original development tree for Linux kernel GTP module; now long in mainline.
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/*
* linux/fs/proc/inode.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
#include <linux/pid_namespace.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/completion.h>
#include <linux/poll.h>
#include <linux/printk.h>
#include <linux/file.h>
#include <linux/limits.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/magic.h>
#include <asm/uaccess.h>
#include "internal.h"
static void proc_evict_inode(struct inode *inode)
{
struct proc_dir_entry *de;
struct ctl_table_header *head;
const struct proc_ns_operations *ns_ops;
void *ns;
truncate_inode_pages(&inode->i_data, 0);
clear_inode(inode);
/* Stop tracking associated processes */
put_pid(PROC_I(inode)->pid);
/* Let go of any associated proc directory entry */
de = PROC_I(inode)->pde;
if (de)
pde_put(de);
head = PROC_I(inode)->sysctl;
if (head) {
rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
sysctl_head_put(head);
}
/* Release any associated namespace */
ns_ops = PROC_I(inode)->ns.ns_ops;
ns = PROC_I(inode)->ns.ns;
if (ns_ops && ns)
ns_ops->put(ns);
}
static struct kmem_cache * proc_inode_cachep;
static struct inode *proc_alloc_inode(struct super_block *sb)
{
struct proc_inode *ei;
struct inode *inode;
ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
if (!ei)
return NULL;
ei->pid = NULL;
ei->fd = 0;
ei->op.proc_get_link = NULL;
ei->pde = NULL;
ei->sysctl = NULL;
ei->sysctl_entry = NULL;
ei->ns.ns = NULL;
ei->ns.ns_ops = NULL;
inode = &ei->vfs_inode;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
return inode;
}
static void proc_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
kmem_cache_free(proc_inode_cachep, PROC_I(inode));
}
static void proc_destroy_inode(struct inode *inode)
{
call_rcu(&inode->i_rcu, proc_i_callback);
}
static void init_once(void *foo)
{
struct proc_inode *ei = (struct proc_inode *) foo;
inode_init_once(&ei->vfs_inode);
}
void __init proc_init_inodecache(void)
{
proc_inode_cachep = kmem_cache_create("proc_inode_cache",
sizeof(struct proc_inode),
0, (SLAB_RECLAIM_ACCOUNT|
SLAB_MEM_SPREAD|SLAB_PANIC),
init_once);
}
static int proc_show_options(struct seq_file *seq, struct dentry *root)
{
struct super_block *sb = root->d_sb;
struct pid_namespace *pid = sb->s_fs_info;
if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
if (pid->hide_pid != 0)
seq_printf(seq, ",hidepid=%u", pid->hide_pid);
return 0;
}
static const struct super_operations proc_sops = {
.alloc_inode = proc_alloc_inode,
.destroy_inode = proc_destroy_inode,
.drop_inode = generic_delete_inode,
.evict_inode = proc_evict_inode,
.statfs = simple_statfs,
.remount_fs = proc_remount,
.show_options = proc_show_options,
};
enum {BIAS = -1U<<31};
static inline int use_pde(struct proc_dir_entry *pde)
{
return atomic_inc_unless_negative(&pde->in_use);
}
static void unuse_pde(struct proc_dir_entry *pde)
{
if (atomic_dec_return(&pde->in_use) == BIAS)
complete(pde->pde_unload_completion);
}
/* pde is locked */
static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
{
if (pdeo->closing) {
/* somebody else is doing that, just wait */
DECLARE_COMPLETION_ONSTACK(c);
pdeo->c = &c;
spin_unlock(&pde->pde_unload_lock);
wait_for_completion(&c);
spin_lock(&pde->pde_unload_lock);
} else {
struct file *file;
pdeo->closing = 1;
spin_unlock(&pde->pde_unload_lock);
file = pdeo->file;
pde->proc_fops->release(file_inode(file), file);
spin_lock(&pde->pde_unload_lock);
list_del_init(&pdeo->lh);
if (pdeo->c)
complete(pdeo->c);
kfree(pdeo);
}
}
void proc_entry_rundown(struct proc_dir_entry *de)
{
DECLARE_COMPLETION_ONSTACK(c);
/* Wait until all existing callers into module are done. */
de->pde_unload_completion = &c;
if (atomic_add_return(BIAS, &de->in_use) != BIAS)
wait_for_completion(&c);
spin_lock(&de->pde_unload_lock);
while (!list_empty(&de->pde_openers)) {
struct pde_opener *pdeo;
pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
close_pdeo(de, pdeo);
}
spin_unlock(&de->pde_unload_lock);
}
static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
loff_t rv = -EINVAL;
if (use_pde(pde)) {
loff_t (*llseek)(struct file *, loff_t, int);
llseek = pde->proc_fops->llseek;
if (!llseek)
llseek = default_llseek;
rv = llseek(file, offset, whence);
unuse_pde(pde);
}
return rv;
}
static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;
if (use_pde(pde)) {
read = pde->proc_fops->read;
if (read)
rv = read(file, buf, count, ppos);
unuse_pde(pde);
}
return rv;
}
static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
struct proc_dir_entry *pde = PDE(file_inode(file));
ssize_t rv = -EIO;
if (use_pde(pde)) {
write = pde->proc_fops->write;
if (write)
rv = write(file, buf, count, ppos);
unuse_pde(pde);
}
return rv;
}
static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
unsigned int rv = DEFAULT_POLLMASK;
unsigned int (*poll)(struct file *, struct poll_table_struct *);
if (use_pde(pde)) {
poll = pde->proc_fops->poll;
if (poll)
rv = poll(file, pts);
unuse_pde(pde);
}
return rv;
}
static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
long rv = -ENOTTY;
long (*ioctl)(struct file *, unsigned int, unsigned long);
if (use_pde(pde)) {
ioctl = pde->proc_fops->unlocked_ioctl;
if (ioctl)
rv = ioctl(file, cmd, arg);
unuse_pde(pde);
}
return rv;
}
#ifdef CONFIG_COMPAT
static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
long rv = -ENOTTY;
long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
if (use_pde(pde)) {
compat_ioctl = pde->proc_fops->compat_ioctl;
if (compat_ioctl)
rv = compat_ioctl(file, cmd, arg);
unuse_pde(pde);
}
return rv;
}
#endif
static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
int rv = -EIO;
int (*mmap)(struct file *, struct vm_area_struct *);
if (use_pde(pde)) {
mmap = pde->proc_fops->mmap;
if (mmap)
rv = mmap(file, vma);
unuse_pde(pde);
}
return rv;
}
static unsigned long
proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
unsigned long len, unsigned long pgoff,
unsigned long flags)
{
struct proc_dir_entry *pde = PDE(file_inode(file));
unsigned long rv = -EIO;
if (use_pde(pde)) {
typeof(proc_reg_get_unmapped_area) *get_area;
get_area = pde->proc_fops->get_unmapped_area;
#ifdef CONFIG_MMU
if (!get_area)
get_area = current->mm->get_unmapped_area;
#endif
if (get_area)
rv = get_area(file, orig_addr, len, pgoff, flags);
else
rv = orig_addr;
unuse_pde(pde);
}
return rv;
}
static int proc_reg_open(struct inode *inode, struct file *file)
{
struct proc_dir_entry *pde = PDE(inode);
int rv = 0;
int (*open)(struct inode *, struct file *);
int (*release)(struct inode *, struct file *);
struct pde_opener *pdeo;
/*
* What for, you ask? Well, we can have open, rmmod, remove_proc_entry
* sequence. ->release won't be called because ->proc_fops will be
* cleared. Depending on complexity of ->release, consequences vary.
*
* We can't wait for mercy when close will be done for real, it's
* deadlockable: rmmod foo </proc/foo . So, we're going to do ->release
* by hand in remove_proc_entry(). For this, save opener's credentials
* for later.
*/
pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL);
if (!pdeo)
return -ENOMEM;
if (!use_pde(pde)) {
kfree(pdeo);
return -ENOENT;
}
open = pde->proc_fops->open;
release = pde->proc_fops->release;
if (open)
rv = open(inode, file);
if (rv == 0 && release) {
/* To know what to release. */
pdeo->file = file;
/* Strictly for "too late" ->release in proc_reg_release(). */
spin_lock(&pde->pde_unload_lock);
list_add(&pdeo->lh, &pde->pde_openers);
spin_unlock(&pde->pde_unload_lock);
} else
kfree(pdeo);
unuse_pde(pde);
return rv;
}
static int proc_reg_release(struct inode *inode, struct file *file)
{
struct proc_dir_entry *pde = PDE(inode);
struct pde_opener *pdeo;
spin_lock(&pde->pde_unload_lock);
list_for_each_entry(pdeo, &pde->pde_openers, lh) {
if (pdeo->file == file) {
close_pdeo(pde, pdeo);
break;
}
}
spin_unlock(&pde->pde_unload_lock);
return 0;
}
static const struct file_operations proc_reg_file_ops = {
.llseek = proc_reg_llseek,
.read = proc_reg_read,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = proc_reg_compat_ioctl,
#endif
.mmap = proc_reg_mmap,
.get_unmapped_area = proc_reg_get_unmapped_area,
.open = proc_reg_open,
.release = proc_reg_release,
};
#ifdef CONFIG_COMPAT
static const struct file_operations proc_reg_file_ops_no_compat = {
.llseek = proc_reg_llseek,
.read = proc_reg_read,
.write = proc_reg_write,
.poll = proc_reg_poll,
.unlocked_ioctl = proc_reg_unlocked_ioctl,
.mmap = proc_reg_mmap,
.get_unmapped_area = proc_reg_get_unmapped_area,
.open = proc_reg_open,
.release = proc_reg_release,
};
#endif
struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
{
struct inode *inode = new_inode_pseudo(sb);
if (inode) {
inode->i_ino = de->low_ino;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
PROC_I(inode)->pde = de;
if (de->mode) {
inode->i_mode = de->mode;
inode->i_uid = de->uid;
inode->i_gid = de->gid;
}
if (de->size)
inode->i_size = de->size;
if (de->nlink)
set_nlink(inode, de->nlink);
WARN_ON(!de->proc_iops);
inode->i_op = de->proc_iops;
if (de->proc_fops) {
if (S_ISREG(inode->i_mode)) {
#ifdef CONFIG_COMPAT
if (!de->proc_fops->compat_ioctl)
inode->i_fop =
&proc_reg_file_ops_no_compat;
else
#endif
inode->i_fop = &proc_reg_file_ops;
} else {
inode->i_fop = de->proc_fops;
}
}
} else
pde_put(de);
return inode;
}
int proc_fill_super(struct super_block *s)
{
struct inode *root_inode;
s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->s_magic = PROC_SUPER_MAGIC;
s->s_op = &proc_sops;
s->s_time_gran = 1;
pde_get(&proc_root);
root_inode = proc_get_inode(s, &proc_root);
if (!root_inode) {
pr_err("proc_fill_super: get root inode failed\n");
return -ENOMEM;
}
s->s_root = d_make_root(root_inode);
if (!s->s_root) {
pr_err("proc_fill_super: allocate dentry failed\n");
return -ENOMEM;
}
return proc_setup_self(s);
}