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authorAl Viro <viro@zeniv.linux.org.uk>2014-11-18 23:38:21 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2014-12-10 21:32:15 -0500
commitbd9b51e79cb0b8bc00a7e0076a4a8963ca4a797c (patch)
treebee3cc60bfbe1d7f837826bf495c0cf92747404b
parent1f55a6ec940fb45e3edaa52b6e9fc40cf8e18dcb (diff)
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: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--arch/ia64/kernel/perfmon.c10
-rw-r--r--fs/inode.c11
-rw-r--r--include/linux/fs.h1
-rw-r--r--net/Makefile2
-rw-r--r--net/nonet.c26
-rw-r--r--net/socket.c19
6 files changed, 8 insertions, 61 deletions
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 5845ffe..ac4528f 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2145,22 +2145,12 @@ doit:
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
diff --git a/fs/inode.c b/fs/inode.c
index 26753ba..5b83ef7 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -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,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2beddc2..b37beaf 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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);
diff --git a/net/Makefile b/net/Makefile
index 7ed1970..1f6c3e4 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -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
diff --git a/net/nonet.c b/net/nonet.c
deleted file mode 100644
index b1a73fd..0000000
--- a/net/nonet.c
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
- * 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,
-};
diff --git a/net/socket.c b/net/socket.c
index fe20c31..850f6c3 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -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