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/*
* /proc/sys support
*/
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include "internal.h"
static 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;
static struct inode *proc_sys_make_inode(struct super_block *sb,
struct ctl_table_header *head, struct ctl_table *table)
{
struct inode *inode;
struct proc_inode *ei;
inode = new_inode(sb);
if (!inode)
goto out;
sysctl_head_get(head);
ei = PROC_I(inode);
ei->sysctl = head;
ei->sysctl_entry = table;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
inode->i_flags |= S_PRIVATE; /* tell selinux to ignore this inode */
inode->i_mode = table->mode;
if (!table->child) {
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_nlink = 0;
inode->i_op = &proc_sys_dir_operations;
inode->i_fop = &proc_sys_dir_file_operations;
}
out:
return inode;
}
static struct ctl_table *find_in_table(struct ctl_table *p, struct qstr *name)
{
int len;
for ( ; p->ctl_name || p->procname; p++) {
if (!p->procname)
continue;
len = strlen(p->procname);
if (len != name->len)
continue;
if (memcmp(p->procname, name->name, len) != 0)
continue;
/* I have a match */
return p;
}
return NULL;
}
static struct ctl_table_header *grab_header(struct inode *inode)
{
if (PROC_I(inode)->sysctl)
return sysctl_head_grab(PROC_I(inode)->sysctl);
else
return sysctl_head_next(NULL);
}
static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct ctl_table_header *head = grab_header(dir);
struct ctl_table *table = PROC_I(dir)->sysctl_entry;
struct ctl_table_header *h = NULL;
struct qstr *name = &dentry->d_name;
struct ctl_table *p;
struct inode *inode;
struct dentry *err = ERR_PTR(-ENOENT);
if (IS_ERR(head))
return ERR_CAST(head);
if (table && !table->child) {
WARN_ON(1);
goto out;
}
table = table ? table->child : head->ctl_table;
p = find_in_table(table, name);
if (!p) {
for (h = sysctl_head_next(NULL); h; h = sysctl_head_next(h)) {
if (h->attached_to != table)
continue;
p = find_in_table(h->attached_by, name);
if (p)
break;
}
}
if (!p)
goto out;
err = ERR_PTR(-ENOMEM);
inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p);
if (h)
sysctl_head_finish(h);
if (!inode)
goto out;
err = NULL;
dentry->d_op = &proc_sys_dentry_operations;
d_add(dentry, inode);
out:
sysctl_head_finish(head);
return err;
}
static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
size_t count, loff_t *ppos, int write)
{
struct inode *inode = filp->f_path.dentry->d_inode;
struct ctl_table_header *head = grab_header(inode);
struct ctl_table *table = PROC_I(inode)->sysctl_entry;
ssize_t error;
size_t res;
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->root, 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;
/* careful: calling conventions are nasty here */
res = count;
error = table->proc_handler(table, write, filp, buf, &res, ppos);
if (!error)
error = res;
out:
sysctl_head_finish(head);
return error;
}
static ssize_t proc_sys_read(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
}
static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
size_t count, loff_t *ppos)
{
return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
}
static int proc_sys_fill_cache(struct file *filp, void *dirent,
filldir_t filldir,
struct ctl_table_header *head,
struct ctl_table *table)
{
struct dentry *child, *dir = filp->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(qname.name, qname.len);
child = d_lookup(dir, &qname);
if (!child) {
child = d_alloc(dir, &qname);
if (child) {
inode = proc_sys_make_inode(dir->d_sb, head, table);
if (!inode) {
dput(child);
return -ENOMEM;
} else {
child->d_op = &proc_sys_dentry_operations;
d_add(child, inode);
}
} else {
return -ENOMEM;
}
}
inode = child->d_inode;
ino = inode->i_ino;
type = inode->i_mode >> 12;
dput(child);
return !!filldir(dirent, qname.name, qname.len, filp->f_pos, ino, type);
}
static int scan(struct ctl_table_header *head, ctl_table *table,
unsigned long *pos, struct file *file,
void *dirent, filldir_t filldir)
{
for (; table->ctl_name || table->procname; table++, (*pos)++) {
int res;
/* Can't do anything without a proc name */
if
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