linux/fs/proc/proc_sysctl.c
Linus Torvalds adfd671676 sysctl-6.6-rc1
Long ago we set out to remove the kitchen sink on kernel/sysctl.c arrays and
 placings sysctls to their own sybsystem or file to help avoid merge conflicts.
 Matthew Wilcox pointed out though that if we're going to do that we might as
 well also *save* space while at it and try to remove the extra last sysctl
 entry added at the end of each array, a sentintel, instead of bloating the
 kernel by adding a new sentinel with each array moved.
 
 Doing that was not so trivial, and has required slowing down the moves of
 kernel/sysctl.c arrays and measuring the impact on size by each new move.
 
 The complex part of the effort to help reduce the size of each sysctl is being
 done by the patient work of el señor Don Joel Granados. A lot of this is truly
 painful code refactoring and testing and then trying to measure the savings of
 each move and removing the sentinels. Although Joel already has code which does
 most of this work, experience with sysctl moves in the past shows is we need to
 be careful due to the slew of odd build failures that are possible due to the
 amount of random Kconfig options sysctls use.
 
 To that end Joel's work is split by first addressing the major housekeeping
 needed to remove the sentinels, which is part of this merge request. The rest
 of the work to actually remove the sentinels will be done later in future
 kernel releases.
 
 At first I was only going to send his first 7 patches of his patch series,
 posted 1 month ago, but in retrospect due to the testing the changes have
 received in linux-next and the minor changes they make this goes with the
 entire set of patches Joel had planned: just sysctl house keeping. There are
 networking changes but these are part of the house keeping too.
 
 The preliminary math is showing this will all help reduce the overall build
 time size of the kernel and run time memory consumed by the kernel by about
 ~64 bytes per array where we are able to remove each sentinel in the future.
 That also means there is no more bloating the kernel with the extra ~64 bytes
 per array moved as no new sentinels are created.
 
 Most of this has been in linux-next for about a month, the last 7 patches took
 a minor refresh 2 week ago based on feedback.
 -----BEGIN PGP SIGNATURE-----
 
 iQJGBAABCgAwFiEENnNq2KuOejlQLZofziMdCjCSiKcFAmTuVnMSHG1jZ3JvZkBr
 ZXJuZWwub3JnAAoJEM4jHQowkoinIckP/imvRlfkO6L0IP7MmJBRPtwY01rsTAKO
 Q14dZ//bG4DVQeGl1FdzrF6hhuLgekU0qW1YDFIWiCXO7CbaxaNBPSUkeW6ReVoC
 R/VHNUPxSR1PWQy1OTJV2t4XKri2sB7ijmUsfsATtISwhei9bggTHEysShtP4tv+
 U87DzhoqMnbYIsfMo49KCqOa1Qm7TmjC1a7WAp6Fph3GJuXAzZR5pXpsd0NtOZ9x
 Ud5RT22icnQpMl7K+yPsqY6XcS5JkgBe/WbSzMAUkYZvBZFBq9t2D+OW5h9TZMhw
 piJWQ9X0Rm7qI2D15mJfXwaOhhyDhWci391hzdJmS6DI0prf6Ma2NFdAWOt/zomI
 uiRujS4bGeBUaK5F4TX2WQ1+jdMtAZ+0FncFnzt4U8q7dzUc91uVCm6iHW3gcfAb
 N7OEg2ZL0gkkgCZHqKxN8wpNQiC2KwnNk+HLAbnL2a/oJYfBtdopQmlxWfrN2hpF
 xxROiENqk483BRdMXDq6DR/gyDZmZWCobXIglSzlqCOjCOcLbDziIJ7pJk83ok09
 h/QnXTYHf9protBq9OIQesgh2pwNzBBLifK84KZLKcb7IbdIKjpQrW5STp04oNGf
 wcGJzEz8tXUe0UKyMM47AcHQGzIy6cdXNLjyF8a+m7rnZzr1ndnMqZyRStZzuQin
 AUg2VWHKPmW9
 =sq2p
 -----END PGP SIGNATURE-----

Merge tag 'sysctl-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "Long ago we set out to remove the kitchen sink on kernel/sysctl.c
  arrays and placings sysctls to their own sybsystem or file to help
  avoid merge conflicts. Matthew Wilcox pointed out though that if we're
  going to do that we might as well also *save* space while at it and
  try to remove the extra last sysctl entry added at the end of each
  array, a sentintel, instead of bloating the kernel by adding a new
  sentinel with each array moved.

  Doing that was not so trivial, and has required slowing down the moves
  of kernel/sysctl.c arrays and measuring the impact on size by each new
  move.

  The complex part of the effort to help reduce the size of each sysctl
  is being done by the patient work of el señor Don Joel Granados. A lot
  of this is truly painful code refactoring and testing and then trying
  to measure the savings of each move and removing the sentinels.
  Although Joel already has code which does most of this work,
  experience with sysctl moves in the past shows is we need to be
  careful due to the slew of odd build failures that are possible due to
  the amount of random Kconfig options sysctls use.

  To that end Joel's work is split by first addressing the major
  housekeeping needed to remove the sentinels, which is part of this
  merge request. The rest of the work to actually remove the sentinels
  will be done later in future kernel releases.

  The preliminary math is showing this will all help reduce the overall
  build time size of the kernel and run time memory consumed by the
  kernel by about ~64 bytes per array where we are able to remove each
  sentinel in the future. That also means there is no more bloating the
  kernel with the extra ~64 bytes per array moved as no new sentinels
  are created"

* tag 'sysctl-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  sysctl: Use ctl_table_size as stopping criteria for list macro
  sysctl: SIZE_MAX->ARRAY_SIZE in register_net_sysctl
  vrf: Update to register_net_sysctl_sz
  networking: Update to register_net_sysctl_sz
  netfilter: Update to register_net_sysctl_sz
  ax.25: Update to register_net_sysctl_sz
  sysctl: Add size to register_net_sysctl function
  sysctl: Add size arg to __register_sysctl_init
  sysctl: Add size to register_sysctl
  sysctl: Add a size arg to __register_sysctl_table
  sysctl: Add size argument to init_header
  sysctl: Add ctl_table_size to ctl_table_header
  sysctl: Use ctl_table_header in list_for_each_table_entry
  sysctl: Prefer ctl_table_header in proc_sysctl
2023-08-29 17:39:15 -07:00

1708 lines
44 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* /proc/sys support
*/
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/poll.h>
#include <linux/proc_fs.h>
#include <linux/printk.h>
#include <linux/security.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/mm.h>
#include <linux/uio.h>
#include <linux/module.h>
#include <linux/bpf-cgroup.h>
#include <linux/mount.h>
#include <linux/kmemleak.h>
#include "internal.h"
#define list_for_each_table_entry(entry, header) \
entry = header->ctl_table; \
for (size_t i = 0 ; i < header->ctl_table_size && entry->procname; ++i, entry++)
static const struct dentry_operations proc_sys_dentry_operations;
static const struct file_operations proc_sys_file_operations;
static const struct inode_operations proc_sys_inode_operations;
static const struct file_operations proc_sys_dir_file_operations;
static const struct inode_operations proc_sys_dir_operations;
/* Support for permanently empty directories */
static struct ctl_table sysctl_mount_point[] = {
{.type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY }
};
/**
* register_sysctl_mount_point() - registers a sysctl mount point
* @path: path for the mount point
*
* Used to create a permanently empty directory to serve as mount point.
* There are some subtle but important permission checks this allows in the
* case of unprivileged mounts.
*/
struct ctl_table_header *register_sysctl_mount_point(const char *path)
{
return register_sysctl_sz(path, sysctl_mount_point, 0);
}
EXPORT_SYMBOL(register_sysctl_mount_point);
#define sysctl_is_perm_empty_ctl_table(tptr) \
(tptr[0].type == SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
#define sysctl_is_perm_empty_ctl_header(hptr) \
(sysctl_is_perm_empty_ctl_table(hptr->ctl_table))
#define sysctl_set_perm_empty_ctl_header(hptr) \
(hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_PERMANENTLY_EMPTY)
#define sysctl_clear_perm_empty_ctl_header(hptr) \
(hptr->ctl_table[0].type = SYSCTL_TABLE_TYPE_DEFAULT)
void proc_sys_poll_notify(struct ctl_table_poll *poll)
{
if (!poll)
return;
atomic_inc(&poll->event);
wake_up_interruptible(&poll->wait);
}
static struct ctl_table root_table[] = {
{
.procname = "",
.mode = S_IFDIR|S_IRUGO|S_IXUGO,
},
{ }
};
static struct ctl_table_root sysctl_table_root = {
.default_set.dir.header = {
{{.count = 1,
.nreg = 1,
.ctl_table = root_table }},
.ctl_table_arg = root_table,
.root = &sysctl_table_root,
.set = &sysctl_table_root.default_set,
},
};
static DEFINE_SPINLOCK(sysctl_lock);
static void drop_sysctl_table(struct ctl_table_header *header);
static int sysctl_follow_link(struct ctl_table_header **phead,
struct ctl_table **pentry);
static int insert_links(struct ctl_table_header *head);
static void put_links(struct ctl_table_header *header);
static void sysctl_print_dir(struct ctl_dir *dir)
{
if (dir->header.parent)
sysctl_print_dir(dir->header.parent);
pr_cont("%s/", dir->header.ctl_table[0].procname);
}
static int namecmp(const char *name1, int len1, const char *name2, int len2)
{
int cmp;
cmp = memcmp(name1, name2, min(len1, len2));
if (cmp == 0)
cmp = len1 - len2;
return cmp;
}
/* Called under sysctl_lock */
static struct ctl_table *find_entry(struct ctl_table_header **phead,
struct ctl_dir *dir, const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
struct rb_node *node = dir->root.rb_node;
while (node)
{
struct ctl_node *ctl_node;
const char *procname;
int cmp;
ctl_node = rb_entry(node, struct ctl_node, node);
head = ctl_node->header;
entry = &head->ctl_table[ctl_node - head->node];
procname = entry->procname;
cmp = namecmp(name, namelen, procname, strlen(procname));
if (cmp < 0)
node = node->rb_left;
else if (cmp > 0)
node = node->rb_right;
else {
*phead = head;
return entry;
}
}
return NULL;
}
static int insert_entry(struct ctl_table_header *head, struct ctl_table *entry)
{
struct rb_node *node = &head->node[entry - head->ctl_table].node;
struct rb_node **p = &head->parent->root.rb_node;
struct rb_node *parent = NULL;
const char *name = entry->procname;
int namelen = strlen(name);
while (*p) {
struct ctl_table_header *parent_head;
struct ctl_table *parent_entry;
struct ctl_node *parent_node;
const char *parent_name;
int cmp;
parent = *p;
parent_node = rb_entry(parent, struct ctl_node, node);
parent_head = parent_node->header;
parent_entry = &parent_head->ctl_table[parent_node - parent_head->node];
parent_name = parent_entry->procname;
cmp = namecmp(name, namelen, parent_name, strlen(parent_name));
if (cmp < 0)
p = &(*p)->rb_left;
else if (cmp > 0)
p = &(*p)->rb_right;
else {
pr_err("sysctl duplicate entry: ");
sysctl_print_dir(head->parent);
pr_cont("%s\n", entry->procname);
return -EEXIST;
}
}
rb_link_node(node, parent, p);
rb_insert_color(node, &head->parent->root);
return 0;
}
static void erase_entry(struct ctl_table_header *head, struct ctl_table *entry)
{
struct rb_node *node = &head->node[entry - head->ctl_table].node;
rb_erase(node, &head->parent->root);
}
static void init_header(struct ctl_table_header *head,
struct ctl_table_root *root, struct ctl_table_set *set,
struct ctl_node *node, struct ctl_table *table, size_t table_size)
{
head->ctl_table = table;
head->ctl_table_size = table_size;
head->ctl_table_arg = table;
head->used = 0;
head->count = 1;
head->nreg = 1;
head->unregistering = NULL;
head->root = root;
head->set = set;
head->parent = NULL;
head->node = node;
INIT_HLIST_HEAD(&head->inodes);
if (node) {
struct ctl_table *entry;
list_for_each_table_entry(entry, head) {
node->header = head;
node++;
}
}
}
static void erase_header(struct ctl_table_header *head)
{
struct ctl_table *entry;
list_for_each_table_entry(entry, head)
erase_entry(head, entry);
}
static int insert_header(struct ctl_dir *dir, struct ctl_table_header *header)
{
struct ctl_table *entry;
struct ctl_table_header *dir_h = &dir->header;
int err;
/* Is this a permanently empty directory? */
if (sysctl_is_perm_empty_ctl_header(dir_h))
return -EROFS;
/* Am I creating a permanently empty directory? */
if (sysctl_is_perm_empty_ctl_table(header->ctl_table)) {
if (!RB_EMPTY_ROOT(&dir->root))
return -EINVAL;
sysctl_set_perm_empty_ctl_header(dir_h);
}
dir_h->nreg++;
header->parent = dir;
err = insert_links(header);
if (err)
goto fail_links;
list_for_each_table_entry(entry, header) {
err = insert_entry(header, entry);
if (err)
goto fail;
}
return 0;
fail:
erase_header(header);
put_links(header);
fail_links:
if (header->ctl_table == sysctl_mount_point)
sysctl_clear_perm_empty_ctl_header(dir_h);
header->parent = NULL;
drop_sysctl_table(dir_h);
return err;
}
/* called under sysctl_lock */
static int use_table(struct ctl_table_header *p)
{
if (unlikely(p->unregistering))
return 0;
p->used++;
return 1;
}
/* called under sysctl_lock */
static void unuse_table(struct ctl_table_header *p)
{
if (!--p->used)
if (unlikely(p->unregistering))
complete(p->unregistering);
}
static void proc_sys_invalidate_dcache(struct ctl_table_header *head)
{
proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock);
}
/* called under sysctl_lock, will reacquire if has to wait */
static void start_unregistering(struct ctl_table_header *p)
{
/*
* if p->used is 0, nobody will ever touch that entry again;
* we'll eliminate all paths to it before dropping sysctl_lock
*/
if (unlikely(p->used)) {
struct completion wait;
init_completion(&wait);
p->unregistering = &wait;
spin_unlock(&sysctl_lock);
wait_for_completion(&wait);
} else {
/* anything non-NULL; we'll never dereference it */
p->unregistering = ERR_PTR(-EINVAL);
spin_unlock(&sysctl_lock);
}
/*
* Invalidate dentries for unregistered sysctls: namespaced sysctls
* can have duplicate names and contaminate dcache very badly.
*/
proc_sys_invalidate_dcache(p);
/*
* do not remove from the list until nobody holds it; walking the
* list in do_sysctl() relies on that.
*/
spin_lock(&sysctl_lock);
erase_header(p);
}
static struct ctl_table_header *sysctl_head_grab(struct ctl_table_header *head)
{
BUG_ON(!head);
spin_lock(&sysctl_lock);
if (!use_table(head))
head = ERR_PTR(-ENOENT);
spin_unlock(&sysctl_lock);
return head;
}
static void sysctl_head_finish(struct ctl_table_header *head)
{
if (!head)
return;
spin_lock(&sysctl_lock);
unuse_table(head);
spin_unlock(&sysctl_lock);
}
static struct ctl_table_set *
lookup_header_set(struct ctl_table_root *root)
{
struct ctl_table_set *set = &root->default_set;
if (root->lookup)
set = root->lookup(root);
return set;
}
static struct ctl_table *lookup_entry(struct ctl_table_header **phead,
struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
spin_lock(&sysctl_lock);
entry = find_entry(&head, dir, name, namelen);
if (entry && use_table(head))
*phead = head;
else
entry = NULL;
spin_unlock(&sysctl_lock);
return entry;
}
static struct ctl_node *first_usable_entry(struct rb_node *node)
{
struct ctl_node *ctl_node;
for (;node; node = rb_next(node)) {
ctl_node = rb_entry(node, struct ctl_node, node);
if (use_table(ctl_node->header))
return ctl_node;
}
return NULL;
}
static void first_entry(struct ctl_dir *dir,
struct ctl_table_header **phead, struct ctl_table **pentry)
{
struct ctl_table_header *head = NULL;
struct ctl_table *entry = NULL;
struct ctl_node *ctl_node;
spin_lock(&sysctl_lock);
ctl_node = first_usable_entry(rb_first(&dir->root));
spin_unlock(&sysctl_lock);
if (ctl_node) {
head = ctl_node->header;
entry = &head->ctl_table[ctl_node - head->node];
}
*phead = head;
*pentry = entry;
}
static void next_entry(struct ctl_table_header **phead, struct ctl_table **pentry)
{
struct ctl_table_header *head = *phead;
struct ctl_table *entry = *pentry;
struct ctl_node *ctl_node = &head->node[entry - head->ctl_table];
spin_lock(&sysctl_lock);
unuse_table(head);
ctl_node = first_usable_entry(rb_next(&ctl_node->node));
spin_unlock(&sysctl_lock);
head = NULL;
if (ctl_node) {
head = ctl_node->header;
entry = &head->ctl_table[ctl_node - head->node];
}
*phead = head;
*pentry = entry;
}
/*
* sysctl_perm does NOT grant the superuser all rights automatically, because
* some sysctl variables are readonly even to root.
*/
static int test_perm(int mode, int op)
{
if (uid_eq(current_euid(), GLOBAL_ROOT_UID))
mode >>= 6;
else if (in_egroup_p(GLOBAL_ROOT_GID))
mode >>= 3;
if ((op & ~mode & (MAY_READ|MAY_WRITE|MAY_EXEC)) == 0)
return 0;
return -EACCES;
}
static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, int op)
{
struct ctl_table_root *root = head->root;
int mode;
if (root->permissions)
mode = root->permissions(head, table);
else
mode = table->mode;
return test_perm(mode, op);
}
static struct inode *proc_sys_make_inode(struct super_block *sb,
struct ctl_table_header *head, struct ctl_table *table)
{
struct ctl_table_root *root = head->root;
struct inode *inode;
struct proc_inode *ei;
inode = new_inode(sb);
if (!inode)
return ERR_PTR(-ENOMEM);
inode->i_ino = get_next_ino();
ei = PROC_I(inode);
spin_lock(&sysctl_lock);
if (unlikely(head->unregistering)) {
spin_unlock(&sysctl_lock);
iput(inode);
return ERR_PTR(-ENOENT);
}
ei->sysctl = head;
ei->sysctl_entry = table;
hlist_add_head_rcu(&ei->sibling_inodes, &head->inodes);
head->count++;
spin_unlock(&sysctl_lock);
inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
inode->i_mode = table->mode;
if (!S_ISDIR(table->mode)) {
inode->i_mode |= S_IFREG;
inode->i_op = &proc_sys_inode_operations;
inode->i_fop = &proc_sys_file_operations;
} else {
inode->i_mode |= S_IFDIR;
inode->i_op = &proc_sys_dir_operations;
inode->i_fop = &proc_sys_dir_file_operations;
if (sysctl_is_perm_empty_ctl_header(head))
make_empty_dir_inode(inode);
}
if (root->set_ownership)
root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);
else {
inode->i_uid = GLOBAL_ROOT_UID;
inode->i_gid = GLOBAL_ROOT_GID;
}
return inode;
}
void proc_sys_evict_inode(struct inode *inode, struct ctl_table_header *head)
{
spin_lock(&sysctl_lock);
hlist_del_init_rcu(&PROC_I(inode)->sibling_inodes);
if (!--head->count)
kfree_rcu(head, rcu);
spin_unlock(&sysctl_lock);
}
static struct ctl_table_header *grab_header(struct inode *inode)
{
struct ctl_table_header *head = PROC_I(inode)->sysctl;
if (!head)
head = &sysctl_table_root.default_set.dir.header;
return sysctl_head_grab(head);
}
static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct ctl_table_header *head = grab_header(dir);
struct ctl_table_header *h = NULL;
const struct qstr *name = &dentry->d_name;
struct ctl_table *p;
struct inode *inode;
struct dentry *err = ERR_PTR(-ENOENT);
struct ctl_dir *ctl_dir;
int ret;
if (IS_ERR(head))
return ERR_CAST(head);
ctl_dir = container_of(head, struct ctl_dir, header);
p = lookup_entry(&h, ctl_dir, name->name, name->len);
if (!p)
goto out;
if (S_ISLNK(p->mode)) {
ret = sysctl_follow_link(&h, &p);
err = ERR_PTR(ret);
if (ret)
goto out;
}
inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
if (IS_ERR(inode)) {
err = ERR_CAST(inode);
goto out;
}
d_set_d_op(dentry, &proc_sys_dentry_operations);
err = d_splice_alias(inode, dentry);
out:
if (h)
sysctl_head_finish(h);
sysctl_head_finish(head);
return err;
}
static ssize_t proc_sys_call_handler(struct kiocb *iocb, struct iov_iter *iter,
int write)
{
struct inode *inode = file_inode(iocb->ki_filp);
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
size_t count = iov_iter_count(iter);
char *kbuf;
ssize_t error;
if (IS_ERR(head))
return PTR_ERR(head);
/*
* At this point we know that the sysctl was not unregistered
* and won't be until we finish.
*/
error = -EPERM;
if (sysctl_perm(head, table, write ? MAY_WRITE : MAY_READ))
goto out;
/* if that can happen at all, it should be -EINVAL, not -EISDIR */
error = -EINVAL;
if (!table->proc_handler)
goto out;
/* don't even try if the size is too large */
error = -ENOMEM;
if (count >= KMALLOC_MAX_SIZE)
goto out;
kbuf = kvzalloc(count + 1, GFP_KERNEL);
if (!kbuf)
goto out;
if (write) {
error = -EFAULT;
if (!copy_from_iter_full(kbuf, count, iter))
goto out_free_buf;
kbuf[count] = '\0';
}
error = BPF_CGROUP_RUN_PROG_SYSCTL(head, table, write, &kbuf, &count,
&iocb->ki_pos);
if (error)
goto out_free_buf;
/* careful: calling conventions are nasty here */
error = table->proc_handler(table, write, kbuf, &count, &iocb->ki_pos);
if (error)
goto out_free_buf;
if (!write) {
error = -EFAULT;
if (copy_to_iter(kbuf, count, iter) < count)
goto out_free_buf;
}
error = count;
out_free_buf:
kvfree(kbuf);
out:
sysctl_head_finish(head);
return error;
}
static ssize_t proc_sys_read(struct kiocb *iocb, struct iov_iter *iter)
{
return proc_sys_call_handler(iocb, iter, 0);
}
static ssize_t proc_sys_write(struct kiocb *iocb, struct iov_iter *iter)
{
return proc_sys_call_handler(iocb, iter, 1);
}
static int proc_sys_open(struct inode *inode, struct file *filp)
{
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
/* sysctl was unregistered */
if (IS_ERR(head))
return PTR_ERR(head);
if (table->poll)
filp->private_data = proc_sys_poll_event(table->poll);
sysctl_head_finish(head);
return 0;
}
static __poll_t proc_sys_poll(struct file *filp, poll_table *wait)
{
struct inode *inode = file_inode(filp);
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
__poll_t ret = DEFAULT_POLLMASK;
unsigned long event;
/* sysctl was unregistered */
if (IS_ERR(head))
return EPOLLERR | EPOLLHUP;
if (!table->proc_handler)
goto out;
if (!table->poll)
goto out;
event = (unsigned long)filp->private_data;
poll_wait(filp, &table->poll->wait, wait);
if (event != atomic_read(&table->poll->event)) {
filp->private_data = proc_sys_poll_event(table->poll);
ret = EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI;
}
out:
sysctl_head_finish(head);
return ret;
}
static bool proc_sys_fill_cache(struct file *file,
struct dir_context *ctx,
struct ctl_table_header *head,
struct ctl_table *table)
{
struct dentry *child, *dir = file->f_path.dentry;
struct inode *inode;
struct qstr qname;
ino_t ino = 0;
unsigned type = DT_UNKNOWN;
qname.name = table->procname;
qname.len = strlen(table->procname);
qname.hash = full_name_hash(dir, qname.name, qname.len);
child = d_lookup(dir, &qname);
if (!child) {
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
child = d_alloc_parallel(dir, &qname, &wq);
if (IS_ERR(child))
return false;
if (d_in_lookup(child)) {
struct dentry *res;
inode = proc_sys_make_inode(dir->d_sb, head, table);
if (IS_ERR(inode)) {
d_lookup_done(child);
dput(child);
return false;
}
d_set_d_op(child, &proc_sys_dentry_operations);
res = d_splice_alias(inode, child);
d_lookup_done(child);
if (unlikely(res)) {
if (IS_ERR(res)) {
dput(child);
return false;
}
dput(child);
child = res;
}
}
}
inode = d_inode(child);
ino = inode->i_ino;
type = inode->i_mode >> 12;
dput(child);
return dir_emit(ctx, qname.name, qname.len, ino, type);
}
static bool proc_sys_link_fill_cache(struct file *file,
struct dir_context *ctx,
struct ctl_table_header *head,
struct ctl_table *table)
{
bool ret = true;
head = sysctl_head_grab(head);
if (IS_ERR(head))
return false;
/* It is not an error if we can not follow the link ignore it */
if (sysctl_follow_link(&head, &table))
goto out;
ret = proc_sys_fill_cache(file, ctx, head, table);
out:
sysctl_head_finish(head);
return ret;
}
static int scan(struct ctl_table_header *head, struct ctl_table *table,
unsigned long *pos, struct file *file,
struct dir_context *ctx)
{
bool res;
if ((*pos)++ < ctx->pos)
return true;
if (unlikely(S_ISLNK(table->mode)))
res = proc_sys_link_fill_cache(file, ctx, head, table);
else
res = proc_sys_fill_cache(file, ctx, head, table);
if (res)
ctx->pos = *pos;
return res;
}
static int proc_sys_readdir(struct file *file, struct dir_context *ctx)
{
struct ctl_table_header *head = grab_header(file_inode(file));
struct ctl_table_header *h = NULL;
struct ctl_table *entry;
struct ctl_dir *ctl_dir;
unsigned long pos;
if (IS_ERR(head))
return PTR_ERR(head);
ctl_dir = container_of(head, struct ctl_dir, header);
if (!dir_emit_dots(file, ctx))
goto out;
pos = 2;
for (first_entry(ctl_dir, &h, &entry); h; next_entry(&h, &entry)) {
if (!scan(h, entry, &pos, file, ctx)) {
sysctl_head_finish(h);
break;
}
}
out:
sysctl_head_finish(head);
return 0;
}
static int proc_sys_permission(struct mnt_idmap *idmap,
struct inode *inode, int mask)
{
/*
* sysctl entries that are not writeable,
* are _NOT_ writeable, capabilities or not.
*/
struct ctl_table_header *head;
struct ctl_table *table;
int error;
/* Executable files are not allowed under /proc/sys/ */
if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
return -EACCES;
head = grab_header(inode);
if (IS_ERR(head))
return PTR_ERR(head);
table = PROC_I(inode)->sysctl_entry;
if (!table) /* global root - r-xr-xr-x */
error = mask & MAY_WRITE ? -EACCES : 0;
else /* Use the permissions on the sysctl table entry */
error = sysctl_perm(head, table, mask & ~MAY_NOT_BLOCK);
sysctl_head_finish(head);
return error;
}
static int proc_sys_setattr(struct mnt_idmap *idmap,
struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
int error;
if (attr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
return -EPERM;
error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
if (error)
return error;
setattr_copy(&nop_mnt_idmap, inode, attr);
return 0;
}
static int proc_sys_getattr(struct mnt_idmap *idmap,
const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
struct inode *inode = d_inode(path->dentry);
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
if (IS_ERR(head))
return PTR_ERR(head);
generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat);
if (table)
stat->mode = (stat->mode & S_IFMT) | table->mode;
sysctl_head_finish(head);
return 0;
}
static const struct file_operations proc_sys_file_operations = {
.open = proc_sys_open,
.poll = proc_sys_poll,
.read_iter = proc_sys_read,
.write_iter = proc_sys_write,
.splice_read = copy_splice_read,
.splice_write = iter_file_splice_write,
.llseek = default_llseek,
};
static const struct file_operations proc_sys_dir_file_operations = {
.read = generic_read_dir,
.iterate_shared = proc_sys_readdir,
.llseek = generic_file_llseek,
};
static const struct inode_operations proc_sys_inode_operations = {
.permission = proc_sys_permission,
.setattr = proc_sys_setattr,
.getattr = proc_sys_getattr,
};
static const struct inode_operations proc_sys_dir_operations = {
.lookup = proc_sys_lookup,
.permission = proc_sys_permission,
.setattr = proc_sys_setattr,
.getattr = proc_sys_getattr,
};
static int proc_sys_revalidate(struct dentry *dentry, unsigned int flags)
{
if (flags & LOOKUP_RCU)
return -ECHILD;
return !PROC_I(d_inode(dentry))->sysctl->unregistering;
}
static int proc_sys_delete(const struct dentry *dentry)
{
return !!PROC_I(d_inode(dentry))->sysctl->unregistering;
}
static int sysctl_is_seen(struct ctl_table_header *p)
{
struct ctl_table_set *set = p->set;
int res;
spin_lock(&sysctl_lock);
if (p->unregistering)
res = 0;
else if (!set->is_seen)
res = 1;
else
res = set->is_seen(set);
spin_unlock(&sysctl_lock);
return res;
}
static int proc_sys_compare(const struct dentry *dentry,
unsigned int len, const char *str, const struct qstr *name)
{
struct ctl_table_header *head;
struct inode *inode;
/* Although proc doesn't have negative dentries, rcu-walk means
* that inode here can be NULL */
/* AV: can it, indeed? */
inode = d_inode_rcu(dentry);
if (!inode)
return 1;
if (name->len != len)
return 1;
if (memcmp(name->name, str, len))
return 1;
head = rcu_dereference(PROC_I(inode)->sysctl);
return !head || !sysctl_is_seen(head);
}
static const struct dentry_operations proc_sys_dentry_operations = {
.d_revalidate = proc_sys_revalidate,
.d_delete = proc_sys_delete,
.d_compare = proc_sys_compare,
};
static struct ctl_dir *find_subdir(struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_header *head;
struct ctl_table *entry;
entry = find_entry(&head, dir, name, namelen);
if (!entry)
return ERR_PTR(-ENOENT);
if (!S_ISDIR(entry->mode))
return ERR_PTR(-ENOTDIR);
return container_of(head, struct ctl_dir, header);
}
static struct ctl_dir *new_dir(struct ctl_table_set *set,
const char *name, int namelen)
{
struct ctl_table *table;
struct ctl_dir *new;
struct ctl_node *node;
char *new_name;
new = kzalloc(sizeof(*new) + sizeof(struct ctl_node) +
sizeof(struct ctl_table)*2 + namelen + 1,
GFP_KERNEL);
if (!new)
return NULL;
node = (struct ctl_node *)(new + 1);
table = (struct ctl_table *)(node + 1);
new_name = (char *)(table + 2);
memcpy(new_name, name, namelen);
table[0].procname = new_name;
table[0].mode = S_IFDIR|S_IRUGO|S_IXUGO;
init_header(&new->header, set->dir.header.root, set, node, table, 1);
return new;
}
/**
* get_subdir - find or create a subdir with the specified name.
* @dir: Directory to create the subdirectory in
* @name: The name of the subdirectory to find or create
* @namelen: The length of name
*
* Takes a directory with an elevated reference count so we know that
* if we drop the lock the directory will not go away. Upon success
* the reference is moved from @dir to the returned subdirectory.
* Upon error an error code is returned and the reference on @dir is
* simply dropped.
*/
static struct ctl_dir *get_subdir(struct ctl_dir *dir,
const char *name, int namelen)
{
struct ctl_table_set *set = dir->header.set;
struct ctl_dir *subdir, *new = NULL;
int err;
spin_lock(&sysctl_lock);
subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
spin_unlock(&sysctl_lock);
new = new_dir(set, name, namelen);
spin_lock(&sysctl_lock);
subdir = ERR_PTR(-ENOMEM);
if (!new)
goto failed;
/* Was the subdir added while we dropped the lock? */
subdir = find_subdir(dir, name, namelen);
if (!IS_ERR(subdir))
goto found;
if (PTR_ERR(subdir) != -ENOENT)
goto failed;
/* Nope. Use the our freshly made directory entry. */
err = insert_header(dir, &new->header);
subdir = ERR_PTR(err);
if (err)
goto failed;
subdir = new;
found:
subdir->header.nreg++;
failed:
if (IS_ERR(subdir)) {
pr_err("sysctl could not get directory: ");
sysctl_print_dir(dir);
pr_cont("%*.*s %ld\n", namelen, namelen, name,
PTR_ERR(subdir));
}
drop_sysctl_table(&dir->header);
if (new)
drop_sysctl_table(&new->header);
spin_unlock(&sysctl_lock);
return subdir;
}
static struct ctl_dir *xlate_dir(struct ctl_table_set *set, struct ctl_dir *dir)
{
struct ctl_dir *parent;
const char *procname;
if (!dir->header.parent)
return &set->dir;
parent = xlate_dir(set, dir->header.parent);
if (IS_ERR(parent))
return parent;
procname = dir->header.ctl_table[0].procname;
return find_subdir(parent, procname, strlen(procname));
}
static int sysctl_follow_link(struct ctl_table_header **phead,
struct ctl_table **pentry)
{
struct ctl_table_header *head;
struct ctl_table_root *root;
struct ctl_table_set *set;
struct ctl_table *entry;
struct ctl_dir *dir;
int ret;
spin_lock(&sysctl_lock);
root = (*pentry)->data;
set = lookup_header_set(root);
dir = xlate_dir(set, (*phead)->parent);
if (IS_ERR(dir))
ret = PTR_ERR(dir);
else {
const char *procname = (*pentry)->procname;
head = NULL;
entry = find_entry(&head, dir, procname, strlen(procname));
ret = -ENOENT;
if (entry && use_table(head)) {
unuse_table(*phead);
*phead = head;
*pentry = entry;
ret = 0;
}
}
spin_unlock(&sysctl_lock);
return ret;
}
static int sysctl_err(const char *path, struct ctl_table *table, char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_err("sysctl table check failed: %s/%s %pV\n",
path, table->procname, &vaf);
va_end(args);
return -EINVAL;
}
static int sysctl_check_table_array(const char *path, struct ctl_table *table)
{
int err = 0;
if ((table->proc_handler == proc_douintvec) ||
(table->proc_handler == proc_douintvec_minmax)) {
if (table->maxlen != sizeof(unsigned int))
err |= sysctl_err(path, table, "array not allowed");
}
if (table->proc_handler == proc_dou8vec_minmax) {
if (table->maxlen != sizeof(u8))
err |= sysctl_err(path, table, "array not allowed");
}
if (table->proc_handler == proc_dobool) {
if (table->maxlen != sizeof(bool))
err |= sysctl_err(path, table, "array not allowed");
}
return err;
}
static int sysctl_check_table(const char *path, struct ctl_table_header *header)
{
struct ctl_table *entry;
int err = 0;
list_for_each_table_entry(entry, header) {
if ((entry->proc_handler == proc_dostring) ||
(entry->proc_handler == proc_dobool) ||
(entry->proc_handler == proc_dointvec) ||
(entry->proc_handler == proc_douintvec) ||
(entry->proc_handler == proc_douintvec_minmax) ||
(entry->proc_handler == proc_dointvec_minmax) ||
(entry->proc_handler == proc_dou8vec_minmax) ||
(entry->proc_handler == proc_dointvec_jiffies) ||
(entry->proc_handler == proc_dointvec_userhz_jiffies) ||
(entry->proc_handler == proc_dointvec_ms_jiffies) ||
(entry->proc_handler == proc_doulongvec_minmax) ||
(entry->proc_handler == proc_doulongvec_ms_jiffies_minmax)) {
if (!entry->data)
err |= sysctl_err(path, entry, "No data");
if (!entry->maxlen)
err |= sysctl_err(path, entry, "No maxlen");
else
err |= sysctl_check_table_array(path, entry);
}
if (!entry->proc_handler)
err |= sysctl_err(path, entry, "No proc_handler");
if ((entry->mode & (S_IRUGO|S_IWUGO)) != entry->mode)
err |= sysctl_err(path, entry, "bogus .mode 0%o",
entry->mode);
}
return err;
}
static struct ctl_table_header *new_links(struct ctl_dir *dir, struct ctl_table_header *head)
{
struct ctl_table *link_table, *entry, *link;
struct ctl_table_header *links;
struct ctl_node *node;
char *link_name;
int nr_entries, name_bytes;
name_bytes = 0;
nr_entries = 0;
list_for_each_table_entry(entry, head) {
nr_entries++;
name_bytes += strlen(entry->procname) + 1;
}
links = kzalloc(sizeof(struct ctl_table_header) +
sizeof(struct ctl_node)*nr_entries +
sizeof(struct ctl_table)*(nr_entries + 1) +
name_bytes,
GFP_KERNEL);
if (!links)
return NULL;
node = (struct ctl_node *)(links + 1);
link_table = (struct ctl_table *)(node + nr_entries);
link_name = (char *)&link_table[nr_entries + 1];
link = link_table;
list_for_each_table_entry(entry, head) {
int len = strlen(entry->procname) + 1;
memcpy(link_name, entry->procname, len);
link->procname = link_name;
link->mode = S_IFLNK|S_IRWXUGO;
link->data = head->root;
link_name += len;
link++;
}
init_header(links, dir->header.root, dir->header.set, node, link_table,
head->ctl_table_size);
links->nreg = nr_entries;
return links;
}
static bool get_links(struct ctl_dir *dir,
struct ctl_table_header *header,
struct ctl_table_root *link_root)
{
struct ctl_table_header *tmp_head;
struct ctl_table *entry, *link;
/* Are there links available for every entry in table? */
list_for_each_table_entry(entry, header) {
const char *procname = entry->procname;
link = find_entry(&tmp_head, dir, procname, strlen(procname));
if (!link)
return false;
if (S_ISDIR(link->mode) && S_ISDIR(entry->mode))
continue;
if (S_ISLNK(link->mode) && (link->data == link_root))
continue;
return false;
}
/* The checks passed. Increase the registration count on the links */
list_for_each_table_entry(entry, header) {
const char *procname = entry->procname;
link = find_entry(&tmp_head, dir, procname, strlen(procname));
tmp_head->nreg++;
}
return true;
}
static int insert_links(struct ctl_table_header *head)
{
struct ctl_table_set *root_set = &sysctl_table_root.default_set;
struct ctl_dir *core_parent;
struct ctl_table_header *links;
int err;
if (head->set == root_set)
return 0;
core_parent = xlate_dir(root_set, head->parent);
if (IS_ERR(core_parent))
return 0;
if (get_links(core_parent, head, head->root))
return 0;
core_parent->header.nreg++;
spin_unlock(&sysctl_lock);
links = new_links(core_parent, head);
spin_lock(&sysctl_lock);
err = -ENOMEM;
if (!links)
goto out;
err = 0;
if (get_links(core_parent, head, head->root)) {
kfree(links);
goto out;
}
err = insert_header(core_parent, links);
if (err)
kfree(links);
out:
drop_sysctl_table(&core_parent->header);
return err;
}
/* Find the directory for the ctl_table. If one is not found create it. */
static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
{
const char *name, *nextname;
for (name = path; name; name = nextname) {
int namelen;
nextname = strchr(name, '/');
if (nextname) {
namelen = nextname - name;
nextname++;
} else {
namelen = strlen(name);
}
if (namelen == 0)
continue;
/*
* namelen ensures if name is "foo/bar/yay" only foo is
* registered first. We traverse as if using mkdir -p and
* return a ctl_dir for the last directory entry.
*/
dir = get_subdir(dir, name, namelen);
if (IS_ERR(dir))
break;
}
return dir;
}
/**
* __register_sysctl_table - register a leaf sysctl table
* @set: Sysctl tree to register on
* @path: The path to the directory the sysctl table is in.
* @table: the top-level table structure without any child. This table
* should not be free'd after registration. So it should not be
* used on stack. It can either be a global or dynamically allocated
* by the caller and free'd later after sysctl unregistration.
* @table_size : The number of elements in table
*
* Register a sysctl table hierarchy. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* The members of the &struct ctl_table structure are used as follows:
*
* procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
* enter a sysctl file
*
* data - a pointer to data for use by proc_handler
*
* maxlen - the maximum size in bytes of the data
*
* mode - the file permissions for the /proc/sys file
*
* child - must be %NULL.
*
* proc_handler - the text handler routine (described below)
*
* extra1, extra2 - extra pointers usable by the proc handler routines
* XXX: we should eventually modify these to use long min / max [0]
* [0] https://lkml.kernel.org/87zgpte9o4.fsf@email.froward.int.ebiederm.org
*
* Leaf nodes in the sysctl tree will be represented by a single file
* under /proc; non-leaf nodes (where child is not NULL) are not allowed,
* sysctl_check_table() verifies this.
*
* There must be a proc_handler routine for any terminal nodes.
* Several default handlers are available to cover common cases -
*
* proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
* proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(),
* proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
*
* It is the handler's job to read the input buffer from user memory
* and process it. The handler should return 0 on success.
*
* This routine returns %NULL on a failure to register, and a pointer
* to the table header on success.
*/
struct ctl_table_header *__register_sysctl_table(
struct ctl_table_set *set,
const char *path, struct ctl_table *table, size_t table_size)
{
struct ctl_table_root *root = set->dir.header.root;
struct ctl_table_header *header;
struct ctl_dir *dir;
struct ctl_node *node;
header = kzalloc(sizeof(struct ctl_table_header) +
sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);
if (!header)
return NULL;
node = (struct ctl_node *)(header + 1);
init_header(header, root, set, node, table, table_size);
if (sysctl_check_table(path, header))
goto fail;
spin_lock(&sysctl_lock);
dir = &set->dir;
/* Reference moved down the directory tree get_subdir */
dir->header.nreg++;
spin_unlock(&sysctl_lock);
dir = sysctl_mkdir_p(dir, path);
if (IS_ERR(dir))
goto fail;
spin_lock(&sysctl_lock);
if (insert_header(dir, header))
goto fail_put_dir_locked;
drop_sysctl_table(&dir->header);
spin_unlock(&sysctl_lock);
return header;
fail_put_dir_locked:
drop_sysctl_table(&dir->header);
spin_unlock(&sysctl_lock);
fail:
kfree(header);
return NULL;
}
/**
* register_sysctl_sz - register a sysctl table
* @path: The path to the directory the sysctl table is in. If the path
* doesn't exist we will create it for you.
* @table: the table structure. The calller must ensure the life of the @table
* will be kept during the lifetime use of the syctl. It must not be freed
* until unregister_sysctl_table() is called with the given returned table
* with this registration. If your code is non modular then you don't need
* to call unregister_sysctl_table() and can instead use something like
* register_sysctl_init() which does not care for the result of the syctl
* registration.
* @table_size: The number of elements in table.
*
* Register a sysctl table. @table should be a filled in ctl_table
* array. A completely 0 filled entry terminates the table.
*
* See __register_sysctl_table for more details.
*/
struct ctl_table_header *register_sysctl_sz(const char *path, struct ctl_table *table,
size_t table_size)
{
return __register_sysctl_table(&sysctl_table_root.default_set,
path, table, table_size);
}
EXPORT_SYMBOL(register_sysctl_sz);
/**
* __register_sysctl_init() - register sysctl table to path
* @path: path name for sysctl base. If that path doesn't exist we will create
* it for you.
* @table: This is the sysctl table that needs to be registered to the path.
* The caller must ensure the life of the @table will be kept during the
* lifetime use of the sysctl.
* @table_name: The name of sysctl table, only used for log printing when
* registration fails
* @table_size: The number of elements in table
*
* The sysctl interface is used by userspace to query or modify at runtime
* a predefined value set on a variable. These variables however have default
* values pre-set. Code which depends on these variables will always work even
* if register_sysctl() fails. If register_sysctl() fails you'd just loose the
* ability to query or modify the sysctls dynamically at run time. Chances of
* register_sysctl() failing on init are extremely low, and so for both reasons
* this function does not return any error as it is used by initialization code.
*
* Context: if your base directory does not exist it will be created for you.
*/
void __init __register_sysctl_init(const char *path, struct ctl_table *table,
const char *table_name, size_t table_size)
{
struct ctl_table_header *hdr = register_sysctl_sz(path, table, table_size);
if (unlikely(!hdr)) {
pr_err("failed when register_sysctl_sz %s to %s\n", table_name, path);
return;
}
kmemleak_not_leak(hdr);
}
static void put_links(struct ctl_table_header *header)
{
struct ctl_table_set *root_set = &sysctl_table_root.default_set;
struct ctl_table_root *root = header->root;
struct ctl_dir *parent = header->parent;
struct ctl_dir *core_parent;
struct ctl_table *entry;
if (header->set == root_set)
return;
core_parent = xlate_dir(root_set, parent);
if (IS_ERR(core_parent))
return;
list_for_each_table_entry(entry, header) {
struct ctl_table_header *link_head;
struct ctl_table *link;
const char *name = entry->procname;
link = find_entry(&link_head, core_parent, name, strlen(name));
if (link &&
((S_ISDIR(link->mode) && S_ISDIR(entry->mode)) ||
(S_ISLNK(link->mode) && (link->data == root)))) {
drop_sysctl_table(link_head);
}
else {
pr_err("sysctl link missing during unregister: ");
sysctl_print_dir(parent);
pr_cont("%s\n", name);
}
}
}
static void drop_sysctl_table(struct ctl_table_header *header)
{
struct ctl_dir *parent = header->parent;
if (--header->nreg)
return;
if (parent) {
put_links(header);
start_unregistering(header);
}
if (!--header->count)
kfree_rcu(header, rcu);
if (parent)
drop_sysctl_table(&parent->header);
}
/**
* unregister_sysctl_table - unregister a sysctl table hierarchy
* @header: the header returned from register_sysctl or __register_sysctl_table
*
* Unregisters the sysctl table and all children. proc entries may not
* actually be removed until they are no longer used by anyone.
*/
void unregister_sysctl_table(struct ctl_table_header * header)
{
might_sleep();
if (header == NULL)
return;
spin_lock(&sysctl_lock);
drop_sysctl_table(header);
spin_unlock(&sysctl_lock);
}
EXPORT_SYMBOL(unregister_sysctl_table);
void setup_sysctl_set(struct ctl_table_set *set,
struct ctl_table_root *root,
int (*is_seen)(struct ctl_table_set *))
{
memset(set, 0, sizeof(*set));
set->is_seen = is_seen;
init_header(&set->dir.header, root, set, NULL, root_table, 1);
}
void retire_sysctl_set(struct ctl_table_set *set)
{
WARN_ON(!RB_EMPTY_ROOT(&set->dir.root));
}
int __init proc_sys_init(void)
{
struct proc_dir_entry *proc_sys_root;
proc_sys_root = proc_mkdir("sys", NULL);
proc_sys_root->proc_iops = &proc_sys_dir_operations;
proc_sys_root->proc_dir_ops = &proc_sys_dir_file_operations;
proc_sys_root->nlink = 0;
return sysctl_init_bases();
}
struct sysctl_alias {
const char *kernel_param;
const char *sysctl_param;
};
/*
* Historically some settings had both sysctl and a command line parameter.
* With the generic sysctl. parameter support, we can handle them at a single
* place and only keep the historical name for compatibility. This is not meant
* to add brand new aliases. When adding existing aliases, consider whether
* the possibly different moment of changing the value (e.g. from early_param
* to the moment do_sysctl_args() is called) is an issue for the specific
* parameter.
*/
static const struct sysctl_alias sysctl_aliases[] = {
{"hardlockup_all_cpu_backtrace", "kernel.hardlockup_all_cpu_backtrace" },
{"hung_task_panic", "kernel.hung_task_panic" },
{"numa_zonelist_order", "vm.numa_zonelist_order" },
{"softlockup_all_cpu_backtrace", "kernel.softlockup_all_cpu_backtrace" },
{"softlockup_panic", "kernel.softlockup_panic" },
{ }
};
static const char *sysctl_find_alias(char *param)
{
const struct sysctl_alias *alias;
for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) {
if (strcmp(alias->kernel_param, param) == 0)
return alias->sysctl_param;
}
return NULL;
}
/* Set sysctl value passed on kernel command line. */
static int process_sysctl_arg(char *param, char *val,
const char *unused, void *arg)
{
char *path;
struct vfsmount **proc_mnt = arg;
struct file_system_type *proc_fs_type;
struct file *file;
int len;
int err;
loff_t pos = 0;
ssize_t wret;
if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) {
param += sizeof("sysctl") - 1;
if (param[0] != '/' && param[0] != '.')
return 0;
param++;
} else {
param = (char *) sysctl_find_alias(param);
if (!param)
return 0;
}
if (!val)
return -EINVAL;
len = strlen(val);
if (len == 0)
return -EINVAL;
/*
* To set sysctl options, we use a temporary mount of proc, look up the
* respective sys/ file and write to it. To avoid mounting it when no
* options were given, we mount it only when the first sysctl option is
* found. Why not a persistent mount? There are problems with a
* persistent mount of proc in that it forces userspace not to use any
* proc mount options.
*/
if (!*proc_mnt) {
proc_fs_type = get_fs_type("proc");
if (!proc_fs_type) {
pr_err("Failed to find procfs to set sysctl from command line\n");
return 0;
}
*proc_mnt = kern_mount(proc_fs_type);
put_filesystem(proc_fs_type);
if (IS_ERR(*proc_mnt)) {
pr_err("Failed to mount procfs to set sysctl from command line\n");
return 0;
}
}
path = kasprintf(GFP_KERNEL, "sys/%s", param);
if (!path)
panic("%s: Failed to allocate path for %s\n", __func__, param);
strreplace(path, '.', '/');
file = file_open_root_mnt(*proc_mnt, path, O_WRONLY, 0);
if (IS_ERR(file)) {
err = PTR_ERR(file);
if (err == -ENOENT)
pr_err("Failed to set sysctl parameter '%s=%s': parameter not found\n",
param, val);
else if (err == -EACCES)
pr_err("Failed to set sysctl parameter '%s=%s': permission denied (read-only?)\n",
param, val);
else
pr_err("Error %pe opening proc file to set sysctl parameter '%s=%s'\n",
file, param, val);
goto out;
}
wret = kernel_write(file, val, len, &pos);
if (wret < 0) {
err = wret;
if (err == -EINVAL)
pr_err("Failed to set sysctl parameter '%s=%s': invalid value\n",
param, val);
else
pr_err("Error %pe writing to proc file to set sysctl parameter '%s=%s'\n",
ERR_PTR(err), param, val);
} else if (wret != len) {
pr_err("Wrote only %zd bytes of %d writing to proc file %s to set sysctl parameter '%s=%s\n",
wret, len, path, param, val);
}
err = filp_close(file, NULL);
if (err)
pr_err("Error %pe closing proc file to set sysctl parameter '%s=%s\n",
ERR_PTR(err), param, val);
out:
kfree(path);
return 0;
}
void do_sysctl_args(void)
{
char *command_line;
struct vfsmount *proc_mnt = NULL;
command_line = kstrdup(saved_command_line, GFP_KERNEL);
if (!command_line)
panic("%s: Failed to allocate copy of command line\n", __func__);
parse_args("Setting sysctl args", command_line,
NULL, 0, -1, -1, &proc_mnt, process_sysctl_arg);
if (proc_mnt)
kern_unmount(proc_mnt);
kfree(command_line);
}