir
;
1311 struct ctl_table
*entry
;
1312 struct ctl_node
*node
;
1315 for (entry
= table
; entry
->procname
; entry
++)
1318 header
= kzalloc(sizeof(struct ctl_table_header
) +
1319 sizeof(struct ctl_node
)*nr_entries
, GFP_KERNEL
);
1323 node
= (struct ctl_node
*)(header
+ 1);
1324 init_header(header
, root
, set
, node
, table
);
1325 if (sysctl_check_table(path
, table
))
1328 spin_lock(&sysctl_lock
);
1330 /* Reference moved down the diretory tree get_subdir */
1332 spin_unlock(&sysctl_lock
);
1334 /* Find the directory for the ctl_table */
1335 for (name
= path
; name
; name
= nextname
) {
1337 nextname
= strchr(name
, '/');
1339 namelen
= nextname
- name
;
1342 namelen
= strlen(name
);
1347 dir
= get_subdir(dir
, name
, namelen
);
1352 spin_lock(&sysctl_lock
);
1353 if (insert_header(dir
, header
))
1354 goto fail_put_dir_locked
;
1356 drop_sysctl_table(&dir
->header
);
1357 spin_unlock(&sysctl_lock
);
1361 fail_put_dir_locked
:
1362 drop_sysctl_table(&dir
->header
);
1363 spin_unlock(&sysctl_lock
);
1371 * register_sysctl - register a sysctl table
1372 * @path: The path to the directory the sysctl table is in.
1373 * @table: the table structure
1375 * Register a sysctl table. @table should be a filled in ctl_table
1376 * array. A completely 0 filled entry terminates the table.
1378 * See __register_sysctl_table for more details.
1380 struct ctl_table_header
*register_sysctl(const char *path
, struct ctl_table
*table
)
1382 return __register_sysctl_table(&sysctl_table_root
.default_set
,
1385 EXPORT_SYMBOL(register_sysctl
);
1387 static char *append_path(const char *path
, char *pos
, const char *name
)
1390 namelen
= strlen(name
);
1391 if (((pos
- path
) + namelen
+ 2) >= PATH_MAX
)
1393 memcpy(pos
, name
, namelen
);
1395 pos
[namelen
+ 1] = '\0';
1400 static int count_subheaders(struct ctl_table
*table
)
1403 int nr_subheaders
= 0;
1404 struct ctl_table
*entry
;
1406 /* special case: no directory and empty directory */
1407 if (!table
|| !table
->procname
)
1410 for (entry
= table
; entry
->procname
; entry
++) {
1412 nr_subheaders
+= count_subheaders(entry
->child
);
1416 return nr_subheaders
+ has_files
;
1419 static int register_leaf_sysctl_tables(const char *path
, char *pos
,
1420 struct ctl_table_header
***subheader
, struct ctl_table_set
*set
,
1421 struct ctl_table
*table
)
1423 struct ctl_table
*ctl_table_arg
= NULL
;
1424 struct ctl_table
*entry
, *files
;
1429 for (entry
= table
; entry
->procname
; entry
++) {
1437 /* If there are mixed files and directories we need a new table */
1438 if (nr_dirs
&& nr_files
) {
1439 struct ctl_table
*new;
1440 files
= kcalloc(nr_files
+ 1, sizeof(struct ctl_table
),
1445 ctl_table_arg
= files
;
1446 for (new = files
, entry
= table
; entry
->procname
; entry
++) {
1454 /* Register everything except a directory full of subdirectories */
1455 if (nr_files
|| !nr_dirs
) {
1456 struct ctl_table_header
*header
;
1457 header
= __register_sysctl_table(set
, path
, files
);
1459 kfree(ctl_table_arg
);
1463 /* Remember if we need to free the file table */
1464 header
->ctl_table_arg
= ctl_table_arg
;
1465 **subheader
= header
;
1469 /* Recurse into the subdirectories. */
1470 for (entry
= table
; entry
->procname
; entry
++) {
1476 err
= -ENAMETOOLONG
;
1477 child_pos
= append_path(path
, pos
, entry
->procname
);
1481 err
= register_leaf_sysctl_tables(path
, child_pos
, subheader
,
1489 /* On failure our caller will unregister all registered subheaders */
1494 * __register_sysctl_paths - register a sysctl table hierarchy
1495 * @set: Sysctl tree to register on
1496 * @path: The path to the directory the sysctl table is in.
1497 * @table: the top-level table structure
1499 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1500 * array. A completely 0 filled entry terminates the table.
1502 * See __register_sysctl_table for more details.
1504 struct ctl_table_header
*__register_sysctl_paths(
1505 struct ctl_table_set
*set
,
1506 const struct ctl_path
*path
, struct ctl_table
*table
)
1508 struct ctl_table
*ctl_table_arg
= table
;
1509 int nr_subheaders
= count_subheaders(table
);
1510 struct ctl_table_header
*header
= NULL
, **subheaders
, **subheader
;
1511 const struct ctl_path
*component
;
1512 char *new_path
, *pos
;
1514 pos
= new_path
= kmalloc(PATH_MAX
, GFP_KERNEL
);
1519 for (component
= path
; component
->procname
; component
++) {
1520 pos
= append_path(new_path
, pos
, component
->procname
);
1524 while (table
->procname
&& table
->child
&& !table
[1].procname
) {
1525 pos
= append_path(new_path
, pos
, table
->procname
);
1528 table
= table
->child
;
1530 if (nr_subheaders
== 1) {
1531 header
= __register_sysctl_table(set
, new_path
, table
);
1533 header
->ctl_table_arg
= ctl_table_arg
;
1535 header
= kzalloc(sizeof(*header
) +
1536 sizeof(*subheaders
)*nr_subheaders
, GFP_KERNEL
);
1540 subheaders
= (struct ctl_table_header
**) (header
+ 1);
1541 subheader
= subheaders
;
1542 header
->ctl_table_arg
= ctl_table_arg
;
1544 if (register_leaf_sysctl_tables(new_path
, pos
, &subheader
,
1546 goto err_register_leaves
;
1553 err_register_leaves
:
1554 while (subheader
> subheaders
) {
1555 struct ctl_table_header
*subh
= *(--subheader
);
1556 struct ctl_table
*table
= subh
->ctl_table_arg
;
1557 unregister_sysctl_table(subh
);
1566 * register_sysctl_paths - register a sysctl table hierarchy
1567 * @path: The path to the directory the sysctl table is in.
1568 * @table: the top-level table structure
1570 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1571 * array. A completely 0 filled entry terminates the table.
1573 * See __register_sysctl_paths for more details.
1575 struct ctl_table_header
*register_sysctl_paths(const struct ctl_path
*path
,
1576 struct ctl_table
*table
)
1578 return __register_sysctl_paths(&sysctl_table_root
.default_set
,
1581 EXPORT_SYMBOL(register_sysctl_paths
);
1584 * register_sysctl_table - register a sysctl table hierarchy
1585 * @table: the top-level table structure
1587 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
1588 * array. A completely 0 filled entry terminates the table.
1590 * See register_sysctl_paths for more details.
1592 struct ctl_table_header
*register_sysctl_table(struct ctl_table
*table
)
1594 static const struct ctl_path null_path
[] = { {} };
1596 return register_sysctl_paths(null_path
, table
);
1598 EXPORT_SYMBOL(register_sysctl_table
);
1600 static void put_links(struct ctl_table_header
*header
)
1602 struct ctl_table_set
*root_set
= &sysctl_table_root
.default_set
;
1603 struct ctl_table_root
*root
= header
->root
;
1604 struct ctl_dir
*parent
= header
->parent
;
1605 struct ctl_dir
*core_parent
;
1606 struct ctl_table
*entry
;
1608 if (header
->set
== root_set
)
1611 core_parent
= xlate_dir(root_set
, parent
);
1612 if (IS_ERR(core_parent
))
1615 for (entry
= header
->ctl_table
; entry
->procname
; entry
++) {
1616 struct ctl_table_header
*link_head
;
1617 struct ctl_table
*link
;
1618 const char *name
= entry
->procname
;
1620 link
= find_entry(&link_head
, core_parent
, name
, strlen(name
));
1622 ((S_ISDIR(link
->mode
) && S_ISDIR(entry
->mode
)) ||
1623 (S_ISLNK(link
->mode
) && (link
->data
== root
)))) {
1624 drop_sysctl_table(link_head
);
1627 pr_err("sysctl link missing during unregister: ");
1628 sysctl_print_dir(parent
);
1629 pr_cont("/%s\n", name
);
1634 static void drop_sysctl_table(struct ctl_table_header
*header
)
1636 struct ctl_dir
*parent
= header
->parent
;
1643 start_unregistering(header
);
1646 if (!--header
->count
)
1647 kfree_rcu(header
, rcu
);
1650 drop_sysctl_table(&parent
->header
);
1654 * unregister_sysctl_table - unregister a sysctl table hierarchy
1655 * @header: the header returned from register_sysctl_table
1657 * Unregisters the sysctl table and all children. proc entries may not
1658 * actually be removed until they are no longer used by anyone.
1660 void unregister_sysctl_table(struct ctl_table_header
* header
)
1668 nr_subheaders
= count_subheaders(header
->ctl_table_arg
);
1669 if (unlikely(nr_subheaders
> 1)) {
1670 struct ctl_table_header
**subheaders
;
1673 subheaders
= (struct ctl_table_header
**)(header
+ 1);
1674 for (i
= nr_subheaders
-1; i
>= 0; i
--) {
1675 struct ctl_table_header
*subh
= subheaders
[i
];
1676 struct ctl_table
*table
= subh
->ctl_table_arg
;
1677 unregister_sysctl_table(subh
);
1684 spin_lock(&sysctl_lock
);
1685 drop_sysctl_table(header
);
1686 spin_unlock(&sysctl_lock
);
1688 EXPORT_SYMBOL(unregister_sysctl_table
);
1690 void setup_sysctl_set(struct ctl_table_set
*set
,
1691 struct ctl_table_root
*root
,
1692 int (*is_seen
)(struct ctl_table_set
*))
1694 memset(set
, 0, sizeof(*set
));
1695 set
->is_seen
= is_seen
;
1696 init_header(&set
->dir
.header
, root
, set
, NULL
, root_table
);
1699 void retire_sysctl_set(struct ctl_table_set
*set
)
1701 WARN_ON(!RB_EMPTY_ROOT(&set
->dir
.root
));
1704 int __init
proc_sys_init(void)
1706 struct proc_dir_entry
*proc_sys_root
;
1708 proc_sys_root
= proc_mkdir("sys", NULL
);
1709 proc_sys_root
->proc_iops
= &proc_sys_dir_operations
;
1710 proc_sys_root
->proc_dir_ops
= &proc_sys_dir_file_operations
;
1711 proc_sys_root
->nlink
= 0;
1713 return sysctl_init();
1716 struct sysctl_alias
{
1717 const char *kernel_param
;
1718 const char *sysctl_param
;
1722 * Historically some settings had both sysctl and a command line parameter.
1723 * With the generic sysctl. parameter support, we can handle them at a single
1724 * place and only keep the historical name for compatibility. This is not meant
1725 * to add brand new aliases. When adding existing aliases, consider whether
1726 * the possibly different moment of changing the value (e.g. from early_param
1727 * to the moment do_sysctl_args() is called) is an issue for the specific
1730 static const struct sysctl_alias sysctl_aliases
[] = {
1731 {"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },
1732 {"hung_task_panic", "kernel.hung_task_panic" },
1733 {"numa_zonelist_order", "vm.numa_zonelist_order" },
1734 {"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },
1735 {"softlockup_panic", "kernel.softlockup_panic" },
1739 static const char *sysctl_find_alias(char *param
)
1741 const struct sysctl_alias
*alias
;
1743 for (alias
= &sysctl_aliases
[0]; alias
->kernel_param
!= NULL
; alias
++) {
1744 if (strcmp(alias
->kernel_param
, param
) == 0)
1745 return alias
->sysctl_param
;
1751 /* Set sysctl value passed on kernel command line. */
1752 static int process_sysctl_arg(char *param
, char *val
,
1753 const char *unused
, void *arg
)
1756 struct vfsmount
**proc_mnt
= arg
;
1757 struct file_system_type
*proc_fs_type
;
1764 if (strncmp(param
, "sysctl", sizeof("sysctl") - 1) == 0) {
1765 param
+= sizeof("sysctl") - 1;
1767 if (param
[0] != '/' && param
[0] != '.')
1772 param
= (char *) sysctl_find_alias(param
);
1784 * To set sysctl options, we use a temporary mount of proc, look up the
1785 * respective sys/ file and write to it. To avoid mounting it when no
1786 * options were given, we mount it only when the first sysctl option is
1787 * found. Why not a persistent mount? There are problems with a
1788 * persistent mount of proc in that it forces userspace not to use any
1789 * proc mount options.
1792 proc_fs_type
= get_fs_type("proc");
1793 if (!proc_fs_type
) {
1794 pr_err("Failed to find procfs to set sysctl from command line\n");
1797 *proc_mnt
= kern_mount(proc_fs_type
);
1798 put_filesystem(proc_fs_type
);
1799 if (IS_ERR(*proc_mnt
)) {
1800 pr_err("Failed to mount procfs to set sysctl from command line\n");
1805 path
= kasprintf(GFP_KERNEL
, "sys/%s", param
);
1807 panic("%s: Failed to allocate path for %s\n", __func__
, param
);
1808 strreplace(path
, '.', '/');
1810 file
= file_open_root_mnt(*proc_mnt
, path
, O_WRONLY
, 0);
1812 err
= PTR_ERR(file
);
1814 pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",
1816 else if (err
== -EACCES
)
1817 pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",
1820 pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",
1824 wret
= kernel_write(file
, val
, len
, &pos
);
1828 pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",
1831 pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",
1832 ERR_PTR(err
), param
, val
);
1833 } else if (wret
!= len
) {
1834 pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",
1835 wret
, len
, path
, param
, val
);
1838 err
= filp_close(file
, NULL
);
1840 pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",
1841 ERR_PTR(err
), param
, val
);
1847 void do_sysctl_args(void)
1850 struct vfsmount
*proc_mnt
= NULL
;
1852 command_line
= kstrdup(saved_command_line
, GFP_KERNEL
);
1854 panic("%s: Failed to allocate copy of command line\n", __func__
);
1856 parse_args("Setting sysctl args", command_line
,
1857 NULL
, 0, -1, -1, &proc_mnt
, process_sysctl_arg
);
1860 kern_unmount(proc_mnt
);
1862 kfree(command_line
);