From bd9b51e79cb0b8bc00a7e0076a4a8963ca4a797c Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 18 Nov 2014 23:38:21 -0500 Subject: 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 --- include/linux/fs.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/fs.h') diff --git a/include/linux/fs.h b/include/linux/fs.h index 2beddc284bc2..b37beaf7a3a5 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); -- cgit v1.2.3