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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/socket.c
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>
Diffstat (limited to 'net/socket.c')
-rw-r--r--net/socket.c19
1 files changed, 0 insertions, 19 deletions
diff --git a/net/socket.c b/net/socket.c
index fe20c319a0b..850f6c38334 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