user/sven/linux.git/fs/devpts, branch v4.4.266

devpts: clean up interface to pty drivers

2016-08-16T07:30:49Z

commit 67245ff332064c01b760afa7a384ccda024bfd24 upstream. This gets rid of the horrible notion of having that struct inode *ptmx_inode be the linchpin of the interface between the pty code and devpts. By de-emphasizing the ptmx inode, a lot of things actually get cleaner, and we will have a much saner way forward. In particular, this will allow us to associate with any particular devpts instance at open-time, and not be artificially tied to one particular ptmx inode. The patch itself is actually fairly straightforward, and apart from some locking and return path cleanups it's pretty mechanical: - the interfaces that devpts exposes all take "struct pts_fs_info *" instead of "struct inode *ptmx_inode" now. NOTE! The "struct pts_fs_info" thing is a completely opaque structure as far as the pty driver is concerned: it's still declared entirely internally to devpts. So the pty code can't actually access it in any way, just pass it as a "cookie" to the devpts code. - the "look up the pts fs info" is now a single clear operation, that also does the reference count increment on the pts superblock. So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get ref" operation (devpts_get_ref(inode)), along with a "put ref" op (devpts_put_ref()). - the pty master "tty->driver_data" field now contains the pts_fs_info, not the ptmx inode. - because we don't care about the ptmx inode any more as some kind of base index, the ref counting can now drop the inode games - it just gets the ref on the superblock. - the pts_fs_info now has a back-pointer to the super_block. That's so that we can easily look up the information we actually need. Although quite often, the pts fs info was actually all we wanted, and not having to look it up based on some magical inode makes things more straightforward. In particular, now that "devpts_get_ref(inode)" operation should really be the *only* place we need to look up what devpts instance we're associated with, and we do it exactly once, at ptmx_open() time. The other side of this is that one ptmx node could now be associated with multiple different devpts instances - you could have a single /dev/ptmx node, and then have multiple mount namespaces with their own instances of devpts mounted on /dev/pts/. And that's all perfectly sane in a model where we just look up the pts instance at open time. This will eventually allow us to get rid of our odd single-vs-multiple pts instance model, but this patch in itself changes no semantics, only an internal binding model. Cc: Eric Biederman Cc: Peter Anvin Cc: Andy Lutomirski Cc: Al Viro Cc: Peter Hurley Cc: Serge Hallyn Cc: Willy Tarreau Cc: Aurelien Jarno Cc: Alan Cox Cc: Jann Horn Cc: Greg KH Cc: Jiri Slaby Cc: Florian Weimer Signed-off-by: Linus Torvalds Cc: Francesco Ruggeri Cc: "Herton R. Krzesinski" Signed-off-by: Greg Kroah-Hartman

pty: make sure super_block is still valid in final /dev/tty close

2016-02-25T20:01:14Z

commit 1f55c718c290616889c04946864a13ef30f64929 upstream. Considering current pty code and multiple devpts instances, it's possible to umount a devpts file system while a program still has /dev/tty opened pointing to a previosuly closed pty pair in that instance. In the case all ptmx and pts/N files are closed, umount can be done. If the program closes /dev/tty after umount is done, devpts_kill_index will use now an invalid super_block, which was already destroyed in the umount operation after running ->kill_sb. This is another "use after free" type of issue, but now related to the allocated super_block instance. To avoid the problem (warning at ida_remove and potential crashes) for this specific case, I added two functions in devpts which grabs additional references to the super_block, which pty code now uses so it makes sure the super block structure is still valid until pty shutdown is done. I also moved the additional inode references to the same functions, which also covered similar case with inode being freed before /dev/tty final close/shutdown. Signed-off-by: Herton R. Krzesinski Reviewed-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

devpts: if initialization failed, don't crash when opening /dev/ptmx

2015-07-01T02:44:58Z

If devpts failed to initialize, it would store an ERR_PTR in the global devpts_mnt. A subsequent open of /dev/ptmx would call devpts_new_index, which would dereference devpts_mnt and crash. Avoid storing invalid values in devpts_mnt; leave it NULL instead. Make both devpts_new_index and devpts_pty_new fail gracefully with ENODEV in that case, which then becomes the return value to the userspace open call on /dev/ptmx. [akpm@linux-foundation.org: remove unneeded static] Signed-off-by: Josh Triplett Reported-by: Fengguang Wu Reviewed-by: Peter Hurley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

VFS: normal filesystems (and lustre): d_inode() annotations

2015-04-15T19:06:57Z

that's the bulk of filesystem drivers dealing with inodes of their own Signed-off-by: David Howells Signed-off-by: Al Viro

fs/devpts/inode.c: convert printk to pr_foo()

2014-06-06T23:08:14Z

Also convert spaces to tabs (checkpatch warnings) if (!dentry) KERN_NOTICE converted to pr_err (like if (!inode) error process) [akpm@linux-foundation.org: use KBUILD_MODNAME, per Joe] Signed-off-by: Fabian Frederick Cc: Joe Perches Cc: "Theodore Ts'o" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs: push sync_filesystem() down to the file system's remount_fs()

2014-03-13T14:14:33Z

Previously, the no-op "mount -o mount /dev/xxx" operation when the file system is already mounted read-write causes an implied, unconditional syncfs(). This seems pretty stupid, and it's certainly documented or guaraunteed to do this, nor is it particularly useful, except in the case where the file system was mounted rw and is getting remounted read-only. However, it's possible that there might be some file systems that are actually depending on this behavior. In most file systems, it's probably fine to only call sync_filesystem() when transitioning from read-write to read-only, and there are some file systems where this is not needed at all (for example, for a pseudo-filesystem or something like romfs). Signed-off-by: "Theodore Ts'o" Cc: linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig Cc: Artem Bityutskiy Cc: Adrian Hunter Cc: Evgeniy Dushistov Cc: Jan Kara Cc: OGAWA Hirofumi Cc: Anders Larsen Cc: Phillip Lougher Cc: Kees Cook Cc: Mikulas Patocka Cc: Petr Vandrovec Cc: xfs@oss.sgi.com Cc: linux-btrfs@vger.kernel.org Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: codalist@coda.cs.cmu.edu Cc: linux-ext4@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: fuse-devel@lists.sourceforge.net Cc: cluster-devel@redhat.com Cc: linux-mtd@lists.infradead.org Cc: jfs-discussion@lists.sourceforge.net Cc: linux-nfs@vger.kernel.org Cc: linux-nilfs@vger.kernel.org Cc: linux-ntfs-dev@lists.sourceforge.net Cc: ocfs2-devel@oss.oracle.com Cc: reiserfs-devel@vger.kernel.org

devpts: plug the memory leak in kill_sb

2013-11-13T03:09:36Z

When devpts is unmounted, there may be a no-longer-used IDR tree hanging off the superblock we are about to kill. This needs to be cleaned up before destroying the SB. The leak is usually not a big deal because unmounting devpts is typically done when shutting down the whole machine. However, shutting down an LXC container instead of a physical machine exposes the problem (the garbage is detectable with kmemleak). Signed-off-by: Ilija Hadzic Cc: Sukadev Bhattiprolu Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

userns: Allow the userns root to mount of devpts

2013-01-27T06:22:21Z

- The context in which devpts is mounted has no effect on the creation of ptys as the /dev/ptmx interface has been used by unprivileged users for many years. - Only support unprivileged mounts in combination with the newinstance option to ensure that mounting of /dev/pts in a user namespace will not allow the options of an existing mount of devpts to be modified. - Create /dev/pts/ptmx as the root user in the user namespace that mounts devpts so that it's permissions to be changed. Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman"

TTY: devpts, document devpts inode operations

2012-10-22T23:50:13Z

Add kernel-doc texts for some devpts functions, i.e. document them. Signed-off-by: Jiri Slaby Acked-by: Alan Cox Signed-off-by: Greg Kroah-Hartman

TTY: devpts, do not set driver_data

2012-10-22T23:50:13Z

The goal is to stop setting and using tty->driver_data in devpts code. It should be used solely by the driver's code, pty in this case. Now driver_data are managed only in the pty driver. devpts_pty_new is switched to accept what we used to dig out of tty_struct, i.e. device node number and index. This also removes a note about driver_data being set outside of the driver. Signed-off-by: Jiri Slaby Acked-by: Alan Cox Signed-off-by: Greg Kroah-Hartman