linux.git/fs/hostfs/hostfs_user.c, branch for-next Linux kernel source tree hostfs: fix dev_t handling 2024-07-03T10:23:50+00:00 Johannes Berg johannes.berg@intel.com 2024-07-02T07:24:41+00:00 267ed02c2121b75e0eaaa338240453b576039e4a dev_t is a kernel type and may have different definitions in kernel and userspace. On 32-bit x86 this currently makes the stat structure being 4 bytes longer in the user code, causing stack corruption. However, this is (potentially) not the only problem, since dev_t is a different type on user/kernel side, so we don't know that the major/minor encoding isn't also different. Decode/encode it instead to address both problems. Cc: stable@vger.kernel.org Fixes: 74ce793bcbde ("hostfs: Fix ephemeral inodes") Link: https://patch.msgid.link/20240702092440.acc960585dd5.Id0767e12f562a69c6cd3c3262dc3d765db350cf6@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> 
dev_t is a kernel type and may have different definitions
in kernel and userspace. On 32-bit x86 this currently makes
the stat structure being 4 bytes longer in the user code,
causing stack corruption.

However, this is (potentially) not the only problem, since
dev_t is a different type on user/kernel side, so we don't
know that the major/minor encoding isn't also different.
Decode/encode it instead to address both problems.

Cc: stable@vger.kernel.org
Fixes: 74ce793bcbde ("hostfs: Fix ephemeral inodes")
Link: https://patch.msgid.link/20240702092440.acc960585dd5.Id0767e12f562a69c6cd3c3262dc3d765db350cf6@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
hostfs: Fix ephemeral inodes 2023-06-12T19:26:19+00:00 Mickaël Salaün mic@digikod.net 2023-06-12T19:14:25+00:00 74ce793bcbde5cef0f82d6ccb3c47cb651295a9a hostfs creates a new inode for each opened or created file, which created useless inode allocations and forbade identifying a host file with a kernel inode. Fix this uncommon filesystem behavior by tying kernel inodes to host file's inode and device IDs. Even if the host filesystem inodes may be recycled, this cannot happen while a file referencing it is opened, which is the case with hostfs. It should be noted that hostfs inode IDs may not be unique for the same hostfs superblock because multiple host's (backed) superblocks may be used. Delete inodes when dropping them to force backed host's file descriptors closing. This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes Landlock fully supported by UML. This is very useful for testing changes. These changes also factor out and simplify some helpers thanks to the new hostfs_inode_update() and the hostfs_iget() revamp: read_name(), hostfs_create(), hostfs_lookup(), hostfs_mknod(), and hostfs_fill_sb_common(). A following commit with new Landlock tests check this new hostfs inode consistency. Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Acked-by: Richard Weinberger <richard@nod.at> Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net> 
hostfs creates a new inode for each opened or created file, which
created useless inode allocations and forbade identifying a host file
with a kernel inode.

Fix this uncommon filesystem behavior by tying kernel inodes to host
file's inode and device IDs.  Even if the host filesystem inodes may be
recycled, this cannot happen while a file referencing it is opened,
which is the case with hostfs.  It should be noted that hostfs inode IDs
may not be unique for the same hostfs superblock because multiple host's
(backed) superblocks may be used.

Delete inodes when dropping them to force backed host's file descriptors
closing.

This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes
Landlock fully supported by UML.  This is very useful for testing
changes.

These changes also factor out and simplify some helpers thanks to the
new hostfs_inode_update() and the hostfs_iget() revamp: read_name(),
hostfs_create(), hostfs_lookup(), hostfs_mknod(), and
hostfs_fill_sb_common().

A following commit with new Landlock tests check this new hostfs inode
consistency.

Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
hostfs: rename do_rmdir() to hostfs_do_rmdir() 2018-04-02T18:15:53+00:00 Dominik Brodowski linux@dominikbrodowski.net 2018-03-11T10:34:48+00:00 6380161ce9d08320d2e09f0fc64b778da433b451 do_rmdir() is used in the VFS layer at fs/namei.c, so use a different name in hostfs. Cc: Jeff Dike <jdike@addtoit.com> Cc: user-mode-linux-devel@lists.sourceforge.net Acked-by: Richard Weinberger <richard@nod.at> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> 
do_rmdir() is used in the VFS layer at fs/namei.c, so use a different
name in hostfs.

Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
um: hostfs: Reduce number of syscalls in readdir 2015-04-13T19:01:07+00:00 Richard Weinberger richard@nod.at 2015-03-24T14:47:38+00:00 0c9bd6365d0b278728359843b8303047ddedb831 Currently hostfs issues every time a seekdir(), in fact it has to do this only upon the first call. Also telldir() can be omitted as we can obtain the directory offset from readdir(). Signed-off-by: Richard Weinberger <richard@nod.at> 
Currently hostfs issues every time a seekdir(), in fact
it has to do this only upon the first call.
Also telldir() can be omitted as we can obtain the directory
offset from readdir().

Signed-off-by: Richard Weinberger <richard@nod.at>
hostfs: No need to box and later unbox the file mode 2015-03-26T22:27:53+00:00 Richard Weinberger richard@nod.at 2015-03-04T22:44:54+00:00 b98b91029cf8a6defc6311d4018c44f3b05fbec7 There is really no point in having a function with 10 arguments. Reported-by: Daniel Walter <d.walter@0x90.at> Signed-off-by: Richard Weinberger <richard@nod.at> 
There is really no point in having a function with 10
arguments.

Reported-by: Daniel Walter <d.walter@0x90.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
hostfs: support rename flags 2014-08-07T18:40:09+00:00 Miklos Szeredi mszeredi@suse.cz 2014-07-23T13:15:35+00:00 9a423bb6e3577bb372942edfb5d9d26632741d43 Support RENAME_NOREPLACE and RENAME_EXCHANGE flags on hostfs if the underlying filesystem supports it. Since renameat2(2) is not yet in any libc, use syscall(2) to invoke the renameat2 syscall. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> 
Support RENAME_NOREPLACE and RENAME_EXCHANGE flags on hostfs if the
underlying filesystem supports it.

Since renameat2(2) is not yet in any libc, use syscall(2) to invoke the
renameat2 syscall.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
um: get rid of pointless include "..." where include <...> will do 2012-10-09T20:28:45+00:00 Al Viro viro@ZenIV.linux.org.uk 2012-10-08T02:27:32+00:00 37185b33240870719b6b5913a46e6a441f1ae96f Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at> 
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
uml/hostfs: Propagate dirent.d_type to filldir() 2012-03-24T23:29:52+00:00 Geert Uytterhoeven geert@linux-m68k.org 2012-01-27T18:14:58+00:00 3ee6bd8e8dc0c58b9ba5bab7ef8a7a131da346eb Currently the (optional) d_type member in struct dirent is always DT_UNKNOWN on hostfs, which may confuse buggy software using readdir(). Make sure to propagate its value from the underlying filesystem if it's available there. Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Signed-off-by: Richard Weinberger <richard@nod.at> 
Currently the (optional) d_type member in struct dirent is always
DT_UNKNOWN on hostfs, which may confuse buggy software using readdir().
Make sure to propagate its value from the underlying filesystem if it's
available there.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
um: kill useless include of user.h 2011-11-02T13:15:13+00:00 Al Viro viro@ftp.linux.org.uk 2011-08-18T19:08:59+00:00 548fd1e8dba90bea674f5969d73498959d83924b everything in USER_OBJ gets it via -include user.h Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at> 
everything in USER_OBJ gets it via -include user.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
hostfs: code cleanups 2010-10-26T23:52:12+00:00 Richard Weinberger richard@nod.at 2010-10-26T21:22:20+00:00 c5c6dd4e2dce3cb4d705d97183bc42b4e33e2606 Some code cleanups for hostfs. Signed-off-by: Richard Weinberger <richard@nod.at> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Some code cleanups for hostfs.

Signed-off-by: Richard Weinberger <richard@nod.at>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>