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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 /net/nonet.c
parent1f55a6ec940fb45e3edaa52b6e9fc40cf8e18dcb (diff)
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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>
Diffstat (limited to 'net/nonet.c')
-rw-r--r--net/nonet.c26
1 files changed, 0 insertions, 26 deletions
diff --git a/net/nonet.c b/net/nonet.c
deleted file mode 100644
index b1a73fda9c12..000000000000
--- 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,
-};