linux-stable/fs/proc/inode.c
Pavel Emelyanov 07543f5c75 pid namespaces: make proc have multiple superblocks - one for each namespace
Each pid namespace have to be visible through its own proc mount.  Thus we
need to have per-namespace proc trees with their own superblocks.

We cannot easily show different pid namespace via one global proc tree, since
each pid refers to different tasks in different namespaces.  E.g.  pid 1
refers to the init task in the initial namespace and to some other task when
seeing from another namespace.  Moreover - pid, exisintg in one namespace may
not exist in the other.

This approach has one move advantage is that the tasks from the init namespace
can see what tasks live in another namespace by reading entries from another
proc tree.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 11:53:39 -07:00

479 lines
11 KiB
C

/*
* 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/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/completion.h>
#include <linux/poll.h>
#include <linux/file.h>
#include <linux/limits.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include "internal.h"
struct proc_dir_entry *de_get(struct proc_dir_entry *de)
{
if (de)
atomic_inc(&de->count);
return de;
}
/*
* Decrements the use count and checks for deferred deletion.
*/
void de_put(struct proc_dir_entry *de)
{
if (de) {
lock_kernel();
if (!atomic_read(&de->count)) {
printk("de_put: entry %s already free!\n", de->name);
unlock_kernel();
return;
}
if (atomic_dec_and_test(&de->count)) {
if (de->deleted) {
printk("de_put: deferred delete of %s\n",
de->name);
free_proc_entry(de);
}
}
unlock_kernel();
}
}
/*
* Decrement the use count of the proc_dir_entry.
*/
static void proc_delete_inode(struct inode *inode)
{
struct proc_dir_entry *de;
truncate_inode_pages(&inode->i_data, 0);
/* 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) {
if (de->owner)
module_put(de->owner);
de_put(de);
}
clear_inode(inode);
}
struct vfsmount *proc_mnt;
static void proc_read_inode(struct inode * inode)
{
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
}
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;
inode = &ei->vfs_inode;
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
return inode;
}
static void proc_destroy_inode(struct inode *inode)
{
kmem_cache_free(proc_inode_cachep, PROC_I(inode));
}
static void init_once(struct kmem_cache * cachep, void *foo)
{
struct proc_inode *ei = (struct proc_inode *) foo;
inode_init_once(&ei->vfs_inode);
}
int __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);
return 0;
}
static int proc_remount(struct super_block *sb, int *flags, char *data)
{
*flags |= MS_NODIRATIME;
return 0;
}
static const struct super_operations proc_sops = {
.alloc_inode = proc_alloc_inode,
.destroy_inode = proc_destroy_inode,
.read_inode = proc_read_inode,
.drop_inode = generic_delete_inode,
.delete_inode = proc_delete_inode,
.statfs = simple_statfs,
.remount_fs = proc_remount,
};
static void pde_users_dec(struct proc_dir_entry *pde)
{
spin_lock(&pde->pde_unload_lock);
pde->pde_users--;
if (pde->pde_unload_completion && pde->pde_users == 0)
complete(pde->pde_unload_completion);
spin_unlock(&pde->pde_unload_lock);
}
static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
{
struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
loff_t rv = -EINVAL;
loff_t (*llseek)(struct file *, loff_t, int);
spin_lock(&pde->pde_unload_lock);
/*
* remove_proc_entry() is going to delete PDE (as part of module
* cleanup sequence). No new callers into module allowed.
*/
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
/*
* Bump refcount so that remove_proc_entry will wail for ->llseek to
* complete.
*/
pde->pde_users++;
/*
* Save function pointer under lock, to protect against ->proc_fops
* NULL'ifying right after ->pde_unload_lock is dropped.
*/
llseek = pde->proc_fops->llseek;
spin_unlock(&pde->pde_unload_lock);
if (!llseek)
llseek = default_llseek;
rv = llseek(file, offset, whence);
pde_users_dec(pde);
return rv;
}
static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
ssize_t rv = -EIO;
ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
read = pde->proc_fops->read;
spin_unlock(&pde->pde_unload_lock);
if (read)
rv = read(file, buf, count, ppos);
pde_users_dec(pde);
return rv;
}
static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
ssize_t rv = -EIO;
ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
write = pde->proc_fops->write;
spin_unlock(&pde->pde_unload_lock);
if (write)
rv = write(file, buf, count, ppos);
pde_users_dec(pde);
return rv;
}
static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
{
struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
unsigned int rv = DEFAULT_POLLMASK;
unsigned int (*poll)(struct file *, struct poll_table_struct *);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
poll = pde->proc_fops->poll;
spin_unlock(&pde->pde_unload_lock);
if (poll)
rv = poll(file, pts);
pde_users_dec(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->f_path.dentry->d_inode);
long rv = -ENOTTY;
long (*unlocked_ioctl)(struct file *, unsigned int, unsigned long);
int (*ioctl)(struct inode *, struct file *, unsigned int, unsigned long);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
unlocked_ioctl = pde->proc_fops->unlocked_ioctl;
ioctl = pde->proc_fops->ioctl;
spin_unlock(&pde->pde_unload_lock);
if (unlocked_ioctl) {
rv = unlocked_ioctl(file, cmd, arg);
if (rv == -ENOIOCTLCMD)
rv = -EINVAL;
} else if (ioctl) {
lock_kernel();
rv = ioctl(file->f_path.dentry->d_inode, file, cmd, arg);
unlock_kernel();
}
pde_users_dec(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->f_path.dentry->d_inode);
long rv = -ENOTTY;
long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
compat_ioctl = pde->proc_fops->compat_ioctl;
spin_unlock(&pde->pde_unload_lock);
if (compat_ioctl)
rv = compat_ioctl(file, cmd, arg);
pde_users_dec(pde);
return rv;
}
#endif
static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
{
struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
int rv = -EIO;
int (*mmap)(struct file *, struct vm_area_struct *);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
mmap = pde->proc_fops->mmap;
spin_unlock(&pde->pde_unload_lock);
if (mmap)
rv = mmap(file, vma);
pde_users_dec(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 *);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
open = pde->proc_fops->open;
spin_unlock(&pde->pde_unload_lock);
if (open)
rv = open(inode, file);
pde_users_dec(pde);
return rv;
}
static int proc_reg_release(struct inode *inode, struct file *file)
{
struct proc_dir_entry *pde = PDE(inode);
int rv = 0;
int (*release)(struct inode *, struct file *);
spin_lock(&pde->pde_unload_lock);
if (!pde->proc_fops) {
spin_unlock(&pde->pde_unload_lock);
return rv;
}
pde->pde_users++;
release = pde->proc_fops->release;
spin_unlock(&pde->pde_unload_lock);
if (release)
rv = release(inode, file);
pde_users_dec(pde);
return rv;
}
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,
.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,
.open = proc_reg_open,
.release = proc_reg_release,
};
#endif
struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
struct proc_dir_entry *de)
{
struct inode * inode;
if (de != NULL && !try_module_get(de->owner))
goto out_mod;
inode = iget(sb, ino);
if (!inode)
goto out_ino;
PROC_I(inode)->fd = 0;
PROC_I(inode)->pde = de;
if (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)
inode->i_nlink = de->nlink;
if (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;
}
}
return inode;
out_ino:
if (de != NULL)
module_put(de->owner);
out_mod:
return NULL;
}
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;
de_get(&proc_root);
root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root);
if (!root_inode)
goto out_no_root;
root_inode->i_uid = 0;
root_inode->i_gid = 0;
s->s_root = d_alloc_root(root_inode);
if (!s->s_root)
goto out_no_root;
return 0;
out_no_root:
printk("proc_read_super: get root inode failed\n");
iput(root_inode);
de_put(&proc_root);
return -ENOMEM;
}
MODULE_LICENSE("GPL");