Commit bd9b51e7 authored by Al Viro's avatar Al Viro

make default ->i_fop have ->open() fail with ENXIO

As it is, default ->i_fop has NULL ->open() (along with all other methods).
The only case where it matters is reopening (via procfs symlink) a file that
didn't get its ->f_op from ->i_fop - anything else will have ->i_fop assigned
to something sane (default would fail on read/write/ioctl/etc.).

	Unfortunately, such case exists - alloc_file() users, especially
anon_get_file() ones.  There we have tons of opened files of very different
kinds sharing the same inode.  As the result, attempt to reopen those via
procfs succeeds and you get a descriptor you can't do anything with.

	Moreover, in case of sockets we set ->i_fop that will only be used
on such reopen attempts - and put a failing ->open() into it to make sure
those do not succeed.

	It would be simpler to put such ->open() into default ->i_fop and leave
it unchanged both for anon inode (as we do anyway) and for socket ones.  Result:
	* everything going through do_dentry_open() works as it used to
	* sock_no_open() kludge is gone
	* attempts to reopen anon-inode files fail as they really ought to
	* ditto for aio_private_file()
	* ditto for perfmon - this one actually tried to imitate sock_no_open()
trick, but failed to set ->i_fop, so in the current tree reopens succeed and
yield completely useless descriptor.  Intent clearly had been to fail with
-ENXIO on such reopens; now it actually does.
	* everything else that used alloc_file() keeps working - it has ->i_fop
set for its inodes anyway
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1f55a6ec
......@@ -2145,22 +2145,12 @@ pfm_close(struct inode *inode, struct file *filp)
return 0;
}
static int
pfm_no_open(struct inode *irrelevant, struct file *dontcare)
{
DPRINT(("pfm_no_open called\n"));
return -ENXIO;
}
static const struct file_operations pfm_file_ops = {
.llseek = no_llseek,
.read = pfm_read,
.write = pfm_write,
.poll = pfm_poll,
.unlocked_ioctl = pfm_ioctl,
.open = pfm_no_open, /* special open code to disallow open via /proc */
.fasync = pfm_fasync,
.release = pfm_close,
.flush = pfm_flush
......
......@@ -114,6 +114,11 @@ int proc_nr_inodes(struct ctl_table *table, int write,
}
#endif
static int no_open(struct inode *inode, struct file *file)
{
return -ENXIO;
}
/**
* inode_init_always - perform inode structure intialisation
* @sb: superblock inode belongs to
......@@ -125,7 +130,7 @@ int proc_nr_inodes(struct ctl_table *table, int write,
int inode_init_always(struct super_block *sb, struct inode *inode)
{
static const struct inode_operations empty_iops;
static const struct file_operations empty_fops;
static const struct file_operations no_open_fops = {.open = no_open};
struct address_space *const mapping = &inode->i_data;
inode->i_sb = sb;
......@@ -133,7 +138,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
inode->i_flags = 0;
atomic_set(&inode->i_count, 1);
inode->i_op = &empty_iops;
inode->i_fop = &empty_fops;
inode->i_fop = &no_open_fops;
inode->__i_nlink = 1;
inode->i_opflags = 0;
i_uid_write(inode, 0);
......@@ -1801,7 +1806,7 @@ void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev)
} else if (S_ISFIFO(mode))
inode->i_fop = &pipefifo_fops;
else if (S_ISSOCK(mode))
inode->i_fop = &bad_sock_fops;
; /* leave it no_open_fops */
else
printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for"
" inode %s:%lu\n", mode, inode->i_sb->s_id,
......
......@@ -2151,7 +2151,6 @@ static inline int sb_is_blkdev_sb(struct super_block *sb)
extern int sync_filesystem(struct super_block *);
extern const struct file_operations def_blk_fops;
extern const struct file_operations def_chr_fops;
extern const struct file_operations bad_sock_fops;
#ifdef CONFIG_BLOCK
extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
extern int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
......
......@@ -5,8 +5,6 @@
# Rewritten to use lists instead of if-statements.
#
obj-y := nonet.o
obj-$(CONFIG_NET) := socket.o core/
tmp-$(CONFIG_COMPAT) := compat.o
......
/*
* net/nonet.c
*
* Dummy functions to allow us to configure network support entirely
* out of the kernel.
*
* Distributed under the terms of the GNU GPL version 2.
* Copyright (c) Matthew Wilcox 2003
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
static int sock_no_open(struct inode *irrelevant, struct file *dontcare)
{
return -ENXIO;
}
const struct file_operations bad_sock_fops = {
.owner = THIS_MODULE,
.open = sock_no_open,
.llseek = noop_llseek,
};
......@@ -113,7 +113,6 @@ unsigned int sysctl_net_busy_read __read_mostly;
unsigned int sysctl_net_busy_poll __read_mostly;
#endif
static int sock_no_open(struct inode *irrelevant, struct file *dontcare);
static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos);
static ssize_t sock_aio_write(struct kiocb *iocb, const struct iovec *iov,
......@@ -151,7 +150,6 @@ static const struct file_operations socket_file_ops = {
.compat_ioctl = compat_sock_ioctl,
#endif
.mmap = sock_mmap,
.open = sock_no_open, /* special open code to disallow open via /proc */
.release = sock_close,
.fasync = sock_fasync,
.sendpage = sock_sendpage,
......@@ -559,23 +557,6 @@ static struct socket *sock_alloc(void)
return sock;
}
/*
* In theory you can't get an open on this inode, but /proc provides
* a back door. Remember to keep it shut otherwise you'll let the
* creepy crawlies in.
*/
static int sock_no_open(struct inode *irrelevant, struct file *dontcare)
{
return -ENXIO;
}
const struct file_operations bad_sock_fops = {
.owner = THIS_MODULE,
.open = sock_no_open,
.llseek = noop_llseek,
};
/**
* sock_release - close a socket
* @sock: socket to close
......
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